JP6850667B2 - tire - Google Patents

Description

The present invention relates to a tire.

In recent years, tires having a skeleton body made of a resin material (hereinafter, also referred to as a tire skeleton body) have been developed for reasons such as weight reduction, ease of molding, and ease of recycling. As an attempt to improve the durability of such a tire, a method of reinforcing the tire skeleton by using a reinforcing cord has been proposed.
For example, Patent Document 1 proposes a method of winding a reinforcing cord member in the circumferential direction around an outer peripheral portion of a resin tire skeleton body.

Japanese Unexamined Patent Publication No. 2012-46030

The tire described in Patent Document 1 has improved durability during running as compared with a conventional tire, but further improvement in durability is desired in terms of performance required for the tire. Further, from the viewpoint of weight reduction and cost, it is desirable that the thickness of the tire skeleton is thin, but if the thickness is reduced, the gas barrier property against air or the like tends to decrease, and the skeleton becomes vulcanized after the rubber material is vulcanized. It may be deformed. On the other hand, if the thickness is increased, the durability during running tends to decrease.

Based on the above circumstances, it is an object of the present invention to provide a tire having improved gas barrier properties, deformation resistance to heating, and running durability while suppressing the overall thickness, weight, and cost.

[1] A pair of bead portions, a pair of side portions extending outward in the tire radial direction from the bead portion, and a crown portion connected to the inside of the side portion in the tire width direction are provided.
An annular tire skeleton containing a resin material and
A coated rubber layer containing rubber and arranged at least on the side portion of the tire skeleton body,
It contains rubber and has a side rubber layer arranged on the side portion of the tire skeleton body via the covering rubber layer.
The difference between the maximum thickness of the tire skeleton and the minimum thickness of the tire skeleton from the maximum bending portion on one side portion to the maximum bending portion on the other side portion is 0.1 mm or less.
In the side portion, the thickness D1 of the maximum bent portion of the tire skeleton is 0.5 mm or more and 2.5 mm or less, and the thickness D2 of the maximum bent portion of the side rubber layer exceeds 1.0 mm and 5.0 mm or less. , and the said tire frame body, wherein of the total thickness of the coating rubber layer and the side rubber layer, the gas permeability of the portion of the minimum thickness D3 is a ^{18 × 10 -14 mol / (m} 2 · s · Pa) or less ,tire.
[2] The tire according to [1], wherein the resin material contains 50% by mass or more of a polyamide-based thermoplastic elastomer.
[3] The tire according to [1] or [2], wherein in the portion having the minimum thickness D3, the gas permeability of the portion composed of the coated rubber layer and the side rubber layer is equal to or less than the gas permeability of the tire skeleton. ..
[4] The tire according to any one of [1] to [3], wherein the thickness D1 is 1.0 mm or more and 2.4 mm or less.

According to the present invention, it is possible to provide a tire having improved gas barrier properties, deformation resistance to heating, and running durability while suppressing the overall thickness, weight, and cost.

It is sectional drawing along the tire width direction which shows the structure of the tire which concerns on one Embodiment of this invention. FIG. 5 is an enlarged cross-sectional view of a bead portion and a side portion of the tire shown in FIG. It is a graph which shows the relationship between the gas permeability in the thinnest part of a side part, and the thickness of a tire skeleton body.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and the present invention is carried out with appropriate modifications within the scope of the object of the present invention. be able to.

In the present specification, the "bead portion" means from the inner end in the tire radial direction to 30% of the tire cross-sectional height. The "side portion" means from the bead portion to the end of the crown portion. Here, the "edge of the crown" means that the tire is attached to the standard rim specified in JATMA YEAR BOOK (2014 version, Japan Automobile Tire Association standard), and the applicable size and ply rating in JATMA YEAR BOOK. It is filled with 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity (internal pressure-bold load in the load capacity correspondence table) as the internal pressure, and refers to the outermost ground contact portion in the tire width direction when the maximum load capacity is loaded. If the TRA standard or ETRTO standard is applied at the place of use or manufacturing, follow each standard.
Here, FIG. 1 shows a cross-sectional view along the tire width direction showing the configuration of the tire according to the embodiment of the present invention. In the tire 100 shown in FIG. 1, the bead portion corresponds to 12, the side portion corresponds to 14, and the crown portion corresponds to 16. Details will be described later.
Further, in the present specification, the term "resin" is a concept including a thermoplastic resin and a thermosetting resin, but does not include vulcanized rubber such as natural rubber and synthetic rubber.
"Rubber" is a polymeric compound with elasticity, but is distinguished herein from thermoplastic resin elastomers.
The "thermoplastic resin" refers to a polymer compound in which a material softens as the temperature rises and becomes relatively hard and strong when cooled, and is a concept including a thermoplastic elastomer. The "thermoplastic resin elastomer" is a polymer compound having elasticity, which is crystalline and constitutes a hard segment having a high melting point or a hard segment having a high cohesive force, and is amorphous and has a low glass transition temperature. It means a thermoplastic resin having a polymer constituting a soft segment.
In the thermoplastic resin elastomer, the hard segment behaves as a pseudo cross-linking point and exhibits elasticity (so-called physical cross-linking). On the other hand, rubber has a double bond in the molecular chain, and by adding sulfur or the like and cross-linking (vulcanization), a three-dimensional network structure is generated and elasticity is exhibited (chemical cross-linking). .. Therefore, in the thermoplastic resin elastomer, the hard segment is melted by heating, and a pseudo cross-linking point is formed again by cooling.
In addition, the numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
Further, the term "process" is included in this term as long as the intended purpose of the process is achieved, not only in an independent process but also in a case where it cannot be clearly distinguished from other processes.

[tire]
The tire of the present invention includes a pair of bead portions, a pair of side portions extending outward in the tire radial direction from the bead portion, and a crown portion connected to the inside of the side portion in the tire width direction.
An annular tire skeleton containing a resin material and
A coated rubber layer containing rubber and arranged at least on the side portion of the tire skeleton body,
It contains rubber and has a side rubber layer arranged on the side portion of the tire skeleton body via the covering rubber layer.
Further, the tire of the present invention satisfies the following conditions 1 to 4.
Condition 1: The difference between the maximum thickness and the minimum thickness of the tire skeleton from the maximum bending portion on one side portion of the tire skeleton portion to the maximum bending portion on the other side portion (hereinafter, "the tire skeleton body". The difference between the maximum thickness and the minimum thickness between the maximum bent portions ”) is 0.1 mm or less.
Condition 2: The thickness D1 of the maximum bent portion in the side portion of the tire skeleton is 0.5 mm or more and 2.5 mm or less.
Condition 3: The thickness D2 of the maximum bent portion of the side rubber layer is more than 1.0 mm and 5.0 mm or less.
Condition 4: In the side portion, tire frame body, covering the rubber layer and of the total thickness of the side rubber layer, a gas permeability of the portion of the minimum thickness D3 is ^{18 × 10 -14 mol / (m} 2 · s · Pa) or less is there.

Here, the maximum bending portion refers to a portion where the tire is bent and the amount of deformation is maximized when the tire is assembled to the standard rim of the JATTA standard and the internal pressure is set to the standard air pressure.
The maximum bent portion is specified by the following method. In the side portion of the cross section in the tire width direction, a group of regions at regular intervals in which the inner peripheral surface (contour) of the tire skeleton is divided at intervals of 0.5 cm is specified, and the radius of curvature in each region is measured. Of the measured radius of curvature, the portion having the smallest radius of curvature is defined as the maximum bending portion of the tire skeleton (the inner peripheral side of the tire skeleton).
The thickness D1 of the maximum bending portion of the tire skeleton is the distance between the inner peripheral surface and the outer peripheral surface of the tire skeleton measured on a normal line perpendicular to the tangent line passing through the maximum bending portion of the tire skeleton. To do.
The thickness D2 of the maximum bent portion of the side rubber layer is the distance between the inner peripheral surface and the outer peripheral surface of the side rubber layer measured on a normal line perpendicular to the tangent line passing through the maximum bent portion of the tire skeleton.
The thickness D1 of the maximum bent portion and the thickness D2 of the maximum bent portion can be measured by a known method. Specifically, it is possible to actually measure the tire cross section obtained by cutting in the tire width direction using a scale.

The minimum thickness D3 of the total thickness of the tire skeleton, the covering rubber layer and the side rubber layer is the tire skeleton and the covering measured in a state where the internal pressure is set to the standard air pressure by assembling to the standard rim of the JATTA standard. Of the total thickness of the rubber layer and the side rubber layer, the portion where the total thickness is the minimum (hereinafter, also referred to as "the thinnest part of the side portion").
The thinnest part of the side portion (that is, the portion having the minimum thickness D3) is specified by the following method.
At the side portion of the cross section in the tire width direction, the total thickness is measured at intervals of 0.5 cm along the inner peripheral surface (contour) of the tire skeleton body. Of the total measured thickness, the portion where the total thickness is the smallest is defined as the thinnest part of the side portion. The total thickness and the minimum thickness D3 can be measured by the same method as the maximum bending portion thickness D1 and the maximum bending portion thickness D2.

The gas permeability in the thinnest part of the side portion is measured by the following method.
A test piece having a laminated structure similar to that of the thinnest laminated structure (tire skeleton, coated rubber layer and side rubber layer) was prepared, and the test piece was used to make JIS K7126-1: 2006 (Part 1: Difference). It can be measured by the pressure method).
Further, the gas permeability of the tire skeleton, the gas permeability of the coated rubber layer, the gas permeability of the side rubber layer, and the gas permeability of the coated rubber layer and the side rubber layer are test pieces having the same structure as each structure. It can be prepared and measured by the same method as described above using the test piece. The same applies when the tire skeleton has an inner rubber layer.

Here, a tire having a tire skeleton body including a resin skeleton body (hereinafter, also referred to as a resin skeleton body) is compared with a conventional tire having a skeleton body formed of rubber (hereinafter, also referred to as a “rubber skeleton body”). It is expected that the weight will be reduced to improve fuel performance and recyclability. On the other hand, in order to produce a resin skeleton that satisfies the running durability required for a tire, it is necessary to use a highly functional resin material, which increases the manufacturing cost. As a method for suppressing the manufacturing cost, a method of reducing the amount of resin used can be mentioned. Specific examples thereof include a method of using a blend material of rubber and resin for the skeleton body and a method of reducing the thickness of the skeleton body. However, the former method tends to reduce the bending durability of the tire. Further, in the latter method, since the thickness of the skeleton is reduced, the gas barrier property is likely to be lowered as compared with the rubber skeleton, and the skeleton may be deformed after the rubber material is vulcanized. If the thickness is increased in order to improve the gas barrier property and the deformation of the skeleton, the durability during running tends to decrease. Further, since a resin material having an enhanced gas barrier property generally tends to have a high elastic modulus, it is easily broken when a mechanical force is applied.

On the other hand, in the tire of the present invention, the difference between the maximum thickness and the minimum thickness between the maximum bending portions of the tire skeleton body (condition 1), the thickness D1 of the maximum bending portion of the tire skeleton body (condition 2), and the side rubber layer. The thickness D2 of the maximum bent portion (condition 3) and the gas permeability in the thinnest portion of the side portion (condition 4) are adjusted to appropriate ranges.
As a result, even if the thickness and weight of the entire tire are kept relatively small, the permeation of air from the inside of the tire is suppressed, the skeleton is less likely to be deformed even after the rubber material is vulcanized, and the durability during tire running is further reduced. Sex also improves.
That is, according to the present invention, a tire having improved gas barrier properties, deformation resistance to heating, and running durability is realized while suppressing the overall thickness, weight, and cost.

Here, the above conditions 1 to 4 are preferably in the following ranges from the viewpoint of improving the gas barrier property, the deformation resistance to heating, and the running durability.

-Condition 1-
The difference between the maximum thickness and the minimum thickness between the maximum bent portions of the tire skeleton is 0.1 mm or less, preferably 0.05 mm or less, and more preferably 0.03 mm or less.
Here, when the above difference is 0.1 mm or less, it means that there is substantially no difference.
That is, the tire skeleton is formed in a state where the thickness between the maximum bent portions is close to uniform (almost the same thickness).
When the above difference is 0.1 mm or less, the tire is easily pressurized evenly, so that problems such as deformation are unlikely to occur in tire molding. In addition, the center of the circle becomes the center as much as possible, and blurring is less likely to occur. As a result, tire durability is likely to be improved.

-Condition 2-
The thickness D1 of the maximum bending portion in the side portion of the tire skeleton is 0.5 mm or more and 2.5 mm or less, preferably 0.8 mm or more and 2.5 mm or less, and more preferably 1.0 mm or more and 2.4 mm or less. is there.
When the thickness D1 of the maximum bent portion is 0.5 mm or more, the handle responsiveness, the gas barrier property, and the cut resistance tend to be improved.
When the thickness D1 of the maximum bent portion is 2.5 mm or less, it is easy to improve air leakage due to the occurrence of side cracks. In addition, the bending durability is likely to be improved, so that the mileage can be improved. Furthermore, since the amount of resin can be reduced, the cost can be suppressed.

− Condition 3-
The thickness D2 of the maximum bent portion of the side rubber layer is more than 1.0 mm and 5.0 mm or less, preferably 2.0 mm or more and 5.0 mm or less, and more preferably 2.5 mm or more and 4.5 mm or less.
When the thickness D2 of the maximum bent portion exceeds 1.0 mm, the gas barrier property and the cut resistance are likely to be improved.
When the thickness D1 of the maximum bent portion is 5.0 mm or less, the weight can be reduced, so that the rolling resistance can be easily reduced.

− Condition 4-
In the side portion, the gas permeability in the minimum thickness D3 portion of the total thickness of the tire skeleton, the covering rubber layer and the side rubber layer, that is, the thinnest portion of the side portion is 18 × ^10-14 mol / (m ^2). · S · Pa) or less, preferably 15 × 10 ^-14 mol / (m ² · s · Pa) or less, more preferably 10 × 10 ^-14 mol / (m ² · s · Pa) or less.
When the gas permeability is 18 × 10 ^-14 mol / (m ² · s · Pa) or less, the internal pressure can be easily maintained.

In the present invention, the gas permeability of the side rubber layer is preferably equal to or less than the gas permeability of the tire skeleton.
When the gas permeability of the tire skeleton is lower than the gas permeability of the side rubber layer, the air permeated from the inside of the tire tends to collect at the interface between the tire skeleton and the rubber layer (side rubber layer and coating rubber layer). As a result, voids are likely to be formed at the interface, which leads to peeling of the interface and reduction of adhesive strength.
When the gas permeability of the side rubber layer is equal to or less than the gas permeability of the tire skeleton, the gas permeated from the inside of the tire is likely to be released to the outside due to the high internal pressure.
Therefore, by setting the relationship of the gas permeability of the side rubber layer ≤ the gas permeability of the tire skeleton, the formation of voids at the interface is suppressed, and the peeling of the interface and the decrease in adhesive strength are suppressed.

As described above, the tire of the present invention has at least a tire skeleton body, a covering rubber layer, and a side rubber layer, and may have other layers if necessary. Examples of other layers include an inner rubber layer provided on the inner peripheral surface of the tire skeleton body, an adhesive layer provided between each member and the layer, and the like.
Hereinafter, each member and layer will be described in detail.

《Tire skeleton》
The tire skeleton body in the present invention includes a resin material.
In the present invention, the "resin material" may contain at least a thermoplastic resin and may contain other components such as additives.

Examples of the thermoplastic resin include polyamide-based thermoplastic resin, polyester-based thermoplastic resin, olefin-based thermoplastic resin, polyurethane-based thermoplastic resin, vinyl chloride-based thermoplastic resin, and polystyrene-based thermoplastic resin. it can. These may be used alone or in combination of two or more. Among these, polyamide-based thermoplastic resins, polyester-based thermoplastic resins, and olefin-based thermoplastic resins are preferable, and polyamide-based thermoplastic resins and olefin-based thermoplastic resins are even more preferable.

Examples of the thermoplastic elastomer include a polyamide-based thermoplastic elastomer (TPA), a polystyrene-based thermoplastic elastomer (TPS), a polyurethane-based thermoplastic elastomer (TPU), and a polyolefin-based thermoplastic elastomer (TPO) specified in JIS K6418. Examples thereof include a polyester-based thermoplastic elastomer (TPEE), a thermoplastic rubber crosslinked product (TPV), and other thermoplastic elastomers (TPZ). Considering the elasticity required during running, moldability during manufacturing, etc., it is preferable to use a thermoplastic resin as the resin material, more preferably a thermoplastic elastomer, and a polyamide-based thermoplastic elastomer. It is particularly preferable to use (TPA).
When the resin material contains a polyamide-based thermoplastic elastomer, the resin material preferably contains the polyamide-based thermoplastic elastomer in an amount of 50% by mass or more, more preferably 65% by mass or more, more preferably 80% by mass, based on the total amount of the resin material. It is particularly preferable to contain% by mass or more.
When the resin material contains 50% by mass or more of the polyamide-based thermoplastic elastomer, the weight of the tire can be reduced and the rolling resistance can be easily reduced.

Hereinafter, a polyamide-based thermoplastic elastomer and a polyolefin-based thermoplastic elastomer will be described as examples of the thermoplastic resin contained in the resin material.

<Polyamide-based thermoplastic elastomer>
The polyamide-based thermoplastic elastomer is a thermoplastic elastomer composed of a copolymer having a polymer constituting a hard segment having a high crystallinity and a high melting point and a polymer constituting a soft segment having an amorphous shape and a low glass transition temperature. It means a polymer having an amide bond (-CONH-) in the main chain of the polymer constituting the hard segment.

− Hard segment −
Examples of the polyamide forming the hard segment (polymer compound forming the hard segment) include a polyamide synthesized using a monomer represented by the following general formula (1) or general formula (2). ..

In the general formula (1), R ¹ represents a molecular chain of a hydrocarbon having 2 to 20 carbon atoms. Examples of the molecular chain of the hydrocarbon having 2 to 20 carbon atoms include an alkylene group having 2 to 20 carbon atoms.

In the general formula (2), R ² represents a molecular chain of a hydrocarbon having 3 to 20 carbon atoms. Examples of the molecular chain of the hydrocarbon having 3 to 20 carbon atoms include an alkylene group having 3 to 20 carbon atoms.

Examples of the monomer represented by the general formula (1) or the general formula (2) include ω-aminocarboxylic acid and lactam. Examples of the polyamide forming the hard segment include polycondensates of these ω-aminocarboxylic acids and lactams, and copolymers of diamines and dicarboxylic acids.

As the polyamide forming the hard segment, a polyamide obtained by ring-opening polycondensation of ε-caprolactam (polyamide 6), a polyamide obtained by ring-opening polycondensation of undecanelactam (polyamide 11), and a polyamide obtained by ring-opening polycondensation of lauryllactam (polyamide) 12), polyamide (polyamide 12) obtained by polycondensing 12-aminododecanoic acid, polyamide (polyamide 66) obtained by polycondensing diamine and dibasic acid, or polyamide (amide MX) having metaxylene diamine as a constituent unit. Can be done.

The amide MX having m-xylylenediamine as a constituent unit can be represented by, for example, the following constituent units (A-1) [where n represents an arbitrary number of repeating units in (A-1)], for example. As n, 2 to 100 is preferable, and 3 to 50 is more preferable.

The number average molecular weight of the polymer (polyamide) forming the hard segment is preferably 300 or more and 15,000 or less from the viewpoint of melt moldability, toughness, and low temperature flexibility.

− Soft segment −
Examples of the polymer forming the soft segment (polymer compound forming the soft segment) include polyester and polyether, and further, for example, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol (PTMG), and the like. ABA type triblock polyether and the like can be mentioned, and these can be used alone or in combination of two or more.

Further, the polymer forming the soft segment may have a functional group introduced at the terminal. The functional group may be any one that reacts with the terminal group of the compound (polymer forming a hard segment, chain length extender, etc.) that reacts with the polymer forming the soft segment. For example, when the terminal group of the compound to be reacted with the polymer forming the soft segment is a carboxy group, the functional group includes an amino group and the like.

Among the polymers forming the soft segment, those having an amino group introduced at the terminal include, for example, polyether diamine obtained by reacting the terminal of a polyether with ammonia or the like, and specifically, ABA-type triblock poly. Examples include ether diamine.
Here, as the "ABA type triblock polyether", a polyether represented by the following general formula (3) can be mentioned.

In the general formula (3), x and z each independently represent an integer of 1 to 20. y represents an integer from 4 to 50.

Further, as the "ABA type triblock polyether diamine", a polyether diamine represented by the following general formula (N) can be mentioned.

In the general formula (N), X _N and Z _N each independently represent an integer of 1 to 20. Y _N represents an integer of 4 to 50.

The number average molecular weight of the polymer forming the soft segment is preferably 200 or more and 6000 or less, more preferably 400 or more and 4000 or less, and particularly preferably 600 or more and 2000 or less, from the viewpoint of toughness and low temperature flexibility.

-Join part-
As described above, examples of the bonding portion of the polyamide-based thermoplastic elastomer include a portion bonded by a chain length extender.
Examples of the chain length extender include dicarboxylic acids, diols, and diisocyanates. As the dicarboxylic acid, for example, at least one selected from aliphatic, alicyclic and aromatic dicarboxylic acids or a derivative thereof can be used. Examples of the diol include an aliphatic diol, an alicyclic diol, and an aromatic diol. As the diisocyanate, for example, an aromatic diisocyanate, an aliphatic diisocyanate, an alicyclic diisocyanate, or a mixture thereof can be used.

-Molecular weight-
The number average molecular weight of the polyamide-based thermoplastic elastomer is, for example, 15,700 to 200,000. If the number average molecular weight of the polyamide-based thermoplastic elastomer is less than 15,700, the rim assembly property may deteriorate. Further, when the number average molecular weight of the polyamide-based thermoplastic elastomer exceeds 200,000, the melt viscosity becomes high, and it is necessary to raise the molding temperature and the mold temperature in order to prevent insufficient filling when forming the tire skeleton. There may be. In that case, the cycle time becomes long, so that the productivity is inferior.

The number average molecular weight of the polyamide-based thermoplastic elastomer is preferably 20,000 to 160,000. The number average molecular weight of the polyamide-based thermoplastic elastomer can be measured by gel permeation chromatography (GPC). For example, GPC (gel permeation chromatography) such as "HLC-8320GPC EcoSEC" manufactured by Tosoh Corporation can be used. Can be used. The same applies to the measurement of the number average molecular weight of other thermoplastic elastomers described later.

In the polyamide-based thermoplastic elastomer, the ratio (x / y) of the mass (x) of the hard segment to the mass (y) of the soft segment is a viewpoint of ensuring rigidity as a tire and a viewpoint of enabling rim assembly. Therefore, 30/70 to 80/20 is preferable, and 50/50 to 75/25 is more preferable.
When the chain length extender is used, the content thereof is such that the functional group (for example, a hydroxyl group or an amino group) at the end of the polymer forming the soft segment and the carboxyl group of the chain length extender are approximately equimolar. It is preferable to set to.

-Manufacturing method-
The polyamide-based thermoplastic elastomer can be synthesized by copolymerizing the polymer forming the hard segment and the polymer forming the soft segment by a known method.
For example, the polyamide-based thermoplastic elastomer comprises a monomer constituting a hard segment (for example, ω-aminocarboxylic acid such as 12-aminododecanoic acid or lactam such as lauryllactam) and a chain length extender (for example, adipic acid or). After polymerizing with dodecanedicarboxylic acid) in a container, polymers constituting the soft segment (for example, polypropylene glycol, ABA type triblock polyether, diamine having these terminals modified to amino groups, etc.) are added. It can be obtained by further polymerization.

In particular, when ω-aminocarboxylic acid is used as the monomer constituting the hard segment, it can be synthesized by performing atmospheric melt polymerization or atmospheric melt polymerization and further reduced pressure melt polymerization. When lactam is used as the monomer constituting the hard segment, an appropriate amount of water can coexist, and from melt polymerization under a pressure of 0.1 MPa to 5 MPa, followed by atmospheric melt polymerization and / or reduced pressure melt polymerization. Can be manufactured by the following method. Moreover, these synthetic reactions can be carried out by either a batch type or a continuous type. Further, for the above-mentioned synthetic reaction, a batch type reaction kettle, a one-tank type or multi-tank type continuous reaction device, a tubular continuous reaction device, or the like may be used alone or in combination as appropriate.

<Polyolefin-based thermoplastic resin elastomer>
Polyolefin-based thermoplastic resin elastomers are soft segments in which at least polyolefin is crystalline and has a high melting point, and other polymers (for example, other polyolefins, polyvinyl compounds, etc.) are amorphous and have a low glass transition temperature. It means a constituent material, and examples thereof include a polyolefin-based thermoplastic resin elastomer (TPO) defined in JIS K6418: 2007.

-Hard segment, soft segment-
Examples of the polyolefin forming the hard segment include polyethylene, polypropylene, isotactic polypropylene, polybutene and the like.
Examples of the polymer forming the soft segment include polyolefin and polyvinyl compound. For example, ethylene propylene rubber such as EPM and EPDM may be used as the soft segment.

Examples of the polyolefin-based thermoplastic resin elastomer include an olefin-α-olefin random copolymer, an olefin block copolymer, and the like, and examples thereof include a propylene block copolymer, an ethylene-propylene copolymer, and a propylene-1-hexene copolymer. Polymer, propylene-4-methyl-1pentene copolymer, propylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-pentene copolymer, ethylene-1-butene Polymers, 1-butene-1-hexene copolymers, 1-butene-4-methyl-pentene, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl methacrylate copolymers, Ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, propylene-methacrylate 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, Examples thereof include a propylene-vinyl acetate copolymer.
The polyolefin content in the polyolefin-based thermoplastic resin elastomer is preferably 50% by mass or more and 100% by mass or less.

As the polyolefin-based thermoplastic resin elastomer, for example, a polyolefin-based thermoplastic resin elastomer having an acidic group (acid-modified polyolefin-based thermoplastic resin elastomer) can also be used.
Here, "acid modification" means binding an unsaturated compound having an acidic group such as a carboxylic acid group, a sulfuric acid group, or a phosphoric acid group to an olefin-based thermoplastic resin elastomer. For example, when an unsaturated carboxylic acid (generally maleic anhydride) is used as an unsaturated compound having an acidic group, an unsaturated bond site of the unsaturated carboxylic acid is bonded to the olefin-based thermoplastic resin elastomer (for example). , Graft polymerization).

-Molecular weight-
The number average molecular weight of the polyolefin-based thermoplastic resin elastomer is preferably 5,000 to 1,000,000. When the number average molecular weight of the polyolefin-based thermoplastic resin elastomer is 5,000 to 1,000,000, the mechanical properties of the thermoplastic resin material are sufficient and the processability is also excellent. From the same viewpoint, the number average molecular weight of the polyolefin-based thermoplastic resin elastomer is more preferably 7,000 to 1,000,000, and particularly preferably 10,000 to 1,000,000.

The mass ratio (x: y) of the hard segment (x) and the soft segment (y) in the polyolefin-based thermoplastic resin elastomer is preferably 50:50 to 95: 5, preferably 50:50, from the viewpoint of moldability. ~ 90:10 is more preferable.

-Manufacturing method-
The polyolefin-based thermoplastic resin elastomer can be synthesized by copolymerizing by a known method.

For acid modification of the polyolefin-based thermoplastic resin elastomer, for example, a twin-screw extruder or the like is used to use an olefin-based thermoplastic resin elastomer, an unsaturated compound having an acidic group (for example, an unsaturated carboxylic acid), and an organic peroxide. Can be carried out by kneading and graft copolymerizing. The amount of the unsaturated compound having an acidic group added is preferably 0.1 part by mass to 20 parts by mass, more preferably 0.5 parts by mass to 10 parts by mass with respect to 100 parts by mass of the olefin-based thermoplastic resin elastomer. ..

<Other additives>
Tire skeletons include various fillers (eg silica, calcium carbonate, clay), antioxidants, vulcanizers, vulcanization accelerators, metal oxides, process oils, plasticizers, depending on the material used. Various additives such as colorants, weather resistant agents, and reinforcing materials may be contained. The content of the additive in the resin material (tire skeleton) is not particularly limited, and can be appropriately used as long as the effects of the present invention are not impaired.

Examples of the anti-aging agent include the anti-aging agents described in International Publication WO2005 / 063482. Specifically, for example, naphthylamines such as phenyl-2-naphthylamine and phenyl-1-naphthylamine, 4,4'-α, α-dimethylbenzyl) diphenylamine, p- (P-toluene / sulfonylamide) -diphenylamine and the like. Amine-based antioxidants such as diphenylamine-based, N, N'-diphenyl-p-phenylenediamine, p-phenylenediamine-based such as N-isopropyl-N'-phenyl-p-phenylenediamine, derivatives or mixtures thereof, etc. Can be mentioned.

As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxides, and resin vulcanizing agents can be used. Examples of the vulcanization accelerator include known vulcanization accelerators such as aldehydes, ammonia, amines, guanidines, thioureas, thiazoles, sulfenamides, thiurams, dithiocarbamates, xanthates and the like. Can be used. Examples of the fatty acid include stearic acid, palmitic acid, myristic acid, lauric acid and the like, and these may be blended in a salt state such as zinc stearate. Of these, stearic acid is preferred. Examples of the metal oxide include zinc oxide (ZnO), iron oxide, magnesium oxide and the like, and zinc oxide is preferable. The process oil may be aromatic, naphthenic, or paraffinic.

<Physical characteristics of the resin material contained in the tire frame>
The melting point (or softening point) of the resin material is usually about 100 ° C. to 350 ° C., preferably about 100 ° C. to 250 ° C., but from the viewpoint of tire productivity, it is preferably about 120 ° C. to 250 ° C., preferably about 120 ° C. to 120 ° C. 200 ° C. is more preferable.
As described above, by using the resin material having a melting point of 120 ° C. to 250 ° C., for example, when the skeleton body of the tire is formed by fusing the divided bodies (skeleton pieces), the periphery of 120 ° C. to 250 ° C. Even if the skeleton is fused in the temperature range, the adhesive strength between the tire skeleton pieces is sufficient. Therefore, the tire of the present invention is excellent in durability during running such as puncture resistance and wear resistance. The heating temperature is preferably 10 ° C. to 150 ° C. higher than the melting point (or softening point) of the resin material forming the tire skeleton piece, and more preferably 10 ° C. to 100 ° C. higher.

The tensile yield strength of the resin material specified in JIS K7113: 1995 is preferably 5 MPa or more, preferably 5 MPa to 20 MPa, and even more preferably 5 MPa to 17 MPa. When the tensile yield strength of the resin material is 5 MPa or more, it can withstand deformation due to a load applied to the tire during running or the like.

The tensile yield elongation of the resin material specified in JIS K7113: 1995 is preferably 10% or more, preferably 10% to 70%, and even more preferably 15% to 60%. When the tensile yield elongation of the resin material is 10% or more, the elastic region is large and the rim assembly property can be improved.

The tensile elongation at break specified in JIS K7113: 1995 of the resin material is preferably 50% or more, preferably 100% or more, further preferably 150% or more, and particularly preferably 200% or more. When the tensile elongation at break of the resin material is 50% or more, the rim assembly property is good and it is possible to make it difficult to break due to a collision.

The deflection temperature under load (at 0.45 MPa load) specified in ISO75-2 or ASTM D648 of the resin material is preferably 50 ° C. or higher, preferably 50 ° C. to 150 ° C., and even more preferably 50 ° C. to 130 ° C. When the deflection temperature under load of the resin material is 50 ° C. or higher, deformation of the tire skeleton can be suppressed even when vulcanization is performed in the production of the tire.

The tensile elastic modulus of the resin material is preferably 100 MPa to 500 MPa, more preferably 200 MPa to 400 MPa, and particularly preferably 200 MPa to 350 MPa from the viewpoint of rim assembly and internal pressure retention.

《Coated rubber layer》
The tire of the present invention has a coated rubber layer. In the present invention, the "covered rubber layer" refers to a layer containing rubber and arranged on the outer peripheral surface of at least a side portion of the tire skeleton. The covering rubber layer may be a layer that covers the outer peripheral surface of the tire skeleton, for example, from one bead portion to the other bead portion.
The rubber contained in the coated rubber layer is not particularly limited, and is, for example, natural rubber (NR); polyisoprene synthetic rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile butadiene. Conjugate diene synthetic rubber such as rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR); ethylene-propylene copolymer rubber (EPM); ethylene-propylene-diene copolymer rubber (EPDM); polysiloxane rubber Etc., and these may be used alone or in combination of two or more. Among these, natural rubber (NR) and a mixture of natural rubber and styrene-butadiene copolymer rubber (SBR / NR) are preferable from the viewpoint of adhesive strength with the adhesive layer.
Further, the coated rubber layer may include, for example, a plurality of reinforcing cords coated with rubber. As the reinforcing cord, a steel cord, a monofilament (single wire) such as a metal fiber or an organic fiber, or a multifilament (twisted wire) obtained by twisting these fibers can be used.
Further, the coated rubber layer may contain at least rubber, and may be formed of a rubber composition obtained by adding other components such as additives to rubber depending on the purpose.
Examples of the additive include a reinforcing material such as carbon black, a filler, a vulcanizing agent, a vulcanization accelerator, a fatty acid or a salt thereof, a metal oxide, a process oil, an antiaging agent, and the like, and these are appropriately blended. can do.

《Side rubber layer》
The tire of the present invention has a side rubber layer. In the present invention, the "side rubber layer" refers to a layer containing rubber and arranged on the radial outer side of the tire skeleton via the coated rubber layer.
As the rubber contained in the side rubber layer, the same type of rubber as the rubber contained in the coated rubber layer can be used.

《Other layers》
As described above, the tire of the present invention may have other layers such as an inner rubber layer and an adhesive layer in addition to the tire skeleton body, the covering rubber layer, and the side rubber layer.
The "inner rubber layer" means a layer containing rubber and arranged on at least a part of the inner peripheral surface of the tire skeleton body. The inner rubber layer may be a layer that covers the inner peripheral surface of the tire skeleton, for example, from one bead portion to the other bead portion.
As the rubber contained in the inner rubber layer, the same type of rubber as the rubber contained in the coated rubber layer can be used. Further, the inner rubber layer may include a plurality of reinforcing cords coated with rubber, similarly to the coated rubber layer.

Each member and layer may be fixed by an adhesive layer. The material of the adhesive layer is not particularly limited as long as each member and layer can be adhered to each other. For example, the adhesive layer can be formed by using an adhesive, and an aqueous dispersion adhesive, a solvent-free adhesive, a solution adhesive, a solid adhesive (for example, a hot melt adhesive) or the like is used. be able to.

Hereinafter, an embodiment of the present invention will be described with reference to embodiments. In the drawings, the arrow W indicates the tire axial direction (tire width direction), and the arrow S indicates the tire radial direction extending from the tire axis (not shown) in the tire radial direction. The alternate long and short dash line CL indicates the equatorial plane of the tire.
FIG. 1 shows a cross-sectional view of the tire configuration according to the present embodiment along the tire width direction, and FIG. 2 shows an enlarged cross-sectional view of a bead portion and a side portion of the tire shown in FIG.

As shown in FIG. 1, the tire 100 of the present embodiment includes an annular tire skeleton body 10. The tire skeleton body 10 includes a pair of bead portions 12, a pair of side portions 14 extending outward from the bead portion 12 in the tire width direction, and a crown portion 16 connected to the inside of the side portions 14 in the tire width direction. A tread member 30 is arranged on the crown portion 16. The tire 100 is assembled to the rim 20.
In this embodiment, a case where the tire skeleton body 10 is formed of a thermoplastic resin will be described.

The tire skeleton 10 is a tire tire in which one bead portion 12, one side portion 14, and a half-width crown portion 16 are integrally formed to form an annular tire skeleton half body 10A having the same shape, facing each other. It is formed by joining at the equatorial plane CL. A thermoplastic material for welding (not shown) is used for joining at the tire equatorial plane CL. The tire skeleton body 10 is not limited to the one formed by joining two members, but may be formed by joining three or more members, a pair of bead portions 12, a pair of side portions 14, and a pair of side portions 14. The crown portion 16 may be integrally molded.

The tire skeleton half body 10A formed by using a thermoplastic material can be molded by, for example, vacuum forming, pressure molding, injection molding (injection molding), melt casting, etc., and when molding (vulcanization) with rubber. Compared with, the manufacturing process can be greatly simplified and the molding time can be shortened. Even if the tire skeleton 10 is made of a single thermoplastic material, each part of the tire skeleton 10 (side portion 14, crown portion 16) is the same as that of a conventional general rubber pneumatic tire. , Bead portion 12, etc.) may use thermoplastic materials having different characteristics.

A bead core 18 is embedded in the bead portion 12 of the tire skeleton body 10. The bead core 18 is made of a steel cord similar to a conventional general pneumatic tire. The bead core 18 may be omitted if the rigidity of the bead portion 12 is ensured and there is no problem in fitting with the rim 20. Further, the bead core 18 may be formed of a cord other than steel, such as an organic fiber cord or a cord coated with a resin of organic fibers, and further, the bead core 18 is formed of a hard resin by injection molding or the like instead of the cord. It may be a plastic one.

A reinforcing cord layer 28 is arranged on the outer side of the crown portion 16 of the tire skeleton body 10 in the tire radial direction via an adhesive layer (not shown) so as to go around the tire in the circumferential direction. The reinforcing cord layer 28 includes a plurality of reinforcing cords 26. The reinforcing cord 26 is covered with a rubber material, and is formed by spirally winding in the tire circumferential direction. In other words, the reinforcing cord layer 28 is formed by spirally winding the reinforcing cord layer 28 formed by coating the reinforcing cord 26 with a rubber material in the tire circumferential direction.

On the outer peripheral surface of the tire skeleton body 10, a covering rubber layer 22 covering the outer peripheral surface of the tire skeleton body 10 is arranged from one bead portion 12 to the other bead portion 12 via the reinforcing cord layer 28. There is. The coated rubber layer 22 includes a plurality of reinforcing cords (not shown) coated with rubber.
A side rubber layer 24 is arranged on the side portion 14 of the tire skeleton body 10 via a covering rubber layer 22.

A tread member 30 is arranged on the tire skeleton body 10, the reinforcing cord layer 28, the covering rubber layer 22, and the side rubber layer 24 on the outer side of the crown portion 16 in the tire radial direction. The tread member 30 constitutes a tire tread that is a ground contact portion of the tire 100. The tread member 30 is made of rubber having better wear resistance than the thermoplastic resin forming the tire skeleton 10. As the rubber used for the tread member 30, rubber of the same type as the rubber used for the conventional rubber pneumatic tire can be used. Further, a drainage groove 30A extending in the tire circumferential direction is formed on the tread surface of the tread member 30. In the present embodiment, two grooves 30A are formed, but the present invention is not limited to this, and more grooves 30A may be formed. Moreover, as a tread pattern, a known one is used.

In order to manufacture the tire 100 in the present embodiment, for example, after obtaining the annular tire skeleton 10, an adhesive is applied to the crown portion 16 of the tire skeleton 10 to form a coating film (adhesive layer). A reinforcing cord 26 coated with an unvulcanized rubber material is spirally wound on the coating film in the tire circumferential direction to form an unvulcanized reinforcing cord layer 28. Next, the coated rubber layer 22 and the side rubber layer 24 containing the unvulcanized rubber material are formed, and the unvulcanized tread member 30 is installed in the crown portion. In the present embodiment, which is subsequently subjected to vulcanization treatment by heating, a reinforcing cord layer 28 having a reinforcing cord 26 on the tire skeleton body 10, a coated rubber layer 22, a side rubber layer 24, and a tread member 30 are provided. Tire 100 can be obtained. The method for manufacturing the tire 100 in the present embodiment is not limited to this method.

(Action)
The operation of the tire 100 in this embodiment will be described.
In the tire 100 of the present embodiment, the difference between the maximum thickness and the minimum thickness between the maximum bending portions of the tire skeleton body 10, the thickness D1 of the maximum bending portion of the tire skeleton body 10, and the thickness of the maximum bending portion of the side rubber layer 24 The gas permeability of D2 and the thinnest portion T of the side portion 14 is adjusted to the above range.
Here, the maximum bent portion of the tire skeleton 10 corresponds to "10B" in FIG. 2, and the thickness D1 of the maximum bent portion corresponds to "D1" in FIG.
The maximum bent portion of the side rubber layer 24 corresponds to “24B” in FIG. 2, and the thickness D2 of the maximum bent portion corresponds to “D2” in FIG.
The minimum thickness D3 of the tire skeleton body 10, the covering rubber layer 22 and the side rubber layer 24 corresponds to “D3” in FIG. Corresponds to "T".
In the tire 100 of the present embodiment, the difference between the maximum thickness and the minimum thickness, the thicknesses (D1, D2), and the gas permeability in the thinnest portion T are adjusted, so that the thickness and weight of the entire tire are compared. Even if the size is kept small, the permeation of air from the inside of the tire is suppressed, the skeleton is less likely to be deformed even after the rubber material is vulcanized, and the durability during tire running can be further improved.
Further, since the tire skeleton 10 of the tire 100 of the present embodiment is formed of a thermoplastic resin, the structure of the tire 100 is simpler than that of a conventional rubber tire.

(Other embodiments)
Although an example of the embodiment has been described with respect to the present invention, the present invention is not limited to the above embodiment, and various other embodiments are possible within the scope of the present invention.

For example, the tire of the above embodiment may be provided with an inner rubber layer arranged on the inner peripheral surface of the tire skeleton body, for example, from one bead portion to the other bead portion.
In this case, the thickness of the tire skeleton is the thickness including the thickness of the inner rubber layer. Further, the gas permeability in the thinnest portion of the side portion is the gas permeability of the minimum thickness portion of the total thickness of the tire skeleton including the inner rubber layer, the covering rubber layer and the side rubber layer.
When the tire of the present embodiment includes an inner rubber layer, the durability during running of the tire can be further improved.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to this.

Tires having the structure shown in the above-described embodiment were produced by the same method as described above, and used as tires of Examples 1 to 9 and Comparative Examples 1 to 3. The resin materials of each example used were those shown in Table 4. The details of each material are as follows.

(Material of tire skeleton)
The following resin materials were used.
TPA1 ... polyamide-based thermoplastic elastomer (manufactured by Ube Industries, Ltd. "UBEST AXPA9055X1", gas ^{permeability: 3 × 10 -16 mol · m} / (m 2 · s · Pa))
TPA2 ... polyamide-based thermoplastic elastomer (manufactured by Ube Industries, Ltd. "UBEST AXPA9048X1", gas ^{permeability: 5 × 10 -16 mol · m} / (m 2 · s · Pa))
TPA3 ... polyamide-based thermoplastic elastomer (manufactured by Arkema "Bae Pebax5533 Bucks series", gas ^{permeability: 5 × 10 -16 mol · m} / (m 2 · s · Pa))
TPA4 ... Polyamide-based thermoplastic elastomer ("PA6" manufactured by Ube Industries, Ltd., gas transmittance: 3 x ^10-16 mol · m / (m ² · s · Pa))

(Material of side rubber layer)
The compounded rubber (unvulcanized rubber) mixed in the compounding shown in Table 1 below was used as the material for the side rubber layer (hereinafter referred to as material A).
Separately, a sample piece of material A (length 100 mm × width 100 mm × thickness 1.0 mm) was obtained, and the rubber in material A was vulcanized. When the gas permeability of the sample piece of the material A after vulcanization was measured by the method described above, the gas permeability was 10 × ^10-16 mol · m / (m ² · s · Pa)). ..

The details of each component in Table 1 are as follows.
Natural rubber (NR): RSS # 3
^* 1 "150L" manufactured by Ube Industries, Ltd.
^* 2 "Seast F" manufactured by Tokai Carbon Co., Ltd.
^* 3 Microcrystalline wax "Ozoace 0701" manufactured by Nippon Seiro Co., Ltd.
^* 4 6PPD "Nocrack 6C" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
^* 5 "Noxeller D" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
^* 6 "Noxeller DM" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
^* 7 "Sun Cellar CM-G" manufactured by Sanshin Chemical Industry Co., Ltd.

(Material of coated rubber layer)
An organic fiber (PET fiber: multifilament) coated with a compounded rubber (unvulcanized rubber) mixed with the composition shown in Table 2 below was used as a material for the coated rubber layer (hereinafter referred to as material B).
Separately, a sample piece of material B (length 100 mm × width 100 mm × thickness 1.0 mm) was obtained, and the rubber in material B was vulcanized. When the gas permeability of the sample piece of the material B after vulcanization was measured by the method described above, the gas permeability was 20 × ^10-16 mol · m / (m ² · s · Pa).

The details of each component in Table 2 are as follows.
Natural rubber (NR): RSS # 3
* 1: Made by Asahi Carbon Co., Ltd., product name "Asahi # 70"
* 2: N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Nocrack 6C"

(Material of tread member)
The compounded rubber (unvulcanized rubber) mixed in the compounding of Table 3 was used as the material of the tread member.

The details of each component in Table 3 are as follows.
Natural rubber: RSS3
Styrene-butadiene rubber: JSR1500
Carbon Black: N234 Tokai Carbon Co., Ltd. "Seast 7HM"
Anti-aging agent: "Antigen 6C" manufactured by Sumitomo Chemical Co., Ltd.
Vulcanization Accelerator DPG: Diphenylguanidine Vulcanization Accelerator CZ: N-Cyclohexylbenzothiazil Sulfenamide

The following measurements and evaluations were performed on the tires of each Example and Comparative Example. The results are shown in Table 4.

[Difference between maximum thickness and minimum thickness between maximum flexion parts of tire skeleton]
The difference between the maximum thickness and the minimum thickness between the maximum bending portions of the tire skeleton was measured. In Table 4, "maximum thickness-minimum thickness" represents the above difference.

[Maximum bending part thickness D1, thickness D2]
The thickness D1 of the maximum bent portion of the tire skeleton and the thickness D2 of the maximum bent portion of the side rubber layer were measured by the methods described above. The thickness of the maximum bent portion of the coated rubber layer was also measured by the same method.

[Gas permeability]
The gas permeability of the thinnest part of the side portion (tire skeleton, coated rubber layer and side rubber layer); gas permeability of the tire skeleton; gas permeability of the coated rubber layer and side rubber layer was measured by the method described above. In Table 4, "tire skeleton + coated rubber layer + side rubber layer" represents the gas permeability in the thinnest portion (the portion having the minimum thickness D3) of the side portion.

[Evaluation of gas barrier property (internal pressure retention characteristic)]
The tires of each example were assembled on the rim, and the tires were filled with air so that the internal pressure was 0.3 MPa. The obtained tire was left in a constant temperature and humidity chamber for 60 days while being maintained in an environment of 40 ° C./50% RH, and the internal pressure of the tire after being left for 60 days was measured.
The evaluation of the gas barrier property (internal pressure holding characteristic) of the tire was performed by calculating the internal pressure of the tire (internal pressure of the tire / internal pressure of the tire of Example 9) with respect to the internal pressure of the tire of Example 9 according to the following criteria.
(Standard)
A: Internal pressure ratio (tire internal pressure / tire of Example 9) is equal to or higher than the standard tire B: Internal pressure ratio (tire internal pressure / tire of Example 9) is at an acceptable level but slightly inferior to the standard tire (within -25%)
C: As the internal pressure ratio (internal pressure of the tire / tire of Example 9) becomes less than the permissible level, it is inferior to the standard tire (more than -25%).

[Evaluation of resin deformation (deformation resistance to heating) after vulcanization]
After the rubber material was vulcanized (150 ° C., 35 minutes, pressure 3 atm or less), the presence or absence of deformation was evaluated by measuring the amount of deformation of the tire skeleton with respect to the tire skeleton before vulcanization.
Specifically, the appearance was visually confirmed, and the presence or absence of deformation was confirmed depending on whether or not the deformation was visible. The vulcanization condition was 1.5 vest (1 vest is T90 (minutes) in curast).

[Evaluation of void formation ability at the tire skeleton / coated rubber layer interface]
After vulcanizing the rubber material (150 ° C., 35 minutes, pressure 3 atm or less), the interface between the tire skeleton and the coated rubber layer was observed with a microscope to confirm the presence or absence of void formation.
Specifically, a cut sample of the tire was prepared, and the presence or absence of void formation was confirmed by observing the interface between the tire skeleton and the coated rubber layer with a microscope.

[Evaluation of cut resistance]
The tire was rolled at a speed of 10 m / s at a specified internal pressure and a specified load, and at that time, a blade-shaped cutter having a width of 500 mm and a height of 30 mm was stepped on. The depth of the cut that entered the tire was used as the measure of cut resistance. In the exponential notation with Comparative Example 3 as 100, the larger the value, the better the result. The evaluation criteria are shown below.
(Standard)
A: Cut resistance (index) is 80 or more B: Cut resistance (index) is 60 or more and less than 80 C: Cut resistance (index) is less than 60

[Evaluation of tire running durability]
Using a drum tester with a smooth drum surface and a diameter of 1.707 m, the ambient temperature was controlled to 30 ± 3 ° C, and the failure occurred under the conditions of an internal pressure of 29.4 kPa and a load of 12.74 kN. The tire was run until the occurrence of. The longer the mileage, the better the running durability.
As a result, the running durability of the tire of Comparative Example 1 is expressed as "100", those less than 60 are regarded as "C", those of 60 or more and less than 100 are regarded as "B", and those of 100 or more are "A". ".

FIG. 3 shows the relationship between the gas permeability in the thinnest part of the side portion and the thickness of the tire skeleton.
As shown in FIG. 3, since the gas permeability of Examples 1 to 9 is smaller than that of Comparative Examples 1 and 2, it can be seen that the gas barrier property is excellent.
Further, as shown in Table 1, in Examples 1 to 9, no resin deformation occurred after vulcanization, and good results were obtained in the evaluation of tire running durability. On the other hand, in Comparative Example 3, although the gas permeability was small, the evaluation of running durability was "C".
Further, the tires of Examples 1 to 9 are relatively lightweight because they have a resin skeleton body, and the thickness of the tire skeleton body and the thickness of the maximum bent portion of the side rubber layer are adjusted.
From the above results, it was found that the tires of Examples 1 to 9 had improved gas barrier properties, deformation resistance to heating, and running durability while suppressing the overall thickness, weight, and cost.

100 tires, 10 tire skeletons, 10A tire skeleton half bodies, 12 bead parts, 14 side parts, 16 crown parts, 18 bead cores, 20 rims, 22 coated rubber layers, 24 side rubber layers, 26 reinforcement cords, 28 reinforcement cord layers, 30 tread member, 30A groove

Claims (3)

A pair of bead portions, a pair of side portions extending outward in the tire radial direction from the bead portion, and a crown portion connected to the inside in the tire width direction of the side portion are provided.
The resin material seen containing the resin material and a polyamide-based thermoplastic elastomer 50 wt% or more including an annular tire frame body,
A coated rubber layer containing rubber and arranged at least on the side portion of the tire skeleton body,
It contains rubber and has a side rubber layer arranged on the side portion of the tire skeleton body via the covering rubber layer.
The difference between the maximum thickness of the tire skeleton and the minimum thickness of the tire skeleton from the maximum bending portion on one side portion to the maximum bending portion on the other side portion is 0.1 mm or less.
In the side portion, the thickness D1 of the maximum bent portion of the tire skeleton is 0.5 mm or more and 2.5 mm or less, and the thickness D2 of the maximum bent portion of the side rubber layer exceeds 1.0 mm and 5.0 mm or less. , and the said tire frame body, wherein of the total thickness of the coating rubber layer and the side rubber layer, the gas permeability of the portion of the minimum thickness D3 is a ^{18 × 10 -14 mol / (m} 2 · s · Pa) or less ,tire. In part of the minimum thickness D3, gas permeability of the portion consisting of the coating rubber layer and the side rubber layer is tire according to claim 1 wherein at most gas permeability of the tire skeleton. The tire according to claim 1 or 2 , wherein the thickness D1 is 1.0 mm or more and 2.4 mm or less.

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