Method for manufacturing core wire for transmission belt and kit for treatment

Abstract

To manufacture a core wire for a transmission belt exhibiting high adhesive strength even to a rubber composition for a transmission belt containing various rubber components, even when an aqueous treatment agent which does not substantially contain resorcin, formaldehyde and a bisphenol A type epoxy resin is used.SOLUTION: A core wire is obtained by treating a first treated yarn obtained by treating an untreated yarn of a core wire for a transmission belt with a first treatment agent (A) containing a first aliphatic polyfunctional epoxy compound (A1), first block polyisocyanate (A2) and a first vinylpyridine-diene-based copolymer (A3), with a second treatment agent (B) containing a second aliphatic polyfunctional epoxy compound (B1), second block polyisocyanate (B2), a second vinylpyridine-diene-based copolymer (B3) and a reactive compatibilizing agent (B4), and heating the treated first treated yarn at a specific temperature.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a core wire for a transmission belt and a treatment kit for forming an adhesive layer between fibers and on the surface of a cord by a two-bath treatment of an aqueous treatment agent substantially free of resorcinol, formaldehyde, and bisphenol A type epoxy resin.

Background Art

[0002] For the adhesion treatment of polyester fiber cords used as core wires in transmission belts, a three-bath treatment with an organic solvent-based primer (first treatment agent) mainly composed of bisphenol A type epoxy resin or polymeric MDI (polymethylene polyphenyl polyisocyanate), an RFL (second treatment agent) obtained by mixing resorcinol, formaldehyde, and latex, and a rubber paste (third treatment agent) in which a rubber composition is dissolved or dispersed in an organic solvent is generally used.

[0003] Bisphenol A type epoxy resin is a general-purpose epoxy resin produced by the condensation reaction of bisphenol A (BPA) and epichlorohydrin. In recent years, due to concerns about the adverse effects of bisphenol A on the environment and the human body, there has been a movement to restrict the use of bisphenol A. Similarly, for resorcinol, formaldehyde, and organic solvents (mainly toluene and methyl ethyl ketone), a reduction in the amount of use is also required, and a method for manufacturing a core wire for a transmission belt with reduced use of these substances is demanded.

[0004] In response to such demands, in the field of tires formed of a composite of a fiber material and rubber, similar to transmission belts, the following have been proposed as adhesion treatment agents for fiber materials forming carcasses (tire cords).

[0005] International Publication No. 2017 / 122964 (Patent Document 1) discloses an adhesion treatment of a polyester fiber cord with a first treatment agent containing a blocked isocyanate and an epoxy compound, and a second treatment agent containing a phenolic epoxy resin and maleic anhydride-modified polybutadiene. Further, as the phenolic epoxy resin, a reaction product of bisphenol A and epichlorohydrin is exemplified.

[0006] International Publication No. 2020 / 178186 (Patent Document 2) discloses an aqueous treatment agent that essentially contains a rubber latex, a blocked isocyanate, and a filler, optionally contains an epoxy group-containing compound and a polymer having a carboxylic acid functional group, and substantially does not contain resorcinol and formaldehyde. Further, as the epoxy group-containing compound, a glycerol-based polyglycidyl ether is preferred, and as the polymer having a carboxylic acid functional group, an acrylic resin is preferred.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, it is difficult to say that the treating agent disclosed in Patent Document 1 is an environmentally friendly treating agent because it contains bisphenol A type epoxy resin, and it did not satisfy the adhesive strength at high temperatures or the adhesive strength with rubber compositions other than NR / SBR (a mixture of natural rubber and styrene-butadiene rubber). The treating agent disclosed in Patent Document 2 also did not satisfy the adhesive strength with rubber compositions other than NR / SBR, and it also lacked the flexural fatigue resistance (toughness of the adhesive film) required for a transmission belt in which large deformations (bending due to winding around a small-diameter pulley and straight-line deformation) are repeated as compared with a tire.

[0009] Therefore, an object of the present invention is to provide a method for manufacturing a core wire for a transmission belt and a treating kit that exhibit high adhesive strength (particularly, adhesive strength at high temperatures) not only with NR / SBR but also with rubber compositions for transmission belts containing various rubber components such as CR (chloroprene rubber), even when using an aqueous treating agent that substantially does not contain resorcinol, formaldehyde, and bisphenol A type epoxy resin.

[0010] Another object of the present invention is to provide a method for easily or efficiently manufacturing a core wire for a transmission belt that exhibits high adhesive strength.

Means for Solving the Problems

[0011] As a result of intensive studies to achieve the above object, the present inventors treated an untreated yarn of a cord for a transmission belt with a first treating agent (A) containing a first aliphatic polyfunctional epoxy compound (A1), a first blocked polyisocyanate (A2), and a first vinylpyridine-diene copolymer (A3) to obtain a first treated yarn, and then treated the first treated yarn with a second treating agent (B) containing a second aliphatic polyfunctional epoxy compound (B1), a second blocked polyisocyanate (B2), a second vinylpyridine-diene copolymer (B3), and a reactive compatibilizer (B4), and then heated the treated yarn at a specific temperature. As a result, it was found that a cord having high adhesion strength can be produced not only for a rubber composition for a transmission belt containing NR / SBR but also for a rubber composition for a transmission belt containing various rubber components such as CR even when using an aqueous treating agent substantially free of resorcinol, formaldehyde, and bisphenol A type epoxy resin, and the present invention was completed.

[0012] That is, the present invention includes the following aspects.

[0013] Aspect [1]: A first treatment step of treating an untreated yarn of a cord for a transmission belt with a first treating agent (A) containing a first aliphatic polyfunctional epoxy compound (A1), a first blocked polyisocyanate (A2), and a first vinylpyridine-diene copolymer (A3) to obtain a first treated yarn; A second treatment step of treating the first treated yarn with a second treating agent (B) containing a second aliphatic polyfunctional epoxy compound (B1), a second blocked polyisocyanate (B2), a second vinylpyridine-diene copolymer (B3), and a reactive compatibilizer (B4) to obtain a second treated yarn; A heat treatment step of heating the second treated yarn at a temperature equal to or higher than the dissociation temperature of the first blocked polyisocyanate (A2) and the second blocked polyisocyanate (B2), A method for producing a cord for a transmission belt, wherein the first treating agent (A) and the second treating agent (B) do not contain resorcinol, formaldehyde, bisphenol A, and reaction products thereof.

[0014] Aspect [2]: The first treating agent (A) and the second treating agent (B) are aqueous treating agents containing a hydrophilic solvent. In the first treatment step, after immersing the untreated yarn in the first treatment agent (A), it is dried, The production method according to the above-mentioned aspect [1], wherein in the second treatment step, after immersing the first treated yarn in the second treatment agent (B), it is dried.

[0015] Aspect [3]: The production method according to the above-mentioned aspect [1] or aspect [2], wherein the epoxy equivalent weights of the first aliphatic polyfunctional epoxy compound (A1) and the second aliphatic polyfunctional epoxy compound (B1) are each 200 g / eq. or less.

[0016] Aspect [4]: The production method according to any one of the above-mentioned aspects [1] to [3], wherein the dissociation temperatures of the first blocked polyisocyanate (A2) and the second blocked polyisocyanate (B2) are each 160 to 250 °C, and the blocking agent is lactams.

[0017] Aspect [5]: The production method according to any one of the above-mentioned aspects [1] to [4], wherein the reactive compatibilizer (B4) contains an acid-modified diene polymer.

[0018] Aspect [6]: The proportion of the first vinylpyridine-diene copolymer (A3) is 5 to 30% by mass in the solid content of the first treatment agent (A), the proportion of the second vinylpyridine-diene copolymer (B3) is 10 to 90% by mass in the solid content of the second treatment agent (B), The production method according to any one of the above-mentioned aspects [1] to [5], wherein the proportion of the reactive compatibilizer (B4) is 0.5 to 20% by mass in the solid content of the second treatment agent (B).

[0019] Aspect [7]: The production method according to any one of the above-mentioned aspects [1] to [6], wherein the second treatment agent (B) contains the same or a similar rubber (B5) as the rubber of the transmission belt (adhered rubber) in contact with the core wire.

[0020] Aspect [8]: The manufacturing method according to any one of the above-mentioned Aspects [1] to [7], wherein the rubber of the transmission belt in contact with the core wire contains at least one selected from the group consisting of natural rubber, styrene-butadiene rubber, and chloroprene rubber.

[0021] Aspect [9]: The manufacturing method according to any one of the above-mentioned Aspects [2] to [8], wherein the first treatment step and the second treatment step are two-bath treatments, and the first treatment agent (A) and the second treatment agent (B) do not contain a hydrophobic organic solvent.

[0022] Aspect

[10] : The manufacturing method according to any one of the above-mentioned Aspects [1] to [9], wherein the untreated yarn is a twisted yarn cord containing polyester fibers.

[0023] Aspect

[11] : A treatment kit or set for treating an untreated yarn of a core wire for a transmission belt, comprising: a first treatment agent (A) containing a first aliphatic polyfunctional epoxy compound (A1), a first blocked polyisocyanate (A2), and a first vinylpyridine-diene copolymer (A3); and a second treatment agent (B) containing a second aliphatic polyfunctional epoxy compound (B1), a second blocked polyisocyanate (B2), a second vinylpyridine-diene copolymer (B3), and a reactive compatibilizer (B4), and the first treatment agent (A) and the second treatment agent (B) do not contain resorcinol, formaldehyde, bisphenol A, and reaction products thereof. A treatment kit or set.

[0024] Aspect

[12] : A core wire for a transmission belt obtained by the manufacturing method according to any one of the above-mentioned Aspects [1] to

[10] .

[0025] In the present application, the "epoxy compound" generally means a compound referred to as an "epoxy resin", and is used in the sense of including not only low-molecular-weight epoxy compounds but also epoxy compounds (oligomers or polymers) with relatively high molecular weights. Further, the fiber or yarn (raw yarn and / or cord (or twisted cord)) treated with the first treating agent may sometimes be simply referred to as an untreated yarn. Furthermore, the numerical range "XX to YY" means including the numerical value "XX" and the numerical value "YY", that is, it may be equal to or greater than the numerical value "XX" and equal to or less than the numerical value "YY".

Advantages of the Invention

[0026] In the present invention, the first treated yarn obtained by treating the untreated yarn of the core wire for a transmission belt with the first treating agent (A) containing the first aliphatic polyfunctional epoxy compound (A1), the first blocked polyisocyanate (A2), and the first vinylpyridine-diene copolymer (A3) is treated with the second treating agent (B) containing the second aliphatic polyfunctional epoxy compound (B1), the second blocked polyisocyanate (B2), the second vinylpyridine-diene copolymer (B3), and the reactive compatibilizer (B4), and then heated at a specific temperature. Therefore, even when using an aqueous treating agent substantially free of resorcinol, formaldehyde, and bisphenol A type epoxy resin, a core wire showing high adhesive strength (particularly, adhesive strength at high temperatures) can be produced for a rubber composition for a transmission belt containing various rubbers such as NR / SBR and CR. Furthermore, in the present invention, the process using the treating agent is a two-step process. In particular, when the treating method of the aqueous treating agent is immersion treatment, a core wire for a transmission belt showing high adhesive strength can be easily or efficiently produced by a two-bath treatment.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0028] <Method for Manufacturing Core Wire> In the present invention, the core wire is obtained by a first treatment step of treating an untreated yarn of a core wire for a transmission belt with a first treatment agent (A) containing a first aliphatic polyfunctional epoxy compound (A1), a first blocked polyisocyanate (A2), and a first vinylpyridine-diene copolymer (A3) to obtain a first treated yarn, a second treatment step of treating the first treated yarn with a second treatment agent (B) containing a second aliphatic polyfunctional epoxy compound (B1), a second blocked polyisocyanate (B2), a second vinylpyridine-diene copolymer (B3), and a reactive compatibilizer (B4) to obtain a second treated yarn, and a heat treatment step of heating the second treated yarn at a temperature equal to or higher than the dissociation temperature of the first blocked polyisocyanate (A2) and the second blocked polyisocyanate (B2). Although the details of the mechanism by which a core wire exhibiting high adhesive strength is obtained through these steps are unclear, it can be presumed as follows.

[0029] That is, on the core wire obtained by the above method, two adhesive films, namely, a first adhesive film formed by the first treatment agent (A) and a second adhesive film formed by the second treatment agent (B), are formed. Further, in the core wire, the blocking agent of the blocked polyisocyanate dissociates by the heat treatment step, and the curing and crosslinking reactions proceed.

[0030] Specifically, it is presumed that the first adhesive film becomes a film with excellent heat resistance due to the isocyanurate generated by the trimerization reaction of the isocyanate regenerated by the dissociation of the blocking agent from the first blocked polyisocyanate (A2), and the product containing an oxazolidone ring formed by the reaction of the aliphatic polyfunctional epoxy compound (A1) with the isocyanate compound or isocyanurate. At this time, since the first treatment agent does not contain a reactive compatibilizer (B4), the first vinylpyridine-diene copolymer (A3) basically does not react with epoxy groups or isocyanate groups and does not inhibit the above reaction. Therefore, it can be presumed that the crosslinking density increases and the mechanical strength of the film is improved. In addition, it can be presumed that the toughness of the film is also improved by the unreacted first vinylpyridine-diene copolymer (A3) contained in the film. In this way, an adhesive film excellent in mechanical strength, heat resistance, and toughness is formed, and it can be presumed that interfacial peeling (fiber interfacial peeling) between the fiber and the first adhesive film can be suppressed even at high temperatures.

[0031] On the other hand, since the second adhesive film contains a reactive compatibilizer (B4), the second vinylpyridine-diene copolymer (B3) reacts with both the epoxy group and hydroxyl group of the second aliphatic polyfunctional epoxy compound (B1) and the isocyanate group of the second blocked isocyanate (B2), and forms a dense and fine phase separation structure while competition between compatibilization and phase separation occurs. It can be presumed that this has the effect of suppressing cohesive failure, which is a phenomenon in which the adhesive film itself is broken and torn. Further, in the second adhesive film that comes into contact with the adherend rubber, by mixing rubber that is the same as or of the same type as the adherend rubber together with the second vinylpyridine-diene copolymer (B3), it can be presumed that interfacial peeling (rubber interfacial peeling) between the second adhesive film and the adherend rubber is suppressed.

[0032] That is, the main role of the first treating agent (A) is to penetrate between fibers and form a first adhesive film around the fibers to prevent rubbing while adhering the fibers together. It can be presumed that the main role of the second treating agent (B) is to form a second adhesive film around the first adhesive film to adhere the core wire and the adherend rubber. Therefore, the first adhesive film is preferably formed by the first treating agent that can simultaneously enhance the mechanical strength, heat resistance, and toughness important for adhesion between fibers and rubbing prevention. The second adhesive film is preferably formed by the second treating agent that is highly effective in suppressing cohesive failure important for adhesion to the adherend rubber. Further, since both the first treating agent (A) and the second treating agent (B) involve curing and crosslinking reactions of an aliphatic polyfunctional epoxy compound and an isocyanate compound, it can be presumed that a strong composite adhesive layer is formed also between the first adhesive film and the second adhesive film, and delamination between the adhesive layers of the first adhesive film and the second adhesive film can be suppressed.

[0033] The manufacturing method of the present invention as described above will be described in detail below.

[0034] [First treatment step] (Untreated yarn for the core wire of the transmission belt) Examples of the raw material fibers constituting the untreated yarn to be treated with the first treating agent (A) include natural fibers (such as cotton and hemp), regenerated fibers (such as rayon and acetate), synthetic fibers (such as polyolefin fibers like polyethylene and polypropylene, styrene-based fibers like polystyrene, fluorine-based fibers like polytetrafluoroethylene, acrylic fibers, vinyl alcohol-based fibers like polyvinyl alcohol, polyamide fibers, polyester fibers, wholly aromatic polyester fibers, aramid fibers, etc.), and inorganic fibers (such as carbon fibers and glass fibers). These fibers can be used alone or in combination of two or more.

[0035] Among these fibers, from the viewpoint of high modulus, C such as ethylene terephthalate and ethylene-2,6-naphthalate 2-4Polyester fibers having alkylene arylate as a main constituent unit [polyalkylene arylate fibers such as polyethylene terephthalate fibers (PET fibers), polyethylene naphthalate fibers (PEN fibers), polytrimethylene terephthalate fibers (PTT fibers), etc.], synthetic fibers such as aramid fibers, inorganic fibers such as carbon fibers, etc. are widely used, and from the viewpoints of economy, mechanical properties, heat resistance, etc., it is preferable to include polyester fibers, and poly C such as PET fibers 2-4 Alkylene-C 6-10 Alkylene arylate fibers are particularly preferred.

[0036] The untreated yarn for treatment with the first treating agent may be in the state of an untwisted raw yarn, but the state of a twisted yarn (untreated twisted yarn cord) obtained by adding twist to the raw yarn is preferable. In the present invention, even in the case of a twisted yarn cord, since the impregnation property into the twisted yarn cord of the first treating agent (between monofilaments and / or between multifilaments) is excellent, the adhesiveness between fibers can be improved.

[0037] In particular, it is preferable to add twist (twist) to the multifilament yarn which is the raw yarn. The twisting may be performed on one raw yarn, or may be performed after aligning a plurality of yarns (for example, about 30 yarns). For twisting, a general ring twister can be used.

[0038] In the raw yarn, the multifilament yarn preferably contains filaments of polyester fibers, and if necessary, may contain filaments of other fibers (such as aramid fibers). The proportion of the polyester fibers is 50% by mass or more (particularly 80 to 100% by mass) based on the whole multifilament yarn, and usually, the whole multifilament yarn may be composed of polyester fibers.

[0039] The multifilament yarn only needs to contain a plurality of filaments, and from the viewpoint of the durability of the transmission belt, for example, it may contain 50 to 5000 filaments, preferably 100 to 1000 filaments, more preferably 150 to 500 filaments, and most preferably 180 to 400 filaments.

[0040] The average fineness of the multifilament yarn is, for example, 300 to 3000 dtex, preferably 500 to 2000 dtex, more preferably 800 to 1500 dtex, and most preferably 1000 to 1300 dtex.

[0041] The average diameter of the filament is, for example, 5 to 50 μm, preferably 10 to 30 μm, more preferably 13 to 27 μm, and most preferably 15 to 25 μm.

[0042] The raw yarn may be a commercially available product. Examples of commercially available raw yarns include "Tetoron (registered trademark)" manufactured by Toray Industries, Inc., which is a raw yarn of polyester fiber.

[0043] The twisted yarn cord may be a twisted yarn cord (single-twisted yarn) obtained by twisting at least one raw yarn in a right twist (S twist) or a left twist (Z twist). However, from the viewpoint of strength, a twisted yarn cord obtained by twisting a plurality of raw yarns together is preferred.

[0044] The twisted yarn cord obtained by twisting a plurality of raw yarns together may be a twisted yarn cord (e.g., various twists, bobbin twists, Lang twists, etc.) obtained by using a plurality of single-twisted yarns as lower-twisted yarns and twisting them in an upper twist, or a twisted yarn cord (e.g., wall twist, etc.) obtained by aligning and twisting a single-twisted yarn and a raw yarn (untwisted yarn) together. Also, the single-twist direction (lower-twist direction) and the upper-twist direction may be either the same direction (Lang twist) or the opposite direction (various twists). Among these, from the viewpoint of excellent suppression of twist-back and flexural fatigue resistance, a two-stage twisted yarn cord (various twists or Lang twists) obtained by using a plurality of single-twisted yarns as lower-twisted yarns and twisting them in an upper twist is preferred, and a various-twist yarn (various-twist cord) is particularly preferred from the viewpoint of being able to suppress the occurrence of twist-back and kinks.

[0045] The number of the lower-twisted yarns constituting these twisted cords is, for example, 1 to 8, preferably 2 to 5, more preferably 2 to 4, and even more preferably 2 to 3. The number of twists of the lower twist may be, for example, 30 to 300 turns / m, preferably 100 to 280 turns / m, more preferably 150 to 250 turns / m, and most preferably 200 to 230 turns / m. In the lower twist, the twist coefficient (T.F.) represented by the following formula (1) can be selected from, for example, a range of about 0.01 to 10. For multifilament twists, 1 to 6 (especially 2 to 4) is preferable, and for Lang twists, 0.2 to 2 is preferable.

[0046] Twist coefficient (T.F.) = [Number of twists (turns / m) × √Total fineness (tex)] / 960 (1)

[0047] The number of upper-twisted yarns is not particularly limited and may be, for example, 2 to 5. When making a multifilament twist cord, 2 to 5 prepared lower-twisted yarns may be aligned and upper-twisted to make a multifilament twist cord. The number of twists of the upper twist is not particularly limited and may be, for example, 30 to 300 turns / m, preferably 50 to 200 turns / m, more preferably 100 to 150 turns / m, and most preferably 100 to 130 turns / m. In the upper twist, the twist coefficient (T.F.) represented by the formula (1) can be selected from, for example, a range of about 0.01 to 10. For multifilament twists, 1 to 6 (especially 2 to 4) is preferable, and for Lang twists, 2 to 5 is preferable.

[0048] The average diameter of the untreated twisted cord for the transmission belt after upper twisting is, for example, 0.2 to 3.5 mm, preferably 0.4 to 3 mm, and more preferably 0.5 to 2.5 mm.

[0049] When representing the twist configuration in a twisted cord formed by twisting together a plurality of raw yarns as (the number of aligned raw yarns during lower twisting) × (the number of aligned lower-twisted yarns during upper twisting), a twisted cord having a configuration such as 1×2, 1×3, 1×5, 2×3, 2×5, 3×3, 3×5, 6×5, 8×3 may be used.

[0050] (A) First treatment agent The first treating agent (A) contains a first aliphatic polyfunctional epoxy compound (A1), a first blocked polyisocyanate (A2), and a first vinylpyridine-diene copolymer (A3).

[0051] (A1) First aliphatic polyfunctional epoxy compound The first aliphatic polyfunctional epoxy compound (A1) is not particularly limited as long as it has an aliphatic skeleton and a plurality of epoxy groups (especially glycidyl groups), and may be an aliphatic glycidyl ether type epoxy compound (or an aliphatic glycidyl ether type epoxy resin).

[0052] The aliphatic glycidyl ether type epoxy compound may be a glycidyl ether compound of a polyol compound. The polyol compound includes alkanediols, polyalkandiols, alkanepolyols, polyalkanepolyols, etc.

[0053] Examples of the alkanediol include C such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, 1,6-hexanediol 2-10 alkanediols and the like.

[0054] Examples of the polyalkandiol include di- to hexaC alkanediols such as diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol 2-10 alkanediols.

[0055] Examples of the alkanepolyol (polyhydric alcohol or sugar alcohol) include C such as glycerol, pentaerythritol, trimethylolethane, trimethylolpropane, sorbitol 3-10 alkanetri to decaols and the like.

[0056] Examples of the polyalkane polyol include di- to octa-C such as diglycerol, dipentaerythritol, di(trimethylolpropane), triglycerol, tetraglycerol, hexaglycerol, etc. 3-10 Examples thereof include alkane polyols.

[0057] Among these polyol compounds, alkane polyols and polyalkane polyols are preferred, and C 4-8 Alkane tri- to octaols, tri- to hexa-C 3-8 Alkane polyols are more preferred.

[0058] Preferred aliphatic glycidyl ether type epoxy compounds include, for example, glycerol polyglycidyl ethers such as glycerol diglycidyl ether and glycerol triglycidyl ether; alkane polyol polyglycidyl ethers such as sorbitol tetraglycidyl ether; polyalkane polyol polyglycidyl ethers such as tetraglycerol tetraglycidyl ether, etc. Particularly preferred aliphatic glycidyl ether type epoxy compounds include, for example, C 5-7 Tri- to octaglycidyl ethers of alkane di- to heptaols, tri- to octaglycidyl ethers of di- to pentaglycerol, tetra- to hexaglycidyl ethers of dipentaerythritol, etc., and C such as sorbitol tetraglycidyl ether 5-7 Tri- to hexaglycidyl ethers of alkane tetra- to heptaols are particularly preferred.

[0059] The first aliphatic polyfunctional epoxy compound (A1) may be a commercially available product. Examples of commercially available products of the first aliphatic polyfunctional epoxy compound (A1) include, for example, "GRILBOND (registered trademark) G1701" manufactured by EMS-CHEMIE, "Denacol (registered trademark) EX-313", "Denacol EX-314", "Denacol EX-321", "Denacol EX-321L", "Denacol EX-421", "Denacol EX-512", "Denacol EX-521", "Denacol EX-612", "Denacol EX-614", "Denacol EX-614B", "Denacol EX-622", "Denacol EX-1610" manufactured by Nagase ChemteX Corporation, etc. Further, the first aliphatic polyfunctional epoxy compound (A1) may be used by diluting these commercially available products with water.

[0060] The epoxy equivalent of the first aliphatic polyfunctional epoxy compound (A1) may be 300 g / eq. or less (particularly 200 g / eq. or less), for example, 10 to 300 g / eq., preferably 50 to 250 g / eq., more preferably 100 to 200 g / eq., still more preferably 130 to 190 g / eq., and most preferably 150 to 180 g / eq. In the present invention, when the epoxy equivalent is within the above range (particularly 200 g / eq. or less), the crosslinking density with the first blocked polyisocyanate (A2) can be increased to improve the mechanical strength and heat resistance of the adhesive film.

[0061] In the present application, the epoxy equivalent is defined as "the mass of an epoxy resin containing 1 equivalent of epoxy groups" and can be measured in accordance with JIS K 7236.

[0062] The number of functional groups (epoxy groups) of the first aliphatic polyfunctional epoxy compound (A1) may be 2 or more in the molecule, but is preferably 2 to 10, more preferably 3 to 8, still more preferably 4 to 7, and most preferably 5 to 6.

[0063] The proportion of the first aliphatic polyfunctional epoxy compound (A1) is, for example, 5 to 300 parts by mass, preferably 10 to 200 parts by mass, more preferably 30 to 180 parts by mass, still more preferably 50 to 150 parts by mass, and most preferably 80 to 120 parts by mass with respect to 100 parts by mass of the first vinylpyridine-diene copolymer (A3). If the proportion of the first aliphatic polyfunctional epoxy compound (A1) is too small, the mechanical strength and heat resistance of the adhesive film may decrease. If it is too large, the heat resistance of the adhesive film may decrease.

[0064] In the present application, when components such as rubber such as vinylpyridine-diene copolymer, block polyisocyanate, surfactant, and reactive compatibilizer (each component contained in the treatment agent) are used in a form containing a solvent or the like, the proportion of the above components means the proportion of the solid content (the solute which is the active ingredient).

[0065] The proportion of the first aliphatic polyfunctional epoxy compound (A1) can be selected from the range of about 0.1 to 20% by mass in the first treatment agent (A), for example, 0.3 to 10% by mass, preferably 0.5 to 8% by mass, more preferably 1 to 5% by mass, still more preferably 2 to 4% by mass, and most preferably 2.5 to 3% by mass. If the proportion of the first aliphatic polyfunctional epoxy compound (A1) is too small, the mechanical strength and heat resistance of the adhesive film may decrease. If it is too large, the heat resistance of the adhesive film may decrease.

[0066] The proportion of the first aliphatic polyfunctional epoxy compound (A1) can be selected from the range of about 1 to 50% by mass in the solid content of the first treatment agent (A), for example, 3 to 40% by mass, preferably 5 to 35% by mass, more preferably 10 to 30% by mass, still more preferably 13 to 25% by mass, and most preferably 15 to 20% by mass.

[0067] In the present application, the "solid content" means the solute with respect to the solvent.

[0068] (A2) The first block polyisocyanate Since the isocyanate groups of the polyisocyanate compound of the first blocked polyisocyanate (A2) are protected by a blocking agent, heating can generate a plurality of free (or reactive) isocyanate groups. Therefore, even if the untreated yarn is treated with the first treating agent (A), the reaction of the first blocked polyisocyanate (blocked polyisocyanate or thermally reactive polyisocyanate) (A2) is suppressed in the first treatment step, so that the permeability of the first treating agent (A) between fibers can be improved.

[0069] In the first blocked polyisocyanate (A2), the polyisocyanate compound protected by the blocking agent may be a polyisocyanate or a prepolymer having an isocyanate group at the terminal group.

[0070] Examples of the polyisocyanate include aliphatic polyisocyanates [aliphatic diisocyanates such as propylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMDI), lysine diisocyanate (LDI), etc., aliphatic triisocyanates such as 1,6,11-undecanetriisocyanate methyl octane, 1,3,6-hexamethylene triisocyanate], alicyclic polyisocyanates [alicyclic diisocyanates such as cyclohexane 1,4-diisocyanate, isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate, hydrogenated bis(isocyanatophenyl)methane, etc., alicyclic triisocyanates such as bicycloheptane triisocyanate, etc.], aromatic polyisocyanates [aromatic diisocyanates such as phenylene diisocyanate, toluene diisocyanate (TDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), naphthalene diisocyanate (NDI), bis(isocyanatophenyl)methane (MDI), toluidine diisocyanate (TODI), 1,3-bis(isocyanatophenyl)propane, etc.; polymethylene polyphenyl polyisocyanates such as polymeric MDI, etc.].

[0071] These polyisocyanates may also be derivatives such as multimers (dimers, trimers, tetramers, etc.), adducts, modified products (biuret-modified products, allophanate-modified products, urea-modified products, etc.), and urethane oligomers having a plurality of isocyanate groups.

[0072] As the modified products or derivatives of polyisocyanates, for example, adducts of polyisocyanates (such as aliphatic polyisocyanates such as HDI) and polyhydric alcohols (such as trimethylolpropane and pentaerythritol), biuret products of the polyisocyanates, multimers of the polyisocyanates, etc. can be preferably used.

[0073] Among these polyisocyanates, aliphatic polyisocyanates or their derivatives (such as HDI or its trimer, etc.), aromatic polyisocyanates (TDI, MDI, etc.) or their derivatives are preferable, and aromatic polyisocyanates or their derivatives are particularly preferable in terms of excellent reactivity of isocyanate groups and anchoring effect.

[0074] The prepolymer having an isocyanate group at the terminal may be a polyurethane prepolymer obtained by reacting an excessive amount of the polyisocyanate with polyols.

[0075] Examples of the polyols include polyester polyols, polyether polyols, polyether ester polyols, polycarbonate polyols, polyester amide polyols, acrylic polymer polyols, etc. These polyols can be used alone or in combination of two or more. Among these polyols, polyether diols such as polyethylene glycol ether are preferable in terms of improving hydrophilicity.

[0076] The polyisocyanate may be an aqueous polyisocyanate. The aqueous polyisocyanate may be a prepolymer containing an oxyethylene chain (for example, a reaction product of a polyisocyanate such as MDI and a polyether polyol such as polyethylene glycol).

[0077] Examples of the blocking agent (protecting agent) include C 1-24 monohydric alcohols such as methanol, ethanol, and isopropanol, or their alkylene oxide adducts (for example, C 2-4 alkylene oxide adducts); phenols such as phenol, cresol, and resorcinol; oximes such as acetoxime, methyl ethyl ketoxime, and cyclohexanone oxime; C 4-20 lactams such as valerolactam, ε-caprolactam, ω-octanelactam, ω-nonanelactam, ω-decanelactam, ω-undecanelactam, ω-laurolactam, ω-tridecanelactam; secondary amines such as dibutylamine and ethyleneimine, and the like.

[0078] These blocking agents can be used alone or in combination of two or more. Among these, oximes and lactams are preferred, and C 4-12 lactams are more preferred, and C 4-8 lactams such as ε-caprolactam are even more preferred.

[0079] The content of the isocyanate group in the first blocked polyisocyanate (A2) is not particularly limited, but is, for example, about 1 to 50% by mass, preferably 3 to 40% by mass, and more preferably 5 to 30% by mass.

[0080] The dissociation temperature of the first blocked polyisocyanate (A2) (the temperature at which the blocking agent dissociates and the active isocyanate groups are regenerated) is equal to or higher than the drying temperature of the first treating agent (A). When the dissociation temperature is high, the drying temperature can be increased, so that the productivity of the core wire can be improved. The dissociation temperature may be, for example, 130°C or higher, preferably 150°C or higher, more preferably 160°C or higher, specifically 130 to 270°C, preferably 150 to 260°C, more preferably 160 to 250°C, still more preferably 165 to 230°C, and most preferably 170 to 200°C. If the dissociation temperature is too low, the drying temperature cannot be increased, so that the drying efficiency decreases and the productivity of the core wire may decrease.

[0081] The first blocked polyisocyanate (A2) may be in the form of an aqueous solution dissolved in an aqueous medium or an aqueous dispersion dispersed in an aqueous medium.

[0082] The first blocked polyisocyanate (A2) may be a commercially available product. Examples of commercially available products of the first blocked polyisocyanate (A2) include "Elastron (registered trademark) BN-27", "Elastron BN-69", "Elastron BN-77" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., "Grilbond (registered trademark) IL-6" manufactured by EMS-CHEMIE, and "Yukarezine AK-81" manufactured by Yoshimura Oil Chemical Co., Ltd.

[0083] The proportion of the first blocked polyisocyanate (A2) is, for example, 10 to 3000 parts by mass, preferably 100 to 1000 parts by mass, more preferably 200 to 800 parts by mass, still more preferably 300 to 500 parts by mass, and most preferably 350 to 450 parts by mass with respect to 100 parts by mass of the first aliphatic polyfunctional epoxy compound (A1). If the proportion of the first blocked polyisocyanate (A2) is too small, the mechanical strength and heat resistance of the adhesive film may decrease, and if it is too large, the toughness of the adhesive film may decrease.

[0084] The proportion of the first block polyisocyanate (A2) is, for example, 10 to 3000 parts by mass, preferably 100 to 1000 parts by mass, more preferably 200 to 800 parts by mass, still more preferably 300 to 500 parts by mass, and most preferably 350 to 450 parts by mass with respect to 100 parts by mass of the first vinylpyridine-diene copolymer (A3). If the proportion of the first block polyisocyanate (A2) is too small, the mechanical strength and heat resistance of the adhesive film may decrease. If it is too large, the toughness of the adhesive film may decrease.

[0085] (A3) The first vinylpyridine-diene copolymer The first vinylpyridine-diene copolymer (A3) is a copolymer containing vinylpyridine units and diene units, and has a function of improving the toughness of the first adhesive film as a latex component.

[0086] In the first vinylpyridine-diene copolymer (A3), examples of the polymerization component (diene monomer) for forming the diene unit include conjugated dienes such as butadiene, isoprene, pentadiene, 2,3-dimethylbutadiene, and chloroprene; non-conjugated dienes such as 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, dicyclopentadiene, 5-vinylnorbornene, and 5-ethylidene-2-norbornene.

[0087] These diene monomers can be used alone or in combination of two or more. Among these diene monomers, conjugated dienes such as butadiene, isoprene, and chloroprene are preferred, and butadiene is particularly preferred.

[0088] The proportion of the diene unit can be selected from the range of about 10 to 95% by mass in the first vinylpyridine-diene copolymer (A3), for example, 15 to 93% by mass, preferably 30 to 90% by mass, more preferably 40 to 85% by mass, still more preferably 50 to 80% by mass, and most preferably 65 to 75% by mass.

[0089] Examples of the polymerization component (vinylpyridine-based monomer) for forming a vinylpyridine unit include 2-vinylpyridine, 4-vinylpyridine, and the like. Among these, 2-vinylpyridine is preferred.

[0090] The proportion of the vinylpyridine unit can be selected from the range of about 1 to 1000 parts by mass with respect to 100 parts by mass of the diene unit. For example, it is 1 to 100 parts by mass, preferably 5 to 50 parts by mass, more preferably 10 to 30 parts by mass, and still more preferably 15 to 25 parts by mass.

[0091] The proportion of the vinylpyridine unit can be selected from the range of about 1 to 80% by mass in the first vinylpyridine-diene copolymer (A3), preferably 3 to 50% by mass, more preferably 5 to 30% by mass, and still more preferably 10 to 20% by mass.

[0092] The first vinylpyridine-diene copolymer (A3) preferably contains other copolymerized units in addition to the vinylpyridine unit and the diene unit.

[0093] As the other copolymerized units, non-reactive units having no reactive groups with respect to an epoxy group and an isocyanate group are preferred. Examples of the polymerization component (copolymerized monomer) for forming the non-reactive unit include C 2-10 α-linear olefins such as ethylene, 1-propylene, 1-butene, 1-pentene, 1-hexene; cyclic C 4-12 cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene; polycyclic olefins such as 2-norbornene, 5-methyl-2-norbornene, 5,5-dimethyl-2-norbornene; aromatic vinyl-based monomers such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, and the like.

[0094] These copolymerized monomers can be used alone or in combination of two or more. Among these copolymerized units, aromatic vinyl-based monomers such as styrene are preferred.

[0095] The proportion of the copolymerized unit may be 1000 parts by mass or less with respect to 100 parts by mass of the diene unit, for example, 1 to 100 parts by mass, preferably 5 to 50 parts by mass, more preferably 10 to 30 parts by mass, and still more preferably 15 to 25 parts by mass.

[0096] The proportion of the copolymerized unit may be 80% by mass or less in the first vinyl pyridine-diene copolymer (A3), preferably 3 to 50% by mass, more preferably 5 to 30% by mass, and still more preferably 10 to 20% by mass.

[0097] Preferred first vinyl pyridine-diene copolymers (A3) include, for example, butadiene-vinyl pyridine copolymers, styrene-butadiene-vinyl pyridine terpolymers (VP latex), and the like. A particularly preferred first vinyl pyridine-diene copolymer (A3) is VP latex.

[0098] The first vinyl pyridine-diene copolymer (A3) may be a commercially available product. Commercially available products of the first vinyl pyridine-diene copolymer (A3) include, for example, "Nipol (registered trademark) 2518FSH" manufactured by Nippon Zeon Co., Ltd., "Pyratex (registered trademark)" manufactured by Japan A&R Co., Ltd., and the like.

[0099] The proportion of the first vinyl pyridine-diene polymer (A3) is, for example, 1 to 1000 parts by mass, preferably 10 to 300 parts by mass, more preferably 30 to 200 parts by mass, still more preferably 50 to 150 parts by mass, and most preferably 80 to 120 parts by mass with respect to 100 parts by mass of the first aliphatic polyfunctional epoxy compound (A1). If the proportion of the first vinyl pyridine-diene polymer (A3) is too small, the toughness of the adhesive film may decrease, or the compatibility with the second adhesive film may decrease, resulting in a decrease in the adhesiveness to the adherend rubber. If it is too large, the mechanical strength and heat resistance of the adhesive film may decrease, or the adhesiveness to the adherend rubber may decrease.

[0100] The proportion of the first vinylpyridine-diene polymer (A3) is, for example, 1 to 100 parts by mass, preferably 3 to 50 parts by mass, more preferably 5 to 40 parts by mass, still more preferably 10 to 35 parts by mass, and most preferably 20 to 30 parts by mass with respect to 100 parts by mass of the first blocked polyisocyanate (A2). If the proportion of the first vinylpyridine-diene polymer (A3) is too small, the toughness of the adhesive film may decrease, the compatibility with the second adhesive film may decrease, and the adhesiveness to the adherend rubber may decrease. If it is too large, the mechanical strength and heat resistance of the adhesive film may decrease, and the adhesiveness to the adherend rubber may decrease.

[0101] The proportion of the first vinylpyridine-diene polymer (A3) may be 1 to 80% by mass in the solid content of the first treating agent (A), preferably 3 to 50% by mass, more preferably 5 to 30% by mass, still more preferably 8 to 25% by mass (for example, 10 to 25% by mass), even more preferably 10 to 22% by mass, and most preferably 15 to 20% by mass. If the proportion of the first vinylpyridine-diene polymer (A3) is too small, the toughness of the adhesive film may decrease, the compatibility with the second adhesive film may decrease, and the adhesiveness to the adherend rubber may decrease. If it is too large, the mechanical strength and heat resistance of the adhesive film may decrease, and the adhesiveness to the adherend rubber may decrease.

[0102] (A4) Surfactant The first treating agent (A) may further contain a surfactant (A4) in order to supplement the water solubility of the first aliphatic polyfunctional epoxy compound (A1) and to improve the permeability of the first treating agent (A) between fibers and the wettability with the second treating agent (B).

[0103] The surfactant (A4) includes ionic surfactants (anionic surfactants, cationic surfactants, and amphoteric surfactants), non-ionic surfactants, etc. The surfactant may be a surfactant that is non-reactive with epoxy groups and isocyanate groups. These surfactants can be used alone or in combination of two or more. Among these, ionic surfactants are particularly preferred because of their high hydrophilicity and ability to improve the permeability of the first treating agent (A) between fibers.

[0104] Examples of the ionic surfactant include anionic surfactants such as sulfonates (alkylbenzene sulfonates, α-olefin sulfonates, alkane sulfonates, etc.), sulfates (alkyl sulfates, polyoxyethylene alkyl ether sulfate esters, etc.), long-chain fatty acid salts, naphthalene sulfonic acid formalin condensates, phosphate esters (aliphatic phosphate ester type, aromatic phosphate ester type, alkyl phosphates, etc.), sulfosuccinate esters (dialkyl sulfosuccinate esters, etc.); cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts; and amphoteric surfactants such as alkyl betaines, imidazoline derivatives, etc.

[0105] These ionic surfactants can be used alone or in combination of two or more. Among these ionic surfactants, anionic surfactants are preferred from the viewpoint of improving the permeability of the first treating agent (A) between fibers. Dialkyl sulfosuccinate esters are preferred from the viewpoint of having low reactivity with epoxy groups and isocyanate groups and improving the permeability of the first treating agent (A) between fibers. DiC alkyl sulfosuccinates such as sodium di(2-ethylhexyl) sulfosuccinate are particularly preferred. 4-12 Dialkyl sulfosuccinates are particularly preferred.

[0106] The surfactant (A4) may be a commercially available product. Examples of the commercially available product of the surfactant (A4) include "Aerosol OT" manufactured by Cytec, which is a dialkyl sulfosuccinate ester, and "Neocol (registered trademark) SW-C" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.

[0107] The proportion of the surfactant (A4) is, for example, 0.1 to 30 parts by mass, preferably 1 to 25 parts by mass, more preferably 3 to 20 parts by mass, still more preferably 5 to 15 parts by mass, and most preferably 8 to 12 parts by mass with respect to 100 parts by mass of the first aliphatic polyfunctional epoxy compound (A1). If the proportion of the surfactant (A4) is too small, there is a risk that the effect of permeating the first treating agent (A) between fibers will not be exhibited. If it is too large, there is a risk that the adhesiveness and heat resistance to the fibers will decrease.

[0108] The proportion of the surfactant (A4) is, for example, 0.1 to 30 parts by mass, preferably 1 to 25 parts by mass, more preferably 3 to 20 parts by mass, still more preferably 5 to 15 parts by mass, and most preferably 8 to 12 parts by mass with respect to 100 parts by mass of the first vinylpyridine-diene copolymer (A3). If the proportion of the surfactant (A4) is too small, there is a risk that the effect of permeating the first treating agent (A) between fibers will not be exhibited. If it is too large, there is a risk that the adhesiveness and heat resistance of the fibers will decrease.

[0109] (A5) Hydrophilic solvent The first treating agent (A) preferably further contains a hydrophilic solvent (A5) from the viewpoint of facilitating the penetration of the first treating agent (A) between fibers by immersion and impregnation treatments. The hydrophilic solvent (A5) has a smaller environmental load than general-purpose organic solvents (especially hydrophobic organic solvents).

[0110] Examples of the hydrophilic solvent (A5) include water, lower aliphatic alcohols (such as C 1-4 alkyl alcohols such as methanol, ethanol, and isopropanol), alkylene glycols (such as ethylene glycol, diethylene glycol, and propylene glycol), and ketones (such as acetone).

[0111] These hydrophilic solvents can be used alone or in combination of two or more. Among these, hydrophilic solvents containing water are preferred, and water alone is particularly preferred.

[0112] The solid content (active ingredient) concentration in the first treating agent (A) may be, for example, 1 to 70% by mass, preferably 5 to 50% by mass, more preferably 10 to 30% by mass, still more preferably 13 to 25% by mass, and most preferably 15 to 20% by mass. If the solid content concentration is too low, there is a risk that the fibers cannot be firmly adhered to each other, and if it is too high, there is a risk that the first treating agent (A) does not sufficiently penetrate between the fibers.

[0113] The proportion of the hydrophilic solvent (A5) is, for example, 100 to 10,000 parts by mass, preferably 500 to 5,000 parts by mass, and more preferably 1,000 to 3,000 parts by mass with respect to 100 parts by mass of the first aliphatic polyfunctional epoxy compound (A1).

[0114] The proportion of the hydrophilic solvent (A5) is, for example, 100 to 10,000 parts by mass, preferably 500 to 5,000 parts by mass, and more preferably 1,000 to 3,000 parts by mass with respect to 100 parts by mass of the first vinylpyridine-diene copolymer (A3).

[0115] (A6) Other additives The first treating agent (A) may further contain, as other additives, conventional additives contained in a treating agent for adhesively treating a core wire, as long as the effects of the present invention are not impaired.

[0116] Examples of the conventional additives include fillers (such as carbon black), curing accelerators, adhesion improvers, anti-aging agents, lubricants, tackifiers, stabilizers, coupling agents, plasticizers, colorants, and the like. These conventional additives can be used alone or in combination of two or more.

[0117] The total proportion of the conventional additives may be 30% by mass or less in the first treating agent (A), for example, 0.01 to 30% by mass, preferably 0.05 to 20% by mass, and more preferably 0.1 to 10% by mass.

[0118] Since the first treatment agent (A) substantially does not contain resorcinol, formaldehyde, bisphenol A, and their reaction products, it can suppress adverse effects on the environment and the human body. Furthermore, the first treatment agent (A) may contain resorcinol, formaldehyde, bisphenol A, and their reaction products as long as the amount is trace and has no impact on the environment and the human body, but it is preferably completely free of resorcinol, formaldehyde, bisphenol A, and their reaction products.

[0119] In the present application, the reaction products of resorcinol, formaldehyde, and bisphenol A are reaction products obtained using at least one selected from the group consisting of resorcinol, formaldehyde, and bisphenol A as raw materials. Examples include condensates of resorcinol and formaldehyde (RF condensates), reaction products of resorcinol, formaldehyde, and latex (RFL), bisphenol A type epoxy resins, and the like.

[0120] The first treatment agent (A) is preferably an aqueous treatment agent containing a hydrophilic solvent (A5). Since the first treatment agent (A) as an aqueous treatment agent substantially does not contain hydrophobic organic solvents (especially aromatic hydrocarbons such as toluene and aliphatic ketones such as methyl ethyl ketone), it can suppress adverse effects on the environment and the human body. Furthermore, the first treatment agent (A) may contain a hydrophobic organic solvent as long as the amount is trace and has no impact on the environment and the human body, but it is preferably completely free of hydrophobic organic solvents.

[0121] When the first treatment agent (A) is an aqueous treatment agent, it may be in any form of a solution such as an aqueous solution, a dispersion, or an emulsion.

[0122] (Treatment method in the first treatment step) The preparation method of the first treatment agent (A) is not particularly limited. For example, it may be prepared by a method of stirring and mixing all components together, or it may be prepared by a method of dividing and stirring and mixing each component. Among these methods, the method of dividing and stirring and mixing each component is preferred.

[0123] As a method for treating the untreated yarn of the transmission belt core wire with the first treating agent (A), there are no particular restrictions, and examples thereof include spraying, coating, impregnation, dipping, and the like. Among these treatment methods, dipping is preferred because it is easy for the first treating agent (A) to uniformly penetrate between the fibers. The dipping time is, for example, 1 to 60 seconds, preferably 5 to 30 seconds, more preferably 10 to 20 seconds.

[0124] After treating the untreated yarn of the transmission belt core wire with the first treating agent (A), it may be dried as necessary. The drying temperature may be a temperature lower than the dissociation temperature of the first block polyisocyanate (A2), and it may be dried at room temperature, but from the viewpoint of shortening the working time, it is preferably dried by heating, and particularly preferably dried by blowing hot air. The drying temperature is, for example, 100 to 170°C, preferably 120 to 165°C, more preferably 130 to 160°C, still more preferably 135 to 155°C, and most preferably 140 to 152°C. The drying time is, for example, 5 seconds to 10 minutes, preferably 10 seconds to 5 minutes, more preferably 30 seconds to 4 minutes, still more preferably 1 to 3 minutes.

[0125] In the obtained first treated yarn, the ratio of the first treating agent (A) (the ratio of the solid content after drying) may be 0.1 part by mass or more with respect to 100 parts by mass of the untreated yarn, and is, for example, 0.1 to 30 parts by mass, preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, still more preferably 3 to 8 parts by mass, and most preferably 4 to 7 parts by mass. If the ratio of the first treating agent (A) is too small, the adhesive force between the fibers cannot be improved, and the mechanical properties and heat resistance of the first adhesive film may also decrease.

[0126] [Second treatment step] In the second treatment step, when the first treated yarn is a twisted cord, the second treating agent (B) forms a second adhesive film on the first adhesive film formed by the first treating agent (A), improving the bundling property of the twisted cord and the adhesion to the first treated yarn, and also improving the adhesion to the rubber constituting the belt.

[0127] (B) Second treating agent The second treating agent (B) contains a second aliphatic polyfunctional epoxy compound (B1), a second blocked polyisocyanate (B2), a second vinylpyridine-diene copolymer (B3), and a reactive compatibilizer (B4).

[0128] (B1) Second aliphatic polyfunctional epoxy compound As the second aliphatic polyfunctional epoxy compound (B1), it can be selected from the aliphatic polyfunctional epoxy compounds exemplified in the section of the first aliphatic polyfunctional epoxy compound (A1), including preferred embodiments. The second aliphatic polyfunctional epoxy compound (B1) may be different from the first aliphatic polyfunctional epoxy compound (A1), but is preferably the same.

[0129] The epoxy equivalent and the number of functional groups of the second aliphatic polyfunctional epoxy compound (B1) can also be selected from the epoxy equivalent and the number of functional groups described in the section of the first aliphatic polyfunctional epoxy compound (A1), including preferred embodiments.

[0130] The proportion of the second aliphatic polyfunctional epoxy compound (B1) can be selected from the range of about 0.05 to 10% by mass in the second treating agent (B), for example, 0.08 to 5% by mass, preferably 0.1 to 3% by mass, more preferably 0.2 to 1% by mass, still more preferably 0.3 to 0.8% by mass, and most preferably 0.4 to 0.6% by mass. If the proportion of the second aliphatic polyfunctional epoxy compound (B1) is too small, the mechanical strength and heat resistance of the adhesive film may decrease. If it is too large, the adhesiveness to the adherend rubber may decrease.

[0131] The proportion of the second aliphatic polyfunctional epoxy compound (B1) can be selected from the range of about 0.1 to 30% by mass in the solid content of the second treating agent (B), for example, 0.3 to 20% by mass, preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass, still more preferably 1.5 to 5% by mass, and most preferably 2 to 3% by mass.

[0132] The proportion of the second aliphatic polyfunctional epoxy compound (B1) is, for example, 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, still more preferably 2 to 4 parts by mass, based on 100 parts by mass of the latex solid content [total amount of the second vinylpyridine-diene copolymer (B3) and other rubbers (B5)]. If the proportion of the second aliphatic polyfunctional epoxy compound (B1) is too small, the mechanical strength and heat resistance of the adhesive film may decrease. If it is too large, the adhesiveness to the adherend rubber may decrease.

[0133] (B2) The second blocked polyisocyanate As the second blocked polyisocyanate (B2), it can be selected from the blocked polyisocyanates exemplified in the section of the first blocked polyisocyanate (A2), including preferred embodiments. The second blocked polyisocyanate (B2) may be different from the first blocked polyisocyanate (A2), but is preferably the same.

[0134] As the blocking agent for the second blocked polyisocyanate (B2), it can be selected from the blocking agents exemplified in the section of the first blocked polyisocyanate (A2), including preferred embodiments.

[0135] The content rate of the isocyanate group and the dissociation temperature of the second blocked polyisocyanate (B2) can also be selected from the content rate of the isocyanate group and the dissociation temperature described in the section of the first blocked polyisocyanate (A2), including preferred embodiments.

[0136] The second blocked polyisocyanate (B2) may be in the form of an aqueous solution dissolved in an aqueous medium or an aqueous dispersion dispersed in an aqueous medium.

[0137] The proportion of the second blocked polyisocyanate (B2) is, for example, 10 to 3000 parts by mass, preferably 100 to 1000 parts by mass, more preferably 200 to 800 parts by mass, still more preferably 300 to 500 parts by mass, and most preferably 350 to 450 parts by mass with respect to 100 parts by mass of the second aliphatic polyfunctional epoxy compound (B1). If the proportion of the second blocked polyisocyanate (B2) is too small, the mechanical strength and heat resistance of the adhesive film may decrease. If it is too large, the adhesiveness to the adherend rubber may decrease.

[0138] The proportion of the second blocked polyisocyanate (B2) is, for example, 1 to 60 parts by mass, preferably 5 to 30 parts by mass, more preferably 10 to 15 parts by mass with respect to 100 parts by mass of the latex solid content [total amount of the second vinylpyridine-diene copolymer (B3) and other rubbers (B5)]. If the proportion of the second blocked polyisocyanate (B2) is too small, the mechanical strength and heat resistance of the adhesive film may decrease. If it is too large, the adhesiveness to the adherend rubber may decrease.

[0139] (B3) The second vinylpyridine-diene copolymer In the second treating agent (B), the second vinylpyridine-diene copolymer (B3) has a function of improving the toughness of the second adhesive film as a latex component and also has a function of improving the adhesiveness to the adherend rubber.

[0140] The second vinylpyridine-diene copolymer (B3) can be selected from the vinylpyridine-diene copolymers exemplified in the section of the first vinylpyridine-diene copolymer (A3), including preferred embodiments. The second vinylpyridine-diene copolymer (B3) may be different from the first vinylpyridine-diene copolymer (A3), but is preferably the same.

[0141] The proportion of the second vinylpyridine-diene copolymer (B3) is, for example, 10 to 1000 parts by mass, preferably 50 to 800 parts by mass, more preferably 100 to 500 parts by mass, still more preferably 150 to 400 parts by mass, and most preferably 200 to 300 parts by mass with respect to 100 parts by mass of the second block polyisocyanate (B2). If the proportion of the second vinylpyridine-diene copolymer (B3) is too small, the adhesion to the adherend rubber may decrease. If it is too large, the mechanical strength and heat resistance of the second adhesive film may decrease, or the adhesion to the adherend rubber that is non-polar or low-polar may decrease.

[0142] The proportion of the second vinylpyridine-diene copolymer (B3) can be selected from the range of about 1 to 100% by mass (especially 1 to 90% by mass) in the latex solids [total amount of the second vinylpyridine-diene copolymer (B3) and other rubbers (B5)], for example, 5 to 100% by mass (for example, 5 to 70% by mass), preferably 10 to 80% by mass (for example, 10 to 50% by mass), more preferably 15 to 60% by mass, still more preferably 20 to 40% by mass, and most preferably 25 to 35% by mass. If the proportion of the second vinylpyridine-diene copolymer (B3) is too small, the adhesion to the adherend rubber may decrease. If it is too large, the mechanical strength and heat resistance of the second adhesive film may decrease, or the adhesion to the adherend rubber that is non-polar or low-polar may decrease.

[0143] The proportion of the second vinylpyridine-diene copolymer (B3) may be 1 to 90% by mass (especially 10 to 90% by mass) in the solids of the second treating agent (B), preferably 3 to 80% by mass, more preferably 5 to 70% by mass, still more preferably 10 to 50% by mass, and most preferably 15 to 40% by mass.

[0144] (B4) Reactive compatibilizer Since the second treating agent (B) contains a reactive compatibilizer (B4), the second vinylpyridine-diene copolymer (B3) reacts with both the epoxy groups and hydroxyl groups of the second aliphatic polyfunctional epoxy compound (B1) and the isocyanate groups of the second blocked isocyanate (B2), and while compatibility and phase separation compete with each other, a dense and fine phase separation structure can be formed, and a second adhesive film excellent in adhesion strength at high temperatures to the adherend rubber can be formed.

[0145] The reactive compatibilizer (B4) is not particularly limited as long as it is a compound having a functional group (such as a carboxyl group or an acid anhydride group) that reacts with the epoxy group, hydroxyl group, or isocyanate group of the second aliphatic polyfunctional epoxy compound (B1) and the second blocked isocyanate (B2), and a double bond (ethylenically unsaturated bond) that can be co-crosslinked with a diene polymer (diene rubber). However, from the viewpoint of mechanical properties of the second adhesive film, etc., an oligomer or polymer having the functional group and the double bond is preferred. Further, as a preferred reactive compatibilizer (B4), from the viewpoint of adhesion to the adherend rubber, etc., for example, an epoxy-modified diene polymer (such as an epoxy-modified product of liquid polybutadiene), an acid-modified diene polymer, a diene polymer having the functional group introduced at the terminal, etc. can be mentioned. These reactive compatibilizers can be used alone or in combination of two or more. Among these reactive compatibilizers, an acid-modified diene polymer is preferred.

[0146] The acid-modified diene polymer may be a diene polymer modified with a carboxylic acid or an acid anhydride, specifically, a diene polymer having a carboxyl group and / or an acid anhydride group. As a method of modification with an acid, it is sufficient that a carboxyl group and / or an acid anhydride group is introduced into the skeleton of the diene polymer, and it is not particularly limited. However, from the viewpoint of mechanical properties, etc., a method of introducing a monomer having a carboxyl group and / or an acid anhydride group by copolymerization is preferred. The form of copolymerization may be random copolymerization, block copolymerization, etc., but graft copolymerization is preferred from the viewpoint of improving adhesion to an elastomer.

[0147] Examples of the diene polymer include polybutadiene, polyisoprene, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. These diene polymers can be used alone or in combination of two or more. Among these, polybutadiene-based polymers containing butadiene units are preferred, and polybutadiene (1,4-butadiene homopolymer) is particularly preferred.

[0148] Examples of the monomer having a carboxyl group and / or an acid anhydride group include unsaturated monocarboxylic acids [e.g., (meth)acrylic acid, crotonic acid, isocrotonic acid, angelic acid, etc.], unsaturated dicarboxylic acids or their acid anhydrides [e.g., (anhydrous) maleic acid, fumaric acid, (anhydrous) citraconic acid, (anhydrous) itaconic acid, mesaconic acid, etc.]. These monomers can be used alone or in combination of two or more. Among these monomers, unsaturated monocarboxylic acids such as (meth)acrylic acid, unsaturated dicarboxylic acids or their acid anhydrides such as (anhydrous) maleic acid are preferred from the viewpoint of improving adhesion, and (anhydrous) maleic acid is particularly preferred. Further, the diene polymer modified with a dicarboxylic acid may be a polymer obtained by ring-opening the acid anhydride group of the diene polymer modified with an anhydrous carboxylic acid. Furthermore, the carboxyl group may be in the form of a salt neutralized with an alkali (e.g., alkali metals such as lithium, sodium, potassium, and alkaline earth metals such as calcium, magnesium, etc.).

[0149] The proportion of the monomer (monomer unit in the acid-modified diene polymer) may be 1 mol or more per 1 mol of the diene polymer, for example, 1 to 30 mol, preferably 3 to 25 mol, more preferably 5 to 20 mol, still more preferably 7 to 15 mol, and most preferably 9 to 13 mol. If the proportion of the monomer is too small, the adhesion to the rubber may decrease.

[0150] The acid value of the acid-modified diene polymer may be 10 mgKOH / g or more, for example, 10 to 500 mgKOH / g, preferably 20 to 300 mgKOH / g, more preferably 30 to 200 mgKOH / g, and most preferably 35 to 150 mgKOH / g. If the acid value is too low, the adhesion to rubber may decrease.

[0151] The number average molecular weight of the acid-modified diene polymer is, in terms of polystyrene in gel permeation chromatography (GPC), for example, 1,000 to 300,000, preferably 1,500 to 100,000, more preferably 2,000 to 10,000, still more preferably 3,000 to 8,000, and most preferably 4,000 to 6,000. If the molecular weight of the acid-modified diene polymer is too small, the adhesion to rubber may decrease, and conversely, if it is too large, the mechanical properties of the second adhesive film may decrease.

[0152] As the acid-modified diene polymer, a (maleic anhydride) maleic acid-modified diene polymer is preferred, a maleic anhydride polybutadiene is more preferred, and a maleic acid-modified polybutadiene is most preferred.

[0153] The reactive compatibilizer (B4) may be a commercially available product. Examples of commercially available products of the reactive compatibilizer (B4) include "Ricobond (registered trademark) 7002" and "Ricobond 7004" manufactured by CRAY VALLEY, which are aqueous emulsions of maleic anhydride-modified polybutadiene.

[0154] The proportion of the reactive compatibilizer (B4) can be selected from the range of about 10 to 3000 parts by mass (particularly 50 to 1000 parts by mass) with respect to 100 parts by mass of the second aliphatic polyfunctional epoxy compound (B1), for example, 50 to 500 parts by mass, preferably 70 to 350 parts by mass, more preferably 100 to 300 parts by mass, still more preferably 130 to 250 parts by mass, and most preferably 150 to 200 parts by mass. If the proportion of the reactive compatibilizer (B4) is too small, the mechanical strength and heat resistance of the second adhesive film may decrease, or the adhesiveness to the polar adherend rubber may decrease. If it is too large, the adhesiveness to the adherend rubber may decrease.

[0155] The proportion of the reactive compatibilizer (B4) can be selected from the range of about 5 to 300 parts by mass with respect to 100 parts by mass of the second blocked polyisocyanate (B2), for example, 10 to 100 parts by mass, preferably 15 to 90 parts by mass, more preferably 20 to 80 parts by mass, still more preferably 30 to 70 parts by mass, and most preferably 40 to 50 parts by mass. If the proportion of the reactive compatibilizer (B4) is too small, the mechanical strength and heat resistance of the second adhesive film may decrease, or the adhesiveness to the polar adherend rubber may decrease. If it is too large, the adhesiveness to the adherend rubber may decrease.

[0156] The proportion of the reactive compatibilizer (B4) is, for example, 0.5 to 20 parts by mass, preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, still more preferably 3 to 8 parts by mass with respect to 100 parts by mass of the latex solid content [total amount of the second vinyl pyridine-diene copolymer (B3) and other rubbers (B5)]. If the proportion of the reactive compatibilizer (B4) is too small, the mechanical strength and heat resistance of the second adhesive film may decrease, or the adhesiveness to the polar adherend rubber may decrease. If it is too large, the adhesiveness to the adherend rubber may decrease.

[0157] The proportion of the reactive compatibilizer (B4) may be 0.1 to 30% by mass, preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass, still more preferably 1.5 to 10% by mass, even more preferably 2 to 8% by mass, and most preferably 3 to 5% by mass in the solid content of the second treating agent (B).

[0158] (B5) Other rubber The second treating agent (B) may further contain, as rubber, other rubber (second rubber) (B5) in addition to the second vinyl pyridine-diene copolymer (B3).

[0159] Examples of the other rubber (B) include diene rubbers [natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), butyl rubber (IIR), styrene-butadiene rubber (SBR), vinyl pyridine-styrene-butadiene copolymer rubber, acrylonitrile-butadiene rubber (nitrile rubber or NBR); hydrogenated products of the above diene rubbers such as hydrogenated nitrile rubber (HNBR, including a mixed polymer of hydrogenated nitrile rubber and a metal salt of an unsaturated carboxylic acid), etc.], olefin rubbers [e.g., ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc. ethylene-α-olefin rubbers (ethylene-α-olefin elastomer; polyoctenylene rubber; ethylene-vinyl acetate copolymer rubber; chlorosulfonated polyethylene rubber (CSM), alkylated chlorosulfonated polyethylene rubber, etc.], epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluorine rubber, etc. These rubbers can be used alone or in combination of two or more.

[0160] By including, as the other rubber (B5), the same or the same type of rubber as the adherend rubber, the second treating agent (B) can improve the adhesiveness to the adherend rubber.

[0161] In the present application, the "same type of rubber" means rubber classified in the same group in JIS K 6397 (abbreviations for raw rubber and latex). That is, in JIS K 6397, rubbers having an unsaturated carbon bond in the main chain are classified into group R (NR, BR, CR, SBR, NBR, vinyl pyridine-styrene-butadiene copolymer rubber, etc.), and rubbers having a polymethylene type saturated main chain are classified into group M (EPDM, CSM, etc.). Combining rubbers belonging to the same group can improve the adhesive strength.

[0162] As the other rubber (B5), it can be appropriately selected according to the type of the adhered rubber, and diene rubber is preferred. Examples of the diene rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), butyl rubber (IIR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (nitrile rubber or NBR), hydrogenated nitrile rubber (H-NBR), and the like. These other rubbers can be used alone or in combination of two or more. Among these, NR, BR, CR, and SBR are preferred, and SBR is particularly preferred.

[0163] Also, as the other rubber (B5), a rubber capable of co-crosslinking with the diene rubber can be selected. For example, chlorosulfonated polyethylene (CSM) can be co-crosslinked with a diene rubber or an ethylene-propylene-diene terpolymer (EPDM) using the chlorosulfone group as a crosslinking point.

[0164] The other rubber (B5) may be in the form of latex.

[0165] The second treating agent (B) preferably contains the same or the same type of rubber as the adhered rubber in terms of improving the adhesion strength between the core wire and the adhered rubber. Therefore, the other rubber (B5) may be the same or the same type of rubber as the adhered rubber (for example, diene rubber).

[0166] The proportion of the other rubber (B5) is 99% by mass or less (particularly 10 to 99% by mass), for example, 95% by mass or less (for example, 30 to 95% by mass), preferably 20 to 90% by mass (for example, 50 to 90% by mass), more preferably 40 to 85% by mass, even more preferably 60 to 80% by mass, and most preferably 65 to 75% by mass in the latex solid content [total amount of the second vinyl pyridine-diene copolymer (B3) and the other rubber (B5)]. If the proportion of the other rubber (B5) is too large, the adhesion to the adhered rubber may decrease. If it is too small, the mechanical strength and heat resistance of the second adhesive film may decrease, or the adhesion to the adhered rubber that is non-polar or low-polar may decrease.

[0167] (B6) Second hydrophilic solvent The second treatment agent (B) preferably contains a hydrophilic solvent (B6) because it is easy to uniformly coat the surface of the first treated yarn by dipping and impregnation treatments. Further, the hydrophilic solvent (B6) has a smaller environmental load than general-purpose organic solvents (particularly, hydrophobic organic solvents).

[0168] As the hydrophilic solvent (B6), it can be selected from the hydrophilic solvents exemplified in the section of the hydrophilic solvent (A5), including preferred embodiments.

[0169] The solid content (active ingredient) concentration in the second treatment agent (B) may be, for example, 5 to 50% by mass, preferably 10 to 30% by mass, and more preferably 15 to 25% by mass. If the solid content concentration is too low, there is a possibility that the surface of the first treated yarn cannot be uniformly coated with the second treatment agent (B), and if it is too high, there is a possibility that the thickness of the second adhesive film becomes non-uniform.

[0170] The ratio of the hydrophilic solvent (B6) is, for example, 100 to 2400 parts by mass, preferably 300 to 1100 parts by mass, and more preferably 400 to 700 parts by mass with respect to 100 parts by mass of the latex solid content [total amount of the second vinylpyridine-diene copolymer (B3) and other rubbers (B5)].

[0171] (B7) Other additives The second treatment agent (B) may further contain, as other additives, conventional additives contained in a treatment agent for adhesively treating a core wire, as long as the effects of the present invention are not impaired.

[0172] Examples of the conventional additives include fillers such as carbon black (such as carbon black, silica such as fumed silica, magnesium oxide, hydrotalcite, etc.), crosslinking agents (such as sulfur, zinc oxide, organic peroxides, etc.), curing accelerators, adhesion improvers, anti-aging agents, lubricants, tackifiers, stabilizers, coupling agents, plasticizers, colorants, etc. These conventional additives can be used alone or in combination of two or more.

[0173] The total proportion of the conventional additives may be 30% by mass or less in the second treating agent (B), for example, 0.01 to 30% by mass, preferably 0.05 to 20% by mass, more preferably 0.1 to 10% by mass.

[0174] Since the second treating agent (B) substantially does not contain resorcinol, formaldehyde, bisphenol A, and reaction products thereof, adverse effects on the environment and the human body can be suppressed. Further, the second treating agent (B) may contain resorcinol, formaldehyde, bisphenol A, and reaction products thereof as long as the amount is trace and has no impact on the environment and the human body, but it is preferably completely free of resorcinol, formaldehyde, bisphenol A, and reaction products thereof.

[0175] The second treating agent (B) is preferably an aqueous treating agent containing a hydrophilic solvent (B6). Since the second treating agent (B) as an aqueous treating agent substantially does not contain a hydrophobic organic solvent (particularly aromatic hydrocarbons such as toluene and aliphatic ketones such as methyl ethyl ketone), adverse effects on the environment and the human body can be suppressed. Further, the second treating agent (B) may contain a hydrophobic organic solvent as long as the amount is trace and has no impact on the environment and the human body, but it is preferably completely free of the hydrophobic organic solvent.

[0176] When the second treating agent (B) is an aqueous treating agent, it may be in any form of a solution such as an aqueous solution, a dispersion, or an emulsion.

[0177] (Treatment method in the second treatment step) The method for preparing the second treating agent (B) is not particularly limited. For example, it may be prepared by a method of stirring and mixing all components together, or it may be prepared by a method of dividing and stirring and mixing each component. Among these methods, the method of dividing and stirring and mixing each component is preferred.

[0178] The method for treating the first treated yarn with the second treating agent (B) is not particularly limited, and examples thereof include spraying, coating, impregnation, dipping, etc. Among these treatment methods, dipping is preferred. The dipping time is, for example, 1 to 60 seconds, preferably 5 to 30 seconds, more preferably 10 to 20 seconds.

[0179] After treating the first treated yarn with the second treating agent (B), it may be dried as necessary. The drying temperature may be a temperature lower than the dissociation temperature of the first blocked polyisocyanate (A2) and the second blocked isocyanate (B2), and it may be dried at room temperature, but from the viewpoint of shortening the working time, it is preferably dried by heating, and particularly preferably dried by blowing hot air. The drying temperature is, for example, 100 to 170 °C, preferably 120 to 165 °C, more preferably 130 to 160 °C, still more preferably 135 to 155 °C, and most preferably 140 to 152 °C. The drying time is, for example, 5 seconds to 10 minutes, preferably 10 seconds to 5 minutes, more preferably 30 seconds to 4 minutes, still more preferably 1 to 3 minutes.

[0180] In addition, when the dissociation temperature of the first blocked polyisocyanate (A2) and the dissociation temperature of the second blocked isocyanate (B2) are different, the drying temperature may be a temperature lower than the lower dissociation temperature.

[0181] In the obtained second treated yarn, the ratio of the second treating agent (B) (the ratio of the solid content after drying) may be 0.1 part by mass or more with respect to 100 parts by mass of the untreated yarn, for example, 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, still more preferably 2 to 4 parts by mass, and most preferably 2.5 to 3.5 parts by mass. If the ratio of the second treating agent (B) is too small, the mechanical properties and heat resistance of the second adhesive film may deteriorate.

[0182] [Heat treatment step] In the heat treatment step, the second treated yarn is heated to promote the crosslinking reaction by the first blocked polyisocyanate (A2) and the second blocked isocyanate (B2).

[0183] The heating temperature can be appropriately selected according to the dissociation temperature as long as it is equal to or higher than the dissociation temperatures of the first blocked polyisocyanate (A2) and the second blocked isocyanate (B2). For example, it is 180 to 250 °C, preferably 190 to 240 °C, and more preferably 200 to 235 °C. The heating temperature is preferably 5 °C or higher than the dissociation temperature. For example, it may be 10 to 70 °C higher, preferably 20 to 60 °C higher, and more preferably 40 to 60 °C higher. The drying time is, for example, 5 seconds to 10 minutes, preferably 10 seconds to 5 minutes, more preferably 30 seconds to 4 minutes, and even more preferably 1 to 3 minutes.

[0184] In addition, when the dissociation temperature of the first blocked polyisocyanate (A2) is different from the dissociation temperature of the second blocked isocyanate (B2), the heating temperature may be a temperature equal to or higher than the higher dissociation temperature.

[0185] The heat-treated second treated yarn may be cooled to room temperature and wound around a bobbin, or it may be subjected to a heat setting treatment for stretching or shrinking during heat treatment and cooling. In the heat setting treatment, the closer the heat treatment temperature is to the melting point of the fiber constituting the second treated yarn, the more the setting effect can be improved. Furthermore, by performing the heat setting treatment, the elongation with respect to the load of the core wire for the transmission belt can be reduced (or increased) to finish with desired characteristics.

[0186] A series of processes from the first treatment step to the heat treatment step can be continuously processed by a cord dip machine that combines a cord drive system, a dipping mechanism, and a hot air furnace capable of maintaining temperature, and a conventional cord dip machine (3-bath treatment machine) for transmission belts can be diverted.

[0187] The manufacturing method of the present invention only needs to include a first treatment step, a second treatment step, and a heat treatment step. The steps using a treatment agent are preferably two steps (when the first treatment step and the second treatment step are immersion steps, it is a two-bath treatment), and it is preferably not to include a step of overcoating with rubber paste. Even if the manufacturing method of the present invention does not include a step of overcoating, which causes an increase in man-hours and an increase in environmental load due to the use of organic solvents, the adhesiveness between the core wire and the adhered rubber can be improved, so that the man-hours and the environmental load can be reduced.

[0188] <Core wire for transmission belt> The core wire for a transmission belt obtained by the manufacturing method of the present invention is a core wire for a transmission belt to which resin and rubber are applied on the surface and between fibers by the manufacturing method, and contains at least a reaction product of an aliphatic polyfunctional epoxy compound, a blocked polyisocyanate, and a vinylpyridine-diene copolymer on the surface and between fibers.

[0189] The core wire obtained by the manufacturing method of the present invention is suitable for use in transmission belts, and is usually used in contact with the rubber layer of the transmission belt, and is preferably embedded in this rubber layer. Further, the rubber layer only needs to be formed of a rubber composition containing rubber, and this rubber corresponds to the adhered rubber that comes into contact with the core wire. The rubber layer can be appropriately selected according to the use of the transmission belt, etc. For example, in a low-edge cogged V-belt, it may be an adhesive rubber layer formed of a rubber composition.

[0190] As the adhered rubber, a rubber that can be vulcanized or crosslinked may be used. For example, in addition to the diene rubbers exemplified in the section of other rubbers (B5), olefin rubbers, epichlorohydrin rubbers, acrylic rubbers, silicone rubbers, urethane rubbers, fluorine rubbers, etc. can be mentioned. These rubbers can be used alone or in combination of two or more. In the present invention, the adhesive strength can be improved not only with respect to NR and SBR but also with respect to the adhered rubber formed of these various rubbers.

[0191] Among these rubbers, as the adherend rubber, diene rubber is preferable, at least one selected from the group consisting of NR, SBR, and CR is preferable, a mixture of NR and SBR, and CR are more preferable, and CR is even more preferable.

[0192] The core wire for the transmission belt may be a polyester core wire obtained by the above manufacturing method. That is, the polyester core wire for the transmission belt may be a polyester multifilament yarn (for example, a twisted cord) treated with the first treating agent (A) and the second treating agent (B).

[0193] The average diameter of the core wire for the transmission belt is, for example, 0.3 to 3.6 mm, preferably 0.5 to 3.1 mm, and more preferably 0.6 to 2.7 mm.

[0194] The transmission belt only needs to contain the above-mentioned core wire for the transmission belt. Usually, it is often a transmission belt provided with a rubber layer in which the core wire for the transmission belt (especially a plurality of core wires for the transmission belt) is embedded along the longitudinal direction (or circumferential direction) of the belt. The interval (spinning pitch) between adjacent core wires is, for example, 0.5 to 4 mm, preferably 0.6 to 2.5 mm, and more preferably 0.7 to 2.3 mm.

[0195] Typically, the transmission belt may be a transmission belt having an adhesive rubber layer and a compression rubber layer on one surface of this adhesive rubber layer, and the adhesive rubber layer embeds the core wire for the transmission belt. An extension rubber layer may be provided on the other surface of the adhesive rubber layer. Further, the transmission belt may cover (or laminate) part (for example, the surface of the extension rubber layer and / or the compression rubber layer) or all of the belt body made of a rubber layer with a reinforcing cloth.

[0196] Examples of such transmission belts include V-belts such as wrapped V-belts and low-edge V-belts, V-ribbed belts, flat belts, toothed belts, and the like.

Examples

[0197] The present invention will be described in more detail based on the following examples, but the present invention is not limited by these examples.

[0198] [Examples 1 to 7] (Production of Twisted Cord) Two raw yarns of polyester fiber (「Tetoron 704M」manufactured by Toray Industries, Inc., fineness 1100 dtex) were aligned and given an S twist of 210 turns per meter, and then these were further aligned in three strands and given a Z twist of 110 turns per meter to obtain a multifilament cord.

[0199] (Preparation of First Treatment Agent) A first treatment agent having the composition shown in Table 1 was prepared. In Examples 1 to 5, first, 27 g of an aliphatic polyfunctional epoxy compound, 4 g of a surfactant, and 80 g of water were added and stirred until a colorless and transparent aqueous solution was obtained. Further, 368 g of a blocked polyisocyanate was added and stirred until uniform to obtain Resin Dispersion 1. Next, while stirring a solution obtained by diluting 69 g of VP latex with 500 g of water, Resin Dispersion 1 was added to obtain a first treatment agent. On the other hand, in Examples 6 and 7, a first treatment agent was obtained in the same manner as in Examples 1 to 5 except that the blending amounts of the respective components were changed to the blending amounts shown in Table 1.

[0200]

Table 1

[0201] Details of the aliphatic polyfunctional epoxy compound, surfactant, blocked polyisocyanate, and VP latex in Table 1 are as follows.

[0202] Aliphatic polyfunctional epoxy compound: 「Denacol EX-614B」manufactured by Nagase ChemteX Corporation, epoxy equivalent 173 g / eq. Surfactant: Dialkyl sulfosuccinate ester salt, 「Neocol SW-C」(solid content concentration 70 mass%) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., aqueous system Block polyisocyanate: "Elastron BN-27" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. (solid content concentration: 30% by mass), dissociation temperature of the blocking agent (ε-caprolactam): approximately 180°C, aqueous system VP latex: "Nipol2518FSH" manufactured by Nippon Zeon Co., Ltd. (solid content concentration: 40.5% by mass), aqueous system

[0203] (Preparation of the second treatment agent) The second treatment agent with the composition shown in Table 2 was prepared. In Examples 1 and 6 - 7, first, 5 g of an aliphatic polyfunctional epoxy compound was added to 64 g of the block polyisocyanate and stirred until uniform. Further, 27 g of the acid-modified diene polymer was diluted with 74 g of water and then added to obtain Resin Dispersion 2. Next, while stirring a solution obtained by diluting 277 g of SBR latex and 118 g of VP latex with 400 g of water, the Resin Dispersion 2 and 35 g of carbon black were added to obtain the second treatment agent. On the other hand, in Examples 2 - 5, the second treatment agent was obtained in the same manner as in Examples 1 and 6 - 7, except that the blending amounts of the respective components were changed to the blending amounts shown in Table 2.

[0204]

Table 2

[0205] Details of the acid-modified diene polymer and SBR latex in Table 2 are as follows. The aliphatic polyfunctional epoxy compound, block polyisocyanate, and VP latex are the same products as those in the first treatment agent.

[0206] Acid-modified diene polymer: maleic anhydride-modified polybutadiene, "Ricobond7004" manufactured by Clay Valley Co., Ltd. (solid content concentration: 30% by mass), aqueous system SBR latex: "NipolLX110" manufactured by Nippon Zeon Co., Ltd. (solid content concentration: 40.5% by mass), aqueous system Carbon black: "FUJI SP BLACK203" manufactured by Fuji Pigment Co., Ltd. (solid content concentration: 23% by mass), aqueous dispersion

[0207] (Treatment process of the cord (dipping, drying, heat treatment)) After dipping the twisted cords in the first treating agent, they were dried at 150°C for 1 minute. Subsequently, after dipping in the second treating agent, they were dried at 150°C for 1 minute and further heat-treated at 230°C for 1 minute. Table 3 shows the adhesion rates of the first treating agent (the mass ratio of the solid content of the first treating agent to the mass of the untreated polyester fiber cord) and the second treating agent (the mass ratio of the solid content of the second treating agent to the mass of the untreated polyester fiber cord).

[0208]

Table 3

[0209] (Adhered rubber) As shown in Tables 4 and 5, two types of adhered rubbers were prepared: an NR / SBR type in which the rubber is a mixture of natural rubber and styrene-butadiene rubber, and a CR type in which the rubber is chloroprene rubber. These adhered rubbers form an adhesive rubber layer around the core wire in the transmission belt and integrate the core wire, the compression rubber layer, and the extension layer.

[0210]

Table 4

[0211]

Table 5

[0212] The details of the components in Tables 4 and 5 are as follows.

[0213] NR: SMR20 (Standard Malaysian Rubber) SBR: "Nipol 1502" manufactured by Zeon Corporation, Japan CR: "PM-40" manufactured by Denka Co., Ltd. Zinc oxide: "Zinc Oxide Type 2" manufactured by Sakai Chemical Industry Co., Ltd. Magnesium oxide: "Kyowa Mag 150" manufactured by Kyowa Chemical Industry Co., Ltd. Stearic acid: "Stearic Acid Camellia" manufactured by NOF Corporation Zinc stearate: "Zinc stearate" manufactured by Kawamura Kasei Kogyo Co., Ltd. Plasticizer A (aromatic oil): "Diana Process Oil AH-16" manufactured by Idemitsu Kosan Co., Ltd. Plasticizer B (naphthenic oil): "SUNTHENE 410" manufactured by Nippon Sun Oil Co., Ltd. Carbon black GPF: "HTC#G" manufactured by Nippon Carbon Co., Ltd. Carbon black ISAF: "Seast 6" manufactured by Tokai Carbon Co., Ltd. Silica: "Ultrasil VN3" manufactured by Evonik Industries AG Antioxidant ODPA (octylated diphenylamine): "Nocrack AD-F" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Adhesion promoter: "T-REZ RA-100" manufactured by ENEOS Co., Ltd. Vulcanization accelerator MBTS (dibenzothiazyl disulfide): "Nocceler DM" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator TMTD (tetramethylthiuram disulfide): "Nocceler TT" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfur: "Powder sulfur" manufactured by Migen Chemical Co., Ltd. Co-crosslinking agent MPBM (N,N’-m-phenylenedimaleimide): "Barnock PM" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0214] (Peel test) The treatment code was spirally wound around the outer circumference of a cylinder with an outer diameter of 150 mm without gaps until the width reached 30 mm. After attaching an adhesive tape on the wound treatment code, it was cut to a length of 150 mm. This laminate of the adhesive tape and the treatment code was inserted into a mold with a width of 30 mm, a length of 150 mm, and a depth of 4 mm with the surface of the adhesive tape facing down (in contact with the bottom surface of the mold). Then, the above-mentioned adherend rubber (uncured rubber sheet) was filled on the treatment code. A reinforcing cloth was placed thereon, and it was vulcanized at a surface pressure of 2 MPa and a temperature of 153 °C for 20 minutes. The vulcanized laminate was cut to a width of 25 mm, and as shown in Figure 1, a peel test sample with a width of 25 mm, a length of 150 mm, and a thickness of 4 mm was prepared.

[0215] As shown in Fig. 2, at one end of the fabricated sample for the peeling test in the length direction, a cut was made with a blade at the interface between the treatment code 2 and the crosslinked rubber 3, separating it into a gripping part A where the adhesive tape 1 and the treatment code 2 were laminated, and a gripping part B where the crosslinked rubber 3 and the reinforcing fabric 4 were laminated (the length of each gripping part was approximately 30 mm).

[0216] The gripping part A was gripped with the upper gripper of a tensile testing machine ("AGS-J10kN" manufactured by Shimadzu Corporation), and the gripping part B was gripped with the lower gripper. The upper gripper was raised at a speed of 50 mm / min, and the peeling mode was observed while recording the tensile force (peeling force). The test temperature (ambient temperature) was 23°C when the adhered rubber was NR / SBR, and was conducted at two levels of 23°C and 100°C when the adhered rubber was CR. The samples for the peeling test were measured after being left at the test temperature for 3 hours or more.

[0217] The peeling mode is classified into interfacial peeling, cohesive failure, and rubber failure. Specifically, as shown in Fig. 3 as a conceptual diagram of the peeling mode, interfacial peeling (interlayer peeling) can be further classified into fiber interfacial peeling (peeling between the cord and the first adhesive film), adhesive interlayer peeling (peeling between the first adhesive film and the second adhesive film), and rubber interfacial peeling (peeling between the second adhesive film and the adhered rubber). Cohesive failure is a mode in which the adhesive film itself is broken, and rubber failure is a mode in which the adhered rubber itself is broken.

[0218] Among these peeling modes, in the case of interfacial peeling and cohesive failure, the peeling force can be compared as an index of adhesive strength. However, in the case of rubber failure, the peeling force becomes an index of the tearing force of the rubber and cannot be used as an index of adhesive strength. However, interfacial peeling is likely to occur when the adhesive strength of the adhesive film is low, and cohesive failure is likely to occur when the mechanical strength and toughness of the adhesive film are low. It can be considered that rubber failure is likely to occur when the adhesive strength, mechanical strength, and toughness of the adhesive film are high. Therefore, when the peeling mode is rubber failure, it can be judged that the adhesive strength and mechanical strength of the adhesive film are good.

[0219] The evaluation results for NR / SBR-based adhered rubber are shown in Table 7, and the evaluation results for CR-based adhered rubber are shown in Table 8.

[0220] [Comparative Example 1] As a comparative example, a three-bath treatment that is widely used as an adhesion treatment for the core wire of a transmission belt was performed. That is, as shown in Table 6, a primer (first treatment agent) mainly composed of polymeric MDI, an RFL (second treatment agent) obtained by mixing resorcinol, formaldehyde, and latex, and an adhesive treatment with a rubber paste (third treatment agent) in which a rubber composition is dissolved or dispersed in an organic solvent was used to prepare a treatment code.

[0221] The first treatment agent (primer) was prepared by dissolving 100 g of polymeric MDI ("Millionate (registered trademark) MR-200" manufactured by Tosoh Corporation, NCO content 30% by mass) in 900 g of toluene. The second treatment agent (RFL) was prepared by mixing and aging an RF solution containing a condensate of resorcinol and formaldehyde and an L solution containing latex. First, 118 g of VP latex "Nipol2518FSH", 277 g of SBR latex "NipolLX110", and 400 g of water were mixed to prepare the L solution. Separately, 32 g of resorcinol was dissolved in 150 g of water, and then 22 g of formalin with a concentration of 37% by mass was added and stirred for 1 hour to prepare the RF solution. After adding the above RF solution while stirring the above L solution, it was aged at 25°C for 1 week to prepare the second treatment agent. The third treatment agent (rubber paste) was prepared by dissolving the above NR / SBR-based adherend rubber in toluene (solid content concentration 6% by mass).

[0222] (Treatment process (immersion, drying, heat treatment)) The same stranded cords as in Example 1 were immersed in the first treatment agent (primer), and then dried at 150°C for 1 minute. Subsequently, they were immersed in the second treatment agent (RFL), dried at 150°C for 1 minute, and further heat-treated at 230°C for 1 minute. Subsequently, they were immersed in the third treatment agent (rubber paste), and then dried at 165°C for 4 minutes to obtain a treatment cord.

[0223] Table 7 shows the evaluation results of the peel test for the NR / SBR-based adherend rubber.

[0224] [Comparative Example 2] For Comparative Example 1, as shown in Table 6, only the third treatment agent (rubber paste) was changed. After dissolving the CR-based adherend rubber in toluene (solid content concentration: 10% by mass), this solution and the primer were mixed at a mass ratio of 6:4 to obtain a third treatment agent (solid content concentration: 10% by mass). The treated cords were manufactured by the same treatment process as in Comparative Example 1, and the results of the peel test are shown in Table 8.

[0225]

Table 6

[0226]

Table 7

[0227]

Table 8

[0228] In Example 1, the peel mode is rubber failure, and it can be judged that an adhesive film having sufficient adhesive strength and mechanical strength is formed, similar to the conventional three-bath treatment. Therefore, it is possible to manufacture an environmentally friendly core wire for a transmission belt that does not contain resorcinol, formaldehyde, bisphenol A, and reaction products thereof without degrading the quality of the transmission belt. It should be noted that even after rubber failure occurs once, a cut is made again with a cutter from the failure point to the interface between the adherend rubber and the cord, and it has been confirmed that the rubber failure still progresses.

[0229] Example 2 is an example in which the reactive compatibilizer of the second treatment agent is less than that in Example 1. Compared with Example 1, in the CR-based adherend rubber, the adhesiveness with the fiber decreased and fiber interface peeling occurred in part. However, even in Example 2, it is possible to manufacture an environmentally friendly core wire for a transmission belt while maintaining the quality of the transmission belt, similar to Example 1. Also, in the NR / SBR-based adherend rubber, it has been confirmed that even if a cut is made again after rubber failure occurs, the rubber failure still progresses, similar to Example 1.

[0230] Example 3 is an example in which the reactive compatibilizer of the second treating agent is more than that in Example 1. Compared with Example 1, the compatibility with non-polar rubber decreases, so the peel strength when the adherend rubber is NR / SBR decreases, but it is equal to or higher than that of CR-based adherend rubber. Also in Example 3, as in Example 1, it is possible to manufacture an environmentally friendly transmission belt core wire while maintaining the quality of the transmission belt. Further, as in Example 1, it has been confirmed that even if a cut is made again after rubber fracture occurs, the rubber fracture progresses.

[0231] Example 4 is an example in which the ratio of VP latex in the latex of the second treating agent is higher than that in Example 1. Compared with Example 1, the compatibility with non-polar rubber decreases, so the peel strength when the adherend rubber is NR / SBR decreases, but it is equal to or higher than that of CR-based adherend rubber. Also in Example 4, as in Example 1, it is possible to manufacture an environmentally friendly transmission belt core wire while maintaining the quality of the transmission belt. Further, as in Example 1, it has been confirmed that even if a cut is made again after rubber fracture occurs, the rubber fracture progresses.

[0232] Example 5 is an example in which the latex of the second treating agent is only VP latex. Similar to Example 4, the compatibility with non-polar rubber decreases, so the peel strength when the adherend rubber is NR / SBR decreases and rubber interface peeling occurs in part, but it is equal to or higher than that of CR-based adherend rubber. Also in Example 5, as in Example 1, it is possible to manufacture an environmentally friendly transmission belt core wire while maintaining the quality of the transmission belt. Further, in the case of CR-based adherend rubber, as in Example 1, it has been confirmed that even if a cut is made again after rubber fracture occurs, the rubber fracture progresses.

[0233] Example 6 is an example in which the VP latex in the first treating agent is less than that in Example 1. Compared with Example 1, the compatibility between the first adhesive film and the second adhesive film decreases, so the peel strength slightly decreases. Also in Example 6, as in Example 1, it is possible to manufacture an environmentally friendly transmission belt core wire while maintaining the quality of the transmission belt. Further, as in Example 1, it has been confirmed that even if a cut is made again after rubber fracture occurs, the rubber fracture progresses.

[0234] Example 7 is an example where the VP latex in the first treating agent is more than that in Example 1. Compared with Example 1, due to the insufficient strength of the first adhesive film, the adhesiveness to the fibers decreased. In particular, in the case of the CR-based adherend rubber, fiber interface peeling occurred partially. However, even in Example 7, similar to Example 1, it is possible to manufacture an environmentally friendly transmission belt core wire while maintaining the quality of the transmission belt. Also, in the case of the NR / SBR-based adherend rubber, similar to Example 1, it has been confirmed that even if a cut is made again after rubber failure occurs, it progresses to rubber failure.

Industrial Applicability

[0235] The transmission belt core wire obtained by the manufacturing method of the present invention is suitable for applications of transmission belts (for example, friction transmission belts such as V-belts and V-ribbed belts, meshing transmission belts such as toothed belts and double-sided toothed belts, etc.).

Explanation of Signs

[0236] 1... Adhesive tape 2... Treating cord 3... Crosslinked rubber 4... Reinforcing fabric

Claims

1. a first treatment step of treating an untreated yarn of a core wire for a power transmission belt with a first treating agent (A) containing a first aliphatic multifunctional epoxy compound (A1), a first blocked polyisocyanate (A2), and a first vinylpyridine-diene copolymer (A3) to obtain a first treated yarn; a second treatment step of treating the first treated yarn with a second treatment agent (B) containing a second aliphatic multifunctional epoxy compound (B1), a second blocked polyisocyanate (B2), a second vinylpyridine-diene copolymer (B3) and a reactive compatibilizer (B4) to obtain a second treated yarn; a heat treatment step of heating the second treated yarn at a temperature equal to or higher than the dissociation temperature of the first blocked polyisocyanate (A2) and the second blocked polyisocyanate (B2), The method for producing a core wire for a power transmission belt, wherein the first treatment agent (A) and the second treatment agent (B) do not contain resorcinol, formaldehyde, bisphenol A, or reaction products thereof.

2. the first treatment agent (A) and the second treatment agent (B) are aqueous treatment agents containing a hydrophilic solvent, In the first treatment step, the untreated yarn is immersed in the first treatment agent (A) and then dried; 2. The manufacturing method according to claim 1, wherein in the second treatment step, the first treated yarn is immersed in the second treatment agent (B) and then dried.

3. 3. The method according to claim 1, wherein the epoxy equivalent of each of the first aliphatic multifunctional epoxy compound (A1) and the second aliphatic multifunctional epoxy compound (B1) is 200 g / eq. or less.

4. The method according to claim 1 or 2, wherein the dissociation temperatures of the first blocked polyisocyanate (A2) and the second blocked polyisocyanate (B2) are each 160 to 250° C., and the blocking agent is a lactam.

5. The method according to claim 1 or 2, wherein the reactive compatibilizer (B4) comprises an acid-modified diene polymer.

6. the proportion of the first vinylpyridine-diene copolymer (A3) is 5 to 30 mass % of the solid content of the first treatment agent (A); the proportion of the second vinylpyridine-diene copolymer (B3) is 10 to 90 mass% of the solid content of the second treatment agent (B); 3. The method according to claim 1, wherein the proportion of the reactive compatibilizer (B4) is 0.5 to 20 mass % of the solid content of the second treatment agent (B).

7. 3. The method according to claim 1, wherein the second treatment agent (B) contains a rubber (B5) that is the same as or of the same type as a rubber of the power transmission belt that is in contact with the core wire.

8. 3. The method according to claim 1, wherein the rubber of the power transmission belt which is in contact with the core wire comprises at least one rubber selected from the group consisting of natural rubber, styrene-butadiene rubber and chloroprene rubber.

9. 3. The method according to claim 2, wherein the first treatment step and the second treatment step are two-bath treatments, and the first treatment agent (A) and the second treatment agent (B) do not contain a hydrophobic organic solvent.

10. 3. The method according to claim 1, wherein the untreated yarn is a twisted cord containing polyester fibers.

11. A treatment kit for treating untreated yarn of a core wire for a transmission belt, comprising: A first treating agent (A) containing a first aliphatic multifunctional epoxy compound (A1), a first blocked polyisocyanate (A2) and a first vinylpyridine-diene copolymer (A3); a second treatment agent (B) containing a second aliphatic multifunctional epoxy compound (B1), a second blocked polyisocyanate (B2), a second vinylpyridine-diene copolymer (B3) and a reactive compatibilizer (B4); and The treatment kit, wherein the first treatment agent (A) and the second treatment agent (B) do not contain resorcinol, formaldehyde, bisphenol A, or reaction products thereof.

12. A core wire for a transmission belt obtained by the method according to claim 1 or 2.

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