JP2007112834A - Rubber composition for tire and pneumatic tire by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for tire having a high stiffness and low cost, without reducing processability, and a pneumatic tire by using the same. <P>SOLUTION: This rubber composition is provided by blending within ranges of 0.5-50 pts.mass paper fiber and 0.5-20 pts.mass phenol-based cured resin based on 100 pts.mass diene-based rubber, and the pneumatic tire by using the same is also provided. In the rubber composition for tire, it is preferable that the ratio of (A) complex modulus at 100°C to (B) complex modulus at 70°C, (A)/(B)×100 (%) is made within a range of 50-100%. Also, it is preferable that the ratio of the mean length (L) to the mean longer diameter (D) of the paper fiber, (L)/(D) is made as ≥10, and the mean length (L) is made as ≥10 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rubber composition for tires that can be manufactured with good processability and is low in cost and high in rigidity, and a pneumatic tire using the same.

  In recent years, due to improvement in performance of automobiles and development of a road network, improvement in handling stability of tires, in particular, handling stability at high speeds, has been demanded. In order to improve the handling stability, it is known that the tread part or the bead part should have a high rigidity. For example, a large amount of carbon or phenolic cured resin is used for the bead apex that reinforces the bead part. A method for increasing the rigidity has been studied.

  Patent Document 1 discloses carbon black and phenolic thermosetting resin in which natural rubber or a blend rubber of natural rubber and diene rubber is adjusted with CTAB adsorption specific surface area, DBP oil absorption, and toluene coloring transmittance at a wavelength of 342 nm. A blended heavy duty radial tire tread rubber composition has been proposed. Patent Document 1 describes that according to the above rubber composition, it is possible to obtain a rubber composition for heavy load radial tires having an excellent balance of wear resistance, cut resistance, and chipping resistance. However, in the above rubber composition, when the carbon filling amount is increased, there is a problem that the Mooney viscosity increases and the processability tends to be deteriorated. Problems such as softening of the bead apex during use may occur.

  Patent Document 2 discloses a studless tire that has good wear resistance and excellent snow / ice road surface grip properties, and the grip properties of which do not easily deteriorate even when running for a long time, and a tread rubber composition from which a tread of the studless tire can be obtained. For the purpose of providing a product, the diene rubber is blended with hard rubber ground particles containing a rubber component, short fibers and a thermosetting resin, and the blending amount and size of the short fibers with respect to the rubber component are adjusted. Tread rubber compositions have been proposed. However, the short fibers blended in the tread rubber composition are produced by a method of cutting newly spun fibers. In addition, since the adhesion between the short fiber and the rubber component, the thermosetting resin, or the like is not always good, there is a case where it is necessary to take measures to appropriately treat the short fiber for the purpose of ensuring the adhesion. Therefore, there is room for improvement from the viewpoint of cost reduction of the tire.

Patent Document 3 discloses a rubber component composed of a diene synthetic rubber and a natural rubber having a glass transition point of a certain value or less for the purpose of providing a studless tire with improved slip resistance on snow and ice roads and excellent wear resistance. A rubber composition for a studless tire containing carbon black having a difference between a numerical value of nitrogen adsorption specific surface area and a numerical value of DBP oil absorption within a certain range. Proposed. However, even in the above rubber composition, when the carbon filling amount is increased, there may be a problem that Mooney viscosity increases and processability deteriorates.
JP-A-7-109383 JP 2000-319451 A JP 2001-329115 A

  An object of the present invention is to solve the above-mentioned problems and to provide a rubber composition for a tire having high rigidity and low cost and a pneumatic tire using the same without reducing workability.

  The present invention is a tire obtained by blending paper fibers in a range of 0.5 to 50 parts by mass and phenolic cured resin in a range of 0.5 to 20 parts by mass with respect to 100 parts by mass of a diene rubber. The present invention relates to a rubber composition.

  In the tire rubber composition of the present invention, the ratio (A) / (B) × 100 (%) of the complex elastic modulus (A) at 100 ° C. and the complex elastic modulus (B) at 70 ° C. is 50 to 100%. It is preferable to be within the range.

  In the tire rubber composition of the present invention, the ratio (L) / (D) of the average length (L) and the average long diameter (D) of the paper fibers is 10 or more, and the average length (L). Is preferably 10 μm or more.

  The present invention also relates to a pneumatic tire using the tire rubber composition.

  According to the present invention, since a predetermined amount of paper fiber and phenolic cured resin are used in combination, a large amount of the phenolic cured resin is present in the paper fiber due to good compatibility between the paper fiber and the phenolic cured resin. The reinforcing effect of the rubber composition can be obtained satisfactorily. Moreover, since the phenolic cured resin is impregnated in the paper fiber, the softening of the rubber composition during use at a high temperature is prevented. In addition, a rubber composition using a combination of paper fibers and a phenol-based cured resin can be made highly rigid without causing an excessive increase in Mooney viscosity, so that it can be manufactured with good workability. it can. By these actions, according to the present invention, it is possible to obtain a low-cost and high-rigidity rubber composition for tires without reducing workability.

  Paper fibers are blended in the tire rubber composition of the present invention. Paper fiber refers to paper that has been shortened by grinding or the like. By blending the paper fiber, the rigidity of the rubber composition can be improved, and by appropriately setting the type and blending amount of the paper fiber, the rigidity of the rubber composition can be easily and arbitrarily controlled. Moreover, since paper fiber is inexpensive, the cost of the rubber composition for tires can be reduced by using the paper fiber as a reinforcing agent. In the tire rubber composition of the present invention, the paper fiber is blended within a range of 0.5 to 50 parts by mass with respect to 100 parts by mass of the rubber component. If the blending amount of the paper fiber is 0.5 parts by mass or more, the reinforcing effect of the rubber composition by blending the paper fiber is sufficiently obtained, and if it is 50 parts by mass or less, the rubber composition becomes too hard. It is possible to prevent the deterioration of workability due to the tire and the deterioration of ride comfort performance when a pneumatic tire is used. The blending amount of the paper fiber is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 30 parts by mass or less, and further preferably 20 parts by mass or less.

  Paper fibers blended in the present invention include pulp obtained by pulping methods such as kraft pulp, semi-chemical pulp, mechanical pulp, non-wood pulp derived from kenaf, bagasse, bamboo, cotton, seaweed, etc., used copy It can be prepared using one or a mixture of two or more raw papers obtained from waste paper pulp obtained by deinking waste paper such as paper, old newspaper, and old corrugated paper. A paper fiber having a relatively large physical strength such as a pulverized product is preferably used. Kraft paper refers to all paper obtained by making kraft pulp (KP), and includes unbleached kraft paper and bleached kraft paper. Kraft pulp is the mainstream of those classified as chemical pulp, and since it has a relatively long fiber length, kraft paper is widely used for packaging applications and the like as paper having excellent strength. As the kraft pulp, either softwood kraft pulp or hardwood kraft pulp can be used, but softwood kraft pulp is preferable because of its relatively long fiber length.

  Kraft pulp is generally produced by the following method. First, impurities of the chip as a raw material are removed, and the thickness, length, etc. are made uniform within a certain range. Next, the chips are steamed with chemicals such as caustic soda and sodium sulfide at a high temperature of, for example, about 150 to 160 ° C. to elute mainly lignin in the chips and pulp. After passing through a washing step for separating the eluted lignin and chemicals from the pulp, the pulp is further treated with oxygen and alkali to further elute residual lignin in the pulp. Finally, foreign matter is removed and washed to obtain unbleached kraft pulp. Unbleached kraft pulp can be made bleached kraft pulp through a bleaching process. By making unbleached kraft pulp, unbleached kraft paper and by making bleached kraft pulp can be produced.

  The average length (L) of the paper fibers blended in the present invention is preferably 10 μm or more, and more preferably in the range of 50 to 1000 μm. When the average length (L) is 10 μm or more, the reinforcing effect of the rubber composition is good. Moreover, when this average length (L) is 1000 micrometers or less, the dispersion | distribution defect of the paper fiber in a rubber composition and the nonuniformity of the physical property of a rubber composition are prevented favorably. The average long diameter (D) of the paper fibers is preferably in the range of 10 to 800 μm, more preferably in the range of 30 to 700 μm, and still more preferably in the range of 30 to 200 μm. When the average major axis (D) is 10 μm or more, the reinforcing effect of the rubber composition is good, and when it is 800 μm or less, poor dispersion of paper fibers in the rubber composition and non-uniform physical properties of the rubber composition. Is well prevented.

  In the present invention, the ratio (L) / (D) of the average length (L) to the average major axis (D) is preferably 10 or more, and more preferably in the range of 20 to 2,000. When the ratio (L) / (D) is 10 or more, the reinforcing effect of the rubber composition is good, and when it is 2000 or less, poor dispersion of paper fibers in the rubber composition or physical properties of the rubber composition. Can be prevented well.

  In the tire rubber composition of the present invention, the phenolic cured resin is blended within a range of 0.5 to 20 parts by mass with respect to 100 parts by mass of the diene rubber. The phenolic cured resin has a reinforcing effect on the rubber composition, but the phenolic cured resin and the paper fiber are well-matched. By combining the phenolic cured resin with the paper fiber, the paper fiber and the phenolic resin are blended. In addition to the reinforcing effect of the rubber composition by each of the cured resins, a greater reinforcing effect is obtained by impregnating the phenolic cured resin into the paper fiber. As a result, the rigidity of the tire rubber composition can be increased without blending a large amount of paper fiber and phenolic cured resin, and the processability during the production of the tire rubber composition is unlikely to decrease. The effect that the cost of a rubber composition can also be reduced is acquired. When the blending amount of the phenolic cured resin with respect to 100 parts by mass of the diene rubber is 0.5 parts by mass or more, the reinforcing effect of the rubber composition is good. Well prevented. The blending amount of the phenolic cured resin with respect to 100 parts by mass of the diene rubber is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further 18 parts by mass or less, and further 16 parts by mass or less. It is preferable.

  Preferable examples of the phenol-based cured resin blended in the present invention include alkylphenol resins, oil-modified phenol resins, cashew-modified phenol resins and the like. Of these, alkylphenol resins and the like are particularly preferably used because they have higher strength.

  The ratio (A) / (B) × 100 (%) of the complex elastic modulus (A) at 100 ° C. and the complex elastic modulus (B) at 70 ° C. of the rubber composition for tires of the present invention is 50 to 100%. Further, it is preferable to be in the range of 60 to 100%, more preferably 70 to 100%. When the ratio (A) / (B) × 100 (%) is 50% or more, there is little decrease in the complex elastic modulus of the rubber composition at high temperatures, and a rubber composition that maintains high rigidity even under high temperature conditions. can get. The complex elastic modulus in the present invention is measured using a viscoelastic spectrometer under conditions of a temperature of 70 ° C. or 100 ° C., a frequency of 10 Hz, and a dynamic strain of ± 1%.

  When the complex elastic modulus (A) at 100 ° C. of the rubber composition for tires of the present invention is 5 MPa or more, further 10 MPa or more, and further 15 MPa or more, it is preferable because high rigidity can be ensured even at high temperature use, 200 MPa or less, Furthermore, when it is set to 180 MPa or less and 150 MPa or less, the rubber composition is preferable because it does not become too hard and can provide good riding comfort performance. Further, when the complex elastic modulus (B) at 70 ° C. of the rubber composition for tire is 5 MPa or more, further 10 MPa or more, and further 15 MPa or more, it is preferable in that a highly rigid rubber composition is obtained, 200 MPa or less, Furthermore, when it is set to 180 MPa or less and 150 MPa or less, the rubber composition is preferable because it does not become too hard and can provide good riding comfort performance.

  The Shore A hardness of the tire rubber composition of the present invention is preferably set within a range of 70 to 98, for example. When the Shore A hardness is 70 or more, the steering stability of the tire is good, and when it is 98 or less, the ride comfort is good. The Shore A hardness is preferably 75 or more, more preferably 80 or more, and is preferably 97 or less and more preferably 96 or less. The Shore A hardness can be measured according to ISO-7619.

  Examples of the diene rubber used in the tire rubber composition of the present invention include natural rubber, styrene-butadiene rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), and ethylene-propylene-diene rubber (EPDM). Chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), etc., and rubber components containing one or more of these are preferred. The ethylene-propylene-diene rubber (EPDM) is an ethylene-propylene rubber (EPM) containing a third diene component. Examples of the third diene component include non-conjugated dienes having 5 to 20 carbon atoms such as 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, and 2,5-dimethyl-1,5. -Hexadiene and 1,4-octadiene, cyclic dienes such as 1,4-cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-methallyl-5 Preferred examples include alkenyl norbornene such as -norbornene and 2-isopropenyl-5-norbornene. In particular, dicyclopentadiene, 5-ethylidene-2-norbornene and the like can be preferably used.

  In the tire rubber composition of the present invention, the following components generally blended in other rubber products can be blended as appropriate.

  As a filler, for example, silica can be blended in an amount of 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rubber component. As the silica, those generally used for general-purpose rubber can be used, and examples thereof include dry method white carbon, wet method white carbon and colloidal silica used as a reinforcing material. Among these, wet method white carbon mainly containing hydrous silicic acid is preferable. When the compounding amount of silica is 5 parts by mass or more, the reinforcing effect on the tire rubber composition is good, and the wear resistance of the tire is good. Moreover, when it is 100 mass parts or less, the fall of workability by the viscosity rise of the unvulcanized rubber composition at the time of manufacture of the rubber composition for tires, and the excessive raise of cost can be prevented.

Nitrogen adsorption specific surface area (BET method) of silica used in the above, for example 50 to 300 m ² / g, it is preferably further in the range of 100 to 200 m ² / g. When the nitrogen adsorption specific surface area of silica is 50 m ² / g or more, a sufficient reinforcing effect on the tire rubber composition can be obtained, thereby improving the tire wear resistance. On the other hand, when the nitrogen adsorption specific surface area is 300 m ² / g or less, the processability of the rubber composition for tires is good, and the steering stability is sufficiently secured. Here, the nitrogen adsorption specific surface area is a value measured by the BET method according to ASTM D3037-81.

  When silica is blended in the rubber composition for tires of the present invention, a silane coupling agent, preferably a sulfur-containing silane coupling agent is blended in an amount of 1% by mass or more and 20% by mass or less with respect to the mass of silica. It is preferable. By adding a silane coupling agent, the wear resistance and steering stability of the tire can be improved. When the amount of the silane coupling agent is 1% by mass or more, the effect of improving the wear resistance and steering stability is good. Is obtained. Moreover, when the compounding quantity of a silane coupling agent is 20 mass% or less, there is little danger that the rubber | gum kneading | mixing and the burning (scorch) in an extrusion process will arise. As sulfur-containing silane coupling agents, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethyl Examples include silylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide, bis- [3- (triethoxysilyl) -propyl] tetrasulfide, 3-mercaptopropyltrimethoxysilane and the like.

  Other silane coupling agents include vinyltrichlorosilane, vinyltris (2-methoxyethoxy) silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ- (2-aminoethyl) Aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like can be used.

  In the present invention, other coupling agents such as aluminate coupling agents and titanium coupling agents can be used alone or in combination with a silane coupling agent depending on the application.

  In addition to the rubber composition for tires of the present invention, other fillers such as carbon black, clay, alumina, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium oxide and titanium oxide are used alone or in combination. A mixture of the above can be used.

Here, carbon black is blended in an amount of 10 parts by mass or more, further 20 parts by mass or more, further 40 parts by mass or more, 150 parts by mass or less, further 100 parts by mass or less, and further 90 parts by mass or less with respect to 100 parts by mass of the rubber component. It is preferable. Here, the physical properties of carbon black are such that the nitrogen adsorption specific surface area (BET method) is in the range of 70 to 300 m ² / g, the DBP oil absorption is in the range of 5 to 300 ml / 100 g, and the iodine adsorption is in the range of 146 to 152 mg / g. The inner one is suitable in terms of the reinforcing effect on the tire rubber composition.

  In addition to the above, a vulcanizing agent, a vulcanization accelerator, a softening agent, a plasticizer, an anti-aging agent, a foaming agent, an anti-scorch agent, and the like can be added to the tire rubber composition of the present invention. .

  As the vulcanizing agent, an organic peroxide or a sulfur vulcanizing agent can be used. Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, 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 (benzoylperoxy) 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-butylperoxy-3,3,5-trimethylsiloxane, n-butyl-4,4 And the like can be used 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.

  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 (Nt-butyl-2-benzothiazylsulfenamide), N, N-dicyclohexyl-2- Examples thereof include sulfenamide compounds such as benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, and N, N-diisopropyl-2-benzothiazolesulfenamide.

  Examples of the thiazole type include MBT (2-mercaptobenzothiazole), MBTS (dibenzothiazyl disulfide), sodium salt of 2-mercaptobenzothiazole, zinc salt, copper salt, cyclohexylamine salt, 2- (2,4-dinitro). Phenyl) mercaptobenzothiazole, 2- (2,6-diethyl-4-morpholinothio) benzothiazole and the like.

  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. , Tetrabutyl thiuram disulfide, pentamethylene thiuram tetrasulfide and the like.

  Examples of thiourea compounds include thiourea compounds such as thiacarbamide, diethyl thiourea, dibutyl thiourea, trimethyl thiourea, and diortolyl thiourea.

  Examples of guanidine compounds include guanidine compounds such as diphenyl guanidine, diortolyl guanidine, triphenyl guanidine, orthotolyl biguanide, and diphenyl guanidine 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 Such Okarubamin acid compounds.

  Examples of the aldehyde-amine system or aldehyde-ammonia system include acetaldehyde-aniline reaction product, butyraldehyde-aniline condensate, hexamethylenetetramine, acetaldehyde-ammonia reaction product, and the like.

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

  In the present invention, a softener may be used in combination in order to further improve kneading processability. Softeners include process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petroleum jelly such as petroleum jelly, fatty oil softener such as castor oil, linseed oil, rapeseed oil, coconut oil, tall oil, , Waxes such as beeswax, carnauba wax and lanolin, and fatty acids such as linoleic acid, palmitic acid, stearic acid and lauric acid.

  Furthermore, the rubber composition for tires of this invention can mix | blend a plasticizer as needed. Specifically, DMP (dimethyl phthalate), DEP (diethyl phthalate), DBP (dibutyl phthalate), DHP (diheptyl phthalate), DOP (dioctyl phthalate), DINP (diisononyl phthalate), DIDP (phthalate) Acid diisodecyl), BBP (butyl benzyl phthalate), DLP (dilauryl phthalate), DCHP (dicyclohexyl phthalate), hydrophthalic anhydride, DOZ (di-2-ethylhexyl azelate), DBS (dibutyl sebacate), DOS (Dioctyl sebacate), acetyl triethyl citrate, acetyl tributyl citrate, DBM (dibutyl maleate), DOM (2-ethylhexyl maleate), DBF (dibutyl fumarate) and the like.

  The tire rubber composition of the present invention includes, as a scorch inhibitor for preventing or retarding scorch, for example, organic acids such as phthalic anhydride, salicylic acid, benzoic acid, nitroso compounds such as N-nitrosodiphenylamine, N-cyclohexyl Thiophthalimide or the like can be used.

  The rubber composition of the present invention can be suitably used for pneumatic tires for passenger cars, buses, trucks and the like. FIG. 1 is a cross-sectional view showing the right half of a pneumatic tire to which the present invention is applied. In FIG. 1, a tire T includes a pair of bead portions 1, a pair of sidewall portions 2, and a tread portion 3 connected to both sidewall portions, and the bead cores 4 embedded between the pair of bead portions 1. And a belt 6 that reinforces the tread portion 3 on the outer periphery of the carcass 5. The carcass 5 has a carcass main body portion extending between the pair of bead cores 4 and a turn-up portion 5a wound around the bead core 4 from the inner side to the outer side in the tire radial direction. A bead apex 7 extending in the sidewall direction from the upper end of the bead core 4 is disposed in a region surrounded by the carcass 5 and the folded portion 5a. The carcass 5 is composed of a ply in which a radial arrangement cord such as a steel cord or an ultrahigh strength organic fiber cord such as aramid is covered with rubber. The rubber composition for tires of the present invention is suitably used for the tread portion 3 and the bead apex 7 of the pneumatic tire having the basic structure as described above.

[Example]
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

  Ingredients shown in Table 1, excluding sulfur and vulcanization accelerator, are kneaded for 4 minutes at about 150 ° C. using a 1.7 L Banbury, and further added with sulfur and vulcanization accelerator to form a biaxial roller. A rubber composition was obtained by kneading at about 80 ° C. for 4 minutes. A rubber sheet is produced using the rubber composition, molded as a bead apex of a tire, vulcanized under conditions of 150 ° C., 35 minutes, 25 kgf (245.16625N), and a test tire of size 195 / 65R15 Was made.

(Complex modulus)
A strip sample having a width of 4 mm, a length of 30 mm, and a thickness of 1.5 mm was prepared, and using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd., the temperature was 70 ° C. and 100 ° C., the frequency was 10 Hz, and the dynamic strain was ± 1%. Under the conditions, the complex elastic modulus (A) at 100 ° C. and the complex elastic modulus (B) at 70 ° C. were measured. Further, the ratio of complex elastic modulus (A) / (B) × 100 (%) was calculated. The results are shown in Table 1.

(Maneuvering stability)
The test tire produced above is mounted on a car, and it runs at 40-100 km / h on a test course, and the steering stability is evaluated by a driver's handle response, rigidity feeling, grip feeling feeling test. It was. The evaluation was performed based on the following criteria with a maximum of 5 points, and the average value of the three drivers was represented by an index with the conventional example 1 as 100. The larger the value, the better the steering stability. The results are shown in Table 1.
5 points: Very good.
4 points: Good.
3 points: normal.
2 points: Slightly inferior.
1 point: Inferior.

(Maneuvering stability at high temperatures)
Except that the speed was increased to 200 km / h, the evaluation of the handling stability at high temperatures was performed in the same way as the above-mentioned evaluation of handling stability, with the driver's lane change, steering response, and rigidity feeling feeling tests. I did it. The evaluation was performed based on the following criteria with a maximum of 5 points, and the average value of the three drivers was represented by an index with the conventional example 1 as 100. The larger the value, the better the steering stability at high temperatures. The results are shown in Table 1.
5 points: Very good.
4 points: Good.
3 points: normal.
2 points: Slightly inferior.
1 point: Inferior.

(Machine durability)
The test tire was placed in an oven at 80 ° C. for 1 week, and was then run for 30,000 km at an internal pressure of 200 kPa, a load of 340 kgf (about 3334.278 N), and a speed of 80 km / hour. If the rubber at the bead part of the tire completed without any damage, it passed, and if it could not complete without damage, it was rejected.

Note 1: NR is “RSS # 3” made in Thailand.
Note 2: SBR is “SBR1502” manufactured by Sumitomo Chemical Co., Ltd.
Note 3: CB is carbon black “N330” manufactured by Mitsubishi Chemical Corporation.
Note 4: The adhesive resin is “SP1068” manufactured by Nippon Shokubai Co., Ltd.
Note 5: Anti-aging agent is “Ozonon 6C” manufactured by Seiko Chemical Co., Ltd.
Note 6: Wax is “Sannokk Wax” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Note 7: Aroma oil is “Diana Process PS32” manufactured by Idemitsu Kosan Co., Ltd.
Note 8: Stearic acid is “paulownia” manufactured by NOF Corporation.
Note 9: Zinc oxide is “Ginbae R” manufactured by Toho Zinc Co., Ltd.
Note 10: Paper fiber is “Neofiber” manufactured by Oji Paper Co., Ltd.
Note 11: The cured resin is Sumitomo Duretsu's phenolic cured resin “Sumilite Resin PR12686”.
Note 12: Sulfur is manufactured by Tsurumi Chemical Co., Ltd.
Note 13: The vulcanization accelerator NS is “Noxeller NS” (Nt-butyl 2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Note 14: Vulcanization accelerator H is “Noxeller H” manufactured by Ouchi Shinsei Chemical Co., Ltd.

  In Comparative Example 1 in which the amount of paper fiber is excessively large and in Comparative Example 2 in which the amount of phenolic cured resin is excessively large, the tire rubber composition becomes too hard and becomes brittle, and the durability is not sufficient. . Further, in Comparative Example 3 in which paper fiber and phenolic cured resin are not blended, and in Comparative Example 4 in which paper fiber is blended and phenolic cured resin is not blended, the rigidity of the tire rubber composition is all Since it is not high enough, steering stability and durability are insufficient. On the other hand, in Examples 1 to 5 in which predetermined amounts of paper fiber and phenolic cured resin are blended, the steering stability, the steering stability at high temperatures, and the durability are all excellent. In Examples 1 to 3 in which 15 parts by mass of the phenol-based cured resin was blended, both the complex elastic modulus at 70 ° C. and 100 ° C. showed larger values as the blended amount of paper fibers increased. In Examples 4 and 5 in which 7.5 parts by mass of phenol-based cured resin was blended, the ratio of complex elastic modulus (A) at 100 ° C. to complex elastic modulus (B) at 70 ° C. (A) / (B ) × 100 (%) value is higher than those of Examples 1-3. In Examples 4 and 5, although the value of the complex elastic modulus of the rubber composition itself is not so high, the rubber composition maintains high rigidity even under high temperature conditions. Property is improved.

  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.

  In the tire rubber composition of the present invention, by using a combination of paper fiber and a phenolic cured resin, an excessive increase in Mooney viscosity during the production of the tire rubber composition is suppressed, and processability is good. It becomes. The rubber composition for tires of the present invention is highly rigid and inexpensive, and can be suitably applied to a pneumatic tire having high steering stability at high speed running.

It is sectional drawing which shows the right half of the pneumatic tire with which this invention is applied.

Explanation of symbols

  T tire, 1 bead part, 2 side wall part, 3 tread part, 4 bead core, 5 carcass, 5a folded part, 6 belt, 7 bead apex.

Claims (4)

  A rubber composition for tires comprising 100 parts by mass of a diene rubber and a paper fiber in a range of 0.5 to 50 parts by mass and a phenolic cured resin in a range of 0.5 to 20 parts by mass. .   The ratio (A) / (B) × 100 (%) of the complex elastic modulus (A) at 100 ° C. and the complex elastic modulus (B) at 70 ° C. is in the range of 50 to 100%. The rubber composition for tires as described.   The ratio (L) / (D) of the average length (L) and the average long diameter (D) of the paper fibers is 10 or more, and the average length (L) is 10 μm or more. The rubber composition for tires described in 1.   A pneumatic tire using the tire rubber composition according to claim 1.

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