JP2012045790A - Method for manufacturing tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a tire using a thermoplastic resin material, to show superior heat resistance, as well as good rolling friction resistance.SOLUTION: The method for manufacturing a tire from a material containing at least a thermoplastic resin material includes: a tire skeleton forming step for forming an annular tire skeleton by using the material containing the thermoplastic resin material; and a heating step for heating the obtained tire skeleton at a temperature in the range from the glass transition temperature (Tg) of the thermoplastic resin material to Tg + 200°C.

Description

  The present invention relates to a method for manufacturing a tire to be attached to a rim, and more particularly, to a method for manufacturing a tire at least partially formed of a thermoplastic 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.
For example, Patent Document 1 discloses a pneumatic tire formed using a thermoplastic polymer material.

  A tire using a thermoplastic polymer material is easier to manufacture and lower in cost than a conventional rubber tire. However, when the tire frame is formed of a uniform thermoplastic polymer material that does not include a reinforcing member such as a carcass ply, the thermoplastic resin material that forms the tire frame compared to a conventional rubber tire Due to these characteristics, there is still room for improvement from the viewpoint of heat resistance (see, for example, Patent Document 1).

When a tire is manufactured from a material including a thermoplastic resin material, the obtained tire is required to realize performance comparable to that of a conventional rubber tire while increasing manufacturing efficiency and realizing low cost. . For example, a tire is required to have a strong resistance to impact, but a tire formed using a thermoplastic resin material as a main material is required to have an impact resistance equal to or higher than that of a tire using a conventional rubber. It has been.
In general, in the thermoplastic resin material, when the heat resistance of the molded body is improved, the molded body itself is hardened, and dynamic viscoelasticity (an index indicating rolling friction resistance important for tire performance) tan δ) tends to deviate from an appropriate value, and it was difficult to manufacture a tire in which both heat resistance and rolling friction resistance were maintained at good values.

JP 2003-104008 A

  The present invention has been made to solve the above problems, and provides a method for producing a tire that uses a thermoplastic resin material, has excellent heat resistance, and maintains a good rolling friction resistance. For the purpose.

(1) A method for manufacturing a tire according to the present invention is a method for manufacturing a tire formed of a material including at least a thermoplastic resin material, and an annular tire skeleton is formed using the material including a thermoplastic resin material. The tire skeleton forming step and the obtained tire skeleton are not less than the glass transition temperature of the thermoplastic resin material contained in the tire skeleton (hereinafter, the glass transition temperature is appropriately expressed as Tg) or more (Tg + 200 ° C.). A heating step of heating at the following temperature.

The method for producing a tire of the present invention is a method for producing a tire having an annular tire skeleton that includes a thermoplastic resin material.
The thermoplastic resin material in the present invention means a resin having thermoplasticity, and does not include vulcanized rubber such as conventional natural rubber and synthetic rubber.
By carrying out the heating step, the morphology of the thermoplastic resin material contained in the tire skeleton is in an equilibrium state, the crystallization of the resin is promoted, the rolling friction coefficient is maintained within a preferable range, the elasticity is improved, and the heat resistance is increased. It is estimated that it will be excellent in performance.

Hereinafter, preferred embodiments of the present invention will be given.
(2) The tire manufacturing method according to (1), wherein the heating step is a step of heating the tire frame body for 0.2 hours to 6 hours.
The formed tire frame is heated under the conditions of 0.2 to 6 hours at the glass transition temperature (Tg) to (Tg + 200 ° C.) of the thermoplastic resin material contained in the tire frame. In this case, the morphology of the resin material is in a sufficiently balanced state, so that the effect of the present invention is improved.

(3) The method for manufacturing a tire according to (1) or (2), wherein the thermoplastic resin includes a thermoplastic elastomer.
By using a thermoplastic resin elastomer made of a copolymer having a crystalline polymer having a high melting point and a non-crystalline polymer having a low glass transition temperature as a thermoplastic resin material. In the heating process, crystallization is promoted only in a polymer that forms a crystalline hard segment with a high melting point, and has no significant effect on a polymer that forms an amorphous soft segment with a low glass transition temperature. Therefore, it is considered that improvement in heat resistance and elasticity can be effectively achieved without reducing flexibility and rolling frictional resistance.

(4) The thermoplastic elastomer is a polyamide-based thermoplastic elastomer, the heating temperature in the heating step is in the range of 40 ° C to 250 ° C, and the heating time is in the range of 0.5 hours to 4 hours ( The manufacturing method of the tire as described in 3).
As a thermoplastic resin material, a polymer comprising a polymer comprising a crystalline hard segment having a high melting point and a non-crystalline polymer comprising a soft segment having a low glass transition temperature is used. The polyamide-based thermoplastic elastomer having an amide bond (—CONH—) in the main chain is advantageous in that it has heat resistance due to the properties of the material and is excellent in tensile modulus, tensile strength and breaking strain. The tire frame body including such a polyamide-based thermoplastic elastomer is used in a material and subjected to a heating step, whereby the heat resistance of the tire frame body is improved.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a tire that uses a thermoplastic resin material, is excellent in heat resistance, and maintains a good rolling friction resistance.

(A) is a perspective view which shows a partial cross section of one Embodiment of the tire which can apply the manufacturing method of this invention, (B) is sectional drawing of the bead part with which the rim | limb was mounted | worn. 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. It is explanatory drawing for demonstrating the operation | movement which embeds a reinforcement cord in the crown part of a tire case using a cord heating apparatus and rollers.

Hereinafter, the present invention will be described in detail.
In the method for producing a tire of the present invention, an annular tire skeleton is molded, and the obtained tire skeleton is converted to a glass transition temperature (Tg) or higher (Tg + 200 ° C.) of a thermoplastic resin material contained in the tire skeleton. It has the heating process heated at the following temperature, It is characterized by the above-mentioned.
Hereinafter, the tire manufacturing method of the present invention will be described in the order of steps together with materials used for manufacturing the tire.

<Tire skeleton formation process>
In the manufacturing method of the present invention, first, a tire frame is formed of a material including a thermoplastic resin material.
(Thermoplastic resin material)
There is no restriction | limiting in particular in the thermoplastic resin material used for manufacture of a tire frame body, According to the objective, it can select suitably and can use it from a thermoplastic polymer or a thermoplastic elastomer.
Among these, from the viewpoint of effects, a thermoplastic elastomer made of a copolymer having a polymer that forms a crystalline hard segment with a high melting point and a polymer that forms an amorphous soft segment with a low glass transition temperature is preferable. .
Considering the elasticity and heat resistance of the resulting tire, the thermoplastic elastomer is a crystalline polymer having a high melting point, and the main chain is composed of an amide bond (—CONH—), urethane bond, styrene, olefin. Preferred are amide-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, and polystyrene-based thermoplastic elastomers obtained by polymerizing monomers having a structure selected from: Alternatively, two or more types may be appropriately selected and used.
Among these, polyamide-based thermoplastic elastomers are preferable because they are excellent in heat resistance. Furthermore, polyamide-based thermoplastic elastomers are preferably used in combination with other suitable thermoplastic elastomers containing a main chain structure other than polyamide. As a result, a tire skeleton that can produce a tire with improved tensile modulus, tensile strength and breaking strain is formed. That is, when a polyamide-based thermoplastic elastomer and another elastomer are used in combination, the elastic modulus of the thermoplastic resin material forming the tire skeleton can be easily set within a desired range by adjusting the content ratio of both. Therefore, it is excellent in manufacturing cost.

The tire manufactured by the tire manufacturing method of the present invention may be provided with a reinforcing cord for the purpose of improving durability.
When the reinforcing coat member is provided, a reinforcing cord layer forming step, which will be described later, is performed after the tire skeleton forming step, and then the heating step is performed.

In this step, an annular tire skeleton is formed of a thermoplastic resin material containing a thermoplastic resin material, preferably a thermoplastic elastomer. In the tire skeleton forming step, the tire skeleton can be formed in one step by injection molding using an appropriate mold, but the tire skeleton pieces constituting a part of two or more tire skeletons are separated separately. It is good also as a tire frame body by producing and joining this.
That is, the step of forming the tire frame body includes a tire frame piece forming step of forming a tire frame piece constituting a part of the tire frame body, and a pair of two by applying heat to the joint surface of the tire frame piece. A tire frame piece joining step of forming the tire frame body by fusing the tire frame pieces as described above. Further, when the tire has a configuration having a reinforcing coat member, a reinforcing cord winding step is further performed in which a reinforcing cord is wound around the outer peripheral portion of the tire frame body in the circumferential direction to form a reinforcing cord layer.

As an example of this process, a thermoplastic resin material containing a polyamide-based thermoplastic elastomer is used as the thermoplastic resin material, and a tire skeleton is formed by molding and joining tire skeleton pieces. I will explain.
First, a tire frame piece is formed using a thermoplastic resin material described later. For the formation of the tire frame piece, a general injection molding, vacuum molding, pressure molding, melt casting, or the like may be applied as a molding method of the resin material.

  The tire frame piece can be, for example, a resin molded body formed by injection molding or the like in which one bead portion, one side portion, and a half-width crown portion are integrated. Usually, the tire frame piece is formed as an annular tire case half of the same shape, and two of them are opposed to each other and joined at the tire equatorial plane portion to form a tire frame body. The tire skeleton may be formed by joining three or more members as desired.

The tire skeleton piece formed of the thermoplastic resin material can be molded by applying a known resin molding method such as vacuum molding, pressure molding, injection molding, melt casting, or the like using an appropriate mold.
As described above, according to the method of forming two tire frame pieces by joining two tire frame pieces having the same shape, there is an advantage that only one type of mold for forming the tire frame pieces is required.
A more specific aspect of the method for manufacturing a tire frame piece to which the present invention can be applied will be described below.
As a mold for molding the tire frame piece, a mold having a fan gate is used and is generally formed by injection molding.
The heating temperature at the time of formation is a temperature equal to or higher than the melting point of the thermoplastic material, for example, when using a polyamide-based thermoplastic elastomer as shown in this embodiment, the melting point is 160 ° C. to 230 ° C. The formation may be performed at a temperature of 250 ° C. or lower.

As the thermoplastic resin material constituting the tire frame piece, granular (pellet-like) or powder-like (flake-like) or fine-powder-like (powder-like) material that is a molding precursor is used, and 80 ° C. before the molding step. Heating is performed at a temperature of 120 ° C. or lower for 2 hours to 6 hours to remove moisture contained in the precursor. If this heating process is insufficient, moisture is vaporized in the molding process, and a phenomenon called defective molding such as gas burning occurs due to compression in the mold.
The melting temperature of the thermoplastic material may be a temperature equal to or higher than the melting point. In order to promote fluidity in the mold and improve the transferability of the molding mold, the temperature is appropriately increased, but 250 ° C. When the material is melted at a temperature exceeding 1, the decomposition of the thermoplastic material is promoted, the material itself is deteriorated, and the physical properties of the molded product are seriously affected. Therefore, it is necessary to form the material at a temperature of 250 ° C. or lower.
As the molding apparatus, a general plunger type or pre-plastic type injection molding machine is used.

  When a polyamide-based thermoplastic elastomer is used, since the thermoplastic resin material can have a melting point of about 100 ° C. to 250 ° C., when forming a tire frame piece or joining a tire frame piece, for example, a tire frame It is not necessary to perform the piece fusion process under a temperature condition of 300 ° C. or higher, and the fusion process can be performed at a relatively low temperature. Thus, since the fusion process can be performed at a relatively low temperature, deterioration of the resin constituting the tire frame piece can be prevented, and the productivity of the tire can be improved from the viewpoint of the energy utilization rate. In addition, the tire skeleton pieces using the polyamide-based thermoplastic elastomer have sufficient adhesion strength between the tire skeleton pieces when fused to form the tire skeleton bodies, and the skeleton bodies themselves depend on the temperature at the time of fusion. Therefore, the durability of the manufactured tire such as puncture resistance and wear resistance can be improved.

In the tire frame piece joining step in the tire frame body forming step, the joining surface of the tire frame piece is heated to a temperature equal to or higher than a melting point of the thermoplastic resin material constituting the tire frame piece (for example, a melting point + 10 ° C or higher and a melting point + 70 ° C or lower). Can be configured to.
As described above, when the joining surface of the divided body is heated to a temperature equal to or higher than the melting point of the thermoplastic resin material constituting the tire frame piece, the tire frame pieces can be sufficiently fused with each other. The productivity of the tire can be increased while improving.
In the tire frame piece joining step, the tire frame piece is obtained by bonding the tire frame pieces and performing hot melt bonding.

In the present embodiment, the tire applied to the production method of the present invention preferably has an annular tire skeleton formed of a thermoplastic resin material containing a polyamide-based thermoplastic elastomer. Hereinafter, a thermoplastic resin material typified by a polyamide-based thermoplastic elastomer useful as a material for a tire frame body to which the production method of the present invention is applied will be described.
Here, the “polyamide thermoplastic elastomer” is composed of a copolymer having a crystalline polymer having a high melting point and another amorphous polymer having a low glass transition temperature. It means a thermoplastic resin material having an amide bond (—CONH—) in the main chain of the polymer constituting the hard segment. Examples of the polyamide-based thermoplastic elastomer include an amide-based thermoplastic elastomer (TPA) defined in JIS K6418 and a polyamide-based elastomer described in JP-A-2004-346273.

  The polyamide-based thermoplastic elastomer comprises at least a hard segment having a crystalline and high melting point, and other polymers (for example, polyester or polyether) are non-crystalline and have a soft segment having a low glass transition temperature. Materials. The polyamide thermoplastic elastomer may use a chain extender such as dicarboxylic acid in addition to the hard segment and the soft segment. Examples of the polyamide that forms the hard segment include polyamides produced from monomers represented by the following general formula (1) or general formula (2).

General formula (1)

[In General Formula (1), R ¹ represents a molecular chain of a hydrocarbon having 2 to 20 carbon atoms or an alkylene group having 2 to 20 carbon atoms. ]

General formula (2)

[In General Formula (2), R ² represents a molecular chain of a hydrocarbon having 3 to 20 carbon atoms or an alkylene group having 3 to 20 carbon atoms. ]

In general formula (1), R ¹ is preferably a hydrocarbon molecular chain having 3 to 18 carbon atoms or an alkylene group having 3 to 18 carbon atoms, and a hydrocarbon molecular chain having 4 to 15 carbon atoms or 4 carbon atoms. To 15 alkylene groups are more preferable, and hydrocarbon chains having 10 to 15 carbon atoms or alkylene groups having 10 to 15 carbon atoms are particularly preferable. In general formula (2), R ² is preferably a hydrocarbon molecular chain having 3 to 18 carbon atoms or an alkylene group having 3 to 18 carbon atoms, and a molecular chain or carbon having 4 to 15 carbon atoms. An alkylene group having 4 to 15 carbon atoms is more preferable, and a molecular chain of a hydrocarbon having 10 to 15 carbon atoms or an alkylene group having 10 to 15 carbon atoms is particularly preferable.
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 copolycondensation polymers of diamine carboxylic acids and dicarboxylic acids.

Examples of the ω-aminocarboxylic acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 10-aminocapric acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. And aliphatic ω-aminocarboxylic acid. Moreover, as a lactam, C5-C20 aliphatic lactams, such as lauryl lactam, (epsilon) -caprolactam, udecan lactam, (omega) -enantolactam, 2-pyrrolidone, etc. can be mentioned.
Examples of the diamine include ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2, Examples thereof include diamine compounds such as aliphatic diamines having 2 to 20 carbon atoms such as 4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 3-methylpentamethylenediamine, and metaxylenediamine. Further, dicarboxylic ^{acids, HOOC- (R 3) m-} COOH (R 3: a hydrocarbon having 3 to 20 carbon atoms, m: 0 or 1) can be represented by, for example, oxalic acid, succinic acid, glutaric acid And aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioic acid.
As the polyamide that forms the hard segment, a polyamide obtained by ring-opening polycondensation of lauryl lactam, ε-caprolactam, or udecan lactam can be preferably used.

  Examples of the polymer that forms the soft segment include polyester and polyether, and examples include polyethylene glycol, propylene glycol, polytetramethylene ether glycol, and ABA type triblock polyether. Here, the “ABA type triblock polyether” means a polyether represented by the following general formula (3).

General formula (3)
[In General Formula (3), x and z each independently represents an integer of 1 to 20. y represents an integer of 4 to 50. ]

  In the general formula (3), each of x and z is preferably an integer of 1 to 18, more preferably an integer of 1 to 16, particularly preferably an integer of 1 to 14, and most preferably an integer of 1 to 12. . In the general formula (3), each of y is preferably an integer of 5 to 45, more preferably an integer of 6 to 40, particularly preferably an integer of 7 to 35, and most preferably an integer of 8 to 30. .

  Examples of the combination of the hard segment and the soft segment include the combinations of the hard segment and the soft segment mentioned above. Among these, lauryl lactam ring-opening polycondensate / polyethylene glycol combination, lauryl lactam ring-opening polycondensate / polypropylene glycol combination, lauryl lactam ring-opening polycondensate / polytetramethylene ether glycol combination, lauryl lactam The ring-opening polycondensate / ABA triblock polyether combination is preferred, and the lauryl lactam ring-opening polycondensate / ABA triblock polyether combination is particularly preferred.

  The number average molecular weight of the polymer (polyamide) constituting the hard segment is preferably 300 to 1500 from the viewpoint of melt moldability. Moreover, as a number average molecular weight of the polymer which comprises the said soft segment, 200-6000 are preferable from a viewpoint of toughness and low temperature flexibility. Furthermore, the volume ratio (x: y) to the hard segment (x) and the soft segment (y) is preferably 50:50 to 90:10, more preferably 50:50 to 80:20, from the viewpoint of moldability. preferable.

  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.

  Examples of the polyamide-based thermoplastic elastomer include, for example, a commercially available “Uvesta XPA” series (for example, XPA9063X1, XPA9055X1, XPA9048X2, XPA9048X1, XPA6040X1, etc.) of Ube Industries, Ltd., and “Stamide” of Daicel Eponic Corporation. Series (for example, E40-S3, E47-S1, E47-S3, E55-S1, E55-S3, EX9200, E50-R2) and the like can be used.

  As the thermoplastic resin material, in addition to the polyamide-based thermoplastic elastomer, other thermoplastic elastomers may be used in combination. As another thermoplastic elastomer, the polymer constituting the hard segment has a skeleton such as urethane, styrene or olefin on the main chain obtained by polymerizing a monomer having a structure selected from urethane, styrene or olefin. Examples thereof include polyurethane, polystyrene, and polyolefin. Other thermoplastic elastomers include, for example, polyurethane-based thermoplastic elastomers (TPU), polystyrene-based thermoplastic elastomers (TPS), polyolefin-based thermoplastic elastomers (TPO), polyester-based thermoplastic elastomers (specified in JIS K6418) TPC), and the like.

As said other thermoplastic elastomer, a commercial item can be used, for example.
As the polyurethane-based thermoplastic resin composition, for example, a commercially available “Elastollan” series (for example, ET680, ET880, ET690, ET890, C80A, S80A) manufactured by BASF can be used.
As the polystyrene-based thermoplastic elastomer, for example, a commercially available “Tuftec” series manufactured by Asahi Kasei Co., Ltd. (for example, H1031, H1041, H1043, H1051, H1052, H1053, H1082, H1141, H1221, H1272) or the like may be used. it can.
Examples of the polyolefin-based thermoplastic elastomer include, for example, commercially available “Tuffmer” series manufactured by Mitsui Chemicals (for example, A0550S, A1050S, A4050S, A1070S, A4070S, A35070S, A1085S, A4085S, A7090, A700090, MH7007, MH7010, P275) or the like can be used.
Examples of the polyester-based thermoplastic elastomer include a commercially available “Hytrel” series (for example, 3046, 5557, 6347, 4047, 4767, etc.) manufactured by Toray DuPont, and a “Velprene” series (P30B, P40B, Use P40H, P55B, P70B, P150B, P280B, P450B, P150M, S1001, S2001, S5001, S6001, S9001, etc., Mitsubishi Chemical's “Primalloy A” series (A1500N, A1600N, A1700N, A1800N, A1900N, etc.) Can do.

  As the thermoplastic resin material, when the other thermoplastic elastomer (y) is used in combination with the polyamide-based thermoplastic elastomer (x), the mass ratio (x: y) between the two is arbitrary. For example, 95: It is preferably 5 to 55:45. When the volume ratio of the elastomer is within the above range, the polyamide thermoplastic elastomer and the other thermoplastic elastomer form a sea-island structure in which the polyamide thermoplastic elastomer is “the sea”. Impact is improved. When two or more other thermoplastic elastomers are used in combination, the total amount of the other elastomers and the total amount of the polyamide-based thermoplastic elastomer is preferably included in the above range.

  As melting | fusing point of the thermoplastic elastomer used for manufacture of a tire, about 100 to 250 degreeC is preferable from a viewpoint of the productivity of a tire, and 100 to 200 degreeC is still more preferable. Thus, by using a thermoplastic resin material containing a thermoplastic elastomer having a melting point of 100 ° C. to 200 ° C., for example, when forming a skeleton of a tire by fusing the divided bodies (frame pieces), The heating temperature of the joining portion can be set to be equal to or higher than the melting point of the thermoplastic resin material forming the tire skeleton. According to this configuration, even if the frame body is fused in a temperature range of 160 ° C. to 250 ° C., the adhesion strength between the tire frame pieces is sufficient. The heating temperature at the time of joining is preferably 10 ° C to 100 ° C higher than the melting point of the thermoplastic resin material including the thermoplastic elastomer that forms the tire frame piece, and more preferably 10 ° C to 70 ° C.

  The total content of the thermoplastic elastomer in the thermoplastic resin material in the present invention is not particularly limited, but is preferably 50% by volume or more based on the total amount of the thermoplastic resin material. When the total content of the thermoplastic elastomer is 50% by volume or more based on the total amount of the thermoplastic resin material, the properties of the thermoplastic elastomer can be fully exhibited, and the durability and productivity of the tire are improved. Can be made. The thermoplastic resin material includes various materials such as rubber, thermoplastic resin, various fillers (for example, silica, calcium carbonate, clay), anti-aging agent, oil, plasticizer, colorant, weathering agent, and the like, as desired. An additive may be contained.

  The tensile elastic modulus (hereinafter referred to as “elastic modulus” in the present specification means the tensile elastic modulus unless otherwise specified) as defined in JIS K7113 of a thermoplastic resin material used in the manufacture of tires is 100 MPa to. 1000 MPa is preferable, 100 MPa to 800 MPa is more preferable, and 100 MPa to 700 MPa is particularly preferable. When the tensile modulus of the polyamide-based thermoplastic elastomer is 100 MPa to 1000 MPa, the rim can be assembled efficiently while maintaining the shape of the tire skeleton.

  The tensile yield strength specified in JIS K7113 of the thermoplastic resin material used for manufacturing tires is preferably 5 MPa or more, preferably 5 MPa to 20 MPa, and more preferably 5 MPa to 17 MPa. When the tensile yield strength of the polyamide-based thermoplastic elastomer is 5 MPa or more, it can withstand deformation against a load applied to the tire during running.

  The tensile yield elongation defined by JIS K7113 of the thermoplastic resin material used for manufacturing tires is preferably 10% or more, preferably 10% to 70%, and more preferably 15% to 60%. When the tensile yield elongation of the polyamide-based thermoplastic elastomer is 10% or more, the elastic region is large and the rim assembly property can be improved.

  As a tensile fracture elongation (JIS K7113) prescribed | regulated to JISK7113 of the thermoplastic resin material used for manufacture of a tire, 50% or more is preferable, 100% or more is preferable, 150% or more is further more preferable, 200% or more is Particularly preferred. When the tensile elongation at break of the polyamide-based thermoplastic elastomer is 50% or more, the rim assembly property is good and it is possible to make it difficult to break against a collision.

  As a deflection temperature under load (0.45 MPa load) specified in ISO75-2 or ASTM D648 of a thermoplastic resin material used for manufacturing a tire, 50 ° C. or higher is preferable, 50 ° C. to 150 ° C. is preferable, and 50 ° C. More preferably, ˜130 ° C. When the deflection temperature under load of the polyamide-based thermoplastic elastomer is 50 ° C. or higher, deformation of the tire frame body can be suppressed even when vulcanization is performed in the manufacture of the tire.

<Heating process>
In this step, the tire frame body obtained in the tire frame body forming step is heat-treated. The heat treatment is performed at a temperature higher than the glass transition temperature (Tg) of the thermoplastic resin material used for forming the tire frame. Specifically, the heating temperature is a temperature range of Tg1 ° C. or higher and Tg1 + 200 ° C. or lower, preferably Tg1 + 50 ° C. or higher and Tg1 + 150 ° C. or lower, where the glass transition temperature of the resin material is Tg1.

In this specification, the Tg of the resin material refers to the resin itself, if a thermoplastic resin is used as the thermoplastic resin material, the hard segment of the thermoplastic elastomer if the thermoplastic elastomer is used. Refers to the Tg of the constituent polymer.
Tg can be measured using an ordinary differential scanning calorimeter, and in this specification, a differential scanning calorimeter (DSC) manufactured by Rigaku Corporation is used in the range of 25 to 400 ° C. The value measured at a temperature rising rate of 5 ° C./min is adopted.
The heating time is preferably from 0.2 hours to 6 hours, and more preferably from 0.5 hours to 4 hours.
By setting the temperature condition and the heating time condition within the above ranges, in the formed tire frame body, the morphology of the thermoplastic resin material contained in the tire frame body becomes an equilibrium state, and the crystallization of the resin is promoted. We believe that the effect will be manifested.

As described above, the heating conditions (heating temperature, heating time) in the heating step are appropriately selected according to the thermoplastic resin material used for forming the tire frame.
For example, when a polyamide thermoplastic elastomer is used as the thermoplastic resin material, the Tg of the polyamide thermoplastic elastomer is −20 ° C. to 20 ° C., and therefore the heating temperature is preferably 40 ° C. or higher and 250 ° C. or lower. It is more preferable that the temperature is not lower than 200 ° C and not higher than 200 ° C. The heating time is preferably 0.2 hours or more and 6 hours or less, and more preferably 0.5 hours or more and 4 hours or less.

There is no particular limitation on the heating means, a method in which the tire frame is placed in a mold and directly heated, a method in which the tire frame is placed in a heating zone and heated by a non-contact heating means such as infrared rays or hot air, an ultrasonic wave or a micro Although the method of heating using a wave etc. is mentioned, it is preferable to take the following heating methods from viewpoints of controllability of heat quantity, safety, and simplicity of the apparatus.
That is, a tire skeleton body or tire skeleton piece molded by injection molding is allowed to stand in a hot air drying apparatus at normal pressure and at a predetermined heating temperature. After heating for a predetermined time, the molded product is taken out and cooled to room temperature. .
The pressure in this heating step is reduced to 10 mmHg or less using a normal vacuum pump device for the purpose of promoting the removal of components such as moisture and monomer contained in the molded product in addition to the desired improvement in heat resistance. For the purpose such as heating in a high pressure state of 0.5 MPa or more using a normal compressor device, when the purpose is to promote adhesion with a molded product of a different material or the same material. The pressure can also be set as appropriate.

In the heating process in this embodiment, since the thermoplastic resin material constituting the molded article is arranged under a temperature condition equal to or higher than the glass transition temperature (Tg), microscopic molecular motion occurs and the elastic modulus of the material is significantly reduced. That is, it softens. Therefore, when stress is applied to the molded product during the heating process, it may be easily deformed. For this reason, in order to prevent undesired deformation, a jig made of a material such as iron, stainless steel, aluminum, titanium, etc., which is not deformed at the heating temperature, is kept in the shape of the molded product. It is also possible to prevent the deformation by arranging in a shape along the line.
By passing through this heating step, the tire obtained by the production method of the present invention can achieve both heat resistance and rolling friction resistance at a high level.

<Reinforcing cord layer forming process>
The tire obtained by the production method of the present invention may be provided with a reinforcing cord as desired. By winding the reinforcing cord around the outer periphery of the tire frame and forming the reinforcing cord layer, the puncture resistance and cut resistance of the tire and the circumferential rigidity of the tire (tire frame) are improved. In addition, the improvement of the circumferential rigidity suppresses the creep of the tire frame formed of a thermoplastic resin material (a phenomenon in which the plastic deformation of the tire frame increases with time under a certain stress).
Here, the reinforcing cord layer forming step provided as desired will be described.
The reinforcing cord layer forming step for providing the reinforcing cord is performed after the tire frame body forming step. The heating step may be performed before or after the heating step. However, in consideration of the stability of the reinforcing cord layer and the adhesion to the tire frame, the heating step may be performed as required. It is preferable to be performed after.

  The reinforcing cord layer can be configured to include a resin material. By including a resin material in the reinforcing cord layer, the difference in hardness between the tire and the reinforcing cord layer can be reduced compared to the case where the reinforcing cord is fixed with cushion rubber.・ Can be fixed. As described above, the “resin material” is a concept including a thermoplastic resin (including a thermoplastic elastomer) and a thermosetting resin, and does not include vulcanized rubber.

Examples of the thermosetting resin that can be used for the reinforcing cord layer include phenol resin, urea resin, melamine resin, epoxy resin, and polyamide resin.
Examples of the thermoplastic resin include urethane resin, olefin resin, vinyl chloride resin, polyamide resin, and the like.

Examples of the thermoplastic elastomer include amide-based thermoplastic elastomer (TPA), polyester-based thermoplastic elastomer (TPC), polyolefin-based thermoplastic elastomer (TPO), and polystyrene-based thermoplastic elastomer (TPS) defined in JIS K6418. , Polyurethane thermoplastic elastomer (TPU), crosslinked thermoplastic rubber (TPV), other thermoplastic elastomer (TPZ), and the like. Note that it is preferable to use a thermoplastic elastomer in consideration of elasticity required at the time of traveling, moldability at the time of manufacture, and the like.
Moreover, the same kind of resin material refers to forms, such as ester systems and styrene systems.

The elastic modulus (tensile elastic modulus defined in JIS K7113) of the resin material used for the reinforcing cord layer is set within a range of 0.1 to 10 times the elastic modulus of the thermoplastic resin forming the tire frame body. It is preferable. When the elastic modulus of the resin material is 10 times or less than the elastic modulus of the thermoplastic resin material forming the tire frame body, the crown portion is not too hard and rim assembly is facilitated. Further, when the elastic modulus of the resin material is 0.1 times or more of the elastic modulus of the thermoplastic resin material forming the tire frame body, the resin constituting the reinforcing cord layer is not too soft and the in-plane shear rigidity Excellent cornering power.
In the tire manufacturing method of the present invention, when the resin is included in the reinforcing cord layer, it is preferable from the viewpoint of the reinforcing cord adhesion that the heating step is performed after this step, that is, the reinforcing cord layer forming step. .

  According to the tire manufacturing method of the present invention including the tire cord body forming step, the heating step, and the reinforcing cord layer forming step that is optionally performed before or after the heating step, the tire has excellent heat resistance and rolling. A tire in which the frictional resistance is maintained at an appropriate value can be manufactured with high productivity.

[First Embodiment]
Below, the manufacturing method of the tire which concerns on 1st Embodiment of the manufacturing method of the tire of this invention according to drawing is demonstrated in order of a process.
The tire 10 of this embodiment will be described. FIG. 1A is a perspective view showing a cross section of an embodiment of a tire obtained by the production method 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 according to the present embodiment has a cross-sectional shape that is substantially the same as 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 portion 21 and the rim flange 22 of the rim 20 shown in FIG. A tire case 17 including a side portion 14 that extends outwardly, and 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. I have.

  Here, the tire case (tire frame body) 17 of the present embodiment is formed of a thermoplastic resin material including a polyamide-based elastomer (“Ubesta XPA9048X1” manufactured by Ube Industries, Ltd .: Tg-20 ° C.). In the present embodiment, the tire case (tire frame body) 17 is formed of a single thermoplastic resin material, but the present invention is not limited to this configuration, and is similar to a conventional general rubber pneumatic tire. Moreover, you may use the thermoplastic resin material which has a different characteristic for every site | part (the side part 14, the crown part 16, the bead part 12, etc.) of the tire case 17. FIG. 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 thermoplastic resin material. The tire case half body 17A is a resin molded body formed by injection molding or the like, in which one bead portion 12, one side portion 14, and a half-width crown portion 16 are integrated, and is formed in an annular shape having the same shape. The tire case (tire frame) 17 is formed by joining the tire case halves 17A facing each other and joining the tire equatorial plane portions.
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 a thermoplastic resin material can be molded by, for example, vacuum molding, pressure molding, 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 thermoplastic 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, An annular seal layer 24 made of rubber is formed. The seal layer 24 may also be formed at a portion where the tire case 17 (beat portion 12) and the bead sheet 21 are in contact with each other. As a material having a better sealing property than the thermoplastic resin material constituting the tire case 17, a softer material can be used as compared with the thermoplastic resin material constituting the tire case 17. 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. If the sealing property between the rim 20 can be secured only with the thermoplastic resin material, the rubber seal layer 24 may be omitted, and another thermoplastic resin having a sealing property superior to that of the thermoplastic resin material is used. Also good. Examples of such other thermoplastic resins include resins such as polyurethane resins, polyolefin resins, and polystyrene resins, and blends of these resins with rubbers or elastomers.

  As shown in FIG. 1, a reinforcing cord 26 having higher rigidity than the thermoplastic resin material constituting the tire case 17 is wound around the crown portion 16 in the circumferential direction of the tire case 17. 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. A tread 30 made of a material having higher wear resistance than the thermoplastic resin material constituting the tire case 17, for example, rubber, is disposed on the outer circumferential side of the reinforcing cord layer 28 in the tire radial direction.

  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 thermoplastic 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 thermoplastic resin material that is more excellent in wear resistance than the thermoplastic 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 tire manufacturing method of the present invention will be described.
(Tire case (tire frame) molding process)
First, a tire half (tire frame piece) is formed by an injection molding apparatus or the like.
Thereafter, the 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. 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 A may be pressed with a predetermined pressure. Next, the periphery of the joint portion of the tire case half is pressed at a temperature equal to or higher than the melting point of the thermoplastic resin material constituting the tire case. When the joining portion of the tire case half is heated and pressurized by the joining mold, the joining portion is melted and the tire case halves are fused together, and the tire case 17 is formed by integrating these members. In the present embodiment, the joining portion of the tire case half is heated using a joining mold, but the present invention is not limited to this. For example, the joining portion is heated by a separately provided high-frequency heater or the like. Alternatively, the tire case halves may be joined by softening or melting in advance by irradiation with hot air, infrared rays, or the like, and pressurizing with a joining mold.
In this embodiment, a polyamide-based elastomer (“Uvesta XPA9048X1” manufactured by Ube Industries, Ltd .: Tg−20 ° C.), which is a thermoplastic resin material forming the tire case 17, is used as the thermoplastic resin material for welding.

(Reinforcement cord member winding process)
Next, the reinforcing cord winding process will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining an operation of embedding a reinforcing cord in a crown portion of a tire case using a cord heating device and rollers. In FIG. 3, the cord supply device 56 includes a reel 58 around which the reinforcing cord 26 is wound, a cord heating device 59 arranged on the downstream side of the reel 58 in the code conveyance direction, and a first code arranged on the downstream side of the cord 26 in the conveyance direction. 1 roller 60, a first cylinder device 62 that moves the first roller 60 in a direction of moving toward and away from the outer peripheral surface of the tire, and a first roller 60 disposed downstream of the cord 26 in the conveying direction. A second roller 64; and a second cylinder device 66 that moves the second roller 64 in a direction in which the second roller 64 comes into contact with or separates from the tire outer peripheral surface. The second roller 64 can be used as a metal cooling roller. Further, in the present embodiment, the surface of the first roller 60 or the second roller 64 is made of a fluororesin (in this embodiment, Teflon (registered trademark)) in order to suppress adhesion of a molten or softened thermoplastic resin material. ). In the present embodiment, the cord supply device 59 is configured to have two rollers, the first roller 60 or the second roller 64, but the present invention is not limited to this configuration, and either one of the rollers. It is also possible to have only one (that is, one roller).

  The cord heating device 59 includes a heater 70 and a fan 72 that generate hot air. Further, the cord heating device 59 includes a heating box 74 through which the cord 26 passes through an internal space in which hot air is supplied, and a discharge port 76 for discharging the heated cord 26.

  In this step, first, the temperature of the heater 70 of the cord heating device 59 is raised, and the ambient air heated by the heater 70 is sent to the heating box 74 by the wind generated by the rotation of the fan 72. Next, the reinforcing cord 26 unwound from the reel 58 is fed into a heating box 74 in which the internal space is heated with hot air (for example, the temperature of the reinforcing cord 26 is heated to about 100 to 200 ° C.). The heated reinforcing cord 26 passes through the discharge port 76 and is wound spirally around the outer peripheral surface of the crown portion 16 of the tire case 17 rotating in the direction of arrow R in FIG. Here, when the heated reinforcing cord 26 comes into contact with the outer peripheral surface of the crown portion 16, the thermoplastic resin material in the contact portion is melted or softened, and at least a part of the heated reinforcing cord 26 is outer peripheral surface of the crown portion 16. Buried in At this time, since the heated reinforcing cord 26 is embedded in the molten or softened thermoplastic resin material, the thermoplastic resin material and the reinforcing cord 26 are in a state where there is no gap, that is, in a close contact state. Thereby, the air entering to the portion where the reinforcing cord 26 is embedded is suppressed. In addition, by heating the reinforcing cord 26 to a temperature higher than the melting point of the thermoplastic resin material of the tire case 17, melting or softening of the thermoplastic resin material in a portion in contact with the reinforcing cord 26 is promoted. By doing in this way, it becomes easy to embed the reinforcement cord 26 in the outer peripheral surface of the crown part 16, and air entry can be effectively suppressed.

(Heating process)
Next, the tire frame body on which the reinforcing cord layer is formed is heated.
Since the glass transition temperature Tg of the thermoplastic resin material is −20 ° C., the heating temperature is performed in the temperature range of 40 ° C. to 180 ° C. for about 0.5 to 2 hours. The heating process is performed by using a hot air heating and drying apparatus, in which the tire frame body on which the reinforcing cord layer is formed is arranged in a direction in which heat is uniformly propagated to the heat source.
The tire frame body heated for a predetermined time is allowed to cool to room temperature after the heat treatment step.

(Tire finishing process)
Next, the vulcanized belt-like tread 30 is wound around the outer peripheral surface of the tire case 17 subjected to the heating process by 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.

In the tire 10 of this embodiment, since the tire case 17 is formed of a thermoplastic resin material, the structure can be simplified and the weight is lighter than that of a conventional rubber. For this reason, if the tire 10 of this embodiment is applied to a motor vehicle, it can reduce in weight and can suppress a fuel consumption.
In the tire 10 of the present embodiment, the reinforcing cord 26 having higher rigidity than the thermoplastic 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 the thermoplastic resin material. Therefore, puncture resistance, cut resistance, and circumferential rigidity of the tire 10 are improved. In addition, it has the advantage that the creep of the tire case 17 formed of the thermoplastic resin material is prevented by improving the circumferential rigidity of the tire 10.

  As mentioned above, although the specific aspect of this invention was demonstrated using 1st Embodiment, this invention is not limited to the above-mentioned aspect.

As shown in the first embodiment, the tire of the present invention can be configured as follows.
In the tire obtained by the manufacturing method of the present invention, at least a part of the reinforcing cord is embedded in the outer peripheral portion of the tire frame formed of the thermoplastic resin material in a cross-sectional view along the axial direction of the tire frame. Can be configured.
Moreover, you may provide the tread formed from the material which has abrasion resistance rather than the said thermoplastic resin material in the radial direction outer side of the said reinforcement cord layer.
wear.

(Function)
In the tire 10 of the present embodiment obtained by the manufacturing method of the present invention, since the tire case 17 formed of a thermoplastic resin material is heat-treated under an appropriate heating condition after molding, the crystal of the thermoplastic resin material When the structure changes, especially when a thermoplastic elastomer is used, the crystallization of the polymer that constitutes the hard segment is promoted, so the heat resistance is excellent and the rolling frictional resistance is deteriorated as the heat resistance is improved. Is suppressed and maintained in an appropriate range, and both are compatible at a high level. For this reason, the tire 10 obtained by the manufacturing method of the present embodiment has excellent heat resistance, low rolling friction resistance, excellent durability, and high steering stability in a wide temperature range.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to this.
First, tires of examples and comparative examples were molded according to the first embodiment described above. At this time, the material forming the tire frame and its glass transition temperature are shown in Table 1 below. Furthermore, the heating temperature and heating time in the heating process are also shown in Table 1 below.
While evaluating the tire performance obtained by the manufacturing method of each Example and a comparative example by the method shown below, the following evaluation was performed also about the test piece obtained by performing the same process.

<Preparation of sample piece>
<Examples 1-8, Comparative Examples 1-4>
A plate-like sample of the following elastomer with an injection molding machine (SE30D injection molding machine manufactured by Sumitomo Heavy Industries, Ltd.) having a molding temperature (cylinder temperature) of 180 to 230 ° C. and a mold temperature of 60 ° C., a thickness of 2 mm, a width of 30 mm, and a length of 100 mm. From the obtained plate-like sample, a φ6 circular sample was punched to prepare a test piece.
(Polyamide thermoplastic elastomer)
“Uvesta XPA9048X1 (Tg: −20 ° C.)” manufactured by Ube Industries, Ltd. (described as “PE1” in Table 1 below)
“Uvesta XPA9055X1 (Tg: 5 ° C.)” manufactured by Ube Industries, Ltd. (described as “PE2” in Table 1 below)
In the manufacturing method of Examples 1-8, the heating process of the circular sample was implemented on the temperature conditions of Table 1, and the heating time.
In the manufacturing methods of Comparative Examples 1 and 3, no heating step was performed. Moreover, in the manufacturing methods of Comparative Examples 2 and 4, as shown in Table 1, the heating step was performed outside the range of temperature conditions defined in the present invention.

<Evaluation of dynamic viscoelasticity>
Using a circular sample having a diameter of 6 mm and a thickness of 2 mm, tan δ at 30 ° C. to 20 Hz was measured using a dynamic viscoelasticity measuring apparatus (Dynamic Mechanical Analysis DMA) manufactured by TA Instruments. Was measured. The results are listed in Table 1 below.

<Evaluation of heat resistance, tensile strength, elongation at break, and tensile modulus>
Similarly, the plate-like sample was punched out to produce a dumbbell-shaped test piece (No. 5 type test piece) defined in JISK6251-1993.
Using a Shimadzu Corp., Shimadzu Autograph AGS-J (5KN), the tensile speed was set to 200 mm / min, and the tensile modulus, tensile strength, and elongation at break of each sample piece were measured. The results are shown in Table 1 below.

It can be seen that the elastomer molded body formed by the production method of the present invention has good heat resistance, and the rolling friction resistance is maintained at an appropriate value from the measurement result of dynamic viscoelasticity (tan δ). That is, the dynamic viscosity elasticity (tan δ) was reduced by 20% or more through the heating step in the production method of the present invention. This corresponds to a reduction of about 10% in the rolling resistance of the tire. Therefore, the tire obtained by the production method of the present invention has excellent running performance regardless of the temperature conditions during use. It can be seen that it is possible to improve the fuel efficiency of the vehicle.
On the other hand, in the elastomer molded body in which the heating step is not performed or the heating step is performed under the temperature condition specified in the present invention, either the heat resistance or the dynamic viscoelasticity is inferior, and the comparative example From the comparison between 1 and Comparative Example 2 or Comparative Example 3 and Comparative Example 4, it can be seen that even if a heating step outside the temperature range of the present invention is performed, these physical properties are hardly improved.

10 tire 12 bead portion 16 crown portion (outer peripheral portion)
18 Beadcore
20 Rim 21 Bead sheet 22 Rim flange 17 Tire case (tire frame)
24 Seal layer (seal part)
26 Reinforcement cord (reinforcement cord member)
28 Reinforcing cord layer 30 Tread D Diameter of reinforcing cord (diameter of reinforcing cord member)
L Embedding amount of reinforcement cord (embedding amount of reinforcement cord member)

Claims (4)

A method of manufacturing a tire formed of a material including at least a thermoplastic resin material,
A tire skeleton forming step of forming an annular tire skeleton using a material containing a thermoplastic resin material, and the obtained tire skeleton, the glass transition temperature of the thermoplastic resin material contained in the tire skeleton ( And a heating step of heating at a temperature not lower than (Tg) and not higher than (Tg + 200 ° C.).   The tire manufacturing method according to claim 1, wherein the heating step is a step of heating the tire frame body for 0.2 hours to 6 hours.   The tire manufacturing method according to claim 1, wherein the thermoplastic resin contains a thermoplastic elastomer.   The thermoplastic elastomer is a polyamide-based thermoplastic elastomer, the heating temperature in the heating step is in the range of 40 ° C to 250 ° C, and the heating time is in the range of 0.5 hours to 4 hours. Tire manufacturing method.