JP7373482B2 - tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to tires.

Pneumatic tires installed on automobiles include two or more inclined belt plies that include cords that are inclined with respect to the tire circumferential direction on the outside in the tire radial direction of the carcass, and A structure including a belt made up of multiple layers including a reinforcing layer and the like is common (see, for example, Patent Documents 1 and 2).

On the other hand, Patent Document 3 discloses a belt in which a resin-coated cord, which is constructed by coating a reinforcing cord with a resin as a polymeric material, is spirally wound in the tire circumferential direction around the outer periphery of a tire frame member. A tire having the following is disclosed.

JP2013-244930A JP2013-220741A JP2018-065426A

The durability of a belt made of reinforcing cords and resin is affected by the belt shape and the distance between adjacent cords in the width direction of the tire, that is, the distance between the cords. becomes difficult to secure.

An object of the present invention is to ensure the durability of a tire that includes a tire case in which the outer side of the carcass in the tire width direction is coated with a rubber material, and a belt in which the reinforcing cord is coated with resin.

The tire according to the first aspect includes a carcass extending from one bead part to the other bead part, and includes a tire case in which at least an outer part of the carcass in the width direction of the tire is covered with a rubber material; Resin-coated cords configured by coating reinforcing cords with resin are spirally wound around the outer periphery of the tire case along the tire circumferential direction, and are adjacent to each other in the tire width direction in the resin-coated cords. a belt configured by bonding the resins to each other, and B is the minimum value of the distance in the tire width direction between two reinforcing cords that are adjacent in the tire width direction without straddling the bonding interface of the resins. , in the cross section in the tire width direction, the average thickness of the belt at the tire equator is C, and the distance in the tire width direction between the two reinforcing cords that are adjacent in the tire width direction across the bonding interface of the resin is D. Then, the range of C/D is 1.33 or more and 2.30 or less, and the range of B/D is 0.08 or more and 1.00 or less.

Here, if C/D is less than 1.33, durability in a water pressure test in which water is injected into the tire is insufficient, and if it exceeds 2.30, durability in a drum test is insufficient. Moreover, if B/D is less than 0.08 or more than 1, durability in the drum test will be insufficient.

In this tire, since the range of C/D and the range of B/D are appropriately set, it is possible to ensure both durability in the water pressure test and durability in the drum test.

In a second aspect, in the tire according to the first aspect, where A is the outer diameter of the reinforcing cord, and E is the minimum thickness of the resin from the outermost periphery of the reinforcing cord, C/A is 1. 99 or more, and E is 0.15 mm or more.

Here, if C/A is less than 1.99 or E is less than 0.15 mm, durability in the drum test will be insufficient.

In this tire, since C/A and E are appropriately set, durability in the drum test can be ensured.

In a third aspect, in the tire according to the first aspect or the second aspect, the distance D ranges from 1.0 mm to 2.1 mm.

Here, if D is less than 1.0 mm, the durability in the drum test will be insufficient, and if it exceeds 2.1 mm, the durability in the water pressure test will be insufficient.

In this tire, since the range of D is appropriately set, it is possible to ensure both durability in the water pressure test and durability in the drum test.

In a fourth aspect, in the tire according to any one of the first to third aspects, the distance B ranges from 0.15 mm to 1.6 mm.

Here, if B is less than 0.15 mm, the durability in the drum test will be insufficient, and if it exceeds 1.6 mm, the durability in the water pressure test will be insufficient.

In this tire, since the range of B is appropriately set, it is possible to ensure both durability in the water pressure test and durability in the drum test.

According to the present invention, it is possible to ensure the durability of a tire including a tire case in which the outer side of the carcass in the tire width direction is coated with a rubber material, and a belt in which the reinforcing cord is coated with resin.

FIG. 1 is a half-sectional view showing a tire according to an embodiment. FIG. 3 is an enlarged cross-sectional view showing a resin-coated cord. FIG. 3 is an enlarged cross-sectional view showing a resin-coated cord. FIG. 3 is an enlarged cross-sectional view showing a resin-coated cord. FIG. 3 is an enlarged cross-sectional view showing a resin-coated cord. It is a table showing test conditions and test results.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing. Components shown using the same reference numerals in the drawings refer to the same or similar components. Note that redundant explanations and symbols in the embodiments described below may be omitted. In addition, the drawings used in the following explanation are all schematic, and the dimensional relationship of each element, the ratio of each element, etc. shown in the drawings do not necessarily match the reality. Moreover, the dimensional relationship of each element, the ratio of each element, etc. do not necessarily match between a plurality of drawings.

In the drawings, the direction of arrow R indicates the tire radial direction, and the direction of arrow W indicates the tire width direction. The tire radial direction means a direction perpendicular to the tire rotation axis (not shown). The tire width direction means a direction parallel to the tire rotation axis (direction of arrow X). The tire width direction can also be referred to as the tire axial direction.

The method for measuring the dimensions of each part is according to the method described in the 2020 edition YEAR BOOK published by JATMA (Japan Automobile Tire Association). If TRA standards or ETRTO standards are applied at the place of use or manufacturing, each standard shall be followed.

In FIG. 1, a tire 10 according to the present embodiment is, for example, a so-called radial tire used for a passenger car, and includes a tire case 25 and a belt 26. FIG. 1 shows the shape of a tire 10 in its natural state before being filled with air.

(tire case)
The tire case 25 includes a pair of bead portions 20 in which bead cores 12 are embedded, and a carcass 16 extending from one bead portion 20 to the other bead portion 20. The carcass 16 is composed of, for example, one carcass ply 14.

The carcass ply 14 is formed by covering a plurality of cords (not shown) extending in the radial direction of the tire 10 with a coating rubber (not shown). The material of the cord of the carcass ply 14 is, for example, PET, but may be other conventionally known materials.

The end portion of the carcass ply 14 in the tire width direction is folded back from the inside of the bead core 12 in the tire radial direction to the outside. The part of the carcass ply 14 that spans from one bead core 12 to the other bead core 12 is called a main body part 14A, and the part that is folded back from the bead core 12 is called a folded part 14B.

A bead filler 18 whose thickness gradually decreases from the bead core 12 toward the outside in the tire radial direction is arranged between the main body portion 14A and the folded portion 14B of the carcass ply 14. In addition, in the tire 10, a portion of the bead filler 18 on the inner side in the tire radial direction from the outer end 18A in the tire radial direction is a bead portion 20.

An inner liner 22 made of rubber is arranged on the inside of the tire of the carcass 16, and a side rubber layer 24 made of a first rubber material is arranged on the outer part (outer side) of the carcass 16 in the tire width direction. . That is, at least the outer side of the carcass 16 in the tire width direction is covered with a rubber material.

In this embodiment, the tire case 25 is composed of the bead core 12, the carcass 16, the bead filler 18, the inner liner 22, and the side rubber layer 24. In other words, the tire case 25 is a tire frame member that forms the frame of the tire 10.

(belt)
A belt 26 is disposed outside the crown portion of the carcass 16, in other words, outside the carcass 16 in the tire radial direction, and the belt 26 is in close contact with the outer peripheral surface of the carcass 16. As shown in FIG. 2, the belt 26 has a resin-coated cord 34 in which a plurality of (eg, two) reinforcing cords 30 are coated with resin 32. As shown in FIG. This resin-coated cord 34 is wound along the tire circumferential direction around the outer periphery of the carcass 16 that constitutes a part of the tire case 25. Specifically, the resin-coated cord 34 is wound around the outer periphery of the carcass 16 in a spiral shape around an axis along the tire axial direction.

The belt 26 is constructed by joining the resins 32 of the resin-coated cord 34 that are adjacent to each other in the tire width direction. In this way, by joining the resins 32 of the resin-coated cord 34, a joining interface 27 is formed on the belt 26. Since the resins 32 of the resin-coated cord 34 are joined together by, for example, welding, the joining interface 27 can also be referred to as a welded portion.

As described above, by winding the resin-coated cord 34 around the outer circumference of the carcass 16 along the tire circumferential direction, the plurality of reinforcing cords 30 are extended along the tire circumferential direction. That is, the plurality of reinforcing cords 30 are provided in a straight line when viewed in the tire radial direction. Furthermore, as shown in FIG. 2, in the cross section of the belt 26 in the tire width direction, a plurality of reinforcing cords 30 are arranged side by side along the tire width direction.

As the reinforcing cord 30, it is preferable to use one that is thicker and has greater strength (tensile strength) than the cord of the carcass ply 14. The reinforcing cord 30 can be composed of a monofilament (single wire) such as a metal fiber or an organic fiber, or a multifilament (stranded wire) obtained by twisting wires using these fibers.

In this embodiment, as shown in FIG. 2, the reinforcing cord 30 is composed of a multifilament (stranded wire) in which a plurality of (for example, seven) strands 30A are twisted. Furthermore, in this embodiment, a metal wire (specifically, a steel cord) is used as the wire 30A. The diameter of the wire 30A is, for example, 0.3 mm or more and 0.5 mm or less. The outer diameter (diameter) A of the reinforcing cord 30 is, for example, 0.86 mm or more and 1.13 mm or less. Here, the outer diameter A of the reinforcing cord 30 is the diameter of the circumscribed circle 30B in which all the wires 30A constituting the reinforcing cord 30 fit.

For the resin 32 that covers the reinforcing cord 30, a resin material having a higher tensile modulus than the rubber that makes up the side rubber layer 24 and the second rubber material that makes up the tread 36, which will be described later, is used. As the resin 32 that covers the reinforcing cord 30, an elastic thermoplastic resin, a thermoplastic elastomer (TPE), a thermosetting resin, or the like can be used. Considering elasticity during running and moldability during manufacturing, it is desirable to use a thermoplastic elastomer.

Examples of thermoplastic elastomers include polyolefin thermoplastic elastomer (TPO), polystyrene thermoplastic elastomer (TPS), polyamide thermoplastic elastomer (TPA), polyurethane thermoplastic elastomer (TPU), and polyester thermoplastic elastomer (TPC). , dynamically crosslinked thermoplastic elastomer (TPV), and the like.

Further, examples of the thermoplastic resin include polyurethane resin, polyolefin resin, vinyl chloride resin, polyamide resin, and the like. Furthermore, as a thermoplastic resin material, for example, the load deflection temperature specified by ISO75-2 or ASTM D648 (at a load of 0.45 MPa) is 78°C or more, and the tensile yield strength specified by JIS K7113 is 10 MPa. As mentioned above, those having a tensile elongation at break of 50% or more as defined in JIS K7113 and a Vicat softening temperature (method A) as defined in JIS K7206 of 130°C or higher can be used.

The tensile modulus (defined in JIS K7113:1995) of the resin 32 covering the reinforcing cord 30 is preferably 50 MPa or more. Further, the upper limit of the tensile modulus of the resin 32 covering the reinforcing cord 30 is preferably 1000 MPa or less. Note that the tensile modulus of the resin 32 covering the reinforcing cord 30 is particularly preferably within the range of 200 to 700 MPa.

It is preferable that the thickness dimension C of the belt 26 of this embodiment is larger than the dimension along the belt radial direction of the reinforcing cord 30 formed in a spiral shape. In other words, it is preferable that the reinforcing cord 30 is completely embedded in the resin 32.

Furthermore, as shown in FIG. 4, the reinforcing cord 30 may be coated with an adhesive resin 31 to improve adhesiveness with the resin 32. In this case, the resin 32 covers the reinforcing cord 30 which is coated with the adhesive resin 31.

Examples of the adhesive resin 31 include modified olefin resins (modified polyethylene resins, modified polypropylene resins, etc.), polyamide resins, polyurethane resins, polyester resins, modified polyester resins, and ethylene-ethyl acrylate copolymers. , those containing one or more thermoplastic resins such as ethylene-vinyl acetate copolymer as a main component (main agent).

Among these, from the viewpoint of adhesion between the reinforcing cord 30 and the resin 32, modified olefin resins, polyester resins, modified polyester resins, ethylene-ethyl acrylate copolymers, and ethylene-vinyl acetate copolymers are used. A hot melt adhesive containing at least one selected from the group consisting of: is preferred, and a hot melt adhesive containing at least one selected from modified olefin resins and modified polyester resins is more preferred; among them, acid-modified olefin resins ( A hot melt adhesive containing at least one selected from a modified olefin resin (acid-modified with an unsaturated carboxylic acid) and a modified polyester resin is more preferable, and a hot melt adhesive containing an acid-modified polyester resin is particularly preferable.

The term "modified olefin resin acid-modified with an unsaturated carboxylic acid" refers to a modified olefin resin obtained by graft copolymerizing an unsaturated carboxylic acid to a polyolefin.

Note that, as shown in FIG. 1, a tread 36 made of a second rubber material is arranged on the outer side of the belt 26 in the tire radial direction. The second rubber material used for the tread 36 is a conventionally known material. A drainage groove 37 is formed in the tread 36. Furthermore, a conventionally known pattern is used for the tread 36.

In FIG. 3, B is the minimum value of the distance in the tire width direction between two reinforcing cords 30 that are adjacent in the tire width direction without straddling the bonding interface 27 of the resin 32. Further, in the cross section in the tire width direction, the average thickness of the belt 26 at the tire equator CL is defined as C. The average thickness C of the belt 26 at the tire equator is the average value when the thickness of the belt 26 at the tire equator is measured at 10 locations in the tire circumferential direction. Specifically, the average thickness C of the belt 26 is preferably 0.70 mm or more when the tire 10 is for a passenger car.

Further, the distance in the tire width direction between two reinforcing cords 30 that are adjacent in the tire width direction across the bonding interface 27 of the resin 32 is defined as D. Then, in this embodiment, the range of C/D is 1.33 to 2.30, and the range of B/D is 0.08 to 1.00.

Here, if C/D is less than 1.33, durability in a water pressure test in which water is injected into the tire is insufficient, and if it exceeds 2.30, durability in a drum test is insufficient. By appropriately setting the C/D range and the B/D range, both durability in the water pressure test and durability in the drum test can be ensured.

When the outer diameter of the reinforcing cord 30 is A, and the minimum thickness of the resin 32 from the outermost periphery of the reinforcing cord 30 is E, C/A is 1.99 or more and E is 0.15 mm or more. You can.

Here, as shown in FIG. 2, when the reinforcing cord 30 is composed of multifilament, the outermost periphery of the reinforcing cord 30 means the circumscribed circle 30B of the strand 30A. Further, the position of the minimum thickness E of the resin 32 differs depending on the position of the reinforcing cord 30. In the example shown in FIG. 3, the thickness of the resin 32 from the outermost periphery of the reinforcing cord 30 to the bonding interface 27 is the minimum thickness E. On the other hand, in the example shown in FIG. 5, the thickness of the resin 32 from the outermost periphery of the reinforcing cord 30 to the inner surface in the tire radial direction of the resin-coated cord 34 is the minimum thickness E. In addition, the thickness of the resin 32 from the outermost circumference of the reinforcing cord 30 to the outer surface of the resin-coated cord 34 in the tire radial direction may be the minimum thickness E (not shown).

Note that if B/D is less than 0.08 or greater than 1, durability in the drum test will be insufficient. Furthermore, if C/A is less than 1.99 or E is less than 0.15 mm, durability in the drum test will be insufficient. By appropriately setting C/A and E, durability in the drum test can be ensured.

The range of distance D may be 1.0 mm or more and 2.1 mm or less. Here, if D is less than 1.0 mm, the durability in the drum test will be insufficient, and if it exceeds 2.1 mm, the durability in the water pressure test will be insufficient. By appropriately setting the range of D, both durability in the water pressure test and durability in the drum test can be ensured.

The range of distance B may be 0.15 mm or more and 1.6 mm or less. Here, if B is less than 0.15 mm, the durability in the drum test will be insufficient, and if it exceeds 1.6 mm, the durability in the water pressure test will be insufficient. By appropriately setting the range of B, it is possible to ensure both durability in the water pressure test and durability in the drum test.

As described above, according to the present embodiment, the durability of the tire 10 including the tire case 25 in which the outer part of the carcass in the tire width direction is covered with a rubber material, and the belt 26 in which the reinforcing cord 30 is covered with the resin 32 is improved. can ensure sex.

(Test example)
As shown in FIG. 6, tires according to Examples and Comparative Examples were manufactured and subjected to a drum durability test (JIS D 4230) and a water pressure test.

Details of the resin covering the reinforcing cord are as follows.
5557: Polyester thermoplastic elastomer (manufactured by DuPont-Toray Co., Ltd., trade name "Hytrel 5557")
P-280B: Polyester thermoplastic elastomer (manufactured by Toyobo Co., Ltd., trade name "Pelprene P-280B")
P-90B...Polyester thermoplastic elastomer (manufactured by Toyobo Co., Ltd., trade name "Pelprene P-90B")

In all Examples and Comparative Examples, the adhesive layer provided between the reinforcing cord and the resin is a resin composition prepared by mixing the following materials.
・Polyester thermoplastic elastomer (manufactured by DuPont Toray Industries, Inc., “Hytrel 6367”)…80 parts by mass ・Polybutylene terephthalate (manufactured by Toray Industries, Inc., “Torecon 1401X06”)…20 parts by mass ・Epoxy resin (Nippon Kayaku (Nippon Kayaku) Co., Ltd., "XD-1000", epoxy equivalent: 245 g/eq to 260 g/eq, softening point: 68°C to 78°C)...10 parts by mass, zinc cyanurate...1 part by mass

<Drum durability test>
After adjusting the internal pressure to 249.2 kPa (3.0 kgf/cm ² ) in a room at 25±2° C., the tire was left for 24 hours. Thereafter, the air pressure was readjusted, a load twice the normal load specified by JIS was applied to the tire, and the tire was run for a maximum of 20,000 km at a speed of 60 km/h on a drum approximately 3 m in diameter. Then, the distance traveled before the tire failed was measured and evaluated according to the following evaluation criteria.

The longer the mileage, the more durable the tire is. If it is classified as [G2], there is no practical problem, and if it is classified as [G1], it can be said to be practically preferable. Those classified as [F] lack practical durability.

[Evaluation criteria]
G1: Completed 20,000km G2: Mileage before failure was 10,000km or more but less than 20,000km F: Mileage before failure was less than 10,000km

<Water pressure test>
After the tires manufactured in Examples and Comparative Examples were assembled into rims, water was injected into the tires, and the water pressure value (tire strength) when the tires were destroyed and the mode of destruction were compared.

The water pressure value was expressed as an index with the value at which the tire of Example 2 was destroyed as 100, and the adhesion between the reinforcing cord and the resin in the belt was evaluated according to the following evaluation criteria. The larger the value, the better the durability. If it is classified as [G2], there is no practical problem, and if it is classified as [G1], it can be said to be practically preferable. Those classified as [F] lack practical durability.

[Evaluation criteria]
G1: Greater than 100 G2: Greater than 85 and less than 100 F: Less than or equal to 85

From the table in Figure 6, if the C/D range is 1.33 or more and 2.30 or less, and the B/D range is 0.08 or more and 1.00 or less, the water pressure test evaluation and drum durability test The evaluation is [A] or [B], which indicates that there is no problem in practical use.

In addition, when paying attention to C/A and E after satisfying the above conditions of C/D and B/D, if C/A is 1.99 or more and E is 0.15 mm or more, the water pressure test The evaluation in the drum durability test and the evaluation in the drum durability test were [A] or [B], indicating that there were no problems in practical use.

Furthermore, if we focus on the distance D after satisfying the above conditions C/D and B/D, if the range of distance D is 1.0 mm or more and 2.1 mm or less, the water pressure test evaluation and the drum durability test evaluation is [A] or [B], and it can be seen that there is no problem in practical use.

In addition, if we focus on distance B after satisfying the conditions of C/D and B/D above, if the range of distance B is 0.15 mm or more and 1.6 mm or less, the water pressure test evaluation and the drum durability test evaluation is [A] or [B], and it can be seen that there is no problem in practical use.

From these results, it can be seen that by satisfying at least the above conditions C/D and B/D, durability without any practical problems can be ensured.

In addition, the numerical values in the shaded columns in the comparative examples indicate that they are outside the numerical range of each condition, and are the reason for the evaluation of [F].

[Other embodiments]
Although an example of the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the above, and can be implemented with various modifications other than the above without departing from the spirit thereof. Of course there is.

DESCRIPTION OF SYMBOLS 10... Tire, 16... Carcass, 20... Bead part, 25... Tire case, 26... Belt, 27... Joining interface, 30... Reinforcement cord, 32... Resin, 34... Resin coated cord

Claims (4)

A tire case configured to include a carcass spanning from one bead part to the other bead part, and at least an outer part of the carcass in the tire width direction is covered with a rubber material;
A resin-coated cord, which is constructed by coating a plurality of reinforcing cords with resin, is spirally wound around the outer periphery of the tire case along the tire circumferential direction, and the resin-coated cords are connected to each other in the tire width direction. a belt configured by joining the adjacent resins;
Equipped with
The minimum value of the distance in the tire width direction between two reinforcing cords that are adjacent in the tire width direction without spanning the bonding interface of the resin is defined as B,
In the tire width direction cross section, the average thickness of the belt at the tire equator is C,
If the distance in the tire width direction between the two reinforcing cords that are adjacent in the tire width direction across the bonding interface of the resin is D,
A tire having a C/D range of 1.33 or more and 2.30 or less, and a B/D range of 0.08 or more and 1.00 or less. The outer diameter of the reinforcement cord is A,
If the minimum thickness of the resin from the outermost periphery of the reinforcing cord is E,
The tire according to claim 1, wherein C/A is 1.99 or more and E is 0.15 mm or more. The tire according to claim 1 or 2, wherein the distance D ranges from 1.0 mm to 2.1 mm. The tire according to any one of claims 1 to 3, wherein the distance B ranges from 0.15 mm to 1.6 mm.