Preparation method of antibacterial EVA (Ethylene Vinyl Acetate) foamed sole

Abstract

The invention discloses a preparation method of an antibacterial EVA (Ethylene Vinyl Acetate) foamed sole, and belongs to the technical field of EVA soles. The preparation method comprises the following steps: mixing the ethylene-vinyl acetate copolymer, the ethylene propylene diene monomer, the compatilizer, the lubricant, the inorganic filler, the coupling agent and the auxiliary agent, pouring into an internal mixer, starting the internal mixer for primary internal mixing, adding the cross-linking agent and the foaming agent, starting the internal mixer again for secondary internal mixing, thinning twice on a roller machine, putting into a granulator, and granulating to obtain a finished product. Stirring and mixing, injecting into a shoe mold, molding and sizing to obtain the antibacterial EVA foamed sole. According to the present invention, the auxiliary agent contains the quaternary ammonium salt structure and the hindered phenol structure, and the chemical action exists between the auxiliary agent, the acetic acid-vinyl acetate copolymer and the ethylene propylene diene monomer, such that the auxiliary agent can be uniformly dispersed and stably exist in the EVA foaming shoe sole so as to provide the excellent aging resistance and the excellent antibacterial property for the long time, and further the EVA foaming shoe sole can provide the good anti-aging property and the good antibacterial property. And yellowing, cracking, bacterium breeding and peculiar smell generation are not easily caused.

Description

Technical Field

[0001] The invention belongs to the technical field of EVA soles, and in particular relates to a method for preparing an antibacterial EVA foamed sole. Background Art

[0002] EVA foam soles are popular among consumers due to their lightness, softness and beautiful appearance. However, the EVA foam soles on the market are prone to aging and yellowing after long-term sun exposure, and are prone to cracking after aging, which affects the appearance of the shoe body and the comfort of wearing.

[0003] In addition, there are a large number of small sweat glands on the human feet that secrete a large amount of sweat, making the soles easily absorb sweat and contaminate the metabolic waste and dandruff of the feet. Therefore, the soles are a warm, humid, nutrient-rich and ideal place for bacteria to grow. Shoes are not washed every day like clothes. Therefore, it is necessary to prepare antibacterial EVA foam soles. At the same time, the substances produced by the large-scale bacterial growth and metabolism will produce foot odor. Foot odor is mainly related to Staphylococcus, aerobic Corynebacterium and Bacillus. Bacteria convert the odorless secretions of the human body into volatile odor products. Ammonia is the product of bacterial decomposition of substances and is the main component of the smell of foot sweat. Summary of the invention

[0004] The purpose of the invention is to overcome the defects of the prior art and provide a method for preparing an antibacterial EVA foamed sole.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing an antibacterial EVA foam sole comprises the following steps: The raw materials of ethylene-vinyl acetate copolymer, ethylene propylene diene monomer rubber, compatibilizer, lubricant, inorganic filler, coupling agent and additive are mixed, poured into an internal mixer, started to perform the first internal mixer, then added with a cross-linking agent and a foaming agent, and started to perform the second internal mixer again, and then thinned twice on a roller machine, put into a granulator, granulated, stirred and mixed, injected into a shoe mold through a computer numerical control injection molding machine, and molded under the conditions of a shoe mold temperature of 178-182°C and a vulcanization time of 280-320s, and fixed in a constant temperature box to obtain an antibacterial EVA foam sole.

[0006] Furthermore, the raw materials of the antibacterial EVA foamed sole include, by weight: 55-65 parts of ethylene-vinyl acetate copolymer, 5-10 parts of ethylene propylene diene rubber, 5-10 parts of compatibilizer, 9-17 parts of inorganic filler, 2-4 parts of coupling agent, 1.5-3 parts of foaming agent, 1-2 parts of lubricant, 1-2 parts of auxiliary agent and 0.5-0.8 parts of cross-linking agent.

[0007] Furthermore, the compatibilizer is ethylene-octene copolymer.

[0008] Furthermore, the inorganic filler is a composition prepared by mixing talcum powder, titanium dioxide and zinc oxide in a weight ratio of 6:2:1.

[0009] Furthermore, the coupling agent is one or more of silane coupling agents.

[0010] Furthermore, the foaming agent is one or more of azodicarbonamide, sodium bicarbonate, and 4,4'-oxybisbenzenesulfonylhydrazide.

[0011] Furthermore, the lubricant is one or more of stearic acid, ethylene bisstearamide, magnesium stearate, zinc stearate, calcium stearate, paraffin, and polyethylene wax.

[0012] Furthermore, the auxiliary agent is prepared by the following steps: S1. The dried three-necked flask was purged with nitrogen for 30 min to exclude air and moisture, and then 3-bis(methylamino)propane and ether were added, stirred and dissolved, and epoxybutene was slowly added to the above three-necked flask through a constant pressure dropping funnel under nitrogen protection. After the addition was completed, the reaction was stirred at 80° C. for 4 h. After the reaction was completed, it was cooled to room temperature and distilled under reduced pressure. Purification by column chromatography (the eluent was a mixed solvent of benzene and ether, and the volume ratio of benzene and ether was 6:4), and the eluent was removed by distillation under reduced pressure to obtain intermediate 1; the amount ratio of 3-bis(methylamino)propane, epoxybutene and ether was 0.092 mol:0.08 mol:100 mL; Under heating and acid catalysis conditions, the amino group of 3-bis(methylamino)propane and the epoxy group of epoxybutene undergo the following chemical reaction, and the reaction process is shown below: S2. Replace the air in the three-necked reaction flask with nitrogen at room temperature, then add intermediate 1, triethylamine and diethyl ether, stir thoroughly until mixed, then slowly add tetradecane chloride, raise the temperature to 60°C after the addition, keep warm for 2 hours, and after the reaction is completed, distill under reduced pressure, purify by column chromatography (a mixed solvent of chloroform and diethyl ether is used as the eluent, and the volume ratio of chloroform and diethyl ether is 9:1), and distill under reduced pressure to obtain intermediate 2; the amount ratio of intermediate 1, tetradecane chloride, triethylamine and diethyl ether is 0.07 mol:0.072 mol:14.6 mL:120 mL; Triethylamine is used as an acid-binding agent. Under heating conditions, -NH- of intermediate 1 and -Cl of chlorotetradecane undergo a nucleophilic substitution reaction. The reaction process is shown below: S3. Add intermediate 2, pyridine and dimethyl sulfoxide to a dry four-necked flask under nitrogen protection, slowly add a mixed solution of 2,6-di-tert-butyl-4-bromomethylphenol and dimethyl sulfoxide after sufficient stirring, and then heat to 80°C for 4 hours of heat preservation. After the reaction is completed, vacuum distillation, column chromatography purification (the eluent is a mixed solvent of benzene and methanol, and the volume ratio of benzene and methanol is 19:1), and vacuum distillation to obtain an auxiliary agent. The dosage ratio of intermediate 2, 2,6-di-tert-butyl-4-bromomethylphenol, pyridine and dimethyl sulfoxide is 0.035 mol: 0.074 mol: 7.2 mL: 200 mL.

[0013] In the presence of pyridine and under heating conditions, the tertiary amine group of intermediate 2 and the -Br of 2,6-di-tert-butyl-4-bromomethylphenol undergo a nucleophilic substitution reaction. The reaction process is as follows: The additives contain quaternary ammonium salt structures with long carbon chains (14 carbons). Quaternary ammonium salts have good surface activity and can bind to and adsorb on the surface of bacterial cell membranes. The positive charge in the quaternary ammonium salt molecules can attract the negatively charged substances (such as phosphatidylcholine) in the bacterial cell membrane, thereby destroying the membrane structure of the bacterial cell and causing bacterial death. Quaternary ammonium salts can also disrupt the enzyme system inside bacteria and affect bacterial metabolism and growth. Quaternary ammonium salts change the protein structure by binding to anions such as chloride, acetate and phosphate in proteins, causing denaturation and inactivation of proteins in bacterial cells, destroying bacterial metabolism and growth, and ultimately causing bacterial death. In addition, the quaternary ammonium salt alkyl chain can insert into and cleave the cell membrane, causing the leakage of substances such as proteins, DNA and RNA in the cell, thereby killing bacteria. When the number of carbon atoms in the quaternary ammonium salt alkyl chain is 14, the quaternary ammonium salt antibacterial agent has the strongest antibacterial performance. Adding additives containing long-chain (14 carbon) quaternary ammonium antibacterial ingredients into EVA foam soles can effectively enhance the antibacterial effect of the soles, thereby avoiding the growth of bacteria and the generation of odors, making them safer and more comfortable, because bacteria such as Staphylococcus can convert odorless secretions of the human body into volatile odors.

[0014] The additive contains a hindered phenol structure. Since the hydroxyl group in the hindered phenol structure is restricted by spatial barriers, the hydrogen atom can easily fall off from the original molecular structure, thereby achieving the role of proton donation and combining with peroxyl radicals, alkyl radicals, hydroxyl radicals, etc., thereby terminating the oxygen aging reaction, thereby making the EVA foam sole have excellent anti-aging effects. The EVA foam sole is not prone to yellowing and cracking due to aging, thereby ensuring the beauty of the shoe body.

[0015] The additive contains terminal carbon-carbon double bonds, which can react chemically with the unreacted carbon-carbon double bonds at the ends of the ethylene-vinyl acetate copolymer and the unsaturated double bonds in the side chains of the EPDM rubber under the action of the cross-linking additive. The additive can then be grafted and cross-linked in the matrix resin, is not easy to migrate and fall off, is not easily affected by the external environment, can be uniformly dispersed and stably exist in the EVA foam sole, and exert antibacterial and anti-aging effects.

[0016] Furthermore, the cross-linking agent is one or both of dicumyl peroxide and di-tert-butyl peroxycumene.

[0017] The beneficial effects of the present invention are as follows: the additive of the present invention contains a quaternary ammonium salt structure and a hindered phenol structure, and there is a chemical reaction between the additive and the acetic acid-vinyl acetate copolymer and the ethylene propylene diene monomer rubber, so the additive can be uniformly dispersed and stably present in the EVA foamed sole, and thus the EVA foamed sole of the present invention has excellent aging resistance and antibacterial properties for a long time, and is not prone to yellowing, cracking, bacterial growth and odor. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1 Preparation of auxiliary agent, the specific steps are as follows: S1. A 250 mL dry three-necked flask was purged with nitrogen for 30 min to exclude air and moisture, and then 11.5 mL 3-bis(methylamino)propane and 100 mL ether were added, and the mixture was stirred to dissolve. Under nitrogen protection, 6.45 mL epoxybutene was slowly added to the three-necked flask through a constant pressure dropping funnel. After the addition was completed, the mixture was stirred and reacted at 80° C. for 4 h. After the reaction was completed, the mixture was cooled to room temperature, and the mixture was distilled under reduced pressure. The mixture was purified by column chromatography (a mixed solvent of benzene and ether was selected as the eluent, and the volume ratio of benzene and ether was 6:4). The eluent was removed by distillation under reduced pressure to obtain intermediate 1. S2, replace the air in a 250mL three-necked reaction flask with nitrogen at room temperature, then add 12.1g of intermediate 1, 14.6mL of triethylamine and 120mL of ether, stir thoroughly until mixed, then slowly add 19.5mL of tetradecyl chloride, raise the temperature to 60°C after the addition is complete, keep the temperature for reaction for 2h, after the reaction is completed, distill under reduced pressure, purify by column chromatography (the eluent is a mixed solvent of chloroform and ether, the volume ratio of chloroform and ether is 9:1), and distill under reduced pressure to obtain intermediate 2; S3. Under nitrogen protection, add 12.9 g of intermediate 2, 7.2 mL of pyridine and 160 mL of dimethyl sulfoxide into a 500 mL dry four-necked flask, stir thoroughly, then slowly add a mixed solution of 22.1 g of 2,6-di-tert-butyl-4-bromomethylphenol and 40 mL of dimethyl sulfoxide, then raise the temperature to 80°C and keep the reaction for 4 hours. After the reaction is completed, distill under reduced pressure, purify by column chromatography (the eluent is a mixed solvent of benzene and methanol, and the volume ratio of benzene and methanol is 19:1), and distill under reduced pressure to obtain an auxiliary agent.

[0020] Example 2 The antibacterial EVA foam sole is prepared, and the specific steps are as follows: 55 parts of ethylene-vinyl acetate copolymer, 5 parts of ethylene propylene diene monomer rubber, 5 parts of ethylene-octene copolymer, 0.5 parts of stearic acid, 0.5 parts of ethylene bis stearamide, 6 parts of talc, 2 parts of titanium dioxide, 1 part of zinc oxide, 2 parts of vinyl trimethoxy silane, and 1 part of the auxiliary agent prepared in Example 1 were mixed and poured into an internal mixer, the internal mixer was started for the first internal mixing, 0.5 parts of dicumyl peroxide and 1.5 parts of azodicarbonamide were added, the internal mixer was started again for the second internal mixing, and then thinned on a roller machine for 2 times, put into a granulator, granulated, stirred and mixed, injected into a shoe mold through a computer numerical control injection molding machine, and molded under the conditions of a shoe mold temperature of 178° C. and a vulcanization time of 280 s, and shaped in a constant temperature box to obtain an antibacterial EVA foam sole.

[0021] Example 3 The antibacterial EVA foam sole is prepared, and the specific steps are as follows: 60 parts of ethylene-vinyl acetate copolymer, 7 parts of ethylene propylene diene monomer rubber, 8 parts of ethylene-octene copolymer, 1.2 parts of zinc stearate, 9 parts of talc, 3 parts of titanium dioxide, 1.5 parts of zinc oxide, 3 parts of vinyl triethoxy silane, and 1.6 parts of the additives prepared in Example 1 were mixed and poured into an internal mixer, the internal mixer was started for the first internal mixing, 0.6 parts of dicumyl peroxide and 2 parts of sodium bicarbonate were added, the internal mixer was started again for the second internal mixing, and then thinned twice on a roller machine, put into a granulator, granulated, stirred and mixed, injected into a shoe mold through a computer numerical control injection molding machine, and molded under the conditions of a shoe mold temperature of 180° C. and a vulcanization time of 300 s, and shaped in a constant temperature box to obtain an antibacterial EVA foam sole.

[0022] Example 4 The antibacterial EVA foam sole is prepared, and the specific steps are as follows: 65 parts of ethylene-vinyl acetate copolymer, 10 parts of ethylene propylene diene monomer rubber, 10 parts of ethylene-octene copolymer, 1 part of zinc stearate, 1 part of polyethylene wax, 12 parts of talc, 4 parts of titanium dioxide, 2 parts of zinc oxide, 4 parts of vinyltrimethoxysilane, and 2 parts of the additives prepared in Example 1 were mixed and poured into an internal mixer, and the internal mixer was started for the first internal mixing, and then 0.8 parts of di-tert-butyl peroxyisopropylbenzene and 3 parts of azodicarbonamide were added, and the internal mixer was started again for the second internal mixing, followed by thinning on a roller machine for 2 times, and the mixture was put into a granulator for granulation, stirred and mixed, and injected into a shoe mold through a computer numerically controlled injection molding machine, and molded under the conditions of a shoe mold temperature of 182° C. and a vulcanization time of 320 s, and shaped in a constant temperature box to obtain an antibacterial EVA foam sole.

[0023] Comparative Example 1 Prepare EVA foam sole, the specific steps are as follows: The remaining steps remain unchanged, and the auxiliary agent in Example 4 is replaced by 1 part of antioxidant 1076 and 1 part of antibacterial agent dimethyl dioctadecyl ammonium chloride to prepare an EVA foam sole.

[0024] Comparative Example 2 Prepare EVA foam sole, the specific steps are as follows: The remaining steps remain unchanged, and the auxiliary agent in Example 4 is removed to prepare the EVA foamed sole.

[0025] Performance Testing The EVA foam soles prepared in Examples 2-4 and Comparative Examples 1-2 were made into test samples, placed in a special plastic bag, and then 1 mL of inoculated bacterial solution was added, and air equivalent to the amount of inoculated bacterial solution was introduced into the plastic bag, and the plastic bag was heat-sealed and shaken at 37°C for 24 hours. The number of surviving bacteria was determined by the dilution plate culture method, and the antibacterial rate was calculated to test the antibacterial rate of the EVA foam soles against Escherichia coli and Staphylococcus aureus. Under the same conditions, the antibacterial rate of the EVA foam soles prepared in Examples 2-4 and Comparative Examples 1-2 was tested after washing 30 times, and the test results are shown in Table 1: Table 1 It can be seen from the test results in Table 1 that the EVA foam soles prepared in Examples 2-4 of the present invention have a more excellent and stable antibacterial effect; from the test results of Comparative Example 1, it can be seen that when the existing antibacterial agent is used as an additive and added to the EVA foam sole, although the antibacterial effect is excellent, the antibacterial stability is poor, which is far inferior to the antibacterial stability of the EVA foam soles of Examples 2-4 of the present invention.

[0026] The EVA foamed soles prepared in Examples 2-4 and Comparative Examples 1-2 were made into test samples, and the tensile strength and elongation at break were tested. The samples were aged at (100±2)°C×12h. After aging, the tensile strength and elongation at break were tested under the same conditions. The test standards were based on GB / T528-2009 and GB / T3512-2001. The test results are shown in Table 2: Table 2 It can be seen from the test results in Table 2 that the EVA foam soles prepared in Examples 2-4 of the present invention have a more excellent and stable anti-aging effect; from the test results of Comparative Example 1, it can be seen that when the existing antioxidant 1076 is used as an additive and added into the EVA foam sole, the anti-aging stability is poor, which is far inferior to the anti-aging stability of the EVA foam soles of Examples 2-4 of the present invention.

[0027] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0028] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing an antibacterial EVA foam sole, It is characterized in that The following steps are involved: The raw materials of ethylene-vinyl acetate copolymer, ethylene propylene diene monomer rubber, compatibilizer, lubricant, inorganic filler, coupling agent and additive are mixed, poured into a mixer for internal mixing, and then a cross-linking agent and a foaming agent are added, and the mixture is internally mixed again, and then thinned on a roller machine, put into a granulator, granulated, stirred, injected into a shoe mold, formed, and shaped to obtain an antibacterial EVA foam sole; Wherein, the auxiliary agent is prepared by the following steps: S1, nitrogen purged the flask, added 3-bis(methylamino)propane and ether, stirred, added epoxybutene, reacted at 80°C for 4h, cooled, distilled under reduced pressure, purified by column chromatography, and distilled under reduced pressure to obtain intermediate 1; S2, replace the air in the bottle with nitrogen, add intermediate 1, triethylamine and diethyl ether, stir, add tetradecane chloride, react at 60°C for 2h, distill under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain intermediate 2; S3. Under nitrogen protection, add intermediate 2, pyridine and dimethyl sulfoxide into a flask, stir and add 2,6-di-tert-butyl-4-bromomethylphenol and dimethyl sulfoxide, react at 80° C. for 4 h, distill under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain an auxiliary agent.

2. A method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The usage ratio of 3-bis(methylamino)propane, epoxybutene and diethyl ether in step S1 is 0.092 mol:0.08 mol:100 mL.

3. A method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The usage ratio of intermediate 1, tetradecane chloride, triethylamine and diethyl ether in step S2 is 0.07 mol: 0.072 mol: 14.6 mL: 120 mL.

4. A method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The usage ratio of the intermediate 2, 2,6-di-tert-butyl-4-bromomethylphenol, pyridine and dimethyl sulfoxide in step S3 is 0.035 mol: 0.074 mol: 7.2 mL: 200 mL.

5. A method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The raw materials of the antibacterial EVA foamed sole include, by weight: 55-65 parts of ethylene-vinyl acetate copolymer, 5-10 parts of ethylene propylene diene rubber, 5-10 parts of compatibilizer, 9-17 parts of inorganic filler, 2-4 parts of coupling agent, 1.5-3 parts of foaming agent, 1-2 parts of lubricant, 1-2 parts of auxiliary agent and 0.5-0.8 parts of crosslinking agent.

6. A method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The compatibilizer is ethylene-octene copolymer.

7. The method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The inorganic filler is a composition prepared by mixing talcum powder, titanium dioxide and zinc oxide in a weight ratio of 6:2:

1.

8. The method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The coupling agent is one or more of silane coupling agents.

9. The method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The foaming agent is one or more of azodicarbonamide, sodium bicarbonate, and 4,4'-oxybisbenzenesulfonyl hydrazide.

10. The method for preparing an antibacterial EVA foam sole according to claim 1, It is characterized in that The lubricant is one or more of stearic acid, ethylene bisstearamide, magnesium stearate, zinc stearate, calcium stearate, paraffin, and polyethylene wax; the crosslinking agent is one or two of diisopropylbenzene peroxide and di-tert-butyl peroxyisopropylbenzene.

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