MXPA00000722A - Leather coating binder and coated leather having good embossability and wet-flex endurance - Google Patents

Abstract

An aqueous leather coating composition and a method for coating leather with the aqueous coating composition are provided. The aqueous coating composition contains an aqueous emulsion polymer which includes from 0.4%to 10%by weight of a copolymerized acetoacetate or acetoacetamide monomer and has a glass transition temperature from -20ºC to 10ºC. In an alternative embodiment the aqueous coating composition contains an aqueous emulsion polymer which includes from 0.1%to 6%by weight of a copolymerized acetoacetate or acetoacetamide monomer and from 2%to 15%by weight of copolymerized carboxylic acid monomer and has a glass transition temperature from -40ºC to 0ºC, the polymer having been contacted with a transition metal oxide, hydroxide, orcarbonate at a pH less than 9 in an amount greater than 0.20 equivalent of transition metal per equivalent of copolymerized carboxylic acid monomer.

Description

AGLUTINANT FOR COVERING LEATHER AND LEATHER COVERED WITH GOOD GOOD AND RESISTANCE TO THE HUMID FLEXION.

The present invention relates to an aqueous composition suitable for use in leather coating and a method for coating leather with an aqueous coating composition to provide coated leather with good embossing and wet bending resistance. More particularly, the present invention relates to an aqueous composition that includes an emulsion polymer that includes from 0.4% to 10% by weight of copolymerized acetoacetate or acetoacetamide monomer based on the weight of the polymer and at a state transition temperature. vitreous (Tg) from -20 ° C to 10 ° C. More particularly, in a second embodiment, the present invention relates to an aqueous composition that includes an emulsion polymer that includes from 0.1% to 6% by weight of copolymerized acetoacetate or acetoacetamide monomer based on the weight of the polymer and from 2% to 15% by weight of copolymerized carboxylic acid monomer based on the weight of the polymer and with a glass transition temperature (Tg) of -20 ° C to 10 ° C after the polymer has been contacted with a transition metal oxide, hydroxide or carbonate at a pH of less than 9 in an amount greater than 0.20 equivalent to the transition metal per equivalent of carboxylic acid monomer copolymerized in the polymer.

The present invention serves to provide an aqueous composition suitable for use in leather coating, particularly a basic coating, which is aesthetically pleasing and protective, and a method for coating leather. The protective properties of the leather coating can be measured by the flexural strength of the coated leather, particularly in wet conditions. The coating can then be embossed for decorative purposes with a desired printing in a hot press. The smoothness of the final leather coating, the ability of the coating to be easily goffered without adhering to the hot press and the retention of the desired print are measured aesthetic properties of the coated leather. U.S. Patent Number 5,202,375 discloses a water-resistant polymer emulsion and coatings containing the emulsion applied to a board of particles and plywood. The polymer of the polymer emulsion contains from about 1 to about 5 weight percent olefinic carboxylic acid monomer and from about 0.5 to about 5 weight percent of a crosslinked monomer, for example, acetoacetoxyethyl methacrylate; and has a (Tg) of from about -50 ° C to about 50 ° C, preferably from about 0 ° C to about 20 ° C. The problem faced by the inventors is the provision of an aqueous composition suitable for use in the leather coating that is aesthetically pleasing and protective, and a method for coating leather that provides a dry coating on the leather that have good embossing and resistance to wet bending. In a first aspect of the present invention there is provided an aqueous composition suitable for use in the leather coating that includes an emulsion polymer that includes from 0.4% to 10% by weight of acetoacetate monomer or copolymerized acetoacetamide based on weight of the polymer and having a transition temperature of the vitreous state (Tg) from -20 ° C to 10 ° C. In a second aspect of the present invention there is provided an aqueous composition suitable for use in the leather coating that includes an aqueous emulsion polymer that includes from 0.1% to 6% by weight of copolymerized acetoacetate or acetoacetamide monomer based on the weight of the polymer and from 2% to 15% by weight of copolymerized carboxylic acid monomer based on the weight of the polymer and having a glass transition temperature of (TG) from -40 ° C to 0 ° C; the polymer having been contacted with an oxide, hydroxide, or transition metal carbonate at a pH of less than 9 in an amount greater than 0.20 equivalent of the transition metal per equivalent of carboxylic acid monomer copolymerized in the polymer. In a third aspect of the present invention there is provided a method for coating leather that includes (a) forming an aqueous composition that includes an emulsion polymer that includes 0.4% to 10% by weight of acetoacetate monomer or copolymerized acetoacetamide based on the weight of the polymer and having a glass transition temperature (Tg) of -20 ° C to 10 ° C; (b) coating leather with the aqueous composition; and (c) drying or allowing the aqueous composition to dry. In a fourth aspect of the invention there is provided a method for coating leather that includes (a) forming an aqueous composition that includes an emulsion polymer of 0.1% to 6% by weight of copolymerized acetoacetate or acetoacetamide monomer based on the weight of the polymer and from 2% to 15% by weight of copolymerized carboxylic acid monomer based on the weight of the polymer and having a glass transition temperature (Tg) from -40 ° C to 0 ° C; (b) contacting the polymer with a transition metal oxide, hydroxide or carbonate at a pH of less than 9 in an amount greater than 0.20 equivalent of the transition metal per equivalent of the carboxylic acid monomer copolymerized in the polymer; (c) coating the leather with the aqueous composition; and (d) drying, or allowing to dry, the aqueous composition. The present invention relates to a composition suitable for use in the leather coating and a method for coating leather with an aqueous composition that includes an emulsion polymer that includes at least one copolymerized ethylene glycol unsaturated monomer and 0.4% a % by weight, preferably from 0.4% to 4% by weight, of copolymerized acetoacetate monomer or acetoacetamide and having a glass transition temperature (Tg) from -20 ° C to 10CC. The emulsion polymer contains at least one etilenglilcol unsaturated monomer copolymerized excluding copolymerized acetoacetate or acetoacetamide copolymerized for example, a monomer of methacrylic ester including methyl acrylate, ethyl acrylate, butyl acrylate, acrylate, 2-ethyl hexyl, decyl acrylate, lauryl acrylate, methyl methacrylate, butyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, aminoalkyl methacrylates; styrene or substituted styrene; butadiene; vinyl acetate or other vinyl esters; vinyl monomers, for example, vinyl chloride, vinylidene chloride, M-vinyl pyrrolidone; and acrylonityl or metachronityl. The use of the term "meta" followed by another term, for example acrylate or acrylamide, as used throughout the presentation, refers to both acrylates or acrylamides and methacrylates and methacrylamides, respectively. The absence of copolymerized monomers containing functional groups capable of chemical reactions with acetoacetate or acetamide groups, for example, the aldehyde and amine groups is preferred. A polymer that includes 25-65% by weight of copolymerized ethyl acrylate is preferred. The emulsion polymer contains from 0.4% to 10% by weight of copolymerized acetoacetate or acetoacetamide copolomerizado, that is, an ethylene unsaturated monomer containing an acetoacetate or acetoacetamide group, such acetoacetato- vinyl methacrylate, acetoacetoxyethyl methacrylate acetoacetoxypropyl, allyl acetoacetate, acetoacetoxybutyl methacrylate, 2,3-diacetocasetoxypropyl methacrylate, vinyl acetoacetamide, and acetoacetoxyethyl methacrylamide. The emulsion polymer may also contain from 0% to 10% of a copolymerized unsaturated monoethylene glycol carboxylic acid monomer, based on the weight of the polymer; for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate and maleic anhydride. Preferred carboxylic acid monomers are acrylic acid, methacrylic acid and itaconic acid. The emulsion polymer used in the present invention may also contain from 0% to 5% multietilenglicol unsaturated monomers copolymerized, for example, allyl methacrylate, diallyl phthalate, dimethacrylate of 1, 4-butylene glycol dimethacrylate, 1, 2-ethylene , 1,6-hexanediol diacrylate and divinyl benzene. The transition temperature of the vitreous state (Tg) of the emulsion polymer is -20 ° C to 10 ° C, as measured by differential scanning calorimetry (DSC) taking the midpoint in the heat flow compared to the temperature transition as the value Tg. Polymerization techniques applied to prepare aqueous emulsion polymers are well known in the art. Conventional surfactants, for example, anionic or non-ionic emulsifiers, can be used in the emulsion polymerization process., for example, alkali metal or alkyl ammonium sulfates, alkyl sulfonic acids, fatty acids and oxyethylated alkyl phenols. The amount of surfactant used is usually from 0.1% to 6% by weight, based on the weight of the monomer. Thermal initiation or reduction oxide processes can be applied. The monomer mixture can be added pure or as an emulsion in water. The monomer mixture can be added in one or more additions or continuously over the assigned reaction period. The addition of the monomer in a single portion is preferred at the beginning of the reaction. Conventional free radical initiators can be used, for example, hydrogen peroxide, T-butyl hydroperoxide, ammonium or alkali persulfates, typically at a level of 0.01% to 3.0% by weight, based on the total monomer weight. Reduction oxide systems use the same initiators together with a suitable reductant, for example sodium sulfoxylate formaldehyde, sodium hydrosulfite, isoascorbic acid and sodium bisulfite at similar levels can be used. Chain transfer agents, for example, mercaptans, can be used to decrease the molecular weight of the polymer formed from one or more of the stage polymers; the use of a chainless transfer agent is preferred. The preferred average particle diameter of the polymerized polymer particles of the emulsion is from 30 manometers to 500 manometers. In an alternative embodiment the emulsion polymer can be prepared in a multistage polymerization process in which two or more polymeric steps vary in composition and are prepared in sequence. Polymerization techniques applied to prepare multistage aqueous emulsion polymers are well known in the art, for example, U.S. Patent Nos. 4,325,856; 4,654,397; and 4,814,373. A preferred two stage polymer has at least 80% by weight based on the weight of the polymer of a first polymer containing from 0.1% to 10% by weight of copolymerized acetoacetate or acetoacetamide monomer and having a transition temperature of vitreous state of (Tg) -40CC at 0 ° C, and 2% to 20% by weight based on the weight of the polymer of a second polymer containing from 0% to 10% by weight of copolymerized acetoacetate or acetoacetamide monomer and which has a 10 ° C higher than the Tg of the first polymer. The process generally produces the formation of at least two mutually incompatible polymer compositions, thus producing the formation of at least two phases. The mutual incompatibility of the two polymer compositions and the multi-phase structure resulting from the polymer particles can be determined in various ways known in the art. The use of scanning electron microscopy using dyeing techniques to enhance the difference between the appearance of the phases, for example, is one such technique. The present invention also relates to an aqueous composition suitable for use in the leather coating of the second aspect of the invention that includes an aqueous emulsion polymer that includes from 0.1% to 6% by weight, preferably from 0.1% to 4% , more preferably from 0.4% to 1% by weight, of copolymerized acetate acetate or acetoacetate monomer based on the weight of the polymer, and from 2% to 15% by weight, preferably from 4% to 5% by weight, of monomer of copolymerized carboxylic acid based on the weight of the polymer and having a glass transition temperature (Tg) of -40 ° C to 0 ° C, preferably of -40% to -8%; the polymer having been contacted with a transition metal oxide, hydroxide or carbonate at a pH of less than 9 in an amount greater than 0.20 equivalent, preferably greater than 0.50 equivalent, of the transition metal per equivalent of copolymerized carboxylic acid monomer in the polymer. The components, but not necessarily the amounts, ranges or values of the elements, of the aqueous emulsion polymer of this second aspect, for example, the copolymerized monomer, the copolymerized acetoacetate or acetoacetamide monomer, the copolymerized carboxylic acid and the Tg are the same as those defined above for the first aspect, as well as the method of preparation and the adjuvants used therein. The second aspect emulsion polymer is contacted with a transition metal oxide, hydroxide or carbonate at a pH lower than pH = 9, preferably pH = 3-β, in an amount greater than 0.20 equivalent, preferably greater than 0.50 equivalent, of the transition metal per equivalent of the copolymerized carboxylic acid monomer in the emulsion polymer in accordance with the process presented in U.S. Patent No. 5,221,284. Oxides, hydroxides and carbonates of zinc, aluminum, tin, tungsten and zirconium are preferred for low cost, low toxicity and low color in the dry coating. The most preferred is zinc oxide. The transition metal oxide, hydroxide or carbonate may be added in the form of a paste in water, optionally with an added dispersant, for example, a polymer or low molecular weight methacrylic acid shell. The oxideTransition metal oxide, hydroxide or carbonate may be added during the polymerization process or after the polymerization has ended. Alternatively, the transition metal can be added in soluble form, for example, a zinc ammonium carbonate solution added after the formation of the emulsion polymer and the neutralization of the emulsion polymer at a pH greater than 8. The aqueous composition it is prepared with techniques well known in the coatings art. First, optionally, at least one pigment is well dispersed in an aqueous medium under high cut as allowed by a COWELS (S) mixer or, alternatively, at least one previously dispersed dye is used. The emulsion polymer is then added under low shear stirring conditions together with other coating adjuvants, as desired. The aqueous coating composition may contain, in addition to the optional pigments and emulsion polymer, conventional coating adjuvants, such as, for example, emulsifiers, coalescing agents, buffers, neutralisers, thickeners, humectants, wetting agents, biocides, plasticizers, agents antifoams, dyes, waxes and antioxidants. An aqueous composition free of organic or polymeric compounds containing functional groups capable of making a chemical reaction with acetoacetate or acetamide groups, for example aldehydes and amines, is preferred. The solids content of the aqueous coating composition can be from about 10% to about 50% by volume. The viscosity of the aqueous composition can be from 0.05 to 10 Pa.s (50 to 10,000 cps), measured using a Brookfield viscometer, the viscosities suitable for the different application methods vary considerably. The composition of the aqueous coating can be applied to leather, for example, dyed mineral leather or dyed vegetable leather, including full-grain leather, defrosted or corrected grain leather, and split leather with or without pretreatment with an impregnating resin blend and with or without the application of subsequent coatings using conventional coating application methods, for example, curtain coater and spraying methods, for example, atomized air spraying, air assisted spraying, airless spraying, high volume spraying and low pressure spraying. and sprayed without air assisted by air. The aqueous coating composition coating the leather is typically dried or allowed to dry, at a temperature of 20 ° C to 75 ° C. Experimental Methods Flexural strength of coated leather Flexural strength in wet or dry conditions is based on the IUF 20 method of the International Union of Leather Chemists using a Bally flexometer (Bally schuh Fabriken AG, Schoenenwerd, Switzerland) . Specimens of dry or wet leather (65 mm by 40 mm) were flexed and examined for the crack measurement after the reported number of flexions. Embossing tests The coated leather was embossed on a turner press at 85-95 ° C and 70.3 kg / cm2 (1000 psi) for 5-7 seconds and the ease of removing the leather from the hot embossing press was evaluated (" Adhesion to the plate ") using a capillary cell plate. The quality of the impression was evaluated by analyzing the embossed capillary cell pattern in terms of precision and clarity. The cut, which is the ability to receive deep impressions without breaking the coating, was evaluated by analyzing the embossing pattern made using a flame plate for cuts in the film with a power 10 microscope. Abbreviations EA = ethyl acrylate BA = butyl acrylate AN = acrylonitile AA = acrylic acid EHA = 2-ethylexyl acrylate AAEM = 2-acetoacetylethyl methacrylate BMA = butyl methacrylate ACRYSOL and HYDROLAC are trademarks of Rohm and Haas Company. EUDERM, BAYDERM, and EUKANOL are trademarks of Bayer AG. The following examples are presented to illustrate the invention and the results obtained through the testing procedures. EXAMPLE 1 Preparation of an emulsion polymer Preparation of the Sample 1. The polymerization was carried out in a three-liter round-bottomed glass flask with a capacity of three liters equipped with a mechanical shaft stirrer, a thermocouple to monitor the temperature, a reflux condenser, a mechanism for heating and cooling and a nitrogen atmosphere. The flask was charged with 420 g of deionized water and 1.0 g of sodium lauryl sulfate and heated to 55 ° C. A pre-monomer emulsion was prepared with 410 g of deionized water, 9 g of sodium lauryl sulfate, 890 g of ethyl acrylate, 100 g of 2-acetoxyethyl methacrylate and 10 g of acrylic acid. 70 g of the previous monomer emulsion was added to the reaction flask together with 0.02 g of iron (II) sulfate heptahydrate, 4.8 of ammonium persulfate and 0.1 of sodium bisulfite. A total of 50 g of deionized water was used to dissolve iron sulfate, ammonium persulfate and sodium bisulfite and to rinse the materials in the reaction flask. After an exotherm of 10 ° C, the previous emulsion monomer was added to the reaction flask with 0.5 g of ammonium persulfate and 0.9 of additional sodium bisulfite for a period of 3 hours while the temperature was maintained at 60 ° C. C. A total of 93 g of deionized water was used to dissolve the ammonium persulfate and sodium bisulfite and to rinse the containers and remove these reagents and the previous emulsion from the reaction flask. After this, 3.5 g of 70% tert-butyl hydroperoxide, 1.7 g of isoascorbic acid and 0.02 g of iron sulphate eptahydrate were added to the reaction with a total of 90 g of deionized water. After cooling to 45 ° C, the pH was raised with 30 g of aqueous 28% ammonia solution. The product of the reaction was cooled to room temperature and filtered to remove the clot. A polymer latex with a solids content of 46.9% by weight, a pH of 8.4 and a viscosity of 0.04 Pa.s (40 cps) was obtained. The Tg of the polymer was determined at -10 ° C. Examples 2-5 and Comparative Examples A-F were prepared according to the process of Sample 1 with the amounts of monomers corresponding to the compositions presented in Table 1.1.

Table 1. Compositions of Sample 2 and Comparative Samples A-B Sample Composition Tg (in ° C) Corap. A 90 EA / 9 MMA / 1 AA - 7 2 80 BA / 8 AN / 10 AAEM / 2 AA - 19 comp. B 81 B A / 8 AN / 9 MMA / 2 AA - 17 EXAMPLE 2 _ Preparation of the Emulsion Polymer Preparation of the Sample 3. The polymerization was carried out in a round-bottomed flask with four inlets of 5 liters capacity equipped with a mechanical stirrer, a thermocoupler to monitor the temperature, a condenser of reflux, a mechanism for heating and cooling and a nitrogen atmosphere. The flask was charged at room temperature with 1765 g of deionized water, 20 g of sodium lauryl sulfate, 960 g of ethyl acrylate, 10 g of 2- (acetoacetoxyethyl) methacrylate and 30 g of acrylic acid. Polymerization was started with 0.02 g of iron sulfate heptahydrate in 5 g of deionized water, 0.25 g of ammonium persulfate in 10 g of deionized water and 1.1 g of technical grade sodium hydrosulfite in 20 g of deionized water. A rapid exotherm was observed at 90 ° C. After cooling to 60 ° C, 2.5 t of 70% tert-butyl hydroperoxide and 1.3 g of isoascorbic acid in a total of 60 g of deionized water were added to the reaction flask. After cooling to 40 ° C, a paste of 5 g of zinc oxide in 14.5 g of deionized water was added to the reaction flask and stirred for one hour. The pH was then raised with 19 g of aqueous 18% ammonia solution. The product of the reaction was cooled to room temperature and filtered to remove the clot. A polymer latex with a solids content of 34.8% by weight was obtained, at a pH of 7.7 and a viscosity of 0.048 Pa.s (48 cps). Examples 4-26 and Comparative Samples C-G were prepared according to the process of Sample 4 with amounts of monomers corresponding to the compositions presented in Table 2.1. Table 2.1 Composition of Samples 4-26 and Comparative Samples C-G Sample Composition Tg of the polymer (in ° C) Comp. C 90 EA / 9 MMA / 1 AA - 6 Comp. D 96.5 EA / 3.5 AA // 0.25 eqv. ZnO 9 4 93.5 EA / 3 AAEM / 3.5 AA // 0.25 eqv. ZnO 7.5 Comp. E 87.5 EA / 9 AAEM / 3.5 AA // 0.25 eqv. ZnO 5 95.5 EA / 1 AAEM / 3.5 AA // 0.25 eqv. ZnO 6 96.5 EA / 1 AAEM / 3.0 AA // 0.29 eqv. ZnO 9 7 96.5 EA / 1 AAEM / 2.5 AA // 0.35 eqv. ZnO 9 8 79.5 EA / 15 BA / 2 AAEM / 3.5 AA // 0.25 eqv. ZnO 14 9 60.5 EA / 35 BA / 1 AAEM / 3.5 AA // 0.25 eqv. ZnO 20 95.5 EA / 1 AAEM / 3.5 AA // 0.25 eqv. ZnO 9 11 61 EA / 35 BA / 0.5 AAEM / 3.5 AA // 0.75 eqv. ZnO 24 12 41 EA / 55 BA / 0.5 AAEM / 3.5 AA // 0.75 eqv. ZnO - 30 13 21 EA / 75 BA / 0.5 AAEM / 3.5 AA // 0.75 e; cqv. ZnO - 37 14 61 EA / 35 EHA / 0.5 AAA / 3.5 AA // 0.75 eqv. ZnO - 29 51 EA / 45 EHA / 0.5 AAA / 3.5 AA // 0.75 eqv. ZnO -36 16 60.6 EA / 35 BA / 0.9 AAEM / 3.5 AA // 0.9 eqv. ZnO - 23 17 80.6 BA / 15 MMA / 0.9 AAEM / 3.5 AA // 0.9 eqv. ZnO- 24 18 63.6 BA / 32 BMA / 0.9 AAEM / 3.5 AA // 0.9 eqv. ZnO- 25 19 43.6 BA / 53 BMA / 0.9 AAEM / 3.5 AA // 0.9 eqv. ZnO- 12 20 68.6 BA / 27 MMA / 0.9 AAEM / 3.5 AA // 0.9 eqv. ZnO- 12 21 56.6 Ba / 39 BMA / 0.9 AAEM / 3.5 AA // 0.9 eqv. ZnO- 20 Comp. F 23.6 BA / 72 BMA / 0.9 AAEM / 3.5 AA // 0.9 eqv. ZnO + 8 Comp. G 56.6 BA / 39 MMA / 0.9 AAEM / 3.5 AA // 0.9 eqv. ZnO +14 22 59.6 EA / 35 Ba / 0.9 AAEM / 4.5 AA // 0.7 eqv. ZnO -20 23 57.3 BA / 29.8 EA / 0.9 AAEM / 4.5 AA // 0.7 eqv. ZnO -22 24 57.3 BA / 28.8 EA / 0.9 AAEM / 5.5 AA // 0.57 eqv. ZnO -21 89 EA / 10 AAEM / 1 AA - 8 26 90.5 EA / 6 AAEM / 3.5 AA // 0.25 eqv. ZnO - 5 EXAMPLE 3 Embossing properties of leather coated with aqueous compositions. An aqueous composition was prepared with 60 g of pre-dispersed black pigment (Stahl PP-15979) and 42 g of polymer solids diluted to a total of 123 g with water 7.5 g of 1/1 Acrysol RM-2020 / water was sprayed on two layers, 0.015 and 0.0065 g / cm2 (14 and 6 grams / square feet), in corrected grain leather with upholstery weight and dried for 2 minutes at 93.3 ° C (200 ° F). Cuts were cut from 3.8 by 11.4 cm (1.5 inch by 4.5 inch) leather pieces and were embossed together with plates that either had a coarse cell cell (CHC) or a Llama print. Adhesion to the plate was evaluated using the CHC plate, the cut resistance was evaluated using the Llama plate. The results are presented in tables 3.1 and 3.2 The leather coated with the compositions of the invention containing Samples 1 and 2 showed superior performance to the leather coated with the compositions Comp. A and Comp. B, respectively.

(Table 3.2 Plate Cutting Flame and Plate Temperature of 88 ° C and 100 ° C Cutting Classification Sample (88 ° C / 100 ° C) Polymer 1 Good (-) / Good Comp. A Severe / Severe 2 Good ( -) / Good Comp. B Severe / Severe Comp C Moderate-Severe / Moderate-Severe 25 Good (-) / Good The leather coated with the compositions of the invention that contained Samples 1, 2 and 25 showed a substantially higher yield to leather coated with Compositions Comp.A, Comp.B and Comp.C, respectively.

EXAMPLE 4 Evaluation of resistance to wet bending of coated leather with aqueous compositions. Aqueous compositions were prepared with 40 G of previously dispersed white pigment (Stahl P-4805) and 21 g of polymer solids constituted with 60 g of water. Full-grain leather was coated with 2 coats, 0.015 and 0.0086 g / sq cm (14 and 8 g / square feet), and dried for 2 minutes at 93.3 ° C (200 ° F). The coated leather was embossed with a coarse capillary cell plate at 70-75 ° C, 50 tons for 8 seconds and its top surface was coated with 0.0043 g / sq cm (4 g / square feet) 2/1 Hydrolac R / Water. The test of resistance to wet bending was performed 2 days after spraying. The results are presented in table 4.1 The color coated with the compositions of the invention containing Samples 1, 2 and 25 showed a substantially higher performance than leather coated with Comp. A and Comp. B, and Comp. C, respectively.

EXAMPLE 5 Evaluation of performance of coated leather with aqueous compositions containing emulsion polymers having various levels of acetoacetate-polymerized monomer. An aqueous composition was prepared with 40 g of previously dispersed white pigment (Stahl P-4805), 15.3 g of polymer solids that constituted a total of 65 g with water. Two coats of the composition were sprayed on full grain leather, 0.015 and 0.0065 g / sq cm (14 and 6 g / square feet), dried for 2 minutes at 93.3 ° C (200 ° F). The coated leather was embossed and its top layer was covered with .0043 g / sq cm (4g / square feet) 2/1 Hydrolac R / water. The results of the evaluation are presented in Tables 5.1 and 5.2.

The leather coated with aqueous compositions containing the emulsion polymer of Samples 4 and 26 show that as the level of AAEM increases, the adhesion to the plate and, in particular, the cut resistance, improved; however, the definition of plaque decreased at the maximum level of AAEM (Comp.E).

Even the minimum level of AAEM in the emulsion polymer (Sample 4) improved the wet flexural strength of the coated leather with an aqueous composition containing the emulsion polymer.

EXAMPLE 6 Performance evaluation of coated leather with aqueous compositions containing emulsion polymers having various compositions.

An aqueous coating composition was prepared with 50 g of pre-dispersed white pigment (Euderm D CR), 12.5 g of silicone dioxide delustrar agent (Euderm Duller SN), 26.3 g of polymer solids, 13.2 g 1/3 of polyacrylate thickener (Euderm Additive NA) / water and constituted with water to a total of 200 g. Two coats, 0.015 and 0.0075 g / sq cm (14 and 7 g / square feet), of the corrected grain leather composition were sprayed and each was dried for two minutes at 93.3 ° C (200 ° F). The coated leather was embossed with a coarse capillary cell plate and its top layer was coated with 0.0043 g / sq cm (4g / sq ft) 2/1 hydrolac R / water. The results are presented in table 6.1.

EXAMPLE 7 Performance evaluation of coated leather with aqueous compositions containing emulsion polymers having various compositions. Aqueous coating compositions containing Samples 10-15 and Comparative Sample D 50 g Euderm D-CR and 26.5 g of polymer solids constituted with water at 125 g (175 g total) were prepared. The viscosity was adjusted to 0.07-0.09 Pa.s (70-90 cps) with RHOPLEX RM-2020 / water. Two layers of the composition were sprayed on full grain leather, 0.014 and 0.0097 g / sq cm (13 and 9 g / square feet), and each was dried for two minutes at 93.3 ° C (200 ° F). The coated leather was embossed with a coarse capillary cell press plate and its top layer was coated with 0.0043 g / sq cm (4 g / square feet) 2/1 Hydrolac R / water. Bally wet bending strength was measured 3 days after spraying. The leather coated with the aqueous coating containing Comparative Sample D produced severe cracks, Samples 10-15 did not produce cracks in the leather after 100,000 cycles. The leather with coatings made with Samples 11-15 were tested for Bally cold bending (-20 ° C); after 20,000 cycles the Leather Sample 11 showed very slight cracks; with polymers 12-15 there were no cracks.

EXAMPLE 8 Evaluation of performance of coated leather with aqueous compositions containing emulsion polymers qt? E has various compositions.

Aqueous coating compositions were prepared with 10 g of previously dispersed black pigment (Stahl Black PP-15979), 15 g water, 25 g Euderm Nappasoft S, 5 g Euderm Duller SN, and 57 g of polymer with 35% solids. The coating viscosity was adjusted to 0.07-0.08 Pa.s (70-80 cps) with Euderm Paste M. Two layers of 0.014 and 0.0065 g / sq cm (13 g / square feet) were sprayed on the grain leather. corrected. Each was dried for two minutes at 93.3 (200 ° F). The coated leather was / sq cm embossed 232 (0.25 square feet) pieces for 5 seconds - at the temperatures shown and its top coat was coated with 0.0043 g / sq cm (4 g / square feet) 2/1 Hydrolac R / water. The test pieces were embossed with a capillary cell impression sufficient for wet bending Bally was tested 3 days after spraying. The leather coated with coatings containing the polymer of Samples 16-19 and 21-22 and Comp. F passed 40,000 push-ups without cracks in the leather. The Bally dry flex was tested 1 day after spraying. The leather coated with the coatings containing all the polymer samples except Comp. G passed 100,000 push-ups without cracks in the leather.

EXAMPLE 9 Evaluation of performance of coated leather with aqueous compositions containing emulsion polymers having various compositions.

An aqueous coating composition was prepared with 140 g of water / 200 g of Euderm D-CR white, 100 g of Euderm Duller SN, 100 g of aqueous emulsion of fatty acid esters (Euderm Nappasoft S), and 460 g of polymer with 35 % solids The coating viscosity was adjusted to 0.06-0.07 (60-70 cps) with 1/1 Euderm Paste M / water. The composition was sprayed at 0.016 g / sq cm (15 g / sq. Ft.) On corrected grain leather, two additional coats of 0.012 g / sq cm each (11 g / sq.ft. each) were sprayed; Each layer was dried for 2 minutes at 93.3 ° C (200 ° F). On the day of spraying, pieces were embossed in pairs of 7.0 cm by 15.2 cm (2.75 by 6 in) with a flame plate at 92 ° C for 5 seconds. Pieces of 232 sq cm (0.25 sq ft) were individually embossed with a coarse capillary cell plate at 93 ° C for 5 seconds.

The leather coated with the aqueous composition containing the polymer without EA (Sample 17) showed poorer embossing than in Samples 22-24.

Claims (4)

1. CLAIMS 1. An aqueous composition suitable for use in the leather coating comprising an aqueous emulsion polymer comprising from 0.4% to 10% by weight of acetoacetate or acetoacetamine monomer copolymerized based on the weight of the polymer and having a transition temperature of the vitrio state from -20 ° C to 10 ° C.
2. 2. An aqueous composition suitable for use in the leather coating comprising an aqueous emulsion polymer comprising from 0.1% to 6% by weight of copolymerized acetoacetate or acetoacetate monomer based on the weight of the polymer and 2% by weight 15% by weight of copolymerized carboxylic acid monomer based on the weight of the polymer and having a glass transition temperature of -40 ° C to 0 ° C; the polymer having been contacted with a transition metal oxide, hydroxide or carbonate with a pH of less than 9 in an amount greater than 0.20 equivalent of the transition metal per equivalent of the carboxylic acid monomer copolymerized in the polymer.
3. 3. A method for coating leather comprising a. Form an aqueous composition comprising an emulsion polymer comprising from 0.4% to 10% by weight of copolymerized acetoacetate or acetoacetamine monomer based on the weight of the polymer and having a glass transition temperature (Tg) of -20 ° C at 10 ° C; b. Coat the leather with the aqueous composition; and c. Dry or allow, dry, the aqueous composition.
4. 4. A method for coating leather comprising a. Form an aqueous composition comprising an emulsion polymer comprising from 0.1% to 6% by weight of copolymerized acetoacetate or acetoacetamine monomer based on the weight of the polymer and from 2% to 15% by weight of copolymerized carboxylic acid monomer with base on the weight of the multimeter having a glass transition temperature (Tg) of -40 ° C to 0 ° C; b. Contacting the polymer with a transition metal oxide, hydroxide or carbonate with a pH of less than 9 in an amount greater than 0.20 equivalent of transition metal per equivalent of carboxylic acid monomer copolymerized in the polymer; c. Coat the leather with the aqueous composition; and d. Dry or allow to dry, the aqueous composition.