Preparation process of an antibacterial and mildew-proof polyethylene plastic

Abstract

The present invention discloses a preparation process of an antibacterial and mildew-proof polyethylene plastic. The present invention uses a polyethylene resin, an end-alkenyl quaternary ammonium salt-modified silicone oil, a polyurethane elastomer, and an antioxidant as raw materials to obtain the antibacterial and mildew-proof polyethylene plastic. The modified silicone oil contains end-alkenyl groups and undergoes chemical cross-linking with polyethylene under the cross-linking action of dicumyl peroxide. Moreover, the end-alkenyl quaternary ammonium salt-modified silicone oil contains a urethane structural unit, and when it is cross-linked and bonded to the molecular chain of polyethylene, it can act as a compatibilizer to improve the interfacial compatibility between the polyethylene matrix and the polyurethane elastomer, significantly improving the tensile properties and flexural strength of the polyethylene plastic. The end-alkenyl quaternary ammonium salt-modified silicone oil contains an organosilicon quaternary ammonium salt antibacterial structure, thus exhibiting excellent bactericidal performance.

Description

Technical Field

[0001] The present invention relates to the technical field of polyethylene, and specifically to a preparation process of an antibacterial and mildew-proof polyethylene plastic. Background Art

[0002] Polyethylene plastics have good insulation performance and processing performance, and are widely used in pipes, films, cables, etc. With the rapid development of high-tech materials, traditional polyethylene has low mechanical strength and does not have antibacterial, flame-retardant and other properties, and can no longer meet the needs of industrial production. At present, the main methods for modifying polyethylene are crosslinking modification, blending modification, etc. Organosilicon materials such as siloxane and silicone oil have good toughness, corrosion resistance, high temperature resistance and other properties, and are widely used in polymer materials. Chinese Patent CN104277182B discloses a preparation method of crosslinked low-density polyethylene, using octafunctional cage-shaped oligosilsesquioxane as a crosslinking agent to improve the mechanical properties and dielectric properties of polyethylene. However, the polyethylene material of this patent does not show good antibacterial and mildew-proof properties.

[0003] Polyurethane elastomer has properties such as high strength, good toughness, wear resistance, oil resistance, etc., and can be used as a toughening agent, widely used in materials such as polyethylene, polyvinyl chloride, and acrylic resin, and can improve the mechanical properties of materials. However, the compatibility between polyurethane elastomer and resins such as polyethylene is poor, and usually a compatibilizer needs to be added to improve the compatibility between polyurethane elastomer and the resin matrix in order to effectively improve the properties of the material. Summary of the Invention

[0004] Technical problems to be solved: The present invention solves the problems of poor mechanical properties and poor antibacterial properties of polyethylene plastics.

[0005] Technical solution: A preparation process of an antibacterial and mildew-proof polyethylene plastic:

[0006] Step S1: Add terminal hydrogen silicone oil, N-methyl diethyl (isopropenylbenzylcarbamate) amine, inhibitor, and Karstedt catalyst into a reaction flask, stir evenly, introduce nitrogen, carry out hydrosilylation reaction, add methanol after the reaction, let it stand for layering, separate and remove methanol, and dry to obtain terminal alkenyl modified silicone oil.

[0007] The structural formula of N-methyl diethyl (isopropenylbenzylcarbamate) amine is:

[0008]

[0009] Step S2: Add terminal alkenyl modified silicone oil, benzyl halide, and N,N-dimethylformamide into a reaction flask, stir and mix evenly, carry out quaternization reaction, concentrate the solution, add methanol, let it stand for layering, separate and remove methanol, and dry to obtain terminal alkenyl quaternary ammonium salt modified silicone oil.

[0010] Step S3: Mix polyethylene resin, end-alkenyl quaternary ammonium salt modified silicone oil, polyurethane elastomer, and antioxidant in a high-speed mixer, then add them to a two-roll mill, add initiator diisopropylbenzene peroxide, and knead at 175 - 185 °C for 6 - 10 min. Finally, heat press the material in a flat vulcanizer at 185 - 190 °C for 10 - 15 min, with a pressure of 10 - 15 MPa, and cool to obtain antibacterial and mildew-proof polyethylene plastic.

[0011] Preferably, in S1, the molar amount of N-methyldiethyl(isopropenylbenzylcarbamate)amine is 205 - 220% of the molar amount of terminal hydrogen silicone oil.

[0012] Preferably, in S1, the hydrosilylation reaction is carried out at 85 - 95 °C for 4 - 8 h.

[0013] Preferably, in S1, the mass of benzyl halide is 22 - 30% of the mass of end-alkenyl quaternary ammonium salt modified silicone oil.

[0014] Preferably, the benzyl halide is benzyl chloride or benzyl bromide.

[0015] Preferably, in S2, the quaternization reaction is carried out at 110 - 130 °C for 60 - 72 h.

[0016] Preferably, in S3, the masses of end-alkenyl quaternary ammonium salt modified silicone oil and polyurethane elastomer are 1 - 4% and 2 - 10% of the mass of polyethylene resin respectively.

[0017] Preferably, the preparation process of N-methyldiethyl(isopropenylbenzylcarbamate)amine in S3 is as follows: Add N-methyldiethanolamine and 200 - 220% of the molar amount of N-methyldiethanolamine of 3-isopropenyl-α,α-dimethylbenzyl isocyanate to 1,4-dioxane, stir and react at 70 - 80 °C for 2 - 4 h, concentrate the solution, and separate by silica gel column chromatography. The eluent is ethyl acetate:petroleum ether = 1:9 (by volume) to obtain N-methyldiethyl(isopropenylbenzylcarbamate)amine.

[0018] The technical effect of the present invention: The present invention uses terminal hydrogen silicone oil and N-methyldiethyl(isopropenylbenzylcarbamate)amine to carry out a hydrosilylation reaction, and regulates the reaction ratio between the two to obtain end-alkenyl quaternary ammonium salt modified silicone oil.

[0019] In the present invention, an alkenyl quaternary ammonium salt modified silicone oil and a polyurethane elastomer are added to a polyethylene resin. The modified silicone oil contains alkenyl groups, which can provide more crosslinking sites. Under the crosslinking action of dicumyl peroxide, it undergoes chemical crosslinking with polyethylene, grafting flexible polysiloxane segments onto the polyethylene molecular chain. After chemical crosslinking, the mechanical properties of the polyethylene plastic are better. Moreover, the alkenyl quaternary ammonium salt modified silicone oil contains urethane structural units, which have good affinity and compatibility with the urethane structural units in the polyurethane elastomer. Crosslinking and bonding them to the molecular chain of polyethylene can act as a compatibilizer, improving the interfacial compatibility between the polyethylene matrix and the polyurethane elastomer, enabling the excellent polyurethane elastomer to exert a better reinforcing effect, and significantly improving the tensile properties and flexural strength of the polyethylene plastic.

[0020] The alkenyl quaternary ammonium salt modified silicone oil added to the polyethylene resin in the present invention contains an organosilicon quaternary ammonium salt antibacterial structure. It can be adsorbed on the cell membrane surface of bacteria, molds and other microorganisms through electrostatic action, and penetrate into the lipid layer and protein layer of the cell membrane, changing the cell membrane permeability, causing substances such as enzymes in the bacteria to escape, and inhibiting the metabolic process of bacteria and microorganisms, thereby exhibiting excellent bactericidal and mildew-proof properties. Brief Description of the Drawings

[0021] Figure 1 is the preparation reaction formula of N-methyldiethyl(isopropenylbenzylcarbamate)amine.

[0022] Figure 2 is the preparation reaction route of the alkenyl quaternary ammonium salt modified silicone oil. Detailed Description of the Invention

[0023] The polyethylene resin of the present invention has the grade 1002YB.

[0024] The hydrogen-terminated silicone oil has the grade BMS202 and a hydrogen content of 0.198%.

[0025] The polyurethane elastomer has the grade BASF 95A.

[0026] Example 1

[0027] Add 6 mmol of N-methyldiethanolamine and 13.2 mmol of 3-isopropenyl-α,α-dimethylbenzyl isocyanate to 5 mL of 1,4-dioxane, stir and react at 70 °C for 4 h. Concentrate the solution and separate it by silica gel column chromatography. The eluent is ethyl acetate:petroleum ether = 1:9 by volume to obtain N-methyldiethyl(isopropenylbenzylcarbamate)amine. The yield is 2.65 g.

[0028] Example 2

[0029] 6 mmol of N-methyldiethanolamine and 12 mmol of 3-isopropenyl-α,α-dimethylbenzyl isocyanate were added to 5 mL of 1,4-dioxane, and the mixture was stirred at 80 °C for 2 h. The solution was concentrated and separated by silica gel column chromatography with an eluent of ethyl acetate:petroleum ether = 1:9 (volume ratio) to obtain N-methyldiethyl(isopropenylbenzylcarbamate)amine. The yield was 2.49 g.

[0030] Example 3

[0031] (1) 20 mmol of terminal hydrogen silicone oil, 41 mmol of N-methyldiethyl(isopropenylbenzylcarbamate)amine (prepared by the same process as in Example 1), 5.8 mg of inhibitor p-methoxyphenol, and 4.2 mg of Karstedt catalyst were added to a reaction flask and stirred evenly. Nitrogen was introduced, and the hydrosilylation reaction was carried out at 95 °C for 4 h. After the reaction, methanol was added, and the mixture was allowed to stand for phase separation. Methanol was separated and removed, and then dried to obtain terminal alkenyl modified silicone oil.

[0032] (2) 20 g of terminal alkenyl modified silicone oil, 4.4 g of benzyl chloride, and 100 mL of N,N-dimethylformamide were added to a reaction flask, stirred and mixed evenly, and the quaternization reaction was carried out at 120 °C for 72 h. The solution was concentrated, methanol was added, and the mixture was allowed to stand for phase separation. Methanol was separated and removed, and then dried to obtain terminal alkenyl quaternary ammonium salt modified silicone oil.

[0033] (3) 1 kg of polyethylene resin, 10 g of terminal alkenyl quaternary ammonium salt modified silicone oil, 20 g of polyurethane elastomer, and 4 g of antioxidant 1010 were added to a high-speed mixer and mixed evenly, and then added to a two-roll mill. 0.58 g of initiator diisopropylbenzene peroxide was added, and the mixture was kneaded at 185 °C for 6 min. Finally, the material was hot-pressed at 190 °C for 15 min under a pressure of 10 MPa in a flat vulcanizer, and then cooled to obtain antibacterial and mildew-proof polyethylene plastic.

[0034] Example 4

[0035] (1) 20 mmol of terminal hydrogen silicone oil, 44 mmol of N-methyldiethyl(isopropenylbenzylcarbamate)amine (prepared by the same process as in Example 1), 6.3 mg of inhibitor p-methoxyphenol, and 5 mg of Karstedt catalyst were added to a reaction flask and stirred evenly. Nitrogen was introduced, and the hydrosilylation reaction was carried out at 85 °C for 8 h. After the reaction, methanol was added, and the mixture was allowed to stand for phase separation. Methanol was separated and removed, and then dried to obtain terminal alkenyl modified silicone oil.

[0036] (2) 20 g of terminal alkenyl modified silicone oil, 4.4 g of benzyl chloride, and 100 mL of N,N-dimethylformamide were added to a reaction flask, stirred and mixed evenly, and the quaternization reaction was carried out at 120 °C for 72 h. The solution was concentrated, methanol was added, and the mixture was allowed to stand for phase separation. Methanol was separated and removed, and then dried to obtain terminal alkenyl quaternary ammonium salt modified silicone oil.

[0037] (3) Mix 1 kg of polyethylene resin, 20 g of alkenyl quaternary ammonium salt modified silicone oil, 40 g of polyurethane elastomer, and 4 g of antioxidant 1010 in a high-speed mixer, then add them to a two-roll mill, add 1.1 g of initiator diisopropylbenzene peroxide, mix at 180 °C for 10 min, and finally heat-press the material in a flat vulcanizer at 190 °C for 10 min under a pressure of 15 MPa, and cool to obtain antibacterial and mildew-proof polyethylene plastic.

[0038] Example 5

[0039] (1) Add 20 mmol of hydrogen-terminated silicone oil, 44 mmol of N-methyldiethyl(isopropenylbenzylcarbamate)amine (the same preparation process as in Example 1), 6.3 mg of inhibitor p-methoxy phenol, and 5 mg of Karstedt catalyst to a reaction flask, stir evenly, introduce nitrogen, carry out hydrosilylation reaction at 85 °C for 6 h, add methanol after the reaction, let it stand for stratification, separate and remove methanol, and dry to obtain alkenyl-modified silicone oil.

[0040] (2) Add 20 g of alkenyl-modified silicone oil, 6 g of benzyl bromide, and 100 mL of N,N-dimethylformamide to a reaction flask, stir evenly, carry out quaternization reaction at 130 °C for 60 h, concentrate the solution, add methanol, let it stand for stratification, separate and remove methanol, and dry to obtain alkenyl quaternary ammonium salt modified silicone oil.

[0041] (3) Mix 1 kg of polyethylene resin, 30 g of alkenyl quaternary ammonium salt modified silicone oil, 70 g of polyurethane elastomer, and 4 g of antioxidant 1010 in a high-speed mixer, then add them to a two-roll mill, add 1.7 g of initiator diisopropylbenzene peroxide, mix at 180 °C for 10 min, and finally heat-press the material in a flat vulcanizer at 185 °C for 15 min under a pressure of 10 MPa, and cool to obtain antibacterial and mildew-proof polyethylene plastic.

[0042] Example 6

[0043] (1) Add 20 mmol of hydrogen-terminated silicone oil, 42 mmol of N-methyldiethyl(isopropenylbenzylcarbamate)amine (the same preparation process as in Example 1), 6 mg of inhibitor p-methoxy phenol, and 4.2 mg of Karstedt catalyst to a reaction flask, stir evenly, introduce nitrogen, carry out hydrosilylation reaction at 95 °C for 4 h, add methanol after the reaction, let it stand for stratification, separate and remove methanol, and dry to obtain alkenyl-modified silicone oil.

[0044] (2) Add 20 g of alkenyl-modified silicone oil, 6 g of benzyl bromide, and 150 mL of N,N-dimethylformamide into a reaction flask, stir and mix evenly, conduct a quaternization reaction at 110 °C for 72 h, concentrate the solution, add methanol, let it stand for stratification, separate and remove methanol, and dry to obtain alkenyl quaternary ammonium salt-modified silicone oil.

[0045] (3) Add 1 kg of polyethylene resin, 40 g of alkenyl quaternary ammonium salt-modified silicone oil, 100 g of polyurethane elastomer, and 4 g of antioxidant 1010 into a high-speed mixer and mix evenly, then add them into a two-roll mill, add 2.6 g of initiator diisopropylbenzene peroxide, knead at 175 °C for 10 min, finally place the material in a flat vulcanizer, hot press at 190 °C for 10 min, with a pressure of 15 MPa, and cool to obtain antibacterial and mildew-proof polyethylene plastic.

[0046] Comparative Example 1

[0047] Add 1 kg of polyethylene resin and 4 g of antioxidant 1010 into a high-speed mixer and mix evenly, then add them into a two-roll mill, add 0.58 g of initiator diisopropylbenzene peroxide, knead at 185 °C for 6 min, finally place the material in a flat vulcanizer, hot press at 190 °C for 15 min, with a pressure of 10 MPa, and cool to obtain antibacterial and mildew-proof polyethylene plastic.

[0048] Comparative Example 2

[0049] Add 1 kg of polyethylene resin, 20 g of polyurethane elastomer, and 4 g of antioxidant 1010 into a high-speed mixer and mix evenly, then add them into a two-roll mill, add 0.58 g of initiator diisopropylbenzene peroxide, knead at 185 °C for 6 min, finally place the material in a flat vulcanizer, hot press at 190 °C for 15 min, with a pressure of 10 MPa, and cool to obtain antibacterial and mildew-proof polyethylene plastic.

[0050] Comparative Example 3

[0051] Add 1 kg of polyethylene resin, 10 g of alkenyl quaternary ammonium salt-modified silicone oil, and 4 g of antioxidant 1010 into a high-speed mixer and mix evenly, then add them into a two-roll mill, add 0.58 g of initiator diisopropylbenzene peroxide, knead at 185 °C for 6 min, finally place the material in a flat vulcanizer, hot press at 190 °C for 15 min, with a pressure of 10 MPa, and cool to obtain antibacterial and mildew-proof polyethylene plastic.

[0052] Comparative Example 4

[0053] 1 kg of polyethylene resin, 10 g of terminal hydrogen silicone oil, 20 g of polyurethane elastomer, and 4 g of antioxidant 1010 were put into a high-speed mixer and mixed evenly, then added to a two-roll mill, and 0.58 g of initiator dicumyl peroxide was added. It was kneaded at 185 °C for 6 min. Finally, the material was hot-pressed at 190 °C for 15 min in a flat vulcanizer under a pressure of 10 MPa, and then cooled to obtain antibacterial and mildew-proof polyethylene plastic.

[0054] The tensile properties of the polyethylene plastic were tested according to the standard of GB / T 1040.1-2018. The flexural properties were tested according to the standard of GB / T 9341-2008. The impact strength was tested according to the standard of GB / T 1843-2008.

[0055] Table 1 Mechanical Property Test of Polyethylene Plastic

[0056]

[0057] After testing, the polyethylene plastic in Comparative Example 1 did not add terminal alkenyl quaternary ammonium salt modified silicone oil and polyurethane elastomer. The tensile strength was only 12.6 MPa, the elongation at break was only 362.1%, and the flexural strength was 10.8 MPa.

[0058] In Examples 3-6, terminal alkenyl quaternary ammonium salt modified silicone oil and polyurethane elastomer were added. The modified silicone oil contains terminal alkenyl, which can provide more crosslinking sites. Under the crosslinking action of dicumyl peroxide, it undergoes chemical crosslinking with polyethylene, grafting flexible polysiloxane chain segments onto the polyethylene molecular chain. At the same time, after chemical crosslinking, the mechanical properties of the polyethylene plastic are better; and the terminal alkenyl quaternary ammonium salt modified silicone oil contains urethane structural units, which have good affinity and compatibility with the urethane structural units in the polyurethane elastomer. Crosslinking and bonding them to the molecular chain of polyethylene can act as a compatibilizer, improving the interfacial compatibility between the polyethylene matrix and the polyurethane elastomer, enabling the excellent polyurethane elastomer to play a better strengthening effect, and significantly improving the tensile properties and flexural strength of the polyethylene plastic.

[0059] In Comparative Example 2, only polyurethane elastomer was added, and the improvement in the tensile strength, elongation at break, and flexural strength of the polyethylene plastic was not significant. This is mainly because the compatibility between the polyurethane elastomer and the polyethylene resin is poor, making it difficult to effectively improve the mechanical properties of polyethylene.

[0060] Compared with Comparative Example 1, in Comparative Example 3, terminal alkenyl quaternary ammonium salt modified silicone oil was added. After chemical crosslinking with the polyethylene resin, the mechanical properties of the polyethylene plastic were significantly improved; however, without adding excellent polyurethane elastomer, the tensile properties and flexural strength of the polyethylene plastic were significantly lower than those of each example.

[0061] Compared with Example 3, in Comparative Example 4, terminal hydrogen silicone oil and polyurethane elastomer were added. The terminal hydrogen silicone oil does not contain terminal alkenyl groups, has fewer chemical cross-linking sites with polyethylene, and its cross-linking performance with the polyethylene resin is lower than that of Example 1. Moreover, the terminal hydrogen silicone oil does not contain urethane structural units and cannot act as a compatibilizer, so it cannot improve the interfacial compatibility between the polyethylene matrix and the polyurethane elastomer, resulting in the mechanical properties of the polyethylene resin being lower than those of Example 3.

[0062] According to the standard of QB / T 2591-2003, the antibacterial performance of polyethylene plastics was tested by the film sticking method. Escherichia coli or Staphylococcus aureus was used as the test strain, the polyethylene plastics of Examples 3-6 and Comparative Examples 2-4 were used as antibacterial test samples, and the polyethylene plastic of Comparative Example 1 was used as a blank control sample. The culture time during the antibacterial test was 24 h, and the temperature was 37 °C. According to the standard of GB 4789.2, the number of viable bacteria after cultivation was tested. The antibacterial rate R was calculated. R = (B - C) / B × 100%. B is the average number of recovered bacteria (cfu / sheet) of the blank control sample. C is the average number of recovered bacteria (cfu / sheet) of the antibacterial test sample.

[0063] Table 2 Antibacterial Performance Test of Polyethylene Plastics

[0064]

[0065] In Examples 3-6 and the terminal alkenyl quaternary ammonium salt modified silicone oil added in Comparative Example 3, which contains an organosilicon quaternary ammonium salt antibacterial structure, can adsorb on the cell membrane surface of microorganisms such as bacteria and molds through electrostatic interaction, and penetrate into the lipid layer and protein layer of the cell membrane, changing the cell membrane permeability, causing substances such as enzymes in the bacteria to escape, and inhibiting the metabolic process of bacteria and microorganisms, thus showing excellent bactericidal and mildew-proof performance.

[0066] In Comparative Example 2, the terminal alkenyl quaternary ammonium salt modified silicone oil was not added, and in Comparative Example 4, only terminal hydrogen silicone oil was added, which does not contain a quaternary ammonium salt antibacterial group, and both hardly have antibacterial performance.

Claims

1. A process for preparing antibacterial and mildew-proof polyethylene plastic, characterized in that: The preparation process is: Step S1, adding hydrogen-terminated silicone oil, N-methyldiethyl (isopropenylbenzylcarbamate) amine, polymerization inhibitor p-hydroxyanisole, and Karstedt catalyst into a reaction bottle, stirring evenly, introducing nitrogen, and performing a hydrosilylation reaction, adding methanol after the reaction, standing to separate, separating, and drying to obtain olefin-terminated modified silicone oil; The structural formula of the N-methyldiethyl (isopropenylbenzylcarbamate) amine is: ； Step S2, adding terminal olefin-modified silicone oil, benzyl halide, and N,N-dimethylformamide into a reaction bottle, stirring and mixing, carrying out quaternization reaction, concentrating the solution, adding methanol, standing for stratification, separating, and drying to obtain terminal olefin-modified quaternary ammonium salt silicone oil; Step S3, adding polyethylene resin, terminal olefin quaternary ammonium salt modified silicone oil, polyurethane elastomer, and antioxidant into a high-speed mixer and mixing, then adding into a double-roll mixer, adding initiator diisopropylbenzene peroxide, mixing, and finally hot pressing the materials in a flat vulcanizer, cooling, and obtaining an antibacterial and mildew-proof polyethylene plastic; The molar amount of N-methyldiethyl(isopropenylbenzylcarbamate)amine in S1 is 205-220% of the molar amount of the hydrogen-terminated silicone oil; The hydrosilylation reaction in S1 is carried out at 85-95° C. for 4-8 hours; The mass of the benzylic halide in S2 is 22-30% of the mass of the terminal olefin quaternary ammonium salt modified silicone oil; the benzylic halide is benzylic chloride or benzyl bromide; The quaternization reaction in S2 is carried out at 110-130° C. for 60-72 hours; The mass of the terminal olefin quaternary ammonium salt modified silicone oil and the polyurethane elastomer in S3 is 1-4% and 2-10% of the mass of the polyethylene resin respectively; The mixing temperature in S3 is 175-185° C. and the time is 6-10 min; the hot pressing temperature is 185-190° C., the pressure is 10-15 MPa and the time is 10-15 min.

2. The preparation process of the antibacterial and mildew-proof polyethylene plastic according to claim 1, characterized in that: The preparation process of N-methyldiethyl (isopropenyl benzyl carbamate) amine in S3 is: add 3-isopropenyl-α,α-dimethylbenzyl isocyanate and N-methyldiethanolamine to 1,4-dioxane, stir and react at 70-80° C. for 2-4 hours, concentrate the solution, and separate by silica gel column chromatography to obtain N-methyldiethyl (isopropenyl benzyl carbamate) amine; the molar amount of the 3-isopropenyl-α,α-dimethylbenzyl isocyanate is 200-220% of the molar amount of the N-methyldiethanolamine.

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