Glass fiber cord for rubber reinforcement, method for producing glass fiber cord for rubber reinforcement, and method for producing transmission belt

Abstract

The purpose of the present disclosure is to provide a glass fiber cord for rubber reinforcement, said glass fiber cord having low elongation. The present disclosure relates to a single-twisted glass fiber cord for rubber reinforcement, said glass fiber cord comprising: a strand formed by bundling 200 to 3,000 glass fiber filaments having an average fiber diameter of 3.0 to 15.0 μm; and a resin coating that covers the surface of the strand. The glass fiber cord for rubber reinforcement is single-twisted in only one direction 7 to 11 times per 10 cm.

Description

Glass fiber cord for rubber reinforcement, method for manufacturing glass fiber cord for rubber reinforcement, and method for manufacturing power transmission belt

[0001] The present disclosure relates to a glass fiber cord for reinforcing rubber, a method for manufacturing a glass fiber cord for reinforcing rubber, and a method for manufacturing a power transmission belt.

[0002] Rubber-reinforcing glass fiber cords are used to reinforce timing belts, which are toothed belts for automobiles, and power transmission belts, which are toothed belts for industrial use. Patent Document 1 describes an example of a rubber-reinforcing glass fiber cord, and the rubber-reinforcing glass fiber cord is obtained as follows.

[0003] First, an adhesive is applied to a glass fiber cord made of a large number of glass filaments bundled together, and the resulting cord is dried to obtain a strand. The strand is then first twisted. Furthermore, a plurality of the first twisted strands (11 strands in this example) are aligned and then second twisted. Patent Document 1 discloses a glass fiber cord for rubber reinforcement obtained by the above procedure.

[0004] International Publication No. 2006 / 001385

[0005] The rubber-reinforcing glass fiber cord obtained in Patent Document 1 has a problem in that it elongates greatly when stress is applied, and therefore a rubber-reinforcing glass fiber cord with less elongation has been desired.

[0006] An object of the present disclosure is to provide a glass fiber cord for rubber reinforcement that has low elongation.

[0007] The present disclosure is as follows.

[0008] The present disclosure (1) relates to a single-twisted glass fiber cord for rubber reinforcement, comprising: a strand formed by bundling 200 to 3,000 glass fiber filaments having an average fiber diameter of 3.0 μm or more and 15.0 μm or less; and a resin coating that covers the surface of the strand, wherein the glass fiber cord for rubber reinforcement is twisted only in one direction at 7 to 11 turns per 10 cm.

[0009] The present disclosure (2) relates to the glass fiber cord for rubber reinforcement according to the present disclosure (1), in which the resin constituting the resin coating contains an acrylonitrile-butadiene copolymer, a blocked isocyanate, and an epoxy resin.

[0010] The present disclosure (3) relates to a method for producing a single-twisted glass fiber cord for rubber reinforcement, including the steps of: attaching a sizing agent to glass fiber filaments having an average fiber diameter of 3.0 μm or more and 15.0 μm or less; bundling and converging 200 to 3,000 of the glass fiber filaments to form a strand; applying a glass fiber coating agent to the strand; heating the strand to which the glass fiber coating agent has been applied; and applying only single twists so that the number of twists is 7 to 11 per 10 cm.

[0011] The present disclosure (4) relates to the method for producing a glass fiber cord for rubber reinforcement according to the present disclosure (3), in which the sizing agent contains an aminosilane.

[0012] The present disclosure (5) relates to the method for producing a glass fiber cord for rubber reinforcement according to the present disclosure (3) or (4), wherein the coating agent contains an acrylonitrile-butadiene copolymer latex, a blocked isocyanate aqueous dispersion, and an epoxy resin aqueous dispersion.

[0013] The present disclosure (6) relates to a method for manufacturing a power transmission belt, including a step of attaching a sizing agent to glass fiber filaments having an average fiber diameter of 3.0 μm or more and 15.0 μm or less, a step of bundling and converging 200 to 3,000 of the glass fiber filaments to form a strand, a step of applying a glass fiber coating agent to the strand, a step of heating the strand to which the glass fiber coating agent has been applied, and a step of adding only one-way twist so that the number of twists is 7 to 11 per 10 cm, thereby obtaining a single-twisted glass fiber cord for rubber reinforcement, and a step of embedding the rubber-reinforcing glass fiber cord in rubber.

[0014] The present disclosure (7) relates to the method for producing a power transmission belt according to the present disclosure (6), wherein the rubber includes urethane rubber or hydrogenated nitrile rubber.

[0015] According to the present disclosure, a glass fiber cord for rubber reinforcement having low elongation can be provided.

[0016] Fig. 1 is a perspective view schematically showing a rubber-reinforcing glass fiber cord to which only one twist has been applied, and Fig. 2 is a perspective view schematically showing a rubber-reinforcing glass fiber cord to which second twist (plying) has been applied.

[0017] The present disclosure will be described in detail below, but the following description of the constituent elements is an example of an embodiment of the present disclosure, and the present disclosure is not limited to these specific details. Various modifications can be made within the scope of the gist of the present disclosure.

[0018] The glass fiber cord for rubber reinforcement according to the present disclosure is a glass fiber cord for rubber reinforcement comprising a strand formed by bundling 200 to 3,000 glass fiber filaments having an average fiber diameter of 3.0 μm or more and 15.0 μm or less, and a resin coating that covers the surface of the strand, and the glass fiber cord for rubber reinforcement is a single-twisted glass fiber cord for rubber reinforcement that is formed by twisting only one way at 7 to 11 times per 10 cm.

[0019] The rubber-reinforcing glass fiber cord comprises a strand in which 200 to 3,000 glass fiber filaments are bundled together.

[0020] In the strand, 200 to 3,000 glass fiber filaments are bundled together. When the number of glass fiber filaments is 200 or more, the strength of the glass fiber cord can be sufficiently increased. When the number of glass fiber filaments exceeds 3,000, when the strand is made into a transmission belt, the rubber-reinforcing glass fiber cord is likely to protrude from the end face of the produced transmission belt. Therefore, the number of glass fiber filaments is preferably 3,000 or less, more preferably 2,000 or less, and particularly preferably 1,000 or less. The number of glass fiber filaments is preferably 400 to 800.

[0021] The strand may be a plurality of filament bundles each including a large number of glass fiber filaments (for example, about 200 filaments) bundled together.

[0022] The glass fiber filaments are preferably bound together with a sizing agent, which may be a known sizing agent containing a surfactant, a silane coupling agent, a pH adjuster, a resin, or the like.

[0023] As the surfactant, known surfactants such as anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants can be used.

[0024] As the silane coupling agent, known silane coupling agents can be used, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 5,6-epoxyhexyltriethoxysilane, 5,6-epoxyhexyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-oxetanylpropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxy ... Examples thereof include 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrippropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltrippropoxysilane, ethyltriisopropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltrippropoxysilane, and propyltriisopropoxysilane.

[0025] Examples of pH adjusters include known acids and alkalis, such as inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, acetic acid, trifluoroacetic acid, methanesulfonic acid, phthalic acid, succinic acid, sodium hydroxide, calcium hydroxide, potassium hydroxide, ammonia, and choline.

[0026] The resin is preferably at least one selected from the group consisting of epoxy resin, polyurethane resin, polyamide resin, phenolic resin, and polyester resin.

[0027] The sizing agent preferably contains an aminosilane as a silane coupling agent, and more preferably contains γ-aminopropyltriethoxysilane.

[0028] The glass composition of the glass constituting the glass fiber filament is not particularly limited, and E-glass, high-strength glass (T-glass, S-glass, etc.), etc. can be used. An example of the glass composition of E-glass is SiO ２ 52 to 56% by weight, Al ２ O ３ 12 to 16% by weight, CaO and MgO total 20 to 25% by weight, R ２ O is 0 to 0.8 wt % (R is an alkali metal), B ２ O ３ An example of the glass composition of T-glass, which is a high-strength glass, is SiO ２ 64 to 66% by weight, Al ２ O ３ An example of the glass composition of S-glass, which is a high strength glass, is SiO ２ 64% by weight, Al ２ O ３ 25% by weight, MgO 10% by weight, Na ２ O+K ２ The O content is 0.3% by weight, and the balance is 0.7% by weight.

[0029] The average fiber diameter of the glass fiber filaments is 3.0 μm or more and 15.0 μm or less. This average fiber diameter is the fiber diameter as a product specification of the glass fiber filament. The average fiber diameter is measured by a measurement method in accordance with JIS R3420 (General Testing Methods for Glass Fibers). Specifically, the cross section of a strand impregnated with resin and cured is observed under a microscope, and the diameters of 25 randomly selected filament cross sections are measured. The number average of the 25 measurement results is defined as the average fiber diameter. Furthermore, when the cross section of the glass fiber filament is not a perfect circle, such as a flattened or elliptical shape, the diameter of the filament cross section is defined as the diameter of a circle (a perfect circle) having the same area as the cross section of the measured filament cross section. If the average fiber diameter is less than 3.0 μm, filament breakage is likely to occur during the production of the glass fiber filaments, leading to increased costs. Furthermore, if the average fiber diameter exceeds 15.0 μm, the flex fatigue resistance of the rubber-reinforcing glass fiber cord may be deteriorated.

[0030] The resin coating covers the surface of the strand. The resin is preferably a composition containing a rubber component, a crosslinking agent, and a pretreatment agent.

[0031] Examples of the rubber component include butadiene-styrene copolymer, dicarboxylated butadiene-styrene polymer, vinylpyridine-butadiene-styrene terpolymer, chloroprene, butadiene rubber, chlorosulfonated polyethylene, acrylonitrile-butadiene copolymer, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), carboxyl-modified nitrile rubber (X-NBR), and carboxyl-modified hydrogenated nitrile rubber (X-HNBR). Of these, acrylonitrile-butadiene copolymer is preferred.

[0032] Examples of crosslinking agents include aromatic or aliphatic organic diisocyanates, polyisocyanates, blocked isocyanates, and blocked polyisocyanates. Among these, blocked isocyanates are preferred. Furthermore, the crosslinking agent may further contain a crosslinking agent other than an isocyanate compound, such as a quinone dioxime crosslinking agent, a methacrylate crosslinking agent such as lauryl methacrylate or methyl methacrylate, an allyl crosslinking agent such as DAF (diallyl fumarate), DAP (diallyl phthalate), TAC (triallyl cyanurate), and TAIC (triallyl isocyanurate), a maleimide crosslinking agent such as bismaleimide, phenylmaleimide, and N,N'-m-phenylenedimaleimide, an aromatic nitroso compound, sulfur, and a peroxide.

[0033] Examples of the pretreatment agent include compounds containing at least one functional group selected from the group consisting of an epoxy group and an amino group, such as aminosilane, epoxysilane, and epoxy resins (novolac epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, brominated epoxy resins, bisphenol AD ​​epoxy resins, and glycidylamine epoxy resins).

[0034] The resin constituting the resin coating preferably contains an acrylonitrile-butadiene copolymer, a blocked isocyanate, and an epoxy resin. Such a coating resin can be formed from a coating agent containing an acrylonitrile-butadiene copolymer latex, an aqueous dispersion of blocked isocyanate, and an aqueous dispersion of epoxy resin. As the aqueous dispersion of blocked isocyanate, an ε-caprolactam block of diphenylmethane diisocyanate is preferably used, and as the aqueous dispersion of epoxy resin, a carboxy-modified self-emulsifying bisphenol A epoxy resin is preferably used.

[0035] The amount of resin coating applied can be expressed as the amount of organic matter applied to the rubber-reinforcing glass fiber cord. The amount of resin coating applied is preferably 16 parts by weight or more and 26 parts by weight or less, assuming that the entire rubber-reinforcing glass fiber cord is 100 parts by weight. When the amount of resin coating applied is 16 parts by weight or more, the adhesion between the rubber to be reinforced and the rubber-reinforcing glass fiber cord can be improved. If the amount of resin coating applied is too high, uneven adhesion may occur, or resin lumps may adhere during drying, resulting in poor appearance. Therefore, the amount of resin coating applied is preferably 26 parts by weight or less.

[0036] The rubber-reinforcing glass fiber cord is twisted only one way with 7 or more and 11 or less turns per 10 cm. The rubber-reinforcing glass fiber cord is twisted only one way with the strands in a resin-coated state, and by setting the number of one-way twists to 7 or more and 11 or less turns per 10 cm, it is possible to obtain a rubber-reinforcing glass fiber cord with small elongation when stress is applied. In particular, by using only one-way twist, it is possible to obtain a rubber-reinforcing glass fiber cord with small elongation when stress is applied, compared to a rubber-reinforcing glass fiber cord with the same average fiber diameter and number of glass fiber filaments but that is second-twisted (paired).

[0037] If the number of single twists is less than 7 times / 10 cm, the glass fibers will not be sufficiently aligned, which may cause loop defects in which some of the glass fibers protrude in a loop from the bundled cord.If the number of single twists is more than 11 times / 10 cm, the rubber-reinforcing glass fiber cord will elongate significantly when stress is applied.

[0038] The difference between a rubber-reinforcing glass fiber cord with only one twist and a rubber-reinforcing glass fiber cord with a second twist (plying) will be described with reference to the drawings. Fig. 1 is a perspective view schematically showing a rubber-reinforcing glass fiber cord with only one twist. Fig. 2 is a perspective view schematically showing a rubber-reinforcing glass fiber cord with a second twist (plying).

[0039] In a rubber-reinforcing glass fiber cord 1 shown in Fig. 1, a strand 20 formed by bundling glass fiber filaments 10 is coated with a resin coating 30 and is only one-way twisted. In a rubber-reinforcing glass fiber cord 2 shown in Fig. 2, a strand 21 formed by bundling glass fiber filaments 10 is coated with a resin coating 30 and is first twisted, and a strand 22 formed by bundling glass fiber filaments 10 is coated with a resin coating 30 and is first twisted. The strands 21 and 22, each resin-coated and first twisted, are then twisted together.

[0040] The preferred overall diameter (cord diameter) of the rubber-reinforcing glass fiber cord is 0.20 mm or more and 0.60 mm or less.

[0041] The rubber-reinforcing glass fiber cord of the present disclosure can be used to reinforce a power transmission belt. The rubber-reinforcing glass fiber cord is preferably embedded in the belt body along the longitudinal direction of the power transmission belt, and a plurality of rubber-reinforcing glass fiber cords are preferably embedded at intervals in the belt width direction.

[0042] A power transmission belt is a belt that transmits the driving force of a drive source such as an engine or motor in order to operate an engine or other machine. Examples of power transmission belts include toothed belts that transmit driving force through meshing transmission and V-belts that transmit driving force through friction transmission.

[0043] Examples of rubber that can be used to form the transmission belt include chloroprene rubber (CR), nitrile rubber, urethane rubber, hydrogenated nitrile rubber (HNBR), ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), styrene-butadiene rubber, butyl rubber, and chlorosulfonated polyethylene rubber. Of these, urethane rubber or hydrogenated nitrile rubber is preferred.

[0044] The rubber may contain various conventional additives (or compounding agents) as necessary. Examples of the additives include vulcanizing agents or crosslinking agents (e.g., oximes (e.g., quinone dioxime), guanidines (e.g., diphenyl guanidine), metal oxides (e.g., magnesium oxide, zinc oxide)), vulcanization aids, vulcanization accelerators, vulcanization retarders, reinforcing agents (e.g., silicon oxides such as carbon black and hydrated silica), metal oxides (e.g., zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide), fillers (e.g., clay, calcium carbonate, talc, mica), plasticizers, softeners (e.g., oils such as paraffin oil and naphthenic oil), processing agents or processing aids (e.g., stearic acid, metal stearates, wax, paraffin), antioxidants (e.g., aromatic amine-based and benzimidazole-based antioxidants), stabilizers (e.g., antioxidants, ultraviolet absorbers, heat stabilizers), lubricants, flame retardants, and antistatic agents. These additives can be used alone or in combination and can be selected depending on the type of rubber, application, performance, etc.

[0045] The manufacturing method of the rubber-reinforcing glass fiber cord of the present disclosure is described below. First, a sizing agent is applied to glass fiber filaments having an average fiber diameter of 3.0 μm or more and 15.0 μm or less. Then, 200 to 3,000 glass fiber filaments to which the sizing agent is applied are bundled and converged to form a strand. The process up to this point can be carried out continuously, for example, by spraying and applying a sizing agent to a large number of glass fiber filaments protruding from a bushing of a glass melting furnace, and converging them to form a strand. The glass fiber filaments and the sizing agent can be the same as those described above in this specification, and the sizing agent preferably contains an aminosilane, more preferably γ-aminopropyltriethoxysilane.

[0046] Alternatively, a filament bundle may be prepared by bundling a plurality of glass fiber filaments to which a sizing agent has been attached, and the resulting strand may be a plurality of filament bundles that are then pulled together. For example, a filament bundle may be prepared by bundling 200 glass fiber filaments, and 2 to 15 of these filament bundles may be pulled together to form a strand with a total of 400 to 3,000 fibers. The filament bundle is not twisted.

[0047] Furthermore, a glass fiber coating agent is applied to the strand. The glass fiber coating agent can be the same as that described above in this specification. The glass fiber coating agent preferably contains an acrylonitrile-butadiene copolymer latex, a water dispersion of a blocked isocyanate, and a water dispersion of an epoxy resin.

[0048] As the blocked isocyanate aqueous dispersion, it is preferable to use an ε-caprolactam blocked product of diphenylmethane diisocyanate, and as the epoxy resin aqueous dispersion, it is preferable to use a carboxy-modified self-emulsifying bisphenol A type epoxy resin.

[0049] The strand coated with the glass fiber coating agent is heated and dried to convert the glass fiber coating agent into a coating resin that coats the surface of the strand. The heating conditions are not particularly limited, but can be, for example, 200 to 300°C and 10 to 60 seconds.

[0050] Only one-way twisting is applied to the resin-coated strand so that the number of twists is 7 or more and 11 or less per 10 cm. A rubber-reinforcing glass fiber cord can be manufactured by the above steps. Furthermore, the one-way twisted rubber-reinforcing glass fiber cord may be further subjected to an overcoat treatment.

[0051] A method for producing a transmission belt according to the present disclosure will be described below. In the method for producing a transmission belt according to the present disclosure, a rubber-reinforcing glass fiber cord is produced by the rubber-reinforcing glass fiber cord production method according to the present disclosure. The obtained rubber-reinforcing glass fiber cord is then embedded in rubber, thereby producing the transmission belt according to the present disclosure.

[0052] The method for embedding the rubber-reinforcing glass fiber cord in the rubber is not particularly limited, and any known method can be used. The rubber to be embedded can be the same as those described above in this specification, and preferably includes urethane rubber or hydrogenated nitrile rubber.

[0053] The power transmission belt includes rubber-reinforcing glass fiber cords that are twisted only in one direction, and can be distinguished from power transmission belts that include rubber-reinforcing glass fiber cords that are twisted in two directions. A power transmission belt including rubber-reinforcing glass fiber cords that are twisted in two directions, 7 or more turns and 11 or less turns per 10 cm, has less elongation than a power transmission belt including rubber-reinforcing glass fiber cords that are twisted in two directions.

[0054] The present disclosure will be described in detail below using examples, but the present disclosure is not limited to these examples. The following components were used as materials. Sizing agent: γ-aminopropyltriethoxysilane (aminosilane). Glass fiber coating agent: The rubber component was an acrylonitrile-butadiene copolymer latex (solid content: 100 wt%), to which 2 to 15 wt% of an ε-caprolactam block of diphenylmethane diisocyanate (solid content) was added as a blocked isocyanate aqueous dispersion, and 2 to 10 wt% of a carboxy-modified self-emulsifying bisphenol A epoxy resin (solid content) was added as an epoxy resin aqueous dispersion. Glass fiber filament (E-glass): E-glass filament manufactured by Central Glass Fiber Co., Ltd., with an average fiber diameter of 9 μm. Glass fiber filament (high-strength glass): T-glass filament manufactured by Nitto Boseki Co., Ltd., with an average fiber diameter of 7 μm.

[0055] Example 1 A filament bundle was prepared by bundling 200 glass fiber filaments (E glass) with a sizing agent, and two of the filament bundles were aligned to form a strand. This strand was then coated with a glass fiber coating agent and placed in a heating furnace, heated at 280°C for 22 seconds, and twisted (primary twisted) 9 times per 10 cm to prepare a glass fiber cord for rubber reinforcement. The diameter of the glass fiber cord was 0.23 mm. This glass fiber cord for rubber reinforcement was only primary twisted and not ply-twisted, so it was a single-twisted glass fiber cord for rubber reinforcement that had only one twist added.

[0056] Examples 2 and 3, Comparative Examples 1 and 5 Single-twisted glass fiber cords for reinforcing rubber were produced in the same manner as in Example 1, except that the number of times of first twisting was changed.

[0057] Comparative Example 2 A filament bundle was prepared by bundling 200 glass fiber filaments (E glass) with a sizing agent, and one of the filament bundles was used as a strand. After being coated with a glass fiber coating agent, the strand was placed in a heating furnace and heated at 280°C for 22 seconds, followed by twisting (primary twisting) 9 times per 10 cm to prepare a primary twisted strand. Two similarly prepared primary twisted strands were twisted together in opposite twisting directions to prepare a rubber-reinforcing glass fiber cord.

[0058] Comparative Examples 3 and 4 Rubber-reinforcing glass fiber cords were produced in the same manner as in Comparative Example 2, except that the number of times of primary twisting and the number of times of plying were changed.

[0059] [Measurement of Tensile Strength and Measurement of Elongation at 75% at Break] Tensile strength measurements were performed using a tensile tester, TENSILON RTI-1310, manufactured by A&D Corporation. In the tensile tester, a rubber-reinforcing glass fiber cord was attached to clamps adjusted to a clamp distance of 250 mm, and a tensile test was performed at a speed of 250 mm / min, and the maximum resistance value until the test piece broke was defined as the tensile strength (N). The stress-strain (elongation) curve was measured simultaneously with the tensile strength measurement, and the elongation (%) at 75% of the stress at break (elongation length (%) based on the length at the start of measurement) was read.

[0060] [Verification of product appearance] Product appearance: It was visually confirmed that the manufactured rubber-reinforcing glass fiber cord was free of stains and loops, and if there were no problems, it was rated as "good." In Comparative Example 5, loops (a defective mode in which the glass fibers were not sufficiently aligned and some of the glass fibers protruded in a loop shape from the bundled cord) occurred.

[0061] The test conditions and evaluation results of the examples and comparative examples using glass fiber filaments (E glass) are shown in Table 1.

[0062] Example 4 A filament bundle was prepared by bundling 200 glass fiber filaments (high-strength glass) with a bundling agent, and four of these filament bundles were aligned to form a strand. This strand was then coated with a glass fiber coating agent and placed in a heating furnace, heated at 280°C for 22 seconds, and twisted (primary twisted) 7 times per 10 cm to prepare a glass fiber cord for rubber reinforcement. The diameter of the glass fiber cord was 0.27 mm. This glass fiber cord for rubber reinforcement was only primary twisted and not ply-twisted, so it was a single-twisted glass fiber cord for rubber reinforcement that had only one twist added.

[0063] Examples 5 and 6, Comparative Example 6 Single-twisted glass fiber cords for reinforcing rubber were produced in the same manner as in Example 4, except that the number of times of first twisting was changed.

[0064] Comparative Example 7 A filament bundle was prepared by bundling 200 glass fiber filaments (high-strength glass) with a sizing agent, two of the filament bundles were aligned to form a strand, a glass fiber coating was applied, and the strand was placed in a heating furnace and heated at 280°C for 22 seconds, followed by twisting (primary twisting) 7 times per 10 cm to prepare a primary twisted strand. Two similarly prepared primary twisted strands were twisted together in opposite twisting directions to prepare a rubber-reinforcing glass fiber cord.

[0065] Comparative Example 8 A rubber-reinforcing glass fiber cord was produced in the same manner as in Comparative Example 7, except that the number of times of primary twisting and the number of times of plying were changed.

[0066] Table 2 shows the test conditions and evaluation results for the examples and comparative examples using glass fiber filaments (high strength glass).

[0067]

[0068] As shown in Tables 1 and 2, the glass fiber cords for rubber reinforcement in each Example in which only one-sided twisting of 7 turns or more and 11 turns or less per 10 cm was added had high tensile strength and a small amount of elongation at 75% at break, and were able to achieve both high tensile strength and small amount of elongation.

[0069] In Comparative Examples 1 and 6, only one-sided twist of 13 turns / 10 cm was applied, but the tensile strength was lower and the elongation was larger than those of the corresponding Examples. In Comparative Example 5, only one-sided twist of 5 turns / 10 cm was applied, but loop defects occurred and the cord was in a state that could not be used as a glass fiber cord for rubber reinforcement. In Comparative Examples 2 to 4 and 7 to 8, ply twist was applied, but the tensile strength was lower and the elongation was larger than those of the corresponding Examples.

[0070] 1, 2: Glass fiber cord for rubber reinforcement 10: Glass fiber filament 20, 21, 22: Strand 30: Resin coating

Claims

1. A single-twist glass fiber cord for rubber reinforcement, comprising a strand formed by bundling 200 to 3,000 glass fiber filaments having an average fiber diameter of 3.0 μm to 15.0 μm, and a resin coating covering the surface of the strand, wherein the glass fiber cord for rubber reinforcement is twisted only in one direction at 7 to 11 turns per 10 cm.

2. The glass fiber cord for rubber reinforcement according to claim 1, wherein the resin constituting the resin coating contains an acrylonitrile-butadiene copolymer, a blocked isocyanate, and an epoxy resin.

3. A method for manufacturing a single-twisted glass fiber cord for rubber reinforcement, comprising: a step of attaching a sizing agent to glass fiber filaments having an average fiber diameter of 3.0 μm or more and 15.0 μm or less; a step of bundling and converging 200 to 3,000 of the glass fiber filaments to form a strand; a step of applying a glass fiber coating agent to the strand; a step of heating the strand to which the glass fiber coating agent has been applied; and a step of adding only single twists so that the number of twists is 7 to 11 per 10 cm.

4. The method for producing a glass fiber cord for rubber reinforcement according to claim 3, wherein the sizing agent contains an aminosilane.

5. The method for producing a glass fiber cord for rubber reinforcement according to claim 3 or 4, wherein the coating agent contains an acrylonitrile-butadiene copolymer latex, a water dispersion of blocked isocyanate, and a water dispersion of epoxy resin.

6. A method for manufacturing a power transmission belt, comprising the steps of: attaching a sizing agent to glass fiber filaments having an average fiber diameter of 3.0 μm or more and 15.0 μm or less; bundling and converging 200 to 3,000 of the glass fiber filaments to form a strand; applying a glass fiber coating to the strand; heating the strand to which the glass fiber coating has been applied; and adding only one-way twist so that the number of twists is 7 to 11 per 10 cm, thereby obtaining a single-twisted glass fiber cord for rubber reinforcement; and embedding the glass fiber cord for rubber reinforcement in rubber.

7. The method for producing a transmission belt according to claim 6, wherein the rubber includes urethane rubber or hydrogenated nitrile rubber.

Images