JPH10330540A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition adapted so as to give a product in which a constituent silicone oil slowly bleeds to its surface to keep its appearance always good or so as to give a product in which the constituent silicone oil and the constituent wax give good appearance and good ozone resistance by compounding a diene rubber with a specified amount of the silicone oil having a specified molecular weight and optionally wax. SOLUTION: The diene rubber component used is a natural rubber(NR), a butadiene rubber(BR), a styrene/butadiene copolymer rubber(SBR), a polyisoprene rubber(IR), an acrylonitrile/butadiene rubber or a blend thereof. The silicone oil is desirably one having a molecular weight of 1.0×10<4> -2.0×10<5> and a solubility parameter (SP value) of 7.0-12.0, is exemplified by dimethylsiloxane, phenylmethylsilicone oil or polyether-modified silicone oil and is used in an amount of 3-15 pts.wt. per 100 pts.wt. diene rubber In order to further improve the ozone resistance, 1-4 pts.wt. wax is added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition, and more particularly, to a rubber composition having improved rubber surface appearance. When the rubber composition of the present invention is used for a pneumatic tire, it is useful because a pneumatic tire having good appearance for a long period of time can be obtained.

[0002]

2. Description of the Related Art In general, a rubber composition used outdoors has an antiaging agent for preventing rubber aging and a wax for preventing generation of rubber cracks due to ozone. These compounding agents, such as antioxidants and waxes, have the problem that they gradually elute (bleed) and solidify on the surface of the rubber over a long period of use, resulting in deterioration of the appearance of the rubber surface.

Conventionally, as a method for improving the appearance of a rubber surface, (1) a method in which a specific p-phenylenediamine-based or quinoline-based antioxidant is blended (Japanese Patent Laid-Open No.
JP-A-144004) and (2) a method of specifying the amount of wax compounded in each layer by using a rubber as a multilayer structure. However, the method (1) does not provide sufficient appearance improvement, and the method (2) In the method (1), there is a problem that the production becomes complicated due to the multilayer structure.

[0004]

Accordingly, the present invention provides a rubber composition, particularly a rubber composition for a tire,
By blending a specific silicone oil, the blended silicone oil gradually bleeds and covers the rubber surface, so that the appearance is always kept in a good state. Another object of the present invention is to blend the silicone oil and wax into a rubber composition to achieve good appearance and ozone resistance.

[0005]

According to the present invention, a diene is used.
The molecular weight is 1.0 × 10 ^Four
~ 2.0 × 10^Five3 to 15 parts by weight of silicone oil
A compounded rubber composition (A) is provided. "Minute" here
"Molecular weight" means "weight average molecular weight".

According to the present invention, a diene rubber 10
The molecular weight is 1.0 × 10 ^{4 to} 2.0 ×
There is provided a rubber composition (B) containing 3 to 15 parts by weight of 10 ⁵ silicone oil and 1 part by weight or more of wax.

Further, according to the present invention, there is provided a pneumatic tire using the rubber composition of (A) or (B).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure, operation and effect of the present invention will be described below. In the present invention, in a diene rubber composition, particularly a rubber composition for a pneumatic tire, by mixing 3 to 15 parts by weight of a silicone oil having a molecular weight of 1.0 × 10 ^{4 to} 2.0 × 10 ⁵ , The compounded silicone oil bleeds and covers the rubber surface,
The feature is that the appearance is always kept in good condition. Since this silicone oil is blended with rubber, even if the silicone oil in the surface layer is removed, the silicone oil bleeds onto the surface one after another and has a good appearance forever. In addition, since silicone oil has a large surface tension, there is an advantage that water-soluble dirt is less likely to adhere.
There is also an advantage that the mold release property at the time of manufacturing a pneumatic tire or the like becomes good, and the application of a release agent used at the time of tire vulcanization becomes unnecessary.

[0009] The silicone oil has a molecular
1.0 × 10^Four~ 2.0 × 10 ^FiveIn the range of
Any type can be used. Only
And typically a Solubility Parameter
Those having an (SP value) of 7.0 to 12.0 are preferred. Siri
As corn oil, if it is in the above SP value range,
Dimethylpolysiloxane and phenylmethylsiloxane
Silicone oil, polyether modified silicone oil,
Alkyl-modified silicone oil, amino-modified silicone
Oil, amino / polyether modified silicone oil,
Higher fatty acid-containing silicone oil, carboxy-modified silicone
Corn oil, higher fatty acid modified silicone oil, etc.
used. The molecular weight of silicone oil is 1.0 × 10
^FourIn the following, the viscosity is low and the mixing workability deteriorates.
2.0 × 10^FiveAbove, hard to bleed, outside
The effect of improving the view is insufficient. In addition, silicone oil
If the amount is less than 5 parts by weight, the effect of improving appearance is insufficient.
If it is more than 15 parts by weight, the processability is remarkable.
descend.

[0010] In the rubber composition of the present invention, in order to further enhance the ozone resistance, wax is used in an amount of 1 part by weight or more, preferably 1 to 5 parts by weight.
Add 4 parts by weight. As such a wax, various waxes usually used for a rubber composition, for example, petroleum waxes such as paraffin wax and microcrystalline wax are used.

The diene rubber component used in the rubber composition according to the present invention includes, for example, natural rubber (NR), various butadiene rubbers (BR), various styrene-butadiene copolymer rubbers (SBR), polyisoprene rubber (I
R), acrylonitrile butadiene rubber, chloroprene rubber, ethylene-propylene-diene copolymer rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber, and the like. These diene rubbers can be used alone or as an arbitrary blend.

The rubber composition according to the present invention is blended with any carbon black and / or silica usually blended in the rubber composition. In addition, ordinary vulcanization or cross-linking agent, vulcanization or cross-linking accelerator, various oils, anti-aging agents, fillers, plasticizers, softeners, and other various additives that are generally compounded for general rubber Such a composition can be kneaded and vulcanized by a general method into a composition, and can be used for vulcanization or crosslinking. The amounts of these additives may be conventional general amounts, as long as the object of the present invention is not adversely affected.

The rubber composition of the present invention is useful as a rubber composition for a pneumatic tire, and can provide a pneumatic tire having excellent appearance over a long period of time while maintaining ozone resistance.

[0014]

EXAMPLES The present invention will be described in more detail below with reference to examples, conventional examples and comparative examples, but it goes without saying that the technical scope of the present invention is not limited to these examples.

The following commercial products were used as the silicone oils 1 to 5 used in the following Examples and Comparative Examples. Silicone oil-1: Silicone oil KF96
-100 (Shin-Etsu Chemical Co., Ltd.) Molecular weight 5.0 × 10 ³ Silicone oil-2: Silicone oil KF96
-300 (Shin-Etsu Chemical Co., Ltd.) Molecular weight 1.5 × 10 ⁴ silicone oil-3: silicone oil KF96
-1000 (Shin-Etsu Chemical Co., Ltd.) Molecular weight 2.5 × 10 ⁴ Silicone oil-4: Silicone oil KF96
−100,000 (Shin-Etsu Chemical Co., Ltd.) Molecular weight 1.6 × 10 ⁵ Silicone oil -5: Silicone oil KE76
BS (Shin-Etsu Chemical Co., Ltd.) Molecular weight 5.5 × 10 ⁶

The following commercially available products were used as the other components used in the following examples. NR (natural rubber): RSS # 1 BR (butadiene rubber): Nipol 1220 (Nippon Zeon Co., Ltd.) FEF CB (carbon black): N550 Diablack E (Mitsubishi Chemical Corporation) Zinc flower: Zinc flower 3 Stearin Acid: Industrial stearic acid Antioxidant: Antigen 6C (Sumitomo Chemical Co., Ltd.) Wax: Sunnock (Ouchi Shinko Chemical Co., Ltd.) Sulfur: Powdered sulfur Vulcanization accelerator: Noxeller DM (Ouchi Shinko Chemical Co., Ltd.) ))

Preparation of Sample The vulcanization accelerator and components other than sulfur were kneaded for 3 to 5 minutes in a 1.8-liter hermetic mixer, and the vulcanization accelerator was added to the masterbatch released when the temperature reached 165 ± 5 ° C. And sulfur were kneaded with an 8-inch open roll to obtain a rubber composition. The “roll workability” of the unvulcanized rubber during the roll kneading was evaluated. Next, the composition was press-vulcanized in a mold of 15 × 15 × 0.2 cm at 160 ° C. for 20 minutes to prepare a target test piece (rubber sheet), and the vulcanization property “300% Mo” was obtained.
d. "," T _B (breaking strength) "," E _B (elongation at break). "
And "Hs (hardness)", and "appearance" and "ozone resistance" were measured and evaluated.

The test methods for the unvulcanized and vulcanized properties of the rubber compositions obtained in the respective examples are as follows. 1) Roll workability: The workability of the unvulcanized rubber on a roll was evaluated as follows. …: Wrapping around the roll is good and processing can be performed without any problem. …: Processing with no problem although winding around the roll is slightly poor. Δ: winding on the roll is poor, and processing cannot be performed unless the back roll has a high roll rotation speed. ×: Level that is difficult to process because there is no winding around the roll. 2) 300% Mod. : Conforms to JIS K6251 (dumbbell shape No. 3). 3) T _B (breaking strength): based on JIS K6251 (dumbbell shape No. 3). 4) E _B (elongation at break): based on JIS K6251 (dumbbell shape No. 3). 5) Hs (hardness): based on JIS K6258. 6) Appearance: The rubber composition vulcanized sheet was left indoors for about 2 months, and the appearance after leaving was visually judged. Judgment was made with numerical values in five stages, and the larger the numerical value, the better the appearance. 7) Ozone resistance: Based on JIS K6259. Temperature 50
The ozone crack was evaluated after standing at 72 ° C. for 72 hours at 100 ° C., an ozone concentration of 100 PPHM, and an elongation of 20%. The alphabet indicates the number of cracks, the numerical value indicates the size and depth of the crack, and A1 → C
The order of 5 indicates that the ozone resistance is poor. In addition, K is a case where it has broken.

Conventional Examples, Examples 1 to 8 and Comparative Examples 1 to 7 These examples show a rubber composition obtained by blending (1) silicone oil-1 to 5 with each NR / BR rubber, and (2) 3 shows the evaluation results of a rubber composition containing wax. The results are shown in Table I below.

[0020]

[Table 1]

[0021]

[Table 2]

The following can be understood from Table I. When the silicone oil having a molecular weight of less than the specified value is blended as in Comparative Examples 1 and 2, the roll processability is deteriorated, and as in Comparative Examples 5 and 6, the silicone oil has a molecular weight greater than the specified value. It is understood that the effect of improving the appearance is poor when the compound is added. In addition, when the amount of the silicone oil is less than the specified value, the effect of improving the appearance is poor, and when the amount of the silicone oil is more than the specified value, the roll processability is poor. Further, as in Comparative Example 7, a rubber composition in which no wax was blended in the conventional rubber composition (a silicone oil was not blended) also showed that the ozone resistance was very poor. On the other hand, in Examples 1 to 8 in which a predetermined amount of the silicone oil having a predetermined molecular weight of the present invention was blended, the roll processability was △ or more, and the appearance and ozone resistance were more than those of the comparative sample. It can be seen that it has improved.

[0023]

As described above, according to the present invention,
Improving the appearance and ozone resistance of the rubber composition after vulcanization without significantly deteriorating the roll processability of the rubber composition when unvulcanized by blending a predetermined amount of silicone oil having a predetermined molecular weight. When a predetermined amount of wax is further added to the composition, the ozone resistance can be further improved. Therefore, the rubber composition of the present invention is extremely useful for a rubber composition for a pneumatic tire.

Claims (3)

[Claims] Claims 1. A 100 parts by weight of a diene rubber,
Child size is 1.0 × 10 ^Four~ 2.0 × 10^FiveSilicone
Rubber set containing 3 to 15 parts by weight of il
Adult. 2. The composition further comprises 1 part by weight or more of wax.
The rubber composition according to claim 1. 3. A pneumatic tire using the rubber composition according to claim 1.