DE4020456A1 - USE OF AQUEOUS POLYURETHANE DISPERSIONS IN LEATHER MAKING - Google Patents

Abstract

The invention concerns the use, in the dressing of leather, of an aqueous polyurethane dispersion containing 100 parts by weight of di- and/or polyisocyanates, 61 to 450 parts by weight (relative to the isocyanate content) of castor oil and/or epoxidized fatty-acid esters ring-opened with C1-8 alkyl alcohols.

Description

The invention relates to the use of an aqueous polyurethane dispersion which, based on 100 parts by weight of di- and / or polyisocyanates, contains 61 to 450 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C _1-8 alkyl alcohols, in leather finishing.

The protective layer is referred to as leather finishing after tanning and greasing, dried leather is applied to protect it against moisture, pollution and damage (Ullmann's Encyclopedia of Technical Chemistry, 4th Edition, Volume 16, Pages 159-163, Verlag Chemie Weinheim, 1978). The preparation film must adhere firmly to the leather and extremely high bending and stretching requirements during further processing as well as during of later use are sufficient. Furthermore, the surface of the Preparatory film be hard enough to withstand sufficient resistance Damage from dry and wet rubbing, bumping and scratching to guarantee. So that the preparation film this different Can meet requirements, it will be in several thin layers from various finishing fleets, especially primer and Final fleets, with intermediate drying and given if intermediate bars and embossing are applied.  

In many cases, the finishing liquors contain polyurethanes, thermoplastic polyacrylates and / or butadiene copolymers as film-forming substances. DE 37 02 615 describes polyurethane dispersions as coating and finishing agents for leather whose polyurethane solids, based on 100 parts by weight of isocyanate component, 6 to 60 parts by weight of castor oil, alkoxylated castor oil and / or epoxidized triglycerides ring-opened with C _1-8 alkyl alcohols, which are optionally alkoxylated. Leather that has been finished with these polyurethane dispersions has good fastness properties.

It has now been found that the fastness properties achieved with the polyurethane dispersions known from DE 37 02 615 are significantly improved if a polyurethane dispersion is used whose polyurethane solids, based on 100 parts by weight of isocyanate component, 61 to 450 parts by weight of castor oil and / or with C _{1 -8} -Alkyl alcohols contains ring-opened epoxidized fatty acid esters.

Accordingly, the subject of the invention is the use of an aqueous polyurethane dispersion having a solids content of between 10 and 50% by weight and a Brookfield viscosity at 20 ° C. of between 10 and 5000 mPa · s, the polyurethane solids based on 100 parts by weight of di- and / or polyisocyanates, 61-450 parts by weight of castor oil and / or with C _1- 8 alkyl alcohols ring-opened epoxidized fatty acid ester contains, in leather finishing.

Preferably, a polyurethane dispersion is used whose polyurethane solids, based on 100 parts by weight of di- and / or polyisocyanates, contains 80 to 200 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C _1-8 alkyl alcohols.

Suitable epoxidized fatty acid esters, the epoxy rings of which are opened with C _1-8 alkyl alcohols, are preferably epoxidized fatty acid mono-, di- and / or triglycerides which are obtained by epoxidation of unsaturated oils, especially soybean oil, linseed oil, tall oil, cottonseed oil, peanut oil, Palm oil, sunflower oil, rape oil and / or claw oil are accessible. According to the process described in DE-PS 8 57 364, unsaturated fatty acid esters can be epoxidized by reaction with peracetic acid in the presence of acidic catalysts or with formic acid formed in situ from formic acid and hydrogen peroxide. Then the epoxidized fatty acid esters with monohydric C _1-8 alkyl alcohols, for example methanol, ethanol, n-propanol, iso-propanol, n-butanol, n-pentanol, n-hexanol, 2-ethylhexanol, n-heptanol and / or n Octanol, but preferably with methanol in the presence of catalysts, for example sodium methylate or potassium hydroxide, at temperatures between 40 and 160 ° C. and pressures between 10 ⁴ and 3 × 10 ⁵ Pa.

As a further polyol component, the ver according to the invention turning polyurethanes containing polyester polyols aliphatic and / or aromatic dicarboxylic acids and diols are built. Aliphatic dicarboxylic acids are suitable for for example succinic acid, adipic acid, suberic acid, azelaic acid, Sebacic acid, brassylic acid and / or dimer fatty acids. Examples suitable aromatic dicarboxylic acids are phthalic acid, Isophthalic acid, terephthalic acid and / or tetrahydrophthalic acid. As Aliphatic dicarboxylic acid is called adipic acid and aromatic Dicarboxylic acid isophthalic acid preferred. The above Dicarboxylic acids are mixed with diols,  for example ethylene glycol, 1,2-propanediol, 1,3-propanediol, Diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, Dimerocenol (Sovermol® 650NS, Henkel KGaA) and / or Neopentyl glycol, esterified.

The polyurethanes to be used according to the invention can also Polyether polyols with average molecular weights between 1000 and 20,000, preferably between 3,000 and 12,000. Be polyether polyols of the general formula are particularly preferred

in which R denotes an alkoxy radical which is derived from glycerol, diglycerol, polyglycerol with a degree of polymerization x between 3 and 6, trimethylolpropane or trimethylolethane, the index x means the degree of polymerization of the alkoxy radical, the indices y are a number between 1 and 8 and z mean a number between 0 and 8, with the proviso that the sum y + z is between 1 and 8, the indices a a number between 1 and 15, b a number between 20 and 100, c a number between 1 and 15 , d is a number between 20 and 150 and e is a number between 1 and 15, with the proviso that the sums a + c + e between 3 and 40, b + d between 40 and 300 and c + e between 1 and 15 lie. Preferred polyether polyols are those of the general formula in which R is an alkoxy radical derived from glycerol or trimethylolpropane, the indices y are 2 or 3 and z is 0 or 1, with the proviso that the sum y + z is 2 or 3 , and the indices a, c and e each represent a number between 1 and 5 and b and d each represent a number between 30 and 100, with the proviso that the sums a + c + e between 3 and 20, b + d between 60 and 200 and c + e are between 1 and 10. The polyether polyols of the general formula are known compounds which, in a manner known per se, by alkoxylation of glycerol, diglycerol, polyglycerol with a degree of polymerization between 3 and 6, trimethylolpropane or trimethylolethane with ethylene oxide and propylene oxide at temperatures between 110 and 200 ° C. and pressures between 10 ⁵ and 2 × 10 ⁶ Pa are accessible.

In order to ensure dispersibility in water, the Production of dihydroxy polyurethanes to be used according to the invention and / or diamino compounds used as anionic groups preferably one or more carboxylate, sulfonate and / or Am contain monium groups, for example dimethylolpropionic acid, Tartaric acid and / or 2,4-diaminobenzenesulfonic acid.

The polyurethanes to be used according to the invention contain, based on 100 parts by weight of isocyanate component, 61 to 450 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C _1-8 alkyl alcohols, 0 to 300 parts by weight of polyester polyols, 0 to 60 parts by weight of polyether polyols and 5 to 50 parts by weight of anio dihydroxy and / or diamino compounds bearing niche groups, preferably 80 to 200 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C _1-8 alkyl alcohols, 1 to 180 parts by weight of polyester polyols, 0 to 20 parts by weight of polyether polyols and 5 to 30 parts by weight of anionic group-bearing dihydroxy and / or diamino compounds, with the proviso that the proportion of the OH equivalents of the polyester polyols, polyether polyols and dihydroxy compounds bearing anionic groups is between 10 and 80%, preferably between 20 and 70% of all OH equivalents.

Aliphatic are suitable as organic di- and / or polyisocyanates and / or aromatic di- and / or triisocyanates, for example Dicyclohexylmethane-4,4'-diisocyanate, 1,6-hexane diisocyanate, 3- Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (Isophorondi isocyanate), tetramethylene diisocyanates, trimethylhexamethylene di isocyanates, dimer fatty acid diisocyanates, 1,4-phenylene diisocyanate, Diphenylmethane diisocyanates, toluene-2,4- and / or toluene ol-2,6-diisocyanate, 2,4,4'-triisocyanatodiphenyl ether and / or 4 ′, 4 ′, 4′-triisocyanato-triphenylmethane. Ali are preferred phatic diisocyanates, especially isophorone diisocyanate, di cyclohexylmethane-4,4'-diisocyanate, 1,6-hexane diisocyanate and / or Dimer fatty acid diisocyanates.

So-called blocked di- and / or polyisocya can also be used nate alone or in combination with the above not bloc Kiert di- and / or polyisocyanates are used. The bloc cated di- and polyisocyanates are opposite at room temperature Hydroxyl groups resistant and only react at temperatures above 50 ° C. Based on the total amount used Di- and / or polyisocyanates contain blocked di- and / or polyisocyanates between 0 and 60% by weight, preferably between 0 and 10% by weight. The production of blocked di and Polyisocyanates are made by reacting organic di- or Polyisocyanates, for example isophorone diisocyanate, with an Al alcohol, for example phenol or m-cresol, in such amounts that all isocyanate groups are blocked.

The polyurethanes to be used according to the invention can, according to be known processes (Ullmanns Encyclopedia of technical chemistry, volume 19, pages 302 ff., Verlag Chemie Wein Heim, 1980). Di- and / or polyisocyanates are preferred Dihydroxy and / or polyols and anionic groups  Diamino compounds in the presence of solvents, for example N-methylpyrrolidone and / or methyl ethyl ketone, and optionally Catalysts, such as N-methylmorpholine, at temperatures between 60 and 120 ° C converted to prepolymers. After that the Polyurethane prepolymer mass dispersed in water and then optionally with chain extenders, such as alkoxylated glycerols and / or diamines, for example ethylenediamine, hexamethylenediamine and / or piperazine. During the dispersion and ket elongation of polyurethanes react in the polyurethane Prepolymer still existing NCO groups with water under Carbon dioxide formation, causing it to become not insignificant, disrupt the foaming comes. In the manufacture of an invention polyurethane dispersion to be used, however, if over at all, such small amounts of foam formed that almost always on one Addition of defoamers can be dispensed with.

A polyurethane dispersion with a high content of castor oil and / or epoxidized fatty acid esters ring-opened with C _1-8 alkyl alcohols as a polyol component in the polyurethane solid, a solids content between 10 and 50% by weight and a Brookfield viscosity at 20 ° C between 10 and 5000 mPa · s can be used according to the invention in the leather finishing in primer, color and / or finishing liquors. The additive liquors include pigment preparations, film-forming substances in the form of aqueous dispersions, such as polyacrylates and / or polyurethanes, binders and fillers, matting agents, penetrators and / or plasticizers. The finishing liquors can be applied using all of the technologies customary in leather finishing, for example by spraying, plushing, pouring and / or roller application. The finishing liquors contain polyurethane dispersions to be used according to the invention in amounts of 1 to 60% by weight.

Leather with a polyurethane to be used according to the invention dispersion have been compared to leather, which with a polyurethane dispersion prepared according to DE 37 02 615 were significantly improved fastness properties, in particular a significantly improved wet rub fastness.  

Examples Production of aqueous polyurethane dispersions according to the invention

To determine the solids content of the aqueous polyurethane dispersions, 10.0 g of the respective polyurethane dispersion were weighed into an aluminum dish. After drying in a drying cabinet at 125 ° C. for 15 hours, the dry residue was determined by weighing the aluminum pan.
calculation

example 1

In a well dried 3-stage glass laboratory reactor Stainless steel MIG stirrers were made of 182.6 g polyester at 25 ° C Adipic acid, isophthalic acid and diethylene glycol with an OH number (OHZ) of 59, 129.2 g soybean oil epoxide, ring opened with methanol (OHZ = 200), 30.0 g dimethylolpropionic acid, 27.2 g N-methylmorpholine and Given 45.1 g of N-methylpyrrolidone. After homogenization 146.7 g of isophorone diisocyanate were added to the polyol mixture. After this the reaction mixture after 2.5 hours at 80 ° C an NCO content of 2.4% by weight, 528.7 g of fully desalted water became water at a temperature of 15 ° C to the prepolymer mass. Then 3.3 g of glycerol × 7 mol Ethylene oxide × 81 moles of propylene oxide (OHZ = 34) to the 35 ° C warm Given polyurethane dispersion. After heating to 60 ° C, the Polyurethane dispersion due to the reaction between the NCO groups and water formed foamed carbon dioxide  (Foam height: 3 cm) was stirred at this temperature for 4 hours and then cooled to room temperature. It turned white stable, 39.6 wt .-% aqueous polyurethane dispersion with a pH of 7.1 and a bookfield viscosity at 20 ° C of 550mPas obtained.

Example 2

The polyurethane prepolymer was analogous to Example 1 in the same Apparatus manufactured. Instead of 129.2 g, 226.1 g Soybean oil epoxide, ring opened with methanol (OHZ = 200) used. To the prepolymer obtained was then fully ent 528.7 g salted water at a temperature of 15 ° C. After warming up at 60 ° C was stirred for 4 hours at this temperature (Schaumhö he: 1 cm) and then cooled to room temperature. there has been a white, stable, 40.4 wt .-% aqueous polyurethane dispersion with a pH of 7.2 and a Brookfield viscosity at 20 ° C of 3500 mPas obtained.

Comparative Example 1 (according to DE 37 02 615)

Analogously to Example 1, a Polyurethane dispersion made. Instead of 129.2 g each but 64.6 g soybean oil epoxide, ring opened with methanol (OHZ = 200) used. After adding 3.3 g of glycerol × 7 moles of ethylene oxide × 31 moles Propylene oxide (OHZ = 34) and heating to 60 ° C occurred foam on (foam height: 9 cm). After stirring for 4 hours at 60 ° C was cooled to room temperature. It became a white, stable, 40.2% by weight aqueous polyurethane dispersion with a pH of 7.0 and a Brookfield viscosity at 20 ° C of 800 mPas ten.  

Example 3

The polyurethane dispersion was the same as in Example 1 Equipment manufactured at the same level. Instead of 129.2 g Soybean oil epoxide, ring opened with methanol, was 129.2 g castor oil (OHZ = 158) used. After adding 3.3 g glycerol × 7 mol Ethylene oxide × 81 moles of propylene oxide (OHZ = 34) and heating to 60 ° C small amounts of foam were formed (foam height: 3 cm). It was a white, stable, 39.3% by weight aqueous polyurethane dispersion with a pH of 7.1 and a Brookfield viscosity at 20 ° C obtained from 2500 mPa · s.

Example 4

The polyurethane dispersion was the same as in Example 2 Apparatus manufactured. Instead of 226.1 g soybean oil epoxide, ring-opened with methanol were 226.1 g castor oil (OHZ = 158) used. After heating the dispersion to 60 ° C became low Amounts of foam formed (foam height: 2 cm). It turned white stable, 40.9 wt .-% aqueous polyurethane dispersion with a pH of 7.4 and a Brookfield viscosity at 20 ° C of 4200 mPas obtained.

Comparative Example 2 (according to DE 37 02 615)

The polyurethane dispersion was the same as in Example 3 Apparatus manufactured. Instead of 129.2 g, 32.3 were castor oil (OHZ = 158) used. After adding 3.3 g glycerol × 7 mol Ethylene oxide × 81 moles of propylene oxide (OHZ = 34) and heating to 60 ° C foamed the polyurethane dispersion (foam height: 14.5 cm). It became a white, stable, 39.9 wt .-% aqueous Polyurethane dispersion with a pH of 7.0 and one Brookfield viscosity at 20 ° C of 1800 mPa · s obtained.  

Examples of use

Tl means parts by weight

Base material: natural crust leather

Head coloring:
100 parts of metal complex dye solution
200 parts of polyglycol ether
200 parts of water

Spray cross once

Primer:
100 parts of pigment
30 parts wax dispersion
10 parts oil emulsion
200 parts of polyacrylate dispersion
300 parts of water

Spray cross twice
iron at 80 ° C / 100 bar
Spray cross once

Graduation:
100 parts of the polyurethane dispersion according to the invention (see table)
100 parts of water

Spray cross twice

The wet rub fastness of the finished leather was according to Veslic Right.  

Evaluation scale of the wet rub fastness: grade 5 = no abrasion, grade 4 = low abrasion, grade 3 = significant abrasion, grade 2 = strong abrasion rubbed, grade 1 = very strong abrasion.

Table 1

Claims (4)

1. Use of an aqueous polyurethane dispersion having a solids content of between 10 and 50% by weight and a Brookfield viscosity at 20 ° C. of between 10 and 5000 mP.s, the polyurethane solids, based on 100 parts by weight of di- and / or polyisocyanates, 61 contains up to 450 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C _1-8 alkyl alcohols in the leather finishing. 2. Use according to claim 1, characterized in that a polyurethane dispersion whose polyurethane solids, based on 100 parts by weight of di- and / or polyisocyanates, contains 80 to 200 parts by weight of castor oil and / or epoxidized fatty acid esters opened with C _1-8 alkyl alcohols, is used. 3. Use according to one or both of claims 1 to 2, characterized in that the polyurethane dispersion to be used contains castor oil and / or epoxidized fatty acid mono-, di- and / or triglycerides ring-opened with C _1-8 alkyl alcohols. 4. Use according to claim 3, characterized in that with C _-8 alkyl alcohols ring-opened epoxidized fatty acid mono-, di- and / or triglycerides with methanol ring-opened soybean oil, linseed oil, tall oil, cottonseed oil, peanut oil, palm oil -, Sunflower oil, rape oil and / or claw oil epoxy.