JP2005060478A - Rubber composition, its vulcanizate, and tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rubber composition which, when used for a tire tread, or the like, fully satisfies on-ice performance, dry driving stability, and abrasion resistance; a vulcanizate thereof; and a tire using the same. <P>SOLUTION: The rubber composition is prepared by dispersing, in a rubber matrix, a non-linear fine-particle-containing resin body containing fine particles with a Mohs hardness of 2 or higher. The vulcanizate is prepared from the rubber composition, wherein the viscosity of the resin body and that of the rubber matrix of which composition are appropriately selected in accordance with the highest vulcanization temperature. The vulcanizate is used for the tire. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rubber composition, a vulcanized rubber thereof, and a tire using the rubber composition. More specifically, the invention improves the on-ice performance of the tire such as braking, driving, cornering performance on an icy road surface, and the like. The present invention relates to a rubber composition capable of improving wear resistance, a vulcanized rubber thereof, and a tire using the rubber composition.

  In general, in order to improve the braking / driving performance (on-ice performance) of a tire on an icy and snowy road surface, research on a tire tread has been actively conducted. On ice and snow road surfaces, a water film is likely to be generated due to frictional heat of the tire and the like, and this water film causes a decrease in the coefficient of friction between the tire and the ice and snow road surface. For this reason, various proposals have been made to improve the water film removal ability and edge effect of the tire tread.

  For example, in a rubber composition used for a tread, an organic resin having a viscosity lower than that of the rubber component during the vulcanization of the rubber composition composed of the rubber component and the foaming agent until the temperature reaches the maximum temperature of the rubber component. It has been proposed to improve the above performance and effects by blending fibers (for example, see Patent Document 1).

Fine particles formed by containing fine particles having a predetermined diameter such as glass fine particles, aluminum hydroxide fine particles, alumina fine particles, iron fine particles, (meth) acrylic resin fine particles, and epoxy resin fine particles in an organic fiber having a predetermined diameter. It has been proposed to add the contained organic fiber to the rubber component of the tire (see, for example, Patent Document 2). And in the rubber composition of a tire containing fine particle-containing organic fibers in a rubber matrix, the viscosity is lower than the viscosity in the rubber matrix until the temperature of the rubber composition reaches the maximum vulcanization temperature at the time of vulcanization. Proposals have been made to further improve the water film removing ability and the edge effect in tires by using the resulting resin for fine particle-containing organic fibers.
Japanese Patent Laid-Open No. 11-48264 JP 2001-233993 A

  However, when a conventional linear resin body made of fine particle-containing organic fibers containing fine particles is dispersed in a rubber component and vulcanized, cylindrical foaming is observed in the rubber matrix (rubber structure). In the case of a long cavity, the block rigidity is deteriorated. For this reason, when it is used for a tread of a tire or the like, although the performance on ice is improved, the dry steering stability and the wear resistance of the tire tend to be deteriorated. For this reason, when used for a tire tread or the like, a rubber composition excellent in performance on ice, stability in dry handling, and wear resistance is desired.

  Accordingly, in view of such circumstances, the present invention provides a rubber composition, a vulcanized rubber, and a rubber composition that can satisfy all of on-ice performance, dry handling stability, and wear resistance when used in a tire tread or the like. It intends to provide a tire using the tire.

That is, the present invention achieves the above object by adopting the following characteristic features (1) to (10).
(1) A rubber composition obtained by dispersing non-linear fine particle-containing resin bodies containing fine particles having a Mohs hardness of 2 or more in a rubber matrix.
(2) The rubber composition according to (1), wherein the fine particle-containing resin body is spherical.
(3) The rubber composition as described in (2) above, wherein the particle-containing resin body has a particle size in the range of 10 to 500 μm.
(4) The rubber composition according to (3), wherein the fine particles have an average particle size in the range of 0.1 to 100 μm, and the fine particles have a smaller diameter than the resin body.
(5) The rubber composition according to any one of (1) to (4), wherein the fine particle-containing resin body contains the fine particles in a range of 5 to 50 parts by mass with respect to 100 parts by mass of the resin.
(6) The rubber component constituting the rubber matrix is composed of at least one rubber component selected from natural rubber and gen synthetic rubber, and the resin body is added to 0.1 part by mass of the rubber component. The rubber composition according to any one of (1) to (5), which is contained in a range of ˜30 parts by mass.
(7) The resin in the fine particle resin body has a viscosity characteristic lower than the rubber viscosity in the rubber matrix before reaching the maximum vulcanization temperature at the time of vulcanization. The rubber composition according to any one of (6).
(8) The rubber composition according to any one of (1) to (7), wherein a foaming agent is blended.
(9) A vulcanized rubber obtained by vulcanizing the rubber composition according to the above (8) and having a foaming ratio in the range of 3 to 40%.
(10) A pair of bead portions, a carcass continuous in a toroidal shape with the bead portions, a belt and a tread for tightening a crown portion of the carcass, and the tread described in (9) above A tire comprising vulcanized rubber.

  According to the above means, a non-linear resin body containing fine particles having a hardness of 2 or more is added to the rubber component. As a result of containing a non-linear resin body in the rubber component, the formation of a cylindrical long cavity during vulcanization is suppressed, and when used for a tire tread, etc. All wear resistance can be satisfied.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is an example of an embodiment for carrying out the invention, and is a schematic sectional view of a tire. In the figure, the same reference numerals as those in FIG. 1 denote the same parts, and the basic configuration is the same as the conventional one shown in the figure. FIG. 2 is a schematic view of a resin body of the rubber composition according to the present invention.

  For example, as shown in FIG. 1, a tire according to the present invention is configured by tightening a pair of bead portions 1, a carcass 2 connected in a toroidal shape to the pair of bead portions 1, and a crown portion of the carcass 2. The belt 3 and the tread 5 having two layers of the cap portion 6 and the base portion 7 are sequentially arranged. 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 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.

  First, embodiments of the rubber composition according to the present invention used for the tread portion and the vulcanized rubber thereof will be described in detail. The rubber composition according to the present invention is obtained by dispersing a non-linear fine particle-containing resin body containing fine particles having a Mohs hardness of 2 or more in a rubber matrix.

  In the present invention, the resin body dispersed in the rubber matrix composed of the rubber component is non-linear. The non-linear resin body does not include a long shape such as an organic fiber, and has an aspect ratio of 1.1 or less. The non-linear resin body is particularly preferably spherical. In this case, as shown in FIG. 2, the ratio Rl / Rs of the long-axis cross-sectional diameter Rl which is the longest in the spherical resin body 10 to the short-axis cross-sectional diameter Rs in the axial direction perpendicular thereto is 1.1. The following is preferable. Thus, if the non-linear resin body approximates a spherical shape, the rubber composition containing the non-linear resin body is reduced in the number of cylindrical cavities after vulcanization, so that the wear resistance and block rigidity are sufficiently improved. Moreover, in such a resin body, it is preferable that the major-axis cross-sectional diameter Rl is in the range of 10 to 500 μm, particularly in the range of 20 to 200 μm. When the long-axis cross-sectional diameter Rl is less than 10 μm, the fine particles cannot be sufficiently contained and retained, and a tire using such a rubber composition does not exhibit a sufficient edge effect on an icy road. Further, when the long-axis cross-sectional diameter Rl exceeds 500 μm, the cavity after the resin body has fallen out becomes too large, so that the wear resistance and block rigidity of the tire rubber are lowered.

  In the present invention, the fine particles contained in the resin body have a Mohs hardness higher than 2 and particularly preferably higher than 5 hardness. If the Mohs hardness of the fine particles is ice hardness, that is, 2 or more, a further scratching effect is exhibited on the tread surface of the tire. 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 / driving performance of the tire on the icy and snowy road surface). The fine particles preferably have an average particle diameter in the range of 0.1 to 100 μm, particularly in the range of 10 to 50 μm. Furthermore, it is desirable that the fine particles have a smaller diameter than the resin body. If the average particle size of the fine particles is less than 0.1, the effect of inclusion in the resin body is not observed, and the scratching effect is not exhibited on the tread surface of the tire. When the average particle size of the fine particles exceeds 100 μm, and when the average particle size is larger than that of the resin body, the resin body cannot sufficiently contain and hold the fine particles.

  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.

  Similar to the non-linear resin body described above, the shape of the fine particles can be confirmed by observing the fine particle group with an electron microscope. In this case, it is confirmed that the particles are 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 a fine particle-containing resin body containing such fine particles, the scratch effect, the edge effect, and the spike effect can be sufficiently enhanced.

  Such fine particles are preferably contained in a range of 5 to 50 parts by mass, particularly 7 to 50 parts by mass with respect to 100 parts by mass of the resin of the resin body. When the amount of the fine particles is less than 5 parts by mass, the scratch effect of the rubber composition in the rubber product and the edge effect and the spike effect may not be sufficiently generated in the tire tread. On the other hand, when the amount of the fine particles exceeds 50 parts by mass, it is difficult to keep the fine particles contained in the resin body.

  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.

  In the present invention, the rubber component constituting the rubber matrix in the rubber composition is preferably at least one rubber component selected from natural rubber and gen-based synthetic rubber. It is preferable that the natural rubber is contained in the range of 20 to 70 parts by mass and the polybutadiene rubber is contained in the range of 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component.

  Moreover, in a rubber composition, it is preferable that the said fine particle containing resin body is the range of 0.1-30 mass parts with respect to 100 mass parts of rubber components. If the resin body is less than 0.1 parts by mass, the scratching effect is not sufficiently exhibited, and the edge effect or spike effect on the tire tread surface and the corresponding on-ice performance are not sufficiently improved. On the other hand, if the blending amount exceeds 30 parts by mass, the wear resistance and block rigidity are not sufficient.

  In the rubber composition of the present invention, in the relationship between the rubber matrix of the rubber component and the resin body, the resin of the resin body has a viscosity characteristic lower than the rubber viscosity before reaching the maximum vulcanization temperature during vulcanization. It does not have to be lower than the rubber viscosity during vulcanization. Those having a viscosity characteristic lower than the rubber viscosity at the time of vulcanization are combined with the addition of a foaming agent to be described later to the rubber composition, and as described above, the resin body forms spherical bubbles by embedding the foaming agent gas. .

  The relationship between the rubber component and the resin body is that the resin body has viscosity characteristics lower than the rubber viscosity at the time of vulcanization, and if a foaming agent is included, the resin body melts quickly during vulcanization, and the viscosity is the rubber matrix. The time when it becomes lower than the viscosity of is earlier. The gas generated from the foaming agent collects inside the resin having a lower viscosity than the rubber matrix. As a result, in the vulcanized rubber, bubbles having a resin layer containing fine particles between the rubber matrix, that is, capsule-shaped spherical cells covered with the resin are efficiently formed without being crushed. The Such spherical bubbles are not necessarily present, but are preferably present in an amount of 30% by volume or more, particularly 60% by volume or more, based on the total bubbles V in the vulcanized rubber, as will be described later. In such a foamed rubber layer that becomes a tire tread, the capsule-like bubbles appear on the surface of the tread, and the groove caused by friction functions as the above-mentioned micro drainage groove. Also fully demonstrate.

  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 means melt viscosity, and is measured using, for example, a cone rheometer, a capillary rheometer, or the like.

  The resin of the resin body is lower than the maximum vulcanization temperature at the time of vulcanization, more preferably 10 ° C. or more, and particularly preferably 20 ° C. or more. 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 of the resin 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.

  In the rubber composition of the present invention, the resin of the resin body is preferably a crystalline resin, a highly crystalline resin, or the like because a resin whose viscosity rapidly decreases at the melting point is preferable. Examples of such crystalline resins include polyethylene (PE), polypropylene (PP), polybutylene, polybutylene succinate, polyethylene succinate, syndiotactic-1,2-polybutadiene (SPB), and polyvinyl alcohol (PVA). Also, single composition polymers such as polyvinyl chloride (PVC), those having a melting point controlled to an appropriate range by copolymerization, blending, etc. can be used, and those obtained by adding additives 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.

  It is preferable to add a foaming agent to the rubber composition of the present invention in order to form bubbles after the addition. In the vulcanized rubber of the present invention obtained by blending a foaming agent, the foaming ratio is preferably in the range of 3 to 40%, particularly preferably in the range of 14 to 40%. A foaming agent is mix | blended in a rubber matrix, and may be mix | blended in a resin body as needed. 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.

  By using the foaming agent and the resin body, the vulcanized rubber serving as the tread surface has non-linear bubbles and has a water film removing ability.

Here, the foaming rate V in the vulcanized rubber is represented by V = (ρ0 / ρ1-1) × 100 (%), and ρ1 represents the density (g / cm ³ ) of the vulcanized rubber (foamed rubber). , Ρ0 represents the density (g / cm ³ ) of the solid phase part (non-foamed part) in the vulcanized rubber (foamed rubber). The density of the solid phase part is calculated from the weight in ethanol and the weight in air. When the foaming ratio V is less than 3%, a sufficient water removal function cannot be obtained due to insufficient volume of the concave portion due to bubbles with respect to the generated water film, and the performance on ice in the vulcanized rubber cannot be sufficiently improved. there is a possibility. On the other hand, when the foaming ratio V exceeds 40%, although the performance on ice can be improved, the amount of bubbles in the vulcanized rubber is excessively increased, so that the rubber breaking limit is greatly reduced, and the durability is improved. It is not preferable in terms.

  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.

When the rubber composition is used for a tire tread or the like, the rubber composition contains carbon black in an amount of 5 to 55 parts by mass with respect to 100 parts by mass of the rubber component, and silica is 100 parts by mass of the rubber component. It is preferably contained in the range of 5 to 55 parts by mass with respect to parts. If the amount of carbon black contained exceeds 55 parts by mass, the tire performance is lowered and the performance on ice is affected. Further, when the carbon black is not contained at all or is less than 5 mass, the performance on ice is adversely affected. As long as carbon black enhances the mechanical performance of the rubber layer and improves processability and the like, a known range in which I ₂ adsorption amount, CTAB specific surface area, N ₂ adsorption amount, DBP adsorption amount, etc. are appropriately selected Carbon black can be used. As the type of carbon black, for example, known ones such as SAF, ISAF-LS, HAF, HAF-HS can be appropriately selected and used.

  Silica does not represent only silicon dioxide in a narrow sense, but means a silicate-based filler. Specifically, in addition to anhydrous silicic acid, silicic acid such as hydrous silicic acid, calcium silicate, aluminum silicate, etc. Contains salt. Silica is contained in the range of 5 to 55 parts by mass, preferably in the range of 30 to 50 parts by mass with respect to 100 parts by mass of the rubber component. When the amount of silica contained exceeds 55 parts by mass, the tire performance is lowered and the performance on ice is also adversely affected. Also, when silica is not contained at all or less than 5 mass, the performance on ice is adversely affected.

  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 promoting aids. , N-cyclohexyl-2-benzothiazyl-sulfenamide, N-oxydiethylene-benzothiazyl-sulfenamide and other antisulfurizing agents, antiozonants, 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, may use 2 or more types together, and may use a commercial item.

  In the present invention, it is indispensable to add a non-linear fine particle-containing resin body to the rubber composition, but if necessary, a linear resin body such as fine particle-containing organic fiber or non-fine particle-containing organic fiber may be used in combination. May be.

  In order to form the tire according to the present invention, the rubber composition described in detail above is kneaded, heated, extruded, etc. under the following conditions and techniques.

  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 is preferably 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 is preferably 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 fluidity of the rubber composition is controlled within a limited temperature range. Specifically, the rubber composition contains plastics such as aromatic oil, naphthenic oil, paraffinic oil, and ester oil. A processability improving agent such as a liquid polymer such as an agent, a liquid polyisoprene rubber, or a liquid polybutadiene rubber is appropriately added to change the viscosity of the rubber composition and enhance its fluidity.

  In the present invention, vulcanization conditions and methods are not particularly limited, and can be appropriately selected according to the type of rubber component. However, when a foamed rubber layer as a tread is produced as in the present invention. The mold vulcanization is good. As described above, when the resin body has a viscosity characteristic that is lower than the rubber viscosity at the time of vulcanization, the maximum vulcanization temperature of the rubber composition during vulcanization constitutes the resin body. It is preferably selected so as to be equal to or higher than the melting point of the resin. If the maximum vulcanization temperature is lower than the melting point of the resin, the resin does not melt as described above, and the gas generated by foaming cannot be taken into the resin. Capsule-like 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 tire tread of the present invention, the bubble recesses formed on the tread surface function as a drainage channel for efficient drainage. Since the concave portion has the above resin layer, particularly a resin layer in which fine particles are present, the concave portion is excellent in peeling resistance, water channel shape retaining property, water channel edge portion abrasion property, water channel retaining property at the time of load input, and the like. .

  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 of the present invention will be described below, but the present invention is not limited to these examples.
(Examples 1-8 and Comparative Examples 1-3)
In order to form a foamed rubber layer from the rubber composition of each Example and Comparative Example, natural rubber, cis-1,4-polybutadiene rubber (trade name; UBEPOL 150L: manufactured by Ube Industries), carbon black (N134 (N ₂ SA: 142 m ² / g): manufactured by Asahi Carbon Co., Ltd.), silica (Nipsil AQ: manufactured by Nippon Silica Co., Ltd.), silane coupling agent (Si69: manufactured by Degussa), aroma oil, stearic acid, anti-aging agent (N -Isopropyl-N'-phenyl-p-phenylenediamine), zinc oxide, vulcanization accelerator (MBTS: dibenzothiazyl disulfide), vulcanization accelerator (CBS: N-cyclohexyl-2-benzothiazolesulfenamide), Sulfur, foaming agent (DNPT: dinitrobentamethylenetetramine), urea, fine particle-containing organic fiber, fine particle-containing resin body, It was formulated with selected fine resin body as appropriate. The blending amounts are shown in Tables 1 and 2 below.

  Moreover, the vulcanization temperature at the time of vulcanization of each rubber composition in the composition shown in Table 1 and Table 2 was measured while a thermocouple was embedded in the rubber composition. As a result, in Examples 1 to 5 and Comparative Examples 1 and 2, the resin viscosity exceeded the melting point of the resin body before reaching the maximum vulcanization temperature, and during the vulcanization of the rubber composition, the resin viscosity Was lower than the rubber matrix viscosity.

  The viscosity (melt viscosity) of the resin body at a maximum vulcanization temperature of 190 ° C. is measured using a cone rheometer (end when the torque of the rubber changes to Max, the torque is the rubber viscosity, the torque change and the foam pressure) Was 6). 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 . However, in Tables 2 of Examples 6 to 8 and Comparative Example 3, the resin body does not foam below the rubber matrix viscosity even when reaching the maximum vulcanization temperature (190 ° C.).

  A tire tread (foamed rubber layer) was formed from each Example and Comparative Example, and tires for each test were manufactured according to normal tire manufacturing conditions.

<Performance on ice>
Mount the tire on a domestic 1600cc class passenger car, drive the passenger car on a general asphalt road for 200km, then drive on a flat surface on ice, step on the brake at a speed of 20km / hr until the tire locks and stop The distance of was measured. The results are shown as an index, with the reciprocal of the distance being 100 for the tires of Comparative Example 1 and Comparative Example 3, respectively. In addition, the larger the value, the better the performance on ice.

<Steering stability>
The test tire is mounted on a 300cc-class sports-type passenger car, and after a preliminary run for 3 minutes at a speed of 80 km / hr, an actual vehicle feeling test is performed at a speed of 60 to 200 km / hr, and straight running is stable. 1 to 10 points were assigned to the performance, turning stability, rigidity, and handling, and each item was averaged to evaluate the handling stability. The steering stability was evaluated by two specialized drivers, and the average of the scores of the two drivers was obtained, and the scores of the tires of Comparative Examples 1 and 3 were displayed as 100. The larger the index value, the higher the steering stability.

<Abrasion resistance performance>
Two test tires were attached to the drive shaft of a passenger car having a displacement of 1500 cc, and were run on the concrete road surface of the test course at a predetermined speed. The amount of change in the groove depth was measured, and the tires according to Comparative Examples 1 and 3 were indicated as 100 and indicated as an index. The larger the value, the better the wear resistance.

表１及び２の結果から、実施例１〜５は、氷上性能、操縦安定性、及び耐摩耗性が共に平均以上であることが判る。また、比較例１〜２に示すように、微粒子含有樹脂体を含まないタイヤのトレッドにあっては、従来のＰＥ有機繊維（線状樹脂体）を配合したとしても、操縦安定性及び耐摩耗性がさほど向上しないことが判る。また、非線状樹脂体を十分に発泡させないものでも、微粒子含有樹脂体には表２の実施例６〜８に示すように、氷上性能を向上させる作用があり、また、操縦安定性及び耐摩耗性も向上してくることが判る。 The above results are shown in Tables 1 and 2.

From the results of Tables 1 and 2, it can be seen that Examples 1 to 5 are above average in terms of on-ice performance, steering stability, and wear resistance. In addition, as shown in Comparative Examples 1 and 2, in the tread of a tire that does not contain the fine particle-containing resin body, even if the conventional PE organic fiber (linear resin body) is blended, the steering stability and wear resistance It turns out that sex does not improve so much. Even if the non-linear resin body is not sufficiently foamed, the fine particle-containing resin body has an effect of improving the performance on ice as shown in Examples 6 to 8 in Table 2, and also has a steering stability and resistance. It can be seen that the wear resistance is also improved.

  The rubber composition according to the present invention can be used for a tire capable of improving the on-ice performance of the tire such as braking, driving, cornering performance, etc. on an icy road surface, and also improving the wear resistance thereof. A rubber composition is appropriately vulcanized, and the vulcanized rubber can be used for a tread portion of a tire.

FIG. 1 is a schematic sectional view of a tire according to the present invention. FIG. 2 is a schematic view of a resin body of the rubber composition according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 A pair of bead part 2 Carcass 3 Belt 4 Tire 5 Tread 6 Cap part 10 Fine particle containing resin 11 Fine particle

Claims (10)

  A rubber composition comprising a non-linear fine particle-containing resin body containing fine particles having a Mohs hardness of 2 or more dispersed in a rubber matrix.   The rubber composition according to claim 1, wherein the fine particle-containing resin body is spherical.   The rubber composition according to claim 2, wherein the fine particle-containing resin body has a particle size in the range of 10 to 500 μm.   4. The rubber composition according to claim 3, wherein the fine particles have an average particle size in the range of 0.1 to 100 [mu] m, and the fine particles have a smaller diameter than the resin body.   The rubber composition according to any one of claims 1 to 4, wherein the fine particle-containing resin body contains 5 to 50 parts by mass of the fine particles with respect to 100 parts by mass of the resin.   The rubber component constituting the rubber matrix is composed of at least one rubber component selected from natural rubber and Gen-based synthetic rubber, and the resin body is added in an amount of 0.1 to 30 masses per 100 mass parts of the rubber component. The rubber composition according to claim 1, which is contained in a range of parts.   The resin in the fine particle-containing resin body has a viscosity characteristic lower than the rubber viscosity in the rubber matrix until reaching the maximum vulcanization temperature at the time of vulcanization. A rubber composition according to any one of the above.   The rubber composition according to any one of claims 1 to 7, comprising a foaming agent.   A vulcanized rubber obtained by vulcanizing the rubber composition according to claim 8 and having a foaming ratio in the range of 3 to 40%.   10. A vulcanized rubber according to claim 9, comprising a pair of bead portions, a carcass continuous in a toroidal shape with the bead portions, and a belt and a tread for tightening a crown portion of the carcass, wherein the tread is a vulcanized rubber according to claim 9. Tire comprising.

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