WO2023228464A1

WO2023228464A1 - Tire

Info

Publication number: WO2023228464A1
Application number: PCT/JP2023/000859
Authority: WO
Inventors: 恭平松本; 倩呉
Original assignee: 株式会社ブリヂストン
Priority date: 2022-05-26
Filing date: 2023-01-13
Publication date: 2023-11-30
Also published as: JP2023173880A

Abstract

The problem addressed by the present invention is to provide a tire that improves steering stability and that can maintain plunger durability even when made light in weight. The solution for this problem is a tire (100), equipped with a belt (60) that comprises at least two belt layers (60A, 60B) disposed in a tread section (30) and belt reinforcement layers (70A, 70B) that are disposed on the outer sides, in the tire radial direction, of the belt (60). The tire (100) is characterized in that: the belt layers (60A, 60B) and the belt reinforcement layers (70A, 70B) are formed by covering a reinforcement material with an elastomer; the reinforcement material of the belt layers (60A, 60B) is metal monofilaments with a filament diameter d of less than 0.30 mm; and the reinforcement material of the belt reinforcement layers (70A, 70N) is organic fiber cords with a break strength of at least 6.5 cN/dtex, a cutting elongation of at least 10%, and an elastic modulus, when stretched by 7%, of at least 6.0 mN/(dtex∙%).

Description

tire

The present invention relates to tires.

Generally, a carcass containing reinforcing cords buried along the meridian direction of a ring-shaped tire body is placed inside the tire where strength is required, and a belt is placed on the outside of the carcass in the tire radial direction. layers are arranged. The belt layer is usually formed using a metal cord-elastomer composite obtained by coating a metal cord such as a steel cord with an elastomer, and provides the tire with load resistance, traction resistance, etc.

In recent years, there has been an increasing demand for lighter tires in order to improve the fuel efficiency of automobiles. Metal cords for belt layers are attracting attention as a means of reducing the weight of tires, and many techniques have been published that use metal filaments as cords for belt layers without twisting them.
For example, Patent Document 1 below discloses a steel cord for reinforcing a tire in which a thermoplastic elastomer composition in which an elastomer is dispersed in a thermoplastic resin is coated around a steel cord body made of a single monofilament, and a steel cord using the same. Tires are disclosed.
In addition, Patent Document 2 below discloses that two to six main filaments of the same diameter are arranged in parallel to form a single layer without being twisted to form a main filament bundle, and one A pneumatic radial tire is disclosed in which a steel cord formed by wrapping a main steel filament as a wrapping filament around a main filament bundle is used as a belt layer of the tire.

Japanese Patent Application Publication No. 2010-053495 JP2012-106570A

By forming a belt layer by coating a metal monofilament with an elastomer, as proposed in Patent Document 1 and Patent Document 2, the weight of the tire can be reduced by making the belt layer thinner. However, the present inventors have investigated that tires using a belt layer made of a metal monofilament coated with an elastomer have reduced plunger durability (durability against protrusion input) and poor handling stability. It was found that the results were not sufficient and there was room for improvement.

Therefore, an object of the present invention is to solve the problems of the above-mentioned prior art and provide a tire that is lightweight, maintains plunger durability, and has improved handling stability.

The gist of the tire of the present invention that solves the above problems is as follows.

[1] A tire comprising a belt consisting of at least two belt layers disposed in the tread portion, and a belt reinforcing layer disposed on the outside of the belt in the tire radial direction,
The belt layer and the belt reinforcing layer are formed by covering a reinforcing material with an elastomer,
The reinforcing material of the belt layer is a metal monofilament with a filament diameter d of less than 0.30 mm,
The reinforcing material of the belt reinforcing layer is an organic fiber cord having a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN/(dtex・%) or more. A tire characterized by:

[2] The tire according to [1], wherein the metal monofilament as a reinforcing material for the belt layer has a filament diameter d of 0.15 mm or more.

[3] The tire according to [1] or [2], wherein the belt layer is formed by coating a metal cord, which is a bundle of a plurality of metal monofilaments aligned in a line without being twisted together, with an elastomer.

[4] The tire according to [3], wherein the distance w ₁ between adjacent metal monofilaments constituting the metal cord is 0.01 mm or more and less than 0.24 mm.

[5] The filament diameter d (mm) of the metal monofilament, the distance w ₁ (mm) between adjacent metal monofilaments forming the metal cord, and the number n (pieces) of metal monofilaments forming the metal cord. However, the following formula (1):
0.45≦[(d/2) ² ×π×n]/{d×[d×n+w ₁ ×(n-1)]}≦0.77... (1)
[In the formula, d is the filament diameter (mm) of the metal monofilament, _w1 is the distance (mm) between adjacent metal monofilaments that make up the metal cord, and n is the diameter of the metal monofilament that makes up the metal cord. The tire according to [3] or [4], which satisfies the following relationship: the number of tires (pieces), where d>0, w ₁ >0, and n is an integer.

[6] The ratio G/w ₂ of the distance G between the surfaces of the metal monofilaments embedded in two adjacent belt layers in the belt and the distance w ₂ between the metal cords is 1.6. The following is
The ratio w ₁ /W of the interval w ₁ between adjacent metal monofilaments constituting the metal cord and the width W of the metal cord is 0.07 or more,
[3] to [5], wherein the ratio d/w ₁ of the filament diameter d of the metal monofilament to the distance w ₁ between adjacent metal monofilaments constituting the metal cord is 1.2 or more and less than 2. Tires listed in any one of the above.

[7] The tire according to any one of [1] to [6], wherein the belt layer has a thickness t of 0.8 mm or less.

[8] The tire according to any one of [1] to [7], wherein the organic fiber cord as a reinforcing material of the belt reinforcing layer is a cord made of polyethylene terephthalate.

[9] The belt includes a first belt layer and a second belt layer laminated on the outside of the first belt layer in the tire radial direction,
The shortest distance a between the metal monofilament of the second belt layer and the metal monofilament of the first belt layer in the tire center part, and the distance between the metal monofilament of the end of the second belt layer and the metal monofilament of the first belt layer. The shortest distance b is the following formula (2):
1.8≦b/a≦4.0... (2)
[In the formula, a is the shortest distance between the metal monofilament of the second belt layer and the metal monofilament of the first belt layer in the tire center part, and b is the shortest distance between the metal monofilament of the end of the second belt layer and the first belt The tire according to any one of [1] to [8], which satisfies the following relationship: [the shortest distance between the layer and the metal monofilament].

According to the present invention, it is possible to provide a tire that is lightweight, maintains plunger durability, and has improved handling stability.

1 is a sectional view of one embodiment of a tire of the present invention. FIG. 3 is a diagram showing a load-elongation curve of a cord. FIG. 1 is a partial cross-sectional view in the width direction of a belt layer according to an embodiment of the tire of the present invention. FIG. 1 is a schematic plan view of metal cords of a belt layer according to an embodiment of a tire of the present invention. FIG. 2 is an explanatory diagram relating to the definition of the ratio of the cross-sectional area of a metal monofilament included in the cross-section of a metal cord. FIG. 1 is an enlarged partial cross-sectional view of a belt according to an embodiment of the tire of the present invention. FIG. 3 is a schematic plan view of metal cords of a belt layer according to another embodiment of the tire of the present invention. FIG. 3 is a schematic cross-sectional view in the width direction of a metal cord of a belt layer according to another embodiment of the tire of the present invention. FIG. 2 is an explanatory diagram of a metal monofilament showing definitions of a molding amount and a molding pitch of the metal monofilament. FIG. 3 is a schematic cross-sectional view in the width direction of a metal cord of a belt layer according to another embodiment of the tire of the present invention. FIG. 3 is a schematic plan view of metal cords of a belt layer according to another embodiment of the tire of the present invention. FIG. 3 is a schematic cross-sectional view in the width direction of a metal cord of a belt layer according to another embodiment of the tire of the present invention. FIG. 2 is an explanatory diagram of a metal monofilament showing definitions of a molding amount and a molding pitch of the metal monofilament. FIG. 3 is a schematic cross-sectional view in the width direction of a metal cord of a belt layer according to another embodiment of the tire of the present invention. FIG. 3 is a schematic cross-sectional view in the width direction of a metal cord of a belt layer according to another embodiment of the tire of the present invention. FIG. 3 is a schematic plan view of metal cords of a belt layer according to another embodiment of the tire of the present invention. FIG. 3 is a schematic cross-sectional view in the width direction of a metal cord of a belt layer according to another embodiment of the tire of the present invention. It is a schematic sectional view of the end part of the belt concerning other embodiments of the tire of the present invention. It is a schematic sectional view of the center part of the belt concerning other embodiments of the tire of the present invention.

Below, the tire of the present invention will be illustrated in detail based on its embodiments.

The tire of this embodiment includes a belt consisting of at least two belt layers disposed in the tread portion, and a belt reinforcing layer disposed on the outside of the belt in the tire radial direction. In the tire of the present embodiment, the belt layer and the belt reinforcing layer are formed by covering a reinforcing material with an elastomer, and the reinforcing material of the belt layer is a metal monofilament with a filament diameter d of less than 0.30 mm. , the reinforcing material of the belt reinforcing layer is an organic fiber having a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN/(dtex・%) or more. It is characterized by being a code.

The tire of this embodiment includes a belt layer formed by covering a metal monofilament with a filament diameter d of less than 0.30 mm with an elastomer, and since the belt layer is thin, it is lightweight.
In addition, if a tire only has a belt layer containing metal monofilament, the in-plane rigidity of the belt layer will be lower than that of a normal belt layer, resulting in a decrease in plunger durability (durability against protrusion input). Although the steering stability is not sufficient, the tire of this embodiment has a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN. /(dtex・%) or more is provided with a belt reinforcing layer made of an organic fiber cord coated with an elastomer, and the belt reinforcing layer supplements the rigidity of the belt layer, suppressing a decrease in plunger durability, and further , it is possible to improve steering stability.
Therefore, the tire of this embodiment maintains plunger durability, is lightweight, and has improved steering stability.

Next, one embodiment of the tire of the present invention will be illustrated in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of one embodiment of the tire of the present invention. The tire 100 shown in FIG. 1 includes a pair of bead portions 10, a pair of sidewall portions 20, a tread portion 30, and a carcass 50 extending in a toroidal shape between bead cores 40 embedded in the bead portions 10. A belt 60 consisting of two

belt layers

60A and 60B disposed on the tread portion 30 (more specifically, disposed on the outside in the tire radial direction of the crown portion of the carcass 50), and a belt 60 on the outside of the belt 60 in the tire radial direction. A belt reinforcing layer (also called a "cap layer") 70A arranged so as to cover the entire belt reinforcing layer 70A, and a pair of belt reinforcing layers (also called "layer layers") arranged so as to cover only both ends of the belt reinforcing layer 70A. ) 70B.

In the tire 100 shown in FIG. 1, the carcass 50 is composed of one carcass ply, and includes a main body portion extending in a toroidal shape between a pair of bead cores 40 respectively embedded in the bead portion 10, and It consists of a folded part that is wound radially outward from the inside to the outside in the tire width direction around the bead core 40, but in the tire of the present invention, the number of plies and structure of the carcass 50 are not limited to this. do not have. Here, the carcass ply constituting the carcass 50 is preferably formed by covering a plurality of reinforcing cords with an elastomer, which extend in a direction substantially perpendicular to the tire circumferential direction (for example, extend at an angle of 70 to 90 degrees). That is, the carcass 50 is preferably a radial carcass. As the reinforcing cord of the carcass 50, a steel cord may be used in addition to an organic fiber cord such as a polyethylene terephthalate cord, a nylon cord, or a rayon cord.

Furthermore, the belt 60 of the tire 100 shown in FIG. The belt is made of a metal monofilament (reinforcement material) coated with an elastomer, preferably a steel monofilament coated with an elastomer, and further includes two

belt layers

60A and 60B. The metal monofilaments constituting the

layers

60A and 60B are laminated to intersect with each other with the tire equatorial plane interposed therebetween, thereby constituting the belt 60.
Note that the belt 60 in the figure is composed of two

belt layers

60A and 60B (hereinafter, the belt layer 60A may be referred to as a "first belt layer" and the belt layer 60B as a "second belt layer". ), in the tire of the present invention, the number of belt layers constituting the belt may be two or more and is not limited to this.
Since the metal monofilament serving as the reinforcing material for the belt layers 60A and 60B has a filament diameter d of less than 0.30 mm, the thickness of the belt layers 60A and 60B can be reduced, contributing to weight reduction of the tire. Here, the filament diameter d of the metal monofilament as a reinforcing material for the belt layer is preferably 0.15 mm or more, and preferably 0.28 mm or less. When the filament diameter d of the metal monofilament is 0.15 mm or more, the plunger durability and steering stability of the tire are further improved, and when it is 0.28 mm or less, the tire becomes even lighter.

The metal monofilament (also referred to as "single wire") only needs to satisfy the filament diameter d described above, and its specific structure is not particularly limited. For example, as the metal monofilament, a straight metal monofilament, a metal monofilament twisted around the axis, a metal monofilament with a flat cross section, a metal monofilament shaped into a spiral shape, a metal monofilament shaped into a plane wave shape, etc. are used. be able to.

Further, in the tire 100 shown in FIG. 1, the

belt reinforcing layers

70A and 70B include organic fiber cords (reinforcing material) arranged substantially parallel to the tire circumferential direction (for example, at an angle of 0 to 5 degrees with respect to the tire circumferential direction). ) is coated with an elastomer. The

belt reinforcing layers

70A and 70B are formed by continuously winding a narrow strip prepared by covering an organic fiber cord with an elastomer in a spiral shape in the tire circumferential direction. In this case, since there is no joint in the circumferential direction of the tire, the uniformity of the tire is good, and since there is no joint, concentration of strain on the joint can be prevented.
Although the tire 100 shown in FIG. 1 includes the belt reinforcing layer 70A and the belt reinforcing layer 70B, a tire in which either one of the belt reinforcing layer 70A and the belt reinforcing layer 70B is omitted is also included in the tire of the present invention. This is an embodiment. Further, in the tire 100 shown in FIG. 1, each of the

belt reinforcing layers

70A and 70B is one layer, but may be two or more layers.
The organic fiber cord that is the reinforcing material for the

belt reinforcing layers

70A and 70B has a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN/(dtex. %), the rigidity is high and the effect of reinforcing the belt 60 (belt layers 60A, 60B) is high, contributing to improving the plunger durability and steering stability of the tire.

In the carcass 50, the belt 60 (belt layers 60A, 60B), and the

belt reinforcing layers

70A, 70B, the elastomer that covers the reinforcing material (reinforcing cord) is not particularly limited, and various elastomers can be used.
The elastomer preferably has a 50% modulus value of 1.5 MPa or more, more preferably 1.8 MPa or more, even more preferably 2.0 MPa or more, as measured in accordance with JIS K 6251 (2010). be. When such an elastomer is used to cover the reinforcing material (reinforcing cord), even when the reinforcing material (reinforcing cord) is stretched in the longitudinal direction, the elastomer inside the carcass 50, belt 60, and

belt reinforcing layers

70A and 70B Since the reinforcing material has high rigidity, it can prevent the reinforcing material (reinforcing cord) from stretching in the longitudinal direction, thereby further improving the steering stability of the tire.

The main components of the elastomer include natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR, high cis BR and low cis BR), nitrile rubber ( NBR), hydrogenated NBR, hydrogenated SBR and other diene rubbers and their hydrogenated products, ethylene-propylene rubber (EPDM, EPM), maleic acid-modified ethylene-propylene rubber (M-EPM), butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymers, acrylic rubber (ACM), olefin rubbers such as ionomers, Br-IIR, Cl-IIR, brominated isobutylene-paramethylstyrene copolymers (Br-IPMS), Halogen-containing rubbers such as chloroprene rubber (CR), hydrin rubber (CHR), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), maleic acid-modified chlorinated polyethylene rubber (M-CM), methyl vinyl silicone rubber , silicone rubber such as dimethyl silicone rubber, methylphenyl vinyl silicone rubber, sulfur-containing rubber such as polysulfide rubber, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicone rubber, Examples include rubbers such as fluororubbers such as fluorophosphazene rubber, and thermoplastic elastomers such as styrene elastomers, olefin elastomers, ester elastomers, urethane elastomers, and polyamide elastomers. The 50% modulus value of the elastomer (covered rubber) was measured in accordance with JIS K 6251 (2010) after vulcanizing the rubber composition of each sample at 145°C for 40 minutes to form a vulcanized rubber. This is the value.

Furthermore, in addition to sulfur, a vulcanization accelerator, and carbon black, the elastomer may contain an anti-aging agent, zinc oxide (zinc white), stearic acid, etc., which are commonly used in rubber products such as tires. can.

The organic fiber cord applied to the

belt reinforcing layers

70A and 70B has a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN/(dtex・%). ) That's it. Here, the cutting strength, cutting elongation, and elastic modulus at 7% elongation of the organic fiber cord are values measured at room temperature (23° C.). Further, various physical properties of the organic fiber cord can be measured according to JIS L 1013 "Chemical fiber filament yarn testing method".
The elastic modulus at 7% elongation is calculated by converting the slope (N/%) of the tangent at the point corresponding to 7% elongation of the load-elongation curve of the cord into a value per 1 dtex. The slope of the tangent at the point corresponding to 7% elongation on the load-elongation curve means the slope of the tangent S at the point corresponding to 7% elongation on the load-elongation curve C of the cord as shown in FIG.
Organic fiber cords with a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN/(dtex %) or more have high strength when cut, Since the elongation when cut is large and the elastic modulus at 7% elongation is high, organic fiber cords with such physical properties are applied to the belt reinforcement layer to supplement the rigidity of the belt layer, making it possible to apply belt layers containing metal monofilaments. It is possible to improve the steering stability of the tire while suppressing a decrease in plunger durability due to

The material of the organic fiber cord is not particularly limited, but includes polyester such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), nylon such as 6-nylon, 6,6-nylon, and 4,6-nylon, and rayon. , Lyocell, and other celluloses. Among these, polyethylene terephthalate is preferred; that is, the organic fiber cord as a reinforcing material for the

belt reinforcing layers

70A and 70B is a cord made of polyethylene terephthalate (hereinafter sometimes simply referred to as "polyethylene terephthalate cord"). It is preferable. Polyethylene terephthalate cord has higher rigidity than commonly used nylon cord and the like, and is excellent in improving tire plunger durability and steering stability.

It is preferable that the organic fiber cord has an elastic modulus of 2.5 mN/(dtex·%) or more under a load of 29.4 N measured at 160°C. Here, the elastic modulus at a load of 29.4N measured at 160°C is calculated by dividing the slope (N/%) of the tangent at the point corresponding to the load of 29.4N on the load-elongation curve of the cord measured at 160°C by 1 dtex. It is calculated by converting it into a hit value.
The reason why the elastic modulus is measured at 160°C is because the temperature inside the tire increases as the tire travels at high speeds, and by the time tire failure occurs during high-speed driving, the temperature of the belt reinforcing layer has reached 160°C. . In particular, the elastic modulus of polyethylene terephthalate cords decreases significantly at high temperatures compared to normal temperatures, and even if the cord is highly elastic at room temperature, if it cannot maintain a high elastic modulus at high temperatures, it will not have sufficient belt reinforcing effect. Therefore, the elastic modulus at high temperatures is of important significance. By setting the elastic modulus of the cord at 29.4N load measured at 160℃ to 2.5mN/(dtex・%) or more, the plunger durability of the tire can be improved, and it can also improve the elasticity during high-speed driving. The amount of protrusion of the belt can be suppressed, reducing stress when the tire is pressed in and out, improving the steering stability of the tire when driving at high speeds.

In order to improve the elastic modulus of the organic fiber cord at 160°C, it is preferable to perform the dipping treatment under high tension. The present inventors adjusted the tension applied to the cord during dipping treatment, produced organic fiber cords with various elastic moduli, covered the obtained dipped cord with an elastomer, applied it to a belt reinforcing layer, and applied it to a tire tire. As a result of examining the plunger durability and handling stability of the tire, the plunger durability of the tire was determined when the elastic modulus of the cord at a load of 29.4N measured at 160°C was 2.5mN/(dtex・%) or more. It was also found that the improvement in handling stability was significant.

Here, in order to make the cord sufficiently highly elastic, it is preferable that the tension at the time of adhesive treatment be 6.9×10 ⁻² N/tex or more. However, the method of increasing the elasticity of the cord is not limited to this, and other methods such as reducing the twist of the cord may be used. The adhesive treatment includes dry treatment, hot treatment, normalization treatment, etc., and is performed by appropriately adjusting temperature and time in addition to tension. In the present invention, the adhesive treatment may be performed in either one-bath treatment or two-bath treatment, but it is preferable to perform adhesive treatment in two ^- bath treatment. It is preferable to apply it to the cord during hot processing.

The organic fiber cord has the following formula (3):
α=T×D ^1/2 ... (3)
[In the formula, α is the twist coefficient, T is the number of twists (twists/100 mm), and D is the total fineness (dtex) of the cord] It is preferable that the twist coefficient α is 500 to 2,500. When the twist coefficient α of the cord is 500 or more, the binding force of the filament is strong and the adhesion is sufficient, and when it is 2500 or less, the effect of improving the durability against protrusion input and the effect of suppressing the protrusion of the belt can be obtained. It can exhibit sufficient elastic modulus.

Further, it is preferable that the organic fiber cord has a total fineness of 1000 to 3500 dtex. When the total fineness of the cord is 1000 dtex or more, sufficient elastic modulus can be exhibited to improve durability against protrusion input and suppress belt protrusion, and when it is 3500 dtex or less, dense driving is possible. , sufficient rigidity per unit width can be ensured.

Note that green tires expand by several percent in the tire radial direction during vulcanization, so if the elastic modulus of the cord used for the belt reinforcement layer is high, it will not be able to follow the expansion of the tire during vulcanization molding, and the organic There is a possibility that the fiber cord and the metal monofilament in the belt layer come into direct contact without using an elastomer (covering rubber). Therefore, in addition to designing the diameter of the raw tire to a certain size in advance, the tension between the belt and the cord of the belt reinforcement layer is adjusted appropriately when winding the elastomer-covered cord to form the belt reinforcement layer. It is preferable to secure a sufficient gauge. Therefore, it is preferable that the elongation rate of the organic fiber cord in the tire after vulcanization is 2% or less relative to the original length of the cord before vulcanization. When a tire is molded with a cord elongation rate of 2% or less, contact between the organic fiber cord and the belt can be suppressed, and separation at the end of the belt can be suppressed from occurring during running.

The raw material for the organic fiber cord is not particularly limited, and may be derived from synthetic products, biological origin, mechanically recycled material obtained by crushing, melting, and respinning PET products such as PET bottles, or PET products such as PET bottles, etc. It may also be derived from chemical recycling by depolymerizing and repolymerizing PET products such as bottles.

Further, the form of the organic fiber cord is not particularly limited, and may be a single-twist structure or a twisted structure (double-twist structure, etc.). In the case of a single-twist structure, for example, a twisted yarn cord can be obtained by aligning the raw yarns and twisting them in one direction. In addition, in the case of a double-twisted structure, for example, a twisted yarn cord can be obtained by first twisting the raw yarn, then combining a plurality of these yarns and applying final twisting in the opposite direction.

The organic fiber cord (particularly the polyethylene terephthalate cord) may contain an adhesive composition containing a thermoplastic polymer (A), a heat-reactive water-based urethane resin (B), and an epoxy compound (C), or these (A) - An adhesive composition comprising rubber latex (D) in addition to (C), wherein the main chain of the thermoplastic polymer (A) substantially has an addition-reactive carbon-carbon double bond. First, it is preferable to perform adhesive treatment with an adhesive composition characterized by having at least one functional group having crosslinking properties as a pendant group. By treating the cord with the adhesive composition, the adhesiveness of the cord to the elastomer (covering rubber) at high temperatures can be improved.

Conventionally, as an adhesive treatment for organic fiber cords (especially polyethylene terephthalate cords), epoxy or isocyanate is applied to the cord surface, and then a resin (hereinafter referred to as RFL resin) made by mixing resorcinol, formaldehyde, and latex is applied onto the cord surface. A so-called two-bath treatment is being carried out. However, with such means, the resin used in the first bath becomes very hard, which increases the strain input to the cord and reduces the fatigue resistance of the cord. Further, such resins can exhibit sufficient adhesion between the cord and the elastomer at room temperature, but the adhesion may be extremely reduced at high temperatures of 130° C. or higher. On the other hand, a thermoplastic polymer (A) which has at least one functional group having crosslinking properties as a pendant group and which does not substantially contain addition-reactive carbon-carbon double bonds in its main chain structure and By using a one-bath mixed solution containing a reactive water-based urethane resin (B) and an epoxy compound (C), the cord can be sufficiently bonded to the elastomer (covering rubber) even at high temperatures of 180°C or higher without curing the cord. can be secured.

The main chain of the thermoplastic polymer (A) mainly has a linear structure, and examples of the main chain include ethylene polymers such as acrylic polymers, vinyl acetate polymers, and vinyl acetate/ethylene polymers. Polymers with added properties or urethane-based polymers are preferred. However, the thermoplastic polymer (A) only needs to have the function of suppressing the resin fluidity at high temperatures and ensuring the breaking strength of the resin by crosslinking the functional groups of the pendant groups. It is not limited to ethylenic addition polymers and urethane-based polymers.

Further, as the functional group of the pendant group of the thermoplastic polymer (A), an oxozaline group, a bismaleimide group, a (blocked) isocyanate group, an aziridine group, a carbodiimide group, a hydrazino group, an epoxy group, an epithio group, etc. are preferable.

Examples of the monomer constituting the ethylenic addition polymer include an ethylenically unsaturated monomer having one carbon-carbon double bond, and a monomer containing two or more carbon-carbon double bonds. It will be done. Here, as the ethylenically unsaturated monomer having one carbon-carbon double bond, α-olefins such as ethylene, propylene, butylene, and isobutylene; styrene, α-methylstyrene, monochlorostyrene, vinyltoluene, α,β-unsaturated aromatic monomers such as vinylnaphthalene and sodium styrene sulfonate; ethylenic carboxylic acids and their salts such as itaconic acid, fumaric acid, maleic acid, acrylic acid, methacrylic acid, and butenetricarboxylic acid; Acid anhydrides such as maleic anhydride and itaconic anhydride; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, methoxypolyethylene (meth)acrylate Glycol, esters of unsaturated carboxylic acids such as 2-hydroxyethyl (meth)acrylate, and 2-aminoethyl (meth)acrylate; monoethyl itaconic acid, monobutyl fumarate, monobutyl maleate, etc. Monoesters of ethylenic dicarboxylic acids; diesters of ethylenic dicarboxylic acids such as diethyl itaconate and dibutyl fumarate; acrylamide, maleic acid amide, N-methylolacrylamide, N-(2-hydroxyethyl)acrylamide, methacryl Amides of α,β-ethylenically unsaturated acids such as amide, N-methylolmethacrylamide, N-(2-hydroxyethyl)methacrylamide, maleic acid amide; 2-hydroxyethyl (meth)acrylate, polyethylene glycol mono( Hydroxyl group-containing monomers such as meth)acrylate; unsaturated nitriles such as acrylonitrile, methaacrylonitrile, fumaronitrile, α-chloroacrylonitrile; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl ketone; vinyl amide; vinyl chloride, vinylidene chloride, vinyl fluoride , halogen-containing α,β-unsaturated monomers such as vinylidene fluoride; vinyl compounds such as vinyl acetate, vinyl valerate, vinyl caprylate, and vinylpyridine; addition polymerizability of 2-isopropenyl-2-oxazoline, etc. Examples include oxazolines; heterocyclic vinyl compounds such as vinylpyrrolidone; unsaturated bond-containing silane compounds such as vinylethoxysilane and α-methacryloxypropyltrimethoxysilane; these may be used alone or in combination of two or more. May be used together. In the present invention, it is preferable to obtain the polymer (A) by radical addition polymerization of these monomers. In addition, monomers constituting the main chain skeleton containing two or more carbon-carbon double bonds include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-butadiene, - Conjugated diene monomers such as halogen-substituted butadiene such as dimethyl-1,3-butadiene and chloroprene, and non-conjugated diene monomers include vinylnorbornene, dicyclopentadiene, 1,4 Examples include non-conjugated diene monomers such as -hexadiene, which may be used alone or in combination of two or more.

The ethylenic addition polymer is composed of units derived from an ethylenically unsaturated monomer having one carbon-carbon double bond and a monomer containing two or more carbon-carbon double bonds, and the total monomer The monomer composition ratio of sulfur-reactive carbon-carbon double bonds is preferably 10 mol% or less, more preferably 0 mol%, based on the amount charged.

The method of introducing a crosslinkable functional group into the ethylenic addition polymer to form the thermoplastic polymer (A) is not particularly limited. For example, addition polymerizable monomers having oxazoline, addition polymerizable monomers having epoxy groups, addition polymerizable monomers having maleimide, addition polymerizable monomers having blocked isocyanate groups, and addition polymerizable monomers having epithio groups. A method of copolymerizing an addition polymerizable monomer or the like when polymerizing the ethylenic addition polymer can be adopted.

In addition, the urethane-based high molecular weight polymers mainly contain urethane bonds obtained by polyaddition reaction of polyisocyanate and a compound having two or more active hydrogens, or urea bonds between isocyanate groups and active hydrogens. It is a high-molecular polymer that has many bonds within its molecules due to reactions. In addition, not only bonds resulting from the reaction between isocyanate groups and active hydrogen, but also ester bonds, ether bonds, amide bonds contained within active hydrogen compound molecules, and uretdione, carbodiimide, etc. generated by reactions between isocyanate groups. It may also be a polymer containing

The heat-reactive aqueous urethane resin (B) is preferably a resin having two or more thermally dissociable blocked isocyanate groups in one molecule. For example, the following general formula (4):

[In the formula, A represents an isocyanate residue of an organic polyisocyanate compound having 3 to 5 functional groups, Y represents an active hydrogen residue of a blocking agent compound that releases isocyanate groups by heat treatment, and Z represents at least 1 X is an active hydrogen residue of a compound having 2 to 4 active hydrogen atoms and at least one anion-forming group, and X is an active hydrogen residue of a polyol compound having 2 to 4 hydroxyl groups and an average molecular weight of 5000 or less. , n is an integer of 2 to 4, and p+m is an integer of 2 to 4 (m≧0.25)] is particularly preferred.

The epoxy compound (C) may be any compound containing two or more, preferably four or more, epoxy groups in one molecule, and may be a reaction between a compound containing an epoxy group, a polyhydric alcohol, and epichlorohydrin. Products are preferred. Specific examples of epoxy compounds include diethylene glycol diglycidyl ether, polyethylene diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and glycerol polyglycidyl ether. Reaction of polyhydric alcohols such as ether, trimethylolpropane polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, and sorbitol polyglycidyl ether with epichlorohydrin. Products; novolac type epoxy resins such as phenol novolak type epoxy resins and cresol novolac type epoxy resins; bisphenol A type epoxy resins and the like.

The rubber latex (D) is preferably vinylpyridine-styrene-butadiene copolymer latex, styrene-butadiene copolymer latex, etc., but is not particularly limited.

The organic fiber cord (especially polyethylene terephthalate cord) can be prepared by using the three types (A), (B), and (C) as the one-bath treatment liquid, and using the normal RFL liquid as the two-bath treatment liquid. is preferred. It is also possible to process the mixture of (A), (B), (C), and (D) in only one bath. In addition, the dry weight ratio of each of these components is (A) 2 to 75% of the dry weight of the adhesive composition, (B) 15 to 87%, (C) 11 to 70%, and (D) 20%. % or less.

The belt reinforcing layer is preferably formed by treating the organic fiber cord with an adhesive, coating it with an elastomer to form a narrow strip, and then continuously winding the strip in a spiral shape in the tire circumferential direction.

Next, embodiments of the belt layer of the tire of the present invention will be illustrated and described. FIG. 3 is a partial cross-sectional view in the width direction of a belt layer according to an embodiment of the tire of the present invention, and FIG. 4 is a schematic plan view of a metal cord of the belt layer according to an embodiment of the tire of the present invention. be.

The belt layer 60A (60B) shown in FIG. 3 is a metal cord 2 made of a bundle of a plurality of metal monofilaments 1 that are not twisted together but are aligned in a line, and is coated with an elastomer 3. The thickness of the belt layer 60A (60B) can be reduced by covering the metal cord 2, which is a bundle of a plurality of metal monofilaments 1 in a line without twisting them together, with an elastomer 3 and applying it to the belt layer 60A (60B). It becomes thinner, making the tire even lighter.

Here, the number of metal monofilaments 1 is preferably 2 or more, more preferably 5 or more, and preferably 20 or less, more preferably 12 or less, still more preferably 10 or less, particularly preferably 9 or less. The metal cord 2 is made up of a bundle of . In the belt layer 60A (60B) shown in FIG. 3, five metal monofilaments 1 are aligned without being twisted together to form a metal cord 2. With such a configuration, the thickness of the belt layer 60A (60B) can be reduced, and the weight of the tire can be reduced.

The distance w ₁ between adjacent metal monofilaments 1 constituting the metal cord 2 is preferably 0.01 mm or more and less than 0.24 mm. In this way, by providing the gap _w1 in the above range between adjacent metal monofilaments 1, it becomes possible to sufficiently penetrate the elastomer 3, and as a result, the metal cord 2 can be deformed out of plane when compressed. It can suppress the bending of metal cords. Further, by setting the interval w ₁ between the metal monofilaments 1 to be less than 0.24 m, separation between the metal monofilaments 1 in the metal cord 2 can be suppressed. On the other hand, when the distance w ₁ between the metal monofilaments 1 is set to 0.01 mm or more, the elastomer 3 sufficiently penetrates between the metal monofilaments 1 in the metal cord 2 . The distance w ₁ between the metal monofilaments 1 is more preferably 0.03 mm or more and 0.20 mm or less, even more preferably 0.03 mm or more and 0.18 mm or less.

In the bundle of metal monofilaments 1, it is difficult for the elastomer to penetrate between closely adjacent monofilaments, resulting in a non-elastomer-covered area that is not covered by the elastomer, and in the non-elastomer-covered area, the metal monofilaments are mutually displaced when the tire rolls. As a result, the in-plane rigidity of the belt may decrease. However, in the belt layer 60A (60B) shown in FIG. 3, since the elastomer 3 sufficiently penetrates between the adjacent metal monofilaments 1, non-elastomer-covered regions are unlikely to occur, and the in-plane rigidity of the belt is sufficiently improved. , the plunger durability and steering stability of the tire can be further improved.

In the belt layer 60A (60B), the existence of continuous non-elastomer coated areas between adjacent metal monofilaments is eliminated to ensure corrosion resistance, improve the in-plane rigidity of the belt, and improve tire plunger durability. In order to obtain a favorable effect of improving performance and handling stability, it is preferable that the elastomer coverage of the adjacent metal monofilaments 1 on the side surfaces in the width direction of the metal cord 2 is 10% or more per unit length, It is more preferably 20% or more, still more preferably 50% or more, even more preferably 80% or more, and particularly preferably 90% or more.
Here, the elastomer coverage rate refers to, for example, using rubber as the elastomer, coating a metal monofilament with rubber, vulcanizing it, pulling the metal monofilament out of the obtained rubber-metal monofilament composite, and applying it to the gap between the metal monofilaments. Measure the length of the side surface in the width direction of the metal monofilament that is covered with the infiltrated rubber, and calculate the following formula:
Elastomer coverage = (rubber coverage length/sample length) x 100 (%)
The average of the values calculated based on
Note that the calculation can be performed in the same manner even when an elastomer other than rubber is used as the elastomer.

In the belt layer 60A (60B), the filament diameter (also referred to as "strand diameter", "wire diameter", or simply "diameter") d of the metal monofilament 1 is less than 0.30 mm, and preferably is 0.15 mm or more, more preferably 0.18 mm or more, even more preferably 0.20 mm or more. By setting the filament diameter d of the metal monofilament 1 to less than 0.30 mm, a sufficient weight reduction effect of the tire can be obtained. Further, by setting the filament diameter d of the metal monofilament 1 to 0.15 mm or more, the strength of the belt layer is improved, and the plunger durability and steering stability of the tire are further improved.

In the belt layer 60A (60B) shown in FIG. 3, the distance _w2 between the metal cords 2 measured in the direction perpendicular to the extending direction of the metal cords 2 is 0.25 mm or more and 2.0 mm or less. preferable. By setting the interval w ₂ between the metal cords 2 to be 0.25 mm or more, it is possible to suppress belt edge separation in which elastomer peeling starting from the cord ends at the ends in the belt width direction propagates between adjacent metal cords. . Furthermore, by setting the interval w2 between the metal cords ₂ to 2.0 mm or less, the rigidity of the belt can be maintained. The distance _w2 between the metal cords 2 is more preferably 0.3 mm or more and 1.8 mm or less, and still more preferably 0.35 mm or more and 1.5 mm or less.

The thickness t of the belt layer 60A (60B) is preferably 0.8 mm or less, and preferably more than 0.30 mm. By setting the thickness t of the belt layer to 0.8 mm or less, the weight of the tire can be further reduced. Further, by setting the thickness t of the belt layer to more than 0.30 mm, the strength of the belt can be improved, and the plunger durability and steering stability of the tire can be further improved.

In the belt layer 60A (60B), the metal monofilament 1 is preferably steel, that is, a linear metal whose main component is iron (the mass of iron with respect to the total mass of the metal monofilament exceeds 50% by mass), It may be composed only of iron, or it may contain metals other than iron, such as zinc, copper, aluminum, and tin.

In the belt layer 60A (60B), the surface state of the metal monofilament 1 is not particularly limited, but may take the following form, for example. That is, as for the metal monofilament 1, it is preferable that the N atoms on the surface be 2 atomic % or more and 60 atomic % or less, and the Cu/Zn ratio on the surface be 1 or more and 4 or less. In addition, as for the metal monofilament 1, the amount of phosphorus contained as an oxide in the outermost layer of the metal monofilament up to 5 nm inward in the radial direction of the metal monofilament from the surface of the metal monofilament is 7.0 as a proportion of the total amount excluding the amount of C. It is preferably at most atomic %.

In the belt layer 60A (60B), the surface of the metal monofilament 1 may be plated. The type of plating is not particularly limited, and examples include zinc (Zn) plating, copper (Cu) plating, tin (Sn) plating, brass (copper-zinc (Cu-Zn)) plating, and bronze (copper-tin (Cu-Zn)) plating. In addition to Cu--Sn) plating, ternary plating such as copper-zinc-tin (Cu-Zn-Sn) plating and copper-zinc-cobalt (Cu-Zn-Co) plating can be mentioned. Among these, brass plating and copper-zinc-cobalt plating are preferred. This is because the brass-plated metal monofilament has excellent adhesion to the elastomer (coated rubber). In addition, in brass plating, the ratio of copper to zinc (copper:zinc) is usually 60 to 70:30 to 40 on a mass basis, and in copper-zinc-cobalt plating, the ratio of copper to zinc is usually 60 to 75% by mass, Cobalt is 0.5-10% by weight. Further, the thickness of the plating layer is preferably 100 nm or more and 300 nm or less.

In the belt layer 60A (60B), there are no particular limitations on the tensile strength or cross-sectional shape of the metal monofilament 1. For example, as the metal monofilament 1, one having a tensile strength of 2500 MPa (250 kg/mm ² ) or more can be used. Furthermore, the cross-sectional shape of the metal monofilament 1 in the width direction is not particularly limited, and may be circular, elliptical, rectangular, triangular, polygonal, or the like. Moreover, it is preferable that the metal monofilament 1 is a substantially straight metal monofilament, as shown in FIG. Here, a straight metal monofilament refers to a metal monofilament that is not intentionally shaped and is substantially unshaped. Note that in the belt layer 60A (60B) shown in FIG. 3, wrapping filaments (spiral filaments) may be used if it is necessary to restrain the bundle of metal monofilaments 1 constituting the metal cord 2.

The belt layer 60A (60B) can be manufactured by a known method. For example, a steel cord can be manufactured by lining up a bundle of metal monofilaments in parallel at a predetermined interval and covering them with an elastomer (coating rubber). The sample can then be manufactured by vulcanization under standard conditions. Further, the metal monofilament can also be molded using a conventional molding machine and according to a conventional method.

The filament diameter d (mm) of the metal monofilament 1, the distance w ₁ (mm) between adjacent metal monofilaments 1 constituting the metal cord 2, and the number n (mm) of the metal monofilaments 1 constituting the metal cord 2. ) means the following formula (1):
0.45≦[(d/2) ² ×π×n]/{d×[d×n+w ₁ ×(n-1)]}≦0.77 (1)
It is preferable that the following relationship is satisfied.
In formula (1), d is the filament diameter (mm) of the metal monofilament 1, and _w1 is the distance between adjacent metal monofilaments 1 (" (also referred to as "distance between surfaces" or "gap amount") (mm), n is the number (pieces) of metal monofilaments 1 constituting the metal cord 2, provided that d>0, and w ₁ >0, and n is an integer.

w ₁ >0, that is, since a gap is provided between adjacent metal monofilaments 1, the elastomer 3 will enter the gap, and the continuous non-elastomer covered area between the metal monofilaments 1 will be eliminated. Therefore, it becomes possible to sufficiently infiltrate the elastomer between adjacent metal monofilaments 1. As a result, the metal cord can be deformed out of plane during compression input, and bending of the metal cord can be suppressed. Further, since there is no water passage path for water when the tire is damaged and flooded, corrosion resistance is greatly improved. Furthermore, since the adjacent metal monofilaments 1 are restrained by the elastomer 3, the adjacent metal monofilaments do not shift from each other even when the tire is rolling, and as a result, the in-plane rigidity of the belt can be improved. The plunger durability and steering stability of the tire can be further improved.

FIG. 5 shows an explanatory diagram related to the regulation of the ratio of the cross-sectional area of the metal monofilament included in the cross-section of the metal cord. In FIG. 5, seven metal monofilaments 1 are aligned without being twisted to form a metal cord 2. Specifically, seven unshaped straight metal monofilaments 1 are arranged at equal intervals. They are arranged in parallel with a gap and covered with an elastomer 3. Here, the term "equally spaced gaps" means a range that includes manufacturing errors.
The above formula (1) defines the ratio of the cross-sectional area of the metal monofilament 1 to one metal cord 2, with the cross-sectional area of the dotted line in the figure being the cross-sectional area of the metal cord 2. That is, the cross-sectional area of the dotted line in the figure (cross-sectional area of the metal monofilament 1 + cross-sectional area of the elastomer 3) is the denominator {d×[d×n+w ₁ ×(n-1)]} in the above formula (1). The cross-sectional area of the metal monofilament 1 included in the dotted line portion in the figure is represented by [(d/2) ² ×π×n] of the molecule in the above formula (1).

A metal cord 2 consisting of a bundle of metal monofilaments 1 aligned with a predetermined gap is used, and the ratio of the cross-sectional area of the metal monofilaments 1 included in the cross section of the metal cord 2 is defined within a predetermined range. As a result, light weight, plunger durability, handling stability, corrosion resistance, separation resistance of the belt layer, etc. can be improved in a well-balanced manner.

From the viewpoint of obtaining each performance in a well-balanced manner, the following formula (1'):
0.48≦[(d/2) ² ×π×n]/{d×[d×n+w ₁ ×(n-1)]}≦0.77 (1')
It is more preferable that the following relationship is satisfied, and the following formula (1''):
0.50≦[(d/2) ² ×π×n]/{d×[d×n+w ₁ ×(n-1)]}≦0.77 (1”)
It is even more preferable to satisfy the following relationship.

FIG. 6 shows an enlarged partial cross-sectional view of a belt according to an embodiment of the tire of the present invention. In FIG. 6, the distance (also referred to as "interlayer gauge") G between the surfaces of the metal monofilaments 1 embedded in two

adjacent belt layers

60A and 60B within the belt 60, and the distance w between the metal cords 2 ₂ , the ratio G/w ₂ is preferably 1.6 or less. Further, in FIG. 6, the ratio w ₁ /W between the interval w ₁ between adjacent metal monofilaments 1 constituting the metal cord 2 and the width W of the metal cord 2 is preferably 0.07 or more. Furthermore, in FIG. 6, the ratio d/w ₁ between the filament diameter d of the metal monofilament 1 and the distance w ₁ between adjacent metal monofilaments 1 constituting the metal cord 2 is 1.2 or more and less than 2. preferable.

Ratio G/w ₂ of the distance G between the surfaces of the metal monofilaments 1 between

adjacent belt layers

60A and 60B and the distance w ₂ between the metal cords 2, the distance between the metal monofilaments 1 constituting the metal cords 2 The ratio w ₁ /W between w ₁ and the width W of the metal cord, and the ratio d/w between the filament diameter d of the metal monofilament 1 and the distance w ₁ between adjacent metal monofilaments 1 constituting the metal cord 2 ₁ satisfies the above range, it is possible to achieve weight reduction and low rolling resistance without deteriorating distortion between the belt layers, plunger durability and steering stability of the tire. Become. The ratio G/w ₂ is more preferably 0.2 or more and 1.6 or less, even more preferably 0.4 or more and 1.4 or less. Further, the ratio w ₁ /W is more preferably 0.07 or more and 0.18 or less, even more preferably 0.07 or more and 0.15 or less. Furthermore, the ratio d/w ₁ is more preferably 1.3 or more and less than 2, even more preferably 1.4 or more and less than 2.

The distance G between the surfaces of the metal monofilaments 1 embedded in two adjacent belt layers in the belt (also referred to as "interlayer gauge") is preferably 0.10 mm or more and 0.60 mm or less, and more preferably is 0.35 mm or more and 0.45 mm or less. By setting the interlayer gauge G to 0.10 mm or more and 0.60 mm or less, it is possible to achieve a well-balanced effect of suppressing strain between the belt layers and achieving light weight and low rolling resistance. When the interlaminar gauge G becomes smaller, the belt layer becomes thinner, which is advantageous in terms of weight reduction and lower rolling resistance, but interlaminar strain deteriorates.

In FIGS. 3 and 4 described above, the metal monofilament 1 is a substantially straight metal monofilament, but in the tire of the present invention, the shape of the metal monofilament may be other than straight.

FIG. 7 is a schematic plan view of the metal cord of the belt layer according to another embodiment of the tire of the present invention, and FIG. 8 is a schematic plan view of the metal cord of the belt layer according to another embodiment of the tire of the present invention in the width direction. It is a schematic sectional view.

The metal cord 2 shown in FIGS. 7 and 8 includes adjacent metal monofilaments 1 in which at least one of the amount of patterning and the patterning pitch in the direction perpendicular to the extending direction of the metal monofilament 1 is different. At least one pair exists. Preferably, in 50% or more of the pairs, adjacent metal monofilaments 1 differ in at least one of the amount of patterning and the patterning pitch in the direction perpendicular to the extending direction of the metal monofilaments 1.
Here, FIG. 9 is an explanatory diagram of a metal monofilament showing definitions of the molding amount h and the molding pitch p of the metal monofilament, and the molding amount h refers to the width of variation of the metal monofilament 1 that does not include the filament diameter. Note that the molding amount h of the metal monofilament 1 is measured by projecting the metal monofilament 1 after molding with a projector and projecting the projected image of the metal monofilament on a screen or the like.

In FIGS. 7 and 8, shaped metal monofilaments 1a and unshaped metal monofilaments 1b (embossed amount 0 mm, embossed pitch ∞mm) are arranged alternately, but metal monofilaments with different embossed amounts are arranged alternately. They may be arranged alternately, or metal monofilaments with different patterning pitches may be arranged alternately. Preferably, the arrangement of the metal monofilaments constituting the bundle is such that both sides of the metal monofilaments are straight metal monofilaments that are not shaped. In this way, by arranging the metal monofilaments 1 having different molding amounts or molding pitches adjacent to each other, it is possible to avoid matching the phases of the two. With such a configuration, it is possible to sufficiently infiltrate the elastomer between the adjacent metal monofilaments 1, and as a result, the metal cord can be deformed out of plane during compression input, and bending of the metal coat can be suppressed.

In the belt layer, if the molding amount h of the metal monofilament 1 is too large, the distance _w2 between the metal cords 2 in the belt layer becomes short, causing a decrease in the strength of the belt. Therefore, the molding amount h of the metal monofilament 1 is preferably about 0.03 to 0.30 mm. If the molding amount h is 0.30 mm or less, a decrease in the strength of the belt layer can be sufficiently suppressed. In particular, from the viewpoint of the distance w ₂ between the metal cords 2 and the strength of the metal monofilament 1, when applying the mold to the metal monofilament 1, the molding amount h is preferably 0.03 to 0.30 mm, more preferably 0. 0.03 to 0.25 mm, more preferably 0.03 to 0.20 mm. Further, the molding pitch p of the metal monofilament 1 is preferably 2 to 30 mm, more preferably 2 to 20 mm, even more preferably 3 to 15 mm.

In the metal cord 2 shown in FIGS. 7 and 8, the molded metal monofilament 1a is molded in the width direction of the metal cord 2, but the molding direction of the metal monofilament 1 in the belt layer is It may be inclined with respect to the width direction of the cord 2. FIG. 10 is a schematic cross-sectional view in the width direction of the metal cord of the belt layer of another embodiment of the tire of the present invention. Even with such a structure, it is possible to sufficiently infiltrate the elastomer between adjacent metal monofilaments 1. However, from the viewpoint of lightness, it is preferable that the patterning direction of adjacent metal monofilaments 1 be in the width direction of the metal cord 2 because the belt layer can be made thinner.

Further, in the belt layer, it is preferable that at least one of the metal monofilaments 1 in the metal cord 2 is a substantially straight metal monofilament. As shown in FIGS. 7 and 8, when an unshaped straight metal monofilament 1b and a shaped metal monofilament 1a are adjacent to each other, a large amount of elastomer infiltrates between the two metal monofilaments 1. The elastomer coverage of the matching metal monofilament 1 on the side surfaces in the width direction of the metal cord 2 is increased. Furthermore, by using straight metal filaments as the metal monofilaments 1 placed at both ends of the metal cord 2, the distance _w2 between adjacent metal cords 2 in the elastomer can be increased, improving durability. can be done. Further, as shown in FIG. 7, it is more preferable that unshaped straight metal monofilaments 1b and shaped metal monofilaments 1a are alternately arranged.

FIG. 11 is a schematic plan view of the metal cord of the belt layer according to another embodiment of the tire of the present invention, and FIG. 12 is a widthwise direction of the metal cord of the belt layer according to another embodiment of the tire of the present invention. It is a schematic sectional view.

In the metal cord 2 shown in FIGS. 11 and 12, all the metal monofilaments 1 are molded with the same molding amount and the same pitch, and there are pairs of metal monofilaments in which adjacent metal monofilaments have different phases. There is at least one.
Here, FIG. 13 is an explanatory diagram of a metal monofilament showing definitions of the patterning amount h and the patterning pitch p of the metal monofilament, and the patterning amount h refers to the width of variation of the metal monofilament 1 that does not include the filament diameter. Note that the molding amount h of the metal monofilament 1 is measured by projecting the metal monofilament 1 after molding with a projector and projecting the projected image of the metal monofilament on a screen or the like.

As in the metal cord 2 shown in FIGS. 11 and 12, the phases of the metal monofilaments 1 having the same molding amount h and the same molding pitch p are made to be different, thereby preventing the two phases from matching. With this configuration, it is possible to sufficiently infiltrate the elastomer between adjacent metal monofilaments 1, and as a result, the metal cord can be deformed in-plane during compression input, reducing fatigue of the metal cord. It can prevent sexual deterioration.

In FIGS. 11 and 12, adjacent metal monofilaments have different phases at at least one location in the metal cord 2, but the phase difference is preferably from π/4 to 7π/4. By setting the phase difference within this range, it becomes possible to further sufficiently infiltrate the elastomer between the adjacent metal monofilaments 1. More preferably, the phase difference is π/2 to 3π/2, and particularly preferably, the phase difference is π.

In the belt layer, if the molding amount h of the metal monofilament 1 is too large, the distance _w2 between the metal cords 2 will become short, causing a decrease in the strength of the belt. Therefore, the molding amount h of the metal monofilament 1 is preferably about 0.03 to 0.30 mm. When the molding amount h is 0.30 mm or less, a decrease in the strength of the belt layer can be sufficiently suppressed. In particular, from the viewpoint of the distance w ₂ between the metal cords 2 and the strength of the metal monofilament 1, when applying the mold to the metal monofilament 1, the molding amount h is preferably 0.03 to 0.30 mm, more preferably 0. 0.03 to 0.25 mm, more preferably 0.03 to 0.20 mm. Further, the molding pitch p of the metal monofilament 1 is preferably 2 to 30 mm, more preferably 2 to 20 mm, and even more preferably 3 to 15 mm.

In the metal cord 2 shown in FIGS. 11 and 12, the molded metal monofilament 1 is molded in the width direction of the metal cord 2, but the molding direction of the metal monofilament 1 is in the width direction of the metal cord 2. It may be tilted against. FIG. 14 is a schematic cross-sectional view in the width direction of the metal cord of the belt layer of another embodiment of the tire of the present invention. Even with such a structure, it is possible to sufficiently infiltrate the rubber between adjacent metal monofilaments 1. However, from the viewpoint of lightness, it is preferable that the patterning direction of adjacent metal monofilaments 1 be in the width direction of the metal cord 2 because the belt layer can be made thinner.

Further, in the belt layer, the molding is not limited to two-dimensional molding, but may be three-dimensional molding. FIG. 15 is a schematic cross-sectional view in the width direction of the metal cord of the belt layer of still another embodiment of the tire of the present invention. In the illustrated example, the metal monofilament 1 is spiral-shaped, and five spiral-shaped metal monofilaments 1 are aligned in a row without being twisted together to form the metal cord 2.

FIG. 16 is a schematic plan view of the metal cord of the belt layer according to another embodiment of the tire of the present invention, and FIG. 17 is a schematic plan view of the metal cord of the belt layer according to another embodiment of the tire of the present invention in the width direction. It is a schematic sectional view.

In the metal cord 2 shown in FIGS. 16 and 17, there is at least one pair of adjacent metal monofilaments 1 that differ in at least one of the amount of three-dimensional molding and the molding pitch. Preferably, in 50% or more of the pairs, adjacent metal monofilaments 1 differ in at least one of the amount of three-dimensional molding and the molding pitch.
Here, the embossed amount h and the embossed pitch p of the metal monofilament are as shown in FIG. 13, and the embossed amount h refers to the range of variation that does not include the filament diameter of the metal monofilament 1. Note that the molding amount h of the metal monofilament 1 is measured by projecting the metal monofilament 1 after molding with a projector and projecting the projected image of the metal monofilament on a screen or the like.

In FIGS. 16 and 17, spirally shaped metal monofilaments 1a and unshaped metal monofilaments 1b (textured amount 0 mm, patterned pitch ∞mm) are arranged alternately. In this way, by arranging the metal monofilaments 1 having different molding amounts or molding pitches adjacent to each other, it is possible to avoid matching the phases of the two. With such a configuration, it is possible to sufficiently infiltrate the elastomer between the adjacent metal monofilaments 1, and as a result, the metal cord can be deformed out of plane during compression input, and bending of the metal cord can be suppressed.

In the belt layer, if the molding amount h of the metal monofilament 1 is too large, the distance _w2 between the metal cords 2 will become short, causing a decrease in the strength of the belt. Therefore, the molding amount h of the metal monofilament 1 is preferably about 0.10 to 0.50 mm. In particular, from the viewpoint of the distance w ₂ between the metal cords 2 and the strength of the metal monofilament, the molding amount h is preferably 0.2 to 0.3 mm. Furthermore, the molding pitch p of the metal monofilament 1 is preferably 5 mm or more, more preferably 8 to 20 mm.

Further, in the belt layer, it is preferable that at least one of the metal monofilaments 1 in the metal cord 2 is a substantially straight metal monofilament. As shown in FIGS. 16 and 17, when an unshaped straight metal monofilament 1b and a shaped metal monofilament 1a are adjacent to each other, a large amount of elastomer infiltrates between the two metal monofilaments 1. The elastomer coverage of the metal monofilament 1 on the side surfaces in the width direction of the metal cord 2 is increased. Furthermore, by using straight metal monofilaments as the metal monofilaments 1 placed at both ends of the metal cord 2, the distance _w2 between adjacent metal cords 2 in the elastomer can be increased, which improves the durability of the belt. can be improved. Moreover, as shown in FIGS. 16 and 17, it is more preferable that unshaped straight metal monofilaments 1b and shaped metal monofilaments 1a are arranged alternately.

Next, other embodiments of the belt related to the tire of the present invention will be illustrated and described.
FIG. 18 is a schematic cross-sectional view of an end portion of a belt according to another embodiment of the tire of the present invention. The belt 60 shown in FIG. 18 includes a first belt layer 60A and a second belt layer 60B laminated on the outside of the first belt layer 60A in the tire radial direction. In the illustrated example, the belt is composed of two belt layers, but the belt may be composed of three or more belt layers.

In addition, in the belt 60 shown in FIG. 18, the shortest distance a between the metal monofilament 1B of the second belt layer 60B and the metal monofilament 1A of the first belt layer 60A at the tire center portion, and the end of the second belt layer 60B. The shortest distance b between the metal monofilament 1B and the metal monofilament 1A of the first belt layer 60A is expressed by the following formula (2):
1.8≦b/a≦4.0
It is preferable that the following relationship is satisfied.
In formula (2), a is the shortest distance between the metal monofilament of the second belt layer and the metal monofilament of the first belt layer in the tire center portion, and b is the shortest distance between the metal monofilament of the end of the second belt layer and the metal monofilament of the first belt layer. This is the shortest distance between one belt layer and the metal monofilament.

In this way, by increasing the distance between the metal monofilaments of each of the first belt layer 60A and the second belt layer 60B at the belt end, which is the starting point of belt edge separation, strain at the belt end is suppressed and the durability is improved. Belt edge separation properties can be improved. By setting b/a to 1.8 or more, the durability of the belt ends (particularly, the belt edge separation durability) can be sufficiently improved. Further, by setting the b/a to 4.0 or less, sufficiently low rolling resistance can be ensured. More preferably, the following formula (2'):
1.8≦b/a≦3.8
satisfies the relationship.

In order to increase the distance between the metal monofilaments of the first belt layer 60A and the second belt layer 60B at the end of the belt, in the illustrated example, between the first belt layer 60A and the second belt layer 60B, , the belt interlayer rubber 4 is arranged, but the thickness of the elastomer (covering rubber) 3 at the ends of the belt layers 60A, 60B may be increased, or the ends of the belt layers 60A, 60B may be It may also be wrapped in a rubber sheet. Note that the same material as the elastomer (covering rubber) 3 of the first belt layer 60A and second belt layer 60B can be used for the rubber sheet wrapping the end portions of the belt interlayer rubber 4 and the belt layers 60A and 60B.

FIG. 19 is a schematic cross-sectional view of the center portion of a belt according to another embodiment of the tire of the present invention, which is the portion surrounded by a broken line in FIG. 18. In FIG. 19, the distances c1 and c2 from both upper and lower surfaces of the first belt layer 60A at the tire center portion to the metal monofilament 1A are both 0.14 mm or less, and the distances c1 and c2 from the upper and lower surfaces of the first belt layer 60A at the tire center portion are both 0.14 mm or less, and It is preferable that the distances c3 and c4 from both the upper and lower surfaces to the metal monofilament 1B are both 0.14 mm or less. With such a configuration, the low rolling resistance of the tire can be sufficiently improved.

Depending on the type of tire to which it is applied, the tire of the present invention may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, or by using a semi-vulcanized rubber that has undergone a pre-vulcanization process, etc. After molding, it may be obtained by further main vulcanization. Note that members other than the belt (belt layer) and belt reinforcing layer of the tire of the present invention are not particularly limited, and known members can be used.
Further, the tire of the present invention is preferably a pneumatic tire, and the gas filled in the pneumatic tire may include normal or air with adjusted oxygen partial pressure, as well as inert gas such as nitrogen, argon, helium, etc. Gas can be used.

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples.

(Preparation of rubber-steel cord composite)
A steel cord (steel monofilament) having the specifications shown in Comparative Examples 1 to 4 and Reference Example 1 in Table 1 was covered with a sheet of about 0.5 mm thick made of a rubber composition (elastomer) from both the upper and lower sides, and A cord-rubber composite was produced.
The rubber composition for coating was prepared by adding 61 parts by mass of carbon black (N326, DPB oil absorption = 72 mL/100 g, N ₂ SA = 78 m ² /g) and zinc oxide to 100 parts by mass of natural rubber, according to a conventional method. 5 parts by mass, 1 part by mass of an antiaging agent (N-phenyl-N'-1,3-dimethylbutyl-p-phenylenediamine, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Nocrac 6C"), 1 part by mass of a sulfur accelerator (N,N'-dicyclohexyl-2-benzothiazylsulfenamide, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Noxela DZ"), and sulfur (insoluble sulfur, manufactured by Flexis Co., Ltd., It was prepared by blending and kneading 5 parts by mass (trade name: "Crystex HS OT-20").
The obtained steel cord-rubber composite was vulcanized at 160° C. for 20 minutes, and the following evaluations were performed.

Here, the metal cord of Comparative Example 3 is one in which steel monofilaments with a filament diameter of 0.35 mm are evenly arranged without being twisted. Further, the metal cord of Reference Example 1 is a cord consisting of a bundle of five steel monofilaments each having a filament diameter of 0.26 mm, which are aligned in a row without being twisted. Further, the metal cord of Comparative Example 4 is a cord made of a bundle of three steel monofilaments each having a diameter of 0.3 mm and arranged in a line without being twisted.

<Belt weight>
A belt layer sample was prepared using the obtained steel cord-rubber composite, and its weight was measured and expressed as an index with the belt weight of Comparative Example 1 as 100. The smaller the numerical value is, the lighter the weight is, which is preferable.

(Evaluation using tires)
A passenger car tire with a tire size of 195/65R15 having the structure shown in FIG. 1 except for not having a belt reinforcing layer was produced by applying each steel cord-rubber composite to two belt layers. The belt angle was ±28° with respect to the tire circumferential direction.

<Rolling resistance>
For each test tire, rolling resistance was measured using a rolling resistance tester in accordance with SAE J 1269. The results were expressed as an index with Comparative Example 1 set as 100. The smaller the number, the better the result.

<Interlayer strain>
For each test tire, the magnitude of strain between the two belt layers was calculated using the finite element method (FEM). The results were expressed as an index with Comparative Example 1 set as 100. The smaller the number, the better the result. However, if it is within the range of 95 to 105, it will be evaluated as being at the same level.

<Maneuvering stability>
Using interlaced belt layer samples prepared using each of the steel cord-rubber composites of Comparative Examples 1 to 4 and Reference Example 1, in-plane stiffness was evaluated by a conventional method and used as an index of handling stability. The results are indexed with the in-plane stiffness value of Comparative Example 1 as 100, and based on this index value, if it is less than 90, it is ×, if it is 90 or more and less than 100, it is △, and if it is 100 or more and less than 110. A score of 110 or more was evaluated as a score of ◎.

Next, for Reference Examples 2 to 7 in Table 1, the belt weight, rolling resistance, and steering stability were evaluated under the same conditions as above, and the evaluation results were determined as predicted values. Further, for Reference Examples 2 to 7 shown in Table 1, interlayer strain was evaluated using the finite element method (FEM) in the same manner as above.
These results are shown in Table 1 below.

*1 The cords of Comparative Examples 1 and 2 are cords with an oval cross section, and the filament diameter of the metal filament in Comparative Examples 1 and 2 is the average cord diameter [(major axis 0.64 mm + minor axis 0.53 mm)/2] means.
*2 The cords of Comparative Examples 1 and 2 are cords with an elliptical cross section, and the distance between the metal monofilaments (inter-cord distance) varies depending on the direction in which the cord is implanted.

From the results in Table 1, it can be seen that by applying to the tire a belt layer formed by covering a metal monofilament with a filament diameter d of less than 0.30 mm with an elastomer, the weight of the tire can be reduced.

<Effect of belt reinforcement layer>
In the tires shown in Reference Examples 1 to 7 in Table 1, the outer side of the belt in the tire radial direction has a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.5 cN/dtex. By providing a belt reinforcing layer made of a cord made of polyethylene terephthalate of 0 mN/(dtex・%) or more and covered with an elastomer, the belt reinforcing layer supplements the rigidity of the belt, improving the plunger durability and steering stability of the tire. It can be confirmed that the performance improves.

<Effects of belt interlayer rubber>
In the tires shown in Reference Examples 1 to 7 in Table 1, the outer side of the belt in the tire radial direction has a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.5 cN/dtex. A belt reinforcing layer is provided in which a cord made of polyethylene terephthalate of 0 mN/(dtex・%) or more is coated with an elastomer, and further, a belt reinforcing layer is provided at the ends of the belt (the ends of the first belt layer and the ends of the second belt layer). By arranging the belt interlayer rubber between the parts (between the parts) and setting b/a in the above formula (2) to 1.8 to 4.0, distortion at the belt end is suppressed, and the belt end part of the tire It can be confirmed that the durability of

100: Tire, 10: Bead portion, 20: Sidewall portion, 30: Tread portion, 40: Bead core, 50: Carcass, 60: Belt, 60A: Belt layer (first belt layer), 60B: Belt layer (second 70A: Belt reinforcement layer (cap layer), 70B: Belt reinforcement layer (layer layer), C: Cord load-elongation curve, S: Cord load-elongation curve at a point corresponding to 7% elongation. Tangent line, 1, 1A, 1B: Metal monofilament, 2: Metal cord, 3: Elastomer (coated rubber), w ₁ : Distance between adjacent metal monofilaments constituting the metal cord, w ₂ : Distance between metal cords, t : Thickness of the belt layer, d: Filament diameter of the metal monofilament (strand diameter, wire diameter, diameter), G: Distance between the surfaces of the metal monofilaments embedded in two adjacent belt layers in the belt ( (interlayer gauge), h: patterning amount of metal monofilament, p: patterning pitch of metal monofilament, 1a: patterned metal monofilament, 1b: unshaped metal monofilament, 4: belt interlayer rubber

Claims

A tire comprising a belt consisting of at least two belt layers disposed in a tread portion, and a belt reinforcing layer disposed on the outside of the belt in the tire radial direction,
The belt layer and the belt reinforcing layer are formed by covering a reinforcing material with an elastomer,
The reinforcing material of the belt layer is a metal monofilament with a filament diameter d of less than 0.30 mm,
The reinforcing material of the belt reinforcing layer is an organic fiber cord having a cutting strength of 6.5 cN/dtex or more, a cutting elongation of 10% or more, and an elastic modulus at 7% elongation of 6.0 mN/(dtex・%) or more. A tire characterized by:
The tire according to claim 1, wherein the metal monofilament as a reinforcing material for the belt layer has a filament diameter d of 0.15 mm or more.
2. The tire according to claim 1, wherein the belt layer is made of a metal cord made of a bundle of metal monofilaments arranged in a line without being twisted together and coated with an elastomer.
The tire according to claim 3, wherein a distance w1 between adjacent metal monofilaments constituting the metal cord is 0.01 mm or more and less than 0.24 mm.
The filament diameter d (mm) of the metal monofilament, the distance w 1 (mm) between adjacent metal monofilaments forming the metal cord, and the number n (pieces) of metal monofilaments forming the metal cord are as follows: Formula (1):
0.45≦[(d/2) 2 ×π×n]/{d×[d×n+w 1 ×(n-1)]}≦0.77... (1)
[In the formula, d is the filament diameter (mm) of the metal monofilament, w1 is the distance (mm) between adjacent metal monofilaments that make up the metal cord, and n is the diameter of the metal monofilament that makes up the metal cord. The tire according to claim 3, which satisfies the following relationship: d>0, w1 >0, and n is an integer.
A ratio G/w 2 of the distance G between the surfaces of the metal monofilaments embedded in two adjacent belt layers in the belt and the distance W 2 between the metal cords is 1.6 or less. ,
The ratio w 1 /W of the interval w 1 between adjacent metal monofilaments constituting the metal cord and the width W of the metal cord is 0.07 or more,
The tire according to claim 3, wherein a ratio d/w 1 between the filament diameter d of the metal monofilament and the distance w 1 between adjacent metal monofilaments constituting the metal cord is 1.2 or more and less than 2.
The tire according to claim 1, wherein the belt layer has a thickness t of 0.8 mm or less.
The tire according to claim 1, wherein the organic fiber cord as a reinforcing material of the belt reinforcing layer is a cord made of polyethylene terephthalate.
The belt includes a first belt layer and a second belt layer laminated on the outside of the first belt layer in the tire radial direction,
The shortest distance a between the metal monofilament of the second belt layer and the metal monofilament of the first belt layer in the tire center part, and the distance between the metal monofilament of the end of the second belt layer and the metal monofilament of the first belt layer. The shortest distance b is the following formula (2):
1.8≦b/a≦4.0... (2)
[In the formula, a is the shortest distance between the metal monofilament of the second belt layer and the metal monofilament of the first belt layer in the tire center part, and b is the shortest distance between the metal monofilament of the end of the second belt layer and the first belt The tire according to claim 1, which satisfies the following relationship: 1. The shortest distance between the layer and the metal monofilament.