Adhesive composition for polyester tire cord, method for manufacturing polyester tire cord, and tire cord

Abstract

The present invention relates to an adhesive composition for a polyester tire cord, a method for preparing a polyester tire cord, and a tire cord comprising the same, according to the present invention, when the polyester tire cord is prepared, the adhesive composition can be used for manufacturing a polyester tire cord, according to the present invention, the binding force between polyester fibers and a first treatment liquid can be increased by treating with the first treatment liquid containing a salt containing an anionic functional group, and then the crosslinking density can be increased by treating with a second treatment liquid containing an isoprene rubber latex, thereby not only having excellent high-temperature adhesive force, but also having excellent water resistance. And no harmful substances are used, so that the environment-friendly property is realized. In addition, uniform adhesion of the processing liquid is achieved by minimizing the influence caused by the external environment, thereby reducing the manufacturing manufacturability and the production cost. The polyester tire cord prepared as above can exhibit high heat-resistant adhesive force, rubber coverage, and excellent heat resistance characteristics.

Description

TECHNICAL FIELD

[0001] The present application relates to an adhesive composition for a polyester tire cord and a polyester tire cord, and more particularly, to an adhesive composition for a polyester tire cord and a polyester tire cord, the composition comprising a first treatment liquid comprising a salt containing an anionic functional group, so that the adhesion of the polyester fiber to the first treatment liquid can be increased, and a second treatment liquid comprising an isoprene rubber latex, so that the crosslinking density is improved, so that an eco-friendly adhesive can be provided, which not only has excellent high-temperature adhesion, but also does not use environmentally harmful substances. BACKGROUND

[0002] In general, polyester fiber reinforced materials represented by polyethylene terephthalate (hereinafter, referred to as "PET") have excellent mechanical strength, elastic modulus, dimensional stability, and heat resistance, which are important properties that rubber reinforcing materials should have, and thus are widely used as rubber composites, for example, reinforcing materials for tires, belts, or hoses, etc. However, since the polyester fiber surface is non-reactive, the adhesion to rubber is poor, and thus methods of improving the adhesion of the fiber to rubber by treating the fiber surface with p-chlorophenol-based RF resin (PEXUL), an epoxy compound, and a diisocyanate compound are being studied.

[0003] These polyester fiber adhesion methods use chemicals such as resorcinol, formaldehyde, ammonia, etc., and thus can cause environmental problems.

[0004] International Patent Publication Nos. WO2013 / 017421 and WO2013 / 017422 disclose a method of providing an eco-friendly adhesive by using a polyphenol or a phloroglucinol having the same reactive group instead of resorcinol and formaldehyde, and an aromatic polyaldehyde. However, since these polyester fiber adhesion methods use substances having low water solubility, a step of modifying them to be soluble in water by a separate reaction process is required, and since the viscosity of the adhesive liquid increases as high molecular weight substances are used, it can be difficult to perform uniform surface treatment.

[0005] On the other hand, International Patent Publication No. WO2015 / 188939 discloses an eco-friendly adhesive using an acrylic resin and an epoxy compound / isocyanate instead of resorcinol, formaldehyde. However, since these eco-friendly adhesives use an acrylic resin as an acid, a step of adjusting the pH to be alkaline to improve the compatibility with the latex is required to be performed separately, and there is also no high-temperature adhesion improvement effect.

[0006] Korean Patent Publication No. 10-2017-0085882 discloses a method for preparing an environmentally friendly secondary treatment solution using epoxy phenolic resin and polybutadiene-maleic anhydride copolymer instead of resorcinol-formaldehyde resin and adding rubber latex. Epoxy phenolic resin and polybutadiene-maleic anhydride copolymer have excellent water solubility and dispersibility, thus allowing for the formulation of adhesives with water without separate modification processes, and exhibiting excellent adhesion without the use of harmful substances such as resorcinol and formaldehyde. However, the adhesion strength (hereinafter referred to as "high-temperature adhesion strength") of these polyester fiber bonding methods is low when measured at a high temperature of approximately 150°C after vulcanization with rubber (160°C, 20 minutes). This is because the physical / chemical bonding strength between the polyester surface and the primary treatment solution is insufficient, and the bond between the secondary treatment solution and the rubber may decompose at high temperatures.

[0007] Furthermore, Japanese Patent Publication No. 2002-363228 discloses a method for improving heat resistance by adding styrene sulfonate during the synthesis of vinylpyridine latex. Since styrene sulfonate possesses both styrene double bonds and a sulfonate, it can improve the heat resistance within the latex. However, the method of synthesis by adding heat-resistant additives to the latex used in the second treatment solution cannot prevent the reduction in high-temperature adhesion between the polyester surface and the first treatment solution. Moreover, since the latex contains styrene sulfonate as an additive to improve heat resistance, it cannot improve the bonding strength with the epoxy compounds and isocyanates used in the first treatment solution. Summary of the Invention

[0008] Technical issues

[0009] One object of the present invention is to provide an adhesive composition for polyester tire cords that is environmentally friendly and achieves uniform adhesion of the adhesive liquid by minimizing the influence of external environmental factors such as temperature and humidity, thereby reducing the processability and production cost and improving the uniformity of quality.

[0010] Another object of the present invention is to provide a method for preparing polyester tire cord, the method using an adhesive composition that has excellent high-temperature adhesion and is environmentally friendly.

[0011] Another objective of this invention is to provide a high-performance tire cord that reduces the rigidity of the tire cord and improves its high-temperature adhesion, thereby preventing the separation of rubber from the cord during high-speed tire travel.

[0012] Technical solution

[0013] One embodiment of the present invention for achieving the above-mentioned objective relates to an adhesive composition for polyester tire cords, comprising:

[0014] The first treatment solution contains blocked diisocyanates, epoxy compounds, and salts containing anionic functional groups; and

[0015] The second treatment solution contains epoxy phenolic resin, polybutadiene-maleic anhydride copolymer, vinylpyridine latex, and isoprene rubber latex.

[0016] Another embodiment of the present invention for achieving the above-mentioned objective relates to a method for preparing polyester tire cord, the method comprising the following steps:

[0017] A first treatment solution is prepared, the first treatment solution comprising a blocked diisocyanate, an epoxy compound, and a salt containing anionic functional groups;

[0018] The polyester raw cord is passed through the first treatment liquid while being subjected to tensile force;

[0019] The raw fabric that has passed through the first treatment solution is dried and heat-treated;

[0020] The heat-treated polyester raw cord is passed through a second treatment solution, the second treatment solution comprising epoxy phenolic resin, polybutadiene-maleic anhydride copolymer, vinyl pyridine latex, and one or more isoprene rubber latexes; and

[0021] The raw fabric that has passed through the second treatment solution is dried and stabilized.

[0022] Another embodiment of the present invention for achieving the above objectives relates to a polyester tire cord prepared by the method for preparing the polyester tire cord and having excellent high-temperature adhesion.

[0023] The effects of the invention

[0024] According to the present invention, when preparing polyester tire cord, the bonding force between the polyester raw cord and the first treatment solution can be increased by treating it with a first treatment solution containing a salt with anionic functional groups, and then the crosslinking density can be increased by treating it with a second treatment solution containing isoprene rubber latex. This results in excellent high-temperature adhesion and environmental friendliness because no environmentally harmful substances are used. Furthermore, by minimizing the impact of external environmental factors to achieve uniform adhesion of the treatment solution, the manufacturing process and production costs can be reduced. This polyester tire cord exhibits high heat-resistant adhesion, high rubber coverage, and excellent heat resistance properties. Detailed Implementation

[0025] This invention can be modified in various ways and can take various forms. It should be understood to include all modifications, equivalents and substitutes within the scope of the concept and technology of this invention.

[0026] In this invention, terms such as “comprising” or “having” should be understood as indicating the presence of features, numbers, steps, actions, structural elements, components or combinations thereof as described in the specification, without pre-excluding the presence or additional possibility of one or more other features or numbers, steps, actions, structural elements, components or combinations thereof.

[0027] According to the present invention, in order to improve high-temperature adhesion, a salt containing anionic functional groups such as sulfonic acid group, sulfuric acid group, phosphonic acid group, phosphoric acid group, phosphorous acid group, phenolic hydroxyl group, and carboxylic acid group is added as a heat-resistant additive in the first treatment solution, and an isoprene rubber latex with high crosslinking density is added in the second treatment solution, thereby providing an adhesive composition with excellent high-temperature adhesion and an environmentally friendly method for preparing polyester tire cord using the same.

[0028] The adhesive composition for polyester tire cords of the present invention, the method for preparing polyester tire cords using the same, and the polyester tire cords prepared therefrom will be described in detail below with reference to the embodiments.

[0029] The adhesive composition for polyester tire cords of the present invention comprises one or more epoxy compounds selected from the group consisting of glycidyl-based glycerol epoxy resin, polyglycidyl epoxy resin, sorbitol epoxy resin, phenolic epoxy resin and cresol phenolic epoxy resin, and a blocking diisocyanate containing thermally dissociated caprolactam, resorcinol, phenol, etc. as a first treatment liquid as an epoxy curing agent.

[0030] The blocked diisocyanate is an isocyanate that is blocked to prevent the isocyanate group (-NCO) from reacting with the hydroxyl group (-OH) at room temperature. It includes at least one of aromatic diisocyanates, such as tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,6-hexane diisocyanate, diphenylmethane 4,4'-diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 2,4- or 2,6-toluene diisocyanate, p-xylene diisocyanate, 2,4'- or 4,4'-diisocyanate diphenylmethane, and 1,3- or 1,4-phenylene diisocyanate.

[0031] The epoxy compound content is from 0.2% to 5.0% by weight, preferably from 0.3% to 2.0% by weight, based on the total solids content in the first treatment solution. When the weight ratio is less than 0.2% by weight, the adhesive properties are reduced due to the low epoxy compound content. When it is greater than 5.0% by weight, the stiffness of the cord increases due to the curing of the epoxy compound, which may lead to a decrease in cord properties such as fatigue resistance.

[0032] Furthermore, the weight ratio of blocked diisocyanate to epoxy compound is 2:1 to 1:5, preferably 1:1 to 1:3. When the content ratio of blocked diisocyanate to epoxy compound is less than 2:1, the epoxy compound cannot be fully cured, resulting in low adhesion. When it is greater than 1:5, the excess curing agent may cause side reactions such as self-reaction of the curing agent, which may lead to a decrease in adhesion.

[0033] According to the present invention, in order to improve the adhesion at high temperatures, salts containing anionic functional groups such as sulfonic acid (salt) group, sulfate (salt) group, phosphonic acid (salt) group, phosphate (salt) group, phosphite (salt) group, phenolic hydroxyl (salt) group, and carboxylic acid (salt) group are used, wherein the anionic functional group refers to a functional group that can exist in anionic form in water.

[0034] Preferably, the weight ratio of the epoxy compound to the salt containing anionic functional groups is 5:1 to 1:3, more preferably, it can be 3:1 to 1:2. When the content ratio of the epoxy compound to the salt containing anionic functional groups is less than 5:1, it is difficult to expect an improvement in the high-temperature adhesive strength due to the anionic functional groups present in the salt. When it is greater than 1:3, the reaction between the fiber surface and the anionic groups due to the addition of excessive anions may lead to a decrease in the initial adhesive strength.

[0035] Salts containing anionic functional groups have high reactivity with PET raw cord. At the same time, due to the presence of anionic groups, they also have high reactivity with epoxy compounds, thereby improving the bonding force between PET raw cord and epoxy compounds. They can also react with epoxy phenolic resin and maleic anhydride in the secondary treatment liquid, thereby improving the adhesion at high temperatures.

[0036] In this invention, the type of salt contained in the salt containing the anionic functional group is not particularly limited, but may include, for example, alkali metal salts such as lithium salts, sodium salts, and potassium salts, salts of Group 2 elements such as calcium salts, amine salts, and ammonium salts. Alkali metal salts are preferred, and sodium salts are more preferred. The salt type may be a single type, or a combination of two or more types.

[0037] Salts containing anionic functional groups may contain alkyl groups with 1 or more but less than 20 substituted or unsubstituted carbon atoms, aryl groups with 6 or more but less than 60 substituted or unsubstituted cyclic carbon atoms, or heteroaryl groups with 2 or more but less than 60 substituted or unsubstituted cyclic carbon atoms. For example, the heteroaryl group may contain O, N, or S as heteroatoms. Furthermore, salts containing anionic functional groups may contain hydrogen, deuterium, alkyl groups with 1 or more but less than 20 substituted or unsubstituted carbon atoms, alkylene groups with 1 or more but less than 20 substituted or unsubstituted carbon atoms, aryl groups with 6 or more but less than 60 substituted or unsubstituted cyclic carbon atoms, or heteroaryl groups with 2 or more but less than 60 substituted or unsubstituted cyclic carbon atoms as substituents.

[0038] As a salt containing an anionic functional group having a sulfonic acid (salt) group, sulfonates such as alkyl sulfonic acids (e.g., methanesulfonic acid, 2-propanol sulfonic acid, lauryl sulfonic acid), alkyl diphenyl ether disulfonic acids (e.g., lauryl diphenyl ether disulfonic acid), and aromatic sulfonic acids (e.g., benzenesulfonic acid, styrene sulfonic acid, p-toluenesulfonic acid, n-dodecylbenzenesulfonic acid, 2-naphthalenesulfonic acid, laurylnaphthalenesulfonic acid) can be used.

[0039] As a salt containing an anionic functional group having a sulfate (salt) group, examples such as alkyl sulfate salts (e.g., ammonium dodecyl sulfate), polyoxyalkylene ether sulfate salts, polyoxyalkylene allyl ether sulfate salts, polyoxyalkylene allyl phenyl ether sulfate salts (e.g., polyoxyethylene allyl phenyl ether sulfate salts), polyoxyalkylene allyl phenyl ether sulfate salts (e.g., polyoxyethylene alkyl allyl phenyl ether sulfate salts), polyoxyalkylene phenyl ether sulfate salts (e.g., polyoxyethylene phenyl ether sulfate salts), and polyoxyalkylene polycyclic phenyl ether sulfate salts can be used.

[0040] As a salt containing anionic functional groups with a phosphonic acid (salt) group, for example, dodecylphosphonic acid can be used.

[0041] As a salt containing anionic functional groups with a phosphate (salt) group, phosphates such as monoalkyl phosphate, alkyl ether phosphate, polyoxyethylene alkyl ether phosphate, polyoxyethylene allyl phenyl ether phosphate, and polyoxyethylene alkyl phenyl ether phosphate can be used.

[0042] Unlike the use of treatment fluids (RFL) containing water, resorcinol, formaldehyde, rubber latex, ammonia, etc., the adhesive for polyester tire cords of the present invention comprises epoxy phenolic resin (e.g., Allnex VPW1942 / 52W), polybutadiene-maleic anhydride copolymer (e.g., Crayvalley Ricobond 7004), and rubber latex capable of interacting with rubber as a second treatment fluid. In order to increase the crosslinking density of the adhesive fluid and rubber through co-vulcanization, the high-temperature adhesion can be improved by adding one or more isoprene rubber latexes with double bonds.

[0043] The content of epoxy phenolic resin is suitable at 1.0% to 5.0% by weight, preferably 1.5% to 3.0% by weight, based on the weight ratio of the total solids content in the second treatment liquid. When it is less than 1.0% by weight, it is difficult to exhibit adhesion to rubber, and when it is greater than 5.0% by weight, there is no increase in adhesion, and the excessive resin content may lead to a decrease in public welfare.

[0044] The weight ratio of epoxy phenolic resin to polybutadiene-maleic anhydride copolymer is preferably from 4:1 to 1:2, and more preferably from 3:1 to 1:1. When the content of polybutadiene-maleic anhydride copolymer is less than 4:1, it is difficult to expect an improvement in the bonding strength between epoxy phenolic resin and latex. When it is greater than 1:2, the adhesive strength decreases due to the increased content of polybutadiene-maleic anhydride copolymer.

[0045] In this invention, the isoprene rubber latex used in the second treatment liquid can be any suitable isoprene rubber latex, for example, one or more selected from the group consisting of synthetic isoprene rubber latex (IR), natural isoprene rubber latex (NR), and combinations thereof. In the embodiments, the isoprene rubber latex can be natural isoprene rubber latex (NR).

[0046] The weight ratio of isoprene rubber latex to vinylpyridine latex is preferably 1:1 to 1:20, more preferably 1:1.5 to 1:15. When the content ratio of isoprene rubber latex to vinylpyridine latex is greater than 1:1, the adhesion and processability decrease. When it is less than 1:20, it is difficult to expect an improvement in high-temperature adhesion as the crosslinking density of the isoprene rubber latex increases.

[0047] In this invention, the rubber latex capable of interacting with rubber includes at least one of vinylpyridine-styrene-butadiene, vinylpyridine-styrene-butadiene modified with carboxylic acid, styrene-butadiene, styrene-butadiene modified with carboxylic acid, and natural rubber latex.

[0048] The second treatment liquid of this invention can be used immediately after mixing water, epoxy phenolic resin, polybutadiene-maleic anhydride, vinylpyridine latex, and one or more isoprene rubber latexes, or after mixing vinylpyridine latex, styrene-butadiene latex, and one or more isoprene rubber latexes. Therefore, no reaction curing time is required, and the adhesive preparation process can be simplified and streamlined, thereby reducing costs. Since the increased process speed has the external effect of reducing the unit price of the product, economic benefits can be achieved. Furthermore, the adhesive preparation process of this invention completely avoids the use of environmentally regulated substances such as resorcinol, formaldehyde, and ammonia, thus providing an environmentally friendly adhesive. By minimizing the influence of external environmental factors such as temperature and humidity, uniform adhesion of the adhesive is achieved, resulting in improved quality uniformity and excellent adhesive properties even at low DPU (Dip Pick Up).

[0049] The method for preparing polyester tire cord of the present invention includes the following steps: preparing a first treatment liquid, wherein the first treatment liquid comprises a blocked diisocyanate, an epoxy compound and a salt containing anionic functional groups; passing the polyester raw cord through the first treatment liquid while applying tensile force; and drying and heat-treating the raw cord that has passed through the first treatment liquid.

[0050] The heat-treated polyester raw cord is passed through a second treatment liquid, which contains epoxy phenolic resin, polybutadiene-maleic anhydride copolymer, vinylpyridine latex and isoprene rubber latex; and the raw cord passing through the second treatment liquid is dried and stabilized.

[0051] The method for preparing polyester tire cord of the present invention uses the above-described adhesive composition for polyester tire cord, and the first treatment liquid and the second treatment liquid are directly applied as described above.

[0052] According to the method for preparing polyester tire cord of the present invention, the bonding force between the polyester raw cord and the first treatment solution can be increased by treating the polyester raw cord with a first treatment solution containing a blocked diisocyanate, an epoxy compound and a salt containing anionic functional groups. Then, the crosslinking density can be increased by treating it with a second treatment solution containing epoxy phenolic resin, polybutadiene-maleic anhydride copolymer, vinyl pyridine latex and isoprene rubber latex. The tire cord prepared thereby not only has excellent high-temperature adhesion, but also has the advantage of not using environmentally harmful substances.

[0053] The specific method for preparing the polyester tire cord of the present invention is described below.

[0054] First, PET fibers can be prepared by melt spinning PET chips. PET yarns can then be prepared by multi-stage stretching and winding of the prepared PET fibers. Raw cord can be prepared by twisting the prepared PET yarns using a twisting machine.

[0055] Twisting and twisting can be performed simultaneously or separately, and are not limited to either method. When twisting and twisting are performed simultaneously, a direct twisting machine can be used; when they are performed separately, a ring twister (RT) twisting machine can be used. The twist rate of the twist / twist can be above 200 / 200 TPM (twist per meter) and below 500 / 500 TPM. When the twist rate of the twist / twist is less than 200 / 200 TPM, the fatigue resistance may decrease due to the reduced elongation of the PET green cord. When the twist rate of the twist / twist is greater than 500 / 500 TPM, the strength of the PET green cord may decrease significantly.

[0056] Tire cords can be prepared by passing the green cords thus prepared for use in tire cords through a first treatment solution and a second treatment solution. Specifically, the step of treating the green cords for tire cords with the first treatment solution may include passing the green cords through the first treatment solution while applying tensile force, and then drying and heat-treating the green cords after passing through the first treatment solution. In this case, based on 100% by weight of the first treatment solution, the first treatment solution may contain 1.0% to 5.0% by weight of a blocked diisocyanate, 0.3% to 2.0% by weight of an epoxy compound, 0.3% to 2.0% by weight of a salt containing anionic functional groups, and the remaining percentage by weight of water.

[0057] In the drying step, moisture is removed, with a preferred drying temperature of 140°C to 180°C and a drying time of 60 to 180 seconds. Then, by heat treatment at a temperature of 200°C to 250°C for 30 to 150 seconds, the blocked diisocyanate is decomposed and becomes reactive, thus making the fiber surface reactive through a chemical reaction with the epoxy compound.

[0058] Then, the raw fabric treated with the first treatment solution is treated with a second treatment solution. The step of the second treatment solution treatment may include passing the raw fabric treated with the first treatment solution through the second treatment solution and drying and stabilizing the raw fabric that has passed through the second treatment solution.

[0059] Based on 100% by weight of the second treatment liquid, the second treatment liquid may contain 1.5% to 3.0% by weight of epoxy phenolic resin, 0.5% to 2.5% by weight of polybutadiene-maleic anhydride copolymer, 10.0% to 20.0% by weight of vinylpyridine latex, 0.5% to 10.0% by weight of isoprene rubber latex, and the remaining % by weight of water, in order to increase high-temperature adhesion by increasing the crosslinking density.

[0060] The epoxy phenolic resin serves to interact with the rubber. This epoxy phenolic resin can be prepared by attaching a high molecular weight polyisocyanate to the end of an epoxy resin synthesized from bisphenol A and epichlorohydrin, phenolic varnish and epichlorohydrin, or methyl phenolic resin and epichlorohydrin, and dispersing it in an organic solvent such as butanol.

[0061] Alternatively, a high molecular weight epoxy compound can be synthesized by addition polymerization of a liquid epoxy resin synthesized from bisphenol A and epichlorohydrin with phenolic varnish or methyl phenolic resin, followed by the attachment of isocyanates blocked with resorcinol, phenol, caprolactam, etc., to the end and dispersion in an organic solvent such as butanol. Another synthetic method involves synthesizing an epoxy compound in the form of phenolic varnish or methyl phenolic resin using bisphenol A and epichlorohydrin, followed by the attachment of resorcinol or resorcinol-formaldehyde resin to the end and dispersion in an organic solvent. Besides the above synthetic methods, a mixture can also be prepared by mixing an epoxy compound in the form of phenolic varnish or methyl phenolic resin with phenol resin, water, a co-solvent, and a dispersant, followed by heating under very strong shear force. This mixture can be uniformly dispersed in the form of small particles and remains stable during cooling using the dispersant. In this case, alcohols or glycol ethers can be used as co-solvents.

[0062] The content of vinylpyridine latex is preferably 10.0% to 20.0% by weight, based on 100% by weight of the second treatment liquid. When the content of vinylpyridine latex is less than 10.0% by weight, it cannot exhibit sufficient adhesion to the rubber. When it is greater than 20.0% by weight, the initial adhesion is improved, but the latex layer formed is too thick, which may lead to the peeling of the latex layer at high temperature. Furthermore, the high adhesion amount leads to increased rigidity, resulting in reduced fatigue resistance. In addition, the latex adheres to the rollers of the heat treatment equipment, leading to reduced operability or an increase in defects in the final product.

[0063] The polyester tire cord prepared in this way has increased crosslinking density, which not only gives it excellent high-temperature adhesion, but also makes it environmentally friendly because it does not use environmentally harmful substances. Furthermore, it achieves uniform adhesion of the treatment liquid by minimizing the impact of the external environment, thereby reducing the cost of preparation and production.

[0064] The present invention will now be described in detail with reference to the following specific embodiments. The embodiments given are merely illustrative of the invention and do not limit the scope of the claims.

[0065] <Examples 1 to 10 and Comparative Examples 1 to 2>

[0066] The polyester tire cord was prepared by adjusting the contents of the first and second treatment solutions as shown in Table 1 below. A 1500 denier 2-ply polyester cord for tire cord, produced with a cable twist of 370 TPM and a ply twist of 370 TPM (PET 1500d / 2 370TPM), was immersed in the first treatment solution while under a tension of 0.1 g / d, dried in a drying zone at 160°C for 2 minutes, and then heat-treated at 245°C. The heat-treated polyester cord was then immersed again in the second treatment solution adhesive solution, dried at 160°C, and stabilized at 245°C to prepare the polyester tire cord.

[0067] <Experimental Example>

[0068] The physical properties of the polyester tire cords prepared in Examples 1 to 10 and Comparative Examples 1 to 2 were evaluated using the following methods, and the results are shown in Table 1 below.

[0069] - Adhesive strength (kgf) evaluation method: H-test (H-Test)

[0070] As a method to demonstrate the adhesion between the heat-treated tire cord and the rubber, the tire cord is placed in a rubber block and vulcanized at 160°C for 20 minutes (initial) under a pressure of 50 kgf / cm² or at 170°C for 60 minutes (heat resistant). The adhesion strength is then measured using an Instrong low-speed elongation tensile testing machine at a tensile speed of 200 m / min. The same test is repeated 10 times, and the average value is calculated. Other methods are performed according to ASTM D4776-98.

[0071] - Adhesion strength test conditions: H- Test (ASTM D4776-98) vulcanization conditions (initial: 160℃*20 minutes, heat resistance: 170℃*60 minutes)

[0072] - CRA Test (Strip Adhesion) Vulcanization Conditions (Initial: 160℃ * 20 minutes, Heat Resistance: 160℃ * 90 minutes)

[0073] - High-temperature adhesion: CRA test, evaluated after vulcanization (160℃*20 minutes) using a tensile testing machine equipped with a high-temperature chamber at 150℃ for 5 minutes.

[0074] - Adhesion Index: The percentage of each CRA adhesion value when the adhesion of existing tire cords using the first treatment fluid (epoxy compound / blocked diisocyanate) and the second treatment fluid (RFL) is set to 100.

[0075] - Rubber adhesion rate: After the high-temperature adhesion evaluation is completed, the degree of rubber adhesion at the peeled-off portion is determined visually. The rubber adhesion rate is evaluated into five grades: A, B, C, D, and E (Grade A: 100-80% rubber adhesion, Grade B: 80-60%, Grade C: 60-40%, Grade D: 40-20%, Grade E: below 20%).

[0076] [Table 1]

[0077]

[0078] According to Table 1, Examples 1 to 10 contained salts with anionic functional groups in their first treatment solutions, while Comparative Examples 1 and 2 did not contain salts with anionic functional groups in their first treatment solutions. Furthermore, Examples 1 to 10 contained rubber latex containing double bonds in their second treatment solutions, while Comparative Example 2 did not contain rubber latex containing double bonds in its second treatment solution. Additionally, Comparative Example 1 contained resorcinol, formaldehyde, and other substances that are subject to environmental regulations in its second treatment solution.

[0079] According to the adhesion index and rubber adhesion rate in Table 1, the adhesive compositions for polyester tire cords prepared according to Examples 1 to 10 exhibit excellent high-temperature adhesion, thereby reducing the processability and production cost of polyester tire cords and improving quality uniformity. Furthermore, no environmentally regulated substances are used in the preparation of the compositions, making them environmentally friendly.

[0080] The preferred embodiments of the present invention have been described in detail above. However, it will be apparent to those skilled in the art that the present invention is not limited to the above embodiments, and various modifications can be made to the structure of the present invention without departing from its purpose or scope. Therefore, the scope of protection of the present invention should be defined by the appended claims and their equivalents.

Claims

1. An adhesive composition for polyester tire cords, characterized in that, Include: The first treatment solution contains blocked diisocyanates, epoxy compounds, and salts containing anionic functional groups; and The second treatment solution contains epoxy phenolic resin, polybutadiene-maleic anhydride copolymer, vinylpyridine latex, and one or more isoprene rubber latexes.

2. The adhesive composition for polyester tire cords according to claim 1, characterized in that, The weight ratio of the epoxy compound to the salt containing anionic functional groups is from 5:1 to 1:

3.

3. The adhesive composition for polyester tire cords according to claim 1, characterized in that, The weight ratio of the one or more isoprene rubber latexes to vinylpyridine latexes is from 1:1 to 1:

20.

4. The adhesive composition for polyester tire cords according to claim 1, characterized in that, The weight ratio of the epoxy phenolic resin to the polybutadiene-maleic anhydride copolymer is 4:1 to 1:

2.

5. The adhesive composition for polyester tire cords according to claim 1, characterized in that, The anionic functional group is selected from the group consisting of sulfonic acid group, sulfate group, phosphonic acid group, phosphoric acid group, phosphite group, phenolic hydroxyl group, and carboxylic acid group.

6. The adhesive composition for polyester tire cords according to claim 1, characterized in that, The salts containing anionic functional groups are selected from the group consisting of lithium salts, sodium salts, potassium salts, calcium salts, amine salts, and ammonium salts.

7. The adhesive composition for polyester tire cords according to claim 1, characterized in that, The isoprene rubber latex is selected from synthetic isoprene rubber latex, natural isoprene rubber latex, and combinations thereof.

8. A method for preparing polyester tire cord, characterized in that, Includes the following steps: A first treatment solution is prepared, the first treatment solution comprising a blocked diisocyanate, an epoxy compound, and a salt containing anionic functional groups; The polyester raw cord is passed through the first treatment liquid while being subjected to tensile force; The raw fabric that has passed through the first treatment solution is dried and heat-treated. The heat-treated polyester raw cord is passed through a second treatment solution, the second treatment solution comprising epoxy phenolic resin, polybutadiene-maleic anhydride copolymer, vinyl pyridine latex, and one or more isoprene rubber latexes; and The raw fabric that has passed through the second treatment solution is dried and stabilized.

9. The method for preparing polyester tire cord according to claim 8, characterized in that, The weight ratio of the epoxy compound to the salt containing anionic functional groups is from 5:1 to 1:

3.

10. The method for preparing polyester tire cord according to claim 8, characterized in that, The weight ratio of the one or more isoprene rubber latexes to vinylpyridine latexes is from 1:1 to 1:

20.

11. The method for preparing polyester tire cord according to claim 8, characterized in that, The weight ratio of the epoxy phenolic resin to the polybutadiene-maleic anhydride copolymer is 4:1 to 1:

2.

12. The method for preparing polyester tire cord according to claim 8, characterized in that, The anionic functional group is selected from the group consisting of sulfonic acid group, sulfate group, phosphonic acid group, phosphoric acid group, phosphite group, phenolic hydroxyl group, and carboxylic acid group.

13. The method for preparing polyester tire cord according to claim 8, characterized in that, The isoprene rubber latex is selected from synthetic isoprene rubber latex, natural isoprene rubber latex, and combinations thereof.

14. A polyester tire cord, characterized in that, Prepared by the method for preparing polyester tire cord according to any one of claims 8 to 13, the heat-resistant adhesive strength to rubber determined by H-test is 12 kgf or more.

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