KR20090046427A - Rubber composition for summer tire tread - Google Patents

Abstract

The present invention relates to a summer tire tread rubber composition, wherein the summer tire tread rubber composition has a condensation point of 44.4 ° C. to 61.4 ° C. and has n-paraffinic, cyclic paraffinic and aromatic containing paraffinic compounds having 22 to 28 carbon atoms. Microcapsules containing one or more phase change material selected from the group consisting of 1 to 25 parts by weight based on 100 parts by weight of the raw material rubber.

According to such a rubber composition by using a phase change material to reduce the temperature rise of the summer tire tread portion can improve the running performance while maintaining the wear resistance.

Summer Tire * Tread * Drive * Phase Transfer

Description

Rubber composition for summer tire tread}

The present invention relates to a summer tire tread rubber composition, and more particularly, to a summer tire tread rubber composition having improved running performance on wet and dry road surfaces while maintaining wear resistance.

Hardness and running performance are closely related to summer tires. In general, when the hardness increases, the driving performance is improved, and when the hardness is low, the driving performance tends to be lowered. In the summer tire, the temperature of the tire tread portion is increased during driving, which has a fundamental problem of lowering the running performance by lowering the hardness of the tire tread portion.

 As a countermeasure for improving and improving the driving performance in the conventional summer tire, a polymer material having a high glass transition temperature was used because the amount of the reinforcing agent in the rubber composition of the summer tire was increased or the styrene content or the vinyl content was high.

However, increasing the amount of reinforcing agent not only adversely affects the workability, but also causes performance problems.

Therefore, efforts have been made to improve the driving performance without using such a method.

Recently, silica compounds have been used in treads to improve running performance on wet roads. Silica compounds can be very useful for improving and improving running performance on wet roads, but have a very detrimental effect on wear resistance. In addition, the cost has a very high disadvantage compared to the carbon black compound, and did not show a distinct advantage in the driving performance and steering performance on dry road surface.

As another conventional technique, a technique for improving driving performance while providing excellent braking performance on wet and dry roads is disclosed in Korean Patent Laid-Open Publication No. 2002-37596, wherein the structure of the tire tread is moved from the shoulder to the inside. By dividing into several sites satisfying specific physical properties, a tread composed of a rubber composition having a compound and physical properties suitable for each performance is provided.

However, even when rubber having different properties inwardly from the shoulder portion is formed, it is difficult to satisfy the running property on various road surfaces, and the work in the extrusion process is complicated and the change of equipment is inevitable, resulting in a cost increase and a decrease in productivity.

The above-mentioned prior arts have tried to improve the driving performance by changing the addition amount of the rubber composition, but could not solve the fundamental problem of deterioration of the driving performance due to the hardness decrease due to the temperature rise of the tire tread portion during the driving.

The present invention was created to solve the above problems, by using a microcapsule containing a phase change material to prevent the rise of the temperature of the tire tre at a high temperature to maintain abrasion resistance while driving performance on wet and dry road surface It is an object to provide a summer tire tread rubber composition that can be improved.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. Furthermore, the objects and advantages of the present invention can be realized by means and combinations indicated in the claims.

The summer tire tread rubber composition according to the present invention has at least one phase transition selected from the group consisting of n-paraffinic, cyclic paraffinic, and aromatic-containing paraffinic compounds having a raw material rubber and a condensation point of 44.4 ° C to 61.4 ° C and having 22 to 28 carbon atoms. Microcapsules containing materials.

Here, the microcapsules are preferably contained in 1 to 25 parts by weight based on 100 parts by weight of the raw rubber.

In addition, the microcapsules are composed of one or more cells, the phase transition material may form a core inside the cell, the cell is selected from the group consisting of acrylic ester monomers, aromatic vinyl monomers, vinyl cyanide monomers and maleimide monomers It is preferred to be made of at least one monomer.

Summer tire tread rubber composition according to the present invention comprises a raw material rubber and microcapsules.

The raw material rubber mainly uses styrene-butadiene rubber in order to maintain braking performance and running performance, which is a required performance of summer tires, and may be used by adding a part of natural rubber and butadiene rubber to compensate for abrasion resistance and rolling resistance. Do.

Hereinafter, the microcapsules according to the present invention will be described in more detail.

The microcapsule is a phase change material (commonly referred to as 'PCM') is a thermal energy from the solid phase to the liquid phase, or from the liquid phase to the gas phase or vice versa without changing the temperature in a certain temperature range It means a material that can absorb or release, and the heat that absorbs or releases while maintaining the same temperature upon phase change is called latent heat.

That is, the phase change material absorbs heat through the phase change process of changing from a solid to a liquid state, and accumulates latent heat. On the contrary, when the phase change material falls to a temperature below the condensation point of changing from a liquid to a solid state, the stored latent heat is released. It will raise the ambient temperature.

Examples of such phase transitions include paraffinic hydrocarbons such as octacoic acid, heptacoic acid, hexacoic acid, and tricoic acid, calcium chloride hexahydride (CaCl _{2 ·} 6H ₂ O), and lithium nitride trihydride (Li ₃ N _· there may be mentioned inorganic flame hydroxyl, such as 3H ₂ O), zinc nitride hexahydro hydride _{(Zn 3 N 2 · 6H 2} O).

The phase change material may be a single pure material alone, but when a pure single material is used, a phase change occurs in a narrow temperature range, so that two or more kinds of phase change materials may be mixed to form a eutectic mixture or to control the degree of hydration. Thus, a phase change material capable of phase change with high calorific value in and out over a wide temperature range can be obtained.

On the other hand, the phase transition material included in the microcapsules of the present invention may be selected from n-paraffinic, cyclic paraffinic and aromatic-containing paraffinic compounds having a condensation point in the range of 44.4 ° C to 61.4 ° C and having 22 to 28 carbon atoms. In particular, it is preferable to use n-paraffinic compounds such as octacoic acid, heptacoic acid, hexacoic acid, tricoic acid, and the like. The paraffinic compound is a wax-like material included in the rubber composition for tires, and can be dispersed well in the rubber even when the cell structure of the microcapsules is destroyed. Examples thereof include cycloheptacoic acid and cyclohexacoic acid. .

In addition, the monomer used in the preparation of the cell for microcapsulation of the phase change material may be optionally used in an acrylic ester monomer, an aromatic vinyl monomer, a vinyl cyanide monomer and a maleimide monomer.

As the acrylic ester monomer, methyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, glycidyl methacrylate and the like can be used. As the aromatic vinyl monomer, styrene, t-butyl styrene, methyl styrene, vinyl toluene, monochloro styrene, dichloro styrene, dibromo styrene, ethyl styrene, vinyl naphthalene, divinyl benzene and the like can be used. Acrylonitrile, methacrylonitrile, ethacrylonitrile, etc. may be used as the vinyl cyanide monomer, and as the maleimide monomer, maleimide, N-methyl maleimide, N-ethyl maleimide, N-butyl maleimide, N-hexyl maleimide, N-dichlorohexyl maleimide, N-phenyl maleimide, N-trimaleimide, etc. can be used.

The microcapsules containing the phase change material may be included in an amount of 1 to 25 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the raw material rubber. In case of using less than 1 part by weight of microcapsules, it is not expected to improve driving performance due to the effect of preventing the temperature rise of the tire tre at high temperatures, and when used in excess of 25 parts by weight, maintenance of wear resistance cannot be expected due to a decrease in the reinforcing effect of the reinforcing agent. .

On the other hand, the structure of the microcapsules consists of one or more rigid cells in which a phase change material forms a core and surrounds the core.

In addition, the summer tire tread rubber composition according to the present invention may be added with a compounding agent, such as carbon black, silica, silica coupling agent, zinc oxide, stearic acid, oil, antioxidant, wax, resin, sulfur, vulcanization accelerator and the like. I can be added by conventional methods.

The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best describe their invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

Summer tire tread rubber composition according to the present invention as described above provides the following effects.

By overcoming the problems of the prior art, which could not simultaneously achieve the effect of improving the wear resistance and the driving performance, it is possible to maintain the wear resistance and improve the driving performance by using microcapsules containing a phase change material.

In addition, there is an advantage that can simplify the complex manufacturing process can significantly reduce the manufacturing cost and manufacturing process.

Hereinafter, the summer tire tread rubber composition according to the present invention will be described in more detail with reference to Examples. However, it should be noted that the present invention is not limited by such an embodiment.

Example  1 and Comparative example  One

The rubber sheet before vulcanization was mixed with a rubber and an additive by a conventional mixing method in the mixing ratio described in the following [Table 1], and the mixed rubber was vulcanized at 160 ° C. for 20 minutes to prepare a test specimen. On the other hand, the physical properties of the rubber composition prepared as described above are shown in [Table 2].

Rubber sheet ingredient ratio ingredient Comparative Example 1 Comparative Example 2 Example 1 Styrene-butadiene rubber ^{1 )} 100 100 100 Carbon Black ^{2 )} 72 72 72 n-octacoic acid - 10 Microencapsulated n-octacoic acid ^{3 )} - - 10 Zinc oxide 2.5 2.5 2.5 Stearic acid 2 2 2 Aromatic oils 42 42 42 Anti-aging 3.5 3.5 3.5 Wax One One One brimstone 2 2 2 Vulcanization accelerator One One One

week)

1) Glass transition temperature -50 ℃, styrene content 24%, vinyl content 16%

2) Nitrogen adsorption specific surface area is 95 ㎡ / g or more and DBP (DiButyl Phthalate) oil absorption is 90 ~ 130 mL / 100g.

3) It is Thermocules ^TM of Outlast Technogies, USA, where n-octacoic acid, which has a condensation point of 61.4 ° C, forms a core as a phase-transfer material and polymerizes methyl methacrylate monomer to form a cell.

Rubber composition property results ingredient Comparative Example 1 Comparative Example 2 Example 1 Tread part temperature (80 ℃) 79 ℃ 78 ℃ 68 ℃ Hardness (25 ℃ / 80 ℃) 63/54 63/53 63/58 300% modulus 101 101 100 Elongation at Break (%) 539 540 545 Tensile Strength (kg / ㎠) 214 213 212 Rambon Wear Index 100 100 101 60 ° C G '(MPa) 51.4 51.2 55.2

It can be seen from the results of Table 2 that the tread portion temperature is low while the Lambbon wear index of the rubber composition according to Example 1 is maintained equal to or higher than that of Comparative Examples 1 and 2, and the hardness and 60 ° C. As a result, the driving performance was improved while maintaining the wear resistance.

In addition, in the case of Comparative Example 2 including a phase change material as in Example 1, since the phase change material is not microencapsulated and thus dispersed in the rubber composition, it does not show a function as a phase change material according to temperature change, and thus has a level equivalent to that of Comparative Example 1. Physical property results were obtained.

As described above, according to the present invention, one or more rigid cells which form a core and surround the phase change material have a phase change material having a function of automatically absorbing heat above a certain temperature and automatically dissipating heat when the temperature falls below a certain temperature. When using a summer tire tread rubber composition containing a microcapsules having a structure of the tread portion by reducing the temperature rise can maintain the wear resistance while improving the running performance.

Claims (3)

Microcapsules containing a condensation point of 44.4 ° C. to 61.4 ° C. and at least one phase change material selected from the group consisting of n-paraffinic, cyclic paraffinic, and aromatic-containing paraffinic compounds having from 22 to 28 carbon atoms based on 100 parts by weight of the raw material rubber Summer tire tread rubber composition comprising 1 to 25 parts by weight. The method of claim 1, The microcapsule is composed of one or more cells, summer tire tread rubber composition, characterized in that the phase change material to form a core inside the cell. The method of claim 2, The cell tire summer rubber composition, characterized in that the cell is made of at least one monomer selected from the group consisting of an acrylic ester monomer, an aromatic vinyl monomer, a vinyl cyanide monomer and a maleimide monomer.