JPH11198606A - Tire for road roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire for use on a road roller improved in oil swelling resistance and cutting resistance without damaging its low heat build-up property. SOLUTION: This tire for use on a road roller is made up of a rubber composition formed by blending 30 to 70 parts by weight of softening agent with 100 parts by weight of rubber component including the ternary copolymer of styrene-acrylonitrile-butadiene manufactured by the emulsion polymerization of styrene content of 15 to 50%, acrylonitrile content of 2 to 10% and butadiene content of 40 to 83%, and is formed by constituting at least a cap tread section out of cap tread, under tread and side sections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road roller tire having improved oil swelling resistance and cut resistance without impairing low heat build-up.

[0002]

2. Description of the Related Art In a tire for a road roller used for road construction or the like, light oil or the like is sprayed on the tire surface in order to prevent asphalt from adhering to the tire surface when asphalt is paved. There is a problem that the tread portion and the side portion of the tire swell in oil.
When the tread oil swells, the shape of the tread tread changes, and the tire shape during tire rotation becomes uneven,
Road surface smoothing work becomes difficult.

[0003] In addition, the road roller tire has a problem that a tread portion and / or a side portion is cut by a stone or the like at the time of leveling a road surface, resulting in damage to the tire. When the oil swells as described above, the hardness of the tread portion and the side portion is reduced, so that the cut flaw further grows. Therefore, the tire for a road roller is required to have not only oil swelling resistance but also cut resistance for preventing a tread portion and / or a side portion from being cut. Furthermore, since the tire for a road roller is used at a considerably high temperature such as in contact with high-temperature asphalt, it is also important that the tire generate low heat.

Conventionally, tires for road rollers include general-purpose styrene-butadiene copolymer rubber (styrene content of 2%).
3.5%) or a styrene-butadiene copolymer rubber with a high styrene content (styrene content 25-60%)
(Japanese Unexamined Patent Publication No. H2-242835). However, in these cases, oil swelling resistance, cut resistance, and low heat generation were not entirely satisfactory.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a tire for a road roller having improved oil swelling resistance and cut resistance without impairing low heat build-up.

[0006]

SUMMARY OF THE INVENTION The tire for a road roller of the present invention has a styrene content of 15 to 50%, an acrylonitrile content of 2 to 10%, and a butadiene content of 40 to 83.
% Of a rubber component containing a styrene-acrylonitrile-butadiene terpolymer produced by an emulsion polymerization method of 100%
Parts by weight, a rubber composition comprising 30 to 70 parts by weight of a softener, a cap tread, an undertread,
And at least a cap tread of the side portions.

[0007] Since at least the cap tread is constituted by the rubber composition as described above, the above object can be achieved. Here, “%” means weight% (hereinafter, “%”).
the same).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber composition used in the present invention comprises a rubber component containing a styrene-acrylonitrile-butadiene terpolymer and a softener. The rubber component may contain a rubber other than the styrene-acrylonitrile-butadiene terpolymer. The other rubber may be any rubber, for example, natural rubber, polyisoprene rubber, polybutadiene rubber, diene rubber such as styrene-butadiene copolymer rubber, or a mixture of two or more thereof Can be mentioned.

The styrene-acrylonitrile-butadiene terpolymer has a styrene content of 15 to 50%, an acrylonitrile content of 2 to 10%, preferably 2 to 8%, and a butadiene content of 40 to 83%. If the styrene content is less than 15%, the effect of improving the oil swelling resistance is small, and sufficient cut resistance cannot be obtained. Styrene content 50
%, It is not preferable because heat generation increases and workability deteriorates.

[0010] When the acrylonitrile content is less than 2%, the oil swelling resistance is not sufficiently improved. Acrylonitrile content 8
If it exceeds 10%, the exothermicity of the obtained rubber composition becomes large. In particular, if it exceeds 10%, the exothermicity of the obtained rubber composition becomes even greater. If the butadiene content is less than 40%, the styrene content or the acrylonitrile content becomes large, which is not preferable in terms of heat buildup. If it exceeds 83%, the effect of improving oil swelling resistance and cut resistance is small, which is not preferable.

The styrene-acrylonitrile-butadiene terpolymer is a random copolymer produced by an emulsion polymerization method. The softener may be one commonly used as a softener in the rubber industry, for example, an oil or a plasticizer. Examples of the oil include tall oil, aromatic oil, and process oil. As the plasticizer, for example, DBP, DHP, DOP, DID
P and the like.

The amount of the softener is 30 to 70 parts by weight based on 100 parts by weight of the rubber component. When the amount is less than 30 parts by weight, the effect of improving the oil swelling resistance is not sufficient. On the other hand, when the amount is more than 70 parts by weight, the oil swelling resistance is improved, but the heat generation is deteriorated and the appearance is also deteriorated. As described above, a compounding agent such as sulfur or carbon black can be appropriately compounded in the rubber composition comprising the rubber component and the softening agent, if necessary.

In the present invention, the rubber composition constitutes at least the cap tread of the cap tread, the undertread, and the side portions. Of the cap tread, under tread, and the side portion, the portion that is most easily swelled with oil, and the portion that is most susceptible to cut damage is the cap tread, so that at least the cap tread among these three portions is made of the rubber composition. It was done. If both the cap tread and the undertread are composed of the rubber composition, the entire tread portion is composed of the rubber composition.

[0014]

EXAMPLE According to the composition (parts by weight) shown in Table 1, a vulcanization accelerator, a raw rubber excluding sulfur, and a compounding agent were mixed in a 1.7 liter Banbury mixer for 5 minutes, and then the mixture was vulcanized. The accelerator and sulfur were added and kneaded with an 8-inch test kneading roll machine for 4 minutes to obtain a rubber composition. These rubber compositions were press-vulcanized at 150 ° C. for 30 minutes to prepare test specimens, and their physical properties (oil swelling resistance, cut resistance, heat generation) were measured and evaluated as follows. Table 1 shows the results.

Oil swelling resistance : A test piece was immersed in JIS # 1 oil for 2 days based on the immersion test method of JIS ^K6301-1975 , and the change rate of the test piece volume after immersion with respect to the test piece volume before immersion was calculated. The rate of change was represented by an index when Comparative Example 2 was set to 100. The smaller the index value, the smaller the rate of change and the better the oil swelling resistance.

Cut resistance : A test piece was immersed in JIS # 1 oil for 2 days in accordance with JIS ^K6301-1975, and the hardness of the test piece after immersion for 2 hours was measured (this hardness was also measured according to JIS). ^K6301-1975 ) and 1 in Comparative Example 2.
The hardness was represented by an index when it was set to 00. The higher the hardness after immersion, the better the cutability. Therefore, the larger the index value, the better the cut resistance.

Exothermicity : Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho, elongation, strain rate 10 ± 2%, frequency 2
It was determined from the value of tan δ measured at 60 ° C. under the condition of 0 Hz. The rate of change was represented by an index when Comparative Example 2 was set to 100. The smaller the index value, the smaller the tan δ and the smaller the heat buildup.

[0018]

[Table 1]

Note) * 1 Nipol 1502 (manufactured by Zeon Corporation), styrene content 23.5%, acrylonitrile content 0%, butadiene content 7
6.5%. * 2 Prototype styrene-butadiene copolymer rubber, styrene content 40%, acrylonitrile content 0%, butadiene content 6
0%.

* 3 Nipol 1042 (Zeon Corporation)
Manufactured), styrene content 0%, acrylonitrile content 33%, butadiene content 67%. * 4 Terpolymer prepared by emulsion polymerization of styrene / acrylonitrile / butadiene, styrene content 3
0%, acrylonitrile content 5%, butadiene content 65%.

* 5 Ternary copolymer experimentally produced by emulsion polymerization of styrene / acrylonitrile / butadiene,
Styrene content 18%, acrylonitrile content 5%, butadiene content 77%. * 6 Tertiary copolymer produced by the emulsion polymerization method of styrene / acrylonitrile / butadiene, styrene content 1
5%, acrylonitrile content 15%, butadiene content 70
%.

* 7 Show Black N339 (manufactured by Showa Cabot Co., Ltd.). * 8 N-1,3-dimethylbutyl-N′-phenyl-
p-phenylenediamine. * 9 N-cyclohexyl-2-benzothiazole-sulfenamide.

As is apparent from Table 1, Examples 1 and 2 related to the rubber compositions comprising the ternary copolymer within the scope of the present invention.
Has excellent oil swelling resistance and low heat generation. On the other hand, when the amount of acrylonitrile is high in the ternary copolymer, heat generation is increased as in Comparative Example 6, which is not preferable. Further, when the oil amount is lower than 30 parts by weight even when the ternary copolymer in the range of the present invention is used, although heat generation is excellent as in Comparative Example 4, improvement in oil swelling resistance cannot be expected. On the other hand, when the oil amount is more than 70 parts by weight, the heat generation becomes too high as in Comparative Example 5, which is not preferable. SB
When R and NBR are blended, heat generation is high as shown in Comparative Example 3. When only commercially available SBR is used as the rubber component, as shown in Comparative Example 1, the oil swelling resistance and the cut resistance are poor.

[0024]

As described above, according to the present invention, the styrene content is 15 to 50% and the acrylonitrile content is 2 to 1%.
0%, and 100 parts by weight of a rubber component containing a styrene-acrylonitrile-butadiene terpolymer produced by an emulsion polymerization method having a butadiene content of 40 to 83%,
A rubber composition comprising 30 to 70 parts by weight of a softener,
Provided is a road roller tire that has improved oil swelling resistance and cut resistance without compromising low heat build-up because at least the cap tread of the cap tread, under tread, and side portions of the road roller tire is configured. be able to.

Claims (3)

[Claims] 1. A styrene content of 15-50%, an acrylonitrile content of 2-10%, and a butadiene content of 40-8.
Rubber component 10 containing styrene-acrylonitrile-butadiene terpolymer prepared by 3% emulsion polymerization
A road roller tire comprising at least a cap tread, an undertread, and a side portion of a rubber composition comprising 30 to 70 parts by weight of a softener with respect to 0 parts by weight. 2. The road roller tire according to claim 1, wherein the acrylonitrile content is 2 to 8%. 3. The road roller tire according to claim 1, wherein the softener is an oil or a plasticizer.