JP2023057244A - radial tire - Google Patents

Abstract

To provide a radial tire that uses, in a carcass ply, a polyester fiber tire cord comprising a novel bonding agent that is free of resorcin and formalin and useful for reducing the environmental load, wherein the radial tire ensures good bonding between fiber and rubber and has high-speed durability that bears comparison with the conventional RFL tire cord.SOLUTION: A radial tire comprises a carcass ply comprising a polyester fiber tire cord, disposed inside a tire tread. The polyester fiber tire cord comprises a polyester fiber treated with a bonding agent comprising at least lignin (A), a blocked isocyanate compound (B) and rubber latex (C).SELECTED DRAWING: None

Description

The present invention relates to a radial tire reinforced with carcass ply cords.

In radial tires, the carcass ply is composed of reinforcing fibers and rubber, and synthetic fibers such as rayon fibers, polyamide fibers, polyester fibers, and aromatic polyamide fibers are widely used as the reinforcing fibers. Among them, polyester fibers are widely and generally used in terms of strength, elastic modulus and price. RFL (resorcin-formalin-latex) adhesives containing resorcinol, formalin and rubber latex have been widely used as means for bonding polyester fibers and rubber compositions. However, both resorcin and formalin are deleterious substances, have a high environmental load, and are harmful to health. In recent years, there has been a demand for control of their release into the atmosphere during use and reduction of their usage. On the other hand, an adhesive composition for synthetic fiber cords that does not contain resorcin and formalin and has good adhesiveness and environment, especially working environment, and a rubber reinforcing material using the same are disclosed, for example, in Patent Documents 1 to 4 below. Proposed.

Patent Document 1 discloses an adhesive composition for organic fiber cords containing a urethane resin having a thermally dissociable blocked isocyanate group, an epoxy compound, a polymer having an oxazoline group, a basic catalyst having a number average molecular weight of 1,000 to 75,000, and rubber latex. object is disclosed.

US Pat. No. 6,200,003 discloses a processing method in which a textile reinforcing member is immersed in a bath containing a polycarboxylic acid, a base, an epoxy compound, a polyisocyanate compound, and VP latex.

Patent Document 3 discloses a water-based adhesive composition containing a thermosetting resin having a specific functional group and an unsaturated elastomer latex.

In Patent Document 4, at least one component selected from the group consisting of polyphenols, chlorophenol resins and lignin resins, and at least one selected from water-soluble polymers other than the above components or water-dispersible polymers other than the above components Organic fiber adhesives containing one component are disclosed.

JP 2013-64037 A Japanese Patent Publication No. 2020-525622 Japanese Patent Publication No. 2019-518087 WO2018/003572

However, according to Patent Document 1, although initial adhesive strength and heat-resistant adhesive strength are exhibited at the same level as conventional RFL, fatigue resistance in rubber is not sufficient. According to Patent Literatures 2, 3 and 4, the initial adhesive strength is as high as the conventional RFL, but the heat-resistant adhesive strength and fatigue resistance in rubber are insufficient. In addition, none of Patent Documents 1 to 4 exhibits sufficient strength and durability as a polyester fiber tire cord.

The present invention has been made as a result of studies aimed at solving the problems in the above-described prior art.

An object of the present invention is to provide a radial tire using a polyester fiber tire cord as a carcass ply made of a new adhesive treatment agent that does not contain resorcin and formalin and is advantageous in reducing the environmental load, and has excellent adhesion between the fiber and rubber. To provide a radial tire having a high-speed durability performance equal to or higher than that of a conventional RFL tire cord.

The present invention employs the following means in order to solve such problems.

(1) A radial tire in which a carcass ply made of a polyester fiber tire cord is arranged inside the tread of the tire, the polyester fiber tire cord comprising at least lignin (A), a blocked isocyanate compound (B) and rubber A radial tire comprising a polyester fiber treated with an adhesive agent containing latex (C).

(2) The above (1), wherein the maximum point strength of the dry film of the adhesive treatment agent is 0.2 MPa to 1.6 MPa, and the maximum point elongation is 2% to 120%. radial tire.

(3) The solid content weight ratio of lignin (A) and blocked isocyanate compound (B) in the adhesive agent is (solid content of A):(solid content of B) = 10:1 to 10:30. A radial tire according to the above (1) or (2), characterized in that:

(4) The solid content weight ratio of lignin (A), blocked isocyanate compound (B) and rubber latex (C) in the adhesive agent is ((solid content of A) + (solid content of B)): The radial tire according to any one of (1) to (3) above, wherein (solid content of C)=10:90 to 60:40.

(5) The polyester fiber tire cord is treated with a precoating agent before being treated with the adhesive treatment agent, and the precoating agent comprises an epoxy compound and a blocked isocyanate compound (solid content weight ratio 10:0 10:30). The radial tire according to any one of (1) to (4) above.

(6) The polyester fiber tire cord has a Gurley cord hardness per resin unit attached to the cord of 30 to 80 mN/% or less, and a Gurley cord hardness change rate after heating of 90% to 130%. The radial tire according to any one of (1) to (5) above.

According to the present invention, a radial tire using a carcass ply of a polyester fiber tire cord treated with a novel adhesive treatment agent that does not contain resorcin and formalin and is advantageous in reducing environmental load is obtained. It is possible to obtain a radial tire having excellent high-speed durability performance equal to or higher than that of a conventional RFL tire cord.

1 is a perspective view of a Gurley cord hardness measuring instrument; FIG.

The present invention will be described in detail below.

The radial tire of the present invention has a carcass ply made of a polyester fiber tire cord treated with an adhesive agent containing at least lignin (A), a blocked isocyanate compound (B) and a rubber latex (C). , which are located inside the tread.

The polyester fiber used in the present invention is preferably a fiber obtained by melt-spinning and drawing a polyester containing terephthalic acid as a main difunctional carboxylic acid and ethylene glycol as a main glycol component. ,6-naphthalene dicarboxylic acid, 4,4-dicarboxyphenoxyethane, isocyanate groups, etc., or polyester fibers in which ethylene glycol is partly or entirely replaced with diethylene glycol, propylene glycol, butanediol, etc. can also be used.

Moreover, the above polyester may be obtained by copolymerizing a trifunctional compound such as trimesic acid, trimellitic acid, boric acid, phosphoric acid, glycerin, and trimethylolpropane, if the amount is small.

The polyester fiber used in the present invention has excellent mechanical properties such as high strength, high toughness, high elastic modulus, low shrinkage, and high fatigue resistance required for tire cords, and is exposed to high temperatures in rubber for a long time. In order to suppress adhesion deterioration and strength deterioration even if it is used, it is preferable to have the following characteristics.
(1) Intrinsic viscosity (IV) = 0.7 to 1.2, more preferably 0.8 to 1.1
(2) carboxyl terminal group (COOH) = 10 to 30 eq/t, more preferably 12 to 25 eq/t
(3) Diethylene glycol (DEG) content = 0.5 to 1.5 wt%, preferably 0.5 to 1.2 wt%
(4) Strength (T) = 6.0 to 10.0 cN/dtex, more preferably 7.0 to 9.0 cN/dtex
(5) Elongation (E) = 8 to 20%, more preferably 10 to 16%
(6) Intermediate elongation (ME) = 4.0 to 6.5%, more preferably 4.5 to 6.0%
(7) Dry heat shrinkage (ΔS150°C) = 2.0 to 12.0%, more preferably 3.0 to 10.0%.

High viscosity, low carboxyl end groups, and low diethylene glycol are advantageous for polyester fibers to have chemical durability in tires. The polyester fibers used in the present invention may be modified with terminal carboxyl group blocking agents such as carbodiimide compounds, epoxy compounds, isocyanate compounds and oxazoline compounds in order to reduce carboxy end groups.

Moreover, it may be a polyester fiber to which a polyepoxide compound has been added in advance in the spinning process. Examples of the polyepoxide compound that can be used in the present invention include compounds containing at least two epoxy groups per molecule in an amount of 0.1 g equivalent or more per 100 g of the compound. Specifically, reaction products of polyhydric alcohols such as pentaerythritol, ethylene glycol, polyethylene glycol, propylene glycol, glycerol and sorbitol and halogen-containing epoxides such as epichlorohydrin, peroxides, unsaturated with hydrogen peroxide, etc. Polyepoxide compounds obtained by oxidizing compounds, namely 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexenecarboxylate, bis(3,4-epoxy-6-methyl-cyclohexylmethyl)adipate, phenol novolac type , hydroquinone type, biphenyl type, bisphenol S type, brominated novolac type, xylene-modified novolac type, phenolglyoxal type, trisoxyphenylmethane type, trisphenol PA type, bisphenol type polyepoxides and the like. Particularly preferred are sorbitol glycidyl ether type and cresol novolac type polyepoxides.

These compounds are usually used as an emulsifying liquid, but in order to prepare an emulsifying liquid or a solution, the compound as it is or, if necessary, dissolved in a small amount of a solvent, is mixed with a known emulsifying agent such as, for example, Sodium alkylbenzenesulfonate, dioctylsulfosuccinate sodium salt, nonylphenol ethylene oxide adduct, etc. are used to emulsify or dissolve them.

The polyepoxide compound is applied together with a spinning oil in the polyester fiber spinning process. At this time, the amount of the polyepoxide compound applied is in the range of 0.1 to 5% by weight. If the amount of the polyepoxide compound attached is less than 0.1% by weight, the effect of the polyepoxide compound may not be sufficiently exhibited, and satisfactory adhesiveness may not be obtained between the polyester fiber and the rubber. On the other hand, when the amount of the polyepoxide compound applied exceeds 5% by weight, the fiber becomes very hard, and not only is it difficult to impart it in the spinning process, but also the permeability of the treatment agent to be treated in the subsequent steps decreases. As a result, the adhesion performance is lowered, which is not preferable.

The polyester fiber used in the present invention is not subject to restrictions such as fineness, number of filaments, cross-sectional shape, etc., but usually a total fineness of 200 to 5000 dtex, a filament of 30 to 1000, and a circular cross section yarn are used. ~500 filament, circular section yarn is preferred. If the total fineness is less than 200 dtex, the strength of the cord may be insufficient. On the other hand, if the number of filaments is less than 30 filaments, the cord may become stiff and may be difficult to handle.

The polyester fiber tire cord used in the present invention is obtained by twisting the above polyester fiber into a twisted yarn cord, and then by treating the twisted yarn cord as it is or by weaving it into a fabric and then treating it with an adhesive. Raw cords used for ordinary carcass tire cords are ply-twisted in the S or Z direction, then combined with two or three ply-twisted cords and usually twisted in the same number of plies in the opposite direction to the ply-twisted plied cord. and This twisted cord is treated with an adhesive to obtain a dipped cord. On the other hand, twisted yarn cords are used as warp yarns, and cotton yarns are used as weft yarns, or cotton yarns are covered with synthetic fibers to form weft yarns. After weaving into a woven fabric, the woven fabric is treated with an adhesive to obtain a dipped fabric.

The polyester fiber tire cord to which the adhesive treatment agent of the present invention is adhered and heat-treated refers to both the above-mentioned dipped cord and dipped cord.

The polyester fiber tire cord used in the present invention is obtained by treating polyester fibers with an adhesive agent containing at least lignin (A), blocked isocyanate compound (B) and rubber latex (C). . Here, "treated" means the state of the adhesive agent after applying the adhesive agent to the polyester fiber and then subjecting it to drying treatment and heat treatment. In the drying treatment and heating treatment, for example, volatile matter contained in the adhesive treatment agent, such as solvents such as water, is distilled off, and the blocking agent of the blocked isocyanate is removed, causing a reaction with isocyanate groups. That is, the polyester fibers treated with the adhesive treatment agent are in a state in which the solid content in the adhesive treatment agent is adhered or bonded to the polyester fibers without being chemically modified or modified. The adhesive agent used in the present invention contains an adhesive agent containing at least lignin (A), blocked isocyanate compound (B) and rubber latex (C) in the same bath (one bath). It is.

Lignin (A) used in the present invention is an aromatic polymer present in trees and is known as a natural polymer compound having a phenylpropane skeleton as a basic structure. Lignin (A) includes naturally produced lignin and chemically treated lignin. Such substances include, for example, kraft lignin obtained from kraft pulp effluent and ligninsulfonic acid obtained from sulfite pulp effluent in the papermaking industry process using wood as a raw material. Ligninsulfonic acid is obtained by introducing a sulfone group into the side chain of the phenylpropane structure of lignin. Examples of ligninsulfonates include sodium ligninsulfonate, magnesium ligninsulfonate, and calcium ligninsulfonate. In the present invention, these can be used singly or in combination, but sodium lignosulfonate is most preferably used from the viewpoint of adhesive strength.

The blocked isocyanate compound (B) used in the present invention is a compound capable of liberating the blocking agent by heating to generate an active isocyanate compound. Blocks such as polyisocyanate compounds such as methyrine diisocyanate and triphenylmethane triisocyanate, phenols such as phenol, cresol, and resorcinol, lactams such as ε-caprolactam and valerolactam, and oximes such as acetoxime, methyl ethyl ketoxime, and cyclohexane oxime. reaction products with reagents.

Among these blocked polyisocyanate compounds, an aromatic polyisocyanate compound obtained by blocking diphenylmethane diisocyanate with ε-caprolactam or methylethylketoxime gives good results.

The blocked isocyanate compound (B) preferably has a dissociation temperature of 100 to 160° C. from the viewpoint of improving adhesive strength.

Rubber latex (C) that can be used in the present invention includes, for example, natural rubber latex, butadiene rubber latex, styrene-butadiene-rubber latex, vinylpyridine-styrene-butadiene rubber latex, nitrile rubber latex, hydrogenated nitrile rubber latex, and chloroprene rubber. Latex, chlorosulfonated rubber latex, ethylene/propylene/diene rubber latex and the like can be mentioned, and these can be used alone or in combination.

In addition to the above (A), (B) and (C), the adhesive agent that can be used in the present invention may include, if necessary, a surfactant, a Foaming agents, vulcanization modifiers, antioxidants and pH modifiers may be added.

The adhesion treatment agent used in the present invention contains at least lignin (A), blocked isocyanate compound (B) and rubber latex (C) and is applied (coated film) in the same bath. It is preferable that the dry film of the agent has a maximum point strength of 0.2 MPa to 1.6 MPa and a maximum point elongation of 2% to 120%. The maximum point strength of the dry film is more preferably 0.3 MPa to 1.4 MPa, and the maximum point elongation of the dry film is more preferably 4% to 100%. If the maximum point strength is less than 0.2 MPa, the adhesive strength may be insufficient, and if it exceeds 1.6 MPa, the fatigue resistance may deteriorate. If the maximum point elongation is less than 2%, the fatigue resistance may deteriorate, and if it exceeds 120%, the adhesiveness may be insufficient. The method for adjusting the dry film and the method for measuring the maximum point strength and maximum point elongation are according to the methods described in the Examples section.

The adhesive agent used in the present invention must contain lignin (A), blocked isocyanate compound (B) and rubber latex (C) in the same agent. It is preferable that the maximum point strength and the maximum point elongation of are within the ranges specified above. By doing so, the adhesive treatment agent exhibits excellent adhesion between rubber and fibers and excellent fatigue resistance of fibers in rubber in a high-temperature atmosphere.

The maximum point strength and maximum point elongation of the dry film of the adhesive treatment agent can be adjusted by the chemical species and mixing ratio contained in the adhesive agent. For example, the maximum point strength can be adjusted to be high by increasing the mixed amount of the blocked isocyanate compound (B) in the adhesive treatment agent. Further, for example, the maximum point elongation can be adjusted to be high by mixing rubber latex into the adhesive treatment agent and increasing the amount of the mixture.

In the adhesive agent used in the present invention, the solid content of lignin (A) in 100% by weight of the total solid content is preferably 5 to 50% by weight, more preferably 10 to 40% by weight. is. If it is less than 5% by weight or more than 50% by weight, the adhesive strength may be insufficient.

In addition, the lignin (A) and the blocked isocyanate compound (B) preferably have a weight ratio of (solid content of A):(solid content of B) of 10:1 to 10:30, more preferably 10 : 5 to 10:20. If the amount of the blocked isocyanate compound is too small in the range exceeding this weight ratio, the adhesive strength may be insufficient. sexuality may worsen.

In addition, the lignin (A), the blocked isocyanate compound (B), and the rubber latex (C) have a weight ratio of ((solid content of A) + (solid content of B)):(solid content of C) of 10: It is preferred that they are mixed at 90-60:40. More preferably, the weight ratio of ((solid content of A)+(solid content of B)):(solid content of C) is 20:80 to 50:50. Outside this range, the adhesive strength may be insufficient and the fatigue resistance may be deteriorated.

The adhesive agent used in the present invention has a solid content dissolved or dispersed in water, and the total solid content concentration is preferably 12 to 20% by weight, more preferably 13 to 19% by weight. is good. Outside this range, the adhesive strength may be lowered. Outside this range, it may not be possible to impart a sufficient amount of solids to the fiber, or cohesive failure at the adhesive solids may occur, which may lead to a decrease in adhesion. .

The adhesion amount of the adhesive agent to the polyester fiber is preferably 1 part by weight to 15 parts by weight, more preferably 1.5 parts by weight to 10 parts by weight, based on the solid content of the adhesive agent per 100 parts by weight of the polyester fiber. It is good to be a department. Outside this range, the adhesive strength may be lowered.

The polyester fiber tire cord used in the present invention may be treated with a pre-coating agent before the polyester fiber is treated with the adhesion treatment agent (adhesion treatment agent containing at least lignin, a blocked isocyanate compound and rubber latex). .

The precoating agent preferably contains at least an epoxy compound and a blocked isocyanate compound (solid content weight ratio: 10:0 to 10:30). Outside this range, the adhesive strength may decrease. The amount of the precoating agent attached to the polyester fiber is preferably such that the solid weight of the precoating agent is 0.1 to 3 parts by weight with respect to 100 parts by weight of the polyester fiber. Outside this range, the adhesive strength may be lowered.

The strength of the polyester fiber tire cord used in the present invention is preferably 5.0 to 7.0 cN/dtex, more preferably 5.3 to 6.7 cN/dtex. If it is less than 5.0 cN/dtex, it may not be possible to bear a practical stress in the tire circumferential direction as a tire cord application. A cord having a tensile strength exceeding 7.0 cN/dtex makes it difficult to obtain a practical tire cord from the standpoint of production stability of raw yarn and cost. Here, the cord strength is a value obtained by dividing the strength of the cord by the reference fineness of the cord structure (for example, 2200 dtex if two raw yarns of 1100 dtex are twisted together).

The polyester fiber tire cord used in the present invention has a Gurley cord hardness per resin unit attached to the cord of 30 to 80 mN/% or less, and a Gurley cord hardness change rate after heating of 90 to 130%. is preferred. More preferably, the Gurley cord hardness is 35 to 75 mN/%, and the Gurley cord hardness change rate after heating is 95% to 120%. Within this range, the followability of the cord to the rubber is improved in the composite of rubber and cord, and good adhesive strength can be obtained. The method of adjusting the hardness of the Gurley cord is not particularly limited, but for example, the hardness of the Gurley cord is reduced by reducing the amount of resin adhered, and the hardness of the Gurley cord is improved by increasing the amount of adhered resin. be able to. Furthermore, the hardness of the Gurley cord can be reduced by reducing the heat treatment temperature and/or the heat treatment time during the heat treatment in the dipping step described later, and by increasing the heat treatment temperature and/or the heat treatment time, Gurley cord hardness can be improved. Also, it can be achieved by setting the tension during the mechanical softening process after passing through the normalizing zone of the dipping process to be described later to 0.5 cN to 5.0 cN/dtex.

The radial tire of the present invention characterized by the above is a radial tire that uses polyester fiber tire cords as carcass plies, which are made of a new adhesive treatment agent that is advantageous in reducing environmental load, and which does not contain resorcin and formalin. It is possible to obtain a radial tire having excellent adhesiveness and high-speed durability equal to or higher than that of a conventional RFL tire cord.

Next, a method for manufacturing a radial tire will be described.

In the method for producing a polyester fiber tire cord used for a radial tire of the present invention, an adhesion treating agent containing at least lignin (A), a blocked isocyanate compound (B) and a rubber latex (C) is adhered to polyester fibers in the same bath. It is a method of applying heat treatment.

Here, the adhesive agent preferably has the following characteristics.
(a) The maximum point strength of the dry film of the adhesive treatment agent is 0.2 MPa to 1.6 MPa
(b) The maximum point elongation of the dry film of the adhesive treatment agent is 2% to 120%.

Here, the polyester fiber may be in the form of a twisted yarn cord or a woven fabric, and the twisted yarn cord or woven fabric is dipped in an adhesive treatment agent in a dip bath bath, and then preferably at a temperature of 100 to 150 ° C. A preferred method is to dry the water content with , followed by heat treatment at 200 to 255°C. Preferred embodiments of the lignin (A), blocked isocyanate compound (B), and rubber latex (C) are those described above.

Here, dipping means applying an adhesive treatment agent to the twisted cords or silk fabric by running the twisted yarn cords or silk fabric in a dipping tank in which a roller is installed and which is filled with an adhesive treatment agent. point to The heat treatment refers to heating the twisted cord or the textile by running the twisted yarn cord or the textile in an oven in which rollers are installed and which can be set to a predetermined temperature. A dipping machine for performing such dipping and heat treatment is commercially available from, for example, Ritzler. As another method for attaching the adhesive treatment agent to the polyester fibers, any method such as coating by spraying the adhesive treatment agent from a nozzle, for example, other than the dipping treatment, can be adopted.

Moreover, in order to control the amount of solid matter adhering to the polyester fibers of the adhesive treatment agent, means such as squeezing with a pressure contact roller, scraping off with a scraper, blowing off with air blowing, and suction may be used.

Furthermore, during the mechanical softening treatment step after the above drying and heat treatment, the polyester fiber cord may be brought into sliding contact with the edge to give a softening treatment to obtain an arbitrary cord stiffness.

In the adhesive agent, lignin (A) and blocked isocyanate compound (B) preferably have a weight ratio of (solid content of A):(solid content of B) of 10:1 to 10:30, More preferably 10:5 to 10:20. If the amount of the blocked isocyanate compound is too small in the range exceeding this weight ratio, the adhesive strength may be insufficient. sexuality may worsen.

In addition, the lignin (A), the blocked isocyanate compound (B), and the rubber latex (C) have a weight ratio of ((solid content of A) + (solid content of B)):(solid content of C) of 10: It is preferred that they are mixed at 90-60:40. More preferably, the weight ratio of ((solid content of A)+(solid content of B)):(solid content of C) is 20:80 to 50:50. Outside this range, the adhesive strength may be insufficient and the fatigue resistance may be deteriorated.

In the polyester fiber tire cord used in the present invention, a pre-coating agent is attached and heat-treated before the adhesive treatment agent (adhesion treatment agent containing at least lignin, a blocked isocyanate compound and rubber latex) is attached to the polyester fiber and heat-treated. It's okay to be there.

The precoating agent preferably contains at least an epoxy compound and a blocked isocyanate compound (solid content weight ratio: 10:0 to 10:30). Outside this range, the adhesive strength may decrease. The amount of the precoating agent attached to the polyester fiber is preferably such that the solid weight of the precoating agent is 0.1 to 3 parts by weight with respect to 100 parts by weight of the polyester fiber. Outside this range, the adhesive strength may be lowered.

When the precoat agent is applied, a dipping method similar to the method described above can be employed. That is, a polyester fiber twisted yarn cord or woven fabric is dipped in a precoating agent in a dip bath bath, followed by drying the moisture at a temperature of preferably 100 to 150°C, followed by heat treatment at 200 to 255°C. is preferred. The same methods as described above can be employed for controlling the amount of solid matter adhered and for the softening treatment.

Next, a carcass ply and a radial tire are manufactured using the polyester fiber tire cord manufactured as described above.

Conventionally known rubbers can be used for the radial tire of the present invention. At least one rubber selected from the group consisting of butadiene rubbers (SBR) can be used. It is also preferable to add known additives such as carbon black, silica, sulfur, zinc white, plasticizers, and the like.

The carcass ply is produced by a method known to those skilled in the art. For example, the rubber is rubberized into a sheet, calendered together with the dipped polyester fiber tire cord, and cut to an appropriate size to form a carcass ply. You get a ply. After that, it is molded into a green tire by a generally known method and press-vulcanized to obtain a radial tire.

The thus-obtained radial tire of the present invention is a radial tire in which a carcass ply is made of a polyester fiber tire cord made of a new adhesive treatment agent that is advantageous in reducing the environmental burden and does not contain resorcinol and formalin. It is an empty radial tire having excellent adhesiveness and high-speed durability equivalent to or higher than that of conventional RFL tire cords.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. In addition, in the examples etc. described specifically below, each measured value is obtained by the following method.

(1) Amount of Adhesive Treating Agent Adhered amount of adhesive agent was determined according to the dip pickup mass method of JIS L1017 (2002).

(2) Initial Adhesive Strength and Heat Resistant Adhesive Strength This shows the adhesive strength between the polyester fiber tire cord and the rubber. The initial adhesive force was measured by embedding polyester fiber tire cords in unvulcanized rubber, 150° C., 30 minutes, 50 kg/cm in accordance with the 3.1T test (A method) of Annex 1 of JIS L1017 (2002). After ^2- press vulcanization and cooling, the polyester fiber tire cord was pulled out from the rubber block at a speed of 300 mm/min. It was taken as the initial adhesive strength. In addition, the heat-resistant adhesive strength was measured by embedding a polyester fiber tire cord in unvulcanized rubber in accordance with JIS L1017 (2002) Annex 1, 3.1T test (A method), 170 ° C., 70 minutes, 50 kg. /cm ² After press vulcanization and cooling, the polyester fiber cord was pulled out from the rubber block at a speed of 300 mm/min, the load required for pulling was determined for each sample, and the arithmetic mean value of 10 samples. was taken as the heat resistant adhesive strength.

(3) Fatigue resistance in rubber (retention rate)
Evaluation was made in accordance with JIS L1017 (2002) Annex 1, 2.2.2 Disk fatigue strength (Goodrich method). Two polyester fiber tire cords are embedded in unvulcanized rubber and press vulcanized at 150° C. for 30 minutes at 50 kg/cm ² to prepare a rubber composite. This test piece was subjected to deformation with 6.3% compression and 12.6% elongation as one cycle at 2600 cycles/min in an atmosphere of 100 ° C. for 12 hours. The breaking strength was measured, and the retention rate of the breaking strength before and after the fatigue test was determined for each sample, and the arithmetic mean value of the eight samples was taken as the fatigue resistance in rubber (retention rate).

The composition of the unvulcanized rubber compound used for the measurement of initial adhesive strength, heat-resistant adhesive strength, and fatigue resistance in rubber is as follows.
Natural rubber (RSS#1): 70 (parts by weight)
SBR (#1502): 30 (parts by weight)
HAF carbon black: 40 (parts by weight)
Stearic acid: 2 (parts by weight)
Sulfur: 2 (parts by weight)
Zinc white: 5 (parts by weight)
2,2'-dithiobenzothiazole: 3 (parts by weight)
Naphthenic acid process oil: 3 (parts by weight).

(4) Maximum point strength and maximum point elongation of dry film of adhesive agent The adhesive agent was applied to a glass plate so that the thickness of the film after drying was 0.5 mm, and dried at room temperature for 72 hours. After that, it was separated from the glass plate, heat-treated in an oven at 120° C. for 15 minutes, and further heat-treated in an oven at 240° C. for 2 minutes. This was punched out with a No. 2 dumbbell type, and a tensile test was performed at a crosshead speed of 50 mm/min in an atmosphere of 25°C using a Tensilon RTM-100 type tester manufactured by Orientec Co., Ltd., and the strength and elongation were measured. The strength and elongation at the point where the strength reaches the maximum value are obtained for each sample, and the arithmetic average value of the strength in the number of samples 6 is the maximum point strength, and the arithmetic average value of the elongation in the number of samples 6 is the maximum point elongation. and

(5) Hardness of Gurley cord per unit of resin adhering to cord A polyester fiber tire cord was cut into a length of 1 m, a metal hook was tied to one end of the cord, and a weight of 300 g was tied to the other end. A measurement sample was obtained by suspending the cord in the air for 24 hours in an environment adjusted to a humidity of 40% and holding the cord vertically.

This was cut to 38.1 mm (1.5 inches) to obtain a test piece, and the Gurley cord hardness was measured with "Gurley's stiffness tester" manufactured by Yasuda Seiki Co., Ltd. The perspective view of "Gurley's stiffness tester" is shown in FIG.

(a) The chuck 1 is fixed at a set position according to the length of the sample, and the test piece 2 is attached. (a) The load setting hole is 25.4 mm (1 inch) (W1 in Fig. 1) and 50.8 mm (2 inches) (W2 in Fig. 1) from the shaft at the bottom of the rotating rod 3 (below the bearing). , and 101.6 mm (4 inches) (W3 in FIG. 1). In this case, the load and the position of the hole must be chosen so that the needle 5 points to 2-4 on the dial 4. (c) When the setting suitable for the test piece 2 is completed, press the drive button, move the drive shaft left and right, and read the value on the dial 4 pointed by the needle to the nearest 0.1 unit. (d) For one test piece 2, obtain the value of 10 test pieces, 20 times in total, and obtain the average value of one sample. The calculation method is as follows. The average value of each measured value was calculated by the following formula. Finally, the Gurley cord hardness (mg) was converted to (mN) and divided by the resin adhesion amount (%) to obtain the Gurley cord hardness (mN/%) per resin unit adhering to the cord.
・Gurley cord hardness (mg) = R x {(W1 x 1) + (W2 x 2) + (W3 x 4)}/5 x (L-12.7) ^{2 /} W x 19.8
however,
R: Average value of measured values W1: Load applied to a load position (hole) of 25.4 mm (unit: g)
W2: Load applied to 50.8 mm load position (hole) (unit: g)
W3: Load applied to the load position (hole) of 101.6 mm (unit: g)
L: sample length (mm)
W: Width of test piece (cord gauge) (mm).

(6) Gurley cord hardness change rate after heating (change rate after heating)
A polyester fiber tire cord was cut into a length of 1m, a metal hook was tied to one end, a 300g weight was tied to the other end, and the cord was hung vertically for 2 hours in an environment adjusted to a temperature of 160°C. to heat the polyester fiber tire cord. Thereafter, the Gurley cord hardness was obtained in the same manner as in (5) above. The value obtained by dividing the value of (6) by the value of (5) was taken as the rate of change in hardness of the Gurley cord after heating (%).

(7) Tire High-speed Durability A radial tire having a tire size of 165-SR13 was manufactured using the polyester fiber tire cord described above as a carcass ply in the same manner as in a normal tire manufacturing process. After completing the high-speed durability test specified in JIS D4230 using a drum tester, the speed was further increased by 10 km/h every 30 minutes, and the running distance until the tire was destroyed was measured. The evaluation was indicated by an index with 100 as the evaluation result of a tire using a polyester fiber tire cord using RFL as a carcass ply, which will be described later (conventional example). A larger index means better high-speed durability.

(Examples 1-4, Comparative Examples 1-3)
Glycerol polyglycidyl ether ("Denacol" EX313 (manufactured by Nagase Kasei Co., Ltd.)), blocked isocyanate compound (DM-6400 (manufactured by Meisei Chemicals)), rubber latex (pylatex, manufactured by Nippon A&L Co., Ltd.) solid content ratio of 20 : 40:40 and diluted with water to obtain a precoating agent (a) having a total solid content of 4.0% by weight.

In addition, lignin (A), blocked isocyanate compound (B), and rubber latex (C) were mixed with water so that the respective solid content ratios were as shown in Table 1, and the total solid content concentration was 15% by weight. An adhesive agent was obtained. The maximum point strength and maximum point elongation of the dry film of the obtained adhesive agent were measured.

Two polyester multifilament yarns of 1670 dtex (“Tetoron” 1670T-360-705M manufactured by Toray Industries, Inc.) were twisted at a base twist of 40 turns/10 cm and a top twist of 40 turns/10 cm to obtain a twisted yarn cord. .

The twisted yarn cord was immersed in the precoating agent using a computer processing machine (manufactured by Ritzler KK), dried at 120°C for 2 minutes, and then heat-treated at 245°C for 1 minute. Subsequently, after being immersed in an adhesive treatment agent containing the components (A), (B), and (C), it was dried at 120°C for 2 minutes, followed by heat treatment (hot treatment) at 240°C for 0.5 minutes. Furthermore, heat treatment (normalizing treatment) was performed at 240° C. for 0.5 minutes.

The adhesive solid content adhesion amount of the obtained polyester fiber tire cord was 1.1 parts by weight of the precoat agent per 100 parts by weight of the polyester fiber, and , 4.0 parts by weight per 100 parts by weight of the polyester fiber.

Each component of the adhesive agent shown in Table 1 is as follows.
(A)-1: lignin (manufactured by Tokyo Kasei Co., Ltd., sodium lignin sulfonate)
(B)-1: Blocked isocyanate (manufactured by Meisei Chemicals, DM-6400, dissociation temperature 120 to 160 ° C.)
(C)-1: Rubber latex (manufactured by Nippon A&L Co., Ltd., Pyratex).

(Example 5)
Glycerol polyglycidyl ether (“Denacol” EX313 (manufactured by Nagase Kasei Co., Ltd.)) and blocked isocyanate compound (DM-6400 (manufactured by Meisei Kagaku Co., Ltd.)) were mixed in the precoating agent so that the solid content ratio was 10:35. The treatment and evaluation were performed in the same manner as in Example 1, except that the precoating agent (a) obtained by diluting with water and having a total solid content of 7.0% by weight was used. The adhesive solid content adhesion amount of the obtained polyester fiber tire cord was 1.7 parts by weight of the precoat agent per 100 parts by weight of the polyester fiber, and , 3.5 parts by weight per 100 parts by weight of the polyester fiber.

(conventional example)
In Example 1, the treatment and evaluation were performed in the same procedure as in Example 1, except that the adhesive agent containing (A), (B), and (C) was changed to an RFL adhesive obtained by the following procedure. gone.
A resorcin/formalin molar ratio of 1/1.5 is mixed in the presence of caustic soda, adjusted to a solid concentration of 10%, and aged for 2 hours to give an initial condensate of resorcin and formalin. got Next, this initial condensate (RF) and rubber latex (pylatex, manufactured by Nippon A&L Co., Ltd.) were mixed at a ratio of RF/L=1/5 (solid content weight ratio) and aged for 24 hours. The mixture was diluted with water to give a 15% solids weight RFL adhesive. The adhesive solid content adhesion amount of the obtained polyester fiber tire cord was 1.1 parts by weight for the precoat agent per 100 parts by weight of the polyester fiber, and 4.0 parts by weight for the RFL adhesive per 100 parts by weight of the polyester fiber. was the department.

The Gurley cord hardness of the polyester fiber tire cord thus obtained and the rate of change in the Gurley cord hardness after heating were measured. In addition, after embedding vulcanization in unvulcanized rubber, initial adhesive strength, heat-resistant adhesive strength, and fatigue resistance in rubber were measured. Further, a radial tire was produced using this polyester fiber tire cord as a carcass ply, and a high-speed durability test was carried out. Table 1 shows the results.

As shown in Table 1, in the case of Examples 1 to 5 according to the present invention, the adhesive treatment agent does not contain resorcin and formalin, which is advantageous in reducing the environmental load compared to the conventional example RFL. It can be seen that the radial tire has good heat-resistant adhesiveness, good fatigue resistance in a high-temperature atmosphere, and high-speed durability performance equal to or higher than that of conventional RFL tire cords.

1 Chuck 2 Test piece 3 Rotating rod 4 Scale plate 5 Needle W1 Load setting hole (25.4 mm (1 inch) from the axis)
W2 load setting hole (50.8 mm (2 inches) from axis)
W3 load setting hole (101.6 mm (4 inches) from axis)

Claims (6)

A radial tire having a carcass ply made of a polyester fiber tire cord disposed inside the tread of the tire, wherein the polyester fiber tire cord contains at least lignin (A), a blocked isocyanate compound (B), and a rubber latex (C). A radial tire comprising a polyester fiber treated with an adhesive treatment agent contained therein. 2. The radial tire according to claim 1, wherein the dry film of said adhesive treatment agent has a maximum point strength of 0.2 MPa to 1.6 MPa and a maximum point elongation of 2% to 120%. The solid content weight ratio of lignin (A) and blocked isocyanate compound (B) in the adhesive agent is (solid content of A):(solid content of B) = 10: 1 to 10: 30. 3. A radial tire according to claim 1 or 2. The solid content weight ratio of lignin (A), blocked isocyanate compound (B) and rubber latex (C) in the adhesive agent is ((A solid content) + (B solid content)): (C solid content)=10:90 to 60:40. The polyester fiber tire cord is treated with a pre-coating agent before being treated with the adhesive treatment agent, and the pre-coating agent comprises an epoxy compound and a blocked isocyanate compound (solid content weight ratio 10: 0 to 10: 30), the radial tire according to any one of claims 1 to 4. The polyester fiber tire cord has a Gurley cord hardness per resin unit attached to the cord of 30 to 80 mN/% or less, and a Gurley cord hardness change rate after heating of 90% to 130%. Item 6. A radial tire according to any one of Items 1 to 5.

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