JP2010248401A - Rubber composition and power transmission belt - Google Patents

Abstract

[Problem] To provide a rubber composition capable of sufficiently exerting the effect of a phenol resin organic reinforcing agent on a molded product while containing an ethylene-α-olefin copolymer, and having high durability while being excellent in durability. The rubber composition of the present invention has 0 phenolic organic reinforcing agent per 100 parts by weight of a rubber component containing an ethylene-α-olefin copolymer. A rubber composition characterized by containing more than 25 parts by weight and less than 25 parts by weight, further containing an ethylene-based copolymer having a polar group in the molecule, and being used by crosslinking the rubber component.
[Selection] Figure 1

Description

  The present invention relates to a rubber composition and a transmission belt that are used after being crosslinked, and more particularly to a rubber composition containing an ethylene-α-olefin copolymer and a transmission belt having a surface formed of a rubber cured product.

2. Description of the Related Art Conventionally, as a means for transmitting rotational power of an engine, a motor, or the like, a method of fixing pulleys or the like to the rotation shafts on the driving side and the driven side and spanning a transmission belt around these pulleys has been widely used.
In this power transmission belt, a friction conductive surface is formed by a rubber cured product obtained by crosslinking a rubber composition, so that it is widely used for high load applications such as automobiles such as low edge type V belts and V ribbed belts. In such a case, a rubber composition containing short fibers is used as a forming material to increase the elasticity of the cured rubber constituting the transmission belt.
However, although the short fiber is useful for increasing the elasticity of a molded product formed by the rubber composition, the cost is generally high and the rubber composition containing the short fiber, for example, transmission If the compression rubber layer of the belt is formed, the manufacturing process of the transmission belt tends to be complicated, and therefore a technique for increasing the elasticity in place of the short fiber blending has been studied.

As a method for increasing the elasticity of a rubber cured product in addition to containing short fibers, a method of adding a large amount of filler such as carbon black to the rubber composition (for example, Patent Document 1 below), or increasing the amount of a vulcanizing agent There is known a technique for increasing the number of cross-linking points.
However, in the method by increasing the amount of filler, the elongation of the rubber is reduced. As a result, the resulting molded product is likely to be cracked or worn, and the durability thereof is reduced. When the amount of the vulcanizing agent is increased, thermal deterioration is likely to occur. As a result, the durability of the molded product may be lowered.

On the other hand, it has been studied to add a resin-based component called an organic reinforcing agent to a rubber composition. For example, Patent Documents 2 to 5 listed below describe modified or unmodified phenolic resin-based organic reinforcing agents. Is added to the rubber composition.
In the case of forming a molded product by crosslinking the rubber composition containing this phenolic resin organic reinforcing agent, it is possible to increase the elasticity of the molded product while suppressing the occurrence of cracks and a decrease in wear resistance. Therefore, the rubber composition can be useful for applications such as a transmission belt.
However, the phenol resin organic reinforcing agent has a problem that it is difficult to sufficiently exert its performance on rubber components such as an ethylene-α-olefin copolymer.
Therefore, it is difficult to impart sufficient durability to the transmission belt formed by the rubber composition using the ethylene-α-olefin copolymer.

JP 2006-194357 A Japanese Patent Laid-Open No. 5-98081 JP-A-10-251451 JP 2006-258201 A JP 2006-266280 A

  In view of the above problems, the present invention provides a rubber composition that can sufficiently exert a reinforcing effect by a phenol resin organic reinforcing agent on a rubber cured product while containing an ethylene-α-olefin copolymer. It is an object to provide a transmission belt that is elastic but has excellent durability.

  In the present invention relating to the rubber composition for solving the above-mentioned problems, the phenol resin organic reinforcing agent exceeds 0 part by weight and 25 parts by weight with respect to 100 parts by weight of the rubber component containing the ethylene-α-olefin copolymer. Further, it is characterized in that it contains an ethylene copolymer having a polar group in the molecule and is used by crosslinking the rubber component.

  Further, in the present invention relating to the transmission belt for solving the above-mentioned problems, the phenol resin organic reinforcing agent is more than 0 part by weight and 25 parts by weight with respect to 100 parts by weight of the rubber component containing the ethylene-α-olefin copolymer. Further, it is characterized in that at least the surface is formed by a rubber cured product obtained by crosslinking a rubber composition containing an ethylene copolymer having a polar group in the molecule.

The rubber composition of the present invention contains, together with a rubber component containing an ethylene-α-olefin copolymer, a phenol resin-based organic reinforcing agent having a predetermined ratio with respect to the rubber component. Since it contains an ethylene-based copolymer having a polar group, it has durability such as bending resistance and abrasion resistance of a cured rubber product compared to a rubber composition not containing a polar compound such as this ethylene-based copolymer. It is possible to increase the elasticity of the rubber cured product while suppressing the decrease.
Therefore, according to the present invention, it is possible to provide a transmission belt that is highly elastic but excellent in durability.

The width direction sectional view showing the power transmission belt of one embodiment. Schematic which shows a belt running test method.

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. 1 while illustrating a V-ribbed belt.
The V-ribbed belt of this embodiment is formed in an endless shape, and FIG. 1 shows a cross-sectional view of a plane orthogonal to the longitudinal direction (circumferential direction) of the V-ribbed belt 1.
As shown also in FIG. 1, the V-ribbed belt 1 of the present embodiment is provided with a compression rubber layer 10 on the belt inner peripheral surface abutted against a pulley (not shown). A three-layer laminated structure in which an adhesive rubber layer 20 and a cover rubber layer 30 are laminated from the rubber layer 10 toward the outer peripheral surface side is formed.
A core wire 40 is embedded in the adhesive rubber layer 20 so as to extend in the belt longitudinal direction.

The compressed rubber layer 10 is formed with three ribs 12 separated by two grooves 11 having a substantially V-shaped cross section continuous in the belt longitudinal direction, and the ribs 12 are parallel to each other. And is extended in the longitudinal direction of the belt.
The rib 12 is formed so that the cross-sectional shape thereof becomes narrower toward the inner peripheral side, and is formed to have a substantially isosceles trapezoidal cross-sectional shape.

  The compressed rubber layer 10 is formed of a rubber composition containing a rubber component, a phenol resin-based organic reinforcing agent, and a polar compound having a polar group in the molecule, and the rubber component contains the above-mentioned rubber component. The rubber component is formed by a rubber cured product in which the rubber component is crosslinked in a state where the organic reinforcing agent is dispersed.

  The rubber component contains ethylene-α-olefin copolymer rubber as a main component, and as the ethylene-α-olefin copolymer, ethylene and α-olefin are used as copolymer components. It is not particularly limited as long as it is, for example, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-octene copolymer, ethylene-butene copolymer, etc. alone or in combination Can be used.

  Among these, an ethylene-propylene-diene copolymer (EPDM) is preferable in that it is low in cost, excellent in processability, and easy to crosslink.

As the ethylene-α-olefin copolymer as the main component of the rubber component, one containing about 5% of ethylidene norbornene is particularly preferable.
For example, an ethylene-propylene-diene copolymer containing 54 to 56% ethylene, 39 to 41% propylene, and 4 to 6% ethylidene norbornene can be suitably used.
Examples of such an ethylene-propylene-diene copolymer include those commercially available from Dow Chemical Company under the trade name “Nodel IP4640”.

Further, a rubber generally used with the ethylene-α-olefin copolymer as the rubber component, for example, natural rubber, polyisoprene, epoxidized natural rubber, styrene-butadiene copolymer, polybutadiene, acrylonitrile-butadiene copolymer Hydrogenated acrylonitrile-butadiene copolymer, butyl rubber, chlorosulfonated polyethylene, alkylated chlorosulfonated polyethylene, chlorinated polyethylene and the like can be used alone or in combination.
However, the ratio of the total amount of the ethylene-α-olefin copolymer to the total rubber component is preferably 50% by weight or more, and more preferably 80% by weight or more.
In particular, it is preferable that all rubber components are constituted only by an ethylene-α-olefin copolymer.

As the phenol resin-based organic reinforcing agent, a novolak-type or resol-type phenol resin and modified products thereof can be used alone or in combination.
The modified product is partially substituted with a modifying agent using tall oil, cashew oil, xylene resin, tert-butyl group, octyl group, nonyl group, phenyl group, alkylphenyl group, etc. Etc.

More specifically, examples include tall oil-modified novolak-type phenol resins, cashew oil-modified novolak-type phenol resins, xylene resin-modified novolac-type phenol resins, and alkylphenol-modified resol-type phenol resins.
As for these, those commercially available from Sumitomo Bakelite Co., Ltd. under the series name “Sumilite Resin” can be exemplified.

The phenol resin organic reinforcing agent is usually contained in an amount of more than 0 parts by weight and less than 25 parts by weight with respect to 100 parts by weight of the rubber component.
Preferably, the rubber composition is desirably contained in the rubber composition so as to be in the range of 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the rubber component. It is desirable that it is contained in the rubber composition so as to be in any of the ranges of parts by weight or less.

  In addition, it is desirable that the phenol resin-based organic reinforcing agent is contained in the rubber composition in the above ratio with respect to the rubber component. If the above range is exceeded, the compressed rubber layer 10 formed by this rubber composition is desirable. This is because the wear resistance and the bending resistance (crack resistance) may be reduced.

  The polar compound is contained in order to improve the dispersibility of the phenol resin organic reinforcing agent and to exert its reinforcing effect more effectively. In the present embodiment, the rubber composition is crosslinked. From the viewpoint of imparting wear resistance and bending resistance to the cured rubber product, it is important to employ an ethylene copolymer having a polar group in the molecule as the polar compound.

The phenol resin-based organic reinforcing agent has relatively low compatibility with the ethylene-α-olefin copolymer, which is the main component of the rubber composition, for example, an ethylene-α-olefin copolymer and a phenol resin system. When the organic reinforcing agent is mixed, a coarse sea-island structure is formed, and a coarse dispersed phase is formed by phenol resin particles in the ethylene-α-olefin copolymer matrix.
On the other hand, when a polar compound such as an ethylene-based copolymer having a polar group in the molecule is present as in this embodiment, this polar compound acts as a surfactant to convert the phenol resin into, for example, average particles. It can be dispersed in the form of fine particles having a diameter of 2 μm or less.
In this way, the phenol resin organic reinforcing agent is dispersed in a fine state, whereby the reinforcing effect of the phenol resin organic reinforcing agent is sufficiently exerted on the compressed rubber layer formed by the rubber composition, and the High elasticity can be achieved while suppressing a decrease in wear and bending resistance.

  Whether or not the phenol resin organic reinforcing agent is dispersed in a fine state can be confirmed by directly observing the size of the particle by a transmission electron micrograph (TEM), etc. The average particle diameter is calculated by calculating the diameter of a circle having the same area as that of the particles observed by the TEM, and obtaining the diameter of a plurality of particles randomly selected in one field of view of the TEM. Can be obtained by arithmetic averaging.

Examples of the ethylene-based copolymer include a copolymer obtained by copolymerizing a monomer having a polar group such as an epoxy group, a glycidyl group, an acrylate group, a carbonyl group, a nitrile group, and a maleic anhydride group with an ethylene monomer. Among them, the combination of a monomer having an epoxy group or a glycidyl group and ethylene is superior in durability to a compressed rubber layer than a combination of a monomer having a maleic anhydride group and ethylene. It is preferable in that high elasticity can be achieved while imparting properties.
More specifically, an ethylene-glycidyl methacrylate copolymer or a graft copolymer of an ethylene-glycidyl methacrylate copolymer (random copolymer) and a styrene-acrylonitrile copolymer (random copolymer) is preferable. Can be adopted.
As such a polymer type polar compound, a commercial product marketed by Sumitomo Chemical under the “Bond Fast” series name or a commercial product marketed by the NOF Corporation under the “Modiper” series name is used. be able to.

The ethylene copolymer preferably contains the polar group as described above in any proportion within the range of 1 wt% to 20 wt%.
More specifically, it is preferable that the glycidyl methacrylate component is contained in any proportion within the range of 9% by weight to 15% by weight, preferably within the range of 10% by weight to 13% by weight. What is contained in any proportion is more preferable.

Further, this ethylene copolymer is contained in the rubber composition in a proportion usually in the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the rubber component.
Especially, it is preferable to contain in a rubber composition in the ratio used as either in the range of 1 to 3 weight part.

（ただし、Ｒ¹は、水素原子、金属原子、又は、炭素数１から１８の飽和又は不飽和炭化水素であり、該飽和又は不飽和炭化水素は、その一部が置換されていてもよい。）

（ただし、Ｒ²は、水素原子、又は、炭素数１から１８の飽和又は不飽和炭化水素であり、該飽和又は不飽和炭化水素は、その一部が置換されていてもよい。さらに、Ｒ²は、当該１価基が結合している炭素との間に二重結合を形成している炭素に結合して環状構造を形成させていても良い。また、Ｒ³は、水素原子、又は、炭素数１から１８の飽和又は不飽和炭化水素であり、該飽和又は不飽和炭化水素は、その一部が置換されていてもよい。） In addition, as a polar compound which exhibits the same kind of function as the ethylene-based copolymer, for example, an α, β-unsaturated carboxylic acid derivative having a molecular weight of about 1000 or less can be mentioned.
As the α, β-unsaturated carboxylic acid derivative, a monovalent group represented by the following structural formula (1) or (2) is attached to at least one carbon forming a polymerizable carbon-carbon double bond. Compounds having a bonded structure are preferred.

(However, R ¹ is a hydrogen atom, a metal atom, or a saturated or unsaturated hydrocarbon having 1 to 18 carbon atoms, and the saturated or unsaturated hydrocarbon may be partially substituted. )

(However, R ² is a hydrogen atom or a saturated or unsaturated hydrocarbon having 1 to 18 carbon atoms, and the saturated or unsaturated hydrocarbon may be partially substituted. ² may be bonded to carbon forming a double bond with the carbon to which the monovalent group is bonded to form a cyclic structure, and R ³ may be a hydrogen atom, or A saturated or unsaturated hydrocarbon having 1 to 18 carbon atoms, and the saturated or unsaturated hydrocarbon may be partially substituted.)

（ただし、Ｒ⁴、Ｒ⁵はそれぞれ、独立して水素原子、又は、１価の有機基を表す。） Especially, as a compound which has a structure as described in said (1), the compound shown to following Structural formula (3) is suitable, A trimethylol propane trimethacrylate etc. can be used suitably.

(However, R ⁴ and R ⁵ each independently represent a hydrogen atom or a monovalent organic group.)

Moreover, as a compound which has a structure as described in said (2), metaphenylene dimaleimide shown to following Structural formula (4) etc. are suitable.

Other α, β-unsaturated carboxylic acid derivatives include, for example, ethylene glycol diacrylate, diethylene glycol diacrylate, zinc methacrylate, zinc acrylate, magnesium acrylate, magnesium methacrylate, triethylene glycol diacrylate, and diacrylic acid. Decaethylene glycol, pentadecaethylene glycol diacrylate, 1,3-butylene diacrylate, allyl acrylate, pentaerythritol tetraacrylate, diethylene glycol phthalate, dimethacrylate pentacontactor ethylene glycol, pentaacrylate diacrylate Glycol, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, pentaerythritol triacrylate, Pentaerythritol dimethacrylate, 1,1,1-trishydroxymethyl ethane diacrylate, 1,1,1-trishydroxymethyl ethane triacrylate, 1,1,1-trishydroxymethylpropane triacrylate, triacrylic acid Trimethylolpropane, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, decaethylene glycol dimethacrylate, pentadecaethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, allyl methacrylate, (Meth) acrylic monomers such as trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, diethylene glycol dimethacrylate, and the like.
These α, β-unsaturated carboxylic acid derivatives have a functional group that can be bonded by reacting with EPDM or the like while having a polar group having a high affinity for a phenol resin used as an organic reinforcing agent. Therefore, the dispersibility of the phenol resin organic reinforcing agent can be improved.
The α, β-unsaturated carboxylic acid derivative is usually contained in the rubber composition in a proportion of 1 to 15 parts by weight with respect to 100 parts by weight of the rubber component.
Among these, the rubber composition is preferably contained in any proportion within the range of 5 parts by weight or more and less than 15 parts by weight, and the rubber composition is contained in any proportion within the range of 5 parts by weight or more and 10 parts by weight or less. More preferably, it is contained.

The rubber composition of the present embodiment contains the ethylene-based copolymer, so that the dispersibility of the phenol resin-based organic reinforcing agent is improved. This α, β-unsaturated carboxylic acid derivative is added to the rubber composition. By adding, the dispersibility of the phenol resin organic reinforcing agent is further improved.
In addition, the α, β-unsaturated carboxylic acid derivative has the same function as that of the ethylene-based copolymer with respect to the function for increasing the elasticity of the rubber cured product.
Therefore, by including this α, β-unsaturated carboxylic acid derivative instead of containing the ethylene copolymer, the dispersibility of the phenol resin organic reinforcing agent is exerted, and bending resistance and wear resistance are improved. It is possible to increase the elasticity of the rubber cured product while suppressing such a decrease in durability.

That is, in order to increase the elasticity of a rubber cured product while suppressing a decrease in durability, either one of the ethylene copolymer and the α, β-unsaturated carboxylic acid derivative is contained in the rubber composition. Alternatively, both may be used in combination in the rubber composition.
Furthermore, one or more of the ethylene copolymers and one or more of the α, β-unsaturated carboxylic acid derivatives may be combined and contained in the rubber composition.

From the viewpoint of the dispersibility of the phenol resin organic reinforcing agent, it may be possible to finely disperse the phenol resin organic reinforcing agent by carrying out high shear kneading on the rubber composition. As a result of excessive shear stress, there is a risk that the properties of the cured rubber obtained by causing molecular breakage of the rubber to crosslink are deteriorated.
From this, it can be said that the rubber composition in the present embodiment has an effect of facilitating the production of a highly elastic rubber molded product excellent in wear resistance and flex resistance.

  In addition to the above components, the rubber composition can contain compounding agents used in general rubber compositions. Examples of the compounding agent include filler components such as carbon black, silica, and clay. Components for crosslinking such as vulcanizing agents, vulcanization accelerators, vulcanizing aids, processing aids, pigments, anti-aging agents, antioxidants, stabilizers, flame retardants, adhesion promoters, antistatic agents, Etc.

  Examples of the carbon black include carbon black for rubber such as FEF, ISAF, and HAF that are classified by general names.

Examples of the vulcanizing agent include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur (Seimisulfur), dimorpholine disulfide, alkylphenol disulfide, and the like.
Examples of organic peroxide-based crosslinking agents include dicumyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide, 2,5-dimethyl-2,5- Examples thereof include di (t-butylperoxy) hexane, 2,5-dimethylhexane-2,5-di (peroxylbenzoate) and the like.

  Examples of the vulcanization accelerator include vulcanization accelerators such as aldehyde-ammonia, guanidine, thiourea, thiazole, sulfenamide, thiuram, and dithiocarbamate.

Examples of the vulcanization aid include zinc oxide, stearic acid, oleic acid, and zinc salts thereof.
As described above, when the short fiber is contained in the rubber composition used for forming the compression rubber layer of the V-ribbed belt, it tends to cause an increase in processing man-hours and an increase in cost. In the invention, the use thereof is not limited, and the invention can be used as long as the effects of the present invention are not significantly impaired.

As a method for obtaining a rubber composition by mixing the above materials, various methods conventionally used for rubber kneading can be appropriately selected and employed, for example, a calender roll, a kneader, a mixer, etc. The kneading means can be used for blending.
In addition, from the viewpoint of dispersibility of the phenol resin organic reinforcing agent, it is preferable to carry out the kneading in a state of being heated to some extent.

In addition, after preforming using the obtained rubber composition, a molded article formed of a rubber cured product is produced by crosslinking by a general crosslinking means such as can vulcanization or hot press. Can do.
At this time, polar groups and unsaturated bonds of ethylene-based copolymers and α, β-unsaturated carboxylic acid derivatives react with phenolic resins used as organic reinforcing materials or cause bonds with rubber. Thus, the rubber cured product can be made highly elastic, and excellent properties in abrasion resistance and flex resistance are imparted to the rubber cured product.

  In the present embodiment, the effect of the present invention can be exerted particularly remarkably because it is easily influenced by the bending that occurs when the transmission belt is wound around the pulleys while being in contact with the pulleys. In this respect, the case where the rubber composition is used for forming the compressed rubber layer 10 as described above is illustrated. However, if necessary, the rubber composition for forming the cover rubber layer 30 and the adhesive rubber layer 20 is used in the present embodiment. It is also possible to employ a rubber composition in the form.

  In the V-ribbed belt of the present embodiment, the compression rubber layer 10 is formed of the rubber composition as described above, so that the wear of the surface of the compression rubber layer 10 (rib), which is a transmission surface for friction transmission, is prevented and cracks are generated. However, in a portion having a large area exposed on the surface, such as the cover rubber layer 30, wear and cracks are caused in the same manner as the transmission surface. In order to form the cover rubber layer 30, a rubber composition containing an ethylene-α-olefin copolymer, a phenol resin-based organic reinforcing agent, and a polar compound is used to form the cover rubber layer 30. It is also possible to improve durability.

In addition, when the abrasion resistance and the bending resistance are not strongly required for the cover rubber layer 30, these portions can be formed by a general rubber composition.
In addition, the rubber composition according to the present embodiment can be used for forming the cover rubber layer 30 and a general rubber composition can be used for forming the compressed rubber layer 10.
That is, the durability of the V-ribbed belt can be improved by forming at least a part of the belt surface with a cured rubber obtained by crosslinking the rubber composition.

As described above, the same applies to the adhesive rubber layer 20 in that a forming material can be selected from a general rubber composition and a rubber composition according to the present embodiment in accordance with required strength. .
The core 40 is not particularly limited, and a general core used in a conventionally known transmission belt can be used. When rubber paste or the like is used as the surface treatment, the rubber illustrated above is used. It is also possible to employ a composition in which the composition is dispersed in an organic solvent.

  As described above, by providing high elasticity while providing excellent durability, the resulting transmission belt can be suitable for high load applications such as automobile applications.

  In the present embodiment, since the abrasion resistance, the bending resistance, etc. are strongly demanded, a power transmission belt is exemplified as a suitable application of the rubber composition according to the present invention. The composition is not limited to such applications, and for example, even when the rubber composition exemplified above is used for applications such as conveyor belts and various blade materials, the effect can be effectively utilized. Is.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Production of transmission belt for evaluation)
First, a V-ribbed belt having a circumference of about 1100 mm and a width of 10 mm was prepared so as to be an evaluation sample for wear resistance and bending resistance.
The configuration of the V-ribbed belt is the same as that shown in FIG. 1, and a compression rubber layer and a cover rubber layer are laminated and integrated through an adhesive rubber layer in which a core wire is embedded. A rubber composition comprising the following compounding materials was used for the formation.

(Blend material)
1) Base rubber 1: manufactured by Dow Chemical Co., ethylene-propylene-diene copolymer, trade name "NOREL DE IP 4640"
2) Organic reinforcing agent 1: manufactured by Sumitomo Bakelite Co., Ltd., tall oil-modified novolac type phenolic resin, trade name “SUMILITERESIN PR-13355”
3) Organic reinforcing agent 2: manufactured by Sumitomo Bakelite Co., Ltd., cashew oil-modified novolak type phenolic resin, trade name “SUMILISERSIN PR-12687”
4) Organic reinforcing agent 3: Made by company, xylene resin modified novolac type phenol resin, trade name “GP-212”
5) Organic reinforcing agent 4: Sumitomo Bakelite Co., Ltd., alkylphenol-modified resol type phenolic resin, trade name “SUMILISERSIN PR-175”
6) Polar compound 1: manufactured by NOF Corporation, graft copolymer of ethylene-glycidyl methacrylate random copolymer and styrene-acrylonitrile random copolymer, trade name “MODIPA A4400”
7) Polar compound 2: manufactured by Sumitomo Chemical Co., Ltd., ethylene-glycidyl methacrylate copolymer (glycidyl methacrylate 12% by weight), trade name “Bond Fast E”
8) Polar compound 3: manufactured by Uniroyal Chemical, maleated EPDM (maleic anhydride content 1%), trade name “Royal Tough 498”
9) Polar compound 4: manufactured by ARKEMA, ethylene / acrylic acid / maleic anhydride terpolymer (comonomer content 9%), trade name “Bondaine LX4110”
10) Polar compound 5: manufactured by Sumitomo Chemical Co., Ltd., ethylene-methyl methacrylate copolymer (methyl methacrylate 25% by weight), trade name “Aklift AK307”
11) Polar compound 6: manufactured by LANXESS, maleic acid-modified ethylene-propylene copolymer (maleic acid 0.7%), trade name “Buna EPTKA8944”
12) Polar compound 7: manufactured by Seiko Chemical Co., Ltd., trimethylolpropane trimethacrylate (α, β-unsaturated carboxylic acid derivative), trade name “Hicross M”
13) Polar compound 8: Metaphenylene dimaleimide (α, β-unsaturated carboxylic acid derivative) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name “Varnock PM”
14) Polar compound 9: manufactured by Kyoei Chemical Co., Ltd., ethylene diacrylate (α, β-unsaturated carboxylic acid derivative), trade name “Light Acrylate 3EG-A”
15) Polar compound 10: manufactured by Kyoei Chemical Co., Ltd., ethylene dimethacrylate (α, β-unsaturated carboxylic acid derivative), trade name “Light Ester EG”
16) Polar compound 11: manufactured by Kawaguchi Chemical Industry Co., Ltd., zinc acrylate (α, β-unsaturated carboxylic acid derivative), trade name “Actor ZA”
17) Polar compound 12: manufactured by Kawaguchi Chemical Industry Co., Ltd., zinc methacrylate (α, β-unsaturated carboxylic acid derivative), trade name “actor ZMA”
18) Carbon black: manufactured by Tokai Carbon Co., Ltd., HAF, trade name “SEAST 3”
19) Process oil: manufactured by Sun Oil, paraffinic process oil, trade name “Samper 2280”
20) Stearic acid: manufactured by NOF Corporation, bead stearic acid, trade name “Tsubaki”
21) Zinc oxide: Zinc Hana No. 3 22) Organic peroxide: NOF Corporation, Dicumyl peroxide, trade name "Park Mill D"
23) Sulfur 1: manufactured by Tsurumi Chemical Co., Ltd., Oil Sulfur 24) Sulfur 2: manufactured by Nippon Dry Distiller Co., Ltd., insoluble sulfur, trade name “Seimi Sulfur”
25) Vulcanization accelerator: manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., sulfenamide-based vulcanization accelerator (N-oxydiethylene-2-benzothiazolylsulfenamide), trade name “Noxeller MSA”

Using such materials, rubber compositions were prepared according to the formulations shown in Tables 1 to 4.
The kneading conditions at this time were adjusted so as to be substantially constant for all the blends.

(Physical property test)
Further, the rubber composition used for the formation of the compressed rubber layer is vulcanized and formed into a sheet shape, and the sheet-like molded body is used as a test piece, and the tensile strength and elongation at break (based on JIS K6251 (2004)) (Elongation at break) was measured.
The elastic modulus was determined by measuring the elastic modulus (100 ° C.) after storing based on JIS K 6394.
The obtained results are collectively shown in Tables 1 to 4.

(Belt running test)
A belt running test was conducted as shown in FIG.
That is, a large-diameter rib pulley having a pulley diameter of 120 mm arranged on the upper and lower sides (the driven pulley 51 on the upper side and the driving pulley 52 on the lower side), and an idler with a pulley diameter of 70 mm arranged on the right in the horizontal direction at the intermediate position between them In contrast to the pulley 54 and the small-diameter rib pulley 53 having a pulley diameter of 55 mm arranged on the right side of the idler pulley 54, the large-diameter rib pulleys 51 and 52 and the small-diameter rib pulley 53 have a rib forming surface (compressed rubber layer). The transmission belt 50 was wound around the idler pulley 54 so that the back surface (cover rubber layer side) was in contact with the idler pulley 54, and a running test of the belt was performed.
At this time, the idler pulley 54 and the small-diameter pulley 55 are set so that the belt winding angle is 90 degrees and the small-diameter pulley 55 is loaded with a set weight of 834 N in the right direction. A belt running test was conducted.
In the evaluation of bending resistance, the drive pulley 52 was rotated clockwise at a rotational speed of 4900 rpm under the condition of 120 ° C., and the time until a crack occurred on the rib surface was measured.
For wear resistance, the driving pulley 52 was rotated clockwise at 4900 rpm for 24 hours at room temperature, and the weight reduction of the transmission belt before and after this test was measured. It was calculated by dividing.
These results are also shown in Tables 1 to 4 together.

(About organic reinforcing agents)
Table 5 below summarizes the evaluation results for Formulations 1-3, 20, and 21.
Also from this table, in the case where no phenol resin-based organic reinforcing agent is contained (Formulation 20), or in the case where 25 parts by weight or more is contained with respect to 100 parts by weight of the rubber component (Formulation 21), the bending It can be seen that durability and wear resistance tend to be reduced.

(About polar compounds (1))
Table 6 below summarizes the evaluation results for Formulations 13, 14, and 23.
From this table, even when a predetermined amount of the phenol resin-based organic reinforcing agent is contained, in the case where no polar compound is contained (Formulation 23), bending durability and wear resistance tend to be lowered. I know that there is.
In addition, it can be seen that the ethylene copolymer (formulation 13) is more effective in wear resistance than the α, β-unsaturated carboxylic acid derivative (formulation 14), although the amount is small.

(About polar compounds (2))
Table 7 below summarizes the evaluation results for Formulations 1, 7 to 10, 14, 24, and 25.
Also from this table, when an ethylene-based copolymer having an epoxy group or a glycidyl group is employed (formulations 1, 7, and 8), excellent results in bending resistance and wear resistance are obtained. I understand that.
It can also be seen that the tensile strength and wear resistance are improved by the addition of the ethylene-based copolymer.

(About polar compounds (3))
Table 8 below summarizes the evaluation results for Formulations 7, 15, 26, and 27.
Also from this table, the ethylene-based copolymer is preferably contained in the rubber composition in a proportion of any one in the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the rubber component. Especially, it turns out that it is especially preferable to contain in the rubber composition in the ratio which becomes either in the range of 1 to 3 weight part.

(About polar compounds (4))
Table 9 below summarizes the evaluation results for Formulations 1, 7, 13, and 22.
Also from this table, the proportion of α, β-unsaturated carboxylic acid derivative (low molecular weight type polar compound) in the range of 5 to 10 parts by weight with respect to 100 parts by weight of the rubber component. It can be seen that it is preferably contained in the rubber composition.

  As described above, according to the present invention, it is possible to provide a rubber composition that can sufficiently exert the reinforcing effect of a phenol resin-based organic reinforcing agent on a molded body while containing an ethylene-α-olefin copolymer. Recognize.

  1: Transmission belt (V-ribbed belt), 10: Compression rubber layer, 20: Adhesive rubber layer, 30: Cover rubber layer, 40: Core wire

Claims (7)

  An ethylene-based organic reinforcing agent is contained in an amount of more than 0 parts by weight and less than 25 parts by weight with respect to 100 parts by weight of a rubber component containing an ethylene-α-olefin copolymer, and further an ethylene having a polar group in the molecule. A rubber composition comprising a copolymer and used by crosslinking the rubber component.   The rubber composition according to claim 1, wherein the ethylene copolymer is an ethylene copolymer obtained by polymerizing a monomer component containing a monomer having a polar group and an ethylene monomer.   The rubber composition according to claim 2, wherein the content of the monomer having a polar group in the ethylene copolymer is 1% by weight or more and 20% by weight or less.   The rubber composition according to claim 2 or 3, wherein the polar group is any one of an epoxy group, a glycidyl group, an acrylate group, a carbonyl group, and a nitrile group. The α, β-unsaturated carboxylic acid derivative further contains a monovalent group represented by the following structural formula (1) or (2), which is polymerizable carbon. The rubber composition according to any one of claims 1 to 4, which is a compound having a structure bonded to at least one carbon forming a carbon double bond.

(However, R ¹ is a hydrogen atom, a metal atom, or a saturated or unsaturated hydrocarbon having 1 to 18 carbon atoms, and the saturated or unsaturated hydrocarbon may be partially substituted. )

(However, R ² is a hydrogen atom or a saturated or unsaturated hydrocarbon having 1 to 18 carbon atoms, and the saturated or unsaturated hydrocarbon may be partially substituted. ² may be bonded to carbon forming a double bond with the carbon to which the monovalent group is bonded to form a cyclic structure, and R ³ may be a hydrogen atom, or A saturated or unsaturated hydrocarbon having 1 to 18 carbon atoms, and the saturated or unsaturated hydrocarbon may be partially substituted.)   The rubber composition according to claim 5, wherein at least one of metaphenylene dimaleimide and trimethylolpropane trimethacrylate is contained as the α, β-unsaturated carboxylic acid derivative.   An ethylene-based organic reinforcing agent is contained in an amount of more than 0 parts by weight and less than 25 parts by weight with respect to 100 parts by weight of a rubber component containing an ethylene-α-olefin copolymer, and further an ethylene having a polar group in the molecule. A power transmission belt, wherein at least a surface is formed by a rubber cured product obtained by crosslinking a rubber composition containing a copolymer.

Images