JP3296641B2 - Fiber cord for rubber reinforcement and power transmission belt using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber reinforcing fiber cord and an improvement of a power transmission belt using the same, and more particularly to a measure for improving physical properties such as heat resistance, water resistance and bending fatigue resistance.

[0002]

2. Description of the Related Art In recent years, demands for improving the life and reliability of a power transmission belt have been increasing. As such a transmission belt, a toothed belt is widely used in various fields. Particularly, an OHC driving toothed belt used for an automobile engine is used under a high load and with multiple shafts, and is subjected to a high temperature condition of 100 to 140 ° C. due to heat of the engine. In addition, rain may enter the engine room due to the weather during traveling, and may be in a highly humid condition due to the synergy with the heat of the engine. There is a problem that the service life of the toothed belt is shortened due to such severe conditions.

As one mode of shortening the service life of the toothed belt, the adhesive layer of the fiber cord, which is a belt tensile member, is broken, or the interface between the fiber cord and the adhesive is broken. In many cases, it leads to the cutting of the belt. Causes of this include cracking of the adhesive layer due to repeated tensile compression stress applied to the belt, cracking of the adhesive layer due to deterioration of the adhesive due to high temperature conditions, water absorption and swelling of the adhesive due to high humidity conditions, tearing, and interface with fibers. It could be destruction.

[0004] Therefore, in order to increase the service life of the toothed belt under severe conditions, improvement of physical properties such as bending fatigue resistance, heat resistance and water resistance of the adhesive layer are important factors.

[0005] By the way, the conventional rubber compound constituting the belt body is bonded to the fiber cord by treating the fiber cord with an RFL solution (a mixture of a resorcin-formalin (RF) condensate and a rubber latex (L)). It is performed by close vulcanization with a vulcanized rubber compound. To improve adhesiveness, heat resistance and bending fatigue resistance, the ratio of R / F,
Various types of latex have been proposed and implemented.

For example, in order to improve heat resistance and water resistance, treatment with RFL using a hydrogenated nitrile rubber (H-NBR) latex having high heat resistance (Japanese Patent Application Laid-Open No.
Further, in order to satisfy bending fatigue resistance and heat resistance, the first layer is treated with RFL using a heat-resistant latex such as H-NBR latex, and the second layer is formed of flexible vinyl pyridine. (Vp) Treatment with RFL using latex, styrene butadiene rubber (SBR) latex, etc. (JP-A-1-213478)
Japanese Patent Application Laid-Open No. Hei 1-2221433), in order to satisfy flex fatigue resistance and heat resistance, a treatment is carried out with RFL using a blend of Vp latex and chlorosulfonated polyethylene rubber (CSM). ) Etc. are performed.

[0007]

However, HN
The RFL using BR has the above-mentioned problem because the RFL film lacks flexibility. Further, when a glass fiber cord is used for the tensile member, voids are generated in the glass fiber cord due to inferior convergence of the filament group, which causes a problem. RFL (L = H-NBR) / RFL (L = V
In the case of performing the two-layer treatment of p), as long as Vp latex is used, the heat resistance is not sufficient, and the following problem occurs.
Further, the cost is increased because the two-layer processing is performed using different materials. RFL blended with CSM and Vp latex is intended to improve flex fatigue resistance. However, since CSM has low water resistance and Vp lacks heat resistance, the following problem remains.

That is, at present, there is no treatment agent which can solve all of the three problems of the above-mentioned bending fatigue resistance, heat resistance and water resistance.

The present invention has been made in view of the above points, and an object of the present invention is to provide rubber latex with H
-By using NBR latex to increase the heat resistance of the fiber cord, and by using other additives in combination with this,
Also improves the bending fatigue resistance and water resistance of the fiber cord, and when used as a tension member of a power transmission belt, the adhesive layer breaks due to mechanical fatigue during belt running, and the adhesive due to thermal aging that occurs in the running environment An object of the present invention is to prevent the adhesive layer from being cracked due to heat curing damage and wet aging of the layer and to greatly improve the belt life.

[0010]

In order to achieve the above object, a first solution of the present invention is to provide a resorcin-formalin condensate, a hydrogenated nitrile rubber (H-NBR) latex and a softening point of 100 ° C. or lower. The fiber cord for rubber reinforcement is treated with a treatment liquid containing a tackifier as a main component.

[0011] A second solution of the present invention is to provide resorcinol.
Formalin condensate, hydrogenated nitrile rubber (H-NBR)
A rubber reinforcing fiber cord treated with a treatment liquid containing latex and a tackifier having a softening point of 100 ° C. or lower as a main component is embedded in the belt body.

The resorcinol-formalin (RF) condensate has a polymerization ratio of resorcinol to formalin of 1:
0.5 to 1: 3 mol ratio, preferably 1: 1 to 1: 2 mol
l ratio. The mixing ratio of the RF resin and the hydrogenated nitrile rubber (H-NBR) latex was 1: 5 in solid content.
１ ： 1: 20 wt ratio. Preferably, when organic fibers are used as the tensile member of the transmission belt, the weight ratio is 1: 5 to 1:10 wt.
When the glass fiber is used, the ratio is 1:10 to 1:20 wt.

H-NBR constituting the latex used in the present invention is obtained by hydrogenating a conjugated diene unit portion of an unsaturated nitrile-conjugated diene copolymer rubber; unsaturated nitrile-conjugated diene-ethylene type unsaturated monomer. Hydrogenated conjugated diene units of three-dimensional copolymer rubbers or unsaturated nitrile-ethylenically unsaturated monomer copolymer rubbers (COO
HH-NBR). In the unsaturated nitrile-ethylene type unsaturated monomer copolymer rubber, a part of the unsaturated monomer is vinyl norbornene, dicyclopentadiene,
A copolymer obtained by substitution with a non-conjugated diene such as 1,4-hexadiene may be used.

The H-NBR is specifically hydrogenated butadiene-acrylonitrile copolymer rubber, isoprene-butadiene-acrylonitrile copolymer rubber, isoprene-acrylonitrile conjugated diene rubber, etc .; butadiene-methyl acrylate-acrylonitrile copolymer rubber Butadiene-acrylic acid-acrylonitrile copolymer rubber and hydrogenated products thereof; butadiene-ethylene-acrylonitrile copolymer rubber, butyl acrylate-ethoxyethyl acrylate-vinyl chloroacetate-acrylonitrile copolymer rubber, butyl acrylate-ethoxy ethyl acrylate -Vinyl norbornene-acrylonitrile copolymer rubber and the like, which can be obtained by using a usual polymerization technique and a usual hydrogenation method.

As the latex, a latex in a state where polymerization has been completed may be used, or a latex obtained by dissolving solid rubber in a solvent and dispersing in water (called post-emulsification) may be used.

The tackifier used in the present invention has a softening point of 100 ° C. or lower, and is not particularly limited as long as it has compatibility with RFL. . For example, rosin, modified rosin (polymerized rosin, partially hydrogenated rosin), derivative of rosin modified rosin (glycerin ester rosin, partially hydrogenated rosin of glycerin ester rosin, fully hydrogenated rosin and polymerized rosin, pentaerythritol ester rosin, penta Partially hydrogenated rosin and polymerized rosin of erythrit ester rosin, polyterpene resin (α-pinene polymer, β-pinene polymer, dipentene polymer), modified terpene (terpene phenol, α-pinene-phenol copolymer) , Aliphatic hydrocarbon resin (olefin and diolefin polymer), cyclopentadiene resin, aromatic petroleum resin, phenol resin (alkylphenol and modified phenol), alkylphenol-acetylene resin, styrene resin, xylene resin, cumarone indene Fat, and vinyl toluene -α-methyl styrene copolymer. Among them, rosin derivatives, terpene phenols, and coumarone indene resins are preferably used.

Since these tackifying resins are usually insoluble in water, they are used as a water dispersion using a surfactant or the like. The aqueous dispersion may be prepared by a conventional method, for example, using a ball mill or a homogenizer.

When the treating agent of the present invention is used as a treating agent for a belt tensile member, if necessary, a vulcanizing agent (sulfur, zinc white, etc.), a vulcanization accelerator, an antioxidant, a softening agent, a plasticizer, Agents, carbon black, silica, fillers, dispersants, emulsifiers, stabilizers, thickeners and the like can be appropriately compounded. Those that do not dissolve in water are used as an aqueous dispersion. In some cases, the tensile body may be previously treated with a treating agent such as an isocyanate compound or an epoxy compound which improves the adhesiveness. The epoxy compound and isocyanate compound used here may be any commonly used epoxy compound or isocyanate compound. The outer layer of the fiber cord treated with the treating agent of the present invention may be overcoated.

The rubber reinforcing fiber cord is treated with the treatment liquid as described above. When the treated rubber reinforcing fiber cord is used as a belt tensile member, it is embedded in the belt body. Thus, a transmission belt is formed.

Typical examples of the rubber reinforcing fiber cord as the belt tensile member include cotton, polyvinyl alcohol fiber, aliphatic and aromatic polyamide fiber, polyester fiber, carbon fiber, glass fiber, metal fiber and the like. Although it is not particularly limited, it includes all fibers conventionally used for bonding with rubber.

The rubber constituting the belt body of the power transmission belt may be either natural rubber or synthetic rubber, and is not particularly limited. For example, acrylonitrile-butadiene copolymer rubber, chlorosulfonated Examples include polyethylene rubber and hydrogenated nitrile rubber.

As the vulcanization system, any vulcanization system of an organic peroxide, a metal oxide or sulfur may be used, and an accelerator may be used. The material may be any known material, and is not particularly limited.

For example, in the case of an organic peroxide, di-t-
Butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α′-bis (t-butylperoxy) -p-diisopropylbenzene, 2,
5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyldi (t-butylperoxy)
Hexin-3,2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyisopropyl carbonate, 1,1-bis (t-butylperoxy) -3,5,5-trimethyl Cyclohexane and the like can be mentioned.

Other vulcanizing agents include vulcanizing agents such as sulfur and triazines, vulcanizing accelerators such as thiazoles, dithiocarbamates, thiurams and thioureas, alkylphenol resins and brominated alkylphenols. Resin vulcanizing agents such as resin and NN'-m-phenylenedimaleimide can be mentioned.

In addition to the above-mentioned vulcanizing agents, the rubber compound may further contain various reinforcing fillers, anti-aging agents, plasticizers, vulcanization aids, and processing agents which are generally known as rubber compounds. An appropriate amount such as an auxiliary agent may be contained.

In order to treat the above-mentioned treating agent to the fiber cord for rubber reinforcement, a usual dipping method may be used. Further, by performing this treatment at a stage before the final twist is applied to the rubber reinforcing fiber cord, more uniform impregnation and coating between the filaments is achieved.

Then, the above-mentioned treatment liquid is processed into a fiber cord for reinforcing rubber, and this is vulcanized and adhered to a rubber layer as a belt tensile member, so that the back rubber layer 1 and the back rubber layer are bonded as shown in FIG. A plurality of belt tension members (core wires) 4 are embedded in the back rubber layer 1 of the belt body 3 composed of a plurality of tooth rubber layers 2 integrally formed on one surface of the rubber layer 1. A toothed belt A as a transmission belt in which the tooth cloth 5 is integrally adhered to the tooth surface of the second gear with an adhesive (not shown) can be obtained.

[0028]

According to the above arrangement, in the first solution of the present invention, the heat resistance of the rubber reinforcing fiber cord is improved by the hydrogenated nitrile rubber (H-NBR) latex in the treatment liquid. Furthermore, the tackifier keeps the flexibility of the adhesive layer of the fiber cord for rubber reinforcement before and after thermal aging, reduces the water absorption of the RFL coating, and makes the rubber cord for rubber reinforcement less susceptible to wet tearing. Thereby, a fiber cord for rubber reinforcement satisfying all of bending fatigue resistance, heat resistance and water resistance can be obtained.

In the second solution of the present invention, the rubber reinforcing fiber cord as described above is embedded in the belt main body, so that the adhesive layer is damaged due to mechanical fatigue during belt running, and the heat generated in the running environment. The thermosetting failure of the adhesive layer due to aging and the tearing of the adhesive layer due to wet aging are prevented, and the belt life is greatly improved.

[0030]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Glass fiber strands (filament diameter 9 μm, counts 15000 to 2250) were treated with the treatment solutions shown in Table 1.
(0 yards / pound) so that the solids adhesion rate becomes 18%, heat-treated at 250 ° C. for 1 minute, and then twisted in a predetermined number to twist the glass for rubber reinforcement of the present example and comparative example. A fiber cord was obtained. Using this glass fiber cord as a belt tensile member (core wire) 4, a toothed belt A as shown in FIG. 1 was produced. Table 2 shows the rubber composition of the belt body 3 (back rubber layer 1, tooth rubber layer 2). Using this toothed belt A, a belt bending test was performed in the following manner, and the data are shown in Table 1. Further, the properties of the RFL coating of the glass fiber cord in this example and the comparative example were measured in the following manner, and the results are shown in Table 3.

As is clear from Table 1, Comparative Examples 1 and 2 in which tackifiers having softening points of 100 ° C. and 75 ° C. were added as treatment agents for the belt tensile member (core wire) 4 were used. ~ 5
It can be seen that the belt life is significantly improved as compared with the case of FIG. As is apparent from Table 1 and 3, the water-resistant belt life is extended, lower the water absorption of RFL coating, elongation at break after heat aging (E _B) it can be seen that also has higher retention.

[0033]

[Table 1]

<Procedure of Belt Bending Test> The toothed belt A is connected to four large pulleys 11 of a belt bending tester shown in FIG.
Four small pulleys 12 arranged between adjacent large pulleys 11
(Diameter: 30 mm), and the weighted belt A was subjected to bending at a bending frequency of 5 × 10 ⁷ times in a water-resistant bending test in a state where a tension of 40 kgf was applied to the toothed belt A. Was examined. At this time, water was dropped on the tooth bottom of the toothed belt A at a rate of 1 liter per hour.
In the heat aging bending test, the heat aging condition was 150 ° C. × 168.
After heat aging at hrs, the belt was run while bending at a bending frequency of 1 × 10 ⁸ times, and then the belt strength retention rate was examined. The toothed belt A used in this test had the structure shown in FIG. 1, the belt width was 19 mm, the belt body 3 was H-NBR,
The tooth cloth 5 is a nylon canvas.

[0035]

[Table 2]

<Procedure for measuring RFL film characteristics> After preparation of the RFL film, it was dried at 40 ° C for 15 hours and then dried at 280 ° C.
It was heat-treated for 2.5 minutes and pressed at 160 ° C for 30 minutes.
The tensile strength was measured with an Instron at a tensile speed of 500 mm / min. The water absorption is 3cm ×
The sheet was cut into a 3 cm sheet, immersed in warm water at 70 ° C., and the weight change before and after that was measured.

[0037]

[Table 3]

[0038]

As described above, according to the first aspect of the present invention, the fiber cord for reinforcing rubber is made of a resorcinol-formalin condensate, a hydrogenated nitrile rubber (H-NBR) latex and a softening point of 100 ° C. or less. The H-NBR latex makes it possible to improve the heat resistance of the fiber cord for rubber reinforcement. In addition, the tackifier can maintain the flexibility of the adhesive layer of the rubber reinforcing fiber cord before and after thermal aging, and reduce the water absorption of the RFL coating to make the rubber reinforcing fiber cord less susceptible to wet tearing. Can be. Therefore, it is possible to obtain a fiber cord for rubber reinforcement satisfying all of bending fatigue resistance, heat resistance and water resistance.

According to the second aspect of the present invention, the rubber reinforcing fiber cord as described above is embedded in the belt body.
Adhesive layer breakage due to mechanical fatigue during belt running, thermosetting damage of the adhesive layer due to thermal aging that occurs in the running environment, and tearing of the adhesive layer due to wet aging can be prevented, greatly improving belt life. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of a toothed belt.

FIG. 2 is a configuration diagram of a belt bending tester.

[Explanation of symbols]

 3 Belt body 4 Belt tensile member (fiber cord for rubber reinforcement) A Toothed belt (transmission belt)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F16G 1/08 F16G 1/08 A // B29K 21:00 B29K 21:00 105: 08 105: 08

Claims (2)

(57) [Claims] 1. A fiber cord for reinforcing rubber, which is treated with a treatment liquid containing a resorcin-formalin condensate, a hydrogenated nitrile rubber latex and a tackifier having a softening point of 100 ° C. or lower as main components. 2. A fiber cord for rubber reinforcement, which is treated with a treatment liquid mainly containing a resorcinol-formalin condensate, a hydrogenated nitrile rubber latex and a tackifier having a softening point of 100 ° C. or less, is embedded in a belt body. A power transmission belt, characterized in that: