Method for reducing reduction of adhesive force between tire framework material and rubber

Abstract

The invention relates to the technical field of curing bladders, and discloses a method for reducing the reduction of adhesive force between a tire framework material and rubber, which comprises the following steps of: adopting a curing bladder with a low heat conductivity coefficient when a tire blank is cured, and controlling the heat conductivity coefficient of the bladder to be less than 0.2 W / (m.K), the mixing raw materials comprise epoxidized butyl rubber, a plasticizer, a reinforcing agent, zinc oxide, stearic acid, an anti-aging agent and a vulcanizing agent, and the reinforcing agent is not a heat-conducting filler; the epoxidation degree of the epoxidized butyl rubber is 5%-10%, and the maleic anhydride modification degree of the epoxidized butyl rubber is 0.5%-3%. By reducing the heat transfer speed during high-temperature vulcanization, the heat transfer of the capsule is slower and more uniform, local overheating in the rubber is prevented, thermal degradation of the rubber and a framework material in the tire is effectively prevented, and the adhesive force between the framework material and the rubber of the tire is prevented from being reduced; particularly, the adhesive force between the cord fabric layer and the belted layer and the rubber is reduced, so that the overall performance of the tire is ensured. And meanwhile, the ring-epoxidized butyl rubber adopted by the invention can ensure that the capsule has excellent mechanical properties and high temperature resistance.

Description

Technical Field

[0001] The invention relates to the technical field of vulcanization bladders, in particular to a method for reducing the decrease in adhesion between tire skeleton materials and rubber. Background Art

[0002] Curing bladder is a hollow thin-walled rubber product of tire vulcanizer. It is used to load the inner cavity of the tire to be vulcanized, and then pass a heating medium (such as steam, nitrogen, air or hot water) to pressurize and heat the tire, and cooperate with the vulcanizer to perform shaping and vulcanization operations. The type of curing bladder varies depending on the structure of the vulcanizer. The bladders used in various shaping vulcanizers are mainly divided into three types: type A, type B and type AB. Among them, type A bladders are divided into barrel-shaped bladders for bias tires and orange-shaped rubber vulcanization bladders for radial tires. Compared with traditional water tires, it has the advantages of simple operation, high degree of automation, fast heat transfer, and short vulcanization time. Especially for the vulcanization of large-scale engineering machinery tires, it can simplify equipment and operation.

[0003] Existing curing bladders usually use high thermal conductivity materials to accelerate heat transfer, shorten curing time and improve production efficiency. However, when the curing steam temperature is too high, the high thermal conductivity of the bladder will aggravate the thermal degradation of the rubber material, resulting in a decrease in the adhesion between the tire skeleton material (such as polyester cord, steel cord) and the rubber, and ultimately affecting the overall performance of the tire. Especially under high curing pressure conditions, in order to obtain better tire mechanical properties, a higher curing steam temperature is often required, which further increases the risk of thermal degradation of rubber and skeleton materials. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a vulcanization bladder with a low thermal conductivity coefficient and an application thereof, wherein the bladder can avoid the problems of tire rubber decomposition and decreased adhesion caused by high temperature, while maintaining the necessary mechanical properties of the tire, thereby extending the tire service life and improving the tire performance.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A method for reducing the decrease in adhesion between a tire skeleton material and rubber, the method comprising: using a low thermal conductivity vulcanizing bladder during tire green body vulcanization, wherein the thermal conductivity of the bladder is controlled to be less than 0.2 W / (m·K), and the mixing raw materials thereof comprise epoxidized butyl rubber, a plasticizer, a reinforcing agent, zinc oxide, stearic acid, an antioxidant and a vulcanizing agent, wherein the reinforcing agent is not a thermally conductive filler; the epoxidized degree of the epoxidized butyl rubber is 5%-10%, and the degree of modification by maleic anhydride is 0.5%-3%.

[0006] Preferably, the capsule is prepared by mixing the raw materials comprising the following components by mass percentage: Epoxidized butyl rubber: 50%-80%; Plasticizer: 10%-20%; Reinforcing agent: 10%-20%; Zinc oxide: 1%-4%; Stearic acid: 0-2%; Anti-aging agent: 1%-2%; Vulcanizing agent: 1%-3%.

[0007] Preferably, the capsule is prepared by mixing the raw materials comprising the following components by mass percentage: Epoxidized butyl rubber: 55%-65%; Plasticizer: 14%-16%; Reinforcement agent: 17%-19%; Zinc oxide: 2%-3%; Stearic acid: 0.5%-1.5%; Anti-aging agent: 1%-2%; Vulcanizing agent: 1.5%-2.5%.

[0008] Preferably, the reinforcing agent includes but is not limited to one or more of calcium carbonate, white carbon black, and clay.

[0009] Preferably, the epoxidized butyl rubber is obtained by first epoxidizing butyl rubber and then modifying it with maleic anhydride.

[0010] Preferably, during the vulcanization of the green tire, the vulcanization steam temperature is 200° C.-230° C., and the total vulcanization time is 7-9 minutes.

[0011] The present invention adopts a vulcanization bladder with a low thermal conductivity coefficient to reduce the speed of heat transfer during high-temperature vulcanization, so that the heat transfer is slower and more uniform, and local overheating inside the rubber is prevented, and the thermal degradation of the rubber inside the tire is effectively prevented, and the adhesion between the skeleton material of the tire and the rubber is avoided to decrease, especially the adhesion between the cord layer and the belt layer material and the rubber is decreased, so as to ensure the overall performance of the tire. At the same time, the present invention adopts epoxidized butyl rubber with an epoxidation degree of 5%-10% and a maleic anhydride modification degree of 0.5%-3%, so as to ensure that the bladder has excellent mechanical properties and high temperature resistance. DETAILED DESCRIPTION

[0012] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] The specific steps for preparing epoxidized butyl rubber are as follows: (1) Synthesis of butyl rubber Raw material ratio: isobutylene: 99.5%; isoprene: 0.5%. Catalyst dosage: aluminum chloride 0.05%-0.1% (mass percentage). Polymerization temperature: -90℃, controlled at low temperature (-80℃ to -100℃) to increase molecular weight and chain regularity. Polymerization time: 0.5 to 1 hour. Terminator: After the reaction is completed, add 0.5%-1% mass percentage of water or ethanol as a terminator to end the polymerization reaction.

[0014] (2) Epoxidation of butyl rubber Solvent: dichloromethane, dissolve butyl rubber in a ratio of 1:5 (butyl rubber: solvent). Epoxidant dosage: epichlorohydrin is added in an amount of 3%-5% of the mass of butyl rubber. Reaction temperature: 60℃ to 80℃. Reaction time: 2 to 3 hours, monitor the reaction until the degree of epoxidation reaches 5%-10%.

[0015] (3) Addition of maleic anhydride Maleic anhydride dosage: 0.5%-3% of the mass of epoxidized butyl rubber. Reaction temperature: controlled at 150°C. Reaction time: 1 to 2 hours to ensure that maleic anhydride fully reacts with the epoxy group to form a stable covalent bond.

[0016] (4) Performance evaluation Testing and Characterization: The final product is tested for mechanical properties, thermal stability, and other performance indicators to ensure that the material meets the intended application requirements.

[0017] Example 1 Provided is a vulcanization bladder with a low thermal conductivity of 0.2 W / (m•K), which is prepared by mixing raw materials comprising the following components by mass percentage: Epoxidized butyl rubber: 60%; Plasticizer: 15%; Reinforcing agent (calcium carbonate): 18%; Zinc oxide: 2.5%; Stearic acid: 1%; Anti-aging agent: 1.5%; Vulcanizing agent: 2%.

[0018] Among them, the epoxidation degree of the epoxidized butyl rubber is 7%, and the degree of modification by maleic anhydride is 2%.

[0019] Application conditions: Heat the vulcanization mold to 160℃, introduce 210℃ steam, use the low thermal conductivity vulcanization bladder to conduct heat, and control the vulcanization time to 7-9 minutes.

[0020] Example 2 Provided is a vulcanized bladder with a low thermal conductivity, which is prepared by mixing raw materials comprising the following components by mass percentage: Epoxidized butyl rubber: 50%; Plasticizer: 20%; Reinforcing agent (calcium carbonate): 20%; Zinc oxide: 4%; Stearic acid: 2%; Anti-aging agent: 2%; Vulcanizing agent: 2%.

[0021] Among them, the epoxidation degree of the epoxidized butyl rubber is 7%, and the degree of modification by maleic anhydride is 2%.

[0022] Application conditions: Heat the vulcanization mold to 160℃, introduce 210℃ steam, use the low thermal conductivity vulcanization bladder to conduct heat, and control the vulcanization time to 7-9 minutes.

[0023] Example 3 Provided is a vulcanized bladder with a low thermal conductivity, which is prepared by mixing raw materials comprising the following components by mass percentage: Epoxidized butyl rubber: 70%; Plasticizer: 10%; Reinforcing agent (calcium carbonate): 15%; Zinc oxide: 1.5%; Stearic acid: 1%; Anti-aging agent: 1%; Vulcanizing agent: 1.5%.

[0024] Among them, the epoxidation degree of the epoxidized butyl rubber is 7%, and the degree of modification by maleic anhydride is 2%.

[0025] Application conditions: Heat the vulcanization mold to 160℃, introduce 210℃ steam, use the low thermal conductivity vulcanization bladder to conduct heat, and control the vulcanization time to 7-9 minutes.

[0026] Comparative Example 1 The difference from Example 1 is that the epoxidized butyl rubber has an epoxidation degree of 2.0%, a maleic anhydride modification degree of 5.0%, and is synthesized in the laboratory. The thermal conductivity of the obtained curing bladder is 0.30 W / (m•K).

[0027] Application conditions: Heat the vulcanization mold to 160℃, introduce 210℃ steam, use the common thermal conductivity vulcanization capsule for vulcanization, and control the vulcanization time within 6-7 minutes.

[0028] Comparative Example 2 The difference from Example 1 is that the epoxidized butyl rubber is replaced by butyl rubber, the brand is Butyl 268, purchased from Exxon. The thermal conductivity of the obtained curing bladder is 0.35 W / (m·K).

[0029] Application conditions: Heat the vulcanization mold to 160℃, introduce 210℃ steam, use the common thermal conductivity vulcanization capsule for vulcanization, and control the vulcanization time within 5-6 minutes.

[0030] Comparative Example 3 Provided is a common thermal conductivity vulcanized capsule with a thermal conductivity of 0.3W / (m•K). The capsule is prepared by mixing the following raw materials in terms of mass percentage: Butyl rubber: 50%; Thermal conductive filler (acetylene black): 15%; Reinforcing agent: 20%; Vulcanizing agent: 2%; Plasticizer: 13%.

[0031] Application conditions: Heat the vulcanization mold to 160℃, introduce 210℃ steam, use the common thermal conductivity vulcanization capsule for vulcanization, and control the vulcanization time within 6-7 minutes.

[0032] Comparative Example 4 Provided is a high thermal conductivity vulcanized capsule with a thermal conductivity of 0.4W / (m•K). The capsule is prepared by mixing the following raw materials in terms of mass percentage: Butyl rubber: 40%; High thermal conductivity filler (graphene): 20%; Reinforcement agent: 30%; Plasticizer: 8%; Vulcanizing agent: 2%.

[0033] Application conditions: Preheat the vulcanization mold to 160℃, pass 210℃ steam, use the high thermal conductivity vulcanization capsule for vulcanization, and control the vulcanization time to 5-6 minutes.

[0034] Source of raw materials: Anti-aging agent: 4020, a product of Shandong Shengao; Vulcanizing agent: Sulfur powder, a product of Shandong Shangshun Company.

[0035] The vulcanized tires of the embodiment and the comparative example were subjected to performance tests, and the results are shown in Table 1.

[0036] Table 1 parameter Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Adhesion between skeleton material and rubber (N / cm) 28 27 30 20 22 23 20 Curing time (minutes) 7.5 7.5 8.0 6.5 5.5 6.5 5.5 Tensile strength(MPa) 19 18 20 16 15 18 16 Tear strength (kN / m) 110 100 95 95 90 100 95 elasticity(%) 75 70 65 70 70 70 65 Product qualification rate (%) 98 96 98 92 90 95 90 It can be seen from Table 1 that Example 1 can effectively avoid the thermal degradation of the rubber inside the tire during high-temperature vulcanization due to its unique low thermal conductivity, and maintain the good mechanical properties of the tire, especially under high-temperature steam conditions, it can ensure the adhesion between the frame material and the rubber. Although Comparative Examples 1 and 2 shorten the vulcanization time, due to the high thermal conductivity, the thermal degradation of the rubber inside the tire and the decrease in the adhesion between the frame material and the rubber, the tensile strength, tear strength, elasticity and product qualification rate of the tire are all reduced, which is not conducive to the service life of the tire. The adhesion between the tire frame material and the rubber obtained in Comparative Examples 3 and 4 is also lower than that of the embodiment.

[0037] The above is a description of the embodiments of the present invention. Through the above description of the disclosed embodiments, professionals and technicians in the field can implement or use the present invention. Various modifications to these embodiments will be apparent to professionals and technicians in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will conform to the widest range consistent with the principles and novelties disclosed herein.

Claims

1. A method for reducing the decrease in adhesion between tire frame material and rubber, characterized in that: The method comprises the following steps: using a low thermal conductivity vulcanizing bladder during tire vulcanization; the thermal conductivity of the bladder is controlled to be less than 0.2 W / (m·K); the mixing raw materials thereof comprise epoxidized butyl rubber, a plasticizer, a reinforcing agent, zinc oxide, stearic acid, an antioxidant and a vulcanizing agent; the reinforcing agent is not a thermally conductive filler; the epoxidized degree of the epoxidized butyl rubber is 5%-10%; and the degree of modification by maleic anhydride is 0.5%-3%.

2. The method according to claim 1, characterized in that The capsule is prepared by mixing the raw materials of the following components by mass percentage: Epoxidized butyl rubber: 50%-80%; Plasticizer: 10%-20%; Reinforcing agent: 10%-20%; Zinc oxide: 1%-4%; Stearic acid: 0-2%; Anti-aging agent: 1%-2%; Vulcanizing agent: 1%-3%.

3. The method according to claim 2, characterized in that The capsule is prepared by mixing the raw materials of the following components by mass percentage: Epoxidized butyl rubber: 55%-65%; Plasticizer: 14%-16%; Reinforcement agent: 17%-19%; Zinc oxide: 2%-3%; Stearic acid: 0.5%-1.5%; Anti-aging agent: 1%-2%; Vulcanizing agent: 1.5%-2.5%.

4. The method according to claim 1, characterized in that: The epoxidized butyl rubber is obtained by first epoxidizing butyl rubber and then modifying it with maleic anhydride.

5. The method according to claim 1, characterized in that The reinforcing agent includes but is not limited to one or more of calcium carbonate, white carbon black, and clay.

6. The method according to claim 1, characterized in that During the vulcanization of the tire green body, the vulcanization steam temperature is 200°C-230°C and the total vulcanization time is 7-9 minutes.