KR20050025816A - Rubber composition with silica for improved electric conductivity - Google Patents

Abstract

Provided is a silica rubber composition improving conductivity which includes a conductive high molecular substance and a metallic powder showing excellent conductivity so that it possibly produces a tire improving conductivity. The silica rubber composition improving conductivity comprises the components of: by 100wt% of raw materials, 20-100wt% of the metallic powder; and 1-10wt% of one or more conductive high molecular substances which are possibly selected from poly-p-phenylene derivatives like poly-p-phenylene, polyphenylene oxide, poly-p-phenylene sulfide, poly-p-phenylene sulfone and poly-p-phenylene vinylene, polypyrrol and polythiophene.

Description

Rubber composition with silica for improved electric conductivity

The present invention relates to a silica rubber composition having improved conductivity, and more particularly, to a silica rubber composition having improved conductivity by including a conductive polymer material and a metal powder having excellent conductivity in a known silica-containing rubber composition.

In general, the tire industry uses carbon black and silica as reinforcing materials for tires. However, rubber containing silica as a reinforcing filler has a tendency to use silica instead of carbon black because it has superior characteristics such as wear resistance, heat generation, durability, and dynamic viscoelasticity, compared to rubber using carbon black.

The physical properties of silica-containing rubbers depend on the properties of silica, and as the silica content increases, the mechanical properties and low temperature viscoelastic properties of the rubber improve, but silica has insulator properties. Have characteristics.

Therefore, a vehicle in which a tire containing a large amount of silica and having insulator characteristics is mounted has a problem in that it does not absorb static electricity generated in the vehicle or discharge it to the ground surface while driving.

Meanwhile, in the conventional tread rubber composition containing 100 parts by weight of raw rubber containing natural rubber, styrene butadiene rubber and butadiene rubber and silica as a reinforcing filler, according to the prior art related to the present invention, Korean Patent Application No. 2001-53834, Tread rubber composition with improved conductivity characterized in that it comprises 7 to 12 parts by weight of conductive carbon black having a surface area of 500 to 1200 mg / g, a DBP value of 150 to 400 ml / 100 g, and 1 to 10 parts by weight of an antistatic agent. have.

However, the above-described prior art differs from the present invention in the known silica-containing rubber composition, which includes a conductive polymer material and a metal powder having excellent conductivity, so as to include improved silica rubber composition.

The present invention aims to provide a silica rubber composition having improved conductivity by including a conductive polymer material and a metal powder having excellent conductivity in a known silica-containing rubber composition in order to solve the above-mentioned problems.

In addition, the present invention can provide a tire having improved conductivity made of a rubber produced by the above-mentioned improved silica rubber composition.

In order to achieve the above object, in the known silica-containing rubber composition, a silica rubber composition having improved conductivity, including 1 to 10 parts by weight of a conductive polymer material and 20 to 100 parts by weight of a metal powder, is used with respect to 100 parts by weight of the raw material rubber. Can be provided.

In the present invention, the raw material rubber can be used as long as it is used as the raw material rubber of the conventional silica-containing rubber composition. As an example of such raw rubbers, synthetic rubbers such as natural rubber, styrene butadiene rubber and butadiene rubber may be used alone, and mixed rubbers in which natural rubber and synthetic rubber mentioned above are mixed at a ratio of 1: 9 to 9: 1 are used. Can be used.

In the present invention, silica may be used as long as it is conventionally used as a reinforcing filler in a rubber composition for a tire. As an example of the silica in the present invention, 50 to 90 parts by weight of the raw material rubber having a CTAB value of 150 to 180, a BET value of 150 to 200, a specific gravity of 2.00, and a SiO ₂ content of 92% or more may be used.

Conductive polymer materials used to improve the conductivity of rubber in the present invention is poly-p-phenylene, polyphenylene oxide, poly-p-phenylene sulfide, poly-p-phenylene sulfone, poly-p-phenylene Any one or more selected from poly-p-phenylene derivatives such as vinylene, polypyrrole, polyaniline, and polythiophene can be used. For example, such conductive polymer materials may be used alone or in combination of two or more having similar characteristics in a uniform mixing ratio.

In the present invention, the conductive polymer material may be added in powder or liquid form, and the conductive polymer material acts as a process aid when blended.

In the present invention, when the conductive polymer material is less than 1 part by weight based on 100 parts by weight of the raw material rubber, it is difficult to impart conductivity to the rubber, and when it is used more than 10 parts by weight, only a high cost is required without any obvious effect on improving the conductivity of the rubber. Therefore, the conductive polymer material in the present invention is preferably used 1 to 10 parts by weight based on 100 parts by weight of the raw material rubber.

As the conductive polymer material used in the present invention, those having a molecular weight of 10,000 to 100,000 can be used. In the present invention, a conductive polymer material having various molecular weights is used. When the conductive polymer material having a molecular weight of 10,000 to 100,000 is used, a rubber meeting the object of the present invention can be obtained.

In order to further improve the conductivity of rubber in the present invention, any metal powder having high conductivity and capable of adhering with rubber may be used in addition to the above-mentioned conductive polymer material. Brass powder may be used as an example of the metal powder in the present invention.

In the present invention, when the metal powder is used in an amount of less than 20 parts by weight based on 100 parts by weight of the raw rubber, it is difficult to improve the conductivity of the rubber. have. Therefore, the metal powder in the present invention is preferably used 20 to 100 parts by weight based on 100 parts by weight of the raw material rubber.

The present invention requires various additives such as fillers, activators, anti-aging agents, process oils, vulcanizing agents, and vulcanization accelerators, which are used in conventional silica rubber compositions for tires, in addition to the above-mentioned raw rubbers, silicas, conductive polymers and metal powders. Depending on the choice can be used in a predetermined amount. However, these are general components used in silica rubber compositions for conventional tires, and thus are not essential components of the present invention.

Meanwhile, the present invention includes a tire having improved conductivity by containing a rubber made of a rubber composition having improved conductivity as mentioned above. In this case, the tire includes any one selected from a tire for a vehicle, a tire for a truck, and a tire for a bus.

Hereinafter, the present invention will be described by the following examples and test examples. However, these are not limited to the scope of the present invention by these as an embodiment of the present invention.

Comparative Example 1

100 parts by weight of styrene butadiene rubber (SBR-1712, Kumho Petrochemical) having a styrene content of 23.5%, 50 parts by weight of carbon black (N330), 2.0 parts by weight of polyethylene glycol (PEG-4000, Yakuri), 5.0 parts by weight of zinc oxide, 2.0 parts by weight of stearic acid, 2.0 parts by weight of N- (1,3-dimethylene) (6PPD), 1.4 parts by weight of sulfur. 1.8 parts by weight of N-t-butylbenzothiazole (TBBS) was placed in a Banbury mixer and cured at 160 ° C. for 18 minutes to prepare a rubber.

Table 1 below summarizes the contents of the rubber composition.

Comparative Example 2

20 parts by weight of carbon black (N330), 30 parts by weight of silica (Z-175), 2.4 parts by weight of silane coupling agent (Si-69), 4 parts by weight of poly-p-phenylene, 10 parts by weight of brass powder are excluded. Then, using the same composition and method as in Comparative Example 1 to prepare a rubber.

In the above poly-p-phenylene, molecular weight is 20,000, brass powder is composed of 60% copper and 40% zinc, the particle diameter of 200㎛ was used.

Comparative Example 3

Comparative Example 1 except that 20 parts by weight of carbon black (N330), 40 parts by weight of silica (Z-175), 3.0 parts by weight of silane coupling agent (Si-69), and 4 parts by weight of poly-p-phenylene were added. Rubber was prepared using the same composition and method as described.

<Example 1>

100 parts by weight of styrene butadiene rubber (SBR-1712, Kumho Petrochemical) having a styrene content of 23.5%, 20 parts by weight of carbon black (N330), 50 parts by weight of silica (Z-175), silane coupling agent (Si-69) 3.6 Parts by weight, polyethylene glycol (PEG-4000, Yakuri) 2.0 parts by weight, zinc oxide 5.0 parts by weight, stearic acid 2.0 parts by weight, N- (1,3-dimethylene) (6PPD) 2.0 parts by weight, sulfur 1.4 parts by weight. 1.8 parts by weight of N-t-butylbenzothiazole (TBBS), 6 parts by weight of poly-p-phenylene, and 20 parts by weight of brass powder were placed in a Banbury mixer and vulcanized at 160 ° C. for 18 minutes to prepare a rubber.

As described above, silica was used having a CTAB value of 150 to 180, a BET value of 150 to 200, a specific gravity of 2.00, and a SiO ₂ content of 92%. In addition, poly-p-phenylene had a molecular weight of 20,000, brass powder consisted of 60% copper and 40% zinc, and used a particle diameter of 200 µm.

Table 1 below summarizes the contents of the rubber composition.

<Example 2>

A rubber was manufactured using the same composition and method as in Example 1, except that 70 parts by weight of silica (Z-175), 4.8 parts by weight of a silane coupling agent (Si-69), and 40 parts by weight of brass powder were used.

<Example 3>

90 parts by weight of silica (Z-175), 4.8 parts by weight of silane coupling agent (Si-69), 10 parts by weight of poly-p-phenylene, 40 parts by weight of brass powder, except that the same composition as in Example 1 was used. And rubber using the method.

Table 1. Rubber Compositions of Comparative Examples and Examples

Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 SBR-1712 100 100 100 100 100 100 Carbon black (N330) 50 20 20 20 20 20 Silica (Z-175) - 30 40 50 70 90 Si-69 - 3.4 3.0 3.6 4.8 4.8 PEG-4000 2.0 2.0 2.0 2.0 2.0 2.0 Zinc oxide 5.0 5.0 5.0 5.0 5.0 5.0 Stearic acid 3.0 3.0 3.0 3.0 3.0 3.0 6PPD 2.0 2.0 2.0 2.0 2.0 2.0 brimstone 1.4 1.4 1.4 1.4 1.4 1.4 TBBS 1.8 1.8 1.8 1.8 1.8 1.8 Poly-p-phenylene - 4 4 6 6 10 Brass powder 10 10 - 20 40 40

<Test Example>

For rubbers prepared in Comparative Examples and Examples, physical properties such as hardness, tensile strength, and elongation were measured according to ASTM-related regulations.

In addition, the electrical conductivity of the rubber prepared in Comparative Examples and Examples was measured. Electrical conductivity measurement was made of each rubber prepared in Comparative Examples and Examples of 50mm in length, 20mm in width, 2mm in thickness of the specimen and measured the average value of the electrical resistance when the resistance is stable for 10 seconds for this specimen.

The measurement results of the physical properties and the electrical conductivity measured above are shown in Table 2 below.

Table 2. Measurements of Comparative Examples and Examples Rubber

Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Hardness 62 41 48 53 67 76 Tensile strength (kgf / cm ² ) 280 265 297 220 210 180 % Elongation 720 535 650 470 310 240 Electrical resistance (Ω) * 1.6 × 10 ⁵ 2.3 × 10 ¹⁰ 2 × 10 ⁹ 1.2 × 10 ⁶ 7 × 10 ⁶ 1.6 × 10 ⁸

* Can clearly distinguish between the insulator and the conductor of the electrical resistance, but typically if the resistance is 10 ⁴ Ω or less conductors (conductive material), is ~10 ⁴ 10 ⁸ Ω semiconductor (conductor nor nor an insulator), ⁹ to 10 If 10 ¹⁶ Ω, it is classified as an insulator

As shown in Table 2, the rubbers of Examples 1 to 3 manufactured by the rubber composition of the present invention can be seen that the electrical conductivity is improved compared to the rubber of Comparative Examples 1 to 3 prepared by the conventional rubber composition. have.

Therefore, it can be seen that a tire including a rubber manufactured by the improved silica rubber composition of the present invention easily absorbs static electricity generated in a vehicle while driving or discharges it to the ground surface.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that it can be changed.

Claims (4)

In known silica-containing rubber compositions, An improved silica rubber composition comprising 1 to 10 parts by weight of a conductive polymer material and 20 to 100 parts by weight of a metal powder, based on 100 parts by weight of raw rubber. The method of claim 1, wherein the conductive polymer material is any selected from phenylene oxide, p-phenylene sulfide, p-phenylene sulfone, p-phenylenevinylene, poly-p-phenylene, polypyrrole, polyaniline, polythiophene An improved silica rubber composition, characterized in that at least one. The improved silica rubber composition according to claim 1, wherein the metal powder is brass. A tire comprising a rubber comprising a silica rubber composition having improved conductivity according to claim 1.