JP6474265B2 - tire - Google Patents

Description

  The present invention relates to a tire mounted on a rim, and particularly relates to a tire in which at least a part of a tire case is formed of a resin material.

Conventionally, pneumatic tires made of rubber, organic fiber materials, steel members, and the like are used in vehicles such as passenger cars.
In recent years, from the viewpoint of weight reduction, ease of molding, and ease of recycling, the use of resin materials, particularly thermoplastic resins and thermoplastic elastomers, as tire materials has been studied. These thermoplastic polymer materials (such as thermoplastic elastomers and thermoplastic resin materials) have many advantages from the viewpoint of improving productivity, such as being capable of injection molding. For example, a tire manufactured using a polyolefin-based thermoplastic elastomer as the thermoplastic polymer material has been proposed (see Patent Document 1).

JP 2012-046031 A

  Tires using thermoplastic polymer materials are easier to manufacture and lower in cost than conventional rubber tires, but they are more efficient than other conventional rubber tires while increasing manufacturing efficiency. Therefore, it is required to achieve performance that is comparable to that of tires (required characteristics of tires). In particular, the polyolefin-based thermoplastic resin is advantageous as a material for the tire frame because it is inexpensive and easy to mold, but there is room for improvement from the viewpoint of suppressing deformation of the tire frame due to heat generation during running. .

  In view of the above circumstances, an object of the present invention is to provide a tire in which a tire frame body is not easily deformed even during traveling.

[1] A tire formed of a resin material containing a crosslinked polyolefin-based thermoplastic resin and having an annular tire skeleton.
[2] The tire according to [1], wherein the crosslinked polyolefin-based thermoplastic resin is a crosslinked product of a polyolefin-based thermoplastic resin having a functional group that undergoes a crosslinking reaction with water.
[3] The tire according to [1], wherein the crosslinked polyolefin-based thermoplastic resin is a crosslinked product of a polyolefin-based thermoplastic resin grafted with a hydrolyzable silane compound.
[4] The tire according to any one of [1] to [3], wherein a gel fraction of the resin contained in the resin material is 40% by mass or more.
[5] The tire according to any one of [1] to [4], wherein the resin material has a tensile modulus of elasticity of 100 MPa to 750 MPa.
[6] The tire according to any one of [1] to [5], wherein the crosslinked polyolefin-based thermoplastic resin is a crosslinked product of a polyolefin resin containing at least one of a polyethylene resin and a polypropylene resin.
[7] The tire according to any one of [1] to [6], further including a reinforcing cord member that is wound around an outer peripheral portion of the tire frame body in a circumferential direction to form a reinforcing cord layer.

  ADVANTAGE OF THE INVENTION According to this invention, the tire which a tire frame body cannot change easily during driving | running | working can be provided.

(A) is a perspective view showing a section of a part of a tire concerning one embodiment of the present invention, and (B) is a sectional view of a bead part attached to a rim. It is sectional drawing along the tire rotating shaft which shows the state by which the reinforcement cord was embed | buried under the crown part of the tire case of the tire of 1st Embodiment.

The tire of the present invention is formed of a resin material containing a crosslinked polyolefin-based thermoplastic resin and has an annular tire skeleton.
Here, in the present invention, the “crosslinked polyolefin-based thermoplastic resin” is a polyolefin-based thermoplastic resin having a crosslinked structure. The “polyolefin thermoplastic resin” is a thermoplastic resin having a polyolefin structure, and preferably a resin having an olefin as a main component (for example, 50% by mass or more) of a monomer unit.
In the present invention, the “thermoplastic resin” is a thermoplastic resin (polymer compound). The “thermoplastic resin” in the present invention includes a thermoplastic elastomer but does not include natural rubber.
Further, in the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  In the present invention, since the tire skeleton includes a crosslinked polyolefin-based thermoplastic resin as a polyolefin-based thermoplastic resin, the tire skeleton is even during traveling compared to the case where only the polyolefin-based thermoplastic resin having no crosslinked structure is used. Is difficult to deform. The reason is not clear, but is presumed as follows.

  In general, many conventional olefinic thermoplastic resins having no crosslinked structure have a low elastic modulus at high temperatures (for example, 70 ° C. or more). Therefore, when the tire skeleton is formed of an olefin-based thermoplastic resin, it is required to suppress deformation of the resin material due to heat generation during traveling, for example, deformation of the tire skeleton due to the internal pressure of the tire.

On the other hand, the crosslinked polyolefin-based thermoplastic resin used in the present invention has a molecular chain constrained by the resin itself having a crosslinked structure, so that it is more thermally than conventional olefin-based thermoplastic resins. Properties (e.g. creep resistance) are considered good. Therefore, the tire of the present invention using the crosslinked polyolefin-based thermoplastic resin for the tire skeleton is more tired even during traveling than the tire using only the polyolefin-based thermoplastic resin having no crosslinked structure for the tire skeleton. It is estimated that the deformation of the skeleton is unlikely to occur.
Hereinafter, the resin material forming the tire frame will be described.

<Resin material>
As described above, the tire of the present invention has a tire frame body using a resin material containing a crosslinked polyolefin-based thermoplastic resin.
The resin material may contain other resins other than the crosslinked polyolefin-based thermoplastic resin as necessary, and may contain components other than the resin. In addition, when the resin material does not contain components other than the resin, the resin material is formed only of the resin.

<Crosslinked polyolefin thermoplastic resin>
As described above, the crosslinked polyolefin-based thermoplastic resin is a polyolefin-based thermoplastic resin having a crosslinked structure. The crosslinked structure may be a structure in which one molecule of the thermoplastic resin is crosslinked, or may be a structure in which different molecules are crosslinked.
Examples of the cross-linked polyolefin-based thermoplastic resin include a cross-linked product in which a plurality of cross-linkable functional groups contained in a polyolefin-based thermoplastic resin having a cross-linkable functional group are combined to form a cross-linked structure (that is, a cross-linkable functional group). For example, a cross-linked polyolefin-based thermoplastic resin). Here, the plurality of crosslinkable functional groups may be present in one molecule of the resin, or may be present in different molecules. The cross-linked body only needs to have a cross-linked structure in which at least a part of the cross-linkable functional group is cross-linked, and it is not necessary that all cross-linkable functional groups form a cross-linked structure. The crosslinked body may have a crosslinkable functional group that does not form a crosslinked structure as long as the effects of the present invention are not impaired.
Hereinafter, a polyolefin-based thermoplastic resin having a crosslinkable functional group (hereinafter, sometimes referred to as “crosslinkable functional group-containing polyolefin-based thermoplastic resin”) will be described.

-Crosslinking functional group-containing polyolefin-based thermoplastic resin-
As described above, the crosslinkable functional group-containing polyolefin-based thermoplastic resin is a polyolefin-based thermoplastic resin having a crosslinkable functional group.
Examples of the crosslinkable functional group include a functional group that reacts with another crosslinkable functional group in the same molecule or in an adjacent molecule (that is, a crosslink reaction) to form a crosslink structure due to an external influence. Examples of the influence from the outside include water (moisture), electron beam, heat and the like.

  Among these, the crosslinkable functional group is preferably a functional group that undergoes a crosslinking reaction with water or an electron beam. Even if only heat is applied, the crosslinking reaction proceeds at the molding temperature (for example, in the range of 180 ° C. to 260 ° C.). Harder functional groups are more preferred. By using such a crosslinkable functional group-containing polyolefin-based thermoplastic resin having a functional group, a resin material is molded (for example, injection molding, extrusion molding, blow molding, etc.) before the crosslinking reaction proceeds, and after molding A crosslinked structure can be formed by a crosslinking reaction by water treatment or electron beam irradiation. Thus, by obtaining the tire frame containing the crosslinked polyolefin-based thermoplastic resin, it is possible to achieve both the moldability of the resin material and the shape maintenance of the tire frame during running.

-Water-crosslinkable functional group-containing polyolefin-based thermoplastic resin-
As an example of the crosslinkable functional group-containing polyolefin-based thermoplastic resin, a polyolefin-based thermoplastic resin having a functional group that crosslinks with water (hereinafter sometimes referred to as “water-crosslinkable functional group”) will be described. Here, “water” is not limited to liquid water but also includes water vapor and the like. Further, “crosslinking reaction with water” means a crosslinking reaction in the presence of liquid water, water vapor or the like (that is, moisture). Hereinafter, the polyolefin-based thermoplastic resin having a water-crosslinkable functional group may be referred to as a “water-crosslinkable functional group-containing polyolefin-based thermoplastic resin”.

  Examples of the water-crosslinkable functional group include an alkoxysilyl group (specifically, for example, a methoxysilyl group, an ethoxysilyl group, etc.), a formyloxysilyl group, and an alkylcarbonyloxysilyl group (specifically, for example, acetoxy Silyl group, propionyloxysilyl group, etc.), alkylaminosilyl group (specifically, for example, methylaminosilyl group, ethylaminosilyl group, etc.), arylaminosilyl group (specifically, for example, phenylaminosilyl group) And hydrolyzable silyl groups such as toluylaminosilyl group).

  Examples of the water-crosslinkable functional group-containing polyolefin-based thermoplastic resin include (1) a polyolefin-based thermoplastic resin modified (for example, grafted) with a compound having a water-crosslinkable functional group, and (2) a water-crosslinkable functional group. And polymers of olefinic monomers (and other olefinic monomers if necessary).

(1) Polyolefin thermoplastic resin grafted with a compound having a water-crosslinkable functional group As the compound having a water-crosslinkable functional group, for example, a compound having the water-crosslinkable functional group and the ethylenically unsaturated hydrocarbon group Is mentioned. Specific examples of the compound having a water-crosslinkable functional group include hydrolyzable silane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and (3-methacryloyloxypropyl) triethoxysilane. It is done.

Examples of the polyolefin-based thermoplastic resin before being grafted with a compound having a water-crosslinkable functional group include olefin-based monomer homopolymers, random copolymers, block copolymers, and the like. Examples of the olefin monomer include α-olefins such as propylene and ethylene; cyclic olefins such as cycloolefins; and the like.
Specific examples of the polyolefin-based thermoplastic resin include, for example, a polyethylene-based thermoplastic resin, a polypropylene-based thermoplastic resin, a polybutadiene-based thermoplastic resin, and the like. From the viewpoint of heat resistance and workability, a polyethylene-based thermoplastic resin and Polypropylene thermoplastic resins are preferred.

The polyethylene-based thermoplastic resin is a resin having ethylene as a main component of a monomer unit (for example, 50% by mass or more). Specifically, for example, an ethylene homopolymer, an ethylene-α-olefin random copolymer, ethylene -Alpha-olefin block copolymer etc. are mentioned.
The polypropylene-based thermoplastic resin is a resin having propylene as a main component of the monomer unit (for example, 50% by mass or more). Specifically, for example, a propylene homopolymer, a propylene-α-olefin random copolymer. And propylene-α-olefin block copolymers.
Examples of the α-olefin include ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1- Examples include α-olefins having about 2 to 20 carbon atoms such as heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene.

The polyolefin-based thermoplastic resin may be a polyolefin-based thermoplastic elastomer.
Examples of the “polyolefin thermoplastic elastomer” include, for example, a hard segment having a high melting point and a crystalline polyolefin, and other polymers (for example, the above-mentioned polyolefins and other polyolefins) are amorphous and have a low glass transition temperature. The material which comprises the segment is mentioned.

  Specific examples of the polyolefin-based thermoplastic elastomer include olefin-α-olefin random copolymers, olefin block copolymers, and the like. For example, propylene block copolymers, ethylene-propylene copolymers, propylene-1- Hexene copolymer, propylene-4-methyl-1-pentene copolymer, propylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-pentene copolymer, ethylene-1- Butene copolymer, 1-butene-1-hexene copolymer, 1-butene-4-methyl-pentene, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer Copolymer, ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer Ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, propylene-methacrylic acid copolymer, propylene-methyl methacrylate copolymer, propylene-ethyl methacrylate copolymer, propylene-butyl methacrylate copolymer , Propylene-methyl acrylate copolymer, propylene-ethyl acrylate copolymer, propylene-butyl acrylate copolymer, ethylene-vinyl acetate copolymer, propylene-vinyl acetate copolymer, and the like.

As a method of grafting a polyolefin-based thermoplastic resin with a compound having a water-crosslinkable functional group, a known method is used. For example, a polyolefin-based thermoplastic resin, a compound having a water-crosslinkable functional group, and a radical generator And a method of melting and kneading are used.
As temperature at the time of melt kneading, the range of 80 degreeC or more and 250 degrees C or less is mentioned, for example.
The graft amount of the water-crosslinkable functional group-containing olefinic thermoplastic resin obtained by grafting a polyolefin-based thermoplastic resin with a compound having a water-crosslinkable functional group is not particularly limited. 0.5 mass% or more and 8 mass% or less are mentioned with respect to the whole system thermoplastic resin. When the graft amount is in the range, the deformation of the tire skeleton during running is suppressed as compared with the case where the graft amount is smaller than the range, and the water-crosslinkable functional group obtained is obtained as compared with the case where the graft amount is larger than the range. The moldability of the olefinic thermoplastic resin is improved.

(2) Polymer such as olefin monomer having water crosslinkable functional group Examples of the olefin monomer having water crosslinkable functional group include general olefin monomers (for example, α-olefins such as propylene and ethylene; Cyclic olefins such as cycloolefin; etc.) in which the hydrogen atom is substituted with a water-crosslinkable functional group.
As for other monomers used as necessary, the same monomers as the above-mentioned general olefin monomers can be mentioned.
As a method for obtaining a water-crosslinkable functional group-containing polyolefin-based thermoplastic resin using an olefin-based monomer having a water-crosslinkable functional group, a method similar to a known method for synthesizing a general olefin resin is used. be able to.

-Crosslinked product of water-crosslinkable functional group-containing polyolefin-based thermoplastic resin-
The method for crosslinking the water-crosslinkable functional group-containing polyolefin-based thermoplastic resin into a crosslinked product is not particularly limited. For example, water (for example, water-crosslinkable functional group-containing polyolefin-based thermoplastic resin in the presence of a crosslinking catalyst) And liquid water, water vapor, etc.). Examples of the temperature at the time of contact between the water-crosslinkable functional group-containing polyolefin-based thermoplastic resin and water include normal temperature (25 ° C.) to 100 ° C. Examples of the contact time between the water-crosslinkable functional group-containing polyolefin-based thermoplastic resin and water include 10 seconds or more and 1 week or less.
However, since the water-crosslinkable functional group-containing polyolefin-based thermoplastic resin can react with moisture in the air to form a crosslinked structure, aggressive water treatment may not always be necessary.

Examples of the crosslinking catalyst include catalysts generally used in silanol condensation reactions. Specifically, for example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, stannous acetate, caprylic acid first Examples thereof include metal fatty acid salts such as tin, zinc caprylate, lead naphthenate and cobalt naphthenate.
Examples of the addition amount of the crosslinking catalyst include 0.000005 parts by mass to 0.05 parts by mass with respect to 100 parts by mass of the water-crosslinkable functional group-containing polyolefin thermoplastic resin, and 0.00001 parts by mass to 0 parts by mass. .01 part by mass or less is preferable.

  In the case of manufacturing a tire skeleton formed of a resin material containing a crosslinked polyolefin-based thermoplastic resin and other components other than the crosslinked polyolefin-based thermoplastic resin, the water-crosslinkable functional group before crosslinking is previously prepared before crosslinking. It is desirable to mix the other components with the group-containing polyolefin-based thermoplastic resin to obtain a mixture. And after performing injection molding etc. using the said mixture and making it into the shape of a tire frame, a crosslinked structure is formed by contact with water (for example, in addition to aggressive water treatment, leaving it in air containing water vapor). It is desirable to form.

The gel fraction of the resin contained in the resin material is preferably 40% by mass or more, more preferably 50% by mass or more, and more preferably, from the viewpoint of suppressing deformation of the tire skeleton during traveling. From the viewpoint of processability, the gel fraction of the resin is preferably 90% by mass or less. Here, the gel fraction indicates the concentration of the crosslinked structure in the entire resin contained in the resin material, and when the resin material contains other resins, the ratio of the other resins contained in the resin material As the amount increases, the value of the gel fraction decreases. The “whole resin” includes a crosslinked polyolefin-based thermoplastic resin and other resins described later, and does not include components other than the resin.
The gel fraction was measured when Soxhlet extraction was performed for 10 hours in boiling xylene at 144 ° C. on a resin component (resin component excluding components other than resin from the resin material) in a resin material containing a crosslinked polyolefin-based thermoplastic resin. This is a value calculated by measuring the dry weight of the insoluble matter and calculating the ratio (mass%) relative to the weight before Soxhlet extraction.

<Other resins>
As described above, the resin material may contain other resins other than the crosslinked polyolefin-based thermoplastic resin as necessary. For example, a thermoplastic elastomer may be added as another resin in order to adjust physical properties such as the elastic modulus of the resin material.
What is necessary is just to select suitably about the mixing ratio of crosslinked polyolefin-type thermoplastic resin and other resin according to the characteristic calculated | required. However, from the viewpoint of suppressing deformation of the tire skeleton during traveling, the ratio of the crosslinked polyolefin-based thermoplastic resin to the crosslinked polyolefin-based thermoplastic resin and other resins as a whole is preferably 50% by mass or more. 70 mass% or more is more preferable, and 90 mass% or more is particularly preferable.
The other resin is not particularly limited. For example, it is grafted with a polyolefin-based thermoplastic resin having no crosslinked structure (specifically, for example, grafted with the compound having the water-crosslinkable functional group). The same as the specific examples of the previous polyolefin-based thermoplastic resin), resins other than the polyolefin-based thermoplastic resin, and the like.

<Physical properties of resin material>
Next, the preferable physical property of the resin material which comprises a tire frame body is demonstrated. The tire frame in the present invention uses the above-mentioned resin material.
The resin material can be obtained by adding the above-mentioned crosslinked polyolefin-based thermoplastic resin and other resins and various additives as necessary, and mixing them appropriately by a known method (for example, melt mixing).
The resin material obtained by melt mixing can be used in the form of pellets if necessary.

  The tensile elastic modulus of the resin material measured in accordance with JIS K7113: 1995 is preferably 100 MPa or more and 750 MPa or less, and more preferably 200 MPa or more and 500 MPa or less, from the viewpoint of suppressing deformation of the tire skeleton during traveling.

  The amount of creep after 3 hours at 65 mm between chucks, load 4 MPa, temperature 70 ° C. measured in accordance with JIS K7115: 1999 in the resin material is 0% from the viewpoint of suppressing deformation of the tire frame body during running. The content is preferably 5% or less and more preferably 0% or more and 3% or less.

[First Embodiment]
A tire according to a first embodiment of the tire of the present invention will be described below with reference to the drawings.
The tire 10 of this embodiment will be described. FIG. 1A is a perspective view showing a partial cross section of a tire according to an embodiment of the present invention. FIG. 1B is a cross-sectional view of the bead portion attached to the rim. As shown in FIG. 1, the tire 10 of the present embodiment has a cross-sectional shape substantially similar to that of a conventional general rubber pneumatic tire.

  As shown in FIG. 1A, the tire 10 includes a pair of bead portions 12 that contact the bead seat 21 and the rim flange 22 of the rim 20 shown in FIG. A side portion 14 that extends in the tire direction, a crown portion 16 (outer peripheral portion) that connects a tire radial direction outer end of one side portion 14 and a tire radial direction outer end of the other side portion 14, and an end portion of the crown portion 16 A tire case 17 including a shoulder portion 19 connected to the side portion 14 is provided.

  Here, for the tire case 17 of the present embodiment, as a resin material, for example, a crosslinked polyolefin-based thermoplastic resin and other resins used as necessary may include those containing additives.

  In the present embodiment, the tire case 17 is formed of a single resin material. However, the present invention is not limited to this configuration, and each part of the tire case 17 is similar to a conventional general rubber pneumatic tire. You may use the thermoplastic resin material which has a different characteristic for every (side part 14, crown part 16, bead part 12, etc.). Further, a reinforcing material (polymer material, metal fiber, cord, nonwoven fabric, woven fabric, etc.) is embedded in the tire case 17 (for example, the bead portion 12, the side portion 14, the crown portion 16 and the like), and the reinforcing material is provided. The tire case 17 may be reinforced.

  The tire case 17 of the present embodiment is obtained by joining a pair of tire case halves (tire frame pieces) 17A formed of a resin material. The tire case half 17A is formed by injection molding or the like so that one bead portion 12, one side portion 14, and a half-width crown portion 16 are integrated with each other so as to face each other. It is formed by joining at the tire equator part. The tire case 17 is not limited to the one formed by joining two members, and may be formed by joining three or more members.

The tire case half 17A formed of the resin material can be formed by, for example, vacuum forming, pressure forming, injection molding, melt casting, or the like. For this reason, it is not necessary to perform vulcanization compared to the case where the tire case is molded with rubber as in the prior art, the manufacturing process can be greatly simplified, and the molding time can be omitted.
In the present embodiment, the tire case half body 17A has a symmetrical shape, that is, the one tire case half body 17A and the other tire case half body 17A have the same shape. There is also an advantage that only one type of mold is required.

  In the present embodiment, as shown in FIG. 1 (B), an annular bead core 18 made of a steel cord is embedded in the bead portion 12 as in a conventional general pneumatic tire. However, the present invention is not limited to this configuration, and the bead core 18 can be omitted if the rigidity of the bead portion 12 is ensured and there is no problem in fitting with the rim 20. In addition to the steel cord, an organic fiber cord, a resin-coated organic fiber cord, or a hard resin may be used.

  In the present embodiment, a material having a better sealing property than a resin material constituting the tire case 17 at a portion that contacts the rim 20 of the bead portion 12 or at least a portion that contacts the rim flange 22 of the rim 20, for example, rubber An annular seal layer 24 made of is formed. The seal layer 24 may also be formed at a portion where the tire case 17 (bead portion 12) and the bead sheet 21 are in contact with each other. As a material having better sealing properties than the resin material constituting the tire case 17, a softer material than the resin material constituting the tire case 17 can be used. As the rubber that can be used for the seal layer 24, it is preferable to use the same type of rubber as that used on the outer surface of the bead portion of a conventional general rubber pneumatic tire. Moreover, you may use the other thermoplastic resin (thermoplastic elastomer) which is more excellent in the sealing performance than the said resin material. Examples of such other thermoplastic resins include polyurethane resins, polyolefin resins, polystyrene thermoplastic resins, polyester resins, and the like, and blends of these resins with rubbers or elastomers. Thermoplastic elastomers can also be used, for example, polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, combinations of these elastomers, and blends with rubber. Thing etc. are mentioned.

  As shown in FIG. 1, a reinforcing cord 26 having higher rigidity than the resin material constituting the tire case 17 is wound around the crown portion 16 in the circumferential direction of the tire case 17. Examples of the material for the reinforcing cord 26 include organic fibers in addition to metals such as steel. The reinforcing cord 26 is wound spirally in a state in which at least a part thereof is embedded in the crown portion 16 in a cross-sectional view along the axial direction of the tire case 17, thereby forming a reinforcing cord layer 28. On the outer circumferential side of the reinforcing cord layer 28 in the tire radial direction, a tread 30 made of a material having higher wear resistance than the resin material constituting the tire case 17, for example, rubber, is disposed.

  The reinforcing cord layer 28 formed by the reinforcing cord 26 will be described with reference to FIG. FIG. 2 is a cross-sectional view along the tire rotation axis showing a state where a reinforcing cord is embedded in the crown portion of the tire case of the tire of the first embodiment. As shown in FIG. 2, the reinforcing cord 26 is spirally wound in a state in which at least a part is embedded in the crown portion 16 in a sectional view along the axial direction of the tire case 17. A reinforcing cord layer 28 indicated by a broken line portion in FIG. 2 is formed together with a part of the outer peripheral portion 17. The portion embedded in the crown portion 16 of the reinforcing cord 26 is in close contact with the resin material constituting the crown portion 16 (tire case 17). As the reinforcing cord 26, a monofilament (single wire) such as a metal fiber or an organic fiber, or a multifilament (twisted wire) obtained by twisting these fibers such as a steel cord twisted with a steel fiber can be used. In the present embodiment, a steel cord is used as the reinforcing cord 26.

  In FIG. 2, the burying amount L indicates the burying amount of the reinforcing cord 26 in the tire rotation axis direction with respect to the tire case 17 (crown portion 16). The embedding amount L of the reinforcing cord 26 in the crown portion 16 is preferably 1/5 or more of the diameter D of the reinforcing cord 26, and more preferably more than 1/2. Most preferably, the entire reinforcing cord 26 is embedded in the crown portion 16. When the embedment amount L of the reinforcing cord 26 exceeds 1/2 of the diameter D of the reinforcing cord 26, it is difficult to jump out of the embedded portion due to the size of the reinforcing cord 26. Further, when the entire reinforcing cord 26 is embedded in the crown portion 16, the surface (outer peripheral surface) becomes flat, and even if a member is placed on the crown portion 16 where the reinforcing cord 26 is embedded, Air can be prevented from entering. The reinforcing cord layer 28 corresponds to a belt disposed on the outer peripheral surface of the carcass of a conventional rubber pneumatic tire.

As described above, the tread 30 is disposed on the outer peripheral side of the reinforcing cord layer 28 in the tire radial direction. The rubber used for the tread 30 is preferably the same type of rubber as that used in conventional rubber pneumatic tires. Instead of the tread 30, a tread formed of another type of resin material that is more excellent in wear resistance than the resin material constituting the tire case 17 may be used. Further, the tread 30 is formed with a tread pattern including a plurality of grooves on the ground contact surface with the road surface in the same manner as a conventional rubber pneumatic tire.
Hereinafter, the manufacturing method of the tire of this embodiment is explained.

(Tire case molding process)
First, for example, as described above, a mixture containing a crosslinkable functional group-containing polyolefin-based thermoplastic resin is formed into the shape of the tire case half body 17A (hereinafter, the mixture formed into the shape of the tire case half body 17A, It may be referred to as “a tire case half before crosslinking”). The molding is preferably performed by injection molding.
Next, the pre-crosslinking tire case halves supported by the thin metal support ring face each other. Next, a joining mold (not shown) is installed so as to be in contact with the outer peripheral surface of the abutting portion of the tire case half before cross-linking. Here, the said joining metal mold | die is comprised so that the periphery of the junction part (butting part) of the tire case half body before bridge | crosslinking may be pressed with a predetermined pressure. Next, the vicinity of the joint portion of the pre-crosslinking tire case half is pressed at a temperature equal to or higher than the melting point (or softening point) of the resin constituting the pre-crosslinking tire case half. When the joint part of the tire case half before cross-linking is heated or pressurized by the joining mold, the joint part melts and the tire case half pre-cross-links fuse together, and these members are integrated into the tire case 17. A tire case before cross-linking having a shape is obtained.
In the present embodiment, the bonding portion of the pre-crosslinking tire case half was heated using a bonding mold, but the present invention is not limited to this, and for example, the bonding portion is formed by a separately provided high-frequency heater or the like. The tire case half body before crosslinking may be joined by heating or softening or melting in advance by irradiation with hot air, infrared rays, or the like, and pressurizing with a joining mold.

(Reinforcement cord member winding process)
Next, although not shown in the drawings, the heated reinforcing cord 26 is applied to the outer peripheral surface of the crown portion of the tire case before cross-linking by using a reel around which the reinforcing cord 26 is wound, a cord heating device, and a cord supply device including various rollers. By wrapping while being embedded, the reinforcing cord layer 28 can be formed on the outer peripheral side of the crown portion of the tire case before crosslinking.

(Crosslinking process)
Next, for example, a crosslinkable functional group-containing polyolefin-based thermoplastic resin contained in the tire case before crosslinking is obtained by performing a crosslinking treatment on the tire case before crosslinking on which the reinforcing cord layer 28 is formed as necessary. A tire case 17 having a reinforcing cord layer 28 is obtained by crosslinking to obtain a crosslinked polyolefin-based thermoplastic resin.

  In the present embodiment, the tire case 17 having the reinforcing cord layer 28 is obtained by joining the pre-crosslinking tire case halves, winding the reinforcing cord 26 around the outer circumferential surface of the pre-crosslinking tire case, and performing a crosslinking treatment. However, the present invention is not limited to this. For example, after the tire case half body 17A is obtained by performing a crosslinking treatment before joining the tire case half bodies before crosslinking, the tire case half body 17A is joined and reinforced cord. 26 may be wound, or the reinforcing cord 26 may be wound after obtaining the tire case 17 by performing the crosslinking treatment before the winding of the reinforcing cord 26 after the joining of the pre-crosslinking tire case half. .

  Next, a vulcanized belt-like tread 30 is wound around the outer peripheral surface of the tire case 17 for one turn, and the tread 30 is bonded to the outer peripheral surface of the tire case 17 using an adhesive or the like. In addition, the precure tread used for the retread tire conventionally known can be used for the tread 30, for example. This step is the same step as the step of bonding the precure tread to the outer peripheral surface of the base tire of the retreaded tire.

  And if the sealing layer 24 which consists of vulcanized rubber is adhere | attached on the bead part 12 of the tire case 17 using an adhesive agent etc., the tire 10 will be completed.

(Function)
In the tire 10 of this embodiment, the tire case 17 is formed of a resin material containing a crosslinked polyolefin-based thermoplastic resin. For this reason, the tire 10 of the present embodiment is unlikely to deform the tire case 17 even during traveling.

Further, in the tire 10 of the present embodiment, a reinforcing cord 26 having a rigidity higher than that of the resin material is spirally wound in the circumferential direction on the outer peripheral surface of the crown portion 16 of the tire case 17 formed of a resin material. Therefore, puncture resistance, cut resistance, and circumferential rigidity of the tire 10 are improved. In addition, creep of the tire case 17 formed of a resin material is prevented by improving the circumferential rigidity of the tire 10.
Further, in the tire 10 in which the reinforcing cord is spirally wound in the circumferential direction, the rigidity in the circumferential direction of the tire 10 is improved as described above, and therefore, the side portion 14 and the shoulder are compared with the tire having no reinforcing cord 26. It tends to be easily deformed by the pressure of air applied to the portion 19. However, in the tire 10 of this embodiment, since the tire case 17 is formed of a resin material containing a crosslinked polyolefin-based thermoplastic resin, the side portion 14 and the shoulder portion 19 are deformed while obtaining the circumferential rigidity of the tire 10. Can be suppressed.

  In addition, at least a part of the reinforcing cord 26 is embedded in the outer peripheral surface of the crown portion 16 of the tire case 17 made of a resin material in a cross-sectional view along the axial direction of the tire case 17 (cross section shown in FIG. 1). In addition, since it is in close contact with the resin material, entry of air at the time of manufacture is suppressed, and movement of the reinforcing cord 26 due to input during travel is suppressed. Thereby, it is suppressed that peeling etc. arise in the reinforcement cord 26, the tire case 17, and the tread 30, and durability of the tire 10 improves.

  And since the embedding amount L of the reinforcement cord 26 is 1/5 or more of the diameter D as shown in FIG. 2, the air entry at the time of manufacture is suppressed effectively, the input at the time of driving, etc. This further suppresses the movement of the reinforcing cord 26.

  Further, since an annular bead core 18 made of a metal material is embedded in the bead portion 12, the tire case 17, that is, the tire 10 is strong against the rim 20 like the conventional rubber pneumatic tire. Retained.

  Furthermore, since a seal layer 24 made of a rubber material having a sealing property than the resin material constituting the tire case 17 is provided at a portion of the bead portion 12 that contacts the rim 20, the tire 10 and the rim 20 The sealing performance between the two is improved. For this reason, compared with the case where it seals only with the rim | limb 20 and the resin material which comprises the tire case 17, the air leak in a tire is suppressed further. Further, the rim fit property is improved by providing the seal layer 24.

  In the first embodiment, the reinforcing cord 26 is heated. However, for example, the outer periphery of the reinforcing cord 26 may be covered with the same resin material as the tire case 17. In this case, the covering reinforcing cord is used. When the wire is wound around the crown portion 16 of the tire case 17, the resin material covered with the reinforcing cord 26 is also heated, so that the air can be effectively suppressed when being embedded in the crown portion 16.

  Further, although it is easy to manufacture the reinforcing cord 26 in a spiral manner, a method of making the reinforcing cord 26 discontinuous in the width direction is also conceivable.

  The tire 10 of the first embodiment is a so-called tubeless tire in which an air chamber is formed between the tire 10 and the rim 20 by attaching the bead portion 12 to the rim 20, but the present invention is limited to this configuration. It may be a complete tube shape.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to this.

[Examples 1 to 5, Comparative Example 1]
A tire having the same configuration as that of the first embodiment described above was formed using the materials described in the following table.
Specifically, when only one type of material described in the following table excluding the cross-linking catalyst master batch is used, it is used as a raw material, and when two or more types of materials described in the table below excluding the cross-linking catalyst master batch are used, biaxial extrusion A mixture obtained by pelletization by melt kneading (extrusion amount 15 kg / h, temperature 200 ° C., rotation speed 150 rpm) with a machine (Technobel KZW31) was used as a raw material. The obtained raw material was blended with a crosslinking catalyst masterbatch shown in the following table (if the crosslinking catalyst masterbatch was not used, the raw material was used as it was), and a tire case half body before crosslinking was obtained by injection molding. Injection molding was performed using an injection molding machine (Mitsubishi Heavy Industries, Ltd., 850-MM) under conditions of a molding temperature of 180 ° C. to 260 ° C. and a mold temperature of 50 ° C. to 70 ° C.

After joining two pre-crosslinking tire case halves to obtain a pre-crosslinking tire case, a steel reinforcing cord member is buried in the pre-crosslinking tire case to form a reinforcing cord layer, which is treated with water to reinforce the cord. A tire case (tire frame) having a layer was obtained. Specifically, the water treatment was performed by immersing a pre-crosslinking tire case having a reinforcing cord layer in 98 ° C. water for 4 hours.
The thickness of the side part in the obtained tire case was 3 mm, and the thickness of the crown part was 3 mm.
A tire was obtained by adhering a tread to a tire case having a reinforcing cord layer.

  In the table below, “Si-PP” indicates a polypropylene resin grafted with a hydrolyzable silane compound (Linklon XPM800MH, manufactured by Mitsubishi Chemical Corporation), and “Si-PE1” is a hydrolyzable silane compound. A grafted polyethylene resin (Mitsubishi Chemical Corporation, Linkron HM600A (containing a crosslinking catalyst)) is shown, and “Si-PE2” is a polyethylene resin grafted with a hydrolyzable silane compound (Mitsubishi Chemical Corporation, "Linkron Catalyst Masterbatch 1" indicates a polyolefin resin mixed with a crosslinking catalyst (Mitsubishi Chemical Co., Ltd., Linkron PZ010), and "Crosslinking Catalyst Masterbatch 2" indicates that a crosslinking catalyst is mixed. Polyolefin resin (Mitsubishi Chemical Co., Ltd., Linkron LZ033) "Refin copolymer 1" indicates a polyolefin-based thermoplastic elastomer having no crosslinkable functional group (Tafmer PN3560 manufactured by Mitsui Chemicals, Inc.), and "PE" is a polyethylene resin having no crosslinkable functional group (Tosoh Corporation) “TPO” indicates a polyolefin-based thermoplastic elastomer having no crosslinkable functional group (Prime TPO F-3740, manufactured by Prime Polymer Co., Ltd.).

[Comparative Examples 2-3]
Tires of Comparative Example 2 and Comparative Example 3 were obtained in the same manner as Example 2 and Example 5, respectively, except that the cross-linking catalyst master batch was not added and water treatment was not performed. In addition, after tire manufacture, it stored so that the water | moisture content in air might not be touched, and the following measurement and evaluation were performed without taking time.

[Measurement of tensile modulus]
In the examples and comparative examples, the resin material of the tire case was punched out to produce a dumbbell-shaped sample piece (No. 3 type sample piece) defined in JIS-K6251: 1993.
Next, using a Shimadzu Autograph AGS-J (5KN) manufactured by Shimadzu Corporation, the tensile speed was set to 200 mm / min. According to JIS K7113: 1995, each dumbbell-shaped sample piece was pulled at 23 ° C. The elastic modulus was measured. The results are shown in the table below.

[Measurement of creep amount]
In the examples and comparative examples, the resin material of the tire case was punched out to produce a dumbbell-shaped sample piece (No. 3 type sample piece) defined in JIS-K6251: 1993.
Next, using a creep tester (manufactured by Yasuda Seiki Seisakusho, model number: 145) as a measuring device, the creep amount after 3 hours at a chuck of 65 mm, a load of 4 MPa, and a temperature of 70 ° C. was measured according to JIS K7115: 1999. . The results are shown in the table below.

[Measurement of gel fraction]
About the resin material of the tire case of Examples 1-5, the gel fraction was measured by the above-mentioned method. The results are shown in the table below.

[Evaluation of tire running performance]
About the tire obtained by the Example and the comparative example, the high-speed performance test was done according to JISD4230: 1999 (high-speed performance test B). The results are shown in the table below.

[Evaluation of shape retention]
The tires obtained in Examples and Comparative Examples were subjected to the following measurements in order to evaluate the shape retention in the tread portion circumferential direction and the side portion thickness direction of the tire during traveling. Specifically, for the shape retentivity in the tread portion circumferential direction, the change in the tire outer peripheral length of the tread central portion before and after traveling was evaluated. About the shape retainability of the side part thickness direction, the change before and behind driving | running | working of the tire width length containing a tread part and a side part was evaluated. The results are shown in the table below.

  As can be seen from the evaluation results shown in the above table, this example has a tire skeleton formed of a resin material containing a cross-linked polyolefin-based thermoplastic resin, and therefore has shape retention during running as compared to the comparative example. It was found that the deformation of the tire frame was difficult to occur.

10 tires, 12 bead portions, 16 crown portions (outer peripheral portions), 17 tire cases (tire frame bodies), 18 bead cores, 19 shoulder portions, 20 rims, 21 bead seats, 22 rim flanges, 24 seal layers (seal portions), 26 Reinforcement cord (reinforcement cord member), 28 Reinforcement cord layer, 30 tread, D Reinforcement cord diameter (reinforcement cord member diameter), L Reinforcement cord embedding amount (reinforcement cord member embedding amount)

Claims (7)

Formed of a resin material containing a crosslinked polyolefin-based thermoplastic resins and have a tire skeleton of the cyclic, the crosslinked polyolefin-based thermoplastic resin is a crosslinked product of a polyolefin-based thermoplastic resin having a functional group capable of crosslinking reaction with water A tire. A crosslinked thermoplastic polyolefin resin grafted with a hydrolyzable silane compound, which is formed of a resin material containing a crosslinked polyolefin thermoplastic resin and has a cyclic tire skeleton. der filter hate. A tire which is formed of a resin material containing a crosslinked polyolefin-based thermoplastic resin and has an annular tire skeleton, and the gel fraction of the resin contained in the resin material is 40% by mass or more. The tire according to claim 1 or 2 , wherein a gel fraction of the resin contained in the resin material is 40% by mass or more.   The tire according to any one of claims 1 to 4, wherein the resin material has a tensile modulus of 100 MPa or more and 750 MPa or less.   The tire according to any one of claims 1 to 5, wherein the crosslinked polyolefin-based thermoplastic resin is a crosslinked product of a polyolefin resin containing at least one of a polyethylene resin and a polypropylene resin.   The tire according to any one of claims 1 to 6, further comprising a reinforcing cord member that is wound in a circumferential direction on an outer peripheral portion of the tire frame body to form a reinforcing cord layer.