Small-multiplying-power EVA composite anti-shrinkage elastomer and preparation method thereof

Abstract

The invention belongs to the technical field of EVA foaming, and provides a small-magnification EVA composite anti-shrinkage elastomer and a preparation method thereof.The small-magnification EVA composite anti-shrinkage elastomer is prepared from, by weight, 15-20 parts of EVA, 25-35 parts of SEBS, 10-15 parts of SSBR, 10-20 parts of OBC, 3-6 parts of BIIR, 40-55 parts of white oil, 4-8 parts of modified nano-silica, 0.1-0.2 part of silicone powder, 0.5-1.5 parts of a cross-linking agent, 2-3 parts of a foaming agent and 1-2 parts of zinc oxide. 0.4-0.8 part of stearic acid, 1-3 parts of an antibacterial agent and 0.5-1 part of an antioxidant. The EVA composite anti-shrinkage elastomer improves the hand feeling and texture, is low in self weight, excellent in antibacterial property and good in skid resistance and wear resistance, can be used for manufacturing shoe materials, and is high in market value.

Description

Technical Field

[0001] The invention belongs to the technical field of EVA foaming, and in particular relates to a small-ratio EVA composite anti-shrinkage elastomer and a preparation method thereof. Background Art

[0002] As a versatile thermoplastic resin, ethylene-vinyl acetate copolymer (EVA) occupies an important position in the plastics industry due to its excellent flexibility, elasticity and stress cracking resistance.

[0003] The plasticity and processability of EVA make it an ideal choice for shoe manufacturing. EVA shoe materials are favored by the market for their light weight, softness, good elasticity and shock absorption performance. However, EVA foam materials also face some challenges in practical applications, such as easy deformation, insufficient wear resistance, poor anti-slip performance and hardening in low temperature environments. Polystyrene-ethylene / butylene-styrene (SEBS), as a thermoplastic elastomer, stands out for its low shrinkage, high plasticity, excellent high elasticity and easy processing. The high strength and toughness of SEBS, combined with its excellent aging resistance and chemical stability, make it an ideal choice for improving the performance of EVA. SEBS can be used as a modified material with impact resistance, anti-slip, wear resistance, compression resistance and cold resistance, and is widely used in various thermoplastic rubbers and plastics. Blending SEBS with EVA can not only significantly improve the mechanical properties of EVA foam materials (such as enhancing its wear resistance and anti-slip properties), but also improve its flexibility under low temperature conditions, thereby expanding the application range of EVA materials.

[0004] Chinese patent CN 108892853 B discloses a heat-shrinkage-resistant rubber-plastic blended foamed midsole, which is composed of the following components: ethylene-vinyl acetate copolymer, styrene-butadiene rubber, ethylene-propylene-diene rubber, olefin block copolymer, talcum powder, zinc oxide, zinc stearate, diisopropylbenzene peroxide, azodicarbonamide, and wood cellulose. The foamed rubber-plastic midsole material prepared by this invention has good heat-shrinkage resistance, low compression deformation rate, and good tensile and rebound properties; however, it does not involve research on antibacterial properties.

[0005] Therefore, there is an urgent need for a small-ratio EVA composite anti-shrinkage elastomer with excellent antibacterial property and good anti-slip and wear resistance. Summary of the invention

[0006] In view of the existing technical problems, the purpose of the present invention is to provide a small-ratio EVA composite anti-shrinkage elastomer and a preparation method thereof. The EVA composite anti-shrinkage elastomer of the present invention has improved hand feel and texture, low dead weight, excellent antibacterial property, good anti-slip and wear resistance, can be used to make shoe materials, and has high market value.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides a small-ratio EVA composite anti-shrinkage elastomer, which comprises the following raw materials in parts by weight: 15-20 parts of EVA, 25-35 parts of SEBS, 10-15 parts of SSBR, 10-20 parts of OBC, 3-6 parts of BIIR, 40-55 parts of white oil, 4-8 parts of modified nano silicon dioxide, 0.1-0.2 parts of silicone powder, 0.5-1.5 parts of cross-linking agent, 2-3 parts of foaming agent, 1-2 parts of zinc oxide, 0.4-0.8 parts of stearic acid, 1-3 parts of antibacterial agent and 0.5-1 parts of antioxidant.

[0009] The reaction mechanism and effects of the present invention are as follows:

[0010] 1. The guanidine compound 1-[4-(trifluoromethyl)phenyl]biguanide hydrochloride in the present invention carries a positive charge, which generates a strong electrostatic attraction with the negative charge on the surface of bacteria. This effect restricts the normal physiological activities of bacteria, disturbs the respiratory mechanism of bacteria, and makes it impossible to carry out energy metabolism normally, thereby achieving the antibacterial function; in addition, the adsorption of guanidine compounds leads to uneven charge distribution on the surface of bacterial cell membranes, causing local deformation, damage or rupture of cell membranes, causing leakage of proteins and other substances in cells, causing cell dysfunction, and ultimately leading to the death of bacteria. However, guanidine antibacterial agents have the common defect of poor thermal stability of organic antibacterial agents. The applicant has synthesized a new antibacterial agent with excellent antibacterial properties and high temperature resistance, making it suitable for plastic processing scenarios.

[0011] On the one hand, the antibacterial agent uses 1-[4-(trifluoromethyl)phenyl]biguanide hydrochloride with a benzene ring structure as a raw material, which makes it have good antibacterial properties and improves heat resistance; on the other hand, the antibacterial agent forms a five-membered nitrogen-containing heterocyclic ring, a triazole group, during the synthesis process. The triazole group has good high-temperature stability and can bind to a variety of enzymes and receptors, showing antibacterial, antifungal, antiviral and other biological activities. The triazole group can also be used as an ultraviolet absorber to improve the photostability of the material. Furthermore, the antibacterial agent structure also contains a fluorine group, which reduces the surface energy of the antibacterial agent and causes it to migrate to the outer surface during the foaming process. The outer layer that is easily exposed to bacteria has a higher content of the antibacterial agent.

[0012] 2. On the one hand, nano-silica contains multiple hydroxyl groups, and the hydroxyl group and the ethoxy group at one end of the silane coupling agent will react and combine. The modified nano-silica has better dispersibility and better compatibility with the system, which can better play the wear-resistant role of nano-silica in shoe materials, further improve the tensile strength and tear strength of EVA foam materials, and enhance the thermal stability of EVA foam materials.

[0013] On the other hand, the introduction of the polar substance N,N'-(4,4'-methylenediphenyl)bismaleimide can further enhance the compatibility of nano-silica and EVA. At the same time, the unsaturated double bonds may participate in bridging and cross-linking during the foaming process, showing good resistance to thermal shrinkage. In addition, N,N'-(4,4'-methylenediphenyl)bismaleimide has the effect of strengthening and toughening, which makes the EVA foamed sole have better dimensional stability, thereby improving the anti-slip performance.

[0014] 3. SEBS elastomer is favored for its light weight, softness and excellent tensile properties. When mixed with EVA and other auxiliary materials, it can significantly improve the efficiency of the foaming process and reduce the required foaming time. At the same time, SEBS can also enhance the elastic properties of EVA materials, reduce the weight of the sole and improve its compression performance. In addition, the mixture of EVA and SEBS can alleviate the common plastic feel of EVA foam materials, thereby improving the touch and overall texture of the product.

[0015] In some embodiments, the antibacterial agent has the following structural formula:

[0016]

[0017] In some embodiments, the method for preparing the antibacterial agent comprises the following steps:

[0018] (1) Add 3-bromo-2,2-dimethyl-1-propanol, sodium azide and dimethyl sulfoxide to a first reaction kettle, heat to 100-120° C., react for 16-24 hours, cool, add deionized water, extract with ethyl acetate 2-3 times, wash 2-3 times, dry, and filter to obtain compound 1;

[0019] (2) Add 1-[4-(trifluoromethyl)phenyl]biguanidine hydrochloride and dimethyl sulfoxide to a second reaction kettle, heat to 50-70° C., stir for 15-30 min, cool, add dropwise a dimethyl sulfoxide solution of 4-bromobutyronitrile, stir for 10-16 h, wash 2-3 times, and dry to obtain compound 2;

[0020] (3) adding N,N-dimethylformamide to the third reaction kettle, degassing for 15-25 min, adding cuprous bromide and pentamethyldiethylenetriamine, degassing for 10-15 min, and obtaining a solution;

[0021] (4) Compound 1 obtained in step (1) and compound 2 obtained in step (2) are mixed, and N,N-dimethylformamide is added, and the mixture is degassed for 15-25 min. The solution obtained in step (3) is added and reacted for 1-1.5 h. Deionized water is then added to precipitate the mixture, and the mixture is centrifuged to obtain a solid;

[0022] (5) Dissolving the solid obtained in step (4) in dimethyl sulfoxide, and then adding deionized water to precipitate, repeating the process three times, and then dissolving the precipitated substance in dimethyl sulfoxide, and drying to obtain an antibacterial agent.

[0023] In some embodiments, the molar ratio of 1-[4-(trifluoromethyl)phenyl]biguanidine hydrochloride to 4-bromobutyronitrile in step (2) is 1:(1.1-1.6).

[0024] In some embodiments, the molar ratio of compound 1 to compound 2 in step (4) is (1.2-1.8):1.

[0025] Preferably, the molar ratio of 3-bromo-2,2-dimethyl-1-propanol to sodium azide in step (1) is 1:(1.1-1.5).

[0026] In some embodiments, the method for preparing the modified nano-silica comprises the following steps:

[0027] S1. The silane coupling agent KH-550 was added to the first reaction vessel containing the mixed solvent and stirred for 30-45 min to obtain a hydrolyzed solution;

[0028] S2. Take the hydrolysis solution obtained in step S1 and add the nano-silica to a second reaction vessel, heat to 50-60 ° C, stir for 3-4h, wash with anhydrous ethanol 3-4 times, centrifuge, and remove the powder;

[0029] S3. Take the powder obtained in step S2 and N,N'-(4,4'-methylenediphenyl)bismaleimide and ball-mill for 1-3 hours, and dry at 50-80°C for 2-4 hours to obtain modified nano-silica.

[0030] In some embodiments, the mass ratio of the silane coupling agent KH-550 to the nano-silicon dioxide in the hydrolysis solution in step S2 is (0.05-0.2):1.

[0031] In some embodiments, the mass ratio of the N,N'-(4,4'-methylenediphenyl)bismaleimide in step S3 to the nano-silicon dioxide in step S2 is (0.02-0.1):1.

[0032] Preferably, the particle size of the nano-silicon dioxide in step S1 is 10-100 nm.

[0033] In some embodiments, the VA content of the EVA is 15-25 wt %.

[0034] In some embodiments, the cross-linking agent is dicumyl peroxide and / or 1,4-di-tert-butylperoxycumene.

[0035] In some embodiments, the foaming agent is a medium-low temperature foaming agent, and the decomposition temperature is below 165°C.

[0036] In some embodiments, the antioxidant is antioxidant 1076 and / or antioxidant 168.

[0037] Preferably, the antioxidants are antioxidant 1076 and antioxidant 168, and the mass ratio of the antioxidants is (2-6):1.

[0038] Another aspect of the present invention provides a method for preparing a small-ratio EVA composite anti-shrinkage elastomer, comprising the following steps:

[0039] 1. Add SEBS, SSBR, OBC, BIIR, white oil, modified nano-silicon dioxide, silicone powder, stearic acid, antibacterial agent and antioxidant into a twin-screw extruder for extrusion granulation to obtain a modified elastomer;

[0040] 2. The modified elastomer obtained in step 1, EVA, a cross-linking agent, a foaming agent and zinc oxide are mixed and then internally kneaded, and then open-mixed and granulated to obtain the EVA composite anti-shrinkage elastomer.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The EVA composite anti-shrinkage elastomer of the present invention has improved hand feel and texture, low dead weight, excellent antibacterial property, good anti-slip and wear resistance, can be used to make shoe materials, and has high market value.

[0043] 2. The present invention synthesizes a new antibacterial agent with excellent antibacterial properties and high temperature resistance, making it suitable for plastic processing scenarios. The new antibacterial agent has good antibacterial properties and improved heat resistance; and the triazole group formed during the synthesis process will not only bind to a variety of enzymes and receptors, showing antibacterial, antifungal, antiviral and other biological activities, but also can be used as an ultraviolet absorber to improve the light stability of the material.

[0044] 3. The modified nano-silicon dioxide of the present invention has better dispersibility, can better play the anti-skid and wear-resistant role of nano-silicon dioxide in shoe materials, can further improve the tensile strength and tear strength of EVA foam materials, and can also enhance the thermal stability of EVA foam materials; in addition, the introduction of the polar substance N,N'-(4,4'-methylenediphenyl) bismaleimide can enhance the compatibility of nano-silicon dioxide and EVA, and its strengthening and toughening effect makes the EVA foam sole have better dimensional stability. DETAILED DESCRIPTION

[0045] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, rather than to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0046] According to the ratios of the raw materials and the preparation methods specified in the following examples and comparative examples, various EVA composite anti-shrinkage elastomers were prepared.

[0047] In order to facilitate those skilled in the art to implement the present invention, some raw material manufacturers of the embodiments and comparative examples are described as follows:

[0048] Nano-silicon dioxide: purchased from Shanghai Waidian International Trading Co., Ltd., particle size 20 nm, model H-20;

[0049] Azodicarbonamide: purchased from Tianjin Zhongke New Materials Co., Ltd., with a decomposition temperature of 145±5℃;

[0050] EVA: purchased from Shanghai Yesu International Trading Co., Ltd., VA content 18wt%, model UE629;

[0051] OBC: purchased from Dongguan Xinrui New Materials Co., Ltd., Dow OBC, model XH4021CFMBMT;

[0052] Silicone powder: purchased from Guangzhou Yinuo Chemical Technology Co., Ltd., model RM4-7051;

[0053] Other raw materials are not specially specified and can be purchased from the market.

[0054] Preparation Example 1

[0055] The preparation method of antibacterial agent A comprises the following steps:

[0056] (1) 0.5 mol of 3-bromo-2,2-dimethyl-1-propanol, 0.65 mol of sodium azide and 325 ml of dimethyl sulfoxide were added to a first reaction kettle, heated to 110° C., reacted for 20 hours, cooled to room temperature, added with 200 ml of deionized water, extracted with 600 ml of ethyl acetate, and the extraction was repeated 3 times. The organic phase obtained by the extraction was then washed with a saturated sodium chloride solution, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed to obtain compound 1;

[0057] (2) 0.1 mol of 1-[4-(trifluoromethyl)phenyl]biguanide hydrochloride and 100 ml of dimethyl sulfoxide were added to a second reaction kettle, heated to 60°C, stirred for 20 min, cooled to room temperature, and 135 ml of a 1 mol / L 4-bromobutyronitrile dimethyl sulfoxide solution was added dropwise. The mixture was stirred for 12 h, washed with acetone three times, and dried at 60°C for 20 h to obtain compound 2;

[0058] (3) 30 ml of N,N-dimethylformamide was added to the third reaction kettle, and the mixture was degassed with nitrogen for 20 min. 0.6 g of cuprous bromide and 1 ml of pentamethyldiethylenetriamine were added, and the mixture was degassed with nitrogen for 10 min to obtain a solution.

[0059] (4) 0.75 mol of compound 1 obtained in step (1) and 0.5 mol of compound 2 obtained in step (2) were mixed, and 500 ml of N,N-dimethylformamide was added, and the mixture was degassed with nitrogen for 20 min. 20 ml of the solution obtained in step (3) was added and reacted for 1 h. Deionized water was added to precipitate, and the mixture was centrifuged to obtain a solid;

[0060] (5) The solid obtained in step (4) was dissolved in 500 ml of dimethyl sulfoxide, and deionized water was added to precipitate. This was repeated three times. The precipitated substance was then dissolved in dimethyl sulfoxide at a solid-liquid ratio of 1 g:7 ml, and dried at 75°C for 20 h to obtain antibacterial agent A.

[0061] Preparation Example 2

[0062] The preparation method of antibacterial agent B is the same as that of Preparation Example 1, except that 180 ml of 1 mol / L 4-bromobutyronitrile dimethyl sulfoxide solution is added dropwise in step (2).

[0063] Preparation Example 3

[0064] The preparation method of antibacterial agent C is the same as that of Preparation Example 1, except that the amount of compound 1 added in step (4) is 1 mol.

[0065] Preparation Example 4

[0066] The preparation method of modified nano-silicon dioxide A comprises the following steps:

[0067] S1. 0.6 g of silane coupling agent KH-550 was added to a first reaction vessel containing a mixed solvent (2 ml of deionized water and 20 ml of ethanol) and stirred for 30 min to obtain a hydrolyzed solution;

[0068] S2. The hydrolyzed solution obtained in step S1 and 5 g of nano-silica were added to a second reaction vessel, heated to 55 ° C, stirred for 3 h, washed with anhydrous ethanol three times, centrifuged at 8000 r / min for 6 min, and the powder was removed;

[0069] S3. Take 5 g of the powder obtained in step S2 and 0.3 g of N,N'-(4,4'-methylenediphenyl)bismaleimide, ball-mill for 2 h, and dry at 65° C. for 3 h to obtain modified nano-silica A.

[0070] Preparation Example 5

[0071] The preparation method of modified nano-silica B is the same as that of Preparation Example 4, except that in step S1, 0.2 g of silane coupling agent KH-550 is added to a first reaction container filled with a mixed solvent (2 ml of deionized water and 20 ml of ethanol), and stirred for 30 min to obtain a hydrolysis solution.

[0072] Preparation Example 6

[0073] The preparation method of modified nano-silica C is the same as that of Preparation Example 4, except that the amount of N,N'-(4,4'-methylenediphenyl)bismaleimide added is 0.6 g.

[0074] Example 1

[0075] A small-ratio EVA composite anti-shrinkage elastomer comprises the following raw materials, measured by weight: 17.5 parts of EVA, 30 parts of SEBS, 12.5 parts of SSBR, 15 parts of OBC, 4.5 parts of BIIR, 47.5 parts of white oil, 6 parts of modified nano silicon dioxide A, 0.15 parts of silicone powder, 1 part of dicumyl peroxide, 2.5 parts of azodicarbonamide, 1.5 parts of zinc oxide, 0.6 parts of stearic acid, 2 parts of antibacterial agent A, 0.6 parts of antioxidant 10760.6 parts and 0.15 parts of antioxidant 1680.15 parts.

[0076] The preparation method of the EVA composite anti-shrinkage elastomer of the present embodiment comprises the following steps:

[0077] 1. Add SEBS, SSBR, OBC, BIIR, white oil, modified nano-silica A, silicone powder, stearic acid, antibacterial agent A, antioxidant 1076 and antioxidant 168 into a twin-screw extruder, adjust the screw speed to 15r / s, and the temperature of each section of the screw to 150℃-190℃-190℃-200℃-200℃-200℃-190℃-190℃-180℃-170℃, and extrude and granulate to obtain a modified elastomer;

[0078] 2. The modified elastomer obtained in step 1, EVA, diisopropylbenzene peroxide, azodicarbonamide and zinc oxide are mixed and then kneaded. The kneading temperature is adjusted to 110° C. and maintained for 20 minutes. Then, the mixture is open-mixed and granulated to obtain the EVA composite anti-shrinkage elastomer.

[0079] Example 2

[0080] A small-ratio EVA composite anti-shrinkage elastomer comprises the following raw materials, measured by weight: 15 parts of EVA, 25 parts of SEBS, 10 parts of SSBR, 10 parts of OBC, 3 parts of BIIR, 40 parts of white oil, 4 parts of modified nano silicon dioxide A, 0.1 parts of silicone powder, 0.5 parts of dicumyl peroxide, 2 parts of azodicarbonamide, 1 part of zinc oxide, 0.4 parts of stearic acid, 1 part of antibacterial agent A, 0.375 parts of antioxidant 1076 and 0.125 parts of antioxidant 168.

[0081] The preparation method of the EVA composite anti-shrinkage elastomer in this embodiment is the same as that in Example 1.

[0082] Example 3

[0083] A small-ratio EVA composite anti-shrinkage elastomer comprises the following raw materials, measured in parts by weight: 20 parts of EVA, 35 parts of SEBS, 15 parts of SSBR, 20 parts of OBC, 6 parts of BIIR, 55 parts of white oil, 8 parts of modified nano silicon dioxide A, 0.2 parts of silicone powder, 1.5 parts of dicumyl peroxide, 3 parts of azodicarbonamide, 2 parts of zinc oxide, 0.8 parts of stearic acid, 3 parts of antibacterial agent A, 10760.85 parts of antioxidant and 1680.15 parts of antioxidant.

[0084] The preparation method of the EVA composite anti-shrinkage elastomer in this embodiment is the same as that in Example 1.

[0085] Example 4

[0086] A small-ratio EVA composite anti-shrinkage elastomer and a preparation method thereof, wherein the specific implementation manner is the same as that of Example 1, except that an equal amount of antibacterial agent B is used to replace antibacterial agent A.

[0087] Example 5

[0088] A small-ratio EVA composite anti-shrinkage elastomer and a preparation method thereof, wherein the specific implementation manner is the same as that of Example 1, except that an equal amount of antibacterial agent C is used to replace antibacterial agent A.

[0089] Example 6

[0090] A small-ratio EVA composite anti-shrinkage elastomer and a preparation method thereof, the specific implementation manner is the same as that of Example 1, except that an equal amount of modified nano-silicon dioxide B is used to replace modified nano-silicon dioxide A.

[0091] Example 7

[0092] A small-ratio EVA composite anti-shrinkage elastomer and a preparation method thereof, the specific implementation manner is the same as that of Example 1, except that an equal amount of modified nano-silicon dioxide C is used to replace modified nano-silicon dioxide A.

[0093] Comparative Example 1

[0094] A small-ratio EVA composite anti-shrinkage elastomer and a preparation method thereof, wherein the specific implementation manner is the same as that of Example 1, except that an equal amount of 1-[4-(trifluoromethyl)phenyl]biguanidine hydrochloride is used to replace the antibacterial agent A.

[0095] Comparative Example 2

[0096] A small-ratio EVA composite anti-shrinkage elastomer and a preparation method thereof, wherein the specific implementation manner is the same as that of Example 1, except that an equal amount of nano-silica is used to replace modified nano-silica A.

[0097] Effect evaluation:

[0098] The EVA composite anti-shrinkage elastomers prepared in the above Examples 1-7 and Comparative Examples 1-2 were tested and analyzed, and the specific results are shown in Table 1.

[0099] Performance Test:

[0100] (1) Antimicrobial test: in accordance with ISO 20150:2019;

[0101] (2) Thermal shrinkage test: in accordance with standard HG / T 2874-1997;

[0102] (3) Wear resistance test: in accordance with standard GB / T 3903.2-2008.

[0103] Table 1

[0104] Serial number Antibacterial rate / % Thermal shrinkage / % Wear resistance(mm) Example 1 99.2 1.6 7.3 Example 2 98.5 2.0 7.6 Example 3 99.3 1.8 7.5 Example 4 96.4 2.2 7.5 Example 5 95.2 1.9 7.4 Example 6 99.0 2.8 8.3 Example 7 99.1 1.8 8.2 Comparative Example 1 88.6 2.4 7.6 Comparative Example 2 99.0 3.0 9.0

[0105] From the results in Table 1, it can be seen that the EVA composite anti-shrinkage elastomer prepared in Examples 1-3 has good antibacterial properties, low thermal shrinkage rate and good wear resistance.

[0106] Compared with Example 1, in the preparation of the antibacterial agent, the molar ratio of 1-[4-(trifluoromethyl)phenyl]biguanidine hydrochloride and 4-bromobutyronitrile is changed, which may form a large amount of over-branched by-products, which may affect the crystallization behavior, fluidity and processing temperature of the EVA material, and further affect the antibacterial properties and thermal shrinkage rate of the EVA composite anti-shrinkage elastomer.

[0107] Compared with Example 1, when preparing the antibacterial agent, the molar ratio of compound 1 to compound 2 is changed, which may produce more by-products, affect the purity of the final synthesized antibacterial agent, reduce the antibacterial property of the EVA composite anti-shrinkage elastomer, and further affect the thermal shrinkage rate.

[0108] Compared with Example 1, when preparing the modified nano-silica, Example 6 changes the mass ratio of the silane coupling agent to the nano-silica, resulting in poor dispersibility and reduced wear resistance and heat shrinkage of the EVA composite anti-shrinkage elastomer.

[0109] Compared with Example 1, in Example 7, when preparing modified nano-silica, the mass ratio of N,N'-(4,4'-methylenediphenyl)bismaleimide to nano-silica was changed, the compatibility was weakened, and the wear resistance of the EVA composite anti-shrinkage elastomer was reduced, while the thermal shrinkage rate did not increase significantly due to the enhanced cross-linking effect.

[0110] Compared with Example 1, Comparative Example 1 uses an equal amount of 1-[4-(trifluoromethyl)phenyl]biguanide hydrochloride to replace antibacterial agent A, which has insufficient heat resistance and greatly reduces its antibacterial activity.

[0111] Compared with Example 1, in Comparative Example 2, an equal amount of commercially available nano-silica was used to replace the modified nano-silica A, which resulted in poor dispersibility and reduced wear resistance and heat shrinkage of the EVA composite anti-shrinkage elastomer.

[0112] The above is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present application. Although the present application is disclosed as above in the preferred embodiment, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A small ratio EVA composite anti-shrinkage elastomer, characterized in that: In parts by weight, it contains the following raw materials: 15-20 parts of EVA, 25-35 parts of SEBS, 10-15 parts of SSBR, 10-20 parts of OBC, 3-6 parts of BIIR, 40-55 parts of white oil, 4-8 parts of modified nano-silicon dioxide, 0.1-0.2 parts of silicone powder, 0.5-1.5 parts of cross-linking agent, 2-3 parts of foaming agent, 1-2 parts of zinc oxide, 0.4-0.8 parts of stearic acid, 1-3 parts of antibacterial agent, and 0.5-1 parts of antioxidant.

2. The small-ratio EVA composite anti-shrinkage elastomer according to claim 1, characterized in that: The structural formula of the antibacterial agent is as follows:

3. The small-ratio EVA composite anti-shrinkage elastomer according to claim 2, characterized in that: The preparation method of the antibacterial agent comprises the following steps: (1) Add 3-bromo-2,2-dimethyl-1-propanol, sodium azide and dimethyl sulfoxide to a first reaction kettle, heat to 100-120° C., react for 16-24 hours, cool, add deionized water, extract with ethyl acetate 2-3 times, wash 2-3 times, dry, and filter to obtain compound 1; (2) Add 1-[4-(trifluoromethyl)phenyl]biguanidine hydrochloride and dimethyl sulfoxide to a second reaction kettle, heat to 50-70° C., stir for 15-30 min, cool, add dropwise a dimethyl sulfoxide solution of 4-bromobutyronitrile, stir for 10-16 h, wash 2-3 times, and dry to obtain compound 2; (3) adding N,N-dimethylformamide to the third reaction kettle, degassing for 15-25 min, adding cuprous bromide and pentamethyldiethylenetriamine, degassing for 10-15 min, and obtaining a solution; (4) Compound 1 obtained in step (1) and compound 2 obtained in step (2) are mixed, and N,N-dimethylformamide is added, and the mixture is degassed for 15-25 min. The solution obtained in step (3) is added and reacted for 1-1.5 h. Deionized water is then added to precipitate the mixture, and the mixture is centrifuged to obtain a solid; (5) Dissolving the solid obtained in step (4) in dimethyl sulfoxide, and then adding deionized water to precipitate, repeating the process three times, and then dissolving the precipitated substance in dimethyl sulfoxide, and drying to obtain an antibacterial agent.

4. The small-ratio EVA composite anti-shrinkage elastomer according to claim 3, characterized in that: The molar ratio of 1-[4-(trifluoromethyl)phenyl]biguanidine hydrochloride to 4-bromobutyronitrile in step (2) is 1:(1.1-1.6).

5. The small-ratio EVA composite anti-shrinkage elastomer according to claim 3, characterized in that: The molar ratio of compound 1 to compound 2 in step (4) is (1.2-1.8):

1.

6. The small-ratio EVA composite anti-shrinkage elastomer according to claim 1, characterized in that: The preparation method of the modified nano-silicon dioxide comprises the following steps: S1. The silane coupling agent KH-550 was added to the first reaction vessel containing the mixed solvent and stirred for 30-45 min to obtain a hydrolyzed solution; S2. Take the hydrolysis solution obtained in step S1 and add the nano-silica to a second reaction vessel, heat to 50-60 ° C, stir for 3-4h, wash with anhydrous ethanol 3-4 times, centrifuge, and remove the powder; S3. Take the powder obtained in step S2 and N,N'-(4,4'-methylenediphenyl)bismaleimide and ball-mill for 1-3 hours, and dry at 50-80°C for 2-4 hours to obtain modified nano-silica.

7. The small-ratio EVA composite anti-shrinkage elastomer according to claim 6, characterized in that: The mass ratio of silane coupling agent KH-550 to nano-silicon dioxide in the hydrolysis solution in step S2 is (0.05-0.2):

1.

8. The small-ratio EVA composite anti-shrinkage elastomer according to claim 6, characterized in that: The mass ratio of the N,N'-(4,4'-methylenediphenyl)bismaleimide in step S3 to the nano-silicon dioxide in step S2 is (0.02-0.1):

1.

9. The small-ratio EVA composite anti-shrinkage elastomer according to claim 1, characterized in that: The VA content of the EVA resin is 15-25wt%.

10. A method for preparing the small-ratio EVA composite anti-shrinkage elastomer according to any one of claims 1 to 9, characterized in that: The following steps are included:

1. Add SEBS, SSBR, OBC, BIIR, white oil, modified nano-silicon dioxide, silicone powder, stearic acid, antibacterial agent and antioxidant into a twin-screw extruder for extrusion granulation to obtain a modified elastomer; 2. The modified elastomer obtained in step 1, EVA, a cross-linking agent, a foaming agent and zinc oxide are mixed and then internally kneaded, and then open-mixed and granulated to obtain the EVA composite anti-shrinkage elastomer.

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