CN102199389A - Self-crosslinking acrylic resin leather finishing agent and preparation method thereof - Google Patents

Abstract

A self-crosslinking acrylic resin leather finishing agent and a preparation method thereof. First, carry out free radical polymerization with acrylate, methacrylic acid and diacetone acrylamide to make an acrylic resin emulsion, adjust the pH of the emulsion to 5-6, and add a water-soluble protein structure as a cross-linking agent to prepare a Novel self-crosslinking acrylic resin leather finish. The present invention uses the protein substance as the crosslinking agent of the acrylic resin, realizes the self-crosslinking of the acrylic resin under room temperature controllability, effectively improves the physical properties of the coating film, and simplifies the production process of the acrylic resin coating film. Through the cross-linking effect, the defects of thermal viscosity and brittleness of the acrylic resin coating agent can be improved. At the same time, protein substances are introduced into the molecular chain of the acrylic resin, and the resin film has the properties of a protein film-forming agent, and the comprehensive performance is good.

Description

A kind of self-crosslinking acrylic resin leather finishing agent and preparation method thereof

technical field

The invention belongs to the production of leather chemicals, in particular to a self-crosslinking acrylic resin leather finishing agent and a preparation method thereof.

Background technique

Polyurethane resins, acrylic resins, butadiene resins, and modified protein film-forming agents are often used as film-forming materials in leather finishing, among which acrylic resins are used in the largest amount. Acrylic resin is synthesized by copolymerization of acrylate monomer and methacrylate monomer. The main absorption peak of acrylic resin is outside the solar spectrum range, so the prepared acrylic resin coating agent has excellent light resistance and Anti-aging properties. At the same time, the acrylic resin coating agent also has good flexibility and toughness, good tensile strength, strong adhesion, and no discoloration, and can be mixed with pigment paste and other water-soluble synthetic resins.

However, due to the chemical structure characteristics of acrylate monomers, the molecular chain of acrylate polymers is generally a linear structure, and functional groups such as carboxyl groups are located on the side chains of linear macromolecules. Therefore, the mechanical properties of its resin film Relatively poor, thermoplastic, sensitive to external temperature when used, has disadvantages such as hot stickiness and cold brittleness. In order to overcome the above defects, researchers at home and abroad have modified acrylic resins, mainly in the following aspects:

In the 1990s, Cytec Corporation of the United States developed an addition-polymerizable isocyanate monomer, dimethyl m-isopropenyl benzyl isocyanate (TMI). The isocyanate group of TMI is protected by two adjacent methyl groups, so it is relatively stable in water and will not undergo premature hydrolysis. He et al. (Appl Polym Sci, 1997, 64: 1143) mixed a copolymer emulsion of TMI and acrylate monomers with an amino-terminated polybutadiene emulsion to obtain a new type of self-curing emulsion. Although the two methyl groups adjacent to NCO in TMI improve the stability of NCO in water, the storage properties of the resulting self-curing emulsions are still poor.

Liu Yumei et al. (China Adhesives, 2005, 14(7): 9) used an oxidation-reduction initiation system to synthesize white latex at room temperature, and added N-methylol on the basis of formaldehyde of the protective colloid and copolymerization of acrylic monomers. Acrylamide is used as a cross-linking monomer to obtain white latex with excellent bonding performance and usability and low production cost. However, due to the release of formaldehyde during use, it is more harmful to humans and the environment.

Bollmann, Heinz et al. (USP 6184410) synthesized a polycarbodiimide crosslinking agent with 1,3 bis (-methyl-1-isocyanatoethyl) benzene as a raw material. The polycarbodiimide crosslinking agent can be quickly and efficiently cured, has a long slurry storage time, and effectively improves the water resistance of the paint film. But it has certain toxicity, the adhesion of the coating needs to be improved, the price is expensive, and the dosage is large, so it is difficult to popularize and use it.

Eastman Co. (USP 6262169) uses diacetone acrylamide and acrylate monomers for copolymerization, introduces diacetone acrylamide monomer units into the molecular main chain, and forms diacetone acrylamide by adding polyamine compounds as crosslinking agents. /Polyamine cross-linking system, using H+ to react with amine groups (to generate protonated amines) to protect them. When the emulsion is dried and formed into a film, the acid gradually volatilizes to realize the cross-linking. The resulting coating film has excellent performance, but the polyamine compound used will pollute the environment.

Cao Jianguo et al. (Acrylic acid chemical industry and application, 2004, 17 (3): 20.) synthesized the primary amine compound (UPA) containing double bonds with maleic anhydride and ethylenediamine, and carried out emulsion copolymerization with acrylate, and then Composite with ethylene glycol diglycidyl ether water emulsion to form a room temperature curing coating. The tensile strength of the obtained composite emulsion coating film is obviously improved, but the system needs to be placed at room temperature for two weeks before it can be naturally dried to form a film, which is a long period, and the storage stability of the emulsion has not been reported.

Cheng Shiliang (Progress in Chemical Industry, 2005, 24(1): 61.) etc. respectively synthesized polyurethane emulsion terminated with hydrazide group and polyacrylate emulsion with ketone carbonyl side chain, and the two were mixed and compounded into a compound that can be cross-treated at room temperature. emulsion and can be stored at room temperature for extended periods of time. However, due to the high price and high cost of the functional monomer, its application is limited.

Zhu Yangrong and others (Journal of Materials Science and Engineering, 2006, 24 (2): 244.) introduced functional monomer acetoacetoxy ethyl methacrylate into the synthetic acrylic emulsion, which is a polymer chain with ketone carbonyl group, and then add γ-aminopropyltriethoxysilane to obtain room temperature self-crosslinking hybrid silicon acrylic emulsion. The water resistance, aging resistance, hardness and tensile strength of the silicon-acrylic latex film have been significantly improved. However, the stable storage time of the system is not stated.

Although through the improvement of the above methods, various modified acrylic resin coating agents have improved in terms of mechanics, adhesion, light resistance and other physical and chemical properties, but some properties in actual use, such as weather resistance, lighting performance, etc. There are also some deficiencies.

Contents of the invention

The purpose of the present invention is to provide a self-crosslinking acrylic resin that not only improves the properties of the acrylic resin coating agent, such as thermal viscosity, cold brittleness, and polishing performance, but also realizes self-crosslinking at room temperature and shortens the film-forming time of the acrylic resin coating agent. Leather finishing agent and preparation method thereof.

To achieve the above object, the preparation method of the present invention is as follows:

Step 1: Pre-emulsification:

First, take 40 parts by mass of deionized aqueous solution dissolved with 2 to 6 parts of emulsifier into the first reactor with agitator, condenser and thermometer, and raise the temperature to 35 to 50 °C;

Then 36.5 parts of butyl acrylate, 12.5 parts of methyl acrylate, 1 part of acrylic acid and 0.5-2 parts of diacetone acrylamide were mixed and added dropwise to the first reactor within 30-60 minutes for pre-emulsification for 30-60 minutes to obtain pre- Emulsion;

The second step: polymerization reaction:

Take 20 parts by mass parts of deionized aqueous solution dissolved with 0.5 to 1 part of emulsifier into the second reactor with agitator, condenser and thermometer, feed _enough N to remove the oxygen in the reactor, and raise the temperature to 30～50℃;

Then add 30-40 parts of pre-emulsion and 10 parts of deionized aqueous solution dissolved with 0.05-0.2 parts of initiator directly into the second reactor. Within 3 hours, drop the remaining pre-emulsion and 20 parts of deionized aqueous solution dissolved with 0.1-0.4 parts of initiator into the second reactor, react for 1-3 hours, cool to room temperature to obtain emulsion, and adjust the pH of the emulsion to 5-6 , use deionized water to adjust the solid content of the emulsion to 30%, then add 20 to 70 parts of 10% protein aqueous solution into the emulsion, then adjust the emulsion to 5 to 6, and stir for 30 minutes to obtain the solid content It is a 20-30% self-crosslinking acrylic resin emulsion.

其中：R₁为C₁₂～C₁₈的长碳链烷基；R₂为H或-SO₃Na；n为乙氧基的数目，n的取值范围是3～20。Emulsifier of the present invention is fatty alcohol polyoxyethylene ether emulsifier, and its structural formula is

Wherein: R ₁ is a C ₁₂ -C ₁₈ long carbon chain alkyl group; R ₂ is H or -SO ₃ Na; n is the number of ethoxy groups, and the value range of n is 3-20.

The emulsifier is a mixture of AES and OS-15, and the mass ratio of AES:OS-15 in the mixture is 1:0.3-3.

The initiator is ammonium persulfate, potassium persulfate, hydrogen peroxide or tert-butanol peroxide.

The protein substance is casein.

The polymerization reaction is continuously fed with N ₂ to maintain an oxygen-free state.

According to the self-crosslinking acrylic resin leather finishing agent made by the preparation method of the present invention, the crosslinking structural representation is:

为丙烯酸树脂主链；

为蛋白质分子链；R₁，R₂为羧基，甲基，甲酯基或正丁酯基。in,

is the main chain of acrylic resin;

is a protein molecular chain; R ₁ and R ₂ are carboxyl, methyl, methyl carboxyl or n-butyl carboxyl.

The present invention uses proteinaceous substances and diacetone acrylamide as the crosslinking system, which not only realizes the room temperature controllable self-crosslinking of the modified acrylic resin, but also shortens the film-forming and drying time and the crosslinking and curing time during leather coating. The introduction of small molecular proteins improves the hot-sticky and cold-brittle properties of the acrylic resin coating film, making the film have better physical properties such as adhesion, extensibility and gloss.

Detailed ways

The present invention is specifically described below by way of examples. It is necessary to point out that this embodiment is only used to further illustrate the present invention, and should not be construed as a limitation of the scope of protection. Those skilled in the art can make some non-essential improvements and adjustments according to the content of the present invention.

Example 1:

Step 1: Pre-emulsification:

First, take 40 parts by mass of deionized aqueous solution in which 2 parts of emulsifier is dissolved and add it to the first reactor equipped with a stirrer, condenser and thermometer, and raise the temperature to 35°C;

Then 36.5 parts of butyl acrylate, 12.5 parts of methyl acrylate, 1 part of acrylic acid and 0.5 part of diacetone acrylamide were mixed and added dropwise to the first reactor within 30 minutes for pre-emulsification for 30 minutes to obtain a pre-emulsion;

The second step: polymerization reaction:

Get 20 parts by mass parts and be dissolved with 0.5 parts of deionized aqueous solution of emulsifier and add in the second reactor that has stirrer, condenser and thermometer, feed enough _N Oxygen in the removal reactor, be warming up to 30 ℃;

Then add 30 parts of pre-emulsion and 10 parts of deionized aqueous solution with 0.05 parts of initiator directly into the second reactor, react until the emulsion is slightly blue, then continue to heat up to 75 ° C, and simultaneously dissolve the remaining pre-emulsion within 3 hours Add 20 parts of deionized aqueous solution with 0.1 part of initiator dropwise into the second reactor, react for 3 hours, cool to room temperature to obtain an emulsion, adjust the pH of the emulsion to 5-6, and adjust the solid content of the emulsion to 30 with deionized water %, then 20 parts of casein aqueous solution with a mass percentage of 10% was added to the emulsion, and the emulsion was adjusted to 5-6, and stirred for 30 minutes to obtain a self-crosslinking acrylic resin emulsion with a solid content of 28%. Wherein the emulsifier is a mixture of AES and OS-15, the mass ratio of AES:OS-15 in the mixture is 1:0.3, the initiator is potassium persulfate, N ₂ is continuously fed into the polymerization reaction, and an oxygen-free state is maintained.

Example 2:

Step 1: Pre-Emulsification:

First, take 40 parts of deionized aqueous solution dissolved with 4 parts of emulsifier in parts by mass and add it to the first reactor with agitator, condenser and thermometer, and heat up to 40°C;

Then 36.5 parts of butyl acrylate, 12.5 parts of methyl acrylate, 1 part of acrylic acid and 1 part of diacetone acrylamide were mixed and added dropwise to the first reactor within 40 minutes for pre-emulsification for 40 minutes to obtain a pre-emulsion;

The second step: polymerization reaction:

Get 20 parts by mass parts and be dissolved with 0.5 parts of deionized aqueous solution of emulsifier and add in the second reactor that has agitator, condenser and thermometer, feed enough _N Oxygen in the removal reactor, be warming up to 40 ℃;

Then add 30 parts of pre-emulsion and 10 parts of deionized aqueous solution with 0.1 part of initiator directly into the second reactor, and react until the emulsion turns slightly blue, then continue to heat up to 90°C, and simultaneously dissolve the remaining pre-emulsion within 1 hour Add 20 parts of deionized aqueous solution containing 0.2 parts of initiator dropwise into the second reactor, react for 1 hour, cool to room temperature to obtain an emulsion, adjust the pH of the emulsion to 5-6, and use deionized water to adjust the solid content of the emulsion to 30 %, then 40 parts of casein aqueous solution with a mass percentage of 10% was added to the emulsion, and then the emulsion was adjusted to 5-6, and stirred for 30 minutes to obtain a self-crosslinking acrylic resin emulsion with a solid content of 26%. Wherein the emulsifier is a mixture of AES and OS-15, the mass ratio of AES:OS-15 in the mixture is 1:1, the initiator is ammonium persulfate, N ₂ is continuously fed into the polymerization reaction, and an oxygen-free state is maintained.

Example 3:

Step 1: Pre-Emulsification:

First, take 40 parts of deionized aqueous solution dissolved with 6 parts of emulsifier in parts by mass and add it to the first reactor with agitator, condenser and thermometer, and raise the temperature to 45°C;

Then 36.5 parts of butyl acrylate, 12.5 parts of methyl acrylate, 1 part of acrylic acid and 1.5 parts of diacetone acrylamide were mixed and added dropwise to the first reactor within 60 minutes for pre-emulsification for 60 minutes to obtain a pre-emulsion;

The second step: polymerization reaction:

Get 20 parts by mass parts and be dissolved with 0.8 parts of deionized aqueous solution of emulsifier and add in the second reactor that has agitator, condenser and thermometer, pass into enough _N Oxygen in the removal reactor, be warming up to 36 ℃;

Then, 40 parts of pre-emulsion and 10 parts of deionized aqueous solution with 0.15 parts of initiator dissolved in it were directly added into the second reactor, and after reacting until the emulsion turned slightly blue, the temperature was continued to rise to 85°C, and the remaining pre-emulsion Emulsion and 20 parts of deionized aqueous solution dissolved with 0.4 parts of initiator were added dropwise into the second reactor, reacted for 2.5 hours, cooled to normal temperature to obtain emulsion, adjusted the pH of the emulsion to 5-6, and adjusted the solid content of the emulsion with deionized water Then add 50 parts of 10% by mass casein aqueous solution into the emulsion, adjust the emulsion to 5-6, and stir for 30 minutes to obtain a self-crosslinking acrylic resin emulsion with a solid content of 30%. Wherein the emulsifier is a mixture of AES and OS-15, the mass ratio of AES:OS-15 in the mixture is 1:2, the initiator is hydrogen peroxide, N ₂ is continuously fed into the polymerization reaction, and an oxygen-free state is maintained.

Example 4:

Step 1: Pre-emulsification:

First, take 40 parts of deionized aqueous solution dissolved with 3 parts of emulsifier in parts by mass and add it to the first reactor with agitator, condenser and thermometer, and raise the temperature to 50°C;

Then 36.5 parts of butyl acrylate, 12.5 parts of methyl acrylate, 1 part of acrylic acid and 2 parts of diacetone acrylamide were mixed and added dropwise to the first reactor within 50 minutes for pre-emulsification for 50 minutes to obtain a pre-emulsion;

The second step: polymerization reaction:

Get 20 parts by mass parts and be dissolved with 1 part of deionized aqueous solution of emulsifier and add in the second reactor that has agitator, condenser and thermometer, pass into enough _N Oxygen in the removal reactor, be warmed up to 50 ℃;

Then add 35 parts of pre-emulsion and 10 parts of deionized aqueous solution with 0.2 parts of initiator directly into the second reactor, react until the emulsion is slightly blue, then continue to heat up to 80 ° C, within 2 hours at the same time the remaining pre-emulsion Add 20 parts of deionized aqueous solution with 0.3 parts of initiator dropwise into the second reactor, react for 2 hours, cool to room temperature to obtain an emulsion, adjust the pH of the emulsion to 5-6, and adjust the solid content of the emulsion to 30 with deionized water %, then 70 parts of casein aqueous solution with a mass percentage of 10% was added to the emulsion, and then the emulsion was adjusted to 5-6, and stirred for 30 minutes to obtain a self-crosslinking acrylic resin emulsion with a solid content of 20%. Wherein the emulsifier is a mixture of AES and OS-15, the mass ratio of AES:OS-15 in the mixture is 1:3, the initiator is tert-butanol peroxide, N ₂ is continuously fed into the polymerization reaction, and an oxygen-free state is maintained.

Claims (7)

1. a preparation method of self-crosslinking acrylic resin leather finishing agent, is characterized in that: Step 1: Pre-emulsification: First, take 40 parts by mass of deionized aqueous solution dissolved with 2 to 6 parts of emulsifier into the first reactor with agitator, condenser and thermometer, and raise the temperature to 35 to 50 °C; Then 36.5 parts of butyl acrylate, 12.5 parts of methyl acrylate, 1 part of acrylic acid and 0.5-2 parts of diacetone acrylamide were mixed and added dropwise to the first reactor within 30-60 minutes for pre-emulsification for 30-60 minutes to obtain pre- Emulsion; The second step: polymerization reaction: Take 20 parts by mass parts of deionized aqueous solution dissolved with 0.5 to 1 part of emulsifier into the second reactor with agitator, condenser and thermometer, feed _enough N to remove the oxygen in the reactor, and raise the temperature to 30～50℃; Then add 30-40 parts of pre-emulsion and 10 parts of deionized aqueous solution dissolved with 0.05-0.2 parts of initiator directly into the second reactor. Within 3 hours, drop the remaining pre-emulsion and 20 parts of deionized aqueous solution dissolved with 0.1-0.4 parts of initiator into the second reactor, react for 1-3 hours, cool to room temperature to obtain emulsion, and adjust the pH of the emulsion to 5-6 , use deionized water to adjust the solid content of the emulsion to 30%, then add 20 to 70 parts of 10% protein aqueous solution into the emulsion, then adjust the emulsion to 5 to 6, and stir for 30 minutes to obtain the solid content It is a 20-30% self-crosslinking acrylic resin emulsion. 2. the preparation method of self-crosslinking acrylic resin leather finishing agent according to claim 1 is characterized in that: described emulsifier is fatty alcohol polyoxyethylene ether emulsifier, and its structural formula is

Wherein: R ₁ is a C ₁₂ -C ₁₈ long carbon chain alkyl group; R ₂ is H or -SO ₃ Na; n is the number of ethoxy groups, and the value range of n is 3-20. 3. the preparation method of self-crosslinking acrylic resin leather finishing agent according to claim 1 is characterized in that: described emulsifying agent is the mixture of AES and OS-15, and the quality of mass ratio AES:OS-15 in the mixture The ratio is 1:0.3~3. 4. The preparation method of self-crosslinking acrylic resin leather finishing agent according to claim 1, characterized in that: the initiator is ammonium persulfate, potassium persulfate, hydrogen peroxide or tert-butyl alcohol peroxide. 5. The preparation method of self-crosslinking acrylic resin leather finishing agent according to claim 1, characterized in that: said proteinaceous substance is casein. 6 . The preparation method of self-crosslinking acrylic resin leather finishing agent according to claim 1 , characterized in that: the polymerization reaction is continuously fed with N ₂ to maintain an oxygen-free state. 6 . 7. A self-crosslinking acrylic resin leather finishing agent made by the preparation method as claimed in claim 1, characterized in that: the crosslinking structure schematic formula is:

in,

is the main chain of acrylic resin;

is a protein molecular chain; R ₁ and R ₂ are carboxyl, methyl, methyl carboxyl or n-butyl carboxyl.