KR100717638B1 - Synthetic rubber based cement composition for tire - Google Patents

Abstract

The present invention relates to a synthetic rubber-based tire cement composition to be applied during tread extrusion, which is excellent in adhesion and can improve appearance quality. More particularly, the present invention is applied to the end and bottom of an extrudate when extruding a tread in an extrusion process. It is a cement composition for improving adhesion with other parts in the molding process, and does not contain carbon black, so that color lines are not contaminated even when over-coated, and suitable for application to tire treads made of high content of styrene and silica rubber composition. A rubber based cement composition.

Synthetic Rubber Tire Cement Composition, Adhesion, Adhesion, Tread Rubber

Description

Synthetic rubber based cement composition for tire}

The present invention relates to a synthetic rubber-based tire cement composition to be applied during tread extrusion, which is excellent in adhesion and can improve appearance quality. More particularly, the present invention is applied to the end and bottom of an extrudate when extruding a tread in an extrusion process. It is a cement composition for improving adhesion with other parts in the molding process, and does not contain carbon black, so that color lines are not contaminated even when over-coated, and suitable for application to tire treads made of high content of styrene and silica rubber composition. A rubber based cement composition.

The cement composition used in the tire manufacturing process is applied to the end and the lower end of the tread extrudates when the tire tread is extruded, and the application of the cement composition prevents the tread joints from spreading and the other parts of the tire (for example, For example, it is possible to improve adhesion and adhesion to the belt), and consequently, to improve the uniformity and durability of the final tire.

In recent years, as the passenger car tire requires high performance and high quality, many rubbers containing synthetic rubber and oil having high styrene content are used in the tread rubber composition. When the existing natural rubber-based cement composition is used as the cement composition in the extrusion of the tread made of such a tread rubber composition, the tip and bottom portions of the tread extrudate are reduced due to the decrease in compatibility between the synthetic rubber in the tread rubber composition and the natural rubber in the cement composition. The natural rubber-based cement applied to the adhesive decreases in adhesive strength, causing separation between rubber interfaces during molding, resulting in quality problems.

In other words, the existing natural rubber cement composition is manufactured using a refined heavy naphtha system as a natural rubber and resin, a vulcanizing agent and a vulcanization accelerator, and a solvent, and the natural rubber cement composition is a conventional synthetic rubber for tread. For the styrene content of less than 30%, there was no significant problem in the adhesion before molding, but for synthetic rubbers containing more than 30% of the styrene content or oils, the adhesion before vulcanization dropped significantly, especially as time passed. The adhesive force was lowered to about one third or less as compared with the initial molding, so that the separation occurred between the tire tread portion and the rubber interface of the cement applied to the tire during molding.

In addition, the conventional cement composition was prepared by dissolving rubber in a solvent in order to exhibit adhesive strength, but also by containing carbon black in the composition, the color of the cement composition becomes black, so that the color line of the adhesive portion when the cement composition is over-coated Appearance deteriorated.

Japanese Patent Laid-Open Publication No. 5-170975 discloses a technique related to a splice cement composition, wherein rubber having a styrene content similar to that of tread rubber, white carbon, and organosilicon compounds are incorporated into a cement composition to improve adhesion to a tread joint. Keep it. However, this technique has a problem of causing a decrease in the green adhesive force when molding the pre-vulcanizing tread rubber.

In Korean Patent Publication No. 2002-84990, a natural rubber cement composition is disclosed. However, this cement composition is a joint part of the tread part and the cement during the molding operation due to the low adhesive strength when applied to a tread mainly composed of synthetic rubber having a high styrene content. Separation occurs, and thus reworking the cement coating must be frequently performed, there is a problem that the operator avoids use.

An object of the present invention is to improve the above problems, by optimizing the content of the binder in the cement composition, that is, the ratio of natural rubber and synthetic rubber, to maintain the adhesive force when applied to the tread made of synthetic rubber rubber during molding It is to provide a tire cement composition which can improve the labor intensity and the productivity of molding work by eliminating the separation between the interfaces and reworking the cement coating, and improving the quality as adhesive strength is maintained even after a certain time. In addition, it does not contain carbon black and has a transparent property by preparing a composition by master batching rubber and other chemicals, thereby providing a synthetic rubber-based tire cement composition which can improve appearance quality without contaminating color lines even when over-coating. will be.

Synthetic rubber-based tire cement composition according to the present invention, which is applied at the time of tire tread extrusion, has a binder composition of 5.5-7.0% by weight, resin 1.5, which is composed of a weight ratio of natural rubber and synthetic rubber of 10-30: 90-70 in 100% by weight of the total composition. ~ 3.0% by weight, vulcanizing agent 0.3 to 0.7% by weight, vulcanization accelerator, characterized in that it comprises a 0.3 to 0.7% by weight and the remaining amount of the solvent.

The natural rubber and the synthetic rubber used in the cement composition of the present invention is not particularly limited in its kind, and preferably, the synthetic rubber is composed of the same type of rubber as the synthetic rubber mainly used for tire tread, and the tread rubber and cement composition. Since compatibility with the rubber in this can be improved, it is preferable to use, for example, emulsion-polymerized styrene-butadiene rubber having a high styrene content.

In the cement composition of the present invention, if the blending ratio of the natural rubber is less than 10, the adhesive strength is lowered, and if it exceeds 30, it is not preferable because the separation between the rubber interface during the molding operation occurs.

In the cement composition of the present invention, when the content of the binder is less than 5.5% by weight, sufficient chemical bonding at the rubber interface is not achieved, and thus the rubber interface strength is lowered. This occurs and is not desirable.

In the cement composition of the present invention, the resin may be KPT-1250, KPA-1509K, KPA-1350, or the like, which is an adhesive of an alkylphenol-formaldehyde resin system. If not more than 3.0% by weight, workability and dispersibility may decrease, which is not preferable.

In the cement composition of the present invention, a mixture of cyclohexane, n-hexane, and the like, which is a hydrocarbon-based organic solvent, can be used, and in particular, it is preferable to use a refined heavy naphtha solvent.

The vulcanizing agent and the vulcanization accelerator used in the cement composition of the present invention are not particularly limited in kind. Preferably, sulfur is used as the vulcanizing agent, and CZ-based vulcanizing accelerator may be used as the vulcanizing accelerator. If the content of the vulcanizing agent and the vulcanization accelerator is outside the range of 0.3 to 0.7% by weight, respectively, it is not preferable because the strength of the rubber interface decreases due to insufficient chemical bonding to the rubber interface after vulcanization.

In addition to the above components, the rubber cement composition of the present invention may be formulated with conventional additives added to a general cement composition in a usual amount of use.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Examples and Comparative Examples

Cement compositions of Examples and Comparative Examples were prepared according to the composition of Table 1 below, the component analysis and physical properties were measured, and the results are shown in Table 1 together.

Table 1

Unit: weight%

Item Comparative example Example bookbinder 6.0 (Natural rubber sole) 6.0 (natural rubber: synthetic rubber ¹⁾ = 20: 80) Resin ²⁾ 2.0 3.0 Vulcanizing agent (sulfur) 0.5 0.5 Vulcanization accelerator (Cz type) 0.5 0.5 Carbon black 5 - Solvent ³⁾ 86 90 Solid content (%) 7.55 8.45 Ash content (%) Trace Trace Specific gravity (g / cm 3) 0.73 0.75 Viscosity (sec) 8.5 10.54 color black Pale yellow

Notes: 1) Synthetic rubber-Emulsion-polymerized styrene-butadiene rubber with 45% styrene content containing 37.5% by weight of oil

    2) KPT-1250 (Kolon Emulsifier), an resin-alkylphenol-formaldehyde-based adhesive

    3) Solvent-Naphtha solvent (composed of mixture of cyclohexane, hydrocarbon and aliphatic hydrocarbon)

In order to grasp the adhesion and adhesion properties of the cement composition of the Examples and Comparative Examples, the results of the test according to ASTM standards are shown in Table 2.

TABLE 2

Item Comparative example Example 1. Adhesion (kgf / cm) Gayu I Initial 1 day 3 days 6 days 8.51 6.73 5.98 3.95 11.49 10.35 8.73 6.88 2. Adhesive force (kgf / cm) After vulcanization 4 hours 3 days 5 days 7 days No specimen destruction No specimen destruction No specimen destruction No specimen destruction No specimen destruction No specimen destruction No specimen destruction No specimen destruction

As can be seen from the above, the synthetic rubber-based cement composition of the present invention showed an improvement in adhesive strength of about 35% in comparison with the pre-vulcanizing adhesive force compared to the conventional natural rubber-based cement composition, the adhesion retention time over the existing natural rubber system It has been shown to be about 2 times better than the cement composition. In addition, cement rework did not occur due to the decrease in adhesion, and the result of evaluation of adhesion showed the same result without specimen destruction like natural rubber cement composition. This has the effect of preventing separation at the joint with the tread using the rubber with increased styrene content and silica content, and the color of the cement composition is pale yellow so that the color of the tread joint is not contaminated even when the tread joint is overcoated. Has the effect of improving.

Claims (4)

In 100 wt% of the total composition, 5.5 to 7.0 wt% of a binder composed of a weight ratio of natural rubber to synthetic rubber of 10 to 30:90 to 70, resin 1.5 to 3.0 wt%, vulcanizing agent 0.3 to 0.7 wt%, vulcanization accelerator 0.3 to A tire cement composition comprising 0.7 wt% and the remaining amount of solvent. The tire cement composition of claim 1, wherein the synthetic rubber is an emulsion polymerized styrene-butadiene rubber. The tire cement composition of claim 1, wherein the resin is an alkylphenol-formaldehyde-based resin. The tire cement composition according to claim 1, wherein the solvent is a hydrocarbon solvent or a heavy naphtha solvent.