JP2011063095A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire preventing uneven wear in a tread center region of the tire including an edge cover layer as a belt cover layer. <P>SOLUTION: In this pneumatic radial tire, the edge cover layers 4 on which reinforcing cords are spirally wound in a tire peripheral direction are provided in at least both end parts of a belt layer 3 arranged in a tread part 2, and a main groove 12 extending in the tire peripheral direction is arranged in the center region not corresponding to at least the edge cover layer 4 on a surface of the tread part 2. In a tread rubber region held between the main groove 12 and a surface of the belt layer 3 opposed to the main groove 12, a thermoplastic film layer 8 made of thermoplastic resin or thermoplastic elastomer composition blended with elastomer in the thermoplastic resin is extended in the tire peripheral direction along the longitudinal direction of the main groove 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire that prevents uneven wear that tends to occur in the tread central region of a tire provided with an edge cover as a belt cover layer.

  Many pneumatic radial tires for high performance are provided with a belt cover layer formed by spirally winding organic fiber cords at a small angle of 10 ° or less in the tire circumferential direction on the outer periphery of the belt layer provided on the tread. ing. This belt cover layer prevents separation at the end of the belt layer by suppressing the both ends of the belt layer from being lifted by centrifugal force during high-speed running. This belt cover layer has a full cover layer that covers the entire width of the belt layer and an edge cover layer that covers only both ends of the belt layer. These two types of cover layers are only one of them depending on the tire characteristics. There are cases where both are arranged and a combination of both.

  However, no matter how these two types of cover layers are arranged, there is a tire provided with an edge cover layer and a plurality of main grooves extending in the tire circumferential direction on the tread surface. (For example, Patent Document 1), the main groove provided in the region corresponding to the edge cover layer suppresses the growth of the outer diameter due to the tagging effect of the edge cover layer, but does not correspond to the edge cover layer. In the main groove portion provided in, the edge cover layer has no tagging effect, and the rubber gauge at the bottom of the groove is thin, so that the rigidity is low. Therefore, the main groove portion in the central region of the tread grows to have a large outer diameter when the inner pressure is filled and inflated, and the ground contact shape P is as shown in FIG.

  That is, in the footprint diagram shown in FIG. 4, 21 and 22 in the grounding shape P are portions corresponding to the main groove, 22 corresponds to the main groove in the central region of the tread, and the grounding of the central portion of the grounding shape P The length is significantly larger than the lengths 21 and 22 at both ends. Therefore, there has been a problem that wear at the center of the tread progresses abnormally compared to both ends, and uneven wear tends to occur.

JP 2007-1401 A

  An object of the present invention is to provide a pneumatic radial tire that prevents uneven wear in a tread central region of a tire provided with an edge cover layer as a belt cover layer.

  The pneumatic radial tire of the present invention that achieves the above-described object has the following configuration (1).

(1) An edge cover layer in which a reinforcing cord is spirally wound in the tire circumferential direction is provided on at least both ends of the belt layer disposed in the tread portion, and at least a center that does not correspond to the edge cover layer on the surface of the tread portion In a pneumatic radial tire in which a main groove extending in the tire circumferential direction is disposed in a region, a thermoplastic resin is provided in a tread rubber region sandwiched between the main groove and the surface of the belt layer facing the main groove. Alternatively, a thermoplastic film layer made of a thermoplastic elastomer composition obtained by blending an elastomer in a thermoplastic resin is provided so as to extend in the tire circumferential direction along the longitudinal direction of the main groove.

In addition, in the pneumatic radial tire of the present invention, it is more preferable to have one of the following configurations (2) to (7).
(2) The thermoplastic film layer is disposed at the groove bottom of the main groove.
(3) The thermoplastic film layer is disposed on an outer surface of the belt layer or an outer surface of a belt cover layer covering the belt layer.
(4) The thermoplastic film layer is disposed on a groove bottom portion of the main groove and an outer surface of the belt layer or an outer surface of a belt cover layer covering the belt layer.
(5) The storage elastic modulus of the thermoplastic film layer is 50 to 2000 MPa, and the thickness is 10 to 500 μm.
(6) The storage elastic modulus of the thermoplastic film layer is 50 to 1000 MPa, and the thickness is 20 to 400 μm.
(7) The storage elastic modulus of the thermoplastic film layer is 50 to 300 MPa, and the thickness is 30 to 300 μm.

  According to the pneumatic radial tire of the present invention, the main groove disposed so as to extend in the tire circumferential direction in a central region not corresponding to the edge cover layer and the surface of the belt layer opposed to the main groove are sandwiched. In the tread rubber region, a thermoplastic film layer made of a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer is blended in a thermoplastic resin is provided along the longitudinal direction of the main groove, so that it is generally more elastic than rubber. The thermoplastic film layer having a high rate can suppress the growth of the outer diameter of the main groove portion in the central region of the tread during inflation of the tire, thereby preventing uneven wear in the central region of the tread.

It is meridian direction sectional drawing of the tread part which shows the embodiment of the pneumatic radial tire of this invention. It is meridian direction sectional drawing of the tread part which shows the other embodiment of the pneumatic radial tire of this invention. FIG. 6 is a footprint diagram showing a ground contact shape of the pneumatic radial tire of Example 4. It is the footprint figure which showed an example of the tire ground contact shape of the conventional tire.

  Hereinafter, the pneumatic radial tire of the present invention will be described in more detail with reference to the embodiment shown in the drawings.

  FIG. 1 is a cross-sectional view of the main part in the tire meridian direction showing a tread portion of an embodiment of a pneumatic radial tire of the present invention.

  In the pneumatic radial tire 1, a belt cover layer is formed on the outer periphery of the belt layer 3 disposed in the tread portion 2. The belt cover layer includes a full cover layer 7 in which a reinforcing cord is spirally wound at a small angle within 10 ° with respect to the tire circumferential direction so as to cover the entire width of the belt layer 3, and both end portions of the full cover layer 7 The edge cover layer 4 is formed by spirally winding the reinforcing cords in the tire circumferential direction so as to cover only the cover. On the surface of the tread portion 2, three main grooves 11 and 12 extending in the tire circumferential direction are arranged in a shoulder region 5 corresponding to the edge cover layer 4 and a central region 6 not corresponding to the edge cover layer 4. ing.

  In the embodiment shown in FIG. 1, the full cover layer 7 is provided as a belt cover layer covering the entire belt width in the tire width direction. However, the full cover layer 7 is not necessarily provided, and the edge cover is not necessarily provided. Only the layer 4 may be provided.

  The pneumatic radial tire of FIG. 1 includes a thermoplastic film layer 8 made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer in a thermoplastic resin at the bottom of the main groove 12 in the central region. It is provided so as to extend in the tire circumferential direction along the direction. The thermoplastic film layer generally has a property that the elastic modulus is larger than that of rubber, and preferably has a storage elastic modulus of 50 to 150 MPa and a thickness of 10 to 500 μm, and more preferably has a storage elastic modulus of 70. The thing which is -130 MPa and thickness is 30-300 micrometers is good. By providing such a thermoplastic film layer 8 along the main groove 12, when the tire is inflated and running at a high speed, the thermoplastic film layer 8 exhibits a very large tagging effect, and the edge cover layer. It is possible to prevent the outer diameter of the main groove 12 in the central region of the tread where 4 is not provided from growing greatly, and as a result, the occurrence of uneven wear can be prevented.

  In the present invention, the position at which the thermoplastic film layer 8 is provided is not limited to the case of the embodiment of FIG. 1, but in the tread rubber region where the main groove 12 in the central region is sandwiched between the outer surfaces of the opposite belt layers 3. As long as it exists, the same effect of preventing uneven wear as described above can be obtained. In FIG. 1, 9 is an inner liner layer and 10 is a carcass layer.

  In FIG. 2, the thermoplastic film layer 8 is arranged on the outer surface of the full cover layer 7 of the belt cover layer inside the main groove 12 in the central region. The thermoplastic film layer 8 may be the outer surface of the belt layer 3 in the case of a tire in which the full cover layer 7 is not provided. Further, it may be an intermediate region between the main groove 12 and the belt layer 3.

  The thermoplastic film layer made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer into a thermoplastic resin used in the present invention preferably has a storage elastic modulus of 50 to 2000 MPa and a thickness of 10 to 500 μm. More preferably, the storage elastic modulus is 50 to 1000 MPa and the thickness is 20 to 400 μm. Most preferably, the storage elastic modulus is 50 to 300 MPa and the thickness is 30 to 300 μm. By disposing the film layer having such physical properties in the main groove portion in the central region, this thermoplastic film layer increases the circumferential rigidity in the main groove portion in the central region, and inflates the tire to drive at high speed. Even when doing so, it is possible to prevent the outer diameter of the main groove portion in the central region from expanding.

  When the storage elastic modulus of the thermoplastic film layer is less than 50 MPa, the effect of increasing the circumferential rigidity is poor, and when it is greater than 150 MPa, the tagging effect in the central region becomes too large, This is not preferable because it may cause uneven wear. Further, when the thickness of the thermoplastic film layer is less than 10 μm, it is difficult to increase the rigidity, and when it exceeds 500 μm, the rigidity is often too high, which is not preferable.

  The thermoplastic film layer referred to in the present invention may be composed of a plurality of sheets, and the thickness when the thermoplastic film layer is composed of a plurality of sheets in this way refers to the total sum of the respective thicknesses.

  In the present invention, the thermoplastic resin constituting the thermoplastic film layer or the thermoplastic resin in the thermoplastic elastomer composition in which the elastomer is blended in the thermoplastic resin may be, for example, a polyamide resin [for example, nylon 6 (N6), Nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 612 (N612), nylon 6/66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer] and Their N-alkoxyalkylates, such as methoxymethyl nylon 6 , Methoxymethylated nylon 6/610 copolymer, methoxymethylated nylon 612, polyester resin [eg, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI Copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, aromatic polyester such as polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer], polynitrile resin [for example, polyacrylonitrile ( PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), (meth) acrylonitrile / styrene copolymer, (meth) acrylonitrile / styrene / butadiene copolymer], poly Tacrylate resins [eg, polymethyl methacrylate (PMMA), polyethyl methacrylate], polyvinyl resins [eg, vinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride ( PDVC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer (ETFE)], cellulosic resins [eg, cellulose acetate, acetic acid Cellulose butyrate], fluororesins [eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymers], imide resins [eg, aromatic Poly Imido (PI)] and the like can be preferably used.

  Examples of the elastomer constituting the thermoplastic elastomer composition include diene rubbers and hydrogenated products thereof [for example, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene butadiene rubber (SBR). , Butadiene rubber (BR, high cis BR and low cis BR), nitrile rubber (NBR), hydrogenated NBR, hydrogenated SBR], olefin rubber [eg, ethylene propylene rubber (EPDM, EPM), maleic acid modified ethylene propylene Rubber (M-EPM), butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer], halogen-containing rubber [for example, Br-IIR, CI-IIR, isobutylene para Brominated methyl styrene copolymer (Br-IPMS) Chloroprene rubber (CR), hydrin rubber (CHR), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), maleic acid modified chlorinated polyethylene rubber (M-CM)], silicone rubber [eg, methyl vinyl silicon Rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (for example, polysulfide rubber), fluorine rubber (for example, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon) Rubbers, fluorine-containing phosphazene rubbers), thermoplastic elastomers (for example, styrene elastomers, olefin elastomers, ester elastomers, urethane elastomers, polyamide elastomers). As it is possible to use.

  In the thermoplastic elastomer composition, the composition ratio between the specific thermoplastic resin and the elastomer is not particularly limited, and is appropriately determined so that the elastomer is dispersed as a discontinuous phase in the thermoplastic resin matrix. The preferred range is 90/10 to 30/70 by weight.

  Hereinafter, specific examples and effects of the pneumatic radial tire of the present invention will be described with reference to examples.

  In the present invention, the storage elastic modulus and wear resistance performance are measured and evaluated by the following methods.

(1) Storage elastic modulus This is a value obtained by measuring the storage elastic modulus at 0 ° C. at a static strain of 10%, a dynamic strain of ± 2%, and a frequency of 20 Hz using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho.

(2) Uneven wear resistance performance A road test was conducted on 215 / 60R16 with 3 main grooves (no rotation), and each set of 4 cars (maximum remaining groove amount-minimum remaining groove) after traveling 20,000 km The amount of the groove was measured with a gauge and averaged by four to evaluate the uneven wear performance. For the maximum remaining groove amount and the minimum remaining groove amount, the larger one of “average remaining groove amount of the two main grooves located on the shoulder side” and “remaining groove amount of the main groove located at the center” is the largest remaining groove amount. The groove amount, which is smaller, is obtained as the minimum remaining groove amount.

  The evaluation results were obtained by using the reciprocal of the measured value and indicated by an index with the reciprocal of the measured value of Comparative Example 1 being 100.

  Moreover, the footprint figure of the pneumatic radial tire of Example 3 was shown in FIG. It can be seen that the pneumatic radial tire of Example 3 is superior in uneven wear resistance compared to that shown in FIG.

  The evaluation result is obtained by using the reciprocal of the measured value, and is represented by an index where the reciprocal of the measured value of the conventional example is 100. The larger the index, the better the wear resistance.

Examples 1 to 12, conventional examples, comparative examples 1 to 6
As shown in FIG. 1, the tire size is 195 / 65R15 91H, the tire structure has three main grooves, the belt layer 3 is made of steel cord, and the full cover layer 7 and the edge cover layer 4 are nylon 66 fibers. Nineteen types of pneumatic radial tires were manufactured, which consisted of a cord, and that a film layer or the like was not provided at the bottom or lower periphery of the shoulder region main groove 11.

  Nineteen types are conventional examples in which a thermoplastic film layer is not provided on the groove bottom of the central region main groove, and thermoplastic film layers having different storage elastic modulus and gauge thickness are provided on the groove bottom of the central region main groove. A total of 18 types provided in a “U” shape were prepared (Examples 1 to 12, Comparative Examples 1 to 6).

  The thermoplastic film layer has the composition shown in Table 1.

  The 19 types of pneumatic radial tires were evaluated for uneven wear resistance, and the results are shown in Table 2. Moreover, the footprint figure of the pneumatic radial tire of Example 4 was shown in FIG. It can be seen that the wear resistance is superior to that shown in FIG.

Examples 13 to 24, conventional examples, comparative examples 7 to 12
The tire size is 195 / 65R15 91H, and as shown in FIG. 2, the tire structure has three main grooves, the belt layer 3 is made of steel cord, and the full cover layer 7 and the edge cover layer 4 are nylon 66 fibers. Nineteen types of pneumatic radial tires were manufactured, which consisted of cords, and that the bottom of the shoulder region main groove 11 and the central region main groove 12 had no film layer or the like.

  In 19 types, a conventional example (same as the above-described conventional example) in which the thermoplastic film layer is not provided on the full cover layer below the central region main groove is used, and as shown in FIG. Under the groove and on the full cover layer, a total of 18 types of belts having a width of 1.5 cm were provided in the entire tire circumferential direction with different storage elastic modulus and gauge thickness (Examples 13 to 24). Comparative Examples 7-12).

  A thermoplastic film layer consists of a composition of Table 1 mentioned above.

  The 19 types of pneumatic radial tires were evaluated for uneven wear resistance by the method described above, and the results are shown in Table 3.

1: Pneumatic radial tire 2: Tread part 3: Belt layer 4: Edge cover layer 5: Shoulder region 6: Center region
7: Full cover layer 8: Thermoplastic film layer 9: Inner liner layer 10: Carcass layer 11: Main groove in the shoulder region 12: Main groove in the central region 21: Ground contact shape portion 22 corresponding to the main groove in the shoulder region Grounding shape part corresponding to the main groove of the area P: Grounding shape

Claims (7)

  In at least both ends of the belt layer disposed in the tread portion, an edge cover layer in which a reinforcing cord is spirally wound in the tire circumferential direction is provided, and at least a central region corresponding to the edge cover layer on the surface of the tread portion, In a pneumatic radial tire having a main groove extending in a tire circumferential direction, a thermoplastic resin or a thermoplastic is provided in a tread rubber region sandwiched between the main groove and the surface of the belt layer facing the main groove. A pneumatic radial tire provided with a thermoplastic film layer made of a thermoplastic elastomer composition obtained by blending an elastomer in a resin so as to extend in the tire circumferential direction along the longitudinal direction of the main groove.   The pneumatic radial tire according to claim 1, wherein the thermoplastic film layer is disposed at a groove bottom portion of the main groove.   The pneumatic radial tire according to claim 1, wherein the thermoplastic film layer is disposed on an outer surface of the belt layer or an outer surface of a belt cover layer covering the belt layer.   The pneumatic radial tire according to claim 1, wherein the thermoplastic film layer is disposed on a groove bottom portion of the main groove and an outer surface of the belt layer or an outer surface of a belt cover layer covering the belt layer.   The pneumatic radial tire according to any one of claims 1 to 4, wherein the thermoplastic film layer has a storage elastic modulus of 50 to 2000 MPa and a thickness of 10 to 500 µm.   The pneumatic radial tire according to claim 5, wherein the thermoplastic film layer has a storage elastic modulus of 50 to 1000 MPa and a thickness of 20 to 400 μm.   The pneumatic radial tire according to claim 6, wherein the thermoplastic film layer has a storage elastic modulus of 50 to 300 MPa and a thickness of 30 to 300 μm.