JP2017074854A - Pneumatic tire, manufacturing method for tread material to be used in the same and tire manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in on-snow performance by improving a tread rubber, a manufacturing method for a tread material to be used for the same, and a manufacturing method for a tire.SOLUTION: A pneumatic tire comprises a block pattern at a tread surface part. In at least part of a tread block constituting the block pattern is buried a core-sheath type conjugate fiber in which a core part is made of high melting point resin (A) having a melting point of 150°C or more and a sheath part is made of a resin material (B) lower in a melting point than the high melting point resin including olefinic system polymers (D), and a longitudinal direction of the conjugate fiber is disposed within 20 degrees from a tire radial direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more particularly, to a pneumatic tire related to improvement of a tread surface portion, a method of manufacturing a tread material used therefor, and a method of manufacturing a tire.

  Conventionally, in winter pneumatic tires, sipes extending in the tread width direction have been added to blocks and ribs (hereinafter collectively referred to as blocks) constituting a tire tread pattern in order to improve braking performance on snow. I came. However, since the amount of water film generated on the road surface on snow differs between low and high temperatures, it is difficult to ensure stable performance in various environments.

  On the other hand, for example, Patent Document 1 provides a tire excellent in performance on ice and snow by simultaneously improving or balancing adhesion, adhesion friction and digging friction, scratch friction and wear resistance on an ice and snow road surface. For this purpose, non-metallic short fibers having a predetermined average fiber diameter and average length are dispersed in a diene rubber so as to be oriented in the tread thickness direction, and the complex elastic modulus E1 in the tread thickness direction and the tire circumference A studless tire having a tread in which the elastic modulus E2 in the direction and the tread rubber hardness are prescribed is disclosed.

  On the other hand, various organic fibers and metal materials have been studied and used as tire reinforcing materials. In addition, as a kind of organic fiber, various studies have been made so far to use a so-called core-sheath fiber as a reinforcing material, which includes a core part having a cross-sectional structure at the center and a sheath part covering the outer periphery thereof. For example, Patent Document 1 discloses that a thermoplastic resin that can be thermally fused to rubber using a resin selected from at least one of polyester, polyamide, polyvinyl alcohol, polyacrylonitrile, rayon, and a heterocyclic ring-containing polymer as a core component. A cord / rubber composite is disclosed in which a cord made of a core-sheath fiber having a resin as a sheath component is embedded in unvulcanized rubber and vulcanized and integrated.

JP 2001-039104 A (Claims etc.) Japanese Patent Laid-Open No. 10-6406 (claims, etc.)

  However, in the technique such as Patent Document 1 in which short fibers are blended in tread rubber, there are problems such as poor dispersion of short fibers into rubber and destruction due to insufficient adhesion (adhesion) force between rubber and fibers. In contrast, when a resin having a relatively low melting point and a good compatibility with rubber and adhesiveness is used as a short fiber, sufficient friction characteristics cannot be obtained.

  Accordingly, an object of the present invention is to provide a pneumatic tire having improved performance on snow by improving tread rubber, a method for producing a tread material used therefor, and a method for producing a tire.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by embedding a specific core-sheath type composite fiber (hereinafter also simply referred to as “core-sheath fiber”) in a tread block of a pneumatic tire. Thus, the present invention has been completed.

That is, the pneumatic tire of the present invention is a pneumatic tire provided with a block pattern on the tread surface portion,
At least a part of the tread block constituting the block pattern is made of a high melting point resin (A) having a core part having a melting point of 150 ° C. or higher, and a sheath part containing the olefin polymer (D) than the high melting point resin. A core-sheath type composite fiber made of a resin material (B) having a low melting point is embedded, and the longitudinal direction of the composite fiber is oriented in a direction within 20 ° from the tire radial direction. To do.

  In the tire of the present invention, the olefin polymer (D) is a propylene-α olefin copolymer (H), a propylene-nonconjugated diene copolymer (I), an unsaturated carboxylic acid or an anhydride thereof. It contains at least one component selected from the group consisting of an ionomer (J) having a degree of neutralization with a metal salt of an olefin copolymer containing monomers of 20% or more, and an olefin homopolymer (K). It is preferable that it consists of.

  In the tire of the present invention, the resin material (B) includes a styrene elastomer (L) containing a single molecular chain in which the olefin polymer (D) and a styrene monomer are mainly continuously arranged. ), A vulcanization accelerator (M), a vulcanization accelerator auxiliary (N), and a filler (O) are preferably contained. Furthermore, in the tire of the present invention, the propylene-α olefin copolymer (H) is preferably a propylene-ethylene random copolymer and / or a propylene-ethylene-butene random copolymer, and the ionomer ( J) is preferably an ionomer of a polyethylene polymer and / or a polypropylene polymer, and the ionomer (J) is particularly preferably an ionomer of an ethylene / methacrylic acid copolymer.

  Furthermore, in the tire of the present invention, the olefin homopolymer (K) is preferably a polyethylene polymer and / or a polypropylene polymer, and the styrene elastomer (L) is a styrene block copolymer. It is preferable to contain a coalescence or a hydrogenated product thereof or a modified product thereof, and the styrene-based elastomer (L) is more preferably a styrene-ethylene-butadiene-styrene copolymer. Furthermore, in the tire of the present invention, the high melting point resin (A) is selected from a polyolefin resin (P), a polyester resin (Q), and a polyamide resin (R) having a melting point of 150 ° C. or higher. A resin material containing a polymer is preferable.

Furthermore, in the tire of the present invention, the fineness of the composite fiber is preferably 0.5 to 2200 dtex. Furthermore, in the tire of the present invention, the embedment density of the composite fiber is preferably 0.5 to 60/50 mm ² .

  The method for producing a tread material of the present invention is a core-sheath type in which a core part is made of a high melting point resin having a melting point of 150 ° C. or more, and a sheath part is made of a resin material containing an olefin polymer and having a lower melting point than the high melting point resin. These composite fibers are aligned in parallel and covered with rubber to form a composite preparation step for preparing a sheet-like rubber-fiber composite, and the obtained rubber-fiber composite is used in the longitudinal direction of the composite fiber. Cutting step to obtain a composite strip by cutting perpendicularly to the surface, and preparing the tread material to obtain a sheet-like tread material by aligning the obtained composite strip so that the fiber cross section of the composite fiber is exposed And a process.

  In the method for producing a tread material of the present invention, a sheet-like rubber-fiber composite having a thickness of 0.8 to 1.5 mm is produced in the composite production step, and the rubber-fiber obtained in the cutting step is produced. It is preferable to cut the composite at intervals of 5 to 10 mm.

  The tire manufacturing method of the present invention includes a sticking step of sticking the tread material obtained by the above tread material manufacturing method to a vulcanized or unvulcanized tire intermediate, and a tire to which the tread material is attached. And a vulcanization step of vulcanizing the intermediate.

  ADVANTAGE OF THE INVENTION According to this invention, it became possible to implement | achieve the pneumatic tire which improved the performance on snow, the manufacturing method of the tread material used for it, and the manufacturing method of a tire.

It is a width direction sectional view showing an example of the pneumatic tire of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view in the width direction showing an example of the pneumatic tire of the present invention. The illustrated tire of the present invention is a block in which a plurality of blocks are defined on a tread tread surface portion by a plurality of circumferential grooves 11 extending in the tire circumferential direction and a plurality of lateral grooves (not illustrated) extending in the tire width direction. It has a pattern. Each block is usually divided into a plurality of small blocks by a sipe extending in a zigzag shape or a wave shape in the tire width direction. In the present invention, the core sheath is provided for each small block divided by the sipe. Fiber is placed.

  In the tire of the present invention, a predetermined core-sheath type composite fiber is embedded in at least a part of the tread block constituting the block pattern, and the longitudinal direction of the composite fiber is substantially in the tire radial direction. It is characterized in that it is oriented. By embedding a predetermined core-sheath type composite fiber in the tread block substantially in the radial direction of the tire, it is possible to increase the coefficient of friction on the icy and snowy road surface and realize a tire with improved performance on snow. became. Here, in the present invention, the substantially tire radial direction means a tire radial direction or a direction within 20 ° from the tire radial direction.

  That is, in the present invention, when considering the friction between snow and rubber, the tread block is not made to have a uniform rubber surface, but the fibers having the core-sheath structure are arranged in the tire radial direction for each small block. Place at. As a result, the hard resin of the core-sheath fiber becomes convex in the rubber matrix, and the contact pressure acts in the fiber axis direction of the core-sheath fiber, so that the core-sheath fiber bites into the snow surface and improves the coefficient of friction. Thus, it is possible to increase the force due to wear caused by scratching or digging the snow surface, and as a result, the wear characteristics on snow can be improved. For example, even if the particles are embedded in rubber and exposed on the tread surface, the particles do not provide a friction improving effect because they are sunk into the rubber by ground pressure at the time of ground contact, but the core sheath according to the present invention Since the fibers are high in hardness, it is considered that at the time of ground contact, the low hardness rubber is recessed and the core-sheath fibers bite into the snow surface, transmitting pressure in the fiber axis direction and catching the snow surface to dig up. In addition, the resin constituting the sheath portion of the core sheath can be improved in wear resistance of the tread rubber during running by using a resin that has good fusion with rubber during vulcanization.

  When the tire with sipe rolls on the surface of the snow surface, a water film is generated on the tire surface when the block contacts the road surface and moves from the stepping side to the kicking side. When a part of this water flows into the sipe, the water film between the tire and the road surface is removed, and slipping of the tire is suppressed. This is a method of improving friction characteristics by removing water between the rubber and the road surface. In the present invention, as a method for further improving friction characteristics, a method is used in which core-sheath fibers are arranged in the tire radial direction and the friction is increased by surface destruction of the road surface. The core-sheath fiber according to the present invention is due to the fusion of the sheath resin to the rubber, so that the fiber falls off from the rubber at the time of wear and breaks (moge, Since there is little reduction in the frictional force caused by scratching or digging the fibers with the travel distance, the slipping of the block can be suppressed over a long period of time and the braking performance can be improved.

  The core-sheath type composite fiber used in the present invention comprises a high melting point resin (A) having a core part having a melting point of 150 ° C. or higher, and the sheath part includes an olefin polymer (D) and has a lower melting point than the high melting point resin. It consists of a resin material (B). In such a core-sheath type composite fiber, the resin material constituting the sheath part has a lower melting point than that of the core part. Therefore, when applied to the reinforcement of rubber articles, the resin material is thermally fused with the rubber by heating during vulcanization. It has the merit that it can be adhered directly by wearing. That is, the core-sheath fiber according to the present invention is embedded in the tread rubber. When the core-sheath fiber is combined with the rubber, the resorcin-formalin-latex as conventionally used for bonding a tire cord is used. Since it is not necessary to perform a dip treatment for attaching an adhesive composition such as an (RFL) adhesive, the bonding process can be simplified. In addition, when adhering organic fibers and rubber using an adhesive composition in reinforcing applications such as tires, in general, the organic fibers are covered with a fiber coating rubber (Skim Rubber) in order to ensure adhesion. However, the core-sheath fiber according to the present invention can obtain a strong adhesive force directly by tread rubber and heat fusion without using a fiber coating rubber.

  Further, according to the study by the present inventors, when the core-sheath fiber according to the present invention is vulcanized, the cut end surface of the core portion exposed before vulcanization is formed by the resin of the sheath portion at the cut end portion. It is known that a strong fusion between the resin and rubber in the sheath can be obtained even in this portion. This is thought to be due to the low melting point resin material forming the sheath flowing by heating during vulcanization and entering the gap between the cut end face of the core made of the high melting point resin and the rubber, Thereby, durability against strain after vulcanization can be further improved.

In the core-sheath type composite fiber according to the present invention, the melting point of the high melting point resin (A) forming the core is 150 ° C. or higher, preferably 160 ° C. or higher. When the melting point of the high melting point resin (A) is less than 150 ° C., when the core of the composite fiber is melted and melted during vulcanization of the rubber article, the foam in the rubber migrates due to migration of bubbles in the rubber. Thus, the resin of the present invention does not have an effect on snow due to the scratching effect by disposing the resin in the tire radial direction.
In the core-sheath type composite fiber according to the present invention, the resin material (B) forming the sheath part preferably has a lower limit of melting point of 80 ° C. or higher, more preferably 120 ° C. or higher, and still more preferably 135. The range is not lower than ° C. If the melting point of the resin material (B) is less than 80 ° C., sufficient adhesion can be obtained due to the formation of fine voids on the surface if the rubber does not adhere sufficiently to the surface of the resin material at the beginning of vulcanization. There is a risk of not being able to. Further, when the melting point of the resin material (B) is 120 ° C. or higher, at a temperature of 130 ° C. or higher as a vulcanization temperature that may be industrially used in a rubber composition containing sulfur and a vulcanization accelerator. It is preferable because the rubber and the low melting point resin material can be fused together and at the same time the vulcanization crosslinking reaction of the rubber composition can be performed. In addition, when the vulcanization temperature is set to 170 ° C. or more in order to shorten the vulcanization time industrially, when the melting point of the resin material (B) is less than 80 ° C., the viscosity of the molten resin becomes too low. The thermal fluidity increases during vulcanization, and a portion where the thickness of the sheath becomes thin due to the pressure during vulcanization occurs, and strain stress such as adhesion test concentrates on the portion where the sheath resin is thin. The melting point of the resin material (B) is more preferably 120 ° C. or higher because it may easily occur. On the other hand, if the upper limit of the melting point of the resin material (B) is less than 150 ° C., the vulcanization temperature is high at 175 ° C. or higher, and the compatibility with the rubber composition at the initial stage of vulcanization due to the thermal fluidity of the resin material. May be obtained. Moreover, it is preferable that the melting point of the resin material (B) is 145 ° C. or lower because the compatibility of the resin at the initial stage of vulcanization can be obtained at a general vulcanization temperature.

  The composite fiber for rubber reinforcement used in the present invention is a resin material (B) having a low melting point in the sheath, and can be directly adhered to the rubber by thermal fusion, and at the same time, the melting point of the core is 150 ° C. or higher. It is a composite fiber having a core-sheath structure, which is a high melting point resin (A). For example, when the monofilament cord has a single composition, the effects of the present invention cannot be obtained. In conventional monofilament cords made of polyolefin resin with a single composition, when the melting point is low, it melts and forms a melt by heat fusion with the rubber of the rubber article. If it becomes the melted body, it becomes impossible to improve the friction between the road surface and the snow surface. On the other hand, in the case of a high melting point where the resin does not become a melt even under heating, the weldability with the rubber becomes low. For this reason, in the monofilament cord of a single composition that is not a composite fiber having a core-sheath structure of the present invention, it is difficult to achieve both a function of improving the friction coefficient and the contradictory function of welding to rubber.

  In the rubber-fiber composite of the present invention, the high melting point resin (A) having a melting point of 150 ° C. or higher forming the core is not particularly limited, and specifically, for example, polypropylene (PP), polyethylene terephthalate (PET). , Polyester resins (Q) such as polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), polyamide resins (R) such as nylon 6, nylon 66, nylon 12, etc. Polyester resins and polyolefin resins (P) are preferred. Among polyester resins, polytrimethylene terephthalate (PTT) resins are particularly preferred.

  The polytrimethylene terephthalate resin forming the core of the present invention may be a polytrimethylene terephthalate homopolymer, copolymer, or a mixture with other miscible resins. Examples of the copolymerizable monomer of polytrimethylene terephthalate copolymer include acid components such as isophthalic acid, succinic acid and adipic acid, glycol components such as 1,4 butanediol and 1,6 hexanediol, and polytetraethylene. Examples include methylene glycol and polyoxymethylene glycol. The content of these monomers capable of copolymerization is not particularly limited, but is preferably 10% by mass or less because the bending rigidity of the copolymer is lowered. Examples of the polyester resin that can be mixed with the polytrimethylene terephthalate polymer include polyethylene terephthalate, polybutylene terephthalate, and the like, and may be mixed at 50% by mass or less.

  The intrinsic viscosity [η] of the polytrimethylene terephthalate is preferably 0.3 to 1.2, more preferably 0.6 to 1.1. When the intrinsic viscosity is less than 0.3, the strength and elongation of the fiber is low, and when it exceeds 1.2, the productivity becomes difficult due to yarn breakage caused by spinning. The intrinsic viscosity [η] can be measured with an Ostwald viscometer using an o-chlorophenol solution at 35 ° C. Moreover, it is preferable that the melting peak temperature calculated | required from DSC measured according to JIS-K-7121 of polytrimethylene terephthalate is 180 degreeC-240 degreeC. More preferably, it is 200 degreeC-235 degreeC. When the melting peak temperature is in the range of 180 to 240 ° C., the weather resistance is high, and the flexural modulus of the resulting composite fiber can be increased.

  Examples of the additive of the mixture comprising the polytrimethylene terephthalate resin include, for example, a plasticizer, a softening agent, an antistatic agent, an extender, a matting agent, a heat stabilizer, a light stabilizer, a flame retardant, an antibacterial agent, and a lubricant. Antioxidants, ultraviolet absorbers, crystal nucleating agents, and the like can be added as long as the effects of the present invention are not impaired.

  The polyolefin resin forming the core is preferably a high melting point polyolefin resin (P), particularly preferably a polypropylene resin, more preferably a crystalline homopolypropylene polymer, and more preferably an isotactic resin. Mention may be made of tic polypropylene.

In the core-sheath type composite fiber used in the present invention, the core part is composed of a high melting point resin (A) having a melting point of 150 ° C. or higher, and the core part can be melted even in the rubber vulcanization process. Absent. The inventor conducted vulcanization for 15 minutes at 195 ° C., which is higher than normal industrial vulcanization conditions, and observed the cross-section of the cord embedded in the rubber after vulcanization. The olefin polymer was melted and deformed in a circular cross section, but the high melting point resin (A) in the core part maintained the cross-sectional shape of the circular core part after core-sheath composite spinning, and was completely melted. In addition, the fiber breaking strength was maintained at 150 N / mm ² or more.

  Thus, if the melting point of the resin at the core of the cord is 150 ° C. or higher, the inventor will not melt and cut the core-sheath fiber even when subjected to heat treatment at 195 ° C. during vulcanization of the rubber article. Furthermore, it has been found that the effect of improving the friction coefficient in the present invention can be obtained. In addition, the reason why the material strength is maintained and heat resistance is maintained even at a processing temperature higher than the melting point inherent to the resin as described above is that when the cord is vulcanized at a constant length by being embedded in rubber, the JIS-K7121 etc. Unlike the method of measuring the melting point without restraining the resin shape, it is considered that the melting point is higher than the melting point inherent to the resin because it is a constant length restraint condition that does not shrink the fiber. Under such “constant length restraint” measurement conditions in which the fibers do not shrink, it is known that a high melting point may occur as a thermal phenomenon under the circumstances specific to fiber materials (2nd edition Fiber Handbook) (Published on March 25, 1994, edited by: Textile Society of Japan, published by Maruzen Co., Ltd., page 207, line 13). However, with a resin material such as the present invention, it is a cord material that is supposed to be melted at a temperature higher than the resin melting point according to the JIS method, and is examined at a temperature corresponding to the rubber vulcanization process, and by heat fusion with rubber. There has been no knowledge so far in which a resin material suitable for reinforcement for rubber articles that has been made to be in direct contact and at the same time has the rigidity of the resin in the core even under heating in the vulcanization process.

  As a preferred example of the present invention, when a polypropylene resin or a PPT resin is used as a resin having a melting point of 150 ° C. or more constituting the core portion, a known 66 nylon or polyethylene terephthalate conventionally used for tire cords. Although the modulus is lower than that of highly elastic cords such as aramid, the elastic modulus is intermediate between these conventional cords and rubber, so it is possible to place the cord at a position in the tire that was not possible with conventional tire cords. One of the features is that it can be done.

  Moreover, in this invention, the resin material (B) which comprises a sheath part contains an olefin type polymer (D), and melting | fusing point is lower than high melting point resin (A). The olefin polymer (D) is an olefin polymer containing a monomer of propylene-α olefin copolymer (H), propylene-nonconjugated diene copolymer (I), unsaturated carboxylic acid or anhydride thereof. It is preferable to comprise at least one component selected from the group consisting of an ionomer (J) having a degree of neutralization with a metal salt of the copolymer of 20% or more, and an olefin homopolymer (K).

  In the propylene-α-olefin copolymer (H) according to the present invention, a known α-olefin monomer can be used as a comonomer copolymerized with propylene. Moreover, the monomer used as a comonomer is not restricted to 1 type, The multi-component copolymer using two or more types of monomers like a terpolymer is also contained as a preferable thing. In addition, within the range in which the intended effect of the present invention can be obtained, other monomers that can be copolymerized with polypropylene can be included, for example, in a range of 5 mol% or less. The polymer contained is also referred to as a propylene-α-olefin random copolymer (H). Preferably, a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, a butene-propylene random copolymer, or the like can be used.

α-olefins having 2 or 4 to 20 carbon atoms, specifically, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene Examples include linear or branched α-olefins such as -1,4-methyl-hexene-1,4,4-dimethylpentene-1, and cyclic olefins such as cyclopentene, cyclohexene, and cycloheptene. These α-olefins may be used alone or in combination of two or more.
Among these, ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene are preferable, and ethylene and 1-butene are particularly preferable.

  Moreover, as a propylene content in the said propylene-alpha olefin type random copolymer (H), Preferably it is 20-99.7 mol%, More preferably, it is 75-99.5 mol%, More preferably, it is 95-99.3. Mol%. If the propylene content is less than 20 mol%, the impact strength may be insufficient due to the formation of a polyethylene crystal component. In general, a propylene content of 75 mol% or more is preferable because spinnability is improved. Further, when the propylene content is 99.7 mol% or less, the randomness of the molecular chain increases due to addition polymerization of other monomers such as ethylene copolymerized with polypropylene, and the cord becomes easy to be thermally fused. Furthermore, the ethylene content is preferably 0.3 mol% to 80 mol%. When the ethylene content exceeds 80 mol%, the fusion resistance between the sheath portion and the adherend rubber is not preferable because the resistance to fracture of the sheath portion is not sufficient, and cracks are easily generated in the sheath portion, which makes it easy to break. . Further, when the ethylene content is 5% or less, the fusion property when the sheath resins come into contact with each other during spinning becomes small, and the spinnability becomes preferable. Further, if the ethylene content is less than 0.3 mol%, the polymer consisting of polypropylene has less disorder of molecular chain orientation due to addition polymerization of the ethylene monomer, and as a result, the crystallinity becomes high. The heat-fusibility of the resin in the sheath portion is reduced.

  The propylene-α-olefin copolymer (H) is preferably a random copolymer in which the block amount in the NMR measurement of the repeating unit of the same vinyl compound portion is 20% or less of the wholly aromatic vinyl compound portion. . The reason why random copolymerization is preferred is that when the propylene-α-olefin copolymer (H) has low crystallinity and is less oriented, butadiene, natural rubber, SBR, etc., which are rubber components with low orientation, are used for the rubber to be adhered. This is because the rubber composition is preferable because it is easy to obtain fusion properties due to the compatibility of molecular chains during heating.

  In the examination of the present invention, the propylene-α-olefin copolymer (H) is an olefin containing a propylene-based copolymer (I) containing propylene and a non-conjugated diene, an unsaturated carboxylic acid or an anhydride monomer thereof. It can be used in combination with one or more olefinic polymers such as ionomers (J) and olefinic homopolymers (K) having a degree of neutralization with a metal salt of the copolymer of 20% or more.

  The reason why the propylene-α-olefin copolymer (H) is used is that the propylene-containing polymer is an olefin polymer having a melting point lower than the melting point of 165 ° C. of the propylene homopolymer by containing the α-olefin in the comonomer. When the melting point is about 90 ° C. to 140 ° C., the core resin specified in the present invention has a melting point suitable for the sheath resin having a melting point of 150 ° C. or higher and lower than that of the core resin. Further, by including other comonomer in the propylene molecular chain, the crystallinity and orientation are lowered, and the heat-fusibility is improved. Further, compared to the propylene-diene copolymer (I), the adhesiveness is low because it does not contain a diene monomer, and the processed cords adhere to each other even when pressure is applied by overlapping them. The blocking property is relatively small with a heat-fusible resin, and is easy to control so as to achieve an appropriate spinning workability.

  Therefore, in the present invention, an olefin polymer resin is used as a matrix component, and the propylene copolymer (I) containing propylene and a non-conjugated diene having good adhesion to a rubber to be adhered but having a rubbery adhesive property. The degree of neutralization with a metal salt of an olefin copolymer containing an unsaturated carboxylic acid or its anhydride monomer having good compatibility with the core resin or the like but having a low melting point is 20 % Of the ionomer (J) and the olefin homopolymer (K) are used in combination, and the single olefin polymer is preferable because both contradictory physical properties can be achieved.

In addition, it is preferable that MFR190 measured according to JIS-K-7210 of the said propylene- alpha olefin type copolymer (H) is 3-100 g / 10min. A more preferred MFR 190 is 5 to 40 g / 10 min, even more preferably 5 to 30 g / 10 min. When the MFR 190 exceeds 100 g / 10 min, the fluidity of the sheath resin is too high, and since the MFR 190 is 3 g / 10 min or longer, the workability during the spinning process and the stretching process is good, and a uniform rubber reinforcing fiber Can be easily obtained.
The melting point of the propylene-α-olefin copolymer (H) measured according to JIS-K-7121 is preferably equal to or lower than the melting point of the high melting point resin (A) in the core. The lower limit of the melting point is not particularly limited, but is preferably 90 ° C or higher, particularly preferably 110 ° C or higher, and further 120 ° C. When using a resin having a good melting point with a melting point of 90 ° C. or less for the resin material (B) of the sheath, it is not used as a single resin, but in combination with an olefin polymer having a melting point higher than that, When the content is mixed at 25% by mass or less, for example, bubbles are less likely to enter the resin material (B) of the sheath during vulcanization. This is more preferable because the decrease in fatigue resistance is less.

The propylene-nonconjugated diene copolymer (I) according to the present invention can be obtained by polymerizing propylene and a known nonconjugated diene. The monomers used as these comonomers are not limited to one type, and multi-component copolymers using two or more types of monomers such as terpolymers are also included as preferable ones. In addition, within the range in which the intended effect of the present invention can be obtained, other monomers that can be copolymerized with polypropylene can be included, for example, in a range of 5 mol% or less, and a polymer containing these monomers. Is also referred to as propylene-nonconjugated diene copolymer (I).
Preferable examples include 1-butene-propylene copolymer.

Non-conjugated diene monomers include 5-ethylidene-2-norbornene, dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, 5-vinyl-2-norbornene, 4,8-dimethyl-1,4,8- Examples include decatriene and 4-ethylidene-8-methyl-1,7-nonadiene.
In particular, when a non-conjugated diene is introduced into ethylene and propylene as a third component, if an ethylene-propylene-diene copolymer (EPDM) component is included, it is due to sulfur as well as adhesion at the interface with the rubber to be adhered. Since the component which has co-vulcanizability is contained, it is preferable.

  Moreover, as a propylene content in the said propylene-nonconjugated diene copolymer, Preferably it is 20-99.7 mol%, More preferably, it is 30-75 mol%, More preferably, it is 40-60 mol%. When the propylene content is less than 20 mol%, a blocking phenomenon in which the sheath resins of the cords stick to each other after spinning tends to occur. On the other hand, when the amount is less than 30 mol%, the surface of the sheath resin is likely to be disturbed due to surface friction during spinning. On the other hand, if the propylene content exceeds 99.7 mol%, the amount of other monomers copolymerized with polypropylene will decrease, the randomness of the molecular chain will decrease, and the crystallinity of polypropylene will increase. Is a low code. On the other hand, when the content of the non-conjugated diene monomer exceeds 80 mol%, the fracture resistance of the sheath portion is not sufficient in the fusion between the sheath portion and the adherend rubber, and cracks are not generated in the sheath portion. It is not preferable because it easily occurs and breaks. On the other hand, when the ethylene content is less than 0.3 mol%, the compatibility with the adherend rubber and the improvement of adhesion by co-vulcanization are reduced.

In the study of the present invention, the propylene-nonconjugated diene copolymer (I) includes another propylene-α-olefin copolymer (H), an unsaturated carboxylic acid or an anhydride monomer thereof. It is preferable to use in combination with an ionomer (J) having a degree of neutralization by the metal salt of the olefin copolymer of 20% or more.
The reason for this is that the olefin copolymer (I) in which the sheath resin contains a conjugated diene such as EPDM contains a diene capable of sulfur crosslinking, thereby improving the adhesion. However, because of the properties derived from amorphous and soft polymers, which are characteristic of rubber-like polymers, it is difficult to spin when used as a fiber material because it stretches amorphously due to spinning stress and breaks the yarn. Although it is a resin, if it is used for the sheath portion of the core-sheath fiber, the resin in the core portion bears the spinning stress, and therefore spinning is possible if it adheres to the surface of the sheath portion. However, with regard to the cord surface properties during spinning, if the amount of rubbery polymer components increases, for example, if the spinning speed is slowed so that the surface is not roughened by spinning, the productivity during processing will be reduced and spinning will be performed. When the cords are stacked and pressure is applied, a blocking phenomenon occurs where the cords stick to each other. For example, after winding the bobbin, the cords may stick to each other or the cord surface may be damaged by unwinding.

  Therefore, in order to achieve both the spinnability of the cord and the anti-blocking manufacturability without improving the adhesiveness while improving the adhesiveness with the rubber, the resin component constituting the resin material (B) is one of the preferable methods. In addition to the propylene-nonconjugated diene copolymer (I), the resinous rubber-like elasticity is low, the olefin random copolymer (H), unsaturated carboxylic acid or its anhydride monomer. The ionomer (J) having a degree of neutralization by the metal salt of the olefin copolymer of 20% or more, or the resin of the olefin homopolymer (K) as a main component of the sheath portion as a resin matrix phase, and a diene component The olefin random copolymer (I) to be contained can be dispersed and used in combination.

  In addition, it is preferable that MFR190 measured according to JIS-K-7210 of the said propylene-nonconjugated diene type copolymer (I) is 2-40 g / 10min. A more preferred MFR 190 is 3 to 30 g / 10 min. When the MFR190 is 100 g / 10 or more, the fluidity of the sheath resin is too high, and since the MFR190 is 3 g / 10 min or more, the workability in the spinning process and the drawing process is good and uniform rubber reinforcing fiber Can be easily obtained. In addition, the melting point of the propylene-nonconjugated diene copolymer (I) measured according to JIS-K7121 (not applying tension or the like to the resin) is preferably equal to or lower than the melting point of the core resin (A). The lower limit of the melting point is not particularly limited, but is preferably 90 ° C or higher, particularly preferably 110 ° C or higher, and further 120 ° C.

The ionomer (J) having a neutralization degree of 20% or more with a metal salt of an olefin copolymer containing an unsaturated carboxylic acid or anhydride monomer according to the present invention is an ethylene-ethylene unsaturated carboxylic acid. It is preferably a polymer ionomer or an ionomer of an unsaturated carboxylic acid polymer of polyolefin. Among these, an ethylene-ethylenically unsaturated carboxylic acid copolymer can be obtained by polymerizing ethylene and a known ethylenically unsaturated carboxylic acid. The monomers used as these comonomers are not limited to one type, and multi-component copolymers using two or more types of monomers such as terpolymers are also included as preferable ones. In addition, within the range in which the intended effect of the present invention can be obtained, other monomers that can be copolymerized with polypropylene can be included in a range of, for example, 5 mol% or less, and the polymer containing these monomers is included. Is also said ionomer (J).
As a preferable example, an ethylene-methacrylic acid copolymer is preferable because a core-sheath composite fiber excellent in fusion property can be obtained.

Ethylenically unsaturated carboxylic acid monomers include vinyl esters such as vinyl acetate and vinyl propionate, acrylic esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, nbutyl acrylate, isobutyl acrylate, and isooctyl acrylate. Examples include acid esters, methacrylic acid esters such as methyl methacrylate and isobutyl methacrylate, and maleic acid esters such as dimethyl maleate and diethyl maleate.
Among these, methyl acrylate and methyl methacrylate are preferable.

  In addition, the monomer content of the ethylenically unsaturated carboxylic acid in the ethylene-ethylenically unsaturated carboxylic acid copolymer is preferably 0.5 to 35% by mass, more preferably 1 to 25% by mass, and still more preferably 2 -10 mass%. When the ethylenically unsaturated carboxylic acid content is less than 0.5% by mass, the compatibility between the olefin polymer and the core resin by the ethylene-ethylenically unsaturated carboxylic acid copolymer is improved. The effect becomes slight and the fusion property is lowered. On the other hand, when the propylene content exceeds 35% by mass, the polarity of the polymer of the olefin polymer becomes large, and the rubber composition of the adherent rubber becomes a polymer such as butadiene rubber or styrene rubber. In the case of nonpolarity, the difference in polarity is made and compatibility is lowered, so that the fusibility is lowered. Further, when the ethylene monomer is 99.5% by mass or more, the compatibility between the polypropylene and the ethylene polymer is not good, so that the fusibility is lowered, and when the ethylene content is 75% by mass or more. Since the resin made of ethylene has a low melting point, the high-temperature adhesiveness of the rubber-fiber composite at high temperatures is lowered, which may be undesirable.

In the present invention, an ethylene-ethylenically unsaturated carboxylic acid copolymer is used as an ionomer (J) having a neutralization degree of 20% or more with a metal salt of an olefin copolymer containing an unsaturated carboxylic acid or anhydride monomer. An ionomer obtained by neutralizing a part or all of the carboxyl groups with a metal, such as a polymer or a modified product of an polyolefin with an unsaturated carboxylic acid, can be used. Examples of the metal species constituting the ionomer include monovalent metals such as lithium, sodium, and potassium, and polyvalent metals such as magnesium, calcium, zinc, copper, cobalt, manganese, lead, and iron. Of these, sodium or zinc is preferable.
In the study of the present invention, in the use of the sheath resin material (B), an ionomer obtained by neutralizing 20% or more of an ethylene-ethylenically unsaturated carboxylic acid copolymer with a metal is preferable. The reason for this is that when the sheath resin material (B) becomes a proton H ⁺ donating acidic atmosphere due to a functional group such as carboxylic acid, sulfur migrates from the rubber to the sheath resin material (B) and is activated. However, since the proton H ⁺ reduces the polyvulcanized product, the polyvulcanized product cannot be formed, so that an environment in which the adhesion to the adherend rubber cannot be strengthened is likely to occur. For this reason, it is preferable that the unsaturated carboxylic acid copolymer (J) is an ionomer, and the sheath of the rubber reinforcing fiber is maintained so that the composition of the resin material (B) of the sheath maintains a Lewis basic atmosphere. In the resin material (B), it is necessary to limit the content or to add a vulcanization accelerator or the like in the present invention, but such knowledge has not been conventionally known. The neutralization degree between the carboxylic acid and the metal salt is preferably 100% or more. However, since the carboxylic acid is a weak acid, the effect of the present invention can be obtained even when the neutralization degree of the carboxylic acid is 20%. In addition, the neutralization degree of preferable carboxylic acid is 20%-250%, More preferably, it is 70%-150%.

In addition, the neutralization degree in this invention is defined by a following formula.
Degree of neutralization (%) = 100 × [(number of moles of cation component of resin component × valence of cation component) + (number of moles of metal component of basic inorganic metal compound × valence of metal component)] / [(Mole number of carboxyl group of resin component)
The amount of the cation component and the amount of the anion component can be determined by a method for examining the degree of neutralization of the ionomer such as neutralization titration.

  The degree of neutralization with a metal salt of an olefin copolymer containing an unsaturated carboxylic acid or its anhydride monomer is 20% according to known literatures such as JP-A Nos. 05-163618 and 07-238420. When the above ionomer (J) is added, compatibility between the core-sheath fibers of the core-sheath fibers is improved. For example, the core part is a polyester or polyamide resin material, and the sheath part is an olefin polymer resin material. Thus, it is known that the adhesion at the interface between the core and sheath can be improved. In the present invention, the ionomer (J) having a neutralization degree of 20% or more with a metal salt of an olefin copolymer containing an unsaturated carboxylic acid or anhydride monomer is an olefin copolymer composition ( When X) is 100 parts by mass, it is preferably 2 to 40 parts by mass, more preferably 2 to 25 parts by mass, and still more preferably 3 to 15 parts by mass. When the ionomer (J) having a degree of neutralization with a metal salt of an olefin copolymer containing an unsaturated carboxylic acid or its anhydride monomer is less than 2 parts by mass, the core sheath of the core-sheath fiber The compatibility is not improved, and the adhesion is slightly improved. On the other hand, if it exceeds 40 parts by mass, bubbles may enter the resin body during vulcanization to form cavities. In this way, when bubbles are generated at a position where there is a step difference in material rigidity between the rubber and the resin of the rubber reinforcing fiber, fatigue due to repeated loads such as when running tends to cause fracture that becomes the core of cracking, Adhesiveness with rubber decreased.

  The ionomer (J) having a neutralization degree of 20% or more by the metal salt of the olefin copolymer containing the unsaturated carboxylic acid or its anhydride monomer is composed of an aliphatic polyester and a polyolefin used for the sheath. Although it is not particularly limited as long as it can be melt-spun together with the composition, it is usually preferable that the MFR 190 measured according to JIS-K-7210 is 0.01 to 200 g / 10 min. A more preferred MFR 190 is in the range of 0.1-100 g / 10 min, even more preferably in the range of 3-60 g / 10 min. In addition, the melting point of the ethylene-ethylenically unsaturated carboxylic acid copolymer or its ionomer measured according to JIS-K7121 is preferably equal to or lower than the melting point of the core resin (A). In addition, although the minimum of melting | fusing point is not restrict | limited in particular, 90 degreeC or more is preferable, Especially preferably, it is 110 degreeC or more, Furthermore, it is 120 degreeC.

  As the olefin homopolymer (K) according to the present invention, an ethylene homopolymer such as high density polyethylene, low density polyethylene or linear low density polyethylene, isotactic polypropylene, atactic polypropylene, or Propylene homopolymers such as syndiotactic polypropylene, 4-methylpentene-1 homopolymers, α-olefin homopolymers such as 1-butene homopolymers (K1), or polybutadiene, polyisoprene, polynorbornene As a suitable example, polyolefin rubber (K2) having an unsaturated hydrocarbon bond in the main chain in the category of JIS-K6397 is mentioned. In the present invention, an α-olefin homopolymer (K1) is particularly preferred in the present invention, and is a high-density polyethylene or a polypropylene (for example, Idemitsu) having a low stereoregularity controlled by a catalyst in propylene polymerization and a low melting point. Kosan Co., Ltd. El Modu, etc.) can be used. These are not used alone but can be used as a mixture.

  In general, the α-olefin homopolymer (K1) generally exhibits properties of a thermoplastic material having high crystallinity such as polyethylene and polypropylene. Conventionally, in core-sheath olefin fibers, various studies have been conducted on blending such α-olefin homopolymers with other olefin polymers. In the fiber for reinforcing rubber of the present invention, the α-olefin homopolymer (K1) has low rubber-like elasticity and good moldability into a fiber shape when the resin is spun. Therefore, the resin of the resin material (B) of the sheath portion Propylene-α-olefin copolymer (H), propylene-containing copolymer (I) containing propylene and non-conjugated diene, unsaturated carboxylic acid, Mixing with polymers such as ionomer (J) having a neutralization degree of 20% or more of the olefin copolymer containing the anhydride monomer with a metal salt, the moldability of the resin into a yarn shape during spinning While ensuring the above, it is possible to achieve both improvement in adhesion suitable for rubber reinforcement by mixing with other polymers.

Examples of the polyethylene include linear low-density polyethylene, high-density polyethylene, etc., and α-olefin such as 1-butene is partially copolymerized to have a short branched structure to lower the crystallinity intentionally. A polymer is mentioned.
Examples of the polypropylene include stereotactic polypropylene such as isotactic, syndiotactic, and atactic, but the polypropylene used for the resin material (B) of the sheath is compatible with the rubber to be adhered. Especially preferred is polypropylene with good steric orientation. Examples of such polypropylene include propylene having low crystallinity due to a single-site catalyst such as a product El Modu made by Idemitsu Kosan Co., Ltd. Use of such propylene for the sheath resin (B) is preferable when polypropylene is used for the core resin because the bond between the core and the sheath can be strengthened.
In addition to polyethylene and polypropylene, poly 1-butene also has high melt miscibility with other olefin components such as polypropylene and is a preferred example.

  As said alpha olefin homopolymer, it is preferable that MFR190 measured according to JIS-K-7210 is 0.01-200 g / 10min. A more preferred MFR 190 is in the range of 0.1-100 g / 10 min, even more preferably in the range of 3-60 g / 10 min. Moreover, it is preferable that melting | fusing point is below the melting | fusing point of core part resin (A). The lower limit of the melting point is not particularly limited, but is preferably 90 ° C. or higher, particularly preferably 110 ° C. or higher, and further 120 ° C.

  In addition, as the polyolefin rubber (K2) having an unsaturated hydrocarbon bond in the main chain in the olefin homopolymer (K), a polymer obtained by polymerizing a low-polarity monomer such as polybutadiene, polyisoprene, or polynorbornene is used. A preferred example is given. When the sheath resin (B) contains a rubber component having low crystallinity as described above, it is easy to obtain adhesion with rubber components such as natural rubber, polybutadiene, and SBR contained in the adherend rubber. Due to the rubbery properties such as being easily stretched, the spinnability and blocking resistance at the time of spinning are reduced, so it is used in combination with a polymer that has a good thread-formation property at the time of spinning rather than being used alone for the sheath resin. And is preferably used as an olefin polymer.

  Examples of the method for producing these olefin polymers include slurry polymerization, gas phase polymerization or liquid phase bulk polymerization using an olefin polymerization catalyst such as a Ziegler catalyst and a metallocene catalyst. Either method of continuous polymerization can be employed.

  In the present invention, the olefin polymer contained in the resin material (B) of the sheath part is a propylene-α olefin copolymer (H), a propylene-nonconjugated diene copolymer (I), an unsaturated carboxylic acid or Contains one or more selected from ionomers (J) and olefin homopolymers (K) having a neutralization degree of 20% or more by the metal salt of the olefin copolymer containing the anhydride monomer. The resin material (B) is 20 to 98 parts by mass of the olefin random copolymer (H) with respect to 100 parts by mass of the olefin polymer, and a propylene-conjugated diene copolymer ( 2) to 80 parts by mass of I), 2 to 35 parts by mass of an ionomer (J) having a neutralization degree of 20% or more with a metal salt of an olefin copolymer containing an unsaturated carboxylic acid or anhydride monomer The above It is preferable that olefin based homopolymer (K) comprises one or more in the range of 2 to 75 parts by weight.

  Further, in the present invention, the resin material (B) constituting the sheath part is a single molecular chain (hereinafter also referred to as “styrene block”) in which a styrene monomer is mainly continuously arranged as a compatibilizing agent. It is preferable to contain the styrene-type elastomer (L) containing). By mix | blending a styrene-type elastomer (L), compatibility with a resin material (B) and rubber | gum can be improved and adhesiveness can be improved.

That is, the low melting point resin material is mainly composed of a polyolefin resin such as a homopolymer such as polyethylene or polypropylene, an ethylene-propylene random copolymer, or the like, which becomes a resin composition having a melting point range specified in the present invention. Although it is a composition, it is known that the resin composition which mixed these generally becomes a phase-separated structure. Therefore, by adding the styrene elastomer (L) as a block copolymer composed of soft segments and hard segments, compatibilization of the phase interface can be promoted. Styrene-based elastomers include adhesion at the interface between the high melting point resin as the core component and the resin material as the sheath component, styrene-butadiene rubber (SBR), butadiene rubber (BR) contained in the sheath component and the adherend rubber, It is preferable to have a segment having an interaction with a molecular structure such as butyl rubber (IIR) or natural rubber (IR) having a polyisoprene structure because adhesion with the adherend rubber is improved. In particular, when the adherent rubber contains styrene-butadiene rubber (SBR), if the sheath component contains a styrene-based block copolymer containing a styrene component, compatibility with the interface with the adherent rubber in fusion bonding Is preferable, and the adhesive strength is improved.
The block copolymer in the present invention is a polymer composed of two or more types of monomer units, and forms a single molecular chain (block) in which at least one monomer unit is mainly arranged long and continuously. Meaning a copolymer. The styrenic block copolymer means a block copolymer containing a block in which styrene monomers are mainly linked and arranged long.

  As the styrene elastomer (L), specifically, a styrene block copolymer can be used, and one containing styrene and a conjugated diolefin compound is preferable. More specifically, as the styrene elastomer (L), a styrene block copolymer, a hydrogenated product thereof, or a modified product thereof is used, and a styrene-butadiene polymer, polystyrene-poly (ethylene / propylene) system is used. Examples thereof include a block copolymer, a styrene-isoprene block polymer, and a polymer obtained by hydrogenation of a double bond of a block copolymer of styrene and butadiene to be completely hydrogenated or partially hydrogenated. The styrene elastomer may be modified with maleic acid.

  Specific examples of the styrene-butadiene polymer include styrene-butadiene polymer (SBS), styrene-ethylene-butadiene copolymer (SEB), styrene-ethylene-butadiene-styrene copolymer (SEBS), and styrene-butadiene. -Butylene-styrene copolymer (SBBS), partially hydrogenated styrene-isoprene-butadiene-styrene copolymer, and the like. Polystyrene-poly (ethylene / propylene) block polymers include polystyrene-poly (ethylene / propylene) block copolymers (SEP), polystyrene-poly (ethylene / propylene) block-polystyrene (SEPS), polystyrene-poly ( Examples include ethylene / butylene) block-polystyrene (SEBS) and polystyrene-poly (ethylene-ethylene / propylene) block-polystyrene (SEEPS). Examples of the styrene-isoprene block polymer include polystyrene-polyisoprene-polystyrene copolymer (SIS) or Asahi Kasei Chemicals Co., Ltd. O. E. And a hydrogenated product of a block copolymer having a styrene block at both ends and a block composed of a styrene block and a random copolymer of butadiene in the main chain. In the present invention, among these, styrene-butadiene polymer, styrene-butadiene-butylene-styrene copolymer and styrene-ethylene-butadiene-styrene copolymer are particularly preferred from the viewpoint of adhesion to rubber and compatibility. Can be preferably used. In the case where the rubber to be adhered is a composition comprising a rubber having a low polarity such as BR, SBR, and NR, the styrene block copolymer or its hydrogenated product does not have a functional group having a strong polarity due to modification or the like. However, since compatibility becomes high, it is preferable.

  Modification in the case where a polar group is further introduced into the hydrogenated product of the styrene-butadiene polymer can be performed, for example, by introducing an amino group, a carboxyl group or an acid anhydride group into the hydrogenated product. Although not particularly limited, in the present invention, as the modification for introducing a polar group, 3-lithio-1- [N, N-bis (trimethylsilyl)] aminopropane, 2-lithio-1- [N, N-bis] Modification by introduction of an unsaturated amino group, such as (trimethylsilyl)] aminoethane, 3-lithio-2,2-dimethyl-1- [N, N-bis (trimethylsilyl)] aminopropane, can be mentioned as a preferred example. .

  The content of the styrene-based elastomer (L) is 0.1 to 30 parts by mass, particularly 1 to 30 parts by mass with respect to 100 parts by mass of the total amount of resin components such as olefin polymers contained in the resin material constituting the sheath. The amount can be 15 parts by mass. By making content of a styrene-type elastomer (L) into the said range, the compatibility improvement effect of a resin material and rubber | gum can be acquired favorably.

  Moreover, in this invention, it is preferable that the resin material which comprises a sheath part contains a vulcanization accelerator (M) further. By containing the vulcanization accelerator (M), an interaction at the rubber interface can be obtained due to the effect that the sulfur content in the adherend rubber becomes a transition state between the vulcanization accelerator and the polyvulcanizate, and rubber is obtained. The surface distribution of the sheath resin from inside or the amount of sulfur transferred to the inside of the resin increases. Further, when a conjugated diene capable of sulfur vulcanization is included in the component of the sheath resin, the co-reaction with the adherend rubber is promoted, and the adhesion between the resin material and the rubber can be further improved.

  Examples of the vulcanization accelerator (M) include basic silica, primary, secondary, and tertiary amines, organic acid salts of these amines or their adducts and salts thereof, aldehyde ammonia type accelerators, and aldehyde amine type. Lewis basic compounds such as accelerators, and other vulcanization accelerators include the sulfur atom of the vulcanization accelerator, when it approaches the cyclic sulfur in the system, it opens to a transition state and becomes active. Sulfur accelerators--Sulfenamide accelerators, guanidine accelerators, thiazole accelerators, thiuram accelerators, dithiocarbamic acid accelerators, etc., which can activate sulfur by generating polyvulcanizates, etc. .

  The Lewis basic compound is not particularly limited as long as it is a Lewis base in the definition of Lewis' acid base and can provide an electron pair. These include nitrogen-containing compounds having a lone electron pair on the nitrogen atom, and specifically, basic vulcanization accelerators known in the rubber industry can be used.

Specific examples of the basic compound include aliphatic primary, secondary or tertiary amines having 5 to 20 carbon atoms, such as n-hexylamine and alkylamines such as octylamine, and dibutylamine. Acyclic monoamines and derivatives thereof such as dialkylamines such as di (2-ethylhexyl) amine, trialkylamines such as tributylamine and trioctylamine, and salts thereof,
Acyclic polyamines and derivatives thereof such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, polyethyleneimine, and salts thereof;
Alicyclic polyamines such as cyclohexylamine and derivatives thereof, and salts thereof,
Hexamethylenetetramine and other alicyclic polyamines and derivatives thereof, and salts thereof, anilines, alkylanilines, diphenylanilines, 1-naphthylanilines, N-phenyl-1-naphthylamines and the like, and aromatic monoamines and derivatives thereof salt,
Examples thereof include aromatic polyamine compounds such as phenylenediamine, diaminotoluene, N-alkylphenylenediamine, benzidine, guanidines, n-butyraldehyde aniline, and derivatives thereof.
Examples of guanidines include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, dicatechol borate di-o-tolylguanidine salt, 1,3-di- Examples include o-cumenyl guanidine, 1,3-di-o-biphenyl guanidine, 1,3-di-o-cumenyl-2-propionyl guanidine, and the like. Of these, 1,3-diphenylguanidine is preferable because of its high reactivity.

  Examples of the organic acid that forms a salt with the amine include carboxylic acid, carbamic acid, 2-mercaptobenzothiazole, and dithiophosphoric acid. Examples of the substance that forms an adduct with the amine include alcohols and oximes. Specific examples of the organic acid salt or adduct of amine include n-butylamine / acetate, dibutylamine / oleate, hexamethylenediamine / carbamate, dicyclohexylamine salt of 2-mercaptobenzothiazole, and the like.

In addition, for example, nitrogen-containing heterocyclic compounds that become basic by having a lone pair on the nitrogen atom include monocyclic inclusions such as pyrazole, imidazole, pyrazoline, imidazoline, pyridine, pyrazine, pyrimidine, and triazine. Nitrogen compounds and derivatives thereof,
Examples thereof include bicyclic nitrogen-containing compounds such as benzimidazole, purine, quinoline, peteridine, acridine, quinoxaline and phthalazine, and derivatives thereof.
In addition, examples of the heterocyclic compound having a heteroatom other than a nitrogen atom include heterocyclic compounds containing nitrogen and other heteroatoms such as oxazoline and thiazoline and derivatives thereof.

  Specific examples of the other vulcanization accelerators include known vulcanization accelerators such as thioureas, thiazoles, sulfenamides, thiurams, dithiocarbamic acids, and xanthogenic acids.

  Examples of thioureas include N, N′-diphenylthiourea, trimethylthiourea, N, N′-diethylthiourea, N, N′-dimethylthiourea, N, N′-dibutylthiourea, ethylenethiourea, N, N′— Diisopropylthiourea, N, N′-dicyclohexylthiourea, 1,3-di (o-tolyl) thiourea, 1,3-di (p-tolyl) thiourea, 1,1-diphenyl-2-thiourea, Examples include 2,5-dithiobiurea, guanylthiourea, 1- (1-naphthyl) -2-thiourea, 1-phenyl-2-thiourea, p-tolylthiourea, o-tolylthiourea and the like. Of these, N, N'-diethylthiourea, trimethylthiourea, N, N'-diphenylthiourea and N, N'-dimethylthiourea are preferred because of their high reactivity.

  Thiazoles include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2- (N, N-diethylthiocarbamoyl) Thio) benzothiazole, 2- (4′-morpholinodithio) benzothiazole, 4-methyl-2-mercaptobenzothiazole, di- (4-methyl-2-benzothiazolyl) disulfide, 5-chloro-2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium, 2-mercapto-6-nitrobenzothiazole, 2-mercapto-naphtho [1,2-d] thiazole, 2-mercapto-5-methoxybenzothiazole, 6-amino-2-mercaptobenzothiazole Etc. It is below. Among these, 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2- (4′-morpholinodithio) benzothiazole Is preferable because of its high reactivity. In addition, for example, di-2-benzothiazolyl disulfide and zinc salt of 2-mercaptobenzothiazole have high solubility even when added to a relatively non-polar polymer, and therefore, spinnability due to deterioration of surface properties due to precipitation or the like. This is a particularly preferable example because it is difficult for the lowering of the film to occur.

  Examples of the sulfenamides include N-cyclohexyl-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, N-methyl-2-benzothiazolylsulfenamide, N-ethyl-2-benzothiazolylsulfenamide, N-propyl-2-benzothiazolylsulfenamide Phenamide, N-butyl-2-benzothiazolylsulfenamide, N-pentyl-2-benzothiazolylsulfenamide, N-hexyl-2-benzothiazolylsulfenamide, N-pentyl-2-benzothia Zolylsulfenamide, N-octyl-2-benzothiazolylsulfur Enamide, N-2-ethylhexyl-2-benzothiazolylsulfenamide, N-decyl-2-benzothiazolylsulfenamide, N-dodecyl-2-benzothiazolylsulfenamide, N-stearyl-2-benzo Thiazolylsulfenamide, N, N-dimethyl-2-benzothiazolylsulfenamide, N, N-diethyl-2-benzothiazolylsulfenamide, N, N-dipropyl-2-benzothiazolylsulfenamide N, N-dibutyl-2-benzothiazolylsulfenamide, N, N-dipentyl-2-benzothiazolylsulfenamide, N, N-dihexyl-2-benzothiazolylsulfenamide, N, N- Dipentyl-2-benzothiazolylsulfenamide, N, N-dioctyl-2-benzothia Rylsulfenamide, N, N-di-2-ethylhexylbenzothiazolylsulfenamide, N-decyl-2-benzothiazolylsulfenamide, N, N-didodecyl-2-benzothiazolylsulfenamide, N , N-distearyl-2-benzothiazolylsulfenamide and the like. Among these, N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, and N-oxydiethylene-2-benzothiazolesulfenamide are highly reactive. Therefore, it is preferable. In addition, for example, N-cyclohexyl-2-benzothiazolylsulfenamide and N-oxydiethylene-2-benzothiazolylsulfenamide have high solubility even when added to a relatively nonpolar polymer, and therefore, precipitation, etc. This is a particularly preferred example because it is difficult for a decrease in spinnability and the like due to deterioration of the surface properties due to.

  Thiurams include tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrapropylthiuram disulfide, tetraisopropylthiuram disulfide, tetrabutylthiuram disulfide, tetrapentylthiuram disulfide, tetrahexylthiuram disulfide, tetraheptylthiuram disulfide, tetraoctylthiuram disulfide, tetra Nonyl thiuram disulfide, tetradecyl thiuram disulfide, tetradodecyl thiuram disulfide, tetrastearyl thiuram disulfide, tetrabenzyl thiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide, tetramethyl thiuram monosulfide, tetraethyl thiuram monosulfide, tetrapropyl thiura Monosulfide, tetraisopropylthiuram monosulfide, tetrabutylthiuram monosulfide, tetrapentylthiuram monosulfide, tetrahexylthiuram monosulfide, tetraheptylthiuram monosulfide, tetraoctylthiuram monosulfide, tetranonylthiuram monosulfide, tetradecylthiuram monosulfide Tetradodecyl thiuram monosulfide, tetrastearyl thiuram monosulfide, tetrabenzyl thiuram monosulfide, dipentamethylene thiuram tetrasulfide and the like. Of these, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, and tetrakis (2-ethylhexyl) thiuram disulfide are preferable because of their high reactivity. Further, when the alkyl group contained in the accelerator compound is large, in the case of a relatively non-polar polymer, the solubility tends to be high, and it is difficult to cause a decrease in spinnability due to deterioration of surface properties due to precipitation, Tetrabutyl thiuram disulfide or tetrakis (2-ethylhexyl) thiuram disulfide is a particularly preferred example.

Dithiocarbamates include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dipropyldithiocarbamate, zinc diisopropyldithiocarbamate, zinc dibutyldithiocarbamate, zinc dipentyldithiocarbamate, zinc dihexyldithiocarbamate, zinc diheptyldithiocarbamate, and dioctyldithiocarbamate. Zinc acid, zinc di (2-ethylhexyl) dithiocarbamate, zinc didecyldithiocarbamate, zinc diddecyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc dibenzyldithiocarbamate, Copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dipropyldithiocarbamate, Copper isopropyldithiocarbamate, copper dibutyldithiocarbamate, copper dipentyldithiocarbamate, copper dihexyldithiocarbamate, copper diheptyldithiocarbamate, copper dioctyldithiocarbamate, copper di (2-ethylhexyl) dithiocarbamate, copper didecyldithiocarbamate, didodecyldithiocarbamate Acid copper, copper N-pentamethylenedithiocarbamate, copper dibenzyldithiocarbamate, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, sodium dipropyldithiocarbamate, sodium diisopropyldithiocarbamate, sodium dibutyldithiocarbamate, sodium dipentyldithiocarbamate, dihexyldithiocarbamine Acid sodium, diheptyldithio Sodium carbamate, sodium dioctyl dithiocarbamate, sodium di (2-ethylhexyl) dithiocarbamate, sodium didecyldithiocarbamate, sodium didodecyldithiocarbamate, sodium N-pentamethylenedithiocarbamate, sodium dibenzyldithiocarbamate, second dimethyldithiocarbamate Iron, ferric diethyldithiocarbamate, ferric dipropyldithiocarbamate, ferric diisopropyldithiocarbamate, ferric dibutyldithiocarbamate, ferric dipentyldithiocarbamate, ferric dihexyldithiocarbamate, diheptyldithiocarbamate Diiron, ferric dioctyldithiocarbamate, ferric di (2-ethylhexyl) dithiocarbamate, didecyldi Examples thereof include ferric thiocarbamate, ferric didodecyldithiocarbamate, ferric N-pentamethylenedithiocarbamate, ferric dibenzyldithiocarbamate and the like.
Of these, zinc N-ethyl-N-phenyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, and zinc dibutyldithiocarbamate are desirable because of their high reactivity. Further, when the alkyl group contained in the accelerator compound is large, in the case of a relatively non-polar polymer, the solubility tends to be high, and it is difficult to cause a decrease in spinnability due to deterioration of surface properties due to precipitation, Zinc dibutyldithiocarbamate is a particularly preferred example.

  Xanthates include zinc methylxanthate, zinc ethylxanthate, zinc propylxanthate, zinc isopropylxanthate, zinc butylxanthate, zinc pentylxanthate, zinc hexylxanthate, zinc heptylxanthate, zinc octylxanthate , Zinc 2-ethylhexylxanthate, zinc decylxanthate, zinc dodecylxanthate, potassium methylxanthate, potassium ethylxanthate, potassium propylxanthate, potassium isopropylxanthate, potassium butylxanthate, potassium pentylxanthate, hexylxanthogen Potassium acetate, potassium heptylxanthate, potassium octylxanthate, 2-ethyl Potassium xylxanthate, potassium decylxanthate, potassium dodecylxanthate, sodium methylxanthate, sodium ethylxanthate, sodium propylxanthate, sodium isopropylxanthate, sodium butylxanthate, sodium pentylxanthate, sodium hexylxanthate, Examples include sodium heptyl xanthate, sodium octyl xanthate, sodium 2-ethylhexyl xanthate, sodium decyl xanthate, sodium dodecyl xanthate, and the like. Of these, zinc isopropylxanthate is preferable because of its high reactivity.

  The above vulcanization accelerator may be used for blending with the sheath resin of the rubber-reinforced core-sheath fiber in a form preliminarily dispersed in an inorganic filler, oil, polymer or the like. These vulcanization accelerators and retarders may be used alone or in combination of two or more.

  Content of a vulcanization accelerator (M) is 0.05-20 mass parts with respect to 100 mass parts of resin components, such as an olefin polymer contained in the resin material which comprises a sheath part, Especially, it is 0. .2 to 5 parts by mass. By making content of a vulcanization accelerator into the said range, the adhesive improvement effect of a resin material and rubber | gum can be acquired favorably.

  In addition to the components described above, a thermoplastic rubber (TPV) cross-linked to a polypropylene-based copolymer may be used for the resin material constituting the sheath for the purpose of increasing the adhesion at the interface with the adherend rubber composition. ), Or “other thermoplastic elastomer (TPZ)” in the classification of thermoplastic elastomers described in JIS K6418. They can finely disperse partially or highly crosslinked rubber in the continuous phase of the matrix of the thermoplastic resin composition of the resin material. Examples of the crosslinked thermoplastic rubber include acrylonitrile-butadiene rubber, natural rubber, epoxidized natural rubber, butyl rubber, and ethylene / propylene / diene rubber. Other thermoplastic elastomers (TPZ) include syndiotactic-1,2-polybutadiene resin or trans-polyisoprene resin.

  In order to add other properties such as oxidation resistance to the high melting point resin and the olefin polymer, the normal resin is used within a range that does not significantly impair the effects of the present invention and workability during spinning. Additives added to can also be blended. As this additional component, conventionally known nucleating agents, antioxidants, neutralizing agents, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, fillers (O) used as compounding agents for polyolefin resins, etc. , Various additives such as metal deactivator, peroxide, antibacterial and antifungal agent, fluorescent brightener, and vulcanization accelerator (N) used as a compounding agent for rubber composition, and other additives Things can be used.

Vulcanization accelerating aids (N) include monovalent metals such as lithium, sodium and potassium, formates such as polyvalent metals such as magnesium, calcium, zinc, copper, cobalt, manganese, lead and iron, acetates, Examples thereof include basic inorganic metal compounds such as nitrates, carbonates, hydrogen carbonates, oxides, hydroxides, and alkoxides.
Specifically, metal hydroxides such as magnesium hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, copper hydroxide; magnesium oxide, calcium oxide, zinc oxide (zinc white), copper oxide Metal carbonates such as magnesium carbonate, calcium carbonate, sodium carbonate, lithium carbonate, and potassium carbonate.
Among these, as the alkali metal salt, a metal hydroxide is preferable, and magnesium hydroxide is particularly preferable.

Fillers (O) include alumina, silica-alumina, magnesium chloride, calcium carbonate, talc, montmorillonite, zakonite, beidellite, nontronite, saponite, hectorite, stevensite, bentonite, teniolite and other smectites, vermiculite, Examples thereof include inorganic particulate carriers such as carbon black and mica group, and porous organic carriers such as polypropylene, polyethylene, polystyrene, styrenedivinylbenzene copolymer, and acrylic acid copolymer. These fillers are blended as fillers to reinforce the sheath part when the sheath part is not sufficiently resistant to fracture in the adhesion between the sheath part and the adherend rubber, and cracks occur in the sheath part. can do.
Examples of the carbon black include furnace black such as SAF carbon black, SAF-HS carbon black, ISAF carbon black, ISAF-HS carbon black, and ISAF-LS carbon black.

  Specific examples of additives include 2,2-methylene-bis (4,6-di-t-butylphenyl) phosphate, talc, 1,3,2,4-di (p-methylbenzylidene) as a nucleating agent. ) Sorbitol compounds such as sorbitol, hydroxy-di (t-butyl benzoate aluminum) and the like.

  Examples of the antioxidant include tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate and 1,1,3-tris (2-methyl-4) as phenolic antioxidants. -Hydroxy-5-t-butylphenyl) butane, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythritol-tetrakis {3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate}, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 3,9-bis [2 -{3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxas B [5,5] undecane, etc. 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethyl-pen Jill) isocyanuric acid.

  Phosphorus antioxidants include tris (mixed, mono and dinonylphenyl phosphite), tris (2,4-di-t-butylphenyl) phosphite, 4,4′-butylidenebis (3-methyl-6). -T-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5-t-butylphenyl) butane, bis (2,4-di -T-butylphenyl) pentaerythritol-di-phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di-t-butyl- 5-methylphenyl) -4,4′-biphenylenediphosphonite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol-di-phos Or the like can be mentioned Aito. Examples of the sulfur-based antioxidant include di-stearyl-thio-di-propionate, di-myristyl-thio-di-propionate, pentaerythritol-tetrakis- (3-lauryl-thio-propionate), and the like.

  Examples of the neutralizing agent include calcium stearate, zinc stearate, hydrotalcite and the like.

  Examples of hindered amine stabilizers include polycondensates of dimethyl oxalate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, tetrakis (1,2,2, 6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, N, N-bis (3 -Aminopropyl) ethylenediamine-2,4-bis {N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino} -6-chloro-1,3,5-triazine condensation Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2 , 4- Yl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {2,2,6,6-tetramethyl-4-piperidyl} imino], poly [(6-morpholino-s -Triazine-2,4-diyl) [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] And so on.

  Examples of the lubricant include higher fatty acid amides such as oleic acid amide, stearic acid amide, behenic acid amide, and ethylene bis stearoid, silicone oil, and higher fatty acid esters.

  Examples of the antistatic agent include higher fatty acid glycerin ester, alkyl diethanolamine, alkyl diethanolamide, alkyl diethanolamide fatty acid monoester and the like.

  Examples of the ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2 And ultraviolet absorbers such as' -hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole.

  Examples of the light stabilizer include n-hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate, 2,4-di-t-butylphenyl-3 ′, 5′-di-t-butyl-4 ′. -Hydroxybenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl-2- (4-hydroxy-2,2,6,6-tetramethyl-1-piperidyl) ethanol succinate Condensate, poly {[6-[(1,1,3,3-tetramethylbutyl) amino] -1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetra Methyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]}, N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- And the like 1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate.

  In particular, from the viewpoint of the combination of the core part and the sheath part, as the same olefin resin, it is possible to use a high melting point polyolefin resin for the core part and a low melting point polyolefin resin for the sheath part. This is preferable because the compatibility of the parts is good. Unlike the case where different types of resins are used for the core and the sheath by using an olefin resin for both the core and the sheath, the bonding force at the core-sheath polymer interface is high, and the core / sheath. Since it has sufficient peeling resistance against interfacial peeling between the parts, the characteristics as a composite fiber can be sufficiently exhibited over a long period of time. Specifically, a crystalline propylene homopolymer having a melting point of 150 ° C. or higher is used as the high melting point polyolefin-based resin in the core, and an ethylene-propylene copolymer or ethylene-propylene is used as the low melting point polyolefin resin in the sheath. It is preferable to use a polypropylene-based copolymer resin obtained by copolymerizing polypropylene with a component capable of copolymerizing with polypropylene, such as a butene-propylene terpolymer, in particular, an ethylene-propylene random copolymer. It is particularly preferable that the high melting point polyolefin-based resin in the core is isotactic polypropylene because of good fiber forming properties during spinning.

  In this case, the melt flow index (melt flow rate, MFR) (MFR1) of the high melting point polyolefin resin and the melt flow index (MFR2) of the low melting point polyolefin resin are particularly limited as long as they can be spun. Although it is not, 0.3-100 g / 10min is preferable. The same applies to the melt flow index of the high melting point resin used for the core other than the high melting point polyolefin resin.

  In particular, the melt flow index (MFR1) of the high melting point resin including the high melting point polyolefin resin is preferably 0.3 to 18 g / 10 min, particularly preferably 0.5 to 15 g / 10 min, more preferably 1 to 10 g / 10 min. You can choose from those in the range. When the MFR of the high-melting point resin is within the above range, the spinning take-out property and stretchability are improved, and the melt of the high-melting point resin in the core part is heated under the vulcanization process for producing the rubber article. This is because the form of the cord can be maintained without flowing.

  Further, the melt flow index (MFR2) of the low melting point polyolefin-based resin is preferably 5 g / 10 min or more, particularly preferably 5 to 70 g / 10 min, and further preferably 10 to 30 g / 10 min. In order to improve the heat fusion property of the low melting point polyolefin resin in the sheath, a resin having a large MFR is preferable because the resin easily flows and fills in the gap with the rubber to be deposited. On the other hand, if the MFR is too large, if there are other reinforcing members, such as ply cords or bead cores, in the vicinity where the composite fiber is disposed, if there is an unintended gap in the rubber covering the composite fiber, Since the melt of the low melting point polyolefin-based resin may wet and spread on the surface of the fiber material of the cord, it is particularly preferably 70 g / 10 min or less. More preferably, it is 30 g / 10 min or less. In this case, when the composite fibers are in contact with each other, the melt of the low melting point polyolefin melts and spreads between the fibers so as to become a lump-like fiber bonded body. This is preferable because the occurrence of this phenomenon is reduced. Further, if it is 20 g / 10 min or less, since the fracture resistance of the resin in the sheath portion is increased when the rubber to be fused is peeled off, it is more preferable that the rubber adheres firmly to the rubber.

  The MFR value (g / 10 min) is the same as JIS-K-7210. The melt flow rate of the polypropylene resin material is 230 ° C. and the load of 21.18 N (2160 g) under the load of the polyethylene resin material. The rate is the melt flow rate measured at a temperature of 190 ° C. and a load of 21.18 N (2160 g), respectively.

  As a ratio of the core part and the sheath part in the composite fiber or resin body in the present invention, the ratio of the core part in the composite fiber or resin body is preferably 10 to 95% by mass, and more preferably 30 to 80% by mass. %. If the ratio of the core portion is too small, the strength of the composite fiber or the resin body may be reduced, and sufficient reinforcing performance may not be obtained. In particular, the core portion ratio of 50% by mass or more is preferable because the reinforcing performance can be enhanced. On the other hand, when the ratio of the core part is too large, the ratio of the sheath part is too small, and the core part is easily exposed in the composite fiber or the resin body, and there is a possibility that sufficient adhesion with the rubber cannot be obtained.

  The production method of the composite fiber (monofilament) of the present invention can be carried out by a wet heating drawing method using a core-sheath type composite spinneret with two single-screw extruders for a core material and a sheath material. The spinning temperature can be 140 to 330 ° C., preferably 160 to 220 ° C. for the sheath component, and 200 to 330 ° C., preferably 210 to 300 ° C. for the core component. The wet heating can be performed, for example, at a wet heating apparatus 100 ° C. and a hot water bath 95-100 ° C., preferably 95-98 ° C. If it is once cooled and then reheated and stretched, the crystallization of the sheath proceeds, which is not preferable from the viewpoint of heat-fusibility. The draw ratio is preferably 1.5 times or more from the viewpoint of crystallization of the core.

  In the present invention, the fineness of the core-sheath fiber, that is, the fiber thickness is preferably in the range of 0.5 to 2200 dtex. If the fiber thickness of the core-sheath fiber is less than 0.5 dtex, the strength becomes low, and the effect of improving the friction coefficient by biting into the snow surface may not be obtained. Also, if the fiber thickness of the core-sheath fiber exceeds 2200 dtex, the spinning speed cord becomes very slow in order to solidify to the center of the cord because the spun yarn is too thick in the fiber production spinning process, It is not preferable because productivity efficiency or equipment rationality is lowered. In addition, the fiber thickness in this invention means the fiber size (based on JISL0101) measured only with the monofilament.

  Furthermore, as a preferable example, in the tire of the present invention, the core-sheath fiber has a fineness of 1 to 200 dtex or a fineness of 350 to 1100 dtex, and these finenesses may be a single fineness. Although it is good, you may include and use the fiber of several different fineness.

  Note that the monofilament cord of the present invention is characterized by high adhesion to rubber even when the thickness of the single fiber of the reinforcing material is 50 dtex or more. When the fiber thickness of the reinforcing material is less than 50 dtex, even when the adhesive composition is not bonded, or the fiber is not fused with the fiber resin and the rubber, a problem in the close contact with the rubber hardly occurs. This is because, when the diameter of a single fiber is reduced, the stress at which the cord is cut becomes smaller than the force at which the cord peels off. Therefore, when the adhesion is evaluated by peeling or the like, the interface between the cord and the rubber is peeled off. This is because the cord is cut before. These are also referred to as so-called “fluff adhesion”, and are phenomena that can be observed at a single fiber thickness of less than 50 dtex, which is about the same as that of fluff.

  Accordingly, even if the monofilament diameter is less than 50 dtex, it is not a problem with cords, nonwoven fabrics, reinforcing materials, etc., but if the thickness of the single fiber is 50 dtex or more, adhesion by the adhesive composition, fusion between fiber resin and rubber, etc. If there is not, adhesion between the rubber and the fiber becomes a problem. The monofilament of the present invention is characterized in that even when the thickness of the single fiber is 50 dtex or more, the close contact with the rubber is high and the end portion of the cord can be fused.

  However, when applied in the vicinity of the surface layer of a tread rubber in which fibers fall off or break (baldness or chipping) during wear as in the present invention, the thickness of the single fiber of the reinforcing material is less than 50 dtex. Even so, it is necessary to have high adhesion to rubber. This is for the following reason. That is, at the time of wear, the cord is worn out without being cut. In such wear, if there is no fusion between the fiber resin and the rubber that adheres to the fluff, the fiber easily peels off, so that the fiber easily falls off from the rubber during wear. However, as in the present invention, even if the thickness of the single fiber is 50 dtex or more, if the cord surface layer has a resin having high adhesiveness with rubber, when it wears at a fiber thickness of less than 50 dtex, This is preferable because the durability of dropping off and breaking (baldness and chipping) of fibers from the rubber is improved.

In the present invention, if the core-sheath fiber is embedded in at least a part of the tread block constituting the block pattern, the effect of improving the friction coefficient can be obtained. Suppose that the core-sheath fiber is embedded. As the buried density of core-sheath fibers is preferably 5 to 60 present / 50 mm ^2. If the burying density of the core-sheath fiber is less than 5/50 mm ² , there is a possibility that a sufficient effect of biting into the snow surface cannot be obtained. In addition, if the density of the core-sheath fibers exceeds 60 fibers / 50 mm ² , the core-sheath fibers are undesirably peeled due to strain stress if they are close to each other or fused together.

  The tire of the present invention only needs to have a core-sheath type composite fiber embedded in at least a part of the tread block in the tread pattern provided on the tread surface, and the internal structure is a general pneumatic tire. And can be appropriately determined as desired. The tire shown in FIG. 1 forms a pair of bead portions 1, a pair of sidewall portions 2 that extend from the pair of bead portions 1 to the outside in the tire radial direction, and a grounding portion that extends between the pair of sidewall portions 2. The tread portion 3 to be made. The illustrated tire has a carcass layer 5 composed of at least one carcass ply extending across a toroid between bead cores 4 embedded in a pair of bead portions 1, and the crown portion of the tire in the radial direction. A belt layer 6 composed of at least two belts arranged on the outside is provided. Although not shown, an inner liner is disposed inside the carcass layer 2 in the tire radial direction, and a bead filler is usually disposed outside the bead core 4 in the tire radial direction.

  In the present invention, as a method for producing a tread material in which the core-sheath fibers are embedded in at least a part of the tread block, first, the core-sheath fibers are aligned in parallel and covered with rubber to form a sheet-like material. A rubber-fiber composite is produced (composite production process). In this step, for example, a predetermined number of core-sheath fibers are aligned in parallel and passed between rolls, and coated with rubber from above and below, or co-extruded, or fibers spun into a core-sheath shape from a nozzle It can be carried out by a method of placing and transporting on a rubber sheet moving in the horizontal direction and further covering with rubber from above. This sheet-like rubber-fiber composite includes one core-sheath fiber in the thickness direction. For example, the sheet thickness can be 0.8 mm to 1.5 mm. In this step, the density of the core-sheath fibers embedded in the tread rubber can be changed by appropriately adjusting the alignment interval (indentation interval) of the core-sheath fibers.

  Next, the obtained rubber-fiber composite is cut perpendicularly to the longitudinal direction of the core-sheath fiber to obtain a composite strip (cutting step). In this case, the cutting interval of the rubber-fiber composite can be set to an appropriate interval according to the thickness of the target tread material, and is not particularly limited. Specifically, it can be 5 to 10 mm.

  Next, the obtained composite strip is aligned so that the fiber cross section of the core-sheath fiber is exposed, whereby a sheet-like tread material can be obtained (tread material production step). At this time, by combining composite strips obtained using core-sheath fibers of different fineness or implantation intervals and strip-shaped tread rubber not containing core-sheath fibers, tread materials having various finenesses and embedment densities can be obtained. Can be obtained.

  In the tread material obtained as described above, since the core-sheath fiber is substantially oriented in the thickness direction of the tread material, in the tire manufactured using this, the core-sheath fiber is surely provided on the road surface. It will be arranged perpendicular to. After affixing the tread material obtained above to a vulcanized or unvulcanized tire intermediate (applying step), the tire intermediate with the tread material affixed is 140 ° C. to 190 ° C. according to a conventional method. The tire of the present invention can be produced by vulcanization at a vulcanization temperature of 0 ° C. for 3 to 50 minutes (vulcanization step). The tread material obtained by the present invention constitutes a tread block that forms the surface of the tread tread portion, and a base rubber made of the same or different compounded rubber is arranged on the inner side in the tire radial direction. Also good.

Hereinafter, the present invention will be described in more detail with reference to examples.
As the thermoplastic resin used as the raw material, the core and sheath resins described in Table 3 below, which were dried using a vacuum dryer, were used.

1) Production of test fibers (Examples 1 to 7, Comparative Examples 1 to 3)
As the core component and the sheath component, using the materials shown in Tables 1 and 2 below, the diameter of the core material and the sheath material are two 50-mm single-screw extruders at the spinning temperature shown in each table. Using a core-sheath type composite spinneret with a thickness of 1.3 mm, melt at a spinning speed of 80 m / min, adjusting the discharge rate to about 8.9 g / min so that the sheath-core ratio is 4: 6 by mass. The fiber was spun and stretched in a 98 ° C. hot water bath to 2.0 times to obtain a core-sheath type composite monofilament having a fineness of 550 dtex.

(Example 7)
Using the materials shown in the following Tables 1 to 3 as the core component and the sheath component, the diameter of the core material and the sheath material are two 50-mm single-screw extruders at the spinning temperature shown in each table. Using a 0.8 mm core-sheath type composite spinneret, melt spinning at a discharge rate of 0.2 g / min and a spinning speed of 22 m / min while adjusting the sheath-core ratio to 4: 6 by mass ratio. Then, it was cooled with air to obtain a core-sheath type composite monofilament having a fineness of 80 dtex.

2) Manufacture of test tires
The entire tread block constituting the block pattern provided on the tread surface is made of a high melting point resin having a melting point of 150 ° C. or higher, and the sheath part contains an olefin polymer and has a melting point higher than that of the high melting point resin. A core-sheath type composite fiber (fineness: 550 dtex) made of a low resin material is embedded at an embedding density of 45 fibers / 50 mm ² so that the longitudinal direction is oriented within 20 ° from the tire radial direction, Test tires of Examples 1 to 7 and Comparative Examples 1 to 3 were produced.

  The tread rubber in which the core-sheath fiber was embedded was manufactured as follows. First, a core-sheath fiber is composite-spun at a fineness of 550 dtex, and the core-sheath fiber is drawn in parallel at an implantation interval of 45/5 cm to be covered with a rubber, so that a sheet-like rubber fiber having a thickness of 1.0 mm is obtained. A composite was prepared. Thereafter, the rubber-fiber composite is cut at intervals of 9 to 10 mm perpendicularly to the longitudinal direction of the composite fiber to obtain a composite strip. The composite strip is exposed so that the fiber cross section of the core-sheath fiber is exposed. The sheet-like tread material was obtained. The tread material was attached to an unvulcanized tire intermediate and then vulcanized to obtain test tires of the examples and comparative examples.

(Performance evaluation on snow)
About each obtained test tire (tire size: 205 / 60R15), the performance on snow was evaluated by driving | running | working a real vehicle. Each tire was filled with an internal pressure of 200 kPa and mounted on a passenger car, and a braking test was performed on a snowy road. In the test, the braking distance from the initial speed of 40 km / h until full braking was applied to the stationary state was measured. From the results, the performance index on snow was determined according to the following formula.
(Performance index on snow) = (braking distance of tire of example) / (braking distance of tire of comparative example 1) × 100
Tables 1 and 2 below show the evaluation results.

(Abrasion resistance evaluation)
Each test tire (tire size: 205 / 60R15) obtained was mounted on a domestic FF vehicle (2000cc) and the groove depth of the tire tread after running 10,000 km was measured, and the tire groove depth was reduced by 1 mm. The travel distance was calculated and indexed by the following formula. It shows that it is excellent in abrasion resistance, so that an index | exponent is large.
(Abrasion resistance index) = (travel distance when the tire groove depth of the example is reduced by 1 mm) / (travel distance when the tire groove depth of the comparative example 1 is reduced by 1 mm) × 100
Tables 1 and 2 below show the evaluation results.

  From the results in the above table, it was confirmed that the tire of each example to which the present invention was applied had improved on-snow robust performance as compared with the tire of Comparative Example 1.

1 Bead part 2 Side wall part 3 Tread part 4 Bead core 5 Carcass layer 6 Belt layer 11 Circumferential groove

Claims (14)

A pneumatic tire having a block pattern on the tread surface,
At least a part of the tread block constituting the block pattern is made of a high melting point resin (A) having a core part having a melting point of 150 ° C. or higher, and a sheath part containing the olefin polymer (D) than the high melting point resin. A core-sheath type composite fiber made of a resin material (B) having a low melting point is embedded, and the longitudinal direction of the composite fiber is oriented in a direction within 20 ° from the tire radial direction. Pneumatic tires.   The olefin polymer (D) includes a propylene-α olefin copolymer (H), a propylene-nonconjugated diene copolymer (I), an unsaturated carboxylic acid or an anhydride monomer thereof. The ionomer (J) having a degree of neutralization with a metal salt of the copolymer of 20% or more and one or more components selected from the group consisting of olefinic homopolymers (K). Pneumatic tire.   The resin material (B) is a styrene elastomer (L) containing a single molecular chain in which the olefin polymer (D) and a styrene monomer are mainly continuously arranged, and a vulcanization accelerator (M). The pneumatic tire according to claim 1 or 2, comprising at least one selected from the group consisting of vulcanization accelerating aid (N) and filler (O).   The pneumatic tire according to claim 2 or 3, wherein the propylene-α-olefin copolymer (H) is a propylene-ethylene random copolymer and / or a propylene-ethylene-butene random copolymer.   The pneumatic tire according to any one of claims 2 to 4, wherein the ionomer (J) is an ionomer of an ethylene / methacrylic acid copolymer.   The pneumatic tire according to any one of claims 2 to 5, wherein the olefin homopolymer (K) is a polyethylene polymer and / or a polypropylene polymer.   The pneumatic tire according to any one of claims 3 to 6, wherein the styrene elastomer (L) contains a styrene block copolymer, a hydrogenated product thereof, or a modified product thereof.   The pneumatic tire according to claim 7, wherein the styrene elastomer (L) is a styrene-ethylene-butadiene-styrene copolymer.   The high-melting point resin (A) is a resin material containing a polymer selected from a polyolefin resin (P) having a melting point of 150 ° C or higher, a polyester resin (Q), and a polyamide resin (R). The pneumatic tire according to any one of 1 to 8.   The pneumatic tire according to any one of claims 1 to 9, wherein the fineness of the composite fiber is 0.5 to 2200 dtex. The embedded density of the composite fibers, the pneumatic tire of any one of claims 1 to 10 0.5 to 60 present / 50 mm ^2.   Core-sheath type composite fibers made of a high melting point resin having a melting point of 150 ° C. or more and a sheath part made of a resin material containing an olefin polymer and having a melting point lower than that of the high melting point resin are arranged in parallel. A composite production step for producing a sheet-like rubber-fiber composite by coating with rubber, and the obtained rubber-fiber composite is cut perpendicularly to the longitudinal direction of the composite fiber to form a composite strip And a tread material production step for obtaining a sheet-like tread material by aligning the obtained composite strip so that a fiber cross section of the composite fiber is exposed. A method for manufacturing a tread material.   A sheet-like rubber-fiber composite having a thickness of 0.8 to 1.5 mm is prepared in the composite preparation step, and the obtained rubber-fiber composite is cut at intervals of 5 to 10 mm in the cutting step. Item 13. A method for producing a tread material according to Item 12. An attaching step of attaching the tread material obtained by the method for producing a tread material according to claim 12 or 13 to a vulcanized or unvulcanized tire intermediate, and a tire intermediate to which the tread material is attached. And a vulcanizing step for vulcanizing the tire.

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