Tire and method for manufacturing tire

Abstract

To provide a tire capable of improving productivity.SOLUTION: In the tire, an injection-molded resin directly welded to a tread rubber layer and a belt layer is interposed between the tread rubber layer and the belt layer including a resin-coated cord, and the thickness of the resin between the cord and the tread rubber layer is thicker than the thickness of the resin positioned on the opposite side of the tread rubber layer of the cord.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to tires and methods for manufacturing tires. [Background technology]

[0002] For example, a tire described in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2014129380 publication Summary of the Invention [Problem to be solved by the invention]

[0004] In the tire of Patent Document 1, a resin layer, a reinforcing cord layer, and a rubber layer are integrated together. The resin layer, reinforcing cord layer, and rubber layer are each bonded together by adhesive, which makes the manufacturing process complicated and leaves room for improvement in productivity.

[0005] In consideration of the above, the present disclosure has an object to provide a tire and a tire manufacturing method that enable improved productivity. [Means for solving the problem]

[0006] In the tire according to the first aspect, an injection-molded resin is interposed between a tread rubber layer and a belt layer including resin-coated cords, and the injection-molded resin is directly welded to the tread rubber layer and the belt layer, and the resin thickness between the cords and the tread rubber layer is thicker than the resin thickness on the opposite side of the cords from the tread rubber layer.

[0007] In the tire according to the first aspect, injection-molded resin is interposed between the tread rubber layer and the belt layer, and the tread rubber layer and the resin are directly welded together, and the belt layer and the resin are directly welded together. This makes it possible to improve productivity of the tire compared to tires in which the tread rubber layer and the resin are bonded together with an adhesive, and the belt layer and the resin are bonded together with an adhesive. Furthermore, by increasing the thickness of the resin between the tread rubber layer and the cords, the force acting from the tread side of the tread rubber layer is less likely to be applied directly to the ends of the cords, thereby suppressing peeling and damage to the resin around the ends of the cords located at the ends of the belt.

[0008] In the tire manufacturing method according to the second aspect, a tire is formed by injecting a thermoplastic resin between a tread rubber layer and a belt layer including cords.

[0009] In the tire manufacturing method according to the second aspect, a tire having a three-layer structure consisting of a tread rubber layer, a resin layer made of the injected resin, and a belt layer is obtained by injection molding a resin between the tread rubber layer and the belt layer. The tread rubber layer and the injected resin are welded together, and the belt layer and the injected resin are welded together, so tire productivity can be improved compared to when the tread rubber layer and the belt layer are bonded to the resin layer with an adhesive.

[0010] A tire manufacturing method according to a third aspect is the tire manufacturing method according to the second aspect, wherein the cord is coated with the same type of thermoplastic resin as the thermoplastic resin used for injection molding.

[0011] In the tire manufacturing method according to the third aspect, the cords of the belt layer are coated with the same type of thermoplastic resin as the thermoplastic resin used for injection molding, which improves the weldability between the thermoplastic resin coating the cords and the injected thermoplastic resin, i.e., improves the bonding strength between the belt layer and the injected thermoplastic resin.

[0012] A tire manufacturing method according to a fourth aspect is the tire manufacturing method according to the second or third aspect, wherein the thermoplastic resin used for injection molding is a polyester-based resin or a polyester-based thermoplastic elastomer.

[0013] In the tire manufacturing method according to the fourth aspect, the thermoplastic resin used for injection molding is a polyester resin or a polyester thermoplastic elastomer, which is excellent in strength and easy to injection mold, thereby making it possible to obtain a tire with high strength and improve tire productivity.

[0014] A tire manufacturing method according to a fifth aspect is the tire manufacturing method according to any one of the second to fourth aspects, wherein the tread rubber layer is surface-treated with a chlorination treatment agent at a portion that comes into contact with the thermoplastic resin to be injection-molded.

[0015] In the tire manufacturing method according to the fifth aspect, the surface of the tread rubber layer that comes into contact with the resin to be injection-molded is surface-treated with a chlorination treatment agent, and therefore the bonding strength between the resin and the tread rubber layer can be increased compared to when the surface is not treated. [Effects of the Invention]

[0016] As described above, the tire and tire manufacturing method of the present disclosure can improve productivity. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a tire according to an embodiment of the present disclosure taken along a tire rotation axis. [Figure 2] FIG. [Figure 3] FIG. 2 is an enlarged cross-sectional view showing the vicinity of a belt end. [Figure 4] FIG. 2 is a cross-sectional view showing a mold for molding a tire. [Figure 5] FIG. 2 is a cross-sectional view of a mold in which a tread rubber layer, a belt layer, and a rubber chafer are arranged as tire components. DETAILED DESCRIPTION OF THE INVENTION

[0018] A tire 10 according to an embodiment of the present disclosure will be described with reference to FIGS. As shown in FIG. 1, a tire 10 of this embodiment is, as an example, a so-called pneumatic tire that is mounted on a rim and filled with air, and has a cross-sectional shape substantially similar to that of a conventional pneumatic tire.

[0019] The tire 10 includes a tire frame member 18 made of resin, which includes a pair of bead portions 12, side portions 14 extending radially outward from the bead portions 12, and a crown portion 16 connecting one side portion 14 to the other side portion 14. The tire frame member 18 is formed from a thermoplastic resin 19, which is an example of a resin in the present disclosure, and details of the thermoplastic resin 19 will be described later.

[0020] The bead portion 12 is a portion that fits onto a rim (not shown). The side portion 14 is a portion that constitutes the side of the tire 10, and is gently curved so as to be convex outward in the tire width direction from the bead portion 12 toward the crown portion 16. The crown portion 16 is a portion that supports a tread rubber layer 34, which is an example of a rubber layer described below, that is disposed on the outer side in the tire radial direction, and in this embodiment, the outer peripheral surface is formed flat along the tire width direction.

[0021] An annular bead core 20, which is an example of a reinforcing layer, is embedded inside the bead portion 12. As shown in Fig. 2, the bead core 20 has an annularly wound cord 22 made of metal (e.g., steel), organic fiber, or the like, coated with resin, which in this embodiment is thermoplastic resin 24. The thermoplastic resin 24 used in the bead core 20 will be described in detail later.

[0022] 1, rubber chafers 26, which are an example of a rubber layer made of vulcanized rubber, are provided on the axially outer surface and radially inner surface of the bead portion 12 in contact with the rim (not shown). The rubber chafers 26 are welded to the tire frame member 18 and are integrated with the tire frame member 18.

[0023] A belt layer 28, which is an example of a reinforcing layer, is provided on the inner periphery of the crown portion 16. As shown in FIG. 3, the belt layer 28 is formed by, for example, spirally wound cords 30 made of metal (e.g., steel), organic fiber, or the like, which are coated with resin, which in this embodiment is a thermoplastic resin 32. As an example, the belt layer 28 in this embodiment has a cylindrical shape with a constant diameter. As shown in FIGS. 1 and 3, the outer circumferential surface and widthwise end surfaces of the belt layer 28 are welded to the tire frame member 18. The thermoplastic resin 32 used in the belt layer 28 will be described in detail later.

[0024] As shown in FIG. 1, a tread rubber layer 34 made of vulcanized rubber that forms the tread portion of the tire 10 is bonded to the outer periphery of the crown portion 16 of the tire frame member 18.

[0025] The tread rubber layer 34 has a flat inner peripheral surface and an outer peripheral surface that is gently curved so as to be convex radially outward. A tread pattern (not shown) is formed on the outer peripheral surface of the tread rubber layer 34.

[0026] A plurality of protrusions 34A formed at a constant height are provided at intervals on the inner peripheral surface of the tread rubber layer 34 so as to maintain a constant distance from the belt layer 28. The tips of the protrusions 34A abut against the outer peripheral surface of the belt layer 28.

[0027] As shown in FIG. 3, a resin thickness t1 between the tread rubber layer and the cords 30 of the belt layer is greater than a resin thickness t2 on the opposite side of the cords 30 from the tread rubber layer .

[0028] (thermoplastic resin) Next, the thermoplastic resin 19 used in the tire frame member 18, the thermoplastic resin 24 used in the bead core 20, and the thermoplastic resin 32 used in the belt layer 28 will be described below.

[0029] Thermoplastic resins (including thermoplastic elastomers) are polymeric compounds that soften and flow as the temperature rises, and become relatively hard and strong when cooled.

[0030] Examples of thermoplastic resins (including thermoplastic elastomers) include polyolefin thermoplastic elastomers (TPO), polystyrene thermoplastic elastomers (TPS), polyamide thermoplastic elastomers (TPA), polyurethane thermoplastic elastomers (TPU), polyester thermoplastic elastomers (TPC), and dynamically crosslinked thermoplastic elastomers (TPV), as well as polyolefin thermoplastic resins, polystyrene thermoplastic resins, polyamide thermoplastic resins, and polyester thermoplastic resins.

[0031] The thermoplastic material may have a deflection temperature under load (under a load of 0.45 MPa) of 78°C or higher as specified in ISO 75-2 or ASTM D648, a tensile yield strength of 10 MPa or higher as specified in JIS K7113, a tensile elongation at break of 50% or higher as specified in JIS K7113, and a Vicat softening temperature (method A) of 130°C as specified in JIS K7206. Note that a polyester resin may be used instead of the polyester thermoplastic elastomer (TPC).

[0032] In this embodiment, the thermoplastic resin 19, the thermoplastic resin 24, and the thermoplastic resin 32 are made of a polyester thermoplastic elastomer (TPC).

[0033] (Mold) 4 shows a cross-sectional view of a mold 40 for molding the tire 10 of this embodiment. The mold 40 is configured to include an outer mold 42 for molding the outer surface side of the tire, and an inner mold (core) 44 for molding the inner surface side of the tire. A cavity S (space) for molding the tire 10 is formed between the outer mold 42 and the inner mold 44.

[0034] The outer mold 42 is provided with gates 46 at positions facing both widthwise ends of the crown portion 16 of the tire frame member 18. The inner mold 44 is formed with protruding holding portions 44A that hold the bead cores 20.

[0035] Next, a manufacturing process of the tire 10 of this embodiment will be described. (1) First, as shown in FIG. 5, the tread rubber layer 34, the belt layer 28, and the rubber chafer 26 are placed in predetermined positions in the cavity S of the mold 40. A plurality of protruding supports 26A are formed along the circumferential direction on the inner periphery of the rubber chafer 26 to sandwich and support the bead core 20 between the rubber chafer 26 and the holding portion 44A of the inner mold 44.

[0036] In the tread rubber layer 34 and the rubber chafer 26, the portions that come into contact with the thermoplastic resin that forms the tire frame member 18 have their surfaces treated with a chlorination treatment agent, for example.

[0037] (Surface treatment with chlorination agent) In the treatment with a chlorination treating agent, for example, the chlorination treating agent is applied to the surface of the rubber composition by immersion, wiping, dropping or the like, and then dried as necessary. The temperature at the time of application of the chlorination treatment agent is, for example, 18°C ​​to 25°C. When the chlorination treatment agent is applied by immersion, the immersion time varies depending on the chlorine concentration of the chlorination treatment agent, but is, for example, 30 seconds to 10 hours, and preferably 1 minute to 5 hours. When drying is carried out after application of the chlorination treatment agent, the drying temperature may be, for example, 15° C. to 40° C., and the drying time may be, for example, 3 minutes to 300 minutes.

[0038] Examples of the chlorination agent include solvent-based chlorination agents and aqueous chlorination agents. Examples of solvent-based chlorination agents include solutions in which a chlorinating agent such as a chlorinated cyanuric acid, e.g., dichloroisocyanuric acid or trichloroisocyanuric acid, is dissolved in an organic solvent. Examples of organic solvents include ethyl acetate and acetone. Among these, a solution of trichloroisocyanuric acid in ethyl acetate is preferred as the solvent-based chlorination agent from the viewpoint of improving adhesion.

[0039] Examples of aqueous chlorination agents include aqueous solutions of chlorinating agents such as chlorinated cyanurates (e.g., sodium dichloroisocyanurate, sodium trichloroisocyanurate), chlorites (e.g., chlorous acid, sodium chlorite), hypochlorites (e.g., hypochlorous acid, sodium hypochlorite), chlorate (e.g., chloric acid, sodium chlorate), and perchlorates (e.g., sodium perchlorate) dissolved in water. Among these aqueous chlorination agents, an aqueous sodium hypochlorite solution is preferred from the viewpoints of solubility in water and ease of handling. The aqueous chlorination agent may further contain an acid (e.g., hydrochloric acid) to adjust the pH. The pH of the aqueous chlorination agent is preferably in the range of 1.8 to 6.0 from the viewpoints of the hypochlorous acid content and stability.

[0040] The chlorine concentration in the chlorination treatment agent is, for example, in the range of 1500 ppm by mass to 6500 ppm by mass, and preferably in the range of 2500 ppm by mass to 6000 ppm by mass. The chlorine concentration in the chlorination treatment agent can be measured using a commercially available water quality meter or residual chlorine meter after diluting it with the solvent or water used.

[0041] The amount of surface chlorine on the contact surface of the rubber layer is 1.8 wt% to 22 wt%, and from the viewpoint of improving adhesion, it is preferably 2.7 wt% to 19 wt%, and more preferably 3.5 wt% to 16 wt%.

[0042] The amount of surface chlorine is determined by energy dispersive X-ray analysis (EDX). Specifically, using a tabletop microscope (Hitachi High-Technologies, Miniscope TM3030Plus) equipped with the analytical equipment QUANTAX70 (BRUKER), the surface to be measured is irradiated with an electron beam at an accelerating voltage of 15 kV and a focal length (WD) of 9 mm, and analysis is performed under conditions of observation magnification of 600x, detection time of 60 seconds, and detection area of ​​200 μmΦ. In the obtained EDX scattered X-ray spectrum, the intensity of the Kα line of Cl (chlorine) at a detection energy of 2.6228 keV is measured, and the amount of surface chlorine is determined by calculating the weight percentage of Cl (chlorine) atoms relative to the weight of all atoms present on the surface from analysis of the detected spectrum. When quantifying the amount of surface chlorine on the contact surface of the rubber layer in the laminate, for example, the laminate may be cut in a direction perpendicular to the contact surface and the above measurement may be carried out on the cross section.

[0043] When the contact surface is a surface treated with a chlorination treatment agent, methods for controlling the surface chlorine content within the above range include a method of selecting the type of chlorination treatment agent, a method of adjusting the concentration of the chlorination treatment agent, the treatment time, the number of treatments, etc., and a combination of these. Furthermore, by having the amount of surface chlorine at the contact surface of the rubber layer within the above range, the movement of the main chain of the rubber contained in the rubber layer is less likely to be hindered by chlorine than when the amount is greater than the above range. Here, if the movement of the main chain of the rubber is hindered by chlorine, the contact surface of the rubber layer behaves hard, and the contact surface is more likely to be broken when the laminate is deformed, which may result in a decrease in adhesion between the resin layer and the rubber layer. Therefore, it is believed that by having the amount of surface chlorine at the contact surface of the rubber layer within the above range, the decrease in adhesion caused by the movement of the main chain of the rubber being hindered by chlorine is suppressed, resulting in excellent adhesion between the resin layer and the rubber layer. For the above reasons, it is presumed that the laminate of this embodiment has excellent adhesion between the resin layer and the rubber layer.

[0044] (2) Molten thermoplastic resin 19 for forming the tire frame member 18 is injected into the cavity S in which the tread rubber layer 34, the belt layer 28, the rubber chafers 26, and the bead cores 20 are arranged.

[0045] In the tire 10 of the present embodiment, the rubber surfaces of the tread rubber layer 34 and the rubber chafer 26 that come into contact with the thermoplastic resin 19 are treated with a chlorination treatment agent, and therefore the tread rubber layer 34 and the rubber chafer 26, which are vulcanized rubber, can be directly and firmly bonded (joined) to the thermoplastic resin 19 that forms the tire frame member 18, compared to when they are not treated with a chlorination treatment agent. Here, "directly bonded" means that the rubber member and the thermoplastic resin are in direct contact with each other and are joined without any adhesive or the like interposed between them.

[0046] In this embodiment, the belt layer 28, the rubber chafer 26, and the bead core 20 are brought into contact with the molten thermoplastic resin 19 that forms the tire frame member 18, thereby bonding the belt layer 28, the rubber chafer 26, and the bead core 20 to the thermoplastic resin 19. This improves productivity compared to the case where the belt layer 28, the rubber chafer 26, and the bead core 20 are bonded to the tire frame member 18 that has been molded in advance (hardened thermoplastic resin) using an adhesive.

[0047] As shown in FIG. 3, in the tire 10 of this embodiment, the resin thickness dimension t1 between the tread rubber layer 34 and the cords 30 of the belt layer 28 is set to be thicker than the resin thickness dimension t2 of the cords 30 on the side opposite to the tread rubber layer 34. This increases the distance from the tread rubber layer 34 to the ends of the cords 30 of the belt layer 28 (ends in the longitudinal direction of the cords; cut ends of the cords). This makes it difficult for forces acting from the tread surface side of the tread rubber layer 34 to act near the ends of the cords 30, thereby suppressing peeling and damage to the resin (thermoplastic resin 19, thermoplastic resin 32) around the ends of the cords 30.

[0048] From the viewpoint of bonding strength, it is preferable that the thermoplastic resin 24 used in the bead cores 20 and the thermoplastic resin 32 used in the belt layers 28 be the same type of thermoplastic resin as the thermoplastic resin 19 used in the tire frame member 18. However, the present disclosure is not limited to this configuration, and the thermoplastic resin 24 used in the bead cores 20 and the thermoplastic resin 32 used in the belt layers 28 may be a resin material different from the thermoplastic resin 19 used in the tire frame member 18.

[0049] [Other embodiments] The above describes one embodiment of the present disclosure, but the present disclosure is not limited to the above, and it goes without saying that various modifications can be made to the present disclosure without departing from the spirit of the present disclosure.

[0050] The tire 10 in the above embodiment is a so-called pneumatic tire that is filled with air when used, but the tire 10 may also be a tire that is not filled with air. An example of a tire that is not filled with air inside is a type in which the crown portion is supported on the rim via radially extending resin spokes instead of the tire side portions and bead portions. [Explanation of symbols]

[0051] 10... Tire, 19... Thermoplastic resin (resin), 28... Belt layer (reinforcing layer), 30... Cord, 34... Tread rubber layer (rubber layer)

Claims

1. an injection-molded resin layer is interposed between a tread rubber layer and a belt layer including resin-coated cords, and the injection-molded resin layer is directly welded to the tread rubber layer and the belt layer; a resin thickness between the cord and the tread rubber layer is thicker than a resin thickness on an opposite side of the cord from the tread rubber layer; tire.

2. A thermoplastic resin is injected between the tread rubber layer and the belt layer including the cords to form a tire. Tire manufacturing method.

3. The cord is coated with the same type of thermoplastic resin as the thermoplastic resin to be injection molded. A method for manufacturing a tire according to claim 2.

4. The thermoplastic resin to be injection molded is a polyester-based resin or a polyester-based thermoplastic elastomer. The method for manufacturing a tire according to claim 2 or 3.

5. the tread rubber layer is surface-treated with a chlorination treatment agent at a portion that comes into contact with the thermoplastic resin to be injection-molded; A method for manufacturing a tire according to claim 4.

Images