KR20070100937A - Manufacturing method of microcell type polyurethane elastomer - Google Patents

Abstract

The invention relates to microcellular polyurethane elastomers which can be produced by reacting polyisocyanates with compounds having at least two hydrogen atoms which are reactive with isocyanate groups. Said elastomers are characterised in that they contains a combination a) made of ai) an aromatic phosphite having a phosphorus content of between 9,00-11,00 wt.-%, and aii) an amine compound. The molar ratio between ai) and aii) is between 0,005-4,0.

Description

Method for producing microcell-type polyurethane elastomer {METHOD FOR PRODUCING MICROCELLULAR POLYURETHANE ELASTOMERS}

One-piece polyurethane foams, often referred to as microcell-like polyurethane elastomers and also referred to herein as MPEs, have been known for some time and are used, for example, to make shoe soles. This is described, for example, in Kunststoffhandbuch [Plastics Handbook], Volume 7 "Polyurethanes", 3rd edition, page 376 ff. The foam is prepared by reacting a polyisocyanate with a compound containing at least two hydrogen atoms reactive with isocyanate groups. Commonly used compounds in this regard are polyester alcohols. This provides materials with good application properties such as high elasticity, high tensile strength and tear propagation strength or low wear. At the same time, the system can be processed with high process reliability. One disadvantage of polyester alcohol-based microcell type polyurethane elastomers is the low hydrolysis resistance of the materials. Low hydrolysis resistance is caused by the inherent propensity of ester groups to hydrolyze. Cleavage of the ester groups leads to a decrease in the molar mass of the polymer, leading to deterioration of the use properties, which can lead to extreme conditions leading to total material collapse.

Thus, numerous efforts have been made in the past to increase the hydrolytic stability of such materials.

One method of improving the hydrolytic stability of the polyester alcohol-based microcell-type polyurethane elastomer that has been proposed is to use a specific polyester alcohol. As an example in the present invention, mention should be made of DE 3 144 968 in which polyester alcohols based on adipic acid, 1,4-butanediol, 1,6-hexanediol and neopentyl glycol are used. Also described are the substitutions or partial substitutions of the polyester alcohols for the more hydrolyzable polyether alcohols.

Another way to improve hydrolysis resistance is to use special additives, usually used in amounts less than 10% by weight. For example, EP # 965 # 582 describes the use of acid anhydrides, while DE 19 710 978 describes the use of a combination of lactones and carbodiimide.

However, solutions that can be taken from the prior art generally have disadvantages. In some cases, high hydrolysis resistance is actually achieved, but only insufficient application properties before aging are obtained simultaneously. In addition, some solutions cannot actually be implemented due to higher feedstock costs. This can occur, for example, when using certain polyester alcohols or when using higher amounts of special additives. A further disadvantage of many solutions that can be taken from the prior art is that the storage stability of the components is reduced. In addition, many solutions have very low effectiveness, particularly where extremely high hydrolytic stability is required.

In general, the use of phosphites in microcell-like polyurethane elastomers is described, for example, in Kunststoffhandbuch, Volume 7 "Polyurethanes", 3rd edition, page 120 ff. In such cases, phosphite can be used as antioxidant adjuvant. Typically, a combination of representative antioxidants, such as steric hindrance phenols, is used to induce synergy, which is associated with a significant increase in effectiveness in the inhibition of the thermal oxidation process.

JP 61128904 describes the use of 4-14% phosphite esters in polyester alcohol-based microcell-like polyurethane elastomers. Phosphites based on phenol and long chain alkyl radicals are used as yellowing inhibitors. The phosphite is used in the prepolymer. JP 63278962 describes polyester-based UV-stable MPEs for footwear. Along with steric hindrance phenol as antioxidant, phosphite is used as antioxidant adjuvant. The weight ratio is 1% by weight. JP 63305162 describes a UV stabilized package for polyester alcohol based MPE. Here, triphenyl phosphite (TPP) is mentioned as an antioxidant adjuvant, especially with steric hindrance phenols. The weight ratio is 0.5% by weight. JP 05214240 describes UV protection for PU soles containing about 1% thiophosphite. JP # 2003147057 describes the use of polycarbonate diols in shoe systems. In the examples, mention is made of adding about 2% by weight of TPP to the prepolymer.

Documents JP 61128904, JP 63278962 and JP 05214240 generally describe the use of phosphites in polyester-based MPE as antioxidant adjuvant. Documents JP 63278962 and JP 63305162 mention in particular that aromatic phosphites can be used as antioxidants in isocyanate reactive components. Document JP 2003147057 describes the use of aromatic phosphites in polyether carbonate alcohol-based microcell-type polyurethane elastomers.

It is an object of the present invention to provide a hydrolysis inhibitor for polyester alcohol-based MPEs which enables high effectiveness at low usage and ensures a high effect regardless of the polyester alcohol used.

The object is to (ai) aromatic phosphites and (aii) amine compounds, which have a phosphorus content of 9.00% to 11% by weight, preferably 9.90% to 10.10% by weight, in particular 9.95% to 10.05% by weight. Achieved using a specific hydrolysis inhibitor (a) consisting of a combination of triethylenediamine, the molar ratio of (ai) and (aii) is preferably 0.005 to 4.0, more preferably 0.1 to 3.0, in particular 0.5 to 2.0. It is preferable to use component (ai) (component B) among isocyanate-containing components and component (aii) (component A) among isocyanate-reactive components.

Accordingly, the present invention provides an MPE which can be prepared by reacting a compound containing at least two hydrogen atoms reactive with isocyanate groups with a polyisocyanate, which (ai) has an aromatic force having a phosphorus content of 9.00% to 11.00% by weight. A combination consisting of a pit and (aii) an amine compound, wherein the molar ratios of (ai) and (aii) are from 0.005 to 4.0.

The present invention further provides a method for preparing MPE by reacting a compound containing at least two hydrogen atoms reactive with isocyanate groups with a polyisocyanate, wherein the method (ai) has a phosphorus content of 9.00% to 11.00% by weight. Carrying out the reaction in the presence of (a), a combination consisting of an aromatic phosphite and (aii) an amine compound, wherein the molar ratio of (ai) and (aii) is 0.005 to 4.0.

The present invention also provides the use of a combination of aromatic phosphite having a phosphorus content of 9.00% to 11.00% by weight and (aii) an amine compound as a hydrolysis inhibitor for MPE.

The present invention also provides a shoe sole comprising the microcell-type polyurethane elastomer of the present invention.

The molar ratio of (ai) and (aii) is preferably 0.1 to 3.0, particularly 0.5 to 2.0.

The phosphorus content of component (ai) is preferably from 9.90% to 10.10% by weight, in particular from 9.95% to 10.05% by weight.

As the component (ai) to be used, triphenyl phosphite (TPP) is preferable.

The amine compound (aii) used may be primary, secondary, preferably tertiary amine. It is preferred that these are amines typically used as catalysts for producing polyurethanes.

The amine compound is triethylamine, triethylenediamine, tributylamine, dimethylbenzylamine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N'-tetramethylbutanediamine, N , N, N ', N'-tetramethylhexane-1,6-diamine, dimethylcyclohexylamine, pentamethyldipropylenetriamine, pentamethyldiethylenetriamine, 3-methyl-6-dimethylamino-3-aza Pentol, dimethylaminopropylamine, 1,3-bisdimethylaminobutane, bis (2-dimethylaminoethyl) ether, N-ethylmorpholine, N-methylmorpholine, N-cyclohexylmorpholine, 2-dimethylamino Methoxyethanol, dimethylethanolamine, tetramethylhexamethylenediamine, dimethylamino-N-methylethanolamine, N-methylimidazole, N- (3-aminopropyl) imidazole, N- (3-aminopropyl) -2 -Methylimidazole, 1- (2-hydroxyethyl) imidazole, N-formyl-N, N'-dimethylbutylenediamine, N-dimethylaminoethylmorpholine, 3,3'-bis-dimethylamimi Nodi-n-propylamine and / or 2,2'-dipiperazinediisopropyl ether, dimethylpiperazine, N, N'-bis (3-aminopropyl) ethylenediamine and / or tris (N, N-dimethylamino Propyl) -s-hexahydrotriazine, or a tertiary amine selected from the group comprising a mixture comprising two or more of said amines, but is for example as described in DE-A 28 12 256. Higher molecular weight tertiary amines may also be used. It is particularly preferable to use triethylenediamine.

In most cases, the amount of tertiary amine used as a catalyst is sufficient to achieve the required stabilization action, together with the aromatic phosphite (ai). However, it is also possible to use additional amines when a catalyst other than an amine catalyst is used, or when an amine catalyst amount is used that is less than the amount required for sufficient stabilization. This additional amine will then not be a tertiary amine used as a catalyst in the process to rule out decay during catalysis.

The hydrolysis inhibitor (a) is preferably used in an amount of 0.0001% to 3%, 0.0005% to 2% and 0.001% to 1.6% by weight based on the weight of the MPE.

In the starting materials used for the production of the MPEs of the invention, the following matters should be mentioned in particular.

Polyisocyanates used in the process according to the invention include aliphatic, cycloaliphatic and aromatic isocyanates and any mixtures thereof known in the art. Examples are diphenylmethane 4,4'-diisocyanate, a mixture of monomeric diphenylmethane diisocyanates and diphenylmethane diisocyanate homologs containing a higher number of rings (polymer MDI), tetramethylene diisocyanate, hexamethylene di Isocyanate (HDI), tolylene diisocyanate (TDI) or mixtures thereof.

Preference is given to using 4,4'-MDI and / or HDI. Particularly preferably used 4,4'-MDI may comprise small amounts, up to about 10% by weight, of allophanate modified or uretonimine modified polyisocyanate. It is also possible to further use small amounts of polyphenylenepolymethylene polyisocyanate (crude MDI). The total amount of the highly functional polyisocyanate should not exceed 5% by weight of the isocyanate used. In addition, the 4,4'-MDI may comprise a small amount, preferably up to 10% by weight of 2,4'-MDI.

Polyisocyanates can also be used in the form of polyisocyanate prepolymers. Such prepolymers are known in the art. This is described below, for example, by preparing the above-mentioned polyisocyanate by reacting a compound containing a hydrogen atom reactive with isocyanate with a polyisocyanate at a temperature of about 80 ° C., and producing the prepolymer. The polyol-polyisocyanate ratio is usually chosen such that the NCO content of the prepolymer is from 8% to 25% by weight, preferably from 10% to 22% by weight, more preferably from 13% to 20% by weight.

Compounds containing hydrogen atoms reactive to isocyanates used are polyester alcohols as described.

The polyester alcohols are polyfunctional alcohols containing 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, preferably polyfunctional carboxylic acids containing 2 to 12 carbon atoms of diol, For example, it is common to prepare by condensation with succinic acid, glutaric acid, adipic acid, phthalic acid, isophthalic acid and / or terephthalic acid and mixtures thereof. Examples of suitable dihydric and polyhydric alcohols are ethylene glycol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol and / or 1,6-hexanediol and mixtures thereof.

Polyester alcohols may also be branched. The functionality of the branched polyester alcohols is preferably more than 2 to 3, in particular 2.2 to 2.8. The number average molecular weight of the branched polyester alcohol is preferably 500 g / mol to 5000 g / mol, more preferably 2000 g / mol to 3000 g / mol.

In general, the average theoretical functionality of the polyester alcohols used in the process according to the invention is 2 to 4, preferably more than 2 to less than 3, and the number average molecular weight is as specified above.

Polyester alcohols can also be used substantially in admixture with polyether alcohols. However, since such mixtures often lack phase stability, it is not desirable to use such mixtures.

Compounds containing two active hydrogen atoms may also include chain extenders used when necessary. Suitable chain extenders are known in the art. Preference is given to using difunctional alcohols having a molecular weight of up to 400 g / mol, in particular in the range from 60 g / mol to 150 g / mol. Examples are ethylene glycol, 1,3-propanediol, diethylene glycol, butanediol-1,4, glycerol or trimethylolpropane, and mixtures thereof. Preference is given to using ethylene glycol.

When used, the chain extender is 1% to 15% by weight, preferably 3% to 12% by weight, more preferably based on the total weight of the compound containing two hydrogen atoms reactive with isocyanate groups It is typical to use in amounts of 4 to 10 weight percent.

Polyisocyanates are generally reacted with a compound containing two active hydrogen atoms in the presence of a blowing agent. The blowing agents used may be generally known chemically or physically active compounds. The chemically active blowing agent may preferably be water. Examples of physical blowing agents are inert (cyclo) aliphatic hydrocarbons containing 4 to 8 carbon atoms that evaporate under polyurethane forming conditions. The amount of blowing agent used depends on the desired density of the foam.

Polyisocyanates, if necessary, include catalysts and auxiliaries and / or additives such as cell regulators, mold release agents, pigments, reinforcing agents such as glass fibers, surface active compounds and / or oxidation, heat or microbial degradation or aging. React with a compound containing two active hydrogen atoms in the presence of a stabilizing agent for.

The catalysts used to prepare the microcell-like polyurethane elastomers of the present invention are conventional and known polyurethane formulation catalysts, for example organometallic compounds such as tin diacetate, tin dioctoate, dibutyltin dilaurate and / or Strong basic amines such as diazabicyclooctane, bis (N, N-dimethylaminoethyl) ether or the aforementioned amines. The catalyst is preferably used in an amount of 0.01 to 10% by weight, preferably 0.02 to 5% by weight, based on the reaction mixture.

As mentioned above, preference is given to using amines, in particular tertiary amines, as catalyst. The amines can be used individually or as any mixture with another amine, as described above. They act simultaneously as component (aii) in the microcell-like polyurethane elastomer. For this reason, it is preferable to use only the amine mentioned in an amount necessary to be effective as a stabilizer. If the amine is not sufficient for the catalytic effect, tertiary amines can be used with other catalysts.

Organic amines that can be used are tertiary amines known from the prior art. Useful tertiary amines are, for example, organic amines such as triethylamine, triethylenediamine, tributylamine, dimethylbenzylamine, N, N, N ', N'-tetramethylethylenediamine, N, N, N' , N'-tetramethylbutanediamine, N, N, N ', N'-tetramethylhexane-1,6-diamine, dimethylcyclohexylamine, pentamethyldipropylenetriamine, pentamethyldiethylenetriamine, 3- Methyl-6-dimethylamino-3-azapentol, dimethylaminopropylamine, 1,3-bisdimethylaminobutane, bis (2-dimethylaminoethyl) ether, N-ethylmorpholine, N-methylmorpholine, N- Cyclohexyl morpholine, 2-dimethylaminoethoxyethanol, dimethylethanolamine, tetramethylhexamethylenediamine, dimethylamino-N-methylethanolamine, N-methylimidazole, N- (3-aminopropyl) imidazole, N- (3-aminopropyl) -2-methylimidazole, 1- (2-hydroxyethyl) imidazole, N-formyl-N, N'-dimethylbutylenediamine, N-dimethylamino Ylmorpholine, 3,3'-bis-dimethylaminodi-n-propylamine and / or 2,2'-dipiperazindiisopropyl ether, dimethylpiperazine, N, N'-bis (3-aminopropyl) Ethylenediamine and / or tris (N, N-dimethylaminopropyl) -s-hexahydrotriazine, or mixtures comprising two or more of these amines, but are described, for example, as described in DE 28x12 256. Similar higher molecular weight tertiary amines are also possible. Particular preference is given to using triethylenediamine.

Catalysts that can be used in mixtures with tertiary amines, as mentioned above, are mainly organometallic compounds, in particular tin compounds such as tin diacetate, tin dioctoate, dibutyltin dilaurate and / or bismuth compounds. have.

The catalyst is preferably mixed with a compound containing at least two hydrogen atoms reactive with isocyanate groups. It is also possible to mix substantially polyisocyanates and at least organometallic compounds.

In general, polyisocyanates are meant as isocyanate components, and compounds containing two or more hydrogen atoms which are usually used as a catalyst, if necessary in admixture with blowing agents and additives and reactive with isocyanates are meant as polyol components.

To produce polyurethane foams, the isocyanate component and the polyol component are usually reacted in an amount such that the equivalent ratio of NCO groups to total reactive hydrogen atoms is from 1: 0.8 to 1: 1.25, preferably from 1: 0.9 to 1: 1.15. . In the present invention, the ratio 1: 1 corresponds to the NCO index 100.

The reaction yielding the microcell polyurethane elastomer is preferably carried out by pressurization in the mold. The mold is preferably composed of a metal such as steel or aluminum, or a plastic such as an epoxy resin. The starting components are mixed at a temperature of 15 ° C. to 90 ° C., preferably 20 ° C. to 35 ° C. and, if necessary, enter the closed mold, preferably at high pressure. The mixing can be carried out by an inflow process through a high pressure or low pressure mixer head known in the art. The temperature of the mold is generally 20 ° C to 90 ° C, preferably 30 ° C to 60 ° C.

The amount of reaction mixture entering the mold is such that the density of the resulting mold is 250 g / l to 600 g / l or 800 g / l to 1200 g / l, preferably 400 g / l to 600 g / l or 820 g / to 1 to 1050 g / l. The degree of compression of the resulting microcell-type polyurethane elastomer is from 1.1 to 8.5, preferably from 1.2 to 5, more preferably from 1.5 to 4.

The microcell type polyurethane elastomer of the present invention can be used for vehicle handles, safety suits, and preferably for shoe soles.

The invention is illustrated in detail by the following examples.

Comparative Examples C1 to C3 and Examples 1 to 4

100 parts by weight of the polyol component and the isocyanate component were thoroughly mixed at 23 ° C. in the parts specified in Table 1, and allowed to cure in a foamed and closed mold, followed by a microcell-type polyurethane elastomer plate having a total density of 550 g / l. The mixture was introduced into an aluminum mold in the form of a plate, heated to 50 ° C. and having dimensions of 20 cm × 20 cm × 1 cm in an amount such that plaque) was calculated.

After storage for 24 hours, dumbbell test specimens were punched from the elastomer plates thus produced using stamps. Prior to starting the aging test, the initial tensile strength was measured according to DIN 53543. The test specimens were then subjected to the aging test at 70 ° C. in water according to DIN 53543. After 14 days the samples were received. The results are summarized in Table 2.

After 2 weeks of hydrolysis aging, the residual tensile strength and elongation of Samples 1-4 were apparently higher than Comparative Samples C1 to C3.

Used feedstock:

PESOL 1: Polyester alcohols prepared from ethylene glycol (Lupraphen ^® 8108), 1,4-butanediol and adipic acid, available from Elastogran GmbH, OHN = 56 mg KOH / g , Activity = 2

Amine catalyst: 33 wt% solution of triethylenediamine in ethylene glycol (Lupragen ^® N 202) available from BASG AG

Cell Stabilizer: Davco ^® DC 193 available from Air Products

Isocyanate prepolymers: prepolymers based on 4,4'-MDI and PESOL1, NCO content = 17.4%

Hydrolysis inhibitor (ai): triphenyl phosphite

Hydrolysis inhibitor (aii): triethylenediamine

Composition of systems C1 to C3 (comparative example) and 1 to 4 (embodiment of the invention) C1 C2 C3 One 2 3 4 A PESOL1 89.24 89.24 89.24 89.24 89.24 89.24 89.24 Monoethylene glycol 8.6 8.6 8.6 8.6 8.6 8.6 8.6 water 0.475 0.475 0.475 0.475 0.475 0.475 0.475 Amine catalyst 1.63 1.63 1.63 1.63 1.63 1.63 1.63 Cell stabilizer 0.14 0.14 0.14 0.14 0.14 0.14 0.14 B Isocyanate Prepolymer 104 104 104 104 104 104 104 Hydrolysis inhibitor (ai) 0 6.5 13.05 0.014 0.135 0.677 1.3 Molar ratio [(hydrolysis inhibitor (ai)) / (hydrolysis inhibitor (aii))] 0.0 5 10 0.01 0.1 0.5 1.0

Aging results for samples C1 to C3 and 1 to 4 C1 C2 C3 One 2 3 4 Tensile Strength [N / mm ² ] t = 0 8 6.7 5.5 7.9 7.8 8 7.4 t = 14 2.8 n.m. n.m. 3.2 3.2 4.6 2.9 Residual Tensile Strength [%] ^(a) 35 0 0 40 41 57 39 Elongation [%] t = 0 429 431 392 441 452 444 452 t = 14 291 n.m. n.m. 362 359 438 321 Residual Elongation [%] ^(a) 67 0 0 82 79 98 71  (a) = residual tensile strength or elongation (% of starting value) after 2 weeks of aging n.m. = not measurable (sample decomposition) t = aging period (days)

Claims (13)

A microcell type polyurethane elastomer which can be prepared by reacting a compound containing at least two hydrogen atoms reactive with isocyanate groups with a polyisocyanate, wherein the (ai) aromatic phosphite having a phosphorus content of 9.00% to 11.00% by weight and ( aii) A microcell polyurethane elastomer comprising a combination (a) consisting of an amine compound, wherein the molar ratio of (ai) and (aii) is 0.005 to 4.0. The microcell type polyurethane elastomer according to claim 1, wherein the molar ratio of (ai) and (aii) is 0.1 to 3.0. The microcell type polyurethane elastomer according to claim 1, wherein the molar ratio of (ai) and (aii) is 0.5 to 2.0. The microcell-type polyurethane elastomer according to claim 1, wherein the phosphorous content of the aromatic phosphite is 9.90% to 10.10% by weight. The microcell-type polyurethane elastomer according to claim 1, wherein the phosphorous content of the aromatic phosphite is 9.95% by weight to 10.05% by weight. The microcell type polyurethane elastomer according to claim 1, wherein the aromatic phosphite is triphenyl phosphite. The microcell type polyurethane elastomer according to claim 1, wherein the amine (aii) used is a tertiary amine. The compound of claim 1, wherein the tertiary amine is triethylamine, triethylenediamine, tributylamine, dimethylbenzylamine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N ' Tetramethylbutanediamine, N, N, N ', N'-tetramethylhexane-1,6-diamine, dimethylcyclohexylamine, pentamethyldipropylenetriamine, pentamethyldiethylenetriamine, 3-methyl-6 -Dimethylamino-3-azapentol, dimethylaminopropylamine, 1,3-bisdimethylaminobutane, bis (2-dimethylaminoethyl) ether, N-ethylmorpholine, N-methylmorpholine, N-cyclohexylmor Pauline, 2-dimethylaminoethoxyethanol, dimethylethanolamine, tetramethylhexamethylenediamine, dimethylamino-N-methylethanolamine, N-methylimidazole, N- (3-aminopropyl) imidazole, N- ( 3-aminopropyl) -2-methylimidazole, 1- (2-hydroxyethyl) imidazole, N-formyl-N, N'-dimethylbutylenediamine, N-dimethylaminoethylmorpholine, 3, 3'-rain -Dimethylaminodi-n-propylamine and / or 2,2'-dipiperazindiisopropyl ether, dimethylpiperazine, N, N'-bis (3-aminopropyl) ethylenediamine and / or tris (N, N -Dimethylaminopropyl) -s-hexahydrotriazine, or a microcell-type polyurethane elastomer selected from the group comprising a mixture comprising two or more of the amines. The microcell type polyurethane elastomer according to claim 1, wherein the tertiary amine is triethylenediamine. A method of preparing a microcell-type polyurethane elastomer by reacting a polyisocyanate with a compound containing two or more hydrogen atoms reactive with isocyanate groups, comprising: (ai) aromatic phosphites having a phosphorus content of 9.00% to 11.00% by weight; aii) carrying out the reaction in the presence of a hydrolysis inhibitor (a) which is a combination consisting of an amine compound, wherein the molar ratio of (ai) and (aii) is from 0.005 to 4.0. Use of the microcell-type polyurethane elastomer according to any one of claims 1 to 9 for producing a shoe sole. Use of an aromatic phosphite and (aii) an amine compound having (ai) phosphorus content of 9.00% to 11.00% by weight as a hydrolysis inhibitor for microcell-like polyurethane elastomers.  A shoe sole comprising the microcell-type polyurethane elastomer according to any one of claims 1 to 9.