JP2009046012A - Rubber block, tread rubber, and tire and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire with drain holes which can be formed when vulcanizing a raw tire in a mold, having improved braking performance on a wet road surface or on an ice/snow covered road surface. <P>SOLUTION: The tire has rubber blocks 3 each partitioned with a peripheral groove 1 and a cross groove 2 and provided on a tread part. The rubber blocks 3 each have the drain holes 4A, 4B opened to the tread face, the side face, or the sipe face in two or more positions and communicated with each other. The drain holes 4A, 4B each have a coat 5 on the inner face, preferably the coat 5 formed of a resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber block, a tread rubber including the rubber block, a tire including the tread rubber, and a method of manufacturing the tire, and particularly relates to a tire excellent in braking performance on a wet road surface or an ice / snow road surface. It is.

  Currently, from the viewpoint of improving vehicle safety, various studies have been made to improve the braking performance and drivability of tires not only on dry road surfaces but also on wet road surfaces, icy and snowy road surfaces, and the like. Yes. For example, in a tire having a block in a tread, a sipe is formed on the surface of the block to improve drainage, and the braking performance of the tire on a wet road surface or an ice / snow road surface is improved. However, in this case, there is a problem that the block rigidity is lowered due to the formation of the sipe, and the steering stability of the tire is lowered.

  With respect to this problem, in Japanese Patent Laid-Open No. 2000-247113 (Patent Document 1), in a tire having a block on a tread, a communication port having one end opened on the tread surface of the block and the other end opened on the side surface of the block is used as a block. There has been proposed a technique for improving the performance of a tire on a wet road surface or an icy / snow road surface while suppressing a decrease in block rigidity.

  Further, in Japanese Patent Application Laid-Open No. 2006-168462 (Patent Document 2), in a tire having a block in which a sipe is formed in a tread, one end is connected to the sipe and opens to the tread, and the other end is different from the sipe on the side surface of the block. There has been proposed a technique for improving the performance of a tire on an icy road while suppressing a decrease in block rigidity by forming a drain hole opened at a position in the block.

JP 2000-247113 A JP 2006-168462 A

  However, in JP-A-2000-247113 and JP-A-2006-168462, although the communication port or drain hole formed in the block can improve the drainage of the block, it is not oriented in the tire radial direction. If these communication ports or drain holes are formed during vulcanization of the green tire in the mold, the mold cannot be removed from the tire unless a large cut is made in the tread rubber after vulcanization. When a large cut is made in the tread rubber, the ground contact area and block rigidity of the tread are reduced, so that the performance of the tire on the wet road surface and the ice / snow road surface cannot be sufficiently improved.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, have drain holes, and the drain holes can be formed at the time of vulcanization of the raw tire in the mold, and are also used for wet road surfaces and ice and snow road surfaces. The present invention provides a tire excellent in braking performance and a method for manufacturing the tire. Another object of the present invention is to provide a tread rubber suitable for such a tire and a rubber block suitable for the tread rubber.

  As a result of diligent investigations to achieve the above object, the present inventor (1) (a) a thermoplastic resin having a shape corresponding to a drain hole while applying a rubber composition containing a foaming agent to a tread rubber The body is embedded in the tread rubber of the green tire, or (b) a thermoplastic resin body having a shape corresponding to the drainage hole and containing the foaming agent is embedded in the tread rubber of the green tire and vulcanized. In addition, the thermoplastic resin body melts and softens during vulcanization, and the gas is collected from the foaming agent at the position where the resin body is embedded, so that a tire having a drain hole having a desired shape can be manufactured. (2) A tire having a drain hole having a desired shape can also be produced by embedding a hollow resin body having a lumen corresponding to the drain hole in a tread rubber of a raw tire and vulcanizing. In these methods, Tread rubber after vulcanization Since it is possible to remove the mold from the tire without making a sharp cut, it is found that the manufactured tire is excellent in braking performance on wet road surfaces and icy and snow road surfaces, and to complete the present invention. It came.

That is, the rubber block of the present invention is characterized by having drain holes that are opened at two or more locations on the upper surface, side surface, or sipe surface, and that the drain holes have a coating on the inner surface. Here, the drainage holes, it is preferable that the cross-sectional area is 1 × 10 ^-6 mm ² or more.

  In a preferred example of the rubber block of the present invention, the coating film is made of a resin. In this case, the edge effect of the rubber block is high.

  The rubber block of the present invention preferably has a plurality of the drain holes. Here, it is more preferable that the plurality of drain holes communicate with each other. In this case, the drainage of the rubber block is high.

  The tread rubber of the present invention is characterized by comprising the above rubber block, and the tire of the present invention is characterized by comprising the tread rubber.

Furthermore, the manufacturing method of the 1st tire of this invention is as follows.
A rubber composition containing a foaming agent and a thermoplastic resin body are prepared, and the thermoplastic resin body is embedded in the foaming agent-containing rubber composition, or a thermoplastic resin body and rubber containing a foaming agent Preparing a composition, embedding the foaming agent-containing thermoplastic resin body in the rubber composition, and forming an unvulcanized tread rubber;
Forming a green tire having the unvulcanized tread rubber in a tread portion;
And vulcanizing the green tire. Here, the thermoplastic resin body is preferably a cross-sectional area is 1 × 10 ^-6 mm ² or more, in this case, the cross-sectional area can be formed 1 × 10 ^-6 mm ² or more drain holes.

In addition, the second tire manufacturing method of the present invention includes:
Preparing a hollow resin body and a rubber composition;
Embedding the hollow resin body in the rubber composition to form an unvulcanized tread rubber;
Forming a green tire having the unvulcanized tread rubber in a tread portion;
And vulcanizing the green tire. Here, the hollow resin body preferably has a cross-sectional area of a lumen of 1 × 10 ⁻⁶ mm ² or more, and in this case, a drain hole having a cross-sectional area of 1 × 10 ⁻⁶ mm ² or more can be formed.

  According to the first and second tire manufacturing methods of the present invention, the tread portion is provided with the rubber block defined by the circumferential groove and the lateral groove, and the rubber block is provided on the tread tread surface, the side surface, or the sipe surface. It is possible to manufacture a tire that has drain holes that are open and communicated at more than one location, and the drain holes have a resin coating on the inner surface. In addition, according to the first and second tire manufacturing methods of the present invention, not only drain holes extending in the tire radial direction, but also drain holes extending in the tire width direction and drain holes extending in the tire circumferential direction are vulcanized. It can be manufactured without making a large cut in the tread rubber.

  According to the present invention, a tire having drainage holes, which can be formed at the time of vulcanization of a raw tire in a mold, and a tire excellent in braking performance on wet road surfaces and icy and snowy road surfaces, and its A manufacturing method can be provided. Moreover, a tread rubber suitable for such a tire and a rubber block suitable for the tread rubber can be provided.

<Rubber block, tread rubber and tire>
Hereinafter, the rubber block, the tread rubber, and the tire of the present invention will be described in detail with reference to the drawings. 1 is a plan view of an example of a tread of a tire according to the present invention, FIG. 2 is an enlarged perspective view of a rubber block of the tread shown in FIG. 1, and FIG. 3 is a perspective view of another rubber block. . The tread shown in FIG. 1 has a plurality of rubber blocks 3 partitioned by a circumferential groove 1 and a lateral groove 2 and has a so-called block pattern, but the tread of the present invention may have another structure. . When the tread has a plurality of rubber blocks 3 defined by the circumferential grooves 1 and the lateral grooves 2, the wet road surface and the ice / snow road surface are affected by the block edge component in the tire circumferential direction and the block edge component in the tire width direction. The braking performance at is improved. Moreover, although the tread shown in FIG. 1 has a left-right symmetric structure with respect to the equator plane CL of the tire, the tread of the present invention is not limited to this.

  The rubber block 3 shown in FIG. 2 has a drain hole 4A that opens to the upper surface (that is, the tread surface) and a drain hole 4B that opens to the side surface, and these drain holes 4A and 4B communicate with each other. When the drain hole 4A opening on the upper surface communicates with the drain hole 4B opening on the side surface, the water taken in from the drain hole 4A opening on the upper surface passes through the drain hole 4B opened on the side surface. Since the water is drained to the side, the drainage is high, and the braking performance on the wet road surface and the snowy road surface of the tire is greatly improved. In addition, in the rubber block 3 shown in FIG. 2, the drainage hole 4A opening on the upper surface is a rectangular parallelepiped shape, the drainage hole 4B opening on the side surface is cylindrical, and the drainage hole 4A and the drainage hole 4B intersect at a right angle. However, the shape of the drain hole in the rubber block 3 of the present invention is not limited to this. Moreover, the rubber block of this invention may have a sipe, and the drainage hole should just open and communicate with two or more places on the upper surface, side surface, or sipe surface of a rubber block. In addition, the opening of a drain hole may exist in the same surface, and may exist in a different surface.

  The rubber block 3 shown in FIG. 3 has a drain hole 4A that opens on the top surface and a drain hole 4B that opens on the side surface, and both the drain hole 4A that opens on the top surface and the drain hole 4B that opens on the side surface. It is cylindrical and intersects at right angles, and the drain holes 4A and 4B communicate with each other. Also in this case, the drainage of the rubber block 3 is high, and the braking performance of the tire on the wet road surface and the icy / snow road surface is greatly improved.

2 and 3, at least one of the drain holes 4A and 4B of the rubber block 3, preferably both, has a cross-sectional area of 1 × 10 ⁻⁶ mm ² or more. This is because if the cross-sectional area of the drain holes 4A and 4B is less than 1 × 10 ⁻⁶ mm ² , the amount that can be drained is reduced.

  FIG. 4 is a cross-sectional view of the rubber block 3 shown in FIG. 2 taken along the surface IV. At least one of the drain holes 4A and 4B of the rubber block 3, preferably both, are coated on the inner surface with a coating 5, preferably resin. It has the film 5 which becomes. When the drain holes 4A and 4B have the coating 5 made of resin on the inner surface, even if the rubber block 3 is stressed, the deformation of the drain holes 4A and 4B is suppressed, and the designed performance can be exhibited. . In this case, the excellent edge effect of the drain holes 4A and 4B increases the friction coefficient μ of the tread on ice, and improves the braking performance of the tire on ice.

  In addition, in FIGS. 2-4, since the drain hole 4A opened on the upper surface is oriented in the tire radial direction, it does not have to have the coating 5 on the inner surface, and is formed at the time of vulcanization by a normal method. Can do. On the other hand, the drain hole 4B that opens to the side surface cannot be formed by a normal method, and as described later, a material that can disappear in a vulcanization process such as a thermoplastic resin body or a hollow resin is formed at a position where the drain hole 4B is formed. It can be produced by forming a tread rubber by embedding in vulcanized and vulcanizing. In addition, even if the drainage hole 4B opened to the side surface extends in the tire circumferential direction, it may extend in the tire width direction.

  Moreover, it is preferable that the opening of the drain hole 4A opened on the upper surface is closed in the rubber block 3, that is, the opening only opens on the upper surface and does not open on the side surface of the rubber block 3. preferable. When the opening of the drain hole 4A that opens on the upper surface is not closed in the rubber block 3, that is, when the opening that opens on both the upper surface and the side surface exists in the rubber block 3, the block rigidity of the rubber block 3 decreases. The steering stability of the tire may be reduced.

  The drain hole 4 in the rubber block 3 shown in FIGS. 2 to 4 is linear, but the drain hole in the rubber block of the present invention may not be linear but may be curved. Good.

<Tire manufacturing method>
The tire of the present invention comprising the tread rubber having the rubber block described above, that is, the tread portion is provided with the rubber block 3 defined by the circumferential groove 1 and the lateral groove 2, and the rubber block 3 is a tread surface, side surface or sipe. A tire having drain holes 4A and 4B that are opened at two or more places on the surface and communicate with each other. The drain holes 4A and 4B have a coating on the inner surface. (A) A thermoplastic resin body is prepared in advance and foamed into a rubber component. A rubber composition is prepared by blending an agent, and the thermoplastic resin body is embedded in the foaming agent-containing rubber composition, or (b) a thermoplastic resin body containing a foaming agent is prepared in advance. In addition, a rubber composition is prepared, and the foaming agent-containing thermoplastic resin body is embedded in the rubber composition to form an unvulcanized tread rubber, and the unvulcanized tread rubber is formed in the tread portion. Shaped raw tire And it can be produced by vulcanizing the biological tire. In this case, the film 5 is made of a thermoplastic resin that has constituted a thermoplastic resin body. Moreover, the shape of the thermoplastic resin body to be used is selected according to the shape of the target drain holes 4A and 4B.

The method for producing the thermoplastic resin body is not particularly limited, and extrusion molding, molding, or the like can be employed. Also, organic fibers, organic fiber cords, or the like can be used as the thermoplastic resin body. it can. Incidentally, a thermoplastic resin material containing a thermoplastic resin body and a foaming agent does not contain a foaming agent, it is preferable that the cross-sectional area is 1 × 10 ^-6 mm ² or more.

  When a thermoplastic resin body is embedded in a rubber composition containing a foaming agent, the thermoplastic resin body melts or softens during vulcanization, while the rubber matrix generates from the foaming agent during vulcanization. Compared with the rubber matrix in which the vulcanization reaction has progressed, the gas thus produced tends to stay inside the molten or softened thermoplastic resin that constitutes the thermoplastic resin body. Further, when a thermoplastic resin body containing a foaming agent is embedded in the rubber composition, the gas generated from the foaming agent in the thermoplastic resin body is melted or softened which constitutes the thermoplastic resin body. There is a tendency to stay inside the thermoplastic resin. As a result, in each rubber block of the tire tread obtained by vulcanization, pores exist where the thermoplastic resin body was present. The pores are encapsulated in the periphery (wall surface of the pores) with a film made of a thermoplastic resin that constitutes a thermoplastic resin body, and thus exhibit an excellent edge effect. It is possible to improve the braking performance on wet road surfaces and ice / snow road surfaces. Note that when the thermoplastic resin material constituting the thermoplastic resin body is polyethylene, polypropylene, or the like, the vulcanized rubber matrix and the resin are firmly bonded.

  The thermoplastic resin body preferably has a thermal characteristic that melts (including softening) until the rubber matrix reaches the maximum vulcanization temperature. A thermoplastic resin having characteristics is preferred. As the thermoplastic resin body having the thermal characteristics, for example, a thermoplastic resin body composed of a crystalline polymer having a melting point lower than the maximum vulcanization temperature can be preferably exemplified. The thermoplastic resin body composed of the crystalline polymer will be described as an example. The larger the difference between the melting point of the thermoplastic resin body and the maximum vulcanization temperature of the rubber composition, the faster the vulcanization of the rubber composition. The thermoplastic resin body melts. On the other hand, if the melting point of the thermoplastic resin body is too close to the maximum vulcanization temperature of the rubber composition, the thermoplastic resin body does not melt quickly at the initial stage of vulcanization, and the thermoplastic resin body melts at the end of vulcanization. . At the end of vulcanization, the gas generated from the foaming agent is dispersed or taken into the vulcanized rubber matrix, and a sufficient amount of air is not retained in the molten thermoplastic resin body.

  The upper limit of the melting point (or softening point) of the thermoplastic resin body is preferably selected in consideration of the above points, and is generally 10 ° C. or more lower than the maximum vulcanization temperature of the rubber composition. It is more preferable that the temperature is lower by 20 ° C. or more. The industrial vulcanization temperature of a rubber composition is generally about 190 ° C at the maximum, but for example, when the maximum vulcanization temperature is set to 190 ° C, the melting point of the thermoplastic resin body Is usually selected within a range of 190 ° C. or less, preferably 180 ° C. or less, and more preferably 170 ° C. or less.

  The thermoplastic resin body may be formed from the above-described crystalline polymer, may be formed from an amorphous polymer, or may be formed from a crystalline polymer and an amorphous polymer. However, it is preferably formed of an organic material containing a crystalline polymer in terms of viscosity control that occurs suddenly at a temperature at which the viscosity changes due to a phase transition and is easy to control the viscosity. More preferably, it is formed from only.

  Examples of the crystalline polymer include polyethylene (PE), polypropylene (PP), polybutylene, polybutylene succinate, polyethylene succinate, syndiotactic-1,2-polybutadiene (SPB), polyvinyl alcohol (PVA), Polyvinyl chloride (PVC) can 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, polyethylene is low in melting point and easy handling. (PE) is particularly preferred.

  Examples of the non-crystalline polymer include polymethyl methacrylate (PMMA), acrylonitrile / butadiene / styrene copolymer (ABS), polystyrene (PS), polyacrylonitrile, and the like. You may use, and may use 2 or more types together. Moreover, these non-crystalline polymers and the above-described crystalline polymers may be used in combination.

  Examples of the foaming agent used for the preparation of the foaming agent-containing rubber composition include azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT), dinitrosopentastyrenetetramine, benzenesulfonylhydrazide derivatives, p, p'- Oxybisbenzenesulfonyl hydrazide (OBSH), ammonium bicarbonate that generates carbon dioxide, sodium bicarbonate, ammonium carbonate, nitrososulfonylazo compounds that generate nitrogen, N, N'-dimethyl-N, N'-dinitrosophthalamide , Toluenesulfonyl hydrazide, p-toluenesulfonyl semicarbazide, p, p′-oxybisbenzenesulfonyl semicarbazide and the like. Among these foaming agents, azodicarbonamide (ADCA) and dinitrosopentamethylenetetramine (DPT) are preferable from the viewpoint of production processability, and azodicarbonamide (ADCA) is particularly preferable. These foaming agents may be used individually by 1 type, and may use 2 or more types together. The blending amount of the foaming agent is not particularly limited, but is preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

  The rubber component is not particularly limited. In addition to natural rubber (NR), polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene-diene rubber. (EPDM), chloroprene rubber (CR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR), and other synthetic rubbers can be used. These rubber components may be used alone or in combination. You may blend and use the above.

  The foaming agent is preferably used in combination with urea, zinc stearate, zinc benzenesulfinate, zinc white or the like as a foaming aid. These may be used individually by 1 type and may use 2 or more types together. By using a foaming aid in combination, the foaming reaction can be promoted to increase the degree of completion of the reaction, and unnecessary deterioration can be suppressed over time.

  The above-mentioned foaming agent-containing rubber composition is a compounding agent usually used in the rubber industry, for example, a filler such as carbon black, a softening agent, stearic acid, and anti-aging, in addition to the foaming agent and foaming aid. An agent, zinc white, a vulcanization accelerator, a vulcanizing agent, and the like can be appropriately selected and blended within a range not impairing the object of the present invention, and kneaded.

  The thermoplastic resin body is embedded in the foaming agent-containing rubber composition prepared as described above to form an unvulcanized tread rubber, and the tread portion is provided with the unvulcanized tread rubber according to a conventional method. Forming a raw tire, vulcanizing the raw tire, generating gas from the foaming agent in the rubber composition, melting or softening the thermoplastic resin body, and keeping the gas inside the thermoplastic resin Thus, drain holes 4A and 4B having a shape corresponding to the shape of the thermoplastic resin body are formed, and the drain holes 4A and 4B have a coating 5 made of the thermoplastic resin that has formed the thermoplastic resin body on the inner surface. .

  On the other hand, when preparing a thermoplastic resin body containing a foaming agent and a rubber composition, and embedding the foaming agent-containing thermoplastic resin body in the rubber composition to form an unvulcanized tread rubber, As the foaming agent and thermoplastic resin, the above foaming agent and thermoplastic resin can be used. For example, the foaming agent-containing thermoplastic is added to the thermoplastic resin and molded into a desired shape. A resin body can be prepared.

  Further, the rubber composition for embedding the above-mentioned foaming agent-containing thermoplastic resin is a compounding agent usually used in the rubber industry, such as a filler such as carbon black, a softening agent, stearic acid, and anti-aging. An agent, zinc white, a vulcanization accelerator, a vulcanizing agent, and the like can be appropriately selected and blended within a range not impairing the object of the present invention, and kneaded.

  The foaming agent-containing thermoplastic resin body prepared as described above is embedded in a rubber composition to form an unvulcanized tread rubber, and a raw material provided with the unvulcanized tread rubber in the tread portion according to a conventional method. Form a tire, vulcanize the green tire, generate gas from the foaming agent in the thermoplastic resin body, melt or soften the thermoplastic resin body, and the gas stays inside the thermoplastic resin Thus, drain holes 4A and 4B having a shape corresponding to the shape of the thermoplastic resin body are formed, and the drain holes 4A and 4B have a coating 5 made of the thermoplastic resin that has formed the thermoplastic resin body on the inner surface. .

  In the above method, the end of the thermoplastic resin body may be covered with rubber or the like. Therefore, in order to prevent the end of the thermoplastic resin body from being covered with rubber or the like, a water-soluble resin or the like may be disposed in advance on the end of the thermoplastic resin body. In this case, drain holes 4A and 4B in which water-soluble resin and the like are disposed at the end of the opening are formed. However, when the tire is used, the water-soluble resin and the like are dissolved by water, and the target drain holes 4A and 4B 4B is obtained.

In the tire of the present invention, a hollow resin body and a rubber composition are prepared in advance, and the hollow resin body is embedded in the rubber composition to form an unvulcanized tread rubber. It can also be produced by forming a green tire having a vulcanized tread rubber in the tread portion and vulcanizing the green tire. In this case, the coating 5 is made of a resin that has formed a hollow resin body. The shape of the lumen of the hollow resin body to be used is selected according to the shape of the target drain holes 4A and 4B, and the hollow resin body has a cross-sectional area of the lumen of 1 × 10 ⁻⁶ mm ² or more. It is preferable that

  Here, the hollow resin body to be used may or may not be melted or softened during vulcanization of the green tire. When the hollow resin body does not melt and soften during vulcanization of the green tire, the holes in the hollow resin body become the drain holes 4A and 4B as they are. On the other hand, when the hollow resin body is melted or softened during vulcanization of the green tire, pores are formed where the hollow resin body was present. The pores are covered with a resin film made of a raw material resin that has formed a hollow resin body in the periphery (the wall surface of the bubbles), and is in a capsule shape.

  When the hollow resin body is melted or softened during vulcanization of the raw tire, the hollow resin body used has a thermal characteristic that melts (including softening) until the rubber matrix reaches the maximum temperature of vulcanization. The material of the hollow resin body is preferably a thermoplastic resin having the above thermal characteristics. As the hollow resin body having the thermal characteristics, for example, a hollow resin body made of a crystalline polymer having a melting point lower than the maximum vulcanization temperature can be suitably exemplified. The hollow resin body made of the crystalline polymer will be described as an example. As the difference between the melting point of the hollow resin body and the maximum vulcanization temperature of the rubber composition increases, the hollow resin body rapidly vulcanizes during the vulcanization of the rubber composition. The body melts. On the other hand, if the melting point of the hollow resin body becomes too close to the maximum vulcanization temperature of the rubber composition, the hollow resin body does not melt quickly at the initial stage of vulcanization, and the hollow resin body melts at the end of vulcanization. At the end of vulcanization, the air present in the hollow resin body diffuses and is dispersed or taken into the vulcanized rubber matrix, and a sufficient amount of air is not retained in the melted hollow resin body.

  When the hollow resin body is melted or softened during vulcanization of the green tire, the upper limit of the melting point (or softening point) of the hollow resin body to be used is preferably selected in consideration of the above points. Further, it is preferably 10 ° C. or more lower than the maximum vulcanization temperature of the rubber composition, more preferably 20 ° C. or more. The industrial vulcanization temperature of a rubber composition is generally about 190 ° C at maximum, but for example, when the maximum vulcanization temperature is set to 190 ° C, the melting point of the hollow resin body Is usually selected within a range of 190 ° C. or less, preferably 180 ° C. or less, and more preferably 170 ° C. or less.

  The hollow resin body may be formed of the above-described crystalline polymer, may be formed of an amorphous polymer, or may be formed of a crystalline polymer and an amorphous polymer. However, it is preferably formed from an organic material containing a crystalline polymer in terms of viscosity control that occurs suddenly at a temperature at which the viscosity changes due to the phase transition, and is easy to control the viscosity. More preferably, it is formed from. As the crystalline polymer and the non-crystalline polymer forming the hollow resin body, the above-described crystalline polymer and non-crystalline polymer capable of forming the thermoplastic resin body may be used. it can.

  On the other hand, the rubber composition for embedding the hollow resin body includes a rubber component, a compounding agent usually used in the rubber industry, for example, a filler such as carbon black, a softener, a stearic acid, an anti-aging agent, a zinc oxide. In addition, a vulcanization accelerator, a vulcanizing agent, and the like can be appropriately selected and blended within a range that does not impair the object of the present invention, and then kneaded.

  The hollow resin body is embedded in the rubber composition to form an unvulcanized tread rubber, and according to a conventional method, a green tire including the unvulcanized tread rubber in a tread portion is formed. The rubber block 3 having drain holes 4A and 4B having a shape corresponding to the shape of the inner cavity of the hollow resin body was formed by vulcanization, and the drain holes 4A and 4B constituted the hollow resin body on the inner surface. It has the film 5 made of resin.

  In the above method, the end of the lumen of the hollow resin body may be blocked with rubber or the like. Therefore, in order to prevent the end of the lumen of the hollow resin body from being blocked by rubber or the like, the end of the lumen of the hollow resin body may be filled in advance with a water-soluble resin or the like. In this case, drain holes 4A and 4B filled with water-soluble resin or the like are formed at the ends of the openings, but the water-soluble resin or the like is dissolved by water when the tire is used, and the desired drain holes 4A and 4B are formed. Is obtained.

  In the above-described method, a conventionally used mold can be used as a mold used for vulcanizing the raw tire. Further, by arranging a blade extending in the tire radial direction on the surface corresponding to the tread of a normal mold, the thermoplastic resin body and the hollow resin body embedded in the tread rubber can be cut. . Further, by arranging a convex portion corresponding to the shape of the drain hole 4A opening in the tread tread surface on the surface corresponding to the tread of the normal mold, the drain hole 4A opening in the tread tread surface may be added. it can.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Example 1
70 parts by mass of natural rubber, 30 parts by mass of polybutadiene rubber [manufactured by JSR, BR01], 50 parts by mass of carbon black (N220), 4.0 parts by mass of dehydrated castor oil fatty acid, 1.5 parts by mass of stearic acid, and 3.0 parts by mass of zinc oxide Aging inhibitor 6C [N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine] 1.0 part by mass, vulcanization accelerator DM (dibenzothiazyl disulfide) 0.2 part by mass, Sulfur accelerator CZ (N-cyclohexyl-2-benzothiazylsulfenamide) 0.5 parts by mass, sulfur 1.2 parts by mass, blowing agent DPT (dinitrosopentamethylenetetramine) 2.5 parts by mass, urea 2.5 parts by mass A foaming agent-containing rubber composition was prepared.

  A tread rubber was produced by embedding a polyethylene fiber having a diameter of 1 mm in the foaming agent-containing rubber composition at a depth of 5 mm from the tread surface so as to be oriented in the tire circumferential direction, and the tread rubber was used. A raw tire was produced. Next, the green tire was vulcanized using a mold having a blade having a cross-sectional shape of 20 mm in width, 1.0 mm in height, and 7.5 mm in the radial direction of the tire in a portion corresponding to the tread surface. A block tire of size 195 / 65R15 was produced. The tread rubber block has a tire circumferential length of 40 mm, a tire width length of 30 mm, and a tire radial depth (block height) of 9 mm. And drain holes that open in the side surfaces extend in the tire circumferential direction.

(Comparative Example 1)
A tire was produced in the same manner as in Example 1 except that tread rubber was produced without embedding polyethylene fibers in the foaming agent-containing rubber composition.

<Evaluation of performance on ice>
From the initial speed of 40 km / h to full braking on the icy road, when the tire is mounted on a regular rim and the internal pressure is 200 kPa, mounted on a passenger car and loaded with a regular load, The braking distance was measured, and the average deceleration was calculated from the initial speed and the braking distance. Further, the average deceleration of the tire of Comparative Example 1 was expressed as an index, and the results shown in Table 1 were obtained. The larger the index value, the larger the average deceleration and the better the braking performance on ice.

  As is apparent from Table 1, the braking performance of the tire on ice can be greatly improved by forming the rubber block having the drainage holes according to the present invention on the tread.

It is a top view of an example of the tread of the tire of the present invention. It is an expansion perspective view of the rubber block of the tread shown in FIG. It is a perspective view of another example of the rubber block according to the present invention. FIG. 4 is a cross-sectional view of the rubber block shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circumferential groove 2 Horizontal groove 3 Rubber block 4A Drainage hole opened to upper surface (tread tread) 4B Drainage hole opened to side surface 5 Coating

Claims (11)

A rubber block having a drainage hole that opens and communicates with two or more locations on the upper surface, side surface, or sipe surface,
The rubber block, wherein the drain hole has a coating on the inner surface. The rubber block according to claim 1, wherein the drainage hole has a cross-sectional area of 1 × 10 ⁻⁶ mm ² or more.   The rubber block according to claim 1, wherein the coating is made of a resin.   The rubber block according to claim 1, wherein the rubber block has a plurality of drain holes.   The rubber block according to claim 4, wherein the plurality of drain holes communicate with each other.   A tread rubber comprising the rubber block according to claim 1.   A tire comprising the tread rubber according to claim 6. The tread portion has a rubber block partitioned by a circumferential groove and a lateral groove, and the rubber block has two or more drain holes that are opened and communicated with each other on the tread surface, side surface, or sipe surface. A method for manufacturing a tire having a coating,
A rubber composition containing a foaming agent and a thermoplastic resin body are prepared, and the thermoplastic resin body is embedded in the foaming agent-containing rubber composition, or a thermoplastic resin body and rubber containing a foaming agent Preparing a composition, embedding the foaming agent-containing thermoplastic resin body in the rubber composition, and forming an unvulcanized tread rubber;
Forming a green tire having the unvulcanized tread rubber in a tread portion;
And a step of vulcanizing the green tire. The tire manufacturing method according to claim 8, wherein a cross-sectional area of the thermoplastic resin body is 1 × 10 ⁻⁶ mm ² or more. The tread portion has a rubber block partitioned by a circumferential groove and a lateral groove, and the rubber block has two or more drain holes that communicate with each other on the tread surface, side surface, or sipe surface. A method for manufacturing a tire having a coating,
Preparing a hollow resin body and a rubber composition;
Embedding the hollow resin body in the rubber composition to form an unvulcanized tread rubber;
Forming a green tire having the unvulcanized tread rubber in a tread portion;
And a step of vulcanizing the green tire. The tire manufacturing method according to claim 10, wherein a cross-sectional area of a lumen of the hollow resin body is 1 × 10 ⁻⁶ mm ² or more.

Images