JPH04211748A - Power transmission belt - Google Patents

Abstract

PURPOSE:To obtain a power transmission belt having a durability during running thereof under a high or low temperature condition by improving the composition of a compression rubber layer which is subjected to repetitions of compressive deformation during running of the belt so as to enhance the heat resistance and cold resistance thereof. CONSTITUTION:In a power transmission belt composed of an adhesive rubber layer 3 in which core wires are embedded, and a resilient layer including a compression rubber layer 4, a rubber composition made of low density polyethylene having a straight chain molecular structure chlorosulfonized so the content of chlorine falls in a range of 15 to 35wt.% preferably 25 to 35wt.% and the content of sulfur falls within 5 to 2.5wt.% is used for the compression rubber layer 4 in the resilient layer. Further, chloroprene rubber or hydride nitrite rubber is used for the adhesive rubber layer 3.

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 made of a V-ribbed belt or a V-belt, which significantly improves the running life of the belt in high-temperature and low-temperature environments.

0002

BACKGROUND OF THE INVENTION In recent years, against the backdrop of social demands for energy saving and compactness, the ambient temperature around the engine compartment of automobiles has been rising compared to the past. Along with this, the operating environment temperature of power transmission belts has also become higher. Conventionally, natural rubber, styrene-butadiene rubber, and chloroprene rubber have been mainly used for power transmission belts, but there has been a problem that early cracks occur in the hardened compressed rubber layer in a high-temperature atmosphere.

[0003] In response to such early belt failure phenomenon,
Improvements in the heat resistance of chloroprene rubber have been studied for some time.
Although some improvements have been made, there are limitations as long as chloroprene rubber is used, and sufficient effects have not yet been achieved.

For this reason, the use of rubbers with highly saturated or completely saturated main chains, such as chlorosulfonated polyethylene rubber, hydrogenated nitrile rubber, and fluororubber, which have excellent heat resistance, is being considered. . Among 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 water resistance is greatly affected by the vulcanization system, especially the acid acceptor. ing. Generally, oxides such as MgO and PbO have been used as acid acceptors for chlorosulfonated polyethylene.

[0005] However, if a lead compound acid acceptor such as PbO or Pb3 O4 is used, a belt with good water resistance can be obtained, but the use of lead compounds is not preferred due to pollution and hygiene problems. Furthermore, when MgO is used as an acid acceptor, water resistance is significantly impaired by MgCl2 produced during the crosslinking reaction, making it inappropriate to be applied to belts. On the other hand, if an epoxy-based acid acceptor is used as an acid acceptor other than a metal oxide, it is possible to obtain a composition with good water resistance, but it may cause odor problems and cause discomfort to the human body. There was a problem of giving.

In order to improve this, the present applicant has developed a power transmission belt using a chlorosulfonated polyethylene rubber composition in which a magnesium oxide-aluminum oxide solid solution is mixed as an acid acceptor in at least the compressed rubber layer of the power transmission belt. proposed. This is Japanese Patent Publication No. 62-24695
It is described in Publication No. 1.

[0007]

[Problems to be Solved by the Invention] However, although this power transmission belt has a greatly improved belt running life in high-temperature atmospheres and has excellent heat resistance compared to belts using chloroprene rubber, It has become clear that the running life of the belt in a low-temperature atmosphere of −30° C. or lower is significantly inferior. The reason for this is that conventional chlorosulfonated polyethylene rubber is made by chlorosulfonating linear high-density polyethylene, and has a chlorine content of 35% by weight, which increases the cohesive energy of chlorine and makes it difficult to operate at low temperatures. It is presumed that this is because the rubber hardens and loses its elasticity, making it more likely to crack.

The present invention addresses these problems by improving the composition of the compressed rubber layer, which is repeatedly compressed and deformed during belt running, to improve its heat resistance and cold resistance, and to improve its heat resistance and cold resistance. The object of the present invention is to provide a power transmission belt that has improved durability when running under low and low temperature atmospheres.

[0009]

[Means for Solving the Problems] That is, the present invention is characterized by providing a power transmission belt comprising an adhesive rubber layer in which a core wire is embedded and an elastic layer including a compressed rubber layer. Chlorine content 15-35% by weight as compressed rubber layer
, preferably 25-32% by weight and a sulfur content of 0.5
A rubber composition of low-density polyethylene with a linear molecular structure that has been chlorosulfonated to a content of ~2.5% by weight is used, and a chloroprene rubber composition or hydrogenated nitrile rubber is used as the adhesive rubber layer. be.

Examples of power transmission belts according to the present invention include V-belts and V-ribbed belts, and the V-ribbed belt 1 shown in FIG. 1 is a high-strength belt made of polyester fiber, aromatic polyamide fiber, or glass fiber. A core wire 2 made of a cord with low elongation is embedded in an adhesive rubber layer 3, and a compressed rubber layer 4, which is an elastic layer, is provided below the core wire 2. The compressed rubber layer 4 is provided with a plurality of ribs 7 having a substantially triangular cross section extending in the longitudinal direction of the belt, and a rubberized canvas 5 attached to the belt surface.

Further, the V-belt 6 shown in FIG. 2 is composed of an adhesive rubber layer 3 in which the core wire 2 is embedded and a compressed rubber layer 4, and furthermore, each surface layer of the adhesive rubber layer 3 and the compressed rubber layer 4 is coated with rubber. The attached canvas 5 is laminated.

The compressed rubber layer 4 has a chlorine content of 15 to 15%.
Low-density polyethylene with a linear molecular structure (referred to as ACSM) that has been chlorosulfonated to have a sulfur content of 35% by weight, preferably 25 to 32% by weight, and a sulfur content in the range of 0.5 to 2.5% by weight. ) is used.

[0013] Since the alkyl side chain of ACSM plays the role of inhibiting polyethylene crystals in the same way as chlorine, the chlorine content can be reduced to 35% by weight or less without leaving any polyethylene crystals. As a result, in the low temperature region, the cohesive force between chlorine is weakened and low temperature resistance is improved. Further, even in a high temperature range, the presence of the alkyl side chain, which is more inactive than chlorine, reduces reactivity and improves heat resistance. The chlorine content is required to be 15% to 35% by weight; if it exceeds 35% by weight, the cold resistance and heat resistance will be insufficient, while if it is less than 15% by weight, the oil resistance and mechanical strength will not be sufficient. Moreover, in order to balance oil resistance, heat resistance, and cold resistance, the preferable content is 25% by weight to 32% by weight.

[0014] The acid acceptor used here is not particularly limited, but a magnesium oxide-aluminum oxide solid solution is preferable, and a specific example thereof is KW-
2000, KW-2100, etc.

[0015] The amount of the acid acceptor added is 1 to 50 parts by weight, preferably 4 to 20 parts by weight, per 100 parts by weight of ACSM. Since the hydrogen chloride generated in the belt cannot be sufficiently removed, the number of crosslinking points in the ACSM decreases, making it impossible to obtain the desired vulcanizate, resulting in a belt that lacks heat resistance and is prone to early cracking. on the other hand,
If it exceeds 50 parts by weight, the Mooney viscosity will be extremely high, causing problems in processing and finishing.

This magnesium oxide-aluminum oxide solid solution may be added as is during kneading, but it may be treated with an anionic surfactant such as sodium stearate or a silane coupling agent in advance to improve dispersibility. It is also possible to use

The ACSM rubber composition contains commonly used carbon black, a softener, an anti-aging agent, a processing aid,
It can be used together with adhesives, vulcanization accelerators, organic or inorganic short fibers, etc.

[0018] There are no particular restrictions on the method of mixing the above-mentioned components, and they may be kneaded by any known means or methods using, for example, a Banbury mixer, a kneader, or the like.

[0019] The adhesive rubber layer 3 is made of a chloroprene rubber composition having heat resistance and good adhesion to core fibers such as polyester fibers, aromatic polyamide fibers, glass fibers, etc., and a hydrogenation rate of 80% or more. hydrogenated nitrile rubber is used. This is because the main chain of ACSM is polyethylene, which has low cohesive energy as a polymer, making it difficult to obtain sufficient adhesive strength.

[0020] The core wire is subjected to adhesive treatment for the purpose of improving adhesion to rubber. Such adhesive treatment generally involves immersing the fibers in resorcinol-formalin-latex (RFL liquid) and then heating and drying the fibers to form an adhesive layer uniformly on the surface. However, without limitation, after pretreatment with an epoxy or isocyanate compound, R
There is also a method of processing with FL liquid.

When the belt is run in a high-temperature atmosphere, the compressed rubber layer 4 is exposed to an environment where it is susceptible to chemical thermal deterioration, and when the belt engages with the pulley, it is compressed.
Also, since it is released when it is separated, it is repeatedly expanded and contracted. However, the ACSM rubber composition used for the compressed rubber layer 4 is not only good for the heat resistance of the belt, but also because it can keep the cohesive energy of chlorine low even in a low-temperature atmosphere due to the limited range of chlorine content. This can prevent hardening of the belt and improve the cold resistance of the belt.

[0022] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

[0023]

[Example] In the V-ribbed belt manufactured in this example, a cord made of polyester fiber rope is embedded in an adhesive rubber layer, and two plies of rubberized cotton canvas are laminated on the upper side, and the other layer is under the adhesive rubber layer. On the sides there is a layer of compressed rubber with three ribs in the longitudinal direction of the belt. The obtained V-ribbed belt is a K-shaped 3-ribbed belt with a length of 975 mm according to the RMA standard, a rib pitch of 3.56 mm, and a rib height of 2.
．． 9mm, belt thickness 5.3mm, and rib angle 40°.

[0024] Here, the compressed rubber layer and the adhesive rubber layer were prepared from the rubber compositions shown in Tables 1 and 2, respectively, kneaded with a Banbury mixer, and then rolled with a calendar roll. The compressed rubber layer contains short fibers and is oriented in the belt width direction.

[0025]

[Table 1]

[0026]

[Table 2]

The method for manufacturing the belt is a conventional method known in the art. First, a 2-ply rubberized cotton canvas is wrapped around a flat cylindrical mold, an adhesive rubber layer is wrapped around it, and the core wire is spun. , After installing the compressed rubber layer, insert the vulcanization jacket on top of the compressed rubber layer. Then,
After putting the mold into a vulcanizing can and vulcanizing at 150°C for 30 minutes, the cylindrical vulcanized sleeve was taken out of the mold, the compressed rubber layer of the sleeve was formed into ribs using a grinder, and the molded body was individually separated. The process consists of cutting into belts.

The results of the heat running test and the cold running test of the V-ribbed belt thus obtained are shown in Table 3.

[0029]

[Table 3]

Further, in order to examine the vulcanized physical properties of the compressed rubber layer, the rubber compounds shown in Table 1 were press-vulcanized at 150° C. for 30 minutes. The results are also listed in Table 1. Table 2 also shows the test results of the rope adhesive strength in the adhesive rubber layer.

In the heat-resistant running test conducted in this example, V
The ribbed belt is passed around a drive pulley with a diameter of 120 mm, a driven pulley with the same diameter, and a tension pulley with a diameter of 70 mm, and the initial tension of the belt is 85 kgf.The driving side is rotated at a rotation speed of 3,600 rpm, and the driven side is loaded with a load of 10 ps.
The belt was run at an ambient temperature of 120° C., and the time until cracks appeared in the ribs of the belt was measured.

In addition, in the cold running test, the V-ribbed belt was stretched around a driving pulley with a diameter of 45 mm and a driven pulley with the same diameter, and the initial tension of the belt was 15 Kgf, and the ambient temperature was -
After standing at 30° C. for 15 hours, it is run for 5 minutes and then stopped for 25 minutes. This process was repeated and the time until cracks appeared in the ribs of the belt was measured. In addition, in the rope adhesion test, the belt was attached to a length of 28.5 cm.
The two ropes were made to protrude, and the rope of the belt was attached to a chuck, and the pulling force of the rope was determined using a tensile tester.

As is clear from the running test results in Table 3, the belt of the present invention uses an ACSM rubber composition for the compressed rubber layer and a chloroprene rubber composition or H-NBR rubber composition for the adhesive rubber layer. It can be seen that the belt life is improved under high temperature and low temperature atmospheres compared to conventional belts.

[0034]

As described above, according to the present invention, by using an ACSM composition in the compressed rubber layer and a chloroprene rubber composition or a hydrogenated nitrile rubber composition in the adhesive rubber layer, the heat resistance and cold resistance of the belt can be improved. It is possible to obtain a power transmission belt which has improved properties and excellent durability without impairing its adhesion to the rope.

[Brief explanation of the drawing]

[Fig. 1] Longitudinal cross-sectional view of a V-ribbed belt according to the present invention

[Figure 2
] Longitudinal cross-sectional view of a V-belt which is another embodiment of the present invention

[Explanation of symbols]

2 Core wire 3 Adhesive rubber layer 4 Compressed rubber layer 5 Canvas with rubber 7 Ribs

Claims (1)

[Claims] Claim 1: A power transmission belt comprising adhesive rubber in which core wires are embedded along the longitudinal direction of the belt and an elastic layer including a compressed rubber layer, wherein the compressed rubber layer of the elastic layer has a chlorine content of 15%. ~35% by weight with a sulfur content of 0.5
A rubber composition of low-density polyethylene with a linear molecular structure that has been chlorosulfonated to a content of ~2.5% by weight is used, and a chloroprene rubber composition or a hydrogenated nitrile rubber composition is used for the adhesive rubber layer. A power transmission belt characterized by its use.