JPH11140234A - Rubber composition for inner liner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject rubber composition capable of exhibiting excellent rubber physical properties and low air permeability by compounding a rubber component with a plate-like mica having a specific aspect ratio at a specific ratio. SOLUTION: This rubber composition comprises a compound of (A) 100 pts.wt% rubber component with (B) 10-50 pts.wt. plate-like mica having 50-100 aspect ratio. The component A includes natural rubber or butyl-based rubber such as halogenated butyl rubber. The component B includes preferably sericite, muscovite or kaolinite. It is preferable in viewpoint excellent in tensile strength that the component B comprises 40-50 wt.% silicon dioxide, 30-40 wt.% aluminum oxide, 1-5 wt.% ferric oxide and 8-12 wt.% potassium oxide. The rubber composition is obtained by kneading and vulcanizing the component A and the component B. Inner liner of tire excellent in rubber physical property and low air permeability even if the structure consists of one layer can be provided thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition for an inner liner of a tire having excellent rubber properties and low air permeability.

[0002]

2. Description of the Related Art In recent years, tires have been reduced in rolling resistance and reduced in weight in accordance with social demands for lowering fuel consumption of vehicles. Above all, as a method of reducing the weight, there is a method of paying attention to the inner liner and reducing the thickness of the gauge while maintaining a slight air permeability that impairs the physical properties of rubber.

For example, JP-A-6-116439 discloses that mica is filled in a rubber composition for an inner liner. However, the technique described in this publication uses a special structure of a rubber laminate having at least three layers, and it cannot be said that a single layer is particularly excellent in rubber physical properties and low air permeability.

Accordingly, the present inventors have conducted intensive studies and as a result, have obtained a rubber composition for an inner liner which is excellent in rubber physical properties and low air permeability even with an ordinary one-layer structure by using a specific mica as a filler. Reached.

[0005]

That is, an object of the present invention is to provide a rubber composition for an inner liner having excellent rubber properties and low air permeability.

[0006]

According to the present invention, there is provided a rubber component comprising:
The present invention relates to a rubber composition for an inner liner, which comprises 0 parts by weight and 10 to 50 parts by weight of mica having a plate-like aspect ratio of 50 to 100.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The rubber component used in the present invention includes, for example, diene rubbers such as natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR) and isoprene rubber (IR), for example, bromine. Butyl rubber (Br-IIR), chlorinated butyl rubber (Cl
-IIR), butyl rubber such as butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR) and the like, and at least one of these may be used. Above all, butyl rubber is preferably used from the viewpoint of low air permeability, and halogenated butyl rubber (Br-II) is preferable from the viewpoint that vulcanization with sulfur is possible.
R, CI-IIR) is particularly preferred.

The types of mica used in the present invention include, for example, sericite (sericite), muscovite (muscovite), phlogopite (phlogovite), soda mica,
Biotite, kaolinite and the like can be mentioned, and at least one of these may be used. Above all, sericite, muscovite, and kaolinite are preferably used because they have few impurities, and sericite is particularly preferable because they have a small particle size and are unlikely to become fracture nuclei.

The mica used in the present invention contains silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), ferric oxide (Fe ₂ O ₃ ) and potassium oxide (K ₂ O). Regarding the composition of the mica, SiO ₂ is 35 to 50.
%, Al ₂ O ₃ is 10 to 40% by weight, Fe ₂ O ₃ is 1 to
10 wt% and K ₂ O may be 5 to 15 wt%,
SiO ₂ is 40 to 50 wt% from the viewpoint of excellent expansion force, Al ₂ O ₃ is 30 to 40 wt%, Fe ₂ O ₃ is 1-5 wt%, of K ₂ O is 8 to 12 wt% Is preferred. The mica usually contains impurities such as zirconium (Zr) and zinc (Zn), but may be any as long as the effects of the present invention are not impaired.

[0010] The mica in the present invention is plate-shaped, and when the obtained rubber composition is processed into an inner liner, the plane of the mica is oriented parallel to the plane direction of the inner liner. Thereby, it has a function of improving low air permeability.

In the present invention, the term "plate-like" means
This is a concept that includes shapes such as flakes and disks.

The average particle size of the mica used in the present invention may be 10 to 30 μm from the viewpoint that the mica is not bonded to the rubber component and if it is too large, it tends to become a destruction nucleus. 10-20 μm
Is preferred. Here, the average particle diameter refers to an average value of the major axis of the plate-like mica.

Further, the aspect ratio of mica used in the present invention may be 50 to 100 from the viewpoint that thinner mica is less likely to become a fracture nucleus, but is preferably from 70 to 100 from the viewpoint of improving mechanical fatigue. preferable.

Incidentally, the aspect ratio is defined as
It refers to the ratio of the major axis to the thickness.

If the mixing ratio of the mica is less than 10 parts by weight, the effect of improving low air permeability cannot be obtained, and if the mixing ratio is more than 50 parts by weight, a significant low air permeability depending on the mixing amount is obtained. From 10 to 50 parts by weight based on 100 parts by weight of the rubber component from the viewpoint that the effect of improving the rubber composition is not obtained and the mechanical strength can be reduced. From the viewpoint, it is preferably 20 to 30 parts by weight.

The rubber composition for an inner liner of the present invention is obtained by kneading and vulcanizing a rubber component and mica by a conventional method. The conditions and methods of kneading and vulcanization can be appropriately selected by those skilled in the art as long as the effects of the present invention are not impaired.

The rubber composition for an inner liner of the present invention contains a filler such as carbon black and calcium carbonate, a tackifier, as long as the effects of the present invention are not impaired.
It may contain vulcanizing agents such as stearic acid, zinc white and sulfur, vulcanization accelerators, process oils and the like.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

[0019]

Example 1 A mixture was obtained by kneading at a mixing ratio shown in Table 1 using a 1.7 L Banbury manufactured by Kobe Steel Ltd. at 150 ° C. for 4 minutes. Then, 1.5 parts by weight of sulfur and 1.0 part by weight of a vulcanization accelerator were added to the obtained kneaded material, and the mixture obtained by kneading the mixture at 80 ° C. for 4 minutes using a biaxial roller was heated at 170 ° C. After vulcanization under the conditions of 10 minutes, a rubber composition 1 for an inner liner of the present invention was obtained.

In Table 1, SBR1500 manufactured by Sumitomo Chemical Co., Ltd. was used as SBR, N660 manufactured by Mitsubishi Chemical Corporation was used as carbon black, Diana Process PS32 manufactured by Idemitsu Kosan Co., Ltd. Success calcium 20 manufactured by Omi Chemical Co., Ltd.
OS, SP10 manufactured by Nippon Shokubai Co., Ltd. as a tackifier
68, paulownia made by NOF Corporation as stearic acid, Ginrei R made by Toho Zinc Co., Ltd. as zinc flower, sulfur made by Tsurumi Chemical Co., Ltd. as sulfur, and Sanshin Chemical as vulcanization accelerator Suncellar CM (N-cyclohexyl-)
2-benzothiazyl-sulfenamide) was used.

As the plate-like mica, Sericite TK-S8 (average particle diameter: 15 μm, aspect ratio: 70, composition: SiO
₂ 45.8% by weight, Al ₂ O ₃ 35.4% by weight, Fe ₂
1.75% by weight of O _{3 and} 9.1% by weight of K ₂ O) were used.

[Evaluation] The obtained rubber composition was evaluated by the following method. The evaluation results are shown in Table 1.

The rubber composition having the measured air permeation is cut to have a diameter of 90 mm and a thickness of 1 m.
m sample was prepared and ASTM D-1434-75
M, the air permeability was measured, and the air permeability coefficient (1
^0-11 cc · cm / cm ² · sec · cmHg) was calculated. For the measurement, a constant temperature gas permeability measuring device M-C1 manufactured by Toyo Seiki Seisaku-sho, Ltd. was used.

Tensile test An evaluation was made using a dumbbell-shaped No. 3 shape based on JIS K6251.

A sample was prepared based on the bending crack test JIS K6260, and
Evaluation was performed by giving 0% strain and 70% strain.

From the rubber composition obtained by air leaking , a 175/70
After making a R13 tire and assembling the rim,
The pressure was set at 0 kPa, and the container was placed in an oven at 80 ° C. for one week, and the decrease in internal pressure was indicated as an index. The higher the index, the better the internal pressure holding performance (note that the gauge of the inner liner was the same in all Examples and Comparative Examples).

Machine durability After placing the tire in an oven at 80 ° C. for one week, the internal pressure is 200 kPa, the load is 340 kgf, and the speed is 80 km / h.
After traveling 30,000 km, the degree of damage to the inner liner was confirmed. If no cracks occurred,
When a crack occurred, it was evaluated as x.

Examples 2 and 3 The rubber compositions 2 and 3 for the inner liner of the present invention were prepared in the same manner as in Example 1 except that the mixing ratio shown in Table 1 was changed.
Then, evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Examples 1 and 2 Comparative inner liner rubber compositions 2 and 3 were obtained in the same manner as in Example 1 except that the mixing ratios were changed as shown in Table 1, and evaluation was performed in the same manner as in Example 1. Was. Table 1 shows the results
Shown in

Example 4 As a mica, LPK manufactured by Foram Co. (average particle size: 15 μm)
m, aspect ratio: 50, composition: 45.8% by weight of SiO ₂ , 35.4% by weight of Al ₂ O ₃ , 1.75% of Fe ₂ O ₃
Wt.%, K ₂ O is 9.1 wt.%) Except that the rubber composition 4 for the inner liner of the present invention was obtained in the same manner as in Example 3 and evaluated in the same manner as in Example 1. Done. Table 1 shows the results.

Comparative Examples 3-5 As mica, W1 manufactured by Foram (average particle size: 15 μm)
m, aspect ratio: 50, composition: 45.8% by weight of SiO ₂ , 35.4% by weight of Al ₂ O ₃ , 1.75% of Fe ₂ O ₃
%, K ₂ O is 9.1% by weight) (Comparative Example 3) or TK-S6 manufactured by Foram (average particle size: 15 μm).
m, aspect ratio: 50, composition: 45.8% by weight of SiO ₂ , 35.4% by weight of Al ₂ O ₃ , 1.75% of Fe ₂ O ₃
Wt.%, K ₂ O is 9.1 wt.%) (Comparative Example 4), or mica was not used (Comparative Example 5).
Rubber compositions 3 to 5 for comparison inner liners were obtained in the same manner as in Example 2, and evaluated in the same manner as in Example 1. Table 1 shows the results.

[0032]

[Table 1]

[0033]

According to the present invention, a rubber composition for an inner liner having excellent rubber properties and low air permeability can be obtained.

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[Procedure amendment]

[Submission date] November 25, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (1)

[Claims] 1. An inner liner rubber composition comprising 100 parts by weight of a rubber component and 10 to 50 parts by weight of mica having a plate-like aspect ratio of 50 to 50.