JP7341695B2 - power transmission belt - Google Patents

Description

The present invention relates to a power transmission belt .

BACKGROUND ART As crosslinked rubber compositions used in rubber products, those containing carboxylic acid-modified ethylene-α-olefin elastomer as a rubber component are known. For example, Patent Document 1 discloses a crosslinked rubber composition having an ethylene content of 10 to 60 mol % and containing an ethylene/propylene copolymer modified with carboxylic acid as a rubber component. Patent Document 2 discloses a crosslinked rubber composition containing, as a rubber component, an ethylene-propylene-diene terpolymer having an ethylene content of 40 to 99 mol% and modified with an unsaturated carboxylic acid. Patent Document 3 discloses a crosslinked rubber composition whose rubber component is a maleic anhydride-modified ethylene/propylene copolymer having an ethylene:propylene molar ratio of 30:70.

Patent No. 5049422 International Publication No. 2009/123228 Japanese Patent Application Publication No. 2010-202784

An object of the present invention is to provide a power transmission belt using a crosslinked rubber composition with excellent wear resistance.

The present invention provides a power transmission belt in which a pulley contact surface is formed of a crosslinked rubber composition, the crosslinked rubber composition comprising a rubber component mainly consisting of a carboxylic acid modified ethylene-α-olefin elastomer, and wet silica. and, the content of the carboxylic acid modified product of the ethylene-α-olefin elastomer in the rubber component is 90% by mass or more, and the content of the wet silica is based on 100 parts by mass of the rubber component. It is 30 parts by mass or more and 80 parts by mass or less.

According to the present invention, excellent wear resistance can be obtained by containing silica and a rubber component mainly composed of a carboxylic acid modified ethylene-α-olefin elastomer.

1 is a graph showing the wear volumes of DIN wear tests of Examples 1 to 4 and Comparative Examples 1 to 4. 2 is a graph showing the tensile stress M ₁₀₀ at 100% elongation at 25° C. of Examples 1 to 4 and Comparative Examples 1 to 4. 1 is a graph showing the tensile strength TB at 25° C. of Examples 1 to 4 and Comparative Examples 1 to 4. 2 is a graph showing the storage modulus G' (10%, 100°C) of Examples 1 to 4 and Comparative Examples 1 to 4 at a strain of 10% and 100°C. 2 is a graph showing the loss coefficient tan δ (10%, 100° C.) at a strain amount of 10% and 100° C. of Examples 1 to 4 and Comparative Examples 1 to 4. Storage modulus of elasticity G' (1%, 100°C) at strain of 1% and 100°C for Examples 1 to 4 and Comparative Examples 1 to 4 %, 100°C) and the ratio (G'(1%, 100°C)/G'(30%, 100°C). 1 is a graph showing the hardness of Examples 1 to 4 and Comparative Examples 1 to 4.

Hereinafter, embodiments will be described in detail.

The crosslinked rubber composition according to the embodiment includes a rubber component mainly consisting of a carboxylic acid modified product (hereinafter referred to as "elastomer A") of an ethylene-α-olefin elastomer (hereinafter referred to as "base elastomer"), and silica. contains. According to the crosslinked rubber composition according to the embodiment, excellent abrasion resistance can be obtained. This is presumed to be because the main component of the rubber component is Elastomer A, which is a carboxylic acid-modified base elastomer, which provides high dispersibility of silica and is uniformly reinforced by the silica.

Here, since the rubber component mainly contains elastomer A, its content is more than 50% by mass. The content of elastomer A in the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and most preferably 100% by mass. Note that the rubber component may contain an ethylene-α-olefin elastomer other than elastomer A, and may also contain other chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), hydrogenated acrylonitrile rubber (H-NBR), etc. ) etc. may be included.

Examples of the base elastomer before carboxylic acid modification include ethylene-propylene copolymer (hereinafter referred to as "EPM"), ethylene-propylene-nonconjugated diene terpolymer (hereinafter referred to as "EPDM"), ethylene-propylene copolymer (hereinafter referred to as "EPDM"), and ethylene-propylene copolymer (hereinafter referred to as "EPDM"). Examples include octene copolymers and ethylene-butene copolymers. The base elastomer preferably contains one or more of these, and from the viewpoint of obtaining excellent wear resistance, it more preferably contains at least one of EPR and EPDM, and preferably contains EPDM. More preferred.

From the viewpoint of obtaining excellent wear resistance, the ethylene content in the base elastomer is preferably 40% by mass or more and 70% by mass or less, more preferably 50% by mass or more and 60% by mass or less, even more preferably 52% by mass or more and 57% by mass. It is as follows. From the viewpoint of obtaining excellent wear resistance, the α-olefin content in the base elastomer is preferably 30% by mass or more and 60% by mass or less, more preferably 35% by mass or more and 55% by mass or less. The ratio of ethylene content to α-olefin content (ethylene content/α-olefin content) in the base elastomer is preferably 0.60 or more and 2.4 or less, more preferably 1.0 from the viewpoint of obtaining excellent wear resistance. 1.5 or less.

When the base elastomer contains EPDM, examples of the non-conjugated diene component include ethylidene nobornene (ENB), dicyclopentadiene, 1,4-hexadiene, and the like. Among these, ethylidene nobornene (ENB) is preferable as the non-conjugated diene component from the viewpoint of obtaining excellent wear resistance. In this case, the non-conjugated diene content of the base elastomer is preferably 1.9% by mass or more and 7.4% by mass or less, more preferably 4.5% by mass or more and 5.5% by mass from the viewpoint of obtaining excellent wear resistance. % or less.

Examples of carboxylic acid-modified products of elastomer A include maleic anhydride-modified products, maleic acid-modified products, itaconic anhydride-modified products, itaconic acid-modified products, fumaric acid-modified products, methacrylic acid-modified products, acrylic acid-modified products, etc. Can be mentioned. The carboxylic acid-modified product of elastomer A preferably contains one or more of these, and more preferably contains a maleic anhydride-modified product from the viewpoint of obtaining excellent wear resistance.

Elastomer A is produced by putting a base elastomer, a carboxylic acid, and a reaction initiator into a closed kneader such as a kneader or a Banbury mixer, and kneading for a predetermined time at a predetermined temperature at which the reaction initiator decomposes. It can be obtained by grafting acid. Elastomer A can also be obtained by modification means such as ultraviolet irradiation.

The rubber component is intermolecularly crosslinked, but may be crosslinked using an organic peroxide as a crosslinking agent, or may be crosslinked using sulfur as a crosslinking agent, and further, They may be used together to form a crosslink. Further, the rubber component may be crosslinked using an electron beam or the like. From the viewpoint of obtaining excellent abrasion resistance, the rubber component is preferably crosslinked using an organic peroxide as a crosslinking agent. In this case, the amount of organic peroxide blended in the uncrosslinked rubber composition before crosslinking is preferably 1.0 parts by mass or more with respect to 100 parts by mass of the rubber component, from the viewpoint of obtaining excellent wear resistance. It is 0 parts by mass or less, more preferably 2.0 parts by mass or more and 4.0 parts by mass or less.

Examples of the silica include wet silica such as precipitated silica and gel silica; synthetic silica such as dry silica such as calcined silica and arc silica. It is preferable that the silica contains one or more of these, and from the viewpoint of obtaining excellent wear resistance, it is more preferable that the silica contains precipitated silica. The BET specific surface area of silica measured based on ISO9277 is, for example, 150 m ² /g or more and 200 m ² /g or less. The primary particle size of silica is, for example, 10 nm or more and 50 nm or less, and the secondary particle size of the silica aggregate is, for example, 1 μm or more and 40 μm or less. From the viewpoint of obtaining excellent abrasion resistance, the content of silica in the crosslinked rubber composition according to the embodiment is preferably 1 part by mass or more and 80 parts by mass or less, more preferably 20 parts by mass, based on 100 parts by mass of the rubber component. Parts or more and 60 parts by weight or less, more preferably 30 parts or more and 50 parts by weight or less.

The crosslinked rubber composition according to the embodiment may also contain a processing aid, a vulcanization accelerator, a vulcanization accelerator, a plasticizer, an anti-aging agent, etc. as rubber compounding agents.

The amount of wear measured by the DIN abrasion test based on JIS K6264-2 of the crosslinked rubber composition according to the embodiment is preferably 300 mm ³ or less, more preferably 200 mm ³ or less.

The tensile stress M ₁₀₀ at 100% elongation at 25° C. of the crosslinked rubber composition according to the embodiment is preferably 1.5 MPa or more, more preferably 3.0 MPa or more. The tensile strength TB at 25° C. of the crosslinked rubber composition according to the embodiment is preferably 3.00 MPa or more, more preferably 10.0 or more. These tensile stress M ₁₀₀ and tensile strength TB at 100% elongation at 25° C. are measured based on JIS K6251:2010.

The storage modulus G' (10%, 100°C) at 10% strain and 100°C of the crosslinked rubber composition according to the embodiment is preferably 1.0 MPa or more and 5.0 MPa or less, more preferably 2.0 MPa or more. It is 4.0 MPa or less. The loss coefficient tan δ (10%, 100°C) at 10% strain and 100°C of the crosslinked rubber composition according to the embodiment is preferably 0.030 or more and 0.16 or less, more preferably 0.070 or more and 0.070 or more. It is 13 or less. The storage modulus G' (1%, 100°C) of the crosslinked rubber composition according to the embodiment at 1% strain and 100°C. The ratio (G'(1%, 100°C)/G'(30%, 100°C)) to ℃) is the strain dependence of the storage modulus G' for evaluating the dispersibility of the filler, that is, the so-called It is an index of the Payne effect, and the closer it is to 1.0, the better the dispersibility of the filler is. It is preferably 0.8 or more and 3.5 or less, more preferably 0.8 or more and 2.0 or less. be. These storage elastic modulus G' and loss coefficient tan δ are measured based on JIS K6394:2007.

The hardness of the crosslinked rubber composition according to the embodiment as measured by a type A durometer based on JIS K6253-3:2012 is preferably 50 or more and 90 or less, more preferably 53 or more and 85 or less.

The crosslinked rubber composition according to the above embodiments is prepared by kneading the rubber component, silica, and other rubber compounding agents using a rubber kneading machine such as a kneader, Banbury mixer, or open roll to prepare an uncrosslinked rubber composition. can be obtained by crosslinking the uncrosslinked rubber composition at a predetermined temperature and a predetermined pressure.

In addition, the crosslinked rubber composition according to the embodiment has excellent abrasion resistance, and is therefore suitable for forming sliding parts of rubber products. suitable for forming.

(Crosslinked rubber composition)
Sheet-shaped crosslinked rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 4 below were prepared. The respective configurations are also shown in Table 1.

<Example 1>
In a closed kneader, EPDM (Nordel IP 4640 manufactured by Dow Chemical Co., Ltd., ethylene content: 55% by mass, propylene content: 40% by mass, non-conjugated diene content (ENB content): 4.9% by mass, ethylene content/propylene content = 1.4, ethylene content/non-conjugated diene content (ENB content) = 11), and 1 part by mass of maleic anhydride and 0.1 part by mass of organic peroxide as a reaction initiator for 100 parts by mass of this EPDM. (Percumyl D manufactured by Nippon Oil & Fats Co., Ltd., dicumyl peroxide) was added and kneaded for 10 minutes at a temperature of 170° C. to prepare maleic anhydride-modified EPDM. Next, this maleic anhydride-modified EPDM was used as a rubber component, and to this, 5 parts by mass of precipitated silica (Ultrasil VN3 manufactured by Evonik) as a filler was added to 100 parts by mass of the rubber component, and 0.5 parts by mass. stearic acid as a processing aid (stearic acid S50, manufactured by Shin Nippon Rika Co., Ltd.), 5 parts by mass of zinc oxide as a vulcanization accelerating aid (3 types of zinc oxide, manufactured by Hakusui Chemical Co., Ltd.), and 3.2 parts by mass of a crosslinking agent. An uncrosslinked rubber composition was prepared by blending and kneading an organic peroxide (Percumyl D, manufactured by NOF Corporation, dicumyl peroxide). A crosslinked rubber composition for testing in a predetermined shape was obtained from this uncrosslinked rubber composition. The obtained crosslinked rubber composition for testing was designated as Example 1.

<Example 2>
Example 2 was a crosslinked rubber composition for testing obtained in the same manner as in Example 1 except that the amount of precipitated silica was 40 parts by mass per 100 parts by mass of the rubber component.

<Example 3>
Example 3 was a crosslinked rubber composition for testing obtained in the same manner as in Example 1 except that the amount of precipitated silica was 70 parts by mass per 100 parts by mass of the rubber component.

<Example 4>
Examples except that EPM (EP11 manufactured by JSR, ethylene content: 52% by mass, propylene content: 48% by mass, ethylene content/propylene content = 1.1) modified with maleic anhydride was used instead of EPDM. Example 4 was a crosslinked rubber composition for testing obtained in the same manner as Example 1.

<Comparative Examples 1 to 4>
Comparative Examples were crosslinked rubber compositions for testing obtained in the same manner as Examples 1 to 4, except that EPDM or EPM that had not been modified with acid was used instead of EPDM or EPM that had been modified with maleic anhydride. I gave it a rating of 1 to 4.

(Test method)
<Abrasion resistance>
For each of Examples 1 to 4 and Comparative Examples 1 to 4, a DIN abrasion test was conducted based on JIS K6264-2:2005 to measure the wear volume.

<Tensile properties>
For each of Examples 1 to 4 and Comparative Examples 1 to 4, tensile stress M ₁₀₀ and tensile strength TB at 100% elongation at 25° C. were measured based on JIS K6251:2010.

<Dynamic viscoelasticity>
For each of Examples 1 to 4 and Comparative Examples 1 to 4, storage modulus G' (10%, 100 °C) and loss coefficient tan δ (10 %, 100°C) was measured.

In addition, the storage elastic modulus G' (1%, 100°C) at a strain of 1% and 100°C and the storage elastic modulus G' (30%, 100°C) at a strain of 30% and 100°C were measured, and the former The ratio of G'(1%, 100°C)/G'(30%, 100°C) to the latter was calculated.

<Hardness>
The hardness of each of Examples 1 to 4 and Comparative Examples 1 to 4 was measured using a type A durometer based on JIS K6253-3:2012.

(Test results)
Table 2 shows the test results. FIG. 1 shows the wear volume of the DIN wear test for Examples 1 to 4 and Comparative Examples 1 to 4. FIG. 2A shows the tensile stress M ₁₀₀ at 100% elongation at 25° C. for Examples 1 to 4 and Comparative Examples 1 to 4. FIG. 2B shows the tensile strength TB at 25° C. of Examples 1 to 4 and Comparative Examples 1 to 4. FIG. 3A shows the storage modulus G' (10%, 100°C) at 10% strain and 100°C for Examples 1 to 4 and Comparative Examples 1 to 4. FIG. 3B shows the loss coefficient tan δ (10%, 100° C.) at 10% strain and 100° C. for Examples 1 to 4 and Comparative Examples 1 to 4. FIG. 4 shows the storage modulus G' (1%, 100°C) at a strain of 1% and 100°C for Examples 1 to 4 and Comparative Examples 1 to 4 and the storage modulus at a strain of 30% and 100°C. The ratio (G' (1%, 100 °C)/G' (30%, 100 °C) to G' (30%, 100 °C) is shown. Indicates hardness.

According to Table 2 and FIG. 1, Examples 1 to 4 in which maleic anhydride-modified EPDM or EPM was used as the rubber component were different from corresponding comparative examples 1 in which maleic anhydride-modified EPDM or EPM was used as the rubber component. It can be seen that the wear volume is smaller than that of Samples 4 to 4, and therefore the wear resistance is superior.

According to Table 2 and FIG. 2A, Examples 1 to 4 in which maleic anhydride-modified EPDM or EPM was used as the rubber component were different from corresponding Comparative Examples 1 in which maleic anhydride-modified EPDM or EPM was used as the rubber component. It can be seen that the tensile stress M ₁₀₀ is higher than that of . Furthermore, when comparing Examples 1 to 3 and Comparative Examples 1 to 3 in which EPDM was used as a rubber component, it was found that when the content of precipitated silica was 40 parts by mass or more based on 100 parts by mass of the rubber component, EPDM was anhydrous. It can be seen that the difference in tensile stress _M100 between the presence and absence of maleic acid modification is very large.

According to Table 2 and FIG. 2B, Examples 1 to 4 in which maleic anhydride-modified EPDM or EPM was used as the rubber component were different from corresponding Comparative Examples 1 in which maleic anhydride-modified EPDM or EPM was used as the rubber component. It can be seen that the tensile strength TB is higher than that of ~4.

According to Table 2 and FIG. 3A, Examples 1, 2, and 4 in which the content of precipitated silica is 40 parts by mass or less based on 100 parts by mass of the rubber component, and corresponding Comparative Examples 1, 2, and 4, it can be seen that there is almost no difference in storage modulus G' (10%, 100° C.) depending on whether EPDM or EPM is modified with maleic anhydride. Further, when comparing Example 3 in which the content of precipitated silica was 70 parts by mass per 100 parts by mass of the rubber component and Comparative Example 3, Example 3 in which maleic anhydride-modified EPDM was used as the rubber component, It can be seen that the storage elastic modulus G' (10%, 100° C.) is lower than that of Comparative Example 3 in which the rubber component was EPDM that was not modified with maleic anhydride.

According to Table 2 and FIG. 3B, Examples 1, 2, and 4 in which the content of precipitated silica is 40 parts by mass or less based on 100 parts by mass of the rubber component, and corresponding Comparative Examples 1, 2, and Comparing Examples 1, 2, and 4, in which maleic anhydride-modified EPDM or EPM was used as a rubber component, compared to Comparative Examples 1, 2, and 4, in which maleic anhydride-modified EPDM or EPM was used as a rubber component. It can be seen that the loss coefficient tan δ (10%, 100° C.) is lower than that of Samples and 4, and therefore the heat generation due to dynamic use is small. Further, when comparing Example 3 in which the content of precipitated silica was 70 parts by mass per 100 parts by mass of the rubber component and Comparative Example 3, Example 3 in which maleic anhydride-modified EPDM was used as the rubber component, It can be seen that the loss coefficient tan δ (10%, 100° C.) is higher than that of Comparative Example 3 in which the rubber component was EPDM that was not modified with maleic anhydride. For these reasons, from the viewpoint of suppressing heat generation due to dynamic use, the content of precipitated silica is preferably less than 70 parts by mass, and 60 parts by mass or less, based on 100 parts by mass of the acid-modified rubber component. It is more preferable that

According to Table 2 and FIG. 4, Examples 1 to 4 in which maleic anhydride-modified EPDM or EPM was used as the rubber component were different from corresponding comparative examples 1 in which maleic anhydride-modified EPDM or EPM was used as the rubber component. It can be seen that G'(1%, 100°C)/G'(30%, 100°C) is closer to 1.0 than that of Sample 4. Therefore, it can be seen that the dispersibility of the precipitated silica as a filler is excellent.

According to Table 2 and FIG. 5, Examples 1 to 4 using EPDM or EPM modified with maleic anhydride as the rubber component, and corresponding Comparative Example 1 using EPDM or EPM not modified with maleic anhydride as the rubber component. Comparing with No. 4 to No. 4, it can be seen that there is almost no difference in hardness.

The present invention is useful in the technical field of power transmission belts .

Claims (11)

A power transmission belt in which a pulley contact surface is formed of a crosslinked rubber composition,
The crosslinked rubber composition contains a rubber component mainly composed of a carboxylic acid modified ethylene-α-olefin elastomer, and wet silica,
The content of the carboxylic acid modified ethylene-α-olefin elastomer in the rubber component is 90% by mass or more,
A power transmission belt in which the content of the wet silica is 30 parts by mass or more and 80 parts by mass or less based on 100 parts by mass of the rubber component. The power transmission belt according to claim 1,
A power transmission belt in which the ethylene-α-olefin elastomer contains an ethylene-propylene copolymer. The power transmission belt according to claim 1 or 2,
A power transmission belt in which the ethylene-α-olefin elastomer includes an ethylene-propylene-nonconjugated diene terpolymer. In the power transmission belt according to claim 3,
A power transmission belt, wherein the non-conjugated diene component in the ethylene/propylene/non-conjugated diene terpolymer is ethylidene nobornene, and the non-conjugated diene content is 1.9% by mass or more and 7.4% by mass or less. The power transmission belt according to any one of claims 1 to 4,
A power transmission belt, wherein the ethylene content of the ethylene-α-olefin elastomer is 40% by mass or more and 70% by mass or less. The power transmission belt according to any one of claims 1 to 5,
A power transmission belt, wherein the ethylene-α-olefin elastomer has an α-olefin content of 30% by mass or more and 60% by mass or less. The power transmission belt according to any one of claims 1 to 6,
A power transmission belt, wherein the ratio of ethylene content to α-olefin content in the ethylene-α-olefin elastomer is 0.60 or more and 2.4 or less. The power transmission belt according to any one of claims 1 to 7,
A power transmission belt , wherein the carboxylic acid modified product includes a maleic anhydride modified product. The power transmission belt according to any one of claims 1 to 8,
A power transmission belt in which the rubber component is crosslinked using an organic peroxide as a crosslinking agent. The power transmission belt according to any one of claims 1 to 9,
A power transmission belt , wherein the wet silica includes precipitated silica. The power transmission belt according to any one of claims 1 to 10,
A power transmission belt whose wear volume measured by a DIN abrasion test based on JIS K6264-2 is 200 mm ³ or less.