JP2008169264A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition providing a pneumatic tire exhibiting excellent on-ice performance, wet performance and fuel efficiency, and having good wear resistance. <P>SOLUTION: The rubber composition has closed cells, and contains (B) 3-50 pts.mass of an inorganic compound powder represented by M-xSiO<SB>2</SB>-yH<SB>2</SB>O and having ≤50 μm average particle diameter and (C) 10-150 pts.mass of silica as a reinforcing filler based on (A) 100 pts.mass of at least one kind of a rubber component selected from a natural rubber and a diene synthetic rubber, and further contains (D) 1-30 mass% of a silane coupling agent represented by formula (II) based on the silica of the component (C). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rubber composition and a pneumatic tire using the rubber composition. More specifically, the present invention is excellent in workability during rubber processing, air performance on ice, WET performance and low fuel consumption, and air with good wear resistance. The present invention relates to a rubber composition capable of providing a filled tire, and a pneumatic tire having the above-described performance using the rubber composition in a tread.

Since spike tires have been regulated, research on tire treads has been actively carried out in order to improve tire braking and driving performance (hereinafter referred to as ice performance) on icy and snowy road surfaces. On an icy and snowy road surface, a water film is likely to be generated due to frictional heat between the icy and snowy road surface and the tire, and the water film reduces the coefficient of friction between the tire and the icy and snowy road surface. For this reason, in order to improve the performance on ice in the tire, it is necessary to improve the water film removing ability, the edge effect and the spike effect of the tire tread.
In order to give the tire tread the ability to remove water film, a lot of micro drain grooves (depth and width of about 100μm) are provided on the road surface of the tire. Increase the coefficient of friction on the road surface. However, in this case, although the performance on ice in the initial use of the tire can be improved, there is a problem that the performance on ice gradually deteriorates as the tire wears. Therefore, in order to prevent the performance on ice from deteriorating even if the tires wear, it is conceivable to form bubbles in the tread with the aim of removing the microscopic water film. In addition, a cylindrical one made of an organic fiber resin is considered.
In addition, it has been proposed to further increase the coefficient of friction on the icy and snowy road surface by adding fine particles to the above-mentioned organic fiber and adding a scratch effect (for example, Patent Document 1 and Patent Document 2). reference).

By incorporating into the rubber composition a cylindrical foam with the above organic fiber resin or a long foam in which fine particles are contained in the cylindrical foam, the performance on ice has been greatly improved by improving the drainage effect and scratching effect. However, inferior to unfoamed rubber from the viewpoint of wear resistance is a major problem that cannot be avoided.
In recent years, it has been found that adding a hydrophilic inorganic filler improves on-ice performance and WET performance, but even with this method, wear resistance tends to decrease, and a complete solution to the problem is not possible. Not reached.

As the filler component used in the tread, carbon black and silica are mainly used, and silica is used as a filler capable of improving wet performance and low fuel consumption. However, when silica is used, it is usually used in combination with a silane coupling agent in order to improve the reinforcing property as a filler, the dispersibility in the rubber component, and ensure the bond between the silica and the polymer. However, when used in combination with a silane coupling agent, there is a problem that the kneading temperature cannot be increased.
In order to improve the wear resistance, it is conceivable to increase the amount of the reinforcing filler. However, simply increasing the blending amount inevitably deteriorates the performance on ice and the workability.

JP 2003-201371 A JP 2001-233993 A

  Under such circumstances, the present invention is a rubber composition capable of providing a pneumatic tire having excellent workability during rubber processing, excellent on-ice performance, WET performance, and low fuel consumption, and good wear resistance. In addition, an object of the present invention is to provide a pneumatic tire having the above-described performance using the rubber composition as a tread.

［式中、Ｒ¹はＲ⁶Ｏ−、Ｒ⁶Ｃ（＝Ｏ）Ｏ−、Ｒ⁶Ｒ⁷Ｃ＝ＮＯ−、Ｒ⁶Ｒ⁷ＣＮＯ−、Ｒ⁶Ｒ⁷Ｎ−又は−（ＯＳｉＲ⁶Ｒ⁷）_m（ＯＳｉＲ⁵Ｒ⁶Ｒ⁷）（ただし、Ｒ⁶及びＲ⁷は、それぞれ独立に水素原子又は炭素数１〜１８の一価の炭化水素基、である。）Ｒ²はＲ¹、水素原子又は炭素数１〜１８の一価の炭化水素基、Ｒ³はＲ¹、Ｒ²又は−[Ｏ（Ｒ⁸Ｏ）_aＨ] 基（ただし、Ｒ⁸は炭素数１〜１８のアルキレン基、ａは１〜４の整数である。）、Ｒ⁴は炭素数１〜１８の二価の炭化水素基、Ｒ⁵は炭素数１〜１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。］
で表されるシランカップリン剤を、前記（Ｃ）成分のシリカに対して１〜３０質量％の割合で含むことを特徴とするゴム組成物、
（２） 前記（Ｂ）成分の平均粒径が、１０〜５０μｍである上記（１）のゴム組成物、
（３） 前記（Ｂ）成分が下記一般式（III）
Ａｌ₂Ｏ₃・ｍＳｉＯ₂・ｎＨ₂Ｏ ………（III）
〔式中のｍは１〜４の整数であり、ｎは０〜４の整数である。〕で表される無機化合物粉体である上記（１）又は（２）のゴム組成物、
（４） 前記（Ｂ）成分が水酸化アルミニウムからなる粉体である上記（１）〜（３）いずれかのゴム組成物、
（５） 総補強性充填材の内（Ｃ）成分の占める割合が、質量比で３０〜１００質量％の範囲である上記（１）〜（４）いずれかのゴム組成物、
（６） （Ｃ）成分以外の補強性充填材がカーボンブラックである上記（５）のゴム組成物、
（７） さらに、（Ａ）成分１００質量部に対して、（Ｅ）微粒子含有有機繊維を０．０２〜２０質量部含む上記（１）〜（６）いずれかのゴム組成物、
（８） 前記（Ｅ）成分が、有機繊維を構成する素材１００質量部に対して、微粒子を５〜９０質量部含有する上記（７）のゴム組成物、
（９） 前記（Ｅ）成分の有機繊維を構成する素材がポリエチレン及び／又はポリプロピレンからなる結晶性高分子であり、かつ融点が１９０℃以下である上記（７）又は（８）のゴム組成物、
（１０） 前記（Ｅ）成分の微粒子を構成する素材が、無機微粒子及び有機微粒子から選択される上記（７）〜（９）いずれかのゴム組成物、及び
（１１） 上記（１）〜（１０）いずれかのゴム組成物をトレッド部の路面と実質的に接する面に用いたことを特徴とする空気入りタイヤ、
を提供するものである。 As a result of intensive studies to achieve the above-mentioned object, the present inventor has, as a result, an inorganic compound powder having a specific structure and a specific average particle diameter, a specific silane, It has been found that the object can be achieved by a rubber composition containing a coupling agent and silica. The present invention has been completed based on such findings.
That is, the present invention
(1) It has closed cells, and (A) at least one rubber component selected from natural rubber and diene-based synthetic rubber, and 100 parts by mass thereof, (B) the following general formula (I)
M ・ xSiO ₂・ yH ₂ O …… (I)
[M in the formula is at least one metal oxide or metal hydroxide selected from Al, Mg, Ti, and Ca, and x and y are both integers of 0 to 10. ]
3 to 50 parts by weight of an inorganic compound powder having an average particle size of 50 μm or less, (C) 10 to 150 parts by weight of silica as a reinforcing filler, and (D) the following general formula (II)

[In the formula, R ¹ is ^{R 6 O-, R 6 C (} = O) O-, R 6 R 7 C = NO-, R 6 R 7 CNO-, R 6 R 7 N- or - (OSiR ⁶ R ⁷ ) _m (OSiR ⁵ R ⁶ R ⁷ ) (wherein R ⁶ and R ⁷ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms) R ² is R ¹ , A hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R ³ is R ¹ , R ² or — [O (R ⁸ O) _a H] group (where R ⁸ is alkylene having 1 to 18 carbon atoms) Group, a is an integer of 1 to 4), R ⁴ represents a divalent hydrocarbon group having 1 to 18 carbon atoms, R ⁵ represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, x, y and z are numbers satisfying the relationship of x + y + z = 3, 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ]
A rubber composition comprising a silane coupling agent represented by the formula (C) in a proportion of 1 to 30% by mass with respect to the silica of the component (C):
(2) The rubber composition according to (1), wherein the average particle size of the component (B) is 10 to 50 μm,
(3) The component (B) is represented by the following general formula (III)
Al ₂ O ₃ · mSiO ₂ · nH ₂ O ……… (III)
[M in the formula is an integer of 1 to 4, and n is an integer of 0 to 4. ] The rubber composition of the above (1) or (2), which is an inorganic compound powder represented by
(4) The rubber composition according to any one of (1) to (3), wherein the component (B) is a powder comprising aluminum hydroxide,
(5) The rubber composition according to any one of (1) to (4) above, wherein the proportion of the component (C) in the total reinforcing filler is in the range of 30 to 100% by mass.
(6) The rubber composition according to (5), wherein the reinforcing filler other than the component (C) is carbon black,
(7) Furthermore, rubber composition in any one of said (1)-(6) which contains 0.02-20 mass parts of (E) fine particle containing organic fiber with respect to 100 mass parts of (A) component,
(8) The rubber composition according to (7), wherein the component (E) contains 5 to 90 parts by mass of fine particles with respect to 100 parts by mass of the material constituting the organic fiber.
(9) The rubber composition according to the above (7) or (8), wherein the material constituting the organic fiber of the component (E) is a crystalline polymer composed of polyethylene and / or polypropylene and has a melting point of 190 ° C. or lower. ,
(10) The rubber composition according to any one of (7) to (9), wherein the material constituting the fine particles of the component (E) is selected from inorganic fine particles and organic fine particles, and (11) the above (1) to ( 10) A pneumatic tire using any one of the rubber compositions on a surface substantially in contact with the road surface of the tread portion,
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, while being excellent in workability | operativity at the time of rubber processing, it is excellent in on-ice performance, WET performance, and low fuel consumption, and the rubber composition which can give a pneumatic tire with favorable abrasion resistance, and this rubber composition It is possible to provide a pneumatic tire having the above-described performance using a thing for a tread.

The rubber composition of the present invention has closed cells, (A) at least one rubber component selected from natural rubber and diene synthetic rubber, (B) inorganic compound powder (C) silica, and (D) It consists of a rubber composition containing a silane coupling agent made of protected mercaptosilane.
The rubber composition having closed cells is preferably used as a tread rubber having a foamed layer substantially in contact with the road surface. The foamed rubber layer has a foaming ratio in the range of 3 to 50%, more preferably 15 to 40%.
By setting the foaming rate within the above range, excellent on-ice performance can be ensured by maintaining wear resistance and DRY performance and securing the volume of the recess in the tread.

The rubber of component (A) may contain only natural rubber, only diene synthetic rubber, or both. There is no restriction | limiting in particular as said diene type synthetic rubber, Although it can select suitably according to the objective from well-known things, For example, a styrene-butadiene copolymer (SBR), polyisoprene (IR), polybutadiene ( BR) and the like. Among these diene-based synthetic rubbers, cis-1,4-polybutadiene is preferable, and those having a cis content of 90% or more are particularly preferable in that the glass transition temperature is low and the effect on performance on ice is large.
In addition, when using the rubber composition of this invention for the tread etc. of a tire, what has a glass transition temperature of -60 degrees C or less as said rubber component is preferable. When a rubber component having such a glass transition temperature is used, the tread or the like is advantageous in that it maintains sufficient rubber elasticity even in a low temperature range and exhibits good performance on ice.

In the rubber composition of the present invention, as the component (B), the following general formula (I)
M · xSiO ₂ · yH ₂ O (I)
[M in Formula (I) is a metal oxide or metal hydroxide selected from Al, Mg, Ti, and Ca, and x and y are integers of 0 to 10, which may be different from each other. ]
It is necessary to contain the inorganic compound powder represented by these.
When the x and y are both 0, the inorganic compound powder represented by the general formula (I) is at least one metal oxide or metal hydroxide selected from Al, Mg, Ti, and Ca. Become. Component (B) is at least one inorganic compound having an average particle size of 50 μm or less.
Specific examples of the inorganic compound represented by the general formula (I) include alumina (Al ₂ O ₃ ), magnesium hydroxide (Mg (OH) ₂ ), magnesium oxide (MgO ₂ ), and titanium white (TiO ₂ ). titanium black (TiO _2n-1), talc _{(3MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O) and the like. In addition, magnesium calcium silicate (CaMgSiO ₄ ) and magnesium silicate (MgSiO ₃ ) also exhibit the same effects as the inorganic compound of the present invention.

Moreover, it is preferable that the said general formula (I) is an inorganic compound or aluminum hydroxide represented by the following general formula (III).
Al ₂ O ₃ · mSiO ₂ · nH ₂ O (III)
M in the formula (III) is an integer of 1 to 4, and n is an integer of 0 to 4.
Specific examples of the inorganic compound represented by the general formula (III) include clay (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ .2SiO ₂ .2H ₂ O), pyrophyllite (Al ₂ O ₃ · 4SiO ₂ · H ₂ O), bentonite (Al ₂ O ₃ · 4SiO ₂ · 2H ₂ O) and the like. Moreover, the aluminum hydroxide used by this invention also contains an alumina hydrate.

The component (B) has an average particle size of 50 μm or less, preferably 10 to 50 μm, and more preferably 15 to 30 μm. By setting the average particle diameter of the component (B) within the above range, it is possible to obtain excellent WET performance while maintaining the fracture resistance of the rubber for tire tread, particularly the wear resistance.
Preferred components (B) used in the present invention are clay (Al ₂ O ₃ .2SiO ₂ ), aluminum hydroxide [Al (OH) ₃ ], and alumina (Al ₂ O ₃ ). Moreover, the (B) component which has the said characteristic used by this invention can be used individually or in mixture of 2 or more. Of these, aluminum hydroxide [Al (OH) ₃ ] is particularly preferable.
In addition, inorganic compound powders that do not satisfy the above conditions, for example, other structures such as sulfides, sulfates, and carbonates selected from Al, Mg, Ti, and Ca are not effective in improving wet skid performance.

  The compounding quantity of the (B) component which has the said characteristic used by this invention is 5-50 mass parts with respect to 100 mass parts of said (A) rubber components, Preferably, it is 5-20 mass parts. By setting the blending amount of the component (B) within the above range, the wear resistance can be maintained and excellent WET performance can be obtained.

In the rubber composition of the present invention, it is necessary to further contain (C) silica as a reinforcing filler.
In the rubber composition of the present invention, examples of the silica used as the component (C) include wet silica (hydrous silicic acid) and dry silica (anhydrous silicic acid). Wet silica is most preferred because it is most effective in achieving both low fuel consumption (low rolling resistance).
This wet silica preferably has a nitrogen adsorption specific surface area (N ₂ SA) by the BET method of 140 to 280 m ² / g from the viewpoint of balance between reinforcement, workability, WET performance, and wear resistance, etc. 170 More preferably, it is -250 m < ² > / g. Suitable wet silica includes, for example, AQ, VN3, LP, NA, etc. manufactured by Tosoh Silica Co., Ltd. and Ultrazil VN3 (N ₂ SA: 210 m ² / g) manufactured by Degussa.
This (C) component silica is blended in an amount of 10 to 150 parts by weight, preferably 40 to 90 parts by weight, per 100 parts by weight of the rubber component (A). When the blending amount of the silica is less than 10 parts by mass, the effect of improving the reinforcing properties and other physical properties is insufficient, and when it exceeds 150 parts by mass, workability and rolling resistance are deteriorated.

In the rubber composition of the present invention, carbon black can be used as a reinforcing filler together with the silica of the component (C) as necessary. The blending amount of the carbon black is preferably 0 to 100 parts by weight, and 0 to 50 parts by weight with respect to 100 parts by weight of the rubber component (A) from the viewpoint of the reinforcing effect, workability, and other performances. More preferred. Examples of carbon black include HAF, N339, IISAF, ISAF, and SAF. Nitrogen adsorption specific surface area of the carbon black _{(N 2 SA, JIS K 6217-2} : conforms to 2001) is preferably from 70~160m ² / g, more preferably 90~160m ² / g. Further, preferably dibutyl phthalate oil absorption: a (DBP, JIS K 6217-4 compliant to 2001) of carbon black 80~170cm ³ / 100g. By using these carbon blacks, the effect of improving various physical properties, particularly fracture characteristics, is increased. In consideration of wear resistance, SAF having a fine particle size is preferable.
In the total reinforcing filler, the proportion of silica of component (C) is 30 to 30 by mass ratio.
It is preferable that it is 100 mass%.

  In the rubber composition of the present invention, as the component (D), the general formula (II)

A silane coupling agent comprising a protected mercaptosilane represented by the formula:
In formula (II), R ¹ is ^{R 6 O-, R 6 C (} = O) O-, R 6 R 7 C = NO-, R 6 R 7 CNO-, R 6 R 7 N- or - ( OSiR ⁶ R ⁷ ) _m (OSiR ⁵ R ⁶ R ⁷ ) (wherein R ⁶ and R ⁷ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms), R ² is R ¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R ³ is an R ¹ , R ² or — [O (R ⁸ O) _a H] group (wherein R ⁸ has 1 to 1 carbon atoms) 18 is an alkylene group, a is an integer of 1 to 4.), R ⁴ is a divalent hydrocarbon group having 1 to 18 carbon atoms, and R ⁵ is a monovalent hydrocarbon group having 1 to 18 carbon atoms. , X, y, and z are numbers satisfying the relationship of x + y + z = 3, 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1.
In the general formula (II), examples of the monovalent hydrocarbon group having 1 to 18 carbon atoms include an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, and an aryl group having 6 to 18 carbon atoms. And an aralkyl group having 7 to 18 carbon atoms. Here, the alkyl group and alkenyl group may be linear, branched or cyclic, and the aryl group and aralkyl group have a substituent such as a lower alkyl group on the aromatic ring. Also good.

Specific examples of the monovalent hydrocarbon group having 1 to 18 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, and tert-butyl group. , Pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, Examples include tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group and the like.
In the general formula (II), the alkylene group having 1 to 18 carbon atoms represented by R ⁸ may be linear, branched, or cyclic, and is preferably linear. is there. Examples of the linear alkylene group include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, a decamethylene group, and a dodecamethylene group.
Examples of the divalent hydrocarbon group having 1 to 18 carbon atoms represented by R ⁴ include an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, and a cycloalkylene having 5 to 18 carbon atoms. Groups, cycloalkylalkylene groups having 6 to 18 carbon atoms, arylene groups having 6 to 18 carbon atoms, and aralkylene groups having 7 to 18 carbon atoms. The alkylene group and alkenylene group may be linear or branched, and the cycloalkylene group, cycloalkylalkylene group, arylene group, and aralkylene group may have a substituent such as a lower alkyl group on the ring. You may have.
R ⁴ is preferably an alkylene group having 1 to 6 carbon atoms, and particularly preferably a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, or a hexamethylene group. it can.

Examples of the silane coupling agent represented by the general formula (II) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3 -Lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexa Noylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2- Kuta Neu Lucio ethyltrimethoxysilane, 2- deca Neu thio ethyltrimethoxysilane, and the like of 2-lauroyl thio ethyltrimethoxysilane.
By using such a silane coupling agent as the component (D), the rubber composition of the present invention has a longer time until burns occur due to a decrease in the viscosity of the unvulcanized rubber. It is possible to knead for a long time, and the workability during rubber processing is excellent, and the dispersion of silica into the rubber component is improved, and the reactivity between silica and polymer is improved, thereby reducing hysteresis loss. Utilizing this improvement, it becomes possible to increase the blending amount of the reinforcing filler, and as a result, a pneumatic tire with good wear resistance can be obtained.
In the present invention, the silane coupling agent of component (D) may be used alone or in combination of two or more. Moreover, the compounding quantity is selected in 2-30 mass% with respect to the silica of the said (C) component. If the blending amount of the silane coupling agent is within the above range, the effects of the present invention are sufficiently exhibited. A preferable blending amount is in the range of 5 to 15% by mass.
Furthermore, in order to couple the silane coupling agent and the polymer, it is preferable to add a proton donor typified by DPG (diphenylguanidine) or the like as a deprotecting agent in the final kneading step. The amount used is preferably from 0.1 to 5.0 parts by weight, more preferably from 0.2 to 3.0 parts by weight, per 100 parts by weight of the rubber component.

In the rubber composition of the present invention, it is preferable that 0.02 to 20 parts by mass of fine particle-containing organic fibers containing fine particles in organic fibers as component (E).
When the component (E) is used in the foamed rubber layer, the effect on water removal and friction increase on the tire surface is exhibited and the performance on ice is enhanced. In addition, as will be described later, when a material having a relatively high hardness is used for the fine particles used in the component (E), the surface of the vulcanized rubber and the molded product is affected during extrusion due to the relationship with the diameter of the organic fiber to be contained. Moreover, the workability | operativity in a factory is caused with such a cause. Therefore, it is preferable that the rubber layer contains organic fibers not containing fine particles together with the component (E) in a predetermined ratio.
As such a ratio, the ratio of the organic fiber / (E) component-containing organic fiber is in the range of 98/2 to 2/98 by mass ratio, particularly in the range of 95/5 to 5/95. It is preferable to do. Among them, the amount of the component (E) is preferably 0.02 to 20 parts by mass with respect to 100 parts by mass of the rubber component (A). More preferably, it is 0.1-15 mass parts.

In the present invention, the total amount of the organic fibers and the component (E) in the rubber layer is 1 to 20 parts by weight, particularly preferably 1.5 to 15 parts by weight, based on 100 parts by weight of the rubber component (A). Part is desirable.
By making these total amounts within the above range, the extrusion workability is improved to eliminate rough skin, and the effect of blending fibers can be obtained sufficiently. In the tread of a tire, the occurrence of cracks is suppressed and the edge effect or spike effect A corresponding improvement in performance on ice is recognized.

The organic fibers used in the organic fiber and the component (E) are not necessarily used simultaneously with the same material, shape, diameter, length, etc., and different organic fibers are used. However, it is desirable to use organic fibers in the range having the following properties.
There is no restriction | limiting in particular in the material of the organic fiber used for an organic fiber and (E) component, According to the objective, it can select suitably. However, as described above, a fiber having a viscosity characteristic that becomes lower than the viscosity of the rubber matrix of the rubber component (A) from the relationship with the rubber component until the maximum temperature of vulcanization is reached at the time of vulcanization. In the present invention, it is preferable to use a constituent resin. That is, the resin constituting the organic fiber preferably has a thermal characteristic that the rubber composition melts (including softening) before reaching the maximum vulcanization temperature.

The above-mentioned long air bubbles that can function as a micro drainage groove in the vulcanized rubber obtained by vulcanizing the rubber composition when having the resin constituting the organic fiber with such thermal characteristics Can be easily formed.
The maximum vulcanization temperature means the maximum temperature reached by the rubber composition during vulcanization of the rubber composition. For example, in the case of mold vulcanization, it means the maximum temperature that the rubber composition reaches from the time the rubber composition enters the mold to the time it exits the mold and is cooled. The maximum vulcanization temperature can be measured, for example, by embedding a thermocouple in the rubber composition. The viscosity of the rubber matrix means a fluid viscosity, and is measured using, for example, a cone rheometer, a capillary rheometer, or the like. The viscosity of the resin constituting the organic fiber means melt viscosity, and is measured using, for example, a cone rheometer, a capillary rheometer, or the like.
Accordingly, preferred examples of the resin selected in the present invention include a crystalline polymer resin having a melting point lower than the maximum vulcanization temperature.

  In the above crystalline polymer, the larger the difference between the melting point and the maximum vulcanization temperature of the rubber composition, the faster it melts during vulcanization of the rubber composition. The time when it becomes lower is earlier. For this reason, when the polymer is melted, the gas present in the rubber composition such as the gas generated from the foaming agent blended in the rubber composition collects inside the polymer having a lower viscosity than the rubber matrix. As a result, in the vulcanized rubber, the closed cells having a resin layer containing fine particles between the rubber matrix, that is, the capsule-like long cells covered with the resin are efficiently removed without being crushed. It is formed.

In the tire tread rubber having a foam layer substantially in contact with the road surface, this capsule-like long bubble appears on the surface of the tread, and the groove caused by surface wear functions as the above-mentioned micro drainage groove, eliminating the water film effect At the same time, the edge effect and the spike effect are fully exhibited.
On the other hand, when the melting point of the resin constituting the organic fiber is close to the maximum vulcanization temperature of the rubber composition, it does not melt quickly at the initial stage of vulcanization but melts at the end of vulcanization. At the end of vulcanization, part of the gas present in the rubber composition is taken into the vulcanized rubber matrix and does not collect inside the molten resin. As a result, the long bubbles that function effectively as the micro drainage grooves are not efficiently formed, and when the resin melting point of the organic fiber is too low, the organic fiber is blended in the rubber composition and kneaded. At this time, fusion between the organic fibers occurs, resulting in poor dispersion of the organic fibers. This also prevents the formation of long bubbles that can function as micro drainage grooves efficiently. Accordingly, the melting point of the organic fiber resin is preferably selected in such a range that does not melt and soften at the temperature in each step before vulcanization and the viscosity of the rubber matrix and the resin is reversed during the vulcanization step.

The upper limit of the melting point of the resin constituting the organic fiber is not particularly limited, but is preferably selected in consideration of the above points, and is lower than the maximum vulcanization temperature of the rubber matrix and lower by 10 ° C. or more. It is preferably 20 ° C. or more, particularly preferably. The industrial vulcanization temperature of the rubber composition is generally about 190 ° C. at the maximum, but for example, when the maximum vulcanization temperature is set to exceed 190 ° C., The melting point is selected within a range of 190 ° C. or less, preferably 180 ° C. or less, and more preferably 170 ° C. or less.
In addition, melting | fusing point of the said resin can be measured using a well-known melting | fusing point measuring apparatus etc., for example, the melting peak temperature measured using the DSC measuring apparatus can be made into the said melting | fusing point.

From the above, the resin constituting the organic fiber may be formed of a crystalline polymer and / or an amorphous polymer. However, as described above, in the present invention, it is formed from an organic material containing a large amount of crystalline polymer in that the viscosity change occurs suddenly at a temperature where there is a phase transition and viscosity control is easy. Preferably, it is formed from only a crystalline polymer.
Specific examples of such a crystalline polymer include, for example, polyethylene (PE), polypropylene (PP), polybutylene, polybutylene succinate, polyethylene succinate, syndiotactic-1,2-polybutadiene (SPB), polyvinyl Single composition polymers such as alcohol (PVA), polyvinyl chloride (PVC), etc., and those whose melting point is controlled to an appropriate range by copolymerization, blending, etc. can be used, and further additives are added to these resins Can also be used. These may be used individually by 1 type and may use 2 or more types together. Among these crystalline polymers, polyolefins and polyolefin copolymers are preferable, polyethylene (PE) and polypropylene (PP) are more preferable in terms of general availability and easy access, and their melting points are relatively low and easy to handle. Polyethylene (PE) is particularly preferred.
Examples of the non-crystalline polymer resin include polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene copolymer (ABS), polystyrene (PS), polyacrylonitrile, copolymers thereof, and blends thereof. Is mentioned. These may be used individually by 1 type and may use 2 or more types together.

Moreover, as an organic fiber used for the organic fiber and (E) component which are used in this invention, the fiber length is the range which is the range of 0.5-20 mm, especially the range which is the range of 1-10 mm. Is preferred.
If organic fibers are present in such a length in the vulcanized rubber when forming the foamed rubber layer, the edge effect and the spike effect will work effectively. It is also possible to sufficiently form long bubbles that can function efficiently as drainage grooves. When the organic fiber length is less than 0.5 mm, the above effects cannot be sufficiently exhibited.
Moreover, when the said organic fiber length exceeds 20 mm, it exists in the tendency for organic fibers to get entangled and the dispersibility falls.
Moreover, in the said organic fiber, the range whose diameter of the fiber is 0.01-0.1 mm, especially the range which is 0.015-0.09 mm is preferable. If the diameter of the organic fiber is less than 0.01 mm, cutting is likely to occur, so that the edge effect or spike effect cannot be sufficiently exhibited. Further, when the diameter exceeds 0.1 mm, a problem occurs in workability.

  In the component (E) used in the present invention, the fine particles contained in the organic fiber include inorganic fine particles and organic fine particles. Specifically, examples of the inorganic fine particles include glass fine particles, aluminum hydroxide fine particles, alumina fine particles, and iron fine particles. Examples of the organic fine particles include (meth) acrylic resin fine particles and epoxy resin fine particles. These may be used individually by 1 type and may use 2 or more types together. Among these, inorganic fine particles are preferable from the viewpoint of excellent scratching effect on ice.

The fine particles used in the present invention preferably have a Mohs hardness higher than hardness 2, particularly higher than hardness 5. When the Mohs hardness of the fine particles is not less than the hardness (1-2) of ice, that is, 2 or more, one scratching effect can be exhibited as a tread on the surface portion of the foamed rubber layer. For this reason, the obtained tire has a large coefficient of friction with the icy and snowy road surface, and is excellent in performance on ice (surface braking and driving performance of the tire on the icy and snowy road surface).
Examples of such fine particles having high hardness include gypsum, calcite, fluorite, orthofeldspar, quartz, and gangue. Preferably, silica glass having a Mohs hardness of 5 or more (hardness 6.5), quartz ( Hardness 7.0), fused alumina (hardness 9.0), etc. can be mentioned. Among them, silica glass, alumina (aluminum oxide), etc. can be used easily at low cost.

Further, the fine particles preferably have 80% by mass or more, preferably 90% by mass or more of the frequency number of the particle size distribution in the range of 10 to 50 μm, and the average particle size is in the range of 10 to 30 μm. Is preferred.
When the particle size at the frequency number is less than 10 μm, when the component (F) is produced, some particles tend to aggregate and the dispersibility tends to decrease. Further, a tire using such a fiber cannot exhibit a sufficient scratching effect, edge effect, or spike effect. On the other hand, when the particle size exceeds 50 μm, problems such as fiber breakage occur frequently during the production of the component (F), and the desired component (F) cannot be obtained efficiently.

The fine particles preferably have a frequency number at the peak value of the particle size distribution of 20% by mass or more, more preferably 25% by mass or more, and further preferably 30% by mass or more.
When the frequency number at the peak value of the fine particles is 20% by mass or more, the particle size distribution curve of the fine particles becomes sharp and the particle size becomes uniform. For this reason, good fibers are obtained that are less likely to break during spinning of the component (E), and the performance on ice is stabilized when such fibers are used in tires. Moreover, in the above-mentioned range, the larger the particle size, the better the tire performance on ice.
Here, the frequency number refers to the mass ratio of the existing particles in the division width when the particle size in the particle size distribution (particle size distribution curve) with respect to the total particle mass is divided by a step size of 2 μm. The frequency number in (1) means the frequency number in the section width including the maximum peak value in the step size in the particle size distribution curve.

Further, the fine particles preferably have an aspect ratio of 1.1 or more, and preferably have corners. More preferably, the aspect ratio is 1.2 or more, and further preferably 1.3 or more. here. The presence of corners means that the entire surface is not a spherical surface or a smooth curved surface.
Fine particles having corners can be used from the beginning for the fine particles of the present invention, but even if the fine particles are spherical, they can be used with the corners existing on the surface of the fine particles, and more Corners can be present.

The shape of the fine particles can be confirmed by observing the fine particle group with an electron microscope, and is confirmed to be not spherical. Further, if the aspect ratio representing the ratio of the major axis to the minor axis of the particle is 1.1 or more, the existence of corners formed on the particle surface can be sufficiently angular. For this reason, in a tire or the like using the (E) fine particle-containing organic fiber containing such fine particles, the scratch effect, the edge effect, and the spike effect can be sufficiently enhanced.
The fine particle component is preferably contained in an amount of 5 to 50 parts by mass, particularly 7 to 50 parts by mass with respect to 100 parts by mass of the resin constituting the component (E).

By making the amount of the fine particles within the above range, the scratch effect in the rubber product of the rubber composition, the edge effect and the spike effect are sufficiently generated in the tire tread, and fiber breakage or the like may occur during the production of the component (E). The component (E) with less problem occurrence can be obtained efficiently.
In the present invention, a foaming agent is blended in the vulcanized rubber before forming the foamed rubber layer in order to form bubbles after vulcanization. By using the foaming agent and the fibers, the foamed rubber layer that becomes a vulcanized rubber or a tread has long air bubbles and forms a micro drainage groove, so that a water film removing ability is imparted.

  Examples of the foaming agent include dinitrosopentamethylenetetramine (DPT), azodicarbonamide (ADCA), dinitrosopentastyrenetetramine, a benzenesulfonyl hydrazide derivative, oxybisbenzenesulfonylhydrazide (OBSH), and a heavy gas that generates carbon dioxide. Ammonium carbonate, sodium bicarbonate, ammonium carbonate, nitrososulfonylazo compound generating nitrogen, N, N′-dimethyl-N, N′-dinitrosophthalamide, toluenesulfonyl hydrazide, P-toluenesulfonyl semicarbazide, P, P ′ -Oxy-bis (benzenesulfonyl semicarbazide) etc. are mentioned.

  Among these foaming agents, in consideration of production processability, dinitrosopentamethylenetetramine (DPT) and azodicarbonamide (ADCA) are preferable, and azodicarbonamide (ADCA) is particularly preferable. These may be used individually by 1 type and may use 2 or more types together. By the action of the foaming agent, the obtained vulcanized rubber becomes a foamed rubber having a high foaming rate.

In the present invention, from the viewpoint of efficient foaming, it is preferable to use a foaming aid as the other component and to use in combination with the foaming agent. Examples of the foaming aid include urea, zinc stearate, zinc benzenesulfinate, zinc white, and the like, which are usually used in the production of foamed products. Among these, urea, zinc stearate, zinc benzenesulfinate and the like are preferable. These may be used individually by 1 type and may use 2 or more types together.
The content of the foaming agent may be appropriately determined according to the purpose, but is generally preferably about 1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The foaming agent may be blended in the rubber matrix or in each organic fiber.

  The other components used in the present invention can be used as long as they do not impair the effects of the present invention. For example, vulcanizing agents such as sulfur, vulcanization accelerators such as dibenzothiazyl disulfide, and vulcanization accelerating aids. , N-cyclohexyl-2-benzothiazyl-sulfenamide, N-oxydiethylene-benzothiazyl-sulfenamide and other antisulfurizing agents, ozone degradation inhibitors, colorants, antistatic agents, dispersants, lubricants, antioxidants, In addition to softeners, inorganic fillers such as carbon black and silica, etc., various compounding agents usually used in the rubber industry can be appropriately selected and used according to the purpose. These may be used individually by 1 type and may use 2 or more types together.

Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic sectional view of a tire according to the present invention. 2A and 2B are schematic cross-sectional views along the circumferential direction and the width direction of the tread portion of the tire according to the present invention. FIG. 3 is an explanatory view illustrating the principle of orienting the fine particle-containing organic fibers in a certain direction.

The tire according to the present invention is a tire in which a foam rubber layer is provided on a surface substantially in contact with the road surface, specifically, as shown in FIGS. 1 to 3, closed cells are provided on at least the surface substantially in contact with the road surface. It consists of a pneumatic tire provided with a foamed rubber layer.
For example, as shown in FIG. 1, a pair of bead portions 1, a carcass 2 connected to the pair of bead portions 1 in a toroidal shape, a belt 3 for tightening a crown portion of the carcass 2, and a cap portion 6 and a tread 5 composed of two layers of a base portion 7 have a radial structure. Since the internal structure other than the tread 5 is the same as that of a general radial tire, description thereof is omitted.

  The surface portion of the tread 5 is a foamed rubber layer formed by vulcanizing the rubber composition according to the present invention. Although there is no restriction | limiting in particular about the manufacturing method of the tire 4, For example, it vulcanizes-molds with a predetermined mold under a predetermined temperature and a predetermined pressure. As a result, the tire 4 having the cap tread 6 formed of the foamed rubber layer of the present invention obtained by vulcanizing an unvulcanized tread is obtained.

In order to form the foamed rubber layer of the tire according to the present invention, the rubber composition detailed above is kneaded, heated, extruded, etc. under the following conditions and methods.
The kneading is not particularly limited with respect to various conditions of the kneading apparatus such as the input volume to the kneading apparatus, the rotor rotation speed, the kneading temperature, and the kneading time, and can be appropriately selected according to the purpose. As the kneading apparatus, a commercially available product can be suitably used.
There is no restriction | limiting in particular about various conditions, such as hot-heating or extrusion time, hot-heating or an extrusion apparatus, and heating or extrusion can be suitably selected according to the objective. A commercially available product can be suitably used as the heating or extrusion device. The heating or extrusion temperature is appropriately selected within a range that does not cause foaming when a foaming agent is present. The extrusion temperature is desirably about 90 to 110 ° C.

  In the present invention, the above-mentioned organic fibers are preferably oriented in the extrusion direction by extrusion or the like, and in order to effectively perform such orientation, the fluidity of the rubber composition is controlled within a limited temperature range. Specifically, in the rubber composition, a processability improver such as a plasticizer such as an aroma oil, naphthene oil, paraffin oil, ester oil, or a liquid polymer such as liquid polyisoprene rubber or liquid polybutadiene rubber. Appropriately added to change the viscosity of the rubber composition and increase its fluidity.

In the case where organic fibers are included in the present invention, in order to produce a foam rubber layer of a tread, (B) fine particle-containing organic fibers and (D) fine particle-free organic fibers are oriented in a direction parallel to the ground contact surface in the tread, that is, The tire is preferably oriented in the circumferential direction of the tire. The drainage in the running direction of the tire can be improved, and the performance on ice can be effectively improved.
As a method for aligning and orienting the organic fibers in the foamed rubber layer, for example, as shown in FIG. 3, the rubber composition 16 containing the fine particle-containing organic fibers 15 is reduced in the cross-sectional area toward the outlet. What is necessary is just to orientate the fine particle containing organic fiber 15 grade | etc., In a fixed direction by extruding from the nozzle | cap | die 17 of the extruder to perform. In this case, the fine particle-containing organic fibers 15 and the like in the rubber composition 16 before being extruded are gradually aligned in the longitudinal direction along the extrusion direction (arrow P direction) in the process of being extruded to the die 17. Thus, when extruded from the die 17, the longitudinal direction thereof can be oriented almost completely in the extrusion direction (arrow A direction). In this case, the degree of orientation of the fine particle-containing organic fibers 15 and the like in the rubber composition 16 is changed depending on the degree of reduction in the cross-sectional area of the channel, the extrusion speed, the viscosity of the rubber composition 16 before vulcanization, and the like.

  In the present invention, the vulcanization conditions and the like are not particularly limited and can be appropriately selected according to the type of rubber component. However, in the case of producing a foamed rubber layer as a tread as in the present invention, a mold is used. Vulcanization is good. As described above, the vulcanization temperature is preferably selected so that the maximum vulcanization temperature of the rubber composition during vulcanization is equal to or higher than the melting point of the resin constituting the organic fiber. If the maximum vulcanization temperature is lower than the melting point of the resin, the fibers do not melt as described above, and the gas generated by foaming cannot be taken into the resin. Long bubbles cannot be efficiently formed in the foamed rubber layer. There is no restriction | limiting in particular in a vulcanizer, A commercial item can be used conveniently.

  In the tread (foamed rubber layer) of the tire according to the present invention, the concave portions of the elongated bubbles generated on the tread surface are directional. For this reason, it functions as a drainage channel for efficient drainage. Since the recess has the protective layer, particularly a protective layer in which fine particles are present, the recess has excellent resistance to peeling, water channel shape retention, water channel edge wear, water channel retention during load input, and the like. . Furthermore, in the tire of the present invention, since the elongated bubbles are present in the entire foamed layer, various functions by the recesses are exhibited from the initial use to the last stage, and the above-mentioned performance on ice is excellent.

  In the present invention, the average diameter (μm) of the elongated bubbles formed in the foamed rubber layer is preferably about 10 to 500 μm. If the average diameter is less than 10 μm, the water drainage performance of the micro drainage grooves formed on the rubber surface may be reduced, and if the average diameter exceeds 500 μm, the cut resistance of the rubber and the block chipping are deteriorated. In addition, the wear resistance on the dry road surface may deteriorate.

The tire according to the present invention can be suitably applied not only to so-called passenger cars but also to various vehicles such as trucks and buses. The tire tread can be suitably used for a structure that needs to suppress slip on an icy and snowy road surface, and the tire tread is, for example, a tread for replacement of a retread tire as long as it is necessary to suppress slip on the ice. Can be used for real tires, etc. When the tire is a pneumatic tire, an inert gas such as nitrogen can be used in addition to air as the gas filled inside.
In the above embodiment, a tread having a two-layer structure has been described as an example. However, the tread structure is not particularly limited and may be a single-layer structure. Furthermore, it may be a multilayer structure divided in the tire radial direction, a structure divided in the tire circumferential direction or tread width direction, and at least a part of the surface layer of the tread is preferably made of the rubber composition of the present invention.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. Various measurement methods were performed based on the following methods.

Examples 1-6 and Comparative Examples 1-6
Based on the content of each compound shown in Table 1, rubber compositions of Examples and Comparative Examples were produced by a conventional method.
The vulcanization temperature at the time of vulcanization of each rubber composition was measured while embedding a thermocouple in the rubber composition. By the time the maximum vulcanization temperature was reached, the melting point of each organic fiber resin was exceeded, and during the vulcanization of the rubber composition, the resin viscosity was lower than the rubber matrix viscosity. The viscosity (melt viscosity) of each organic fiber resin at the maximum vulcanization temperature was measured using a cone rheometer (end when the torque of the rubber changed to Max, and the torque was changed to the rubber viscosity. The change in pressure was measured. On the other hand, the viscosity (flow viscosity) at the maximum vulcanization temperature of the rubber composition is a corn rheometer model 1-C manufactured by Monsanto, and given a constant amplitude input of 100 cycles / min while changing the temperature. The torque was measured over time, and the minimum torque value at that time was taken as the viscosity (dome pressure 0.59 MPa, holding pressure 0.78 MPa, closing pressure 0.78 MPa, swing angle ± 5 °), and 11 .
Each of the obtained rubber compositions was used for a tread (foamed rubber layer) to produce a test passenger car radial tire and tire size 185 / 70R15 by a conventional method.

[Tire performance evaluation]
<Performance on ice>
Four test tires (tire size 185 / 70R15) were mounted on a domestic 1600 CC class passenger car, and the braking performance on ice at an ice temperature of −1 ° C. was confirmed. The tire of Comparative Example 1 was used as a control tire, and performance on ice = (braking distance of control tire / braking distance of other examples) × 100. Larger values indicate better performance on ice. The evaluation results are shown in Table 1.
<WET performance>
Measure the braking distance from the initial speed of 40, 60, 80 km / hr on wet asphalt road surface, the tire of Comparative Example 1 is the control tire, the control tire is 100 at each speed, and other values are comparative examples An index was calculated by 1 braking distance ÷ braking distance of test tire × 100, and the index was expressed as an average of the three levels. Therefore, the larger the numerical value, the better. The evaluation results are shown in Table 1.

<Abrasion resistance>
After traveling 10,000 km on a paved road surface with an actual vehicle, the remaining groove was measured, and the travel distance required for the tread to wear 1 mm was relatively compared, and Comparative Example 1 was displayed as an index as 100 (corresponding to 8000 km / mm). The larger the index, the better the wear resistance. The evaluation results are shown in Table 1.
<Rolling resistance test>
The rolling resistance is a coasting method when rotating at a speed of 80 km / h using a rotating drum having a steel smooth surface with an outer diameter of 1707.6 mm and a width of 350 mm under a load of 4500 N (460 kg). Measured and evaluated. The measured values were indexed with the value of Comparative Example 1 as 100. The larger this value, the better the rolling resistance (low fuel consumption). The evaluation results are shown in Table 1.

注」
＊１．シス−１，４−ポリブタジエンゴム：（商品名；ＵＢＥＰＯＬ １５０Ｌ：宇部興産社製）
＊２．カーボンブラック：［Ｎ１３４（Ｎ₂ＳＡ：１４６ｍ²／ｇ）］：旭カーボン社製）
＊３．シリカ：（Ｎｉｐｓｉｌ ＡＱ：東・ソーシリカ株式会社製）
＊４．シランカップリング剤：（Ｓｉ６９：デグサ社製）
＊５．「ＮＸＴ」シランカップリング剤：Ｇｅｎｅｒａｌ Ｅｌｅｃｔｒｉｃ社製、化学名：３−オクタノイルチオプロピルトリエトキシシラン
＊６．無機化合物粉体：水酸化アルミニウム「ハイジライトＨ−３１」昭和電工社製、
平均粒径２０μｍ
＊７．老化防止剤：（Ｎ−イソプロピル−Ｎ’−フェニル−ｐ−フェニレンジアミン）
＊８．加硫促進剤：（ＤＰＧ：ジフェニルグァニジン）
＊９．加硫促進剤：（ＭＢＴＳ：ジベンゾチアジルジスルフィド）
＊１０．加硫促進剤：（ＣＢＳ：Ｎ−シクロヘキシル−２−ベンゾチアゾールスルフェンアミド）
＊１１．発泡剤：（ＤＮＰＴ：ジニトロソペンタメチレンテトラミン）
＊１２．微粒子含有有機繊維：繊維を構成する樹脂（ポリエチレン融点１３２℃、微粒子含有量１５質量部、微粒子平均粒径２０μｍ、繊維平均直径３２μｍ、繊維平均長さ２ｍｍ

note"
* 1. Cis-1,4-polybutadiene rubber: (trade name; UBEPOL 150L: manufactured by Ube Industries)
* 2. Carbon black: [N134 (N ₂ SA: 146 m ² / g)]: manufactured by Asahi Carbon Co.)
* 3. Silica: (Nipsil AQ: manufactured by East Sosilica Corporation)
* 4. Silane coupling agent: (Si69: Degussa)
* 5. “NXT” silane coupling agent: manufactured by General Electric, chemical name: 3-octanoylthiopropyltriethoxysilane * 6. Inorganic compound powder: aluminum hydroxide “Hijilite H-31” manufactured by Showa Denko KK
Average particle size 20μm
* 7. Anti-aging agent: (N-isopropyl-N′-phenyl-p-phenylenediamine)
* 8. Vulcanization accelerator: (DPG: diphenylguanidine)
* 9. Vulcanization accelerator: (MBTS: dibenzothiazyl disulfide)
* 10. Vulcanization accelerator: (CBS: N-cyclohexyl-2-benzothiazolesulfenamide)
* 11. Foaming agent: (DNPT: dinitrosopentamethylenetetramine)
* 12. Fine particle-containing organic fiber: resin constituting the fiber (polyethylene melting point 132 ° C., fine particle content 15 parts by mass, fine particle average particle diameter 20 μm, fiber average diameter 32 μm, fiber average length 2 mm

The following can be seen from Table 1. The total amount (silica + carbon black) of the reinforcing fillers of Examples 2 to 6 using “NXT” silane coupling agent as the silane coupling agent was 70, 80, and 100 parts by mass, and the reinforcements of Comparative Examples 1 to 6 were used. The total amount of the filler is 10 to 40 parts by mass compared to 60 parts by mass. Conventionally, if the amount of the reinforcing filler is increased, the rolling resistance (low heat build-up) tends to deteriorate, but the difference between the two is unacceptable.
Similarly, the difference between the comparative example and the example in terms of WET performance and on-ice performance is not recognized even though the reinforcing filler is increased. With regard to wear resistance, the effect of increasing the reinforcing filler is recognized and improved.
Therefore, it can be seen that Examples 2 to 6 in which the amount of the reinforcing filler is increased have the same excellent effects on ice, WET performance, and rolling resistance as conventional ones, and the wear resistance is improved as compared with the conventional ones. .

  The present invention provides a rubber composition capable of providing a pneumatic tire having excellent workability during rubber processing, excellent on-ice performance, WET performance, and low fuel consumption, and good wear resistance, and the rubber composition. The pneumatic tire which has the said performance used for a tread can be provided. In particular, it can be suitably used for passenger car tires.

FIG. 1 is a schematic sectional view of a tire according to the present invention. 2A and 2B are schematic cross-sectional views along the circumferential direction and the width direction of the tread portion of the tire according to the present invention. FIG. 3 is an explanatory view illustrating the principle of orienting the fine particle-containing organic fibers in a certain direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pair of bead part 2 Carcass 3 Belt 4 Tire 5 Tread 6 Cap part 6A Vulcanized rubber 7 Base part 12 Long bubble 13 Recess 14 Protective layer 15 Fine particle containing organic fiber 16 Rubber composition 17 Base 18 Spherical bubble 19 Spherical bubble Recess 20 of fine particle P direction of extrusion

Claims (11)

(B) the following general formula (I) with closed cells and (A) at least one rubber component selected from natural rubber and diene-based synthetic rubber, and 100 parts by mass thereof:
M ・ xSiO ₂・ yH ₂ O …… (I)
[M in the formula is at least one metal oxide or metal hydroxide selected from Al, Mg, Ti, and Ca, and x and y are both integers of 0 to 10. ]
3 to 50 parts by weight of an inorganic compound powder having an average particle size of 50 μm or less, (C) 10 to 150 parts by weight of silica as a reinforcing filler, and (D) the following general formula (II)

[In the formula, R ¹ is ^{R 6 O-, R 6 C (} = O) O-, R 6 R 7 C = NO-, R 6 R 7 CNO-, R 6 R 7 N- or - (OSiR ⁶ R ⁷ ) _m (OSiR ⁵ R ⁶ R ⁷ ) (wherein R ⁶ and R ⁷ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms) R ² is R ¹ , A hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R ³ is R ¹ , R ² or — [O (R ⁸ O) _a H] group (where R ⁸ is alkylene having 1 to 18 carbon atoms) Group, a is an integer of 1 to 4), R ⁴ represents a divalent hydrocarbon group having 1 to 18 carbon atoms, R ⁵ represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, x, y and z are numbers satisfying the relationship of x + y + z = 3, 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ]
The rubber composition characterized by including the silane coupling agent represented by these in the ratio of 1-30 mass% with respect to the silica of the said (C) component.   The rubber composition according to claim 1, wherein the component (B) has an average particle size of 10 to 50 μm. The component (B) is represented by the following general formula (III)
Al ₂ O ₃ · mSiO ₂ · nH ₂ O ……… (III)
[M in the formula is an integer of 1 to 4, and n is an integer of 0 to 4. The rubber composition according to claim 1 or 2, which is an inorganic compound powder represented by the formula:   The rubber composition according to claim 1, wherein the component (B) is a powder made of aluminum hydroxide.   The rubber composition according to any one of claims 1 to 4, wherein a ratio of the component (C) in the total reinforcing filler is in a range of 30 to 100% by mass.   The rubber composition according to claim 5, wherein the reinforcing filler other than the component (C) is carbon black.   Furthermore, the rubber composition in any one of Claims 1-6 containing 0.02-20 mass parts of (E) fine particle containing organic fiber with respect to 100 mass parts of (A) component.   The rubber composition according to claim 7, wherein the component (E) contains 5 to 90 parts by mass of fine particles with respect to 100 parts by mass of the material constituting the organic fiber.   The rubber composition according to claim 7 or 8, wherein the material constituting the organic fiber of the component (E) is a crystalline polymer made of polyethylene and / or polypropylene and has a melting point of 190 ° C or lower.   The rubber composition according to any one of claims 7 to 9, wherein a material constituting the fine particles of the component (E) is selected from inorganic fine particles and organic fine particles.   A pneumatic tire using the rubber composition according to claim 1 on a surface substantially in contact with a road surface of a tread portion.

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