CN118909346B

CN118909346B - A kind of conductive EVA foam material and preparation method thereof

Info

Publication number: CN118909346B
Application number: CN202411409034.6A
Authority: CN
Inventors: 叶涛; 许华港; 王芳芳
Original assignee: Quanzhou Zukang Biotechnology Co ltd
Current assignee: Quanzhou Zukang Biotechnology Co ltd
Priority date: 2024-10-10
Filing date: 2024-10-10
Publication date: 2024-12-27
Anticipated expiration: 2044-10-10
Also published as: CN118909346A

Abstract

本发明公开了一种导电EVA发泡材料及其制备方法，涉及EVA发泡材料技术领域，所述导电EVA发泡材料由以下组分制成：乙烯‑醋酸乙烯共聚物60~80份、POE 5~20份、EPDM 5~10份、发泡剂AC 3~6份、硬脂酸0.5~2份、硬脂酸锌0.5~2份、氧化锌1~3份、过氧化二异丙苯1~5份、改性碳纤维3~10份；本发明通过添加改性碳纤维赋予材料良好导电性，同时保持EVA原有轻质、柔软特性，POE和EPDM的加入增强了力学性能，适用于防静电工作鞋等专业鞋履和普通鞋类，拓展了EVA在鞋业的应用。The invention discloses a conductive EVA foam material and a preparation method thereof, and relates to the technical field of EVA foam materials. The conductive EVA foam material is prepared from the following components: 60-80 parts of ethylene-vinyl acetate copolymer, 5-20 parts of POE, 5-10 parts of EPDM, 3-6 parts of foaming agent AC, 0.5-2 parts of stearic acid, 0.5-2 parts of zinc stearate, 1-3 parts of zinc oxide, 1-5 parts of dicumyl peroxide, and 3-10 parts of modified carbon fiber. The invention provides the material with good conductivity by adding the modified carbon fiber, while maintaining the original light weight and softness of EVA. The addition of POE and EPDM enhances the mechanical properties. The conductive EVA foam material is suitable for professional shoes and common shoes such as antistatic work shoes, and expands the application of EVA in the footwear industry.

Description

Conductive EVA (ethylene-vinyl acetate) foaming material and preparation method thereof

Technical Field

The invention relates to the technical field of EVA foaming materials, in particular to a conductive EVA foaming material and a preparation method thereof.

Background

EVA (ethylene-vinyl acetate copolymer) foaming materials are widely applied in the field of shoe materials because of the advantages of light weight, softness, good elasticity, strong buffering and damping properties and the like. In particular, EVA foam exhibits excellent performance and cost performance in athletic, recreational midsole and insole materials.

However, the conventional EVA foaming material has a remarkable defect that the volume resistivity is generally above 10 ¹⁴ ohm cm, and belongs to an insulating material. The characteristics can cause problems of static electricity accumulation, discomfort caused by static electricity generated by a wearer during walking or movement, potential safety hazards, safety accidents caused by static electricity accumulation under certain special environments (such as electronic factories and flammable and explosive areas), functional limitation and incapacity of meeting the requirements of part of professional footwear (such as antistatic working shoes) on the electric conductivity.

Therefore, developing EVA foaming materials with certain conductive performance has important significance for improving the functionality and the comfort of shoe materials.

At present, the method for improving the conductivity of the EVA foaming material mainly adopts the following steps of adding conductive filler, commonly used carbon black, carbon fiber, metal powder and the like, and has the advantages of obvious effect, relatively simple process, possibly affecting the light weight and flexibility of the material, increasing the cost, coating conductive coating on the surface of the EVA foaming material, having the advantages of not affecting the performance of the material body, having the disadvantages of poor wear resistance and unstable long-term use effect, adding antistatic agent, using various antistatic agents, having the advantages of simple processing, little influence on other performances of the material, having the disadvantages of limited conductive effect and being easily influenced by environmental humidity.

The Chinese patent document CN112574494A discloses an EVA foaming material and a preparation method thereof, wherein the EVA foaming material comprises a main material, a filling agent, a foaming agent, a bridging agent, a foaming accelerator, a lubricant, a deodorizing doping material and a wear-resistant doping material, wherein the main material adopts EVA, the filling agent adopts calcium carbonate, the foaming agent adopts AC-3000H, the bridging agent adopts DTAIC and BIPB mixed components, the foaming accelerator adopts zinc oxide powder and zinc stearate mixed components, the lubricant adopts stearic acid lubricant, the deodorizing doping material adopts nano silver particles, the wear-resistant doping material adopts carbon fiber components, the preparation process is sequentially carried out according to the operations of S1, S2, S3 and S4, the inner structure of the EVA foaming material comprises a breathable deodorizing layer and a wear-resistant layer, the breathable deodorizing layer is provided with air holes, the lower end of the breathable deodorizing layer is fixedly connected with the wear-resistant layer, and the wear-resistant layer is provided with wear-resistant holes.

However, when the EVA foaming material is applied to shoe materials, various challenges remain on how to effectively improve the conductivity while maintaining the light and soft characteristics of the EVA foaming material, how to ensure the uniform distribution of conductive components in the foaming process, avoid influencing the appearance and the hand feeling of the shoe materials, how to balance multiple factors such as the conductivity, the mechanical property, the processing property and the cost, how to ensure the long-term stability of the conductivity, and meet the service life requirement of the shoe materials.

Therefore, a novel foaming material for shoe materials, which has good conductivity and the original excellent characteristics of the EVA foaming material, is developed, and has important practical application value. The functional and comfort of the shoe material can be improved, and a new application direction of the EVA foaming material in the field of shoes can be possibly developed, such as development of innovative products of professional antistatic shoes, intelligent shoes and the like.

Disclosure of Invention

In order to solve the defects existing in the prior art, the invention aims to provide the conductive EVA foaming material and the preparation method thereof, the modified carbon fiber is added to endow the material with good conductivity, meanwhile, the original light and soft characteristics of EVA are kept, the mechanical properties are enhanced by adding POE and EPDM, the conductive EVA foaming material is suitable for professional shoe soles and common shoes such as antistatic working shoes, and the application of EVA in the shoe industry is expanded.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

The conductive EVA foaming material is prepared from, by weight, 60-80 parts of an ethylene-vinyl acetate copolymer, 5-20 parts of POE, 5-10 parts of EPDM, 3-6 parts of a foaming agent AC, 0.5-2 parts of stearic acid, 0.5-2 parts of zinc stearate, 1-3 parts of zinc oxide, 1-5 parts of dicumyl peroxide and 3-10 parts of modified carbon fibers.

Preferably, the preparation method of the modified carbon fiber comprises the following steps:

(1) Extracting carbon fiber with acetone solution, washing with deionized water, oven drying, adding into oxalyl chloride, stirring under nitrogen atmosphere for reaction, filtering, washing with alcohol, and drying to obtain acyl chloride carbon fiber;

The acyl chlorination of carbon fiber, the reaction of carboxyl (-COOH) on the surface of carbon fiber with oxalyl chloride (ClCOCOCl) to form acyl chloride (-COCl) R-COOH+ ClCOCOCl- & gt R-COCl+CO ₂ +HCl, increases the reactivity of the surface of carbon fiber.

Preferably, in the step (1), the carbon fiber has a diameter of 10 to 38 μm and a length of 0.5 to 1.5mm.

Preferably, in the step (1), the carbon fiber is extracted by acetone for 10-14 hours, the dosage ratio of the carbon fiber to oxalyl chloride is 10 g:50-200 mL, and the stirring reaction is carried out for 2-6 hours under the condition of 35-60 ℃.

(2) Adding acyl carbon chloride fiber and 4-hydroxy cinnamic acid into dichloromethane under the condition of avoiding light, stirring and mixing, continuously introducing nitrogen, adding triethylamine, stirring and reacting, filtering, washing and drying the product to obtain cinnamic acid modified carbon fiber;

And cinnamic acid modification, namely, carrying out esterification reaction on acyl chloride groups on acyl chloride carbon fibers and hydroxyl groups of 4-hydroxy cinnamic acid, namely, taking R-COCl+HO-C ₆H₄-CH=CH-COOH → R-COO-C₆H₄ -CH=CH-COOH+HCl and triethylamine as alkali to neutralize the HCl generated by the reaction and promote the reaction to be carried out.

Preferably, in the step (2), the dosage ratio of the acyl chloride carbon fiber, the 4-hydroxy cinnamic acid and the dichloromethane is 10 g:5-12 g:50-100 mL, and the dosage of the triethylamine is 1-5wt% of the 4-hydroxy cinnamic acid.

Preferably, in the step (2), the stirring reaction condition is 50-80 ℃ and the stirring reaction is carried out for 4-12 hours.

(3) Adding cinnamic acid modified carbon fiber and polyaniline into DMF under the condition of avoiding light, stirring and mixing, continuously introducing nitrogen, adding DCC, stirring and reacting, filtering, washing and drying the product to obtain the modified carbon fiber.

The polyaniline graft DCC firstly reacts with carboxyl to form O-acyl isourea intermediate, then the intermediate reacts with amino of polyaniline to form amide bond, and DCU is released at the same time, R-COO-C ₆H₄-CH=CH-COOH + H₂ N-polyaniline+DCC→R-COO-C ₆H₄ -CH=CH-CONH-polyaniline+DCU (dicyclohexylurea).

Preferably, in the step (3), the polyaniline is 5000-50000 Da and PDI <2.

Preferably, in the step (3), the dosage ratio of the cinnamic acid modified carbon fiber, the polyaniline and the DMF is 10 g:5-15 g:100-200 mL, and the dosage of the DCC is 5-10wt% of the polyaniline.

Preferably, in the step (3), stirring reaction is carried out for 6-18 hours under the condition of 60-100 ℃.

The invention further claims a preparation method of the conductive EVA foaming material, which comprises the steps of uniformly mixing raw materials, placing the mixture in a preheated extruder, extruding and mixing the mixture at the temperature of each area of 110-120 ℃ at 20-50 r/min, transferring the obtained mixture into an open mill, mixing the mixture for 10-30 min, pressing the mixture into 3-5 mm sheets or granulating the sheet or the granule, placing the sheet or the granule in a preheated press vulcanizer die cavity, and performing die pressing foaming at the temperature of 2-12 MPa and 165-180 ℃ for 8-16 min to obtain the conductive EVA foaming material.

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention provides a conductive EVA foaming material, which takes ethylene-vinyl acetate copolymer as a main body and is matched with proper foaming agents such as AC, stearic acid, zinc stearate, zinc oxide and dicumyl peroxide, so that good foaming performance and basic physical performance of the material are ensured. In particular, the modified carbon fiber is added, so that the balance between the conductivity and the original excellent characteristics of EVA is successfully realized. The EVA foaming material not only maintains the characteristics of light weight, softness, good elasticity and strong buffering and damping properties of the EVA foaming material, but also has good conductivity, and effectively solves the problem of static accumulation. By optimizing the proportion of each component, the invention successfully develops a novel material with the advantages of conductivity and traditional EVA, can obviously improve the functionality and comfort of shoe materials, simultaneously meets the requirements of professional shoes such as antistatic working shoes and the like, and opens up a new application direction for EVA foaming materials in the field of shoes. In addition, the invention adopts the conventional mixing, extrusion, open milling and mould pressing processes, has simple and reliable preparation method, is easy to realize industrial production, and has good application prospect.

(2) The invention provides a preparation method of modified carbon fiber, which comprises the steps of firstly, activating the surface of the carbon fiber through oxalyl chloride treatment, converting hydroxyl groups on the surface of the carbon fiber into acyl chloride groups with higher activity, secondly, modifying the carbon fiber by utilizing 4-hydroxy cinnamic acid, wherein the acyl chloride groups on the surface of the carbon fiber and hydroxyl groups in the 4-hydroxy cinnamic acid are subjected to esterification reaction, successfully introducing the cinnamic acid groups with optical activity, simultaneously introducing carboxyl groups and carbon-carbon double bond structures on the surface of the carbon fiber, and finally, further modifying by polyaniline, wherein in the step, the carboxyl groups on the surface of the cinnamic acid modified carbon fiber and amino groups at the chain ends of polyaniline molecules are subjected to condensation reaction to form amide bonds, so that polyaniline molecules with excellent conductivity are linked to the surface of the carbon fiber. The multi-step and multi-group involved modification process not only remarkably improves the conductivity of the carbon fiber, but also improves the compatibility and dispersibility of the carbon fiber with an EVA matrix by introducing various functional groups.

(3) The modified carbon fiber provided by the invention has the advantages that the modified carbon fiber has higher conductivity after three-step modification process, and can realize good conductive effect under lower addition amount, so that the light property and flexibility of the EVA foaming material are maintained to the maximum extent. And secondly, the introduced cinnamate group has excellent ultraviolet absorption capacity and larger molar absorption coefficient, and is beneficial to improving the ultraviolet resistance of the EVA foaming material. Furthermore, the polyaniline is grafted to the surface of the carbon fiber through the 4-hydroxy cinnamic acid, so that the polyaniline network and EVA are effectively and uniformly compounded, the polyaniline is ensured not to migrate out of the foaming material in the use process, and the conductivity and antistatic capacity of the material are further enhanced. In addition, after the 4-hydroxy cinnamic acid is chemically bonded with the components with double bonds in the foaming material, the modified carbon fiber is endowed with excellent low migration property, oxidation resistance and antistatic long-acting property. The multiple modification not only enhances the interaction between the carbon fiber and the EVA matrix and improves the dispersibility and interface bonding strength of the carbon fiber in the material, thereby being beneficial to forming a stable conductive network, but also ensures that the conductive EVA foaming material keeps stable performance in the long-term use process. In conclusion, the modified carbon fiber provides key technical support for developing the high-performance multifunctional conductive EVA foaming material, and the comprehensive performance and the application value of the material are remarkably improved.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following examples. Of course, the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.

Unless otherwise specified, both chemical reagents and materials in the present invention are purchased through a market route or synthesized from raw materials purchased through a market route.

Ethylene vinyl acetate copolymer was purchased from dupont under the trademark EVA 265;

EPDM was purchased from dow corporation under the trademark EPDM5565;

POE is available from mitsunobu chemical company under the designation DF740.

A preparation method of a conductive EVA foaming material comprises the following steps:

(1) Extracting 10g of carbon fiber with 100mL of acetone solution for 10-14 h, washing with deionized water, drying, adding into 50-200 mL of oxalyl chloride, stirring and reacting for 2-6 h under the nitrogen atmosphere at 35-60 ℃, filtering the product, washing with alcohol, and drying to obtain acyl chloride carbon fiber;

(2) Adding 10g of acyl chloride carbon fiber and 5-12 g of 4-hydroxy cinnamic acid into 50-100 mL of dichloromethane under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 0.05-0.6 g of triethylamine, stirring and reacting for 4-12 h at 50-80 ℃, filtering, washing and drying the product to obtain cinnamic acid modified carbon fiber;

(3) Adding 10g of cinnamic acid modified carbon fiber and 5-15 g of polyaniline into 100-200 mL of DMF under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 0.25~1.5g DCC,60~100 ℃ and stirring and reacting for 6-18 h, filtering, washing and drying the product to obtain the modified carbon fiber;

(4) 60-80 parts of ethylene-vinyl acetate copolymer, 5-20 parts of POE, 5-10 parts of EPDM, 3-6 parts of foaming agent AC, 0.5-2 parts of stearic acid, 0.5-2 parts of zinc stearate, 1-3 parts of zinc oxide, 1-5 parts of dicumyl peroxide and 3-10 parts of modified carbon fiber are uniformly mixed, then the mixture is placed into a preheated extruder, extrusion mixing is carried out at 110-120 ℃ and 20-50 r/min, the obtained mixture is transferred into an open mill, mixed for 10-30 min, then pressed into 3-5 mm slices or granules, placed into a preheated flat vulcanizing machine die cavity, and subjected to compression molding foaming for 8-16 min at 2-12 MPa and 165-180 ℃ to obtain the conductive EVA foaming material.

The invention will be further illustrated by the following examples.

Example 1

(1) Extracting 10g of carbon fiber with 100mL of acetone solution for 14h, washing with deionized water, drying, adding into 100mL of oxalyl chloride, stirring and reacting for 2h under the nitrogen atmosphere at 60 ℃, filtering the product, washing with alcohol, and drying to obtain the acyl chloride carbon fiber;

(2) Adding 10g of acyl chloride carbon fiber and 12g of 4-hydroxy cinnamic acid into 100mL of dichloromethane under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 0.6g of triethylamine, stirring and reacting for 4 hours at 80 ℃, filtering, washing and drying the product to obtain cinnamic acid modified carbon fiber;

(3) Adding 10g of cinnamic acid modified carbon fiber and 15g of polyaniline into 150mL of DMF under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 1.5g of DCC, stirring and reacting for 6h at 100 ℃, filtering, washing and drying the product to obtain the modified carbon fiber;

(4) Mixing 8kg of ethylene-vinyl acetate copolymer, 2kg of POE, 1kg of EPDM, 0.6kg of foaming agent AC, 0.2kg of stearic acid, 0.2kg of zinc stearate, 0.3kg of zinc oxide, 0.5kg of dicumyl peroxide and 1kg of modified carbon fiber uniformly, putting the mixture into a preheated extruder, extruding and mixing at 115 ℃ and 40r/min, transferring the obtained mixture into an open mill, mixing for 20min, pressing the mixture into 4mm slices, putting the slices into a preheated press vulcanizer die cavity, and performing die pressing foaming for 12min at 8MPa and 170 ℃ to obtain the conductive EVA foaming material.

Example 2

(1) Extracting 10g of carbon fiber with 100mL of acetone solution for 13h, washing with deionized water, drying, adding into 100mL of oxalyl chloride, stirring and reacting for 3h under the nitrogen atmosphere at 50 ℃, filtering the product, washing with alcohol, and drying to obtain the acyl chloride carbon fiber;

(2) Adding 10g of acyl chloride carbon fiber and 10g of 4-hydroxy cinnamic acid into 100mL of dichloromethane under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 0.4g of triethylamine, stirring and reacting for 7h at 70 ℃, filtering, washing and drying the product to obtain cinnamic acid modified carbon fiber;

(3) Adding 10g of cinnamic acid modified carbon fiber and 12g of polyaniline into 150mL of DMF under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 1.2g of DCC, stirring and reacting for 10 hours at 90 ℃, filtering, washing and drying the product to obtain the modified carbon fiber;

(4) Mixing 7.4kg of ethylene-vinyl acetate copolymer, 1.5kg of POE, 0.8kg of EPDM, 0.5kg of foaming agent AC, 0.15kg of stearic acid, 0.15kg of zinc stearate, 0.25kg of zinc oxide, 0.4kg of dicumyl peroxide and 0.8kg of modified carbon fiber uniformly, putting the mixture into a preheated extruder, extruding and mixing at 115 ℃ and 40r/min, transferring the obtained mixture into an open mill, mixing for 20min, granulating, putting the mixture into a preheated flat vulcanizing machine die cavity, and performing die pressing foaming at 8MPa and 170 ℃ for 12min to obtain the conductive EVA foaming material.

Example 3

(1) Extracting 10g of carbon fiber with 100mL of acetone solution for 11h, washing with deionized water, drying, adding into 100mL of oxalyl chloride, stirring and reacting for 4h under the nitrogen atmosphere at 40 ℃, filtering the product, washing with alcohol, and drying to obtain the acyl chloride carbon fiber;

(2) Adding 10g of acyl chloride carbon fiber and 8g of 4-hydroxy cinnamic acid into 100mL of dichloromethane under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 0.2g of triethylamine, stirring and reacting for 10 hours at 60 ℃, filtering, washing and drying the product to obtain cinnamic acid modified carbon fiber;

(3) Adding 10g of cinnamic acid modified carbon fiber and 8g of polyaniline into 150mL of DMF under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 0.7g of DCC, stirring and reacting for 14h at 70 ℃, filtering, washing and drying the product to obtain the modified carbon fiber;

(4) Mixing 6.8kg of ethylene-vinyl acetate copolymer, 1kg of POE, 0.6kg of EPDM, 0.4kg of foaming agent AC, 0.1kg of stearic acid, 0.1kg of zinc stearate, 0.2kg of zinc oxide, 0.3kg of dicumyl peroxide and 0.5kg of modified carbon fiber uniformly, putting the mixture into a preheated extruder, extruding and mixing at 115 ℃ and 40r/min, transferring the obtained mixture into an open mill, mixing for 20min, pressing into 4mm slices, putting the slices into a preheated flat vulcanizing machine die cavity, and performing compression molding foaming at 8MPa and 170 ℃ for 12min to obtain the conductive EVA foaming material.

Example 4

(1) Extracting 10g of carbon fiber with 100mL of acetone solution for 10h, washing with deionized water, drying, adding into 100mL of oxalyl chloride, stirring and reacting for 6h under the nitrogen atmosphere at 35 ℃, filtering the product, washing with alcohol, and drying to obtain the acyl chloride carbon fiber;

(2) Adding 10g of acyl chloride carbon fiber and 5g of 4-hydroxy cinnamic acid into 100mL of dichloromethane under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 0.05g of triethylamine, stirring and reacting for 12 hours at 50 ℃, filtering, washing and drying the product to obtain cinnamic acid modified carbon fiber;

(3) Adding 10g of cinnamic acid modified carbon fiber and 5g of polyaniline into 150mL of DMF under the condition of light shielding, stirring and mixing, continuously introducing nitrogen, adding 0.25g of DCC, stirring and reacting for 18h at 60 ℃, filtering, washing and drying the product to obtain the modified carbon fiber;

(4) Mixing 6kg of ethylene-vinyl acetate copolymer, 0.5kg of POE, 0.5kg of EPDM, 0.3kg of foaming agent AC, 0.05kg of stearic acid, 0.05kg of zinc stearate, 0.1kg of zinc oxide, 0.1kg of dicumyl peroxide and 0.3kg of modified carbon fiber uniformly, putting the mixture into a preheated extruder, extruding and mixing at 115 ℃ and 40r/min, transferring the obtained mixture into an open mill, mixing for 20min, pressing into 4mm slices, putting the slices into a preheated flat vulcanizing machine die cavity, and performing compression molding foaming at 8MPa and 170 ℃ for 12min to obtain the conductive EVA foaming material.

Comparative example 1

The preparation method of the EVA foaming material comprises the following steps:

(3) Mixing 8kg of ethylene-vinyl acetate copolymer, 2kg of POE, 1kg of EPDM, 0.6kg of foaming agent AC, 0.2kg of stearic acid, 0.2kg of zinc stearate, 0.3kg of zinc oxide, 0.5kg of dicumyl peroxide and 1kg of cinnamic acid modified carbon fiber uniformly, putting the mixture into a preheated extruder, extruding and mixing at 115 ℃ and 40r/min, transferring the obtained mixture into an open mill, mixing for 20min, pressing the mixture into 4mm slices, putting the slices into a preheated flat vulcanizing machine die cavity, and performing die pressing foaming for 12min at 8MPa and 170 ℃ to obtain the EVA foaming material.

Comparative example 2

(2) Mixing 8kg of ethylene-vinyl acetate copolymer, 2kg of POE, 1kg of EPDM, 0.6kg of foaming agent AC, 0.2kg of stearic acid, 0.2kg of zinc stearate, 0.3kg of zinc oxide, 0.5kg of dicumyl peroxide and 1kg of acyl chloride carbon fiber uniformly, putting the mixture into a preheated extruder, extruding and mixing at 115 ℃ and 40r/min, transferring the obtained mixture into an open mill, mixing for 20min, pressing the mixture into 4mm slices, putting the slices into a preheated flat vulcanizing machine die cavity, and performing die pressing foaming for 12min at 8MPa and 170 ℃ to obtain the EVA foaming material.

The EVA foaming materials prepared in examples 1-4 and comparative examples 1-2 are subjected to performance test, the Shore hardness is measured by referring to HG/T2489-2007 'hardness test method of microporous materials for shoes', the permanent compression deflection is measured by referring to HG/T2876-2009 'compression deformation test method of microporous materials for rubber and plastic shoes', the tearing strength is measured by referring to GB/T529-2008 'measurement of tearing strength of vulcanized rubber or thermoplastic rubber (trouser, right angle and crescent test), the elongation and tensile strength are measured by referring to GB/T528-2009' measurement of tensile stress strain property of vulcanized rubber or thermoplastic rubber ', the sample is subjected to ultraviolet irradiation aging test, the surface temperature of the test sample is 60+/-5 ℃, the ultraviolet wavelength range is 280-400 nm, the irradiation intensity is 15 kW.h/m ², the ultraviolet irradiation test time is 2000h, the yellowing index before and after the test is measured by referring to HG/T3862-2006' test method of yellow index of plastics ', the DC resistance or conductivity of the foaming material is confirmed by referring to ASTM D257-2014' test standard of DC resistance or conductivity, the specific current is measured by referring to the specific current table 1.

Table 1 EVA foam Performance test results

	Example 1	Example 2	Example 3	Example 4	Comparative example 1	Comparative example 2
							Shore hardness of	51	48	46	42	53	51
Permanent compression distortion (%)	19.3	20.1	20.8	21.2	23.4	27.6
							Tear strength (N/mm)	24.1	23.5	23.2	22.6	20.7	17.4
Tensile Strength (MPa)	3.6	3.4	3.1	3.1	2.6	2.1
							Yellowing index change (delta YI)	0.4	0.4	0.5	0.5	0.5	1.3
Surface resistance (omega)	3.1×10⁶	3.7×10⁶	5.2×10⁶	6.3×10⁶	6.5×10⁸	1.9×10⁹

The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims

1. A conductive EVA foam material, characterized in that it is made of the following components by weight: 60-80 parts of ethylene-vinyl acetate copolymer, 5-20 parts of POE, 5-10 parts of EPDM, 3-6 parts of foaming agent AC, 0.5-2 parts of stearic acid, 0.5-2 parts of zinc stearate, 1-3 parts of zinc oxide, 1-5 parts of dicumyl peroxide, and 3-10 parts of modified carbon fiber;

The method for preparing the modified carbon fiber comprises the following steps:

(1) extracting the carbon fiber with an acetone solution, then washing with deionized water, drying, adding it to oxalyl chloride, stirring and reacting under a nitrogen atmosphere, filtering the product, washing with alcohol, and drying to obtain chlorinated carbon fiber;

(2) Adding chlorinated carbon fiber and 4-hydroxycinnamic acid to dichloromethane under light-proof conditions, stirring and mixing, continuously introducing nitrogen, adding triethylamine, stirring and reacting, filtering, washing, and drying the product to obtain cinnamic acid-modified carbon fiber;

(3) Add cinnamic acid-modified carbon fiber and polyaniline to DMF under light-proof conditions, stir and mix, continuously introduce nitrogen, add DCC, stir to react, filter, wash and dry the product to obtain modified carbon fiber.

2. The conductive EVA foam material according to claim 1, characterized in that in step (1), the carbon fiber has a diameter of 10-38 μm and a length of 0.5-1.5 mm.

3. The conductive EVA foam material according to claim 1, characterized in that, in step (1), the carbon fiber is extracted with acetone for 10 to 14 hours; the amount ratio of the carbon fiber to oxalyl chloride is 10 g: 50 to 200 mL; and the stirring reaction conditions are stirring the reaction at 35 to 60° C. for 2 to 6 hours.

4. The conductive EVA foam material according to claim 1, characterized in that in step (2), the amount ratio of chlorinated carbon fiber, 4-hydroxycinnamic acid, and dichloromethane is 10g:5~12g:50~100mL; the amount of triethylamine is 1~5wt% of 4-hydroxycinnamic acid.

5. The conductive EVA foam material according to claim 1, characterized in that in step (2), the stirring reaction conditions are 50-80°C and 4-12h.

6. The conductive EVA foam material according to claim 1, characterized in that in step (3), the polyaniline is 5000-50000 Da, and PDI<2.

7. The conductive EVA foam material according to claim 1, characterized in that in step (3), the amount ratio of cinnamic acid modified carbon fiber, polyaniline and DMF is 10g:5-15g:100-200mL; the amount of DCC is 5-10wt% of the polyaniline.

8. The conductive EVA foam material according to claim 1, characterized in that in step (3), the stirring reaction conditions are 60-100°C and 6-18h.

9. A method for preparing a conductive EVA foam material as claimed in any one of claims 1 to 8, characterized in that it comprises the following steps: after the raw materials are mixed evenly, they are placed in a preheated extruder, the temperature of each zone is 110-120° C., and extrusion and mixing are performed at 20-50 r/min; after the obtained mixture is transferred to an open mill and mixed for 10-30 min, it is pressed into 3-5 mm thin sheets or granules, placed in a preheated flat vulcanizer mold cavity, and molded and foamed at 2-12 MPa and 165-180° C. for 8-16 min to obtain the conductive EVA foam material.