Adhesive composition for tire cord, tire cord and tire

Abstract

The present invention relates to an adhesive composition for tire cord, a tire cord and a tire, wherein the adhesive composition comprises an epoxy compound, a latex, an alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000, an amine compound and water, the tire cord comprises an adhesive layer formed of the adhesive composition, and the tire comprises the tire cord.

Description

Technical Field

[0001] The invention relates to an adhesive composition for a tire cord, a tire cord and a tire. Background Art

[0002] In order to enhance the strength of the rubber structure, fiber reinforcement is used. For example, in a rubber tire, polyester fiber, polyamide fiber, aramid fiber or polyvinyl alcohol fiber etc. can be used as a reinforcement. And, in some cases, depending on the fiber, the adhesion between the fiber and the rubber is not good, therefore, an adhesive is applied to the surface of the fiber to supplement the adhesion between the fiber and the rubber. For example, in order to improve the bonding strength between the polyester fiber (original cord) used for the tire cord and the tire rubber, an adhesive is applied to the polyester fiber.

[0003] Generally speaking, among adhesives used for the above purposes, rubber (or latex) containing resorcinol-formaldehyde or a component derived therefrom is included. However, RF containing resorcinol (a type of phenol) and formaldehyde, which are known to be carcinogens, is known to be harmful to the human body. Moreover, for adhesive waste liquid containing RF, specific subsequent management and subsequent treatment costs are generally required.

[0004] Meanwhile, as the method for applying the above-mentioned adhesive composition on the fiber-reinforced material, dipping or spraying can be considered. In this preparatory process, the various components constituting the adhesive composition should be uniformly mixed and dispersed in the solvent included in the composition. And, even after dipping or spraying the composition in which the various components are uniformly mixed and dispersed, the composition should also be uniformly coated on the surface of the fiber-reinforced material with appropriate amount. If the components of the composition are not fully mixed or the fluidity of the composition is excessively increased due to excessive use of solvent, then the bonding strength can not be ensured. Summary of the invention

[0005] Technical issues

[0006] An object of the present invention is to provide an environmentally friendly adhesive composition for tire cords, which can significantly improve the adhesive strength and heat-resistant adhesive strength between tire rubber and tire cords.

[0007] Another object of the present invention is to provide a tire cord having high adhesive strength and heat-resistant adhesiveness to tire rubber, thereby being able to improve the durability of the tire.

[0008] Still another object of the present invention is to provide a tire comprising the above tire cord.

[0009] Technical Solution

[0010] The present invention provides an adhesive composition for tire cords, comprising: an epoxy compound; a latex; an alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000; an amine compound; and water.

[0011] The present invention also provides a tire cord, comprising: a fiber base; and an adhesive layer formed on the fiber base, wherein the adhesive layer is formed of the adhesive composition for a tire cord.

[0012] The present invention also provides a tire cord, comprising: a fiber base; and an adhesive layer formed on the fiber base, wherein the adhesive layer comprises an epoxy compound, a latex, an alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000, and an amine compound.

[0013] The present invention also provides a tire comprising the tire cord.

[0014] Hereinafter, an adhesive composition for a tire cord, a tire cord, and a tire according to specific embodiments of the present invention will be described in detail.

[0015] As used herein, weight average molecular weight refers to the weight average molecular weight of polystyrene conversion measured by the GPC method. In the process of measuring the weight average molecular weight of polystyrene conversion measured by GPC, known analytical equipment, detectors (such as refractive index detectors) and analytical columns can be used, and commonly used temperature conditions, solvents and flow rates can be applied.

[0016] As a specific example of measurement conditions, a 0.05%-LiCl / DMF solution for analysis is prepared by weighing 2.12 g of anhydrous lithium chloride (LiCl), placing it in a 1 liter volumetric flask, and dissolving it in N,N-dimethylformamide (DMF). 0.0250 g (25 mg) of a polymer sample such as a polyurethane resin is added to a vial, and 10 ml of 0.05%-LiCl / DMF is added and dissolved. Then, the solution was filtered using a syringe filter with a pore size of 0.45 μm, and 100 μl of the solution was introduced into GPC. As the mobile phase of GPC, LiCl / DMF was used and introduced at a flow rate of 1.0 mL / min; as a column, 1 Agilent PLgel 5 μm Guard (7.5 x 50 mm) and 2 Agilent PLgel 5 μm Mixed D (7.5 x 300 mm) were connected in series; as a detector, an Agilent 1260 Infinity II system, RI detector was used; the measurement temperature was 40°C.

[0017] For the standard substance, 0.0050 g (5 mg) of polystyrene was added to a vial, 5 ml of 0.05%-LiCl / DMF was added and dissolved, and the measurement was performed by the above method. The calibration curve was drawn by PS 842000, 193000, 65000, 16200 and 4000.

[0018] According to one embodiment of the present invention, there is provided an adhesive composition for a tire cord, including: an epoxy compound; latex; an alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000; an amine compound; and water.

[0019] The inventors have experimentally confirmed that even if the adhesive composition applied to tire cord contains a common polyurethane resin, the bonding strength cannot be fully ensured. However, when an alicyclic polyurethane resin having a predetermined weight-average molecular weight is used, the bonding strength and heat-resistant bonding strength can be significantly improved. In particular, high bonding strength and heat-resistant adhesion with tire rubber can be exhibited, thereby improving the durability of the tire, thereby completing the present invention.

[0020] More specifically, since the weight average molecular weight (Mw) of the alicyclic polyurethane resin included in the adhesive composition for tire cord is 250,000 to 350,000, the adhesive composition for tire cord can have a viscosity similar to that of latex at room temperature, does not hydrolyze even at high temperatures, and the composition has high adhesion and is stable during stirring.

[0021] Specifically, the lower limit of the weight average molecular weight (Mw) of the polyurethane may be, for example, 255,000 or more, 260,000 or more, 265,000 or more, 270,000 or more, 275,000 or more, 280,000 or more, 285,000 or more, 290,000 or more, 295,000 or more, 300,000 or more, or 305,000 or more. And, the upper limit of the weight average molecular weight (Mw) of the polyurethane may be, for example, 345,000 or less, 340,000 or less, 335,000 or less, 330,000 or less, 325,000 or less, 320,000 or less, 315,000 or less, 310,000 or less, 305,000 or less, or 300,000 or less.

[0022] If the weight average molecular weight (Mw) of the alicyclic polyurethane resin is low, the viscosity of the adhesive composition for tire cord may be relatively low, and thus, sufficient adhesive performance may not be exhibited, and high adhesive strength and heat-resistant adhesion with tire rubber may not be ensured.

[0023] If the weight average molecular weight (Mw) of the alicyclic polyurethane resin is high, the viscosity of the adhesive composition for tire cord may be significantly increased, and thus, other components may not be uniformly mixed, and thus, it may be difficult to ensure uniform adhesive strength. Also, if the weight average molecular weight (Mw) of the alicyclic polyurethane resin is high, the alicyclic polyurethane resin itself may react in advance or react with other components to form a gel, and thus, the preparation of a uniform adhesive solution may be disturbed, and appearance defects of the product may occur.

[0024] At the same time, the alicyclic polyurethane resin with a weight average molecular weight (Mw) of 250,000 to 350,000 protects or captures the amine compound described below, so that the adhesive layer (or coating) formed by the adhesive composition can be stably cured. In addition, since the polyurethane has excellent affinity with rubber or latex components, it helps the stable bonding of the adhesive composition and the adherend including rubber, thus ensuring excellent bonding strength (especially, heat-resistant bonding strength) with the adherend. In addition, in the case of using water-dispersed polyurethane, the wear resistance and elasticity of the polyurethane can also be ensured.

[0025] The alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000 includes an alicyclic structure, and thus can improve not only the mechanical strength and dimensional stability of the adhesive composition for tire cords and tire cords prepared therefrom, but also heat resistance and fatigue properties.

[0026] On the contrary, in the case where the adhesive composition for tire cord contains an aromatic polyurethane resin containing an aromatic group in the molecule, the tensile strength or fatigue resistance of the tire cord prepared using the same may be deteriorated, or the uniformity or homogeneity of the adhesive composition for tire cord may be deteriorated, and thus, the bonding strength may be deteriorated.

[0027] The alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000 may include a reaction product between a polyisocyanate and a polyol, the polyisocyanate including one or more alicyclic groups having a carbon number of 4 to 30, more specifically, it may include a reaction product between a diisocyanate and a polyol, the diisocyanate including one or more alicyclic groups having a carbon number of 4 to 30 and including a central group having a total carbon number of 4 to 40.

[0028] The alicyclic diisocyanate may be 4,4'-dicyclohexylmethane diisocyanate (H12MDI), isophorone diisocyanate (IPDI), 1,4-cyclohexylene diisocyanate or a mixture thereof.

[0029] As examples of the polyol, polyester polyol, polyether polyol, polycarbonate polyol and the like can be mentioned.

[0030] The alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000 may further include: alcohol substances such as ethylene glycol (EG), 1,4-butanediol (BD), 1,6-hexanediol (HD) and trimethylolpropane (TMP); and chain extenders such as ethylenediamine (EDA) and diethanolamine.

[0031] Meanwhile, the alicyclic polyurethane resin may be a polyurethane dispersed in water (H2O). The content of water contained in the water-dispersed polyurethane is not particularly limited. For example, the content of water in the water-dispersed polyurethane may be 40wt% to 80wt%, and the rest may be occupied by the polyurethane. Depending on the circumstances, a small amount of known additives may be contained in the water-dispersed polyurethane in an amount of about 10wt% or less, about 5wt% or less, or about 1wt% or less.

[0032] More specifically, the alicyclic polyurethane resin may be a water-dispersed alicyclic polyurethane resin formed of an alicyclic polyurethane ionomer.

[0033] The water-dispersible alicyclic polyurethane resin formed of an alicyclic polyurethane ionomer can be prepared as follows: a polyester polyurethane (PU) is prepared from an alicyclic polyisocyanate such as 4,4'-dicyclohexylmethane diisocyanate (H12MDI), 1,6-hexanediol (HD) and dimethylolbutyric acid (DMBA), and the like, and is neutralized with triethylamine (TEA), and then dispersed in water and chain-extended with ethylenediamine (EDA) in water.

[0034] More specifically, the alicyclic polyurethane resin may include 1 mol % to 20 mol % of a moiety derived from one or more compounds selected from dimethylolbutanoic acid and dimethylolpropionic acid.

[0035] In the alicyclic polyurethane resin, moieties derived from one or more compounds selected from dimethylolbutyric acid and dimethylolpropionic acid are linked to ionic functional groups on the surface of the alicyclic polyurethane resin, thereby improving the degree of stability of the entire molecule during dispersion in water, so that the adhesive composition for tire cord can have adhesive strength and flexibility at high temperatures.

[0036] If the content of the moiety derived from one or more compounds selected from dimethylolbutyric acid and dimethylolpropionic acid in the alicyclic urethane resin is too small, the polymerization degree of the alicyclic urethane resin may decrease, or the molecular weight may not be sufficiently secured.

[0037] If the content of the moiety derived from one or more compounds selected from dimethylolbutyric acid and dimethylolpropionic acid in the alicyclic polyurethane resin is too large, the viscosity of the adhesive composition for tire cords may increase, or sludge may be formed in the composition.

[0038] Meanwhile, the adhesive composition for a tire cord may include 0.5 wt % to 10 wt % of an alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000.

[0039] If the adhesive composition for tire cords includes a low content of alicyclic polyurethane resin compared to epoxy compounds, the adhesive properties and fatigue properties may be deteriorated, and the adhesive properties may be significantly deteriorated. If the adhesive composition for tire cords includes an excessive content of alicyclic polyurethane resin compared to epoxy compounds, the concentration of the adhesive composition for tire cords may be significantly increased, and therefore, sludge may be generated or gel may be generated during the application of the adhesive composition, and appearance defects of the product may be generated.

[0040] Meanwhile, the adhesive composition for a tire cord may satisfy a viscosity within a range of 2.50 to 2.85 measured using an Ubbelohde viscometer at room temperature.

[0041] "Room temperature" is a state in which the temperature is not particularly increased or decreased, and for example, it may refer to a temperature in the range of 15° C. to 30° C. Specifically, within the above temperature range, the room temperature may be a temperature of 17° C. or more, 19° C. or more, 21° C. or more, or 23° C. or more and 29° C. or less or 27° C. or less.

[0042] Also, throughout the specification, unless otherwise specified, the temperature at which evaluation of numerical properties is performed may be room temperature.

[0043] Specifically, the lower limit of the viscosity of the adhesive composition can be, for example, 2.51 or more, 2.52 or more, 2.53 or more, 2.54 or more, 2.55 or more, 2.56 or more, 2.57 or more, 2.58 or more, 2.59 or more, 2.60 or more, 2.61 or more, 2.62 or more, 2.63 or more, 2.64 or more, 2.65 or more, 2.66 or more, 2.67 or more, 2.68 or more, 2.69 or more, or 2.70 or more.

[0044] Furthermore, the upper limit of the viscosity of the adhesive composition may be, for example, 2.84 or less, 2.83 or less, 2.82 or less, 2.81 or less, 2.80 or less, 2.79 or less, 2.78 or less, 2.77 or less, 2.76 or less, 2.75 or less, 2.74 or less, 2.73 or less, 2.72 or less, or 2.71 or less.

[0045] In the case where the adhesive composition for a tire cord satisfies the above-mentioned viscosity range, as shown in the following test, an optimum pick up rate may be ensured, processability and productivity may be improved, and excellent adhesive strength may be provided.

[0046] In particular, it has been confirmed that when water (H2O) is used instead of an organic solvent as a dispersion medium for an adhesive composition or each component contained in the composition, the viscosity of the adhesive composition may decrease and sufficient adhesive strength may not be ensured in consideration of the risk of fire, harm to the human body, and dispersibility of other components of the composition.

[0047] The epoxy compound functions as a curing agent, thereby forming a three-dimensional network structure when the adhesive is heat-treated, and imparting adhesive strength and layer stability to a coating layer formed from the adhesive composition.

[0048] Assuming that the viscosity range of the total composition described above is met, the type of epoxy compound contained in the adhesive composition is not particularly limited. For example, glycidyl ether compounds such as diethylene glycol-diglycidyl ether, polyethylene glycol-diglycidyl ether, polypropylene glycol-diglycidyl ether, neopentyl glycol-diglycidyl ether, 1,6-hexanediol-diglycidyl ether, glycerol-polyglycidyl ether, trimethylolpropane-polyglycidyl ether, polyglycerol-polyglycidyl ether, pentaerythritol-polyglycidyl ether, diglycerol-polyglycidyl ether and sorbitol-polyglycidyl ether can be used; linear phenolic epoxy resins such as phenol linear phenolic epoxy resins or cresol linear phenolic epoxy resins; and bisphenol-type epoxy resins such as bisphenol A type epoxy resins or bisphenol F type epoxy resins can be used.

[0049] Also, provided that the viscosity range of the total composition described above is satisfied, known or commercially available epoxy compounds may be used. For example, as the epoxy compound, EX614B from Nagase, KETL6000 from Kolon, CL16 from Ipox Chemicals, or GE500 from Raschig may be used.

[0050] The epoxy equivalent (g / EQ) of the commercially available sorbitol polyglycidyl ether suggested above may be 120 to 300 g / eq, and if the equivalent of the sorbitol polyglycidyl ether is less than 120, the polymerization unit of the epoxy resin may be small, and thus it may be difficult to form a network structure between isocyanates. Also, if the equivalent of the sorbitol polyglycidyl ether is greater than 300, the epoxy amount per unit molecule may be relatively insufficient, and thus, the adhesive strength may be deteriorated.

[0051] The adhesive composition for a tire cord may include 0.1 wt % to 10 wt % of the epoxy compound.

[0052] The latex contained in the adhesive composition for a tire cord is a component used in consideration of the use of the composition.

[0053] Specifically, the adhesive composition can be used for adherend components such as rubber compounds, rubber structures or rubber reinforcements, and in the case of using latex, it can be beneficial to ensure affinity, compatibility or bonding strength with the adherend. Depending on the circumstances, the latex component included in the adhesive composition can be the same as the rubber component of the adherend.

[0054] According to an example, the latex may not contain resorcinol-formaldehyde or components derived therefrom. That is, the adhesive composition may be an RF-free composition. Therefore, compared with the prior art using RF latex, an environmentally friendly adhesive composition that is harmless to the human body can be provided. In addition, the use of such an adhesive composition has the advantage of reducing subsequent management and subsequent processing costs.

[0055] There is no particular limitation on the kind of latex that can be used in the adhesive composition, as long as it does not contain resorcinol-formaldehyde or a component derived therefrom and satisfies the viscosity of the total composition as described above.

[0056] According to an example, as the latex, natural rubber latex, vinyl-pyridine-styrene-butadiene copolymer latex (VP latex), styrene-butadiene copolymer latex, acrylate copolymer latex, butyl rubber latex, chloroprene rubber latex or their modified latex can be used. For the modified latex, the method for modifying the latex or the specific type of the latex is not limited. For example, a modified latex obtained by modifying a vinyl-pyridine-styrene-butadiene copolymer with a carboxylic acid or the like can be used.

[0057] Commercially available latexes can also be used as long as the viscosity of the total composition described below can be satisfied. For example, as VP latex, commercial products such as LM-60 from Denaka, VP-150 from APCOTEX, VB-1099 from Nippon A&L, or 5218 or 0653 from Closlen can be used.

[0058] According to one example, a latex component including one or more of the above-described latexes can be used in the adhesive composition.

[0059] According to an example, the adhesive composition for tire cord may include 1.0wt% to 30wt% of latex. When the above range is met, it may be beneficial to ensure affinity, compatibility or bonding strength with the rubber-containing adherend to which the adhesive composition is used.

[0060] According to one example, the latex, while dissolved in a solvent (water or an organic solvent), can be mixed with the other components of the composition.

[0061] The amine compound included in the adhesive composition for a tire cord functions as a curing agent. Due to the curing or accelerated curing caused by the amine compound, a stable coating layer can be formed.

[0062] In the adhesive composition for tire cord, considering the viscosity drop caused by using an alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000 and a solvent (water), one or more amine compounds may be used. Specifically, the adhesive composition may include an amine compound having at least a chain structure.

[0063] According to one example, the amine compound having a chain structure may be a compound derived from the reaction of ethylenediamine and stearic acid. Here, the carbon number of the amine compound may be 8 to 20 (product name: Acrawax from Lonza TM C Dispersion liquid). The amine compound may be present in a solid state or a liquid state, and in the case where it is present in a solid state, a solvent for dispersing it into a liquid may be used.

[0064] In addition, the type of the amine compound is not particularly limited, and according to one example of the present invention, an amine compound that can be used as a curing agent can be used as the amine compound without limitation. As the amine compound, for example, at least one of alicyclic amine, aliphatic amine and aromatic amine can be used.

[0065] More specifically, according to one example of the present invention, piperazine from DAEJUNG, G640 from Kukdo Chemical, HK511 from Huntsman Corporation, and the like may be used as the amine compound.

[0066] Considering the curing acceleration effect of the adhesive composition for a tire cord, the weight ratio of the amine compound having a chain structure to the alicyclic amine compound may be 1:1 to 3:1 or 7:1.

[0067] The adhesive composition for a tire cord may include 0.1 wt % to 10 wt % of the amine compound.

[0068] The adhesive composition for a tire cord may include water (H2O).

[0069] Specifically, considering the hazards to human body and the risk of fire, the adhesive composition for tire cord uses water as a solvent instead of an organic solvent (such as toluene or ethanol). That is, the adhesive composition for tire cord can be a water-based composition or an aqueous composition.

[0070] According to one example, the water used as a solvent in the adhesive composition may be demineralized water.

[0071] According to an example, based on the total weight of the composition whose viscosity is measured, the content of water may be 50 wt% or more, or 65 wt% or more. Specifically, the lower limit of the content of water may be, for example, 70 wt% or more, 75 wt% or more, or 80 wt% or more. And, the upper limit of the content of water may be, for example, 95 wt% or less, 85 wt% or less, or 75 wt% or less. When the above range is met, each component constituting the composition may be fully dispersed in the solvent.

[0072] According to one example, the content of water in the total composition may refer to the content of water mixed as a solvent.

[0073] According to one example, the content of water in the total composition may include not only the content of water mixed as a solvent but also the content of water mixed in other components, such as water used to disperse the alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000.

[0074] Meanwhile, the adhesive composition for tire cords may further include one or more cross-linking agents selected from isocyanate compounds, aziridine compounds and metal chelate compounds.

[0075] The kind of the cross-linking agent for imparting adhesive strength and cohesive strength is not particularly limited, and common compounds such as isocyanate compounds, aziridine compounds, epoxy compounds, and metal chelate compounds can be used.

[0076] The adhesive composition for a tire cord may include the cross-linking agent in an amount of about 1 wt % to about 20 wt %.

[0077] When the adhesive is heat-treated, the cross-linking agent forms a three-dimensional network structure, thereby imparting adhesive strength and layer stability to a coating layer formed from the adhesive composition.

[0078] The type of isocyanate is not particularly limited, but the type of isocyanate can be selected in consideration of the viscosity range of the total composition as described above. For example, as the isocyanate, a compound containing an alicyclic group, i.e., an alicyclic isocyanate, can be used. Compared with non-aromatic polyisocyanates, aromatic polyisocyanates can ensure a high reaction rate, and therefore, they can be conducive to improving the low viscosity of the aqueous composition.

[0079] According to one example, the aryl group included in the isocyanate compound may be a phenyl group, and as the isocyanate compound including such an aryl group, for example, methylene diphenyl polyisocyanate or polymethylene polyphenyl polyisocyanate may be used.

[0080] According to one example, the isocyanate compound can be a blocked isocyanate. The blocked isocyanate compound can be prepared by adding a known blocking agent to a polyisocyanate compound. As such a blocking agent, the following compounds can be used: for example, phenols such as phenol, thiophenol, chlorophenol, cresol, resorcinol, p-sec-butylphenol, p-tert-butylphenol, p-sec-amylphenol, p-octylphenol, p-nonylphenol; secondary or tertiary alcohols such as isopropanol and tert-butyl alcohol, etc.; aromatic secondary amines such as diphenylamine and dimethylaniline, etc.; phthalimide; lactams such as δ-valerolactam, etc.; caprolactams such as ε-caprolactam; active methylene compounds such as dialkyl malonate, acetylacetone and alkyl acetoacetate, etc.; oximes such as acetone oxime, methyl ethyl ketone oxime and cyclohexanone oxime, etc.; basic nitrogen compounds such as 3-hydroxypyridine, and acidic sodium sulfite, etc.

[0081] More specifically, commercially available water-dispersible blocked isocyanate products, such as IL-6 from EMS, DM-6500 from MEISEIChemical, etc., can be used as the isocyanate.

[0082] And, provided that the viscosity range of the above-mentioned total composition is met, known or commercially available isocyanate compounds can be used. For example, commercially available water-dispersible blocked isocyanate products such as IL-6 from EMS or DM-6500 from MEISEI Chemical can be used.

[0083] Meanwhile, according to another embodiment of the present invention, there is provided a tire cord including: a fiber base; and an adhesive layer formed on the fiber base, and the adhesive layer is formed of the adhesive composition according to one embodiment.

[0084] For the detailed description of the adhesive composition for a tire cord according to the above-mentioned embodiment, the above-mentioned description applies.

[0085] The adhesive composition for tire cord does not contain resorcinol-formaldehyde or its derived components, so it is environmentally friendly, and it can significantly improve the bonding strength or heat-resistant bonding strength between tire rubber and tire cord, so it has high bonding strength or heat-resistant bonding strength to tire rubber, and can improve the durability of the tire. And, according to the present disclosure, a tire including the above tire cord is provided.

[0086] Although the specific use of the tire cord is not limited, since the adhesive layer is included, higher adhesion with the hybrid cord can be achieved, and it can be applied to large tires requiring higher heat-resistant adhesion.

[0087] According to another embodiment of the present invention, there is provided a tire cord, comprising: a fiber base; and an adhesive layer formed on the fiber base, wherein the adhesive layer comprises an epoxy compound, a latex, an alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000, and an amine compound.

[0088] The adhesive composition for tire cord does not contain resorcinol-formaldehyde or its derived components, so it is environmentally friendly, and it can significantly improve the bonding strength or heat-resistant bonding strength between tire rubber and tire cord, so it has high bonding strength or heat-resistant bonding strength to tire rubber, and can improve the durability of the tire. And, according to the present disclosure, a tire including the above tire cord is provided.

[0089] The alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000 may include a reaction product between polyisocyanate including one or more alicyclic groups having a carbon number of 4 to 30 and polyol.

[0090] The alicyclic polyurethane resin may include 1 mol % to 20 mol % of a moiety derived from one or more compounds selected from dimethylolbutanoic acid and dimethylolpropionic acid.

[0091] The fiber base may be a raw cord including polyester fibers.

[0092] Although the specific use of the tire cord is not limited, since the adhesive layer is included, higher adhesion with the hybrid cord can be achieved, and it can be applied to large tires requiring higher heat-resistant adhesion.

[0093] Meanwhile, according to still another embodiment of the present invention, a tire including the above tire cord is provided.

[0094] The pneumatic tire may include: a tread portion; a pair of shoulder portions, respectively extending around the tread portion to both sides; a pair of sidewall portions, extending to respective shoulder portions; a pair of bead portions, respectively extending to respective sidewall portions; a carcass layer formed inside the tread portion, the shoulder portion, the sidewall portion and the bead portion; a cord located inside the carcass layer; a belt portion located between the inner surface of the tread portion and the carcass layer; and an inner liner bonded to the inner side of the carcass layer.

[0095] Beneficial Effects

[0096] According to the present disclosure, an environmentally friendly adhesive composition for tire cord can be provided, which can significantly improve the bonding strength and heat-resistant bonding strength between tire rubber and tire cord; a tire cord can be provided, which has high bonding strength and heat-resistant bonding strength with tire rubber, thereby improving the durability of the tire; and a tire including the above-mentioned tire cord can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 Schematic diagram showing the Ubbelohde viscometer used in Test Example 1. DETAILED DESCRIPTION

[0098] The present invention will be described in more detail in the following examples. However, these examples are provided only to illustrate the present invention, and the scope of the present invention is not limited thereto.

[0099] [Examples and Comparative Examples: Adhesive Composition for Tire Cord and Preparation of Tire Cord]

[0100] Example 1

[0101] (1) Synthesis of water-dispersible polyurethane resin

[0102] Polyester polyol (weight average molecular weight: 2000), diol (1,6-hexanediol) and dimethylolbutyric acid (DMBA) were introduced at the molar ratios shown in Table 1 below and mixed at 75±5° C. and atmospheric pressure for 4 hours.

[0103] Then, 4,4'-dicyclohexylmethane diisocyanate (H 12 MDI) was added to the mixture and reacted for 2 hours to prepare an alicyclic polyurethane prepolymer.

[0104] The reaction temperature of the prepolymer prepared above was lowered to 60° C., and a neutralizing agent (triethanolamine, TEA) was introduced into a solvent (acetone) for dispersion. Here, a stirrer was used for dispersion, and the RPM of the stirrer was maintained at 1000 to 1500. After the dispersion was completed, the prepolymer was decompressed to remove acetone.

[0105] Distilled water was introduced into the neutralized prepolymer so that the solid content became 60%. Then, a chain extender (ethylenediamine, EDA) was added to prepare a water-dispersed alicyclic polyurethane (weight average molecular weight: 308,000 g / mol).

[0106] (2) Preparation of adhesive composition for tire cord

[0107] The components were mixed in the content ratios (wt %) as shown in Table 4 below, and stirred at a temperature of about 20° C. for 24 hours to prepare compositions of Examples and Comparative Examples.

[0108] (3) Preparation of tire cord

[0109] Two primary twist yarns 111 and 112 (Z direction) with a twist number of 360 TPM were prepared using polyester yarn, and then the two primary twist yarns 111 and 112 were twisted together with a twist number of 360 TPM to obtain a plied yarn (1650 dtex / 2 strands). The plied yarn prepared in this way was used as the original cord 110.

[0110] The original cord 110 composed of polyester was immersed in the first coating solution and then treated at a drying temperature of 150° C. and a curing temperature of 240° C. for 1 minute to form a first coating layer 211 , thereby providing the original cord 110 with reactive groups.

[0111] Then, in order to provide the adhesive composition to the original cord 110 on which the first coating layer 211 is formed, the original cord 110 on which the first coating layer 211 is formed is dipped in the second coating solution, and then dried and cured. Here, drying and curing are performed by treating at a drying temperature of 150° C. and a curing temperature of 235° C. for 1 minute, respectively. The first coating solution dipping process and the second coating solution dipping process are performed continuously, wherein the tension is 0.5 g / d. Thus, the tire cord 201 is prepared in the form of a dipped cord.

[0112] Examples 2 to 10

[0113] (1) Synthesis of water-dispersible polyurethane resin

[0114] A water-dispersed alicyclic polyurethane was prepared by the same method as in Example 1, except that the molar ratio of the components used was changed as shown in Table 1 or Table 2 below.

[0115] (2) Preparation of adhesive composition for tire cord

[0116] The components were mixed in the content ratio (wt %) as shown in Table 4 or Table 5 below, and stirred at a temperature of about 20° C. for 24 hours to prepare each composition.

[0117] (3) Preparation of tire cord

[0118] A tire cord was prepared by the same method as in Example 1 except that the adhesive composition for the tire cord was changed.

[0119] Comparative Examples 1 to 5

[0120] (1) Synthesis of water-dispersible polyurethane resin

[0121] A water-dispersed alicyclic polyurethane was prepared by the same method as in Example 1, except that the molar ratios of the components used were changed as shown in Table 3 below.

[0122] Here, the weight average molecular weights of the water-dispersible alicyclic polyurethane resins used in Comparative Examples 1 to 4, respectively, are as shown in Table 3, and in Comparative Example 5, methylene diphenyl diisocyanate (MDI) aromatic diisocyanate was used instead of 4,4'-dicyclohexylmethane diisocyanate.

[0123] (2) Preparation of adhesive composition for tire cord

[0124] The components were mixed in the content ratios (wt %) as shown in Table 6 below, and stirred at a temperature of about 20° C. for 24 hours to prepare each composition.

[0125] (3) Preparation of tire cord

[0126] A tire cord was prepared by the same method as in Example 1 except that the adhesive composition for the tire cord was changed.

[0127] [Table 1]

[0128] (Unit: molar ratio) Example 1 Example 2 Example 3 Example 4 Example 5 (A) Polyester polyol 1 0.5 2 1 1 (B) Diol 0.2 0.2 0.2 1 2 (C)DMBA 0.8 0.8 0.8 0.8 0.8 <![CDATA[(D)H 12 MDI]]> 2 2 2 2 2 (E)EDA 1 1 1 1 1 (F)TEA 7 7 7 7 7 Mw(g / mol) 308,000 286,000 346,000 316,000 322,000

[0129] [Table 2]

[0130] (Unit: molar ratio) Example 6 Example 7 Example 8 Example 9 Example 10 (A) Polyester polyol 1 1 1 1 1 (B) Diol 6 8 0.2 0.2 0.2 (C)DMBA 0.8 0.8 3 0.8 0.8 <![CDATA[(D)H 12 MDI]]> 2 2 2 2 2 (E)EDA 1 1 1 4 1 (F)TEA 7 7 7 7 5 Mw(g / mol) 337000 342000 299000 319000 299000

[0131] [Table 3]

[0132] (Unit: molar ratio) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 (A) Polyester polyol 0.1 2.5 1 1 1 (B) Diol 0.2 0.2 0 12 0.2 (C)DMBA 0.8 0.8 0.8 0.8 0.8 <![CDATA[(D)H 12 MDI]]> 2 2 2 2 - (D)MDI - - - - 2 (E)EDA 1 1 1 1 1 (F)TEA 7 7 7 7 7 Mw(g / mol) 231000 364000 217000 379000 315000

[0133] [Table 4]

[0134] (Unit: wt%) Example 1 Example 2 Example 3 Example 4 Example 5 (A) Latex 14.7 14.7 14.7 14.7 14.7 (B) Water-dispersible polyurethane 1.5 1.5 1.5 1.5 1.5 (C) Amine compounds 1.8 1.8 1.8 1.8 1.8 (D) Chain Extender 0.4 0.4 0.4 0.4 0.4 (E) Epoxy compounds 1.7 1.7 1.7 1.7 1.7 (F) Isocyanate 3.4 3.4 3.4 3.4 3.4 (G) Solvent 76.5 76.5 76.5 76.5 76.5 TSC 23.5 23.5 23.5 23.5 23.5

[0135] [Table 5]

[0136] (Unit: wt%) Example 6 Example 7 Example 8 Example 9 Example 10 (A) Latex 14.7 14.7 14.7 14.7 14.7 (B) Water-dispersible polyurethane 1.5 1.5 1.5 1.5 1.5 (C) Amine compounds 1.8 1.8 1.8 1.8 1.8 (D) Chain Extender 0.4 0.4 0.4 0.4 0.4 (E) Epoxy compounds 1.7 1.7 1.7 1.7 1.7 (F) Isocyanate 3.4 3.4 3.4 3.4 3.4 (G) Solvent 76.5 76.5 76.5 76.5 76.5 TSC 23.5 23.5 23.5 23.5 23.5

[0137] [Table 6]

[0138]

[0139] <Description of Tables 4 to 6>

[0140] (A) Latex: VP latex 0653 from Closlen

[0141] (C) Amine compound: Acrawax from Lonza TM C dispersion (D) chain extender: piperazine

[0142] (E) Epoxy compound: EX614B from NAGASE (sorbitol polyglycidyl ether, epoxy content: 167 g / eq, viscosity (mPa·s): 21,200)

[0143] (F) Isocyanate: IL-6 from EMS

[0144] (G) Solvent: demineralized water

[0145] TSC: Total Solid Content

[0146] [Test example]

[0147] Test Example 1: Measurement of Viscosity of Compositions of Examples and Comparative Examples

[0148] The viscosity of each composition of Examples and Comparative Examples prepared above was measured at room temperature (about 25° C.) using an Ubbelohde viscometer.

[0149] The composition was placed in a constant temperature water tank (about 25° C.) for 30 minutes and then measured using an Ubbelohde viscometer. Specifically, by the following process, a certain amount of softened water was added to the Ubbelohde viscometer and the viscosity properties of the softened water were measured, and the viscosity properties of the composition were measured by the same method, and then the relative viscosity was calculated based on the measured viscosity properties of the softened water.

[0150] The specific measurement method of viscosity is as follows, and the measurement results are shown in Table 7.

[0151] (1) Introduce the sample (composition or demineralized water) into tube A of the Ubbelohde viscometer.

[0152] (2) After setting a constant temperature water bath at 25°C, fix it so that part C is immersed in the water bath and leave it for 30 minutes.

[0153] (3) Use a pipette to position the sample in the middle of section C.

[0154] (4) The sample flows downward, and the time from when the sample liquid level passes through the upper scale line of B until the sample liquid level passes through the lower scale line of B is measured.

[0155] (5) The measured time is applied to the relative viscosity calculation formula to calculate the relative viscosity.

[0156] <Relative viscosity calculation formula>:

[0157] T1 / T0

[0158] T1: The time from when the composition passes the upper scale line of B until the composition passes the lower scale line of B T0: The time from when the softened water passes the upper scale line of B until the softened water passes the lower scale line of B Test Example 2: Evaluation of Adhesion Strength

[0159] For each tire cord prepared in the examples and comparative examples, in order to evaluate the adhesive strength per unit area, the adhesive peel strength of the tire cord was measured according to ASTM D4393. Specifically, a rubber sheet having a thickness of 0.6 mm, a cord layer, and a rubber sheet having a thickness of 0.6 mm were sequentially stacked to prepare a test specimen, which was then subjected to a 170°C, 60 kg / cm 2 The test specimens were prepared by vulcanizing under a pressure of 1000 g for 15 minutes.

[0160] Then, the vulcanized sample was cut to prepare a sample with a width of 1 inch. For the prepared sample, the peel strength was tested at 25°C and a speed of 125 mm / min using a universal testing machine (Instron) to measure the adhesive strength of the tire cord. Here, the average value of the load generated during the peeling process was evaluated as the adhesive strength. The adhesive strength was evaluated and summarized in Table 7 below.

[0161] Test Example 3: Evaluation of thermal fatigue resistance

[0162] For each tire cord prepared in Examples and Comparative Examples, fatigue resistance of each composition of Examples and Comparative Examples was measured.

[0163] Specifically, a rubber sheet with a thickness of 0.6 mm, a cord layer, a rubber sheet with a thickness of 0.6 mm, a cord layer, and a rubber sheet with a thickness of 0.6 mm were sequentially stacked to prepare a test piece, and then, the test piece was heated at 170° C. and 60 kg / cm 2 The specimens were vulcanized under a pressure of 100°C for 15 minutes to prepare the specimens. Then, the vulcanized specimens were cut to prepare specimens having a width of 1 inch. The fatigue properties of the prepared specimens can be evaluated by observing the adhesion strength of the rubber compound to the tire cord and the interface of the unflexed portion and the flexed portion of the tire cord mat specimen.

[0164] In the fatigue tester, a specimen with a width of 1 inch was attached and then preheated at 100°C for 30 minutes. Then, the tester condition of 100,000 cycles at 180 rpm and a load of 60 kg was established, and a 1-inch flexing roller was used. After the fatigue evaluation was completed, the specimen was taken out of the tester and left at room temperature for 12 hours, and then a peel strength test was performed using a universal testing machine (Instron) at 25°C and 125 mm / min.

[0165] Thermal fatigue resistance was measured according to the following Formula 1, and the results are shown in Table 7 below.

[0166] [Formula 1]

[0167] Fatigue (%) = (measurement result of adhesive strength for the flexed portion) * 100 / (measurement result of adhesive strength for the unflexed portion)

[0168] [Table 7]

[0169] Viscosity (RV) Adhesion strength (%) Thermal fatigue resistance (%) Example 1 2.71 100 100 Example 2 2.64 97 100 Example 3 2.82 97 98 Example 4 2.73 100 99 Example 5 2.76 100 95 Example 6 2.79 100 95 Example 7 2.81 100 99 Example 8 2.74 100 100 Example 9 2.54 100 97 Example 10 2.60 99 98 Comparative Example 1 2.41 75 72 Comparative Example 2 2.88 75 79 Comparative Example 3 2.44 72 81 Comparative Example 4 2.89 76 80 Comparative Example 5 2.92 77 79

[0170] As shown in Table 7, it was confirmed that the adhesive composition for tire cord of the Example had a viscosity ranging from 2.50 to 2.85 and, when applied, could improve the bonding strength of the tire cord to the carcass layer and ensure excellent heat-resistant bonding strength and heat fatigue resistance.

[0171] In contrast, it was confirmed that when the adhesive composition for a tire cord of the comparative example was applied, sufficient adhesive strength of the tire cord to the carcass layer could not be ensured, and the heat-resistant adhesive strength and heat fatigue resistance were relatively low.

Claims

1. An adhesive composition for tire cord, comprising: 0.1 wt % to 10 wt % of an epoxy compound; 1 wt % to 30 wt % of latex; 0.5 wt % to 10 wt % of an alicyclic polyurethane resin having a weight average molecular weight (Mw) of 250,000 to 350,000; 0.1 wt % to 10 wt % of an amine compound; and 50wt% to 95wt% water, in, The alicyclic polyurethane resin comprises a reaction product between a polyisocyanate and a polyol, wherein the polyisocyanate comprises one or more alicyclic groups having a carbon number of 4 to 30, The viscosity of the adhesive composition measured at room temperature using an Ubbelohde viscometer is in the range of 2.50 to 2.

85.

2. The adhesive composition for tire cord according to claim 1, wherein The alicyclic polyurethane resin is a water-dispersed alicyclic polyurethane resin formed of an alicyclic polyurethane ionomer.

3. The adhesive composition for tire cord according to claim 1, wherein The cycloaliphatic polyurethane resin includes 1 mol % to 20 mol % of a moiety derived from one or more compounds selected from dimethylolbutanoic acid and dimethylolpropionic acid.

4. The adhesive composition for tire cord according to claim 1, wherein The amine compound includes an amine compound having a chain structure.

5. The adhesive composition for tire cord according to claim 1, wherein The adhesive composition for tire cords further comprises one or more cross-linking agents selected from isocyanate compounds, aziridine compounds and metal chelate compounds.

6. A tire cord comprising: Fiber substrate; and An adhesive layer is formed on the fiber substrate, and the adhesive layer is formed from the adhesive composition according to claim 1.

7. The tire cord according to claim 6, wherein The fiber base is raw cords including polyester fibers.

8. A tire comprising the tire cord according to claim 6.

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