KR20090132059A - A rubber composition to reinforce the sidewall of run-flat tire - Google Patents

Abstract

PURPOSE: A rubber composition for reinforcing a sidewall of run-flat tire is provided to improve modulus property and heat generation property by using a vinyl-cis rusbber as a rubber-resin composite and a nano reinforcing resin containing a modified phenol formaldehyde resin. CONSTITUTION: A rubber composition for reinforcing a sidewall of run-flat tire comprises a base rubber 100.0 parts by weight, a nano reinforcing resin 0.5~10 parts by weight containing phenol formaldehyde resin degenerated with cashew nut shell liquid, carbon black 30~60 parts by weight and silica 10~50 parts by weight. The base rubber comprises natural rubber 20~80 weight% and a vinyl-cis rusbber 20~80 weight% as a rubber-resin composite.

Description

Rubber composition for reinforcement of sidewall of run flat tire {A RUBBER COMPOSITION TO REINFORCE THE SIDEWALL OF RUN-FLAT TIRE}

The present invention relates to a rubber composition for reinforcing sidewalls of a run flat tire, and more particularly, a raw rubber and a modified phenol formaldehyde made of natural rubber and vinyl-cis rubber (VCR), a rubber-resin composite. The present invention relates to a rubber composition for reinforcing sidewalls of run-flat tires, which is made of nano-reinforcement resins containing resins.

Run-flat tires are tires that can travel a certain distance without the inflation pressure by inserting structures or reinforcement sidewalls inside the tires. It provides functionality suitable for high speed driving of sports cars and some high-grade sedans, and has been installed in mass production vehicles recently because it enables relatively stable driving without damaging tires during high speed driving.

However, the disadvantage of run flat tires is that they are expensive and have a higher noise level than ordinary tires. However, these problems can be solved as technology advances, and thus the demand for run flat tires is expected to increase gradually.

In general, various additives are used in rubber for tires to improve physical properties. For example, carbon black and / or silica are mainly used for reinforcement of rubber. Recently, a method of improving physical properties by applying a rubber-resin composite obtained by directly polymerizing a reinforcing resin to a polybutadiene rubber in addition to carbon black and silica has been proposed. However, including vinyl-cis rubber (VCR), a rubber-resin composite, improves the mechanical properties and reduces the durability of run-flat tires due to high heat generation, and improves the heat-generating properties of rubber by reducing the content of fillers. There is a limit to complement the characteristics together.

An object of the present invention is to solve the above problems, nano-reinforcement composed of natural rubber, raw rubber made of vinyl-cis rubber (VCR) rubber and resin composite and modified phenol formaldehyde resin It is to provide a rubber composition for reinforcing the sidewall of the run-flat tire, which is made of a resin, thereby improving the modulus characteristics and heat generation characteristics.

Rubber composition for reinforcing the sidewall of the run-flat tire of the present invention is modified with respect to 100 parts by weight of the raw material rubber consisting of 20 to 80% by weight of natural rubber and 20 to 80% by weight of vinyl-sheath rubber (VCR), a rubber-resin composite It comprises a 0.5 to 10 parts by weight of nano-reinforcement resin, 30 to 60 parts by weight of carbon black and 10 to 50 parts by weight of silica containing a phenol formaldehyde resin.

Natural rubber used as the raw material rubber in the present invention is a conventional one used in the rubber industry, and many products are commercialized according to the RSS (ribbed smoked sheet), SMR, STR and SIR (Standard rubber, according to the classification and product grade according to the place of production). And the like). The natural rubber is preferably used 20 to 80% by weight, when the content is less than 20% by weight can not achieve a performance improvement due to the excellent tensile strength, tear strength of the natural rubber, the content exceeds 80% by weight In this case, the content of vinyl-cis rubber (VCR) is relatively low, which is not preferable because it can not achieve an effective improvement of performance according to the object of the present invention.

Vinyl-cis rubber (VCR), a rubber-resin composite used as a raw material rubber in the present invention, polymerizes 1,4-polybutadiene rubber by polymerizing butadiene under a cobalt (Co) or aluminum (Al) catalyst for polymerization in a solvent. step; And a rubber-resin composite prepared by dispersing a highly crystalline syndiotactic-1,2-polybutadiene (SPB) resin using the prepared 1,4-polybutadiene rubber as a matrix, followed by purification and drying. The rubber thus produced is in the form of a micro-dispersion vinyl-cis rubber (VCR) in which a polybutadiene rubber is a matrix and a highly crystalline syndiotactic-1,2-polybutadiene (SPB) resin is dispersed.

Syndiotactic-1,2-polybutadiene (SPB) resin used in the vinyl-cis rubber (VCR), which is the rubber-resin composite, is a highly crystalline (70-80% crystallization) fibrous material and has a diameter of 0.02-0.1 μm. It is preferable that it is 80-90 m <2> / g.

Vinyl-sheath rubber (VCR), the rubber-resin composite, has a resin dispersed in a matrix rubber in the form of short fibers, and serves as a reinforcing material. The reinforcing effect is about three times better than that of a conventional carbon black filler. This reinforcing effect appears to be due to the effective interfacial interaction with the matrix rubber due to the dispersed state of the ultrafine fiber shape or aggregated structure of the syndiotactic-1,2-polybutadiene (SPB) resin.

The content of the vinyl-cis rubber (VCR) used in the present invention is preferably 20 to 80% by weight. If the amount is less than 20% by weight, the desired performance is not improved. It is not preferable to exceed the% because the content of natural rubber is relatively reduced and there is a problem in that it does not have the best performance due to the increase in the 1,4-polybutadiene rubber matrix of vinyl-cis rubber.

Nano-reinforcement resin used in the present invention, nano-reinforcement resin consisting of 80 to 95% by weight of phenol formaldehyde resin modified with cashew nut shell liquid (CNSL: cashew nut shell liquid) and 5 to 20% by weight of general formaldehyde resin It is preferable to use 0.5 to 10 parts by weight based on 100 parts by weight of the raw material rubber, but when the amount is less than 0.5 parts by weight, the tensile properties are not good due to the low reinforcing effect, and when the amount exceeds 10 parts by weight, excessive modulus rises. And due to the low elongation and the like there is a limit in obtaining the physical properties of the rubber of the present invention.

Carbon black used as the filler in the present invention is preferably used 30 to 60 parts by weight based on 100 parts by weight of the raw material rubber, when the content is less than 30 parts by weight of rubber properties (tension properties) is good due to the low filling effect It is not preferable because it is not preferable, and if it exceeds 60 parts by weight, there is a limit in obtaining the desired rubber properties such as excessive hardness and modulus increase.

Silica used as a filler in the present invention is preferably used 10 to 50 parts by weight based on 100 parts by weight of the raw material rubber, when the content is less than 10 parts by weight of rubber properties (tension properties) is not good due to the low filling effect. It is not preferable, and if it exceeds 50 parts by weight, there is a limit in obtaining the desired rubber properties such as excessive hardness and modulus increase, and there is a problem of poor work performance in post-process due to workability and shrinkage problems such as compounding and extrusion. Not desirable

To the rubber composition of the present invention, additives for rubber composition for sidewall reinforcement, for example, process oil, zinc oxide, stearic acid, anti-aging agent, wax, pressure-sensitive adhesive, accelerator, and other additives may be appropriately selected and added. The choice and amount of additives for are known in the art.

The rubber composition for reinforcing the sidewall of the run flat tire of the present invention is a modulus by using a natural rubber, a raw rubber made of vinyl-cis rubber (VCR), a rubber-resin composite, and a nano-reinforced resin composed of a modified phenol formaldehyde resin. Characteristics and heating characteristics can be improved.

Hereinafter, the present invention will be described in more detail with reference to the following Examples and Comparative Examples. The following examples are merely examples for carrying out the present invention, and are not intended to limit the protection scope of the present invention.

Example  And Comparative example

Raw rubbers, nano reinforcing resins, carbon black, silica, coupling agents, dispersants, paraffin oil, zinc oxide, stearic acid, active agents, antioxidants and adhesives of the contents as shown in Table 1 below were placed in a Banbury mixer, 140 Mixing at 30 ° C. for 30 minutes to obtain a rubber compound, adding a vulcanizing agent, a vulcanization accelerator, a vulcanization retardant with the contents shown in Table 1 to the rubber compound and vulcanizing at 150 ° C. for 20 minutes to prepare a rubber specimen. It was.

                                                     (Unit: parts by weight) Item Comparative Example 1 Comparative Example 2 Example 1 Example 2 Natural rubber 60 60 60 60 Polybutadiene rubber ^{1 )} 40 - - - Vinyl sheath rubber ^{2 )} - 40 40 40 Reinforcement resin1 ^{3 )} - 5 - - Nano reinforced resin2 ^{4 )} - - 5 10 Carbon black 50 50 50 40 Silica 10 10 10 10 Coupling Agents ^{5 )} 1.5 1.5 1.5 1.5 Paraffin oil 3 3 3 3 Activator ^{6 )} 3 3 3 3 Zinc oxide 4 4 4 4 Stearic acid 2 2 2 2 Antioxidant ^{7 )} 2.5 2.5 2.5 2.5 Dispersants ^{8 )} 2 2 2 2 Glue ^{9 )} 2.5 2.5 2.5 2.5 Vulcanizer ^{10 )} 6 6 6 6 Vulcanization Accelerator (NS) ^{11 )} 1.5 5 5 5 Pulmonary Delay Retardant (PVI) ^{12 )} 0.2 0.2 0.2 0.2

week)

1) Polybutadiene rubber: KBR-01 (Kumho Petrochemical Co., Ltd.)

2) Vinyl sheath rubber: VCR-617 (product of UBE company)

3) Reinforcing resin 1: Formaldehyde resin (DYPHENE-8318, manufactured by PMC, USA)

4) Nano Reinforcement Resin 2: Nano reinforcement resin (RNC-1315A, made by MNB Green Earth Co., Ltd.) consisting of 90% by weight of phenol formaldehyde resin and 10% by weight of formaldehyde resin modified with CNSL.

5) Coupling agent: Bis- (3-triethoxysilylpropyl) tetrasulfide (X-50S)

6) Activator: Zinc salt mixture of aliphatic carboxylic acid and aromatic carboxylic acid (Activator-73A, manufactured by Strucktol)

7) Antioxidant: N- (1,3-dimethylbutyl) -N-phenyl-P-phenylenediamine (N- (1,3-dimethylbutyl) -N-Phenyl-P-Phenylenediamine (Kumanox-13))

8) Dispersant: EF-44 (Strucktol)

9) Adhesive: Resorcinol Formaldehyde Resin (B-18-S)

10) Vulcanizer: Insoluble sulfur (80%) + process oil (20%)

11) Vulcanization accelerator (NS): N-tert-butyl-2-benzothiazolesulfenamide

12) Vulcanization Delay Agent: N-cyclohexylthiophthalimide

The rubber specimens prepared in Examples and Comparative Examples were measured for hardness, 100% modulus, tensile strength, elongation, pattern viscosity, heating properties, and blowout according to ASTM-related regulations. It is shown collectively in Table 2 below.

                                                           (Unit: Relative Index) Properties Comparative Example 1 Comparative Example 2 Example 1 Example 2 Hardness (ShoreA method) 100 105 100 100 100% Modulus (kg / ㎠) 100 130 120 120 Tensile Strength (kg / ㎠) 100 130 125 140 Elongation (%) 100 95 110 120 Viscosity 100 120 110 100 Fever 100 150 140 100 Blowout 100 105 110 110

As can be seen from the results of Table 2, according to the present invention, a vinyl-cis rubber, which is a rubber-resin composite, is used as a raw material rubber, and phenol formaldehyde modified with CNSL is used instead of the conventional nano-reinforcement resin. In the case of using the nano-reinforcement resin to be, high tensile properties can be expressed even at a low level of exothermic properties, thereby achieving improved durability.

Claims (5)

Containing phenol formaldehyde resin modified with cashew nut shell liquid with respect to 100 parts by weight of the raw material rubber consisting of 20 to 80% by weight of natural rubber and 20 to 80% by weight of vinyl-cis rubber as a rubber-resin composite Rubber composition for sidewall reinforcement of a run flat tire comprising 0.5 to 10 parts by weight of nano-reinforcement resin, 30 to 60 parts by weight of carbon black and 10 to 50 parts by weight of silica. The run-flat tire according to claim 1, wherein the rubber-resin composite vinyl-cis rubber is formed by dispersing highly crystalline fibrous syndiotactic-1,2-polybutadiene resin in 1,4-polybutadiene rubber. Rubber composition for reinforcing sidewalls. The run flat according to claim 2, wherein the highly crystalline fibrous syndiotactic-1,2-polybutadiene resin has a diameter of 0.02 to 0.1 µm and a short fiber having a specific surface area of 80 to 90 m 2 / g. Rubber composition for reinforcing sidewalls of tires. According to claim 1, wherein the nano-reinforcement resin, run characterized in that consisting of 80 to 95% by weight of phenol formaldehyde resin modified with cashew nut shell liquid and 5 to 20% by weight of formaldehyde resin. Rubber composition for reinforcing sidewalls of flat tires. The run flat tire which has a side wall part to which the rubber composition for sidewall reinforcement of any one of Claims 1-4 was applied.