JP2010047073A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire enhancing visibility of depth of a remained groove while enhancing water-discharge property. <P>SOLUTION: At least a groove bottom of the groove formed on a tread surface 1 is covered by a film layer 5 comprising a thermoplastic resin colored to a chromatic color other than black or to white or a thermoplastic elastomer composition in which a thermoplastic resin component and an elastomer component are blended. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that improves the visibility of the remaining groove depth while improving drainage.

  When the tire is worn and the groove formed on the tread surface becomes shallow, there is a problem that the drainage performance on the tread surface is lowered and the braking / driving performance on the wet road surface is drastically lowered. In order to prevent such a situation, it is obliged to provide a wear indicator indicating that the depth of the remaining groove is 1.6 mm at the bottom of the main groove formed on the tread surface.

  Conventionally, in order to improve the visibility of the remaining groove depth of the groove formed on the tread surface, a ring-shaped collar member is fitted into the groove of the tread portion (see, for example, Patent Document 1), or from the groove bottom. There is a proposal in which a color-coded laminated structure that protrudes toward the tread surface is provided, and the progress of wear is grasped by a change in the color of the laminated structure (see, for example, Patent Document 2).

However, in the former, there is a problem that the drainage performance is reduced because the volume of the groove is restricted by the arrangement of the collar member, and in the latter case, there is a problem that productivity is poor in addition to the reduction in drainage. However, none of the proposals has been satisfactory yet as a measure for improving the visibility of the remaining groove depth.
Japanese Patent No. 3817350 Utility Model Registration No. 3067056

  An object of the present invention is to solve the above-mentioned problems, and to provide a pneumatic tire that improves the visibility of the remaining groove depth while improving the drainage.

  The pneumatic tire of the present invention that achieves the above object comprises a thermoplastic resin or a thermoplastic resin component colored with a chromatic or white color other than black at least at the groove bottom of the grooves formed on the tread surface, and an elastomer component. A film layer made of a blended thermoplastic elastomer composition is coated.

Moreover, in the structure mentioned above, it is preferable to comprise as described in the following (1)-(5).
(1) The film layer is coated on the groove sidewall as well as the groove bottom.
(2) A fluorescent substance or a light reflective substance is blended in the thermoplastic resin or thermoplastic elastomer composition constituting the film layer.
(3) The storage elastic modulus of the thermoplastic resin or the thermoplastic elastomer composition constituting the film layer is set to 10 to 500 MPa.
(4) The thickness of the film layer is 0.02 to 1.3 mm.
(5) The groove provided with the film layer is a main groove extending in the tire circumferential direction. In this case, it is preferable that the surface of the wear indicator formed in the main groove is covered with a second film layer colored in a chromatic color other than black or a white color different from the film layer. Further, the second film layer is preferably composed of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component.

  According to the present invention, a thermoplastic resin colored with a chromatic color or white color other than black, or a thermoplastic elastomer composition blended with an elastomer component, at least at the groove bottom of the grooves formed on the tread surface. Since the film layer which consists of this is coat | covered, the change of the shape of a groove | channel and the depth of a remaining groove | channel can be easily grasped | ascertained visually by the distinguishability of the colored film layer. Moreover, since no special material is disposed on the inner surface of the groove except for the film layer, the volume of the groove is not reduced. Further, since the film layer has a lower coefficient of friction than rubber, the groove wall The frictional resistance in can be reduced and drainage can be improved.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a sectional view in the tire meridian direction showing an example of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing grooves formed on the tread surface of the tire of FIG.

  In FIG. 1, a tread surface 1 of a pneumatic tire is formed with a main groove 2 extending in the tire circumferential direction and sub-grooves extending in the tire width direction not shown in FIG. As a result, various tread patterns are formed. In the figure, 3 indicates a belt layer and 4 indicates a carcass layer.

  In the pneumatic tire of the present invention, as shown in FIG. 2, at least the groove bottom (the groove bottom and the side wall of the main groove 2 in the figure) among the grooves formed on the tread surface 1 has a chromatic color or white color other than black. A film layer 5 made of a colored thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component is coated.

  Thereby, the change in the shape of the groove and the depth of the remaining groove can be easily grasped visually by the distinguishability of the colored film layer 5. In addition, since no special substance is disposed on the inner surface of the groove except for the film layer 5, the volume of the groove is not reduced, and the film layer 5 has a lower coefficient of friction than the surrounding rubber. Therefore, the frictional resistance in the groove wall can be reduced and the drainage can be improved.

  Here, the color of the film layer 5 is not particularly limited. However, since the tread rubber is black, it is preferable that the color of the film layer 5 is, for example, yellow or white with high discrimination.

  The thermoplastic resin described above is not particularly limited. For example, polyamide resin, polyester resin, polynitrile resin, polymethacrylate resin, polyvinyl resin, cellulose resin, fluorine resin, imide resin Etc. are used.

  The thermoplastic elastomer composition can be formed by mixing an elastomer component with the above-described thermoplastic resin component. Examples of the elastomer include a diene rubber and a hydrogenated product thereof, an olefin rubber, and a halogen-containing rubber. Rubber, silicon rubber, sulfur-containing rubber, fluorine rubber, thermoplastic elastomer and the like are used.

  When the thermoplastic resin component and the elastomer component described above are different in compatibility, it is preferable to make them compatible using a suitable compatibilizer as the third component. By mixing a compatibilizing agent with the blend system, the interfacial tension between the thermoplastic resin and the elastomer component decreases, and as a result, the rubber particle size forming the dispersion layer becomes fine, so the characteristics of both components are improved. It will be expressed more effectively. As such a compatibilizing agent, generally, a copolymer having a structure of both or one of the thermoplastic resin and the elastomer component, or an epoxy group, a carbonyl group, a halogen which can react with the thermoplastic resin or the elastomer component are used. A copolymer having a group, an amino group, an oxazoline group, a hydroxyl group and the like can be taken. These copolymers may be selected depending on the type of thermoplastic resin and elastomer component to be mixed, but those commonly used include styrene / ethylene / butylene block copolymer (SEBS) and its maleic acid modified products. EPDM, EPM, EPDM / styrene or EPDM / acrylonitrile graft copolymer and its modified maleic acid, styrene / maleic acid copolymer, reactive phenoxin and the like. The amount of the compatibilizing agent is not particularly limited, but is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymer component (the total of the thermoplastic resin and the elastomer component). .

  In the present invention, the composition ratio of the specific thermoplastic resin component (A) and the elastomer component (B) when the thermoplastic resin and the elastomer are blended is not particularly limited, but the thermoplastic resin component ( The weight ratio of A) to the elastomer component (B) is preferably 90/10 to 30/70.

  The thermoplastic elastomer composition thus obtained has a structure in which the elastomer component (B) is dispersed as a discontinuous phase in the matrix of the thermoplastic resin (A). By taking such a structure, it is possible to provide both sufficient flexibility and sufficient rigidity due to the effect of the resin layer as a continuous phase, and at the time of molding, the thermoplastic resin can be used regardless of the amount of the elastomer component. Equivalent moldability can be obtained.

  In the present invention, in order to adhere the film layer 5 to the rubber of the groove wall, a tire molding is performed by using an ordinary rubber-based, phenol resin-based, acrylic copolymer-based, isocyanate-based polymer and a crosslinking agent dissolved in a solvent. Sometimes, it may be applied to the position of the groove on the tread surface, or it may be applied to the entire surface of the tread surface and bonded by heat and pressure during tire vulcanization. Examples of the solvent-based adhesive include phenol resin (Chemlock 220, Rhode), chlorinated rubber (Chemlock 205, Chemlock 234B), isocyanate (Chemlock 402), and the like.

  1 and 2 exemplify the case where the film layer 5 is coated over the entire groove wall of the groove, but in the pneumatic tire of the present invention, as shown in FIG. Can be covered, or a part of the groove bottom can be covered as shown in FIG.

  In the present invention, the thermoplastic resin or the thermoplastic elastomer composition constituting the film layer 5 may be blended with a fluorescent substance or a light reflecting substance. Thereby, the change in the shape of the groove and the depth of the remaining groove can be easily confirmed even at night.

  Furthermore, by adjusting the elastic modulus of the thermoplastic resin or the thermoplastic elastomer composition constituting the film layer 5, it is possible to suppress the occurrence of cracks on the wall surface of the groove. In particular, as illustrated in FIG. 3A or 3B, by providing the film layer 5 on the entire surface or a part of the groove bottom, the generation of cracks at the groove bottom can be efficiently suppressed.

  In the present invention, the storage elastic modulus of the thermoplastic resin or the thermoplastic elastomer composition constituting the film layer 5 may be adjusted to 10 to 500 MPa, preferably 25 to 400 MPa. Thereby, since the deformation | transformation of the groove bottom part where bending distortion concentrates most on a tread surface is suppressed by the elasticity of the film layer 5, generation | occurrence | production of the crack in a groove bottom can be suppressed efficiently. Here, if the storage elastic modulus is less than 10 MPa, the effect of suppressing cracks in the groove wall is insufficient, and if the storage elastic modulus exceeds 500 MPa, the film layer 5 is too hard to follow the movement of rubber around the groove bottom. The film layer 5 may be peeled off.

  In addition, the storage elastic modulus mentioned above applies the value in 20 degreeC when using a viscoelasticity spectrometer made from Toyo Seiki Seisakusho and making static strain 10%, dynamic strain +/- 2%, and frequency 20Hz.

  More preferably, the thickness of the film layer 5 is 0.02 to 1.3 mm, preferably 0.05 to 1.0 mm. If the thickness is less than 0.02 mm, the effect of suppressing cracks in the groove wall is insufficient, and if it exceeds 1.3 mm, it becomes difficult to follow the movement of rubber around the groove bottom, and the film layer 5 may be peeled off.

  In the pneumatic tire of the present invention, it is preferable to provide the film layer 5 on the groove wall of the main groove 2 extending in the tire circumferential direction in order to more efficiently improve the drainage performance when traveling on a wet road surface. Thereby, since the friction coefficient in the wall surface of the main groove 2 is reduced, the drainage performance in a wet road surface can be improved reliably.

  More preferably, as illustrated in FIG. 4, the second film layer 7 in which the surface of the wear indicator 6 formed in the main groove 2 is colored in a chromatic color or white other than black, which is different from the film layer 5 described above. Cover with. Thereby, the distinguishability of the wear indicator 6 can be improved and the visibility of the remaining groove depth can be further improved.

  The second film layer 7 may be composed of a thermoplastic elastomer composition in which a plastic resin or a thermoplastic resin component and an elastomer component are blended, like the film layer 5. Thereby, since the film layer 5 covered on the surface of the wear indicator 6 and the second film layer 7 covered on the upper surface thereof are firmly bonded, the visibility of the wear indicator 6 can be secured over a long period of time. .

It is sectional drawing which shows an example of the pneumatic tire by embodiment of this invention. It is sectional drawing which expands and shows the main groove formed in the tread surface of the tire of FIG. (A) And (b) is sectional drawing equivalent to FIG. 2 by other embodiment of this invention, respectively. FIG. 6 is a cross-sectional view corresponding to FIG. 2 according to still another embodiment of the present invention.

Explanation of symbols

1 tread surface 2 main groove 5 film layer 6 wear indicator 7 second film layer

Claims (8)

  Cover at least the groove bottom of the groove formed on the tread surface with a chromatic or white colored thermoplastic resin or a thermoplastic elastomer composition blended with a thermoplastic resin component and an elastomer component. Pneumatic tire.   The pneumatic tire according to claim 1, wherein the film layer is also coated on a side wall of the groove together with the groove bottom.   The pneumatic tire according to claim 1 or 2, wherein a fluorescent substance or a light reflecting substance is blended in the thermoplastic resin or the thermoplastic elastomer composition constituting the film layer.   The pneumatic tire according to claim 1, 2, or 3, wherein a storage elastic modulus of a thermoplastic resin or a thermoplastic elastomer composition constituting the film layer is 10 to 500 MPa.   The pneumatic tire according to claim 1, 2, 3, or 4, wherein the film layer has a thickness of 0.02 to 0.13 mm.   The pneumatic tire according to claim 1, 2, 3, 4, or 5, wherein the groove provided with the film layer is a main groove extending in a tire circumferential direction.   The pneumatic tire according to claim 6, wherein the surface of the wear indicator formed in the main groove is covered with a second film layer colored in a chromatic color or white other than black different from the film layer.   The pneumatic tire according to claim 7, wherein the second film layer is made of a thermoplastic elastomer composition in which a plastic resin or a thermoplastic resin component and an elastomer component are blended.

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