DE2041550A1 - Process for treating flat structures with anionic aqueous polyurethane dispersions - Google Patents

Description

FARBENFABRIKEN BAYER AG

LE VERKU S EN · Bayerwerk patent department

2 AUG. 1970

Process for treating flat structures with anionic aqueous polyurethane dispersions

A coating or finish of fabrics such as In addition to aesthetic properties, leather or synthetic leather must also have good resistance to friction and resistance against repeated folding and kinking. The union of the last two properties mentioned in one Finish or a coating is not easy as the two properties are contrary. Especially with aqueous Coating systems have not yet achieved this satisfactorily.

It has been found, surprisingly, that coatings that are extremely resistant to kinking and rubbing are obtained if leather and Artificial leather by customary methods with mixtures of aqueous anionic polyurethane dispersions, hardening agents Based on aqueous solutions of melamine methylol compounds with at least an average of 3 methylol groups, those with lower Monohydric aliphatic alcohols can be etherified and coated with acids or acidic compounds or finished, the ratio of polyurethane to curing agent in the mixture being 100: 15 to 100: 100, preferably 100: 20 to 100 ί 60 parts by weight, based on dry substance.

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The present invention thus relates to a method for coating or pinishing flat structures, in particular Leather and artificial leather, using conventional methods with a combination of dispersions of synthetic polymer substances and hardening agents, characterized in that the polymer dispersions are aqueous dispersions of anionic polyurethanes or their graft copolymers with copolymerizable monomers and as hardeners, aqueous solutions of melamine methylol compounds with an average of at least three, optionally Methylol groups etherified with lower monohydric aliphatic alcohols together with acidic ones Compounds are used and that the ratio of polyurethane to melamine methylol compound in the mixture 100: 15 to 100: 100 parts by weight, based on dry substances.

The polyurethane dispersions suitable for the process according to the invention are made in a manner known per se from high molecular weight compounds with reactive hydrogen atoms with a molecular weight of 300 - 20,000, polyisocyanates and any chain extenders to be used produced with reactive hydrogen atoms available polyurethanes.

As compounds with reactive hydrogen atoms with a molecular weight of 300 - 20,000, polyisocyanates and Any chain extenders with reactive hydrogen atoms which may be used at the same time are all known and commonly used components. Examples are in Belgian patents 653 223, 669 954 and 673 432 and in the German Auslegeschrift 1 067 678. The proportions used can be known per se Way within wide limits, depending on whether soft, flexible or elastic or very hard and thermoplastics are produced aollen.

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Examples of the production of aqueous polyurethane dispersions can be found in the German Auslegeschrifts 1 097 678, 1 187 012, 1 184-946, 1 178 786, 1 179 363, in the Belgian Patents 653 223, 658 026, 669 954, 673 432 and 688 299, in English patent 883 568, in French Patent 1 108 785 and in the American patent 3 178 310 and in German Offenlegungsschrift 1 939 911.

Constructed dispersions are particularly suitable emulsifier for the inventive method, in particular emulsifier-free dispersions of anionic polyurethanes with 0.1 - 3.0 being preferred Oj5 - 2 _t 0 percent by weight of sulphonate and / or '

Carboxylate groups are preferred.

In the preparation of dispersions of polyurethanes with anionic groups, a pre-adduct containing isocyanate groups is generally reacted with the anionic component, preferably in organic solution, water is added and, if appropriate, the organic solvent is distilled off. However, the procedure can also be reversed by initially introducing water containing the anionic component and introducing the pre-adduct containing isocyanate groups. Are suitable for installation suitable anionic components, for example the alkali metal salts of amino acids such as taurine, methyl taurine, like 6-aminocaproic acid, glycine, sulfanilic acid, diamino benzoic acid, ornithine, lysine, 1: 1 adducts of sultones, such as propane sultone or butane sultone to diamines such as ethylene diamine, hydrazine, or 1, 6-hexamethylenediamine.

In general, the dispersions are adjusted to a solids content of 20-60% by weight, preferably 30-50% by weight.

The polyurethane dispersions are stable, can be stored and shipped. In the process according to the invention, you can use poly

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merisate dispersions and copolymer dispersions based on of vinyl acetate, butadiene, styrene, acrylonitrile, acrylic esters and methacrylic esters, vinyl chloride, vinylidene chloride and others polymerizable and copolymerizable monomers blended or preferably modified by graft polymerisation with polymerisable monomers, with further diluents, Fillers, crosslinking agents and other additives mixed and processed in the usual known manner to give shape.

A graft copolymer dispersion is prepared in such a way that the aqueous dispersion of an anionic one Polyurethane, optionally with the addition of a suitable one Emulsifier, with a radical polymerizable vinyl monomer or a monomer mixture and triggers the polymerization under the usual conditions. It is there possible both to add the entire amount of vinyl monomer at once as well as to submit only a part and the rest to be added in the course of the reaction. The properties can be determined by selecting suitable monomers or monomer combinations of the polyurethane serving as the graft substrate vary in any way.

In principle, all free-radically polymerizable vinyl monomers can be used as vinyl monomers Mono- and polyvinyl compounds into consideration. Examples of such connections are:

1) Esters of β-unsaturated carboxylic acids, e.g. B. methyl methacrylate, Ethyl acrylate, butyl acrylate, stearyl methacrylate, Hydroxypropyl acrylate, methoxymethyl methacrylate, esters of Maleic acid, fumaric acid, itaconic acid, etc.

2) ctjβ-unsaturated carboxylic acids, e.g. B. acrylic acid, methacrylic acid, Maleic acid;

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• cc, ß-unsaturated carboxylic acids, ζ. B. acrylamide, icrylamide, maleic acid amide, maleic acid imide;

substituted amides of unsaturated carboxylic acids, e.g. B. methylol methacrylamide, methoxymethylacrylamide; ·

5) Nitriles Oc., Ss-unsaturated carboxylic acids, e.g. B. Acrylonitrile, Methacrylonitrile;

6) vinyl esters, e.g. B. vinyl acetate, vinyl chloroacetate, vinyl chloride;

7) vinyl ethers, e.g. B. vinyl ethyl ether;

8) vinyl ketones, e.g. B. vinyl methyl ketone;

9) vinyl alloys, e.g. B. vinylformamide, vinylacetamide;

10) vinyl aromatics, e.g. B. styrene, vinyl toluene;

11) vinyl heterocycles, e.g. Vinyl pyridine, vinyl pyrrolidone;

12) vinylidene compounds, e.g. B. vinylidene chloride ι

13) Di vinyl compounds, ζ. B. divinylbenzene, butanediol dimethacryD.at; ·

14) Monoolefj.ne, e.g. B. Xethylene, propylene;

15) conjugated diolefins, e.g. B. butadiene, isoprene, 2-chlorobutadiene;

16) allyl compounds, e.g. B. allyl acetate, allyl alcohol.

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As polymerization catalysts come anorgai'ische per-compounds, such as potassium or Amm on iump he _f sulfate, hydrogen peroxide, percarbonates, organic Peroxidv "; turns, such as acyl peroxides such as benzoyl peroxide, alkyl hydroperoxides such as tert-butyl hydroperoxide, Cumolhydrt.psroxid, p-methane hydroperoxide, Dialkyl peroxides, such as di-tert-butyl peroxide, peroxyesters, such as perbenzoic acid-tert-biityl ester, are suitable. The inorganic or organic per-compounds are advantageously used in combination with reducing agents in a known manner. Suitable reducing agents are, for example, sodium pyrosulfite or bisulfite, sodium formaldehyde sulfoxylate, triethanolamine, tetraethylene pentamine.

The amount of catalyst to be considered is within what is customary for polymerizations of this type in imprint coming borders, d. H. between 0.01 and 5 percent by weight, based on the total amount of monomers.

To influence the molecular weights, the usual regulators, such as long-chain alkyl mercaptans, diisopropyl ranthogenate, Nitro compounds or organic halogen compounds, are used in the polymerization.

The polymerization temperatures depend on those used Monomer types and the activation systems and are between 0 and 150 ° C, preferably between 30 and 100 ° C.

Both anionic and nonionic or combinations of these emulsifiers can be used as emulsifiers.

Suitable anionic emulsifiers are higher fatty acids, resin acids, acidic fatty alcoholsulfuric acid esters, and higher Alkyl sulfonates and alkyl aryl sulfonates, sulfonated castor oil, Sulfonic acid esters or the water-soluble salts of sulfonated ethylene oxide adducts can be used.

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The known reaction products of ethylene oxide with long-chain fatty alcohols or are used as nonionic emulsifiers Phenols are suitable, in particular reaction products of more than 10 moles of ethylene oxide with 1 mole of fatty alcohol or phenol come into use.

The total amount of the abovementioned emulsifiers can be up to 20 percent by weight, based on the total amount of monomers. It is preferably between 2 and 10 percent by weight.

In addition to the above emulsifiers, known protective colloids, such as polyvinyl alcohol, can also be used at any point in time and polyvinylpyrrolidone, polyacrylamides or water-soluble copolymers with a predominant acrylamide content, polyacrylic acid Salts, condensation products of formaldehyde with naphthalenesulfonic acids, casein, tragacanth, alginic acids, methoxy or carbonyl cellulose or inorganic compounds such as magnesium hydroxide, finely divided barium sulfate or highly disperse silica are used.

The anionic polyurethanes and the monomers to be polymerized can be used in any desired form in the reaction mixture Mixing ratios must be available. Preferably 5-95 wt .- # of anionic polyurethanes to 95-5 wt .- # of Monomers used. The polyurethanes are used in the form of their aqueous dispersions and generally have Solids contents of 5-60 wt .- #.

The emulsion polymerization can also be carried out without emulsifiers are, the anionic polyurethane as; Emulsifier and serves as a graft base. In this case it will be preferably at least 20% by weight of the anionic polyurethane and up to 80% by weight of polymerizable monomers used.

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The hardening agents are tri-, tetra-, penta- or hexamethylol compounds of melamine, obtainable by customary methods, or mixtures thereof, which can be etherified with 3 or more, preferably on average 3 or 6, mol of a lower, monohydric aliphatic alcohol. Suitable alcohols are, for. B. called ethanol or especially methanol. Polynuclear melamine-formaldehyde condensates, such as. B. methylol compounds of methylenebismelamine and its ethers can be used.

The curing agents are added to the polyurethane dispersion before processing. The amount is 15-100, preferably 20 - 60 parts, based on 100 parts of solid polyurethane, always calculated as parts by weight and on dry matter. the aqueous solutions of the hardening agents are mostly 30 - 50 #, but can also have a higher concentration or, if necessary, before mixing with the polyurethane dispersion be diluted. The pH values of the hardener solutions are usually between 5-7. If there is an intolerance is observed with the polyurethane latex, this can be done by correcting the pH z. B. in the boundaries between 5 and 12 can be corrected. It is sometimes desirable to finish leather or synthetic leather with a softer finish first To provide base layer, the z. B. contains 20-30 parts of hardener per 100 parts of polyurethane, and then with a finish, the z. B. contains 40-60 parts hardener.

In order to accelerate the curing of the coating, acids or acidic compounds are added to the polyurethane-curing agent mixture to add. For example, hydrochloric acid, sulfuric acid, phosphoric acid, tartaric acid, oxalic acid, Citric acid, lactic acid, salicylic acid and especially maleic acid, ammonium chloride or diammonophosphate called. The amounts of the additives can be within wide limits

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vary. Usually -0.5 - 10 9 », with strong acids less, in the case of very weak acids or weakly acidic salts more, preferably 2 - 8 #, based on dry substances, polyurethane used. ,,

The coating mixtures containing water, polyurethane dispersion, curing agent solution and acid catalyst can also contain pigments, dyes, stabilizers, other polymer dispersions, hardening agents, emulsifiers, light stabilizers, matting agents and fillers, oils, waxes, dispersions of organic liquids, ζ α B. gasoline, and gloss agents, and preferably contain ammonia, so that a pH value of i is 5-10, preferably 6-8 in the final aqueous mixture. This is beneficial to the pot life of the mixture, which can be increased from a few hours to over 20 hours. When the finish dries later, the ammonia evaporates and the acidic catalysts take effect. This is particularly the case when using ammonium chloride as a catalyst. The pesticide content of the mixtures can fluctuate within wide limits, depending on the application technique, but it will mostly be in the limits of 10 - 40 ^ solids content, advantageously between 15 - 25 ^.

The mixture is applied by customary methods, such as. B. Spraying on, pouring on, printing on, ruffling "

or combinations of application methods. In the interests of good water vapor permeability, spraying is used and printing by means of a rasterized applicator is preferred. The order quantities are z. B. 1. - 50 g, preferably 10-30g solids / m surface.

After the application is dried and pickled »read outs occurs faster, the higher the temperature selected However, it must be below the softening temperature ! Finishes and the ■ substrate lie »in general will

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Bake out temperatures between 80 and 160 ° C can be selected, usually between 90 and 120 ° C. The duration is then ζ. B. between 30 and 6 minutes. The hardening continues even after baking, so that the top layer after 1 - 10 Days reached the final property profile. The baking rate can be increased or the baking temperature can be increased can be decreased by increasing the amount of catalyst.

The mixtures described are particularly suitable for pinishing artificial leathers, for. B. with a microporous top layer, by known processes such as the coagulation or evaporation process from polyurethane or polyvinyl compounds or combinations of these products, e.g. B. according to Belgian patents 692 116 and 700 304.

After drying or baking, the pine trees can be ironed, pressed or calendered to vary the surface or be embossed. The surface to be finished is advantageously embossed before finishing.

example 1

212 g of adipic acid-1,6-hexanediol-neopentyl glycol polyester are dehydrated at 120 ° C. for 30 minutes in a water jet vacuum and then reacted with 38 g of 1,6-hexanediisocyanate for 2 hours. After cooling, the melt is taken up in 700 ml of acetone and a solution of 50 g of water, 3.75 g of ethylenediamine, 7.6 g of 1,3-propane sultone and 35 g of 10% aqueous potassium hydroxide solution are added. After a short reaction time, 310 ml of water are quickly stirred and the acetone Waeser "vacuum distillation. The 40 # dispersion obtained can be used directly for the process according to the invention. There were 350 g of water with 50 g of 20 # ammonium chloride

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Solution mixed therein 20 g of 25 dissolved i "ammonia and 130 g of a 45 5» aqueous solution of Trimethylolmelamintrimethyläthers, then 150 g of a commercially available about 35 follow soot _r casein color paste mixed and finally 300 of the above-described 40 g #igen anionic polyurethane dispersion added. The mixture showed a pH of approx. 9f which decreased to 8 within 5 minutes. From this mixture, first 3 fine crosses and then 1 wet crossover were sprayed onto a microporous polyurethane synthetic leather, whereby a uniform coverage was achieved. It was then dried in flowing air at 90 ° C. for 15 minutes and ironed. After 3 days, the smooth, shiny j | Finish a water vapor permeable

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ability of 2 mg / cm -h (measured according to IUP 15 _f cf. "Das Leder", 1961, 86-88), a buckling strength of over 200,000 folds (measured by means of a flexometer, see IUP 20 "Das Leder", 1964, 87-88) and good dry and wet rub resistance (measured according to SATRA, see J. Soc. Leather Trades Ohem. (1957), 120-125). If the ammonium chloride is omitted, very poor rub fastness is obtained. Without the addition of a hardener, the result is a finish that is insufficiently kink and rubbing fastness. If equivalent amounts of formaldehyde or paraformaldehyde are used in place of the melamine derivative mentioned, inadequate rub fastness and, in the case of formaldehyde, also inadequate kink fastness. "

Example 2

250 g of a 1,6-hexanediol phthalic acid polyester (MW 2000) are reacted after dehydration at 120 ° C and 30 Torr (2 hours) with 38 g of 1,6-hexane diisocyanate. The melt is taken up with 700 ml of acetone and with a reaction mixture of 50 ml of water, 7 »25 g of hexamethylenediamine, 8.5 g Butaneulton and 25 g of 10 # aqueous sodium hydroxide solution were added. After brief stirring, 300 g of water are added and

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the acetone is distilled off in a water jet pump vacuum at 50 ° C. The liquid dispersion obtained is 48%, residual acetone content 0.4% ,

360 g of water are mixed with 5 g of maleic acid, 155 g of a 45% strength aqueous solution of trimethylolmelamine trimethyl ether, 200 g of a commercially available brown pigment-casein color paste and 280 g the above dispersion mixed. As described in Example 1, this mixture is used to produce a microporous polyurethane leatherette finished. After baking (10 min. At 110), it was embossed and tested after 3 days. There were similar ones Properties as found in Example 1, the water vapor permeability was 1 mg / cm »h.

Example 3

From 250 g of the 1,2-propylene glycol adipic acid polyester (MG 2000) and 46 g of 1,6-hexane diisocyanate is at 120 ° C a prepolymer produced. After cooling to 60 ° C, the melt is taken up with 800 ml of acetone and then with a reaction mixture of 50 ml of water, 3.8 g of ethylenediamine, 7.6 g of propane sultone and 25 g of 10 9 »strength aqueous sodium hydroxide solution offset. After 5 minutes, 300 ml of water are stirred in. The acetone is then distilled off at 50 ° C. in a water jet pump vacuum. The dispersion obtained is largely free of acetone and approx. 44

Ee is made using the dispersions described above a Finieh mixture prepared according to Example 2 and on a Microporous polyurethane synthetic leather sprayed on and baked. If the wet rub fastness is slightly worse, an otherwise achieved similar result.

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Example 4

The mixture of Example 1 is prepared, with the difference that a white pigment is added and the ammonia is omitted and a corresponding amount of a commercially available hexamethylolmelamine solution (50%) is used in place of the trimethylolmelamine trimethyl ether. After spraying the mixture to a microporous polyurethane artificial leather and cure for 20 minutes, "at 10O ⁰ C one obtains a similar finish with excellent light fastness. Example 5 *

In a stirred autoclave with 6 1 contents were 1600 g of an anionic polyurethane dispersion with a Peststoffgehalt of $ 40> according mixed with 1300 ml of water Example. 1 After adding 1 g of n-dodecyl mercaptan, 15 g of a polyglycol ether of 3-benzyl-4-hydroxybiphenyl and 25 g of the sodium salt of a long-chain alkyl sulfonic acid, the autoclave was made air-free by evacuating and filling up with nitrogen several times and heated to 40.degree. Then 200 g of butadiene, the solution of 1 g of sodium pyrosulfite in 50 ml of water and the solution of 3 g of potassium persulfate in 100 ml of water were pumped in with the exclusion of air. After the polymerization had ,, the revealed himself in one! Temperature rise, I further 760 g of butadiene was pumped in over the course of 3 hours and then stirred to a Peatatoffgehalt 38.5 $>. A coagulate-free white dispersion was drained to which β g of 2,2-methylene-bis- (4-ethyl-5-cyclohexylphenol) were added as an antioxidant and freed from residual monomers by stirring in air.

415 g of this dispersion are mixed with a solution of 370 g water, 5 g maleic acid _f 110 g 45% strength irimethylolmelamine triraethyl ether .und. 100 g of a commercially available, aqueous, nonionic, emulsifier containing light brown pigment

paste mixed. Then a microporous polyurethane synthetic leather Finished and hardened according to Example 1. It became a smooth finish with a soapy feel and poor lightfastness than in the examples described above, but otherwise similar properties are obtained.

Example 6

The following mixture was polymerized in the manner described in Example 5:

Polyurethane dispersion according to Example 1 1,600 g

Water 1,300 g

n-dodecyl mercaptan 1 g

Polyglycol ether of 3-benzyl-4-hydroxy-biphenyl 15 g

Sodium salt of a long-chain alkyl sulfonic acid 25 g

Butadiene 750 g

Acrylonitrile 250 g

Sodium pyrosulfite dissolved in 50 ml of water 1 g

Potassium persulfate dissolved in 100 ml of water 3 g

The polymerization was started with 200 g of the monomer mixture and the remaining 800 g were pumped in over the course of 3 hours. After 8 hours, a coagulum-free dispersion was formed with a Peststoffgehalt of 41.1 $>, the g for stabilizing with added 6 referred to in Example 5 antioxidant and was degassed by stirring.

With 340 g of the dispersion obtained, a mixture with 450 g of water, 5 g of maleic acid, 155 g of 45% trimethylolmelamine trimethyl ether was prepared and 50 g of a commercially available aqueous

Brown pigment dispersion (approx. 40 #ig) produced and a full-grain chrome leather finished in the manner described in Example 1 and baked at 80 ° C. for 30 minutes. After leaving

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ironing became a smooth finish, good crease and rub fastness, but obtained only moderate lightfastness.

Example 7 ''

In the manner described in Example 5, the following mixture was made polymerized:

Polyurethane dispersion according to Example 1, 2,400 g

Water 810 g

n-dodecyl mercaptan 2 g j

Polyglycol ether of 3-benzyl-4-hydroxy-biphenyl 8 g

Sodium salt of a long chain alkyl sulfonic acid 16 g

Butadiene 640 g

Sodium pyrosulfite, dissolved in 50 ml of water 1g

Potassium persulfate, dissolved in 100 ml of water 2g

Again the polymerization was initiated with 140 g of butadiene and the residual butadiene was pumped in within 3 hours * Then was polymerized to a Peststoff salary of 42 $>. The total duration of the polymerization was 10 hours. After draining, the resulting dispersion was degassed and mixed with 10 g of the above-mentioned antioxidant. The product was free from coagulum. f

A mixture was prepared according to Example 6 and accordingly applied. The result was comparable.

In all examples 1-7, omission of the melamine derivative is obtained and / or the catalyst has very poor rub fastnesses and usually also poor buckling strengths, d. H. extensive destruction of the finish under the test conditions,

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Claims (1)

Patent entitlement Process for coating or finishing flat structures, in particular leather and artificial leather, by customary processes with a combination of dispersions of synthetic polymeric substances and curing agents, characterized in that the polymer dispersions are aqueous dispersions of anionic polyurethanes or their graft copolymers with copolymerizable monomers and, as curing agents, aqueous solutions of melamine methylol compounds with average of at least three optionally tables with lower monohydric alipha ~ W alcohols etherified methylol groups are used together with acidic compounds, and that the ratio of polyurethane to Melaminmethylolverbindung in the mixture of 100: 15 to 100: 100 parts by weight, based on dry substances is. Le A 13 245 - 16 - 209809/1639