REINFORCING MEMBER FOR TIRES AND TIRE USING SAME

Abstract

Provided is a tire reinforcing member that can further improve various tire performances, such as steering stability and ride comfort. Also provided is a tire in which various tire performances, such as steering stability and ride comfort, are further improved by the use of the tire reinforcing member. A tire reinforcing member (10) is formed by laminating two or more layer members (3) each obtained by covering elongated fiber materials (1) with a polymer material (2). The layer members each have a thickness of 0.01 mm to 0.5 mm, and the whole reinforcing member has a thickness of 0.5 mm to 2.0 mm.

Claims

1. A tire reinforcing member formed by laminating two or more layer members each obtained by covering elongated fiber materials with a polymer material, wherein the layer members each have a thickness of 0.01 mm to 0.5 mm, and the whole reinforcing member has a thickness of 0.5 mm to 2.0 mm.

2. The tire reinforcing member according to claim 1, wherein the fiber materials are carbon fibers.

3. The tire reinforcing member according to claim 1, wherein the polymer material is a thermoplastic resin or a thermoplastic elastomer.

4. The tire reinforcing member according to claim 1, wherein the fiber materials uniformly exist in the polymer material.

5. The tire reinforcing member according to claim 1, having a specific tensile strength of 300 MPa or higher and a specific elastic modulus of 5 GPa or higher, both with respect to a tire circumferential direction.

6. The tire reinforcing member according to claim 1, wherein the fiber materials have a specific tensile strength of 500 MPa or higher and a specific elastic modulus of 5 GPa or higher.

7. The tire reinforcing member according to claim 1, wherein the polymer material has a specific elastic modulus of 1 MPa or higher.

8. The tire reinforcing member according to claim 1, wherein a volume fraction of the fiber materials contained per unit volume of the layer members is 30 to 80% by volume.

9. The tire reinforcing member according to claim 1, wherein the fiber materials have an extending direction in a range of 10 to +10 with respect to a longitudinal direction of the layer members.

10. The tire reinforcing member according to claim 1, wherein the fiber materials comprise: a component A extending in a direction of +20 to +90 with respect to the longitudinal direction of the layer members; and a component B extending in a direction of 20 to 90 with respect to the longitudinal direction of the layer members, and an inclination direction of the component A and that of the component B are line-symmetrical with respect to the longitudinal direction of the layer members.

11. The tire reinforcing member according to claim 10, wherein the component A and the component B are contained in different layer members.

12. The tire reinforcing member according to claim 10, wherein the component A and the component B are contained in the same layer member.

13. The tire reinforcing member according to claim 1, which is formed by directly laminating the two or more layer members.

14. The tire reinforcing member according to claim 2, wherein the polymer material is a thermoplastic resin or a thermoplastic elastomer.

15. The tire reinforcing member according to claim 2, wherein the fiber materials uniformly exist in the polymer material.

16. The tire reinforcing member according to claim 2, having a specific tensile strength of 300 MPa or higher and a specific elastic modulus of 5 GPa or higher, both with respect to a tire circumferential direction.

17. The tire reinforcing member according to claim 2, wherein the fiber materials have a specific tensile strength of 500 MPa or higher and a specific elastic modulus of 5 GPa or higher.

18. The tire reinforcing member according to claim 2, wherein the polymer material has a specific elastic modulus of 1 MPa or higher.

19. The tire reinforcing member according to claim 2, wherein a volume fraction of the fiber materials contained per unit volume of the layer members is 30 to 80% by volume.

20. A tire comprising the tire reinforcing member according to claim 1 that is arranged in a crown portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a widthwise cross-sectional view illustrating one example of a tire reinforcing member of the present invention.

[0017] FIG. 2 is a widthwise cross-sectional view illustrating one example of a tire of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0018] Embodiments of the present invention will now be described in detail referring to the drawings.

[0019] FIG. 1 is a widthwise cross-sectional view illustrating one example of a tire reinforcing member of the present invention. As illustrated, a tire reinforcing member 10 of the present invention assumes the form of a film or a sheet that is obtained by laminating two or more, for example, two to ten, preferably three to five (three in the illustrated example) layer members 3 each formed by covering elongated fiber materials 1 with a polymer material 2.

[0020] In the present invention, it is important that the layer members 3 each have a thickness of 0.01 mm to 0.5 mm and the whole reinforcing member 10 has a thickness of 0.5 mm to 2.0 mm. This enables to obtain a reinforcing member that can further improve various tire performances, such as steering stability and ride comfort, while reducing the weight of the reinforcing member 10 itself. Further, a reduction in the weight of the reinforcing member 10 itself can contribute to a reduction in the tire weight. Moreover, by using the reinforcing member 10 of the present invention in place of a conventional belt, the rolling resistance can be reduced and the fuel efficiency can be improved as compared to before.

[0021] The thickness of each layer member 3 is required to be 0.01 mm to 0.5 mm, preferably 0.1 mm to 0.3 mm. An excessively small thickness of the layer member 3 leads to an increased number of steps in the molding process for lamination, while an excessively large thickness of the layer member 3 leads to deterioration of the ride comfort due to an increase in the out-of-plane flexural rigidity.

[0022] The thickness of the whole reinforcing member 10 of the present invention is required to be 0.5 mm to 2.0 mm, preferably 1.0 mm to 2.0 mm. An increase in the thickness of the reinforcing member 10 tends to improve the steering stability; however, since it also increases the out-of-plane flexural rigidity, which conflicts with the demand for weight reduction, it is necessary to control the thickness to be not greater than 2.0 mm. Meanwhile, when the thickness of the reinforcing member 10 is excessively small, a required rigidity cannot be attained.

[0023] In the present invention, specific examples of the fiber materials 1 include carbon fibers (CF), such as polyacrylonitrile (PAN)-based carbon fibers, pitch-based carbon fibers, and rayon-based carbon fibers; glass fibers; metal fibers made of steel or the like; organic fibers such as aramid fibers (aromatic polyamide fibers), polyketone (PK) fibers, poly-p-phenylene benzobisoxazole (PBO) fibers, polyarylate fibers, nylon fibers (aliphatic polyamide fiber), and polyester fibers (e.g., polyethylene terephthalate (PET) fibers); rock fibers (rock wool) such as basalt fibers and andesite fibers, among which carbon fibers can be preferably used. Alternatively, composite fibers made of two or more kinds of the above-described fibers may be used as well.

[0024] The thickness of the fiber materials 1 in the layer members 3 is preferably 0.05 mm to 0.3 mm, more preferably 0.1 mm to 0.3 mm.

[0025] In the present invention, specific examples of the polymer material 2 include thermoplastic resins, thermoplastic elastomers, thermosetting resins, photocurable resins, and rubber materials, among which thermoplastic resins and thermoplastic elastomers can be preferably used.

[0026] Thereamong, as the thermoplastic resins, for example, polyamide resins such as polyamide 66 (PA66), polyether resins such as polyether ether ketones (PEEK), urethane resins, olefin resins, vinyl chloride resins, and polyester resins such as PET can be used.

[0027] As the thermoplastic elastomers, for example, amide-based thermoplastic elastomers (TPA), ester-based thermoplastic elastomers (TPC), olefin-based thermoplastic elastomers (TPO), styrene-based thermoplastic elastomers (TPS), urethane-based thermoplastic elastomers (TPU), thermoplastic rubber vulcanizates (TPV), and other thermoplastic elastomers (TPZ), all of which are defined in JIS K6418, can be used.

[0028] As the thermosetting resins, for example, phenol resins, urea resins, melamine resins, epoxy resins, and polyester resins can be used.

[0029] The reinforcing member 10 of the present invention is composed of the layer members 3 each obtained by covering the fiber materials 1 with the polymer material 2; therefore, it is necessary to ensure the adhesion between the reinforcing member 10 and its surrounding rubber members when the reinforcing member 10 is arranged inside a tire. In this respect, the use of an adhesive may be considered for ensuring the adhesion with rubber and, as the polymer material 2, it is also preferred to use a material that is adhesive with rubber components.

[0030] The reinforcing member 10 of the present invention has a specific tensile strength in the tire circumferential direction of preferably 300 MPa or higher, more preferably 800 MPa or higher, still more preferably 1,100 MPa or higher, and the higher the specific tensile strength of the reinforcing member 10, the more preferred it is. Particularly, the specific tensile strength may be 2,500 MPa or less. Further, the reinforcing member 10 of the present invention has a specific elastic modulus in the tire circumferential direction of preferably 5 GPa or higher, more preferably 35 GPa or higher, still more preferably 45 GPa or higher, and the higher the specific elastic modulus, the more preferred it is. Particularly, the specific elastic modulus may be 200 GPa or less. When the specific tensile strength is small, the thickness is increased for ensuring the strength and the rigidity, and this leads an increase in the weight, which is not preferred.

[0031] In the present invention, the specific tensile strength of the fiber materials 1 is preferably 500 MPa or higher, more preferably 700 MPa or higher, still more preferably 2,000 MPa or higher, and the higher the specific tensile strength of the fiber materials 1, the more preferred it is. Further, the specific elastic modulus of the fiber materials 1 is preferably 5 GPa or higher, more preferably 8 GPa or higher, still more preferably 95 GPa or higher, and the higher the specific elastic modulus of the fiber materials 1, the more preferred it is. When the fiber materials 1 have a specific tensile strength of less than 500 MPa and/or a specific elastic modulus of less than 5 GPa, it is necessary to increase the fiber amount for ensuring the rigidity, and this causes an increase in the weight, which is not preferred.

[0032] In the present invention, the specific elastic modulus of the polymer material 2 is preferably 1 MPa or higher, more preferably 100 MPa or higher, and the higher the specific elastic modulus of the polymer material 2, the more preferred it is. When the specific elastic modulus of the polymer material 2 is small, the thickness is increased for ensuring the strength and the rigidity, and this leads an increase in the weight, which is not preferred.

[0033] It is noted here that, in the present invention, the specific tensile strength and the specific elastic modulus that are stated for the reinforcing member 10, the fiber materials 1 and the polymer material 2 may be values measured under the conditions having a temperature of 25 C. and a humidity of 55% RH in accordance with JIS L1017 and JIS K7113, respectively.

[0034] In the present invention, it is preferred that the fiber materials 1 uniformly exist in the polymer material 2. Specifically, for example, the fiber materials 1 are allowed to uniformly exist in a single direction of arrangement in the plane of each layer member 3 by parallelly arranging the fiber materials 1 at regular intervals or without any spacing and embedding these fiber materials 1 in the polymer material 2, or the fiber materials 1 are allowed to exist uniformly in two or more directions of arrangement in the plane of each layer member 3 by preparing a fabric using the fiber materials 1 and embedding this fabric in the polymer material 2.

[0035] In the present invention, the volume fraction of the fiber materials 1 contained per unit volume of the layer members 3 is preferably 30 to 80% by volume, particularly preferably 40 to 60% by volume. By controlling the volume fraction of the fiber materials 1 contained per unit volume of the layer members 3 to be in a range of 30 to 80% by volume, the ratio of fibers and a resin is made uniform as a material, which is preferred.

[0036] In the reinforcing member of the present invention, the extending direction of the fiber materials 1 is not particularly restricted; however, it is preferably in a range of 10 to +10 with respect to the longitudinal direction of the layer members 3. This enables to ensure the strength and the rigidity in the circumferential direction, which is preferred.

[0037] In the reinforcing member 10 of the present invention, the fiber materials 1 may include: a component A extending in a direction of +20 to +90, particularly +40 to +80, with respect to the longitudinal direction of the layer members 3; and a component B extending in a direction of 20 to 90, particularly 40 to 80, with respect to the longitudinal direction of the layer members 3, and the inclination direction of the component A and that of the component B may be line-symmetrical with respect to the longitudinal direction of the layer members 3. This enables to attain both satisfactory strength and satisfactory shear rigidity in the circumferential direction, which is preferred.

[0038] In this case, the component A and the component B may be contained in different layer members 3, or may be contained in the same layer member 3.

[0039] FIG. 2 is a widthwise cross-sectional view illustrating a tire for passenger vehicles that is one example of a tire of the present invention. An illustrated tire 20 includes: a tread portion 11 which forms a ground-contact part; a pair of side wall portions 12 which continuously extend inward in the tire radial direction on the respective sides of the tread portion 11; and bead portions 13 which continuously extend on the circumferential inner side of each side wall portion 12. The tread portion 11, the side wall portions 12 and the bead portions 13 are reinforced by a carcass 14 which is composed of at least one carcass ply (e.g., one or two carcass plies; a single carcass ply in the illustrated example) toroidally extending from one bead portion 13 to the other bead portion 13. In the illustrated tire 20, bead cores 15 are each embedded in the pair of the bead portions 13, and the carcass 14 is folded around the bead cores 15 from the inside to the outside of the tire and thereby anchored. In addition, bead fillers 16 are arranged on the tire radial-direction outer side of the respective bead cores 15.

[0040] The tire 20 of the present invention is characterized by including the reinforcing member 10 of the present invention that is arranged in a crown portion. In the illustrated example, the reinforcing member 10 of the present invention is arranged on the tire radial-direction outer side of the carcass 14 in the crown portion, in place of a conventional intersecting belt layer. By this, as described above, various tire performances such as steering stability and ride comfort can be further improved.

[0041] In the tire of the present invention, as required, one or more cap layers 17 covering the entirety of the reinforcing member 10 in the tire width direction, and one or more layered layers 18 covering the tire width-direction ends of the reinforcing member 10 may be arranged on the tire radial-direction outer side of the reinforcing member 10. Further, an inner liner is usually arranged on the innermost surface of the tire, although not illustrated in the drawing.

[0042] The reinforcing member 10 of the present invention can be formed by, for example, but not particularly limited to, winding the layer member 3, which is obtained by covering the fiber materials 1 with the polymer material 2, two or more times in the tire circumferential direction.

DESCRIPTION OF SYMBOLS

[0043] 1: fiber material [0044] 2: polymer material [0045] 3: layer member [0046] 10: tire reinforcing member [0047] 11: tread portion [0048] 12: side wall portion [0049] 13: bead portion [0050] 14: carcass [0051] 15: bead core [0052] 16: bead filler [0053] 17: cap layer [0054] 18: layered layer [0055] 20: tire for passenger vehicles