JP2003240056A - Power transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission belt with high strength, high modulus, small deterioration of strength of the belt after running, and excellent bending fatigue resistance. <P>SOLUTION: This toothed belt 1 is equipped with a plurality of teeth 2 along a belt longitudinal direction; a belt body comprising a back part 4 with core wires 3 as a reinforcing core member embedded spirally on a belt pitch line of the belt body; and a base cloth 5 adhered on the surface of the teeth 2. The core wire 3 is a strand cord obtained by twisting strands constituted with polyparaphenylenebenzobisoxazole fiber and those constituted with glass fiber. The strands of the above fiber serve as a core part 7, and those of glass fiber serve as a skin part 6. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission belt, and more particularly to a power transmission belt suitable for a drive unit that requires high strength and high modulus performance.

[0002]

2. Description of the Related Art Generally, transmission belts such as toothed belts, V-belts and V-ribbed belts have a cord embedded in a main body made of a rubber composition as a reinforcing core. The cord is a member that bears most of the belt tension, and its characteristics are determined by the type of fiber and the number of twists, the twist direction, the fineness, and other combinations. As the fiber type constituting the cord, a twisted cord composed of high modulus fibers such as polyester, glass and aramid fibers is generally used.

As a usage layout of these transmission belts, for example, a toothed belt, it has been generally practiced to hang the belt on a drive shaft and a driven shaft and to provide a tensioner to maintain a constant tension. However, in recent years, due to the demand for smaller installation space due to the downsizing of equipment and the reduction in the number of parts due to cost reduction, it is often the case that the tensioner cannot be installed and it is often used in layouts where the shafts are fixed. There is a demand for a belt with less number of belts. There is also a demand for narrower belts as the apparatus becomes more compact.

However, when a conventional belt is examined, a transmission belt using a polyester fiber cord has very good bending fatigue resistance but poor dimensional stability.
There is a problem that high positioning accuracy cannot be obtained. Further, the transmission belt using the aramid fiber cord has characteristics such as high strength and excellent bending fatigue resistance, but there is a problem that dimensional change with time due to moisture absorption is large.

On the other hand, a power transmission belt using a glass fiber cord has characteristics that it is excellent in dimensional stability and dimensional stability over time. However, with the recent advancements in the functionality and performance of precision equipment, the demands for strength and modulus have further increased.If the cord fineness is set higher than the general-purpose value in order to meet these demands, the bending fatigue resistance will increase. There was a problem that it decreased. In addition, if a wide belt is designed to increase the number of core wires embedded in the main body, there is also an adverse effect that it goes against the space saving of the engine room.

Against this background, polyparaphenylene benzobisoxazole fibers (PBO fibers), which have higher modulus and strength than conventional general-purpose fibers, have recently attracted attention. In particular, in strength and elastic modulus, it exceeds aramid fiber. Therefore, in the industrial belt industry, by using this PBO fiber as a core wire, high strength and high modulus can be achieved without increasing the fineness of the cord and the space of the engine room. It is expected that a new power transmission belt can be provided. However, since the PBO fiber has almost no functional groups in its molecular skeleton, it has poor adhesiveness to rubber as compared with conventional short fibers, and it is considered difficult to realize a cord-rubber composite. It was

Therefore, in order to improve the adhesiveness with rubber,
It has been proposed to subject PBO fibers to a special bonding treatment. For example, in Japanese Unexamined Patent Publication No. 9-176332, after treatment with a first treatment liquid composed of an epoxy compound, rubber latex, and a heat-reactive water-soluble urethane resin, a second treatment liquid composed of resorcin, formalin, and rubber latex is used. A technique for improving the adhesiveness with rubber by treating is disclosed.

[0008]

However, even if the above-mentioned technique is applied to PBO short fibers, the adhesive force with the rubber composition is not sufficiently satisfactory, and there is a problem in practical use. A belt used in a layout with a fixed axial distance is required to have a small dimensional change over time and a low rate of decrease in tension after running. However, considering a conventional belt made of PBO fiber, It was found that there was a problem in flex fatigue resistance.

The present invention has been made in view of the above points, and provides a power transmission belt which has high strength and high modulus, has a small decrease in belt strength after running, and satisfies excellent bending fatigue resistance. To do.

[0010]

That is, the invention according to claim 1 of the present application is a power transmission belt comprising an adhesive rubber layer in which a core wire is embedded along the longitudinal direction of the belt, and a compression rubber layer. The wire is a cord composed of polyparaphenylenebenzobisoxazole fiber and glass fiber, and is characterized in that the polyparaphenylenebenzobisoxazole fiber serves as a core portion and the glass fiber serves as a skin portion.

The invention according to claim 2 of the present application is the power transmission belt according to claim 1, wherein the core wire is made of polyparaphenylenebenzobisoxazole fiber and a glass rope is made of glass fiber. The twisted cord is a twisted cord obtained by twisting together, wherein the child rope made of polyparaphenylene benzobisoxazole fiber is constituted as a core portion, and the child rope made of glass fiber is constituted as a skin portion.

The invention according to claim 3 of the present application is characterized in that, in the power transmission belt according to claim 1 or 2, the skin portion and the core portion are constituted by using a flyer twisting machine.

The invention according to claim 4 of the present application is characterized in that, in the power transmission belt according to any one of claims 1 to 3, the power transmission belt is a toothed belt.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a toothed belt 1 according to the present invention.
Indicates. The toothed belt 1 is composed of a plurality of tooth portions 2 along the longitudinal direction of the belt and a belt body composed of a back portion 4 in which a core wire 3 as a reinforcing core is spirally embedded on a belt pitch line of the belt body, A base cloth 5 is attached to the surface of the tooth portion 2.

The base cloth 5 is a base cloth selected from woven fabric, knitted fabric, non-woven fabric and the like. As the fiber material that constitutes the base cloth,
Known publicly available ones can be used, for example, natural fibers such as cotton and hemp, inorganic fibers such as metal fibers and glass fibers, and polyamide, polyester, polyethylene, polyurethane, polystyrene, polyfluoroethylene, polyacryl, polyvinyl alcohol, Organic fibers such as wholly aromatic polyester and aramid are listed, and they are plain weave, twill weave,
It is preferable to use a woven fabric such as satin weave.

Although the form of the fiber is not limited to spun yarn, multifilament yarn, monofilament yarn, etc., the monofilament yarn is used as the constituent yarn to increase the unevenness due to the intersection of the warp and the weft, thereby lowering the surface friction coefficient. When it is made to show, it shows favorable wear resistance and tooth chipping resistance. Other than that, lowering the weaving density and using fibers with a large diameter are also effective means for lowering the surface friction coefficient. Further, during molding by the press-fitting method used as a known technique, shrinkage is required in the weft direction of the base fabric,
The weft yarn along the longitudinal direction of the belt body is crimped 6
It is preferable to use nylon or 66 nylon, or a composite yarn twisted with a urethane elastic yarn. Also base cloth 5
When a monofilament yarn is used for the warp yarn, it is preferable to use it for the warp yarn because it does not affect the shrinkability in the weft direction.

The base cloth 5 is made of resorcinol according to a known technique.
After dipping in the formalin-latex liquid (RFL liquid), rubbing the unvulcanized rubber on the base cloth 5 is performed, or after dipping in the RFL liquid, dipping treatment is performed in a soaking liquid in which the rubber is dissolved in a solvent. Alternatively, the adhesion treatment may be performed only with the RFL liquid.

The RFL solution is a mixture of an initial condensate of resorcin and formalin and rubber latex, and a molar ratio of resorcin and formalin is preferably 1: 0.5 to 3 in order to enhance the adhesive force. is there. The initial condensate of resorcin and formalin was mixed with the latex so that the resin content was 10 to 100 parts by weight with respect to 100 parts by weight of the rubber content of the latex, and the total solid content concentration was 5 to 40. It is adjusted so that it becomes a% concentration. RFL
A carbon black solution may be appropriately mixed with the solution to blacken the treated fabric, or a known surfactant may be added in an amount of 0.1 to 5.0% by weight. Examples of the latex include styrene-butadiene-vinylpyridine terpolymer, chlorosulfonated polyethylene, hydrogenated nitrile rubber, epichlorohydrin, natural rubber, SBR, chloroprene rubber, olefin-vinyl ester copolymer, EPDM and the like. Examples include latex.

The belt body composed of the back portion 4 and the tooth portion 2 is formed of a rubber layer and is made of natural rubber (N
R), styrene-butadiene rubber (SBR), chloroprene rubber (CR), chlorosulfonated polyethylene (C)
SM), alkylated chlorosulfonated polyethylene (A
CSM), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), hydrogenated nitrile rubber mixed with unsaturated carboxylic acid metal salt, ethylene propylene diene monomer (EPDM), butyl rubber (IIR), etc. The rubbers used may be used alone or in a blend. Alternatively, polyurethane rubber may be used in addition to these rubbers. Above all, in the case of a toothed belt, it is desirable to use a rubber having an improved heat aging resistance, and in the case of a hydrogenated nitrile rubber, the hydrogenation rate is 80% or more, and the heat resistance and ozone resistance characteristics are exhibited. Therefore, 90% or more is more preferable. Hydrogenation rate 8
If the hydrogenated nitrile rubber content is less than 0%, the heat resistance and ozone resistance are extremely lowered.

A reinforcing agent such as carbon black, a filler, a softening agent, an antioxidant, a vulcanization aid, and a vulcanizing agent such as sulfur or organic peroxide are added to and mixed with the rubber. It When an organic oxide is blended as a cross-linking agent, in order to secure a predetermined modulus (tensile elastic modulus) and cutting elongation, 0.2 to 10 parts by mass of the organic peroxide is added to 100 parts by mass of the polymer component. It is necessary to mix parts and crosslink. The organic peroxide is not particularly limited, but specifically, di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, 1,1-t-butyl peroxy-3,3. , 5-Trimethylcyclohexane, 2,5-di-methyl-2,5-di (t-butylperoxy) hexane, 2,5-di-methyl-2,5-di (t-butylperoxy) hexane-3, bis ( t-butylperoxydi-isopropyl) benzene,
2,5-di-methyl-2,5-di (benzoylperoxy) hexane, t-butylperoxybenzoate, t-
Butyl peroxy-2-ethyl-hexyl carbonate and the like can be used. In addition to such organic peroxides, metal oxides, sulfur compounds, oxime nitroso compounds, and monomers and polymers generally used as co-crosslinking agents may be added in appropriate amounts.

The core wire 3 is a cord composed of polyparaphenylene benzobisoxazole fiber (PBO fiber) and glass fiber, and the PBO fiber is the core portion 7 and the glass fiber is the skin portion 6. Code is used. The composition of the glass core wire may be either E glass or S glass (high strength glass), and is not limited to the thickness of the filament, the number of filaments converged, and the number of strands. Further, it is not limited to an adhesive treatment agent, a sizing agent used as a protective material for a glass filament at the time of bending, an RFL, an overcoat agent and the like. The PBO fiber is obtained by spinning a polymer obtained by polycondensing diaminoresorcinol and terephthalic acid in a polyphosphoric acid solvent. It has higher physical property values than conventional general-purpose fibers, and exhibits strength and elastic modulus higher than that of aramid fibers in mechanical properties, for example.
However, since it has almost no functional groups in its molecular skeleton, it has a problem that it is more difficult to adhere to rubber than conventional fibers. Therefore, by arranging the glass fiber in the cord surface layer, that is, the skin portion 6, the adhesive force between the cord and the rubber is improved, and by arranging the PBO fiber in the cord core portion, that is, the core portion 7, high strength and high modulus can be achieved. And

Specifically, the core wire 3 is P as shown in FIG.
A twisted cord obtained by twisting a child rope 8 made of BO fiber and a child rope 9 made of glass fiber. The child rope 8 made of PBO fiber is made of a core portion 7 and glass fiber. What is constructed so that the child rope 9 becomes the skin portion 6 is used. The core wire is produced using, for example, a flyer twisting machine.

In the cord, the fineness of the PBO fiber rope is 200 to 1,700 dtex, the fineness of the glass fiber rope is 400 to 3,500 dtex, and the total fineness is 4,000.
It is preferable to set to be about 12,000 dtex in order to extend the belt life. The number of upper twists of the cord is preferably 50 to 120 times / m, and the number of lower twists of the cord is 50 to 200 for the rope made of PBO fiber.
It is desirable to set the number of turns / m and the length of the rope made of glass fiber to 50 to 200 times / m. In addition, it is also possible to provide middle twist between the upper twist and the lower twist. The upper twist is preferably twisted in the opposite direction to the lower twist, that is, plied.

The core wire 3 is subjected to an adhesive treatment for the purpose of improving adhesiveness with rubber. As such an adhesion treatment, fibers are resorcin-formalin-latex (RF
After being immersed in the liquid L), it is generally heated and dried to uniformly form an adhesive layer on the surface. However, the method is not limited to this, and there is also a method of performing pretreatment with an epoxy or isocyanate compound and then treating with an RFL solution.

As a concrete method, the untreated cord is impregnated with a pretreatment liquid selected from an epoxy compound and an isocyanate compound to be pre-dipped, and then 160 to 20.
It is dried by passing it through a drying oven set at a temperature of 0 ° C. for 30 to 600 seconds, and subsequently impregnated with an adhesive treatment made of RFL liquid.
After this, it is also possible to carry out a post-treatment with a rubber paste.
The processing procedure is not limited to the above. For example, pre-dip-processed child rope may be twisted to form a cord, and the cord may be subjected to RFL treatment. When pre-dip treatment is applied to the child rope, the same pre-dip processing may be applied to each child rope of PBO and glass fiber, or different pre-dip processing may be applied to each child rope, or only one of the child ropes is pre-dipped. May be applied. The PBO fiber is preferably subjected to a pre-dip treatment with a pretreatment liquid containing a nitrile rubber-modified epoxy resin, an alkylphenol / formaldehyde resin, a cross-linking agent, and a solvent in order to enhance the adhesive strength.

Examples of epoxy compounds include polyhydric alcohols such as ethylene glycol, glycerin and pentaerythritol, reaction products of polyalkylene glycols such as polyethylene glycol and halogen-containing epoxy compounds such as epichlorohydrin, resorcin,
It is a reaction product with a polyhydric phenol such as bis (4-hydroxyphenyl) dimethylmethane, a phenol / formaldehyde resin, a resorcin / formaldehyde resin, or a halogen-containing epoxy compound. This epoxy compound is used by mixing it with an organic solvent such as toluene or methyl ethyl ketone. Examples of the isocyanate compound include 4,4′-diphenylmethane diisocyanate,
There are 2,4-diisocyanate, P-phenyl diisocyanate, polyaryl polyisocyanate, and the like. This isocyanate compound is also used as a mixture with an organic solvent such as toluene or methyl ethyl ketone.

The latex used in the RFL solution here is chloroprene, styrene / butadiene / vinyl pyridine terpolymer, hydrogenated nitrile, NBR or the like.

The cord processed as described above has a spinning pitch, that is, a winding pitch of the core wire of 1.0 to 1.
By setting the thickness to 3 mm, a belt with a high modulus can be finished. If the length is less than 1.0 mm, the cord will ride on the adjacent cord and cannot be wound.
If it exceeds 3 mm, the modulus of the belt gradually decreases.

The toothed belt is generally manufactured by a press-fitting molding method. That is, a canvas forming a tooth cloth is wound around a cylindrical mold having a groove portion corresponding to the tooth portion of the toothed belt to be formed, a rope serving as a core wire is spirally wound in order, and further on that. Wrap an unvulcanized rubber sheet forming the teeth and back. By moving the mold into a vulcanizing can and heating and pressurizing it, the rubber sheet is pressed into the groove portion of the mold to form the tooth portion. Each of the toothed belts can be obtained by cutting the obtained sleeve-shaped molded product into slices with a cutter according to a predetermined width.

The present invention can be applied to transmission belts such as V-belts and V-ribbed belts, in addition to the above-mentioned toothed belt.

[0031]

EXAMPLES The present invention will be described in more detail with reference to specific examples. Example 1 As a core wire, as shown in Table 1, one bundle of PBO fiber multifilaments (brand name: Zylon) of 545 dtex
Was prepared and dipped in the pre-dip solution shown in Table 2, then 2
It heat-processed at 00 degreeC for 1 minute. Next, after being immersed in the RFL solution shown in Table 3, it was further heat-treated at 230 ° C. for 1 minute. This treated raw yarn was twisted 120 times / m to obtain a PBO fiber strand. Further, ECG-150 glass fibers were prepared, and three glass fibers were aligned and immersed in the RFL solution shown in Table 3, and then heat-treated at 230 ° C. for 1 minute. The treated raw yarn was twisted 120 times / m to obtain a glass fiber strand.
Then, four PBO child ropes and nine glass child ropes are twisted into various twists using a flyer twisting machine, then immersed in the treatment liquid shown in Table 5 and heat treated at 160 ° C for 3 minutes to obtain a treatment cord. Was produced.

Comparative Example 1 As a core wire, as shown in Table 1, a bundle of glass fibers of ECG-150 was prepared, and three glass fibers were aligned and immersed in the RFL solution shown in Table 3 and then at 230 ° C. And heat treated for 1 minute. The treated raw yarn was twisted 120 times / m to obtain a glass fiber strand. Then, the 13 cords were twisted into various twists, dipped in the treatment liquid shown in Table 5 and heat-treated at 160 ° C. for 3 minutes to prepare a treated cord.

Comparative Example 2 As a core wire, as shown in Table 1, one bundle is 1,090 dte.
x PBO fiber multifilament (trade name: Zylo
n) was prepared, immersed in the pre-dip solution shown in Table 2, and then heat-treated at 200 ° C. for 1 minute. Next, R shown in Table 3
After soaking in FL liquid, heat treatment at 230 ° C for 1 minute, and then twisting the treated raw yarn 45 times / m to PB.
It was made of O fiber rope. Then, after twisting the three strands into a rung twist, the strands are dipped in the treatment liquid shown in Table 5 to 160 ° C.
Then, heat treatment was performed for 3 minutes to prepare a treated cord.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

Next, a toothed belt was produced using the above cord. A canvas made of RFL-treated aramid fibers was set in a mold into an endless tube having wefts in the circumferential direction so that the warps were along the width direction of the belt. By winding so as to be arranged at a pitch of 5 mm, and further by rolling a rolled sheet made of the rubber composition shown in Table 4 from above, pressurizing and vulcanizing,
A sleeve-shaped molded product was produced. By cutting this into a predetermined width, the belt width is 19.1 mm and the tooth pitch is 8 m.
A toothed belt with m and 99 teeth was obtained. And the following performance was tested.

1. Treated Cord Tensile Strength The treated cord tensile strength was measured based on JIS L1071.

2. Treated cord peeling force The treated fiber cords are arranged in two dense arrangements and pressure-bonded to the rubber compound shown in Table 4 at a temperature of 153 ° C. and a pressure of 2 MPa for 30 minutes, and then cut into a width of 25 mm, a length of 140 mm and a thickness of 4 m.
A sheet-shaped sample of m was prepared. The flat peeling force was measured at room temperature using a tensile tester to evaluate the adhesive force between the treated cord and rubber.

3. Belt strength The belt was pulled at a speed of 50 mm / min to determine the maximum load when the belt was cut.

4. The SS curve of the belt modulus belt was created, and the slope of the straight line portion of the SS curve was calculated.

5. Belt Strength Retention Rate A running test was carried out for 200 hours in a room temperature atmosphere according to the layout shown in FIG. 3, and then the strength of the belt after running was measured. Then, the belt strength after running was divided by the belt strength before running to obtain the belt strength retention rate.

As a result, the toothed belt of Example 1 using the core wire in which the child rope made of polyparaphenylene benzobisoxazole fiber is the core portion and the child rope made of the glass fiber is the skin portion, Compared with the toothed belt of Comparative Example 1 using a core made of glass fiber, it has excellent tensile strength and belt modulus even with the same belt width, and has substantially the same belt strength retention rate. Was confirmed. That is, it is understood that the embodiment is a belt suitable for the demand for space saving. Further, it was confirmed that Comparative Example 2, which is composed of the PBO fiber strand alone, has an extremely low adhesive force between the rubber and the core wire, but the Example shows extremely excellent adhesiveness.

[0046]

As described above, in the invention described in the claims of the present application, in the power transmission belt including the adhesive rubber layer having the core wire embedded along the belt longitudinal direction and the compression rubber layer, the core wire is A cord composed of polyparaphenylene benzobisoxazole fiber and glass fiber,
A power transmission belt characterized by comprising a polyparaphenylene benzobisoxazole fiber as a core portion and a glass fiber as a skin portion, which has high strength and high modulus, and a decrease in belt strength after running is small, It has the effect of satisfying excellent flex fatigue resistance.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view of a toothed belt according to the present invention.

FIG. 2 is a sectional view of a core wire used in the power transmission belt according to the present invention.

FIG. 3 is a layout of a running test device for a toothed belt.

[Explanation of symbols]

1 toothed belt 2 teeth 3 cores 4 back 5 base cloth 6 skin part 7 core part 8 Child rope (PBO fiber) 9 Baby rope (aramid fiber)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4F072 AB07 AB09 AB24 AD02 AE01                       AE02 AF24 AF31 AG03 AH21                       AJ04 AL19

Claims (4)

[Claims] 1. A power transmission belt comprising an adhesive rubber layer in which a core wire is embedded along the longitudinal direction of the belt, and a compression rubber layer, wherein the core wire is composed of polyparaphenylene benzobisoxazole fiber and glass fiber. A power transmission belt, wherein the cord is a polyparaphenylene benzobisoxazole fiber and the glass fiber is a skin portion. 2. The cord is a twisted cord formed by twisting a strand made of polyparaphenylene benzobisoxazole fiber and a strand made of glass fiber, which is a polyparaphenylene benzobisoxazole fiber. 2. The power transmission belt according to claim 1, wherein the child rope made of is a core portion, and the child rope made of glass fiber is a skin portion. 3. A skin part, using a flyer twisting machine,
The power transmission belt according to claim 1 or 2, which constitutes a core portion. 4. The power transmission belt according to claim 1, wherein the power transmission belt is a toothed belt.