Multifunctional polycarboxylic acid retanning fatliquor and preparation method thereof

Abstract

The invention provides a multifunctional polycarboxylic acid retanning fatliquor and a preparation method thereof, and belongs to the field of leather auxiliaries. The preparation method of the multifunctional polycarboxylic acid retanning fatliquor comprises the following steps: heating and refluxing itaconic acid and carboxylic acid long carbon chain ester containing vinyl as monomers in a low-carbon alcohol solvent environment in the presence of an initiator to carry out free radical copolymerization, mixing with deionized water, neutralizing, and distilling to remove the solvent, thereby obtaining the multifunctional polycarboxylic acid retanning fatliquor. According to the multifunctional polycarboxylic acid retanning fatliquor and the preparation method thereof, the defects of an existing chromium salt retanning agent and an existing acrylic resin tanning agent can be effectively overcome, the raw materials are renewable resources and easy to obtain, and the retanning agent is easy to biodegrade and high in environmental friendliness; meanwhile, the leather retanning and fat liquoring functions are achieved, the production period can be effectively shortened, the production efficiency is improved, the production energy consumption is reduced, and the leather retanning and fat liquoring effects are good.

Description

Technical Field

[0001] The invention relates to the field of leather auxiliaries, in particular to a multifunctional polycarboxylic acid retanning fatliquor and a preparation method thereof. Background Art

[0002] There are many processes in the leather production process, among which retanning is an extremely important process in the leather production process. Retanning can not only enhance the tanning effect, but also improve the properties of leather in many aspects, greatly increasing the value of leather. Therefore, retanning is called the "alchemy" in leather production [Lv Bin, Jia Lu, Ma Jianzhong, et al., Research Progress of Retanning Agents with Darkening Effect, China Leather, 2014, 43 (21): 45-47; Chao W, Zeng Y, Liao X, et al; Effect of retanning agent on dry heat resistance of leathers. The Journal of the American Leather Chemists Association, 2013, 108 (8): 294-299]. The effect of retanning mainly depends on the retanning agent.

[0003] Retanning agents are materials that can react with collagen or leather to produce a tanning effect. Currently used retanning agents can be divided into two categories: inorganic metal salt retanning agents, mainly chromium salts, followed by aluminum salts, zirconium salts, etc.; organic retanning agents, mainly vegetable tanning agents, aldehyde tanning agents and polymer tanning agents. Chromium salts are the main tanning agents commonly used in the prior art. Although they have good tanning effects, they have a series of environmental and health risk issues. Specifically, after the chromium-containing waste produced by chromium salt tanning is landfilled, chromium will be deposited in the soil, polluting the soil and water sources; at the same time, Cr (Ш) is easily oxidized to Cr (VI), which can induce mutations in organisms, directly damage human skin, and accumulate in internal organs, inducing various diseases and cancers [Qiang TT, Chen L, Zhang Q, et al. A sustainable and cleaner speedy tanning system based on condensed tannins catalyzed by laccase, Journal of Cleaner Production, 2018, 197 (1): 1117-1123]. Therefore, the policies and regulations of developed countries and regions in the world strictly limit the amount of Cr (VI) in leather products [Gu Cuiping, Polymer metal chromium complex leather tanning agent and its preparation method, Anhui University thesis, 2005]. In addition, chromium resources are very limited and unevenly distributed around the world. my country's chromium resources are relatively scarce, and chromium reserves account for only 0.3% of the world's total. Therefore, how to avoid or reduce the use of chromium salt retanning agents, reduce the pollution caused by chromium emissions, and achieve clean tanning is an important direction for the sustainable development of the leather industry. Finding clean and green chrome-free retanning agents to replace chrome retanning agents has become a research hotspot in the leather industry [Yuan Xuzheng, Li Yan, Lu Vina, Comparative study on the retanning properties of common aldehyde and derivative tanning agents, Leather and Chemical Industry, 2015, 32 (5): 19-22; Sundar VJ, Rao JR, Muralidharan C, Cleaner chrome tanning-emerging options, Journal of Cleaner Production, 2002, 10 (1): 69-74].

[0004] Organic retanning agents have fewer environmental and safety issues, meet the requirements of sustainable development, and are the main development direction of chrome-free tanning agents. Existing acrylic polymer retanning agents are the most important organic retanning agents, which have good selective filling and thickening properties, can improve the flexibility and fullness of finished leather, and improve the physical properties of leather. The retanned leather has the advantages of light resistance, aging resistance, and good napping properties. Moreover, there are many types of copolymerizable monomers, and different copolymerizable monomers can be used to produce retanning agents with various properties, thereby meeting the needs of leathers of different styles. In addition. Acrylic polymer tanning agents can also effectively promote the fixation and absorption of chromium ions, and the waste liquid after tanning is less toxic and easy to handle. Therefore, acrylic polymer tanning agents are currently one of the most popular organic retanning agent varieties. Since its introduction, it has not only been one of the research hotspots of leather chemists, but also one of the "magic weapons" of leather engineers. Leather expert PS Venkatachulan called it a "miracle retanning agent". It is a type of retanning agent widely used in leather processing [Zhang Biao, Jin Yong, Cao Zhifeng, Research progress on the retanning mechanism and modification of acrylic resin retanning agents, Western Leather, 2010, 32 (11): 32-37; Bao Yan, Ma Jianzhong, Application and research progress of acrylic polymer tanning agents, China Leather, 2011, 40 (15): 51-55].

[0005] Despite this, acrylic resin tanning agents also have the following problems: acrylic resin tanning agents are high molecular polymer tanning agents made by free radical copolymerization of (meth) acrylic acid as the main component and other vinyl monomers. (Meth) acrylic acid and other monomers are deep-processed products of non-renewable petroleum resources. During the processing and post-processing process, more carbon dioxide emissions will occur, which is not in line with the current "double carbon" emission reduction trend; and when petroleum resources are exhausted, acrylic resin retanning agents will face the problem of raw material shortage. Furthermore, existing acrylic resin retanning agents are difficult to biodegrade, and will continue to accumulate when discharged into the environment, causing persistent pollution to the ecological environment; and acrylic resin retanning agents also have certain toxicity, especially irritation, and also pose certain hazards to human health.

[0006] Furthermore, the functions of traditional retanning agents are relatively single, and in the leather tanning process, a variety of tanning agents and auxiliaries are generally used in combination, which directly leads to the cumbersome tanning process, long processing cycle, and serious energy waste. Therefore, multifunctionalization (such as having waterproofing, retanning and fatliquoring functions at the same time) is one of the development directions of existing retanning agents, especially combining the two processes of retanning and fatliquoring into one, which can effectively shorten the production cycle, improve production efficiency and reduce production energy consumption. However, there are not many retanning and fatliquoring agents that can be successfully applied in industry, and biodegradable multifunctional retanning and fatliquoring agents have not been reported. Summary of the invention

[0007] In order to solve the technical problems existing in the prior art, the present invention provides a multifunctional polycarboxylic acid retanning and fatliquoring agent and a preparation method thereof, which can effectively avoid the defects of the existing chromium salt retanning agent and acrylic resin tanning agent, the raw materials are renewable resources that are easy to obtain, the retanning agent is easy to biodegrade, and is highly environmentally friendly; at the same time, it has the functions of retanning and fatliquoring, can effectively shorten the production cycle, improve production efficiency and reduce production energy consumption, and has a good retanning and fatliquoring effect on leather.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: A preparation method of a multifunctional polycarboxylic acid retanning and fat-liquoring agent comprises the following steps: adding a first portion of a low-carbon alcohol solvent into a reaction kettle, stirring and heating to reflux, and keeping the temperature; subsequently adding an initiator and a low-carbon alcohol mixed solution of a vinyl-containing carboxylic acid long-chain ester, and adding powdered itaconic acid in multiple batches; controlling the adding time of the initiator and the low-carbon alcohol mixed solution of the vinyl-containing carboxylic acid long-chain ester to be 2.5-4 hours; continuing to keep the temperature and reflux for 4-5 hours after the addition is completed, adding deionized water, and adjusting the pH value to 7-8 with a sodium hydroxide solution; removing the solvent by atmospheric distillation, and stopping the distillation when the gas phase temperature reaches 100°C, thereby preparing a multifunctional polycarboxylic acid retanning and fat-liquoring agent; The mixed solution of the initiator and the low-carbon alcohol containing vinyl long-chain carboxylic acid ester is a mixed solution in which the initiator and the long-carbon alcohol containing vinyl long-chain carboxylic acid ester are simultaneously dissolved in a second portion of low-carbon alcohol solvent.

[0009] Furthermore, the vinyl-containing long-chain carboxylic acid ester is one of the following: lauryl acrylate, hexadecanol acrylate, octadecyl acrylate, lauryl methacrylate, hexadecanol methacrylate, octadecyl methacrylate, lauryl maleate, hexadecanol maleate, octadecyl maleate, lauryl itaconate, hexadecanol itaconate, and octadecyl itaconate.

[0010] Furthermore, the low-carbon alcohol solvent is at least one of the following: isopropanol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether.

[0011] Preferably, the weight of the first portion of the low-carbon alcohol solvent is 40-60% of the total weight of all the low-carbon alcohol solvents; the second portion of the low-carbon alcohol solvent is the remaining weight of the low-carbon alcohol solvent.

[0012] Preferably, the mass ratio of itaconic acid, vinyl-containing long-chain carboxylic acid ester and all low-carbon alcohol solvents is 1:1-2.2:1.5-6.5.

[0013] Preferably, the initiator is an azo initiator or a peroxide initiator; The added weight of the initiator is 0.5-10% of the total weight of itaconic acid and the vinyl-containing long-chain carboxylic acid ester.

[0014] Preferably, the added weight of the deionized water is 150-250% of the total weight of itaconic acid and vinyl-containing long-chain carboxylic acid ester.

[0015] Preferably, the powdered itaconic acid is added in multiple batches, and the time interval between the addition of adjacent batches of powdered itaconic acid does not exceed 5 minutes.

[0016] Preferably, the mass concentration of the sodium hydroxide solution is 10-50wt%.

[0017] A multifunctional polycarboxylic acid retanning fatliquor is prepared by adopting the above-mentioned preparation method.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method of the multifunctional polycarboxylic acid retanning and fatliquor of the present invention uses itaconic acid monomer as raw material, which is obtained by chemical method, microbial fermentation method or whole cell catalysis method with biomass raw material as substrate, and is a renewable chemical raw material that is easy to obtain; and the carbon dioxide emission in the preparation process using itaconic acid monomer is extremely low, which is in line with the "double carbon" emission reduction trend; at the same time, a vinyl-containing carboxylic acid long carbon chain ester is used as a monomer, and a multifunctional polycarboxylic acid retanning and fatliquor is obtained through free radical copolymerization; the multifunctional polycarboxylic acid retanning and fatliquor can effectively avoid the defects of existing chromium salt retanning agents and acrylic resin tanning agents, and is easy to biodegrade. After use, it will not accumulate in the environment and will not cause persistent pollution to the environment. In addition, the raw material monomers selected by the present invention have high activity, the polymerization process is easy to control, and the preparation process is simple, safe and efficient. At the same time, the multifunctional polycarboxylic acid retanning fatliquor of the present invention has low toxicity, low irritation, and little harm to human health.

[0019] (2) The multifunctional polycarboxylic acid retanning and fatliquoring agent of the present invention has both retanning and fatliquoring functions, and can perform both retanning and fatliquoring treatments on leather at the same time, which can effectively shorten the production cycle, improve production efficiency and reduce production energy consumption; the multifunctional polycarboxylic acid retanning and fatliquoring agent has good filling, retanning and fatliquoring effects on leather, has good permeability to leather and is easy to absorb, and the obtained leather has low odor, high yellowing resistance and good waterproof function. DETAILED DESCRIPTION

[0020] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] The embodiment of the present invention provides a method for preparing a multifunctional polycarboxylic acid retanning and fatliquor. Itaconic acid and a vinyl-containing carboxylic acid long-chain ester are used as monomers. In the presence of an initiator, the monomers are heated under reflux for free radical copolymerization in a low-carbon alcohol solvent environment. The monomers are then mixed with deionized water, neutralized with a sodium hydroxide solution, and the solvent is removed by distillation to prepare the multifunctional polycarboxylic acid retanning and fatliquor. The preparation method of the multifunctional polycarboxylic acid retanning fatliquor, the synthesis route is as follows:

[0023] ; Among them, R 1 For - (CH 2 ) n CH 3 , where n is one of the following: 11, 15, or 17; R 2 H or -CH 3 .

[0024] Specifically, the preparation method of the multifunctional polycarboxylic acid retanning fatliquor comprises the following steps: (1) Raw material preparation: weigh itaconic acid, vinyl-containing long-chain carboxylic acid ester, initiator, and low-carbon alcohol solvent; divide the low-carbon alcohol solvent into two parts to obtain a first part of low-carbon alcohol solvent and a second part of low-carbon alcohol solvent. The weight of the first part of low-carbon alcohol solvent is 40-60% of the total weight of the low-carbon alcohol solvent; the second part of low-carbon alcohol solvent is the remaining weight of the low-carbon alcohol solvent.

[0025] The vinyl-containing long carbon chain carboxylic acid ester is one of the following: lauryl acrylate, hexadecanol acrylate, octadecyl acrylate, lauryl methacrylate, hexadecanol methacrylate, octadecyl methacrylate, lauryl maleate, hexadecanol maleate, octadecyl maleate, lauryl itaconate, hexadecanol itaconate, octadecyl itaconate; preferably lauryl acrylate or lauryl methacrylate.

[0026] The low-carbon alcohol solvent is at least one of the following: isopropanol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether; preferably isopropanol, or a mixture of isopropanol and ethylene glycol monobutyl ether.

[0027] The initiator is an azo initiator or a peroxide initiator; preferably an azo initiator; more preferably azobisisobutyronitrile.

[0028] (2) Synthesis of retanning fatliquor: Add the first portion of low-carbon alcohol solvent to the reactor, heat to reflux state and then keep warm; then add the initiator and the low-carbon alcohol mixed solution of long-carbon chain ester of vinyl carboxylic acid; while adding the mixed solution, add powdered itaconic acid in multiple batches, and control the addition time of the mixed solution to be 2.5-4 hours; after all materials are added, keep the reflux state and continue the reaction for 4-5 hours; then add deionized water, and use sodium hydroxide solution to neutralize the pH to 7-8; remove the solvent by atmospheric distillation, and stop distilling when the gas phase temperature reaches 100°C to obtain a multifunctional polycarboxylic acid retanning fatliquor.

[0029] In the step (2), the mixed solution of the initiator and the vinyl-containing long-chain carboxylic acid ester in low-carbon alcohol is a mixed solution in which the initiator and the vinyl-containing long-chain carboxylic acid ester are simultaneously dissolved in the second portion of low-carbon alcohol solvent (the remaining weight of the low-carbon alcohol solvent).

[0030] In the step (2), the mass ratio of itaconic acid, vinyl-containing carboxylic acid long-chain ester, and low-carbon alcohol solvent is 1:1-2.2:1.5-6.5; preferably 1:1.5-1.8:3.5-5.5.

[0031] In the step (2), the added weight of the initiator is 0.5-10% of the total weight of itaconic acid and the vinyl-containing long-chain carboxylic acid ester; preferably 1-3%.

[0032] In the step (2), the weight of the added deionized water is 150-250% of the total weight of itaconic acid and the vinyl-containing long-chain carboxylic acid ester.

[0033] In the step (2), the powdered itaconic acid is added in multiple batches, and the time interval between the addition of adjacent batches of powdered itaconic acid does not exceed 5 minutes.

[0034] In the step (2), the temperature of the reaction mixture heated to reflux is preferably 80-85°C.

[0035] In step (2), the mass concentration of the sodium hydroxide solution is 10-50wt%, preferably 25-35wt%.

[0036] The embodiment of the present invention also provides a multifunctional polycarboxylic acid retanning fatliquor prepared by the above method.

[0037] The present invention is further described below in conjunction with some specific embodiments.

[0038] In each embodiment and related measurement, itaconic acid used is an industrial product, which is a product of Qingdao Kehai Biological Group Co., Ltd. of Qingdao Langyatai Group; azobisisobutyronitrile is an industrial product, which is a product of Jinan Quansheng Chemical Co., Ltd.; dodecanol acrylate and dodecanol methacrylate are industrial products, which are products of Shandong Suihua Biotechnology Co., Ltd.; isopropanol is an industrial product, which is a product of Shandong Taixi Chemical Co., Ltd.; ethylene glycol monobutyl ether is an industrial product, which is a product of Shandong Xuxiang Chemical Co., Ltd.; the raw cowhide and comparison retanning agent used are provided by Shandong Lining Science and Technology New Materials Co., Ltd.; MF-1 is a multifunctional self-lubricating polymer filled retanning agent used by Sichuan Dawe Technology Co., Ltd., which is used as a comparison sample for the performance evaluation of the products in each embodiment of the present invention. DK is a multifunctional auxiliary agent of organic acid condensation products, YS is a synthetic fatliquor of sulfonate derivatives and high molecular weight aliphatic hydrocarbons, KC is a neutralizing and retanning agent of organic acid salts, inorganic salts, polyethylene glycol and polyols. DK, YS and KC are all products of Shandong Lining Technology New Materials Co., Ltd.; AB chromium powder is a chromium powder product of Guangzhou Deli Chemical Co., Ltd.

[0039] In each example, the monomer conversion rate was determined by double bond bromine addition method, referring to [Zhang Zhixian, Zhang Ruihao, Quantitative Analysis of Organic Functional Groups, Chemical Industry Press, 1990].

[0040] The viscosity of the polymer aqueous solution was measured using a NDJ-1 rotary viscometer produced by Shanghai Yueping Scientific Instrument Co., Ltd. The test temperature was 25 °C.

[0041] Molecular weight determination of polymer: water-soluble acrylic resin was used as standard sample and determined by gel permeation chromatography (GPC). The instrument used was American Waters 1515 gel chromatograph.

[0042] Determination of solid content of sample: Accurately weigh 10g of sample into a beaker, put it into an oven, and dry it at 110°C to constant weight. The percentage of dry weight to wet weight of the sample is the solid content of the sample.

[0043] Biodegradability evaluation: Evaluated according to the evaluation criteria in the literature [Han Minghan, Jin Yong, Principles and Applications of Green Engineering [M], Beijing: Tsinghua University Press, 2005.11].

[0044] Example 1 This embodiment provides a method for preparing a multifunctional polycarboxylic acid retanning fatliquor, comprising the following steps: Weigh itaconic acid, dodecanol acrylate, azobisisobutyronitrile, and isopropanol respectively, and divide isopropanol into two parts (i.e., the first part of low-carbon alcohol solvent and the second part of low-carbon alcohol solvent) for standby use; first add 60mL of isopropanol (i.e., the first part of low-carbon alcohol solvent) to a 500mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a feeding device, and heat it to 83°C (micro-reflux state), and then start to add the low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate at a uniform rate, and at the same time, add 26g of itaconic acid powder to the reactor in a multiple feeding manner of adding once every 5min, and control the feeding time of the low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate to be 3h; after the addition is completed, keep the reflux state and continue the reaction for 4h; then add 120mL of deionized water, and use 41.1g The pH value of the product was neutralized to 7.5 with 30wt% sodium hydroxide solution; the solvent was then removed by atmospheric distillation, and the distillation was stopped when the gas phase temperature reached 100°C to obtain a multifunctional polycarboxylic acid retanning fatliquor with a solid content of 32.4wt%, a monomer conversion rate of 99.3%, a weight average molecular weight Mw of 25632, a molecular weight distribution Mw / Mn of 2.47, and a viscosity of a 10wt% product aqueous solution of 55mPa·s.

[0045] The low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate is prepared by dissolving 1.3 g of azobisisobutyronitrile and 40 g of dodecanol acrylate in 60 mL of isopropanol (i.e., the second low-carbon alcohol solvent).

[0046] The test showed that the multifunctional polycarboxylic acid retanning fatliquor of the present embodiment had good biodegradability, and the biodegradation rates after 7 days and 28 days were 22.3wt% and 52.3wt%, respectively.

[0047] This embodiment also provides a multifunctional polycarboxylic acid retanning fatliquor prepared by the aforementioned method.

[0048] Example 2 This embodiment provides a method for preparing a multifunctional polycarboxylic acid retanning fatliquor, comprising the following steps: Weigh itaconic acid, lauryl acrylate, azobisisobutyronitrile, and isopropanol respectively, and divide the isopropanol into two parts (i.e., the first part of low-carbon alcohol solvent and the second part of low-carbon alcohol solvent) for standby use; first add 60mL of isopropanol (i.e., the first part of low-carbon alcohol solvent) to a 500mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a feeding device, and heat it to 85°C (micro-reflux state), and then start to add the low-carbon alcohol mixed solution of azobisisobutyronitrile and lauryl acrylate at a uniform rate, and at the same time, add 26g of itaconic acid powder to the reactor in a multiple feeding manner of adding once every 5min, and control the feeding time of the low-carbon alcohol mixed solution of azobisisobutyronitrile and lauryl acrylate to be 3h; after the addition is completed, keep the reflux state and continue the reaction for 4h; then add 100mL of deionized water, and use 41.1g 30wt% sodium hydroxide solution was neutralized to pH 7.5; then the solvent was removed by atmospheric distillation, and the distillation was stopped when the gas phase temperature reached 100°C to obtain 193.5g of a multifunctional polycarboxylic acid retanning fatliquor with a solid content of 30.9wt%, a monomer conversion rate of 99.1%, a weight average molecular weight Mw of 22316, a molecular weight distribution Mw / Mn of 2.17, and a viscosity of a 10wt% product aqueous solution of 31mPa·s.

[0049] The low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate is prepared by dissolving 1.3 g of azobisisobutyronitrile and 26 g of dodecanol acrylate in 60 mL of isopropanol (i.e., the second low-carbon alcohol solvent).

[0050] The test showed that the multifunctional polycarboxylic acid retanning fatliquor of the present embodiment had excellent biodegradability, and the biodegradation rates after 7 days and 28 days were 22.8 wt % and 53.3 wt %, respectively.

[0051] This embodiment also provides a multifunctional polycarboxylic acid retanning fatliquor prepared by the aforementioned method.

[0052] Example 3 This embodiment provides a method for preparing a multifunctional polycarboxylic acid retanning fatliquor, comprising the following steps: Itaconic acid, lauryl acrylate, azobisisobutyronitrile, and isopropanol were weighed separately, and the isopropanol was divided into two parts (i.e., the first part of low-carbon alcohol solvent and the second part of low-carbon alcohol solvent) for standby use; 60 mL of isopropanol (i.e., the first part of low-carbon alcohol solvent) was first added to a 500 mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a feeding device, and after heating to 80 ° C (micro-reflux state), azobisisobutyronitrile and lauryl acrylate low-carbon alcohol mixed solution were added at a uniform rate, and at the same time, 26 g of itaconic acid powder was added to the reactor in a multiple feeding manner of adding once every 5 minutes, and the feeding time of azobisisobutyronitrile and lauryl acrylate low-carbon alcohol mixed solution was controlled to be 3 hours; after the addition was completed, the reflux state was maintained and the reaction was continued for 4 hours; then 120 mL of deionized water was added, and 41.1 g of 30wt% sodium hydroxide solution was neutralized to pH 7.5; then the solvent was removed by atmospheric distillation, and the distillation was stopped when the gas phase temperature reached 100°C to obtain 272.8g of a multifunctional polycarboxylic acid retanning fatliquor with a solid content of 32.5wt%, a monomer conversion rate of 98.7%, a weight average molecular weight Mw of 28963, a molecular weight distribution Mw / Mn of 2.79, and a viscosity of a 10wt% product aqueous solution of 86mPa·s.

[0053] The low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate is prepared by dissolving 1.3 g of azobisisobutyronitrile and 40 g of dodecanol acrylate in 60 mL of isopropanol (i.e., the second low-carbon alcohol solvent).

[0054] The test showed that the multifunctional polycarboxylic acid retanning fatliquor of the present embodiment had excellent biodegradability, and the biodegradation rates after 7 days and 28 days were 21.3 wt % and 50.3 wt %, respectively.

[0055] This embodiment also provides a multifunctional polycarboxylic acid retanning fatliquor prepared by the aforementioned method.

[0056] Example 4 This embodiment provides a method for preparing a multifunctional polycarboxylic acid retanning fatliquor, comprising the following steps: Itaconic acid, lauryl acrylate, azobisisobutyronitrile, isopropanol, and ethylene glycol monobutyl ether were weighed separately, and isopropanol and ethylene glycol monobutyl ether were mixed in equal volumes and divided into two portions (i.e., the first portion of low-carbon alcohol solvent and the second portion of low-carbon alcohol solvent) for standby use; 30 mL of a mixture of isopropanol and 30 mL of ethylene glycol monobutyl ether (i.e., the first portion of low-carbon alcohol solvent) was first added to a 500 mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a feeding device, and after heating to 85 ° C, a low-carbon alcohol mixed solution of azobisisobutyronitrile and lauryl acrylate was uniformly added at a rate, and at the same time, 26 g of itaconic acid powder was added to the reactor in a multiple feeding manner of adding once every 5 minutes, and the feeding time of the low-carbon alcohol mixed solution of azobisisobutyronitrile and lauryl acrylate was controlled to be 3 hours; after the feeding was completed, the reflux state was maintained and the reaction was continued for 4 hours; then 120 mL of deionized water was added, and 41.1 g of 30wt% sodium hydroxide solution was neutralized to pH 7.5; then the solvent was removed by atmospheric distillation, and the distillation was stopped when the gas phase temperature reached 100°C to obtain 228.1g of a multifunctional polycarboxylic acid retanning and fatliquor agent with a solid content of 32.4wt%, a monomer conversion rate of 99.0%, a weight average molecular weight Mw of 24932, a molecular weight distribution Mw / Mn of 2.45, and a viscosity of a 10wt% product aqueous solution of 42mPa·s.

[0057] The low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate is prepared by dissolving 1.3 g of azobisisobutyronitrile and 40 g of dodecanol acrylate in a mixture of 30 mL of isopropanol and 30 mL of ethylene glycol monobutyl ether (i.e., the second low-carbon alcohol solvent).

[0058] The test showed that the multifunctional polycarboxylic acid retanning fatliquor of the present embodiment had excellent biodegradability, and the biodegradation rates after 7 days and 28 days were 22.1 wt % and 52.0 wt %, respectively.

[0059] This embodiment also provides a multifunctional polycarboxylic acid retanning fatliquor prepared by the aforementioned method.

[0060] Example 5 This embodiment provides a method for preparing a multifunctional polycarboxylic acid retanning fatliquor, comprising the following steps: Weigh itaconic acid, dodecanol acrylate, azobisisobutyronitrile, and isopropanol respectively, and divide isopropanol into two parts (i.e., the first part of low-carbon alcohol solvent and the second part of low-carbon alcohol solvent) for standby use; first add 60mL of isopropanol (i.e., the first part of low-carbon alcohol solvent) to a 500mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a feeding device, and heat it to 83°C (micro-reflux state), and then start to add the low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate at a uniform rate, and at the same time, add 26g of itaconic acid powder to the reactor in a multiple feeding manner of adding once every 5min, and control the feeding time of the low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate to be 3h; after the addition is completed, keep the reflux state and continue the reaction for 4h; then add 120mL of deionized water, and use 41.1g 30wt% sodium hydroxide solution was neutralized to pH 7.5; then the solvent was removed by atmospheric distillation, and the distillation was stopped when the gas phase temperature reached 100°C to obtain 226.9g of a multifunctional polycarboxylic acid retanning fatliquor with a solid content of 32.1wt%, a monomer conversion rate of 98.4%, a weight average molecular weight Mw of 29863, a molecular weight distribution Mw / Mn of 2.82, and a viscosity of a 10wt% product aqueous solution of 92mPa·s.

[0061] The low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate is prepared by dissolving 0.5 g of azobisisobutyronitrile and 40 g of dodecanol acrylate in 60 mL of isopropanol (i.e., the second low-carbon alcohol solvent).

[0062] The test showed that the multifunctional polycarboxylic acid retanning fatliquor of the present embodiment had excellent biodegradability, and the biodegradation rates after 7 days and 28 days were 21.6 wt % and 51.4 wt %, respectively.

[0063] This embodiment also provides a multifunctional polycarboxylic acid retanning fatliquor prepared by the aforementioned method.

[0064] Example 6 This embodiment provides a method for preparing a multifunctional polycarboxylic acid retanning fatliquor, comprising the following steps: Weigh itaconic acid, dodecanol acrylate, azobisisobutyronitrile, and isopropanol respectively, and divide the isopropanol into two parts (i.e., the first part of low-carbon alcohol solvent and the second part of low-carbon alcohol solvent) for standby use; first add 60mL of isopropanol (i.e., the first part of low-carbon alcohol solvent) to a 500mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a feeding device, and heat it to 80-85°C (micro-reflux state), and then start to add the low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate at a uniform rate, and at the same time, add 26g of itaconic acid powder to the reactor in a multiple feeding manner of adding once every 5min, and control the feeding time of the low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate to be 3h; after the feeding is completed, keep the reflux state and continue the reaction for 4h; then add 120mL of deionized water, and use 41.1g 30wt% sodium hydroxide solution was neutralized to pH 7.5; then the solvent was removed by atmospheric distillation, and the distillation was stopped when the gas phase temperature was 100°C to obtain 231.4g of a multifunctional polycarboxylic acid retanning fatliquor with a solid content of 33.3wt%, a monomer conversion rate of 99.4%, a weight average molecular weight Mw of 22135, a molecular weight distribution Mw / Mn of 2.16, and a viscosity of a 10wt% product aqueous solution of 26mPa·s.

[0065] The low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol acrylate is prepared by dissolving 5.0 g of azobisisobutyronitrile and 40 g of dodecanol acrylate in 60 mL of isopropanol (i.e., the second low-carbon alcohol solvent).

[0066] The test showed that the multifunctional polycarboxylic acid retanning fatliquor of the present embodiment had excellent biodegradability, and the biodegradation rates after 7 days and 28 days were 23.6 wt % and 54.3 wt %, respectively.

[0067] This embodiment also provides a multifunctional polycarboxylic acid retanning fatliquor prepared by the aforementioned method.

[0068] Example 7 This embodiment provides a method for preparing a multifunctional polycarboxylic acid retanning fatliquor, comprising the following steps: Weigh itaconic acid, dodecanol methacrylate, azobisisobutyronitrile, and isopropanol respectively, and divide isopropanol into two parts (i.e., the first part of low-carbon alcohol solvent and the second part of low-carbon alcohol solvent) for standby use; first add 60mL of isopropanol (i.e., the first part of low-carbon alcohol solvent) to a 500mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a feeding device, and heat it to 80-85°C (micro-reflux state), and then start to add azobisisobutyronitrile and dodecanol methacrylate low-carbon alcohol mixed solution at a uniform rate, and at the same time, add 26g of itaconic acid powder to the reactor in a multiple feeding manner of adding once every 5min, and control the feeding time of azobisisobutyronitrile and dodecanol methacrylate low-carbon alcohol mixed solution to be 3h; after the feeding is completed, keep the reflux state and continue the reaction for 4h; then add 120mL of deionized water, and use 41.1g 30wt% sodium hydroxide solution was neutralized to pH 7.5; then the solvent was removed by atmospheric distillation, and the distillation was stopped when the gas phase temperature reached 100°C to obtain 227.9g of a multifunctional polycarboxylic acid retanning fatliquor with a solid content of 32.4wt%, a monomer conversion rate of 99.0%, a weight average molecular weight Mw of 26123, a molecular weight distribution Mw / Mn of 2.53, and a viscosity of a 10wt% product aqueous solution of 62mPa·s.

[0069] The low-carbon alcohol mixed solution of azobisisobutyronitrile and dodecanol methacrylate is prepared by dissolving 1.3 g of azobisisobutyronitrile and 40 g of dodecanol methacrylate in 60 mL of isopropanol (i.e., the second low-carbon alcohol solvent).

[0070] The test showed that the multifunctional polycarboxylic acid retanning fatliquor of the present embodiment had excellent biodegradability, and the biodegradation rates after 7 days and 28 days were 21.3 wt % and 51.1 wt %, respectively.

[0071] This embodiment also provides a multifunctional polycarboxylic acid retanning fatliquor prepared by the aforementioned method.

[0072] The multifunctional polycarboxylic acid retanning and fatliquoring agents and the filling retanning agent MF-1 (comparative sample) of Examples 1-7 were respectively used to carry out leather retanning and fatliquoring tests. The specific retanning and fatliquoring process was as follows: using American cowhide, the leather embryo was first pickled and rewetted, and the pH value of the leather embryo was adjusted to 3.2±0.2; then the pickled and rewetted leather embryo was chrome retanned, and the pH value of the leather embryo was 4.0; then the leather embryo was neutralized to a pH of 5 to facilitate material combination; finally, the multifunctional polycarboxylic acid retanning and fatliquoring agents or the filling retanning agent MF-1 of each embodiment were respectively used to fill tanning and fatliquoring the leather embryo; the tanned leather was preliminarily evaluated when it was out of the drum, and the final evaluation was carried out after drying. Among them, the dosage basis is the weight of cowhide.

[0073] During the retanning and fatliquoring process, the operating conditions of each process are shown in the following table:

[0074] The evaluation method for leather tanning and fatliquoring performance is shown in the following table:

[0075] After the leather retanning and fatliquoring test, the performance indicators of the multifunctional polycarboxylic acid retanning and fatliquoring agent and the filling retanning agent MF-1 in each embodiment on leather tanning and fatliquoring are as follows:

[0076] It can be seen that the multifunctional polycarboxylic acid retanning and fatliquoring agents of Examples 1-7 of the present invention have better permeability, less odor, higher yellowing resistance, better waterproof function and natural feel for leather tanning than the existing filling retanning agent MF-1; the rest of the properties are similar to those of the filling retanning agent MF-1.

[0077] Unless otherwise specified, all percentages used in the present invention are by mass.

[0078] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a multifunctional polycarboxylic acid retanning fatliquor, characterized in that: Add the first portion of low-carbon alcohol solvent into the reaction kettle, stir and heat to reflux, and keep warm; then add the initiator and the low-carbon alcohol mixed solution of the vinyl-containing carboxylic acid long-chain ester, and add powdered itaconic acid in batches; control the adding time of the initiator and the low-carbon alcohol mixed solution of the vinyl-containing carboxylic acid long-chain ester to be 2.5-4 hours; after the addition is completed, continue to keep warm and reflux for 4-5 hours, add deionized water, and adjust the pH value to 7-8 with sodium hydroxide solution; remove the solvent by atmospheric distillation, and stop distilling when the gas phase temperature is 100°C to obtain a multifunctional polycarboxylic acid retanning fatliquor; The mixed solution of the initiator and the low-carbon alcohol containing vinyl long-chain carboxylic acid ester is a mixed solution in which the initiator and the long-carbon alcohol containing vinyl long-chain carboxylic acid ester are simultaneously dissolved in a second portion of low-carbon alcohol solvent.

2. The method for preparing the multifunctional polycarboxylic acid retanning fatliquor according to claim 1, characterized in that: The vinyl-containing long carbon chain carboxylic acid ester is one of the following: lauryl acrylate, hexadecanol acrylate, octadecyl acrylate, lauryl methacrylate, hexadecanol methacrylate, octadecyl methacrylate, lauryl maleate, hexadecanol maleate, octadecyl maleate, lauryl itaconate, hexadecanol itaconate, octadecyl itaconate.

3. The method for preparing the multifunctional polycarboxylic acid retanning fatliquor according to claim 1, characterized in that: The low-carbon alcohol solvent is at least one of the following: isopropanol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monoethyl ether, and propylene glycol monopropyl ether.

4. The method for preparing the multifunctional polycarboxylic acid retanning fatliquor according to claim 1, characterized in that: The weight of the first portion of the low-carbon alcohol solvent is 40-60% of the total weight of all the low-carbon alcohol solvents; the second portion of the low-carbon alcohol solvent is the remaining weight of the low-carbon alcohol solvent.

5. The method for preparing the multifunctional polycarboxylic acid retanning fatliquor according to claim 4, characterized in that: The mass ratio of itaconic acid, vinyl-containing carboxylic acid long-chain ester and all low-carbon alcohol solvents is 1:1-2.2:1.5-6.

5.

6. The method for preparing the multifunctional polycarboxylic acid retanning fatliquor according to claim 1, characterized in that: The initiator is an azo initiator or a peroxide initiator; The added weight of the initiator is 0.5-10% of the total weight of itaconic acid and the vinyl-containing long-chain carboxylic acid ester.

7. The method for preparing the multifunctional polycarboxylic acid retanning fatliquor according to claim 1, characterized in that: The added weight of the deionized water is 150-250% of the total weight of itaconic acid and the vinyl-containing long-chain carboxylic acid ester.

8. The method for preparing the multifunctional polycarboxylic acid retanning fatliquor according to claim 1, characterized in that: The powdered itaconic acid is added in multiple batches, and the time interval between the additions of adjacent batches of powdered itaconic acid shall not exceed 5 minutes.

9. The method for preparing the multifunctional polycarboxylic acid retanning fatliquor according to claim 1, characterized in that: The mass concentration of the sodium hydroxide solution is 10-50wt%.

10. A multifunctional polycarboxylic acid retanning fatliquor, characterized in that: The method is prepared by the method according to any one of claims 1 to 9.

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