Method for producing hydrophobicizing leather treatment agents

Abstract

A method of preparing hydrophobicizing leather treatment compositions includes the steps of a) free-radically initiated copolymerization of i) at least one ethylenically unsaturated carboxylic acid or its derivatives, and ii) at least one (meth)acrylate of a primary saturated C.sub.8 to C.sub.22 alcohol, b) mixing the reaction mixture obtained after step a) with water, c) salting at least some of the carboxyl groups of the reaction mixture obtained after step b) with a base, and d) shearing the reaction mixture obtained after step c) to an average particle size of 0.05-10 μm,
wherein step a) is carried out in oil as reaction medium and wherein the atmosphere in step a) contains less than 0.1% by volume of an oxidizing gas.

Claims

1. A method of preparing hydrophobicizing leather treatment compositions comprising the steps of a) free-radically initiated copolymerization of i) at least one ethylenically unsaturated carboxylic acid or its derivatives, and ii) at least one (meth)acrylate of a primary saturated C.sub.8 to C22 alcohol, b) mixing the reaction mixture obtained after step a) with water, c) salting carboxyl groups of the reaction mixture obtained after step b) with a base, and d) shearing the reaction mixture obtained after step c) to an average particle size of 0.05-10 μm, wherein step a) is carried out in white oil as reaction medium and wherein the atmosphere in step a) comprises less than 0.1% by volume of an oxidizing gas.

2. The method according to claim 1, wherein the at least one ethylenically unsaturated carboxylic acid or its derivatives of component i) is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid and also their derivatives, and alkali metal salts, and their mixtures.

3. The method according to claim 1, wherein the at least one (meth)acrylate of a primary saturated C.sub.8 to C22 alcohol of component ii) is selected from the group consisting of octyl acrylate, octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, methacrylic ester of hydrogenated tallow fat alcohol, acrylic ester of hydrogenated tallow fat alcohol, stearyl methacrylate, stearyl acrylate, hexadecyl acrylate, hexadecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, eicosanyl acrylate, eicosanyl methacrylate, docosanyl methacrylate and docosanyl acrylate and their mixtures.

4. The method according to claim 1, wherein the copolymerization is initiated by at least one activator selected from the group consisting of tertiary butyl hydroperoxide, ditertiary butyl peroxide, dibenzoyl peroxide, succinic peroxide, cumene hydroperoxide, tertiary butyl perbenzoate, 2,2-azobis(2-methylbutyronitrile), 2,2-azobisisobutyronitrile and mixtures thereof.

5. The method according to claim 1, wherein step a) utilizes at least one chain transfer agent.

6. The method according to claim 1, wherein the weight ratio of the at least one ethylenically unsaturated carboxylic acid or its derivatives of component i) to the at least one (meth)acrylate of a primary saturated C8 to C22 alcohol of component ii) is 1:10-10:1.

7. The method according to claim 1, wherein the shearing in step d) is to an average particle size of 0.1-8 μm.

8. The method according to claim 1, wherein further added substances present in the process are selected from the group consisting of organic solvents, emulsifiers, preservatives and also at least one further comonomer of component iii), said further comonomer being used in step a).

9. The method according to claim 1, wherein the amounts of the components used in steps a)-d) of the method, expressed relative to the total dry amount of the reaction mixture obtained after step d), are as follows: at least one ethylenically unsaturated carboxylic acids or its derivatives of component i): 3.0 to 25.0 wt %, at least one (meth)acrylate of a primary saturated C8 to C22 alcohol of component ii): 8.0 to 20.0 wt %, at least one activator: 0.12 to 5 wt %, at least one chain transfer agent: 0.02 to 2.0 wt %, at least one base: 1.8 to 7.0 wt %, white oil: 50.0 to 87.0 wt %, and further added substances: 0.0 to 8.0 wt %.

10. The method according to claim 1, wherein the method utilizes less than 2 wt % of an organic solvent, relative to the total dry amount of the reaction mixture obtained after step d).

11. The method according to claim 1, wherein the method utilizes less than 2 wt % of an emulsifier, relative to the total dry amount of the reaction mixture obtained after step d).

12. The method according to claim 1, wherein the at least one (meth)acrylate of a primary saturated C8 to C22 alcohol of component ii) is selected from the group consisting hexadecyl acrylate, stearyl methacrylate and their mixtures.

13. The method according to claim 1, wherein the copolymerization is initiated by at least one activator selected from the group consisting of ditertiary butyl peroxide, 2,2-azobis(2-methylbutyronitrile) and mixtures thereof.

Description

EXAMPLES

I) Method of Preparing Hydrophobicizing Leather Treatment Compositions in the Manner of the Present Invention

Example 1

(1) 130 g of White oil 285 (from Parafluid) are initially charged at 140° C. under nitrogen. The monomers are prepared as a mixture of 130 g of Stearyl methacrylate 1618 F (from BASF SE), 70 g of 98% pure acrylic acid (from Acros) and 1.2 g of oleic acid (from Aldrich), while a solution of 6 g of ditertiary butyl peroxide (from Merck) in 20 g of White oil 285 (from Parafluid) serves as initiator solution.

(2) To consistently start the reaction, 10 g of the monomer mixture are added to the initial charge of white oil and, after homogenization, the remainder of the abovementioned monomer mixture is then added over 2 hours under agitation at the same time as the abovementioned initiator solution. Further stirring at 140° C. for 2 hours follows the admixture.

(3) After two hours, the batch is allowed to cool down to 100° C. and admixed with 1440.7 g of demineralized water. After the admixture of water, 77.8 g of 50% aqueous sodium hydroxide solution diluted with 100 g of demineralized water are added.

(4) After one hour of stirring at 80 to 90° C., a vacuum is applied for devolatilization and 600 g of water are admixed to adjust the solids content to 20%.

(5) 200 g of the dispersion obtained are admixed with 50 g of White oil 285 (from Parafluid) and treated with a T 25 B Ultra-Turrax from IKA at 300 rpm for 10 min. The average particle size of the dispersion is measured as 1.397 μm by dynamic light scattering (using an LS 230 from Beckman Coulter).

Example 2

(6) 130 g of White oil 285 (from Parafluid) are initially charged at 140° C. under nitrogen. The monomers are prepared as a mixture of 130 g of Stearyl methacrylate 1618 F (from BASF SE), 70 g of 98% pure acrylic acid (from Acros) and 1.2 g of oleic acid (from Aldrich), while a solution of 6 g of ditertiary butyl peroxide (from Merck) in 20 g of White oil 285 (from Parafluid) serves as initiator solution.

(7) To consistently start the reaction, 10 g of the monomer solution are added to the initial charge of white oil and, after homogenization, the remainder of the abovementioned monomer mixture is then added over 2 hours under agitation at the same time as the abovementioned initiator solution.

(8) Further stirring for 2 hours follows the admixture. After the first hour, 546 g of White oil 285 (from Parafluid) are admixed.

(9) The two hours are followed by cooling down to 100° C. and admixing 1274.3 g of demineralized water, preheated to 80 to 90° C., until homogeneous. After water admixture, 77.8 g of 50% aqueous sodium hydroxide solution diluted with 100 g of demineralized water are added.

(10) One hour of stirring at 80 to 90° C. is followed by application of vacuum for devolatilization and adjustment of the solids content to 40%.

(11) For shearing, the dispersion obtained is aftertreated with a T 25 B Ultra-Turrax from IKA at the highest setting for 10 minutes.

(12) The average particle size of the dispersion is measured as 1.687 μm (measurement method and instrument correspond to Example 1).

Example 3

(13) 263.6 g of White oil 285 (from Parafluid) are initially charged at 140° C. under nitrogen.

(14) The monomers are prepared as a mixture of 47.2 g of Stearyl methacrylate 1618 F (from BASF SE), 25.5 g of 98% pure acrylic acid (from Acros) and 3.5 g of 1-butanol (from Alfa-Aesar), while a solution of 2.1 g of ditertiary butyl peroxide (from Merck) in 20 g of White oil 285 (from Parafluid) serves as initiator solution.

(15) To consistently start the reaction, 9.8 g of the monomer mixture are added to the initial charge of white oil and, after homogenization, the remainder of the abovementioned monomer mixture is then added over 2 hours under agitation at the same time as the abovementioned initiator solution. Further stirring at the same temperature for 2 hours follows the admixture.

(16) The two hours are followed by cooling down to 100° C. and admixing 560.0 g of demineralized water, preheated to 80 to 90° C., until homogeneous. After water admixture, 28.2 g of 50% aqueous sodium hydroxide solution diluted with 100 g of demineralized water are added.

(17) After one hour of stirring at 80 to 90° C., a vacuum is applied for devolatilization and 44.3 g of water are admixed to adjust the solids content to 36%.

(18) The dispersion thinned to a 20% solids content for viscosity reasons is treated twice with a Micro Fluidizer from Micro Fluidics at 1100 bar. The average particle size of the dispersion is measured as 0.133 μm (measurement method and instrument correspond to Example 1).

Example 4

(19) 130 g of White oil 285 (from Parafluid) are initially charged at 140° C. under nitrogen.

(20) The monomers are prepared as a mixture of 130 g of Stearyl methacrylate 1618 F (from BASF SE), 70 g of 98% pure acrylic acid (from Acros) and 1.2 g of oleic acid (from Aldrich), while a solution of 6 g of ditertiary butyl peroxide (from Merck) in 20 g of White oil 285 (from Parafluid) serves as initiator solution.

(21) To consistently start the reaction, 10 g of the monomer solution are added to the initial charge of white oil and, after homogenization, the remainder of the abovementioned monomer mixture is then added over 2 hours under agitation at the same time as the abovementioned initiator solution.

(22) Further stirring for two hours follows the admixture. After the first hour, 546 g of White oil 285 (from Parafluid) are admixed.

(23) After two hours, the batch is allowed to cool down to 90° C. and the clear solution is drawn off.

(24) A glass beaker is initially charged with 230.4 g of water followed by the admixture of 13.2 g of 50% aqueous sodium hydroxide solution. This mixture is stirred with a 70 mm diameter dissolver disc at low speeds. This is followed by the addition in the form of a thin jet of 150.8 g of the polymer prepared as described in Example 5 and dissolved in white oil, and the speed is carefully raised to 3000 rpm.

(25) The dispersion thus obtained (with a solids content of 39.9%) is then aftertreated with a Gaulin 15M 8TA high-pressure homogenizer at 200 bar twice and thereafter once more at 500 bar.

(26) The average particle size of the dispersion is measured as 5.448 μm (measurement method and instrument correspond to Example 1).

Example 5

(27) 130 g of White oil 285 (from Parafluid) are initially charged at 140° C. under nitrogen.

(28) The monomers are prepared as a mixture of 130 g of Stearyl methacrylate 1618 F (from BASF SE), 70 g of 98% pure acrylic acid (from Acros) and 1.2 g of oleic acid (from Aldrich), while a solution of 6 g of ditertiary butyl peroxide (from Merck) in 20 g of White oil 285 (from Parafluid) serves as initiator solution.

(29) To consistently start the reaction, 10 g of the monomer solution are added to the initial charge of white oil and, after homogenization, the remainder of the abovementioned monomer mixture is then added over 2 hours under agitation at the same time as the abovementioned initiator solution.

(30) Further stirring for two hours follows the admixture. After the first hour, 546 g of White oil 285 (from Parafluid) are admixed.

(31) After two hours, the batch is allowed to cool down to 90° C. Thereafter, 2059.3 g of demineralized water are admixed under agitation, followed by stirring until homogeneous. Then, 77.8 g of 50% aqueous sodium hydroxide solution dissolved in 100 g of water are run in and the reaction mixture is additionally stirred at 80 to 90° C. for one hour and then briefly devolatilized in vacuo.

(32) The 30% dispersion present is treated with a 70 mm diameter dissolver disc at 4000 revolutions/min for 5 minutes. The average particle size of the dispersion is measured as 3.102 μm (measurement method and instrument correspond to Example 1).

Example 6

(33) 180 g of White oil 285 (from Parafluid) are initially charged in a stirred three-neck flask at 140° C. under nitrogen.

(34) The monomers are prepared as a mixture of 70 g of Stearyl methacrylate 1618 F (from BASF SE), 130 g of 98% pure acrylic acid (from Acros) and 3.6 g of oleic acid (from Aldrich), while a solution of 6 g of ditertiary butyl peroxide (from Merck) in 20 g of White oil 285 (from Parafluid) serves as initiator solution.

(35) To consistently start the reaction, 10 g of the monomer solution are added to the initial charge of white oil and, after homogenization, the remainder of the abovementioned monomer mixture is then added over 2 hours at the same time as the abovementioned initiator solution.

(36) Following a pronounced increase in viscosity, a further 250 g of white oil are added. This is followed by a further two hours of stirring at 140° C.

(37) After two hours, the batch is allowed to cool down to 90° C. Thereafter, 436.6 g of demineralized water are admixed under agitation, followed by stirring until homogeneous. Then, 60 g of 50% aqueous sodium hydroxide solution are run in and the reaction mixture is additionally stirred at 80 to 90° C. for one hour. During that time, altogether 1300 ml of demineralized water are admixed to reduce the viscosity. This is followed by brief devolatilization in vacuo.

(38) The 26% dispersion present is treated with a 70 mm diameter dissolver disc at 4000 revolutions/min for 5 minutes. The average particle size of the dispersion is measured as 2.756 μm (measurement method and instrument correspond to Example 1).

II) Performance Examples

Tanning of Leather by Using the Hydrophobicizing Leather Treatment Compositions Obtained According to Examples 1-6

(39) The starting material is chrome-tanned cattlehide wet blue containing about 2.5% of chromium(III) oxide and having a shaved thickness of 1.5 to 2.0 mm; the treatment takes place in customary rotating drums.

(40) The following operating steps are carried out in sequence (the particulars in % are based on the shaved weight of the wet blue):

(41) A. Acidic wash with 200% of water and 0.2% of 85% formic acid. (Time required: 15 min): Target pH of liquor at the end: 3.3. Drop the float.

(42) B. Retanning, first stage (time required in total: 240 min)

(43) Admixture of 100% of water and

(44) 2% of a lightfast chromium- and syntan-containing retanning agent (Blancorol RC, LANXESS)

(45) 2% of chromium(III) sulfate, (Chromosal B, LANXESS),

(46) 1.5% of a lightfast anionic retanning agent (Tanigan PAK, LANXESS),

(47) 1.0% of sodium formate,

(48) 1.0% of sodium bicarbonate,

(49) 3.0% of a synthetic polycondensation replacement tanning agent (Tanigan F, LANXESS),

(50) Target pH of the liquor at the end: 5.0.

(51) Drop the float.

(52) C. Retanning, dyeing (time required in total: 240 min):

(53) Admixture of 50% of water and

(54) 4.0% of an acrylate copolymer-based retanning agent (Leukotan 8090 LANXESS),

(55) 4.0% of chestnut extract, sweetened,

(56) 4.0% of a synthetic polycondensation replacement tanning agent (Tanigan F, LANXESS),

(57) 4.0% of an anionic resin type tanning agent (Retingan R 7, LANXESS),

(58) 1.0% of a synthetic polycondensation tanning agent (Tanigan PR, LANXESS),

(59) 3.0% of a dye (Baygenal Yellow Brown 3G, LANXESS),

(60) 5.0% of a hydrophobicizing leather treatment composition as per any one of Examples 1-6

(61) 4.0% of a hydrophobicizer based on polysiloxane (Levotan W, LANXESS)

(62) D. Sharpening (time required in total: 60 min):

(63) Admixture of 100% of water and

(64) 1.1% of 85% formic acid and also after 30 minutes

(65) 1.1% of 85% formic acid.

(66) Target pH of the liquor at the end: 3.4 to 3.6.

(67) Drop the float.

(68) E. Rinsing (time required in total: 10 min):

(69) Admixture of 300% of water.

(70) Drop the float.

(71) F. Fixing (time required in total: 90 min):

(72) Admixture of 300% of water and

(73) 2% of modified chromium(III) sulfate (Chromosal BF, LANXESS) and after 30 minutes again

(74) 2% of modified chromium(III) sulfate.

(75) Target pH of the liquor at the end: 3.3.

(76) After 60 min drop the float.

(77) G. Rinsing (time required in total: 10 min):

(78) Admixture of 300% of water.

(79) Drop the float.

(80) H. Rinsing (time required in total: 10 min):

(81) Admixture of 300% of water.

(82) Drop the float.

(83) I. Rinsing (time required in total: 10 min):

(84) Admixture of 300% of water.

(85) Drop the float.

(86) J. Finalizing:

(87) After draining, leathers horsed overnight, then set out, suspension dried, staked.

(88) The leathers obtained are soft, firm-grained, exhibited a smooth grain side and have a pleasant hand. No depth of shade difference is detectable between the grain side and the flesh side.

(89) To determine their hydrophobic properties, especially their dynamic water resistance, the leathers were MAESER tested (in line with ASTM D 2099-70). In this test, the waterproofness of the leather treated with the hydrophobicizing leather treatment composition is tested under permanent flexing of the diecut leather test specimen. This simulates the stress imposed on a leather made into a shoe or boot donned for a walk in a wet environment (high wet grass, puddles, mud).

(90) A MAESER value of >greater than 15 000 is the minimum criterion of the U.S. military for waterproof shoe leather. The static water absorption of up to 30% is deemed acceptable for the industrial standard.

(91) To this end, 4 test specimens were diecut out of each leather, two in the longitudinal direction and two crosswise thereto. In addition, the static water absorption was determined.

(92) TABLE-US-00001 TABLE 1 Average MAESER particle size value MAESER values Water absorption Example μm average individual static [%] 1 1.397 >50000 4 × >50000 26.6 2 1.687 42175 39000, 29700, 2 × 50000 32.8 3 0.133 >50000 4 × >50000 24.7 4 5.448 32900 12800, 22300, 46500, >50000 32.1 5 3.102 39750 1 × 9000, 3 × >50000 23.8 6 2.756 14495 11500, 17400, 13550, 15530 42.7