DE4002418A1 - Dressing for improving feel of leather - Google Patents

Abstract

A dressing agent for leather contains polyurethanes with alkoxysilane terminal gps., prepd. in several stages by (A) reaction of aliphatic and/or aromatic di- and/or tri-isocyanates with polyethylene glycols with Mn 500-6000, in equiv. ratio of OH:NCO of 1:1.5-2, (B) reaction of the prod. with hydrophobic di- and/or poly-ols, in equiv. ratio of OH:NCO still present of 1:1.1-10, and (C) reaction of the prod. with alkoxysilanes of formula X -(CH2)q-Si(Rn)-(OR1)3-n (I), to 0 wt.% NCO content. R, R1 = 1-4C alkyl; X = amino or mercapto; n = 0 or 1; q = 2-4.

Description

The invention relates to gripping agents for leather which terminated alkoxysilane groups Contain polyurethanes, as well as the use of alkoxysilane group-terminated polyurethanes as grip agents in the 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 to 163, Verlag Chemie Weinheim, 1978). The preparation film must adhere firmly to the leather and have extremely high bending and stretching requirements during further processing and during the later use will suffice. 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 dressing fleets, especially the primer  and final liquors, with respective intermediate drying and if necessary Intermediate temples or embossing applied.

Due to the film-forming polymers used in leather finishing, such as copolymers containing acrylate or butadiene, Nitrocellulose lacquers or polyurethanes, the handle is opposite the untreated leathers changed in an undesirable manner. In Dependence on the layer thickness and the type of polymer used becomes a more or less pronounced plastic-like, preserved unnatural grip. It is known through Use of grip agents in the finish (top coat) or in non-trimmed or trimmed leather applied handle whispers to correct the grip properties of finished leather. Fats, oils, natural are usually used as grip agents and / or synthetic waxes, paraffins, silicone compounds and / or metal soaps used in the form of solutions or dispersions ("Library of Leather" Volume 6, pages 138 to 139, review Verlag, Frankfurt am Main 1982). However, these grip means have the disadvantage that the grip improvement by abrasion and / or Migration of the handle means from the surface to the dressing or is lost in the leather in a relatively short time.

The object underlying the invention was therefore in Development of gripping aids through the individual treatment steps deterioration caused by the dressing Remove grip properties of leather. The one with the ones to be developed Grip means to improve the grip properties get very close to the natural leather handle and be permanent, d. H. not within a short time due to abrasion or migration of the handle get lost in the dressing or in the leather. Furthermore the physical fastness properties, for example fastness to rubbing,  as well as the flexibility of the preparation not adversely affected will.

It has now been found that the high on the handle means Requirements of polyurethanes terminated with alkoxysilane groups met will.

The invention accordingly relates to grip means for leather, containing polyurethanes terminated with alkoxysilane groups in several stages

• A. Implementation of aliphatic and / or aromatic di- and / or triisocyanates with polyethylene glycols with number averages the molecular weights between 500 and 6000, the OH / NCO equivalent ratio is between 1: 1.5 and 1: 2,
• B. Reaction of the reaction products obtained in stage A with hydrophobic Di- and / or polyols, the equivalent ratio the OH groups of the diols and / or polyols to those still present NCO groups is between 1: 1.1 and 1:10 and
• C. Reaction of the reaction products obtained in stage B with alkoxysilanes of the general formula I in which R and R¹ are identical or different and are a C _1-4 alkyl radical and X is an amino or mercapto group, n is 0 or 1 and q is an integer between 2 and 4, up to an NCO content of 0 % By weight.

Another object of the invention is the use of these in several Steps produced alkoxysilane group-terminated polyurethanes as a grip in leather finishing.

The synthesis of the polyurethanes terminated by alkoxysilane groups takes place gradually in the order given. After reaching the theoretical content of -N = C = O groups (abbreviated: theoretical NCO content) of the respective stage, the reaction mixture reacted with the next stage reagent. The term "Theoretical NCO content" means that all OH groups with -N = C = O groups (abbreviated: NCO groups) have reacted and thus in Reaction product no free OH groups are present.

The polyurethanes terminated by alkoxysilane groups according to the invention are manufactured in a manner known per se (Ullmanns Encyclopedia der technical chemistry, volume 19, pages 302-310, publisher Chemistry 1980). Polyethylene glycols with number average molecular weights between 500 and 6000, if desired in a mixture with trimethylolpropane and / or dimethylolcarboxylic acids with 1 to 6 C atoms are present without solvent, optionally in Presence of catalysts, for example dibutyltin dilaurate, with di- and / or triisocyanates at temperatures between 60 and 100 ° C implemented. This is related to the polyol components OH / NCO equivalent ratio between 1: 1.5 and 1: 2, preferably between 1: 1.8 and 1: 2. After reaching the theoretical NCO contents are between the reaction mixture at temperatures 60 and 100 ° C hydrophobic di- and / or polyols added, the Equivalent ratio of the OH groups of the hydrophobic di- and / or Polyols to the remaining NCO groups between 1: 1.1 and 1:10, preferably between 1: 1.3 and 1: 1.5. After reaching of the theoretical NCO content are general alkoxysilanes Formula I added at temperatures between 50 and 70 ° C.  

Based on the remaining NCO equivalents, alkoxy aminoalkyl and / or alkoxy-mercaptoalkylsilanes in equimolar Amounts used. After all remaining NCO groups with the alkoxysilanes have reacted, the reaction is complete. The The alkoxysilane-terminated polyurethanes obtained are in the Room temperature, d. H. wax-like at temperatures between 15 and 25 ° C firm and have a white color.

For the production of polyurethanes terminated by alkoxysilane groups the aliphatic known from polyurethane chemistry are suitable and / or aromatic, cyclic and / or noncyclic di- and / or triisocyanates, for example dicyclohexylmethane-4,4'- diisocyanate, 1,6-hexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (Isophorone diisocyanate), tetramethylene diisocyanates, Trimethylhexamethylene diisocyanate, 1,4-phenylene diisocyanate, Diphenylmethane diisocyanates, toluene-2,4- and / or toluene- 2,6-diisocyanate, 2,4,4'-triisocyanatodiphenyl ether and / or 4 ′, 4 ′ ′ -, 4 ′ ′ ′ - triisocyanato-triphenylmethane. Preferably be aliphatic diisocyanates and particularly preferably trimethylhexamethylene diisocyanates used.

The reactions of diisocyanates are preferably carried out with mixtures from polyethylene glycols with number average molecular weights between 500 and 6000, trimethylolpropane and optionally aliphatic dimethylol carboxylic acids with 1 to 6 carbon atoms, especially preferably with mixtures of polyethylene glycols with number averages the molecular weights between 500 and 2500, trimethylolpropane and optionally aliphatic dimethylol carboxylic acids carried out with 1 to 6 carbon atoms. Triisocyanates are preferably with polyethylene glycols with number average molecular weights between 500 and 6000, possibly in combination with aliphatic dimethylolcarboxylic acids with 1 to 6 carbon atoms,  particularly preferred with polyethylene glycols with number average Molecular weights between 500 and 2500, if desired in combination with aliphatic dimethylol carboxylic acids with 1 to 6 C- Atoms implemented. These reactions can be carried out in the presence of catalysts, for example tertiary amines, dibutyltin dilaurate and / or dibutyltin diacetate. In trimethylolpropane containing Polyethylene glycol blends the trimethylol propane content chosen so that on a polyethylene glycol OH equivalent not more than 0.33 trimethylolpropane OH equivalents come. In polyethylene glycol containing dimethylolcarboxylic acid Mixtures is a maximum of one polyethylene glycol OH equivalent Dimethylol carboxylic acid OH equivalent used. Aliphatic Dimethylolcarboxylic acids with 1 to 6 carbon atoms, for example Dimethylolacetic acid, dimethylolpropionic acid and / or dimethylolvaleric acid can be used together with polyethylene glycols or with mixtures made of polyethylene glycols and trimethylolpropane will. However, it is also possible to use aliphatic dimethylol carboxylic acids only then add to the reaction mixture after all OH groups of the polyethylene glycols and optionally of trimethylolpropane have reacted with the NCO groups. The OH / NCO equivalent ratio, d. H. the equivalent ratio of the OH groups of Polyethylene glycols, optionally trimethylolpropane and optionally Dimethylolcarboxylic acids to the NCO groups is, as already given above, between 1: 1.5 and 1: 2, preferably between 1: 1.8 and 1: 2.

The preferred hydrophobic di- and / or polyols are polytetrahydrofurans with number average molecular weights between 400 and 2000, C _12-18 fatty acid diethanolamides, monoglycerides of aliphatic C _8-22 fatty acids and / or polysiloxanes of the general formula II

where the index x means a number between 5 and 15. Polytetrahydrofurans with number average molecular weights between 400 and 2000 are particularly preferred.

Polytetrahydrofurans are commercial products and are e.g. B. offered by BASF. C _12-18 fatty acid diethanolamides which can be prepared by reacting C _12-18 fatty acids, such as lauric acid, myristic acid, coconut fatty acid and / or oleic acid, with diethanolamine (Kirk-Othmer: "Encyclopedia of Chemical Technology", volume 22, pages 373-376 , John Wiley & Sons, New York 1983) and monoglycerides of C _8-22 fatty acids, which can be prepared by reacting fats and / or oils with glycerol, for example lauric acid, coconut fatty acid, stearic acid, oleic acid and / or tallow fatty acid monoglyceride (Kirk - Othmer: "Encyclopedia of Chemical Technology", volume 22, pages 367-368, John Wiley & Sons, New York 1983) are commercially available products. Polysiloxanes of the general formula II are offered, for example, by Wacker.

Suitable for the production of polyurethanes terminated by alkoxysilane groups are preferably alkoxysilanes of the general formula I, in which the R and R¹ are the same or different and methyl or ethyl and X represents an amino group and n represents 0 or 1 and q represents two or three is, for example aminopropyltriethoxysilane and / or aminopropyltrimethoxysilane. Alkoxysilanes are commercial products and are, for example  distributed by Dynamit Nobel under the name Dynasilan.

The polyurethanes according to the invention are in the form of aqueous dispersions used. To produce these dispersions, the alkoxysilane group-terminated polyurethanes at temperatures between 60 and 100 ° C melted and then either in aqueous alkaline solutions with temperatures between 5 and 60 ° C stirred in or with aqueous alkaline solutions at temperatures between 5 and 60 ° C. The viscosity of the melted Polyurethanes should be conveniently at the melting temperature do not exceed a value of 50,000 mPa · s. As an aqueous alkaline Solutions are preferably sodium hydroxide solution or potassium hydroxide solution used. The polyurethane content is in the aqueous obtained Dispersions between 5 and 30 wt .-%, preferably between 10 and 20% by weight. The dispersions have a pH of 10.

It may be advantageous to use the aqueous, polyurethane-containing dispersions together with known gripping agents such as greases, oils, natural and / or synthetic waxes, paraffins, silicone compounds and / or metal soaps. To this end the aqueous, polyurethane-containing dispersions with the known Grip means preferably before using them together mixed. The weight ratio of alkoxysilane groups was terminated Polyurethanes to known grip means is preferably between 100: 1 and 20:80, particularly preferably between 100: 1 and 40:60. The grip means according to the invention can be used together with polymer compounds, e.g. B. polyacrylates, polyurethanes, caseins and / or Cellulose esters, pigments, matting agents, fillers and / or organic solvents can be applied. The invention Handle means can be used as a handle finish directly the undressed leather as well as in the finishing, d. H. in primer  and final fleets as well as handle whispers.

The application of the grip means according to the invention can be done with all technologies customary in leather finishing, for example by Spraying, plushing, pouring and / or roller application. The aqueous treatment liquors or dispersions contain per liter preferably 2 to 300 g, particularly preferably 2 to 200 g, of alkoxysilane groups Polyurethanes.

The leather treated with the grip means according to the invention are characterized by good, permanent grip properties that the are similar to natural leather handles. Compared to known ones Grip means with the inventive grip means Fastnesses of the dressing, for example fastness to rubbing, as well as the Flexibility of the leather is not negatively affected. Also effect the grip means according to the invention in particular with primed leathers a reduction in the ironing and stacking of the dressing.

Examples Example 1 Production of the alkoxysilane group-terminated Polyurethane I

72 g of 1550 polywax (polyethylene glycol, number average molecular weight: 1600, manufacturer: Chemische Werke Hüls) with one Water content of 0.06% by weight, 0.45 g trimethylolpropane and 0.02 g Benzoyl chloride was placed in a three-necked flask in a nitrogen atmosphere mixed. After adding 21 g of trimethylhexamethylene diisocyanate was heated to 60 ° C. After an hour the theoretical NCO content of 4.5 wt .-% reached and 50 g of polytetrahydrofuran (Number average molecular weight: 2000) added. After stirring for two hours at 70 ° C, the theoretical NCO content was 1.5% by weight. Then 11.1 g of aminopropyltriethoxysilane slowly admitted. After stirring for one hour at 50 ° C the reached NCO content the value 0% by weight. After cooling to a temperature of A white, waxy solid product was obtained at 22 ° C.

Example 2 Preparation of an aqueous dispersion of the alkoxysilane group-terminated Polyurethane I

125 g of polyurethane I were melted at 85 ° C. Then were 875 g of 0.25% by weight potassium hydroxide solution at a temperature into the melt of 50 ° C within 10 minutes at 600 revolutions per Minute stirred. A homogeneous aqueous dispersion was obtained.  

Examples of use

Tl means parts by weight
CAB means cellulose acetobutyrate

A. Handle means for aniline furniture loaders

Starting material: full-grain, barrel-colored crust

Fleet:
300 parts of water
100 parts of alkoxysilane group-terminated polyurethane dispersion, prepared according to Example 2
10 parts of carbodiimide crosslinker

2 × spray, millen

B. Grip means for aqueous closure

Base material: primed upper leather

Fleet:
100 parts of an aqueous top, consisting of polyurethane / polyacrylate dispersion
40 tl. Matting agent (SiO₂ in CAB emulsion)
20 parts of alkoxysilane-terminated polyurethane dispersion, prepared according to Example 2
200 parts of water

Spray 2 ×, iron  

C. Handle and anti-adhesive in the primer

Starting material: full-grain, barrel-dyed upper leather, crust

Fleet:
50 parts of pigment
50 parts of polyurethane dispersion
150 parts of polyacrylate dispersion
30 parts. Matting agent based on a SiO₂ dispersion
30 parts of alkoxysilane group-terminated polyurethane dispersion, prepared according to Example 2
350 parts of water

1 × roller application
Spray 2 times
iron
Top coat
inject

D. Handle whisper

Base material: finished furniture leather

Fleet:
300 parts of water
30 parts of wax dispersion
70 parts of alkoxysilane group-terminated polyurethane dispersion, prepared according to Example 2

Spray 1 ×
millen

Claims (17)

1. Grip agent for leather containing alkoxysilane group-terminated polyurethanes, produced in several stages by

• A. reaction of aliphatic and / or aromatic di- and / or triisocyanates with polyethylene glycols with number average molecular weights between 500 and 6000, the OH / NCO equivalent ratio being between 1: 1.5 and 1: 2,
• B. Reaction of the reaction products obtained in stage A with hydrophobic diols and / or polyols, the equivalent ratio of the OH groups of the diols and / or polyols to the NCO groups still present being between 1: 1.1 and 1:10 and
• C. by reaction of the reaction products obtained in stage B with alkoxysilanes of the general formula I in which the radicals R and R¹ are identical or different and are a C _1-4 alkyl radical and X is an amino or mercapto group, n is 0 or 1 and q is an integer between 2 and 4, up to an NCO content of 0% by weight.

2. Handle means according to claim 1, characterized in that the Level A equivalent ratio between 1: 1.8 and 1: 2 lies.   3. Handle means according to one or both of claims 1 to 2, characterized characterized in that the equivalent ratio of stage B is between 1: 1.3 and 1: 1.5. 4. handle means according to one or more of claims 1 to 3, characterized in that these polyurethanes are manufactured by reacting aliphatic diisocyanates. 5. handle means according to one or more of claims 1 to 4, characterized in that polyethylene glycols number average Have molecular weights between 500 and 2500. 6. handle means according to one or more of claims 1 to 5, characterized in that these polyurethanes are manufactured by reacting diisocyanates with mixtures containing Polyethylene glycols, trimethylolpropane and optionally aliphatic dimethylol carboxylic acids with 1 to 6 carbon atoms. 7. Grip agent according to one or more of claims 1 to 6, characterized in that hydrophobic di- and / or polyols polytetrahydrofurans with number average molecular weights between 400 and 2000, C _12-18 fatty acid diethanolamides, monoglycerides of C _8-22 fatty acids and / or polysiloxanes of the general formula II in the index x is a number between 5 and 15, preferably polytetrahydrofuran with number average molecular weights between 400 and 2000. 8. grip means according to one or more of claims 1 to 7, characterized in that in the general formula I R and R¹ are the same or different and methyl or Ethyl and X represent an amino group and n is 0 or 1 and q 2 or 3. 9. Use of alkoxysilane group-terminated polyurethanes, produced in several stages by

• A. reaction of aliphatic and / or aromatic di- and / or triisocyanates with polyethylene glycols with number average molecular weights between 500 and 6000, the OH / NCO equivalent ratio being between 1: 1.5 and 1: 2,
• B. Reaction of the reaction products obtained in stage A with hydrophobic diols and / or polyols, the equivalent ratio of the OH groups of the diols and / or polyols to the NCO groups still present being between 1: 1.1 and 1:10 and
• C. by reaction of the reaction products obtained in stage B with alkoxysilanes of the general formula I in which the radicals R and R¹ are identical or different and are a C _1-4 alkyl radical and X is an amino or mercapto group, n is 0 or 1 and q is an integer between 2 and 4, up to an NCO content from 0% by weight

as a grip in leather finishing. 10. Use according to claim 9, characterized in that the Level A equivalent ratio between 1: 1.8 and 1: 2 lies. 11. Use according to one or both of claims 9 to 10, characterized characterized in that the equivalent ratio of stage B is between 1: 1.3 and 1: 5. 12. Use according to one or more of claims 9 to 11, characterized in that with aliphatic diisocyanates manufactured polyurethanes can be used. 13. Use according to one or more of claims 9 to 12, characterized in that with polyethylene glycols Number average molecular weights between 500 and 2500 Polyurethanes are used.   14. Use according to one or more of claims 9 to 13, characterized in that polyurethanes manufactured by Implementation of diisocyanates with mixtures of polyethylene glycols and trimethylolpropane and optionally aliphatic Dimethylolcarboxylic acids with 1 to 6 carbon atoms can be used. 15. Use according to one or more of claims 9 to 14, characterized in that polyurethane, reacted with polytetrahydrofurans with number average molecular weights between 400 and 2000, C _12-18 fatty acid diethanolamides, monoglycerides of C _8-22 fatty acids and / or polysiloxanes of the general formula II in which the index x denotes a number between 5 and 15, preferably reacted with polytetrahydrofuran with number average molecular weights between 400 and 2000, as the hydrophobic di- and / or polyol component. 16. Use according to one or more of claims 9 to 15, characterized in that polyurethanes reacted with Alkoxysilanes of the general formula I in which the radicals R and R¹ are the same or different and are methyl or ethyl and X represent an amino group and n is 0 or 1 and q is 2 or 3, be used.