An ultrahigh molecular weight polyethylene-nitrile rubber composite elastomeric material and a method of making the same

Abstract

The application discloses an ultrahigh molecular weight polyethylene-acrylonitrile butadiene rubber composite elastic material, which comprises 70wt%-95wt% of ultrahigh molecular weight polyethylene and 5wt%-30wt% of acrylonitrile butadiene rubber powder, has an island-sea structure, wherein the acrylonitrile butadiene rubber powder is a dispersed phase, the ultrahigh molecular weight polyethylene is a continuous phase, and the dispersed phase and the continuous phase are connected by C-C chemical bonds; and the particle size of the acrylonitrile butadiene rubber powder is less than or equal to 0.7mm. By limiting the content of the ultrahigh molecular weight polyethylene and the acrylonitrile butadiene rubber powder, combining the connection between the two phases by C-C chemical bonds and limiting the particle size of the acrylonitrile butadiene rubber powder, the rubber particles in the composite elastic material are first deformed when the composite elastic material is subjected to external force, so that the composite elastic material has good resilience and lower permanent deformation at a smaller strain.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material and its preparation method. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMW-PE) has excellent strength and modulus compared to other engineering plastics, but its elasticity is relatively poor. Nitrile rubber (NBR) has excellent oil resistance, high abrasion resistance, good heat resistance, and strong adhesion, but its disadvantages are lower strength and modulus.

[0003] To address the issues of low strength and modulus of traditional nitrile rubber (NBR) and poor elasticity of ultra-high molecular weight polyethylene (UHMWPE), current technologies mostly involve combining UHMWPE with NBR and other additives to create composite materials. However, direct blending of NBR and UHMWPE presents two problems: first, polar NBR and non-polar UHMWPE have poor compatibility, resulting in suboptimal performance; second, current techniques involve mixing block-shaped NBR and UHMWPE in an internal mixer, but the high melting point of UHMWPE, making it difficult to melt, hinders this mixing process and compromises the uniformity of the mixture. Therefore, existing UHMWPE / NBR composites fail to leverage the respective advantages of both materials, resulting in poor overall performance.

[0004] For example, Chinese patent document CN113321858A discloses a high-strength, high-wear-resistant rubber composite material, its preparation method, and its application in tunnel boring machine seals. By weight, the raw material components for preparing this rubber composite material include 100 parts of nitrile rubber, 6-12 parts of ultra-high molecular weight polyethylene, 3-15 parts of molybdenite, 0.4-2 parts of coupling agent, 50-120 parts of carbon black, 1-5 parts of nano-zinc oxide, 2-5 parts of antioxidant, 0.5-2 parts of accelerator, 1-5 parts of softener, 0.5-2 parts of vulcanizing agent, and 0.1-1 parts of scorching inhibitor. This rubber composite material exhibits high strength and high wear resistance.

[0005] Chinese patent document CN106947135A discloses a polyethylene bearing with high load-bearing capacity, belonging to the technical field of mechanical parts. It is composed of ultra-high molecular weight polyethylene (UHMWPE), nitrile rubber, a self-lubricant, zinc oxide, stearic acid, a crosslinking agent, an antioxidant, EVA-modified resin, di-2-octyl phthalate, zinc oxide, a foaming agent, lead stearate, carbon fiber, and nano-graphite powder. This design maintains the advantages of UHMWPE's self-lubrication and wear resistance while further improving its wear resistance by introducing a self-lubricant. The introduction of a rubber component improves its water-lubricated friction performance while also enhancing the material's flexibility, impact resistance, and vibration damping. Furthermore, friction coefficient testing results show that the water-lubricated friction coefficient of this UHMWPE composite material is significantly lower than that of UHMWPE itself, making it suitable for use as a water-lubricated bearing material.

[0006] Chinese patent document CN104292590A discloses a halogen-free, non-toxic, and environmentally friendly nozzle, which is composed of the following raw materials in parts by weight: 90-100 parts ultra-high molecular weight polyethylene, 1-2 parts diphenyl azidophosphate, 2-3 parts cyclohexanehexyl alcohol, 0.8-1 parts dimethylformamide, 3-5 parts bone char, 0.4-1 parts decabromodiphenyl ethane, 0.1-0.2 parts vinyl acetate, 1-2 parts sodium oleate, 10-12 parts attapulgite, 2-3 parts zinc borate hydrate, 2-3 parts calcium aluminate, 1-2 parts 2-bromo-4-methylphenol, 1-2 parts methylcellulose, and 5-7 parts high-resistance additives. The high-resistance additives added in this invention include: esterified butyral, which has excellent softness and flexibility; emulsified adhesive, which promotes compatibility between materials and improves melt flowability; and methyl methacrylate-butadiene-styrene terpolymer, after softening, blended and modified with esterified butyral and emulsified adhesive, which greatly improves the surface resistance of the finished product.

[0007] Chinese patent document CN1305955C discloses a butadiene rubber-low-density polyethylene crosslinker, characterized in that it is composed of the following components: 50-80 parts by mass of butadiene rubber, 20-50 parts by mass of low-density polyethylene, 0-10 parts by mass of inorganic rigid particles, and 0.1-1 parts by mass of peroxide initiator; the raw butadiene rubber has a Mooney viscosity (ML(1+4)) of 38-45 at 100°C; the low-density polyethylene is a long-branched polyethylene produced by high-pressure gas phase method, with a density between 0.919 and 0.923 g / cm³ and a melt index (MI) between 1.8 and 3.2 g / 10 min.

[0008] Chinese patent document CN100509946C discloses a composition comprising an elastomer and high molecular weight polyethylene with an irregular granular shape, a method for preparing the composition, and its uses. The composition comprises at least one elastomer matrix and at least one other phase comprising high and / or ultra-high molecular weight polyethylene particles with an irregular shape, wherein the high and / or ultra-high molecular weight polyethylene particles with an irregular shape have a porous structure and a bulk density of less than 0.35 g / cm³. 3 The elastomer matrix can be selected from nitrile rubber or nitrile rubber containing carboxyl groups, etc. Summary of the Invention

[0009] In view of the problems existing in the prior art and the directions for improvement, the present invention provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material to solve the problems of low strength and modulus of traditional nitrile rubber, extremely poor elasticity of ultra-high molecular weight polyethylene, and poor overall performance of existing composite materials made of ultra-high molecular weight polyethylene and nitrile rubber.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] An ultra-high molecular weight polyethylene-nitrile rubber composite elastic material comprises 70wt%-95wt% ultra-high molecular weight polyethylene and 5wt%-30wt% nitrile rubber powder; and has an island structure.

[0012] The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase. The dispersed phase and the continuous phase are connected by C-C chemical bonds. The particle size of the nitrile rubber powder is ≤0.7mm.

[0013] The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by this invention has a much higher modulus than nitrile rubber. Therefore, by limiting the content of ultra-high molecular weight polyethylene and nitrile rubber powder, the rubber particles in the final composite elastic material deform first when subjected to external force, so that the composite elastic material has good resilience at a small strain, that is, it has low permanent deformation.

[0014] Optionally, in the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention, the ultra-high molecular weight polyethylene has a number average molecular weight of 1.5 million to 10 million and is in powder form.

[0015] Optionally, the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention further includes sulfur, accelerator, zinc oxide and stearic acid; wherein the amount of sulfur, accelerator, zinc oxide and stearic acid is not specifically limited and can be adjusted according to actual needs. For example, based on 100 parts by weight of nitrile rubber powder, 0.3-2 parts by weight of sulfur, 0.3-2.5 parts by weight of accelerator, 1-4 parts by weight of zinc oxide and 0.5-2 parts by weight of stearic acid can be added.

[0016] The present invention also provides a method for preparing the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material, comprising the following steps:

[0017] After mixing ultra-high molecular weight polyethylene, nitrile rubber powder and crosslinking agent evenly, the mixture is pressed and molded, and then crosslinked and cooled to obtain the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material.

[0018] The temperature of the compression molding step is greater than the softening temperature of the ultra-high molecular weight polyethylene and less than the decomposition temperature of the crosslinking agent.

[0019] The crosslinking temperature is higher than the decomposition temperature of the crosslinking agent, and neither the nitrile rubber powder nor the ultra-high molecular weight polyethylene degrades.

[0020] During the compression molding process of this preparation method, ultra-high molecular weight polyethylene (UHMWPE) melts or softens, causing it to interlock under surface tension to form a continuous phase. Meanwhile, the nitrile rubber powder remains unmelted, retaining its original phase state and forming a dispersed phase. During the crosslinking process, the decomposition of the crosslinking agent enables the C / C chemical bonds between the nitrile rubber powder and the UHMWPE phase to be linked.

[0021] Optionally, in the preparation method of the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention, the crosslinking step is carried out under normal pressure, that is, after compression molding, the pressure is released to normal pressure, and then crosslinking is carried out.

[0022] Optionally, in the preparation method of the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention, the amount of the crosslinking agent is 0.1wt%-4wt% of the total amount of the ultra-high molecular weight polyethylene and the nitrile rubber powder.

[0023] Optionally, in the preparation method of the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention, the crosslinking agent is a peroxide crosslinking agent, preferably DCP (dicumyl peroxide).

[0024] Optionally, in the preparation method of the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention, the compression molding temperature is 110-140℃. The specific molding pressure depends on the molding equipment, and is generally greater than or equal to 10T; the specific molding time is determined according to the molding pressure and molding temperature, so as to ensure that the mold used for molding is well filled, and is generally 1-60min.

[0025] Optionally, in the preparation method of the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention, the crosslinking temperature is 140-200℃. The specific crosslinking time is determined by the amount of crosslinking agent and the crosslinking temperature, and should be 1-60 min to ensure complete crosslinking.

[0026] Optionally, the preparation method of the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention further includes a step of mixing sulfur, accelerator, zinc oxide, and stearic acid with the ultra-high molecular weight polyethylene, the nitrile rubber powder, and the crosslinking agent. The purpose of adding sulfur, accelerator, zinc oxide, and stearic acid is to improve the degree of crosslinking of the nitrile rubber itself.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention has a dispersed phase particle size determined by the particle size of nitrile rubber powder, which is very easy to control. At the same time, there is a C-C bond connection between the dispersed phase composed of nitrile rubber powder and the continuous phase composed of ultra-high molecular weight polyethylene. Therefore, the composite elastic material has low thermal fluidity and good heat resistance.

[0029] 2. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention has nitrile rubber particles with good elasticity inside, which makes the composite elastic material have better elasticity than polyethylene when subjected to compression, stretching and shearing. It can produce elastic deformation similar to rubber and exhibits low permanent deformation. At the same time, by limiting the content of nitrile rubber powder to no more than 30%, it effectively avoids the formation of a continuous phase in some areas by too much nitrile rubber powder, which would lead to a significant decrease in the strength of the material.

[0030] 3. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention has a dispersed phase and a continuous phase connected by C-C bonds, which gives the two phases a high interfacial strength. This means that when the material is stretched, the ultra-high molecular weight polyethylene phase and the nitrile rubber phase are not prone to phase separation, so the nitrile rubber particles will not become stress concentration points, and the high modulus and high strength characteristics of ultra-high molecular weight polyethylene will not be destroyed.

[0031] 4. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention is characterized by the nitrile rubber in the ultra-high molecular weight polyethylene being cross-linked by the cross-linking agent DCP, which gives it excellent elasticity and the composite elastic material having a high elastic modulus.

[0032] 5. In the preparation method of the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by the present invention, by using nitrile rubber powder with a small particle size, good blending between it and ultra-high molecular weight polyethylene and crosslinking agent DCP can be achieved, resulting in a composite elastic material with good dispersibility, elasticity, and strength. Molding is carried out at a temperature higher than the softening temperature of ultra-high molecular weight polyethylene and lower than the decomposition temperature of the crosslinking agent. Taking the crosslinking agent DCP as an example, since the half-life of DCP at 130℃ is approximately 2.2 hours, molding at a temperature below 130℃ ensures that DCP does not decompose or decomposes in very small amounts during the molding process, preventing crosslinking reactions in the system. This results in good system fluidity, allowing rubber particles to be more uniformly dispersed in the continuous phase of ultra-high molecular weight polyethylene. The prepared composite material exhibits superior strength and elasticity. Furthermore, after molding, the crosslinking reaction is carried out under normal pressure, effectively avoiding excessive stress in the material. After the crosslinking reaction, the stress in the material is essentially eliminated, resulting in high dimensional stability, good toughness, and excellent elongation. Detailed Implementation

[0033] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0034] For any experimental steps or conditions not specified in the examples and comparative examples, the procedures and conditions described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0035] Example 1

[0036] This embodiment provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 80 wt% ultra-high molecular weight polyethylene with a molecular weight of 2 million and 20% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0037] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0038] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 2 million, cryogenically pulverized nitrile rubber with a particle size of 0.6 mm, and DCP peroxide are mixed uniformly by high-speed mixing to obtain a mixture;

[0039] The amount of DCP used is 1 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0040] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 120℃ and 40T pressure for 30 minutes.

[0041] 3) After releasing the pressure, the mixture from step 2) is molded together with the mold. Then, the temperature of the flat vulcanizing machine is increased to 160°C and held for 10 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0042] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0043] Comparative Example 1-1

[0044] This comparative example provides an ultra-high molecular weight polyethylene material, and the specific preparation method is as follows:

[0045] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 2 million and DCP peroxide were mixed uniformly by high-speed mixing to obtain a mixture;

[0046] The amount of DCP used is 1 wt% of the mass of ultra-high molecular weight polyethylene;

[0047] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 120℃ and 40T pressure for 30 minutes.

[0048] 3) After releasing the pressure, take the mixture from step 2) and mold, raise the temperature of the flat vulcanizing machine to 160°C and hold it for 10 minutes.

[0049] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0050] Comparative Examples 1-2

[0051] This comparative example provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 80 wt% ultra-high molecular weight polyethylene with a molecular weight of 2 million and 20% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0052] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0053] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 2 million, cryogenically pulverized nitrile rubber with a particle size of 1 mm, and DCP peroxide are mixed uniformly by high-speed mixing to obtain a mixture;

[0054] The amount of DCP used is 1 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0055] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 120℃ and 40T pressure for 30 minutes.

[0056] 3) After releasing the pressure, the mixture from step 2) is molded together with the mold. Then, the temperature of the flat vulcanizing machine is increased to 160°C and held for 10 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0057] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0058] Comparative Examples 1-3

[0059] This comparative example provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 60 wt% ultra-high molecular weight polyethylene with a molecular weight of 2 million and 40% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0060] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0061] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 2 million, cryogenically pulverized nitrile rubber with a particle size of 1 mm, and DCP peroxide are mixed uniformly by high-speed mixing to obtain a mixture;

[0062] The amount of DCP used is 1 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0063] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 120℃ and 40T pressure for 30 minutes.

[0064] 3) After releasing the pressure, the mixture from step 2) is molded together with the mold. Then, the temperature of the flat vulcanizing machine is increased to 160°C and held for 10 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0065] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0066] Comparative Examples 1-4

[0067] This comparative example provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 80 wt% ultra-high molecular weight polyethylene with a molecular weight of 2 million and 20% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0068] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0069] 1) A mixture is obtained by uniformly mixing ultra-high molecular weight polyethylene with a number average molecular weight of 2 million and cryogenically pulverized nitrile rubber with a particle size of 0.6 mm through high-speed mixing;

[0070] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 120℃ and 40T pressure for 30 minutes.

[0071] 3) After releasing the pressure, take the mixture from step 2) and mold, raise the temperature of the flat vulcanizing machine to 160°C and hold it for 10 minutes.

[0072] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0073] Comparative Examples 1-5

[0074] This comparative example provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 80 wt% ultra-high molecular weight polyethylene with a molecular weight of 2 million and 20% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0075] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0076] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 2 million, cryogenically pulverized nitrile rubber with a particle size of 0.6 mm, and DCP peroxide are mixed uniformly by high-speed mixing to obtain a mixture;

[0077] The amount of DCP used is 1 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0078] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 150°C and 40T pressure for 30 minutes.

[0079] 3) After releasing the pressure, the mixture from step 2) is molded together with the mold. Then, the temperature of the flat vulcanizing machine is increased to 160°C and held for 10 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0080] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0081] Example 2

[0082] This embodiment provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 70 wt% ultra-high molecular weight polyethylene with a molecular weight of 2 million and 30% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0083] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0084] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 2 million, cryogenically pulverized nitrile rubber with a particle size of 0.7 mm, and DCP peroxide are mixed uniformly by high-speed mixing to obtain a mixture;

[0085] The amount of DCP used is 4 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0086] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 110℃ and 30T pressure for 40 minutes.

[0087] 3) After releasing the pressure, the mixture from step 2) is molded together with the mold. Then, the temperature of the flat vulcanizing machine is increased to 140°C and held for 60 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0088] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0089] Example 3

[0090] This embodiment provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 90 wt% ultra-high molecular weight polyethylene with a molecular weight of 3 million and 10% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0091] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0092] 1) A mixture is obtained by uniformly mixing ultra-high molecular weight polyethylene with a number average molecular weight of 3 million, cryogenically pulverized nitrile rubber with a particle size of 0.5 mm, and DCP peroxide through high-speed mixing.

[0093] The amount of DCP used is 0.1 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0094] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 130℃ and 10T pressure for 8 minutes.

[0095] 3) After releasing the pressure, the mixture from step 2) is molded together with the mold. Then, the temperature of the flat vulcanizing machine is increased to 200°C and held for 8 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0096] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0097] Example 4

[0098] This embodiment provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 95 wt% ultra-high molecular weight polyethylene with a molecular weight of 3.5 million and 5% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0099] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0100] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 3.5 million, cryogenically pulverized nitrile rubber with a particle size of 0.4 mm, and DCP peroxide are mixed uniformly by high-speed mixing to obtain a mixture;

[0101] The amount of DCP used is 1.5 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0102] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 135℃ and 50T pressure for 20 minutes.

[0103] 3) After releasing the pressure, the mixture from step 2) is molded together with the mold. Then, the temperature of the flat vulcanizing machine is increased to 180°C and held for 15 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0104] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0105] Example 5

[0106] This embodiment provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material, comprising 3.5 million molecular weight ultra-high molecular weight polyethylene, nitrile rubber powder, zinc oxide, stearic acid, sulfur, and accelerator TBBS; based on the mass of 100% ultra-high molecular weight polyethylene and nitrile rubber powder, it contains 95 wt% ultra-high molecular weight polyethylene with a molecular weight of 3.5 million and 5% nitrile rubber powder; zinc oxide accounts for 3 wt% of the nitrile rubber powder, stearic acid accounts for 1 wt% of the nitrile rubber powder, sulfur accounts for 1.5 wt% of the nitrile rubber powder, and TBBS accounts for 1 wt% of the nitrile rubber powder; wherein, the nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, and the two phases are linked by C-C chemical bonds. This composite elastic material has an island structure.

[0107] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0108] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 3.5 million, cryogenically pulverized nitrile rubber with a particle size of 0.4 mm, DCP peroxide, zinc oxide, stearic acid, sulfur and accelerator TBBS are mixed uniformly by high-speed mixing to obtain a mixture.

[0109] The amount of DCP used is 2.8 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0110] 2) Place the mixture obtained in step 1) into a mold and perform compression molding using a flat vulcanizing machine at 135℃ and 50T pressure for 15 minutes.

[0111] 3) After releasing the pressure, the mixture from step 2) is molded together with the mold. Then, the temperature of the flat vulcanizing machine is increased to 180°C and held for 15 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0112] 4) After cooling the mixture from step 3) together with the mold to room temperature, remove the product.

[0113] Example 6

[0114] This embodiment provides an ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. Based on 100% by mass (DCP content negligible), the composite elastic material contains 80 wt% ultra-high molecular weight polyethylene with a molecular weight of 2 million and 20% nitrile rubber powder. The nitrile rubber powder is the dispersed phase, and the ultra-high molecular weight polyethylene is the continuous phase, with the two phases linked by C-C chemical bonds. This composite elastic material has an island-of-sea structure.

[0115] The preparation method of the above-mentioned ultra-high molecular weight polyethylene-nitrile rubber composite elastic material is as follows:

[0116] 1) Ultra-high molecular weight polyethylene with a number average molecular weight of 2 million, cryogenically pulverized nitrile rubber with a particle size of 0.6 mm, and DCP peroxide are mixed uniformly by high-speed mixing to obtain a mixture;

[0117] The amount of DCP used is 1 wt% of the total mass of powdered nitrile rubber and ultra-high molecular weight polyethylene;

[0118] 2) Place the mixture obtained in step 1) into a mold and mold it using a flat vulcanizing machine at 120℃ and 40T pressure for 50 minutes.

[0119] 3) After pressing the mixture from step 2) together with the mold, without releasing the pressure, directly raise the temperature of the flat vulcanizing machine to 160°C and keep it at that temperature for 10 minutes. This process can achieve the C-C chemical bond linking in the powdered nitrile phase and the ultra-high molecular weight polyethylene phase.

[0120] 4) After cooling the mixture from step 3) along with the mold to room temperature, remove the product. This method does not require releasing the pressure, which effectively shortens the operation time.

[0121] The products obtained in the above embodiments and comparative examples were subjected to the following performance tests, and the specific test results are shown below. The test methods are as follows:

[0122] Tensile strength and yield elongation: GB / T 1040-2018;

[0123] Flexural modulus: GB / T 9341-2008;

[0124] Compression set at constant strain at room temperature: GB / T 1683-2018;

[0125] Resilience: GB / T 1681-1991.

[0126] Table 1

[0127]

[0128] As shown in the table above, the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material provided by this invention has high strength, elongation, and flexural modulus, while also exhibiting low compression set. A comparison between Example 1 and Example 6 shows that while directly raising the temperature after compression molding without releasing the pressure can shorten the preparation time and improve efficiency, the overall effect is correspondingly worse.

[0129] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A composite elastic material of ultra-high molecular weight polyethylene-nitrile rubber, characterized in that, It includes 70wt%-95wt% ultra-high molecular weight polyethylene and 5wt%-30wt% nitrile rubber powder; and has an island structure. Wherein, the nitrile rubber powder is the dispersed phase, the ultra-high molecular weight polyethylene is the continuous phase, and the dispersed phase and the continuous phase are connected by C-C chemical bonds; the particle size of the nitrile rubber powder is ≤0.7mm; The preparation method of the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material includes the following steps: After mixing ultra-high molecular weight polyethylene, nitrile rubber powder and crosslinking agent evenly, the mixture is pressed and molded, and then crosslinked and cooled to obtain the ultra-high molecular weight polyethylene-nitrile rubber composite elastic material. The temperature of the compression molding step is greater than the softening temperature of the ultra-high molecular weight polyethylene and less than the decomposition temperature of the crosslinking agent. The crosslinking temperature is higher than the decomposition temperature of the crosslinking agent, and neither the nitrile rubber powder nor the ultra-high molecular weight polyethylene degrades.

2. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material as described in claim 1, characterized in that, The ultra-high molecular weight polyethylene has a number average molecular weight of 1.5 million to 10 million and is in powder form.

3. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material as described in claim 1, characterized in that, The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material also includes sulfur, accelerator, zinc oxide and stearic acid.

4. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material as described in claim 1, characterized in that, The crosslinking step is carried out under normal pressure.

5. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material as described in claim 1, characterized in that, The amount of the crosslinking agent is 0.1wt%-4wt% of the total amount of the ultra-high molecular weight polyethylene and the nitrile rubber powder.

6. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material as described in claim 1, characterized in that, The crosslinking agent is a peroxide crosslinking agent.

7. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material as described in claim 1, characterized in that, The pressing temperature is 110-140℃.

8. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material as described in claim 1, characterized in that, The crosslinking temperature is 140-200℃.

9. The ultra-high molecular weight polyethylene-nitrile rubber composite elastic material as described in claim 1, characterized in that, It also includes the step of mixing sulfur, accelerator, zinc oxide and stearic acid with the ultra-high molecular weight polyethylene, the nitrile rubber powder and the crosslinking agent.

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