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CN-122011608-A - Rubber composition for high-heat-resistance long-service-life vulcanized capsule and preparation method thereof

CN122011608ACN 122011608 ACN122011608 ACN 122011608ACN-122011608-A

Abstract

The invention provides a rubber composition for a high heat-resistant long-life vulcanized capsule and a preparation method thereof. The rubber composition for the high heat-resistant long-life vulcanized capsule comprises, by weight, 90-100 parts of butyl rubber, 3-10 parts of low-unsaturation butyl rubber, 40-70 parts of reinforcing filler, 3-10 parts of phenolic resin vulcanizing agent, 2-8 parts of active agent and 1-10 parts of functionalized liquid butyl rubber. The invention uses the functionalized liquid butyl rubber with active functional groups to replace the traditional castor oil to prepare the rubber composition for curing the capsule, and the prepared rubber composition has excellent heat resistance and longer flex life.

Inventors

  • MA MIN
  • JIANG WEI
  • ZHOU WENXIANG
  • Qian Sicong

Assignees

  • 浙江信汇新材料股份有限公司

Dates

Publication Date
20260512
Application Date
20251225

Claims (10)

  1. 1. The rubber composition for the high heat-resistant long-life vulcanized capsule is characterized by comprising the following components in parts by weight: 90-100 parts of butyl rubber; 3-10 parts of low-unsaturation butyl rubber; 40-70 parts of reinforcing filler; 3-10 parts of phenolic resin vulcanizing agent; 2-8 parts of active agent, and 1-10 Parts of functionalized liquid butyl rubber.
  2. 2. The rubber composition for a high heat-resistant long-life vulcanized capsule of claim 1, wherein the functionalized liquid butyl rubber is a liquid butyl rubber grafted with phenolic hydroxyl groups, maleic anhydride or benzyl halide functional groups on molecular chains, the functional group content of the functionalized liquid butyl rubber is 0.05-0.5mol/100g, and the number average molecular weight Mn of the functionalized liquid butyl rubber is 8000-15000.
  3. 3. The rubber composition for high heat-resistant long-life vulcanized capsules according to claim 2, wherein the functionalized liquid butyl rubber is prepared by a solution grafting method comprising the following steps: Dissolving basic liquid butyl rubber in a nonpolar solvent to form a glue solution; adding a grafting monomer and an initiator into the glue solution under the protection of nitrogen, and performing grafting reaction at the temperature of 80-120 ℃; after the grafting reaction is finished, unreacted monomers and solvent are removed through precipitation, washing and drying, so that the functionalized liquid butyl rubber is obtained; Wherein the grafting monomer is selected from one of maleic anhydride, p-hydroxystyrene or p-chloromethylstyrene.
  4. 4. The rubber composition for a high heat-resistant long-life vulcanized capsule of claim 3, wherein the initiator is dibenzoyl peroxide or azobisisobutyronitrile, the addition amount of the initiator is 0.5-2.0% of the mass of the basic liquid butyl rubber, and the gel content of the functionalized liquid butyl rubber prepared by the solution grafting method is lower than 0.1%.
  5. 5. The rubber composition for a high heat-resistant long-life vulcanized capsule of claim 1, wherein the active agent comprises zinc oxide and magnesium oxide, the mass ratio of the magnesium oxide to the zinc oxide is 1:2-4, and the magnesium oxide can form ionic bonding with functional groups on a molecular chain of the functionalized liquid butyl rubber.
  6. 6. A rubber composition for a high heat resistant long life vulcanized capsule according to claim 1, wherein said reinforcing filler comprises carbon black.
  7. 7. A process for producing a rubber composition for a high heat-resistant long-life vulcanized capsule as defined in any one of claims 1 to 6, characterized by comprising the steps of: S1, one-stage mixing, namely adding 90-100 parts of butyl rubber, 3-10 parts of low-unsaturation butyl rubber, 40-70 parts of reinforcing filler and 2-8 parts of active agent in an internal mixer in parts by weight, and mixing: S2, two-stage mixing, namely adding 3-10 parts by weight of phenolic resin vulcanizing agent and 1-10 parts by weight of functional liquid butyl rubber, mixing and discharging rubber; S3, filtering the rubber and open mill, namely filtering the rubber after rubber discharge by a rubber filter, and then carrying out thin pass and triangular bag opening on the open mill to obtain a lower piece; S4, vulcanization molding.
  8. 8. The method for producing a rubber composition for a high heat-resistant long-life vulcanized rubber capsule according to claim 7, further comprising the step of pre-kneading said functionalized liquid butyl rubber with a part of a phenolic resin vulcanizing agent for 3 to 8 minutes at 130 to 150℃before said step S1 to produce a pre-crosslinked plasticizing masterbatch, wherein said pre-crosslinked plasticizing masterbatch is used in place of the functionalized liquid butyl rubber directly added in said step S2.
  9. 9. The method for producing a rubber composition for a high heat-resistant long-life vulcanized capsule according to claim 7, wherein in said step S3, said filtration is performed through a 150-200 mesh sieve at 90-110 ℃.
  10. 10. The method of claim 7, wherein in the step S4, the vulcanization molding conditions are a vulcanization temperature of 170-190 ℃, a vulcanization time t90+10 minutes, and a vulcanization pressure of not less than 15MPa.

Description

Rubber composition for high-heat-resistance long-service-life vulcanized capsule and preparation method thereof Technical Field The invention relates to a high-performance rubber material for a tire vulcanization process, in particular to a rubber composition for a high-heat-resistance long-service-life vulcanization capsule and a preparation method thereof, and belongs to the technical field of rubber production. Background In the manufacture of pneumatic tires, vulcanization is a critical process step that determines the final properties of the tire. The curing bladder acts as a core component on the curing press and operates at high temperature, high pressure and under severe conditions of repeated expansion and contraction. The inner core of the mold is used for supporting the green tire from the inside, so that the green tire is clung to the patterns of the outer mold, and the vulcanization shaping of the tire is completed under the action of a heat medium. Therefore, the cured capsules must possess excellent thermal aging resistance, flex fatigue resistance, low permanent set, and good thermal conductivity. Currently, the dominant cured capsule substrate in the industry is butyl rubber (IIR), particularly resin cured butyl rubber systems. However, in order to ensure the flexibility of the capsules during repeated expansion and contraction and to reduce the mooney viscosity of the compound to facilitate processing, softeners (plasticizers) have to be added to the conventional capsule formulation. For a long time, castor oil has become a standard softener in the industry because of its wide source and certain plasticizing effect on butyl rubber. Castor oil, however, is a physical plasticizer and is subject to migration and extraction. The castor oil molecules are not connected with the butyl rubber matrix by chemical bonds, and are physically mixed only by intermolecular forces. At working temperatures of up to 170-190 ℃ for curing the capsules, small molecular castor oil migrates very easily from the rubber network to the capsule surface with hundreds of high-rate stretch retraction cycles. The capsule body is gradually hardened to lose elasticity, cracks appear prematurely, the service life of the capsule is shortened, and the migrating castor oil can pollute the inner wall of the tire or form carbon deposition on the surface of the capsule, so that the dynamic balance performance and the appearance quality of the tire are affected. Secondly, castor oil has better heat resistance than other vegetable oils, but still can undergo oxidation, decomposition or polymerization reaction under the long-term high-temperature aerobic environment. The decomposition products are often acidic, and can accelerate the degradation of a main chain of butyl rubber, so that capsules are soft and sticky, the demolding difficulty is increased, and even the capsules are adhered to the inside of a tire, so that serious production accidents are caused. Furthermore, in conventional butyl rubber capsule formulations, a large amount of carbon black is typically filled in order to enhance heat conduction and reinforcement. Castor oil is not perfect as a polar molecule, and compatibility with non-polar butyl rubber and carbon black surfaces. In the kneading process, if the dispersion is uneven, stress concentration points are likely to be formed in a microscopic scale. These microscopic defects rapidly propagate into macrocracks under repeated flexing, causing abrupt rupture of the capsule. Attempts have also been made in the prior art to use paraffinic or aromatic oils instead of castor oil, but these mineral oils have a poorer compatibility with the resin vulcanization system and interfere with the crosslinking reaction of the resin on the butyl rubber, resulting in a slower vulcanization rate and a lower crosslink density. There have also been attempts to use low molecular weight polyisobutenes as plasticizers which, although solving the compatibility problem, still fall under the physical filling, owing to the lack of reactive functional groups, and do not solve the migration and contribution problems to the modulus at high temperatures. Disclosure of Invention Based on the background, the invention aims to provide a rubber composition for a high heat-resistant long-life vulcanized capsule and a preparation method thereof, which solve the technical problems of easy migration and extraction, poor heat aging resistance, short service life, easy pollution to tires and the like caused by using physical plasticizers such as castor oil and the like in vulcanized capsules in the prior art. In order to achieve the above object, the present invention provides the following technical solutions: a rubber composition for a high heat-resistant long-life vulcanized capsule comprises the following components in parts by weight: 90-100 parts of butyl rubber; 3-10 parts of low-unsaturation butyl rubber; 40-70 parts of reinforcing filler; 3-10