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CN-122011522-A - Flame-retardant sidewall rubber composition, mixing method thereof and tire

CN122011522ACN 122011522 ACN122011522 ACN 122011522ACN-122011522-A

Abstract

The invention relates to the technical field of rubber manufacture, and discloses a flame-retardant sidewall rubber composition, a mixing method thereof and a tire. In a common diene rubber system, the flame retardant performance of the rubber composition can be effectively improved by adding a small amount of zinc salt flame retardant and ceramic microbeads into chlorinated polyethylene, the use of halogen compounds such as bromine, chlorine and the like in hazardous substances with high toxicity is avoided, VOC emission is reduced, meanwhile, the lubricity of natural paraffin and the polarity and elasticity of the chlorinated polyethylene are used as high molecular compatilizer, the dispersibility of the zinc salt flame retardant and the ceramic microbeads in rubber is effectively improved, the process dispersion problem caused by using inorganic flame retardants such as antimony trioxide with high content and the like and the performance degradation problem of the rubber composition are avoided, and therefore the flame retardant rubber composition with low smoke, low toxicity, high efficiency and industrialization can be comprehensively realized.

Inventors

  • Dai Zhongjuan
  • JIANG QI
  • HUANG XIANHONG
  • YANG HUIYING
  • ZHOU XIAOYU
  • Kan Xueqing

Assignees

  • 中策橡胶集团股份有限公司

Dates

Publication Date
20260512
Application Date
20260128

Claims (10)

  1. 1. The flame-retardant sidewall rubber composition is characterized by being prepared by mixing the following raw materials in parts by weight (100 parts by weight) of raw rubber: from 40 to 60phr of natural rubber, 40 To 60phr of butadiene rubber, 10 To 20phr of carbon black, 30 To 40phr of white carbon black, Silane 2.0 to 4.0phr, 20 To 60phr of chlorinated polyethylene CPE, 1.0 To 5.0phr of natural paraffin, Ceramic microbeads 2.0-10phr, Zinc salt flame retardant 5.0-10phr.
  2. 2. The flame retardant sidewall rubber composition according to claim 1, wherein the rubber composition is prepared by mixing the following raw materials in 100 parts by weight of raw rubber: 45-55phr of natural rubber, 45-55Phr of butadiene rubber, 10 To 20phr of carbon black, 30 To 40phr of white carbon black, Silane 2.0 to 4.0phr, 40 To 60phr of chlorinated polyethylene CPE, 1.0 To 5.0phr of natural paraffin, Ceramic microbeads 2.0-10phr, 5.0 To 10phr of zinc salt flame retardant; Further, the rubber composition is prepared by mixing the following raw materials: 10.0 to 13.0phr of softening agent, 1.5 To 2.5phr of protective wax, 2.5 To 6.0phr of anti-aging agent, 4.0 To 6.0phr of activator, 1.0 To 2.0phr of vulcanizing agent, 0.6 To 1.8phr of accelerator.
  3. 3. The flame retardant sidewall rubber composition according to claim 1 or 2, wherein the zinc salt flame retardant is a mixture of diboron trioxide and zinc oxide in a ratio of 2:1-1:1.
  4. 4. The flame retardant sidewall rubber composition according to claim 1 or 2, wherein the ceramic microbeads are silica-alumina ceramic with a D50 of 10um or less.
  5. 5. A flame retardant sidewall rubber composition according to claim 1 or 2, wherein the chlorinated polyethylene CPE has a chlorine content of 25% -45%, more preferably 30% -40%.
  6. 6. The flame retardant sidewall rubber composition of claim 1 or 2, wherein the carbon black is selected from the group consisting of N3 series or N2 series carbon black, preferably N330 or N375 carbon black; And/or the white carbon black is white carbon black 165 or white carbon black 175 or high-dispersion white carbon black; And/or the silane is one or more of Si69, si-75 and mercaptosilane; And/or the softener is one or two of aromatic hydrocarbon oil, tertiary butyl phenol aldehyde resin and octyl phenol aldehyde resin; And/or, the activator is stearic acid and zinc oxide; And/or, the vulcanizing agent is sulfur; and/or the accelerator is accelerator NS, accelerator CZ or a mixture of the two.
  7. 7. A process for the preparation of a rubber composition according to any one of claims 1 to 6, comprising the steps of: 1) The first section of mixing, namely adding natural rubber, zinc salt flame retardant, ceramic microbeads and 1/2 chlorinated polyethylene, pressing the lump for 30-40s, lifting the lump for cleaning, adding carbon black, and then pressing the lump for mixing until the temperature reaches 145-155 ℃ for rubber discharge; 2) The second section of mixing, namely adding a section of mixed rubber, butadiene rubber, the rest of chlorinated polyethylene, natural paraffin, white carbon black and silane, pressing and lump mixing to 120-130 ℃, adding a softening agent and other compounding agents (except vulcanizing agent and accelerator), pressing and lump mixing for 25-35s, lifting and lump cleaning, and pressing and lump mixing to 145-155 ℃ for rubber discharge; 3) And in the third section of mixing, adding the second-section mixed rubber, a vulcanizing agent and an accelerator, pressing the mixture for 30-40s, lifting the mixture for cleaning, and pressing the mixture for mixing to 105-115 ℃ for rubber discharge.
  8. 8. The method according to claim 7, wherein the first stage mixing, the second stage mixing and the third stage mixing are performed in an internal mixer, and each stage of mixing is performed after the rubber is discharged, thinned through an open mill, sheeted and cooled, and then enters the next stage mixing.
  9. 9. The method for producing a rubber composition according to claim 7, wherein the vulcanization condition of the rubber composition is 140 to 160℃for 15 to 30 minutes.
  10. 10. An all-steel radial tire comprising a crown, a shoulder, a sidewall, a belt layer, a cap ply and a ply layer, wherein the sidewall is prepared by vulcanizing the rubber composition according to any one of claims 1 to 6.

Description

Flame-retardant sidewall rubber composition, mixing method thereof and tire Technical Field The invention relates to the technical field of tire rubber manufacturing, in particular to a flame-retardant sidewall rubber composition, a mixing method thereof and a tire. Background The tire is used as a key component for contacting a vehicle with a road surface and carrying load, and the tire side is in a coupling working condition of alternating deflection, hot oxygen environment and external oxygen supply for a long time in the service process, wherein on one hand, the tire side repeatedly bends and deforms and generates hysteresis heat during rolling, especially in heavy load, high speed, long downhill continuous braking, summer high-temperature road surface, mine/dangerous chemicals transportation and other scenes, the local temperature rise of the tire side is easier to accumulate, on the other hand, the tire side is directly exposed in the air, the combined action of oxygen and heat can accelerate the thermal oxygen aging and cracking expansion of rubber, and on the other hand, the tire side can also induce combustion or smoldering under the conditions of external fire sources, friction sparks, electric arcs or abnormal overheat. The traditional sidewall rubber mostly adopts diene rubber such as Natural Rubber (NR), butadiene Rubber (BR) and the like as main bodies, and uses a carbon black reinforcing and sulfur system for vulcanization, and the system has mature advantages in the aspects of flex resistance, tear resistance and dynamic fatigue resistance, but the diene rubber body has higher combustibility, and the carbon black is easy to generate sparks and smoke dust when burnt, so that the safety redundancy of the sidewall under the condition of fire or thermal runaway is insufficient. Therefore, the flame-retardant/self-extinguishing capability is improved on the premise of not obviously sacrificing the dynamic fatigue, mechanical and processing properties of the side rubber, and the consistency and environment-friendly compliance requirements of industrial continuous mixing are met, so that the method becomes an important research direction in the field of tire materials. In the prior art, the flame retardant modification of rubber for tires generally adopts the following paths that firstly, halogen flame retardants are introduced and cooperated with synergists such as antimony trioxide, the flame retardant level is improved through gas phase blocking and condensed phase char formation/heat insulation, secondly, borate (such as zinc borate and the like) is adopted to cooperate with the halogen flame retardants and the antimony trioxide to improve smoke suppression and char formation, and thirdly, the flame retardance of materials is improved through high-polarity or body flame retardant elastomers/rubbers (such as chlorine-containing or fluorine-containing elastomers) or flame retardance is realized through endothermic decomposition of a large amount of inorganic flame retardant fillers. However, in engineering application of the high dynamic fatigue part of the sidewall rubber, the scheme often faces multi-objective contradiction among flame retardant efficiency, mechanics/fatigue, processing dispersion, environment protection compliance and cost, so that the comprehensive performance and large-scale manufacturing are difficult to be achieved. For example, the prior patent document CN104311909a discloses a flame-resistant and flame-retardant tire rubber composition, which is characterized in that a certain amount of flame retardant is additionally used for improving the flame-resistant and flame-retardant effect relative to a common tire sizing material, a flame-retardant bag/flame-retardant system consisting of decabromodiphenyl ether, antimony trioxide, zinc borate and the like is adopted in the embodiment, and a raw rubber system, a filling system and a protection system are matched and adjusted at the same time so as to meet the performance requirements of the tire. The scheme has the advantages that the flame retardant system is mature, the oxygen index and the flame retardant grade are improved directly, but engineering application of the scheme often has two hidden troubles, namely, a halogen flame retardant and an antimonous oxide system possibly bring higher smoke density and corrosive product risks in the combustion or thermal decomposition process, part of the halogen flame retardant system is more sensitive in the environment-friendly regulation and supply chain management level, and the flame retardant and various inorganic powder are used together to put higher requirements on mixing and dispersing, and stress concentration points are easily formed if the dispersing is uneven, so that the flex crack resistance and the dynamic fatigue life of the sidewall rubber are adversely affected. In other words, although the scheme can improve flame retardance, the long-term reliability and batch c