- use of polyol mixtures in rigid and semi-rigid polyurethane foams

IS 2 175 672 T3

DESCRIPTION

Use of polyol blends in rigid and semi-rigid polyurethane foams.

The present invention relates to rigid and semi-rigid polyurethane foams that contain a mixture of polyols, especially polyurethane foams that exhibit strong adhesion to polyolefins and block copolymers that comprise more than 50% by weight of at least one block of polyolefin.

Polyurethane foams are typically produced from a polyol and a polyisocyanate. Rigid and semi-rigid polyurethane foams are well known in the art and are used in a wide variety of applications where foams with a wide range of properties are needed. A considerable number of different types of polyols are required to make the various foams. However, it was still difficult to obtain all the desired properties and it is sometimes necessary to adopt intermediate solutions.

Various polyols have been proposed for use in the manufacture of polyurethane foams, including polyether polyols such as those marketed under the trade names CARADOL, TERATHANE and POLYTHF and polyether polyols such as those marketed under the trade names TONE and FORMREZ.

International PCT Publication No. WO 97/00902 describes the preparation of polyurethane foams, in particular resilient and flexible foams, from an aromatic polyisocyanate having a functionality of 2.5 to 3.0 isocyanate groups per molecule and a polydiene diol having a number average molecular weight of 1,000 to 20,000 and a functionality of 1.6 to 2 hydroxyl groups per molecule.

The use of polyol blends to prepare polyurethane foams with desired properties is known. Examples of polyol blends for use in the preparation of rigid and semi-rigid polyurethane foams are those marketed under the trade names CARADOL PP520-03, LP585-01, LP530-03, GB450-01, GB475-01 and GB250.

United States Patent N^° 4,752,626 describes the preparation of a high resilience urethane foam. The foaming system consists of a thixotroypic polyisocyanate and a thixotroypic polyol. The polyol component comprises a mixture of polyols, composed of a polyolefin polyol and a polyoxyalkylene polyol in a weight ratio of 95/5 to 50/50.

It will be appreciated that there is still room for improvement in this field. In particular, there is a need to improve the adhesion of rigid and semi-rigid polyurethane foams to polyolefins, which include copolymers of olefin monomers, and block copolymers comprising at least 50% by weight of at least one polyolefin block. without, however, having a significant impact on other desirable foam properties.

Until now, it has been difficult to firmly adhere polyurethane foams to polyolefins without the use of a separate adhesive layer. In particular, it is known that polyurethane foams do not adhere firmly to thermoplastic polyolefins without the use of a separate adhesive layer.

Surprisingly, rigid and semi-rigid polyurethane foams have now been discovered which have one or more advantageous properties compared to foams of this type of the prior art. In particular, foams have been discovered which are capable of adhering very firmly to polyolefins and to block copolymers comprising at least 50% by weight of at least one polyolefin block, using a specific polyol blend.

Consequently, according to a first aspect, the present invention refers to a mixture of polyols for use in the preparation of polyurethane foam comprising:

(i) 80 to 99% by weight of at least one polyether polyol or polyether; and (ii) 1 to 20% by weight of at least one polyolefin polyol.

Preferably, the amount of polyolefin polyol present is 2 to 20% by weight, more preferably 2 to 5%. The polyolefin polyol can be linear or radial, preferably linear. Typically, the polyolefin polyol has a functionality in the range of 0.8 to 8, preferably 0.8 to 3.

The polyether polyol and / or polyether polyol typically has a functionality in the range of 0.8 to 8,

ES 2 175 672 T3 but preferably in the range of greater than 2 to 8, more preferably in the range of greater than 2 to 5. To ensure that sufficient crosslinking occurs in the foam, it is preferred that the number average functionality of the polyol mixture is greater than 2, preferably in the range of 2.5 to 8, more preferably in the range of 2.5 to 5. Functionality is defined as the number of functional groups, in this case hydroxyl groups, per molecule. Functionality can be determined by nuclear magnetic resonance (NMR) techniques or chemical titration.

The numerical mean functionality of the mixture is determined by the following formula (I).

[Fpo *% wtpo + Fes *% wtes + Fet *% Wtet] / 100 (I)

In this formula, F represents the functionality of the polyols, "po" corresponds to polyolefin-polyol, "es" corresponds to polyester-polyol, "et" corresponds to polyether-polyol, and% wt represents the percent by weight of the respective polyols in the blend.

The backbone of the polyolefin-polyol polymer, ie, the polyolefin, is typically the polymerized product of an olefin monomer or of an olefin monomer and a vinyl aromatic monomer. The olefin monomer typically contains 2 to 12 carbon atoms. Preferably, the olefin monomer is a diene containing 4 to 10 carbon atoms, more preferably 4 to 6 carbon atoms, even more preferably butadiene or isoprene, most preferably butadiene.

The vinyl aromatic monomer is preferably a mono aromatic vinyl monomer, such as styrene or alkyl-substituted styrene, in which the alkyl substituent (s) contain 1 to 4 carbon atoms. Most preferably, the vinyl aromatic monomer is styrene or mono-alkyl substituted styrene. The polyolefin polyol may contain up to 50% by weight of polymerized vinylaromaatic monomer, preferably 0 to 20% by weight, more preferably 0 to 5% by weight.

Preferably, the polyolefin polyol contains less than 20% olephane unsaturated in the main chain of the polymer. More preferably, the olephane unsaturation is less than 5%. The term "olephanous unsaturation", as used herein, excludes unsaturation present in any of the aromatic groups of the polymer. Those in the know know ways to determine olephane unsaturation.

The polyolefin polyol is preferably a polydiene polyol, more preferably a polydiene diol or a polydiene mono-ol or mixtures thereof. Most preferably, the polyolefin polyol is a polydiene diol. Typically, the polydiene diol has a functionality in the range of 1.5 to 2.5 hydroxyl groups per molecule, preferably in the range of 1.8 to 2.0, most preferably in the range of 1.9 to 2, 0. The polydiene-mono-ol has a functionality typically in the range of 0.8 to 1.5, preferably 0.85 to 1.15, most preferably 0.9 to 1.0.

The main chain of the diol and polydiene-mono-ol polymer, ie, the polydiene, is typically the hydrogenated polymerized product of conjugated diene monomers containing 4 to 10 carbon atoms; preferably 4 to 6 carbon atoms; more preferably butadiene or isoprene, in particular butadiene. Preferably, a hydrogenated polybutadiene diol having between 30% and 70% 1,2-addicon is used to minimize viscosity and subsequent crystallization. The diol and / or polydiene-mono-ol preferably used in the present invention can be prepared by means of an anionic initiator, as described in United States patents numbers 5,376,745, 5,391,663, 5,393,843, 5,405,911 and 5,416,168.

Polymerization of the polydiene diol begins with a monolithium or dilithium initiator, building a "living" (growing) polymer backbone from each lithium nucleus. Anioanic polymerization is carried out in solution, in an organic solvent, typically a hydrocarbon, such as hexane, cyclohexane or benzene, although polar solvents, such as tetrahydrofuran, can also be used. The molar ratio of initiator to monoomer determines the molecular weight of the polymer.

If the conjugated diene is 1,3-butadiene and the resulting polymer is to be hydrogenated, the anionic polymerization of butadiene in a hydrocarbon solvent such as cyclohexane is controlled topically with structure modifiers such as diethyl ether or glyme (1,2-diethoxyethane) to obtain the desired amount of 1,2 addition. In a hydrogenated polybutadiene polymer, the optimal balance between low viscosity and high solubility occurs with a 60/40 ratio of 1,4-butadiene and 1,2-butadiene. This butadiene microstructure can be achieved, for example, during polymerization at 50 C in cyclohexane which

ES 2 175 672 T3 contains about 6% by volume of diethyl ether or about 1,000 ppm of glyme.

Ammonium polymerization is stopped by the addition of a functional group transfer agent, such as those described in US Patent Specification Nos. 5,391,637, 5,393,843, and 5,418,296, but preferably the living polymer is protected with oxide. of ethylene, before stopping the polymerization. Thus, if a dilithium initiator is used, preferably, the living polymer is protected with two moles of ethylene oxide and the polymerization is stopped with two moles of methanol to produce the desired polydiene diol.

The polydiene diol can also be made using a monolithium initiator that contains a hydroxyl group that has been blocked such as silyl ether (as in US patent specifications numbers 5,376,745 and 5,416,168). A suitable initiator is hydroxypropyl lithium in which the hydroxyl group is blocked such as silyl trimethyl ether. This monolithium initiator can be used for the polymerization of butadiene in a hydrocarbon solvent or polar solvent. The "living" (growing) polymer is then protected with one mole of ethylene oxide for each mole of polymer and the polymerization is stopped with one mole of methanol to produce the mono-hydroxy polydiene polymer. The silyl ether is then removed by acid catalyzed cleavage in the presence of water, obtaining the desired polydiene diol.

The process for preparing polydiene-mono-ol can be analogous to that of polydiene-diol. In the preparation of the polydiene-mono-ol a monolithium initiator is used topically, which does not contain hydroxyl groups as described above. Polymerization of the initiator and the conjugated diene monoomer results in a living (growing) polymer. Preferably, the living polymer is then protected with one mole of ethylene oxide and the polymerization is stopped with one mole of methanol.

The diol and / or polydiene-mono-ol is preferably hydrogenated so that at least 90%, more preferably at least 95%, of the olephonic carbon-carbon double bonds of the polydiene are saturated. The hydrogenation of these polyomers can be carried out by various well-established processes including hydrogenation in the presence of catalysts such as Raney nickel, noble metals such as platinum and palladium, soluble transition metal catalysts, and titanium catalysts as described in the specification. United States Patent No. 5,039,755. A particularly preferred catalyst is a mixture of nickel 2-ethylhexanoate and triethylaluminum.

In the polybutadiene polymer, the 1,2-addition of butadiene is preferably not less than about 30%, because after hydrogenation, if the 1,2-addition of butadiene is less than about 30%, the polymer would be a solid. Cook at room temperature. To minimize the viscosity of the diol and / or mono-ol, the 1,2-butadiene content is preferably between 40 and 60%.

If isoprene is used as the conjugated diene for the preparation of the polydiene diol, the addition of 1.4 of the isoprene polyomers is preferably not less than 80%, in order to reduce the Tg and the viscosity. Diene microstructures are determined topically by NMR¹³C in chloroform.

The hydroxyl equivalent weights of the polydiene monools are preferably in the range of 500 to 15,000, most preferably in the range of 1,000 to 12,500.

The hydroxyl equivalent weights of the polydiene diols are preferably in the range of 250 to 10,000, most preferably in the range of 500 to 7,500, most preferably 1,500 to 3,000.

Suitable number average molecular weights of the polydiene diols are between 500 and 20,000, most preferably between 1,000 and 15,000, most preferably between 3,000 and 6,000. Suitable number average molecular weights of polydiene monools are between 500 and 15,000, most preferably between 1,000 and 12,500, most preferably between 1,500 and 6,000. The number average molecular weights mentioned herein are number average molecular weights measured by gel permeation chromatography (GPC) calibrated with polybutadiene standards having known number average molecular weights. The solvent used in the GPC analyzes is tetrahydrofuran.

Polyether polyols and polyether polyols are compounds well known to those skilled in the art and available on the market. From the group of polyether polyols and polyether polyols, preferably a polyether polyol is used.

Polyether polyols are topically the reaction product of an alkylene oxide and an initiator.

IS 2 175 672 T3

As the alkylene oxide, preferably propylene oxide or mixtures of propylene oxide and ethylene oxide are used.

Those connoisseurs of the technique also know the initiators well. Examples of suitable initiators for the manufacture of the polyether polyol used in the preparation of rigid and semi-rigid foams include glycerol, sucrose, sorbitol, amines, glycols or phenolic compounds, as well as their mixtures.

The structure of the polyether-polyol chains is very important, as it determines the properties of the final polyurethane foam. The most important factors are the molecular weight and the functionality of the polyether polyol. A person skilled in the art has the knowledge to select the right polyether polyol for a set of desired properties.

The polyether polyols preferably have a number average molecular weight in the range of 200 to 2,000, preferably 250 to 1,500, most preferably 250 to 1,000. Polyether polyols are often characterized by their hydroxyl ondx. For the preparation of rigid foams, the hydroxyl index is preferably in the range of 200 to 1,500 mg KOH / g, more preferably 250 to 1,000 mg KOH / g, determined according to ASTM D2849A. For the preparation of semi-rigid foams, the hydroxyl index is preferably in the range of 100 to 400 mg KOH / g. If mixtures of polyether polyols are used, it will be noted that the hydroxyl onyx of the individual polyether polyols may suitably not be in the above ranges, but preferably the average hydroxyl onyx of the polyether mixture polyols is maintained in the ranges mentioned above.

According to an additional aspect, the present invention refers to a process for preparing polyurethane foams that comprises the steps of:

combine 1 to 20 parts of at least one polyolefin-polyol and 80 to 99 parts of at least one polyetherpolyol and / or polyether-polyol, adding the total of the polyolefin-polyol and the polyolefin-polyol and / or polyether-polyol 100 parts in total, with a blowing agent, a catalyst and, optionally, a surfactant to form a mixture;

adding a polyisocyanate having a functionality of more than two isocyanate groups per molecule, in an amount such that the molar ratio of NCO: OH is at least 0.9: 1; and forming a polyurethane foam with the combined mixture and the polyisocyanate.

Preferably, the molar ratio of NCO: OH is between 0.9: 1 and 1.3: 1. If water is used as the blowing agent, most preferably the molar ratio of NCO: OH is greater than 1: 1. For the purposes of the present specification, it should be understood that in determining the molar ratio of NCO: OH, only the OH groups of the polyol mixture are taken into account.

In principle, any polyisocyanate, and mixtures of polyisocyanates, can be used for the preparation of rigid and semi-rigid polyurethane foams. However, the polyisocyanate and / or the polyol blend must have a functionality greater than 2 to allow the formation of a three-dimensional network by crosslinking. Preferably, both the polyol mixture and the polyisocyanate (s) have an average functionality greater than 2. The functionality of the polyisocyanate is preferably between 2 and 8, more preferably between 2 and 5.

Preferably, the polyisocyanate is an aromaotic polyisocyanate, most preferably polymeric diphenylmethane diisocyanate (MDI). Polymeric MDI, sometimes known as crude MDI, is a commercially available product. The Shell company markets a type of polymeric MDI under the trade name CARADATE 30.

Frequently, surfactants are added to improve the miscibility of the components, which favors the reaction between hydroxyl and isocyanate. In addition, the surface tension of the mixture is reduced, which influences cell nucleation and stabilizes the expanding foam, producing a fine cellular structure. Preferably the surfactant is a silicone oil. An example of a suitable commercially available silicone oil is TEGOSTAB-B8404 (TEGOSTAB is a trade name). Where appropriate, the surfactant is usually added in an amount of 0.5 to 5 parts by weight (pp) per 100 pp of the total polyol blend, preferably 0.5 to 2 pp.

In principle, any catalyst with known ability to catalyze one or more of the foaming reactions of the system can be used. European patent specification No. 0 358 282 describes

ES 2 175 672 T3 screen examples of suitable catalysts, including amines such as tertiary amines, carboxylic acid salts and organometallic catalysts.

Examples of suitable tertiary amines are triethylenediamine, N-methylmorpholine, N-ethylmorpholine, diethylethanolamine, N-cocomorpholine, 1-methyl-4-dimethyl-amino-ethyl-piperazine, 3-methoxypropyl-dimethylamine, N, N, N '- trimethyl-isopropyl-propylenediamine, 3-diethylamino-propyl-diethylamine, dimethylbenzylamine and dimethylcyclohexylamine. An example of a carboxylic acid salt useful as a catalyst is sodium acetate. Suitable organometallic catalysts are stannous octoate, stannous oleate, stannous acetate, stannous laureate, lead octoate, lead naphthenate, nickel naphthenate, cobalt naphthenate and dibutyl dichloride. Other examples of organometallic compounds useful as catalysts in the production of polyurethanes are described in US Patent Specification No. 2,846,408. Of course, mixtures of two or more of the above catalysts can also be applied.

The amount of catalyst, or catalyst blend, which is normally used is in the range of 0.01 to 5.0 pp, preferably in the range of 0.2 to 2.0 pp, per 100 parts of polyol blend.

Various blowing agents can be used. Suitable blowing agents are halogenated hydrocarbons, aliphatic alkanes and alicyclic alkanes, as well as water, which is often referred to as a chemical blowing agent. Due to the ozone depletion effect of fully chlorinated fluoroalkanes (CFCs), the use of this type of blowing agent is not preferred yet, although the scope of the present invention contemplates its use. Halogenated alkanes in which at least one hydrogen atom has not been replaced by a halogen atom (so-called HCFCs) have a lower ozone depletion potential and are consequently the preferred halogenated hydrocarbons for use in blowing foams. physical. A very suitable HCFC-type blowing agent is 1-chloro-l, l-difluoroethane. Still preferred blowing agents are hydrofluorinated hydrocarbons whose ozone depletion potential is believed to be zero.

The use of water as a (chemical) expansion agent is also well known. Water reacts with isocyanate groups following the well-known NCO / H2O reaction, from which carbon dioxide is released causing blowing.

Alifautic and alicyclic alkanes, finally, were developed as expansion agents, still alternatives to CFCs. Examples of such alkanes are n-pentane, isopentane and n-hexane (aliphatic), and cyclopentane and cyclohexane (alicyclic).

It will be understood that the foregoing blowing agents can be used singly or in mixtures of two or more agents. Of the blowing agents mentioned above, water and cyclopentane have been found to be particularly suitable as blowing agents for the purposes of the present invention. The amounts to be used of the blowing agents are those applied in a conventional way, that is, in the range of 0.1 to 5 pp per 100 parts of polyol mixture, in the case of water, and in the range of about 0.1 to 20 pp per 100 parts of reactive polyol in the case of halogenated hydrocarbons, aliphatic alkanes and alicyclic alkanes. Preferably the blowing agent is still water.

Preferably, an amount of water of 0.5 to 3.5 parts by weight (pp) is added per 100 parts of polyol mixture. Preferably, distilled or demineralized water is used, as impurities can affect the foaming reaction.

Air Products company markets various amines, organometallic catalysts and silicone surfactants for the manufacture of polyurethane foams under the trade name DABCO.

If desired, flame retardants, fillers and other additives can be added. The typical connoisseur of this technique should know how to select the appropriate additional compounds to be added to the composition to be foamed.

Polyurethane foams are preferably prepared by mixing all the components except the polyisocyanate. Preferably, the polyol blend is preheated prior to mixing to reduce viscosity. After mixing, the polyisocyanate is quickly added and the mixture stirred briefly before being poured into a mold that receives the expanding foam. Typically, the mold contains a polyolefunic substrate to which the foam must adhere.

The polyurethane foam can be subjected to a cure treatment by heating the foam to a high temperature, usually between 100 and 160^°C for a certain period, typically in

ES 2 175 672 T3 the range from 10 minutes to 96 hours, preferably from 30 minutes to 48 hours. However, the heat generated by the exothermic polyurethane formation reaction is usually sufficient to ensure complete cure, and the process is carried out under adiabatic conditions.

According to a third aspect, the present invention relates to a polyurethane foam that can be obtained by a process such as that described hereinabove. The foam according to the present invention typically has a bulk density in the range of 10 to 800 kg / m³, preferably 20 to 250 kg / m³, more preferably 20 to 120 kg / m³.

The adhesion to polypropylene of the foam according to the invention, determined by the force necessary to detach a 25 cm flat polypropylene plate from the foam², is topically more than 150 N / 25cm². Preferably, the adhesion to polypropylene is greater than 200N / 25cm², more preferably from 250 N / 25cm² up to the tensioon limit of cohesion of the foam itself.

The invention also relates to articles containing said polyurethane foam, as well as compounds formed by a polyolefin or block copolymers comprising more than 50% by weight of at least one polyolefin block and said polyurethane foam.

The foams of the present invention are preferably used as insulating material (including water insulating material) in home appliances, pipe insulation, automotive applications, eg dashboards, and in the construction industry.

The following examples illustrate rigid and semi-rigid polyurethane foams according to the present invention. The examples are not intended to limit the present invention to specific embodiments, although each example may illustrate a separate claim that is stated as a patentable invention. Example 1

A polyol blend was prepared for use in the preparation of a semi-rigid polyurethane foam. The polyol mixture contained 50 parts by weight (pp) of a polyether polyol with a hydroxyl onyx of 520 mg KOH / g and marketed under the trade name CARADOL 520-03, 45 pp of a polyether polyol with a hydroxyl onyx. of 36 mg KOH / g and marketed under the trade name CARADOL 36-03, and 5 pp of a hydrogenated polybutadiene diol with a functionality of 1.9 and a hydroxyl equivalent weight of 1,700.

1 part by weight per 100 parts of polyol mixture (pp) of a silicone oil surfactant, marketed under the trade name TEGOSTAB B8404, 0.8 pp of a catalyst analogous to glyme (glyme) was added to the polyol mixture. , marketed under the trade name DIME-6, and 0.8 pp of an ammonium type catalyst, marketed under the trade name DABCO 33LV. This last catalyst is a mixture of 33% by weight of triethylenediamine (TEDA) and 67% by weight of dipropylene glycol.

In addition, 1.8 pp of water was added as a blowing agent (chemical) per 100 parts of total polyol mixture.

Subsequently, 105 pp of polymeric MDI was added per 100 parts of polyol mixture and the reaction mixture was stirred. Polymeric MDI, marketed under the trade name CARADATE 30, contained about 70% by weight of diphenylmethane diisocyanate, the remainder being its isomers, oligoomers, and polymers. The molar ratio of NCO: OH was 1.05: 1.

The reaction mixture was poured into a mold at the bottom of which a polyolefin plate had been placed. The mold was closed and the mixture was allowed to react, without additional heating or cooling of the mold. After the reaction was completed and a foam had formed, the mold containing the foam was allowed to cool for 60 minutes.

The same experiment was repeated several times, each time placing a different type of polyolefin material in the mold. The force necessary to detach the polyolefin plate from the foam was determined. The results are presented in Table 1.

Example 2

The experiment as described in Example 1 was repeated several times, each time placing a different type of polyolefin material in the mold. A mixture of polyols was used that differed

ES 2 175 672 T3 of the mixture used in Example 1 containing 15 pp of the polybutadiene diol used in Example 1 and 35 pp of CARADOL 36-03. The force necessary to detach the polyolefin plate from the foam was determined. The results are presented in Table 1.

Comparative Example 3

The experiment as described in Example 1 was repeated several times, each time placing a different type of polyolefin material in the mold. A polyol mixture was used which differed from the mixture used in Example 1 in that it contained only 50 pp of polyether polyol CARADOL 36-03 and did not contain polybutadiene diol. The force necessary to detach the polyolefin plate from the foam was determined. The results are presented in Table 1.

TABLE 1

Force required to detach polyolefin plates from polyurethane foams

<td>Polyolefin plates</td><td>Example 1 (N / 25cm²)</td><td>Example 2 (N / 25cm²)</td><td>Example comp. 3 (N / 25cm²)</td>

<td>MM 17</td><td>&gt; 600 (c)</td><td>&gt; 600 (c)</td><td> 83</td>

<td>GXPA 018</td><td>420 (c)</td><td>&gt; 600 (c)</td><td> 91</td>

<td>GXPA 055</td><td>&gt; 600 (c) / 445</td><td>&gt; 600 (c)</td><td> 81/78</td>

<td>GXPA 064</td><td> 450</td><td>&gt; 600 (c)</td><td> 81</td>

(c) = limit cohesion stress of the foam.

81/78 = measurement performed twice

As seen in Table 1, the addition of a small amount of polydiene diol to the polyether polyol significantly improves the adhesion to polyolephonic substrates of the polyurethane foam produced from the polyols. The polyolephonic substrates used in the tests whose results are presented in Table 1 were supplied by the company Montell Polyolefins. MMl7 is an intimate blend of PMMA and a polypropylene resin. GXPA018 is a glass fiber reinforced polypropylene, containing 30% glass fiber by weight. GXPA055 is a polypropylene reinforced with fiberglass and modified to increase its impact resistance, containing 35% by weight of fiberglass. GXPA064 is a polypropylene modified to increase its impact resistance that contains 30% by weight of CaCO3. The Montell Polyolefins company markets the different types of GXPA under the trade name HIVALLOY.

Example 4

The introduction of the hydrogenated polybutadiene diol of Example 1 in rigid foams improves the adhesion of the foams to polyethylene, the optimal concentration of the formulation being 3%. With this concentration, in most cases, the cohesion limit of the foam is reached instead of breaking the adhesion of foam and polyethylene. With larger amounts, this phenomenon is not observed. The foam looks good and cannot be distinguished from the reference formulation. Other topical properties of the foams (mechaonic and thermic properties, content of closed cells) were also measured and compared with the quality of the reference formulation, with favorable results.

The following sample preparation procedure was used:

- the mold and polyethylene plates were preheated to approximately 50^°C

- the plates were glued in the mold

- the reaction mixtures were poured onto the plates and the mold was closed

- the mold was filled with a density of approximately 50 g / l

- the molded parts were cut and tested a few days later.

IS 2 175 672 T3

The reference formulation is based on CARADOL GB475-0l and GB250-0l, which are polyether polyols with hydroxyl onices of 475 and 250, respectively. The modified formulations contain 3%, 5% or 10% (of the polyol mixture) of the hydrogenated polybutadiene diol, ie polyethylene / butylene diol (EB diol). The results are presented in Tables 2 and 3.

TABLE 2

<td>Product</td><td>Ref.</td><td> 3%</td><td> 5%</td><td> 10%</td>

<td>GB250-01</td><td> 60</td><td> 57</td><td> 55</td><td> 50</td>

<td>GB470-0l</td><td> 40</td><td> 40</td><td> 40</td><td> 40</td>

<td>EB Diol-</td><td> 0</td><td> 3</td><td> 5</td><td> 10</td>

<td>TEGOSTAB B-8404</td><td> 1,5</td><td> 1,5</td><td> 1,5</td><td> 1,5</td>

<td>Tell me-6</td><td> 1,1</td><td> 1,1</td><td> 1,1</td><td> 1,1</td>

<td>H2O</td><td> 4</td><td> 4</td><td> 4</td><td> 4</td>

<td>CARADATE-30</td><td> 146</td><td> 144,3</td><td> 143,3</td><td> 141</td>

<td colspan="5">Properties</td>

<td>Basic density</td><td>45.1 g / l</td><td> 44,6</td><td> 42,6</td><td> 43,6</td>

<td>Resistance to</td><td></td><td></td><td></td><td></td>

<td>compression</td><td>250 kPa</td><td> 229</td><td> 187</td><td> 212</td>

<td>Accession</td><td>80 kPa</td><td> 223</td><td> 144</td><td> 161</td>

<td>CCC</td><td> 91 %</td><td> 91</td><td> 90</td><td> 89</td>

<td>^T softening</td><td> 135^°C</td><td> 137</td><td> 136</td><td> 137</td>

* CCC = closed cell content

The evolution over time of the thoracic conductivity of the reference formulation was compared with that of the formulation containing 5% EB diol. The untreated foams were conditioned at 50^°C and the thermal conductivity, lambda, was measured at 10^°C after several periods. The formulation containing polyethylene / butylene diol (EB diol) appears to evolve slightly faster, but the difference is small.

TABLE 3

<td>Lambda of the Ref (mW / mK)</td><td>Lambda of the 5% formulation</td><td>Time (days)</td>

<td> 23,8</td><td> 23,6</td><td> 0</td>

<td> 25,7</td><td> 26,2</td><td> 3</td>

<td> 26,8</td><td> 27,5</td><td> 4</td>

<td> 30,4</td><td> 31,7</td><td> 9</td>

<td> 32,9</td><td> 33</td><td> 16</td>

The use of 3% polyethylene / butylene diol in the formulation significantly improves the adhesion of the foam to the polyethylene, without significantly affecting other properties of the foam.