Modified NBR / PVC foam material and preparation method thereof

Abstract

The invention discloses a modified NBR / PVC foam material and a preparation method thereof, and relates to the technical field of foam materials. The material comprises the following components in parts by weight: 100 parts of NBR, 28 parts of PVC, 8-12 parts of calcium carbonate, 1 part of a heat stabilizer, 1.2 parts of a vulcanizing agent, 1.3 parts of an accelerant, 1-2 parts of an anti-aging agent, 30 parts of a plasticizer, 0.5-2 parts of a flame retardant, 8-12 parts of a rubber reinforcing agent and 8 parts of a foaming agent. Wherein the main component of the heat stabilizer is an epoxy fatty acid calcium-zinc stabilizer, and a quantitative auxiliary heat stabilizer is added into the heat stabilizer; the proportion and components of the calcium-zinc stabilizer are adjusted to a certain degree, the calcium-zinc stabilizer is combined with the amino crotonate, the alpha-phenylindole and the zeolite for utilization, the same thermal stability effect as a plumbate stabilizer is achieved, meanwhile, the calcium-zinc stabilizer has non-toxic and environment-friendly performance, and vulcanization pollution in the production process is reduced; and the problems of high consumption of the lubricant and damage to lubrication balance are solved.

Description

[0001] This application is a divisional application. The application number of the parent case is 202111664092.X, the application date is December 30, 2021, and the invention title is "A Modified NBR / PVC Foaming Material and Its Preparation Method". Technical Field

[0002] The present invention relates to the technical field of foaming materials, and particularly to a modified NBR / PVC foaming material and its preparation method. Background Art

[0003] Soft foaming materials are made from raw materials such as plastics (PE, EVA, etc.) and rubbers (SBR, CR, etc.), along with auxiliary materials such as catalysts, foam stabilizers, and blowing agents. Through physical foaming or cross-linking foaming, a large number of fine bubbles appear in the plastics and rubbers, increasing the volume and reducing the density. Soft foaming materials are light in weight and good in softness, and have functions such as buffering, sound absorption, shock absorption, heat preservation, and filtration. They are widely used in industries such as electronics, household appliances, automobiles, and sports and leisure.

[0004] Nitrile rubber (NBR) is a synthetic rubber prepared by emulsion polymerization of butadiene and acrylonitrile. NBR foaming materials have extremely strong oil resistance, excellent adhesiveness, and aging resistance. However, their physical and mechanical properties such as tensile strength, hardness, modulus at a specified elongation, and tear strength are poor.

[0005] To obtain better performance, generally, PVC materials with good commonality are added to NBR. The solubility parameters and polarities of polyvinyl chloride (PVC) and nitrile rubber (NBR) are similar, and the two have good compatibility. Using their blend as the matrix of the foaming material can make the foamed products have both the elasticity of rubber foamed products and the good rigidity and small shrinkage rate of plastic foamed products.

[0006] Currently, Chinese Patent No. CN104804252A discloses a high-strength NBR / PVC foaming material and its preparation method, including the following raw materials in parts by weight: 20 - 24 parts of nitrile rubber, 16 - 20 parts of polyvinyl chloride, 22 - 26 parts of filler, 14 - 18 parts of plasticizer, 3.6 - 4 parts of blowing agent, 3.6 - 4.2 parts of sulfur masterbatch, 5 - 7 parts of carbon black, 0.6 - 1 part of zinc oxide, 0.8 - 1.2 parts of stearic acid, 0.8 - 1.2 parts of polyethylene glycol, 0.6 - 1.2 parts of paraffin, 0.3 - 0.5 part of antioxidant, 0.5 - 0.7 part of chewing agent, 2 - 4 parts of rubber tear resistance agent, and 2 - 2.4 parts of accelerator masterbatch.

[0007] This high-strength NBR / PVC foaming material can decompose smoothly and relatively quickly during the calendering process to form uniform pores, improving the density and tensile strength of the foaming material. However, due to the poor thermal stability of PVC materials during production, stabilizers need to be added to inhibit their decomposition. Currently, low-cost lead salt stabilizers are widely used. Lead salt stabilizers themselves have certain toxicity and are prone to sulfur pollution during processing and cannot be used in transparent products. Therefore, many foaming materials are not suitable for lead salt stabilizers. Summary of the Invention

[0008] In view of the above technical problems and overcoming the disadvantages of the prior art, the present invention provides a modified NBR / PVC foaming material and a preparation method thereof.

[0009] To solve the above technical problems, the present invention provides a modified NBR / PVC foaming material and a preparation method thereof.

[0010] Technical effect: The present invention adjusts the ratio and components of calcium-zinc stabilizers to a certain extent, combines and utilizes them with aminocrotonic acid ester, α-phenylindole and zeolite, replaces lead salt stabilizers, achieves the same thermal stability effect as lead salt stabilizers, and at the same time has the non-toxic and environmentally friendly performance that lead salt stabilizers do not have, reducing the sulfur pollution during the production of foaming materials; at the same time, by changing certain processing conditions, the problem that calcium-zinc stabilizers need to consume a large amount of lubricants and cause damage to the lubrication balance is solved.

[0011] The further limited technical solution of the present invention is: A modified NBR / PVC foaming material, comprising the following components in proportion:

[0012]

[0013] Among them, the main component of the heat stabilizer is epoxy fatty acid calcium-zinc stabilizer, and a certain amount of auxiliary heat stabilizer is added thereto. The specific ratio is:

[0014]

[0015] When preparing the heat stabilizer, first add epoxy plasticizer, aminocrotonic acid ester, and α-phenylindole to the epoxy fatty acid calcium-zinc stabilizer main agent at the same time, then add organic phosphite auxiliary antioxidant and β-diketone auxiliary stabilizer in sequence, and finally add polyol catalyst, zeolite and hydrotalcite at the same time.

[0016] By adopting the above technical solution, after adding the epoxy plasticizer to the heat stabilizer main agent, when the PVC material releases hydrogen chloride when heated, the epoxy group in the epoxy plasticizer can absorb hydrogen chloride and generate o-chlorohydrin to cut off the growth of the conjugated chain, form a cyclic compound, reduce the zinc burning generated during the processing of the PVC material, and improve the thermal stability and mechanical properties of the NBR / PVC foaming material;

[0017] Secondly, ethyl aminocrotonate and α-phenylindole are added to the main heat stabilizer. Ethyl aminocrotonate and α-phenylindole can cooperate with the epoxide, greatly enhancing the heat stabilization effect of the calcium-zinc stabilizer. At the same time, during the processing of the foaming material, they can undergo a substitution reaction with the suspended chlorine atoms and combine with hydrogen chloride, greatly enhancing the stability of the PVC material during the processing;

[0018] Thirdly, the organic phosphite auxiliary antioxidant can react with hydroperoxides to be reduced to alcohols. At the same time, its hindered group can form a PVC degradation reaction terminator, ensuring the smooth progress of the PVC reaction. In addition, phosphite can also act as a turbidity inhibitor during the PVC processing, significantly improving the transparency and color purity of the NBR / PVC foaming material;

[0019] In addition, the β-diketone auxiliary stabilizer can cooperate with most stabilizers, enhancing the synergistic effect between components, greatly improving the transparency of the product, reducing the occurrence of zinc burning, and also improving the discoloration of PVC products during storage, enhancing the weather resistance of the product; and adding a polyol catalyst can form a complex with zinc stearate and zinc chloride. On the one hand, it accelerates the substitution rate of chlorine atoms on allyl chloride, and on the other hand, it inhibits the catalytic effect of zinc chloride on the degradation of polyvinyl chloride, inhibiting zinc burning;

[0020] Finally, hydrotalcite has excellent heat stabilization, absorbs chlorine atoms, and finally forms the structure of magnesium-aluminum hydrotalcite. It can be used in combination with the main heat stabilizer to improve the heat stability of the PVC material, and can also enhance the flame retardancy of the material. By using its own lubricating properties to achieve lubrication, it reduces the use of lubricants and controls production costs; and zeolite is an inorganic material with a special pore structure, having excellent adsorption and catalytic properties, which can inhibit zinc burning, enhance the long-term static and dynamic stability of PVC products, and reduce the equilibrium torque.

[0021] Furthermore, the polyol catalyst is pentaerythritol or polyvinyl alcohol or sorbitol or mannitol; the epoxy plasticizer is epoxy soybean oil or epoxy linseed oil or epoxy stearate; the organic phosphite auxiliary antioxidant is phenyl diisooctyl phosphite or octyl phosphite or diphenyl decyl phosphite; the β-diketone auxiliary stabilizer is isovaleryl benzoyl methane or β-diketone T-247 or pyrrolidine-2,4-dione.

[0022] Furthermore, the vulcanizing agent is zinc stearate and sulfur; the accelerator is 2-mercaptobenzothiazole or zinc diethyldithiocarbamate, and tetra methyl thiuram disulfide and N-cyclohexyl-2-benzothiazole sulfenamide are added for combined use:

[0023] By adopting the above technical solutions,

[0024] Further, the anti-aging agent is antioxidant 4010NA or antioxidant AW or p-phenylenediamine antioxidant, and antioxidant RD is added for combined use; the plasticizer is diisononyl phthalate; the rubber reinforcing agent is carbon black:

[0025] By adopting the above technical solution,

[0026] Further, the flame retardant is decabromodiphenylethane, and antimony trioxide is added for combined use; the foaming agent is N,N'-dinitrosopentamethylenetetramine, and a foaming aid is added for combined use, and the foaming aid is urea resin BK:

[0027] By adopting the above technical solution,

[0028] Another object of the present invention is to provide a modified NBR / PVC foaming material and a preparation method thereof, and the specific technical solution is as follows:

[0029] A modified NBR / PVC foaming material and a preparation method thereof, comprising the following steps:

[0030] S1, PVC pre-swelling. Take a quantitative amount of PVC particles, heat them to 80°C, then add a plasticizer and a heat stabilizer and stir evenly to form a paste, and let it stand for 2 h at 80°C;

[0031] S2, PVC plasticization. Place the pre-swollen PVC material in an internal mixer for plasticization. Wait until the PVC turns into a continuous transparent state, and keep the temperature of the internal mixer at room temperature; take a quantitative amount of NBR and perform three-stage plastic refining treatment on it;

[0032] S3, NBR / PVC blending. Put the three-stage plastic refined NBR material into an internal mixer, add calcium carbonate, a promoter, an anti-aging agent, a flame retardant and a rubber reinforcing agent, mix for 6 - 9 min until evenly mixed, then discharge and take out, thin pass 3 - 5 times to make an NBR / PVC masterbatch. Add a foaming agent and a vulcanizing agent to the NBR / PVC masterbatch on the roll of a low-temperature open mill for mixing. After completion, let it stand for 24 h until it reaches room temperature and then cut into sheets;

[0033] S4, foaming. Place the obtained NBR / PVC masterbatch sheet on a flat vulcanizer for mold pressing and foaming. The foaming temperature is 172°C - 176°C, and foam for 10 min to obtain the finished product, and then cool and package.

[0034] Further, in S2, the temperature in the internal mixer during plasticization is 150°C, the plasticization time is 3 - 5 min, and the rotation speed is 57 - 63 r / min.

[0035] Preferably, the discharge temperature in S3 is controlled at 147 - 153°C, and the foaming pressure in S4 is 14 - 16 MPa.

[0036] In summary, the present invention has the following beneficial effects:

[0037] (1) In the present invention, components such as epoxy plasticizer, zeolite, amino crotonate, and α-phenyl indole are added to the calcium-zinc stabilizer, achieving a thermal stability effect at the same or even higher level as that of lead-based stabilizers. At the same time, through the properties of components such as zeolite, the sulfurization pollution generated during the processing of PVC materials is reduced. The problem of lubrication balance destruction caused by the consumption of a large amount of lubricants in the calcium-zinc stabilizer is reduced by components such as hydrotalcite, improving the quality of the foaming material. At the same time, compared with lead-based stabilizers, the production cost of the present invention is low, and it has non-toxic and environmentally friendly properties, avoiding environmental pollution caused by the use of lead-based stabilizers, and also improving the mechanical strength and performance of the foaming material itself, and enhancing the stability of the long-term static foaming material;

[0038] (2) In the present invention, after adding the heat stabilizer of the present invention, the phenomenon of zinc burning generated during the processing of PVC materials can be reduced, improving the mechanical properties and thermal stability of the foaming material. By adding materials such as phosphite ester, it can play an anti-clouding role, enhancing the overall transparency and color purity of the foaming material, improving the discoloration situation of the foaming material during storage, and enhancing the overall weather resistance;

[0039] (3) In the present invention, adding zeolite and hydrotalcite can play a lubricating role, reducing the use of lubricants, lowering the production cost and the influence of lubricants on the properties of the foaming material, and also enhancing the overall long-term static and dynamic stability of the foaming material and reducing the balance torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a diagram showing the influence of PVC content on the properties of the foaming material in Example 1.

[0041] Figure 2 It is a diagram showing the influence of PVC content on the physical properties of the foaming material in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0042] A modified NBR / PVC foaming material provided in this embodiment includes the following proportion components:

[0043]

[0044] Among them, the vulcanizing agents are zinc stearate and sulfur; zinc stearate is mainly used as a lubricant and demolding agent for styrene resins, phenolic resins, and amino resins. At the same time, it also has the functions of a vulcanization activator and a softening agent in rubber. Therefore, it can also play roles of lubrication, thermal stability, and foam promotion in the foaming material.

[0045] The accelerator is 2-mercaptobenzothiazole or zinc diethyldithiocarbamate, and tetra methyl thiuram disulfide and N-cyclohexyl-2-benzothiazole sulfenamide are used in combination; 2-mercaptobenzothiazole is a general-purpose accelerator, widely used as an ultra-fast vulcanization accelerator for various rubbers, natural rubber and general synthetic rubbers.

[0046] Tetra methyl thiuram disulfide - belongs to the "sulfurless vulcanization" vulcanizing agent and also belongs to the ultra-accelerator. It has a wide vulcanization flatness and can use a relatively high vulcanization temperature. It is an ultra-accelerator for natural, synthetic rubbers and latex, and can be used as a vulcanizing agent. And N-cyclohexyl-2-benzothiazole sulfenamide - is an excellent post-effect accelerator, suitable for natural rubber, synthetic rubber and rubber products such as tires.

[0047] The anti-aging agent is antioxidant 4010NA or antioxidant AW or p-phenylenediamine antioxidant, and antioxidant RD is used in combination; antioxidant 4010NA has good dispersibility and has no influence on vulcanization. Antioxidant RD is suitable for natural rubber and synthetic rubbers such as nitrile, styrene-butadiene, ethylene-propylene and chloroprene. It has excellent anti-aging protection effects against heat and oxygen.

[0048] The plasticizer is diisononyl phthalate; diisononyl phthalate is applied to various hard and soft plastic products and can be mixed with other plasticizers without affecting its own properties. The rubber reinforcing agent is carbon black, and it can also be used for coloring foamed materials:

[0049] The flame retardant is decabromodiphenylethane, and antimony trioxide is used in combination; the foaming agent is N,N'-dinitrosopentamethylenetetramine, and a foaming aid is used in combination. The foaming aid is urea resin BK; foaming agent H is widely used in rubber foaming. In addition, foaming agent H is also widely used in plasticized PVC calendering and blow molding foaming. And urea resin BK is suitable for PVC / NBR, various rubbers and rubber-like foamed vulcanized products. It has excellent vulcanization acceleration effects, can reduce the dosage of vulcanization accelerators, can absorb ammonia and formaldehyde, and can obtain a uniform cell structure at the same time.

[0050] The main component of the heat stabilizer is calcium zinc epoxy fatty acid stabilizer, and a quantitative auxiliary heat stabilizer is added thereto. The specific ratio is:

[0051]

[0052] When preparing the heat stabilizer, first add epoxy plasticizer, amino crotonate, α-phenylindole to the calcium zinc epoxy fatty acid main stabilizer at the same time, then add organic phosphite auxiliary antioxidant and β-diketone auxiliary stabilizer in turn, and finally add polyol catalyst, zeolite and hydrotalcite at the same time.

[0053] The polyol catalyst is pentaerythritol or polyvinyl alcohol or sorbitol or mannitol; the epoxy plasticizer is epoxy soybean oil or epoxy linseed oil or epoxy stearate; the organic phosphite auxiliary antioxidant is phenyl diisooctyl phosphite or octyl phosphite or diphenyl decyl phosphite; the β-diketone auxiliary stabilizer is isovaleryl benzoyl methane or β-diketone T-247 or pyrrolidine-2,4-dione.

[0054] The steps for preparing the heat stabilizer include:

[0055] S1: Weigh the above materials according to the ratio, put a quantitative amount of epoxy fatty acid calcium zinc stabilizer main agent into the reaction vessel, heat up to 80 °C, and simultaneously add amino crotonate and α-phenyl indole therein, and stir and react for 10 min;

[0056] S2: Add the organic phosphite auxiliary antioxidant to the stirred solution, heat up to 90 °C and stir for 5 min, add the β-diketone auxiliary stabilizer, stir and react for 25 min;

[0057] S3: Heat the reacted solution to 100 °C - 105 °C for dehydration, after completion, cool down to 85 °C, and finally add the polyol catalyst, zeolite and hydrotalcite, stir until the reaction ends, then the heat stabilizer is obtained.

[0058] Using this heat stabilizer can cut off the growth of conjugated chains in PVC during the production of NBR / PVC foamed materials, form cyclic compounds, reduce zinc burning generated during the processing of PVC materials, and improve the thermal stability and mechanical properties of NBR / PVC foamed materials;

[0059] Greatly improve the thermal stability effect of the calcium zinc stabilizer and enhance the stability of PVC materials during the processing; it can also significantly improve the transparency and color purity of NBR / PVC foamed materials, improve the discoloration of PVC products during storage, and improve the weather resistance of the products.

[0060] The present invention also provides a modified NBR / PVC foamed material and its preparation method, including the following steps:

[0061] S1, PVC pre-swelling, take a quantitative amount of PVC particles, heat to 80 °C, then add the plasticizer and heat stabilizer and stir evenly to form a paste, and let it stand for 2 h at 80 °C;

[0062] S2, PVC plasticization, place the pre-swollen PVC material in an internal mixer for plasticization. Wait until the PVC turns into a continuous transparent state, and keep the room temperature of the internal mixer; take a quantitative amount of NBR, conduct three-stage plastic refining treatment on it. When plasticizing, the temperature in the internal mixer is 150 °C, the plasticizing time is 3 - 5 min, and the rotation speed is 57 - 63 r / min;

[0063] S3. NBR / PVC blending: Put the NBR material after three-stage plasticizing into a Banbury mixer, add calcium carbonate, accelerator, antioxidant, flame retardant and rubber reinforcing agent, mix for 6 - 9 minutes until evenly mixed, then discharge and take out. Control the temperature during discharging at 147 - 153 °C, pass through the calender 3 - 5 times to make the NBR / PVC masterbatch. Add blowing agent and vulcanizing agent to the NBR / PVC masterbatch on the low-temperature open mill roller for mixing. After completion, let it stand at room temperature for 24 hours and then cut into sheets.

[0064] S4. Foaming: Place the obtained NBR / PVC masterbatch sheet on a flat vulcanizing machine for mold pressing and foaming. The foaming temperature is 172 °C - 176 °C, the foaming pressure is 14 - 16 Mpa, foam for 10 minutes to obtain the finished product, and then cool and package.

[0065] Determine the best ratio of each component:

[0066] The content of PVC has a relatively significant impact on the performance of the foaming material. As the content of PVC increases, the density and hardness of the foam first decrease and then increase. As Figure 1 shown, when the PVC amount is 28 phr, the density and hardness of the foam are the smallest, its tensile strength and elongation at break reach the peak, and the comprehensive performance is good. Therefore, when PVC is 28 phr, the blending effect with NBR is the best.

[0067] The accelerator plays a crucial role in the vulcanization speed and foaming speed of the foam. The best dosage of the accelerator is 1.3 phr. As shown in Table 1, the best dosage of the vulcanizing agent is 1.2 phr.

[0068] Table 1 Influence of vulcanizing agent with different weight components on the density of mold-pressed foam

[0069] Experiment Serial Number Weight Component of Vulcanizing Agent / phr <![CDATA[Molding and foaming density at 170 °C (g·cm -3 )]]> 1 0.6 0.074 2 0.8 0.095 3 1.0 0.091 4 1.2 0.104 5 1.4 0.063

[0070] NBR has high hardness, large intermolecular force and poor processing performance. In order to weaken its intermolecular force and endow it with softness and elasticity, a plasticizer must be added. As shown in Table 2, the best component ratio of the plasticizer is 30 phr. When the DOP dosage is 30 phr, the foam cells are the most dense and the formed open-cell structure is the least.

[0071] Table 2 Influence of plasticizer content on the foaming material

[0072]

[0073] The dosage of the blowing agent has a great impact on the formation of the foam. As the dosage of the blowing agent increases, the density of the mold-pressed foam shows a decreasing trend, and the density is the smallest when the addition amount is 8 phr. And when the dosages of blowing agent H and urea resin BK are the same, the open-cell rate of the foaming material is the best.

[0074] Table 3 Influence of Heat Stabilizer Dosage on the Properties of NBR / PVC Masterbatch

[0075] Performance / phr of Heat Stabilizer 0.70 0.85 1.00 1.15 Hardness (Shore A) 60 65 72 68 Tensile Strength / MPa 16 24 31 27 Elongation at Break % 415 610 685 592 50% Modulus / MPa 1.04 1.23 1.28 1.21 100% Modulus / MPa 1.55 1.83 2.03 1.96 <![CDATA[Tear strength / (kN·m -1 )]]> 72 103 125 117 Compression Set at 100°C for 24 h by 25% 21 25 32 27 Impact Elasticity 41 30 22 18 Abrasion 0.22 0.16 0.10 0.11

[0076] The influence of heat stabilizer dosage on the properties of NBR / PVC foamed materials is shown in Table 3. The above property reference standards include GB / T 23651-2009 Introduction and Guide for Hardness Testing of Vulcanized Rubber or Thermoplastic Rubber, GB / T 528-2009 Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber, GB / T 1685-2008 Determination of Compression Stress Relaxation of Vulcanized Rubber or Thermoplastic Rubber at Normal and High Temperatures, etc.

[0077] In summary, when the heat stabilizer is 1.0 phr, the hardness, tensile strength, modulus at a specified elongation, elongation at break, and tear strength of the NBR / PVC masterbatch are all the best, which improves the mechanical strength but reduces the impact elasticity to a certain extent.

[0078] In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A modified NBR / PVC foamed material, comprising, characterized in that: It includes the following proportion components: Among them, the main component of the heat stabilizer is calcium zinc stabilizer of epoxy fatty acid, and a quantitative auxiliary heat stabilizer is added thereto. The specific ratio is as follows: When preparing the heat stabilizer, first add epoxy plasticizer, amino crotonate, and α-phenyl indole into the main agent of calcium zinc stabilizer of epoxy fatty acid at the same time, then successively add organic phosphite auxiliary antioxidant and β-diketone auxiliary stabilizer, and finally add polyol catalyst, zeolite and hydrotalcite at the same time; The polyol catalyst is pentaerythritol or polyvinyl alcohol or sorbitol or mannitol; the epoxy plasticizer is epoxy soybean oil or epoxy linseed oil or epoxy stearate; The organic phosphite auxiliary antioxidant is phenyl diisooctyl phosphite or octyl phosphite or diphenyl decyl phosphite; the β-diketone auxiliary stabilizer is isovaleryl benzoyl methane or β-diketone T-247 or pyrrolidine-2,4-dione.

2. The modified NBR / PVC foamed material according to claim 1, wherein: The vulcanizing agent is zinc stearate and sulfur; the accelerator is 2-mercaptobenzothiazole or zinc diethyldithiocarbamate, and tetramethylthiuram disulfide and N-cyclohexyl-2-benzothiazole sulfenamide are added for combined use.

3. A modified NBR / PVC foamed material according to claim 1, characterized in that: The antioxidant is antioxidant 4010NA or antioxidant AW or p-phenylenediamine antioxidant, and antioxidant RD is added for combined use; the plasticizer is diisononyl phthalate; the rubber reinforcing agent is carbon black.

4. A modified NBR / PVC foamed material according to claim 1, characterized in that: The flame retardant is decabromodiphenylethane, and antimony trioxide is added for combined use; the foaming agent is N,N'-dinitrosopentamethylenetetramine, and a foaming aid is added for combined use. The foaming aid is urea resin BK.

5. A preparation method of a modified NBR / PVC foaming material according to any one of claims 1 to 4, characterized in that, It includes the following steps: S1. PVC pre-swelling: Take a quantitative amount of PVC particles, heat them to 80°C, then add a plasticizer and a heat stabilizer and stir evenly to form a paste, and let it stand for 2 h at 80°C; S2. PVC plasticization: Place the pre-swollen PVC material in an internal mixer for plasticization. Wait until the PVC turns into a continuous transparent state, and keep the room temperature of the internal mixer; Take a quantitative amount of NBR and conduct three-stage plastic refining treatment on it; S3. NBR / PVC blending: Put the three-stage plastic refined NBR material into an internal mixer, add calcium carbonate, accelerator, antioxidant, flame retardant and rubber reinforcing agent, knead for 6-9 min until evenly mixed, then discharge and take out, thin pass 3-5 times to make NBR / PVC masterbatch. Add a foaming agent and a vulcanizing agent to the NBR / PVC masterbatch on the roll of a low-temperature open mill for kneading. After completion, let it stand at room temperature for 24 h and then cut into sheets; S4. Foaming: Place the obtained NBR / PVC masterbatch sheet on a flat vulcanizer for mold pressing and foaming. The foaming temperature is 172°C - 176°C, and foam for 10 min to obtain the finished product, and then cool and package.

6. The preparation method of a modified NBR / PVC foamed material according to claim 5, characterized in that: In S2, the temperature in the internal mixer during plasticization is 150°C, the plasticization time is 3-5 min, and the rotation speed is 57-63 r / min.

7. The preparation method of a modified NBR / PVC foaming material according to claim 5, characterized in that: In S3, the temperature during discharging is controlled at 147-153°C, and the foaming pressure in S4 is 14-16 MPa.

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