KR20120132346A

KR20120132346A - Pneumatic tire

Info

Publication number: KR20120132346A
Application number: KR1020120050190A
Authority: KR
Inventors: 타츠야 미야자키
Original assignee: 스미토모 고무 고교 가부시키가이샤
Priority date: 2011-05-27
Filing date: 2012-05-11
Publication date: 2012-12-05

Abstract

The present invention provides a pneumatic tire excellent in durability. A pneumatic tire comprising a sidewall and a carcass, wherein the sidewall is made of a rubber composition for a sidewall containing a certain amount of sulfur, and the carcass is made of a carcass cord coated with a rubber composition for coating a carcass cord. There is provided a pneumatic tire in which the sulfur content of the monthly rubber composition and the carcass cord coating rubber composition satisfies a specific relationship. Also, as a pneumatic tire comprising a clinch and a carcass, the clinch is made of a rubber composition for clinch containing a certain amount of sulfur, and the carcass is made of a carcass cord coated with a rubber composition for coating a carcass cord, and There is provided a pneumatic tire in which the sulfur content of the tooth rubber composition and the carcass cord coating rubber composition satisfies a specific relationship.

Description

Pneumatic tire {PNEUMATIC TIRE}

The present invention relates to a pneumatic tire.

In addition to the tread contacting the road surface, the pneumatic tire is composed of various members such as sidewalls, carcasses, and clinches. In the blending design of the rubber composition used for each member of the prior art, the rubber composition of each member is designed through the experimental test to provide the best rubber composition for each member (for example, Patent Documents 1 to 3). According to the evaluation result of the experimental test, the pneumatic tire was produced combining each member which consists of the best rubber compositions, respectively. However, there has been a problem that the durability of the manufactured pneumatic tire is often lower than the durability expected from the experimental test results.

Patent Document 1: Japanese Patent No. 4308289 Patent Document 2: Japanese Patent Application Laid-Open No. 2008-24913 Patent Document 3: Japanese Patent No. 4246245

An object of the present invention is to solve the above problems and to provide a pneumatic tire having excellent durability.

The present inventors have studied the above problems, and sulfur is moved between members during vulcanization and tire use, and the movement of sulfur causes changes in physical properties in each member. The hypothesis reached that the durability is lower than expected.

And paying attention to the movement of sulfur from the rubber composition for a carcass topping used in carcasses, the carcass cord coating rubber composition and a member adjacent to carcass (e.g., a sidewall, It has been found that the durability of a pneumatic tire produced so that the sulfur content of the rubber composition (for example, a rubber composition for sidewall, a rubber composition for clinch, etc.) used for clinching) satisfies a specific relational expression is very excellent. Moreover, the inventor determined the range of sulfur content according to the expected performance peculiar to each member, and completed the present invention.

That is, according to the first aspect of the present invention, there is provided a pneumatic tire including a sidewall and a carcass, wherein the sidewall is a rubber composition for sidewalls having a sulfur content of more than 1.41 parts by mass and less than 2.5 parts by mass with respect to 100 parts by mass of the rubber component. The car tire manufactured by the carcass cord coated with the carcass cord coating rubber composition containing the rubber component, and the sulfur content of the rubber composition for the sidewall and the carcass cord coating rubber composition satisfying the following relation Is provided.

-0.2 <(sulfur content with respect to 100 mass parts of rubber components of the rubber composition for carcass cord coating)-(sulfur content with respect to 100 mass parts of the rubber component of the rubber composition for sidewalls) <1.1

In the first aspect of the present invention, the sulfur content of the rubber composition for sidewall is preferably more than 1.61 parts by mass and less than 2.3 parts by mass with respect to 100 parts by mass of the rubber component.

In the first aspect of the present invention, the sulfur content of the carcass cord coating rubber composition is preferably more than 1.91 parts by mass and less than 3.5 parts by mass with respect to 100 parts by mass of the rubber component.

In 1st aspect of this invention, it is preferable that content of the process oil of the rubber composition for sidewalls is 10 mass parts or less with respect to 100 mass parts of rubber components.

In 1st aspect of this invention, it is preferable that content of the alkylphenol-sulfur chloride condensate of the rubber composition for sidewalls is 0.2-6 mass parts with respect to 100 mass parts of rubber components.

According to a second aspect of the present invention, there is provided a pneumatic tire comprising a clinch and a carcass, wherein the clinch includes a rubber component and has a sulfur content with respect to 100 parts by mass of the rubber component, wherein the sulfur content exceeds 1.71 parts by mass and is less than 2.9 parts by mass. The carcass is made of a carcass cord coated with a carcass cord coating rubber composition including a rubber component, and the sulfur content of the clinch rubber composition and the carcass cord coating rubber composition satisfies the following relationship. Tires are provided.

-0.6 <(sulfur content with respect to 100 mass parts of rubber components of the rubber composition for carcass cord coating)-(sulfur content with respect to 100 mass parts of the rubber component of the rubber composition for cleaning) <1.1

In the second aspect of the present invention, the sulfur content of the rubber composition for clinch is preferably more than 1.91 parts by mass and less than 2.7 parts by mass with respect to 100 parts by mass of the rubber component.

In the second aspect of the present invention, the sulfur content of the carcass cord coating rubber composition is preferably more than 1.91 parts by mass and less than 3.5 parts by mass with respect to 100 parts by mass of the rubber component.

In 2nd aspect of this invention, it is preferable that content of the sulfenamide type vulcanization accelerator of the rubber composition for clinch is 2.5-3.5 mass parts with respect to 100 mass parts of rubber components.

In the second aspect of the present invention, the content of the alkylphenol-sulfur chloride condensate in the rubber composition for clinch is preferably 0.2 to 6 parts by mass based on 100 parts by mass of the rubber component.

According to a first aspect of the present invention, there is provided a pneumatic tire comprising a sidewall and a carcass, wherein the sidewall is made of a rubber composition for sidewalls containing a certain amount of sulfur, and the carcass is coated with a rubber composition for coating a carcass cord. It is made of a carcass cord and is excellent in durability because the sulfur content of the rubber composition for sidewall and the rubber composition for carcass cord coating satisfies a specific relational expression. Good steering stability, fuel efficiency and elongation at break can also be achieved.

According to a second aspect of the present invention, there is provided a pneumatic tire comprising a clinch and a carcass, wherein the clinch is made of a rubber composition for clinching containing a certain amount of sulfur, and the carcass is coated with a carcass cord coating rubber composition. It is made of a cord, and is excellent in durability because the sulfur content of the rubber composition for clinching and the rubber composition for coating a carcass cord satisfies a specific relationship. In addition, good steering stability, fuel efficiency and elongation at break can be obtained.

According to the first aspect of the present invention, a pneumatic tire comprising a sidewall and a carcass, wherein the sidewall includes a rubber component and has a sulfur content of more than 1.41 parts by mass and less than 2.5 parts by mass with respect to 100 parts by mass of the rubber component. The carcass is made of a carcass cord coated with a carcass cord coating rubber composition containing a rubber component, and the sulfur content of the rubber composition for sidewall and the carcass cord coating rubber composition is represented by the following relationship. Satisfies.

As sulfur transfers from the carcass to the sidewall, the crosslinking density of the sidewall rubber increases, so that the crack growth resistance and the elongation at break of the sidewall rubber are greatly deteriorated, and it is separated from the dip surface in contact with the carcass. separation is liable to occur, and durability deteriorates significantly. On the other hand, in the carcass whose sulfur is reduced by the movement, the sulfur concentration around the carcass cord is lowered, and the sulfur necessary for the recombination of sulfur between the carcass cord and the rubber composition for coating the carcass cord is insufficient and durability is reduced.

In contrast, when sulfur moves from the sidewall to the carcass, if the amount of movement is large, the hardness Hs of the sidewall is lowered, and thus the steering stability is lowered. And although the amount of sulfur in carcass increases and adhesiveness with a carcass cord improves, crack growth resistance falls, and durability falls.

On the other hand, in the first aspect of the present invention, since the sulfur content of the rubber composition for the sidewall and the rubber composition for the carcass cord coating satisfies the above relation, and the specific amount of sulfur is contained in the rubber composition for the sidewall, the sulfur is moved. It is possible to appropriately adjust the amount of sulfur movement by suppressing this, so that good durability can be obtained while maintaining good steering stability, fuel efficiency, and elongation at break.

The first type of pneumatic tire of the present invention includes a sidewall and a carcass.

Carcass is a member made of a carcass cord and a carcass cord covering rubber layer, also called a case. Specifically, for example, the member shown in Fig. 1 and the like of Japanese Patent Laid-Open No. 2008-75066.

The sidewall is a member disposed outside the carcass, and is specifically, for example, a member shown in Fig. 1 and the like of Japanese Patent Laid-Open No. 2008-75066.

In a first aspect of the invention, the sidewall is made of a rubber composition for the sidewall, and the carcass is made of a carcass cord coated with the rubber composition for coating the carcass cord.

In the first aspect of the present invention, the sulfur content of the rubber composition for sidewall and the rubber composition for carcass cord coating satisfies the following relationship. Thereby, the durability of a pneumatic tire can be improved suitably. In the case of -0.2 or less, the adhesiveness of a carcass cord and the rubber | carcass cord coating rubber | gum will fall, and durability fall will be caused. Moreover, in the case of 1.1 or more, the crosslinking density of a sidewall (especially the surface layer of a sidewall) increases, a crack growth resistance falls, and durability falls.

In the present specification, the sulfur content means the total content of pure sulfur in the vulcanizing agent blended into the rubber composition. The content of pure sulfur here means, for example, the amount of pure sulfur contained in the oil-containing sulfur when oil-containing sulfur is used as the vulcanizing agent, and further contains a sulfur atom as the vulcanizing agent (eg, alkyl Phenol-sulfur chloride condensate), the amount of sulfur atoms contained in the compound.

As for the minimum of the said relational formula, 0 is preferable and 0.2 is more preferable.

1.0 is preferable and, as for the upper limit of the said relational formula, 0.9 is more preferable.

Below, the rubber composition for sidewalls and the carcass cord coating rubber composition used by the 1st aspect of this invention are demonstrated.

(Rubber composition for sidewall)

Although the vulcanizing agent which can be used for the rubber composition for side walls is not specifically limited, Sulfur, alkylphenol-sulfur chloride condensate, etc. are mentioned as a suitable example. Sulfur is preferable as a vulcanizing agent, and it is also preferable to mix | blend an alkylphenol-sulfur chloride condensate with sulfur.

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur and the like.

By blending the alkylphenol-sulfur chloride condensate, it is possible to form a thermally stable crosslinked structure as compared with normal sulfur crosslinking, to greatly improve fuel efficiency and durability, and to improve steering stability. In addition, since the alkylphenol-sulfur chloride condensate binds strongly with the rubber component, it is considered that sulfur contained in the condensate is difficult to move.

As an alkylphenol-sulfur chloride condensate, the alkylphenol-sulphur chloride condensate represented by following formula (1) is preferable.

In the formula, R means an alkyl group or amyl group having 5 to 15 carbon atoms, which may be the same or different from each other. x and y mean an integer of 1 to 4, which is the same or different. In addition, m means the integer of 0-300.

In order to improve the dispersibility in the rubber component of the alkylphenol-sulfur chloride condensate, m is an integer of 0 to 300, an integer of 0 to 100 is preferable, and an integer of 3 to 100 is more preferable. When m is 3 or more, the effect of improving scorch delay, steering stability, fuel efficiency, elongation at break and durability is great. In order to allow high hardness to be expressed efficiently (ie, to suppress reversal), x and y are each an integer of 1 to 4, and both are preferred. In order to improve the dispersibility in the rubber component of the alkylphenol-sulfur chloride condensate, R is an alkyl group having 5 to 15 carbon atoms or an amyl group, and an alkyl group having 8 to 15 carbon atoms is preferable. When carbon number is 8 or more, the effect of improving scorch retardation, steering stability, fuel efficiency, breaking elongation, and durability is large.

The alkylphenol-sulfur chloride condensate can be prepared by a known method, and is not particularly limited. Examples thereof include a method in which the alkylphenol and sulfur chloride are reacted at a molar ratio of 1: 0.9 to 1.25.

As a specific example of the alkylphenol-sulfur chloride condensation, TACKIROL V200 manufactured by Taoka Chemical Co., Ltd., (Formula (1), wherein R = C ₈ H ₁₇ ; x = 2; y = 2; m = 0 to 100 integer) and TS3101 (formula _{(1) R = C 12 H} 25 in; x = 2; y = 2 ;? m = 170 can be given a constant of 210), and the like.

The sulfur content of the alkylphenol-sulfur chloride condensate is SO ₂ by heating the condensate at 800 to 1000 ° C. in a combustion furnace. Gas or SO ₃ After converting to gas, the ratio calculated | required optically quantified the quantity of sulfur from the gas generation amount.

Content of the said alkylphenol-sulfur chloride condensate becomes like this. Preferably it is 0.2 mass part or more, More preferably, it is 0.5 mass part or more with respect to 100 mass parts of rubber components. If it is less than 0.2 mass part, the effect which mix | blended the alkylphenol-sulfur chloride condensate cannot fully be acquired. Preferably the said content is 6 mass parts or less, More preferably, it is 2 mass parts or less. When it exceeds 6 mass parts, there exists a possibility that durability may fall large.

In the rubber composition for sidewalls, the sulfur content exceeds 1.41 parts by mass, preferably exceeds 1.61 parts by mass, and more preferably exceeds 1.85 parts by mass with respect to 100 parts by mass of the rubber component. At 1.41 parts by mass or less, the inflow of sulfur from the carcass increases, the crack growth resistance and the elongation at break of the sidewall rubber are greatly deteriorated, and separation is liable to occur on the dip surface in contact with the carcass, and the durability is greatly deteriorated. Also, not enough steering stability is obtained. The said content is less than 2.5 mass parts, Preferably it is less than 2.3 mass parts, More preferably, it is less than 2.2 mass parts. At 2.5 parts by mass or more, the elongation at break (particularly elongation at break after thermal aging), crack growth resistance, fuel efficiency and durability are lowered.

Although the rubber which can be used for the rubber component of the rubber composition for sidewalls is not specifically limited, For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber Diene rubbers such as (SIBR), chloroprene rubber (CR) and acrylonitrile butadiene rubber (NBR). Rubber may be used independently and may use two or more types together. Especially, NR or BR is preferable and in order to obtain favorable durability, maintaining good steering stability, fuel efficiency, and elongation at break, it is more preferable to use NR and BR together.

The said NR is not specifically limited, For example, a general thing in tire industry, such as SIR20, RSS # 3, TSR20, IR2200, can be used.

NR content in 100 mass% of rubber components becomes like this. Preferably it is 40 mass% or more, More preferably, it is 50 mass% or more. The said NR content becomes like this. Preferably it is 80 mass% or less, More preferably, it is 70 mass% or less. If the NR content is within the above range, good durability is ensured while maintaining good steering stability, fuel efficiency, and elongation at break.

The BR is not particularly limited, and those common in the tire industry can be used. For example, 1,2-syndiotactic poly, such as high cis-content BR, Ube Industries, Ltd., VCR412, VCR617, such as BR1220 manufactured by Zeon Corporation, Ube Industries, Ltd., manufactured BR150B, and the like. BR containing butadiene crystals (SPB), BR of high-content vinyl such as Europrene BR HV80 manufactured by Polimeri Europa, BR (rare earth BR) synthesized using a rare earth catalyst. Moreover, tin modified butadiene rubber (tin modified BR) modified with a tin compound can also be used. Among them, a rare earth system BR capable of obtaining good durability while maintaining good steering stability, fuel efficiency, and elongation at break is preferable. In addition, the use of tin-modified BRs in combination with rare earth BRs can further improve fuel efficiency.

As the rare earth catalyst used in the synthesis of the rare earth BR, a well-known one can be used, and examples thereof include a lanthanum-based rare earth element compound, an organoaluminum compound, an aluminoxane, a halogen-containing compound, and a catalyst containing a Lewis base if necessary. Etc. can be mentioned. Especially, the Nd type catalyst which used the neodymium (Nd) containing compound as a lanthanum series rare earth element compound is especially preferable.

Examples of the lanthanum rare earth element compounds include halides, carboxylates, alcoholates, thioalcolates, and amides of rare earth metals having an atomic number of 57 to 71. Among them, as described above, the use of the Nd-based catalyst is preferable in that it provides a high cis content and a low vinyl content BR.

As the organoaluminum compound, those represented by AlR ^a R ^b R ^c (wherein R ^a , R ^b and R ^c are the same or different from each other and represent hydrogen or a hydrocarbon group having 1 to 8 carbon atoms) can be used. Examples of aluminoxanes include acyclic aluminoxanes and cyclic aluminoxanes. As the halogen-containing compound, represented by AlX _k R ^d ₃ _-k (wherein X is halogen, R ^d is an alkyl, aryl or aralkyl group having 1 to 20 carbon atoms, and k is 1, 1.5, 2 or 3). Aluminum halides; Strontium halides such as Me ₃ SrCl, Me ₂ SrCl ₂ , MeSrHCl ₂ or MeSrCl ₃ ; And metal halides such as silicon tetrachloride, tin tetrachloride or titanium tetrachloride. Lewis bases are used for complex formation of lanthanum series rare earth element compounds, with compounds such as acetylacetone, ketones or alcohols being suitable.

In the polymerization of butadiene, the rare earth-based catalyst may be used in a state dissolved in an organic solvent (n-hexane, cyclohexane, n-heptane, toluene, xylene, benzene, etc.), and suitable carriers such as silica, magnesia, magnesium chloride, and the like. You may use it on it. The polymerization conditions may be either solution polymerization or bulk polymerization, a preferable polymerization temperature is -30 to 150 ° C, and the polymerization pressure may be arbitrarily selected according to other conditions.

In the rare earth system BR, the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is preferably 1.2 or more, and more preferably 1.5 or more. If it is less than 1.2, workability tends to be significantly deteriorated. The Mw / Mn is preferably 5 or less, more preferably 4 or less. When it exceeds 5, there exists a tendency for the improvement effect of abrasion resistance to fall.

Mw of the rare earth system BR is preferably 300,000 or more, more preferably 500,000 or more, and preferably 1.5 million or less, and more preferably 1.2 million or less. Further, Mn of the rare earth-based BR is preferably 100,000 or more, more preferably 150,000 or more, and preferably 1 million or less, and more preferably 800,000 or less. If Mw or Mn is less than the lower limit, there is a tendency for wear resistance to deteriorate and fuel efficiency to deteriorate. If the upper limit is exceeded, workability may deteriorate.

In the present invention, the values of Mw and Mn are values determined by using a gel permeation chromatograph (GPC) and adjusting to polystyrene standards.

The sheath content of the rare earth-based BR is preferably 90% by mass or more, more preferably 93% by mass or more, even more preferably 95% by mass or more. If the sheath content is less than 90% by mass, wear resistance and fuel efficiency may be lowered.

The vinyl content of the rare earth-based BR is preferably 1.8% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.5% by mass or less, particularly preferably 0.3% by mass or less. If the vinyl content exceeds 1.8% by mass, wear resistance may be lowered.

In the present invention, the vinyl content (amount of 1,2-butadiene base unit) and the cis content (amount of cis-1,4-butadiene base unit) of the rare earth system BR can be measured by infrared absorption spectrum analysis.

BR content in 100 mass% of rubber components becomes like this. Preferably it is 20 mass% or more, More preferably, it is 30 mass% or more. The BR content is preferably 60 mass% or less, more preferably 50 mass% or less. When the BR content is within the above range, it provides good durability while maintaining good steering stability, fuel efficiency and elongation at break.

The process oil loosens the sulfur-crosslinked polymer structure, thereby promoting the migration of sulfur. The sulfur migration promoting effect of the process oil is greater than other softeners such as C5 resins. In addition, since the crosslinking density of the rubber composition for sidewalls is relatively low, sulfur inflow from carcass can be further suppressed if the rubber composition has a low process oil content. Therefore, the content of the process oil is preferably 10 parts by mass or less with respect to 100 parts by mass of the rubber component. When it exceeds 10 parts by mass, the inflow of sulfur from the carcass increases, which may lower the durability.

You may mix | blend carbon black with the rubber composition for sidewalls. By incorporating carbon black, reinforcement can be improved, and as a result, durability and steering stability can be improved. Examples of carbon blacks that can be used include, but are not limited to, GPF, FEF, HAF, ISAF, SAF, and the like.

In the case of using carbon black, the nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is preferably 20 m ² / g or more. If the N ₂ SA is less than 20 m ² / g, durability and steering stability may be degraded. N ₂ SA of the carbon black is 100 m ² / g or less is preferable, more preferably 60 m ² / g or less. If the N ₂ SA exceeds 100 m ² / g, there is a fear that sufficient fuel efficiency and processability may not be obtained.

Here, the nitrogen adsorption specific surface area of carbon black is calculated | required by JISK6217-2: 2001.

The content of the carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 10 parts by mass, sufficient reinforcement cannot be obtained and durability and steering stability tend to be deteriorated. The content of the carbon black is preferably 100 parts by mass or less, and more preferably 70 parts by mass or less with respect to 100 parts by mass of the rubber component. If it exceeds 100 parts by mass, fuel efficiency may deteriorate.

In addition to the components described above, the rubber composition contains a compounding agent commonly used in the rubber industry, for example, fillers (such as silica), waxes, antioxidants, antioxidants, vulcanizing agents (stearic acid, zinc oxide, etc.), vulcanization accelerators, and the like. Also good.

Examples of the vulcanization accelerator include guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based and xanthate-based compounds. These vulcanization accelerators may be used alone or in combination of two or more thereof. Among these, sulfenamide-based vulcanization accelerators (for example, N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS) and N-cyclohexyl-2-) from the viewpoint of dispersibility in the rubber composition and physical property stability of the vulcanizate. Benzothiazolyl sulfenamide (CBS), N, N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS), N, N-diisopropyl-2-benzothiazole sulfenamide), and TBBS is More preferred.

The compounding quantity of a vulcanization accelerator becomes like this. Preferably it is 0.4 mass part or more with respect to 100 mass parts of rubber components. Moreover, 2.0 mass parts or less are preferable, and, as for the said compounding quantity, 1.5 mass parts or less are more preferable. When the compounding amount of the vulcanization accelerator is within the above range, crosslinking density and crack growth resistance suitable as sidewall rubber can be obtained, and the amount of sulfur shifting can be adjusted to an appropriate amount, and thus the effect of the present invention can be more successfully obtained.

A well-known method can be used for the manufacturing method of the rubber composition for side walls. For example, each component can be manufactured by the method of kneading | mixing using rubber kneading apparatuses, such as an open roll mill and a Banbury mixer.

(Rubber composition for carcass cord coating)

Although it does not specifically limit as a rubber which can be used for the rubber component of the carcass cord coating rubber composition, The diene type rubber like the above-mentioned rubber composition for sidewalls can be used. Rubber may be used independently and may use 2 or more types together. Especially, NR or SBR is preferable at the point which can ensure favorable durability, maintaining good steering stability, fuel efficiency, and elongation at break, and it is more preferable to use NR and SBR together. Moreover, the combination of NR, SBR, and BR is also preferable because it can improve crack growth resistance.

NR is not specifically limited, The same thing as the rubber composition for sidewalls mentioned above can be used.

NR content in 100 mass% of rubber components becomes like this. Preferably it is 50 mass% or more, More preferably, it is 60 mass% or more. The said NR content becomes like this. Preferably it is 90 mass% or less, More preferably, it is 80 mass% or less. If the NR content is within the above range, good durability is ensured while maintaining good steering stability, fuel efficiency, and elongation at break.

SBR is not particularly limited, and those generally used in the tire industry, such as emulsion polymerization styrene butadiene rubber (E-SBR) and solution polymerization styrene butadiene rubber (S-SBR), can be used. Among these, E-SBR is preferable in that good durability can be obtained while maintaining good steering stability, fuel efficiency, and elongation at break.

SBR content in 100 mass% of rubber components becomes like this. Preferably it is 10 mass% or more, More preferably, it is 20 mass% or more. The said SBR content becomes like this. Preferably it is 50 mass% or less, More preferably, it is 40 mass% or less. If the SBR content is within this range, it provides good durability while maintaining good steering stability and fuel efficiency and elongation at break.

The vulcanizing agent which can be used is not specifically limited, The same thing as the rubber composition for sidewalls mentioned above can be used.

It is preferable that it is more than 1.91 mass parts with respect to 100 mass parts of rubber components, and, as for the sulfur content of the rubber composition for carcass cord coating, it is more preferable that it exceeds 2.41 mass parts. At 1.91 parts by mass or less, the adhesiveness with the carcass cord may decrease, resulting in a decrease in durability. In addition, there is a fear that sufficient fuel efficiency and elongation at break cannot be obtained. The content is preferably less than 3.5 parts by mass, more preferably less than 3.1 parts by mass, still more preferably less than 3.0 parts by mass. At 3.5 parts by mass or more, the elongation at break and the resistance to crack growth are lowered, resulting in a decrease in durability. In addition, there is a fear that sufficient fuel efficiency may not be obtained. If the sulfur content is within the above range, while maintaining good steering stability and fuel efficiency, good elongation at break, crack growth resistance, and adhesiveness with a carcass cord can be obtained, resulting in good durability.

As for content of process oil, 4-12 mass parts is preferable with respect to 100 mass parts of rubber components. When the content of the process oil is within the above range, good sheet formability can be obtained, and the sulfur transfer amount can be adjusted to an appropriate amount.

You may mix | blend carbon black with the rubber composition for carcass cord coating | cover. By combining carbon black, reinforcement can be increased, thereby improving durability and steering stability.

In the case of using carbon black, the nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is preferably 40 m ² / g or more, more preferably 60 m ² / g or more. If N ₂ SA is less than 40 m ² / g, the durability and the steering stability may be lowered. Also, N ₂ SA of the carbon black and is 150 m ² / g or less preferably, and more preferably 100 m ² / g or less. If the N ₂ SA exceeds 150 m ² / g, the dispersibility may deteriorate and there is a fear that sufficient fuel efficiency may not be obtained.

The content of the carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 10 parts by mass, sufficient reinforcement cannot be obtained and durability and steering stability tend to be deteriorated. Moreover, content of carbon black is preferably 90 mass parts or less, More preferably, it is 60 mass parts or less with respect to 100 mass parts of rubber components. If it exceeds 90 parts by mass, fuel efficiency may be deteriorated.

In order to improve the adhesion with the cord, the rubber composition for coating the carcass cord is at least selected from resorcinol resin (condensate), modified resorcinol resin (condensate), cresol resin, and modified cresol resin. One type of compound may be combined with the methylene donor.

The rubber composition may contain, in addition to the above components, a compounding agent, a filler (for example, silica), a wax, an antioxidant, an anti-aging agent, a vulcanizing agent (stearic acid, zinc oxide, etc.), a vulcanization accelerator, and the like used in the existing rubber industry. .

As a vulcanization accelerator, the same thing as the rubber composition for sidewalls mentioned above can be used suitably.

The content of the vulcanization accelerator is preferably 0.3 parts by mass or more, more preferably 0.8 parts by mass or more, and still more preferably 0.9 parts by mass or more based on 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 2.5 mass parts or less, More preferably, it is 1.7 mass parts or less. When the content of the vulcanization accelerator is within the above range, a suitable crosslinking density can be obtained with the carcass cord coated rubber, and at the same time, the amount of sulfur migration can be appropriately adjusted, and the effect of the present invention is more successfully obtained.

As a manufacturing method of the rubber composition for carcass cord coating, the same method as the rubber composition for sidewalls mentioned above can be used.

The pneumatic tire of the first aspect of the present invention can be manufactured by a general method using the above-described rubber composition. That is, the rubber composition of the pre-vulcanization stage which mix | blended various additives as needed was extruded to the shape of each member of a tire (in the case of a sidewall, the rubber composition for sidewalls is formed in the form of a sidewall, The case is formed in the form of a carcass by pressing and coating the carcass cord coating rubber composition in the form of a sheet before vulcanization from above and below on a carcass cord), and molding in a conventional manner on a tire forming machine and joining together with other tire members. After forming the unvulcanized tire, the tire can be manufactured by heating and pressing in a vulcanizer.

Examples of carcass cords include cords produced from fibers such as polyethylene, nylon, aramid, glass fiber, polyester, rayon, polyethylene terephthalate and the like. You can also use hybrid cords made from different types of fibers.

Second Embodiment of the Invention

The second type of pneumatic tire of the present invention includes a clinch and a carcass. The clinch contains a rubber component and is composed of a rubber composition for clinch having a sulfur content of more than 1.71 parts by mass and less than 2.9 parts by mass with respect to 100 parts by mass of the rubber component. Carcass is comprised with the carcass cord coated with the rubber composition for carcass cord coating containing a rubber component. The sulfur content of the rubber composition for clinching and the rubber composition for coating a carcass cord satisfies the following expression.

When sulfur transfers from the carcass to the clinch, the crosslinking density of the clinch rubber increases, the elongation at break of the clinch rubber is greatly deteriorated, and separation is likely to occur on the dip surface in contact with the carcass, and the durability is greatly deteriorated. On the other hand, in the carcass whose sulfur is reduced by the above-described movement, the sulfur concentration around the carcass cord is lowered, and the sulfur necessary for the recombination of sulfur between the carcass cord and the rubber composition for coating the carcass cord is insufficient and durability is lowered.

On the contrary, when sulfur moves from the clinch to the carcass, if the amount of movement is large, the hardness (Hs) of the clinch decreases, resulting in a decrease in rim-slip resistance (durability) and steering stability. And although the amount of sulfur of carcass increases and adhesiveness with a carcass cord improves, crack growth resistance falls, and durability falls.

On the other hand, in the second aspect of the present invention, since the sulfur content of the rubber composition for clinching and the rubber composition for coating the carcass cord satisfies the above relation, the sulfur composition is contained in the rubber composition for clinching, so that the sulfur is moved. It is possible to appropriately adjust the amount of sulfur movement by suppressing this, so that good durability can be obtained while maintaining good steering stability, fuel efficiency, and elongation at break.

The second type of pneumatic tire of the present invention includes a clinch and a carcass.

The clinch is a rubber part that covers the contact with the rim located at the inner edge of the sidewall, also known as a clinch apex or rubber chafer. Specifically, for example, the member shown in Fig. 1 and the like of Japanese Patent Laid-Open No. 2008-75066. Carcass is as described above.

In a second form of the invention, the clinch is made of a rubber composition for clinching, and the carcass is made of a carcass cord coated with the rubber composition for carcass cord coating.

In the second aspect of the present invention, the sulfur content of the rubber composition for clinching and the rubber composition for coating a carcass cord satisfies the following relationship. Thereby, the durability of a pneumatic tire can be improved suitably. In the case of -0.6 or less, sulfur moves from the clinch to the carcass, resulting in a decrease in hardness (Hs) of the clinch, resulting in a decrease in rim-slip resistance (durability) and steering stability. In the case of 1.1 or more, sulfur moves from the carcass to the clinch, and the elongation at break is lowered at the clinch, and the adhesion to the carcass cord is lowered at the carcass, resulting in lower durability.

As for the minimum of the said relational formula, -0.4 is preferable and -0.2 is more preferable.

Below, the rubber composition for clinch used by the 2nd aspect of this invention is demonstrated. The rubber composition for coating a carcass cord is the same as the first aspect of the present invention described above.

(Rubber composition for cleaning)

The vulcanizing agent which can be used for the rubber composition for clinch is not particularly limited, and the same vulcanizing agent as the rubber composition for sidewalls described above can be suitably used. Like the rubber composition for sidewalls, sulfur is preferable as the vulcanizing agent, and it is also preferable to mix an alkylphenol-sulfur chloride condensate with sulfur.

The content of the alkylphenol-sulfur chloride condensate is preferably 0.2 parts by mass or more and more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 0.2 mass part, the effect (particularly fuel efficiency) which mix | blended the alkylphenol-sulfur chloride condensate is not fully acquired. Preferably the said content is 6 mass parts or less, More preferably, it is 2 mass parts or less. When it exceeds 6 mass parts, there exists a possibility that durability (especially elongation at break) may fall large.

In the rubber composition for clinching, the sulfur content exceeds 1.71 parts by mass, preferably exceeds 1.81 parts by mass, and more preferably exceeds 1.91 parts by mass with respect to 100 parts by mass of the rubber component. At 1.71 parts by mass or less, the inflow rate of sulfur from the carcass increases, the elongation at break of the clinch rubber is greatly deteriorated, and separation is likely to occur at the dip surface in contact with the carcass, and the durability is greatly deteriorated. In addition, sufficient steering stability and fuel efficiency will not be achieved. The content is less than 2.9 parts by mass, preferably less than 2.7 parts by mass, more preferably less than 2.5 parts by mass. At 2.9 parts by mass or more, abrasion resistance is lowered due to heat oxidation degradation of the clinch rubber itself, and cracks are generated at the abraded portion, thereby reducing durability. When the sulfur content is within the above range, good fracture elongation, crack growth resistance, and wear resistance can be obtained while maintaining good steering stability and fuel efficiency, and as a result, good durability is secured.

Although the rubber which can be used for the rubber component of the rubber composition for clinch is not specifically limited, The diene type rubber like the above-mentioned rubber composition for sidewalls can be used. Rubber may be used independently and may use two or more types together. Especially, NR or BR is preferable at the point which can ensure favorable durability, maintaining good steering stability, fuel efficiency, and elongation at break, and it is more preferable to use NR and BR together.

NR content in 100 mass% of rubber components becomes like this. Preferably it is 10 mass% or more, More preferably, it is 20 mass% or more. The said NR content becomes like this. Preferably it is 50 mass% or less, More preferably, it is 40 mass% or less. If the NR content is within the above range, good durability is ensured while maintaining good steering stability, fuel efficiency, and elongation at break.

BR is not specifically limited, The same thing as the rubber composition for sidewalls mentioned above can be used. Among them, BR (VCR) containing the rare earth-based BR or 1,2-syndiotactic polybutadiene crystal described above is preferable in that good durability can be ensured while maintaining good steering stability, fuel efficiency, and elongation at break. Do. In addition, using tin-modified BR together with the rare earth-based BR can further improve fuel efficiency.

BR content in 100 mass% of rubber components becomes like this. Preferably it is 50 mass% or more, More preferably, it is 60 mass% or more. The BR content is preferably 90% by mass or less, more preferably 80% by mass or less. If the BR content is within the above range, good durability is ensured while maintaining good steering stability, fuel efficiency, and elongation at break.

Since the crosslinking density of the clinch rubber composition is relatively high, the content of the process oil is not particularly limited, but is preferably 3 to 12 parts by mass and more preferably 3 to 7 parts by mass with respect to 100 parts by mass of the rubber component. If the content of the process oil is in the above range, the amount of sulfur shift can be adjusted to an appropriate level.

It is preferable to mix | blend carbon black with the rubber composition for clinch. By incorporating carbon black, reinforcement can be improved, and as a result, durability and steering stability can be improved.

In the case of using carbon black, the nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is preferably 40 m ² / g or more, more preferably 60 m ² / g or more. If the N ₂ SA is less than 40 m ² / g, durability and steering stability may be degraded. In addition, N ₂ SA of the carbon black is 150 m ² / g or less are preferred, 100 m ² / g or less is more preferable. If the N ₂ SA exceeds 150 m ² / g, there is a fear that a sufficient fuel efficiency may not be obtained.

The content of the carbon black is preferably 30 parts by mass or more, and more preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 30 parts by mass, sufficient reinforcement cannot be obtained, and durability and steering stability tend to deteriorate. The content of the carbon black is preferably 120 parts by mass or less, and more preferably 80 parts by mass or less with respect to 100 parts by mass of the rubber component. If it exceeds 120 parts by mass, fuel efficiency may deteriorate.

The amount of the vulcanization accelerator (preferably sulfenamide vulcanization accelerator) is preferably 2.5 parts by mass or more, more preferably 2.8 parts by mass or more based on 100 parts by mass of the rubber component. Moreover, as for the said compounding quantity, 3.5 mass parts or less are preferable. When the amount of the vulcanization accelerator is in the above range, a crosslinking density suitable as a clinch rubber can be obtained, so that the amount of sulfur movement can be adjusted to an appropriate level with good steering stability and fuel efficiency, and as a result, the effect of the present invention can be more successfully obtained. Can be.

As a manufacturing method of the rubber composition for clinch, the method similar to the rubber composition for sidewalls mentioned above can be used.

The pneumatic tire of the second aspect of the present invention can be manufactured by a general method using the above-described rubber composition. That is, if necessary, the rubber composition of the pre-vulcanization stage in which various additives are blended is extruded into the shape of each member of the tire (in the case of a clinch, the rubber composition for clinch is formed in the form of a clinch, and in the case of carcass) The rubber composition for covering the carcass cord in the form of a sheet before vulcanization is formed in the form of carcass by compression coating on the carcass cord from the top and the bottom), molded in a conventional manner on a tire forming machine, and joined together with other tire members, After the sulfur tire is formed, the tire can be manufactured by heating and pressing in a vulcanizer.

As a carcass code, the same thing as the 1st form of this invention mentioned above can be used.

Hereinafter, the present invention will be described in detail with reference to Examples. However, the present invention is not limited only to these examples.

Below is a list of various chemicals used in the Examples and Comparative Examples.

NR: TSR20

SBR: Zebra Corporation manufactured SBR1502 (E-SBR)

BR1: CB24 manufactured by LANXESS KK (BR synthesized using an Nd catalyst; Tg: -116 ° C; cis content: 96% by mass; vinyl content: 0.7% by mass; ML ₁ ₊₄ (100 ° C): 45; Mw / Mn: 2.69; Mw: 500,000; Mn: 186,000)

BR2: BR1250H (tin modified BR) manufactured by Zeon Corporation

Carbon Black 1: DIABLACK H (N330; N ₂ SA: 79 m ² / g) manufactured by Mitsubishi Chemical Corporation

Carbon black 2: DIABLACK E (N550; N ₂ SA: 41 m ² / g) manufactured by Mitsubishi Chemical Corporation

Silica: ULTRASIL VN3 manufactured by Degussa (N ₂ SA: 175 m ² / g)

Antioxidant: Sumitomo Chemical Co., Ltd. ANTIGENE 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine)

SUMIKANOL 620: Taoka Chemical Co., Ltd. Manufacture Modified Resorcinol Resin

SUMIKANOL 507A: Taoka Chemical Co., Ltd. Manufacture Methylene Donor

Zinc Oxide: Mitsui Mining & Smelting Co., Ltd. Manufacture Zinc Oxide # 1

Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation

Insoluble sulfur with 10% oil: Nippon Kanryu Industry Co., Ltd. Manufacture SEIMI OT

TBBS: Ouchi Shinko Chemical Industrial Co., Ltd. Manufacture NOCCELER NS (N-tert-butyl-2-benzothiazolyl sulfenamide)

Process Oil: H & R Manufacture TDAE

Wax: Nippon Seiro Co., Ltd. Manufacturer Ozoace 0355

V200: Taoka Chemical Co., Ltd. Production TACKIROL V200 (Alkylphenol-sulfur chloride condensate (sulfur content: 24 mass%, mass average molecular weight: 9,000), R = C ₈ H _{17 in} formula (1); x = 2; y = 2; m = 0? Integer of 100)

TS3101: Taoka Chemical Co., Ltd. Preparation TS3101 (alkylphenol-sulfur chloride condensate (sulfur content: 27 mass%, mass average molecular weight: 62,000), R = C ₁₂ H ₂₅ of the formula (1); x = 2; y = 2; m = 170? 210 Integer)

C5 resin: Maruzen Petrochemical Co., Ltd. Manufacture Marukarez T-100AS

(Examples and Comparative Examples)

According to the compounding quantity of Tables 1-3, materials other than SUMIKANOL 507A, a vulcanizing agent, and a vulcanization accelerator were knead | mixed for 5 minutes at 150 degreeC using the Banbury mixer, and the mixed dough was obtained. Then, SUMIKANOL 507A, a vulcanizing agent and a vulcanization accelerator were added to the obtained mixed dough, and kneaded at 80 ° C. for 3 minutes using an open roll mill to obtain an unvulcanized rubber composition. A part of the obtained unvulcanized rubber composition was vulcanized under pressure at 170 ° C. for 12 minutes to obtain a vulcanized rubber composition.

In addition, another part of the obtained unvulcanized rubber composition is molded into a clinch shape in the case of a rubber composition for clinching, and in the case of a rubber composition for carcass cord coating, a 1.2 mm thick coating rubber sheet is molded and then the sheet is formed. It shape | molded in the carcass shape by the method of coat | covering a carcass cord (polyester cord), and in the case of the rubber composition for sidewalls, it shape | molded in the sidewall shape. And the test pneumatic tire (195 / 65R15) was produced by joining with the other tire member according to the combination shown in Table 2 and Table 3, and pressurizing and vulcanizing at 170 degreeC for 12 minutes.

The following evaluation was performed using the obtained vulcanized rubber composition and a test pneumatic tire. Each test result is shown in Tables 1-3.

(Complex modulus (hardness; E ^* ), fuel efficiency (tanδ))

Loss tangent and complex modulus (E ^* ) of each vulcanized rubber composition under conditions of temperature 70 ° C., initial strain 10%, dynamic strain 2%, frequency 10 Hz using a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho Co., Ltd.) ) Was measured.

Smaller tan δ values indicate lower rolling resistance and better fuel efficiency. Larger E ^* indicates better steering stability.

(Tension test)

Using a No. 3 dumbbell-shaped test piece made of a vulcanized rubber composition, a tensile test was performed at room temperature in accordance with JIS K 6251 "Vulcanized Rubber or Thermoplastic Rubber-How to Obtain Tensile Stress-Strain Properties" to measure elongation at break EB (%). The larger the EB, the better the elongation at break.

(Drum durability (high load endurance drum test))

Maximum load (maximum internal pressure) of the JIS standard Under the condition of 230% load, the tire was drum-run at a speed of 20 km / h, and the travel distance until the tire was damaged was measured. And the index of the reference tire was set to 100, and the mileage of each tire was represented by the durability index using the following calculation formula. Higher durability index indicates superior durability and better performance.

The reference tire was a pneumatic tire which combined the rubber composition A for carcass cord coating and the rubber composition I for sidewall in Table 2, and the pneumatic tire which combined the rubber composition A for carcass cord coating and the rubber composition I for clinching in Table 3. .

The drum durability evaluation result is italic, and a comparative example, and the evaluation result is not italic, is an example.

(Durability index) = (mileage of each tire) / (mileage of the reference tire) × 100

As shown in Table 1 and Table 2, a pneumatic tire with sidewalls and carcass, wherein the sidewalls are made of a rubber composition for sidewalls containing a certain amount of sulfur, and the carcass is coated with a rubber composition for carcass cord coating. The pneumatic tire produced by the carcass cord and whose sulfur content of the rubber composition for sidewalls and the rubber composition for carcass cord coating satisfy | fills a specific relationship was excellent in durability. Good steering stability, fuel efficiency and elongation at break were also obtained.

The pneumatic tire produced using the rubber composition H for sidewalls which has more process oil content than the rubber composition A for sidewalls was inferior to the pneumatic tire produced using the rubber composition A for sidewalls.

The durability of the pneumatic tire produced using the rubber composition A for carcass cord coating was very excellent. The pneumatic tire produced using the rubber composition F for carcass cord coating was very excellent in fuel efficiency.

As shown in Tables 1 and 3, pneumatic tires with clinch and carcass, wherein the clinch is made of a rubber composition for clinch containing a certain amount of sulfur, and carcass is coated with a carcass cord coating rubber composition The pneumatic tire which was produced by the cord and whose sulfur content of the rubber composition for clinching and the rubber composition for coating a carcass cord satisfies a specific relational expression was excellent in durability. Good steering stability, fuel efficiency and elongation at break were also obtained.

The pneumatic tire produced using the clinch rubber composition H which has more process oil content than the rubber composition A for clinch was inferior to the pneumatic tire produced using the rubber composition A for clinch.

The pneumatic tires produced using the rubber composition E for clinch having less content of a vulcanization accelerator than the rubber composition A for clinching were inferior to the pneumatic tires produced using the rubber composition A for clinching.

The durability of the pneumatic tire using the rubber composition A for carcass cord coating was very excellent.

Claims

A pneumatic tire comprising a sidewall and a carcass,
The said side wall is produced from the rubber composition for side walls containing a rubber component and whose sulfur content is more than 1.41 mass parts and less than 2.5 mass parts with respect to 100 mass parts of rubber components,
The carcass is made of a carcass cord coated with a rubber composition for coating a carcass cord including a rubber component,
The pneumatic tire of which the sulfur content of the said rubber composition for sidewalls and the said rubber composition for carcass cord coating satisfies the following formula.
-0.2 <(sulfur content with respect to 100 mass parts of rubber components of the rubber composition for carcass cord coating)-(sulfur content with respect to 100 mass parts of the rubber component of the rubber composition for sidewalls) <1.1

The pneumatic tire according to claim 1, wherein the sulfur content of the rubber composition for sidewalls is more than 1.61 parts by mass and less than 2.3 parts by mass with respect to 100 parts by mass of the rubber component.

The pneumatic tire according to claim 1, wherein the sulfur content of the carcass cord coating rubber composition is greater than 1.91 parts by mass and less than 3.5 parts by mass with respect to 100 parts by mass of the rubber component.

The pneumatic tire according to claim 1, wherein the process oil content of the rubber composition for sidewalls is 10 parts by mass or less based on 100 parts by mass of the rubber component.

The pneumatic tire according to claim 1, wherein the alkylphenol-sulfur chloride condensate content of the rubber composition for the sidewall is 0.2 to 6 parts by mass with respect to 100 parts by mass of the rubber component.

A pneumatic tire comprising clinch and carcass,
The clinch is made of a rubber composition for clinch containing a rubber component and having a sulfur content of more than 1.71 parts by mass and less than 2.9 parts by mass with respect to 100 parts by mass of the rubber component,
The carcass is made of a carcass cord coated with a rubber composition for coating a carcass cord including a rubber component,
A pneumatic tire wherein the sulfur content of the rubber composition for clinching and the rubber composition for coating a carcass cord satisfies the following expression.
-0.6 <(sulfur content with respect to 100 mass parts of rubber components of the rubber composition for carcass cord coating)-(sulfur content with respect to 100 mass parts of the rubber component of the rubber composition for cleaning) <1.1

The pneumatic tire according to claim 6, wherein the sulfur content of the rubber composition for clinch is greater than 1.91 parts by mass and less than 2.7 parts by mass with respect to 100 parts by mass of the rubber component.

The pneumatic tire according to claim 6, wherein the sulfur content of the carcass cord coating rubber composition is more than 1.91 parts by mass and less than 3.5 parts by mass with respect to 100 parts by mass of the rubber component.

The pneumatic tire according to claim 6, wherein a content of the sulfenamide-based vulcanization accelerator of the rubber composition for clinching is 2.5 to 3.5 parts by mass based on 100 parts by mass of the rubber component.

The pneumatic tire according to claim 6, wherein the content of the alkylphenol-sulfur chloride condensate of the rubber composition for clinch is 0.2 to 6 parts by mass based on 100 parts by mass of the rubber component.