JP2002309053A - White rubber composition and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white rubber composition excellent in whiteness, having excellent rubber characteristics including rubber processability, vulcanization characteristic, strength, hardness and modulus and a tire using the rubber composition. SOLUTION: This white rubber composition is obtained by compounding 100 pts.wt. rubber component containing >=20 pts.wt. halogenated butyl rubber with 10-200 pts.wt. at least one kind of group consisting of fibrous xonotlite and magnesium oxysulfate whisker. This tire is obtained by using the rubber composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a white rubber composition used for a white rubber portion of a rubber product such as a tire, and a tire using the same.

[0002]

2. Description of the Related Art Conventionally, a sidewall line of a tire has a circular line formed of white rubber for decoration, a letter such as a manufacturing company name or a brand name, a design pattern or the like, a so-called white line, a white letter, or the like. May be provided.

As a filler for the white rubber, a white filler such as calcium carbonate, kaolin clay or silica has been used in place of carbon black used in the compounding of a usual rubber composition.

[0004] The above-mentioned white filler has a lower rubber reinforcing effect than carbon black, and rubber properties such as rubber strength, hardness and modulus are inferior to those of carbon black compounding, and cracks occur in the white rubber portion during use. This is problematic in that it not only impairs the appearance but also reduces the durability of the tire.

[0005] In addition, due to the lack of the rubber properties, there is a problem that in the polishing step of the sidewall portion surface where the white rubber is exposed on the surface, polishing marks of a glider remain on the surface of the white rubber to reduce the commercial value. During the use of the tire, there is a problem in that the polished traces are clogged with dirt, dust, etc., and the white rubber is contaminated or discolored, thereby impairing the decorativeness.

In conventional white fillers, calcium carbonate has a high degree of whiteness but has a particularly small reinforcing effect, and kaolin-based clay is a yellowish-white powder, so that the rubber color is dull, and silica has a vivid white color. Each of the white fillers has the problem that the dispersibility in the rubber is poor and the viscosity of the unvulcanized rubber increases and the vulcanization rate slows down. Each white filler has satisfactory whiteness and rubber characteristics. Had been rare.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and expresses vivid whiteness, and is excellent in rubber processability and vulcanization characteristics, as well as rubber strength, hardness and modulus. An object of the present invention is to provide a white rubber composition having rubber properties and a tire using the same.

[0008]

According to the present invention, at least one member selected from the group consisting of fibrous zonotolite and magnesium oxysulfate whisker is added to 100 parts by weight of a rubber component containing at least 20 parts by weight of a halogenated butyl rubber. It is a white rubber composition characterized by being compounded by weight.

According to the white rubber composition of the present invention, the halogenated butyl rubber is excellent in weather resistance, chemical resistance, oil resistance, etc., has good compatibility with other rubbers, and has a good vulcanization rate, so that it is white. Suitable as a rubber component. A white rubber composition having excellent whiteness and rubber properties and having good workability can be obtained by mixing a predetermined amount of one or more selected from the group consisting of fibrous zonotolite and magnesium oxysulfate whisker. be able to.

The present invention also provides a tire using the white rubber composition, wherein the white rubber composition is applied mainly to a sidewall portion to form a white line or a white letter, Vivid white color is obtained to obtain an excellent decorative effect, and the appearance performance can be improved. In addition, good polishing workability when forming white lines etc., small polishing scratches and high commercial value, and it is possible to prevent contamination during use because dust and the like are not easily clogged,
Further, the occurrence of cracks in the white portion can be suppressed, and the same durability as a normal tire can be obtained.

[0011]

Embodiments of the present invention will be described below.

The white rubber composition of the present invention contains at least 20 parts by weight of a highly colorless and highly transparent halogenated butyl rubber as a rubber component based on 100 parts by weight of the raw rubber component. The remaining rubber component is not particularly limited, but from the viewpoint of constituting the sidewall portion of the tire, a diene-based rubber that provides excellent durability, such as rubber strength, hardness and modulus, is preferable. , Isoprene rubber, styrene-butadiene rubber, butadiene rubber, and the like, and one or more of them can be used.

As the halogenated butyl rubber, brominated butyl rubber, chlorinated butyl rubber and the like can be used. Weather resistance such as ozone resistance and ultraviolet resistance, chemical resistance, etc.
Since butyl rubber is excellent in oil resistance and the like, and is halogenated, compatibility with other rubbers and a delay in vulcanization rate are improved, so that it is preferable as a white rubber component.

The compounding amount of the halogenated butyl rubber is 2
If the amount is less than 0 parts by weight, sufficient weather resistance such as ozone resistance and ultraviolet light resistance cannot be obtained, and the white rubber portion during use of the tire is liable to cause deterioration such as minute cracks, and the appearance and durability are likely to be reduced. .

The white filler used in the present invention is used alone or in combination of two or more selected from the group consisting of fibrous zonotolite and magnesium oxysulfate whisker, and 10 to 200 parts by weight based on 100 parts by weight of the rubber component. In the range of parts.

The fibrous zonotolite and magnesium oxysulfate whisker improve the whiteness of the vulcanized rubber and can exhibit a brighter white color than the conventional white filler.

Further, since the dispersibility in rubber is good, there is no increase in rubber viscosity, and there is no delay in vulcanization because vulcanizing agents such as vulcanization accelerators are not adsorbed. Therefore, the rubber processability and workability are not impaired, and the rubber reinforcing effect is excellent, so that rubber properties such as rubber strength, hardness, and modulus can be improved to the same level as the carbon black compounding.

When the amount of the fibrous zonotolite and magnesium oxysulfate whisker is less than 10 parts by weight, the whiteness of the rubber composition is not sufficiently exhibited, and the rubber strength and
Improvement in rubber properties such as hardness and modulus cannot be obtained.
On the other hand, when the amount exceeds 200 parts by weight, the dispersibility in the rubber decreases, and mixing and molding are difficult, which is not preferable.

The fibrous zonotolite has a chemical formula of 6C
refers to a needle crystal substance represented by _{aO · 6SiO 2 · 2H 2 O} , but the fiber shape is not particularly limited, 1 to 5 [mu] m average fiber length (L) has an average fiber diameter (D) is 0.1
0.5 μm is a preferable range, L exceeds 5 μm,
When D is less than 0.1 μm, it becomes difficult to uniformly disperse the rubber in the rubber during rubber mixing, and L is less than 1 μm and D is 0.1 μm.
If it exceeds 5 μm, the reinforcing property is lacking, and it becomes difficult to obtain desired rubber properties.

Further, a surface-treated fibrous zonotolite obtained by treating the surface of a fibrous zonotolite with a surfactant or a coupling agent can be used, and the dispersibility in rubber is improved as compared with an untreated product. The effect is more exhibited, and the rubber characteristics can be improved.

As the surfactant, various anionic, cationic, zwitterionic and nonionic surfactants can be used, such as alkyl ether sulfate, tetradecylamine acetate, dimethylalkyl lauryl petaine, and the like. And polyoxyethylene octadecylamine.

As the above-mentioned coupling agent, various coupling agents such as silane-based, titanate-based, aluminum-based, chromium-based, and boron-based coupling agents can be used. Agent is a preferred form, and as the silane coupling agent,
For example, vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tris (β-methoxy ethoxy) silane and the like can be mentioned.

The fiber shape of this surface-treated fibrous zonotolite has an average fiber length (L) of 1 like the untreated product.
It is preferable that the average fiber diameter (D) is 0.1 to 0.5 μm.

The magnesium oxysulfate whisker has a chemical formula of MgSO ₄ .5Mg (OH) ₂
A whisker-like substance represented by 3H ₂ O, whose whisker shape is not particularly limited, but the average whisker length (L) is preferably 10 μm or less, and the average whisker diameter (D) is preferably 0.5 to 1.0 μm. Yes, L is 10μ
If D exceeds 0.5 and D is less than 0.5 μm, it is difficult to uniformly disperse the rubber in the rubber during mixing, and if D exceeds 1 μm, the reinforcing properties are lacking, and the desired rubber properties cannot be obtained, which is not preferable.

In the white rubber composition of the present invention, the above-mentioned fibrous zonotolite and magnesium oxysulfate whisker can be used alone or in combination of two or more.

It is preferable that titanium oxide and ultramarine blue are added to the white rubber composition of the present invention. Titanium oxide prevents yellowing of the white rubber, and a small amount of ultramarine blue enhances the white color and provides more vivid whiteness. Has the effect of expressing

Further, the white rubber composition of the present invention optionally uses compounding agents such as stearic acid, zinc white, fillers, softeners, antioxidants, resins, vulcanizing agents and vulcanization accelerators. can do.

The white rubber composition of the present invention is prepared by mixing a rubber component with fibrous zonotolite, magnesium oxysulfate whisker, and other compounding agents using a Banbury mixer, a kneader, a roll, or the like that is commonly used in the rubber industry. Obtained by mixing according to a conventional method.

The present invention also relates to a tire using the white rubber composition, which is usually used for a white rubber portion such as a white line or a white letter on a sidewall portion,
It is used for decoration of automobile tires for passenger cars, trucks and buses, motorcycle tires, bicycle tires, infant tricycles and game tires, and can improve the appearance performance.

The formation of the above-mentioned white line or white letter is a method used in the production process of a tire having a general white line, that is, an unvulcanized white rubber composition formed in a tape shape is not vulcanized. The tire may be buried around the sidewall portion of the vulcanized tire, and the periphery of the sidewall portion after vulcanization of the tire may be polished using a grinder device to expose the white rubber portion on the surface of the sidewall portion.

Of course, the white rubber composition of the present invention can be used for applications other than tires.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The rubber components, compounding agents and white fillers used in Examples and Comparative Examples are as shown below, and the amounts (parts by weight) thereof are shown in Tables 1 and 2.

Natural rubber: SIR3L Brominated butyl rubber: EXXON bromobutyl 22
55-Stearic acid: Industrial stearic acid-Zinc flower: No. 1 zinc flower-Ultramarine: Daiichi Kasei Co., Ltd. Ultramarine No. 1500-Titanium oxide: Furukawa Kikai Metal Co., Ltd. Anatase FA
-50 ・ Sulfur: 150 mesh powdered sulfur ・ Vulcanization accelerator DM: Ouchi Shinko Chemical Co., Ltd. Noxeller DM ・ Calcium carbonate: Nitto Powder Co., Ltd. Nobelite TT ・ Caryon clay: Takehara Chemical Co., Ltd. Hard Bright・ Silica: Nipsil AQ, Nippon Silica Kogyo Co., Ltd. ・ Fibrous zonotolite (denoted as Zonotorite A): Ube Materials Co., Ltd. Zonoheidi ・ Surface treated fibrous zonotolite (denoted as Zonotorite B): Ube Materials Co., Ltd. Surface treatment Zonoheidi ・ Magnesium oxysulfate whisker (denoted as Mg whisker): Mos Heidi, Ube Materials Co., Ltd. Each rubber composition shown in Tables 1 and 2 is mixed in a usual manner using a 20-liter closed Banbury mixer, and each white color is mixed. A rubber composition is prepared and its vulcanization properties, rubber properties, whiteness, The polishing properties were evaluated by the following test methods. The results are shown in Tables 1 and 2.

(Vulcanization properties) Mooney viscosity: JIS K
Measured at 100 ° C in accordance with 6300, "ML1 + 4"
Indicated by Comparative Example 1 is indicated by an index with 100 as an index, and index 8
0 to 130 is a good range.

Rheometer vulcanization rate: JIS K63
Measured at 160 ° C. according to 00 and shown as “t90”. Comparative Example 1 is shown as an index with 100 as the index. The smaller the numerical value, the faster the vulcanization rate and the better.

(Rubber properties) Hardness "Hs", 100% and 300% tensile stress "M100", "M300", tensile strength "TB", and elongation "EB" were measured and indicated in accordance with JIS K6253. Was. The index is shown as an index with Comparative Example 1 being 100, and the larger the value, the better.

(Whiteness) The vulcanized sample of each white rubber composition was visually judged, and a bright white “鮮”, a white (equivalent level to Comparative Example 1) “○”, and a white dullness “ △ "
And whiteness were evaluated and are shown in the table.

(Abrasiveness) A white line tire (size P21) in which each white rubber composition was embedded in a sidewall portion
5 / 65R14), a sidewall portion was polished using a grinder polisher to expose white rubber, and polishing marks on the white rubber surface were visually judged. "A" indicates that the polishing scratches were small and at a good level, and "A" indicates that the polishing scratches were large and many, and "A" indicates poor appearance, and the polishing properties were evaluated.

[0040]

[Table 1]

[0041]

[Table 2]

As shown in Table 1, each of the examples according to the present invention has excellent vulcanization characteristics and rubber characteristics, and has satisfactory whiteness and excellent polishing properties. Above all, Examples 2, 4, 6, 7, 8 in which 70 parts by weight of fibrous zonotolite or magnesium oxysulfate whisker was blended.
Has a vivid white color, maintains strength and elongation, can improve rubber hardness and modulus, and is excellent in abrasiveness.

On the other hand, in each of the comparative examples shown in Table 2, the whiteness was inferior when the white filler was a carion-based clay (Comparative Example 2).
Silica compound (Comparative Example 3) has satisfactory whiteness, but has an increased viscosity, a low vulcanization rate, poor workability, and reduced rubber properties. Also, Comparative Example 4 with a small amount of zonotolite did not have satisfactory whiteness, and had poor polishing properties due to a decrease in rubber characteristics. Comparative Example 5 with a large amount of compound had good whiteness, but had poor dispersibility in rubber. This is unfavorable because the viscosity decreases and the Mooney viscosity increases and the vulcanization rate is delayed.

[0044]

As described above, in the white rubber composition of the present invention, fibrous zonotolite and magnesium oxysulfate whisker are used alone or in combination with 100 parts by weight of a rubber component containing 20 parts by weight or more of halogenated butyl rubber. 10 to 200 parts by weight, and has excellent workability such as whiteness, workability, and vulcanizability, and has excellent rubber properties such as rubber strength, hardness, and modulus. The tire having the white line used in Example 1 shows a bright white color and has excellent appearance performance capable of suppressing contamination during use.

Claims (2)

[Claims] 1. A rubber composition containing 20 parts by weight or more of halogenated butyl rubber and 100 parts by weight of at least one of a group consisting of fibrous zonotolite and magnesium oxysulfate whisker. Characteristic white rubber composition. 2. A tire using the white rubber composition according to claim 1.