JP2008169298A - Rubber composition and pneumatic tire using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition which, when used for the tread rubber of a tire, can improve both the initial gripping performance and the travelling stability of the tire more than those of the conventional one, and provide a pneumatic tire using the rubber composition for the tread rubber. <P>SOLUTION: For the tread rubber of the tire there is used the rubber composition characterized by incorporating, based on 100 pts.mass of a rubber component, 10-60 pts.mass of at least one hydrogenated petroleum resin having a softening point of ≥120°C, obtained by partially or wholly hydrogenating a petroleum resin consisting of 5C components and/or 9C components. The rubber composition is further incorporated with 5-60 parts by mass of at least one resin selected from 9C resins which have a softening point of ≥140°C and ≤190°C and contain indene, based on 100 pts.mass of the rubber component. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rubber composition capable of improving both the initial grip performance and running stability of a tire as compared with a conventional tire by using the tread rubber for a tire, and the tread rubber. It relates to a pneumatic tire used in the above.

  It is desired that a high-performance tire tread used for competitions or the like maintains excellent handling stability (DRY grip performance) from the initial driving to the end of driving on a dry road surface. Therefore, conventionally, for the purpose of improving the DRY grip property (initial grip performance) at the beginning of running when the tire is relatively low in temperature, an oil component including a low softening point resin and a liquid polymer in a rubber composition used for tread rubber. In addition, it has been studied to add a softener or the like that exhibits an effect at a low temperature.

For example, although a rubber composition containing a C ₉ aromatic resin or the like is described in Patent Document 1, in consideration of dispersibility during resin kneading, the rubber composition has a softening point of 140 ° C. It is blended with the following C ₉ aromatic resin.

However, a tire produced by blending a resin with a low softening point in this way and using the rubber composition as a tread rubber has improved initial grip performance. As the temperature increases, the grip performance decreases. On the other hand, when compounded in the rubber composition alone high softening point resin such as C ₉ resins for tire temperature improves the grip performance of the tire at the time of rise (running stability) while traveling on the low road surface The initial grip performance of the tire is greatly reduced.

  As a method for solving such a problem, a method is conceivable in which both a high softening point resin and a low softening point resin are blended in a rubber composition. However, since the total resin amount to be blended affects the temperature characteristics of the rubber composition, the amount of resin that can be blended in the rubber composition is limited. Therefore, the tire obtained by this method has a moderate initial grip performance and running stability. Therefore, it is necessary to provide a rubber composition for use in a tread rubber of a tire that can achieve both high initial grip performance and running stability of the tire.

JP-A-5-9336

  The present inventor has intensively studied under which conditions the grip performance of a tire using a rubber composition containing a low softening point resin and good initial grip performance as a tread rubber is deteriorated. It was found that even on the same course, the degree of decrease in grip performance greatly changes depending on the road surface temperature. That is, it was found that the running stability of the tire hardly decreases when the road surface temperature is 10 ° C. or lower, whereas the running stability of the tire tends to decrease when the road surface temperature exceeds 40 ° C.

  Further, in a circuit where the road surface temperature is 42 ° C., a vehicle equipped with a tire using the rubber composition as a tread rubber was run, and the internal temperature of the tire during running was measured. It has been found that the internal temperature of the tire has increased from 100 ° C to 110 ° C. Since the internal temperature of the tire is measured after the vehicle returns to the garage, the internal temperature during driving is expected to be higher. Since the rubber composition containing the low softening point resin has a large decrease in the dynamic elastic modulus (E ′) at 100 ° C. or higher, the tire using the rubber composition as a tread rubber has a high temperature inside the tire. At that time, there is a concern that the rubber composition is softened together with the resin and the running stability is lowered.

  Accordingly, the present invention provides a rubber composition capable of improving both the initial grip performance and running stability of a tire as compared with a conventional tire by using the tread rubber of a tire, and the rubber composition. The purpose is to provide a pneumatic tire used for tread rubber.

In order to achieve the above object, the present inventor has an effect of lowering E ′ at room temperature and can secure E ′ at high temperature, and has a softening point of at least 120 ° C. or more and a combination of two or more of these resins was intensive studies with respect to rubber compositions containing Te, hitherto formulation examples of the rubber composition did, C ₅ components and / or parts petroleum resin comprising C ₉ components or fully hydrogenated and softening point A rubber composition for tread rubber that can produce a tire having both higher initial grip performance and running stability than a conventional tire by blending at least one hydrogenated petroleum resin having a temperature of 120 ° C. or higher into the rubber composition. It has been found that it can be prepared, and the present invention has been completed.

That is, the rubber composition of the present invention, with respect to 100 parts by mass of the rubber component, C ₅ components and / or C ₉ petroleum resin portion consisting of components or fully hydrogenated hydrogenated the softening point is above 120 ° C. It is characterized by comprising 10 to 60 parts by mass of at least one added petroleum resin.

In the rubber composition of the present invention, the rubber composition is at least one selected from C ₉ resins having a softening point of 140 ° C. or higher and 190 ° C. or lower and containing indene with respect to 100 parts by mass of the rubber component. It is preferable to blend 5 to 60 parts by mass.

  Moreover, it is preferable that the said rubber component contains 70 mass% or more of butadiene-type copolymers whose vinyl bond amount of a butadiene part is 10% or more.

  Furthermore, it is preferable that the butadiene-based copolymer contains a styrene-butadiene copolymer (SBR).

  The styrene-butadiene copolymer preferably has a styrene content of 20 to 60% by mass.

  Moreover, it is preferable that the rubber composition of the present invention further comprises 60 to 200 parts by mass of carbon black with respect to 100 parts by mass of the rubber component.

  The pneumatic tire of the present invention is preferably produced using the rubber composition as a tread rubber.

  The present invention relates to a rubber composition capable of improving both the initial grip performance and running stability of a tire as compared with a conventional tire by using the tread rubber for a tire, and the tread rubber. The pneumatic tire used for the can be provided.

The rubber composition of the present invention, with respect to 100 parts by mass of the rubber component, C ₅ components and / or C ₉ petroleum resin portion consisting of components or fully hydrogenated and softening point of 120 ° C. or more hydrogenated petroleum 10 to 60 parts by mass of at least one resin is blended. Here, if a resin having a softening point of less than 120 ° C. is blended, the running stability of the tire is impaired. In view of dispersibility during kneading, the resin preferably has a softening point of 180 ° C. or lower. In order to give the rubber composition the properties of the resin, it is necessary that the amount of the resin is 10 parts by mass or more with respect to 100 parts by mass of the rubber component. The composition is cured. As hydrogenated petroleum resin having a softening point of 120 ° C. or higher partially or completely hydrogenated petroleum resin composed of C ₅ component and / or C ₉ component, Alcon P125 (softening point 125 ° C.) manufactured by Arakawa Chemical Co., Ltd. Idemitsu Kosan Imabu Y135 (softening point 135 ° C), Arakawa Chemical Co., Ltd. Alcon M135 (softening point 135 ° C), Idemitsu Kosan Imabu P140 (softening point 140 ° C), Arakawa Chemical Co., Ltd. Alcon P140 (softening point 140 ° C), etc. Is mentioned. These can be blended in the rubber composition alone or in combination of two or more.

The rubber composition of the present invention further has 5 to 60 parts by mass of at least one selected from C ₉ resins having a softening point of 140 ° C. or higher and 190 ° C. or lower and containing indene with respect to 100 parts by mass of the rubber component. It is preferable to mix. Although the desired effect can be obtained by blending the hydrogenated petroleum resin alone into the rubber composition, it is preferable to blend the resin further. Here, if a C ₉ resin containing indene having a softening point of less than 140 ° C. is blended in the rubber composition, the running stability of the tire cannot be improved. In consideration of the dispersibility of the resin during kneading, the softening point is preferably 190 ° C. or lower. In order to give the rubber composition the characteristics of the resin, it is necessary to blend 5 parts by mass or more with respect to 100 parts by mass of the rubber component. The composition is cured. The C ₉ resin containing the indene, homopolymer of indene, as well as of a copolymer resin of C ₉ aromatic monomer refers to a resin that contains indene in the monomer raw material, the C ₉ Examples of aromatic monomers include vinyltoluene, α-methylstyrene, coumarone, and the like. That is, examples of the C ₉ resin include vinyltoluene-α-methylstyrene-indene resin, vinyltoluene-indene resin, α-methylstyrene-indene resin, coumarone-indene resin, and the like.

Softening point of the C ₉ resin is preferably in the range of 140 to 180 ° C., more preferably in the range of from 155 to 180 ° C.. The C ₉ resin is more preferably an α-methylstyrene-vinyltoluene-indene copolymer resin having a softening point of 155 ° C. or higher and 180 ° C. or lower.

  In the rubber composition of the present invention, it is preferable that the rubber component contains 70% by mass or more of a butadiene-based copolymer having a vinyl bond amount in the butadiene portion of 10% or more. If the vinyl bond content of the butadiene part is less than 10%, the rigidity of the rubber composition at a high temperature range is lowered and a desired effect cannot be obtained, and the content of the butadiene copolymer in the rubber component is 70. If it is less than mass%, the basic heat resistance of the rubber composition is greatly reduced.

  The rubber component of the rubber composition of the present invention is not particularly limited. In addition to the butadiene copolymer, natural rubber, polybutadiene rubber, polyisoprene rubber, ethylene-propylene copolymer, isobutylene-isoprene copolymer. Further, a diene rubber such as polychloroprene may be included.

  In the rubber composition of the present invention, the butadiene copolymer preferably contains a styrene-butadiene copolymer. When the butadiene-based copolymer contains a styrene-butadiene copolymer, the rubber composition has improved hysteresis loss, and thus grip performance is improved. The styrene-butadiene copolymer may be synthesized by any synthesis method such as emulsion polymerization or solution polymerization. Examples of the butadiene copolymer other than the styrene-butadiene copolymer include acrylonitrile-butadiene copolymer.

  Moreover, it is preferable that the styrene content rate of the said styrene-butadiene copolymer is 20-60 mass%. If the styrene content is less than 20% by mass, the tire cannot obtain a desired grip performance at low and high temperatures, and if the styrene content exceeds 60% by mass, the block rigidity becomes higher than necessary and the road surface is increased. Therefore, the tire cannot obtain a desired grip performance. Further, since the grip performance of the tire is remarkably enhanced, the styrene content of the styrene-butadiene copolymer is more preferably 20 to 45% by mass.

The rubber composition of the present invention preferably further comprises 60 to 200 parts by mass of carbon black and more preferably 60 to 160 parts by mass with respect to 100 parts by mass of the rubber component. Here, if the blending amount of carbon black in the rubber composition is less than 60 parts by mass, the contribution to improving the DRY grip property of the tire is not sufficient, and if it exceeds 200 parts by mass, the wear resistance of the tire is reduced. Further, the workability is extremely deteriorated. The amount of carbon black added to the rubber composition is more preferably 70 to 140 parts by mass. The carbon black preferably has a nitrogen adsorption specific surface area of about 80 to 280 m ² / g. When the nitrogen adsorption specific surface area of carbon black is less than 80 m ² / g, sufficient elastic modulus cannot be obtained and wear resistance deteriorates, and when it exceeds 280 m ² / g, improvement in grip strength and wear resistance cannot be expected, but kneading Workability deteriorates. Examples of the carbon black include HAF, ISAF, and SAF, and SAF is preferable from the viewpoint of achieving both wear resistance and grip performance. Carbon black may be used individually by 1 type, or may use 2 or more types together, and a commercial item can be used conveniently.

  Furthermore, in the rubber composition of the present invention, the acetone / chloroform extract after vulcanization is preferably 30 to 270 parts by mass with respect to 100 parts by mass of the rubber component. If the extract is less than 30 parts by mass and exceeds 270 parts by mass, neither improvement in grip performance nor wear resistance can be expected, and the kneading workability is further deteriorated. The extracted amount is more preferably 30 to 200 parts by mass with respect to 100 parts by mass of the rubber component, from the viewpoint of both improvement in gripping force and wear resistance and good kneading workability.

  In addition to this, the phenolic resin used in the rubber industry can be used for the rubber composition. Examples of the alkylphenol resins include alkylphenol-acetylene resins such as pt-butylphenol-acetylene, and alkylphenol-formartenes including cresols, xylenols, pt-butylphenol, and pt-octylphenols. Examples thereof include hydride resins. The softening point of these resins is preferably 130 to 160 ° C. When the softening point is less than 130 ° C., running stability is lowered, and when it exceeds 160 ° C., the polarity of the resin is high, so that the resin is not uniformly dispersed during kneading, and the wear resistance is significantly lowered. These alkylphenol resins may be used alone or in combination of two or more. It is preferable that the compounding quantity of this resin is 10-100 mass parts with respect to 100 mass parts of rubber components. When the amount of the resin is less than 10 parts by mass, the grip performance by the resin is not improved, and when it exceeds 100 parts by mass, the kneading workability is remarkably deteriorated. Moreover, since these effects are remarkable, it is more preferable that the compounding quantity of this resin is 20-80 mass parts.

  The rubber composition includes rubber components, resin components, carbon black, oils such as process oils, vulcanizing agents, vulcanization accelerators, anti-aging agents, softening agents, zinc oxide, inorganic fillers, and ozone deterioration prevention. Additives, colorants, antistatic agents, lubricants, antioxidants, coupling agents, foaming agents, foaming aids, and compounding agents commonly used in the rubber industry such as stearic acid are within the range that does not impair the purpose of the present invention. Can be appropriately selected and blended. As these compounding agents, commercially available products can be suitably used.

  There is no restriction | limiting in particular as oils, such as the said process oil, According to the objective, it can select suitably and can be used. Examples of the oil include aromatic oils, naphthenic oils, paraffinic oils, ester oils, solution conjugated diene rubbers, solution hydrogenated conjugated diene rubbers, and the like. When the oil component is contained in the rubber composition, the fluidity of the rubber composition can be controlled. Therefore, by reducing the viscosity of the rubber composition before vulcanization and increasing the fluidity, the rubber composition can be improved very well. This is advantageous in that it can be extruded.

  The content of the oil in the rubber composition is preferably 35 to 200 parts by mass, including these oils, when the rubber component is oil-extended with respect to 100 parts by mass of the rubber component. Part by mass is more preferable. When the oil content is less than 35 parts by mass with respect to 100 parts by mass of the rubber component, the Mooney viscosity of the unvulcanized rubber becomes extremely high and the workability deteriorates, and further, the DRY grip property of the tire also deteriorates. When the amount exceeds 200 parts by mass, the Mooney viscosity becomes extremely low and workability is deteriorated. Further, the tread becomes too soft and wear resistance may be deteriorated.

  Further, as the vulcanizing agent, in addition to conventional sulfur, at least one of an organic thiosulfate compound (for example, sodium 1,6-hexamethylenedithiosulfate dihydrate) and a bismaleimide compound (for example, phenylene bismaleimide) Seeds can be used in combination.

  Examples of the vulcanization accelerator include tetrakis-2-ethylhexyl thiuram disulfide, tetrakis-2-isopropyl thiuram disulfide, tetrakis-dodecyl thiuram disulfide, and thiuram compounds such as tetrakis-benzyl thiuram disulfide, di-2-ethyl Dithiocarbamate compounds such as zinc hexyl dithiocarbamate, zinc dodecyldithiocarbamate, and zinc benzyldithiocarbamate, and dibenzothiazyl disulfide, 4,4′-dimethyldibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazyl- Sulfenamide, Nt-butyl-2-benzothiazyl-sulfenamide, Nt-butyl-2-benzothiazyl-sulfenimide, N-oxydiethylene-benzothiazyl Fen'amido, and N, hexyl N'- dicyclohexyl-2-benzothiazyl - benzothiazolyl vulcanization accelerator such as sulfenamide and the like.

  The rubber composition of the present invention can be produced by kneading, heating, extruding, vulcanizing, etc., a rubber component, a resin, and the above-described other compounding agents appropriately selected as necessary.

  The kneading conditions are not particularly limited, and are appropriately determined according to various conditions such as the amount of each component charged into the kneading apparatus, the rotational speed of the rotor, the ram pressure, the kneading temperature, the kneading time, and the type of the kneading apparatus. You can choose. Examples of the kneading apparatus include Banbury mixers, intermixes, and kneaders that are generally used for kneading rubber compositions.

  The conditions for the heating are not particularly limited, and various conditions such as the heating temperature, the heating time, and the heating apparatus can be appropriately selected according to the purpose. Examples of the heating apparatus include a roll machine that is usually used for heating a rubber composition.

  The conditions for extrusion are not particularly limited, and can be appropriately selected according to various conditions such as extrusion time, extrusion speed, extrusion apparatus, and extrusion temperature. As said extrusion apparatus, the extruder etc. which are generally used for extrusion of the rubber composition for tires are mentioned. The extrusion temperature can be appropriately determined.

  There is no restriction | limiting in particular about the apparatus, system, conditions, etc. which perform a vulcanization | cure, According to the objective, it can select suitably. Examples of the vulcanizing apparatus include a molding vulcanizer using a mold generally used for vulcanizing a tire rubber composition. The vulcanization temperature is usually about 100 to about 190 ° C.

  The rubber composition of the present invention is preferably used for a tread rubber of a pneumatic tire, particularly a tread rubber of a tire for a high-speed competition vehicle used for circuit running or the like. In addition, as a tire member other than the tread rubber, a known member can be used. Further, as the gas filled in the pneumatic tire, an inert gas such as nitrogen, argon, helium, or the like can be used in addition to normal or air whose oxygen partial pressure is adjusted.

  The pneumatic tire of the present invention comprises at least the rubber composition, preferably at least for a tread. The tire of the present invention is not particularly limited except that the rubber composition of the present invention is used, and a known tire configuration can be adopted as it is.

  As an example of the configuration of the pneumatic tire of the present invention, the pneumatic tire includes a pair of bead portions, a carcass connected to the bead portion in a toroid shape, a belt and a tread for tightening a crown portion of the carcass It is mentioned that it is a tire which has. The tire of the present invention may have a radial structure or a bias structure.

  The structure of the tread of the pneumatic tire of the present invention is not particularly limited, and may be a one-layer structure or a multilayer structure, and an upper cap portion that directly contacts the road surface; You may have what is called a cap base structure comprised from the base part of the lower layer arrange | positioned adjacent to the inner side of the tire of a cap part. In the present invention, it is preferable that at least the cap portion is formed of the rubber composition.

  Although there is no restriction | limiting in particular about the tire of this invention, For example, it can manufacture as follows. That is, first, the rubber composition of the present invention is prepared, and the rubber composition is pasted on an unvulcanized base portion that is preliminarily pasted on the crown portion of the raw tire case. Thereafter, it can be produced by vulcanization molding with a predetermined mold at a predetermined temperature and a predetermined pressure.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the scope of the present invention.

(Comparative Examples 1-3 and Examples 1-5)
Each rubber composition was kneaded and prepared using a Banbury mixer in accordance with the formulation shown in Table 1 below (unit: parts by mass). Further, a tread of a passenger car tire (size: 225 / 40R18) was formed using the rubber composition, and a prototype tire was manufactured. Thereafter, the DRY grip properties and the like of the rubber composition and the prototype tire were evaluated according to the following methods. The results are shown in Table 1.

<Dynamic elastic modulus E '(MPa)>
After the obtained rubber composition is vulcanized at 145 ° C. for 45 minutes, a constant stress measurement is performed with a flexometer described in JIS K6265, and the time until a crack occurs inside the sample is measured as a heat fatigue time. went. The data shows values indexed with Comparative Example 1 as 100.

<DRY grip>
Equipped with a high-performance vehicle that can run a prototype tire at a maximum speed of 300 km / h and run on a circuit, the initial grip (initial grip performance) of the first lap of measurement and the final grip of the last lap of measurement (travel stability The feeling of the test driver in the property was evaluated according to the following criteria. It means that it is excellent in DRY grip property, so that a numerical value becomes large with a positive value.
+3: To the extent that a general driver with low driving frequency can clearly recognize the difference +2: To the extent that a general driver with high driving frequency can recognize the difference +1: To the extent that a professional driver can recognize the difference 0・ Control-1: To the extent that a professional driver can recognize the difference-2 ... To the extent that a general driver with high driving frequency can recognize the difference-3 ... With a general driver with low driving frequency clearly seeing the difference As much as possible

* 1 Made by Nippon Synthetic Rubber Co., Ltd., 0120 (styrene content 35%, vinyl bond 16%, 35% aromatic oil)
* 2 SAF (N2SA 150m ² / g)
* 3 Fucole Aromax # 3, manufactured by Fuji Kosan Co., Ltd.
* 4 Seiko Chemical Co., Ltd., microcrystalline wax * 5 Ouchi Shinsei Chemical Co., Ltd., N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine * 6 Arakawa Chemical Alcon M90, partially hydrogenated petroleum resin, softening point 90 ° C
* 7 Made by Nippon Petrochemical Co., Ltd., Neopolymer 170S, vinyltoluene-α-methylstyrene-indene resin, softening point 170 ° C
* 8 Idemitsu Kosan Co., Ltd., Imabe P140, hydrogenated petroleum resin, softening point 140 ° C
* 9 Alcon M135 from Arakawa Chemical Industries, hydrogenated petroleum resin, softening point 135 ° C
* 10 Ouchi Shinsei Chemical Industry Co., Ltd., Nt-butyl-2-benzothiazyl-sulfene * 11 Flexis Co., Ltd., tetrakisbenzylthiuram disulfide

  In Comparative Example 1 in which only the resin A having a softening point of 90 ° C. is blended, the initial grip performance is very good, but the running stability is low. On the other hand, in Comparative Example 2 in which the resin B having a softening point of 170 ° C. is blended, the E ′ at 120 ° C. becomes 150 and the running stability is remarkably improved, but the initial grip performance is greatly reduced. In Comparative Example 3, the above two resins were combined and blended. However, since a resin having a low softening point was blended, E ′ at 120 ° C. hardly increased, and running stability was hardly improved.

  In contrast to these results, Example 1 in which the resin C having a softening point of 140 ° C. is improved in running stability while maintaining the initial grip performance. Furthermore, when resin B having a softening point of 170 ° C. is used in combination, running stability is greatly improved without impairing the initial grip (Examples 2 to 4). The same effect can be confirmed when resin D is blended (Example 5).

Claims (7)

10 parts by weight of at least one hydrogenated petroleum resin having a softening point of 120 ° C. or higher obtained by partially or completely hydrogenating a petroleum resin comprising a C ₅ component and / or a C ₉ component with respect to 100 parts by mass of the rubber component. A rubber composition comprising 60 parts by mass. The rubber component is further blended in an amount of 5 to 60 parts by mass of at least one resin selected from C ₉ resins having a softening point of 140 ° C. or higher and 190 ° C. or lower and containing indene. The rubber composition according to claim 1, wherein   2. The rubber composition according to claim 1, wherein the rubber component contains 70% by mass or more of a butadiene-based copolymer having a vinyl bond amount in a butadiene portion of 10% or more.   The rubber composition according to claim 3, wherein the butadiene-based copolymer includes a styrene-butadiene copolymer.   The rubber composition according to claim 4, wherein the styrene-butadiene copolymer has a styrene content of 20 to 60% by mass.   Furthermore, 60-200 mass parts of carbon black is mix | blended with respect to 100 mass parts of said rubber components, The rubber composition of Claim 1 characterized by the above-mentioned.   A pneumatic tire using the rubber composition according to claim 1 for a tread rubber.