WO2006066763A1

WO2006066763A1 - Method for producing microcellular polyurethane elastomers

Info

Publication number: WO2006066763A1
Application number: PCT/EP2005/013405
Authority: WO
Inventors: Markus SCHÜTTE; Diane Terese Langer
Original assignee: Basf Aktiengesellschaft
Priority date: 2004-12-17
Filing date: 2005-12-14
Publication date: 2006-06-29
Also published as: DE102004061609B4; KR20070100937A; CN101080428A; CN101080428B; DE102004061609A1

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

Process for the preparation of microcellular polyurethane elastomers

Polyurethane integral foams, often referred to as microcellular polyurethane elastomers and hereinafter also referred to as MPE, have been known for a long time and are used, for example, for the production of shoe soles. They are described, for example, in the Kunststoffhandbuch, volume 7 "Polyurethane", 3rd edition, page 376 et seq., They are prepared by reacting polyisocyanates with compounds having at least two isocyanate-reactive hydrogen atoms as compounds having at least two hydrogen atoms reactive with isocyanate groups These materials are often used to produce high performance materials such as high elasticity, high tensile and tear strength or low abrasion, while at the same time processing such systems with high process reliability, a disadvantage of microcellular polyester-based polyurethane elastomers The low resistance to hydrolysis is caused by the intrinsic susceptibility of the ester groups to hydrolytic degradation, and the cleavage of the ester groups causes a reduction in the molar mass e of the polymer and leads to a deterioration of the performance, which can lead to total material failure in extreme cases.

Therefore, there have been many attempts in the past to increase the hydrolysis resistance of such materials.

As a way to improve the hydrolysis resistance of polyester-based microcellular polyurethane elastomers, the use of special polyester alcohols is suggested. By way of example, mention may 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. In addition, the substitution or partial substitution of the polyester alcohols for hydrolysis-resistant polyether alcohols is described.

Another possibility for improving the hydrolysis resistance is the use of certain additives, which are usually used in amounts of less than 10 wt .-%. 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 carbodiimides.

However, the solutions to be taken from the prior art usually have disadvantages. In some cases, higher hydrolysis resistances are achieved, but at the same time only insufficient use properties are obtained before aging. In addition, some solutions can not be realized in practice due to the higher input costs. This can be done, for example, in the case of the use of special len polyester alcohols or high amounts of certain additives occur. Another disadvantage of many of the prior art solutions to be taken is the reduction of the storage stability of the components. Furthermore, many solutions have too low an efficacy, especially if extremely high demands are made on the hydrolysis resistance.

The use of phosphites generally in microcellular polyurethane elastomers is known and is described e.g. in Kunststoffhandbuch, volume 7 "Polyurethane", 3rd edition, page 120 ff., phosphites are used as antioxidants, and their use in combination with typical antioxidants, such as sterically hindered phenols, leads to a synergistic effect Effect, combined with a significant increase in the effect of preventing thermal oxidation processes.

JP 61128904 describes the use of 4-14% by weight of phosphite esters in polyester-based microcellular polyurethane elastomers. Phosphites based on phenol and long-chain alkyl radicals are used as yellowing inhibitors. The phosphites are used in the prepolymer. JP 63278962 describes UV-stable polyester-based MPE for shoe soles. Phosphites are used as antioxidant aids together with sterically hindered phenols as antioxidant. The proportion by weight is 1 wt .-%. JP 63305162 describes a UV stabilization package for polyester alcohol-based MPE. Here is u.a. Triphenyl phosphite (TPP) as an antioxidant aid in connection with sterically hindered phenols mentioned. The proportion by weight is 0.5% by weight. JP 05214240 describes a UV protection for PUR shoe soles which i.a. Contains thiophosphites in amounts of about 1%.

JP 2003147057 describes the use of polycarbonate diols in shoe systems. The example mentions that about 2% by weight of TPP is added to the prepolymer.

JP 61128904, JP 63278962 and JP 05214240 generally describe the use of phosphites in polyester-based MPE as antioxidant aids. The documents JP 63278962 and JP 63305162 mention that i.a. aromatic phosphites can be used as an antioxidant in the isocyanate-reactive component. The document JP 2003147057 describes the use of aromatic phosphites in microcellular polyurethane elastomers based on polyether carbonate alcohols.

The object of the present application was to provide a hydrolysis protection agent for polyester alcohol-based MPE, which allows a high effect at low input and guarantees high efficiency regardless of the polyester alcohol used. The object could be achieved by the use of a special hydrolysis protection agent a), consisting of a combination of ai) an aromatic phosphite with a phosphorus content of 9.00 to 11, 00 wt .-%, preferably 9.90 to 10 , 10 wt .-% and in particular 9.95 to 10.05 wt .-% and aii) an amine compound such as triethylenediamine, wherein the molar ratio between ai) and aii) preferably 0.005 to 4.0, particularly preferably. 0.1 to 3.0, and especially 0.5 to 2.0. is. The component ai) is preferably used in the isocyanate-containing component (B component) and aii) in the isocyanate-reactive component (A component).

The invention accordingly MPE, can be prepared by reacting polyisocyanates with compounds having at least two isocyanate-reactive hydrogen atoms, characterized in that it is a combination of a) consisting of ai) an aromatic phosphite having a phosphorus content of 9.00 to 11 , 00 wt .-%, and aii) of an amine compound, wherein the molar ratio between ai) and aii) is 0.005 to 4.0.

The invention furthermore relates to a process for the preparation of MPE by reacting polyisocyanates with compounds having at least two isocyanate-reactive hydrogen atoms, characterized in that the reaction in the presence of a), which comprises a combination consisting of ai) an aromatic phosphite with phosphorus content of 9.00 to 11.00 wt%, and aii) an amine compound, wherein the molar ratio between ai) and aii) is 0.005 to 4.0.

The invention also provides the use of a combination of ai) an aromatic phosphite having a phosphorus content of 9.00 to 11, 00 wt .-%, and aii) an amine compound as a hydrolysis protection for MPE.

The invention also relates to shoe soles comprising the microcellular polyurethane elastomers according to the invention.

The molar ratio between ai) and aii) is preferably 0.1 to 3.0, and more preferably 0.5 to 2.0.

The phosphorus content of component ai) is preferably 9.90 to 10.10 wt .-% and in particular 9.95 to 10.05 wt .-%.

The component ai) used is preferably triphenyl phosphite (TPP). 4

As amine compounds aii) primary, secondary and preferably tertiary amines can be used. These are preferably those amines which are customarily used as catalysts for the preparation of polyurethanes.

Preference is given to tertiary amines selected from the groups comprising triethylamine, triethylenediamine, tributylamine, dimethylbenzylamine, N, N ₁ N ', N'-tetramethylethylenediamine, N, N, N', N'-tetramethylbutanediamine, N, N , N ', N'-tetramethylhexane-1,6-diamine, dimethylcyclohexylamine, pentamethyldipropylenetriamine, penta-methyldiethylenetriamine, 3-methyl-6-dimethylamino-3-azapentol, dimethylaminopropylamine, 1,3-bisdimethylaminobutane, bis ( 2-dimethylaminoethyl) ether, N-ethylmorpholine, N-methylmorpholine, N-cyclohexylmorpholine, 2-dimethylaminoethoxyethanol, dimethylethanolamine, tetramethylhexamethylenediamine, dimethylamino-N-methylethanolamine, N-methylimidazole, N- Aminopropyl) imidazole, N- (3-aminopropyl) -2-methylimidazole, 1- (2-hydroxyethyl) imidazole, N-formyl-N, N'-dimethylbutylenediamine, N-dimethylaminoethylmorpholine, 3,3'-bis-dimethylamino-di n-propylamine and / or 2,2'-dipiparazin diisopropyl ether, dimethylpiparazine, N, N'-bis (3-aminopropyl) ethylenediamine and / or tris (N, N-dimethylaminopropyl) -s-hexahydrotriazine, or mixtures containing at least two of said amines, wherein higher molecular weight tertiary amines, as described for example in DE-A 28 12 256, can be used. Triethylenediamine is particularly preferably used.

In most cases, the amount of tertiary amines used as a catalyst is sufficient to achieve the required stabilizing effect in combination with the aromatic phosphites ai). However, it is also possible to use additional amines when using other than amine catalysts or when using smaller amounts of amine catalysts than required for adequate stabilization. These will not be the tertiary amines used as catalysts in the process to exclude catalysis disturbances.

Preferably, the hydrolysis protection agent a) in an amount of 0.0001 to 3, 0.0005 to 2 and 0.001 to 1, 6 wt .-%, based on the weight of the MPE used.

The following can be said in detail about the starting materials used to prepare the MPE according to the invention.

The polyisocyanates used in the process according to the invention include the known from the prior art aliphatic, cycloaliphatic and aromatic isocyanates and any mixtures thereof. Examples are diisocyanate 4,4 ^{'diphenylmethane} ~, the mixtures of monomeric diphenylmethane diisocyanates and higher-nuclear homologues of diphenylmethane diisocyanate (polymeric MDI), tetramethylene 5 013405

O is diisocyanate, hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI) or mixtures thereof.

Preferably, 4,4'-MDI and / or HDI is used. The most preferred 4,4'-MDI may contain minor amounts, up to about 10% by weight, of allophanate- or urethane-onimine-modified polyisocyanates. It is also possible to use small amounts of polyphenylenepolymethylene polyisocyanate (crude MDI). The total amount of these high-functionality polyisocyanates should not exceed 5% by weight of the isocyanate used. Furthermore, the 4,4'-MDI may contain small amounts, preferably at most 10% by weight, of 2,4'-MDI.

The polyisocyanates can also be used in the form of polyisocyanate prepolymers. These prepolymers are known in the art. The preparation is carried out in a manner known per se, by reacting polyisocyanates described above, for example at temperatures of about 8O ⁰ C, with the compounds described below with isocyanate-reactive hydrogen atoms to the prepolymer. The polyol-polyisocyanate ratio is generally chosen so that the NCO content of the prepolymer 8 to 25 wt .-%, preferably 10 to 22 wt .-%, particularly preferably 13 to 20 wt .-% is.

As compounds with isocyanate-reactive hydrogen atoms, as described, polyester alcohols are used.

The polyester alcohols are generally obtained by condensation of polyfunctional alcohols, preferably diols, having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, with polyfunctional carboxylic acids having 2 to 12 carbon atoms, for example 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.

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

In general, the polyester alcohols used for the process according to the invention have an average theoretical functionality of 2 to 4, preferably of more than 2 to less than 3 and the above-mentioned number average molecular weights. b

The polyester alcohols used can in principle also be used in a mixture with polyether alcohols. However, since such mixtures often have insufficient phase stability, the use of such mixtures is not preferred.

The compounds having two active hydrogen atoms also include the optionally used chain extenders. Suitable chain extenders are known in the art. Preference is given to using 2-functional alcohols having molecular weights below 400 g / mol, in particular in the range from 60 to 150 g / mol. Examples are ethylene glycol, 1,3-propanediol, diethylene glycol, butanediol-1, 4, glycerol or trimethylolpropane, and mixtures thereof. Preferably, ethylene glycol is used.

The chain extender, if used, is usually present in an amount of from 1 to 15% by weight, preferably from 3 to 12% by weight, more preferably from 4 to 10% by weight, based on the total weight of the two compounds Isocyanatatgruppen reactive hydrogen atoms used.

The reaction of the polyisocyanates with the compounds having two active hydrogen atoms is usually carried out in the presence of blowing agents. As blowing agents it is possible to use generally known chemically or physically active compounds. As the chemically acting blowing agent, water can preferably be used. Examples of physical blowing agents are inert (cyclo) aliphatic hydrocarbons having from 4 to 8 carbon atoms which evaporate under the conditions of polyurethane formation. The amount of blowing agent used depends on the desired density of the foams.

The reaction of the polyisocyanates with the compounds with two active hydrogen atoms is optionally carried out in the presence of catalysts and of auxiliaries and / or additives, such. Cell regulators, release agents, pigments, reinforcing agents such as glass fibers, surface-active compounds and / or stabilizers against oxidative, thermal or microbial degradation or aging.

Catalysts for the preparation of the microcellular polyurethane elastomers according to the invention can be the customary and known polyurethane-forming catalysts, for example organic metal compounds, such as tin diacetate, tin dioctoate, dibutyltin dilaurate, and / or strongly basic amines, such as diazabicyclooctane, bis (N, N-dimethylaminoethyl) ether or the above-mentioned amines. The catalysts are preferably used in an amount of from 0.01 to 10% by weight, preferably from 0.02 to 5% by weight, based on the reaction mixture. As described above, amines, in particular tertiary amines, are preferably used as catalysts. The amines can, as described above, individually or as any mixtures with one another set. These act simultaneously in the microcellular polyurethane elastomers as component aii). For this purpose, it is preferred to use only the amines mentioned in the amounts required for the action as a stabilizer. If this is not sufficient for the catalytic effect, the tertiary amines can be used in combination with other catalysts.

As organic amines known from the prior art tertiary amines are useful. For example, suitable are 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-bis-dimethylaminobutane, bis (2-dimethylaminoethyl) - ether, N-ethylmorpholine, N-methylmorpholine, N-cyclohexylmorpholine, 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-ethylmorpholine, 3,3'-bis-dimethylamino-di-n- propylamine and / or 2,2'-dipiparazin diisopropyl ether, dimethyl piparazine, N, N'-bis (3-aminopropyl) ethylenediamine and / or tris (N, N-dimethylaminopropyl) -s-hexahydr otriazine, or mixtures containing at least two of said amines, wherein higher molecular weight tertiary amines, as described for example in DE-A 28 12 256, are possible. Particularly preferred is the use of triethylenediamine.

The catalysts which can be used in a mixture with the tertiary amines are, as described above, mainly organic metal compounds, in particular tin compounds, such as tin diacetate, tin dioctoate, dibutyltin dilaurate, and / or bismuth compound.

The catalysts are preferably mixed with the compounds having at least two isocyanate-reactive hydrogen atoms. In principle, it is also possible to mix at least the organic metal compounds with the polyisocyanates.

In general, the polyisocyanates are referred to as the isocyanate component and the compounds having at least two isocyanate-reactive hydrogen atoms, which is usually used in admixture with the catalysts, optionally the blowing agents and additives, as a polyol component. For the preparation of polyurethane foams, the isocyanate component and the polyol component are usually reacted in amounts such that the equivalent ratio of NCO groups to the sum of the reactive hydrogen atoms is 1: 0.8 to 1: 1, 25, preferably 1: 0.9 to 1 : 1, 15 is. A ratio of 1: 1 corresponds to an NGO index of 100.

The reaction to the microcellular polyurethane elastomer is preferably carried out in densified forms. The molds are preferably made of metal, for example steel or aluminum, or else of plastic, for example epoxy resin. The starting components are mixed at temperatures of 15 to 90 ^° C., preferably at 20 to 35 ^° C., and if appropriate under elevated pressure, introduced into the preferably closed molding tool. The mixing can be carried out during introduction by known in the art high or low pressure mixing heads. The mold temperature is generally between 20 and 90 ⁰ C, preferably between 30 and 60 ° C.

The amount of the reaction mixture introduced into the mold is such that the resulting molded articles have a density of from 250 to 600 g / l or from 800 to 1200 g / l, preferably from 400 to 600 g / l or from 820 to 1050 g / l , exhibit. The degrees of compression of the resulting microcellular polyurethane elastomers are between 1, 1 and 8.5, preferably between 1.2 and 5, particularly preferably between 1, 5 and 4.

The microcellular polyurethane elastomers according to the invention can be used for steering wheels, safety clothing and preferably for shoe soles.

The invention will be explained in more detail in the following examples.

Comparative Examples V1 to V3 and Examples 1 to 4

100 parts by weight of the polyol component and the specified in Table 1 parts by weight of the isocyanate component were thoroughly mixed at 23 ° C and the mixture in a tempered at 50 ⁰ C, plate-shaped aluminum mold with dimensions of 20cm x 20 cm × 1 cm in such an amount that after foaming and curing in the closed mold, a microcellular polyurethane elastomer plate with a total density of 550 g / l resulted.

From the elastomer plates produced in this way, shoulder bars were punched out as test specimens after 24 hours of storage with a punching tool. Before the beginning of the aging tests, the initial values of the tensile strength according to DIN 53543 were determined. The specimens were then after an aging test at 70 ⁰ C under water after DIN 53543 subjected. Sampling takes place after 14 days. The results of the tests are summarized in Table 2.

The residual tensile strength and elongation after 2 weeks hydrolysis aging of samples 1-4 is significantly higher than that of comparative samples V1 -V3.

Used ingredients:

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

Amine catalyst: 33% strength by weight solution of triethylenediamine in ethylene glycol (Lupragen ^® N 202) BASF AG

Cell stabilizer: Dabco ^® DC 193 from Air Products

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

Hydrolysis protection agent ai): triphenyl phosphite

Hydrolysis protection agent aii): triethylenediamine

Table 1: Composition of the systems V1-V3 (comparative examples) and 1-4 (examples according to the invention).

Table 2: Aging results of samples V1-V3 and 1-4.

a) = residual tensile strength or residual strain in% of the initial value after 2 weeks of aging.

n.m. = not measurable (sample destroyed)

t = aging interval in days

Claims

claims

1. Microcellular polyurethane elastomers obtainable by reacting polyisocyanates with compounds having at least two isocyanate-reactive hydrogen atoms, characterized in that they contain a combination a) consisting of ai) an aromatic phosphite having a phosphorus content of 9 , 00 to 11, 00 wt .-%, and aii) of an amine compound, wherein the molar ratio between ai) and aii) is 0.005 to 4.0.

2. Microcellular polyurethane elastomers according to claim 1, characterized in that the molar ratio between ai) and aii) is 0.1 to 3.0.

3. Microcellular polyurethane elastomers according to claim 1, characterized in that the molar ratio between ai) and aii) is 0.5 to 2.0.

4. Microcellular polyurethane elastomers according to claim 1, characterized in that the aromatic phosphite has a phosphorus content of 9.90 to 10.10 wt .-%.

5. Microcellular polyurethane elastomers according to claim 1, characterized in that the aromatic phosphite has a phosphorus content of 9.95 to 10.05 wt .-%.

6. Microcellular polyurethane elastomers according to claim 1, characterized in that the aromatic phosphite is triphenyl phosphite.

7. Microcellular polyurethane elastomers according to claim 1, characterized in that tertiary amines are used as amines aii).

8. Microcellular polyurethane elastomers according to claim 1, characterized in that the tertiary amines are selected from the group comprising 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-cyclohexylmorpholine, 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-dimethylaminoethylmomholin. 3,3'-bis-dimethylamino-di-n-propylamine and / or 2,2'-dipiparazinone diisopropyl ether, dimethyl piparazine, N, N'-bis (3-aminopropyl) ethylenediamine and / or tris (N, N-dimethylaminopropyl) -s-hexahydrotriazine, or mixtures containing at least two of said amines.

9. Microcellular polyurethane elastomers according to claim 1, characterized in that the tertiary amine is triethylenediamine.

10. A process for the preparation of microcellular polyurethane elastomers by reacting polyisocyanates with compounds having at least two isocyanate-reactive hydrogen atoms, characterized in that the

Reacting in the presence of a hydrolysis protection agent a), which is a combination consisting of ai) an aromatic phosphite having a phosphorus content of 9.00 to 11, 00 wt .-%, and aii) an amine compound, wherein the molar Ratio between ai) and aii) is 0.005 to 4.0.

11. Use of microcellular polyurethane elastomers according to any one of claims 1-9 for the production of shoe soles.

12. Use of ai) an aromatic phosphite having a phosphorus content of 9.00 to 11.00% by weight, and aii) an amine compound as a hydrolysis protection agent for microcellular polyurethane elastomers.

13. shoe soles containing microcellular polyurethane elastomers according to any one of claims 1 to 9.