KR101397298B1 - Tire tread rubber composition having improved wear resistance - Google Patents

Abstract

The present invention relates to a rubber composition for truck and bus tire treads, and more particularly to a rubber composition for truck and bus tire treads, which is capable of improving the abrasion properties and cutting and chipping of trucks and bus tires, And to rubber compositions for bus tire treads.

Description

Technical Field [0001] The present invention relates to a tire composition for a truck and a bus tread having improved abrasion resistance,

The present invention relates to a rubber composition for truck and bus tire treads, and more particularly to a rubber composition for trucks and bus tire treads that improves the abrasion properties and cutting & chipping of tires for trucks and buses traveling on packaged and unpaved trucks. And to rubber compositions for bus tire treads.

Conventionally, in order to improve the abrasion resistance and tearing phenomena of trucks and bus tires running on packed and unpaved roads, an emulsion-polymerized styrene-butadiene rubber (E-2) having a styrene content of 12 to 24% by weight, which is an isotropic rubber together with natural rubber or butadiene rubber, SBR) is mixed with natural rubber. In general rubber composition ratios, it is common practice to use 30 to 100 parts by weight or 0 to 70 parts by weight of emulsion-polymerized styrene-butadiene rubber per 100 parts by weight of natural rubber or butadiene rubber in order to improve abrasion performance. Styrene-butadiene rubber is superior to natural rubber in terms of heat aging characteristics and shows high hardness in the range of low deformation. Therefore, it has a great cutting resistance and is advantageous in tearing due to isotropic characteristics.

However, as the use amount of styrene butadiene rubber increases, tear strength and heat generation characteristics as well as tensile properties increase, which makes it difficult to apply to tread rubber for truck and bus tires. In addition, emulsion polymerized styrene butadiene rubber has relatively high tensile strength due to its high molecular weight compared to solution polymerized styrene butadiene rubber, but has relatively low tear strength. In order to increase the tear energy value, 5 to 15 parts by weight of silica may be used, but the effect is relatively limited. In addition, considering the fact that the phenomenon of tire cutting and tearing on the road surface is a composite phenomenon, tire wear for trucks and buses traveling together with packing and unpacking should reflect not only the composition but also the physical properties thereof, but there is no accurate standard therefor.

U.S. Patent Application Publication No. 2006-026645 discloses that an emulsion polymerized styrene butadiene rubber having a styrene content of 12 to 16% and a glass transition temperature of -70 to 60 ° C is mixed with natural rubber, 2004-0177907 discloses the use of 5 to 30 parts by weight of a high trans-emulsion styrene-butadiene rubber, 15 to 30 parts by weight of silica and 20 to 40 parts by weight of carbon black in natural rubber and butadiene rubber, Both inventions improved the abrasion performance of trucks and bus tires, but there is no improved example of tearing.

Therefore, it is necessary to develop a technique for improving wear resistance performance and tearing phenomenon of the tire.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the problems of the prior art as described above, and it is an object of the present invention to provide a rubber composition comprising a mixture of an aliphatic resin and an aromatic resin and carbon black to raw rubber composed of natural rubber and solution polymerized styrene butadiene rubber, The present invention provides a rubber composition for a tire tread having improved resistance to cutting and tearing by improving physical properties of a tire tread rubber of a bus and a truck.

The rubber composition for a tire tread according to the present invention comprises 2 to 10 parts by weight of a mixture of an aliphatic resin and an aromatic resin and 40 to 60 parts by weight of carbon black with respect to 100 parts by weight of a raw rubber composed of a natural rubber and a solution polymerized styrene butadiene rubber .

In the rubber composition for a tire tread according to the present invention, the mixing ratio of the natural rubber and the solution-polymerized styrene-butadiene rubber constituting the raw material rubber is not particularly limited, and is preferably 1: 99 to 99: 1, for example.

In the rubber composition for a tire tread according to the present invention, the solution-polymerized styrene butadiene rubber (S-SBR) has a styrene content of 30 to 50 wt%, a vinyl content of 15 to 25 wt%, a glass transition temperature of -60 If the styrene content is less than 30% by weight or the vinyl content is less than 15% by weight, the resistance characteristic of the cutting property is deteriorated, and if the styrene content exceeds 50% by weight or the vinyl content If it exceeds 25% by weight, it may cause problems in compatibility with other rubbers, which is not preferable. The glass transition temperature (Tg), which is an important factor in the wear characteristics, depends on the styrene content and the vinyl content. Therefore, in order to maintain the glass transition temperature at -60 ° C to -25 ° C, the styrene content and the vinyl content And is preferably limited to the above range.

In the rubber composition for a tire tread according to the present invention, the mixture of aliphatic resin and aromatic resin (AAHR) is used for increasing the compatibility of the starting rubber, The mixing weight ratio is preferably from 2: 1 to 1: 2, because the mixing ratio is the most excellent in the above range.

The aliphatic resin used in the present invention is a C5 aliphatic hydrocarbon resin and may have a softening point of 98 to 120 ° C.

The aromatic resin used in the present invention may be a C9-based aromatic hydrocarbon resin or a petroleum resin and have a softening point of 90 to 130 ° C.

The amount of the mixture of the aliphatic resin and the aromatic resin is preferably 2 to 10 parts by weight based on 100 parts by weight of the raw rubber. If the amount is less than 2 parts by weight, the rubber compatibility may deteriorate, and if it exceeds 10 parts by weight, Molecular weight abrasion and physical property deterioration.

In the rubber composition for a tire tread according to the present invention, the carbon black has an iodine adsorption value of 100 to 130 mg / g and a dibutyl phthalate adsorption value of 80 to 120 ml / 100 g, and the content of the carbon black is 100 parts by weight If the amount is less than 40 parts by weight, the abrasion resistance is deteriorated. If the amount is more than 60 parts by weight, a phenomenon such as tearing may increase due to a decrease in hardness and elongation percentage, which is not preferable.

The rubber composition of the present invention may further comprise conventional additives added to conventional tread rubber compositions, such as common myth zinc, stearic acid, sulfur, and accelerators, wherein the zinc oxide content is in the range of about 100 parts by weight 1 to 3 parts by weight, and the content of the promoter may be 0.8 to 2.5 parts by weight based on 100 parts by weight of the raw rubber.

The rubber composition for a tire tread according to the present invention has a 300% tensile property value of 95 to 130 kgf / cm 2, a shore-A hardness of 62 to 65, and an elongation of 550% or more.

The tire according to the present invention has a tread portion made of the rubber composition for a tire tread according to the present invention.

According to the present invention, a processability problem can be solved by using a mixture of an aliphatic resin and an aromatic resin (AAHR) as a processing aid in order to enhance the compatibility of S-SBR having high styrene content and high vinyl content with natural rubber, Improving the dispersibility and increasing the tear strength, thereby improving the abrasion resistance and tearing characteristics of trucks and bus tires that are packaged and unpacked.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples. The following examples are only illustrative of the present invention and do not limit the scope of protection of the present invention.

Example  And Comparative Example

The tire tread rubber compositions of Examples and Comparative Examples were prepared according to the composition shown in the following Table 1, rubber specimens were prepared from each rubber composition, vulcanized at 160 캜, and the properties thereof were measured according to the ASTM standard. Respectively.

(Unit: parts by weight) Raw rubber Styrene content
(weight%) vinyl
content
(weight%) Glass transition temperature
(° C) AAHR ^{1 )}
content Comparative Example 1 Weight ratio of natural rubber / S-SBR = 60: 40 23.5 30 -52 - Comparative Example 2 Weight ratio of natural rubber / S-SBR = 60: 40 23.5 50 -36 5 Example 1 Weight ratio of natural rubber / S-SBR = 60: 40 30 15 -60 5 Example 2 Weight ratio of natural rubber / S-SBR = 60: 40 30 15 -60 3 Example 3 Weight ratio of natural rubber / S-SBR = 60: 40 40 25 -25 5 Example 4 Weight ratio of natural rubber / S-SBR = 60: 40 40 15 -50 3

Note 1) A mixture of aliphatic resin: aromatic resin = 1: 1 (manufactured by BASF)

Note 1) Modulus from stress-strain curve using Instron.

2) and 3) Obtain tensile strength and elongation at a rate of 250 mm / min.

4) and 5) Relative value based on T1. The higher the value, the better the abrasion resistance and cutting / chipping characteristics.

6) Based on ASTM D2663 method.

7) Based on ASTM D624 method using die C specimen.

As shown in Table 1, Comparative Example 1 in which the styrene content of the S-SBR was out of the range of the present invention and Comparative Example 1 in which the AAHR was not used and Comparative Example 2 in which the vinyl content was out of the range of the present invention It can be seen that Examples 1 to 4 of the present invention have improved abrasion resistance, increased cut / chip resistance index, and increased tear resistance. This is an effect of improving the dispersion and increasing the compatibility of the natural rubber and the synthetic rubber S-SBR. In particular, the tear resistance is improved by increasing the tear strength due to the increase of the styrene content of the S-SBR.

Claims (6)

Based on 100 parts by weight of a raw material rubber composed of a solution-polymerized styrene-butadiene rubber having a natural rubber and a styrene content of 30 to 50% by weight, a vinyl content of 15 to 25% by weight and a glass transition temperature of -60 to -25 占 폚, C5 aliphatic hydrocarbon resin having 98 to 120 deg. C: 2 to 10 parts by weight of a mixture of an aliphatic resin and an aromatic resin having a mixing weight ratio of C9 aromatic hydrocarbon resin having a softening point of 90 DEG C to 130 DEG C of 2: 1 to 1: 2 And 40 to 60 parts by weight of carbon black. The method according to claim 1,
Wherein the carbon black has an iodine adsorption value of 100 to 130 mg / g and an adsorption value of dibutyl phthalate of 80 to 120 ml / 100 g. The method according to claim 1,
Wherein the rubber composition for a tire tread has a 300% tensile property value of 95 to 130 kgf / cm 2, a Shore A hardness of 62 to 65, and an elongation percentage of 550% or more. A tire having a tread portion comprising the rubber composition for a tire tread according to any one of claims 1 to 3.
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