JP4573523B2 - Silica masterbatch, method for producing the same, and rubber composition using silica masterbatch - Google Patents

Description

  The present invention relates to a silica masterbatch and a rubber composition using the same. In particular, the present invention relates to a rubber component, a silica masterbatch composed of silica and a silane compound, and a tire rubber composition using the same.

  For tires such as automobiles, tires that have a good balance between low rolling resistance and wear resistance are required from the viewpoint of reducing fuel consumption and extending the period of tire replacement.

  In recent years, silica has attracted attention as a material that exhibits such performance. For example, a styrene-butadiene rubber (SBR) having a high glass transition temperature and carbon black are mixed to produce a carbon black masterbatch, and a rubber composition is produced by mixing this with SBR and silica having a low glass transition temperature. It has been proposed. According to this method, an SBR phase with a high glass transition temperature and a low SBR phase sea-island structure are obtained, and silica is segregated in the sea phase and carbon black is segregated in the island phase. Both wear resistance, which is a characteristic of carbon black, can be exhibited (see Patent Document 1). However, this method has not been sufficient to improve these performances.

  Since silica is a polar substance, it is inferior in compatibility with a polymer that is a nonpolar substance. Therefore, the combined use with a silane compound has become a common method. In order to express the above performance, it is necessary to efficiently react silica and silane compound and further polymer, and in the kneading process, a chemical that inhibits the reaction between silica and silane compound is added in another process. Improvements are being attempted. However, there is still room for improvement from the viewpoint of the reaction efficiency between silica and silane compounds and the dispersibility in the polymer. In such a method, reaction efficiency and dispersibility are greatly affected by kneading conditions (kneading temperature, timing of adding chemicals, etc.).

Japanese Patent Laid-Open No. 11-60816

  An object of the present invention is to provide a silica masterbatch that improves the reaction efficiency of silica and a silane compound, a silane compound and a polymer, and has good dispersibility of silica in the polymer, and a method for producing the same.

  Furthermore, an object of the present invention is to provide a rubber composition for tires that is excellent in rolling resistance reduction effect and wear resistance.

  The present invention relates to a method for producing a silica masterbatch, characterized in that natural rubber and / or an emulsion polymerized polymer, silica and a silane compound are mixed and then heat-treated.

  The emulsion polymerization polymer is preferably an emulsion polymerization styrene-butadiene rubber.

  The present invention also relates to a method for producing a silica masterbatch, characterized in that natural rubber latex and / or emulsion polymer emulsion, silica and silane compound are mixed and then heat-treated.

  The emulsion polymer emulsion is preferably an emulsion polymerized styrene-butadiene rubber emulsion.

  In each of the above production methods, it is preferable to use undried silica as the silica.

  In each of the above production methods, it is preferable to remove water after the heat treatment.

  Furthermore, this invention relates to the silica masterbatch obtained by each said manufacturing method.

  Furthermore, the present invention is a rubber composition obtained using the silica masterbatch, wherein the rubber component in the silica masterbatch is 30% by weight or more of the total rubber component contained in the rubber composition, The present invention relates to a rubber composition containing 20 to 100 parts by weight of silica and 4 to 12 parts by weight of a silane compound with respect to 100 parts by weight of a rubber component.

  According to the present invention, a reactive (silane) is obtained by premixing a rubber component (especially an emulsion polymer emulsion and / or natural rubber latex), silica (especially undried silica) and a silane compound and applying heat treatment. A silica masterbatch with a high reaction rate) can be obtained.

  Further, by using the silica masterbatch, a tire rubber composition having an effect of reducing rolling resistance and excellent wear resistance can be obtained.

  In the method for producing a silica masterbatch of the present invention, a rubber component, silica and a silane compound are mixed in advance, and heat treatment is performed, whereby the reaction efficiency between the silica and the silane compound is high and the dispersibility in the polymer is good. A fresh silica masterbatch.

  As the rubber component, natural rubber and / or an emulsion polymerization polymer are used.

  Examples of the emulsion-polymerized polymer include emulsion-polymerized styrene-butadiene rubber (E-SBR), and E-SBR is preferably used in terms of a reaction in the same aqueous solution as silica particularly in the production process. .

  The upper limit of the styrene unit amount of the E-SBR is preferably 45% by weight, more preferably 40% by weight in the E-SBR. When the styrene unit amount exceeds 45% by weight, the wear resistance tends to be inferior.

  The lower limit of the glass transition temperature (Tg) of the E-SBR is preferably −60 ° C., more preferably −50 ° C. When Tg is less than −60 ° C., grip performance tends to be inferior. The upper limit of Tg is preferably −20 ° C., more preferably −30 ° C. When Tg exceeds −20 ° C., cracks tend to occur due to embrittlement at low temperatures.

  The rubber component is preferably mixed in a rubber latex state. For example, as the emulsion polymer, it is preferable to mix an emulsion polymer emulsion before solid state, that is, before aggregation and drying. In the case of natural rubber (NR), natural rubber latex is preferably used. In the case of E-SBR, it is preferable to use E-SBR emulsion.

  Similarly, the silica is preferably mixed with silica before drying, that is, undried silica.

  By mixing rubber latex and undried silica, the undried silica is kept in a fine particle state, the dispersibility in the polymer solution is improved, and the reaction efficiency with the silane compound is increased, resulting in a reduction in rolling resistance. , And improved wear resistance.

  Examples of the silane compound include bis (3-triethoxysilylpropyl) tetrasulfide, bis (triethoxysilylpropyl) disulfide, triethoxysilylpropyl isocyanate, vinyltriethoxysilane, vinyltrimethoxysilane, and γ-methacryloxypropyl. Trimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ- (polyethyleneamino) -propyltrimethoxysilane, N-β- (amino Examples thereof include silane coupling agents such as ethyl) -γ-aminopropyltrimethoxysilane and N′-vinylbenzyl-N-trimethoxysilylpropylethylenediamine salt. These may be used alone or in combination of two or more.

  When the rubber component, silica and silane compound are solid, a Banbury mixer and a kneader can be mixed, and when the rubber component is rubber latex and the silica is undried silica, they can be mixed in an aqueous solution tank.

  With respect to 100 parts by weight of the rubber component in the silica masterbatch, the content of silica is preferably 20 parts by weight at the lower limit, and more preferably 30 parts by weight. When the content of silica is less than 20 parts by weight, the effect obtained by blending silica tends not to be exhibited. Further, the upper limit of the silica content is preferably 100 parts by weight, more preferably 80 parts by weight. If the content of silica exceeds 100 parts by weight, processing into a veil tends to be difficult.

  The lower limit of the content of the silane compound is preferably 4 parts by weight, more preferably 6 parts by weight with respect to 100 parts by weight of the rubber component in the silica masterbatch. If the content of the silane compound is less than 4 parts by weight, it is not a sufficient amount for coating the surface of the silica, and the aggregation of the silica cannot be suppressed. Moreover, it is preferable that the upper limit of content of a silane compound is 15 weight part, Furthermore, 12 weight part. When the content of the silane compound exceeds 15 parts by weight, the workability (scorch) tends to deteriorate due to sulfur contained in the silane.

  Next, the obtained mixture is heat-treated at an appropriate temperature. There is an advantage that the reactivity and dispersibility are improved by mixing the rubber component, silica and silane compound and then further heat-treating.

  The heat treatment temperature is preferably 100 ° C., more preferably 120 ° C. at the lower limit. Below 100 ° C., unreacted silane tends to remain. Moreover, it is preferable that it is 200 degreeC at the upper limit, Furthermore, it is 170 degreeC. When the temperature exceeds 200 ° C., the reaction between the silane and the polymer occurs, and the Mooney viscosity tends to increase rapidly.

  The heat treatment time is preferably 60 minutes at the lower limit, and more preferably 120 minutes. Less than 60 minutes is insufficient to complete the reaction. Further, it is preferably 360 minutes at the upper limit, and more preferably 240 minutes. If it exceeds 360 minutes, there is a tendency that cost disadvantages occur in the process.

  Next, the rubber composition of the present invention will be described. The rubber composition of the present invention is obtained by kneading the silica masterbatch with other materials.

  Specific examples of the rubber component kneaded with the silica masterbatch include, for example, natural rubber (NR), various butadiene rubbers (BR), various styrene-butadiene copolymer rubbers (SBR), isoprene rubber (IR), Butyl rubber (IIR), acrylonitrile butadiene rubber (NBR), acrylonitrile-styrene-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene copolymer rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber , Isoprene-butadiene copolymer rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber, urethane rubber and the like. These may be used alone or in a blend of two or more. There is no particular limitation on the blend ratio when blending. Among these, NR, BR, SBR, IR, styrene-isoprene-butadiene copolymer rubber, etc. from the viewpoint of good workability for tire tread applications and obtaining wear resistance suitable for tire tread applications. Is preferred.

  In addition to the above, the rubber composition of the present invention includes a reinforcing agent such as carbon black and / or silica generally used for the production of a rubber composition for tire treads, process oil, wax, anti-aging agent, and silane coupling agent. A silane compound such as stearic acid and zinc oxide, and a vulcanizing agent such as sulfur and a vulcanization accelerator may be blended and added in an amount usually used as necessary.

  The rubber composition of the present invention can be obtained, for example, by kneading a mixture obtained by adding other materials to the silica master batch using a Banbury mixer or the like. At this time, the lower limit of the kneading temperature is preferably about 80 ° C., more preferably about 100 ° C. If the kneading temperature is lower than about 80 ° C., the rubber viscosity may increase and workability may decrease. Further, the upper limit of the kneading temperature is preferably about 200 ° C., more preferably 180 ° C. When the temperature exceeds 200 ° C., burning tends to occur.

  The compounding amount of the rubber component in the silica masterbatch is preferably determined so as to be 30% by weight or more, further 50% by weight or more, particularly 80% by weight of the total rubber component contained in the rubber composition. If the rubber component in the silica masterbatch is less than 30% by weight, the effect of using the silica masterbatch tends not to be obtained.

  The rubber composition of the present invention obtained as described above has a silica content (the total amount of silica in the silica masterbatch and silica added during kneading of the rubber composition) with respect to 100 parts by weight of the total rubber component. Is preferably 20 parts by weight, more preferably 30 parts by weight. If the total silica content is less than 20 parts by weight, sufficient effects tend not to be obtained. The upper limit of the total silica content is preferably 100 parts by weight, more preferably 80 parts by weight. When the total silica content exceeds 100 parts by weight, processability tends to deteriorate due to an increase in Mooney viscosity.

  The lower limit of the content of the silica compound (the total amount of the silane compound in the silica masterbatch and the silane compound added during kneading of the rubber composition) is 4 parts by weight with respect to 100 parts by weight of the total rubber component. preferable. When the content of the silane compound is less than 4 parts by weight, it is not a sufficient amount for coating the surface of the silica, and aggregation of the silica cannot be suppressed. As a result, Mooney viscosity increases, poor dispersion and the like tend to occur. Moreover, it is preferable that the upper limit of content of a silane compound is 12 weight part. When the content of the silane compound exceeds 12 parts by weight, the workability (scorch) tends to deteriorate due to sulfur contained in the silane.

  The use of the rubber composition of the present invention is not particularly limited, but it is preferably used for a tire tread portion. The rubber composition of the present invention is molded into a tread shape to form a general tire. A tire can be manufactured by a sulfur method.

  Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

The materials and test methods used in the examples and comparative examples are summarized below.
(material)
NR (solid): RSS # 3 manufactured by Tech Bee Hang
E-SBR (solid): SBR1502 manufactured by Sumitomo Chemical Co., Ltd. (styrene unit amount: 23 wt%, Tg: −54 ° C.)
Silica (powder): VN3 manufactured by Degussa
Silane compound: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Carbon Black: Diamond Black I manufactured by Mitsubishi Chemical Corporation
Aroma oil: Diana Process PS32 manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: Ozonon 6C manufactured by Seiko Chemical Co., Ltd.
Wax: Sannox wax manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Stearic acid: Tungsten zinc oxide manufactured by Nippon Oil & Fats Co., Ltd .: 2 types of zinc oxide manufactured by Mitsui Kinzoku Mining Co., Ltd. Powder sulfur vulcanization accelerator: NOCSELER NS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

(Test method)
Rolling resistance A test piece was prepared from a vulcanized rubber sample, and loss tangent (tan δ) at 60 ° C. under a condition of a frequency of 10 Hz and a dynamic strain of 2.0% using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. Was measured. The reciprocal of the obtained value of tan δ was taken and indicated as an index with Comparative Example 1 as 100 (reference) for the E-SBR system and Comparative Example 2 as the NR system. The larger the index, the smaller the tan δ, indicating that the rolling resistance is reduced and better.

Abrasion resistance A test piece was prepared from a vulcanized rubber sample, and surface rotation speed was 80m / min, sand fall rate was 20g / min, slip rate was 30%, load load using a lambone wear tester manufactured by Iwamoto Seisakusho Co., Ltd. A wear test was carried out at 40 N, and wear loss was measured. The test results are shown as an index with Comparative Example 1 as the E-SBR system and Comparative Example 2 as 100 (reference) in the NR system. The larger the index, the better the wear resistance.

Examples 1 to 4 and Comparative Example 1 <E-SBR system>
(Manufacturing method of silica masterbatch)
(1) Silica masterbatch A
Without agglomerating the E-SBR emulsion, undried silica and the silane compound were mixed at 100 ° C. for 60 minutes. At this time, E-SBR was mixed so that the weight ratio of rubber content: silica solid content: silane compound was 100: 56: 4 (silica solid content + silane compound = 60).
The obtained mixture was heat-treated at 170 ° C. for 240 minutes, and then water was removed to produce silica master batch A.

(2) Silica masterbatch B
E-SBR (solid), silica (solid), and the silane compound were kneaded at 100 ° C. for 5 minutes using a Banbury mixer, and then heat treated at 170 ° C. for 3 minutes to produce silica master batch B.

(Method for producing rubber composition)
The components listed in Table 1 were kneaded at about 150 ° C. for 5 minutes using a Banbury mixer. Sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded at 80 ° C. for 5 minutes with a biaxial open roll. The obtained rubber composition was vulcanized at 160 ° C. for 18 minutes to obtain a vulcanized rubber sample.

  The obtained vulcanized rubber samples were tested for rolling resistance and wear resistance. The results are shown in Table 1.

  In Example 1 in which E-SBR (solid), silica (solid) and silane compound of Comparative Example 1 were substituted with equal amounts of silica masterbatch A, the rolling resistance was reduced and the wear resistance was improved.

  The E-SBR (solid), silica (solid) and silane compound of Comparative Example 1 were partially substituted with the same amount of silica masterbatch A in Example 2, and silica masterbatch A, and the remaining E-SBR (solid ), Silica (solid) and a silane compound were also added in Example 3, and the same effect was obtained. In Example 4 in which partial substitution was performed with silica masterbatch A and the remaining E-SBR (solid), silica (solid) and silane compound were further added, the wear resistance was improved.

Examples 5 to 8 and Comparative Example 2 <NR system>
(Manufacturing method of silica masterbatch)
Silica masterbatch C
Natural rubber latex (NR latex) was mixed so that the weight ratio of rubber content: silica solid content: silane compound was 100: 56: 4 (silica solid content + silane compound = 60).
The obtained mixture was heat-treated at 150 ° C. for 240 minutes, and then water was removed to produce a silica master batch C.

Silica masterbatch D
NR (solid), silica (solid), and a silane compound were kneaded at 100 ° C. for 5 minutes using a Banbury mixer, and then heat-treated at 150 ° C. for 3 minutes to produce silica master batch D.

(Method for producing rubber composition)
A vulcanized rubber sample was obtained in the same manner as the E-SBR system except that the main components listed in Table 2 were used. The obtained vulcanized rubber samples were tested for rolling resistance and wear resistance. The results are shown in Table 2.

  In Example 5 in which NR (solid), silica (solid), and silane compound of Comparative Example 2 were substituted with equal amounts of silica masterbatch C, the rolling resistance was reduced and the wear resistance was improved.

  NR (solid), silica (solid) and silane compound of Comparative Example 2 were partially substituted with silica masterbatch D in equivalent amount of Example 6 and silica masterbatch C, and the remaining NR (solid), silica ( The same effect was also obtained in Example 7 in which a solid) and a silane compound were further added.

  In Example 8 where partial substitution was performed with silica masterbatch C and the remaining NR (solid), silica (solid) and silane compound were added afterwards, the wear resistance was improved.

Claims (8)

Natural rubber and / or emulsion polymerized polymer, after kneaded only silica and silane compounds, method for producing a silica masterbatch, characterized in that the heat treatment. The process according to claim 1, wherein the emulsion polymerized polymer is an emulsion polymerized styrene-butadiene rubber. The production method according to claim 1 or 2 , wherein water is removed after the heat treatment. A method for producing a silica masterbatch, characterized in that a natural rubber latex and / or emulsion polymer emulsion, silica and a silane compound alone are mixed , heat treated, and water is removed after the heat treatment . The process according to claim 4 , wherein the emulsion polymerization polymer emulsion is an emulsion polymerization styrene-butadiene rubber emulsion. The production method according to claim 1, 2 , 3 , 4, or 5 , wherein undried silica is used as the silica. The silica masterbatch obtained by the manufacturing method of Claim 1, 2, 3, 4, 5 or 6. A rubber composition obtained using the silica masterbatch according to claim 7, wherein the rubber component in the silica masterbatch is 30% by weight or more of the total rubber component contained in the rubber composition, A rubber composition containing 20 to 100 parts by weight of silica and 4 to 12 parts by weight of a silane compound with respect to 100 parts by weight.