A low temperature resistant EPDM rubber composite material and preparation method thereof

Abstract

The present application relates to the technical field of rubber composite materials, and specifically to a low-temperature resistant EPDM rubber composite material and a preparation method thereof. The composite material significantly improves the low-temperature resistance and resilience of the material by introducing modified nano-silica-loaded polybutadiene and / or polyisobutylene soft segments and liquid EPDM rubber into the EPDM rubber matrix. The mass ratio of the EPDM rubber matrix, the modified nano-silica-loaded soft segment monomer and the liquid EPDM rubber in the composite material is 1:(0.1-0.5):(0.5-1). Compared with the prior art, the rubber composite material of the present application significantly improves the low-temperature compliance and elasticity while maintaining the original excellent oxidation resistance, ozone resistance, heat resistance and chemical resistance of the EPDM rubber, greatly improving the performance in cold environments, and is suitable for various low-temperature environments. The fields of sealing, shock absorption and protection.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber composite materials, and in particular to a low-temperature resistant EPDM rubber composite material and a preparation method thereof. The composite material significantly improves the low-temperature resistance and resilience of the material by introducing polybutadiene and / or polyisobutylene soft segments loaded with modified nano-silica, and is suitable for various fields such as sealing, shock absorption and protection in low-temperature environments. Background Art

[0002] As the market share and popularity of electric vehicles increase, the proportion of electric vehicles used in extremely cold regions increases. Therefore, the low-temperature resistance requirements for the thermal management system seals of electric vehicles increase. It is necessary to ensure that the seals can maintain rubber elasticity and ensure stable sealing performance under extremely cold weather conditions.

[0003] Ethylene propylene diene monomer (EPDM) is a terpolymer made of ethylene, propylene and an unsaturated third monomer (non-conjugated diene). It belongs to saturated carbon chain rubber and has excellent aging resistance, chemical resistance, and excellent electrical insulation properties. It is widely used in the automotive industry, wires and cables, sealing materials, and heat-resistant products. Although the EPDM we use at present is amorphous, it still has a certain degree of crystallization when the ethylene content is high, which makes the product have poor elasticity at low temperatures and poor flexural properties under high deformation, limiting its application in certain fields. In order to improve the low-temperature resistance of EPDM rubber, people have tried a variety of methods, such as adding plasticizers and changing the cross-linking density, but these methods often affect the mechanical properties and durability of the material. Chinese patent CN110527200B provides a low-temperature resistant high-rebound rubber windshield material, which improves the low-temperature performance and flexural resistance of EPDM by introducing maleic anhydride modified polybutadiene, but the simple mixing method brings limited improvement in low-temperature resistance. It is still necessary to develop rubber composite materials with better low-temperature resistance to meet the needs of the development of electric vehicles. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies mentioned in the above background technology and provide a low-temperature resistant EPDM rubber composite material and a preparation method thereof, by introducing a modified nano-silica-loaded soft segment monomer and liquid EPDM rubber into an EPDM rubber matrix, determining the most suitable ratio of the three, so that the composite material can still maintain excellent flexibility and resilience in a low-temperature environment.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A low-temperature resistant EPDM rubber composite material comprises the following components: an EPDM rubber matrix, a soft segment monomer loaded with modified nano-silica and liquid EPDM rubber, wherein the modified nano-silica loaded soft segment monomer is prepared by a specific method and uniformly dispersed in the EPDM rubber matrix, thereby improving the low-temperature resistance and resilience of the material.

[0007] More specifically, the soft segment monomer is selected from polybutadiene and / or polyisobutylene.

[0008] More specifically, the preparation method of the modified nano-silica loaded soft segment monomer includes: dissolving polybutadiene and / or polyisobutylene soft segment in an organic solvent, adding modified nano-silica, uniformly dispersing the modified nano-silica in the polybutadiene and / or polyisobutylene solution under ultrasonic or stirring conditions, and then obtaining the polybutadiene and / or polyisobutylene soft segment loaded by the modified nano-silica by evaporating the solvent or by precipitation method; wherein the mass ratio of the polybutadiene and / or polyisobutylene soft segment to the modified nano-silica is 5:1 to 20:1, the organic solvent is toluene, xylene or tetrahydrofuran, and the ultrasonic or stirring time is 1 to 4 hours; the main component of the modified nano-silica is kaolin-type silica, and contains 1%-5% of sepiolite, the average particle size of the modified nano-silica is less than 100nm, and the specific surface area is greater than 200㎡ / g.

[0009] The mass ratio of the EPDM rubber matrix, the soft segment monomer loaded with modified nano-silica and the liquid EPDM rubber in the composite material satisfies 1:(0.1-0.5):(0.5-1).

[0010] More specifically, the composite material includes 50-100 parts of EPDM rubber, 5-50 parts of soft segment monomer loaded with modified nano-silica, 25-100 parts of liquid EPDM rubber, and further includes 20-40 parts of carbon black, 2-3 parts of coupling agent, 0.8-1.2 parts of active magnesium oxide, 0.8-1.2 parts of stearic acid, 4-6 parts of antioxidant, 6-8 parts of accelerator, 0.5-1.5 parts of plasticizer, 1.5-2.5 parts of cross-linking agent and 1-2 parts of sulfur.

[0011] More specifically, the vinyl content of the EPDM rubber is 55.0%-65.0%.

[0012] More specifically, the Mooney viscosity of the liquid EPDM rubber is lower than 10MU under the condition of ML (1+4) 100°C.

[0013] More specifically, the carbon black includes one or more of BC1031 carbon black, spray carbon black, and highly dispersed white carbon black.

[0014] The present invention also provides a method for preparing the above-mentioned low-temperature resistant EPDM rubber composite material, comprising the following steps: mixing the EPDM rubber matrix, the soft segment loaded with modified nano-silica and the liquid EPDM rubber according to a predetermined ratio, and mixing them in a high-speed mixer or an internal mixer to uniformly disperse the components; plasticizing and calendering the mixed materials to obtain a composite material sheet; and vulcanizing the composite material sheet to obtain the final low-temperature resistant EPDM rubber composite material.

[0015] More specifically, before the vulcanization treatment, a preheating step is also included, the preheating temperature is 100°C to 140°C, and the preheating time is 5 to 10 minutes. After the vulcanization treatment step, post-treatment steps such as cooling, trimming and inspection are also included to ensure the final quality and performance of the composite material.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] By introducing polybutadiene and / or polyisobutylene soft segments loaded with modified nano-silica, the low-temperature resistance and resilience of the composite material are significantly improved; the introduction of butadiene monomers into the rubber molecular chain can improve the low-temperature performance of the rubber itself, and at the same time can destroy the crystallization phenomenon of the vinyl group and the propylene group in the EPDM rubber, thereby improving the low-temperature compliance and elasticity of the EPDM rubber molecular chain; the use of modified nano-silica for loading can double the performance improvement effect.

[0018] The synergistic effect of the modified nano-silica loaded soft segment and the liquid EPDM rubber enables the composite material to maintain excellent flexibility and resilience in low temperature environments, which is significantly better than the low-temperature performance of rubber simply mixed with a single soft segment.

[0019] Adding sepiolite to modify nano-silica can not only greatly improve the loading capacity of nano-silica, thereby significantly improving the low-temperature resistance of the composite material, but also the strong rheological properties and ion exchange activity of sepiolite make the composite rubber have strong chemical reactivity, which can further react with fillers such as highly dispersed silica and silane coupling agents, so that the entire rubber forms a complete cross-linked network, improving the interaction between the rubber and silica and coupling agents, thereby improving the mechanical properties of the composite material. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described in detail below through embodiments.

[0021] Preparation Example

[0022] 100g of polybutadiene soft segment is dissolved in 500mL of toluene, and 10g of modified nano-silica is added. The modified nano-silica is kaolin-type silica and contains 1%-5% of sepiolite. The modified nano-silica is evenly dispersed in the polybutadiene solution under ultrasonic conditions for 2 hours. The average particle size of the modified nano-silica is less than 100nm and the specific surface area is greater than 200㎡ / g. Then, the polybutadiene soft segment loaded with the modified nano-silica is obtained by evaporating the solvent.

[0023] Example 1

[0024] This embodiment prepares a low-temperature resistant EPDM rubber composite material, and the specific steps are as follows:

[0025] Preheating: Preheat the high-low dual-speed mixer to 70-80°C, the open mill to 90-100°C, and the heating and pressure mixer to 100-125°C; at room temperature, premix 4 parts of silane coupling agent directly with 60 parts of highly dispersed silica to ensure that the coupling agent is evenly distributed on the surface of silica.

[0026] Preparation of masterbatch: 50 parts of EPDM matrix, 15 parts of modified nano-silica loaded polybutadiene and 35 parts of liquid EPDM are mixed at a mixing temperature of 60°C for 20 minutes. The mixed materials are plasticized at a plasticizing temperature of 100°C for 10 minutes; then the pre-mixed high-dispersion white carbon black and coupling agent mixture is added, and the temperature is kept at no more than 130°C; 8 parts of accelerator, 1.8 parts of active magnesium oxide, 2 parts of stearic acid, 2.5 parts of plasticizer, 10 parts of antioxidant and 3 parts of cross-linking agent are added, and the mixture is mixed at a low speed for 2 minutes to ensure full dispersion without destroying the structure of the material.

[0027] Vulcanization molding: transfer the mixed masterbatch to an open mixer cooled to room temperature, add 6 parts of pre-mixed accelerator and 3 parts of pre-dispersed sulfur; mix at a low speed to ensure uniform distribution, no more than 5 minutes, and avoid over-processing; finally, the mixed rubber is formed into a preform of the desired shape through an extruder or molding, and finally the composite material sheet is vulcanized at a vulcanization temperature of 175°C and a vulcanization time of 8 minutes to obtain the final low-temperature resistant EPDM rubber composite material.

[0028] Example 2

[0029] The difference between this embodiment and embodiment 1 is that in the preparation of the masterbatch, 50 parts of EPDM rubber matrix, 25 parts of modified nano-silica-loaded polybutadiene and 50 parts of liquid EPDM rubber are mixed, and the other components are adjusted in proportion. The other steps are the same as in embodiment 1.

[0030] Example 3

[0031] The difference between this embodiment and embodiment 1 is that in the preparation of the masterbatch, 50 parts of EPDM rubber matrix, 5 parts of modified nano-silica-loaded polybutadiene and 25 parts of liquid EPDM rubber are mixed, and the other components are adjusted in proportion. The other steps are the same as in embodiment 1.

[0032] Comparative Example 1

[0033] The difference between this comparative example and Example 1 is that the soft segment monomer loaded with modified nano-silica and the liquid EPDM rubber are not added, and only the EPDM rubber matrix is ​​mixed with other components to prepare the composite material. The other steps are the same as those in Example 1.

[0034] Comparative Example 2

[0035] The difference between this comparative example and Example 1 is that no modified nano-silica is added, and the EPDM rubber matrix is ​​directly mixed with polybutadiene and liquid EPDM rubber to prepare the composite material. The other steps are the same as those in Example 1.

[0036] Comparative Example 3

[0037] The difference between this comparative example and Example 1 is that no modified nano-silica-loaded soft segment monomer is added, and only the EPDM rubber matrix and the liquid EPDM rubber are mixed to prepare the composite material. The other steps are the same as those in Example 1.

[0038] Performance Testing

[0039] The composite materials prepared in Examples 1-3 and Comparative Examples 1-3 were tested for performance, and the test results are shown in the following table:

[0040]

[0041] It can be seen from the above table that the composite materials prepared in Examples 1-3 have From the above test data, it can be seen that the products prepared in the examples not only meet the industry standards, but the samples also perform well in mechanical property tests such as tensile strength, exceeding existing material standards.

[0042] In addition, low temperature tests were also carried out on the samples. The specific test standards and results are as follows:

[0043] Test item: Low temperature shrinkage

[0044] Sample Description: Rubber Sheet

[0045] Test method: GB / T 7758-2020

[0046] Test conditions:

[0047] Specimen: Dumbbell type

[0048] Sample thickness: 2.09mm

[0049] Pretreatment conditions: -70°C, 10 min

[0050] Heating rate: 1°C / min

[0051] Gauge length: 50mm

[0052] Elongation: 50%

[0053] Laboratory environment conditions: 23±2°C, 50±5%RH

[0054] The test results are shown in the following table:

[0055]

[0056] The data show that in a low temperature environment, the samples maintain high elasticity and flexibility, showing excellent low temperature resistance, while the composite materials prepared in Comparative Examples 1-3 show poor low temperature resistance.

[0057] The low-temperature resistant EPDM rubber composite material and the preparation method thereof provided by the present invention significantly improve the low-temperature resistance and resilience of the composite material by introducing a polybutadiene and / or polyisobutylene soft segment loaded with modified nano-silica. The composite materials prepared in Examples 1-3 can still maintain excellent flexibility and resilience in a low-temperature environment, and are suitable for various fields such as sealing, shock absorption and protection in low-temperature environments. The results of Comparative Examples 1-3 further demonstrate the important role of the polybutadiene and / or polyisobutylene soft segment loaded with modified nano-silica in improving the low-temperature resistance of the composite material.

[0058] The present invention provides a low-temperature resistant EPDM rubber composite material and a preparation method thereof, wherein the preparation method of modified nano-silica-loaded polybutadiene soft segment, as well as specific parameters such as the weight fraction of each key component, the parameters of the nano-materials and the preparation method are particularly emphasized. By accurately controlling these parameters, the present invention can prepare an EPDM rubber composite material with excellent low-temperature resistance and resilience. The above specific embodiments are only exemplary embodiments of the present invention and are not intended to limit the scope of protection thereof. Any modification, replacement or equivalent transformation based on the spirit and principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A low temperature resistant EPDM rubber composite material, characterized in that: The composite material comprises the following components: an EPDM rubber matrix, a soft segment monomer loaded with modified nano-silica and liquid EPDM rubber, wherein the soft segment monomer loaded with modified nano-silica is prepared by a specific method and uniformly dispersed in the EPDM rubber matrix to improve the low temperature resistance and resilience of the material, and the soft segment monomer is selected from polybutadiene and / or polyisobutylene; wherein the mass ratio of the EPDM rubber matrix, the soft segment monomer loaded with modified nano-silica and the liquid EPDM rubber is 1:(0.1-0.5):(0.5-1); The method for preparing a soft segment monomer loaded with modified nano-silica comprises: dissolving a polybutadiene and / or polyisobutylene soft segment in an organic solvent, adding modified nano-silica, uniformly dispersing the modified nano-silica in the polybutadiene and / or polyisobutylene solution under ultrasonic or stirring conditions, and then obtaining the polybutadiene and / or polyisobutylene soft segment loaded with modified nano-silica by evaporating the solvent or by a precipitation method; wherein the mass ratio of the polybutadiene and / or polyisobutylene soft segment to the modified nano-silica is 5:1 to 20:1, the organic solvent is selected from toluene, xylene or tetrahydrofuran, and the ultrasonic or stirring time is 1 to 4 hours; the main component of the modified nano-silica is kaolin-type silica, and contains 1%-5% of sepiolite, the average particle size of the modified nano-silica is less than 100nm, and the specific surface area is greater than 200㎡ / g.

2. The low temperature resistant EPDM rubber composite material according to claim 1, characterized in that: The EPDM rubber composite material includes 50-100 parts of EPDM rubber, 5-50 parts of modified nano-silica-loaded soft segment monomers, 25-100 parts of liquid EPDM rubber, 40-90 parts of carbon black, 4-8 parts of coupling agents, 1.6-2.4 parts of active magnesium oxide, 1.6-2.4 parts of stearic acid, 8-12 parts of antioxidants, 12-18 parts of accelerators, 1.5-3.5 parts of plasticizers, 3-5 parts of cross-linking aids and 2-4 parts of sulfur.

3. The low temperature resistant EPDM rubber composite material according to claim 2, characterized in that: The vinyl content of the EPDM rubber is 55.0%-65.0%.

4. The low temperature resistant EPDM rubber composite material according to claim 2, characterized in that: The Mooney viscosity of the liquid EPDM rubber is lower than 10MU under the condition of ML (1+4) 100°C.

5. The low temperature resistant EPDM rubber composite material according to claim 2, characterized in that: The carbon black includes one or more of BC1031 carbon black, spray carbon black, and highly dispersed white carbon black.

6. A method for preparing the low temperature resistant EPDM rubber composite material as claimed in claim 2, characterized in that: The following steps are involved: S1: preparing modified nano-silica supported polybutadiene and / or polyisobutylene soft segments; S2: Mixing the EPDM rubber matrix, the modified nano-silica-loaded soft segment monomer and the liquid EPDM rubber in a predetermined ratio, and sequentially adding carbon black, coupling agent, active magnesium oxide, stearic acid, antioxidant, accelerator, plasticizer, co-crosslinking agent and sulfur, and mixing in a high-speed mixer or internal mixer to uniformly disperse the components; S3: plasticizing and calendering the mixed materials to obtain a composite material sheet; S4: vulcanizing the composite material sheet at a vulcanization temperature of 150° C. to 180° C. for a vulcanization time of 8 to 30 minutes to obtain a final low-temperature resistant EPDM rubber composite material.

7. The preparation method according to claim 6, characterized in that: Before the vulcanization treatment, a preheating step is also included, with the preheating temperature being 100°C to 140°C and the preheating time being 5 to 10 minutes.

8. The preparation method according to any one of claims 6 to 7, characterized in that: After the vulcanization step, post-processing steps are also included, including cooling, trimming and inspection to ensure the final quality and performance of the composite material.

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