JP2008303265A - Rubber composition for clinch apex and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a clinch apex, in which the amounts of an oil resource-derived raw materials to be used are reduced and which has excellent crack resistance, a low heat generation property and excellent processability when prepared and to provide a pneumatic tire using the rubber composition. <P>SOLUTION: The rubber composition for the clinch apex contains a rubber component, an inorganic filler of 50-80 parts mass on the basis of 100 parts mass rubber component, and carbon black. The rubber component consists of at least one of natural rubber and epoxidized natural rubber. The inorganic filler contains silica. The amount of the carbon black to be blended is 2-5 parts mass on the basis of 100 parts mass rubber component. The pneumatic tire using the rubber composition for the clinch apex is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber composition for clinch apex and a pneumatic tire including a clinch apex rubber made of the rubber composition for clinch apex.

  Conventionally, a clinch apex rubber is provided in a chafing portion with a rim of a pneumatic tire. The clinch apex rubber has a function of transmitting a driving force from the rim to the tire during traveling and a function of holding the load of the tire. Therefore, the clinch apex rubber needs to have high hardness and excellent heat aging characteristics. In addition, the clinch apex rubber is also required to have predetermined wear resistance in order to reduce wear caused by rubbing with the rim due to repeated deformation of the tire during traveling. In addition, physical properties such as stiffness, hardness, and mechanical strength of clinch apex rubber have a great influence on steering stability performance during traveling, and it is also required to set these performances within an appropriate range.

  On the other hand, in recent years, methods for reducing the amount of raw materials derived from petroleum resources have been studied in various technical fields due to increasing interest in environmental problems. Currently, commercially available tires are composed of raw materials in which more than half of the total weight is petroleum resources. For example, a general tire for a passenger car contains about 20% by mass of synthetic rubber, about 20% by mass of carbon black, a softener, a synthetic fiber, and the like, so that about 50% by mass or more of the entire tire is derived from raw materials of petroleum resources. It is configured. Accordingly, it is desired to develop a rubber for tires using a raw material derived from a natural resource that satisfies the same or more required characteristics as when using a raw material derived from a petroleum resource.

  In Patent Document 1, for the purpose of reducing rolling resistance, 5 to 150 parts by weight of an inorganic filler, 0 to 30 parts by weight of a silane coupling agent, and an iodine value of 130 or less with respect to 100 parts by weight of a diene rubber. A rubber composition containing 5 to 100 parts by weight of a certain vegetable oil has been proposed.

Patent Document 2 discloses (A) a diene rubber for the purpose of providing a rubber composition for a tread and a pneumatic tire that can greatly improve wet grip performance without reducing the wear resistance and rolling resistance characteristics of the tire. Or 100 parts by weight of a rubber component comprising a mixture of diene rubber and natural rubber and containing at least 20% by weight of styrene-butadiene rubber, (B) 5 to 50 parts by weight of clay, and (C) a nitrogen adsorption specific surface area. Containing 5 parts by weight or more of silica of 100 to 300 m ² / g and (D) 1 part by weight or more of carbon black having a nitrogen adsorption specific surface area of 70 to 300 m ² / g, (B) clay and (C) silica The total amount of (B) clay, (C) silica and (D) carbon black is 100 parts by weight or less. For tire tread rubber compositions have been proposed.

  In Patent Document 3, for the purpose of providing a rubber composition for a base tread capable of reducing fuel consumption in automobile driving and a tire using the rubber composition, 100 parts by weight of a rubber component composed of natural rubber and butadiene rubber is used. A rubber composition for base treads containing 1 to 20 parts by weight of a composite material composed of starch and a plasticizer has been proposed.

  Patent Document 4 discloses a rubber component made of natural rubber and / or isoprene rubber, and butadiene rubber for the purpose of providing a rubber composition for a sidewall that enables low fuel consumption in automobile driving, and a tire using the rubber composition. A rubber composition for a sidewall containing 1 to 20 parts by weight of a composite material composed of starch and a plasticizer is proposed with respect to 100 parts by weight.

  Patent Document 5 discloses a tire rubber composition that maintains the performance required as a tire member such as air permeation resistance, crack growth resistance and hardness, and further has improved workability, and a tire obtained thereby. For the purpose of providing, 100 parts by weight of a rubber component made of natural rubber and / or a modified product thereof, 30 parts by weight or more of silica, 5 to 15 parts by weight of calcium carbonate, and 5 parts by weight or less of carbon black A rubber composition for tires to be contained has been proposed.

  Patent Document 6 discloses a rubber composition for a breaker having an excellent balance of rigidity, heat resistance, adhesion, wet heat adhesion, elongation performance, and the like, and a pneumatic tire using the rubber composition for a breaker layer or a belt layer. For 100 parts by weight of a rubber component mainly composed of natural rubber and / or isoprene rubber, 55 to 65 parts by weight of carbon black, 5 to 15 parts by weight of silica, 3.5 to 4 A rubber composition for a breaker has been proposed containing 5 parts by weight of sulfur, 0.08 parts by weight or more of cobalt, a resorcin resin and a methylene donor.

However, the conventional technology can reduce the amount of raw materials derived from petroleum resources, has excellent crack resistance, low heat generation, and excellent processability during preparation. Pneumatic tires have not been obtained.
JP 2003-64222 A JP 2002-105245 A Japanese Patent Laid-Open No. 2005-2287 JP 2005-53944 A JP 2006-89526 A JP 2002-338734 A

  The present invention solves the above-mentioned problems, reduces the amount of raw materials derived from petroleum resources, has excellent crack resistance, low heat build-up, and a rubber composition for clinch apex that is excellent in workability during preparation and An object is to provide a pneumatic tire using the same.

  The present invention contains a rubber component, an inorganic filler compounded within a range of 50 to 80 parts by mass with respect to 100 parts by mass of the rubber component, and carbon black, and the rubber component includes natural rubber and epoxidation. A rubber composition for clinch apex comprising at least one of natural rubber, the inorganic filler contains silica, and the amount of carbon black is in the range of 2 to 5 parts by mass with respect to 100 parts by mass of the rubber component. I will provide a.

  In the rubber composition for clinch apex of the present invention, the inorganic filler can be composed of at least one selected from calcium carbonate, aluminum hydroxide, clay, mica, and magnesium oxide, and silica. In this case, the total amount of calcium carbonate, aluminum hydroxide, clay, mica and magnesium oxide is preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component.

  In the rubber composition for clinch apex of the present invention, the inorganic filler may be made of silica.

  The present invention also provides a pneumatic tire provided with a clinch apex rubber comprising any one of the rubber compositions for clinch apex described above.

  According to the present invention, the use amount of raw materials derived from petroleum resources is reduced, and the rubber composition for clinch apex that has excellent crack resistance, low heat build-up, and excellent workability during preparation, and the same are used. It becomes possible to provide a pneumatic tire.

  In the rubber composition for clinch apex of the present invention, at least one of natural rubber and epoxidized natural rubber is used as a rubber component, and by using a small amount of carbon black, the use of raw materials derived from petroleum resources is used. The amount can be reduced. Moreover, the processability at the time of preparation is also good by using the rubber component and a small amount of carbon black. In the present invention, the heat generation property of the pneumatic tire can be reduced by using the rubber composition for clinch apex in which the blending amount of carbon black is small. On the other hand, in this invention, since the compounding quantity of an inorganic filler shall be in the predetermined range, favorable crack resistance is obtained with fillers other than carbon black.

<Rubber component>
The rubber component used in the present invention comprises at least one of natural rubber (NR) and epoxidized natural rubber (ENR). That is, in the present invention, since synthetic rubber derived from petroleum resources is not used, the amount of raw material derived from petroleum resources can be reduced.

  As the natural rubber (NR), those conventionally used in the rubber industry can be used, and examples thereof include natural rubber of grades such as RSS # 3 and TSR.

  Epoxidized natural rubber (ENR) is a kind of modified natural rubber in which unsaturated double bonds of natural rubber are epoxidized, and molecular cohesion is increased by epoxy groups that are polar groups. Therefore, the glass transition temperature (Tg) is higher than that of natural rubber, and the mechanical strength, abrasion resistance, and air permeation resistance are excellent. In particular, when silica is compounded in the rubber composition, due to the reaction between the silanol group on the silica surface and the epoxy group of the epoxidized natural rubber, the same degree as when carbon black is compounded in the rubber composition. The mechanical strength and wear resistance can be obtained.

  As the epoxidized natural rubber (ENR), a commercially available product may be used, or an epoxidized natural rubber (NR) may be used. The method for epoxidizing natural rubber (NR) is not particularly limited, and examples thereof include a chlorohydrin method, a direct oxidation method, a hydrogen peroxide method, an alkyl hydroperoxide method, and a peracid method. Examples of the peracid method include a method of reacting an organic peracid such as peracetic acid or performic acid as an epoxidizing agent with an emulsion of natural rubber.

  The epoxidation rate of the epoxidized natural rubber (ENR) is preferably 5 mol% or more, and more preferably 10 mol% or more. Here, the epoxidation rate means a ratio of the number of epoxidized out of the total number of double bonds in the natural rubber before epoxidation, and is obtained by, for example, titration analysis or nuclear magnetic resonance (NMR) analysis. . When the epoxidation rate of epoxidized natural rubber (ENR) is less than 5 mol%, the glass transition temperature of epoxidized natural rubber (ENR) is low, so the rubber hardness of the rubber composition for clinch apex is low. The durability and fatigue resistance of a pneumatic tire using the apex rubber composition as a clinch apex rubber tends to decrease. The epoxidation rate of the epoxidized natural rubber (ENR) is preferably 65 mol% or less, and more preferably 60 mol% or less. When the epoxidation rate of epoxidized natural rubber (ENR) exceeds 65 mol%, the rubber composition for clinch apex tends to be hard and mechanical strength tends to decrease.

  More typical examples of the epoxidized natural rubber (ENR) include an epoxidized natural rubber having an epoxidation rate of 25 mol% and an epoxidized natural rubber having an epoxidation rate of 50 mol%.

  The content of natural rubber (NR) in the rubber component is preferably 10% by mass or more. When the content of natural rubber (NR) is less than 10% by mass, the mechanical strength of the rubber composition for clinch apex tends to be low. The content of natural rubber (NR) is more preferably 30% by mass or more, and further preferably 40% by mass or more. The content of natural rubber (NR) in the rubber component is preferably 90% by mass or less. When the content of natural rubber (NR) exceeds 90% by mass, the tear strength of the rubber composition for clinch apex tends to be low. The content of natural rubber (NR) is more preferably 80% by mass or less.

  The content of epoxidized natural rubber (ENR) in the rubber component is preferably 10% by mass or more. When the content of epoxidized natural rubber (ENR) is less than 10% by mass, the tensile strength tends to decrease. The content of the epoxidized natural rubber (ENR) is more preferably 20% by mass or more, and further preferably 30% by mass or more. The content of epoxidized natural rubber (ENR) in the rubber component is preferably 70% by mass or less. When the content of epoxidized natural rubber (ENR) exceeds 70% by mass, the rubber hardness tends to be too high, and the mechanical strength of the rubber composition for clinch apex tends to be low. The content of epoxidized natural rubber (ENR) is more preferably 60% by mass or less.

<Inorganic filler>
In the rubber composition for clinch apex of this invention, an inorganic filler is mix | blended within the range of 50-80 mass parts with respect to 100 mass parts of rubber components. When the compounding amount of the inorganic filler with respect to 100 parts by mass of the rubber component is less than 50 parts by mass, desired crack resistance cannot be obtained, and when it exceeds 80 parts by mass, the workability is deteriorated. The blending amount of the inorganic filler is more preferably 55 parts by mass or more, and further preferably 60 parts by mass or more, more preferably 75 parts by mass or less, and even more preferably 70 parts by mass or less.

  The inorganic filler contains silica. Thereby, since the usage-amount of carbon black can be reduced, maintaining the mechanical strength of the rubber composition for clinch apex favorably, the usage-amount of the raw material derived from a petroleum resource can be reduced. Further, by combining carbon black in addition to the inorganic filler, it is possible to prevent deterioration of workability that occurs when a large amount of silica is used.

  The inorganic filler can be composed of at least one selected from calcium carbonate, aluminum hydroxide, clay, mica, and magnesium oxide and silica. In this case, since calcium carbonate, aluminum hydroxide, clay, mica, magnesium oxide, and silica are all derived from non-petroleum resources, the effect of reducing the amount of raw materials derived from petroleum resources is maintained while maintaining good mechanical strength. It can be obtained well.

  In the present invention, clay (that is, clay) is a general term for an aggregate of fine particles generated by weathering or metamorphism of rocks or minerals, and more typically, clay minerals having a particle size of 2 μm or less. Means the main component. Here, the clay mineral typically means crystalline or amorphous mainly composed of layered silicate.

  Specific examples of the clay include wet kaolin (unfired kaolin), fired kaolin, wet and dry wax stone clays, and clays whose surfaces are treated with a coupling agent. Among these, a clay whose surface is treated with a coupling agent is preferable in terms of excellent dispersibility in rubber.

  On the other hand, the inorganic filler can be made of silica. Also in this case, the combined use of silica derived from non-petroleum resources can achieve a good effect of reducing the amount of raw materials derived from petroleum resources while maintaining good mechanical strength.

(Carbon black)
The compounding quantity of carbon black shall be in the range of 2-5 mass parts with respect to 100 mass parts of rubber components. When the compounding amount of carbon black with respect to 100 parts by mass of the rubber component is less than 2 parts by mass, crack resistance and processability deteriorate, and when it exceeds 5 parts by mass, the effect of reducing the amount of raw materials derived from petroleum resources is reduced. Also, it becomes difficult to impart low heat build-up. The blending amount of carbon black is more preferably 3 parts by mass or more, and more preferably 4 parts by mass or less.

  The iodine adsorption specific surface area of carbon black is preferably 30 g / kg or more. In this case, the mechanical strength of the rubber composition for clinch apex is good. The iodine adsorption specific surface area of carbon black is more preferably 40 g / kg or more, and more preferably 70 g / kg or more. Moreover, it is preferable that the iodine adsorption specific surface area of carbon black is 150 g / kg or less, and in this case, workability is favorable. The iodine adsorption specific surface area of carbon black is further preferably 130 g / kg or less, more preferably 125 g / kg or less.

  As a preferable commercial product of carbon black, for example, “Dia Black H” manufactured by Mitsubishi Chemical Corporation can be exemplified.

(silica)
It is preferable that the compounding quantity of a silica shall be in the range of 25-70 mass parts with respect to 100 mass parts of rubber components. When the blending amount of silica is less than 25 parts by mass, the reinforcing effect due to blending of silica tends to be small, and when it exceeds 70 parts by mass, workability tends to decrease. The blending amount of silica is more preferably 30 parts by mass or more, and further preferably 35 parts by mass or more, and more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less.

  Moreover, when an inorganic filler contains fillers other than a silica, it is preferable that the compounding quantity of a silica shall be in the range of 30-55 mass parts with respect to 100 mass parts of rubber components. When the blending amount of silica is less than 30 parts by mass, the reinforcing effect due to blending of silica tends to be small, and when it exceeds 55 parts by mass, workability tends to decrease. The blending amount of silica is more preferably 35 parts by mass or more, and further preferably 40 parts by mass or more, more preferably 50 parts by mass or less, and further preferably 45 parts by mass or less.

The BET specific surface area of silica is preferably 100 m ² / g or more. In this case, the mechanical strength of the rubber composition for clinch apex is good. The BET specific surface area of silica is more preferably 130 m ² / g or more, and more preferably 150 m ² / g or more. Moreover, it is preferable that the BET specific surface area of a silica is 200 m < ² > / g or less, In this case, workability is favorable. The BET specific surface area of silica is more preferably 190 m ² / g or less, and further preferably 180 m ² / g or less.

  Silica may be prepared by a wet method or may be prepared by a dry method. As a preferable commercial product of silica, for example, “Ultrasil VN3” manufactured by Degussa can be exemplified.

(Other fillers that can be blended as inorganic fillers)
Examples of the filler that can be blended in addition to silica as the inorganic filler in the present invention include the aforementioned calcium carbonate, aluminum hydroxide, clay, mica, magnesium oxide and the like. In particular, among inorganic fillers, fillers other than silica (hereinafter also simply referred to as other fillers) are preferably made of calcium carbonate, aluminum hydroxide, clay, mica, and magnesium oxide.

  Among the inorganic fillers of the present invention, the total amount of other fillers is preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. When the total amount of the other fillers is less than 20 parts by mass, the workability tends to be low because the amount of silica increases. The total amount is preferably 22 parts by mass or more, more preferably 25 parts by mass or more. On the other hand, when the total amount exceeds 50 parts by mass, the reinforcing effect tends to be reduced by reducing the amount of silica, so the total amount is preferably 50 parts by mass or less. Furthermore, it is more preferable that it is 40 mass parts or less, and also 30 mass parts or less.

  Moreover, it is preferable that the compounding quantity of a calcium carbonate exists in the range of 20-40 mass parts with respect to 100 mass parts of rubber components. When the blending amount of calcium carbonate is less than 20 parts by mass, the blending amount of silica tends to decrease because of the increased blending amount of silica, and when it exceeds 40 parts by mass, the blending amount of silica decreases to reduce the blending amount. The effect tends to be low. The blending amount of calcium carbonate is more preferably 25 parts by mass or more, and more preferably 35 parts by mass or less.

<Silane coupling agent>
In the present invention, silica is blended. Therefore, when a silane coupling agent is used in combination, an excellent reinforcing effect is preferably given to the rubber composition for clinch apex. The compounding amount of the silane coupling agent is preferably in the range of 4 to 12% by mass when the compounding amount of silica is 100% by mass. When the amount of the silane coupling agent is less than 4% by mass, the reinforcing effect tends to be low. When the amount exceeds 12% by mass, a significant improvement in the reinforcing effect cannot be expected even if the amount is increased, while the cost is high. It tends to be uneconomical because it rises. The blending amount of the silane coupling agent is more preferably 6% by mass or more, and more preferably 8% by mass or more.

  As the silane coupling agent, a conventionally known silane coupling agent can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4- Triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxy Silylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) ) Resulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3 -Trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-tri Ethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthio Sulfide systems such as rubamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane Mercapto type such as 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; Vinyl type such as vinyltriethoxysilane, vinyltrimethoxysilane; 3-aminopropyltriethoxysilane 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxy Amino systems such as silane; glycidoxy systems such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane Nitro compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltri Chloro-based compounds such as ethoxysilane; These silane coupling agents may be used alone or in combination of two or more.

  Of these, Si69 (bis (3-triethoxysilylpropyl) tetrasulfide), Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Degussa are preferably used because of their good processability. It is done.

<Other ingredients>
In the rubber composition for clinch apex of the present invention, in addition to the above-mentioned components, other compounding agents conventionally used in the rubber industry, such as vulcanizing agents, stearic acid, vulcanization accelerators, vulcanization acceleration aids. Oils, hardened resins, waxes, antioxidants, etc. may be added. Moreover, as a filler other than the above-mentioned silica and carbon, for example, titanium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc and the like may be used in combination.

  As the vulcanizing agent, an organic peroxide or a sulfur-based vulcanizing agent can be used. Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, and di-t-butyl peroxide. , T-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoyl) Peroxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 or 1,3-bis (t-butylperoxypropyl) benzene, di-t-butylperoxy- Diisopropylbenzene, t-butylperoxybenzene, 2,4-dichlorobenzoyl peroxide, 1,1-di t- butyl peroxy-3,3,5-trimethyl siloxane, and the like can be used n- butyl-4,4-di -t- butyl peroxy valerate. Of these, dicumyl peroxide, t-butylperoxybenzene and di-t-butylperoxy-diisopropylbenzene are preferred. Moreover, as a sulfur type vulcanizing agent, sulfur, morpholine disulfide, etc. can be used, for example. Of these, sulfur is preferred. These vulcanizing agents may be used alone or in combination of two or more. Further, sulfur may be oil-treated.

  Vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Those containing at least one of them can be used. Examples of the sulfenamide system include CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (N-tert-butyl-2-benzothiazylsulfenamide), N, N-dicyclohexyl-2- Sulfenamide compounds such as benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, and N, N-diisopropyl-2-benzothiazolesulfenamide can be used. Examples of the thiazole group include MBT (2-mercaptobenzothiazole), MBTS (dibenzothiazyl disulfide), sodium salt of 2-mercaptobenzothiazole, zinc salt, copper salt, cyclohexylamine salt, 2- (2,4-dinitro). Thiazole compounds such as phenyl) mercaptobenzothiazole and 2- (2,6-diethyl-4-morpholinothio) benzothiazole can be used. Examples of thiurams include TMTD (tetramethyl thiuram disulfide), tetraethyl thiuram disulfide, tetramethyl thiuram monosulfide, dipentamethylene thiuram disulfide, dipentamethylene thiuram monosulfide, dipentamethylene thiuram tetrasulfide, dipentamethylene thiuram hexasulfide. Further, thiuram compounds such as tetrabutylthiuram disulfide and pentamethylenethiuram tetrasulfide can be used. As the thiourea series, for example, thiourea compounds such as thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, diortolylthiourea and the like can be used. Examples of guanidine-based compounds include guanidine-based compounds such as diphenylguanidine, diortolylguanidine, triphenylguanidine, orthotolylbiguanide, and diphenylguanidine phthalate. Examples of dithiocarbamate include zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diamyldithiocarbamate, zinc dipropyldithiocarbamate , Complex salt of zinc pentamethylenedithiocarbamate and piperidine, zinc hexadecyl (or octadecyl) isopropyldithiocarbamate, zinc dibenzyldithiocarbamate, sodium diethyldithiocarbamate, piperidine pentamethylenedithiocarbamate, selenium dimethyldithiocarbamate, tellurium diethyldithiocarbamate, diamyl Di, such as cadmium dithiocarbamate And the like can be used Okarubamin acid compound. As the aldehyde-amine system or aldehyde-ammonia system, for example, an aldehyde-amine system or aldehyde-ammonia system compound such as acetaldehyde-aniline reaction product, butyraldehyde-aniline condensate, hexamethylenetetramine, acetaldehyde-ammonia reaction product, etc. is used. can do. As the imidazoline-based compound, for example, an imidazoline-based compound such as 2-mercaptoimidazoline can be used. As the xanthate type, for example, a xanthate type compound such as zinc dibutylxanthate can be used. These vulcanization accelerators may be used alone or in combination of two or more.

  As the anti-aging agent, amine-based, phenol-based, imidazole-based, carbamic acid metal salts, and the like can be appropriately selected and used.

  Examples of the oil include process oil, vegetable oil and fat, or a mixture thereof. Examples of the process oil include paraffinic process oil, naphthenic process oil, and aromatic process oil. Vegetable oils include castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, cocoon oil, jojoba oil, macadamia nut oil, safflower oil, tung oil, and the like.

  The rubber hardness (that is, JIS-A hardness) measured by the hardness test method (JIS K6253) of the rubber composition for clinch apex of the present invention is preferably in the range of 60-80. When the rubber hardness is less than 60, the rigidity of the rubber composition for clinch apex is low and the durability of the pneumatic tire tends to decrease. On the other hand, when the rubber hardness exceeds 80, the rubber composition for clinch apex becomes hard and the mechanical strength tends to decrease. The rubber hardness is more preferably 65 or more, and further preferably 75 or more.

  The present invention also provides a pneumatic tire provided with a clinch apex rubber comprising the rubber composition for clinch apex of the present invention as described above. Hereinafter, the pneumatic tire of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view illustrating the left half of a pneumatic tire according to the present invention. The pneumatic tire 1 includes a tread portion 2, a pair of sidewall portions 3 extending inward in the tire radial direction from both ends of the tread portion 2, and a bead portion 4 positioned at an inner end of each sidewall portion 3. Prepare. A carcass 6 is bridged between the bead portions 4 and 4, and a belt layer 7 is provided outside the carcass 6 and inside the tread portion 2 to reinforce the tread portion 2 with a tagging effect.

  The carcass 6 is formed of one or more carcass plies in which the carcass cord is arranged at an angle of, for example, 70 to 90 ° with respect to the tire equator CO. The carcass ply extends from the tread portion 2 to the sidewall portion 3. After that, the periphery of the bead core 5 of the bead portion 4 is folded back from the inner side in the tire axial direction to be locked.

  The belt layer 7 is composed of two or more belt plies in which the belt cords are arranged at an angle of, for example, 40 ° or less with respect to the tire equator CO. The belt layers 7 are stacked in different directions so that the belt cords cross each other. is doing. If necessary, a band layer (not shown) for preventing lifting at both ends of the belt layer 7 may be provided at least outside the belt layer 7. At this time, the band layer is formed of a low modulus organic fiber. The cord is formed of a continuous ply spirally wound substantially parallel to the tire equator CO.

  Further, a bead apex rubber 8 extending radially outward from the bead core 5 is disposed in the bead portion 4, and an inner liner rubber 9 forming a tire lumen surface is adjacent to the inside of the carcass 6. The outside of the carcass 6 is protected by the clinch apex rubber 4G and the side wall rubber 3G. The rubber composition for clinch apex of the present invention is used for the clinch apex rubber 4G.

  Although FIG. 1 illustrates a pneumatic tire for a passenger car, the present invention is not limited to this, and air used for various vehicles such as a passenger car, a truck, a bus, and a heavy vehicle. Provide filled tires.

  The pneumatic tire of the present invention is produced by a conventionally known method using the rubber composition for clinch apex of the present invention. In other words, the rubber composition for clinch apex containing the above-described essential components and other compounding agents blended as necessary is kneaded and extruded in accordance with the shape of the tire clinch at the unvulcanized stage. And an unvulcanized tire is formed by shape | molding with a tire molding machine with a normal method with the other member of a tire. The tire of the present invention can be obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

  Such a pneumatic tire of the present invention is reduced in the amount of use of raw materials derived from petroleum resources, particularly in clinch apex rubber, and sufficient consideration is given to resource saving and environmental protection, as well as crack resistance, low heat generation, A rubber composition for clinch apex that is highly compatible in processability at the time of preparation is used, and it is an “eco-tyre” that is friendly to the global environment, and is excellent in durability and fuel consumption.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these.

<Examples 1-11 and Comparative Examples 1-5>
Among the blending components shown in Tables 1 to 3, the blending components excluding sulfur and the vulcanization accelerator were kneaded at about 150 ° C. for 5 minutes using a banbury. An unvulcanized rubber composition obtained by adding sulfur and a vulcanization accelerator to the kneaded material obtained in the amounts shown in Tables 1 to 3 and then kneading at about 80 ° C. for 5 minutes using a biaxial open roll. Was extruded to prepare an unvulcanized rubber sheet. The obtained unvulcanized rubber sheet was vulcanized at 170 ° C. for 12 minutes to produce a test rubber sheet.

  Moreover, the unvulcanized tire was formed by forming the unvulcanized rubber sheet obtained above in a clinch apex portion and molding it together with other members of the tire by a usual method on a tire molding machine. This unvulcanized tire was heated and pressurized at 170 ° C. for 15 minutes in a vulcanizer to obtain a test tire.

The above test tire is
Carcass ply cord angle 90 degrees cord material in the tire circumferential direction Polyester 1500 denier / 2
Breaker cord angle 24 ° × 24 ° cord material in tire circumferential direction 1 × 3 × 0.27
It has the basic structure.

(Mooney viscosity ML (1 + 4) (130 ° C))
With respect to the above-mentioned unvulcanized rubber composition, Mooney viscosity (ML (1 + 4)) was measured at 130 ° C. according to JIS K6251. The smaller the value, the lower the viscosity and the better the workability.

(Tan δ)
A test piece was cut out from the rubber sheet for testing obtained above, and tan δ was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under the conditions of a temperature of 60 ° C., an initial strain of 10%, and a dynamic strain of 2%. It shows that exothermic property and rolling resistance are so low that a numerical value is small.

(Elongation at break EB)
The test rubber sheet obtained above was subjected to a tensile test using a No. 3 dumbbell according to JIS K6251, and the elongation at break EB (%) was measured. It shows that it is excellent in crack resistance, so that a numerical value is large.

(Deformation and crack resistance)
The test tire obtained above was mounted on a 2000 cc passenger car, and a running test of about 50000 km was performed. The tire deformation and cracks after running were visually evaluated according to the following criteria.

Deformation A: Deformation is not recognized.
B: Some deformation is observed.
C: Deformation is large.

Crack A: No crack is observed.
B: Some cracks are observed.
C: A lot of cracks are generated.

Note 1: Natural rubber is “RSS # 3” manufactured by Tech Bee Hang.
Note 2: The epoxidized natural rubber is “ENR25” (epoxidation rate: 25 mol%) manufactured by MRB.
Note 3: The butadiene rubber is “BR150B” manufactured by Ube Industries.
Note 4: Carbon black is “N330” (iodine adsorption specific surface area: 70 mg / g) manufactured by Tokai Carbon.
Note 5: Silica is “Ultrasil VN3” (BET specific surface area: 172 m ² / g) manufactured by Degussa.
Note 6: Calcium carbonate is “Success 200S” manufactured by Omi Chemical.
Note 7: The clay is Burgess Pigment's “Burges KE”.
Note 8: Silane coupling agent 1 is “Si266” manufactured by Degussa.
Note 9: Silane coupling agent 2 is “KBE103” manufactured by Shin-Etsu Chemical.
Note 10: Process oil is “PS32” manufactured by Idemitsu Chemical.
Note 11: Soybean oil is “soybean white squeezed oil” manufactured by Nisshin Oilio.
Note 12: Wax is “Sannokk Wax” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Note 13: The anti-aging agent is “NOCRACK 6C” (N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Note 14: Stearic acid is stearic acid manufactured by NOF Corporation.
Note 15: Zinc Hana is “Zinc Hana 1” manufactured by Mitsui Mining & Smelting.
Note 16: Sulfur is "powder sulfur" manufactured by Tsurumi Chemical Co., Ltd.
Note 17: The vulcanization accelerator is “Noxeller CZ” manufactured by Ouchi Shinsei Chemical.

  As shown in Tables 1 to 3, in Comparative Example 3 using butadiene rubber and containing a large amount of carbon black, Comparative Example 4 using butadiene rubber with a large tan δ and a small elongation at break and a small amount of carbon black. The Mooney viscosity was high. Further, in Comparative Example 5 in which no carbon black was used, the value of elongation at break was low. In the example using natural rubber, Mooney viscosity and tan δ were high in Comparative Example 1 with a large amount of carbon black, and appearance after running was inferior in Comparative Example 2 with a small amount of silica.

  On the other hand, in Examples 1 to 11 using natural rubber and / or epoxidized natural rubber and using a predetermined amount of carbon black and a predetermined amount of inorganic filler containing silica, Mooney viscosity and tan δ are reduced, and elongation at break is reduced. And the appearance after running was also good.

  Therefore, according to the present invention, the rubber composition for clinch apex, which reduces the amount of petroleum resource-derived raw materials used, has excellent crack resistance, low heat build-up, and excellent workability during preparation, and the same are used. It can be seen that a pneumatic tire can be provided.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The rubber composition for clinch apex of the present invention is suitably applied to the clinch apex rubber of pneumatic tires for various uses such as for passenger cars, trucks, buses, heavy vehicles, etc. , And can be suitably applied to the various uses described above.

It is a schematic sectional drawing which shows an example of the pneumatic tire of this invention.

Explanation of symbols

  1 tire, 2 tread part, 3 side wall part, 4 bead part, 5 bead core, 6 carcass, 7 belt layer, 8 bead apex rubber, 9 inner liner rubber, 3G side wall rubber, 4G clinch apex rubber.

Claims (4)

Containing a rubber component, an inorganic filler blended within a range of 50 to 80 parts by mass with respect to 100 parts by mass of the rubber component, and carbon black,
The rubber component consists of at least one of natural rubber and epoxidized natural rubber,
The inorganic filler contains silica;
The compounding quantity of the said carbon black is a rubber composition for clinch apex which exists in the range of 2-5 mass parts with respect to 100 mass parts of said rubber components. The inorganic filler comprises at least one selected from calcium carbonate, aluminum hydroxide, clay, mica, magnesium oxide and the silica,
The clinch apex according to claim 1, wherein a total amount of the calcium carbonate, the aluminum hydroxide, the clay, the mica, and the magnesium oxide is 20 parts by mass or more with respect to 100 parts by mass of the rubber component. Rubber composition.   The rubber composition for clinch apex according to claim 1, wherein the inorganic filler is made of the silica.   A pneumatic tire provided with the clinch apex rubber which consists of a rubber composition for clinch apex in any one of Claims 1-3.

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