Process for the preparation of polyvinylidene chloride layered silicate nanocomposites

(54) Title: SILICATE NANOCOMPOSITE IN LAYERS WITH POLYVINYLIDENE CHLORIDE AND FILM PREPARED WITH IT (30) Unionist Priority: 27/01/2006US 11 / 341,695, 03/29/2005 US 60 / 666,213 (73) Holder (s) : cryovac, inc (72) Inventor (s): solomon bekele (74) Attorney (s): Dannemann, Siemsen, Bigler & Ipanema Moreira (86) International Request: pct us20060H606de28 / 03/2006 (87) International Publication: wo 2006 / i05273of 10/05/2006 (57) Summary: layered silicate nanocomposite WITH POLYVINYLIDENE CHLORIDE AND FILM PREPARED WITH IT. A polymeric film includes at least one layer, this including a layered silicate nanocomposite composition with polyvinylidene chloride, the composition including 100 parts, by weight of the composition, of a layered silicate nanocomposite with polyvinylidene chloride; from 0.1 to 10 parts, by weight of the composition, of a stabilizer; and from 0.1 to 10 parts, by weight of the composition, of a polymeric processing aid. Alternatively, the polymeric film includes at least one layer, at least one layer including a layered silicate nanocomposite composition with polyvinylidene chloride, the composition including 100 parts, by weight of the composition, of a layered silicate nanocomposite with chloride polyvinylidene; and from 0.1 to 10 parts, by weight of the composition, of a fatty acid soap. You can prepare a blister pack with any of these films.

Descriptive Report of the Patent of Invention for NANOCOMPOSITE OF SILICATE IN LAYERS WITH POLYVINYLIDENE CHLORIDE AND FILM PREPARED WITH IT.

This claim claims the benefit of the North American series n provisional order⁹ 60/666213, filed on March 29, 2005, the content of which is incorporated herein by reference.

Field of the Invention

The present invention relates to a layered silicate nanocomposite with polyvinylidene chloride and a composition and film prepared with it, such as a film suitable for packaging pharmaceutical products in blister packs.

Background of the Invention

Conventional blister packs typically include a base with one or, more commonly, a plurality of recesses that are surrounded by a lip and a lid attached to the lip. Pills, capsules or other contents are accommodated in the respective recesses and can be removed from there by (1) pressing on the respective recess, thus causing the contents to penetrate the lid (usually an aluminum foil or similar), or by (2) removal of the cover part over the recess, thus gaining access to the contents of the recess.

In practice, a base is formed with recesses and a rim that defines the base material between the recesses; the base recesses are filled with pills and the like; the base.com the filled recesses are covered with a lid; and the lid is glued or otherwise adhered to the edge of the base.

The base of the blister pack is sometimes composed of an inner part (to be adhered to the cap) of ACLAR® PTFE (polychlorinated trifluoroethylene), a material that is very expensive and with less than optimal oxygen barrier properties. This material has a moisture vapor transmission rate (MVTR) of typically about 0.4 grams / m²to 25 micrometers (1 mil) thick. The outer part of the base is often PVC (polyvinyl chloride) about 250 micrometers (10 mils) thick. PVC, polyamides, polioiefins, polyesters are other materials that can be used to prepare the base. An aluminum foil can be added to the base.

The cover is typically made of aluminum foil or aluminum foil laminate. Aluminum foil is a preferred material for blister packaging caps, as the thickness of the material used requires relatively little force to break it. Consequently, the energy for penetration is low, and aluminum essentially exhibits no elasticity. Plastic laminates can also be used for the cover.

Some blister packs have a lid with a line of weakness in the region of each recess. In others, each recess can be covered with an individual cap segment. Within each line of weakness or in each cap segment there may be a tab to hold that allows the individual recess to be exposed by tearing off the cap segment.

The preparation of a vinylidene chloride copolymer, often called saran or PVdC, in a PVdC composition capable of forming a packaging film with a low moisture vapor transmission rate (MVTR), and also a low transmission rate oxygen (OTR) would be desirable for applications such as blister packaging of pharmaceutical products sensitive to both oxygen and moisture.

Stabilizers are often used in the formulation of compositions based on PVdC. These stabilizers reduce the thermal degradation of PVdC formulations during extrusion. Unfortunately, a compromise between OTR and thermal stability is sometimes necessary in the design of these formulations. Thus, a composition with increased amounts of a stabilizer sometimes results in increased thermal stability, but at the expense of the oxygen barrier properties. Conversely, a better (lower) OTR can be obtained by reducing the relative amounts of stabilizer in the formulation, but this can result in a less stable PVdC composition.

US Patent no.^s 6,673,406 (Bekele), incorporated herein by reference in its entirety, has a composition and a film in which a hydrophilic clay is mixed, such as a montmorillonite modified with a PVdC, and the mixture is incorporated in a polymeric film with at least one layer.

Nanosilicates are available in natural (clays) and synthetic types.

Natural types have been found to tend to disperse poorly when mixed in bulk in PVdC. Because of this poor dispersibility, the oxygen barrier property of a film prepared with the natural PVdC / nanosilicate mixture will not necessarily be increased.

Modified types of nanosilicates have better dispersion characteristics than natural types and, consequently, generally better oxygen barrier. However, the surface treatments used to modify nanosilicates are based on quaternary alkyl ammonium chloride. Regardless of the alkyl component of this salt, it has been found that this material adversely affects the thermal stability of the PVdC to which it has been mixed.

It has also been found that there are load limitations with respect to both natural and modified types of nanosilicates when using an extrusion coating process. Extrusion coating is a well-known process for preparing contract bags containing PVdC. In general, in an extrusion coating process, less than 4% by weight of the PVdC mixture can be composed of nanosilicates.

Consequently, it is desirable to resolve the issues of dispersibility, thermal stability and load generated by the bulk mixing of nanosilicates in PVdC.

Summary of the Invention

In a first aspect, the composition comprises a layered silicate nano4 composite with polyvinylidene chloride.

In a second aspect, the polymeric film comprises at least one layer, this comprising a layered silicate nanocomposite with polyvinylidene chloride.

In a third aspect, the polymeric film comprises at least one layer, this comprising the layered silicate nanocomposite composition with polyvinylidene chloride, the composition comprising 100 parts, by weight of the composition, of a layered silicate nanocomposite with chloride polyvinylidene; from 0.1 to 10 parts, by weight of the composition, of a stabilizer; and from 0.1 to 10 parts, by weight of the composition, of a polymeric processing aid.

In a fourth aspect, the polymeric film comprises at least one layer, at least one layer comprising a layered silicate nanocomposite composition with polyvinyl chloride. but the composition comprising 100 parts, by weight of the composition, of a layered silicate nanocomposite with polyvinylidene chloride; and from 0.1 to 10 parts, by weight of the composition, of a fatty acid soap.

In a fifth aspect, the blister pack comprises a base, the base comprising a plurality of recesses, and an edge around the recesses; a lid attached to the rim; and content arranged in the respective recesses; wherein at least one of the base or cap comprises a layered silicate nanocomposite composition with polyvinylidene chloride, the composition comprising 100 parts, by weight of the composition, of a layered silicate nanocomposite with polyvinylidene chloride; from 0.1 to 10 parts, by weight of the composition, of a stabilizer; and from 0.1 to 10 parts, by weight of the composition, of a polymeric processing aid.

In a sixth aspect, the blister pack comprises a base, the base comprising a plurality of recesses, and a rim around the recesses; a lid attached to the rim; and content arranged in the respective recesses; wherein at least one of the base or cap comprises a layered silicate nanocomposite composition with polyvinylidene chloride, the composition comprising 100 parts, by weight of the composition, of a layered silicate nanocomposite with polyvinylidene chloride; and from 0.1 to 10 parts, by weight of the composition, of a fatty acid soap.

In a seventh aspect, the layered silicate nanocomposite composition with polyvinylidene chloride comprises 100 parts, by weight of the composition, of a layered silicate nanocomposite with polyvinylidene chloride; from 0.1 to 10 parts, by weight of the composition, of a stabilizer; and from 0.1 to 10 parts, by weight of the composition, of a polymeric processing aid.

In an eighth aspect, the layered silicate nanocomposite composition with polyvinylidene chloride comprises 100 parts, by weight of the composition, of a layered silicate nanocomposite with polyvinylidene chloride; and from 0.1 to 10 parts, by weight of the composition, of a fatty acid soap.

Definitions

Layered silicate nanocomposite with polyvinylidene chloride and layered silicate nanocomposite with PVdC and others here refers to a polymer prepared in situ in a suspension process or an emulsion process. The in situ process allows a polymer penetration that results in a finite expansion of the silicate crystals, producing intercalated polymer / clay hybrids. With exfoliation, a wide penetration of the polymer and delamination of the silicate crystallites are achieved, resulting in nanoscale silicate layers suspended in a PVdC matrix. In a polymer preparation method, a high polarity aqueous dispersion of nano clay is pre-dispersed in the monomer premix before polymerization. The nanoclay may be a kaolin, talcum powder, smectite, vermiculite or mica. The pre-dispersion of the nano clay can be as high as 10% by weight of the total monomer content of the suspension. After pre-mixing is prepared, the conventional polymerization and post-polymerization steps are carried out. The result is a vinylidene chloride copolymer with the vinylidene chloride monomer and a comonomer such as vinyl chloride, styrene, vinyl acetate, acrylonitrile and C1 - C12 acrylic esters of (meth) acrylic acid (eg methyl acrylate) , butyl acrylate, methyl methacrylate and others) and also including up to 10%, by weight of the composition, of a nanosilicate.

(meth) acrylic acid refers here to both acrylic and acid-methacrylic acid;

(met) acrylate refers here to both acrylate and methacrylate;

polymer here refers to the product of a polymerization reaction and includes homopolymers, copolymers, terpolymers, tetrapolymers and others;

copolymer refers here to a polymer formed by the polymerization reaction of at least two different monomers and includes random copolymers, block copolymers, grafted copolymers and the like;

ethylene / alpha-olefin copolymer (EAO) refers here to ethylene copolymers with one or more comonomers selected from C₃ to C10 alpha-olefins, such as propene, butene-1, hexene-1, octene-1 and others, where the copolymer molecules comprise long polymer chains with relatively few side chain branches originating from the alpha-olefin which has reacted with ethylene . This molecular structure must be contrasted with conventional low or medium density and high pressure polyethylene, which are highly branched with respect to EAOs, and with high pressure polyethylene containing both long and short chain branches . EAO includes heterogeneous materials such as linear medium density polyethylene (LMDPE), linear low density polyethylene (LLDPE) and very low or ultra low density polyethylene (VLDPE and ULDPE), such as DOWLEX® or ATTANE® resins supplied by Dow, ESCORENE resins ® or EXCEED® provided by Exxon; as well as linear homogeneous ethylene / alpha olefin copolymers (HEAO), such as TAFMER® resins supplied by Mitsui Petrochemical Corporation, EXACT® resins supplied by Exxon, or long chain branched resins (HE7

AO) AFFINITY® supplied by Dow Chemical Company, or ENGAGE® resins supplied by DuPont Dow Elastomers;

packing¹¹ here refers to a film configured around a product:

film refers here to plastic mesh materials with a thickness of 0.50 mm (20 mils) or less, such as 0.25 mm (10 mils) or less;

bonding layer here refers to a layer of a film that may be involved in bonding the film to itself or another layer;

bonding refers here to a connection of a first film surface to a second film surface created by heating (for example, by means of a heated bar, hot air, infrared radiation, ultrasonic bonding and others) of the respective surfaces to at least their respective bonding start temperatures;

barrier here refers to a layer of a film that can significantly delay the transmission of one or more gases (for example, O2);

abuse layer refers here to a layer of a film that can resist abrasion, perforation and / or other potential causes of reduced packaging integrity and / or potential causes of reduced quality of packaging appearance;

bonding layer here refers to a layer of a film that can provide interlayer adhesion to adjacent layers that include otherwise non-adherent or poorly adherent polymers;

volume layer refers here to a layer of a film that can increase the abuse resistance, stiffness or modulus of a film;

lamination refers here to the bonding of two or more layers of film to each other, for example, using a polyurethane adhesive;

total free contraction means the percentage of dimensional change in a 10 cmx10 cm film specimen, contracted at a specified test temperature, such as 85 ° C (185 ° F), with quantitative determination being performed according to ASTM D 2732 , as set out in the 1990 Yearbook of ASTM Standards, vol. 08.02, 368-371, the entire exposition of which is incorporated herein by reference. Total free contraction refers to the totality of free contraction in both the longitudinal and transverse directions.

Machine direction refers here to the direction along the length of a film, that is, in the direction of the film when it is formed during extrusion and / or coating: and transverse direction refers here to the direction through the film, that is, the direction that is perpendicular to the machine direction.

Linear low density polyethylene (LLDPE) here refers to a polyethylene with a density of 0.917 to 0.925 grams per cubic centimeter, prepared by Zeigler / Natta catalysis.

Linear medium density polyethylene (LMDPE) refers here to a polyethylene with a density of 0.926 grams per cubic centimeter to 0.939 grams per cubic centimeter, prepared by Zeigler / Natta catalysis.

The term orientation ratio (that is, the product of the extent to which a film is oriented in several directions, usually two directions perpendicular to each other) is used when describing the degree of orientation of a given film. The orientation in the machine direction is called stretching, while the orientation in the transversal direction is called stretching. For films extruded through an annular die, elongation is achieved by blowing the film to produce a bubble. For these films, the stretch is obtained by passing the film through two sets of rollers with a driven wedge angle, with the downstream assembly having a higher surface speed than the upstream assembly, with the resulting stretching ratio being the surface speed of the set downstream of rollers with a wedge angle divided by the surface speed of the set upstream of rollers with a wedge angle.

All percentages of compositions used herein are presented based on weight, unless otherwise designated. Brief Description of Drawings

A detailed description of the modalities of the invention follows, with reference to the accompanying drawings, in which:

Figure 1 is a schematic cross section of a monolayer film;

Figure 2 is a schematic cross section of a two-layer film;

Figure 3 is a schematic cross section of a three-layer film;

Figure 4 is a schematic cross section of a four-layer film;

Figure 5 shows a longitudinal section through a blister pack;

Figure 6 shows a plan view of the blister pack of Figure 5;

Figure 7 shows a cross section through the blister pack of Figure 6; and

Figure 8 shows a fragmented and expanded cross-sectional view of the blister pack of Figure 6.

Detailed Description of the Invention

In Situ Polymerization

Clays are naturally occurring minerals and, therefore, their composition is highly variable. The purity of the clay will affect the final properties of the composite. Many clays are aluminosilicates that have leaf-like layered structures and consist of tetrahedral S1O4 silica bound to AIO alumina.₆ octahedral in many ways. A 2: 1 tetrahedron for octahedron results in smectite clays. Among smectites, the most common is montmorillonite (bentonite). Other metals, such as magnesium, can replace aluminum in the crystalline structure. These magnesium silicate clays are hectorites. Depending on the composition of the clay, the sheets or layers carry a charge on the surface and edges. This charge is balanced by counter ions that are located in the interlayer spacing of the clay. The thickness of the layers or platelets is on the order of 1 nm, and the aspect ratio range is 100 - 1,500. The molecular weight of platelets [1.3 x 10⁸] is considerably higher than that of most polymers. They also have very high surface areas, several hundred square meters per gram. They also have ion exchange capabilities. Clays, due to their charged nature, in general are highly hydrophilic species and, therefore, are incompatible with polymeric systems. Thus, a necessary requirement to make these clays compatible with polymers is to change their polarity and make them organophilic. This is achieved by exchanging hydrophilic clay ions with an organic cation, such as an alkylammonium ion. In montmorillonite, the sodium ions in the clay can be exchanged for an amino acid, such as 12-aminododecanoic acid [ADA].

At⁺-ARGILA + HO₂CR-NH₃+ C | · - HO₂CR-NH₃⁺ -ARGILA +

NaCl

In addition to montmorillonite and hectorite, other synthetic clays, such as hydrotalcite, can be produced in a very pure form and can bring a positive charge on the platelet.

The final nanocomposite can be intercalated or exfoliated.

In an interleaved system, the organic polymer (PVdC) can be inserted between the clay layers, so that the inter-platelet spacing expands, but the layers still maintain a well-defined spatial relationship with each other.

In exfoliation, the plates are completely separated, and the individual layers are distributed throughout the polymeric matrix (PVdC).

With the modification of the surface polarity of the clay, the onion ions can allow a thermodynamically favorable penetration of polymer precursors in the interlayer region. The ability of onion ions to assist in the delamination of clay depends on its chemical nature, such as its polarity. For positively charged clays, such as hydrotalcite, the modification by onion salt is replaced by the use of an ionic surfactant11. Other types of clay modifications include ion-dipole interactions, silane coupling agents and the use of block copolymers and graft copolymers.

PVdC-nano-clay nanocomposites with respect to the invention can be prepared by suspension polymerization of free radicals or emulsion polymerization of free radicals. A nano-clay slurry is pre-dispersed in an aqueous phase with appropriate suspending agents, and the pH is adjusted from 6 to 8. This slurry is pumped into the polymerization reactor when the polymer conversion has reached at least 20 %. The reaction continues after adding the nanoclay slurry until the desired polymer conversion is achieved.

Another method that can be used is to add the nanoclay slurry to the reactor after the specified polymer conversion is achieved, and the reaction is terminated.

In both cases, the appropriate reaction agitation is maintained, or increased if there is an increase in the viscosity of the system, and sufficient time must be allowed to achieve the desired exfoliation of the nano clay.

The typical steps of suspension polymerization of PVdC can be followed. These steps include the preparation of monomers, such as vinylidene chloride (CH₂ = CCI₂) and vinyl chloride, and the use of water, initiators, suspending agents, antioxidants and others. Monomeric units can also be derived from styrene, vinyl acetate, acrylonitrile and Ci - Ci esters₂ (meth) acrylic acid alkyls (for example, methyl acrylate, butyl acrylate, methyl methacrylate and others). The production of PVdC (saran) is well known in the art. The preparation of the reactor includes purging with nitrogen, heating to the reaction temperature, stirring the water mixture, monomers and other additives at the desired stirring speed. The reaction is then started, and the reaction is carried out to the defined conversion.

After the reaction is complete, the polymer can be freed from unreacted monomers, washed and separated from water and dried. The dry composite nano12 is then formulated with appropriate processing additives and made into a film. Processing additives can be added to the reactor or mixed later.

Figure 1 of this report shows a monolayer film 10 with a single layer 11.

Layer 11 comprises the layered silicate nanocomposite with polyvinylidene chloride of the invention.

Figure 2 shows a two-layer film 20 with a layer 21 and a layer 22.

Layer 21 comprises the layered silicate nanocomposite with polyvinylidene chloride shown above for layer 11 of figure 1.

Layer 22 may comprise any suitable polymeric material, such as a thermoplastic polymeric material, such as an olefinic polymer, such as an ethylene polymer, such as an ethylene homopolymer or copolymer, such as an ethylene / alpha-olefin copolymer, such as ethylene / alpha- copolymers heterogeneous or homogeneous olefin.

Layer 22 may comprise an olefinic polymer or copolymer such as an ethylene / vinyl acetate copolymer; ethylene / alkyl acrylate copolymer, ethylene / (meth) acrylic acid copolymer; ionomer; propylene homopolymer and copolymer; and butylene homopolymer and copolymer.

Mixtures of any of the materials exposed here for layer 22 can be included in layer 22.

Figure 3 shows a three-layer film 30 with layers 31, 32 and 33.

Layer 31 comprises the layered silicate nanocomposite with polyvinylidene chloride shown above for layer 11 of figure 1.

Layers 32 and 33 comprise any of the polymers shown above for layer 22 of figure 2.

The layers 32 and 33 can be the same or they can be different.

The difference may be in composition, one or more physical properties, thickness, quantity or type of additives, degree of crosslinking or orientation or other. For example, layer 32 can comprise ethylene / vinyl acetate with 6% vinyl acetate, whereas layer 33 can comprise ethylene / vinyl acetate with 9% vinyl acetate. As another example, As another example, layer 32 can comprise an ethylene / vinyl acetate with 6% vinyl acetate, whereas layer 33 can comprise an ethylene / alpha-olefin copolymer. Film structures according to the invention can therefore be represented as A / B / A or A / B / C, where A, B and C each represent a separate layer of a multilayer film.

A multilayer film structure according to an embodiment of the present invention has at least four layers. This film 40 (see figure 4) includes a glue layer 43, a volume layer 44, an O barrier layer₂ 41 comprising the silicate nanocomposite layered with polyvinylidene chloride, and an abuse layer 42. Layers 43, 41 and 42 can correspond in composition to any of layers 22, 32 and 33 of the preceding figures. The volume layer 44 can be arranged between the glue layer 43 and the O barrier layer₂ 41, and the O barrier layer₂ 41 can be arranged between the volume layer 44 and the abuse layer 42. If desired, the layers, comprising polymeric adhesives, can be arranged between the glue layer 43 and the volume layer 44, as well as between the barrier layer of the₂ 41 and the abuse layer 42.

The volume layer 44 can comprise any of the materials exposed for layers 32 and 33 of figure 3.

The film of the present invention can have any desired total thickness, as long as the film has the desired properties for the intended end use. Thicknesses can vary from 2.5 to 500 mi30 meters (0.1 to 20 mils), as well as from 7.5 to 400 micrometers (0.3 to 16 mils),

12.5 to 300 micrometers (0.5 to 12 mils), 17.5 to 200 micrometers (0.7 to 8 mils), 25 to 150 micrometers (1.0 to 6 mils) and 32.5 to 100 micrometers ( 1.3 to 4 mils).

Figure 6 shows a conventional blister pack 50 for packaging pharmaceutical products, such as tablets. The cover 52 is attached to the base 56 on the edges 54 of the base 56 (see also figure 5). A plurality of recesses 58, each intended to accommodate a tablet, capsule or other pharmaceutical product, is covered by the cap 52. The cap 52 is conventionally of a metal or foil. Figure 5 shows a longitudinal section through the blister pack 50. The base 56 with the recesses 58 makes contact with the cap 52 on the edges 54. In the region of the edges 54, the cap 52 is joined to the base 56, for example, by gluing or adhesive bonding (glue / adhesive not shown for clarity purposes) ). Figure 7 shows a cross section through the blister pack 50 with its base 56, lid 52 and recesses 58.

Figure 8 shows a fragmentary and expanded section view of the blister pack 50, using film of the present invention. The base 56 is composed of an inner film 62 and an outer film 60.

The inner film 62 comprises the film of the present invention. The film 62 can be a collapsed flat film. This film can provide good (low) MVTR, as well as low OTR for pharmaceutical applications.

The outer film 60 can be any suitable film, such as the PVC (polyvinyl chloride) film used in some blister packs.

Alternatively, the base may comprise a single film comprising the film of the present invention, without the need for an additional film 60.

In another alternative, the film of the invention may comprise the outer film, and another film may form the inner film 62.

Those skilled in the art will understand that various combinations can be made, as long as a film of the invention is present in the base.

In yet another embodiment, the film of the invention can form the lid of the blister pack, and a conventional sheet or plastic film can form the base.

Films 63 and 60 can be bonded together by any suitable means, such as lamination, co-extrusion, extrusion coating, extrusion lamination, thermal bonding, glue bonding and others.

The base of the present blister pack can be embossed, deep drawn or vacuum shaped.

The cover may, in one embodiment, comprise an aluminum foil or a laminate containing an aluminum foil, or a plastic that exhibits low elasticity and poor elongation properties.

The base may have, for example, 6 to 30 recesses in the form of cups or plates. The recesses are surrounded by a rim, the rim forming an interconnected smooth plane. The base can be prepared, for example, as an endless strip with the contents in the recesses and placed together with the lid, in particular in the form of a lid sheet, also in the form of an endless strip. The cover covers the base completely and, for example, by gluing or adhesive bonding, is attached to the base at the edges. The lid can be glued or adhesive-bonded to the rim over the entire area or, by choosing a special bonding tool or bonding pattern for the purpose, that bonding or bonding can be only partial. Then, the endless strip of base with lid can be cut to the desired size. This can be done, for example, using a stamping tool. At the same time, the blister pack can be contoured externally, or it is possible to give weakness to the cap material or base to allow the blister pack to be folded or to create cap segments, making it easy to remove the cap segment and removal of the content is possible.

The layered silicate nanocomposite with polyvinylidene chloride of the invention can include any suitable vinylidene chloride-containing copolymer, i.e., a copolymer that includes monomeric units derived from vinylidene chloride (CH₂ = CCI₂) and also monomeric units derived from one or more of vinyl chloride, styrene, vinyl acetate, acrylonitrile and Ci - Ci esters₂ alkyls of (meth) acrylic acid (for example, methyl acrylate, butyl acrylate, methyl methacrylate and others). Thus, suitable PVdC resins include, for example, one or more of vinylidene chloride / vinyl chloride copolymer, vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer, vinylidene chloride / acrylate copolymer butyl, vinylidene chloride / styrene copolymer and vinylidene chloride / vinyl acetate copolymer. The percentage by weight of the vinylidene chloride monomer is preferably 75% to 96% by weight of the copolymer, excluding the nanosilicate content, the percentage by weight of the second monomer, for example, vinyl chloride, is preferably , from 4% to 25% by weight of the copolymer, excluding the nanosilicate content.

The stabilizer of the invention can include one or more of:

1) epoxidized compounds, such as epichlorohydrin / bisphenol A, epoxidized soybean oil, epoxidized linseed oil, epoxidized linseed oil fatty acid ester, epoxidated octylate, epoxidized glycol dioleate and others and mixtures thereof;

2) oxidized polyethylene;

3) 2-ethyl hexyl diphenyl phosphate;

4) polyethylene chlorate;

5) tetraethylene glycol di (2-ethyloxate);

6) a metal salt of a weak inorganic acid, for example, tetrasodium pyrophosphate;

7) a fatty acid soap, for example, calcium ricinoleate; and

8) a hydrotalcite, such as aluminum magnesium hydroxycarbonate, available from MITSUI® under the brand name DHT4A®, or ALCAMIZER®1 available from Kisuma Chemicals.

Commercial examples of epoxidized compounds include epichlorohydrin / bisphenol A, an epoxy resin available from Shell as EPON ™ 828; epoxidized soybean oil, available from Viking Chemical Company as VIKOFLEX® 7177; epoxidized linseed oil, available from Viking Chemical

Company as VIKOFLEX® 7190; epoxidized linseed oil fatty acid ester, available from Viking Chemical Company as VIKOFLEX® 9040; epoxidized octyl talate, available from CP Hall Company as Monoplex S-73; and epoxidized glycol dioleate, available from CP Hall Company as MONOPLEX ™ S-75.

The stabilizer may comprise 0.1, 0.5, 1.2, 3, 4, 5, 6, 7, 8, 9 or 10 parts by weight of the layered silicate nanocomposite composition with polyvinylidene chloride of the invention, as from 0.5 to 5, as from 1 to 3, as from 1.5 to 2 parts by weight of the inventive layered silicate nanocomposite composition with polyvinylidene chloride.

Commercial examples of a stabilizer include FERRO® PLASCHEK® 775, an epoxidized soybean oil, and calcium ricinoleate available from the Acme-Hardesty Company.

The polymeric processing aid of the invention can include one or more of:

1) a fatty acid soap, for example, calcium ricinoleate;

2) a terpolymer with an acrylate comonomer, such as methyl methacrylate / butyl acrylate / styrene terpolymer; methyl methacrylate / butyl acrylate / butyl methacrylate terpolymer or mixtures thereof;

3) n- (2-hydroxyethyl) -12 hydroxy stearamide; and

4) propylene glycol mono-ricinoleate.

The polymeric processing aid may comprise 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 parts by weight of the layered silicate nanocomposite composition with polyvinylidene chloride from invention; for example, the polymeric processing aid comprises from 0.5 to 5, as from 1 to 3, as from 1.5 to 2 parts by weight of the layered silicate nanocomposite composition with polyvinylidene chloride of the invention.

A commercial example of a polymeric processing aid is ELF ATOCHEM® METABLEN® L1000, an acrylic polymeric processing aid.

It should be noted that a fatty acid soap, for example, calcium ricinoleate, can work both as a stabilizer and as a polymeric processing aid. In this embodiment, the fatty acid soap may comprise 0.1, 0.5, 1.2, 3, 4, 5, 6, 7, 8, 9 or 10 parts by weight of the layered silicate nanocomposite composition with chloride polyvinylidene of the invention. For example, a fatty acid soap may comprise from 0.5 to 5, as from 1 to 3, as from 1.5 to 2 parts by weight of the layered silicate nanocomposite composition with polyvinylidene chloride of the invention.

Other co-stabilizing polymeric processing aids can optionally be included in the composition, such as HENKEL® LOXIOL® VPG1732, a complex ester of high molecular weight, and CASCHEM® CASTOWAX® NF, a hydrogenated castor oil.

The nanosilicate of the invention can include one or more clays of the phytosilicate group, including one or more of:

1) dioctahedral clays, such as montmorillonite, beidelite and nontronite; and

2) trioctahedral clays, such as saponite, hectorite and sauconite;

and, in particular, oxon ion modified forms of these clays.

The nanosilicate may comprise 0, 1, 0, 5, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 parts by weight of the layered silicate nanocomposite composition with polyvinylidene chloride of the invention, for example For example, the nanosilicate may comprise from 0.5 to 8, as from 1 to 5, as from 1.5 to 4 parts by weight of the layered silicate nanocomposite composition with polyvinylidene chloride of the invention.

Commercial examples of nanosilicates include CLOISITE® 20A and CLOISITE® 15A, which are a montmorillonite clay modified with oxon ion from Southern Clay Products; NANOMER® 1.31 PS, which is a Montmorillonite clay modified with oxide ion from Nanocor; BENTONE® 107 and BENTONE® 111, which are bentonite clays (a subset of smectite); BENTONE® 108 and BENTONE® 166, which are hectorite clays (also a subset of smectite), BENTONE® clays available from Elementis

Specialties; a nanotalco with the composition Mg₃SiOio (OH)₂ available from Nanova LLC; and a nanotalco (phyllosilicate) available from Argonne National Laboratory.

Optionally, the composition and film of the invention can include an acid remover (hydrogen chloride). If present, the acid remover may comprise from 0.1 to 4, as from 0.5 to 2, parts by weight of the layered silicate nanocomposite composition with polyvinylidene chloride of the invention.

A commercial example of an acid remover is MITSUI® DHT4A, a magnesium aluminum hydroxycarbonate of formula Mg₄, 5Al2 (OH)₁₃CO33.5H2O. An alternative material is tetrasodium pyrophosphate (TSPP).

The determination of the overall thermal stability of the layered silicate nanocomposite composition with polyvinylidene chloride of the invention can be carried out by working the composition between a pair of heated rollers or inside a heated mixing chamber. The time required to produce an appreciably blackened polymer due to shear degradation and temperature-induced degradation is a measure of the effectiveness of the thermal stability of the composition. Mixtures of commercially acceptable vinylidene chloride copolymers show thermal stability times of at least 10 minutes in a mixing device such as a BRABENDER® mixer operated at about 168 ° C (335 ° F) and 63 revolutions per minute.

The composition of the invention can be extruded and processed by any of the numerous methods known to those skilled in the art to form a film or a layer of a multilayer film, for example by the methods set forth in U.S. Patent Nos.^and 3,741,253 (Brax et al.), 4,278,738 (Brax et al.) And 4,284,458 (Schirmer), all of which are incorporated herein by reference in their entirety. Thus, any suitable method of preparing a film with an oxygen barrier layer can be used to prepare a film according to the present invention, as long as the method uses a layered silicate nanocomposite composition with polyvinyl chloride above. described. Suitable methods include coextrusion with tubular run, as shown in U.S. Patent no.^s 4,551,380 [Schoenberg], incorporated herein by reference in its entirety, coextrusion with tubular or flat running, or extrusion (for monolayer films) or coextrusion (for multilayer films) of blown bubbles by techniques well known in the art. Multilayer films can be prepared by co-extrusion, extrusion coating, extrusion lamination, crown bonding or conventional lamination of all layers of the film. A method for producing a multilayer film with a PVdC layer is disclosed in U.S. Patent no.^and 4,112,181, issued September 5, 1978 to Baird, Jr. et al., Hereby incorporated by reference in its entirety. This patent describes a method of coextruding a tubular peylicium, in which the walls of the tube have at least three layers, a central layer being a PVdC layer. The tubular film is subsequently biaxially oriented by the trapped bubble technique. The 3-layer film can be cross-linked by electron beam irradiation.

A satisfactory method for the production of a multilayer saran film is disclosed in U.S. Patent No.^and3,741,253, on June 26, 1973 for Brax et al, here incorporated by reference in its entirety, which presents a biaxially oriented multilayer film, with a PVdC barrier layer. This film is made by an extrusion coating process, in which a layer or layers of a polymer substrate, such as polyethylene or ethylene copolymer and vinyl acetate, is extruded in the form of a tube, cross-linked by irradiation and inflated. One layer of PVdC is coated by extrusion over the inflated tube, and another layer or layers of polymer is simultaneously or sequentially coated by extrusion over the PVdC. After cooling, this multilayer tubular structure is flattened and rolled up. Then, the tube is inflated and heated to its orientation temperature, thus orienting the film biaxially. The bubble is quickly cooled to fix the orientation. This process produces a heat-shrinkable barrier film with low oxygen permeability. Likewise, the advantages of a cross-linked film are obtained without subjecting the PVdC layer to irradiation, which tends to degrade saran. The barrier layer in the examples of the patent by Brax et al. is a plasticized copolymer of vinylidene chloride and vinyl chloride.

The film of the invention can be cross-linked or non-cross-linked, oriented or non-oriented, contractile with heat or non-contractile with heat. When the film is heat shrinkable, it has a total free contraction at 85 ° C (185 ° F) of 10 to 100%. All or a part of the film of the present invention can be irradiated to induce crosslinking. In the irradiation process, the film is subjected to an energetic radiation treatment, such as corona discharge, plasma, flame, ultraviolet, X-rays, gamma rays, beta-rays and treatment with high-energy electrons, which induces cross-linking between molecules of the irradiated material. The appropriate dosage level can be determined by standard dosimetry methods known to those skilled in the art, and the precise amount of irradiation to be used depends, of course, on the particular film structure and its end use. The film can be irradiated at a level of 0.5 - 15 megarads (MR) (5 to 150 KGrays), such as 1-12 MR. Additional details on the irradiation of polymeric films can be found, for example, in US patents no.^and 4,064,296 (Bornstein et al.), 4,120,716 (Bonet) and 4,879,430 (Hoffman), all of which are incorporated herein by reference in their entirety.

Films of the invention can be prepared by tubular co-extrusion and by extrusion coating. In the latter case, a substrate is extruded or co-extruded, optionally irradiated, then optionally oriented by stretching; and, then, a layer of the layered silicate nanocomposite with polyvinylidene chloride as set forth herein is extruded, optionally with at least one additional layer, to the substrate.

Films of the invention may have the following structures:

<img file="BRPI0609503A2_D0001.tif" />

on what:

A = silicate nanocomposite layered with polyvinylidene chloride.

B, C and D = any of the materials presented above for layers 43, 44 and 42, respectively, of figure 4.

The polymeric components used to manufacture the film according to the present invention can also contain appropriate amounts of other additives normally included in or mixed with these compositions. These include slip agents, antioxidants, fillers, dyes, pigments, radiation stabilizers, antistatic agents, elastomers and other additives known to those skilled in the packaging film technique.

The multilayer film of the present invention can have any number of total layers and any desired total thickness, as long as the film imparts the desired properties to the particular packaging operation in which the film is used.

The film layer comprising PVdC (silicate nanocomposite layered with polyvinylidene chloride) can be irradiated at a dosage level of 15 MR without significant change (degradation) of the film. However, chlorinated species are generated that may not be accepted by the FDA.

As is also known to those skilled in the art, the use of a polymer comprising metric units derived from vinylidene chloride and methyl acrylate reduces the degrading effect of PVdC irradiation.

The film of the invention can be laminated, adhesively fixed, coated by extrusion or laminated by extrusion to a substrate to form a laminate. The lamination can be performed by joining the layers with adhesive, joining with heat and pressure and even coating by spreading and coating by extrusion.

The film of the present invention is particularly suitable for packaging applications where the product (s) that are packaged must be protected against O₂ atmospheric. More particularly, the film according to the present invention is particularly useful as a blister pack for pharmaceutical substances, as a film suitable for use as a barrier pouch and as a film suitable for use in a patch pouch.

You can prepare a blister pack with the PVdC composition presented above and the film made with it by conventional techniques and in a conventional packaging format.

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Φ

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O

Co co co

CD

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AND

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AND

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CX o

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<td>H-</td><td></td><td>N</td>

<td>O</td><td>r- O</td><td>O</td>

<td>Q</td><td>&lt;θ</td><td> &lt; -8</td>

<td>CO</td><td></td><td></td>

<td>O ç</td><td>OO c</td><td>oo 8</td>

<td>c0</td><td>q ω &lt;co</td><td>Q CO &lt;co</td>

<td>Z</td><td>&gt; LU CL Z</td><td>&gt; UJ Q_ Z</td>

LO

<img file="BRPI0609503A2_D0002.tif" />

Notes from Table 1

1: 6- 9% by weight of MA comonomer.

2: epoxidized soybean oil.

3: polymeric processing aid.

4: smectite clay [montmorillonite] surface treated with quaternary ammonium salt.

5: natural smectite from Southern Clay Products Inc,

6: natural montmorillonite from Elementis Specialties.

7: phyllosilicate nanotalco from Argonne National Labs.

8: 3 - 6% by weight of MA comonomer.

9: VDC-VC, wherein the% w / w of vinyl chloride is between 8 and 14 wt% of the VDC-VC copolymer.

10: AS is an acid remover.

It should also be noted that ppc means parts per hundred (in units of weight) of material. Thus, by way of example, in the film of the first comparative example, the equivalent of 100 kilograms of VDC / MA resin was mixed with 2 kilograms of ESO material and 2 kilograms of polymeric processing aid. An equivalent of ppc is parts by weight. For the examples, the VDC / MA is listed separately from the nanotalco (the nanosilicate) to indicate the relative quantities of each material present in the examples, but it should be understood that the nanosilicate is in fact part of the silicate nanocomposite structure in layers with chloride polyvinylidene.

Additional Predictive Examples

Example 10

A four-layer film is co-extruded by a hot blowing process like an annular tube, the film having the construction:

EVE₁/EVE₂/ PVdC / EVA₂on what:

EVAi = EVA with 3.3% by weight of vinyl acetate content, available from Huntsman as PE1335®.

PVdC = silicate nanocomposite layered with polyvinylidene chloride.

EVE₂ = EVA with 28% by weight vinyl acetate content, available from DuPont as ELVAX®3182-2.

After extrusion, the tubular coextruded is collapsed on itself to form a flat film with the construction:

EVA ^ EVAs / PVdC / EVAs // EVAg / PVdC / EVAg / EVA!

A preferred thickness for each PVdC layer is

18.75 micrometers (0.75 mils).

Example 11

A four-layer film like the one in the previous example is prepared by a co-extrusion process with running, but in which the outer layer of EVAi is replaced by an LLDPE. The film therefore has the construction:

LLDPE / EVA₂/ PVdC / EVA₂

Two commercial LLDPE resins, each usable in this

For example, they are DOWLEX 2045.03 and DOWLEX 2045.04, both available from Dow. Each is an ethylene / octene-1 copolymer with an octene content of 6.5% by weight and a density of 0.920 grams / cm³.