Ozone-resistant nitrile butadiene rubber composite sealant and its preparation method

Abstract

This invention discloses an ozone-resistant nitrile rubber composite sealant and its preparation method, comprising a modified nitrile rubber base layer and a fluororubber composite layer. The modified nitrile rubber base layer and the fluororubber composite layer are bonded together using a low-temperature synchronous vulcanization process with a specially formulated fluororubber composite layer graft compatibilizer. The invention also includes a preparation method comprising the following steps: S1, weighing and preparing the modified nitrile rubber base layer according to its mass proportions; S2, directionally dispersing the composite reinforcing filler and composite ozone protectant through directional shear mixing to obtain the modified nitrile rubber raw material; S3, bonding the modified nitrile rubber raw material and the fluororubber composite layer together using a specially formulated fluororubber composite layer graft compatibilizer through a low-temperature co-vulcanization process to obtain the nitrile rubber sealant. This invention solves the problems of poor ozone resistance in existing nitrile rubber sealants, weak interlayer bonding in traditional composite nitrile rubber sealants, and the difficulty in simultaneously achieving ozone resistance and oil resistance elasticity.

Description

Technical Field

[0001] This invention relates to the field of nitrile rubber technology, specifically to an ozone-resistant nitrile rubber composite sealing material and its preparation method. Background Technology

[0002] Nitrile rubber, with its excellent oil resistance and high elasticity, is widely used in the production of sealing products in automotive parts, construction machinery, and oil pipelines. However, the molecular chains of conventional nitrile rubber are easily damaged by ozone oxidation. Long-term use in outdoor and high-ozone conditions can easily lead to surface cracking and elasticity deterioration, resulting in seal failure.

[0003] Currently, most existing solutions for improving the ozone resistance of nitrile butadiene rubber (NBR) employ physical bonding between NBR and fluororubber, relying solely on interfacial adhesion to achieve a two-layer bond. This results in low bond strength, making the composite layer prone to delamination and detachment under equipment vibration or prolonged oil immersion, leading to poor sealing reliability. While perfluororubber seals offer excellent ozone resistance, their high raw material costs, insufficient rubber elasticity, and suboptimal sealing performance make it difficult to balance performance and production costs. Furthermore, traditional composite seals often employ a step-by-step vulcanization and bonding process, which is cumbersome, inefficient, and fails to achieve a balance between ozone resistance, interlayer bond strength, and product manufacturing costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an ozone-resistant nitrile rubber composite sealant and its preparation method, which solves the problems of poor ozone resistance of existing nitrile rubber sealants, weak interlayer bonding of traditional composite nitrile rubber sealants, and the difficulty in simultaneously achieving ozone resistance and oil resistance elasticity.

[0005] To achieve the above objectives, the present invention provides an ozone-resistant nitrile rubber composite sealing material, characterized in that it comprises a modified nitrile rubber base layer and a fluororubber composite layer. The modified nitrile rubber base layer is formulated by weight ratio as follows: 100 parts nitrile rubber, 1-2 parts stearic acid, 5-8 parts zinc oxide, 30-40 parts carbon black N550, 20-30 parts silica, 2-3 parts microcrystalline wax, 1.5-2 parts antioxidant 4010NA, 1-1.5 parts antioxidant NBC, 8-15 parts plasticizer DOP, 1-2 parts accelerator DM, 1.5-2.5 parts accelerator CZ, 0.5-1 part vulcanizing agent sulfur, and 3-5 parts of a special graft compatibilizer for the fluororubber composite layer. The modified nitrile rubber base layer and the fluororubber composite layer are bonded together by a low-temperature synchronous vulcanization process using the special graft compatibilizer for the fluororubber composite layer to form the nitrile rubber sealing material.

[0006] The present invention further comprises: the carbon black N550 and silica are combined to form a composite reinforcing filler, the total amount of the composite reinforcing filler is 60-95 parts by mass, the microcrystalline wax, antioxidant 4010NA and antioxidant NBC are compounded to form a composite ozone protectant, and the modified nitrile rubber base layer is processed by a directional shear mixing process to directionally disperse the composite reinforcing filler and the composite ozone protectant.

[0007] The present invention further specifies that the acrylonitrile content of the nitrile rubber is 35%-41%.

[0008] The present invention further includes a preparation method comprising the following steps: S1. Weigh and prepare according to the mass fraction of the modified nitrile rubber base layer; S2. Modified nitrile butadiene raw material is prepared by directional shear mixing to directionally disperse the composite reinforcing filler and composite ozone protectant. S3. Modified nitrile rubber raw material and fluororubber composite layer are bonded together by low-temperature co-vulcanization process using a compounded fluororubber composite layer special graft compatibilizer to achieve synchronous vulcanization and composite of modified nitrile rubber layer and fluororubber composite layer, thus obtaining nitrile rubber sealing material.

[0009] The advantages of adopting the above technical solution are as follows: The technology uses nitrile rubber with an acrylonitrile content of 35%~41% as the matrix material, compounded with a high-efficiency ozone protectant, silica / carbon black composite reinforcing filler, plasticizer, and crosslinking agent. Through ratio optimization, the ozone aging resistance of the matrix rubber itself is improved, while retaining the excellent oil resistance and high elasticity of nitrile rubber, thus inhibiting ozone cracking at the matrix material level. Furthermore, the directional shear mixing process during compounding ensures that the reinforcing filler and ozone protectant are directionally dispersed in the rubber compound along the direction of sealing stress, improving the material's tear resistance and ozone aging resistance, and avoiding performance degradation caused by filler agglomeration. The modified nitrile rubber base layer and the fluororubber composite layer are bonded together using a low-temperature synchronous vulcanization process with a special graft compatibilizer for fluororubber composite layers. This achieves simultaneous vulcanization and molding of the nitrile rubber modified layer and the fluororubber composite layer. Compared with the traditional secondary bonding process, this significantly improves the bonding strength between the composite layers and avoids problems such as interface delamination and peeling during use. The ozone-resistant nitrile rubber composite sealing material prepared by the above technology is highly practical and can be directly used to prepare various sealing components such as sealing rings, oil seals, dust seals, and gaskets. It is suitable for working conditions with ozone exposure and oil resistance sealing requirements, such as engineering machinery, automotive engines, hydraulic and pneumatic systems, and petrochemical pipelines, and has a wide range of applications. Meanwhile, the economic benefits are significant. On the one hand, the modified composite formula improves performance while controlling raw material costs, and the one-step co-vulcanization process simplifies the production process, reduces labor and equipment costs, and improves production efficiency. On the other hand, the material's excellent ozone resistance, oil resistance, and high elasticity can significantly extend the service life of sealing components and reduce replacement and maintenance costs for end users. At the same time, this material is significantly more competitive than traditional nitrile rubber sealing materials and has a greater cost advantage than pure fluororubber materials. It has broad market application prospects and can bring significant economic benefits and market share increases to manufacturing enterprises. Attached Figure Description

[0010] Figure 1 This is a simplified flowchart of the present invention. Detailed Implementation

[0011] This invention provides an ozone-resistant nitrile rubber composite sealing material, characterized in that it comprises a modified nitrile rubber base layer and a fluororubber composite layer. The modified nitrile rubber base layer is formulated in the following proportions by weight: 100 parts nitrile rubber, 1-2 parts stearic acid, 5-8 parts zinc oxide, 30-40 parts carbon black N550, 20-30 parts silica, 2-3 parts microcrystalline wax, 1.5-2 parts antioxidant 4010NA, 1-1.5 parts antioxidant NBC, 8-15 parts plasticizer DOP, 1-2 parts accelerator DM, 1.5-2.5 parts accelerator CZ, 0.5-1 part vulcanizing agent sulfur, and a special graft phase for the fluororubber composite layer. The modified nitrile rubber base layer and the fluororubber composite layer are bonded together by a low-temperature synchronous vulcanization process using a special graft compatibilizer for fluororubber composite layers to form a nitrile rubber sealing material. The carbon black N550 and silica are combined to form a composite reinforcing filler, and the total amount of the composite reinforcing filler is 60-95 parts by weight. The microcrystalline wax, antioxidant 4010NA, and antioxidant NBC are compounded to form a composite ozone protectant. The modified nitrile rubber base layer is processed by a directional shear mixing process to directionally disperse the composite reinforcing filler and the composite ozone protectant. The acrylonitrile content of the nitrile rubber is 35%-41%.

[0012] Furthermore, it also includes a method for preparing an ozone-resistant nitrile rubber composite sealant, comprising the following steps: S1. Weigh and prepare according to the mass fraction of the modified nitrile rubber base layer; S2. Modified nitrile butadiene raw material is prepared by directional shear mixing to directionally disperse the composite reinforcing filler and composite ozone protectant. S3. Modified nitrile rubber raw material and fluororubber composite layer are bonded together by low-temperature co-vulcanization process using a compounded fluororubber composite layer special graft compatibilizer to achieve synchronous vulcanization and composite of modified nitrile rubber layer and fluororubber composite layer, thus obtaining nitrile rubber sealing material.

[0013] The ozone-resistant nitrile rubber composite sealant prepared based on the above embodiments exhibits significantly improved ozone resistance, exceeding that of traditional nitrile rubber sealants by more than three times. It can withstand long-term use in environments with high ozone concentrations of 100 pphm and maintains good elasticity and sealing performance over a wide temperature range of -40℃ to 100℃. Furthermore, the interlayer bonding strength is increased by more than 50%. Compared to pure fluororubber sealants, its raw material cost is reduced by more than 40%.

[0014] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. An ozone-resistant nitrile rubber composite sealing material, characterized in that: The material comprises a modified nitrile rubber base layer and a fluororubber composite layer. The modified nitrile rubber base layer is formulated by weight ratio as follows: 100 parts nitrile rubber, 1-2 parts stearic acid, 5-8 parts zinc oxide, 30-40 parts carbon black N550, 20-30 parts silica, 2-3 parts microcrystalline wax, 1.5-2 parts antioxidant 4010NA, 1-1.5 parts antioxidant NBC, 8-15 parts plasticizer DOP, 1-2 parts accelerator DM, 1.5-2.5 parts accelerator CZ, 0.5-1 part vulcanizing agent sulfur, and 3-5 parts of a special graft compatibilizer for the fluororubber composite layer. The modified nitrile rubber base layer and the fluororubber composite layer are bonded together by a low-temperature synchronous vulcanization process using the special graft compatibilizer for the fluororubber composite layer to form a nitrile rubber sealing material.

2. The ozone resistant nitrile rubber composite sealing material according to claim 1, characterized in that: The carbon black N550 and silica are combined to form a composite reinforcing filler, and the total amount of the composite reinforcing filler is 60-95 parts by mass. The microcrystalline wax, antioxidant 4010NA, and antioxidant NBC are compounded to form a composite ozone protectant. The modified nitrile rubber base layer is processed by a directional shear mixing process to directionally disperse the composite reinforcing filler and the composite ozone protectant.

3. The ozone resistant nitrile rubber composite sealing material according to claim 1, characterized in that: The acrylonitrile content of the nitrile rubber is 35%-41%.

4. The process for preparing ozone resistant nitrile rubber composite seal material according to any one of claims 1 to 3, characterized in that: Includes the following steps: S1. Weigh and prepare according to the mass fraction of the modified nitrile rubber base layer; S2. Modified nitrile butadiene raw material is prepared by directional shear mixing to directionally disperse the composite reinforcing filler and composite ozone protectant. S3. Modified nitrile rubber raw material and fluororubber composite layer are bonded together by low-temperature co-vulcanization process using a compounded fluororubber composite layer special graft compatibilizer to achieve synchronous vulcanization and composite of modified nitrile rubber layer and fluororubber composite layer, thus obtaining nitrile rubber sealing material.

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