Process for the preparation of polyacrylate leather finishing agents with dual antibacterial action

Abstract

The application provides a preparation method of polyacrylate leather finishing agent with double antibacterial effect, characterized in that acrylic ester comonomer and antibacterial functional monomer are prepared into pre-emulsion under the emulsification of a surfactant, and then copolymerization of the antibacterial functional monomer and the acrylic ester monomer is initiated by an initiator to obtain the polyacrylate leather finishing agent. The antibacterial functional monomers used in the application include two categories of antibacterial and adhesive menthol derivative monomers and quaternary phosphonium salt monomers containing carbon-carbon double bonds. The quaternary phosphonium salt antibacterial monomer has excellent bactericidal performance, and the menthol derivative is of natural origin and has good antibacterial and adhesive performance. Through ingenious design and suitable polymerization method, the antibacterial monomers with different antibacterial effects are introduced into polyacrylate at the molecular level, and the prepared polyacrylate leather finishing agent has both bactericidal performance and antimicrobial adhesive performance.

Description

Technical Field

[0001] The invention relates to the research field of antibacterial materials and the development field of water-based leather finishing materials, and in particular to a method for preparing a water-based polyacrylate leather finishing agent with dual antibacterial effects. Background Art

[0002] Leather, made from raw hides with largely intact original structure and processed through a series of physical and chemical processes, is a biomaterial with excellent physical and mechanical properties, wear comfort, and degradation stability. Due to its exceptional comfort, high breathability, and durability, it is widely used in daily life. The annual trade in leather products is estimated to reach $100 billion, demonstrating the critical role the leather industry plays in the global economy. However, leather products, rich in proteins and fats, are more susceptible to microbial invasion than other materials. Furthermore, the various additives added during leather processing and the presence of human secretions such as sweat and sebum on its surface create favorable conditions for microbial adhesion, growth, and proliferation, ultimately leading to the formation of biofilms. Furthermore, the humid and hot environments during storage and transportation often cause mold and mildew. Biofilms formed on leather surfaces can cause numerous undesirable effects, such as discoloration, unpleasant odors, product damage, and even the risk of skin infections. Therefore, inhibiting the adhesion and proliferation of microorganisms on leather surfaces has long been a concern.

[0003] To address this issue, the use of antimicrobial polymer coatings in leather finishing processes is a very effective strategy. Leather surface finishing is an important process for improving the appearance and physical properties of leather, and imparting functional protection and high added value such as antibacterial and mildew resistance. To reduce environmental pressure, the development of most new materials has now shifted from solvent-based materials to environmentally friendly water-based materials. Water-based polyacrylate emulsions have excellent film-forming properties, adhesion, weather resistance, gloss and color retention, and are inexpensive, safe, and environmentally friendly. They have become the most widely used type of film-forming substance in leather finishing materials. Among the existing methods for mildew prevention of finished leather, the most effective and main method is to add bactericidal and mildew-proofing agents to the water-based polyacrylate emulsions for leather finishing. However, the physical blending method is only suitable for short-term protection. During use, the small molecule bactericidal and mildew-proofing agents on the leather surface will gradually migrate and become free, losing their effectiveness. Therefore, from the perspective of toxicity, combining low-toxic organic antibacterial agents with polyacrylates to synthesize polyacrylates with antibacterial properties will be the development direction of antibacterial polyacrylates. Moreover, this method can give polyacrylates permanent antibacterial properties because the antibacterial monomers are introduced into the polyacrylate matrix at the molecular level.

[0004] On the other hand, most current strategies for preparing antimicrobial leather coatings focus on modifying the coating by adding bactericides or antibiotics. These methods aim to kill microorganisms attached to the leather surface. However, a significant issue is that the coating surface is easily covered by dead microbial residues, which prevents the interaction of the bactericidal components with other live bacteria, ultimately leading to antimicrobial failure. Therefore, people have gradually realized that developing new coatings with antimicrobial adhesion is an effective strategy for preventing biofouling. The antimicrobial mechanism of this strategy is different from that of traditional bactericidal mechanisms. It mainly prevents microorganisms from adhering to the surface of the material, thereby preventing their growth and reproduction. However, for microbial anti-adhesive leather coatings, it is difficult to achieve complete long-term prevention of microbial adhesion. Therefore, antimicrobial leather coatings that combine bactericidal and antimicrobial adhesion effects are a promising method for effectively preventing microbial contamination.

[0005] Quaternary phosphonium salts are compounds with a similar structure to quaternary ammonium salts. Compared to quaternary ammonium salts, they have more efficient and broad-spectrum bactericidal properties, low toxicity, good compatibility, and a wider pH range of use (pH 2-12), which makes up for the shortcomings of quaternary ammonium salts, which are poorly stable and only exhibit high bactericidal properties under alkaline conditions. The method of the present invention is to introduce quaternary phosphonium salts of different structures into polymer coatings at the molecular level and retain their lasting bactericidal efficacy, thereby imparting permanent antibacterial properties to polyacrylates. In order to solve the problem that the release of small molecule antibacterial agents in the antibacterial process pollutes the human body and the environment, in recent years, scientific researchers have used antibacterial groups through polymerization reactions to prepare polymer antibacterial agents or introduced small molecule antibacterial agents into stable polymer matrices through chemical bonds to obtain polymer materials or products with antibacterial effects. This will become a hot topic in the research and development of antibacterial polymers. Guo Qiliang et al. modified polyurethane acrylate (PUA) with a quaternary phosphonium salt unsaturated monomer (allyltriphenylphosphonium bromide) and produced a PUA material with excellent antibacterial properties through copolymerization. Li et al. introduced triphenylphosphine into the epoxy rubber backbone, ring-opening and quaternizing the epoxy rubber. After introducing a quaternary phosphonium salt with antibacterial activity, they produced a rubber product with long-lasting antibacterial properties. Tom et al. used click chemistry to graft a quaternary phosphonium azide onto polyester. The resulting polyester material can be used as a food packaging material and has excellent antibacterial properties.

[0006] Menthol, derived from natural plants, has been shown to significantly inhibit the growth of various fungi and bacteria. It achieves its antimicrobial effects by acting on the lipids of biofilms, altering membrane permeability. However, its antimicrobial properties are very limited. Recent research by the applicant has discovered that monomers with stereochemical effects can recognize microbial cells. Incorporating these monomers into a leather polymer matrix to create a leather coating can impart excellent antimicrobial adhesion properties to the leather, thereby achieving antibacterial and mildew-proofing effects. The applicant's research has discovered that menthol possesses a stereochemical structure that imparts excellent antimicrobial adhesion properties to the surface of the material.

[0007] Based on this, the purpose of the present invention is to first add a surfactant and an acrylate copolymer monomer to form a pre-emulsion, and then copolymerize a menthol derivative monomer with antibacterial adhesion properties and a quaternary phosphonium salt monomer with bactericidal properties with the acrylate monomer through an initiator to obtain a water-based polyacrylate leather finishing agent with dual antibacterial effects. Summary of the Invention

[0008] The present invention provides a method for preparing a water-based polyacrylate leather finishing agent with dual antibacterial effects. The method is characterized in that the acrylate comonomer and the antibacterial functional monomer are prepared into a pre-emulsion under the emulsifying action of a surfactant, and then the antibacterial functional monomer and the acrylate comonomer are copolymerized by initiating an initiator to prepare a water-based polyacrylate leather finishing agent with dual antibacterial effects. The specific preparation steps are as follows:

[0009] (1) Add a certain amount of surfactant to the reactor, and then add acrylate comonomer and antibacterial functional monomer. The amount of surfactant is 2-5 wt% of the total amount of comonomer, and the mass ratio of comonomer to water is (0.4-1):1. High-speed emulsification dispersion is carried out for 10-30 min at a stirring speed of 4000-10000 rpm to obtain a pre-emulsion.

[0010] (2) The pre-emulsion is added to a reactor equipped with a condensing and stirring device at a temperature of 60-80°C, and a certain amount of water-soluble initiator aqueous solution is added dropwise thereto. The dropping speed is controlled so that the dropping time is controlled within 0.5-1 h. The amount of initiator used is 0.4-1 wt% of the total amount of the comonomer. The mass ratio of the comonomer to water in the entire reaction system is (0.2-0.5):1. The temperature is raised to 75-100°C, the stirring speed is 500-2000 rpm, and the reaction is stirred for 2-5 h to obtain a water-based polyacrylate leather finishing agent with dual antibacterial effect.

[0011] The acrylate comonomer includes two components, a soft monomer and a hard monomer. The soft monomer is one of ethyl acrylate, n-propyl acrylate and n-butyl acrylate; the hard monomer is one of methyl acrylate, methyl methacrylate and ethyl methacrylate; the antibacterial functional monomer includes two components, one is a menthol derivative with antibacterial adhesion performance and containing a carbon-carbon double bond, and the other is a quaternary phosphonium salt with a carbon-carbon double bond. The mass ratio of the soft monomer to the hard monomer is (1~3):1, and the amount of the antibacterial functional monomer is 10~25 wt% of the total mass of the acrylate comonomer and the antibacterial functional monomer.

[0012] The water-based polyacrylate leather finishing material with dual antibacterial effects is characterized in that the quaternary phosphonium salt monomer with a carbon-carbon double bond is one of allyltriphenylphosphine bromide, (4-pentenyl)triphenylphosphine bromide and vinyltriphenylphosphine bromide.

[0013] The water-based polyacrylate leather coating material with dual antibacterial effects is characterized in that the menthol derivative with antibacterial adhesion properties is one of isopulegol, isopulegol and isomenthol, and the amount of the menthol derivative accounts for 10-30% of the total mass of the antibacterial functional monomer.

[0014] The water-based polyacrylate leather finishing material with dual antibacterial effects is characterized in that the surfactant is one of alkylphenol polyoxyethylene ether (OP-10), fatty alcohol polyoxyethylene ether (AEO-10), and polyol polyoxyethylene ether fatty acid ester (T-20).

[0015] The water-based polyacrylate leather finishing material with dual antibacterial effects is characterized in that the initiator is one of ammonium persulfate and potassium persulfate.

[0016] The antimicrobial functional monomers used in this invention include menthol derivatives with antimicrobial adhesion properties and quaternary phosphonium salt monomers containing carbon-carbon double bonds. Quaternary phosphonium salt antimicrobial monomers possess excellent bactericidal properties, while menthol derivatives are naturally derived and exhibit excellent antimicrobial adhesion and a degree of hydrophobicity, meeting the wet-rub resistance requirements of leather coatings. Through ingenious design and a suitable polymerization method, this patent introduces two antimicrobial monomers with different antimicrobial properties into polyacrylate at the molecular level. The resulting water-based polyacrylate leather finishing agent exhibits both bactericidal and antimicrobial adhesion properties. DETAILED DESCRIPTION

[0017] Three embodiments of the present invention are given below to specifically illustrate the preparation method of the water-based polyacrylate leather finishing agent with dual antibacterial effect.

[0018] Example 1:

[0019] Add 0.5 g of alkylphenol polyoxyethylene ether (OP-10) and 25 g of deionized water to the reactor, and then add the acrylic ester comonomer mixture: 4.2 g of methyl acrylate, 12.85 g of n-butyl acrylate, 3.41 g of allyltriphenylphosphonium bromide, and 0.85 g of isopulegol. High-speed emulsification and dispersion are carried out for 10 to 30 min at an emulsification and dispersion speed of 8000 rpm to obtain a pre-emulsion.

[0020] The pre-emulsion was added to a 250 ml three-necked flask equipped with a condenser and stirrer. The temperature was maintained at 70°C and the stirring speed was 1000 rpm. 0.15 g of the initiator ammonium persulfate was dissolved in 20 g of water. The ammonium persulfate aqueous solution was gradually added dropwise to the reaction flask, controlling the addition rate so that the addition was complete within 0.5 h. The temperature was raised to 85°C and the reaction was continued for 3 h. The mixture was then cooled to room temperature and filtered to obtain a water-based polyacrylate leather finishing agent with dual antibacterial properties.

[0021] Example 2:

[0022] Add 1 g of alkylphenol polyoxyethylene ether (OP-10) and 60 g of deionized water to the reactor, and then add the acrylic ester comonomer mixture: 8.4 g of methyl methacrylate, 25 g of ethyl acrylate, 7.77 g of (4-pentenyl)triphenylphosphonium bromide, and 3.33 g of isopulegol. High-speed emulsification and dispersion are carried out for 10 to 30 minutes at an emulsification and dispersion speed of 8000 rpm to obtain a pre-emulsion.

[0023] The pre-emulsion was added to a 250 ml three-necked flask equipped with a condenser and stirrer. The flask was maintained at 70°C and stirred at 1000 rpm. 0.3 g of the initiator ammonium persulfate was dissolved in 40 g of water. The ammonium persulfate aqueous solution was gradually added dropwise to the reaction flask, controlling the addition rate to ensure complete addition within 0.5 h. The temperature was raised to 85°C and the reaction was continued for 4 h. The mixture was then cooled to room temperature and filtered to obtain a water-based polyacrylate leather finishing agent with dual antibacterial properties.

[0024] Example 3:

[0025] Add 1.5 g of alkylphenol polyoxyethylene ether (OP-10) and 75 g of deionized water to the reactor, and then add the acrylic ester comonomer mixture: 10 g of n-propyl acrylate, 20 g of ethyl methacrylate, 3 g of vinyltriphenylphosphine bromide, and 0.33 g of isomenthol. High-speed emulsification and dispersion are carried out for 10 to 30 min at an emulsification and dispersion speed of 8000 rpm to obtain a pre-emulsion.

[0026] The pre-emulsion was added to a 250 ml three-necked flask equipped with a condenser and stirrer. The flask was maintained at 70°C and stirred at 1000 rpm. 0.3 g of the initiator ammonium persulfate was dissolved in 40 g of water. The ammonium persulfate aqueous solution was gradually added dropwise to the reaction flask, controlling the addition rate to ensure complete addition within 0.5 h. The temperature was raised to 80°C and the reaction was continued for 5 h. The mixture was then cooled to room temperature and filtered to obtain a water-based polyacrylate leather finishing agent with dual antibacterial properties.

Claims

1. A method for preparing a water-based polyacrylate leather finishing agent with dual antibacterial effects, characterized in that Under the emulsification effect of a surfactant, an acrylate comonomer and an antibacterial functional monomer are prepared into a pre-emulsion, and then an initiator is used to initiate a copolymerization reaction between the antibacterial functional monomer and the acrylate comonomer to prepare a water-based polyacrylate leather finishing agent with dual antibacterial effects. The specific preparation steps are as follows: (1) Add a certain amount of surfactant to the reactor, and then add acrylate comonomer and antibacterial functional monomer. The amount of surfactant is 2-5 wt% of the total amount of comonomer, and the mass ratio of comonomer to water is (0.4-1):

1. High-speed emulsification dispersion is carried out for 10-30 min at a stirring speed of 4000-10000 rpm to obtain a pre-emulsion. (2) The pre-emulsion is added to a reactor equipped with a condensing and stirring device at a temperature of 60-80°C, and a certain amount of water-soluble initiator aqueous solution is added dropwise thereto. The dropping speed is controlled so that the dropping time is controlled within 0.5-1 h. The amount of initiator used is 0.4-1 wt% of the total amount of the comonomer. The mass ratio of the comonomer to water in the entire reaction system is (0.2-0.5):

1. The temperature is raised to 75-100°C, the stirring speed is 500-2000 rpm, and the reaction is stirred for 2-5 h to obtain a water-based polyacrylate leather finishing agent with dual antibacterial effect. The acrylate comonomer includes two components, a soft monomer and a hard monomer, the soft monomer is one of ethyl acrylate, n-propyl acrylate and n-butyl acrylate; the hard monomer is one of methyl acrylate, methyl methacrylate and ethyl methacrylate; the antibacterial functional monomer includes two components, one is a menthol derivative with antibacterial adhesion performance and containing a carbon-carbon double bond, and the other is a quaternary phosphonium salt with a carbon-carbon double bond; the mass ratio of the soft monomer to the hard monomer is (1-3):1, and the amount of the antibacterial functional monomer is 10-25 wt% of the total mass of the acrylate comonomer and the antibacterial functional monomer.

2. The method for preparing a water-based polyacrylate leather finishing agent with dual antibacterial effect according to claim 1, characterized in that The quaternary phosphonium salt with a carbon-carbon double bond is one of allyltriphenylphosphine bromide, (4-pentenyl)triphenylphosphine bromide and vinyltriphenylphosphine bromide.

3. The method for preparing a water-based polyacrylate leather finishing agent with dual antibacterial effect according to claim 1, characterized in that The menthol derivative with antibacterial adhesion performance is one of isopulegol, isopulegol and isomenthol, and the amount of the menthol derivative accounts for 10-30% of the total mass of the antibacterial functional monomer.

4. The method for preparing a water-based polyacrylate leather finishing agent with dual antibacterial effect according to claim 1, characterized in that The surfactant is one of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether and polyol polyoxyethylene ether fatty acid ester.

5. The method for preparing a water-based polyacrylate leather finishing agent with dual antibacterial effect according to claim 1, characterized in that The initiator is one of ammonium persulfate and potassium persulfate.