Polyester fiber cord for rubber reinforcement

Abstract

To provide a polyester fiber cord for rubber reinforcement that is composed of a new adhesive treatment agent that does not contain a resorcinol-formaldehyde resin and uses an alternative raw material advantageous for environmental load reduction, which exhibits initial adhesive force equivalent to or higher than that of a conventional RFL adhesive, remarkably improves heat-resistant adhesive force when being exposed to high temperature in rubber for a long time in a rubber vulcanization step and in use of a product, improves fatigue resistance, and is suitable as a reinforcement material of a tire, and to provide a polyester fiber cord for rubber reinforcement which can suppress accumulation of resin scum in a dip step, and has good productivity.SOLUTION: A polyester fiber cord for rubber reinforcement in which a polyester fiber is coated with a first treatment agent containing at least four kinds of (A) a compound containing an oxazoline group, (B) a blocked isocyanate compound, (C) a rubber latex and (D) an epoxy compound, and is coated with a second treatment agent containing at least three kinds of (a) a lignin derivative, (b) a blocked isocyanate compound and (c) a rubber latex as its outer layer, wherein the first treatment agent contains 10-50 wt.% of (A) the compound containing the oxazoline group, 3 to 13 wt.% of (B) the blocked isocyanate compound, 20 to 60 wt.% of (C) the rubber latex and 20 to 60 wt.% of (D) the epoxy compound, based on 100 wt.% of the total solid content, (a) the lignin derivative contained in the second treatment agent has a number average molecular weight of 10,000 to 60,000 and a weight average molecular weight of 80,000 to 130,000, and a resorcinol-formaldehyde resin is not contained.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a polyester fiber cord for rubber reinforcement, which is made of a novel adhesive treatment agent that is advantageous in reducing environmental impact and has significantly improved heat-resistant adhesive strength. [Background technology]

[0002] Synthetic fibers such as nylon fibers, polyester fibers, and aromatic polyamide fibers are widely used as reinforcing materials in rubber products such as tires, hoses, and belts. RFL (resorcinol-formaldehyde-latex) adhesives, containing resorcinol-formaldehyde resin (consisting of resorcinol and formalin) and rubber latex, have traditionally been widely used to bond these synthetic fibers to rubber compositions. However, both resorcinol and formalin are highly toxic substances with a high environmental impact and health risks. Therefore, in recent years, there has been a demand to reduce their release into the atmosphere during use and to decrease their usage.

[0003] Furthermore, as mentioned above, synthetic fibers are widely used as reinforcing materials in rubber products, and polyester fibers, in particular, are favored for use in tires due to their excellent strength, modulus of elasticity, and thermal dimensional stability. When polyester fibers are used embedded in rubber products as reinforcing materials, they undergo thermal degradation in high-temperature environments. This chemical thermal degradation is affected by the rubber itself and the various additives blended into the rubber. Polyester fibers subjected to high-temperature treatment in rubber containing amine-based antioxidants undergo amine decomposition and hydrolysis mainly due to these amine-based compounds, low molecular weight compounds produced by the oxidative degradation of the rubber itself, water molecules, and moisture contained in the rubber. Polyester fibers that have undergone such amine decomposition and hydrolysis have a significant decrease in their initial properties such as adhesion and strength, making them unsuitable for use.

[0004] When polyester fibers undergo amine decomposition or hydrolysis, they experience a decrease in strength due to molecular chain severance and a reduction in adhesion between the rubber and the fiber layer. However, despite these drawbacks, polyester fibers, when used as rubber reinforcing fibers, offer high strength, high modulus of elasticity, excellent thermal dimensional stability, and improvements in fatigue resistance and adhesion. Combined with advancements in tire manufacturing technology, they are now used as the carcass material for most passenger car radial tires. Nevertheless, due to the aforementioned inherent drawbacks, their use is currently limited to passenger car carcass materials with relatively small tire sizes, where heat generated during high-speed tire operation is less likely to accumulate and chemical degradation is less likely. They are only used to a very limited extent in large tires such as those for trucks and buses. Generally, polyester fiber cords are not used in truck and bus tires, aircraft tires, run-flat tires, or the cap ply material of radial tires.

[0005] Cap ply materials and run-flat tire reinforcements generate significantly more heat and reach higher temperatures than carcass materials. Conventional polyester fiber cords are unsuitable for these applications, and nylon 66 and rayon fibers, which have superior heat-resistant adhesive properties, are generally used instead. From the standpoint of cost, supply stability, and elastic modulus, polyester fiber is preferable as a fiber material for tire reinforcements, but a significant improvement in the heat-resistant adhesive properties of polyester fiber cords is necessary for their application in these uses.

[0006] Furthermore, in order to give the fibers adhesive properties to rubber, it is essential to treat the fiber surface with an adhesive such as the RFL mentioned above. However, in the adhesive treatment process, resin residue caused by the composition of the applied adhesive adheres to the treatment equipment, such as the rolls of the dipping machine, leading to a decrease in productivity as continuous production becomes difficult due to the need for cleaning. In addition, there is a problem that the resin residue accumulated on the rolls is transferred to the surface of the dip cord, leading to quality defects.

[0007] Examples of technologies addressing the above problem include the prior art described in Patent Documents 1 to 6.

[0008] Patent Document 1 discloses a method for treating polyester fibers with an aqueous adhesive composition containing a thermosetting resin having a specific functional group and an unsaturated elastomer latex.

[0009] Patent Document 2 discloses a method for treating polyester fibers with an organic fiber adhesive comprising at least one component selected from the group consisting of polyphenols, chlorophenol resins, and lignin resins, and at least one component selected from water-soluble polymers other than the aforementioned components or water-dispersible polymers other than the aforementioned components.

[0010] Patent Document 3 discloses a method for treating polyester fibers with an aqueous adhesive composition comprising a specific blocked isocyanate oligomer with three or more functions, a latex, a polyacrylate or lignin compound, and an additive.

[0011] Patent Document 4 discloses a method in which polyester fibers are treated with a treatment solution containing a carrier and an aqueous solution of blocked isocyanate, and then treated with RFL containing an epoxy compound.

[0012] Patent Document 5 discloses a method in which polyester fibers are treated with a treatment solution containing a thermoplastic polymer, a heat-reactive aqueous urethane, and an epoxy compound, and then treated with RFL.

[0013] Patent document 6 discloses a method of treating polyester fibers with a treatment agent containing three types of compounds: a compound containing an oxazoline group, an epoxy compound, and a rubber latex, and then treating them with RFL. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] Special Publication No. 2019-518087 [Patent Document 2] WO2018 / 003572 issue [Patent Document 3] U.S. Publication No. 2020 / 0024416 [Patent Document 4] Japanese Patent Publication No. 2006-2327 [Patent Document 5] Japanese Patent Publication No. 2001-19927 [Patent Document 6] Japanese Patent Publication No. 2013-10909 [Overview of the project] [Problems that the invention aims to solve]

[0015] However, while Patent Documents 1-3 do not use resorcinol-formaldehyde resin and exhibit adhesive strength comparable to conventional RFL adhesives, they do not sufficiently contribute to further improvement in heat-resistant adhesive strength, improved fatigue resistance in rubber, or improved tire performance. Patent Documents 4-6 show improvement in heat-resistant adhesive strength, but all of them use conventional RFL adhesives, which has the problem of a large environmental impact. In addition, all of Patent Documents 1-6 still have the production problem of resin residue accumulation in the dipping process.

[0016] This invention was developed as a result of investigating the problem of the prior art described above.

[0017] The object of the present invention is a polyester fiber cord for rubber reinforcement made of a novel adhesive treatment agent that does not contain resorcinol-formaldehyde resin and uses alternative raw materials advantageous for reducing environmental impact, exhibiting initial adhesive strength equal to or greater than that of conventional RFL adhesives, and significantly improving heat-resistant adhesive strength when exposed to high temperatures in rubber for long periods during the rubber vulcanization process and product use, thereby improving fatigue resistance, and providing a polyester fiber cord for rubber reinforcement that is suitable as a tire reinforcement material. Furthermore, the present invention provides a polyester fiber cord for rubber reinforcement that can suppress the accumulation of resin residue in the dipping process and has good productivity. [Means for solving the problem]

[0018] To solve these problems, the present invention employs the following means.

[0019] That is, (1) A polyester fiber cord for rubber reinforcement, wherein the polyester fiber is coated with a first treatment agent containing at least four kinds of compounds: (A) a compound containing an oxazoline group, (B) a blocked isocyanate compound, (C) a rubber latex, and (D) an epoxy compound, and further coated with a second treatment agent containing at least three kinds of compounds: (a) a lignin derivative, (b) a blocked isocyanate compound, and (c) a rubber latex as an outer layer thereof. The first treatment agent contains, based on 100% by weight of the total solid content, 10-50% by weight of (A) a compound containing an oxazoline group, 3-13% by weight of (B) a blocked isocyanate compound, 20-60% by weight of (C) a rubber latex, and 20-60% by weight of (D) an epoxy compound. And the number average molecular weight of the (a) lignin derivative contained in the second treatment agent is 10,000-60,000 and the weight average molecular weight is 80,000-130,000, and it does not contain a resorcinol-formaldehyde resin.

[0020] (2) The polyester fiber cord for rubber reinforcement according to (1) above, wherein the (B) blocked isocyanate compound contained in the first treatment agent is a bifunctional MDI-based blocked isocyanate.

[0021] (3) The polyester fiber cord for rubber reinforcement according to (1) above, wherein the (b) blocked isocyanate compound contained in the second treatment agent is a bifunctional MDI-based blocked isocyanate.

[0022] (4) The polyester fiber cord for rubber reinforcement according to (1) above, wherein the (B) blocked isocyanate compound contained in the first treatment agent is a bifunctional MDI-based blocked isocyanate, and the (b) blocked isocyanate compound contained in the second treatment agent is a bifunctional MDI-based blocked isocyanate.

[0023] (5) The rubber-reinforced polyester fiber cord according to (1) above, characterized in that the (C) rubber latex contained in the first treatment agent includes VP latex having a Mooney viscosity (ML1+4 100℃) of 20 to 100 and a Tg of -70℃ to -30℃.

[0024] (6) The rubber-reinforced polyester fiber cord according to (1) above, characterized in that the (c) rubber latex contained in the second treatment agent includes VP latex having a Mooney viscosity (ML1+4 100℃) of 20 to 100 and a Tg of -70℃ to -30℃.

[0025] (7) The rubber-reinforced polyester fiber cord according to (1) above, characterized in that the (B) blocked isocyanate compound contained in the first treatment agent is a bifunctional MDI-based blocked isocyanate, the (b) blocked isocyanate compound contained in the second treatment agent is a bifunctional MDI-based blocked isocyanate, the (C) rubber latex contained in the first treatment agent contains VP latex with a Mooney viscosity (ML1+4 100℃) of 20 to 100 and a Tg of -70℃ to -30℃, and the (c) rubber latex contained in the second treatment agent contains VP latex with a Mooney viscosity (ML1+4 100℃) of 20 to 100 and a Tg of -70℃ to -30℃.

[0026] (8) The polyester fiber cord for rubber reinforcement according to any one of (1) to (7) above, characterized in that the (A) oxazoline group-containing compound contained in the first treatment agent has a Tg of 0 to 80°C and an oxazoline group content of 1.0 to 5.0 mmol / g, solid.

[0027] (9) The tackiness of the cord surface is 2.0 to 10.0 N / cm 2 A polyester fiber cord for rubber reinforcement according to any of (1) to (7) above, characterized in that it is the same as described above.

[0028] (10) The polyester fiber cord for rubber reinforcement according to any one of (1) to (7) above, characterized in that when the total solid content of the second treatment agent is 100% by weight by dry weight, the content of (a) lignin derivative is 5 to 50% by weight, and the weight ratio of solid content of (a) lignin derivative to (b) blocked isocyanate compound is (solid content of a):(solid content of b)=10:1 to 10:20.

[0029] (11) A polyester fiber cord for rubber reinforcement according to any of (1) to (7) above, characterized in that the amount of resin adhering to the film by the first treatment agent is 1 to 4% by weight, the amount of resin adhering to the film by the second treatment agent is 1 to 4% by weight, and the total amount of resin adhering to the film by the first treatment agent and the film by the second treatment agent is 2 to 6% by weight.

[0030] (12) A tire made using a rubber-reinforced polyester fiber cord as described in any of (1) to (11) above. [Effects of the Invention]

[0031] The present invention relates to a polyester fiber cord for rubber reinforcement, comprising a novel adhesive treatment agent that does not contain resorcinol-formaldehyde resin and uses alternative raw materials advantageous for reducing environmental impact. This cord exhibits initial adhesive strength equal to or greater than that of conventional RFL adhesives, and significantly improves heat-resistant adhesive strength when exposed to high temperatures in rubber for extended periods during the rubber vulcanization process and product use, thereby improving fatigue resistance and making it suitable as a reinforcing material for tires. Furthermore, it is possible to provide a polyester fiber cord for rubber reinforcement that suppresses resin residue accumulation in the dipping process and offers good productivity. [Modes for carrying out the invention]

[0032] The present invention will be described in detail below.

[0033] The rubber-reinforced polyester fiber cord of the present invention is characterized in that the polyester fiber is coated with a first treatment agent comprising at least four types: (A) a compound containing an oxazoline group, (B) a blocked isocyanate compound, (C) rubber latex, and (D) an epoxy compound, and further coated as an outer layer with a second treatment agent comprising at least three types: (a) a lignin derivative, (b) a blocked isocyanate compound, and (c) rubber latex.

[0034] The polyester fibers used in this invention are preferably those obtained by melt-spinning and drawing a polyester having terephthalic acid as the main difunctional carboxylic acid and ethylene glycol as the main glycol component. However, fibers made of polyester in which terephthalic acid is partially or completely replaced with 2,6-naphthalenedicarboxylic acid, 4,4-dicarboxyphenoxyethane, isocyanate groups, etc., or in which ethylene glycol is partially or completely replaced with diethylene glycol, propylene glycol, butanediol, etc., can also be used.

[0035] Furthermore, the above-mentioned polyester may, in small amounts, be a copolymer of trifunctional compounds such as trimesic acid, trimellitic acid, boric acid, phosphoric acid, glycerin, and trimethylolpropane.

[0036] The polyester fiber cord for rubber reinforcement of the present invention has excellent mechanical properties such as high strength, high toughness, high modulus of elasticity, low shrinkage, and high fatigue resistance, and suppresses adhesive degradation and strength degradation even when exposed to high temperatures in rubber for a long time. Therefore, the polyester fiber used in the present invention preferably has the following properties. (1) Intrinsic viscosity (IV) = 0.7 to 1.2, more preferably 0.8 to 1.1 (2) Carboxyl terminal group (COOH) = 10-30 eq / t, more preferably 12-25 eq / t (3) Diethylene glycol (DEG) content = 0.5 to 1.5% by weight, more preferably 0.5 to 1.2% by weight (4) Strength (T) = 6.0 to 10.0 cN / dtex, more preferably 7.0 to 9.0 cN / dtex (5) Elongation (E) = 8-20%, more preferably 10-16% (6) Intermediate elongation (ME) = 4.0 to 6.5%, more preferably 4.5 to 6.0% (7) Dry heat shrinkage rate (ΔS150℃) = 2.0 to 12.0%, more preferably 3.0 to 10.0%.

[0037] For the polyester fibers used in the rubber-reinforced polyester fiber cord of the present invention to have particularly good chemical durability, it is advantageous that they have high viscosity, few carboxyl end groups, and a low amount of diethylene glycol.

[0038] The polyester fibers used in the present invention may be modified using terminal carboxyl group chelating agents such as carbodiimide compounds, epoxy compounds, isocyanate compounds, and oxazoline compounds to reduce the number of carboxyl end groups.

[0039] Furthermore, the polyester fibers of the present invention may have polyepoxide compounds applied to them in advance during the yarn manufacturing process. Examples of polyepoxide compounds that can be used in the present invention include compounds that contain at least two epoxy groups in one molecule, in an amount of 0.1 g equivalent or more per 100 g of the compound. Specifically, examples include reaction products of polyhydric alcohols such as pentaerythritol, ethylene glycol, polyethylene glycol, propylene glycol, glycerol, and sorbitol with halogen-containing epoxides such as epichlorohydrin, and polyepoxide compounds obtained by oxidizing unsaturated compounds with peroxide or hydrogen peroxide, namely aromatic polyepoxides such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexene carbochylate, 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, phenol glyoxal type, trisoxyphenylmethane type, trisphenol PA type, and bisphenol type polyepoxides. Particularly preferred are sorbitol glycidyl ether type and cresol novolac type polyepoxides.

[0040] These compounds are typically used as emulsifiers. To make an emulsifier or solution, the compound is used either as is or, if necessary, dissolved in a small amount of solvent, and then emulsified or dissolved using a known emulsifier, such as sodium alkylbenzenesulfonate, sodium dioctyl sulfosuccinate, or nonylphenol ethylene oxide adduct.

[0041] The polyepoxide compound is applied together with the spinning oil during the polyester fiber spinning process. 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 applied is less than 0.1% by weight, the effect of the polyepoxide compound may not be fully exerted, and satisfactory adhesion between the polyester fiber and the rubber may not be obtained. On the other hand, if the amount of the polyepoxide compound applied exceeds 5% by weight, the fiber becomes very hard, making it difficult to apply during the spinning process, and as a result the penetration of treatment agents applied in subsequent processes decreases, the adhesive performance is reduced, which is undesirable.

[0042] The polyester fibers used in this invention are not subject to restrictions on fineness, filament count, cross-sectional shape, etc., but typically, a total fineness of 200 to 5000 dtex, 30 to 1000 filaments, and a circular cross-section yarn are used, with a total fineness of 250 to 3000 dtex, 50 to 500 filaments, and a circular cross-section yarn being more preferable. If the total fineness is less than 200 dtex, the strength of the cord may be insufficient, and if it exceeds 5000 dtex, the cord may become thick and its handling may decrease. Also, if it is less than 30 filaments, the cord may become stiff and its handling may worsen, and if it exceeds 500 filaments, the amount of fuzz may increase and the quality may decrease.

[0043] The polyester fiber cord for rubber reinforcement of the present invention is obtained by twisting the above-mentioned polyester fibers to form a twisted cord, and then applying an adhesive treatment to the twisted cord either as is or after weaving it into a raw mat. The raw cord used for ordinary carcass tire cords is obtained by first twisting it in the S or Z direction, then combining two or three under-twisted cords and applying usually the same number of top twists in the opposite direction to the under-twist to form a multi-twisted cord. Dip cord is obtained by applying an adhesive treatment to this twisted cord. On the other hand, twisted cord is used as the warp, cotton yarn is used as the weft, or synthetic fiber is covered with cotton yarn as the weft, and after weaving it into a raw mat, dip mat is obtained by applying an adhesive treatment to the raw mat.

[0044] The polyester fiber cord for rubber reinforcement in this invention refers to both the dip cord and the dip roll described above.

[0045] The rubber-reinforced polyester fiber cord of the present invention is characterized in that the polyester fiber is coated with a first treatment agent comprising at least four types: (A) a compound containing an oxazoline group, (B) a blocked isocyanate compound, (C) rubber latex, and (D) an epoxy compound, and further coated as an outer layer with a second treatment agent comprising at least three types: (a) a lignin derivative, (b) a blocked isocyanate compound, and (c) rubber latex.

[0046] The compound containing an oxazoline group (A) used in the first treatment agent of the present invention refers to a compound that contains an oxazoline group (preferably a 2-oxazoline group) at the end or side chain of a substance whose main skeleton is a general organic compound or organic polymer or oligomer. The oxazoline group can be present in one or more quantities in the skeleton, but it is more preferable to have a large number of oxazoline groups, which are reactive functional groups, in order to improve adhesive performance. As the skeleton of the main chain of the oxazoline group-containing compound, hydrocarbon chains, ethylene glycol chains, bisphenols such as bisphenol A, and initial polymers such as phenol resins, novolac resins, and resol resins can be used, and substances containing aromatic rings or heterocycles in their molecular skeletons can also be used. Furthermore, substances containing an oxazoline group at the end or side chain of the main component monomer and / or polymers or oligomers composed thereof are also useful. Examples of these monomers include styrene, styrene derivatives, acrylonitrile, methacrylic acid esters, methacrylic acid, ethylene, butadiene, and acrylamide, which can be used as individual polymers and / or oligomers, as well as copolymers. They can also be used as mixtures of these.

[0047] The oxazoline group-containing compound can be used in liquid, molten, solid, or dissolved in water or an organic solvent capable of dissolving them, or as a suspension dispersed in water or the like (emulsion particles, latex particles, etc.). For example, such a compound may be used as is, or dissolved in a small amount of solvent as needed, and then emulsified or dissolved using a known emulsifier, such as sodium alkylbenzenesulfonate, sodium dioctyl sulfosuccinate, or nonylphenol ethylene oxide adduct.

[0048] The oxazoline group-containing compound preferably has a Tg (glass transition temperature) of 0 to 80°C and an oxazoline group content of 1.0 to 5.0 mmol / g, solid, and more preferably has a Tg (glass transition temperature) of 10 to 70°C and an oxazoline group content of 1.2 to 3.0 mmol / g, solid. If the content falls outside this range, the heat-resistant adhesive strength may decrease.

[0049] The (B) blocked isocyanate compound used in the first treatment agent in the present invention is a compound that can release a blocking agent upon heating to produce an active isocyanate compound. Examples of blocked isocyanate compounds include reaction products of polyisocyanate compounds having a skeleton such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and triphenylmethane triisocyanate, and blocking agents such as 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.

[0050] Among these blocked isocyanate compounds, bifunctional MDI-based blocked isocyanates in which diphenylmethane diisocyanate is blocked with a blocking agent are particularly preferred for obtaining good adhesion and fatigue resistance. More preferably, bifunctional MDI-based blocked isocyanates blocked with oximes are preferred. Polymeric MDI having three or more isocyanate groups may have reduced fatigue resistance and is therefore undesirable.

[0051] Examples of rubber latex (C) that can be used in the first treatment agent of the present invention include natural rubber latex, butadiene rubber latex, styrene-butadiene rubber latex, vinylpyridine-styrene-butadiene rubber latex, nitrile rubber latex, hydrogenated nitrile rubber latex, chloroprene rubber latex, chlorosulfonated rubber latex, ethylene-propylene-diene rubber latex, etc., which can be used alone or in combination. In particular, it is preferable from the viewpoint of adhesive strength and fatigue resistance that the latex contains VP latex with a Mooney viscosity (ML1+4 100℃) of 20 to 100 and a Tg of -70℃ to -30℃, and more preferably VP latex with a Mooney viscosity (ML1+4 100℃) of 30 to 80 and a Tg of -60℃ to -40℃.

[0052] The epoxy compound (D) that can be used in the first treatment agent of the present invention has two or more epoxy groups in one molecule.

[0053] Compounds having two or more epoxy groups in their molecule include, for example, glycidyl ether-type epoxy resins obtained from compounds having hydroxyl groups in their molecule, glycidylamine-type epoxy resins obtained from compounds having amino groups in their molecule, glycidyl ester-type epoxy resins obtained from compounds having carboxyl groups in their molecule, cyclic aliphatic epoxy resins obtained from compounds having unsaturated bonds in their molecule, heterocyclic epoxy resins such as triglycidyl isocyanates, or epoxy resins in which two or more types selected from these are mixed in the molecule.

[0054] Specific examples of glycidyl ether type epoxy resins include bisphenol A type epoxy resins obtained by the reaction of bisphenol A with halogen-containing epoxides such as epichlorohydrin, bisphenol F type epoxy resins obtained by the reaction of bisphenol F with the halogen-containing epoxides, biphenyl type epoxy resins obtained by the reaction of biphenyl with the halogen-containing epoxides, resorcinol type epoxy resins obtained by the reaction of resorcinol with the halogen-containing epoxides, bisphenol S type epoxy resins obtained by the reaction of bisphenol S with the halogen-containing epoxides, polyethylene glycol type epoxy resins and polypropylene glycol type epoxy resins which are reaction products of polyhydric alcohols with the halogen-containing epoxides, epoxy resins obtained by oxidizing the unsaturated bond portion of bis-(3,4-epoxy-6-methyl-dicyclohexylmethyl) adipate, 3,4-epoxycyclohexene epoxide, etc., as well as naphthalene type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and halogen or alkyl substituted derivatives thereof.

[0055] The rubber-reinforced polyester fiber cord of the present invention is coated with a first treatment agent comprising (A) a compound containing an oxazoline group, (B) a blocked isocyanate compound, (C) rubber latex, and (D) an epoxy compound. The first treatment agent must contain 10 to 50% by weight of (A) the compound containing an oxazoline group, 3 to 13% by weight of (B) the blocked isocyanate compound, 20 to 60% by weight of (C) the rubber latex, and 20 to 60% by weight of (D) the epoxy compound, based on the total solids content (dry weight) of the first treatment agent. Preferably, the first treatment agent... The first treatment agent contains, more preferably, 15-40% by weight of (A) a compound containing an oxazoline group, 5-11% by weight of (B) a blocked isocyanate compound, 30-50% by weight of (C) rubber latex, and 30-50% by weight of (D) an epoxy compound, relative to the total solid content of the treatment agent. If the proportion of (A) a compound containing an oxazoline group falls outside this range, the heat-resistant adhesive strength and fatigue resistance may decrease. If the proportion of (B) a blocked isocyanate compound falls outside this range, the initial adhesive strength may decrease. If the proportion of (C) rubber latex falls outside this range, the initial adhesive strength and fatigue resistance may decrease. (D) If the proportion of epoxy compounds falls outside this range, the initial adhesive strength may decrease and fatigue resistance may worsen.

[0056] Furthermore, in addition to (A), (B), (C), and (D) above, surfactants, defoaming agents, vulcanization modifiers, antioxidants, and pH adjusters may be added to the first treatment agent used in the present invention as needed, within the limits that do not hinder the objectives and effects of the present invention.

[0057] The (a) lignin derivative used in the second treatment agent of the present invention is a state in which lignin present in trees, which are biomass, has been chemically treated. Examples of such derivatives include kraft lignin obtained from kraft pulp wastewater and ligninsulfonic acid obtained from sulfite pulp wastewater in the papermaking process that uses wood as a raw material. Lignosulfonic acid is obtained by introducing a sulfonate 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 alone or in combination, but sodium ligninsulfonate is most preferably used from the viewpoint of adhesive strength.

[0058] The lignin derivative (a) used in this invention must have a number average molecular weight of 10,000 to 60,000 and a weight average molecular weight of 80,000 to 130,000, preferably a number average molecular weight of 20,000 to 50,000 and a weight average molecular weight of 90,000 to 120,000. If the number average molecular weight and weight average molecular weight exceed the upper limit of this range, fatigue resistance may be insufficient, the storage stability of the adhesive treatment agent may deteriorate, and resin residue may accumulate in the dipping process, making continuous production difficult. If the number average molecular weight and weight average molecular weight are below the lower limit of this range, the initial adhesion strength to rubber and fatigue resistance will decrease, which is undesirable. Furthermore, the weight average molecular weight (Mw) / number average molecular weight (Mn) is preferably 2.5 to 5.0, and more preferably 2.8 to 4.7. If it falls outside this range, adhesion strength and fatigue resistance may be insufficient. In this invention, the number-average molecular weight and weight-average molecular weight refer to the values ​​measured by the methods described in the Examples section.

[0059] The (b) blocked isocyanate compound used in the second treatment agent in the present invention is the same as the (B) blocked isocyanate compound used in the first treatment agent, and the preferably used blocked isocyanate compound is also the same.

[0060] The (c) rubber latex that can be used in the second treatment agent of the present invention is the same as the (C) rubber latex used in the first treatment agent, and the preferred Mooney viscosity is also the same. Examples include natural rubber latex, butadiene rubber latex, styrene-butadiene rubber latex, vinylpyridine-styrene-butadiene rubber latex, nitrile rubber latex, hydrogenated nitrile rubber latex, chloroprene rubber latex, chlorosulfonated rubber latex, ethylene-propylene-diene rubber latex, etc., and these can be used alone or in combination. In particular, it is preferable from the viewpoint of adhesive strength and fatigue resistance to include VP latex with a Mooney viscosity (ML1+4 100℃) of 20 to 100 and a Tg of -70℃ to -30℃, and more preferably VP latex with a Mooney viscosity (ML1+4 100℃) of 30 to 80 and a Tg of -60℃ to -40℃.

[0061] In the second treatment agent of the present invention, when the total solid content contained in the adhesive treatment agent is taken as 100% by weight, the content of (a) lignin derivative is preferably 5 to 50% by weight, more preferably 7 to 45% by weight, and even more preferably 10 to 40% by weight. If it is less than 5% by weight or more than 50% by weight, the adhesive strength and fatigue resistance may be insufficient.

[0062] Furthermore, the solid content weight ratio of (a) lignin derivative to (b) blocked isocyanate compound is preferably (solid content of a):(solid content of b) = 10:1 to 10:20, and more preferably 10:5 to 10:20. If the amount of (b) is less than this weight ratio, the adhesive strength may be insufficient, and if the amount of (b) is more than this weight ratio, the cord may become hard, and the fatigue resistance in rubber may deteriorate. Using the cord for reinforcing rubber products such as tires, belts, and hoses may worsen the durability of the product, which is undesirable.

[0063] Furthermore, the solid content weight ratio of (a) lignin derivative, (B) blocked isocyanate compound, and (c) rubber latex is preferably ((solid content of a) + (solid content of b)):(solid content of c) = 10:90 to 60:40, and more preferably 20:80 to 50:50. If the ratio deviates from this range, the adhesive strength may be insufficient or the fatigue resistance may deteriorate.

[0064] Furthermore, in addition to (a), (b), and (c) above, surfactants, defoaming agents, vulcanization modifiers, antioxidants, pH adjusters, carbon black, colorants, etc. may be added to the second treatment agent used in the present invention as needed, within the limits that do not hinder the objectives and effects of the present invention.

[0065] The first treatment agent of the present invention is a solid component dissolved or dispersed in water, and the total solid component concentration is preferably 1 to 15% by weight, more preferably 2 to 13% by weight, and even more preferably 3 to 10% by weight. If the concentration is outside this range, it may lead to a decrease in initial adhesive strength and heat-resistant adhesive strength.

[0066] The second treatment agent of the present invention is a solid component dissolved or dispersed in water, and the total solid component concentration is preferably 5 to 25% by weight, more preferably 10 to 20% by weight, and even more preferably 12 to 18% by weight. If the concentration falls outside this range, it may lead to a decrease in initial adhesive strength.

[0067] The amount of resin adhering to the film by the first treatment agent of the present invention is 1 to 4% by weight per 100% by weight of polyester fiber, and the amount of resin adhering to the film by the second treatment agent is 1 to 4% by weight per 100% by weight of polyester fiber, and the total amount of resin adhering to the film by the first and second treatment agents is 2 to 6% by weight per 100% by weight of polyester fiber. Preferably, the amount of resin adhering to the film by the first treatment agent is 1.5 to 3.0% by weight per 100% by weight of polyester fiber, the amount of resin adhering to the film by the second treatment agent is 1.5 to 3.0% by weight per 100% by weight of polyester fiber, and the total amount of resin adhering to the film by the first and second treatment agents is 2 to 5% by weight per 100% by weight of polyester fiber. If the amounts are outside this range, a decrease in adhesive strength may occur.

[0068] Furthermore, the surface tackiness of the rubber-reinforced polyester fiber cord of the present invention is 2.0 to 10.0 N / cm². 2 Preferably, and more preferably, 3.0 to 9.0 N / cm² 2 It is preferable that this be the case. The tackiness of the cord surface can be measured by the method described later. If the tackiness of the cord surface is less than 2.0, the adhesion to the rubber may decrease, and if it exceeds 10.0, resin residue may accumulate during the dipping process, which may worsen the cord's passability through the process. The tackiness of the cord can be adjusted to a desirable range by optimizing the selection and content of the latex in the second bath treatment agent, as well as the mixing ratio with other compounding agents.

[0069] Next, the method for manufacturing the rubber-reinforced polyester fiber cord of the present invention will be described.

[0070] An example of a method for producing a rubber-reinforced polyester fiber cord according to the present invention is to attach polyester fibers to a first treatment agent containing at least four types: (A) a compound containing an oxazoline group, (B) a blocked isocyanate compound, (C) rubber latex, and (D) an epoxy compound, and then heat-treat the cord. Subsequently, the obtained cord is attached to a second treatment agent containing at least three types: (a) a lignin derivative, (b) a blocked isocyanate compound, and (c) rubber latex, and then heat-treat the cord. The polyester fibers may be in the form of twisted cord or raw bamboo roll. The heat treatment after attachment of the first and second treatment agents is preferably carried out by drying the moisture at a temperature of 100 to 150°C, followed by heat treatment at 200 to 255°C.

[0071] Methods for applying the first or second treatment agent to polyester fibers include, for example, dipping. Dip treatment involves running a twisted cord or raw yarn through a dipping tank filled with an adhesive treatment agent and equipped with rollers, thereby applying the treatment agent to the twisted cord or raw yarn. Heat treatment involves running a twisted cord or raw yarn through an oven equipped with rollers and capable of being set to a predetermined temperature, thereby heating the twisted cord or raw yarn. Such dipping and heat treatment machines are commercially available, for example, from Ritzler. In addition to dipping, other methods for applying the treatment agent to polyester fibers include, for example, application by spraying the adhesive treatment agent from a nozzle.

[0072] Furthermore, to control the amount of solid material adhering to the polyester fibers, methods such as squeezing with a pressure roller, scraping with a scraper, blowing with air, and suction may be used.

[0073] Furthermore, during the mechanical softening process following the drying and heat treatment described above, a softening treatment can be applied to obtain the desired cord stiffness by sliding the polyester fiber cord against the edge.

[0074] The present invention provides a rubber-reinforced polyester fiber cord that is obtained in this manner and is made of a novel adhesive treatment agent that does not contain resorcinol-formaldehyde resin and uses alternative raw materials advantageous for reducing environmental impact. This rubber-reinforced polyester fiber cord exhibits initial adhesive strength equivalent to or greater than conventional RFL, and significantly improves heat-resistant adhesive strength when exposed to high temperatures in rubber for long periods during the rubber vulcanization process and product use, thereby improving fatigue resistance and making it suitable as a reinforcing material for tires. Furthermore, it is possible to provide a rubber-reinforced polyester fiber cord that can suppress the accumulation of resin residue in the dipping process and has good productivity. [Examples]

[0075] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. In the examples described below, each measurement value was obtained by the following method.

[0076] (1) Amount of adhesive treatment agent applied The amount of adhesive applied was determined according to the mass method for dip pickups as specified in JIS L1017 (2002).

[0077] (2) Initial bonding strength and heat-resistant bonding strength This shows the adhesive strength between polyester fiber cord and rubber. The initial adhesive strength was measured in accordance with JIS L1017 (2002) Annex 1, 3.1T test (Method A), by embedding the polyester fiber cord in unvulcanized rubber and measuring at 150°C for 30 minutes at 50 kg / cm². 2 After press vulcanization and subsequent cooling, the polyester fiber cord was pulled out of the rubber block at a speed of 300 mm / min. The load required for this pulling was determined for each sample, and the arithmetic mean of 10 samples was used as the initial adhesive strength. Furthermore, the heat-resistant adhesive strength was measured in accordance with JIS L1017 (2002) Annex 1, 3.1T test (Method A), by embedding the polyester fiber cord in unvulcanized rubber and measuring at 150°C for 180 minutes at 50 kg / cm². 2After press vulcanization and subsequent cooling, the synthetic fiber cord was pulled out of the rubber block at a speed of 300 mm / min. The load required for this pulling was determined for each sample, and the arithmetic mean of 10 samples was used as the heat-resistant adhesive strength.

[0078] (3) Fatigue resistance (retention rate) in rubber The fatigue strength of the disc was evaluated in accordance with JIS L1017 (2002), Annex 1, 2.2.2, Goodrich method. Two polyester fiber cords were embedded in unvulcanized rubber and subjected to a fatigue test at 150°C for 30 minutes at 50 kg / cm². 2 A rubber composite was prepared by press vulcanization under the specified conditions. This test specimen was subjected to deformation of 6.3% compression and 12.6% elongation per cycle at 2600 cycles / min in a 100°C atmosphere for 12 hours. After that, the polyester fiber cord was removed from the rubber and the fracture strength after fatigue was measured. The retention rate of the fracture strength before and after the fatigue test was determined for each sample, and the arithmetic mean of the eight samples was taken as the fatigue resistance (retention rate) in the rubber.

[0079] The composition of the unvulcanized rubber compound used for measuring initial adhesion, heat-resistant adhesion, and fatigue resistance in rubber is as follows. Natural rubber (RSS#1): 70 (parts by weight) SBR (#1502, manufactured by JSR Corporation): 30 (parts by weight) HAF Carbon Black: 40 (weight portion) Stearic acid: 2 parts by weight Sulfur: 2 (parts by weight) Zinc oxide: 5 (parts by weight) 2,2'-Dithiobenzothiazole: 3 parts by weight Naphthenic acid process oil: 3 parts by weight.

[0080] (4) Passability through the dipping process Two strands of 1670dtex polyester multifilament yarn (Toray Industries, Inc., "Tetron" 1670T-360-705M) were twisted with 40 twists / 10cm for the undertwist and 40 twists / 10cm for the upper twist to obtain a twisted cord. The twisted cord was immersed in a first treatment agent using a computer treater (Ritzler Co., Ltd.), dried at 120°C for 2 minutes, and then heat-treated at 245°C for 1 minute. Subsequently, it was immersed in a second treatment agent, dried at 120°C for 2 minutes, and then heat-treated at 240°C for 1 minute to obtain a polyester fiber cord. After 3000m of heat treatment with the second treatment agent, the amount of resin residue accumulated on the heat treatment furnace turn roll (the roll in contact with the cord) of the computer treater was checked and determined (resin residue: high = B > A > S = none). In this invention, S and A are considered acceptable levels for process passability that are suitable for practical use, but S is superior in practical terms.

[0081] (5) Measurement of number-average molecular weight and weight-average molecular weight of lignin derivatives The number-average molecular weight and weight-average molecular weight of lignin derivatives were measured by GPC (gel permeation chromatography). A solvent (ammonia buffer / methanol) was added to the lignin derivative sample, and the mixture was stirred at room temperature to dissolve it. The sample was then filtered through a 0.5 μm filter. The results were then measured by GPC, and peaks were detected using a UV detector. The molecular weight was determined relative to polyethylene oxide and polyethylene glycol. The measurement results are described in the examples below. Detailed measurement conditions are described below. Measuring device: Manufactured by Shimadzu Corporation Column used: TSKgel GMPW XL 1 club, G3000PW XL 1 piece (φ7.8mm x 30cm, manufactured by Tosoh) Solvent: 0.1M ammonia buffer (pH 11) / methanol (4 / 1, v / v) Standard materials: Monodisperse polyethylene oxide and polyethylene glycol manufactured by Tosoh and Agilent. Detector: UV detector (Shimadzu Corporation SPD-M20A).

[0082] (6) Tackiness of the cord surface Unvulcanized rubber (0.4 mm thick) was attached to the contact part (1 x 1.5 cm) of the "Tackiness Checker" HTC-1 manufactured by Toyo Seiki Co., Ltd. with double-sided tape. On the other hand, a polyester fiber cord was wound around a flat aluminum plate without gaps. Using the "Tackiness Checker", the tackiness of the polyester fiber cord on the aluminum plate was measured under the measurement conditions of a pressure bonding force of 10 N and a pressure bonding time of 6 seconds (unit: N / 1.5 cm 2 ). The arithmetic mean value of 6 measurement times was calculated and converted to the unit N / cm 2 . The value obtained was taken as the tackiness of the cord surface layer. The composition of the unvulcanized rubber compound used was the same as that in (3) above.

[0083] (7) High-speed durability of tires Using the above-mentioned polyester fiber cord as a carcass ply, a radial tire with a tire size of 165 - SR13 was created in the same manner as the normal tire manufacturing process. After completing the high-speed durability test specified in JIS D4230 using a drum tester, the driving distance until the tire breaks was measured by increasing the speed in 10 km / h units every 30 minutes. The evaluation was shown using an index with the evaluation result of a tire using a polyester fiber cord with the RFL adhesive (conventional example) described later for the carcass ply set as 100. A larger index means better high-speed durability.

[0084] (Examples 1 - 12, Comparative Examples 1 - 7) (A) A compound containing an oxazoline group, (B) a blocked isocyanate compound, (C) a rubber latex, and (D) an epoxy compound were mixed so that the solid content ratios were as shown in Table 1, and diluted with water to obtain a first treatment agent with a total solid content concentration of 6% by weight. Only in Example 2, the total solid content concentration was 2% by weight.

[0085] Also, (a) a lignin derivative, (b) a blocked isocyanate compound, and (c) a rubber latex were mixed so that the solid content ratios were as shown in Table 1, and diluted with water to obtain a second treatment agent with a total solid content concentration of 15% by weight. Only in Example 2, the total solid content concentration was 20% by weight.

[0086] Two strands of 1670dtex polyester multifilament yarn (Toray Industries, Inc., "Tetron" 1670T-360-705M) were twisted together with 40 twists per 10cm for the undertwist and 40 twists per 10cm for the upper twist to obtain a twisted cord.

[0087] The twisted cord was immersed in a first treatment agent using a computer treater (manufactured by Ritzler Co., Ltd.), dried at 120°C for 2 minutes, and then heat-treated at 245°C for 1 minute. Subsequently, it was immersed in a second treatment agent, dried at 120°C for 2 minutes, and then heat-treated at 240°C for 1 minute to obtain a polyester fiber cord.

[0088] The amount of resin adhering to the coating of the obtained polyester fiber cord with the first treatment agent and the amount of resin adhering to the coating of the coating with the second treatment agent are shown in Table 1.

[0089] The components of the first bath treatment agent shown in Table 1 are as follows: (A)-1: Compound containing an oxazoline group (Epocross K-2035E, manufactured by Nippon Shokubai Co., Ltd., oxazoline group-containing acrylic-styrene copolymer, Tg 50℃, oxazoline group content 1.8 mmol / g, solid) (A)-2: Compound containing an oxazoline group (Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., oxazoline group-containing acrylic copolymer, Tg 50℃, oxazoline group content 4.5 mmol / g, solid) (A)-3: Compound containing an oxazoline group (Epocross K-2010E, manufactured by Nippon Shokubai Co., Ltd., oxazoline group-containing acrylic-styrene copolymer, Tg -50℃, oxazoline group content 1.8 mmol / g, solid) (A)-4: Compound containing an oxazoline group (Epocross WS-300, manufactured by Nippon Shokubai Co., Ltd., oxazoline group-containing acrylic / styrene copolymer, Tg 90℃, oxazoline group content 7.7 mmol / g, solid) (B)-1: Blocked isocyanate (DM-6400, manufactured by Meisei Chemical, oxime-blocked MDI, 2 functional groups) (B)-2: Blocked isocyanate (DM-3031CONC, manufactured by Meisei Chemical, lactam block MDI, 2 functional groups) (B)-3: Blocked isocyanate (Elastron BN-27, manufactured by Daiichi Kogyo Seiyaku, lactam block polymeric MDI, 5 functional groups) (B)-4: Blocked isocyanate (Meisei Chemical Co., Ltd. "Meikanate" TP-10, oxime-blocked TDI, 6 functional groups) (C)-1: Rubber latex (PYRATEX manufactured by Nippon A&L Co., Ltd., VP latex, Mooney viscosity (ML1+4 100℃) 35, Tg-55℃). (C)-2: Rubber latex (PYRATEX-HM manufactured by Nippon A&L Co., Ltd., VP latex, Mooney viscosity (ML1+4 100℃) 90, Tg-55℃). (C)-3: Rubber latex (PYRATEX-LB manufactured by Nippon A&L Co., Ltd., VP latex, Mooney viscosity (ML1+4 100℃) 120, Tg-25℃). (D)-1: Epoxy compound (Nagase ChemteX Corporation, "Denacol" EX614B).

[0090] The components of the second bath treatment agent shown in Table 1 are as follows: (a)-1: Lignin derivative ("Vanilex" N, manufactured by Nippon Paper Industries Co., Ltd., sodium ligninsulfonate, number average molecular weight 29,000, weight average molecular weight 105,000) (a)-2: Lignan derivative ("Vanilex" RN, manufactured by Nippon Paper Industries Co., Ltd., sodium ligninsulfonate, number average molecular weight 34,000, weight average molecular weight 112,000) (a)-3: Lignin derivative (Pearllex "NP" manufactured by Nippon Paper Industries Co., Ltd., sodium lignin sulfonate, number average molecular weight 97,000, weight average molecular weight 146,000) (a)-4: Lignin derivative ("Sun Extract" P252 manufactured by Nippon Paper Industries Co., Ltd., sodium lignin sulfonate, number average molecular weight 66,000, weight average molecular weight 135,000) (b)-1: Blocked isocyanate (DM-6400, manufactured by Meisei Chemical, oxime-blocked MDI, 2 functional groups) (b)-2: Blocked isocyanate (DM-3031CONC, manufactured by Meisei Chemical, lactam block MDI, 2 functional groups) (b)-3: Blocked isocyanate (Elastron BN-27, manufactured by Daiichi Kogyo Seiyaku, lactam block polymeric MDI, 5 functional groups) (c)-1: Rubber latex (PYRATEX manufactured by Nippon A&L Co., Ltd., VP latex, Mooney viscosity (ML1+4 100℃) 35, Tg-55℃). (c)-2: Rubber latex (PYRATEX-HM manufactured by Nippon A&L Co., Ltd., VP latex, Mooney viscosity (ML1+4 100℃) 90, Tg-55℃). (c)-3: Rubber latex (PYRATEX-LB manufactured by Nippon A&L Co., Ltd., VP latex, Mooney viscosity (ML1+4 100℃) 120, Tg-25℃).

[0091] (Comparative Example 8) The same treatment as in Example 1 was performed, except that immersion with the first treatment agent and heat treatment were not performed.

[0092] (Conventional example) For the first treatment agent, a treatment agent with the composition shown in Table 1 was used, and for the second treatment agent, a conventional RFL adhesive was used, and the same immersion and heat treatment as in Example 1 was performed. RFL was prepared by mixing resorcinol / formaldehyde in a molar ratio of 1 / 1.5 in the presence of caustic soda, adjusting the solid content concentration to 10%, and aging for 2 hours to obtain an initial condensate of resorcinol and formalin (RF (resorcinol-formaldehyde resin)). Next, this initial condensate (RF) and rubber latex (Piratex, 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. This mixture was diluted with water to a solid content of 15% by weight and used.

[0093] The polyester fiber cords obtained as described above were embedded in unvulcanized rubber and vulcanized. After this, the initial adhesive strength, heat-resistant adhesive strength, and fatigue resistance in the rubber were measured. Furthermore, radial tires were fabricated using these polyester fiber tire cords as carcass plies, and high-speed durability tests were conducted. The results are shown in Tables 1 and 2.

[0094] As shown in Tables 1 and 2, in the examples according to the present invention, the adhesive treatment agent does not contain resorcinol-formaldehyde resin, which is advantageous in reducing environmental impact compared to conventional RFL adhesives, and the adhesion to rubber is as good as that of RFL adhesives, and furthermore, the heat-resistant adhesive strength is significantly better and fatigue resistance is improved. In addition, it can be seen that the accumulation of resin residue in the dipping process is suppressed and productivity is improved. Furthermore, it can be seen that tire performance with high-speed durability performance superior to that of tire cords made with conventional RFL adhesives can be obtained.

[0095] [Table 1]

[0096] [Table 2]

Claims

1. A polyester fiber cord for rubber reinforcement is provided, wherein the polyester fiber is coated with a first treatment agent comprising at least four types: (A) a compound containing an oxazoline group, (B) a blocked isocyanate compound, (C) rubber latex, and (D) an epoxy compound, and further coated as an outer layer with a second treatment agent comprising at least three types: (a) a lignin derivative, (b) a blocked isocyanate compound, and (c) rubber latex, wherein the first treatment agent comprises (A) with a total solid content of 100% by weight. A polyester fiber cord for rubber reinforcement, characterized in that it contains 10 to 50% by weight of a compound containing an oxazoline group, 3 to 13% by weight of a blocked isocyanate compound, 20 to 60% by weight of a rubber latex, and 20 to 60% by weight of an epoxy compound, and the number average molecular weight of the lignin derivative contained in the second treatment agent is 10,000 to 60,000 and the weight average molecular weight is 80,000 to 130,000, and it does not contain resorcinol-formaldehyde resin.

2. The polyester fiber cord for rubber reinforcement according to claim 1, characterized in that the (B) blocked isocyanate compound contained in the first treatment agent is a bifunctional MDI-based blocked isocyanate.

3. The rubber-reinforced polyester fiber cord according to claim 1, characterized in that the (b) blocked isocyanate compound contained in the second treatment agent is a bifunctional MDI-based blocked isocyanate.

4. The rubber-reinforced polyester fiber cord according to claim 1, characterized in that the (B) blocked isocyanate compound contained in the first treatment agent is a bifunctional MDI-based blocked isocyanate, and the (b) blocked isocyanate compound contained in the second treatment agent is a bifunctional MDI-based blocked isocyanate.

5. The rubber-reinforced polyester fiber cord according to claim 1, characterized in that the (C) rubber latex contained in the first treatment agent includes VP latex having a Mooney viscosity (ML1 + 4 at 100°C) of 20 to 100 and a Tg of -70°C to -30°C.

6. The rubber-reinforced polyester fiber cord according to claim 1, characterized in that the (c) rubber latex contained in the second treatment agent includes VP latex having a Mooney viscosity (ML1 + 4 at 100°C) of 20 to 100 and a Tg of -70°C to -30°C.

7. The (B) blocked isocyanate compound contained in the first treatment agent is a bifunctional MDI-based blocked isocyanate, and the (b) blocked isocyanate compound contained in the second treatment agent is a bifunctional MDI-based blocked isocyanate, and further, The rubber-reinforced polyester fiber cord according to claim 1, characterized in that the (C) rubber latex contained in the first treatment agent contains VP latex having a Mooney viscosity (ML1 + 4 100°C) of 20 to 100 and a Tg of -70°C to -30°C, and the (c) rubber latex contained in the second treatment agent contains VP latex having a Mooney viscosity (ML1 + 4 100°C) of 20 to 100 and a Tg of -70°C to -30°C.

8. The rubber-reinforced polyester fiber cord according to any one of claims 1 to 7, characterized in that the (A) oxazoline group-containing compound contained in the first treatment agent has a Tg of 0 to 80°C and an oxazoline group content of 1.0 to 5.0 mmol / g, solid.

9. A polyester fiber cord for rubber reinforcement according to any one of claims 1 to 7, characterized in that the tackiness of the cord surface layer is 2.0 to 10.0 N / cm².

10. The second treatment agent is characterized in that, when the total solid content of the treatment agent is 100% by weight, the content of (a) lignin derivative is 5 to 50% by weight, and the solid content weight ratio of (a) lignin derivative to (b) blocked isocyanate compound is (solid content of a): (solid content of b) = 10:1 to 10:20, as described in any one of claims 1 to 7.

11. A polyester fiber cord for rubber reinforcement according to any one of claims 1 to 7, characterized in that the amount of resin adhering to the film by the first treatment agent is 1 to 4% by weight, the amount of resin adhering to the film by the second treatment agent is 1 to 4% by weight, and the total amount of resin adhering to the film by the first treatment agent and the film by the second treatment agent is 2 to 6% by weight.

12. A tire made using a rubber-reinforced polyester fiber cord according to any one of claims 1 to 7.

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