JPH11193849A - Power transmitting belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a belt, when running in a high- temperature atmosphere and a low-temperature atmosphere, by using ethylene- alpha-olefin elastomer for a compression rubber layer subjected to repeating compression and deformation when the belt runs and improving an adhesive layer. SOLUTION: Ethylene-alpha-olefin elastomer is used as an adhesive rubber layer 3 for a power transmitting belt 1 to form sulfide of sulfur cross-linkage available rubber composition and ethylene-alpha-olefin elastomer is used as a compression rubber layer 4 to form cross-linkage of organic peroxide cross- linkage available rubber composition.

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 such as a V-ribbed belt or a V-belt. The present invention also relates to a power transmission belt having excellent weather resistance.

[0002]

2. Description of the Related Art In recent years, due to social demands for energy saving and compactness, the ambient temperature around an engine room of an automobile has been increasing as compared with the related art. As a result, the operating temperature of the power transmission belt has been increasing. Conventionally, natural rubber, styrene-butadiene rubber, and chloroprene rubber have been mainly used for power transmission belts. However, in a high-temperature atmosphere, a problem has occurred in that a crack is generated in a cured compressed rubber layer at an early stage.

[0003] In response to such an early breakage phenomenon of the belt,
Improvement of the heat resistance of chloroprene rubber has been studied,
Although some improvements have been made, there is a limit as long as chloroprene rubber is used, and at present no sufficient effect has been obtained.

[0004] For this reason, the use of rubbers having a highly saturated or completely saturated main chain, such as chlorosulfonated polyethylene rubber, hydrogenated nitrile rubber, and fluoro rubber, which are excellent in heat resistance, has been studied. . Of these, chlorosulfonated polyethylene is generally equivalent to chloroprene rubber in terms of dynamic fatigue resistance, abrasion resistance and oil resistance, but it is known that the vulcanization system, especially the acid acceptor, has a large effect on water resistance. Have been. Usually, oxides such as MgO and PbO have been used as acid acceptors for chlorosulfonated polyethylene.

However, PbO, Pb_ThreeO_FourEtc. of lead compounds
If an acid acceptor is used, a belt with good water resistance can be obtained.
However, use of lead compounds is preferred due to pollution and hygiene issues.
Absent. When MgO is used as an acid acceptor,
MgCl generated during the bridge reaction _TwoSignificantly impairs water resistance
In short, adaptation to the belt was inappropriate. Meanwhile, metal
Use an epoxy acid acceptor as an acid acceptor other than oxides
If it is, it is possible to obtain a composition having good water resistance
However, there is a problem of odor and the like, which causes discomfort to human body
was there.

[0006]

However, this power transmission belt has a significantly improved belt running life in a high-temperature atmosphere as compared with a belt using chloroprene rubber, and has excellent heat resistance. It became clear that the running life of the belt in a low temperature atmosphere of -30 ° C or less was significantly inferior. The reason for this is that conventional chlorosulfonated polyethylene rubber is a chlorosulfonated polyethylene, which contains chlorine, so that the cohesive energy of chlorine increases at low temperatures and the rubber hardens in the low temperature range, causing the rubber to harden. This is presumed to be due to lack of elasticity and easy cracking.

On the other hand, ethylene-alpha-olefin elastomers such as ethylene-propylene rubber (EPR) and ethylene-propylene-diene rubber (EPDM) have excellent heat resistance and cold resistance, and Although it is an inexpensive polymer, it does not have oil resistance, so it is not actively used for such applications. V
In the case of dry friction transmission such as a ribbed belt, a large amount of oil is slipped when a large amount of oil is applied, and the transmission function is impaired. Thus, the transmission has been rarely used, but has recently been studied. It has been disclosed.

However, the ethylene-propylene rubber has a low tearing power, and the use of a peroxide cross-linking system further lowers the tearing power, so that there is a problem that the cord tends to pop out during running. On the other hand, in the case of using a sulfur cross-linking system, it is difficult to sufficiently increase the degree of vulcanization, so that the abrasion increases during running. This was a major problem that caused pronunciation. In addition, when EPDM having an extremely large amount of double bonds in the molecule is used to increase the degree of vulcanization, adhesive wear can be improved to some extent, but heat resistance deteriorates.

The present invention addresses this problem by using an ethylene-alpha-olefin elastomer for the compressed rubber layer that is repeatedly undergoing compression deformation during belt running, and by improving the adhesive layer. An object of the present invention is to provide a power transmission belt in which heat resistance and cold resistance are improved and the durability of the belt during traveling in a high-temperature atmosphere and a low-temperature atmosphere is improved.

[0010]

According to the present invention, there is provided a power transmission belt in which at least an adhesive rubber layer having a core wire embedded therein and a compression rubber layer are laminated, wherein the adhesive rubber layer is ethylene-alpha. -Power using a vulcanizate of a sulfur crosslinkable rubber composition using an olefin elastomer and a crosslinked product of an organic peroxide crosslinkable rubber composition using an ethylene-alpha-olefin elastomer as a compressed rubber layer In the transmission belt.

According to the invention of claim 2 of the present application, the power transmission belt is composed of an adhesive rubber having a core buried along the belt longitudinal direction and a compressed rubber layer having at least one rib portion along the belt longitudinal direction. V-ribbed belt.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A V-ribbed belt 1 shown in FIG.
A core wire 2 made of a high-strength, low-elongation cord made of polyester fiber, aramid fiber, or glass fiber is embedded in an adhesive rubber layer 3, and a compression rubber layer 4 as an elastic layer is provided below the core wire. doing. The compressed rubber layer 4 is provided with a plurality of rib portions 7 having a substantially triangular cross section extending in the longitudinal direction of the belt, and a rubber attached fabric 5 attached to the surface of the belt.

Ethylene used for the compressed rubber layer 4
A typical example of the alpha-olefin elastomer is EPDM, which is a rubber composed of an ethylene-propylene-diene monomer. Examples of diene monomers include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene, and the like. Also, ethylene-propylene rubber (EPR) can be used.

For crosslinking of the rubber, an organic peroxide is used. For example, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, 1,3-bis (t -Butylperoxyisopropyl) benzene, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexyne-3,
2,5-dimethyl-2,5- (benzoylperoxy)
Hexane, 2,5-dimethyl-2,5-mono (t-butylperoxy) hexane and the like can be mentioned. This organic peroxide is used alone or as a mixture in the range of 0.005 to 0.02 mol g per 100 g of the ethylene-alpha-olefin elastomer.

By blending a crosslinking assistant (co-agent), the degree of crosslinking can be increased to prevent problems such as adhesive wear. Examples of the crosslinking aid include TIAC, TAC, 1,2 polybutadiene, metal salts of unsaturated carboxylic acids, oximes, guanidine, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, NN′-m- It is usually used for peroxide crosslinking such as phenylene bismaleimide and sulfur.

If necessary, ordinary rubbers such as carbon black, reinforcing agents such as silica, fillers such as calcium carbonate and talc, plasticizers, stabilizers, processing aids and coloring agents. What is used in the formulation is used.

Short fibers made of nylon 6, nylon 66, polyester, cotton, and aramid are mixed into the compressed rubber layer 4 to improve the lateral pressure resistance of the compressed rubber layer 4 and to be in contact with the pulley. The short fibers protrude from the surface of the compressed rubber layer 4 to reduce the friction coefficient of the compressed rubber layer 4 and reduce noise during belt running. Of these staple fibers, aramid staple fibers having rigidity, strength and abrasion resistance are most effective.

In order for the aramid short fiber to sufficiently exhibit the above-mentioned effects, the fiber length of the aramid fiber should be 1 to 20.
In mm, the amount is 1 to 30 parts by weight per 100 parts by weight of the ethylene-alpha-olefin elastomer. The aramid fiber is an aramid having an aromatic ring in its molecular structure, such as, for example, Conex, Nomex, Kevlar, Technora, Twaron and the like.

If the amount of the aramid short fiber is less than 1 part by weight, the rubber of the compressed rubber layer 4 tends to stick and wears out. It is not evenly dispersed in rubber. However, the addition of this aramid short fiber is not essential, and may be the one to which short fibers made of other materials are added.

The compressed rubber layer 4 has an ethylene-alpha-olefin elastomer and a fiber diameter of 1.0 μm or less, preferably 0.05 to 500 parts by weight, based on 100 parts by weight of the ethylene-alpha-olefin elastomer as a matrix rubber. The fiber may contain 1 to 50 parts by weight, preferably 5 to 25 parts by weight of a short fiber reinforced rubber grafted with 0.8 µm short fibers. If the blending amount of the short microfiber reinforced rubber is less than 1 part by weight, abrasion resistance is not sufficient, and if it exceeds 50 parts by weight, elongation of the rubber composition is reduced, and heat resistance and bending resistance are reduced.

Since the ethylene-alpha-olefin elastomer constituting the microshort fiber reinforced rubber is completely the same as or similar to the ethylene-alpha-olefin elastomer of the matrix rubber of the compressed rubber layer 4, the matrix has Good bonding with rubber. For this reason, between the micro short fiber reinforced rubber and the matrix rubber,
Alternatively, since the ethylene-alpha-olefin elastomer and the short microfibers are chemically bonded even in the short microfiber reinforced rubber, cracks are not easily formed in the compressed rubber layer 4, and even if cracks are generated, they are hardly propagated.

In the above micro-short fiber reinforced rubber, the interface between the micro-short fibers and the ethylene-alpha-olefin elastomer is a coupling agent such as vinyl tris (β
-Methoxyethoxy) silane, vinyltriethoxysilane, silane coupling agents such as γ-methacryloxypropyltrimethoxysilane, titanate coupling agents such as isopropyltriisostearoyl titanate, acrylic acid, methacrylic acid, and maleic acid And unsaturated carboxylic acid, or a novolak-type phenol resin, and the like, which is grafted through an adhesive such as an ethylene-alpha-olefin elastomer and fine short fibers, and an adhesive such as a coupling agent. Is obtained by kneading and extruding at a temperature higher than or equal to the melting point.

The short microfiber reinforced rubber has a rubber component as a continuous phase in which the short microfibers are dispersed in a fine form, and the short microfibers form a strong chemical bond or interaction with the rubber component at the interface. ing. For this reason, the rubber layer containing this hardly cracks, and even if the cracks do not easily propagate. Moreover, the belt using this also has excellent heat resistance, cold resistance, bending resistance, and abrasion resistance.

On the other hand, the above-mentioned ethylene-alpha-olefin is used for the adhesive rubber layer 3 so as to have heat resistance and to improve the adhesion to the polyester fiber, aromatic polyamide fiber, glass fiber and the like which are core wires. An elastomeric rubber composition that can be crosslinked with sulfur is used. And, if necessary, carbon black, a reinforcing agent such as silica, a filler such as calcium carbonate and talc, a plasticizer, a stabilizer, a processing aid, and a usual rubber compound such as a coloring agent are used. Things are used.

The ethylene-alpha-olefin elastomer used for the adhesive rubber layer 3 is EPDM.
Has an iodine value of 4 or more and less than 40, and when it is less than 4, crosslinking of the rubber composition with sulfur is not sufficient, and a problem of pop-out of the cord occurs. On the other hand, if it exceeds 40,
The scorch of the rubber composition becomes short, making it difficult to handle, and the heat resistance becomes poor. Further, the short microfiber reinforced rubber can be added.

The amount of sulfur added to the adhesive rubber layer 3 depends on the amount of the ethylene-alpha-olefin elastomer 10
It is 0.5 to 3.0 parts by weight with respect to 0 parts by weight.

The core wire is subjected to an adhesive treatment for the purpose of improving the adhesiveness with rubber. As such an adhesive treatment, it is common to immerse the fiber in resorcin-formalin-latex (RFL solution) and then heat and dry to form an adhesive layer uniformly on the surface. However, without being limited to this, after pretreatment with an epoxy or isocyanate compound, R
There is also a method of treating with an FL solution.

The method of mixing the above components is not particularly limited, and for example, kneading can be carried out using a Banbury mixer, a kneader, or the like by a known method and method as appropriate.

One example of a method for manufacturing a V-ribbed belt is as follows. First, one or a plurality of cover canvases and an adhesive rubber layer are wrapped around the peripheral surface of a cylindrical forming drum, and then a core wire made of a rope is helically spun on this, and then a compressed rubber layer is sequentially wound. After applying to obtain a laminate, the laminate is crosslinked with sulfur or an organic peroxide to obtain a crosslinked sleeve.

Next, the bridging sleeve is hung on a driving roll and a driven roll, and is run under a predetermined tension. Further, the rotated grinding wheel is moved so as to abut the running bridging sleeve to compress the bridging sleeve. 3 to 100 on rubber layer surface
The plurality of groove portions are polished at a time.

The bridging sleeve obtained in this manner is removed from the driving roll and the driven roll, and the bridging sleeve is hung on another driving roll and the driven roll to run, cut into a predetermined width by a cutter, and individually cut. Finish the V-ribbed belt.

Further, in the present invention, in addition to the above-mentioned V-ribbed belt, a V-belt 8 having a rubber-attached cloth attached to only the upper and lower surfaces of the belt as shown in FIG. 2 is also included. The V-belt 8 has a core wire 2 embedded in an adhesive rubber layer 3 and a compression rubber layer 4 as an elastic body layer below the core wire 2. Cogs may be provided on the compressed rubber layer 4 at predetermined intervals along the longitudinal direction.

[0033]

The present invention will be described in more detail with reference to the following examples.

In the V-ribbed belt manufactured in this embodiment,
A cord made of polyester fiber rope is buried in the adhesive rubber layer, and a ply of cotton sewing cloth with a sewing machine joint is placed on the upper side thereof, and a compressed rubber layer is provided below the adhesive rubber layer to form three layers. The rib has the belt in the longitudinal direction. The obtained V-ribbed belt has a length of 9 according to the RMA standard.
A 75 mm K-type 3-ribbed belt with a rib pitch of 3.
56mm, rib height 2.9mm, belt thickness 5.3m
m, and the rib angle is 40 °.

Here, the compressed rubber layer and the adhesive rubber layer were prepared from the rubber compositions shown in Table 1, respectively, kneaded with a Banbury mixer, and then rolled with calender rolls. The compressed rubber layer contains short fibers and is oriented in the belt width direction.

[0036]

[Table 1]

The method of manufacturing the belt is a conventional method known in the art. First, a one-ply sewing machine jointed cotton canvas with rubber is wound around a flat cylindrical mold,
After winding the adhesive rubber layer, spinning the core wire, and setting the compression rubber layer, a crosslinking jacket is inserted on the compression rubber layer. Next, put the molding mold in a vulcanizing can,
After cross-linking, the process comprises removing the cylindrical cross-linked sleeve from the mold, forming the compressed rubber layer of the sleeve into ribs with a grinder, and cutting the molded body into individual belts.

The V-ribbed belt thus obtained was evaluated for the presence or absence of adhesive wear by a peeling test of the adhesive rubber and the core wire, a heat-resistant running test, and a running test at room temperature. The results are shown in Tables 2 and 3.

First, in the peeling test, two core wires of the above-mentioned V-ribbed belt were peeled off at a speed of 50 mm / min under an ambient temperature of 23 ° C. and 120 ° C. using a strograph T.

The running test machine used for the evaluation of the heat resistant running test includes a driving pulley (120 mm in diameter), a driven pulley (120 mm in diameter), and an idler pulley (70 m in diameter).
m) and a tension pulley (diameter: 45 mm). A belt is hung on each pulley of the testing machine, the ambient temperature is 120 ° C., the number of rotations of the driving pulley is 49
The driven pulley was driven at 12 horsepower at 00 rpm, and the tension pulley was run with an initial tension of 57 kgf.

The idler pulley is engaged at the back of the V-ribbed belt 1, and its wrapping angle is about 90 degrees. By this running test method, the time until cracks occurred in the rib portions of the belt was measured, and the heat resistance performance was compared.

In the evaluation of the presence or absence of adhesive wear by a running test at room temperature, a driving pulley (120 m in diameter) was used as a running test machine.
m), a driven pulley (diameter 120 mm), an idler pulley (diameter 85 mm) and a tension pulley (diameter 4 mm).
5 mm), the rotation speed of the driving pulley is 4900 rpm, and the tension pulley is 8 mm.
The vehicle was run with an initial tension of 5 kgf.

[0043]

[Table 2]

[0044]

[Table 3]

As is clear from the results of Tables 2 and 3, a rubber composition of an organic peroxide-crosslinkable ethylene-propylene rubber was used for the rib portion, and the sulfur-crosslinkable ethylene-propylene rubber was used for the adhesive rubber layer. It can be understood that the belt of the present invention using the rubber composition of the present invention increases the adhesive force between the core wire and the adhesive rubber layer as compared with the conventional belt, improves the belt life under a high-temperature atmosphere, and hardly causes adhesive wear. .

[0046]

As described above, according to the present invention, a vulcanizate of a sulfur crosslinkable rubber composition using an ethylene-alpha-olefin elastomer as an adhesive rubber layer, and an ethylene-alpha-olefin as a compression rubber layer. This is a power transmission belt that uses a crosslinked product of an organic peroxide crosslinkable rubber composition using an olefin elastomer, which increases the adhesive strength between the core wire and the adhesive rubber layer, and improves the belt life in a high-temperature atmosphere. In addition, there is an effect that adhesive abrasion hardly occurs.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a V-ribbed belt according to the present invention.

FIG. 2 is a vertical sectional view of a V-belt according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 V-ribbed belt 2 core wire 3 adhesive rubber layer 4 compression rubber layer 5 canvas with rubber 7 rib

Claims (2)

[Claims] 1. A power transmission belt in which at least an adhesive rubber layer embedded with a core wire and a compressed rubber layer are laminated, a sulfur crosslinkable rubber composition using an ethylene-alpha-olefin elastomer as the adhesive rubber layer is added. A power transmission belt using a crosslinked product of a sulfur composition and an organic peroxide crosslinkable rubber composition using an ethylene-alpha-olefin elastomer as a compression rubber layer. 2. The power transmission belt according to claim 1, wherein the power transmission belt is a V-ribbed belt including an adhesive rubber having a core buried along a longitudinal direction of the belt and a compressed rubber layer having at least one rib portion along the longitudinal direction of the belt. Item 7. A power transmission belt according to Item 1.