JP5073189B2 - Method for producing rubber composition and rubber composition obtained thereby - Google Patents

Description

  The present invention relates to a method for producing a rubber composition and a rubber composition obtained thereby.

  In particular, tire treads of pneumatic tires are required to have both excellent grip performance on wet road surfaces (wet grip performance) and excellent wear resistance, and various studies have been made.

  For example, Patent Document 1 discloses a rubber composition in which a halogenated butyl rubber or a brominated product of a copolymer of isobutylene and paramethylstyrene and a diene rubber are blended. According to it, selection of brominated products of halogenated butyl rubber or copolymer of isobutylene and paramethylstyrene and diene rubber, and further brominated products of copolymer of halogenated butyl rubber or isobutylene and paramethylstyrene. Although wet grip performance has improved to some extent from mechanical vulcanization, it has not been sufficient. Furthermore, when the blending amount is increased in order to increase the wet grip performance of the brominated product of the halogenated butyl rubber or isobutylene and paramethylstyrene copolymer, the wear resistance tends to decrease.

JP 2000-191865 A

  An object of this invention is to provide the manufacturing method of the rubber composition excellent in wet grip performance and abrasion resistance, and the rubber composition obtained by it.

  The present invention contains (A) 20 to 80% by weight of one or more rubbers selected from (A) halogenated butyl rubber and a copolymer of isobutylene and paramethylstyrene, and (B) 20 to 80% by weight of a diene rubber. A method for producing a rubber composition containing 20 to 100 parts by weight of a reinforcing agent with respect to 100 parts by weight of a rubber component, wherein (1) the rubber (A) and It comprises a step of mixing a reinforcing agent of 80% by weight or more of the total amount of the reinforcing agent for 10 seconds or more, and (2) a step of mixing the diene rubber (B), the remaining reinforcing agent and the mixture obtained in the step (1). The present invention relates to a method for producing a rubber composition.

  The reinforcing agent is preferably carbon black or silica.

  Moreover, this invention relates to the rubber composition obtained by the said manufacturing method.

  Furthermore, the present invention relates to a pneumatic tire having a tire tread made of the rubber composition.

  According to the present invention, first, a bound rubber is formed by mixing one or more kinds of rubber selected from halogenated butyl rubber and a halide of a copolymer of isobutylene and paramethylstyrene and a specific amount of reinforcing agent. By further mixing the diene rubber, the obtained rubber composition can improve both wet grip performance and wear resistance.

  The method for producing the rubber composition of the present invention is selected from (1) a halogenated butyl rubber and a copolymer halide of isobutylene and paramethylstyrene (1) at 50 to 200 ° C. in a closed mixer 1 A step of mixing more than 10 kinds of rubber (rubber (A)) and 80% by weight or more of the reinforcing agent for 10 seconds or more, and (2) (B) diene rubber (rubber (B)) and the remaining reinforcement. It comprises a step of mixing the agent and the mixture obtained in step (1).

  Examples of the halogenated butyl rubber in the rubber (A) include chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), fluorinated butyl rubber (F-IIR), and iodinated butyl rubber (I-IIR). , Br-IIR is preferred.

  The rubber (A) is a halide of a copolymer of isobutylene and paramethylstyrene. In addition to the halide of the copolymer of isobutylene and paramethylstyrene, there is no limitation as long as it is a halide of a copolymer of isomonoolefin and paraalkylstyrene, but the copolymer weight of isobutylene and paramethylstyrene is not limited. Combined halides are preferred.

  The halide of the copolymer of isobutylene and paramethylstyrene is not particularly limited, but from the viewpoint of co-crosslinking property, the amount of isobutylene unit / paramethylstyrene unit is 90/10 to 98/2 in weight ratio. The halogen content is preferably 0.5 to 5% by weight.

  Examples of the halide of the copolymer of isobutylene and paramethylstyrene include fluorides, chlorides, bromides, and iodides. Among these, bromides are preferable.

  As the rubber (A), any one of halogenated butyl rubber and halogenated copolymer of isobutylene and paramethylstyrene, or a combination thereof can be used. However, since the crosslinking efficiency is high, isobutylene and para A copolymer halide with methylstyrene is preferable, and a bromide copolymer of isobutylene and paramethylstyrene is more preferable.

  The halogen content of the halogenated butyl rubber or the halide of the copolymer of isobutylene and paramethylstyrene is preferably 1.8 to 2.4% by weight. If the halogen content is less than 1.8% by weight, the degree of vulcanization is too low and the strength tends to decrease. On the other hand, when the halogen content exceeds 2.4% by weight, the degree of vulcanization becomes high and tends to be hard.

  The rubber (B) is vulcanized at a carbon-carbon double bond portion such as natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), isoprene rubber (IR), acrylonitrile butadiene rubber (NBR), etc. Among them, NR and SBR are preferable, and NR is more preferable because the strength of the tire tread is improved and the tackiness is also improved.

  Examples of the reinforcing agent include carbon black, silica, clay, aluminum hydroxide, calcium carbonate, talc, mica, and the like. Carbon black or silica is preferable because it forms a lot of bound rubber and has excellent reinforcing properties.

  There is no restriction | limiting in particular as said carbon black, For example, HAF, ISAF, SAF, GPF, FEF, FT etc. can be used.

  In normal kneading of the rubber composition, the rubber (A) and the reinforcing agent are kneaded together with other rubber components and additives, so that sufficient interaction between the rubber (A) and the reinforcing agent is achieved. Cannot be obtained, and sufficient wear resistance and wet grip performance cannot be obtained.

  On the other hand, as in the present invention, in the step (1), the rubber (A) and a large amount of the reinforcing agent are kneaded first so that the rubber (A) and the reinforcing agent show a strong interaction, and the vicinity of the reinforcing agent The rubber (A) can be a bound rubber. Since the bound rubber is firmly attached to the reinforcing agent, a large stress can be generated against an external stimulus.

  In the rubber composition obtained by the production method of the present invention, when an external stimulus is given to the rubber composition, stress concentration occurs in a portion having a very high elastic modulus, that is, in the vicinity of the reinforcing agent, and thus a bound rubber is obtained. The rubber composition in which the mechanical properties of the rubber (A) (mechanical properties contributing to wet grip, such as tan δ) are dominant over the mechanical properties of the rubber composition, and as a result both wet grip performance and wear resistance are improved. You can get things.

  The compounding ratio of the reinforcing agent in the step (1) is 80% by weight or more, preferably 85% by weight or more of the total amount of the reinforcing agent. When the reinforcing agent blended in the step (1) is less than 80% by weight, the amount of bound rubber of the target rubber component cannot be obtained, the tire performance is not improved, and the breaking strength is not sufficient. Further, the compounding ratio of the reinforcing agent is particularly preferably 100% by weight in order to bring out all the properties of the rubber (A).

The mixing step of step (1) is performed by a closed mixer. Here, examples of the closed mixer include a Banbury (trademark) mixer and a kneader.

  In the step (1), the mixing temperature in the closed mixer is 50 ° C. or higher. When the mixing temperature is less than 50 ° C., heat sufficient to form a bound rubber formed by heat during mixing cannot be obtained, and it is difficult to form a bound rubber. In step (1), the mixing temperature in the closed mixer is 200 ° C. or lower. When the mixing temperature exceeds 200 ° C., the heat resistance performance of the rubber is exceeded, so that the rubber deteriorates.

  In step (1), the mixing time is 10 seconds or longer, preferably 30 seconds or longer. When the mixing time is less than 10 seconds, heat is not generated in the rubber being mixed, and as a result, a bound rubber is hardly formed. The mixing time is preferably 600 seconds or shorter, and more preferably 480 seconds or shorter. Even if the mixing time exceeds 600 seconds, an increase in bound rubber is not recognized, so that the cost tends to increase, and further, the rubber tends to deteriorate by kneading for a long time.

  In the step (2), the rubber (B) and the remaining reinforcing agent are mixed together with the mixture obtained in the step (1). The remaining reinforcing agent refers to a reinforcing agent that was not used in step (1) among the reinforcing agents used in the production of the rubber composition.

  The mixing step in step (2) is preferably performed with a closed mixer.

  In the step (2), the mixing temperature in the closed mixer is preferably 30 to 200 ° C. If the mixing temperature is less than 30 ° C., the mixture obtained in the step (1) has a high viscosity, so that it tends to be difficult to mix with the rubber (B), and if the mixing temperature exceeds 200 ° C., Degradation tends to occur.

  In the step (2), the mixing time is preferably 30 to 600 seconds. If the mixing time is less than 30 seconds, the rubber (A) and the rubber (B) tend to be insufficiently mixed. If the mixing time exceeds 600 seconds, the rubber temperature tends to increase and the rubber tends to deteriorate. There is.

  In the method for producing a rubber composition of the present invention, additives generally used in the rubber composition, for example, softeners such as oil, stearic acid, zinc oxide and the like can be blended. In order to improve property, it is preferable to mix in a process (2).

  The mixture obtained through the steps (1) and (2) may be mixed together with a vulcanizing agent and a vulcanization accelerator in a roll machine such as an open roll, as in the production of a general rubber composition. it can.

  The rubber composition obtained by the production method of the present invention comprises a rubber component and a reinforcing agent.

  The rubber component is composed of rubber (A) and rubber (B).

  In the rubber composition, the content of the rubber (A) in the rubber component is 20% by weight or more, preferably 25% by weight or more. When the content of the rubber (A) is less than 20% by weight, the low air permeability and moisture permeability are poor, and the tire performance of the rubber (A) is impaired. The rubber (A) content is 80% by weight or less, preferably 75% by weight or less. When the rubber (A) content exceeds 80% by weight, the tire performance of the rubber (B) is impaired.

  In the rubber composition, the content of the rubber (B) in the rubber component is 20% by weight or more, preferably 25% by weight or more. When the content of the rubber (B) is less than 20% by weight, the tire performance of the rubber (B) is impaired. The rubber (B) content is 80% by weight or less, preferably 75% by weight or less. When the content of the rubber (B) exceeds 80% by weight, the tire performance of the rubber (A) is impaired.

  The reinforcing agent is preferably 20 parts by weight or more, more preferably 30 parts by weight or more, and still more preferably 40 parts by weight or more with respect to 100 parts by weight of the rubber component. When the compounding amount of the reinforcing agent is less than 20 parts by weight, the reinforcing property tends to be low. The amount of the reinforcing agent is preferably 100 parts by weight or less, more preferably 90 parts by weight or less, and still more preferably 80 parts by weight or less. When the compounding amount of the reinforcing agent exceeds 100 parts by weight, workability is deteriorated.

  In addition to the rubber component and the reinforcing agent, the rubber composition of the present invention is a general compound used for tire rubber compounding, for example, a plasticizer such as chemical oil, a tackifier, A crosslinking agent such as sulfur and zinc white, a crosslinking aid, a vulcanization accelerator and the like can be included.

  In the rubber composition of the present invention, the rubber (A) and the reinforcing agent are kneaded in a closed mixer (step (1)), and then the diene rubber (B) and the remaining reinforcing agent are further mixed ( Step (2)).

  The content of rubber (A) in the bound rubber produced in the vicinity of the reinforcing agent in the rubber composition obtained by the production method of the present invention is determined by immersing the unvulcanized rubber composition in a good solvent such as toluene, and It can be quantified by chemical analysis for removing the CB gel and the rubber component (bound rubber) that have become insoluble in the solvent. Further, even with a transmission electron microscope, it is possible to determine which raw rubber the bound rubber is made of, depending on the position of the reinforcing agent.

  The rubber (A) content in the bound rubber is preferably 65 to 100%. When the rubber (A) content is less than 65%, the tire performance and mechanical properties of the rubber (A) tend not to be sufficiently exhibited.

  The rubber composition obtained by the production method of the present invention is preferably used as a tire. In particular, since it exhibits excellent wet grip performance and wear resistance, it is suitably used as a tire tread among tire members.

  Next, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

  In Examples and Comparative Examples, chemicals used for evaluation rubber are shown. Table 1 shows the contents of the rubber for evaluation.

Brominated product of copolymer of isobutylene and paramethylstyrene: manufactured by Nippon Butyl Co., Ltd. (distributor: ExxonMobil Co., Ltd.) Exxpro 90-10 (bromine content: 2.0% by weight)
Natural rubber (NR): RSS # 3
Carbon Black (HAF): Diamond Black H manufactured by Mitsubishi Chemical Corporation
Stearic acid: Zinc stearate manufactured by Nippon Oil & Fats Co., Ltd .: Zinc Hana No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd. Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. NS: Ouchi Shinsei Chemical Noxeller NS Co., Ltd.
Vulcanization accelerator DM: NOCELLER DM of Ouchi Shinsei Chemical Co., Ltd.

Example 1 and Comparative Examples 1-2
<Method for producing rubber for evaluation>
(Production of rubber for evaluation of Example 1)
Exxpro 90-10 and HAF in the blending amounts shown in step (1) of Table 1 are kneaded for 5 minutes under a condition of 100 ° C. using a Banbury mixer, and then the mixture obtained in step (1) is mixed. Then, NR, stearic acid, and zinc white as shown in step (2) of Table 1 were added and kneaded for 5 minutes at 100 ° C. using a Banbury mixer to prepare a kneaded product. Next, sulfur and vulcanization accelerators NS and DM having the blending amounts shown in Table 1 were added to the kneaded product, and kneaded at 50 ° C. for 5 minutes using an 8-inch roll. Was subjected to press vulcanization at 160 ° C. for 10 minutes to produce a rubber for evaluation of Example 1. In the bound rubber in the rubber for evaluation of Example 1 calculated by immersing the kneaded product obtained in the step (2) in toluene for 48 hours and analyzing the obtained bound rubber by pyrolysis gas chromatography. The rubber (A) content was 80%.

(Production of rubber for evaluation of Comparative Example 1)
A rubber for evaluation of Comparative Example 1 was prepared in the same manner as in Example 1 except that NR was added and kneaded in Step (1) and HAF was added and kneaded in Step (2). In the bound rubber in the rubber for evaluation of Comparative Example 1 calculated by immersing the kneaded product obtained in the step (2) in toluene for 48 hours and analyzing the obtained bound rubber by pyrolysis gas chromatography. The rubber (A) content was 40%.

(Production of rubber for evaluation of Comparative Example 2)
A rubber for evaluation of Comparative Example 2 was produced in the same manner as in Example 1 except that NR was blended in Step (1) and Exxpro 90-10 was blended in Step (2). In the bound rubber in the rubber for evaluation of Comparative Example 2 calculated by immersing the kneaded product obtained in the step (2) in toluene for 48 hours and analyzing the obtained bound rubber by pyrolysis gas chromatography. The rubber (A) content was 3%.

  Using the evaluation rubbers of Example 1 and Comparative Examples 1 and 2, the following characteristic tests were performed.

(Tan δ)
Rubber for evaluation of Example 1 and Comparative Examples 1 and 2 at 0 ° C. under conditions of initial elongation of 10%, frequency of 10 Hz and dynamic amplitude of ± 0.25% using VES-FIII2 manufactured by Iwamoto Seisakusho Co., Ltd. Tan δ was measured. The larger tan δ at 0 ° C., the better the wet grip performance.

(Abrasion test)
Using a Lambourne abrasion tester, the Lambourne abrasion amount of the rubber for evaluation of Example 1 and Comparative Examples 1 and 2 was measured under the conditions of a load of 1.5 kgf, a temperature of 23 ° C., a slip rate of 50%, and a test time of 3 minutes. The volume loss amount of each formulation was calculated, and the volume loss amount of the comparative example was taken as 100, and the index was expressed by the following formula. The larger the wear index, the better the wear resistance.
(Abrasion index) = (Volume loss amount of Comparative Example 1) / (Volume loss amount of each formulation) × 100

(Wet grip test)
A pneumatic tire having a tread composed of the rubber composition of Example 1 and Comparative Examples 1 and 2 was produced (size 195 / 60R15). Run on a lubricated road surface at 40 km / h with a μ-s measurement vehicle equipped with the tire, measure the friction coefficient (μ) from when the brake is applied to when it stops, and detect the maximum friction coefficient during that time. did. Then, with respect to the obtained maximum friction coefficient, the maximum friction coefficient of Comparative Example 1 was set to 100, and the maximum friction coefficients of Example 1 and Comparative Example 2 were each displayed as an index (wet grip index). The larger the wet grip index, the better the wet grip performance of the tire.

  The test results are shown in Table 1.

Claims (3)

Rubber component 100 containing (A) 20 to 80% by weight of one or more kinds of rubbers selected from halogenated butyl rubber and halogenated copolymer of isobutylene and paramethylstyrene, and (B) 20 to 80% by weight of diene rubber A method for producing a rubber composition containing 20 to 100 parts by weight of a reinforcing agent with respect to parts by weight,
(1) Step of mixing rubber (A) and 100% by weight of the reinforcing agent in a closed mixer at 50 to 200 ° C. for 10 seconds or more, and (2) Diene rubber (B) and step A method for producing a rubber composition comprising a step of mixing the mixture obtained in (1). The method for producing a rubber composition according to claim 1, wherein the reinforcing agent is carbon black or silica. The method for producing a rubber composition according to claim 1, wherein the reinforcing agent is carbon black.