JP2009096919A - Rubber composition for tread, tread and tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a tread capable of producing a tire excellent in processability of unvulcanized tire and having low rolling resistance and high chipping resistance, and to provide a tread and tire produced by using the rubber composition for the tread. <P>SOLUTION: This rubber composition for the tread 2 comprises a rubber component, a carbon black of ≥20 but ≤80 parts by mass, silica of ≥10 but ≤80 parts by mass, a silane coupling agent of ≥0.2 but ≤5 parts by mass, and an alkoxy group-containing compound that is a long chain alkyl ammonium salt, of ≥0.1 but ≤5 parts by mass based on 100 parts by mass of the rubber component. The tread and the tire 1 produced by use of the rubber composition for the tread are also disclosed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber composition for a tread, a tread, and a tire, and in particular, a rubber composition for a tread that is excellent in processability when unvulcanized, and that can produce a tire having low rolling resistance and high chipping resistance, The present invention relates to a tread and a tire formed using this tread rubber composition.

  In order to reduce the rolling resistance of the tire, as a method for preparing a rubber composition for a tire tread, a method of blending a solution-polymerized styrene butadiene rubber (solution-polymerized SBR: SSBR), or a reinforcing filler more than carbon black. A method using silica is well known.

  However, the rubber composition for tread obtained by the method of compounding solution-polymerized SBR or the method of compounding a large amount of silica decreases the rupture strength and elongation of the rubber after vulcanization and tends to cause chipping (anti-chipping performance). Inferior), and there was a problem that chipping of the tread occurred.

  Although a method of blending a large amount of fillers such as carbon black and silica is also conceivable, the hardness of the rubber composition for tread when not vulcanized tends to increase, so that the processability when unvulcanized is improved. There was a problem of getting worse.

For example, Patent Document 1 discloses a rubber composition for a tread containing a composite material of starch and a plasticizer.
JP 2003-192832 A

  However, in the rubber composition for a tread disclosed in Patent Document 1 above, the rubber after vulcanization does not have sufficient elongation, and the chipping resistance of a tire having a tread produced using this rubber composition for a tread There was a problem of getting worse.

  In view of the above circumstances, an object of the present invention is to provide a rubber composition for a tread that is excellent in processability during unvulcanization, can produce a tire having low rolling resistance and high chipping resistance, and the rubber for the tread. It is to provide a tread and a tire formed using the composition.

  The present invention relates to a rubber component, 20 to 80 parts by mass of carbon black, 10 to 80 parts by mass of silica, and 0.2 to 5 parts by mass with respect to 100 parts by mass of the rubber component. A rubber composition for treads, which comprises a silane coupling agent in an amount of not more than 0.1 part and an alkoxy group-containing compound in an amount of not less than 0.1 parts by mass and not more than 5 parts by mass, It is.

Moreover, this invention is a tread formed from said rubber composition for treads.
Furthermore, this invention is a tire manufactured using said tread.

  According to the present invention, a rubber composition for a tread that is excellent in processability when unvulcanized, can produce a tire having low rolling resistance and high chipping resistance, and formed using this rubber composition for tread. Treads and tires can be provided.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Rubber component>
As the rubber component used in the present invention, conventionally known rubber components can be used singly or in combination of two or more. For example, natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR) ), Styrene-butadiene copolymer rubber (SBR), solution polymerized SBR (SSBR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber, polychloroprene (CR), etc. alone Or in combination of two or more.

  Among these, as the rubber component, it is preferable to use a mixed rubber of solution polymerization SBR (SSBR) and polybutadiene rubber (BR). In this case, the characteristics of a tire manufactured using a tread composed of the rubber composition for a tread of the present invention tend to be good.

  Moreover, when using a mixed rubber of solution polymerization SBR (SSBR) and polybutadiene rubber (BR) as a rubber component, the mixing ratio (mass ratio) of solution polymerization SBR (SSBR) and polybutadiene rubber (BR) is: (Mixed mass of solution polymerization SBR (SSBR)) / (Mixed mass of polybutadiene rubber (BR)) is preferably 50/50 to 60/40, and more preferably 65/35 to 70/30.

<Carbon black>
As carbon black used in the present invention, conventionally known carbon black can be used without limitation, and for example, carbon black such as SAF, ISAF, HAF, and FEF can be used.

  In the tread rubber composition of the present invention, carbon black is contained in an amount of 20 to 80 parts by mass with respect to 100 parts by mass of the rubber component. When the content of carbon black is less than 20 parts by mass with respect to 100 parts by mass of the rubber component, some of the characteristics of the tire manufactured using the tread composed of the rubber composition for a tread of the present invention are not good. Even when the amount exceeds 80 parts by mass, some of the characteristics of the tire manufactured using the tread composed of the rubber composition for a tread of the present invention are insufficient.

  Further, the content of carbon black is preferably 25 parts by mass or more and 70 parts by mass or less, and more preferably 30 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of carbon black is 25 parts by mass or more and 70 parts by mass or less, particularly 30 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component, the rubber for treads of the present invention There exists a tendency for the characteristic of the tire manufactured using the tread which consists of a composition to become favorable.

  In the present invention, the content of carbon black when two or more different types of carbon black are used in combination means the total content of the two or more types of carbon black.

<Silica>
As the silica used in the present invention, conventionally known silica can be used without limitation. For example, silica (anhydrous silicic acid) obtained by a dry method and / or silica (hydrous silicic acid) obtained by a wet method can be used. Can be used.

  Further, the rubber composition for a tread of the present invention contains 10 parts by mass or more and 80 parts by mass or less of silica with respect to 100 parts by mass of the rubber component. When the silica content is less than 10 parts by mass with respect to 100 parts by mass of the rubber component, the characteristics of the tire manufactured using the tread comprising the rubber composition for a tread of the present invention by addition of silica are improved. When the effect is insufficient and the amount exceeds 80 parts by mass, a reduction in the characteristics of a part of a tire manufactured using a tread composed of the rubber composition for a tread of the present invention due to the addition of silica appears.

  Moreover, it is preferable that it is 20 to 80 mass parts with respect to 100 mass parts of said rubber components, and, as for content of a silica, it is more preferable that it is 30 to 80 mass parts. When the silica content is 20 parts by weight or more and 80 parts by weight or less, particularly 30 parts by weight or more and 80 parts by weight or less with respect to 100 parts by weight of the rubber component, the rubber composition for treads of the present invention. There exists a tendency for the characteristic of the tire manufactured using the tread which consists of a thing to become favorable.

Further, the nitrogen adsorption specific surface area of the silica by the BET method is preferably 100 m ² / g or more and 300 m ² / g or less, and more preferably 150 m ² / g or more and 250 m ² / g or less. When the specific surface area of nitrogen adsorption by silica BET method is 100 m ² / g or more and 300 m ² / g or less, particularly 150 m ² / g or more and 250 m ² / g or less, the rubber composition for tread of the present invention is used. There is a tendency that the characteristics of a tire manufactured using the tread to be improved.

  In addition, the nitrogen adsorption specific surface area by the BET method of a silica can be measured by the method based on ASTM-D-4820-93.

  In the present invention, the content of silica when two or more different types of silica are used in combination means the total content of the two or more types of silica.

<Silane coupling agent>
As the silane coupling agent used in the present invention, conventionally known silane coupling agents can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3 -Triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarb Moyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide Sulfide systems such as 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxy Mercapto series such as silane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, vinyltriethoxysilane, vinyltri Vinyl type such as toxisilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, etc. Glycidoxy systems such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 3 -Nitropropyl trimethoxysilane, 3-nitropropyl triethoxysilane and other nitro compounds, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane etc Chloro systems. In addition, said silane coupling agent may be used independently and may be used in combination of 2 or more type.

  The silane coupling agent used in the present invention is contained in an amount of 0.2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the silane coupling agent is less than 0.2 parts by mass with respect to 100 parts by mass of the rubber component, the reactivity between silica and the silane coupling agent becomes small, and when the content exceeds 5 parts by mass, silane A large amount of unreacted components of the coupling agent tends to remain, and there is a tendency that problems in the process such as roll adhesion occur.

  Moreover, it is preferable that content of a silane coupling agent is 0.2-5 mass parts with respect to 100 mass parts of said rubber components, It is 0.25-3 mass parts. Is more preferable.

  In the present invention, the content of the silane coupling agent when two or more different types of silane coupling agents are used in combination means the total content of the two or more silane coupling agents.

<Alkoxy group-containing compound>
As the alkoxy group-containing compound used in the present invention, an alkoxy group-containing compound represented by the following formula (1) is used.

  The alkoxy group-containing compound is contained in an amount of 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the alkoxy group-containing compound is less than 0.1 parts by mass with respect to 100 parts by mass of the rubber component, the amount of the alkoxy group-containing compound is too small and the compounding effect of the alkoxy group-containing compound is sufficient. If the amount exceeds 5 parts by mass, the amount of unreacted residue increases and the vulcanization rate is greatly changed.

  The content of the alkoxy group-containing compound is preferably 0.1 parts by mass or more and 5 parts by mass or less, and 0.5 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the rubber component. Is more preferable.

  The tread rubber composition of the present invention contains silica, but a large amount of silanol groups having strong acidic groups are present on the surface of the silica, which is a rubber at the time of vulcanization reaction delay and unvulcanized rubber. Curing of the composition (increased Mooney viscosity) is caused to adversely affect processability when unvulcanized. Moreover, the workability at the time of unvulcanization is also inhibited by a part of silica and an unreacted silane coupling agent adhering to the roll.

However, in the present invention, the ethoxy group (—C ₂ H ₅ OH) in the above alkoxy group-containing compound reacts with the silanol group on the surface of the silica, and 1 mol of the alkoxy group-containing compound has three silanol groups. Reacts to generate 3 moles of water. That is, in the present invention, in addition to the conventional reaction between silica and a silane coupling agent, the amount of silanol groups on the surface of unreacted silica is reduced by the reaction between unreacted silica and an alkoxy group-containing compound. Therefore, the delay of the vulcanization reaction and the curing of the rubber composition when not vulcanized can be suppressed. Therefore, the alkoxy group-containing compound is considered to have a function of promoting the vulcanization reaction. Further, without using the special vulcanization accelerator D (guanidine-based) used when silica is blended, it is possible to replace it with a general vulcanization accelerator (sulfenamide-based).

  Moreover, the physical properties (rolling resistance and chipping resistance) of the rubber composition after vulcanization can be made excellent by the reaction between silica and the alkoxy group-containing compound. Furthermore, since the compounding quantity of a silane coupling agent can be reduced by addition of said alkoxy group containing compound, generation | occurrence | production of the problem that an unreacted silane coupling agent adheres to a roll can be suppressed.

  In addition, the alkoxy group-containing compound dissolves on the surface of the rubber composition for a tread of the present invention even when added in a small amount to form a film on the surface of the roll. It has the effect of suppressing the adhesion of the.

  The hydroxyl group (—OH) in the alkoxy group-containing compound is effective for dispersing silica. In addition, due to the double bond present in the alkoxy group-containing compound, the alkoxy group-containing compound has high compatibility with the rubber component, and can reduce the Mooney viscosity of the tread rubber of the present invention. . Therefore, in the rubber composition for a tread of the present invention, the addition of the alkoxy group-containing compound improves the dispersibility of the rubber component, silica, and carbon black, thereby curing the rubber composition when unvulcanized. Can be suppressed.

<Other ingredients>
In addition to the above materials, the rubber composition for a tire tread of the present invention includes, for example, zinc oxide, stearic acid, oil, wax, anti-aging agent, sulfur or vulcanization accelerator commonly used in the tire industry. Various materials such as an agent may be appropriately blended.

  Here, as a zinc oxide, a conventionally well-known thing can be used, for example, Mitsui Kinzoku Co., Ltd. zinc white No. 1 etc. can be used.

  Moreover, as stearic acid, a conventionally well-known thing can be used, for example, a cocoon etc. by Nippon Oils and Fats Co., Ltd. can be used.

  Moreover, conventionally well-known thing can be used as oil, For example, process oil, vegetable oil, or a mixture thereof etc. can be used. As the process oil, for example, paraffinic process oil, naphthenic process oil, aromatic process oil, or the like can be used. As vegetable oils and fats, for example, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, beet flower oil, Sesame oil, olive oil, sunflower oil, palm kernel oil, coconut oil, jojoba oil, macadamia nut oil, tung oil, and the like can be used.

  Moreover, as a wax, a conventionally well-known thing can be used, for example, the sun knock wax by Ouchi Shinsei Chemical Co., Ltd. etc. can be used.

  As the anti-aging agent, conventionally known ones can be used. For example, Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylene manufactured by Sumitomo Chemical Co., Ltd.). Diamine) and the like can be used.

  Moreover, conventionally well-known thing can be used as sulfur, for example, powder sulfur etc. by Tsurumi Chemical Co., Ltd. can be used.

  Further, as the vulcanization accelerator, conventionally known ones can be used. For example, sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde- Those containing at least one of ammonia-based, imidazoline-based, or xanthate-based vulcanization accelerators 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, 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 (tetramethylthiuram disulfide), tetraethylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram disulfide, dipentamethylenethiuram monosulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexasulfide. Further, thiuram compounds such as tetrabutylthiuram disulfide and pentamethylenethiuram tetrasulfide can be used. Examples of thiourea compounds that can be used include thiourea compounds such as thiocarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, and diortolylthiourea. Examples of the 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 Dithiocarbamate such as cadmium It can be used carbamic acid compounds. As the aldehyde-amine system or aldehyde-ammonia system, for example, an aldehyde-amine system or aldehyde-ammonia system compound such as an acetaldehyde-aniline reaction product, butyraldehyde-aniline condensate, hexamethylenetetramine, acetaldehyde-ammonia reaction product, or the like is used. be able to. 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.

<Tire>
The rubber composition for a tread of the present invention can be produced by mixing materials such as the rubber component, carbon black, silica, silane coupling agent and alkoxy group-containing compound by, for example, kneading. And a tread of a tire can be formed by extruding the rubber composition for a tread of the present invention in an unvulcanized state.

  Further, a green tire is produced by, for example, disposing a tire member including a tread produced using the rubber composition for a tread of the present invention in a predetermined position as described above, and thereafter each tire of the green tire. The tire of the present invention is produced by vulcanizing the rubber composition constituting the member.

  FIG. 1 shows a schematic cross-sectional view of the upper left half of an example of the tire of the present invention. Here, the tire 1 includes a tread 2 that serves as a ground contact surface of the tire 1, a pair of sidewalls 3 that extend inward in the tire radial direction from both ends of the tread 2 to form the side surfaces of the tire 1, And a bead core 5 located at the inner end in the tire radial direction. A ply 6 is bridged between the bead cores 5 and 5, and a belt 7 is installed outside the ply 6 and inside the tread 2.

  For example, the ply 6 has an angle of, for example, 70 ° to 90 ° with respect to the tire equator CO (a virtual line obtained by rotating the center of the width of the outer peripheral surface of the tire 1 once in the circumferential direction of the outer peripheral surface of the tire 1). A plurality of cords can be formed from a rubber sheet embedded in the rubber composition. Further, the ply 6 is folded and locked around the bead core 5 from the tread 2 through the sidewall 3 to the outside in the tire axial direction.

  The belt 7 can be formed from, for example, a rubber sheet in which a plurality of cords that form an angle of, for example, 40 ° or less with respect to the tire equator CO is embedded in the rubber composition.

  Further, the tire 1 may be provided with a band (not shown) for suppressing the peeling of the belt 7 as necessary. Here, the band can be installed by, for example, a rubber sheet in which a plurality of cords are embedded in a rubber composition and spirally wound around the belt 7 substantially parallel to the tire equator CO.

  The tire 1 has a bead apex 8 extending outward in the tire radial direction from the bead core 5, and an inner liner 9 is installed inside the ply 6. Are covered with a side wall 3 and a clinch 4 extending inward in the tire radial direction from the side wall 3.

  In the above, a tire for a passenger car is illustrated as the tire 1 of the present invention, but the present invention is not limited to this, and is used for various vehicles such as a passenger car, a truck, a bus, and a heavy vehicle. Tire.

  The rubber composition for a tread of the present invention comprises 20 parts by mass or more and 80 parts by mass or less of carbon black, 10 parts by mass or more and 80 parts by mass or less of silica with respect to 100 parts by mass of the rubber component; The rubber composition for treads of the present invention is unvulcanized because it contains 2 parts by mass or more and 5 parts by mass or less of a silane coupling agent and 0.1 parts by mass or more and 5 parts by mass or less of an alkoxy group-containing compound. In some cases, since the processability is excellent, a tire tread can be easily formed, and a tire manufactured using the tread has low rolling resistance and high chipping resistance.

  Therefore, the rubber composition for a tread of the present invention is preferably used for forming a tire tread.

<Preparation of unvulcanized rubber composition>
According to the composition shown in Table 1, rubber component, carbon black, silica, silane coupling agent, alkoxy group-containing compound, oil, wax, anti-aging agent, stearic acid and zinc oxide are mixed for 5 minutes using a 1.7 L Banbury mixer. Kneaded. Then, according to the formulation shown in Table 1, sulfur and a vulcanization accelerator were added to the kneaded material thus obtained, and kneaded for 7 minutes using an open roll. Example 1 and Example 2 and comparison Each unvulcanized rubber composition of Example 1 was obtained.

  The numerical values shown in the rubber column of Table 1 indicate the mixing ratio (mass ratio) of rubber components made of a mixed rubber of SSBR and BR, and are shown in the additive column of Table 1. In the numerical values, the amount of each additive is expressed in parts by mass when the amount of the rubber component is 100 parts by mass. Moreover, as the alkoxy group-containing compound, the alkoxy group-containing compound represented by the above formula (1) was used.

(Note 1) SSBR: 2530 manufactured by Asahi Kasei Corporation
(Note 2) BR: 1220 manufactured by Nippon Zeon Co., Ltd.
(Note 3) Carbon black: N220 manufactured by Tokai Carbon Co., Ltd.
(Note 4) Silica: VN3 manufactured by Tosoh Corp. (nitrogen adsorption specific surface area by BET method: 200 m ² / g)
(Note 5) Silane coupling agent: 6062N manufactured by Toray Dow Co., Ltd.
(Note 6) Alkoxy group-containing compound: Actiplast PP manufactured by Bayer Co., Ltd.
(Note 7) Oil: AH40 manufactured by Idemitsu Kosan Co., Ltd.
(Note 8) Wax: 0355 manufactured by Nippon Seiwa Co., Ltd.
(Note 9) Anti-aging agent: 6C manufactured by Sumitomo Chemical Co., Ltd.
(Note 10) Stearic acid: Tsubaki made by NOF Corporation (Note 11) Zinc oxide: ^# 3 made by Mitsui Mining & Smelting Co., Ltd.
(Note 12) Sulfur: Tsurumi Chemical Co., Ltd. (Note 13) Vulcanization accelerator: DZ made by Ouchi Shinsei Chemical Industry Co., Ltd.
<Mooney viscosity and scorch time measurement>
About each unvulcanized rubber composition of Example 1 and Example 2 produced as mentioned above, and the comparative example 1, "Unvulcanized rubber-physical characteristic-part 1 of JIS K 6300-1: 2001: The Mooney viscosity and scorch time were measured according to “How to obtain viscosity and scorch time by Mooney viscometer”, respectively. And while calculating the relative value (Mooney viscosity index) of the Mooney viscosity with respect to the unvulcanized rubber composition of Comparative Example 1 from the measured value of Mooney viscosity by the following formula (2), the following formula (3): The relative value (scorch time index) of the scorch time for the unvulcanized rubber composition of Comparative Example 1 was calculated from the measured value of the scorch time. The results are shown in the Mooney viscosity index column and the Scorch time index column of Table 1, respectively.

A smaller value in the Mooney viscosity column in Table 1 indicates that the Mooney viscosity is lower, indicating that the processability when unvulcanized is excellent. In addition, the smaller the value in the scorch time column, the shorter the scorch time, and the better the workability when unvulcanized.
(Mooney viscosity index) = 100 × (measured value of Mooney viscosity of each of the unvulcanized rubber compositions of Examples 1 and 2 and Comparative Example 1) / (Mooney of the unvulcanized rubber composition of Comparative Example 1) Viscosity measurement value) (2)
(Scorch time index) = 100 × (measured value of scorch time of each of the unvulcanized rubber compositions of Examples 1 and 2 and Comparative Example 1) / (Scorch of the unvulcanized rubber composition of Comparative Example 1) Time measurement value) (3)
<Rolling resistance test>
Vulcanized rubber sheets were prepared by vulcanizing the unvulcanized rubber compositions of Examples 1 and 2 and Comparative Example 1 prepared as described above at 150 ° C. for 30 minutes, respectively.

  And each test piece of Example 1, Example 2, and Comparative Example 1 was produced from the vulcanized rubber sheet produced as described above, and viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) was used. The loss tangent (tan δ) was measured under the conditions of a temperature of 30 ° C., an initial strain of 10%, and a dynamic strain of 2%. And the relative value (rolling resistance index) of the loss tangent with respect to the test piece of Comparative Example 1 was calculated from the measured value of the loss tangent by the following formula (4). The results are shown in the rolling resistance index column of Table 1.

The larger the numerical value in the column of the rolling resistance index in Table 1, the lower the rolling resistance and the lower the fuel consumption.
(Rolling resistance index) = 100 × (measured value of loss tangent of test piece of Comparative Example 1) / (measured value of loss tangent of each test piece of Example 1, Example 2 and Comparative Example 1) (4 )
<Tensile stress at cutting and elongation test at cutting>
The test pieces of Example 1, Example 2 and Comparative Example 1 were prepared from the vulcanized rubber sheet prepared as described above, and JIS K 6251: 2004 “Vulcanized rubber and thermoplastic rubber—of tensile properties. According to “How to obtain”, the tensile stress TB at cutting and the elongation EB at cutting were measured. And while calculating the relative value (tensile index at the time of cutting) of the tensile stress TB at the time of cutting with respect to the test piece of comparative example 1 from the measured value of tensile stress TB at the time of cutting by the following formula (5), the following formula ( 6), the relative value of the elongation EB at break (elongation index at break) with respect to the test piece of Comparative Example 1 was calculated from the measured value of the elongation EB at break. The results are shown in the column of tensile stress index at cutting and column of elongation index at cutting in Table 1, respectively.

The larger the numerical value in the column of tensile stress index at cutting in Table 1, the higher the tensile stress at cutting and the higher the chipping resistance. In addition, the larger the numerical value in the column of elongation index at break in Table 1, the greater the elongation at break and the higher the chipping resistance.
(Tensile stress index during cutting) = 100 × (Measured value of tensile stress TB during cutting of each test piece of Examples 1 and 2 and Comparative Example 1) / (Tensile stress during cutting of the test piece of Comparative Example 1) TB measured value) (5)
(Elongation index at break) = 100 × (Measured value of elongation EB at break of each test piece of Examples 1 and 2 and Comparative Example 1) / (Measurement of elongation EB at break of the test piece of Comparative Example 1) Value) ... (6)
<Evaluation>
As shown in Table 1, the unvulcanized rubber compositions of Example 1 and Example 2 in which 2.5 parts by mass of the alkoxy group-containing compound represented by the above formula (1) were contained per 100 parts by mass of the rubber component Both the Mooney viscosity index and the scorch time index can be greatly reduced compared to the unvulcanized rubber composition of Comparative Example 1 that does not contain the alkoxy group-containing compound. Therefore, it was confirmed that the unvulcanized rubber compositions of Example 1 and Example 2 can greatly improve the processability when unvulcanized as compared with the unvulcanized rubber composition of Comparative Example 1.

  Moreover, as shown in Table 1, Example 1 and Example 2 which were made to contain 2.5 mass parts of alkoxy-group containing compounds represented by said Formula (1) with respect to 100 mass parts of rubber components are unvulcanized | cured. The vulcanized rubber obtained by vulcanizing the rubber composition is more rolled than the vulcanized rubber obtained by vulcanizing the unvulcanized rubber composition of Comparative Example 1 which does not contain the alkoxy group-containing compound. The resistance index, the tensile stress index during cutting, and the elongation index during cutting can be significantly increased. Therefore, when the tire tread is produced using the unvulcanized rubber composition of Example 1 and Example 2, the tire tread is produced using the unvulcanized rubber composition of Comparative Example 1. In comparison, the rolling resistance of the tire can be lowered and the chipping resistance can be increased.

  Therefore, from the above results, it is considered that the unvulcanized rubber compositions of Examples 1 and 2 are preferably used as a rubber composition for a tire tread.

  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.

  According to the present invention, a rubber composition for a tread that is excellent in processability when unvulcanized, can produce a tire having low rolling resistance and high chipping resistance, and formed using this rubber composition for tread. Treads and tires can be provided.

It is typical sectional drawing of the upper left half of an example of the tire of this invention.

Explanation of symbols

1 tire, 2 tread, 3 sidewall, 4 clinch, 5 bead core, 6
Ply, 7 belt, 8 bead apex, 9 inner liner.

Claims (3)

20 parts by weight to 80 parts by weight of carbon black, 10 parts by weight to 80 parts by weight of silica, and 0.2 parts by weight to 5 parts by weight with respect to 100 parts by weight of the rubber component A silane coupling agent and 0.1 to 5 parts by mass of an alkoxy group-containing compound,
The rubber composition for a tread, wherein the alkoxy group-containing compound is a compound represented by the following formula (1).

  A tread formed from the rubber composition for a tread according to claim 1.   A tire manufactured using the tread according to claim 2.

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