阅读说明：本技术 阻燃橡胶鞋底及其制备方法 (Flame-retardant rubber sole and preparation method thereof ) 是由 陈松雄 晋齐怀 张世林 王春桥 田杰 毛昌虎 廖浦江 于 2021-09-02 设计创作，主要内容包括：本发明公开了一种阻燃橡胶鞋底,按重量份数计算,它包括2#标准胶,SN121型氯丁橡胶、顺丁橡胶、硫磺、促进剂、硫化活性剂、脱模剂、炭黑、软化剂、混合阻燃剂及防老剂。本发明以天然橡胶、氯丁胶、顺丁橡胶作为主体材料,通过加入补强填充剂及软化剂来保障胶料的物理性能,确保了橡胶鞋底的使用寿命和工艺操作性能,并通过采用高效阻燃剂十溴二苯醚、氯化石蜡、硼酸锌和氧化锑共同作为阻燃体系,为产品提供优异阻燃性能；达到在燃烧时生成炭层,以吸附熔融、着火的聚合物,能防止液滴传递火灾,克服了常规NR+SBR+BR混炼胶极易燃烧的缺点,其阻燃级别可达到UL94V-0级,在垂直燃烧试验中达到自熄要求。(The invention discloses a flame-retardant rubber sole which comprises 2# standard rubber, SN121 type chloroprene rubber, butadiene rubber, sulfur, an accelerator, a vulcanization activator, a mold release agent, carbon black, a softener, a mixed flame retardant and an anti-aging agent in parts by weight. The natural rubber, the chloroprene rubber and the butadiene rubber are used as main materials, the physical properties of rubber materials are guaranteed by adding the reinforcing filler and the softener, the service life and the process operation performance of rubber soles are guaranteed, and the high-efficiency flame retardant decabromodiphenyl ether, chlorinated paraffin, zinc borate and antimony oxide are used as a flame retardant system, so that excellent flame retardant performance is provided for products; the flame-retardant rubber can generate a carbon layer during combustion to adsorb molten and ignited polymers, can prevent liquid drops from transmitting fire, overcomes the defect that the conventional NR + SBR + BR rubber compound is extremely easy to combust, has the flame-retardant grade reaching UL94V-0 grade, and meets the self-extinguishing requirement in a vertical combustion test.)

1. A flame-retardant rubber sole is characterized in that: the flame retardant rubber comprises, by mass, 50-55 parts of No. 2 standard rubber, 15-20 parts of SN121 type chloroprene rubber, 25-35 parts of butadiene rubber, 1.9-2.1 parts of sulfur, 3-4 parts of an accelerator, 8-10 parts of a vulcanization activator, 0.5-0.7 part of a release agent, 53-57 parts of carbon black, 14-18 parts of a softener, 60-70 parts of a mixed flame retardant and 1.0-2.0 parts of an anti-aging agent.

2. The flame-retardant rubber shoe sole according to claim 1, wherein: the flame retardant rubber comprises, by weight, 50 parts of No. 2 standard rubber, 18 parts of SN121 type chloroprene rubber, 32 parts of butadiene rubber, 2 parts of sulfur, 3.5 parts of an accelerator, 9 parts of a vulcanization activator, 0.6 part of a release agent, 55 parts of carbon black, 16 parts of a softener, 65 parts of a mixed flame retardant and 1.5 parts of an anti-aging agent.

3. The flame-retardant rubber shoe sole according to claim 1 or 2, characterized in that: the butadiene rubber is BR 9000.

4. The flame-retardant rubber shoe sole according to claim 1 or 2, characterized in that: every 3.5 parts of accelerator consists of 0.8 part of accelerator DM, 0.3 part of accelerator NA-22, 2.0 parts of accelerator CBS and 0.4 part of accelerator D.

5. The flame-retardant rubber shoe sole according to claim 1 or 2, characterized in that: every 9 parts of vulcanization activator comprises 3 parts of tertiary stearic acid, 5 parts of nano zinc oxide and 1 part of light magnesium oxide.

6. The flame-retardant rubber shoe sole according to claim 1 or 2, characterized in that: each 16 parts of softener consists of 11 parts of dibutyl phthalate and 5 parts of solid coumarone; every 65 parts of the mixed flame retardant consists of 20 parts of decabromodiphenyl ether, 10 parts of antimony trioxide, 20 parts of chlorinated paraffin-70 and 15 parts of zinc borate.

7. The flame-retardant rubber shoe sole according to claim 1 or 2, characterized in that: the carbon black type is N220 carbon black.

8. The flame-retardant rubber shoe sole according to claim 1 or 2, characterized in that: every 1.5 parts of the anti-aging agent consists of 1.0 part of anti-aging agent CD and 0.5 part of anti-aging agent 4010 NA; and 0.08-0.12 part of a scorch retarder which is salicylic acid.

9. The preparation method of the flame-retardant rubber sole is characterized by taking the components in parts by mass, and comprises the following steps:

firstly, preparing a master batch, namely adding 4/5 # 2 standard rubber, butadiene rubber, 1.6 parts of stearic acid, carbon black and solid coumarone in a softener into an internal mixer, performing press mixing for 4-5 minutes, lifting a top bolt to scrape rubber when the current load of the internal mixer is reduced to 220A, sending overflowing materials at the mouth of the internal mixer into an internal mixing chamber, finishing scraping within 15-25 seconds, adding 1/2 dibutyl phthalate in the softener within next 30 seconds, playing back an upper top bolt in place, continuing to perform press mixing, performing press mixing for 3.5-4 minutes after the load of the rubber mixer is lifted, and increasing the load of the rubber mixer to more than 160A to discharge, thus obtaining the master batch;

and step two, standing the master batch for 12 hours, adding the rest 2# standard rubber, SN121 chloroprene rubber and the middle materials into an internal mixer, pressing for 50-65 seconds, adding a mixed flame retardant, pressing for 3-5 minutes, lifting the top plug and scraping rubber, pressing for 2 minutes, adding the rest dibutyl phthalate in the softener when the sound of pounding is generated due to rubber material friction in the internal mixer, pressing for 1 minute after the rubber load rises to 200A, discharging, adding sulfur into the discharged rubber material on an open rubber mixer, and uniformly turning to obtain the finished product.

10. The method for preparing a flame-retardant rubber sole according to claim 9, wherein: the medium material comprises residual materials in the accelerator, a release agent, an anti-aging agent and a scorch retarder.

Technical Field

The invention relates to rubber and a preparation method thereof, in particular to a flame-retardant rubber sole and a preparation method thereof.

Background

As cloth rubber shoes with flame retardant function, the main users of the rubber shoes generally belong to the forest fire prevention work category, and under abnormal scenes such as rescue, fire extinguishment and the like caused by forest fire, the shoes and clothes worn by forest fire fighters usually contact with flame or burning bodies for a short time, and the chances that the shoe bodies contact with the burning bodies are high, so that the sole rubber for the shoes used by the forest fire fighters is required to have proper flame retardant capability, namely, the reduction of the protective performance caused by the continuous burning of the sole rubber can be prevented on the premise of having enough flame retardant performance. Due to the particularity of the working environment of forest protection personnel, the sole rubber is required to have enough service performance.

Generally, pure chloroprene rubber is adopted as a main material of the flame-retardant sole rubber, and the flame-retardant performance of the flame-retardant sole rubber has an outstanding protection advantage. But due to the characteristics of the chloroprene rubber, the rubber material for shoes has poor processing performance, low stability and short service life of the processed flame-retardant rubber shoes. And the cost is always high because the bonding is difficult and the production yield is seriously influenced.

The importance of the development of natural rubber flame retardant materials:

with the expansion of the application field of natural rubber, the requirement for the flame retardant property of rubber products is higher and higher, and the development and application of natural rubber flame retardant products become more and more important. The natural rubber has an extreme oxygen index of about 17, and belongs to an extremely flammable material. The rubber sole taking the natural rubber and the cis-butadiene rubber as a combined system has excellent comprehensive performance, and has great practical significance in researching the flame resistance of the carbon black reinforced rubber sole.

In the process of manufacturing the rubber for flame-retardant shoes, the natural rubber is filled with the flame retardant, which is an optimal scheme and has the advantages of easy forming and processing, low cost and long service life of rubber shoes. However, inorganic materials of antimony trioxide and aluminum hydroxide are used as flame retardants, and the flame retardant capability is limited, so that the inorganic materials are required to be used in a formula in a large amount, which causes the problems of great reduction of the physical properties of rubber, formation of abnormal quality problems such as rubber blooming and the like, rubber shoes are not durable to wear, have more three wastes, are not environment-friendly, and have small use value and low application range.

By combining the advantages of the chloroprene rubber and the natural rubber, the blend body which is prepared by taking the natural rubber as the main body and the chloroprene rubber as the auxiliary flame retardant and is used for researching the rubber can form the characteristics of excellent flame retardant property, good bonding effect, high production efficiency, proper cost and long service life of products.

Disclosure of Invention

The purpose of the invention is: the flame-retardant rubber sole and the preparation method thereof have the advantages of good flame-retardant performance, capability of preventing liquid drops from transmitting fire, long service life and capability of overcoming the defects of the prior art.

The invention is realized by the following steps: the flame retardant rubber comprises, by mass, 50-55 parts of No. 2 standard rubber, 15-20 parts of SN121 type chloroprene rubber, 25-35 parts of butadiene rubber, 1.9-2.1 parts of sulfur, 3-4 parts of an accelerator, 8-10 parts of a vulcanization activator, 0.5-0.7 part of a release agent, 53-57 parts of carbon black, 14-18 parts of a softener, 60-70 parts of a mixed flame retardant and 1.0-2.0 parts of an anti-aging agent.

More preferably, the rubber composition comprises, by weight, 50 parts of No. 2 standard rubber, 18 parts of SN121 type chloroprene rubber, 32 parts of butadiene rubber, 2 parts of sulfur, 3.5 parts of an accelerator, 9 parts of a vulcanization activator, 0.6 part of a mold release agent, 55 parts of carbon black, 16 parts of a softener, 65 parts of a mixed flame retardant and 1.5 parts of an anti-aging agent.

The butadiene rubber is BR 9000.

Every 3.5 parts of accelerator consists of 0.8 part of accelerator DM, 0.3 part of accelerator NA-22, 2.0 parts of accelerator CBS and 0.4 part of accelerator D.

Every 9 parts of vulcanization activator comprises 3 parts of tertiary stearic acid, 5 parts of nano zinc oxide and 1 part of light magnesium oxide.

Each 16 parts of softener consists of 11 parts of dibutyl phthalate and 5 parts of solid coumarone; every 65 parts of the mixed flame retardant consists of 20 parts of decabromodiphenyl ether, 10 parts of antimony trioxide, 20 parts of chlorinated paraffin-70 and 15 parts of zinc borate.

The carbon black type is N220 carbon black.

Every 1.5 parts of the anti-aging agent consists of 1.0 part of anti-aging agent CD and 0.5 part of anti-aging agent 4010 NA; and 0.08-0.12 part of a scorch retarder which is salicylic acid.

The preparation method of the flame-retardant rubber sole comprises the following steps of:

firstly, preparing a master batch, namely adding 4/5 # 2 standard rubber, butadiene rubber, 1.6 parts of stearic acid, carbon black and solid coumarone in a softener into an internal mixer, performing press mixing for 4-5 minutes, lifting a top bolt to scrape rubber when the current load of the internal mixer is reduced to 220A, sending overflowing materials at the mouth of the internal mixer into an internal mixing chamber, finishing scraping within 15-25 seconds, adding 1/2 dibutyl phthalate in the softener within next 30 seconds, playing back an upper top bolt in place, continuing to perform press mixing, performing press mixing for 3.5-4 minutes after the load of the rubber mixer is lifted, and increasing the load of the rubber mixer to more than 160A to discharge, thus obtaining the master batch;

and step two, standing the master batch for 12 hours, adding the rest 2# standard rubber, SN121 chloroprene rubber and the middle materials into an internal mixer, pressing for 50-65 seconds, adding a mixed flame retardant, pressing for 3-5 minutes, lifting the top plug and scraping rubber, pressing for 2 minutes, adding the rest dibutyl phthalate in the softener when the sound of pounding is generated due to rubber material friction in the internal mixer, pressing for 1 minute after the rubber load rises to 200A, discharging, adding sulfur into the discharged rubber material on an open rubber mixer, and uniformly turning to obtain the finished product.

The medium material comprises residual materials in the accelerator, a release agent, an anti-aging agent and a scorch retarder.

The chemical name of the anti-aging agent CD is carbodiimide; the chemical name of the anti-aging agent 4010NA is N-phenyl-N' -yl-p-phenylenediamine.

The comparison standards adopted by the invention are as follows:

the UL94 fire rating is 94HB, 94V, 94-5V.

A) Grade 94 HB: i.e. when the test piece is ignited in a horizontal mode, 1) the thickness of the test piece is less than 3.05mm, and the burning speed is less than 76.2 mm/min; 2) the thickness of the test piece is 3.05-12.7 mm, and the burning speed is less than 38.1 mm/min; this is a 94HB level minimum requirement.

B)94V level: the test piece can reach the following standard when being vertically burnt, and can be divided into three stages of V-0, V-1 and V-2. Wherein

V-0 level: when each flame was removed, the test piece ignited no more than 10 seconds and no sparks dropped to surgical cotton 305mm from the test piece to ignite the ignition point and no residual flame for more than 30 seconds.

V-1 grade: the same as V-0, except that the test piece had to be extinguished within 30 seconds and had no residual combustion after 60 seconds.

V-2 level: same as V-0 except that there are starred drops that catch fire on the dried cotton.

94V-0 level: the flame does not support combustion for 15 seconds (1000BTU) and can be automatically fried and extinguished;

94V-1 level: the flame dropped for 30 seconds (1000BTU), but no flame was generated.

94V-2 level: the flame man will drop in 30 seconds (1000BTU), has flame, but will not ignite cotton, and will self-extinguish.

94 HB: OBTU is almost non-fire-resistant.

The flame retardant grade is gradually increased from HB, V-2, V-1 to V-0:

1) HB: the lowest flame retardant rating in the UL94 standard. Requiring a burn rate of less than 40 mm per minute for samples 3 to 13 mm thick; a sample less than 3 mm thick with a burning rate less than 70 mm per minute; or extinguished before the 100 mm mark.

2) V-2: after two 10 second burn tests on the samples, the flame extinguished within 60 seconds. There may be combustion products falling.

3) V-1: after two 10 second burn tests on the samples, the flame extinguished within 60 seconds. No combustible material can fall off.

4) V-0: after two 10 second burn tests on the samples, the flame extinguished within 30 seconds. No combustible material can fall off.

The ingredients are combined with each other, so that the ingredients have positive effects on the product performance, and the method comprises the following steps:

1. wear resistance: the high-weight N220 carbon black filled NR/SN/BR combined system is matched with solid coumarone and dibutyl phthalate to improve the elongation of vulcanized rubber, improve the wear resistance of the vulcanized rubber and greatly prolong the service life of products (Table 1).

TABLE 1

The vulcanized rubber has the advantages that the vulcanized rubber has the optimal physical and mechanical properties, good process performance, good wear resistance, optimal comprehensive performance and longest service life (note that the service life of general rubber shoes is 30-45 days under test conditions), and the flame resistance meets the requirements, wherein the vulcanized rubber comprises 50 parts of # 2 standard rubber, 18 parts of SN121 chloroprene rubber, 32 parts of butadiene rubber, 55 parts of N220 carbon black, 5 parts of solid coumarone and 11 parts of dibutyl phthalate.

2. Optimizing the system ratio of the accelerator and the anti-aging agent to obtain 3.5 parts of accelerator, namely 0.8 part of accelerator DM, 0.3 part of accelerator NA-22, 2.0 parts of accelerator CBS and 0.4 part of accelerator D; 1.0 part of anti-aging agent CD and 0.5 part of anti-aging agent 4010 NA; 3 '10-3' 30 of the vulcanization starting point at 143 ℃ cooperatively form an optimal network structure, thereby realizing wear resistance and high elasticity.

TABLE 2 optimization of accelerators and anti-aging systems

As can be seen from Table 2, the optimum amounts of accelerator and antioxidant are: 0.8 part of accelerator DM, 2.3 parts of accelerator CBS, 0.4 part of accelerator D, 1.0 part of antioxidant CD and 0.5 part of antioxidant 4010 NA.

3. And (4) matching the vulcanizing agent with the active agent.

TABLE 3 optimized sulfide dosage vs. active agent Performance

As shown in Table 3, the process performance safety, wear resistance and flame retardant effect of the rubber compound using 2.0 parts of sulfur, 5 parts of nano zinc oxide, 3 parts of stearic acid and 1 part of light magnesium oxide are all in good states.

4. Flame retardant ratio study

TABLE 4 COMPARATIVE PERFORMANCE TEST TABLE FOR FIRE-RETARDANT

The results in table 4 show that the optimal flame retardant ratio is: 20 parts of decabromodiphenyl ether, 10 parts of antimony trioxide, 20 parts of chlorinated paraffin-70 and 15 parts of zinc borate.

The physical properties of the product are obtained through a series of researches: the tensile strength is more than 11.5Mpa, the elongation at break is more than 380%, and the Akron abrasion is less than 0.35cm³The flame retardant rating of the flame retardant reaches UL94V-0 grade at 1.61 km.

Due to the adoption of the technical scheme, compared with the prior art, the natural rubber, the butadiene rubber and the SN 121-type chloroprene rubber are used as main materials, the physical properties of rubber materials are guaranteed by adding the reinforcing agent and the softening agent, so that the product has the advantages of wear resistance, wear resistance and the like, the service life of rubber soles is ensured, and the high-efficiency flame retardant decabromodiphenyl ether, chlorinated paraffin, zinc borate and antimony oxide are used as a flame retardant system together, so that excellent flame retardant performance is provided for the product; the flame-retardant rubber can generate a carbon layer during combustion to adsorb molten and ignited polymers, can prevent liquid drops from transmitting fire, overcomes the defect that the conventional NR + SBR + BR rubber compound is extremely easy to combust, has the flame-retardant grade reaching UL94V-0 grade, and meets the self-extinguishing requirement in a vertical combustion test. The method is simple, low in cost and good in using effect.

Detailed Description

Example 1 of the invention: the flame-retardant rubber sole comprises, by weight, 50 parts of No. 2 standard rubber, 18 parts of chloroprene rubber SN121, 32 parts of butadiene rubber, 2 parts of sulfur, 3.5 parts of an accelerator (each 3.5 parts of the accelerator consists of 0.8 part of an accelerator DM, 0.3 part of an accelerator NA-22, 2.0 parts of an accelerator CBS and 0.4 part of an accelerator D), 9 parts of a vulcanization activator (each 9 parts of the vulcanization activator consists of 3 parts of tertiary stearic acid, 5 parts of nano zinc oxide and 1 part of light magnesium oxide), 0.6 part of a mold release agent, 55 parts of carbon black, 16 parts of a softener (each 16 parts of the softener consists of 11 parts of dibutyl phthalate and 5 parts of solid coumarone), 65 parts of a mixed flame retardant (each 65 parts of the mixed flame retardant consists of 20 parts of decabromodiphenyl ether and 10 parts of antimony oxide, 20 parts of chlorinated paraffin (-70), 15 parts of zinc borate) and 1.5 parts of an anti-aging agent.

Adding 40 parts of natural rubber, 32 parts of butadiene rubber, 1.6 parts of stearic acid, 55 parts of carbon black and solid coumarone into an internal mixer, carrying out press mixing for 4-5 minutes, lifting a top bolt to scrape rubber when the current load of the rubber mixer is reduced to 220A, sending an overflowing material at the mouth of the internal mixer into an internal mixing chamber, finishing scraping within 15-25 seconds, adding 6 parts of dibutyl phthalate within next 30 seconds, returning the top bolt to the right position, continuing to carry out press mixing, carrying out press mixing for 3.5-4 minutes after the load of the rubber mixer is lifted, returning the load of the rubber mixer to above 160A, and discharging to obtain masterbatch;

and step two, standing the master batch for 12 hours, adding the master batch, 10 parts of natural rubber, 18 parts of SN121 chloroprene rubber, a mixed flame retardant and a medium material into an internal mixer, pressing for 50-65 seconds, adding the mixed flame retardant, pressing for 3-5 minutes, lifting a top bolt for scraping, pressing for 2 minutes, adding 5 parts of dibutyl phthalate when the internal of the internal mixer generates a muffling sound due to rubber material friction, performing rubber mixing for 1 minute after the load rises to 200A, discharging, adding sulfur into the discharged rubber material on an open rubber mixer, and uniformly turning to obtain a finished product.

Example 2 of the invention: the flame-retardant rubber sole comprises, by weight, 55 parts of No. 2 standard rubber, 18 parts of chloroprene rubber SN121, 27 parts of butadiene rubber, 2 parts of sulfur, 3.5 parts of an accelerator (each 3.5 parts of the accelerator consists of 0.8 part of an accelerator DM, 0.3 part of an accelerator NA-22, 2.0 parts of an accelerator CBS and 0.4 part of an accelerator D), 8.5 parts of a vulcanization activator (each 8.5 parts of the vulcanization activator consists of 3 parts of tertiary stearic acid, 4.5 parts of nano zinc oxide and 1 part of light magnesium oxide), 0.6 part of a mold release agent, 54 parts of N220 carbon black, 16 parts of a softener (each 16 parts of the softener consists of 11 parts of dibutyl phthalate and 5 parts of solid coumarone), 65 parts of a mixed flame retardant (each 65 parts of the mixed flame retardant consists of 20 parts of decabromodiphenyl ether and 10 parts of antimony oxide, 20 parts of chlorinated paraffin (-70), 15 parts of zinc borate) and 1.2 parts of an anti-aging agent.

Adding 40 parts of natural rubber, 27 parts of butadiene rubber, 1.6 parts of stearic acid, 54 parts of carbon black and solid coumarone into an internal mixer, carrying out press mixing for 4-5 minutes, lifting a top bolt to scrape rubber when the current load of the rubber mixer is reduced to 220A, sending an overflowing material at the mouth of the internal mixer into an internal mixing chamber, finishing scraping within 15-25 seconds, adding 6 parts of dibutyl phthalate within next 30 seconds, returning the top bolt to the right position, continuing to carry out press mixing, carrying out press mixing for 3.5-4 minutes after the load of the rubber mixer is lifted, returning the load of the rubber mixer to above 160A, and discharging to obtain masterbatch;

standing the master batch for 12 hours, adding the master batch, 15 parts of natural rubber, 18 parts of chloroprene rubber and a medium material into an internal mixer, pressing for 50-65 seconds, adding a mixed flame retardant, pressing for 3-5 minutes, lifting a top bolt to scrape rubber, pressing for 2 minutes, adding 5 parts of dibutyl phthalate when the internal of the internal mixer generates a muffling sound due to rubber material friction, mixing for 1 minute after the load rises to 200A, discharging, adding sulfur into the discharged rubber material on an open rubber mixer, and uniformly turning to obtain a finished product.

Example 3 of the invention: the flame-retardant rubber sole comprises, by weight, 52 parts of No. 2 standard rubber, 48 parts of synthetic rubber (28 parts of butadiene rubber and 20 parts of chloroprene rubber are used), 2 parts of sulfur, 3.5 parts of an accelerator (each 3.5 parts of the accelerator consists of 0.8 part of an accelerator DM, 0.3 part of an accelerator NA-22, 2.0 parts of an accelerator CBS and 0.4 part of an accelerator D), 8.0 parts of a vulcanization activator (each 8.5 parts of the vulcanization activator consists of 2.5 parts of tertiary stearic acid, 4.5 parts of nano zinc oxide and 1 part of light magnesium oxide), 0.6 part of a mold release agent, 73 parts of N220 carbon black, 16 parts of a softener (each 16 parts of the softener consists of 11 parts of dibutyl phthalate and 5 parts of solid coumarone), 65 parts of a mixed flame retardant (each 65 parts of a mixed flame retardant consists of 20 parts of decabromodiphenyl ether, 10 parts of antimony oxide, 20 parts of (-70) and 15 parts of zinc borate), 1.2 parts of an anti-aging agent.

Adding 40 parts of natural rubber, 28 parts of butadiene rubber, 1.6 parts of stearic acid, 55 parts of carbon black and solid coumarone into an internal mixer, carrying out press mixing for 4-5 minutes, lifting a top bolt to scrape rubber when the current load of the rubber mixer is reduced to 220A, sending an overflowing material at the mouth of the internal mixer into an internal mixing chamber, finishing scraping within 15-25 seconds, adding 6 parts of dibutyl phthalate within next 30 seconds, returning the top bolt to the right position, continuing to carry out press mixing, carrying out press mixing for 3.5-4 minutes after the load of the rubber mixer is lifted, returning the load of the rubber mixer to above 160A, and discharging to obtain masterbatch;

standing the master batch for 12 hours, adding the master batch, 12 parts of natural rubber, 20 parts of chloroprene rubber and a medium material into an internal mixer, pressing for 50-65 seconds, adding a mixed flame retardant, pressing for 3-5 minutes, lifting a top bolt to scrape rubber, pressing for 2 minutes, adding 5 parts of dibutyl phthalate when the internal of the internal mixer generates a muffling sound due to rubber material friction, mixing for 1 minute after the load rises to 200A, discharging, adding sulfur into the discharged rubber material on an open rubber mixer, and uniformly turning to obtain a finished product.