A rubber-plastic composite material based on ethylene-propylene-diene rubber and a production process thereof

Abstract

The application relates to the technical field of materials, and discloses a rubber-plastic composite material based on a ternary ethylene-propylene rubber and a production process thereof. The composite material is prepared through a closed mixing, extrusion and vulcanization foaming process by taking the ternary ethylene-propylene rubber and ethylene-vinyl acetate copolymer as base materials and taking modified palygorskite functional materials and the like as auxiliary materials. The modified palygorskite functional material is prepared by modifying a macromolecular polymer of methyltrisiloxane-phosphorus derivative alternately connected on the surface of the palygorskite. The palygorskite can efficiently exert the advantages of the inorganic additive, and improve the mechanical strength of the rubber-plastic composite material. The phosphorus element of the macromolecular polymer can promote the rapid formation of a dense carbon layer on the surface of the material when combustion occurs. The silicon element can form silicon oxide deposited on the surface of the carbon layer, improve the strength of the carbon layer, form a high-strength carbon layer, and synergize with the palygorskite to effectively improve the flame-retardant performance of the rubber-plastic composite material.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and in particular to an EPDM-based rubber-plastic composite material and a production process thereof. Background Art

[0002] Rubber-plastic composite foam material is based on rubber and plastic and is made through a vulcanization foaming process. Due to the closed bubble structure inside the material, the density can be significantly reduced. This feature not only reduces product weight and transportation costs, but also facilitates installation and construction. Therefore, it has excellent sound insulation, shock absorption, and heat insulation effects, and is therefore widely used in various industries.

[0003] Among numerous rubber substrates, EPDM (ethylene propylene diene monomer) has become a key base material for rubber-plastic composite foam materials due to its excellent mechanical properties, weather resistance, corrosion resistance, and ozone resistance. Ethylene-vinyl acetate copolymer (EVA) possesses excellent flexibility and chemical resistance. Therefore, using EPDM and EVA as base materials can leverage their complementary strengths to produce excellent rubber-plastic composite foam materials.

[0004] Although rubber-plastic composite foam materials have excellent properties, they are extremely prone to combustion due to their unique bubble structure, and are also accompanied by the phenomenon of molten dripping, causing the fire to spread rapidly. In the current era of frequent fires, this undoubtedly has a huge negative impact on the application prospects of rubber-plastic composite foam materials. The existing technology generally achieves the purpose of improving the flame retardant properties of rubber-plastic materials by adding flame retardants. For example, the invention patent with publication number CN111662512B discloses a rubber-plastic foam material and a preparation method thereof, which achieves flame retardant modification by adding a high content of inorganic flame retardant. However, excessive content of inorganic flame retardant will have a negative effect on the mechanical properties of the material. Based on this, the present invention provides a rubber-plastic composite material that can solve the problems existing in the existing technology. Summary of the Invention

[0005] In order to solve the problems mentioned in the background technology, the purpose of the present invention is to provide a rubber-plastic composite material based on EPDM rubber and a production process thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A rubber-plastic composite material based on EPDM rubber, comprising the following raw materials in parts by weight:

[0008] 35-45 parts of EPDM rubber;

[0009] 10-15 parts of ethylene-vinyl acetate copolymer;

[0010] 15-20 parts of chlorinated paraffin oil;

[0011] 3-6.5 parts of modified palygorskite functional material;

[0012] 5-10 parts of foaming agent;

[0013] 0.2-0.5 parts of vulcanizing agent;

[0014] 1-2 parts zinc oxide;

[0015] 2-6 parts of accelerator;

[0016] Carbon black 0.5-1 part;

[0017] 5-12 parts of polyethylene wax.

[0018] As a further embodiment of the present invention, the modified palygorskite functional material is prepared by the following method:

[0019] Step 1: Add palygorskite to tetrahydrofuran, ultrasonically disperse it evenly, raise the temperature to 50-60°C, continue to add dimethylchlorosilane and accelerator, and after the addition is completed, keep stirring for 4-6 hours, stop heating, cool the material, centrifuge the solid material, wash it, and vacuum dry it to obtain organic palygorskite;

[0020] Step 2: Disperse the organic palygorskite in an N,N-dimethylformamide medium to form a uniform dispersion, then add an excess of a diene-substituted phosphorus-containing derivative and a catalyst to the dispersion, turn on the heating, raise the temperature to 80-90°C, keep stirring for 2-4 hours, continue to add an excess of a methyltrisiloxane derivative, complete the addition, stir evenly, then raise the temperature to 90-100°C, keep stirring for 12-16 hours, stop heating, cool and discharge the material, and the modified palygorskite functional material can be obtained.

[0021] As a further embodiment of the present invention, in step 1, the accelerator is triethylamine.

[0022] As a further embodiment of the present invention, in step 2, the preparation method of the diene-substituted phosphorus-containing derivative is as follows:

[0023] Add diallylcarbamoyl chloride and phosphorus oxychloride compounds to toluene, heat to 50-60°C, stir until completely dissolved, introduce nitrogen protection, then heat to 80-90°C, continue to keep warm and stir for 6-12 hours, remove the solvent by rotary evaporation, cool and discharge, and purify to obtain a diene-substituted phosphorus-containing derivative.

[0024] As a further embodiment of the present invention, the phosphorus oxychloride compound is any one of diisobutyl phosphite, diisopropyl phosphite, diisooctyl phosphite or dibenzyl phosphite.

[0025] As a further embodiment of the present invention, the molar ratio of the diallylcarbamoyl chloride to the phosphorus oxychloride compound is 1:1.

[0026] As a further embodiment of the present invention, in step 2, the catalyst is chloroplatinic acid.

[0027] As a further embodiment of the present invention, in step 2, the methyltrisiloxane derivative is 1,1,3,3,5,5-hexamethyltrisiloxane or 1,1,3,3,5,5,7,7-octamethyltetrasiloxane.

[0028] In the above technical solution, dimethylchlorosilane is first used as a modifier. Under the action of a promoter, the Si-Cl in its structure can replace the hydroxyl group on the surface of palygorskite, thereby achieving organic modification of the palygorskite and preparing an organic palygorskite. Then, under the action of a chloroplatinic acid catalyst, the Si-H on the surface of the organic palygorskite can undergo hydrosilylation with the unsaturated alkenyl substituent in the structure of the diene-substituted phosphorus-containing derivative. The excess diene-substituted phosphorus-containing derivative and methyltrisiloxane derivative in the system will undergo continuous hydrosilylation on the surface of the palygorskite, thereby forming a macromolecular polymer of alternating methyltrisiloxane-phosphorus derivatives on the surface of the palygorskite, thereby preparing a modified palygorskite functional material.

[0029] Among them, the diene-substituted phosphorus-containing derivative is prepared by using diallylcarbamoyl chloride and phosphorus oxychloride compounds as reactants, and utilizing the principle that the acyl chloride groups in each other's structures can react with PH to obtain a diene-substituted phosphorus-containing derivative containing two equivalents of unsaturated alkenyl substituents in the structure.

[0030] As a further embodiment of the present invention, the foaming agent is azodicarbonamide; the vulcanizing agent is sulfur; and the accelerator is a mixture of accelerator DPTT and accelerator EZ, with a mass ratio of 1:0.5-1.

[0031] A production process for a rubber-plastic composite material based on EPDM rubber comprises the following steps:

[0032] The first step is to prepare all the raw materials according to the weight ratio;

[0033] Step 2: Add EPDM rubber, ethylene-vinyl acetate copolymer, chlorinated paraffin oil, modified palygorskite functional material, foaming agent, zinc oxide, carbon black and polyethylene wax into an internal mixer, mix them uniformly at a temperature of 130-140°C, transfer them to an open mixer, roll them into sheets, cool them naturally and leave them for 24-36 hours to form a precursor material;

[0034] The third step is to add the vulcanizing agent and accelerator to the precursor in a secondary open milling manner. After mixing, transfer it to the extruder for extrusion. Control the head temperature at 50-70°C and add the extruded rubber material to the oven for vulcanization and foaming. The vulcanization and foaming are carried out at six different temperatures, namely 130±2°C, 140±2°C, 155±2°C, 170±2°C, 183±2°C, and 190±2°C. After completion, cool it with air.

[0035] Beneficial effects of the present invention:

[0036] The present invention modifies the surface of palygorskite with a macromolecular polymer in which methyl trisiloxane and phosphorus derivatives are alternately connected, and uses the modified palygorskite as a functional material. Since the macromolecular polymer forms a "transition" between the palygorskite and the EPDM rubber, the interfacial compatibility between the palygorskite and the EPDM rubber can be improved. On the one hand, the palygorskite can be enabled to effectively exert its advantages as an inorganic additive and improve the mechanical strength of the rubber-plastic composite material. In addition, the phosphorus element in the macromolecular polymer structure can promote the rapid formation of a dense carbon layer on the surface of the material when combustion occurs, thereby preventing the combustion from continuing. The silicon element can form silicon oxide and be deposited on the surface of the carbon layer, thereby improving the strength of the carbon layer, thereby isolating oxygen and heat from the outside through the carbon layer. At the same time, the layered chain structure of the palygorskite can cooperate with the carbon layer to prevent the combustion from continuing, thereby effectively improving the flame retardant properties of the rubber-plastic composite material.

[0037] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 This is the infrared test image of the diene-substituted phosphorus-containing derivative. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] Example 1

[0042] A rubber-plastic composite material based on EPDM rubber, comprising the following raw materials in parts by weight:

[0043] 35 parts of EPDM rubber;

[0044] 10 parts of ethylene-vinyl acetate copolymer;

[0045] 15 parts of chlorinated paraffin oil;

[0046] 3 parts of modified palygorskite functional material;

[0047] 5 parts of azodicarbonamide, a foaming agent;

[0048] 0.2 parts of sulfur;

[0049] 1 part zinc oxide;

[0050] 2 parts of accelerator;

[0051] 0.5 parts of carbon black;

[0052] 5 parts of polyethylene wax.

[0053] The production process of the rubber-plastic composite material comprises the following steps:

[0054] The first step is to prepare all the raw materials according to the weight ratio;

[0055] In the second step, EPDM rubber, ethylene-vinyl acetate copolymer, chlorinated paraffin oil, modified palygorskite functional material, foaming agent azodicarbonamide, zinc oxide, carbon black and polyethylene wax are added to an internal mixer, mixed uniformly at a temperature of 130° C., and then transferred to an open mixer, rolled into sheets, cooled naturally and left to stand for 24 hours to form a precursor material;

[0056] The third step is to add sulfur and accelerator to the precursor material in a secondary open milling manner, mix well, transfer to the extruder for extrusion, control the head temperature at 50°C, add the extruded rubber material to the oven for vulcanization and foaming, and vulcanization and foaming are carried out at six different temperatures, namely 130±2°C, 140±2°C, 155±2°C, 170±2°C, 183±2°C, and 190±2°C. After completion, cool it with air.

[0057] The accelerator is a mixture of accelerator DPTT and accelerator EZ, with a mass ratio of 1:1, and the same applies to the following.

[0058] The modified palygorskite functional material is prepared by the following method:

[0059] Step 1: add 1.8 g of palygorskite to tetrahydrofuran, ultrasonically disperse it, raise the temperature to 50°C, continue to add 3.4 g of dimethylchlorosilane and 0.5 g of triethylamine, and after the addition is complete, keep stirring for 6 hours, stop heating, cool the material, centrifuge the solid material, wash it, and vacuum dry it to obtain an organic palygorskite;

[0060] Step 2: 1.5 g of organic palygorskite is dispersed in an N,N-dimethylformamide medium to form a uniform dispersion, and then 5.5 g of a diene-substituted phosphorus derivative and 0.01 g of chloroplatinic acid are added to the dispersion, and heating is turned on to raise the temperature to 85 ° C. After stirring for 3 hours, 4.8 g of 1,1,3,3,5,5,7,7-octamethyltetrasiloxane is added. After the addition is completed, stir evenly, and then the temperature is raised to 95 ° C. After continuous stirring for 15 hours, the heating is stopped, the temperature is cooled and the material is discharged to obtain a modified palygorskite functional material.

[0061] The preparation method of the diene-substituted phosphorus-containing derivative is as follows:

[0062] Add 0.4 g of diallylcarbamoyl chloride and 0.42 g of diisopropyl phosphite to toluene, heat to 55°C, stir until completely dissolved, introduce nitrogen protection, then raise the temperature to 85°C, keep stirring for 9 hours, remove the solvent by rotary evaporation, cool and discharge the material, and purify it to obtain a diene-substituted phosphorus-containing derivative.

[0063] Figure 1 This is the infrared test pattern of the diene-substituted phosphorus-containing derivative, where 3000-3100 cm -1 The characteristic absorption peak at 1762 cm is attributed to the CH characteristic absorption peak in the unsaturated olefinic functional group. -1 The characteristic absorption peak at 1294 cm is the C=O characteristic absorption peak. -1 The characteristic absorption peak at 2350-2440 cm-1 is attributed to the characteristic absorption peak of P=O. -1 Obvious pH characteristic absorption peaks were observed.

[0064] Example 2

[0065] A rubber-plastic composite material based on EPDM rubber, comprising the following raw materials in parts by weight:

[0066] 36 parts of EPDM rubber;

[0067] 12 parts of ethylene-vinyl acetate copolymer;

[0068] 18 parts of chlorinated paraffin oil;

[0069] 6 parts of modified palygorskite functional material;

[0070] 8 parts of foaming agent;

[0071] 0.3 parts of sulfur;

[0072] 1.5 parts of zinc oxide;

[0073] 4 parts of accelerator;

[0074] 0.8 parts of carbon black;

[0075] 6 parts of polyethylene wax.

[0076] The production process of the rubber-plastic composite material comprises the following steps:

[0077] The first step is to prepare all the raw materials according to the weight ratio;

[0078] Step 2: Add EPDM rubber, ethylene-vinyl acetate copolymer, chlorinated paraffin oil, modified palygorskite functional material, foaming agent, zinc oxide, carbon black and polyethylene wax into an internal mixer, mix them uniformly at 135°C, transfer them to an open mixer, roll them into sheets, cool them naturally and leave them for 36 hours to form a precursor material;

[0079] The third step is to add sulfur and accelerator to the precursor material in a secondary open milling manner, mix well, transfer to the extruder for extrusion, control the head temperature at 60°C, add the extruded rubber material to the oven for vulcanization and foaming, and vulcanization and foaming are carried out at six different temperatures, namely 130±2°C, 140±2°C, 155±2°C, 170±2°C, 183±2°C, and 190±2°C. After completion, cool it with air.

[0080] Example 3

[0081] A rubber-plastic composite material based on EPDM rubber, comprising the following raw materials in parts by weight:

[0082] 45 parts of EPDM rubber;

[0083] 15 parts of ethylene-vinyl acetate copolymer;

[0084] 20 parts of chlorinated paraffin oil;

[0085] 6.5 parts of modified palygorskite functional material;

[0086] 10 parts of foaming agent;

[0087] 0.5 parts of sulfur;

[0088] 2 parts zinc oxide;

[0089] 6 parts of accelerator;

[0090] 1 part carbon black;

[0091] 12 parts of polyethylene wax.

[0092] The production process of the rubber-plastic composite material comprises the following steps:

[0093] The first step is to prepare all the raw materials according to the weight ratio;

[0094] Step 2: Add EPDM rubber, ethylene-vinyl acetate copolymer, chlorinated paraffin oil, modified palygorskite functional material, foaming agent, zinc oxide, carbon black and polyethylene wax into an internal mixer, mix them uniformly at 140°C, transfer them to an open mixer, roll them into sheets, cool them naturally and leave them for 36 hours to form a precursor material;

[0095] The third step is to add sulfur and accelerator to the precursor material in a secondary open milling manner, mix well, transfer to the extruder for extrusion, control the head temperature at 70°C, add the extruded rubber material to the oven for vulcanization and foaming, and vulcanization and foaming are carried out at six different temperatures, namely 130±2°C, 140±2°C, 155±2°C, 170±2°C, 183±2°C, and 190±2°C. After completion, cool it with air.

[0096] Comparative Example 1

[0097] A rubber-plastic composite material based on EPDM rubber, comprising the following raw materials in parts by weight:

[0098] 36 parts of EPDM rubber;

[0099] 12 parts of ethylene-vinyl acetate copolymer;

[0100] 18 parts of chlorinated paraffin oil;

[0101] 6 parts of palygorskite;

[0102] 8 parts of foaming agent;

[0103] 0.3 parts of sulfur;

[0104] 1.5 parts of zinc oxide;

[0105] 4 parts of accelerator;

[0106] 0.8 parts of carbon black;

[0107] 6 parts of polyethylene wax.

[0108] The production process of the rubber-plastic composite material comprises the following steps:

[0109] The first step is to prepare all the raw materials according to the weight ratio;

[0110] In the second step, EPDM rubber, ethylene-vinyl acetate copolymer, chlorinated paraffin oil, palygorskite, foaming agent, zinc oxide, carbon black and polyethylene wax are added to an internal mixer, mixed uniformly at a temperature of 135° C., and then transferred to an open mixer, rolled into sheets, cooled naturally and left to stand for 36 hours to form a precursor material;

[0111] The third step is to add sulfur and accelerator to the precursor material in a secondary open milling manner, mix well, transfer to the extruder for extrusion, control the head temperature at 60°C, add the extruded rubber material to the oven for vulcanization and foaming, and vulcanization and foaming are carried out at six different temperatures, namely 130±2°C, 140±2°C, 155±2°C, 170±2°C, 183±2°C, and 190±2°C. After completion, cool it with air.

[0112] Comparative Example 2

[0113] A rubber-plastic composite material based on EPDM rubber, comprising the following raw materials in parts by weight:

[0114] 36 parts of EPDM rubber;

[0115] 12 parts of ethylene-vinyl acetate copolymer;

[0116] 18 parts of chlorinated paraffin oil;

[0117] 8 parts of foaming agent;

[0118] 0.3 parts of sulfur;

[0119] 1.5 parts of zinc oxide;

[0120] 4 parts of accelerator;

[0121] 0.8 parts of carbon black;

[0122] 6 parts of polyethylene wax.

[0123] The production process of the rubber-plastic composite material comprises the following steps:

[0124] The first step is to prepare all the raw materials according to the weight ratio;

[0125] In the second step, EPDM rubber, ethylene-vinyl acetate copolymer, chlorinated paraffin oil, foaming agent, zinc oxide, carbon black and polyethylene wax are added to an internal mixer, mixed uniformly at a temperature of 135°C, and then transferred to an open mixer for rolling into sheets. After natural cooling, the sheets are left for 36 hours to form a precursor material.

[0126] The third step is to add sulfur and accelerator to the precursor material in a secondary open milling manner, mix well, transfer to the extruder for extrusion, control the head temperature at 60°C, add the extruded rubber material to the oven for vulcanization and foaming, and vulcanization and foaming are carried out at six different temperatures, namely 130±2°C, 140±2°C, 155±2°C, 170±2°C, 183±2°C, and 190±2°C. After completion, cool it with air.

[0127] Performance Testing

[0128] The rubber-plastic composite materials in the examples and comparative examples were made into test specimens that met the specifications and subjected to various performance tests;

[0129] Conduct flame retardant performance test according to standard GB / T 2406.2-2009;

[0130] Compressive strength test is carried out according to the standard GB / T 8813-2020;

[0131] The test results are shown in the table below:

[0132]

[0133] Analysis and test results show that the rubber-plastic composite material obtained by directly adding unmodified palygorskite as an additive has obvious poor mechanical properties and flame retardant properties. This is because after the surface modification is lost, the phosphorus and silicon flame retardant elements in the modifier cannot be used to form a dense carbon layer, and agglomeration may have occurred, leading to the above phenomenon.

[0134] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

[0135] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A rubber-plastic composite material based on EPDM rubber, characterized in that: According to parts by weight, the following raw materials are included: 35-45 parts of EPDM rubber; 10-15 parts of ethylene-vinyl acetate copolymer; 15-20 parts of chlorinated paraffin oil; 3-6.5 parts of modified palygorskite functional material; 5-10 parts of foaming agent; 0.2-0.5 parts of vulcanizing agent; 1-2 parts zinc oxide; 2-6 parts of accelerator; Carbon black 0.5-1 part; 5-12 parts of polyethylene wax; The modified palygorskite functional material is prepared by the following method: Step 1: Under the action of a promoter, dimethylchlorosilane is used to modify the surface of palygorskite to obtain an organic palygorskite; Step 2: In an N,N-dimethylformamide medium, using a diene-substituted phosphorus-containing derivative as a linker, under the action of a catalyst, the organic palygorskite and the methyltrisiloxane derivative are connected, and the added excess diene-substituted phosphorus-containing derivative and methyltrisiloxane derivative are in situ polymerized on the surface of the organic palygorskite to obtain a modified palygorskite functional material.

2. The EPDM-based rubber-plastic composite material according to claim 1, characterized in that: In step 1, the accelerator is triethylamine.

3. The EPDM-based rubber-plastic composite material according to claim 1, characterized in that: In step 2, the diene-substituted phosphorus-containing derivative is prepared by reacting diallylcarbamoyl chloride and a phosphorus oxychloride compound as raw materials.

4. The EPDM-based rubber-plastic composite material according to claim 3, characterized in that: The phosphorus oxychloride compound is any one of diisobutyl phosphite, diisopropyl phosphite, diisooctyl phosphite or dibenzyl phosphite.

5. The EPDM-based rubber-plastic composite material according to claim 3, characterized in that: The molar ratio of the diallylcarbamoyl chloride to the phosphorus oxychloride compound is 1:

1.

6. The EPDM-based rubber-plastic composite material according to claim 1, characterized in that: In step 2, the catalyst is chloroplatinic acid.

7. The EPDM-based rubber-plastic composite material according to claim 1, characterized in that: In step 2, the methyltrisiloxane derivative is 1,1,3,3,5,5-hexamethyltrisiloxane or 1,1,3,3,5,5,7,7-octamethyltetrasiloxane.

8. The EPDM-based rubber-plastic composite material according to claim 1, characterized in that: The foaming agent is azodicarbonamide; the vulcanizing agent is sulfur; and the accelerator is a mixture of accelerator DPTT and accelerator EZ, with a mass ratio of 1:0.5-1.

9. A production process for the EPDM-based rubber-plastic composite material according to claim 1, characterized in that: The following steps are involved: The first step is to prepare all the raw materials according to the weight ratio; Step 2: Add EPDM rubber, ethylene-vinyl acetate copolymer, chlorinated paraffin oil, modified palygorskite functional material, foaming agent, zinc oxide, carbon black and polyethylene wax into an internal mixer, mix them uniformly at a temperature of 130-140°C, transfer them to an open mixer, roll them into sheets, cool them naturally and leave them for 24-36 hours to form a precursor material; The third step is to add the vulcanizing agent and accelerator to the precursor in a secondary open milling manner. After mixing, transfer it to the extruder for extrusion. Control the head temperature at 50-70°C and add the extruded rubber material to the oven for vulcanization and foaming. The vulcanization and foaming are carried out at six different temperatures, namely 130±2°C, 140±2°C, 155±2°C, 170±2°C, 183±2°C, and 190±2°C. After completion, cool it with air.

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