JPH11166078A - Rubber composition for transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition for transmission belt capable of giving a transmission belt causing no environmental pollution even by incineration and having excellent heat resistance, oil resistance and cold resistance. SOLUTION: This composition contains a polymer crosslinked material having ethylene, a (meth)acrylic acid ester and a crosslinking component as constituting components. The content of the (meth)acrylic acid ester is 30-70 wt.%, and that of the crosslinking component is 2-8 wt.%. The composition contains at least an amine vulcanizing agent besides the polymer crosslinked material. Further, the composition contains aluminum hydroxide, and its content is 5-40 pts.wt. based on 100 pts.wt. of the polymer crosslinked material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a power transmission belt capable of obtaining a power transmission belt having no risk of generating harmful substances and having excellent functionality.

[0002]

2. Description of the Related Art Transmission belts are used, for example, as friction transmission belts such as V-belts and V-rib belts such as wrapped belts and low-edge belts, and as meshing transmission belts such as timing belts for use in automobiles and general industries. Widely used.

[0003] These power transmission belts are usually composed of an adhesive rubber layer in which a core wire is bonded and buried, and a compression rubber layer laminated on the adhesive rubber layer. The lower canvas is bonded.

[0004] Devices for improving the life and reliability of the power transmission belt have been used for a long time. For example, a fiber made of polyester or the like is used as the core wire, and in order to improve the adhesion between the core wire and the adhesive rubber layer, sulfur is compounded in the rubber constituting the adhesive rubber layer, or thiuram vulcanization is performed. A device such as blending of an accelerator has been devised.

As the rubber used for the adhesive rubber layer and the compression rubber layer of such a power transmission belt, chloroprene rubber has been widely used. Chloroprene rubber is excellent in heat deterioration resistance, and has sufficient adhesiveness to the core wire.
Since the adhesiveness to the canvas can be improved, it was suitable as a rubber for a power transmission belt.

However, in recent years, harmful substances such as dioxins generated during incineration of chlorine-containing compounds have attracted attention from the viewpoint of environmental protection. In view of the above, there has been devised to avoid chlorine-containing compounds in compounds constituting industrial products, and the use of chloroprene rubber containing chlorine as an essential element is being avoided.

For example, NBR and hydrogenated NBR have been put into practical use as a rubber for a power transmission belt in place of chloroprene rubber. However, these rubbers have compression resistance,
Since the self-heating property is inferior to chloroprene rubber, the belt form and conditions of use are limited, and the use in fields requiring heat resistance and abrasion resistance is particularly limited. Was the actual situation.

[0008] Recently, an ethylene-acrylic acid copolymer has attracted attention as a novel elastomer material. Since this product is excellent in heat resistance, oil resistance, chemical resistance, etc., various products have been put to practical use in static applications such as sealing materials, hoses and tubes. However, ethylene-acrylic acid copolymers have large damping characteristics,
When this is used as the rubber for the power transmission belt, the belt itself absorbs the vibration during belt running, and the running noise of the belt is reduced.However, the vibration energy is converted into heat energy, the belt temperature rises, and the belt temperature rises. There was a risk of deterioration in characteristics and ignition.

[0009]

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a power transmission belt which does not cause environmental pollution even when incinerated and has excellent heat resistance, oil resistance and cold resistance. An object of the present invention is to provide a rubber composition for rubber.

[0010]

SUMMARY OF THE INVENTION The present invention provides an ethylene,
A rubber composition for a power transmission belt, comprising a (meth) acrylic acid ester and a crosslinked polymer having a crosslinking component as a constituent component. Hereinafter, the present invention will be described in detail.

The rubber composition for a power transmission belt of the present invention comprises ethylene, a (meth) acrylate, and a crosslinked polymer having a crosslinking component as a constituent. As the crosslinked polymer having ethylene, (meth) acrylic acid ester, and a cross-linking component as components, a ternary copolymer using a third monomer as a cross-linking component in addition to ethylene and (meth) acrylic ester. Polymers and the like can be mentioned.

The above (meth) acrylate means acrylate and / or methacrylate. As the (meth) acrylic acid ester, an ester of an alcohol having 1 to 8 carbon atoms and (meth) acrylic acid is preferable. For example, methyl (meth) acrylate,
Examples thereof include ethyl (meth) acrylate, n-butyl (meth) acrylate, and ethylhexyl (meth) acrylate. These can be used alone or in combination of two or more.

Examples of the third monomer include acrylic acid, methacrylic acid, acrylonitrile, vinyl acetate and the like; glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether containing an epoxy group.

The content of the (meth) acrylate in the terpolymer is preferably 30 to 70% by weight. If the content of the (meth) acrylic acid ester is less than 30% by weight, the crystallinity of the copolymer may be high and sufficient elasticity may not be obtained. The embrittlement point may be high, making it difficult to use at low temperatures. The content of the crosslinking component in the terpolymer is preferably 2 to 8% by weight. If the content of the cross-linking component is less than 2% by weight, the deteriorated form may not be cured and may not function as a compressed rubber, and if it exceeds 8% by weight, necessary rubber elasticity may be lost. There is.

In preparing the crosslinked polymer, a crosslinking agent is added. The crosslinking agent is not particularly limited, and examples thereof include urea derivatives, monoamines, and diamines that perform crosslinking based on a condensation reaction; diisocyanates and bisethyleneimine compounds that perform crosslinking based on an addition reaction.

The rubber composition for a power transmission belt preferably contains an amine vulcanizing agent as a vulcanizing agent. The amine vulcanizing agent is not particularly limited, and examples thereof include methylene dianiline and hexamethylene diamine carbamate. The amount of the amine vulcanizing agent is preferably 1 to 10 parts by weight based on 100 parts by weight of the polymer crosslinked product. If the amount of the amine vulcanizing agent is less than 1 part by weight, sufficient rubber elasticity and strength cannot be obtained, and if it exceeds 10 parts by weight, rubber elasticity and bending fatigue resistance will be poor. The amine vulcanizing agent may be used alone or in combination with another vulcanizing agent. Examples of the other vulcanizing agents include, for example, organic peroxides. The total amount when other vulcanizing agents are added is preferably 1 to 20 parts by weight.

When a vulcanizing agent such as the amine vulcanizing agent is contained in the rubber composition for a power transmission belt, it is preferable to further use a vulcanizing aid in combination. The vulcanization aid is not particularly limited and includes, for example, diphenylguanidine, di-o-
Tolyl guanidine, tetramethyl guanidine and the like can be mentioned. The amount of the vulcanization aid is preferably 1.5 to 15 parts by weight based on 100 parts by weight of the polymer crosslinked product. If the amount of the vulcanization aid is less than 1.5 parts by weight, sufficient rubber elasticity and strength cannot be obtained, and if it exceeds 15 parts by weight, rubber elasticity and bending fatigue resistance will be poor.

The rubber composition for a power transmission belt preferably further contains aluminum hydroxide. Since aluminum hydroxide has a high thermal conductivity, heat generated when the power transmission belt runs is easily released to the outside of the power transmission belt, and the temperature rise of the power transmission belt is prevented. Further, when the power transmission belt burns due to a fire or the like, the water of crystallization in the aluminum hydroxide is released, so that the spread of the combustion is prevented. The aluminum hydroxide has a chemical formula of Al (OH) ₃ or
It is represented by Al ₂ O ₃ .xH ₂ O. x represents the amount of water molecules in the hydrate.

The amount of the aluminum hydroxide is preferably 5 to 40 parts by weight based on 100 parts by weight of the crosslinked polymer. If the amount is less than 5 parts by weight, the thermal conductivity of the power transmission belt does not increase, so that a sufficient heat radiation effect cannot be exerted. If the amount exceeds 40 parts by weight, the mechanical properties of the power transmission belt deteriorate and the belt runs. Cause trouble. More preferably, it is 10 to 30 parts by weight.

The rubber composition for a power transmission belt may contain, for example, carbon black, a plasticizer and the like in addition to the above-mentioned components. The compounding amount of the above carbon black is
By giving a suitable rubber strength to the rubber composition for the power transmission belt, it is possible to provide the power transmission belt with a suitable strength and flexibility. Is preferred. If the amount of the carbon black is less than 30 parts by weight, the rubber strength may be insufficient. If the amount is more than 70 parts by weight, the rubber may be hard and the bending fatigue property may be poor.

The plasticizer is not particularly restricted but includes, for example, polyether-based process oils. The blending amount of the plasticizer is 10
0 to 20 parts by weight relative to 0 parts by weight is preferred.

The rubber composition for a power transmission belt of the present invention can be used as a component of a power transmission belt. Therefore, a V-belt, which is an embodiment of the transmission belt, will be described with reference to FIG. As shown in FIG. 1, the V-belt generally includes an adhesive rubber layer 12 having a core wire 11 bonded and embedded therein, and a compression rubber layer 13 laminated on the adhesive rubber layer 12. The upper canvas 14 and the lower canvas 15 are adhered as necessary. When laminating the compressed rubber layer 13 on the adhesive rubber layer 12, after forming a core support layer at the interface between the adhesive rubber layer 12 and the compressed rubber layer 13, the core support layer is removed. The layers may be laminated through the intermediary.

The rubber composition for a power transmission belt of the present invention is suitably used, for example, as the adhesive rubber layer 12 or the compression rubber layer 13 of the V-belt, which is one embodiment of the power transmission belt.

Examples of the cords include polyester cords. As the above canvas, for example,
Examples thereof include cotton, a blend of cotton and polyester, and a blend of cotton and polyamide.

The power transmission belt obtained by using the rubber composition for a power transmission belt of the present invention is not particularly limited as long as it is generally used as a power transmission belt.
A friction transmission belt such as a V-belt and a V-rib belt shown in FIG.
Transmission belts for automobiles and general industries, such as meshing transmission belts such as timing belts, can be given.
The power transmission belt is also one of the present invention.

Since the rubber composition for a power transmission belt of the present invention has the above-described structure, the power transmission belt using the rubber composition for a power transmission belt of the present invention does not cause environmental pollution even when incinerated, and is excellent. It has heat resistance, oil resistance, abrasion resistance, and bending resistance. In addition, when aluminum hydroxide is added as a component, a heat transmission belt having high heat dissipation and flame retardancy can be obtained.

[0027]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, the compounding amount shown in Table 1 and Table 3 was described by "part by weight".

Example 1 The ethylene-acrylic acid ester-based polymer having the composition shown in Table 1 has tensile properties in accordance with JIS K 6301, heat resistance in accordance with JIS K 6301, and flame retardancy in accordance with JIS K 6301. It was evaluated according to 6324. The results are shown in Table 2. While showing the flame retardant effect, no decrease in physical properties was observed.

Using the ethylene-acrylate polymer as a compression rubber layer, a transmission belt as shown in FIG. 1 was produced. The fire retardancy of the power transmission belt obtained was determined by JI
When evaluated in accordance with SK6324, it showed flame retardancy. Further, the obtained transmission belt is applied to the driving pulley 21 and the driven pulley 22 of φ70 of the belt running test device 20 shown in FIG.
0 kgf), at room temperature and at a rotation speed of 4900 rpm.
Was evaluated under the following conditions. As a result of examining the state of the power transmission belt after traveling for 200 hours, no major defect that adversely affects the belt traveling was found.

[0030]

[Table 1]

Example 2 An ethylene-acrylate polymer having the composition shown in Table 1 was evaluated in the same manner as in Example 1, and the results are shown in Table 2. While showing the flame retardant effect, no decrease in physical properties was observed. A power transmission belt was prepared in the same manner as in Example 1 except that the ethylene-acrylate polymer was used, and the flame retardancy was evaluated. In addition, as a result of examining the state of the power transmission belt after running for 200 hours, no major defect affecting the belt running was found.

Comparative Example 1 An ethylene-acrylate polymer having the composition shown in Table 1 was evaluated in the same manner as in Example 1, and the results are shown in Table 2. Also, except that this ethylene-acrylate polymer was used, a transmission belt was prepared in the same manner as in Example 1, and the flame retardancy was evaluated.
It showed flammability.

Comparative Example 2 An ethylene-acrylate polymer having the composition shown in Table 1 was evaluated in the same manner as in Example 1, and the results are shown in Table 2. Also, except that this ethylene-acrylate polymer was used, a transmission belt was prepared in the same manner as in Example 1, and the flame retardancy was evaluated.
It showed flammability.

[0034]

[Table 2]

Example 3 The physical properties of an ethylene-acrylate polymer having the composition shown in Table 3 were measured by the following methods.
The results are shown in Table 4.

[0036]Evaluation methods Tensile strength (MPa)  It was measured in accordance with JIS K6251.Elongation at break (%)  It was measured in accordance with JIS K6251.Hardness (JIS A)  It was measured according to JIS K6253.Heat aging elongation at break retention (%) [120 ° C x 6 days]  It was measured according to JIS K6257.Dematcher flex fatigue test 100,000 times crack length (mm)  It was measured according to JIS K 6260.

Using this ethylene-acrylate polymer as a compressed rubber layer, a transmission belt as shown in FIG. 1 was produced. The obtained transmission belt is applied to the driving pulley 21 and the driven pulley 22 of φ70 of the belt running test device 20 shown in FIG.
N (80 kgf) load, 85 ° C, rotation speed 490
A running test was performed under the condition of 0 rpm, the time from the start of running to the occurrence of cracks in the compressed rubber layer was measured, and the durability was evaluated. The results are shown in Table 4. This power transmission belt was less likely to crack in a belt durability test, and was excellent in heat resistance and durability.

[0038]

[Table 3]

Example 4 An ethylene-acrylate polymer having the composition shown in Table 3 was evaluated in the same manner as in Example 4, and the results are shown in Table 4. A power transmission belt was prepared in the same manner as in Example 4 except that this ethylene-acrylate polymer was used, and the durability was evaluated. The results are shown in Table 4. This power transmission belt was less likely to crack in a belt durability test, and was excellent in heat resistance and durability.

Example 5 An ethylene-acrylate polymer having the composition shown in Table 3 was evaluated in the same manner as in Example 4, and the results are shown in Table 4. A power transmission belt was prepared in the same manner as in Example 4 except that this ethylene-acrylate polymer was used, and the durability was evaluated. The results are shown in Table 4. This power transmission belt was less likely to crack in a belt durability test, and was excellent in heat resistance and durability.

Comparative Example 3 An ethylene-acrylate polymer having the composition shown in Table 3 was evaluated in the same manner as in Example 4, and the results are shown in Table 4. A power transmission belt was prepared in the same manner as in Example 4 except that the ethylene-acrylate polymer was used, and the durability was evaluated. The results are shown in Table 4. Since the power transmission belt had low heat resistance, the compression rubber was hardened, and cracks began early in the durability test.

Comparative Example 4 An ethylene-acrylate polymer having the composition shown in Table 3 was evaluated in the same manner as in Example 4, and the results are shown in Table 4. A power transmission belt was prepared in the same manner as in Example 4 except that the ethylene-acrylate polymer was used, and the durability was evaluated. The results are shown in Table 4. Since the power transmission belt had low heat resistance, the compression rubber was hardened, and cracks began early in the durability test.

Comparative Example 5 An ethylene-acrylate polymer having the composition shown in Table 3 was evaluated in the same manner as in Example 4, and the results are shown in Table 4. A power transmission belt was prepared in the same manner as in Example 4 except that the ethylene-acrylate polymer was used, and the durability was evaluated. The results are shown in Table 4. Since this power transmission belt was inferior in fatigue resistance, cracks started early in the durability test.

[0044]

[Table 4]

The following compounds were used as the compounds shown in Tables 1 and 3. Polymer (1): ethylene-acrylate-acrylic acid copolymer (VAMAC HG (Mooney viscosity M
L1 + 4 (100 ° C.) = 27 ± 3), manufactured by DuPont) Polymer (2): ethylene-acrylate-epoxy copolymer (Esprene EMA 2752 (acrylate content = 59 wt%, crosslinking site monomer content = 2.3 wt%, Mooney viscosity ML1 + 4 (10
0 ° C) = 16), manufactured by Sumitomo Chemical Co., Ltd.) Carbon black (Table 1): FEF carbon Carbon black (Table 3): HAF carbon Plasticizer: Polyether-based process oil (ADEKASIZER RS-735) Vulcanizing agent 1 : Hexamethylenediamine carbamate Vulcanizing agent 2: Isocyanuric acid Vulcanizing agent 3: Quaternary ammonium salt compound Vulcanizing agent 4: Thiourea compound Vulcanizing accelerator 1: Di-o-tolylguanidine Vulcanizing accelerator 2: Di -O-tolylguanigin
e salt of dicatechol bora
te Vulcanization accelerator 3: Tetramethylthiuram disulfide Vulcanization accelerator 4: N-cyclohexyl-2-benzothiazolylsulfenamide Aluminum hydroxide: Heidilite H-40 Chloroprene rubber: Neoprene GS H-NBR: Zetball 2020

[0046]

Since the rubber composition for a power transmission belt of the present invention has the above-mentioned constitution, a power transmission belt using the rubber composition for a power transmission belt of the present invention does not cause environmental pollution even when incinerated, and It has excellent heat resistance, oil resistance, abrasion resistance, and bending resistance. Further, when aluminum hydroxide is contained, the heat dissipation is high, so that the temperature rise during running of the belt can be more effectively suppressed or prevented. Furthermore, it is flame-retardant and can prevent the spread of combustion in a fire or the like.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a V-belt which is an embodiment of a power transmission belt using the rubber composition for a power transmission belt of the present invention.

FIG. 2 is a schematic view of a belt running test device for evaluating the durability of a power transmission belt using the rubber composition for a power transmission belt of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Core wire 12 Adhesive rubber layer 13 Compressed rubber layer 14, 15 Canvas 20 Belt running test device 21 Drive pulley 22 Follower pulley 23 Power transmission belt

Claims (6)

[Claims] 1. A rubber composition for a power transmission belt comprising ethylene, a (meth) acrylate, and a crosslinked polymer having a crosslinking component as a constituent. 2. The content of the (meth) acrylate is 30 to 70% by weight, and the content of the crosslinking component is 2 to 70% by weight.
The rubber composition for a power transmission belt according to claim 1, which is 8% by weight. 3. The rubber composition for a power transmission belt according to claim 1, wherein the rubber composition further comprises at least an amine vulcanizing agent in addition to the crosslinked polymer. 4. The rubber composition for a power transmission belt according to claim 1, further comprising aluminum hydroxide. 5. The rubber composition for a power transmission belt according to claim 4, wherein the content of aluminum hydroxide is 5 to 40 parts by weight based on 100 parts by weight of the crosslinked polymer. 6. A power transmission belt comprising the power transmission rubber composition according to claim 1, 2, 3, 4, or 5.