Disclosure of Invention
The invention aims to provide a method for tanning sheep leather by using an organic amine and an epoxy resin tanning agent, aiming at the problems of tanning the obtained leather by using the epoxy resin tanning agent alone or combining with other tanning agents at present.
The invention provides a method for tanning sheepskins by using organic amine and an epoxy resin composition tanning agent, which is to perform tanning on the sheepskins softened by a conventional process or pickled and deacidified by the conventional process to the pH value of 7.5-8.0 according to the following process steps and conditions:
1) rotating in organic amine bath liquid with the liquid ratio of 80-100% and the mass percent concentration of 0.5-1.2% for 30-60 min at the temperature of 25-40 ℃;
2) adding the epoxy resin composition tanning agent into a rotary drum according to the mass percentage concentration of 6-12%, rotating for 1-2 hours at 35-40 ℃, then rotating for tanning for 6-10 hours at 45-50 ℃, replenishing water, and standing overnight;
3) rotating for at least 30min the next day, sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0, rotating for at least 30min, taking out the drum and building a bridge, and then performing subsequent process treatment according to the conventional method.
The organic amine used in the above method is any one of melamine, dicyandiamide or amino resin.
The epoxy resin composition tanning agent used in the method is composed of epoxy resin X and epoxy resin Y, and the mass ratio of the epoxy resin X to the epoxy resin Y is 0.5: 1-5: 1.
Wherein the epoxy resin X is a compound of the following general formula (I):
wherein R comprises one or two of the following A groups and B or C segments:
The epoxy resin X is prepared by the following process steps and conditions:
dropwise adding epoxy chloropropane in a molar ratio of 1: 4-6 of isophorone diamine (IPDA) at normal temperature while stirring, reacting at a constant temperature of 25-35 ℃ for 2-4 h, then sequentially adding polyol and a catalyst, dropwise adding epoxy chloropropane in a molar ratio of 1: 1-2 of hydroxyl groups in polyol, heating to 50-70 ℃ after dropwise adding, reacting at a constant temperature for 3-8 h, then cooling to 20-45 ℃, dropwise adding an alkaline compound in a molar ratio of 1: 0.8-1.1 of epoxy chloropropane, reacting at a constant temperature for 2-4 h, adding a neutralizing agent to neutralize until the pH value is neutral, carrying out rotary distillation on an upper layer product, removing unreacted epoxy chloropropane and residual water, and filtering to obtain epoxy resin X, wherein the molar ratio of isophorone diamine to polyol is 1: 1-1: 5.
Wherein the polyhydric alcohol is at least one of 1, 4-butanediol, ethylene glycol, diethylene glycol, glycerol and polyethylene glycol (average molecular weight 300, 400, 600), preferably glycerol, polyethylene glycol (average molecular weight 300, 400) and 1, 4-butanediol; the catalyst is any one of Lewis acid catalysts or Lewis base catalysts, preferably boron trifluoride diethyl etherate, tetrabutyl ammonium bromide or N, N-dimethylaniline, and the dosage of the catalyst is 0.4-1.0% of the total weight of isophorone diamine and polyhydric alcohol; the alkaline compound is sodium hydroxide solution or potassium hydroxide solution; the neutralizing agent is a mixed solution of potassium dihydrogen phosphate or sodium dihydrogen phosphate solution and acetic acid solution, wherein the weight ratio of the potassium dihydrogen phosphate or the sodium dihydrogen phosphate solution to the acetic acid solution is 0.5-5: 1, and the concentration of the potassium dihydrogen phosphate or the sodium dihydrogen phosphate solution is 15-25 wt%; the concentration of the acetic acid solution is 5-100 wt%; and the dripping speed of the epoxy chloropropane is 20-60 drops/min.
The epoxy resin Y contains at least one aliphatic glycidyl ether compound, and the aliphatic glycidyl ether compound is specifically at least one of ethylene glycol diglycidyl ether, 1, 4-butanediol diglycidyl ether, glycerol triglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether (the average molecular weight of polyethylene glycol is 300-600). At least one of 1, 4-butanediol diglycidyl ether, glycerol triglycidyl ether, and polyethylene glycol diglycidyl ether is preferable.
Compared with the prior art, the invention has the advantages that:
(1) the method provided by the invention firstly permeates organic amine into the leather fiber to provide more binding points for the epoxy resin tanning agent added in the subsequent process step, and the organic amine and the amine on the leather collagen fiber can simultaneously react with the epoxy resin tanning agent to form a reticular cross-linked structure, so that the moisture-heat resistance stability of the leather is improved, and the epoxy resin can be used as a main tanning agent to tan sheep skin, thereby improving the tanning performance of the leather.
(2) Because the X component of the epoxy resin composition tanning agent used by the method contains alicyclic group with rigid structure, when the X component permeates into leather fiber, the X component can endow leather with plump characteristic, so that the structure of the tanned leather is more stable, and the Y component can better penetrate into the molecular interior of leather collagen fiber to form intramolecular or intermolecular crosslinking, thereby further improving the damp-heat resistance stability of the leather and ensuring that the shrinkage temperature of the tanned leather reaches more than 80 ℃.
(3) Because the isophorone diglycidyl amine chain segment contained in the X component of the epoxy resin composition tanning agent used by the method is a tertiary amine molecular structure and can play a role of catalyzing the ring opening of an epoxy group, the tanning time of the composition can be greatly reduced, the existence of the glycidyl ether chain segment can endow the epoxy resin composition tanning agent with certain self-emulsifying property, and the Y component can endow the composition with emulsibility, so that the emulsifying effect is better, and the permeation of the epoxy resin composition tanning agent among leather fibers is promoted.
(4) The method of the invention adopts the organic amine to be cooperated with the tanning agent of the epoxy resin composition to tan the sheepskin, so that the method is not only suitable for directly tanning the sheepskin after the conventional softening, omits the pickling process, shortens the tanning time to be less than 10h (generally 3-5 days), but also reduces the neutral salt pollution generated by the pickling process, is also suitable for tanning the sheepskin which requires the conventional pickling and the deacidification treatment, and has wider application range.
(5) According to the method adopted by the invention, the pH value is adjusted to 5.5-6.0 after tanning is finished, the tertiary amine structure contained in the X component in the tanning agent of the epoxy resin composition generates quaternary ammonium salt under an acidic condition, and the quaternary ammonium salt has a good antibacterial effect on leather, so that the storage period of the tanned leather at room temperature is longer than 6 months, and the shrinkage temperature is not changed and the mildew phenomenon is not seen.
(6) The process provided by the method of the invention is adopted to tanne the sheepskin, and the tanned sheepskin has clear grain surface, plump and pure white color and excellent yellowing resistance.
Detailed Description
The present invention will be described in detail with reference to specific embodiments. It should be noted that the following examples are not to be construed as limiting the scope of the present invention, and that the skilled person in this field could make modifications and variations of the present invention without departing from the spirit or essential attributes thereof.
It is worth to be noted that 1) the concentrations of the materials used in the following examples are mass percent concentrations; 2) the epoxy value of the epoxy resin X in the composition obtained in the following examples was measured by the acetone hydrochloride method and was the number of moles of epoxy groups contained in 100g of the product; the viscosity was measured at 25 ℃ by the rotational viscosity method.
Example 1
In this example, the sheepskin after being delimed and softened conventionally is put into a rotary drum for tanning:
firstly, performing rotation treatment at 35 ℃ for 60min in melamine bath liquid with the liquid ratio of 80% and the concentration of 1.0%, then adding an epoxy resin composition tanning agent with the concentration of 10%, rotating at 40 ℃ for 1h, rotating at 50 ℃ for 8h, replenishing water, standing overnight, rotating at least 30min the next day, then sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (the mass ratio of acetic acid to water is 1: 10), rotating for at least 30min, and performing subsequent process treatment after going out of the drum and building a horse according to the conventional method.
The tanning agent of the epoxy resin composition consists of epoxy resin X and epoxy resin Y in a mass ratio of 5:1, wherein the epoxy resin Y contains glycerol triglycidyl ether and ethylene glycol diglycidyl ether in a mass ratio of 2:1, and the epoxy resin X is prepared by the following method:
adding 17g (0.1mol) of isophorone diamine into a normal-temperature water bath, dropwise adding 37g (0.4mol) of epichlorohydrin at the speed of 20 drops/min while stirring, carrying out constant-temperature reaction for 4h at the condition of 25 ℃ water bath, then sequentially adding 36.8g (0.4mol) of glycerol and 0.32g of boron trifluoride diethyl etherate, dropwise adding 111g (1.2mol) of epichlorohydrin at the speed of 50 drops/min, heating to 50 ℃ after dropwise adding, carrying out constant-temperature reaction for 5h, dropwise adding 160g (1.6mol) of sodium hydroxide solution (with the concentration of 40%) when cooling to 45 ℃, continuing to carry out constant-temperature reaction for 2h, and finally adding a mixture of potassium dihydrogen phosphate (with the concentration of 20%) and acetic acid (with the mass ratio of 1:1 to neutralize the product until the pH value is neutral. And (3) carrying out rotary distillation on the upper-layer product, evaporating unreacted epoxy chloropropane and residual water, and filtering to obtain the epoxy resin X. The product had an epoxy value of 0.5596 and a viscosity of 324mPa ≤.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 83.4 ℃, the leather is plump, the thickening rate is 48.79%, and the mildew resistance grade is 1 according to a QB/T4199-2011 test.
Example 2
In the embodiment, the sheepskin after conventional deliming and softening (degreasing is carried out simultaneously in the softening process, and the pH value is adjusted to 7.5-8.0 by baking soda) and pickling is put into a rotary drum for tanning:
firstly, rotating and treating for 30min at 40 ℃ in dicyandiamide bath liquid with the liquid ratio of 90% and the concentration of 0.5%, then adding epoxy resin composition tanning agent with the concentration of 6%, rotating for 2h at 38 ℃, rotating for 10h at 45 ℃, replenishing water, standing overnight, rotating for at least 30min the next day, then sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0 by using formic acid solution (the mass ratio of formic acid to water is 1: 10), rotating for at least 30min, taking out of the drum and building a horse, and then carrying out subsequent process treatment according to the convention.
The tanning agent of the epoxy resin composition consists of an epoxy resin X and an epoxy resin Y in a mass ratio of 0.5:1, wherein the epoxy resin Y contains glycerol triglycidyl ether and polyethylene glycol (average molecular weight is 400) diglycidyl ether in a mass ratio of 3:1, and the epoxy resin X is prepared by the following method:
adding 17g (0.1mol) of isophorone diamine into a water bath at normal temperature, dropwise adding 37g (0.4mol) of epichlorohydrin while stirring at a speed of 25 drops/min, carrying out constant-temperature reaction for 2h at a water bath condition of 30 ℃, then sequentially adding 160g (0.4mol) of polyethylene glycol (average molecular weight is 400) and 0.71g of boron trifluoride diethyl etherate, dropwise adding 74g (0.8mol) of epichlorohydrin at a speed of 60 drops/min, heating to 60 ℃ after the dropwise adding is finished, carrying out constant-temperature reaction for 4h, cooling to 30 ℃, dropwise adding 120g (1.2mol) of sodium hydroxide solution (concentration is 40%), continuing to carry out constant-temperature reaction for 3h, and finally adding a mixture of potassium dihydrogen phosphate (concentration is 20%) solution and acetic acid (concentration is 50%) in a mass ratio of 2:1 to neutralize the product until the pH value is neutral. And (4) carrying out rotary distillation on the upper-layer product, evaporating unreacted epoxy chloropropane and residual water, and filtering to obtain the component X. The product had an epoxy value of 0.4746 and a viscosity of 305mPa ≤.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 81.0 ℃, the leather is plump, the thickening rate is 51.04%, and the mildew resistance grade is 1 according to a QB/T4199-2011 test.
Example 3
In this example, the sheepskin after being delimed and softened conventionally is put into a rotary drum for tanning:
firstly, carrying out rotation treatment for 50min at 30 ℃ in a bath liquid of amino resin (melamine and formaldehyde polymer with the molar ratio of melamine to formaldehyde being 1:5) with the liquid ratio of 80% and the concentration of 0.8%, then adding an epoxy resin composition tanning agent with the concentration of 12%, rotating for 1h at 35 ℃, rotating for 10h at 48 ℃, replenishing water, standing overnight, rotating for at least 30min the next day, then sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (the mass ratio of acetic acid to water is 1: 10), rotating for at least 30min, and carrying out subsequent process treatment according to the conventional method.
The tanning agent of the epoxy resin composition consists of epoxy resin X and epoxy resin Y in a mass ratio of 4:1, wherein the epoxy resin Y contains glycerol triglycidyl ether, ethylene glycol diglycidyl ether and 1, 4-butanediol diglycidyl ether in a mass ratio of 1:1:1, and the epoxy resin X is prepared by the following method:
adding 17g (0.1mol) of isophorone diamine into a water bath at normal temperature, dropwise adding 46.2g (0.5mol) of epichlorohydrin at the speed of 20 drops/min while stirring, carrying out constant-temperature reaction for 3h at the temperature of 30 ℃ in the water bath, then sequentially adding 27.6g (0.3mol) of glycerol and 0.45g of tetrabutylammonium bromide, dropwise adding 92.52g (1.0mol) of epichlorohydrin at the speed of 60 drops/min, heating to 55 ℃ after the dropwise addition is finished, carrying out constant-temperature reaction for 4h, then cooling to 25 ℃, dropwise adding 151g (1.35mol) of potassium hydroxide solution (with the concentration of 50%), continuing to carry out constant-temperature reaction for 4h, and finally adding a mixture of sodium dihydrogen phosphate (with the concentration of 20%) and acetic acid (with the mass ratio of 5:1 to neutralize the product until the pH value is neutral. And (4) carrying out rotary distillation on the upper-layer product, evaporating unreacted epoxy chloropropane and residual water, and filtering to obtain the component X. The product had an epoxy value of 0.5673 and a viscosity of 309mPa ≤.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 85.3 ℃, the leather is plump, the thickening rate is 62.4 percent, and the mildew resistance grade is 1 grade according to a QB/T4199-2011 test.
Example 4
In this example, the skins, which are subjected to conventional deliming and softening (degreasing simultaneously in the softening step, and adjusting the pH to 7.5-8.0 with baking soda), are tanned in a drum:
firstly, performing rotation treatment at 35 ℃ for 40min in a melamine bath solution with the liquid ratio of 100% and the concentration of 1.2%, then adding an epoxy resin composition tanning agent with the concentration of 8%, rotating at 40 ℃ for 1.5h, rotating at 50 ℃ for 6h, replenishing water, standing overnight, rotating for at least 30min the next day, then sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (the mass ratio of acetic acid to water is 1: 10), rotating for at least 30min, and taking out of the drum and building a horse to perform subsequent process treatment according to the convention.
The tanning agent of the epoxy resin composition consists of epoxy resin X and epoxy resin Y in a mass ratio of 3:1, wherein the epoxy resin Y contains glycerol triglycidyl ether and diethylene glycol diglycidyl ether in a mass ratio of 2:1, and the epoxy resin X is prepared by the following method:
adding 17g (0.1mol) of isophorone diamine into a water bath at normal temperature, dropwise adding 55.5g (0.6mol) of epichlorohydrin while stirring at a speed of 25 drops/min, carrying out constant-temperature reaction for 3h at a temperature of 35 ℃ in the water bath, then sequentially adding 31g (0.5mol) of ethylene glycol and 0.29g of boron trifluoride diethyl etherate, dropwise adding 185g (2.0mol) of epichlorohydrin at a speed of 40 drops/min, heating to 60 ℃ after the dropwise addition, carrying out constant-temperature reaction for 4h, cooling to 30 ℃, dropwise adding 140g (1.4mol) of sodium hydroxide solution (with the concentration of 40%), continuing to carry out constant-temperature reaction for 2h, and finally adding a mixture of potassium dihydrogen phosphate (with the concentration of 25%) solution and acetic acid (with the mass ratio of 0.5:1 to neutralize the product until the pH value is neutral. And (4) carrying out rotary distillation on the upper-layer product, evaporating unreacted epoxy chloropropane and residual water, and filtering to obtain the component X. The product had an epoxy value of 0.5017 and a viscosity of 533mPa ≤.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 84.0 ℃, the leather is plump, the thickening rate is 52.9 percent, and the mildew resistance grade is 1 grade according to a QB/T4199-2011 test.
Example 5
In this example, the skins, which are subjected to conventional deliming and softening (degreasing simultaneously in the softening step, and adjusting the pH to 7.5-8.0 with baking soda), are tanned in a drum:
firstly, rotating a commercially available amino resin retanning agent bath solution with the liquid ratio of 80% and the concentration of 0.5% for 60min at 25 ℃, then adding an epoxy resin composition tanning agent with the concentration of 10%, rotating for 2h at 35 ℃, rotating for 8h at 45 ℃, replenishing water, standing overnight, rotating for at least 30min the next day, then sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0 by using a formic acid solution (the formic acid: the water is 1:10 (mass ratio)), rotating for at least 30min, and taking out of the drum and building a horse to carry out subsequent process treatment according to the conventional method.
The tanning agent of the epoxy resin composition consists of epoxy resin X and epoxy resin Y in a mass ratio of 2:1, wherein the epoxy resin Y contains glycerol triglycidyl ether, polyethylene glycol diglycidyl ether (the average molecular weight of polyethylene glycol is 300) and ethylene glycol diglycidyl ether in a mass ratio of 1:1:0.5, and the epoxy resin X is prepared by the following method:
adding 17g (0.1mol) of isophorone diamine into a water bath at normal temperature, dropwise adding 46.3g (0.5mol) of epichlorohydrin at the speed of 20 drops/min while stirring, reacting for 3 hours at the constant temperature of 35 ℃ in the water bath, then sequentially adding 9.0g (0.1mol) of 1, 4-butanediol and 0.21g N, N-dimethylaniline, dropwise adding 37g (0.4mol) of epichlorohydrin at the speed of 30 drops/min, heating to 70 ℃ after the dropwise addition is finished, reacting for 3 hours at the constant temperature, cooling to 20 ℃, dropwise adding 80.8g (0.72mol) of potassium hydroxide solution (the concentration is 50 percent), continuing to react for 4 hours at the constant temperature, and finally adding a mixture of sodium dihydrogen phosphate (the concentration is 15 percent) solution and acetic acid (the concentration is 100 percent) in the mass ratio of 5:1 to neutralize the product until the pH value is neutral. And (4) carrying out rotary distillation on the upper-layer product, evaporating unreacted epoxy chloropropane and residual water, and filtering to obtain the component X. The product had an epoxy value of 0.5945 and a viscosity of 840mPa ≤.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 83.2 ℃, the leather is plump, the thickening rate is 64.76%, and the mildew resistance grade is 1 according to a QB/T4199-2011 test.
TABLE 1 corresponding average molecular weights and molecular weight distributions for the products of the examples
Comparative example 1
In the comparative example, the sheepskin which is subjected to conventional deliming and softening (degreasing is carried out simultaneously in the softening process, and the pH value is adjusted to 7.5-8.0 by using baking soda) is put into a rotary drum for tanning:
rotating the solution in a glycerol triglycidyl ether bath lotion with the liquid ratio of 80% and the concentration of 10% for 1h at 45 ℃, rotating the solution for 6h at 50 ℃, replenishing water, standing overnight, rotating the solution for at least 30min the next day, then sequentially controlling water and washing the solution, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (the mass ratio of acetic acid to water is 1: 10), rotating the solution for at least 30min, and taking the solution out of a drum and carrying out subsequent process treatment according to the convention.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 73.2 ℃, and the thickening rate is 18.92%.
Comparative example 2
In the comparative example, the sheepskin which is subjected to conventional deliming and softening (degreasing is carried out simultaneously in the softening process, and the pH value is adjusted to 7.5-8.0 by using baking soda) is put into a rotary drum for tanning:
rotating the epoxy resin X bath lotion with the liquid ratio of 80% and the concentration of 10% for 1h at 40 ℃, rotating the epoxy resin X bath lotion for 6h at 48 ℃, replenishing water, standing overnight, rotating for at least 30min the next day, then sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (the mass ratio of acetic acid to water is 1: 10), and taking the system out of the drum and setting up the same, thus carrying out subsequent process treatment according to the convention.
Wherein the epoxy resin X used is prepared by the following method:
adding 17g (0.1mol) of isophorone diamine into a water bath at normal temperature, dropwise adding 37g (0.4mol) of epichlorohydrin while stirring at a speed of 25 drops/min, carrying out constant-temperature reaction for 4h under a water bath condition at 25 ℃, then sequentially adding 18.4g (0.2mol) of glycerol, 18g (0.2mol) of 1, 4-butanediol and 0.37g of boron trifluoride diethyl ether, dropwise adding 111g (1.2mol) of epichlorohydrin at a speed of 60 drops/min, heating to 50 ℃ after dropwise adding, carrying out constant-temperature reaction for 8h, then cooling to 45 ℃, dropwise adding 160g (1.6mol) of sodium hydroxide solution (with the concentration of 40%), continuing constant-temperature reaction for 2h, and finally adding a mixture of potassium dihydrogen phosphate (with the concentration of 20%) and acetic acid (with the mass ratio of 1:1 to neutralize the product until the pH value is neutral. And (3) carrying out rotary distillation on the upper-layer product, evaporating unreacted epoxy chloropropane and residual water, and filtering to obtain the component X. The tanning agent had an epoxy value of 0.5606 and a viscosity of 315mPa ≤.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 78.4 ℃, and the thickening rate is 33.32%.
Comparative example 3
In the comparative example, the sheepskin which is subjected to conventional deliming and softening (degreasing is carried out simultaneously in the softening process, and the pH value is adjusted to 7.5-8.0 by using baking soda) is put into a rotary drum for tanning:
rotating in a polyethylene glycol diglycidyl ether (polyethylene glycol average molecular weight is 400) bath liquid with the liquid ratio of 100% and the concentration of 10% for 1h at 40 ℃, rotating for 6h at 50 ℃, replenishing water, standing overnight, rotating for at least 30min the next day, then sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (acetic acid: water is 1:10 (mass ratio)), rotating for at least 30min, and taking out of the drum and the horse, thus carrying out subsequent process treatment according to the convention.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 70.2 ℃, and the thickening rate is 33.40%.
Comparative example 4
In the comparative example, the sheepskin which is subjected to conventional deliming and softening (degreasing is carried out simultaneously in the softening process, and the pH value is adjusted to 7.5-8.0 by using baking soda) is put into a rotary drum for tanning:
rotating the mixture in an ethylene glycol diglycidyl ether bath solution with the liquid ratio of 80% and the concentration of 10% for 1h at 40 ℃, rotating the mixture for 6h at 50 ℃, replenishing water, standing overnight, rotating the mixture for at least 30min the next day, then sequentially controlling water and washing the mixture, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (the mass ratio of acetic acid to water is 1: 10), and taking the mixture out of a drum and setting up the mixture, thus carrying out subsequent process treatment according to the convention.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 69.5 ℃, and the thickening rate is 10.29%.
Comparative example 5
In the comparative example, the sheepskin which is subjected to conventional deliming and softening (degreasing is carried out simultaneously in the softening process, and the pH value is adjusted to 7.5-8.0 by using baking soda) is put into a rotary drum for tanning:
rotating the solution in a glycerol triglycidyl ether bath lotion with the liquid ratio of 80% and the concentration of 10% for 1h at 45 ℃, rotating the solution for 6h at 50 ℃, replenishing water, standing overnight, rotating the solution for at least 30min the next day, then sequentially controlling water and washing the solution, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (the mass ratio of acetic acid to water is 1: 10), rotating the solution for at least 30min, and taking the solution out of a drum and setting up the solution, thus the subsequent process treatment can be carried out according to the conventional method.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 73.2 ℃, and the thickening rate is 18.92%.
Otherwise the procedure was as in comparative example 1
Rotating the epoxy resin composition tanning agent bath liquid with the liquid ratio of 80% and the concentration of 10% for 1h at 40 ℃, rotating the epoxy resin composition tanning agent bath liquid for 8h at 50 ℃, replenishing water, standing overnight, rotating for at least 30min the next day, then sequentially controlling water and washing, adjusting the pH value of the system to 5.5-6.0 by using an acetic acid solution (the mass ratio of acetic acid to water is 1: 10), rotating for at least 30min, and taking out of the drum and setting up the drum, thus the subsequent process treatment can be carried out according to the convention.
The tanning agent of the epoxy resin composition is still composed of an epoxy resin X and an epoxy resin Y with the mass ratio of 5:1, and the epoxy resin X and the epoxy resin Y are the same as those in the embodiment 1 and are not the same.
The shrinkage temperature Ts of the obtained sheepskin finished leather is 79.5 ℃, and the thickening rate is 30.82%.
According to comparative examples 1 to 5, the leather obtained by using the X component, glycerol triglycidyl ether, polyethylene glycol diglycidyl ether (polyethylene glycol average molecular weight is 400), ethylene glycol diglycidyl ether and even the epoxy resin composition as the tanning agent is general in body fullness, and the shrinkage temperature and the thickening rate are lower than those of the leather tanned by the composition tanning agent; when the organic amine is used for synergistic tanning, the shrinkage temperature and the thickening rate of the tanned leather are improved to a certain extent on the basis of finished leather tanned by the composite tanning agent alone. That is, the leather is tanned by the tanning agent in the invention, and the white wet leather performance is obviously better than that of the leather which is tanned by one tanning agent.