JP5236180B2 - Rubber composition for covering textile cord and tire using the same - Google Patents

Description

  The present invention relates to a rubber composition for covering a textile cord and a tire using the same.

  In general, since a large load is applied to an automobile tire, a steel cord is used as a breaker and a textile cord is used as a carcass as a reinforcing material. In particular, if the tires generate heat during running and the rubber and cord are peeled off, this may cause a fatal tire failure. In addition, when a steel cord is used as a carcass cord, there is a problem that steering stability, riding comfort, rolling resistance and the like are deteriorated.

Conventionally, raw materials derived from petroleum resources such as carbon black are mainly used for rubber compositions for covering textile cords. However, in recent years, interest in global environmental conservation has increased, and automobiles are no exception, and regulations on CO ₂ emission control have been strengthened. Furthermore, oil resources are limited and the supply amount has been decreasing year by year. Oil prices are expected to rise, and there are limits to the use of raw materials derived from petroleum resources such as carbon black. As for the performance of the tire, it is necessary to consider the environment, to reduce rolling resistance in order to improve fuel efficiency, and to improve durability (rubber strength) in order to run for a long time.

  As a technique for reducing rolling resistance, a technique using silica, which is a raw material derived from non-petroleum resources, is known instead of carbon black. When silica is blended in place of carbon black, not only can rolling resistance be reduced, but the proportion of raw materials derived from petroleum resources can be reduced, giving consideration to the environment and preparing for future reductions in oil supply. However, there is a problem that Mooney viscosity increases and processability deteriorates.

  In addition, as a technique for reducing rolling resistance, a technique for reducing the blending amount of carbon black is also known. When carbon black is reduced, not only can rolling resistance be reduced, but the proportion of raw materials derived from petroleum resources can be reduced, and in consideration of the environment, it is possible to prepare for future reductions in oil supply. There is a problem that the rubber strength decreases.

  Patent Document 1 discloses an eco-tire that has a carcass sprite wrapping that uses a predetermined non-oil resource, increases the non-oil resource ratio in the tire, and is excellent in grip performance, durability, and riding comfort. It does not improve both rolling resistance characteristics and processability, and the rubber strength is not superior to a tire mainly composed of raw materials derived from petroleum resources, and there is still room for improvement in any performance.

JP 2003-63206 A

  In consideration of the environment, the present invention provides for a rubber composition for covering a textile cord mainly composed of raw materials derived from petroleum resources and a tire using the same, while preparing for a future reduction in the supply of petroleum resources. An object of the present invention is to provide a rubber composition for covering a textile cord which has reduced rolling resistance and is excellent in workability and rubber strength, and a tire using the rubber composition.

The present invention is a textile cord coating containing 25 to 80 parts by mass of silica having a nitrogen adsorption specific surface area of 70 to 150 m ² / g and 1 to 15 parts by mass of a silane coupling agent with respect to 100 parts by mass of diene rubber. The present invention relates to a tire having a carcass obtained by coating a textile cord in which polyethylene terephthalate is twisted with a rubber composition for use.

The silane coupling agent is represented by the following general formula, and the content of the silane coupling agent in which the number of sulfur atoms in the polysulfide part in the textile cord covering rubber composition is two is the total silane coupling agent. It is preferable that it is 60 mass% or more.
_{(RO) 3 -Si- (CH 2} ) x -S n - (CH 2) x -Si- (OR) 3
(In the formula, R is a linear or branched alkyl group, the carbon number of R is an integer of 1 to 8, x is an integer of 1 to 8, n represents the number of sulfur atoms in the polysulfide part, (The average value of n is 2 to 3.)

  According to the present invention, by blending a predetermined amount of a predetermined rubber component, a predetermined silica, and a silane coupling agent, considering the environment, the raw material derived from petroleum resources can be prepared in preparation for a decrease in the future supply of oil. Textile cord covering rubber composition having a main component as a main component and a rubber composition for covering a textile cord which has reduced rolling resistance and is excellent in processability and rubber strength even compared with a tire using the same. Can be provided.

  The rubber composition for covering a textile cord of the present invention contains a rubber component, silica and a silane coupling agent.

  The rubber component contains a diene rubber.

  The diene rubber is not particularly limited, and examples thereof include natural rubber (NR), epoxidized natural rubber (ENR), butadiene rubber (BR), styrene butadiene rubber (SBR), isoprene rubber (IR), butyl rubber (IIR), Examples include acrylonitrile butadiene rubber (NBR), ethylene propylene diene rubber (EPDM), and halogenated butyl rubber (X-IIR). These rubber components may be used alone or in combination of two or more. . Among these, NR and / or ENR are preferable, and NR is more preferable because environmental consideration can be taken, and a reduction in the supply amount of petroleum in the future can be prepared, and further, rolling resistance can be reduced.

  As the NR, grades of NR such as RSS # 3 and TSR20 conventionally used in the rubber industry can be used.

  The content of NR in the rubber component is preferably 85% by mass or more, and more preferably 95% by mass or more. If the NR content is less than 85% by mass, the ratio of raw materials derived from non-petroleum resources cannot be increased, and it is not possible to consider the environment or to prepare for a future reduction in the supply of oil. Tends to increase. In particular, the content of NR is most preferably 100% by mass.

  There is no restriction | limiting in particular as a silica, The thing prepared by the wet method or the dry method can be used.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is 70 m ² / g or more, preferably 80 m ² / g or more, more preferably 90 m ² / g or more. When the N ₂ SA of silica is less than 70 m ² / g, the reinforcing effect of the rubber composition by the blending of silica cannot be sufficiently obtained. Further, N ₂ SA of silica is 150 m ² / g or less, preferably 130 m ² / g or less. When the N ₂ SA of silica exceeds 150 m ² / g, the Mooney viscosity increases excessively, and the processability when coating the textile cord tends to decrease. The N ₂ SA of silica can be measured in accordance with ASTM-D-4820-93.

  The content of silica is 25 parts by mass or more, preferably 30 parts by mass or more, and more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. If the silica content is less than 25 parts by mass, the ratio of raw materials derived from non-petroleum resources cannot be increased, and it is not possible to consider the environment or to prepare for a future reduction in the supply of oil, as well as reinforcing properties. Is also significantly worse. The silica content is 80 parts by mass or less, preferably 75 parts by mass or less. When the content of silica exceeds 80 parts by mass, rolling resistance increases, and the Mooney viscosity increases excessively, resulting in poor workability.

In this invention, it is preferable to contain the silane coupling agent represented by a following formula.
_{(RO) 3 -Si- (CH 2} ) x -S n - (CH 2) x -Si- (OR) 3
(In the formula, R is a linear or branched alkyl group, the carbon number of R is an integer of 1 to 8, x is an integer of 1 to 8, n represents the number of sulfur atoms in the polysulfide part, (The average value of n is 2 to 3.)

  In the formula, R is preferably a linear or branched alkyl group, and more preferably a linear alkyl group.

  1-8 are preferable and, as for carbon number of R, 2-7 are more preferable. When the carbon number of R is 0, there is no alkoxy group, and the binding property between silica and the silane coupling agent tends to be impaired. When the carbon number exceeds 8, the affinity between silica and the silane coupling agent is impaired. Tend.

  x is preferably from 1 to 8, and more preferably from 2 to 7. When x is 0, it tends to be chemically unstable, and the decomposition and deterioration of the silane coupling agent in the rubber composition tend to be accelerated, and when it exceeds 8, silane is necessary for obtaining a sufficient reinforcing effect. There exists a tendency for content of a coupling agent to increase too much.

  n represents the number of sulfur atoms in the polysulfide part. Here, the average value of n is preferably 2 to 3. When the average value of n is less than 2, the decomposition temperature of the silane coupling agent becomes high and kneading can be performed at a higher temperature, but the vulcanization rate tends to increase, and if it exceeds 3, the silane cup There is a tendency that the decomposition temperature of the ring agent becomes low, it is easily decomposed during kneading, sulfur atoms are released, and the problem of rubber burning tends to occur during kneading.

  Examples of such silane coupling agents include bis (3-triethoxysilylpropyl) polysulfide, bis (2-triethoxysilylethyl) polysulfide, bis (3-trimethoxysilylpropyl) polysulfide, and bis (2-triethoxy). Methoxysilylethyl) polysulfide, bis (4-triethoxysilylbutyl) polysulfide, bis (4-trimethoxysilylbutyl) polysulfide, bis (triethoxysilylpropyl) polysulfide, and the like. These silane coupling agents are one kind. Or you may use it in combination of 2 or more types.

  Among the silane coupling agents contained in the rubber composition for covering a textile cord of the present invention, the content of the silane coupling agent (the silane coupling agent with n = 2) having 2 sulfur atoms in the polysulfide part is 60 mass% or more is preferable and 65 mass% or more is more preferable. When the content rate of the silane coupling agent of n = 2 is less than 60% by mass, the decomposition temperature of the silane coupling agent is relatively low, and is easily decomposed during kneading, and the workability tends to be lowered. In particular, the content of the n = 2 silane coupling agent is most preferably 100% by mass.

  The content of the silane coupling agent is 1 part by mass or more, preferably 2 parts by mass or more with respect to 100 parts by mass of the rubber component. When the content of the silane coupling agent is less than 1 part by mass, the reinforcing effect of the rubber composition by blending the silane coupling agent cannot be sufficiently obtained. Moreover, content of a silane coupling agent is 15 mass parts or less, Preferably it is 12 mass parts or less. When the content of the silane coupling agent exceeds 15 parts by mass, the Mooney viscosity increases excessively and the processability decreases.

  In the present invention, by containing a predetermined amount of a rubber component including a diene rubber, a predetermined silica and a silane coupling agent, in consideration of the environment, and in preparation for a decrease in the future supply of oil, the petroleum resource is further reduced. Compared to the rubber composition for covering textile cords as the main component, it is possible to provide a rubber composition for covering textiles with reduced rolling resistance and improved processability and rubber strength. In addition, it is possible to provide an economical eco-tire while preparing for a future decrease in the supply of oil.

  The rubber composition for covering a textile cord of the present invention is mainly intended to prepare for a reduction in the future supply of oil in consideration of the environment by using raw materials derived from non-petroleum resources as a main component. It is preferable not to use petroleum resins.

  In addition to the rubber component, silica, and silane coupling agent, the rubber composition for coating a textile cord of the present invention includes compounding agents conventionally used in the rubber industry, such as softeners, various anti-aging agents, stearic acid, Vulcanizing agents such as zinc oxide and sulfur, various vulcanization accelerators, and the like can be appropriately blended as necessary.

  The rubber composition for covering a textile cord of the present invention is produced by a general method. That is, the rubber composition for covering a textile cord of the present invention can be produced by kneading the compounding agent with a Banbury mixer, a kneader, an open roll or the like and then vulcanizing it.

  The rubber composition for coating a textile cord of the present invention does not contain organic acid cobalt compounded to enhance the adhesion to the steel cord, and therefore the rolling resistance deteriorates when used by coating the steel cord. It is preferable to use the cord coated.

  Here, the textile cord is a cord formed by twisting a plurality of filaments made of an organic fiber material. Nylon 6, nylon 66, polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), poly Paraphenylene terephthalamide (PPTA), polyvinyl alcohol (PVA), and the like can be mentioned, and these can be used alone or as a plurality of organic fiber materials. Among these, PET is preferable because it has a relatively high modulus and good steering stability.

  In addition, the rubber composition for covering a textile cord of the present invention does not contain cobalt organic acid compounded in order to improve the adhesiveness with a steel cord, so that the storage stability of the rubber composition in an unvulcanized state is high and the rubber strength is high. It is preferable to use it as a carcass because it is excellent in that it can be manufactured at low cost.

  The tire of the present invention can be produced by an ordinary method using the rubber composition for covering a textile cord of the present invention. That is, if necessary, the rubber composition for covering a textile cord of the present invention, which is blended with the above compounding agent, is used in a non-vulcanized state using a calender roll or the like so that the rubber composition does not generate excessive heat. To make a film-like unvulcanized rubber sheet with a thickness of 1 mm or less, and to produce an unvulcanized carcass by covering the textile cord, along with other components of the tire, on the tire molding machine An unvulcanized tire is molded by molding by a normal method. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain the tire of the present invention.

  As described above, by using the rubber composition for covering a textile cord of the present invention, the tire of the present invention can be made into an eco-tire that is environmentally friendly and can be prepared for a future reduction in the amount of oil supply.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Next, various chemicals used in Examples and Comparative Examples will be described together.
Natural rubber (NR): TSR20
Carbon black: Dia Black H (N ₂ SA: 79 m ² / g) manufactured by Mitsubishi Chemical Corporation
Silica 1: Z115GR manufactured by Rhodia (N ₂ SA: 112 m ² / g)
Silica 2: Ultrazil VN3 manufactured by Degussa (N ₂ SA: 175 m ² / g)
Silane coupling agent: Si75 (bis (triethoxysilylpropyl) disulfide) manufactured by Degussa
Process oil: Diana Process PS32 manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: Nocrack 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Stearic acid: Stearic acid “paulownia” manufactured by NOF Corporation
Zinc oxide: Zinc oxide No. 1 (average particle size: 290 nm) manufactured by Mitsui Mining & Smelting Co., Ltd.
Sulfur: Kristex HSOT20 manufactured by Flexis
Vulcanization accelerator: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Example 1 and Comparative Examples 1-3
In accordance with the formulation shown in Table 1, using a 1.7 L Banbury mixer manufactured by Kobe Steel Co., Ltd., filling chemicals other than sulfur and vulcanization accelerator so that the filling rate is 58%, and at 90 rpm The mixture was kneaded for 3 minutes until reaching 150 ° C. to obtain a kneaded product. Next, using a calender roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 3 minutes under the conditions of a line speed of 20 rpm and 90 ° C., and a thin film having a thickness of 0.7 mm An unvulcanized rubber sheet was obtained. Furthermore, the vulcanized rubber sheet of Example 1 and Comparative Examples 1-3 was created by vulcanizing the obtained unvulcanized rubber sheet at 175 ° C. for 10 minutes.

(Processability)
A test piece of a predetermined size was prepared from the unvulcanized rubber sheet, and according to JIS K 6300 “Unvulcanized rubber—physical properties—Part 1: Determination of viscosity and scorch time using Mooney viscometer”. Using a viscosity tester, the Mooney viscosity (ML _{1 +} 4/130 ° C) at the time when 4 minutes passed by rotating a small rotor under the temperature condition of 130 ° C heated by preheating for 1 minute was measured. The Mooney viscosity index of Comparative Example 1 was set to 100, and the Mooney viscosity of each formulation was indicated by an index according to the following formula. In addition, it shows that Mooney viscosity is so small that Mooney viscosity index is large and it is excellent in workability.
(Mooney viscosity index) = (Mooney viscosity of Comparative Example 1)
÷ (Mooney viscosity of each formulation) x 100

(Rubber strength)
A vulcanized rubber test piece was prepared from the vulcanized rubber sheet using a No. 3 dumbbell, and subjected to a tensile test according to JIS K 6251 “Vulcanized rubber and thermoplastic rubber—How to obtain tensile properties”. (TB) and elongation at break (EB) were measured, and the product (TB × EB) was calculated. In addition, it shows that it is excellent in rubber | gum strength, so that TB * EB is large.

(Rolling resistance)
A textile cord is covered with the unvulcanized rubber sheet to produce an unvulcanized carcass, and bonded to another tire member, and vulcanized at 175 ° C. for 10 minutes, whereby a test tire (tire size: 195 / 65R15). As the cord, polyethylene terephthalate (PET) was used in Example 1 and Comparative Examples 1 and 2, and a steel cord was used in Comparative Example 3.

Using a rolling resistance tester manufactured by STL, the rolling resistance when the test tire was run under the conditions of rim: 6JJ × 15, internal pressure: 230 kPa, load: 49 N, speed: 80 km / h, The rolling resistance index of Comparative Example 1 was set to 100, and the rolling resistance of each formulation was displayed as an index. In addition, it shows that rolling resistance is reduced and it is excellent, so that a rolling resistance index | exponent is large.
(Rolling resistance index) = (Rolling resistance of Comparative Example 1)
÷ (Rolling resistance of each compound) x 100

  The evaluation results of the above test are shown in Table 1.

  Comparative Example 1 is a textile cord coating rubber composition containing a large amount of a conventional petroleum resource-derived raw material containing carbon black.

  In Example 1 in which a predetermined amount of NR, a predetermined silica, and a silane coupling agent are blended, the raw material derived from non-petroleum resources is a main component, which is environmentally friendly and prepares for a future decrease in the supply of oil. Further, even when compared with Comparative Example 1 containing a large amount of raw materials derived from petroleum resources, it is possible to reduce rolling resistance and improve rubber strength and workability.

In Comparative Example 2 in which N ₂ SA is blended with silica that is not within the predetermined range, the main component is a non-petroleum resource, which can be environmentally friendly and can be prepared for a future reduction in the supply of oil. Furthermore, even if compared with Comparative Example 1 containing a large amount of raw materials derived from petroleum resources, the rubber strength can be maintained and the rolling resistance can be reduced, but the workability is remarkably deteriorated.

Claims (1)

For 100 parts by mass of diene rubber,
A rubber composition for covering a textile cord containing 25 to 80 parts by mass of silica having a nitrogen adsorption specific surface area of 70 to 150 m ² / g and 1 to 15 parts by mass of a silane coupling agent and not containing carbon black. A tire having a carcass obtained by covering a textile cord twisted with terephthalate ,
The silane coupling agent is represented by the following general formula:
The tire whose content rate of the silane coupling agent whose number of sulfur atoms of a polysulfide part is two is 60 mass% or more of all the silane coupling agents.
_{(RO) 3 -Si- (CH 2} ) x -S n - (CH 2) x -Si- (OR) 3
(In the formula, R is a linear or branched alkyl group, the carbon number of R is an integer of 1 to 8, x is an integer of 1 to 8, n represents the number of sulfur atoms in the polysulfide part, (The average value of n is 2 to 3.)