Improved nanocomposite compositions and methods for making and using same

【0001】

The present invention generally relates to modified nanocomposite compositions and methods for making and using them. More specifically, the present invention relates to nanocomposites that exhibit improved physical properties. The present invention also relates to, for example, the use of improved nanocomposite compositions as coatings, sealants, caulking materials, adhesives, and adhesives for plastics.

【0002】

One way to improve polymer properties is by adding a clay material to the polymer to form a composite material. However, incorporating clay into the polymer cannot provide the desired improvement in the physical properties, especially the mechanical properties of the polymer. This may be due to the lack of affinity between the clay and the polymer, for example, at the interface or boundary between the clay and the polymer in the material. In this regard, the affinity of the clay with the polymer can improve the physical properties of the resulting nanocomposite by uniformly dispersing the clay material in the polymer. When uniformly dispersed, the relatively large surface area of the clay can provide additional interfaces between the clay and the polymer, which subsequently improve the physical properties by reducing the mobility of the polymer chains at these interfaces. sell. In contrast, the lack of affinity between the clay and the polymer can have a detrimental effect on the strength of the composition by having pockets of concentrated clay in the polymer rather than being uniformly dispersed. The affinity between clays and polymers is inherently related to the fact that clays are generally compatible, whereas polymers such as the polymers used in the aforementioned applications are generally hydrophobic.

【0003】

Clay minerals are generally composed of hydrated aluminum silicate, which is finely crushed and has plate-like properties. The crystalline structure of a typical clay mineral is AlO (OH).₂SiO bonded to the octahedral layer₄It is a multi-layer structure composed of a combination of tetrahedral layers. As used herein, the phrase "gallery" refers to the interlayer space of layered clay minerals. As used herein, the phrase "d-spacing" or "basic spacing" defines the total thickness of a single layer and the thickness of layers or galleries that are repeating units of multi-layer minerals. Depending on the clay mineral, the gallery may contain water and / or other components such as potassium, sodium, or calcium cations. Clay minerals vary based on their component layers and the combination of cations. Si in a tetrahedral network⁴⁺Al that replaces the ion³⁺Or Fe³⁺, Or Al that replaces other cations in the octahedral network³⁺, Mg²⁺Or Fe²⁺Cation isomorphic substitutions of clay minerals, such as, generally occur and can impart an effective negative charge in the clay structure. Naturally occurring elements within the clay gallery, such as water molecules or sodium or potassium cations, are attached to the surface of the clay layer by this effective negative charge.

【0004】

A nanocomposite is a composition having one or more dimensions in which at least one of its components, eg, length, width or thickness, is in the nanometer size range. As used herein, the phrase "nanocomposite" refers to the state of matter in which a polymer molecule is present in a clay layer that is at least partially exfoliated. Recently, nanocomposites containing layered clay materials such as montmorillonite with a silicate layer about 1 nanometer thick dispersed in a polymeric matrix have been developed as a means of improving the physical properties of polymers. In order to effectively improve the physical or mechanical properties, the clay is generally homogeneous in the polymer to further promote the interface between the clay and the polymer and enhance the clay's affinity for the polymer at these interfaces. Is distributed to. In addition, if the clay is uniformly dispersed in the polymer, a small amount of clay material can be added to the nanocomposite composition without adversely affecting the physical properties of the nanocomposite.

【0005】

Polymer / clay nanocomposites can be characterized as one of several common types: inserted nanocomposites, exfoliated nanocomposites, or combinations thereof. As used herein, the phrase "insertion nanocomposite" refers to a nanocomposite composed of constant insertion of polymers within clay layers. As used herein, the phrase "peeling nanocomposite" refers to a nanocomposite in which a 1 nm thick layer of clay is dispersed in a matrix that forms a composite structure on a trace scale. The latter type of composite, or exfoliated nanocomposite, maximizes the polymer / clay interaction, thereby making the entire surface of the clay layer available for the polymer. This modification can lead to the most dramatic changes in the mechanical and physical properties of the resulting polymer. In contrast, as used herein, the phrase "conventional composite" refers to a composite in which clay acts as a conventional filler and is not dispersed on a nanoscale. These composites generally do not enjoy the improvements in mechanical and physical properties found in exfoliated nanocomposites. In certain embodiments of the invention, some portion of the clay in the polymer / clay nanocomposite may be present as a larger structure than the stripped or inserted composite.

【0006】

The interlayer surface chemistry of the clay has been modified to reduce the hydrophilicity of the silicate layer in order to further promote the affinity between the clay and the polymer at the interface and provide a uniform dispersion of the clay within the polymer. sell. One way to change the interfacial chemistry of the clay is to use a surfactant or modifier such as silane to prepare the clay dispersion prior to incorporation into the polymer. For example, surfactants are generally molecules that exhibit hydrophilic function (affinity with polar media such as water or clay) and organic affinity function (affinity with organic molecules such as oil or polymer). Can include. The use of a surfactant disperses the clay in the polymer. As used herein, the phrase "hydrophobically modified clay" may indicate its surface chemistry that is improved through the use of agents such as surfactants, silanes, or other modifiers. Represents clay. As used herein, the term "non-modified clay" refers to a clay that has not been hydrophobically modified by a modifier or is used in its natural state.

【0007】

Typical modifiers used to reduce hydrophilicity in clay are, but are not limited to, amino acids, alkylammonium ions, silanes, aminomethylstyrene, or living-free radical polymerization initiators (LFRP). Can be mentioned. Further unrestricted examples of other suitable agents for nanocomposite synthesis are described by M. Ogawa et al., "Preparation of inorganic through the insertion of organic ammonium ions into laminated silicates. -organic nanocomposites through intercalation of organoammonium ions into layered silicates) ", Bull.Chem.Soc.Jpn., Vol. 70, pp. 2593-2619 (1997).

【0008】

Amino acid surfactants are basic amino groups (-NH)₂) And an acidic carboxyl group (-COOH). Upon introduction into an acidic medium, the protons are transferred from the -COOH group to the intermolecular-NH.₂Can be migrated to the basis. Cation exchange is formed-NH³⁺Naturally occurring cations (ie, Na) between the functional group and the clay layer⁺, K⁺Etc.) and seems to occur. This is -NH³⁺Functional groups result in "sandwiched" insertions between the individual layers that replace the naturally occurring cations. As used herein, the phrase "insert" refers to the incorporation of foreign molecules, atoms, or ions between layers of clay material. As a result of this insertion state, the clay becomes hydrophobic. Amino acid surfactants are commonly used in the production of polyamide 6-clay hybrids because their acid functional groups can polymerize with the ε-caprolactam inserted between the layers. As a result, inter-gallery polymerization delaminates the clay in the polymer matrix, thereby forming a nanocomposite.

【0009】

Alkaline ammonium ion surfactants such as onium salts are commonly used to prepare clay dispersions for nanocomposite materials. The basic formula for a typical alkylammonium ion is CH₃-(CH₂)_n-NH³⁺(In the formula, n is 1 to 18). It is believed that the alkylammonium ions can also be easily exchanged with the naturally occurring cations present between the clay plates that give rise to the inserted state. In addition, alkylammonium ions can increase the d-interval between clay layers, reducing the surface energy of the clay, thereby inserting various polar organic species between the clay layers. It is thought that it can be done.

【0010】

Silanes can also be used in the synthesis of unsaturated polyester-clay nanocomposites. Silane is the formula R-SiX₃(In the formula, R is an organic functional group bonded to silicon by a hydrolyzable stable means, and X is a hydrolyzable group that can be converted to a silanol group by hydrolysis). Family. Silanes are believed to interact primarily with clay-like inorganic surfaces that have hydroxy groups attached to silicon or aluminum, thereby forming bonds with the inorganic surface.

【0011】

Hydrophobically modified clays have often been used in the production of nanocomposite materials. Article by Xavier Kornmann, "Synthesis and characterization of Thermoset-Clay Nanocomposites) (here referred to as Kornmann ) synthesizes nanocomposites with hydrophobically modified clay using in-situ polymerization, melt insertion, or solution-based polymerization methods. Some examples are provided. In that case, the method is to swell the hydrophobically modified clay, referred to in the article as "organic clay", in the monomer, and then add a hardener or raise the temperature. The polymerization reaction is initiated to form the nanocomposite. It is considered that the polymerization reaction leads to the separation of the clay. In the melt insertion method, the molten thermoplastic resin is mixed with the hydrophobically modified clay and then annealed at a temperature above the glass transition temperature of the polymer to form a nanocomposite. Finally, in the solution polymerization method, the hydrophobically modified clay was first swollen in a solvent such as toluene or N, N-dimethylformamide. The polymer is then dissolved in the solvent it inserts between the clay layers. The solvent is then removed from the nanocomposite produced by evaporation.

【0012】

Kormann also considers preparing nanocomposites using solution polymerization in which the polar solvent contains unmodified clay, which is deionized water. However, Kormann has not considered adding multivalent cations to the aqueous system.

【0013】

There are significant processing difficulties faced when preparing nanocomposites in aqueous dispersions with hydrophobically modified clays. In this regard, U.S. Pat. No. 5,883,173 (Elspass), published to Elspass et al., By polymerizing or mixing latex polymers in the presence of a dispersion of laminated (clay) materials. It describes how to prepare a single-stage rubbery nanocomposite. In the provided aqueous latex method, Elspass disperses the laminate material in water with a surfactant such as an omium salt to separate the layers, then polymerizes the monomers for approximately 46 hours to layer the polymer. Disclose that it is inserted between.

【0014】

The process of adding detergent to strip the layers is time consuming (eg, Elspass mixes clay, detergent, and monomer slurry for 20 hours before polymerizing for an additional 26 hours. Disclose that). In addition, the stripped clay dispersion is very viscous, which tends to cause processing problems. The method of the present invention does not require the clay to be exfoliated with the added surfactant and is therefore faster and less viscous than that disclosed by Elspass.

【0015】

Huang et al., "Synthesis and characterization of PMMA Nanocomposites by Suspension and Emulsion Polymerization", Amer. Chem.S. (2000) ("Huang") Describes the use of hydrophobically modified clays to form PMMA nanocomposites via emulsion polymerization. During the emulsion polymerization, the surfactant was used as an emulsifier and non-modified clay was added after the polymerization. The resulting nanocomposite Tg is too high to be useful for many of the applications disclosed herein. In addition, nanocomposites are formed by "melt pressurization" processing rather than aqueous systems.

【0016】

Another drawback of using hydrophobically modified clays is that the surfactants used to modify the clays, especially anionic surfactants, can destabilize the polymer latex emulsion. There is. Many of the surfactants used to disperse clay, such as onium salts, are also emulsifiers. In some cases, extreme difficulties may be faced in preparing stable polymeric latex in the presence of such onium salt modified clays. In the presence of such onium salts, large amounts of emulsifiers are generally required to keep such emulsions stable. A large amount of emulsifier can reduce the properties of the polymer in its end use (eg, less water resistance). In addition, large amounts of emulsifier can have a destructive effect on the formation of polymer latex particles. Non-uniform polymer latex particle formation can lead to variations in emulsion droplet size that result in non-uniform polymer particle size. Large amounts of emulsifier can also lead to the formation of "secondary particles" that can widen the particle size distribution. Similarly, often the shear instability of emulsions, variability in polymer molecular weight (leading to variability in polymer processing and properties), and decomposition of properties when dried into powders (eg, dust resulting from the presence of small polymer particles). ) There is a problem related to a wide range of particle size distributions.

【0017】

The problems mentioned above exacerbate the formation of latex polymer particles using the emulsion polymerization process. More specifically, the problems described above exacerbate the formation of multi-stage latex polymer particles. Examples of multi-stage polymer processing that are susceptible to these problems include the production of "core-shell" polymer particles, gradual monomer addition, or the use of "gradual addition" processes.

【0018】

Yet another method of altering the interlayer surface chemistry of the clay material and eventually improving the clay's affinity for the polymer involves the production of ion-dipoles that promote clay detachment. Article "Nanocomposites Produced Utilizing a Novel Ion-Dipole Clay Surface Modification) , GW Beall and SJT sipursky, Chem.Technol.Polym.Addit. (1999), Chapter 15, pp. 266-280, are partially negative for replacing water molecules within the gallery of sodium montmorillonite clay. Teaching the use of organic molecules or polymers carrying charged functional groups. The negative charges of these functional groups appear to form an ion-dipole bond with the exchangeable sodium ions on the surface of the clay layer. The presence of these functional groups in the clay gallery can assist in the exfoliation of clay minerals. Instead, the clay remains inserted with these functional groups and then exfoliated so that the functional groups can participate in the polymerization reaction. However, for specific purposes, it may not be desirable to involve these functional groups in the polymerization and leave them in the structure of the nanocomposite.

【0019】

U.S. Pat. No. 5,998,528 (Tsipursky) issued to Tsipursky et al. Adds divalent or trivalent cations during or after the insertion of clay minerals to increase the viscosity of the clay slurry. Disclose what to do. The clay slurry is mixed with one or more polymers, especially water-soluble polymers, and organic solvents to produce viscous carrier compositions. As specified above, viscous slurries such as the viscous carrier composition disclosed in Tsipursky can lead to processing problems in forming nanocomposite compositions. In addition, introducing a solvent into the nanocomposite composition may be undesirable.

【0020】

The present invention does not require the use of additional polymers, solvents, or other means to improve the affinity of the clay with the polymer at its interface and to improve the overall mechanical properties of the nanocomposite. .. Therefore, the mechanical properties of the nanocomposite facilitate ion exchange of the first cations in the clay contained therein and increase the affinity between the polymer and the clay at their interface in the nanocomposite composition. It is surprising and unexpected that it can be improved through the addition of a promoting second cation, typically a polyvalent cation.

【0021】

The present invention is in part directed to modified composite compositions and methods for producing them. In particular, one embodiment comprises supplying at least one first ethylenically unsaturated monomer, at least partially stripped aqueous clay, and optionally at least one second ethylenically unsaturated monomer. A step of supplying an aqueous clay dispersion, a step in which the clay has a first exchangeable monomer, a step of adding a second monomer to the aqueous clay dispersion, and a second step. The step of exchanging at least a part of the cations with at least a part of the first cations to form a modified aqueous clay dispersion, the first ethylenically unsaturated monomer and the modified aqueous. The aqueous nanocomplex, wherein the clay dispersion is mixed and at least a portion of the first or second monomer is polymerized so that at least one first or second ethylenically unsaturated monomer comprises a polar monomer. A method for producing an aqueous nanocomposite dispersion liquid, which comprises a step of forming a material dispersion liquid, is provided. In certain embodiments, the first ethylenically unsaturated monomer and the second ethylenically unsaturated monomer are the same monomer. In other embodiments, the first and second ethylenically unsaturated monomers are different monomers.

【0022】

These and other aspects of the invention will become even more apparent from the detailed description below.

【0023】

The present invention is directed to a method of improving the physical properties of a nanocomposite composition by improving the affinity between the polymer contained therein and clay. The nanocomposite compositions of the present invention may advantageously exhibit improved balance properties as compared to nanocomposite compositions prepared by prior art methods. In particular, the nanocomposite compositions of the present invention may preferably exhibit improved strength properties without undergoing additional processing steps or adding additional clays, polymers, or solvents to the composition. .. The present invention improves a variety of nanocomposite compositions produced by emulsification, suspension, solvent, agglomeration, or other polymerization methods through the addition of a second, typically polyvalent cation. It also provides a method. The affinity of the polymer for clay in the nanocomposite composition can be improved regardless of whether a second cation is added before or after the polymerization of the system.

【0024】

The addition of a second cation, typically a metal ion, to the nanocomposite composition containing the polymer and the first cation, especially clay containing naturally occurring cations, is the addition of the polymer and clay at their interface. It was found here that the affinity with can be desirablely enhanced. The enhanced affinity of the polymer and clay yields nanocomposites that exhibit improved physical properties such as enhanced tensile strength. The present invention is considered for emulsion-based polymers or aqueous nanocomposite dispersions, but the methods of the invention are suitable for a variety of polymerization methods, such as, but not limited to, solution or suspension polymerization techniques. It turned out. In fact, the present invention allows any polymerization in which a partially or completely negatively charged monomer, oligomer, or stabilizer is attached to the positive charge of the second cation and can be involved in the polymerization. Suitable for technology.

【0025】

In certain embodiments of the invention, nanocomposites are prepared via emulsion-based polymerization techniques. For example, in connection with the preparation of an aqueous nanocomposite dispersion, two separate aqueous reaction mixtures are first prepared, followed by multi-stage emulsion polymerization of the monomers in the reaction mixture. As for the use of the present invention, multi-stage polymerization is mainly investigated as two stages, but it can be seen that the polymerization of monomers having more than two stages is further intended. As used herein, the terms "step," "multistage," and "coreshell" refer to, for example, U.S. Pat. Nos. 3,793,402, which disclose various methods of achieving "step" and "multistage" polymers. It is intended to include its broadest possible meaning, such as the meaning transmitted in 3,971,835, 5,534,594, and 5,599,854. The first aqueous reaction mixture generally contains a monomer mixture, whereas the second aqueous reaction mixture contains an aqueous clay dispersion and optionally a monomer mixture. However, in certain embodiments, the first aqueous reaction mixture may also include an aqueous clay dispersion. The phrase "aqueous nanocomposite dispersion" refers to clay and polymer nanocomposites that further contain an aqueous or aqueous phase. In certain embodiments, the monomer mixture in the first and / or second aqueous reaction mixture can be emulsified. In these embodiments, the monomer mixture in the first and second aqueous reaction mixtures may contain the same monomer or may contain different monomers. In one embodiment of the invention, the weight percentage of clay relative to the total amount of monomers in the aqueous nanocomposite dispersion is 0.05% to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%. Even more preferably, it can be in the range of 0.5% to 5%.

【0026】

Aqueous nanocomposite dispersions contain polymerization units derived from at least one type of ethylenically unsaturated monomer. As used herein, the term "unit derived from" refers to a polymer molecule in which a polymer is synthesized by a known polymerization technique that includes its constituent monomer "unit derived from". Preferably, an ethylenically unsaturated monomer is selected that indicates that the polymerization unit in the aqueous nanocomposite dispersion is water insoluble, i.e. poorly or insoluble in water. "Water insoluble" means having a water solubility of 150 mmol / liter or less of the monomer at 25 ° C to 50 ° C.

【0027】

Preparation of the monomer mixture generally involves vigorous mixing of water, and optionally an emulsifier, with at least one ethylenically unsaturated monomer. In other embodiments of the invention, the monomer can be added "as is", i.e. without water. The amount of monomer, water, and emulsifier in the monomer mixture can vary, for example, depending on the particular monomer and / or emulsifier selected, the intended end use, polymerization technique, and the like. In certain embodiments, the amount of monomer in the monomer mixture is preferably in the range of 25-100, preferably 40-90, and even more preferably 60-80% by weight. When aqueous, the amount of water in the monomer mixture is 0.1-75, more preferably 10-60, even more preferably 20 relative to the total weight of the emulsified monomer mixture (eg, monomer, emulsifier, and water). It is in the amount of ~ 40% by weight. When added, the amount of emulsifier in the monomer mixture is preferably in the range of 0.01-10, preferably 0.05-2, and even more preferably 0.1-1% by weight. In certain embodiments where a clay that has been hydrophobically modified or treated with a detergent is used, the amount of emulsifier in the system is typically such that the detergent is also an emulsifier. Can be adjusted to a lower amount.

【0028】

Monomers that can be polymerized include those listed in The Polymer Handbook, 3rd Edition, Brandrup and Immergut, Wiley Interscience, Chapter 2, (1989). Included are any ethylenically unsaturated monomers commonly known in the industry. Suitable ethylenically unsaturated monomers include, for example, C₁~ C₁₈Alkyl (meth) acrylate monomers (eg, methyl-, ethyl-, propyl-, n-butyl-, sec-butyl, tert-butyl, pentyl-, isobornyl-, hexyl-, heptyl-, n-octyl-, 2- Ethylhexyl-, decyl-, undecyl-, dodecyl-, lauryl, cetyl, and stearyl- (meth) acrylate, etc.); Vinyl aromatic monomers (eg, styrene, alpha-methylstyrene, para-methylstyrene, chlorostyrene, vinyltoluene) , Dibromostyrene, tribromostyrene, vinylnaphthalene, isopropenylnaphthalene, divinylbenzene, etc.); Vinyl esters (eg, vinyl acetate; vinyl versatate, etc.); Vinyl unsaturated carboxylic acid monomers (eg, methacrylate, acrylic acid, malein, etc.) Acids, itaconic acids); nitrogen-containing vinyl unsaturated monomers (eg, acrylonitrile, methacrylonitrile, and C)₁~ C₁₈Alkyl (meth) acrylamide, etc.); Diene (eg, butadiene and isoprene); ethylene, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and the like. As used herein, the phrase "alkyl (meth) acrylate" refers to esters of both alkyl acrylates and alkyl methacrylates.

【0029】

It is preferred to use monomers selected from the class of alkyl (meth) acrylates for the purpose of preparing nanocomposite compositions that exhibit desirable resistance to weathering. Ethylene unsaturated monomers are used for the purpose of providing an inexpensive, commercially available aqueous nanocomposite dispersion.₁~ C₁₈Alkyl methacrylate, C₁~ C₁₈It is preferably selected from the group consisting of alkyl acrylates, acrylic acids, methacrylic acids, butadiene, vinyl aromatic monomers and the like. For the purpose of using aqueous nanocomposite dispersions for preparing dressings and adhesives, C₁~ C₁₈Alkyl (meth) acrylate monomers; acrylic acid; methacrylic acid; itaconic acid; vinyl acetate; vinyl versatate; vinyl aromatic monomers and the like are preferably used. Due to their relatively low cost and commercially available availability, n-butyl acrylate, ethyl acrylate, butyl methacrylate, methyl methacrylate, styrene, butadiene, for the purpose of providing aqueous nanocomposite dispersions for a variety of applications. , Acrylic acid, and methacrylic acid monomers would be even more preferred.

【0030】

If it is desirable to covalently crosslink the polymer and / or graft-bonded multi-stage polymer (eg, to prepare core-shell two-stage polymer particles), a cross-linking agent and / or graft linker is also included in the monomer mixture. sell. As used herein, the phrase "crosslinking agent" refers to a polyfunctional monomer capable of forming two or more covalent bonds between polymer molecules of the same type. As used herein, the phrase "graft linker" refers to a polyfunctional monomer capable of forming two or more covalent bonds between one type of polymer molecule and another type of polymer molecule. Suitable crosslinkers or graft linkers include, for example, divinylbenzene, butylene glycol dimethacrylate; ethylene glycol di (meth) acrylate, butylene glycol diacrylate, oligoethylene glycol diacrylate, oligoethylene glycol dimethacrylate, trimethylol-propanedi. Alcan polyols such as acrylates, trimethylolpropane dimethacrylates, trimethylol-propanetriacrylates (TMPTA) or trimethylolpropane trimethacrylates-polyacrylates or alkane polyols-polymethacrylates, and allyl acrylates, diallyl malates, and especially. Examples thereof include unsaturated carboxylic acid allyl esters such as allyl methacrylate.

【0031】

In certain preferred embodiments, the at least one monomer in the monomer mixture is a polar monomer. As used herein, the phrase "polar monomer" refers to a monomer that is partially or completely negatively charged. Examples of these monomers include, but are not limited to, monomers containing a carboxylic acid, phosphoric acid, or sulfuric acid functional group. Yet another example of a polar monomer is a monomer containing hydroxyl groups, esters, ethers, aldehydes and ketone functional groups. Preferably, the polar monomer is a carboxylic acid-containing monomer. As used herein, the phrase "acid-containing monomer" is such as one or more acid functional groups, or anhydrides such as methacrylic anhydride, maleic anhydride, or itaconic anhydride. Refers to any ethylenically unsaturated monomer containing a functional group capable of forming an acid. Examples of acid-containing monomers include carboxylic acid-bearing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and fumaric acid; acrylic oxypropionic acid and (meth) acrylic oxypropionic acid; styrene. Sulfonic acid-bearing monomers such as sulfonic acid, sodium vinyl sulfonate, sulfoethyl acrylate, sulfoethyl methacrylate, ethyl methacrylate-2-sulfonic acid, or 2-acrylamide-2-methylpropanesulfonic acid; phosphoethyl methacrylate; acid-containing monomers Corresponding salts of; or combinations thereof. In other embodiments of the invention, polar monomers are partially or completely negatively charged, such as trimmers, having one or more points of desaturation, such as terminal unsaturation. With respect to polar oligomers or unsaturated oligomers. In certain other embodiments of the invention, the polar monomer can be base soluble (ie, many COs).₂For low molecular weight polymeric stabilizers (containing H groups and alkaline soluble). Certain unrestricted examples of these polar polymeric stabilizers include the registered trademark MOREZ 101 or the registered trademark TAMOL 731, both of which are Philadelphia, PA. Rohm and Haas), ink. (Rohm and Haas, Inc.) to thus be produced. In these embodiments, the amount of polarity stabilizer in the system can be in the range of 15-50% by weight.

【0032】

In certain embodiments, the aqueous clay dispersion, or second reaction mixture, may contain a monomer mixture of at least one ethylenically unsaturated monomer, which is an anionic monomer. Preferably, the anionic monomer is an acid-containing monomer. In these embodiments, some of the anionic monomers are "staged", i.e., some of the anionic monomers, 50% or less, preferably 25% or less, even more preferably 10% or less. It is added to the clay-free first aqueous reaction mixture and the remaining anionic monomers are added to the second aqueous reaction mixture. In embodiments involving acid-containing monomers, it is believed that the acid-containing monomers, acid functional groups, are equilibrated in the clay gallery and retained there during the polymerization process. The acid-containing monomer helps reduce the viscosity of the aqueous reaction mixture containing clay and can enhance the affinity of the polymer for the clay surface. This stepping method of adding anionic monomers can beneficially result in improvements in physical properties compared to adding the anionic monomers directly to the first aqueous reaction mixture.

【0033】

In embodiments where the acid-added monomer is staged, the amount of acid staged in the second aqueous reaction mixture containing clay is greater than 0% of the total acid added in the aqueous nanocomposite dispersion. Can fall in the range of less than 100%. The second aqueous reaction mixture may contain 1% to 50%, preferably 5% to 25%, and even more preferably 5% to 15% of acid-containing monomers in the aqueous nanocomposite dispersion. Anions for embodiments that utilize high concentrations of acid (ie, 10% or more of the total monomers in the aqueous nanocomposite dispersion are acid-containing monomers) or for stabilization of the polymer dispersion. For embodiments that use a sex surfactant, a low percentage of the acid-containing monomer is incorporated into the second aqueous reaction mixture. The optimum amount of acid-containing monomer will vary depending on the composition of the reaction mixture and the type of acid, but the amount of acid-containing monomer will generally vary with the clay CEC and, if any, a second aqueous reaction mixture. The amount equivalent to the amount of divalent (or higher valence) ions added to the liquid. Therefore, the optimum amount for enhancing the affinity of the polymer with clay contains one clay acid group, one divalent ion, and one acid-containing monomer. The optimum amount uses only as many acid-containing monomers as necessary in the second aqueous reaction mixture to modify the clay with the polymer; then the rest in the first aqueous reaction mixture. The amount of acid-containing monomer helps stabilize the growing polymer / clay nanocomposite particles.

【0034】

For example, in embodiments where a nonionic polymerizable stabilizer such as an alkylethoxylated surfactant is used, the relative of the acid-containing monomer in the second aqueous reaction mixture to the first aqueous reaction monomer. The amount tends to be a higher percentage of the total amount of acid-containing mixture in the nanocomposite. In these embodiments, the acid-containing monomers are intended to specifically aid in the insertion and exfoliation of clay, not for the stabilization of polymer particles.

【0035】

In embodiments where the monomer mixture is emulsified, suitable emulsifiers are, but are not limited to, alkyl-, aryl-, aralkyl-, alkalil-sulfate or sulfonate salts; alkyl-, aryl-, aralkyl-, arca. Lille-poly (alkoxyalkyl) ethers; alkyl-, aryl-, aralkyl-, alkalinel-poly (alkoxyalkyl) sulfates; potassium oleate, especially alkaline salts of long chain fatty acids such as alkyldiphenyloxide disulfonate, etc. In addition, those conventionally used for emulsion polymerization can be mentioned. Preferred emulsifiers may include, for example, dodecylbenzene sulfonate and dioctyl sulfosuccinate.

【0036】

The second aqueous reaction mixture contains an aqueous clay dispersion. Aqueous clay dispersions are at least 0.05, typically 0.1-20, more typically 0.1-15, and even more typically 0.1-10, based on the weight of the monomers in the aqueous nanocomposite dispersion. , Most typically contains 0.5-5% by weight clay. The amount of water present in the aqueous clay dispersion is 70 to almost 100% by weight. In certain embodiments, the aqueous clay dispersion may also contain a monomer mixture containing at least one ethylenically unsaturated monomer, such as the monomers disclosed herein. Preferably, at least one ethylenically unsaturated monomer in the mixture is a polar monomer. In embodiments where the monomer mixture is added to the aqueous clay dispersion, the% by weight of the monomers in the aqueous clay dispersion can be 0.01% to 100% by weight.

【0037】

In certain embodiments of the invention, the weight% of clay in the aqueous phase can decrease as it becomes incorporated into the nanocomposite / polymer phase of the aqueous nanocomposite dispersion. This decrease in clay concentration can occur during the polymerization process as the polymer is formed and the clay (ie, the stripped clay layer and / or the non-peeled clay particles) is incorporated into the nanocomposite particles.

【0038】

Suitable clays for aqueous clay dispersions include any natural or synthetic laminated minerals that can be inserted or exfoliated. Examples of such clays include laminated silicate minerals. Laminated silicate minerals that can be used include natural and synthetic minerals capable of forming interlayer compounds. Examples of certain naturally occurring minerals include, but are not limited to, smectite, phyllosilicate, montmorillonite, saponite, byderite, montmorillonite, hectorite, stephensite, vermiculite, kaolinite and halosite. Can be mentioned. Preferably, among these minerals, there is montmorillonite. An unrestricted example of some synthetic minerals, or synthetic phosphoricates, is the registered trademark Laponite manufactured by Laporte Industries, Ltd. of Charlotte, North Carolina. (LAPONITE), magadiite, and fluorohectorite can be mentioned.

【0039】

Clays generally have at least one naturally occurring cation, such as potassium, calcium, or sodium, or a first cation present in their galleries that is attracted to the effective negative charge on the clay surface. For example, clays such as montmorillonite can be naturally occurring such as sodium or calcium or can be utilized with the first cation. The terms "sodium form" or "calcium form" correspond to clays having a first cation, which is sodium or calcium, respectively.

【0040】

The clay cation exchange capacity (CEC) relates to the ion exchange capacity of the clay, expressed as the positive charge per unit mass of colloidal particles, or the total amount of positive charges that can be adsorbed on the clay surface. Certain CEC values for the illustrated clay minerals are as follows: montmorillonite clay is in the range 70-150 meq / 100 g; halosite clay is in the range 40-50 meq / 100 g; and kaolin Night clay is in the range of 1 ~ 10meq / 100g. In certain embodiments of the invention, the clay selected preferably has a high CEC value. In a preferred embodiment, the clay used in the present invention has a CEC allowance of about 40 meq / 100 g or more, preferably a CEC allowance of about 70 meq / 100 g or more, more preferably a CEC allowance of about 90 meq / 100 g or more, and even more. Preferably, it can have a CEC allowance of about 100 meq / 100 g or more. In certain embodiments of the invention, the clay CEC improves the clay's affinity for the polymer in the nanocomposite dispersion by electrochemically reducing the clay prior to polymerization of at least some of the monomers. The allowance can be increased.

【0041】

In the present invention, the clay in the aqueous clay dispersion can be stripped either partially or completely. Preferably, the clay is at least partially exfoliated clay. As used herein, the phrase "at least partially stripped clay" generally corresponds to clay in which the layers are completely or partially separated from each other. In contrast, the phrase "non-peeling clay" generally corresponds to the physical state of clay that does not exist as a separated layer. The phrase "insertion" generally corresponds to the condition in which the polymer is sandwiched between layers of clay in the system. The phrase "partially inserted" generally corresponds to a condition in which some of the clay layers in the system have polymers between the layers and no other clay layers. Any of the various polymer and clay-based states can be used in the present invention.

【0042】

In general, a completely ("sufficiently") exfoliated aqueous dispersion of clay is highly viscous and / or gelatinous at clay concentrations of a few percent or higher. The exact weight% (concentration) of the clay forming such a highly viscous gel is not limited to these, but one of ordinary skill in the art would expect to be due to a number of factors including clay type, temperature, pH, etc. Must be done. Typically, the clay dispersion forms a free fluid rather than a viscous gel.

【0043】

In the present invention, limiting the degree of exfoliation to less than 100% complete, i.e., partial exfoliation (less than 100%), generally results in a reduced viscosity and / or non-gelled fluid state of the clay dispersion. provide. Thus, some of the clay that is exfoliated into the clay layer generally provides a major contribution to the increase in viscosity, while the non-exfoliated portion (ie, clay particles) makes a small contribution to the increase in viscosity. To serve. Therefore, the total amount of partially exfoliated clay in the aqueous clay dispersion is generally less than about several% by weight, preferably 5% by weight or less, more preferably 4% by weight or less, based on the total weight of the dispersion. Even more preferably, it is 3% by weight or less. Further exfoliation of the clay can occur during continuous treatments such as the step of emulsion polymerization. It is expected that the reduction in viscosity of the aqueous clay dispersion can be supported by dispersants such as, but not limited to, polyphosphoric acid. These can be added during the polymerization process or to the polymerization product.

【0044】

Often, moderate mechanical mixing that does not require high shear may be appropriate to provide dispersion of at least partially exfoliated clay in water. If a fully exfoliated clay causes processing problems related to high viscosity and / or the presence of gel in the reaction medium, the degree of exfoliation should be less than complete. Similarly, the clay should be at least partially exfoliated to achieve the desired chemical and physical properties. Similarly, the step of shearing clay in an aqueous environment generally results in an increase in viscosity in the aqueous environment. Generally, the greater the degree of peeling, the greater the increase in viscosity.

【0045】

In addition to increasing the degree of clay exfoliation, increasing the clay concentration in the aqueous nanocomposite dispersion can also result in an increase in viscosity. To this end, the viscosity can be controlled by diluting the reaction medium and / or clay dispersion with a suitable liquid such as water. Typically, it may be desirable to control the viscosity of the reaction medium and / or clay dispersion by dilution prior to the polymerization step. For example, in order to obtain a high concentration of clay enrichment in the nanocomposite of the present invention (eg, an amount of clay greater than 5% relative to the total weight polymer in the aqueous nanocomposite dispersion), the reaction medium may be: It can be diluted with a sufficient amount of water prior to the continuous polymerization step to reduce the viscosity. The amount of dilution required to achieve a particular viscosity level can be readily determined by one of ordinary skill in the art. In general, the solid content concentration of the reaction medium is less than 50%, typically between 10% and 40%, and even more typically 20%, in order to obtain a sufficient viscosity range prior to subsequent addition of the reactants. Can be controlled between ~ 30%. In certain embodiments, the viscosity of the aqueous dispersion prior to the addition of the reactants is measured using a Brookfield viscometer at 60 rpm (rpm) and using a # 3 spindle. If so, it falls within the range up to 5,000 centipoise ("cps").

【0046】

Aqueous clay dispersions can be produced by applying a shearing force to an aqueous clay mixture containing at least one unmodified clay, such as by mechanical mixing that partially and / or sufficiently strips the clay. Various high shear methods are also envisaged that destroy the physically perfect state of the clay particles in water in order to exfoliate the clay at least partially without the need for a modifier such as a surfactant. These methods include, but are not limited to, ultrasound, megasonication, grinding / crushing, high speed mixing, homogenization and the like. Aqueous clay dispersions have a shearing force at temperatures in the range of 10 to 150 ° C, preferably 20 to 100 ° C, more preferably 20 to 90 ° C, to further aid in stripping the clay layer. Can also be applied to. Such high shear methods can be used in the methods of the invention, but these methods are not required to achieve at least a partially exfoliated state. In various embodiments of the invention, the clay may contain both exfoliated clay layers and non-exfoliated clay particles. In certain embodiments of the invention, homogenization of the clay dispersion is not required. In fact, in certain embodiments of the invention, homogenization is not required to provide the desired improvement in physical properties such as tensile strength, depending on the amount of clay in the dispersion.

【0047】

Hydrophobic modifications can also be used in the methods of the invention. In certain embodiments of the invention, the clay can be at least partially hydrophobically modified. As specified above, modifiers such as surfactants modify the surface chemistry of clay, for example, by ion exchange with naturally occurring cations present in the clay. This results in a "sandwiched" or "inserted" state in which the surfactant is "sandwiched" between the individual layers that replace the naturally occurring cations. An exemplary surfactant is characterized in that the hydrophilic head group and tail are selected from hydrogen and alkyl, alkenyl, and alkynyl groups having about 4 to about 30 carbon atoms. Anionic, cationic, or nonionic surfactants having one oil-affinitive tail can be mentioned. Preferably, the surfactant used in the method of the present invention is a cationic surfactant. As used herein, the phrase "cationic surfactant" means that the hydrophobic or hydrophilic moiety, preferably the hydrophilic moiety, carries a positive charge when dissolved in an aqueous medium. The surfactant characterized by is shown. Representative cationic surfactants are, for example, salts containing quaternary ammonium, quaternary phosphonium, or quaternary sulfonium cations, or aliphatic mono-, di-, and polyamines derived from fatty acids and loginic acids. Such as onium salt. With the representative surfactants provided, the positive charge is generally present in amino or tetranitrogen.

【0048】

As specified above, the clay material present in the nanocomposite dispersion, or the clay dispersion contained therein, includes first cations between the clay layers. Instead, the first cation may exist as a counterion to the anion in the surfactant. This first cation refers to naturally occurring cations present within the gallery of clay minerals, such as sodium, potassium, or calcium cations, and / or surfactants, preferably cationic surfactants. Can include. For example, the first cation may preferably contain 0 to 20% by weight, or more preferably 0 to 50% by weight, of the dry weight of the clay. In certain preferred embodiments, sodium-type, hydrophobically modified clays are even more preferred.

【0049】

A second cation, preferably a polyvalent cation, more preferably at least one divalent or trivalent cation, and even more preferably Ca, Mg, Cu, Mg, Fe, or Zr. At least one divalent or trivalent metal cation, such as, is added to the aqueous nanocomposite dispersion or clay dispersion. Preferably, the second cation does not include an onium cation or a cationic surfactant. Addition of a second cation to the aqueous clay dispersion yields a modified aqueous clay dispersion. Addition of a second cation to the aqueous nanocomposite dispersion yields an in-situ modified clay. The cations are preferably soluble, i.e., present at such a concentration that all of the cations are soluble in the solvent. In a preferred embodiment, the solvent is water and the cations are water soluble.

【0050】

The second cation can preferably be added in the form of a slurry or solution. In certain embodiments of the invention, the second cation is added in the form of a solution containing a metal salt containing at least one divalent and / or trivalent cation. Preferably, the metal salt is dissolved in water or other solvent. Examples of such metal salts are, but are not limited to, Ca (OH).₂, Mg (OH)₂, Or Mg (SO)₄). A further, unlimited example of a metal salt containing a divalent or trivalent cation is provided in US Pat. No. 5,998,538. The choice of the second cation can be influenced by the end use of the nanocomposite, whereas the choice of anion can affect the solubility. The amount of the second cation added to the aqueous nanocomposite or clay dispersion is 0.001 to 10% by weight, more preferably 0.01 to 5, based on the dry weight of the clay in the nanocomposite or clay dispersion. It is in the range of% by weight, and even more preferably 0.1 to 1% by weight. High temperatures are preferred because they favor the exchange of second cations with the first exchangeable cations. However, the second cation can exchange with the first exchangeable cation at room temperature, i.e. above 25 ° C.

【0051】

According to the present invention, at least a part of the second cation effectively exchanges ions with at least a part of the first cation. The second cation need not be completely exchanged for the first cation. The degree of exchange can be determined, for example, by isolating the polymer from the aqueous phase in latex and analyzing the aqueous phase by standard techniques such as quantitative atomic absorbance.

【0052】

The choice of a second cation to be added to the nanocomposite system or clay dispersion depends, for example, on the desired properties or intended end use. Preferably, at least a portion of the second cation should differ from at least a portion of the first cation for effective ion exchange. For example, in a system in which the first cation contains sodium, calcium, and a cationic surfactant, divalent cations such as calcium are generally first the sodium cation and then the cationic surfactant. Replace with activator. The first calcium cation is not expected to exchange for the second calcium cation, and on the contrary, reaches equilibrium. Therefore, if the first cation is entirely composed of calcium, the exchange does not occur explicitly. For example, the literature "Ion Exchange Interaction of Quaternary Alkylammonium Cations with Sodium and Calcium Forms of Quaternary Alkylammonium Cations with Sodium and Calcium Forms of Montmorillonite) , AI Zhukova et al., Ukr.Khim.Zh., 1975, Vol. 41 (7), pp. 696-699, that the naturally occurring calcium cations in montmorillonite clay are the surfactant cations Me.₄N⁺Or BuNH³⁺Describe that they are more tightly coupled. The ratio of ion exchange is a variety of factors such as the relative amount of the first and second cations in the system, the relative size of the cations to be exchanged, and / or the amount of water molecules present in the gallery. It changes depending on. Since the exchange of the first and second cations is reversible, in certain preferred embodiments of the invention, the forward reaction, or the reaction of exchanging the second cation for the first cation, is Preferably, it occurs rather than the reverse reaction.

【0053】

The second cation can be added to the clay dispersion during or at any time thereafter during the polymerization process to enhance the polymer's affinity for clay in the system and improve the physical properties of the nanocomposite. .. Preferably, the second cation can be added to the aqueous clay dispersion before or during the polymerization of the monomers forming the nanocomposite dispersion. This state of addition generally results in a significant improvement in the physical properties of the nanocomposite compared to the addition of a second cation after the polymerization. Improved properties can also be seen when the second cation exchanges for the first exchangeable cation in the presence of soap nonionic surfactant, calcium hydroxide, or water. .. The presence of nonionic surfactants enhances the physical properties of the resulting product, such as the extent to which the second cation is exchanged for the first exchangeable cation, and the tensile strength of the nanocomposite. appear.

【0054】

The modified aqueous clay nanocomposite dispersion or the aqueous clay dispersion to which the second cation is added may exhibit a lower viscosity than the unmodified aqueous nanocomposite dispersion. Depending on the composition of the nanocomposite dispersion, the decrease in viscosity can be orders of magnitude, ie from thousands of centipoises to hundreds of centipoises. This decrease in viscosity can be due to the attraction of the negative portion of the polymer to the cations exchanged on the clay surface.

【0055】

In certain preferred embodiments of the invention, the step of supplying at least one first ethylenically unsaturated monomer, at least partially stripped clay, and optionally at least one second ethylenically unsaturated monomer. A step of supplying the containing aqueous clay dispersion liquid, wherein the clay has a first exchangeable cation, and a step of adding a second cation to the water-based clay dispersion liquid, the second step. A step of exchanging at least a part of the cations with at least a part of the first cations to form a modified aqueous clay dispersion, modified with the first ethylenically unsaturated monomer. The step of combining the aqueous clay dispersion and the polymerization of the first or second monomer to obtain the aqueous nanocomposite dispersion in which at least one first or second ethylenically unsaturated monomer contains a polar monomer. A method for producing an aqueous nanocomposite dispersion including a step of forming is provided. In certain embodiments, the monomers of the nanocomposite dispersion are polymerized after the addition step. These steps can be performed in a variety of different sequences. For example, in one embodiment, the second supply and addition steps can be performed either before or after the polymerization step.

【0056】

In the third step of one embodiment of the present invention, the first and second aqueous reaction mixtures, or the aqueous mixture and the aqueous clay dispersion, are emulsion-polymerized in multiple steps. In such multi-stage emulsion polymerization, the monomer of the first monomer mixture is preferably converted to greater than 80%, preferably greater than 90%, and even more preferably greater than 95% to form a polymer particle dispersion. Involves in step-growth polymerization of two or more monomer mixtures that are polymerized to a degree. In this polymerization, preferably in the presence of a polymer particle dispersion to form another polymer (eg, the surrounding polymer shell or domain within the polymer particles) with the polymer particles and / or another polymer particle. Polymerization of the second monomer mixture containing the clay dispersion is followed.

【0057】

In another aspect of the invention, the aqueous dispersion can be prepared by a multi-stage emulsion polymerization step in which at least two steps of different composition are polymerized in sequential form. Such a step usually results in the formation of at least two mutually incompatible polymer compositions, thereby forming at least two phases within the polymer particles in the aqueous nanocomposite dispersion. Such particles include, for example, core / shell or core / sheath particles, core / shell particles with a shell phase that incompletely encapsulates the core, core / shell particles with diverse cores, and intrusive network particles. It consists of two or more phases of various structures. In all of these cases, the majority surface area of the particle is occupied by at least one outer phase and the inside of the particle is occupied by at least one inner phase. Each of the stages of the multistage emulsion polymer in the aqueous nanocomposite dispersion may contain the same monomers, surfactants, redox initiators, chain transfer agents, etc. as disclosed herein for emulsion polymers. Polymerization techniques used to prepare such multistage emulsion polymers, such as US Pat. Nos. 4,325,856; 4,654,397; and 4,814,373, are well known in the art.

【0058】

It should be recognized that during this step, the first and second aqueous reaction mixtures can be subjected to multistage polymerization in any order. In order to prepare the nanocomposite composition in the form of a dry powder, the monomer in the clay-containing mixture or the second aqueous reaction mixture is polymerized after the monomer in the first aqueous reaction mixture. Is preferable.

【0059】

In one embodiment of the invention, the clay can be exfoliated at least partially during the polymerization of the monomer and the monomer in the second reaction mixture containing the clay. In this embodiment, the clay / monomer mixture may be the first step of the multistage polymerization so that the inner polymer core portion of the multistage polymer preferably comprises at least a portion of the clay. In another embodiment, the clay / monomer mixture may be the second stage of multistage polymerization, so that the outer polymer shell portion of the multistage polymer generally comprises at least a portion of the clay. In another embodiment, both stages can include clay.

【0060】

The emulsion polymerization step is generally carried out in a suitable reactor, where the reactants (monomer, initiator, any emulsifier, aqueous clay dispersion, and any chain transfer agent) are properly combined and mixed. It is reacted in an aqueous medium and heat can be transferred and released to the reactor. The reactants are preferably added to the reactor slowly (in a semi-batch method, gradually), continuously or quickly as a "shot" (batch-like) over time. Typically, the reactants are added gradually (gradual addition"" to the reactor.

【0061】

In another embodiment of the invention, the nanocomposite dispersion of the invention can be polymerized through techniques other than emulsion polymerization. For example, nanocomposite dispersions can be polymerized via bulk polymerization techniques, ie, polymerization without added solvent or water. In other embodiments, solution polymerization techniques can be used when the heat of polymerization of the monomer or the viscosity of the polymer is too high. Preferably, this polymerization occurs in an aqueous medium, but other media or solvents may be used. However, certain drawbacks associated with solution polymerization can be solvent removal at the completion of the reaction and chain transfer reactions with solvents that can limit the molecular weight.

【0062】

In another embodiment of the invention, the monomers in the nanocomposite can be polymerized by suspension polymerization. In these embodiments, the monomers are mechanically dispersed in a liquid medium, preferably water, and polymerized as droplets.

【0063】

Various initiator systems are known in the free radical initiation industry and can be used in the methods described herein. The choice of initiator system can vary depending on the polymerization technique used. Heat initiators such as, but not limited to, persulfates can be used. Alternatively, a free radical redox initiator system may be used. Examples of such systems include, for example, sodium metasulfite, sodium hydrogen peroxide, sodium formaldehyde sulfoxylate, sodium bisulfite, isoascorbic acid, sodium hydrosulfite, 2-hydroxy-2-sulfinatoacetic acid, 2-. Oxidizing agents such as persulfites, azos, peroxides (eg hydrogen peroxide, t-butyl hydroperoxide, t-amyl hydroperoxide) in combination with reducing agents or reducing agents such as hydroxysulfonatoacetic acid. Alternatively, an oxidant or the like can be mentioned.

【0064】

Free radical initiators commonly used in various step methods are carried out in the temperature range of 10 ° C to 100 ° C, preferably 20 ° C to 95 ° C, more preferably 55 ° C to 90 ° C. It is conventionally used in free radical redox polymerization. Temperatures above 100 ° C are possible using equipment designed for high pressure. In certain embodiments involved in redox initiation, the initiation temperature is preferably maintained below 85 ° C, more preferably below 55 ° C, for redox initiation. In other embodiments involved in heat initiation with persulfate, temperatures in the range 80 ° C to 90 ° C are used.

【0065】

In certain embodiments, the present invention may use redox methods to initiate modification of the clay surface and aid in the polymerization of monomers between layers of clay. A relatively large percentage of the weight of the clay, especially more than 2% by weight, contains redox-active polyvalent metal ions such as iron, copper, manganese, etc. that are present in the gallery and / or in the surface layer of the clay. These redox-active polyvalent metal ions, which are unique in the clay or added to the system, can be used to promote radical generation from the redox-initiator component. In the redox method, Fe^IIOr Fe^IIIClays containing metal ions, such as, can be reacted in the presence of either an oxidant or a reductant, respectively, to form radicals. Redox-inducing radicals are formed in the space between the clay layers or on the surface of the clay, facilitating the insertion and / or exfoliation of the clay. In addition, the redox method can produce polymer clay nanocomposites that exhibit a higher degree of film transparency than in the absence of redox.

【0066】

Fe^IIIn a redox method in which clay with is reacted in the presence of an oxide, the chemically reduced form is its natural Fe.^IIClay in form, optionally added to an aqueous reaction mixture containing a surfactant. Preferably, the amount of reducer added is sufficient to reduce the number of moles of any iron contained in the clay. Fe of it^IIIFrom Fe^IIConfirmation of the reduction of clay to is made by observing the color change of the aqueous reaction mixture. The aqueous reaction mixture can be gray / green in appearance. Once the iron is reduced, the chemical oxidant is added to the aqueous reaction mixture along with one or more monomers. Fe with oxidants^IIThe interaction of the clay causes an electrochemical reaction that causes the transfer of electrons from the iron associated with the clay to the oxidant. Reduction of the oxidant transforms the oxidant into redox-induced radicals that can initiate polymer chains, either on the surface of the clay or in the gallery space between the clay layers. It is disassembled. In this means, the redox initiation system can aid in the insertion and / or exfoliation of polymer / clay nanocomposites. This redox method can be used to initiate and / or maintain polymerization throughout the formation of the entire nanocomposite. In addition, redox methods can be used to alter the CEC value of clay.

【0067】

In an alternative embodiment, Fe^IIIMolded clay is reacted in the presence of a reducing body, and the monomeric emulsion found is its natural Fe.^IIIIt is added to an aqueous reaction mixture containing clay in a mold. The reducer is clay Fe^IIIIt interacts with the groups and is oxidized, which can cause radical formation and the initiation of continuous polymer chains on or near the surface of the clay. Once speciation is complete, the nanocomposite latex is formed by the standard methods disclosed herein. This redox method can also be used to initiate and / or maintain polymerization throughout the formation of the entire nanocomposite. In addition, redox methods can be used to alter the CEC value of clay.

【0068】

In certain embodiments where the redox system is the sole source of radicals, polymer chain growth is confined to either the tablet or the conversion space on the surface of the clay. It may continue to appear in the area near the clay surface. Redox (such as sodium formaldehyde sulfoxylate, isoarcobic acid, etc.) and oxides (ammonium persulfate, hydrogen peroxide, etc.), along with redox-active polyvalent metal ions found in clay or added separately. The use of (such as tert-butyl hydroperoxide, etc.) is also a useful method for preparing the polymer / clay nanocomposites of the present invention.

【0069】

In one embodiment of the invention, the monomers can be added to the reactor in batch-like (shot or continuously fed over time; 0.5-18 hours, preferably 1-12. Continuous supply by slowly adding the aqueous reaction mixture to the reactor over time, even more preferably 2-6 hours, is useful for controlling the reaction temperature.

【0070】

A buffer may also be present in the reaction mixture during the emulsification mixture. The buffer is generally, but is not limited to, a salt of a weak acid such as sodium bicarbonate, sodium carbonate or sodium acetate. When added, the amount of buffering agent that may be present in the reaction mixture can be in the range of 0.01-5% by weight based on the total monomers used for the polymerization. In general, low concentrations of strong bases such as ammonia or sodium hydroxide can also be used to control the pH of the polymerization. These agents can be added either before, during, or after the polymerization step. The buffer controls the hydrolysis of certain monomers and affects the degree of premature cross-linking during polymerization (as when N-methyloacrylamide monomers are used) or the rate of degradation of the initiator. And / or to control colloidal stability, can be further used to influence the degree of dissociation of the carboxylic acid monomer and surfactant.

【0071】

Optionally, at least one chain transfer agent can be incorporated during the polymerization to control the molecular weight of the polymer. Examples of chain transfer agents include, but are not limited to, mercaptans, polymercaptans, and polyhalogen compounds. In addition, unlimited examples of chain transfer agents include ethyl mercaptans, n-propyl mercaptans, n-butyl mercaptans, isobutyl mercaptans, t-butyl mercaptans, n-amyl mercaptans, isoamyl mercaptans, t-amyl mercaptans, n-hexyls. Alkyl mercaptans such as mercaptan, cyclohexyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan; mercaptocarboxylic acids such as methyl mercaptopropionate and 3-mercaptopropionic acid and their esters; isopropanol, iso Examples include alcohols such as butanol, lauryl alcohol, and t-octyl alcohol; and halogenated compounds such as carbon tetrachloride, tetrachloroethylene, and trichloro-bromoethane. Generally, 0-10% by weight can be used relative to the weight of the monomer mixture. The polymer molecular weight can also be controlled by other techniques such as selecting the ratio of initiator to monomer.

【0072】

Stabilizing surfactants can be added to one or both of the reaction mixtures to prevent agglutination of the polymeric latex particles. Generally, growing latex particles are stabilized during emulsion polymerization by one or more surfactants, such as anionic or nonionic surfactants, or mixtures thereof. Examples of surfactants suitable for emulsion polymerization are the annually published McCutcheon's Detergents and Emulsifiers (MC Publishing Co., Glen Rock, NJ). )) Provided. Other stabilizers such as protective colloids may be used.

【0073】

The first mixture of monomers can be polymerized in the presence of a preformed polymer dispersion (seed latex) to control the desired particle size. Seeds are also commonly used to control the structure and / or morphology of the resulting polymer. The "seed" latex may contain small particles with an average diameter of less than 200 nm, preferably less than 100 nm, and even more preferably less than 65 nm. Common seed latex particles are similar or different in composition of the monomers used in the production of first-stage multi-stage nanocomposites or first-stage seeded single-stage nanocomposite polymers. Can indicate composition. The preformed polymer dispersion may include polymer particles of a rubbery material and may be similar or different in composition to the core polymer. As used herein, the phrase "rubbery" refers to the thermodynamic state of a polymer above its glass transition temperature. Alternatively, seeds include hard non-rubbery polymer particles (eg, polystyrene or polymethylmethacrylate) that can be used to regulate the index of refraction, as taught by Myers et al., US Pat. No. 3,971,835.

【0074】

The present invention also includes nanocomposite polymer particles formed in the previous polymerization or additional polymerization steps. These steps can occur before, during, or after the formation of clay-containing steps.

【0075】

Another method of the present invention is to apply an aqueous dispersion containing at least one ethylenically unsaturated monomer and a layered clay modified by adding a second cation into one or more emulsion polymer seeds. Gradually added and involved in polymerization. In this way, the emulsion polymer seed has a particle diameter of preferably 20-500 nm, more preferably 30-400 nm, and even more preferably 40-300 nm. The emulsion polymer seed is 0.1 to 10%, preferably 0.5% to 8%, and even more preferably 1% to 5%, based on the dry weight of the total polymer weight in the nanocomposite dispersion. While the polymer seeds generally do not need to contain clay, in this embodiment the polymer seeds are further clay, preferably up to 20%, based on the dry weight of the total polymer weight in the nanocomposite dispersion. It is intended to contain up to 10% clay, more preferably up to 5% clay.

【0076】

The aqueous dispersion in this method is at least 1 of 80 to 99.95%, preferably 85 to 99.9%, even more preferably 90 to 99.9%, based on the dry weight of the total polymer weight in the nanocomposite dispersion. 0.05% to 20%, preferably 0.1% to 15%, even more preferably 0.1% to 10%, based on the dry weight of the total polymer weight in the ethylenically unsaturated monomer and the nanocomposite dispersion. Contains layered clay.

【0077】

After each step of polymerization, at least 95%, preferably at least 97%, and even more preferably 99%, based on the weight of the monomer, may be polymerized in the reactor before the step-growth polymerization step is initiated. desirable.

【0078】

Emulsion polymer seeds can be formed in the same reaction vessel in which the monomer is polymerized and / or manufactured in a separate reaction vessel and can be continuously introduced into the reaction vessel in which the monomer is polymerized. In certain embodiments, the polymer seeds of the aqueous emulsion are formed in the same reaction vessel in which the monomers are polymerized. In these embodiments, the aqueous clay dispersion may contain up to 200% by weight of layered clay based on dry weight. The low solid percentage in the reaction vessel allows anyone to obtain high clay concentrations while maintaining the available viscosity. In an alternative embodiment, the polymer seed may contain at least partially exfoliated layered clay relative to dry weight. In this embodiment, the amount of clay is in the range of 0.05% to 20%, preferably 0.1% to 15%, even more preferably 0.1% to 10% of the total dry polymer weight in the polymer seed.

【0079】

Another method of the present invention is to mix an aqueous emulsion polymer with a layered clay modified by the addition of a second cation at 0.1-10% based on the dry weight of the emulsion polymer. Involved in preparing nanocomposite dispersions. In this method, the aqueous emulsion polymer is preferably prepared by any of a variety of known methods of preparing emulsion polymers by emulsion polymerization techniques. In one embodiment of this method, it is preferred that the nanocomposite dispersion is prepared using a gradual addition "grad-add" method. In this embodiment, it is also preferred that the nanocomposite polymer is prepared by multi-stage polymerization, such as core-shell polymer particles with a rubber core and a hard shell.

【0080】

The step of mixing the modified layered clay in this embodiment is preferably completed without the need for a clay surfactant. In another embodiment, the clay to which the second cation is added is pre-dispersed in water and mixed with an aqueous emulsion polymer. Any mechanical mixing device may be suitable as long as the clay particles are at least partially exfoliated. More preferably, the clay particles are mixed to uniformly disperse the clay in the nanocomposite dispersion. For example, the registered trademark COWLES mechanical mixer can be used to prepare modified aqueous clay dispersions containing up to 20% clay. However, it is more preferred to use a mechanical homogenizer to prepare an aqueous clay dispersion containing 0.1-10% clay.

【0081】

The aqueous nanocomposite clay-polymer dispersion of the present invention is also prepared by utilizing reverse phase emulsion polymerization. For example, in U.S. Pat. Nos. 3,284,393, 3,826,771, 4,745,154, the methods described in the accompanying literature are these when used to make acid-containing polymers (high or low concentrations of acid). Can be used to incorporate clay and second cations into the aqueous phase of the polymerization of. The reverse phase emulsion polymerization method can yield high molecular weight polymers or copolymers based on the water soluble monomers and mixtures contained therein. The aqueous solution of these monomers can be dispersed in the oil phase by means of a water emulsifier in oil and subsequently polymerized continuously under free radical forming conditions.

【0082】

Aqueous nanocomposite clay-polymer dispersions can be useful, for example, as coatings, sealants, caulks, adhesives, and plastic additives. A coating composition containing an aqueous nanocomposite clay-polymer dispersion provides improved properties such as block resistance, print resistance and dirt topic up properties, improved barrier properties, and improved flame retardancy. Can be shown. In addition, the coating composition comprising the aqueous nanocomposite of the present invention demonstrates the ability to utilize a more flexible binder without the need for additional fusion agents (solvents) for film formation and in dry films. Sufficient hardness, toughness, and low stickiness can still be maintained. Suitable uses for the coating compositions of the present invention are building coatings (particularly low VOC applications for semi-gloss and luster); factory coatings (metals and woods, thermoplastics and thermosettings); Repair coatings (eg, on metal); automotive coatings; concrete roof tile coatings; elastomeric roof coatings; elastomeric wall coatings; external insulation finishing systems; and inks. The aqueous nanocomposite dispersion of the present invention can be useful as an additive, a dispersant, an alkali-soluble resin, and an acid-functional viscosity-imparting agent. It is further intended that the aqueous nanocomposite dispersion may impart hardness when used as an additive for coating applications. Another use for aqueous nanocomposite dispersions is for opaque polymers and hollow spherical pigments. Mixing of the aqueous nanocomposite dispersion can provide, for example, a harder, more fracture resistant shell or may be suitable for fiber modification. Further unrestricted examples of applications for aqueous clay-polymer nanocomposite dispersions are polishes; binders (such as non-woven fabrics, paper coatings, pigment printing, or ink binders); Adhesives (such as pressure sensitive adhesives, coagulation adhesives, or other water-based adhesives); adhesives for plastics; ion exchange resins; hairdressing fixers; caulking materials; And sealant material. Aqueous clay-polymer nanocomposite dispersions can impart strength and toughness to the aforementioned applications.

【0083】

In one embodiment of the invention, the aqueous nanocomposite dispersion can be dried to form a film (eg, coating and adhesive). In this embodiment, the nanocomposite polymer preferably has a glass transition temperature in the range of -80 ° C to 50 ° C. The glass transition temperature can be calculated using the Fox equation (see TGFox, Bull. Am. Physics Soc., Volume 1, Publication No. 3, p. 123 (1956)).

【0084】

Another embodiment of the present invention is intended to prepare a coating composition comprising an aqueous nanocomposite dispersion. Examples of the coating composition of the present invention include building coatings, repair coatings, factory coatings, automobile coatings, elastomeric wall or roof coatings, exterior insulation finish coatings, and the like. Paper or thick paper coatings, paint topcoats, textile coatings and lining coatings, leather coatings, cemented roof tile coatings, and coatings or paint compositions that may be described by those skilled in the art as road paints. Can be mentioned. Alternatively, the coating or coating composition may be described as a clear coating, a matte coating, a satin coating, a semi-gloss coating, a gloss coating, a primer, a textured coating, and the like. In these embodiments, the polymer of the nanocomposite preferably has a glass transition temperature in the range of 0 ° C to 70 ° C.

【0085】

The coating composition of the present invention further comprises pigments and / or fillers such as titanium dioxide, iron oxide, zinc oxide, magnesium silicate, calcium carbonate, organic and inorganic color pigments, and clays other than layered clays. sell. Such pigment-colored compositions generally contain 3 to 70% by volume, or more preferably 15 to 60% by volume.

【0086】

The dressing composition can be prepared by techniques well known in dressing techniques. First, optionally at least one pigment is dispersed in an aqueous medium under high shear as imparted by the registered trademark COWLES mixer, or instead, at least one pre-dispersed. Pigments can be used. The aqueous nanocomposite dispersion can then be added, if desired, together with other dressing adjuvants under low shear agitation. Alternatively, the aqueous nanocomposite dispersion can be included in any pigment dispersion step. Coating composition includes, for example, pressure-sensitive adhesives, emulsifiers, fusion agents, plasticizers, buffers, neutralizers, thickeners or rheology modifiers, moisturizers, heat-, humidity-, light-, and other. Chemical-or energy-hardeners such as cross-linking agents, wetting agents, biocides, plasticizers, defoamers, colorants, waxes, water repellents, slip or scratch resistant agents, antioxidants, etc. It may also include conventional coating adjuvants. In addition to the aqueous nanocomposite dispersions described herein, the coating composition can be at least one other polymer, preferably, but not limited to, solid particles, particles having single voids, or polyvoid particles. It may include an additional emulsion polymer selected from film-forming and non-film-forming emulsion polymers, including polymerizable pigments such as. These additional polymers, when added to the coating composition of the present invention, may be present in an amount of 0-200% of the total dry polymer weight in the nanocomposite dispersion, based on dry weight.

【0087】

The solid content of the dressing composition can range from 10% to 70% by volume. The viscosity of the dressing composition can be 0.05-100 Pascal-seconds (Pa.s), or 50-100,000 centipoise (cP), as measured using a Brookfield viscometer; Viscosities suitable for use vary considerably.

【0088】

The coating composition can be, for example, a roll coater, a brushing and spraying method such as doctor blade coating, a printing method, an air spray spray, an air assist spray, an airless spray, a high volume low pressure spray, an air assist airless spray, an air knife application. , Trailing blade coating, curtain coating, and can be applied by conventional usage methods such as extrusion.

【0089】

The coating composition is, for example, paper or thick paper; compressed wooden products; glass; plastics; wood; metal; primer or pre-painted surfaces; weathered surfaces; asphalt substrates; ceramics; leather; and "raw" or hardened forms. Can be applied to substrates such as water-hard substrates such as cement, concrete, gypsum and stucco in. The dressing composition applied to the substrate is generally dried or dried at a temperature of 10 ° C to 95 ° C.

【0090】

In another embodiment of the invention, an adhesive composition comprising an aqueous nanocomposite dispersion is provided. The various components, methods, and uses of the dressing compositions described above are preferably applicable to these nanocomposite-containing adhesive compositions.

【0091】

In another embodiment of the invention, a caulking and sealant composition comprising an aqueous nanocomposite dispersion is provided. The various components, methods, and uses of the coating compositions described above are preferably applicable to these nanocomposite-containing caulking and sealant compositions. In addition, the caulking and sealant compositions preferably have a paste-like or gel-like consistency, preferably with a higher viscosity as indicated by the coating. Thus, caulking and sealant materials can be prepared using the aqueous nanocomposite dispersions of the present invention according to common formulations known in the art for preparing caulking and sealant materials from emulsion polymers. In this embodiment, the caulking and sealant materials can be prepared by mixing an aqueous nanocomposite dispersion with a filler by methods known in the art.

【0092】

In some embodiments of the invention, the aqueous nanocomposite dispersion preferably forms a film by drying with or without the addition of a plasticizer or flocculant (eg, coating and adhesive). In these embodiments, the nanocomposite polymer preferably has a glass transition temperature in the range of -80 ° C to 100 ° C.

【0093】

In another embodiment of the invention, an adhesive composition comprising an aqueous nanocomposite dispersion is intended. Adhesive compositions include, for example, pressure sensitive adhesives, laminated adhesives, packaging adhesives, hot melt adhesives, reactive adhesives, coagulation adhesives, and flexible or rigid industrial adhesives in the art. Some are known. In these embodiments, it is preferred that the nanocomposite polymer exhibits a glass transition temperature in the range of -80 ° C to 80 ° C. Adhesives are generally prepared by mixing any pigment, and any of the adjuvants listed above as a dressing adjuvant. Adhesive compositions are generally applied to plastic substrates such as films, sheets, and reinforced plastic composites; metal foils; woven fabrics; metals; glass; cemented substrates; and substrates including wood or wood composites. To. Coating on the substrate is generally performed mechanically by a moving roll coater or by a manual coating device.

【0094】

In another embodiment of the invention, a caulking or sealant material containing an aqueous nanocomposite dispersion is considered. In these embodiments, the nanocomposite polymer preferably has a glass transition temperature in the range of -80 ° C to 0 ° C. Caulking or sealant materials are generally prepared by mixing pigments and, where appropriate, any of the adjuvants listed above as coating adjuvants. Caulking or sealant compositions are generally prepared with high solid content concentrations such as 70% by weight and above to minimize shrinkage on drying, resulting in a gel-like or paste-like composition. Can have consistency. Caulking or sealant compositions are generally applied to the filling and / or sealing joints of substrates, including metals; glass; cemented substrates; wood or wood composites; and combinations thereof, and are generally applied under ambient conditions. And it is dried.

【0095】

In another embodiment of the invention, an ink composition comprising an aqueous nanocomposite dispersion is considered. Examples of the ink composition include those known in the art as flexographic printing inks, gravure inks, inkjet inks, and pigment printing pastes. In these embodiments, the nanocomposite polymer preferably has a glass transition temperature in the range of -50 ° C to 50 ° C. Inks are generally made by mixing any pigment, pre-dispersed pigment, or dye, and any of the adjuvants listed above as a dressing adjuvant. Ink compositions are generally applied to substrates including plastic substrates such as films, sheets, and reinforced plastic composites; paper or thick paper; metal foil; woven fabrics; metal; glass; cloth; and wood or wood composites. Will be done. Application to the substrate is generally performed mechanically by flexographic printing blankets, gravure rolls, silk screens.

【0096】

In another aspect of the invention is intended a digital image composition that incorporates an aqueous nanocomposite dispersion and / or nanocomposite particles. As used herein, the term "digital image" generally relates to a composition for copying an image onto a substrate. Suitable uses for digital image compositions include toners for electrophotographic techniques such as xerography, or compositions for inkjet printers or similar applications. The Tg and particle size of a digital image composition will vary depending on the method or system of application. In general, digital image compositions for ink jet applications may have smaller particle sizes and lower Tg than the particle size and Tg for digital image compositions for electrophotographic applications. For example, a typical Tg value for inkjet applications can be in the range of 45 ° C to 60 ° C, while a Tg value for electrophotographic technology applications can be in the range of 55 ° C to 85 ° C. .. In addition, unrestricted variables such as viscosity, surface tension, and pH of the digital image composition can also be adjusted based on the end use of the composition.

【0097】

In another embodiment of the invention, a non-woven binder comprising an aqueous nanocomposite dispersion is intended. Nonwoven binder compositions include, for example, binders for consumer and industrial nonwovens such as wipe fibers and interlinings, binders for insulating nonwovens such as fiberfills and fiberglass, and filter papers for oils. Examples include those known as binders / strengthening agents for non-woven fabrics and papers. In these embodiments, the nanocomposite polymer preferably has a glass transition temperature in the range of -60 ° C to 50 ° C. Nonwoven binders are generally prepared by mixing any pigment and, where appropriate, any of the adjuvants listed above as a dressing adjuvant. Nonwoven binder compositions are applied to substrates such as cellulose fibers such as paper and rayon; synthetic fibers such as polyester, aramid, and nylon; nonwovens formed from glass fibers and mixtures thereof. The coating on the substrate is generally carried out mechanically by a saturated bath, a rotary coating machine, a spray or the like.

【0098】

In another embodiment of the invention, a polish containing an aqueous nanocomposite dispersion is intended. Examples of the polish composition include those known in the art as floor polishes, furniture polishes, and automotive polishes. In these embodiments, the nanocomposite polymer preferably has a glass transition temperature in the range of 0 ° C to 50 ° C. The polish is generally prepared by mixing any pigment and, if appropriate, any of the adjuvants listed here as a dressing adjuvant, especially a wax. The polish composition is generally applied to a substrate including timber, vinyl or polyurethane flooring, ceramic styles, painted metals and the like. The application to the substrate is generally carried out by a spray, a roller, a mop or the like.

【0099】

In another embodiment of the invention, a plastic additive comprising an aqueous nanocomposite dispersion is intended. Examples of the plastic additive composition include those known in the art as processing aids and impact modifiers. In these embodiments, the nanocomposite polymer preferably has a glass transition temperature in the range of -50 ° C to 50 ° C. Plastic additives are generally prepared by mixing any pigment and, where appropriate, any of the adjuvants listed above as a dressing adjuvant and drying the composition to powder form. .. The plastic additive composition can generally be mixed with plastics such as polyvinyl chloride, polymethylmethacrylate and polypropylene by disruption or extrusion.

【0100】

In another aspect of the invention, the nanocomposite emulsion polymer can be prepared by a multi-stage emulsion polymerization method characterized in that at least two steps of different composition are polymerized in a continuous form. Such methods usually result in the formation of at least two mutually incompatible polymer compositions, thereby forming at least two phases within the polymer particles. Such particles include, for example, core / shell or core / sheath particles, core / shell particles with a shell phase that incompletely encapsulates the core, core / shell particles with multiple cores, and intrusive network particles. Consists of two or more phases of various shape dimensions. In all of these cases, the majority of the surface area of the particle is occupied by at least one outer phase and the inside of the particle is occupied by at least one inner phase. Each of the stages of the multistage emulsion polymer may include the same monomers, surfactants, chain transfer agents, etc. as disclosed herein above for the emulsion polymer. In the case of multi-stage polymer particles, the Tg for the purposes of the present invention is calculated by the Fox equation using the overall composition of the emulsion polymer, regardless of the number of stages or phases there. Polymerization techniques used to prepare such multistage emulsion polymers are well known in the art, such as US Pat. Nos. 4,325,856; 4,654,397; and 4,814,373.

【0101】

In another aspect of the invention, the nanocomposite emulsion polymer is a bimodal or multimodal particle size distribution, as taught in US Pat. Nos. 4,247,438; 4,657,966; and 5,498,655. Bimodal or multimodal molecular weight distributions as taught in 4,501,845 and 5,990,228, or non-spherical particles such as rods as taught in US Pat. No. 5,369,163, and US Pat. No. 4,791,151. It can be prepared by an emulsifying polymerization method performed in such a way as to produce multilobe particles, as taught in.

【0102】

In another aspect of the invention, the nanocomposite emulsion polymer, when dried, such as, for example, particles with single voids, multi-void particles, and particles with voids and a penetration network of polymers (polymer "sponge"). It can be prepared by a method of producing particles containing at least one void.

【0103】

In another aspect of the invention, the emulsion polymer of the nanocomposite can be prepared by a method of producing particles that can function in an alternative or in addition to providing binder functionality. Intended is an emulsion polymer that acts as a pigment dispersant or thickener / rheology modifier, such as an alkali-soluble, acid-soluble, and hydrophobically modified emulsion polymer.

【0104】

In certain aspects of the invention, the aqueous nanocomposite dispersion can be used in polymer compositions that incorporate high concentrations of acid functionality. These polymer compositions include thickeners (eg, US Pat. No. 4,421,902 and references therein), dispersants (eg, US Pat. Nos. 5,326,843 and 3,037,952 and references therein) and binders (eg, US Pat. Nos. 4,421,902 and references therein). For example, it is useful as an additive in an aqueous system as US Pat. No. 5,326,843 and US Pat. No. 4,876,313 (references therein), as well as coatings, inks, adhesives, and the like. When the nanocomposite composition prepared by the method of the invention is incorporated into a high acid polymer composition, the resulting polymer can increase in hardness. This imparts properties such as improved block resistance (ie, the dressing does not adhere to itself or other articles) when used in a coating composition. Ink binders composed entirely or partially of high acid polymers have enhanced heat seal resistance (block resistance at high temperatures) when the nanocomposite composition is added to the binder composition. ) And toughness. In yet another embodiment utilizing a high acid polymer, the nanocomposite compositions of the present invention are as described in a dry powder polymer cement modifier (eg, European Patent No. 0654454 and references therein). ) Can be used.

【0105】

Example Example 1 (Calcium / MAA / Na₂CO₃2% clay in order of addition-no homogenization) Aqueous nanocomposites, clay polymer dispersions were synthesized via the following methods: 612.00 g of deionized (DI) water in an empty reactor kettle, 5.08 g of polar surfactant (30% aqueous solution) and 20.40 g of PGV montmorillonite clay (Na)⁺Form) ("PGV" is the trade name for sodium montmorillonite clay sold by Nanocor in Arlington Heights, Illinois). The mixture is heated to 85 ° C and then Ca (OH) in 5.00 g of DI water.₂1.84 g of the above was added. The kettle was filled with half of the acid-containing monomer, or 7.55 g of methacrylic acid, followed by 3.10 g of buffer, sodium carbonate, as a result of which foaming was observed. In separate containers, a monomer emulsion containing 426.60 g of water, 36.90 g of polar surfactant (30% aqueous solution), 662.00 g of butyl acrylate, 342.70 g of methyl methacrylate, and 7.55 g of methacrylic acid was formed. A 55.80 g amount of monomeric emulsion was added to the kettle to form polymer seeds. Then, 4.03 g of ammonium persulfate (dissolved in 28 g of water) was added to initiate polymerization. Monomer emulsion was fed to the kettle to maintain a reactor temperature of 85 ° C. After the monomer supply was completed, the batch was cooled to 65 ° C. When reaching 65 ° C, 5.58 g of ferrous sulfate (0.15% aqueous) was added to the kettle. Then 1.12 g of 70% tert-butyl hydroperoxide in 20.00 g of water was added with 0.56 g of isoascorbic acid in 20.00 g of water. The temperature dropped below 45 ° C. Raise the pH of the batch to 7.5 with ammonium hydroxide (28% aqueous) and 4.77 g caisson LX (1.4% aqueous) manufactured with 6.20 g water. ) Was added. The resulting aqueous nanocomposite dispersion had a viscosity of 174 centipoise. The viscosity of the aqueous nanocomposite dispersion comprises a step of cation exchange, but is lower than that of the unmodified aqueous nanocomposite dispersion (see Example 8 above). The sample was filtered through a 100 mesh screen to remove large pieces of all agglomerates.

【0106】

Example 2 (Calcium / MAA / Na₂CO₃2% clay in order of addition-with homogenization) Kettle contents (clay, surfactant, water) manufactured by PRO250 Homogenizer (Pro Scientific, Monroe, Connecticut) ) Was homogenized for 20 minutes, and an aqueous nanocomposite dispersion was prepared by the polymerization method of Example 1.

【0107】

Example 3 (MAA / calcium / Na₂CO₃Half of the 2% clay) acid-containing monomer in the order of addition, or 7.55 g of methacrylic acid, 1.84 g of Ca (OH) in 5.00 g of DI water₂An aqueous nanocomposite dispersion was prepared by the polymerization method of Example 1 except that it was added before the addition of.

【0108】

Example 4 (MAA / calcium / Na₂CO₃2% clay in order of addition-with homogenization) Half of the acid-containing monomer, or 7.55 g of methacrylic acid, 1.84 g of Ca (OH) in 5.00 g of DI water₂An aqueous nanocomposite dispersion was prepared by the polymerization method of Example 2 except that it was added before the addition of.

【0109】

Example 5 (MAA-Na₂CO₃2% clay with addition; Ca²⁺(Post-addition) Aqueous nanocomposite dispersions were synthesized via the following methods: 612.00 g DI water, 5.08 g polar surfactant (30% aqueous solution), and 20.40 g in an empty reactor kettle. Was filled with montmorillonite clay (Na + morphology). The mixture was heated to 85 ° C. The kettle was then filled with 7.55 g of methacrylic acid, followed by 3.10 g of sodium carbonate (foaming was observed). A monomer emulsion containing 426.60 g of water, 36.90 g of polar surfactant (30% aqueous solution), 662.00 g of butyl acrylate, 342.70 g of methyl methacrylate, and 7.55 g of methacrylic acid was formed in separate containers. A 55.80 g amount of monomeric emulsion was added to the kettle to form polymer seeds. Then, 4.03 g of ammonium persulfate (dissolved in 28 g of water) was added to initiate polymerization. The monomer emulsion was fed to the kettle to maintain a reactor temperature of 85 ° C. After the monomer supply was complete, the batch was cooled to 65 ° C and when 65 ° C was reached, 5.58 g ferrous sulfate (0.15% aqueous) was added to the reactor. Then 1.12 g of 70% tert-butyl hydroperoxide in 20.00 g of water was added with 0.56 g of isoascorbic acid in 20.00 g of water. The temperature was lowered below 45 ° C. Raise the pH of the batch to 7.5 with ammonium hydroxide (28% aqueous) and kill bacteria (4.77 g KATHON LX (1.4% aqueous) made with 6.20 g water) Was added. The sample was filtered through a 100 mesh screen to remove large pieces of all agglomerates. 1.84 g of Ca (OH) in 5.00 g of DI water₂Was slowly added to the latex.

【0110】

Example 6 (MAA-Na₂CO₃No clay with addition; Ca²⁺Latex was prepared by the polymerization method of Example 4 except that it did not contain clay.

【0111】

Example 7 (added clay or Ca²⁺None) Latex was prepared by the polymerization method of Example 5, except that no post-calcium addition was included. Further, the total amount of methacrylic acid input was incorporated into the monomer emulsion.

【0112】

Example 8 (2% PGV; added Ca²⁺None) An aqueous nanocomposite dispersion was prepared by the polymerization method of Example 6 except that 2% PGV clay (based on the weight of the monomer) was incorporated into the monomer emulsion and homogenized for 20 minutes prior to polymerization. The resulting aqueous nanocomposite dispersion had a viscosity of 480 centipoise. The viscosity of the aqueous nanocomposite dispersion was higher than that of the aqueous nanocomposite dispersion that included or modified the cation exchange step (see Example 1).

【0113】

The nanocomposites or polymers of Examples 1-8 were made on sample films of unblended dressings and tested for maximum tensile strength and elongation properties. Test data for each film is available at Tinius Olsen Benchtop Universal Testing Machine (Willow Grove, Pennsylvania, Pennsylvania). -Collected by Machine Company (Tinius Olsen Benchtop Universal Testing Machine Company). The sample film was pulled at a speed of 5.08 cm / min. The tester was calibrated for film thickness, width, and weight for each sample film. The initial distance between the clamps supporting each sample film was 2.54 cm. The test was conducted in a controlled environment room at a temperature of 22 ° C and a humidity of 50%. Tension measurements for each film are provided in Table I below. Table I: Tension property pair, clay addition method [Table 1]<img file="JP2004509986A_D0001.tif" />(1) Tension_maximumThe value is +/- 3 points. Samples are not averaged.

【0114】

As the results in Table I show, the addition of a second cation, or Ca²⁺The multivalent ion slurry containing, improved the overall tensile properties and almost doubled the maximum tensile strength of the composition, regardless of whether the composition contained clay (Compare Example 7 to Example 6). To do). Similarly, Ca in clay-containing compositions or nanocomposite dispersions²⁺The addition of the multivalent ion slurry containing also significantly improved the overall tensile properties of the nanocomposite (compare Example 8 with 3). In some embodiments of the invention, such as Example 1, the maximum tensile strength of the nanocomposite is, as in Example 7, no clay, Ca.²⁺Approximately 5.5 times that of similar polymers without the addition of slurry.

【0115】

Figure 1 shows the tensile strength (psi) vs. elongation for the various polymer or nanocomposite compositions in Table I. As Figure 1 shows, Ca²⁺When containing both clay in the form of a slurry and a second cation, the modulus of elasticity is even higher than that of a polymer lacking one or both of these components, as evidenced by the high initial gradient of the strength / elongation curve. Produced the material of.

【0116】

Example 9 Emulsion-based polymer composition as well as the same polymer and Na²⁺Two nanocomposite compositions containing cloucite clay were prepared by the methods of the invention. "Sodium cloisite" is the trade name for sodium montmorillonite clay available from Southern Clay Products in Gonzales, Texas. FIG. 2 provides illustrated representative examples of tensile strength (psi) vs. elongation for these compositions. The nanocomposite compositions shown in FIG. 2 differ in the order in which the polymerizable polar monomers or acids are added. In FIG. 2, the nanocomposite represented by a circle and the polymer represented by a square are added by standard acid addition, i.e. all of the polymerizable acids are added to the monomer emulsion. In contrast, the nanocomposites represented by the triangles represent a stepwise acid approach in which half of the acid is added to the clay dispersion and half of the acid is added to the monomeric emulsion. As shown in Figure 2, the nanocomposites with the gradual addition of acids showed even higher modulus than the polymers or nanocomposites according to the standard acid addition approach.

【0117】

Example 10-Magnesium Example (Magnesium / MAA / Na)₂CO₃2% clay in order of addition-no homogenization) Aqueous nanocomposite dispersions were synthesized via the following methods: 612.00 g of DI water, 5.08 g of polar surfactant (30) in an empty reactor kettle. % Aqueous solution), and 20.40 g of montmorillonite clay (Na + form). The mixture is heated to 85 ° C and then 1.45 g of Mg (OH) in 5.00 g of DI water.₂Was then added: the kettle was then charged with 7.55 g of methacrylic acid, followed by 3.10 g of sodium carbonate (foaming was observed). Form a monomer emulsion in a separate container containing 426.60 g of water, 36.90 g of anionic surfactant (30% aqueous solution), 662.00 g of butyl acrylate, 342.70 g of methyl methacrylate, and 7.55 g of methacrylic acid. did. A 55.80 g amount of monomeric emulsion was added to the kettle to form polymer seeds. Then, 4.03 g of ammonium persulfate (dissolved in 28 g of water) was added to initiate polymerization. The monomer emulsion was fed to the kettle to maintain a reactor temperature of 85 ° C. After the monomer supply was complete, the batch was cooled to 65 ° C and when 65 ° C was reached, 5.58 g ferrous sulfate (0.15% aqueous) was added to the reactor. Then 1.12 g of 70% tert-butyl hydroperoxide in 20.00 g of water was added with 0.56 g of isoascorbic acid in 20.00 g of water. The temperature was lowered below 45 ° C. The pH of the batch was raised to 7.5 with ammonium hydroxide (28% aqueous) and a bacteriostatic agent (4.77 g KATHON LX (1.4% aqueous) with 6.20 g water) was added. .. The sample was filtered through a 100 mesh screen to remove large pieces of all agglomerates.

【0118】

Example 11 (Calcium / MAA / Na₂CO₃An aqueous nanocomposite dispersion was prepared by the polymerization method of Example 1 except that 5% clay) 5% PGV clay was used in the order of addition. The nanocomposite or polymer of Example 11 was made on a sample film of unblended dressing and tested for tensile properties of maximum tensile strength according to the methods shown in Table I and FIG. The resulting tensile strength was 506 psi. The viscosity of the aqueous nanocomposite dispersion was 294 centipoise. The viscosity of the aqueous nanocomposite dispersion was lower than that of the aqueous nanocomposite dispersion containing or not modifying the cation exchange step (see Example 12 below).

【0119】

Example 12 (5% PGV; added Ca²⁺None) An aqueous nanocomposite dispersion was prepared by the polymerization method of Example 8 except that 5% PGV clay was used. The nanocomposite or polymer of Example 12 was made on a sample film of unblended dressing and tested for tensile properties of maximum tensile strength according to the methods shown in Table I and FIG. The resulting tensile strength was 108.7 psi. The viscosity of the aqueous nanocomposite dispersion was 2300 centipoise. The viscosity of the aqueous nanocomposite dispersion was higher than that of the aqueous nanocomposite dispersion containing or modified cation exchange steps (see Example 11 above).

【0120】

Reference Example 13 Latex was synthesized via the following method: in an empty reactor kettle, 436.00 g of DI water, 5.08 g of anionic surfactant (30% aqueous solution), and 3.10 g of sodium carbonate. Was filled. A monomer emulsion containing 626.60 g of water, 36.90 g of anionic surfactant (30% aqueous solution), 654.67 g of butyl acrylate, 350.00 g of methyl methacrylate, and 15.10 g of methacrylic acid was formed. The kettle contents were heated to 85 ° C. A 55.80 g amount of monomeric emulsion was added to the kettle to form polymer seeds. Then, 4.03 g of ammonium persulfate (dissolved in 28 g of water) was added to initiate polymerization. The monomer emulsion was fed to the kettle to maintain a reactor temperature of 85 ° C. After the monomer supply was complete, the batch was cooled to 65 ° C and when 65 ° C was reached, 5.58 g ferrous sulfate (0.15% aqueous) was added to the reactor. Then 1.12 g of 70% tert-butyl hydroperoxide in 20 g of water was added with 0.56 g of isoascorbic acid in 20.00 g of water. The temperature was lowered below 45 ° C. Raise the pH of the batch to 7.5 with ammonium hydroxide (28% aqueous) and add a bacteriostatic agent (4.77 g KATHON LX (1.4% aqueous) with 6.20 g water). did. The sample was filtered through a 100 mesh screen to remove large pieces of all agglomerates.

【0121】

Example 14 (Calcium / MAA / Na₂CO₃/ Na₂S₂O₄2% clay in the order of addition) Add a sufficient amount of reduced sodium hydrosulfite to the reactor in an aqueous solution to Fe all the iron in the clay sample kettle.^IIAn aqueous nanocomposite dispersion was prepared by the polymerization method of Example 11 except for reduction to morphology. The contents of the reactor were stirred for 10 minutes after the addition of the reducing solution; a color change to green / gray was observed indicating iron reduction. The resulting nanocomposite was made into a sample film of unblended dressing and tested for tensile properties of maximum tensile strength according to the methods shown in Table I and FIG. The resulting tensile strength was 44.0 psi. The viscosity of the aqueous nanocomposite dispersion was 428 centipoise. The viscosity of the aqueous nanocomposite dispersion was lower than that of the aqueous nanocomposite dispersion containing or not modifying the cation exchange step (see Example 12 above).

【0122】

Example 15 (Calcium / MAA / Na₂CO₃/ Na₂S₂O₄5% clay in order of addition) Aqueous nanocomposites, clay polymer dispersions are synthesized via the following methods: 612.00 g of deionized (DI) water, 5.08 g of polarity in an empty reactor kettle. Surfactant (30% aqueous solution), and 20.40 g of PGV sodium montmorillonite clay (Na)⁺Form) is filled. The mixture is heated to 85 ° C and then 1.84 g of Ca (OH) in 5.00 g of DI water.₂Was added. The kettle is filled with half of the acid-containing monomer, or 7.55 g of methacrylic acid, followed by 3.10 g of buffer, sodium carbonate, as a result of which foaming is observed. A monomer emulsion containing 426.60 g of water, 36.90 g of polar surfactant (30% aqueous solution), 662.00 g of butyl acrylate, 342.70 g of methyl methacrylate, and 7.55 g of methacrylic acid was formed in separate containers. A 55.80 g amount of monomeric emulsion was added to the kettle to form polymer seeds. Then, 4.03 g of ammonium persulfate (dissolved in 28 g of water) was added to initiate polymerization. Monomer emulsion, 2.0 g aqueous solution of 70% tert-butyl hydroperoxide in 40 g water, and 40 g water so that the reactor temperature of 65 ° C is maintained through the three partially separated inlets. Feed the kettle with 2 g of isoascorbic acid. After the monomer supply is complete, 5.58 g ferrous sulfate (0.15% aqueous) is added to the reactor. Then 1.12 g of 70% tert-butyl hydroperoxide in 20.00 g of water is added with 0.56 g of isoascorbic acid in 20.00 g of water. Lower the temperature below 45 ° C. Raise the pH of the batch to 7.5 with ammonium hydroxide (28% aqueous) and add a bacteriostatic agent (4.77 g KATHON LX (1.4% aqueous) with 6.20 g water). To do.

[Simple explanation of drawings]

[Figure 1]

Table I shows the tensile strength (psi) vs. elongation for various polymer or nanocomposite compositions.

[Figure 2]

The tensile strength (psi) vs. elongation ratio for these compositions is shown.