JPH0987434A - Rubber composition for transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having high hardness and strength and excellent flexural resistance, abrasion resistance and moldability by compounding a fiber-reinforced thermoplastic composition having a specific composition with a vulcanizable rubber and carbon black at specific ratios. SOLUTION: This rubber composition is produced by compounding (A) a fiber-reinforced thermoplastic composition composed of (i) a vulcanizable rubber, (ii) a polyolefin and (iii) a thermoplastic polymer having amide group in the main chain, wherein the component (iii) is dispersed in the form of fine fibers in a matrix consisting of the components (i) and (ii) and is bonded to the components (i) and (ii), (B) a vulcanizable rubber and (C) carbon black. The amounts of the components (ii), (iii) and (C) are 1-20 pts.wt., 1-20 pts.wt. and 30-70 pts.wt., based on 100 pts.wt. of the sum of the components (i) and (B), respectively. Preferably, the components (i) and (B)are each a hydrogenated nitrile rubber, etc., the component (ii) is a high-density polyethylene, etc., and the component (iii) is nylon 6, etc. The average diameter of the fiber of the component (iii) is preferably 0.05-1μm.

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, which is excellent in workability, strength and durability and has a high hardness. Can be used not only for transmission belts, but also for industrial products such as conveyor belts, hoses, rubber rolls, rubber crawlers, bushes, packings and boots.

[0002]

2. Description of the Related Art Generally, transmission belts are roughly classified into friction transmission belts such as V-belts, V-ribbed belts and flat belts, and meshing transmission belts (toothed belts). These V-belts, V-ribbed belts, toothed belts and the like are used as transmission belts for automobiles. In recent years, due to measures against automobile exhaust gas, energy saving, downsizing, and higher engine output, the transmission belt is also required to be lighter and more durable (bending resistance, abrasion resistance). ing. Therefore, the rubber composition used for the belt is also required to have high hardness, high strength, flex resistance, and abrasion resistance. Conventionally, in order to meet these demands, there is a method of increasing the amount of an inorganic reinforcing agent such as carbon black or a method of mixing short fibers into a rubber belt composition. Although the method of increasing the amount of the reinforcing agent such as carbon black achieves hardness and strength to some extent, it has drawbacks such as difficulty in kneading and deterioration of molding processability due to too high Mooney viscosity of the compound. Have Moreover, the flex resistance is not sufficient. Furthermore, the specific gravity of the rubber compound is increased, so it is not suitable for reducing the weight of the transmission belt. On the other hand, in the method of mixing short fibers, it becomes difficult to mix the short fibers, and the diameter of the short fibers is large, and because the short fibers and the rubber are insufficiently bonded, durability (bending resistance, abrasion resistance It has a drawback that it deteriorates the property).

[0003]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned drawbacks and has excellent workability, high hardness, high strength, and bending resistance.
An object of the present invention is to provide a rubber composition for a power transmission belt, which has excellent wear resistance.

[0004]

According to the present invention, (A) a fiber reinforced thermoplastic composition, that is, (1) vulcanizable rubber (first rubber) (2) polyolefin (3) main chain A composition comprising a thermoplastic polymer having an amide group therein, wherein component (1) and component (2) constitute a matrix, and component (3) is dispersed as fine fibers in the matrix, In addition, component (3) comprises a fiber-reinforced thermoplastic composition in which component (1) and component (2) are combined, (B) vulcanizable rubber (second rubber), and (C) carbon black. The amount of the polyolefin of the component (2) is 1 to 20 parts by weight, and the component (3) is added to 100 parts by weight of the total of the vulcanizable rubber components (the first rubber and the second rubber). 1) to 20% by weight of the thermoplastic polymer having an amide group in its main chain. Part, the amount of (C) carbon black is 3
A rubber composition for a power transmission belt, which comprises 0 to 70 parts by weight, is provided.

Further, according to the present invention, the fine fibers of the thermoplastic polymer having an amide group in the main chain of the component (3) in the fiber reinforced thermoplastic composition (A) are 0.05 to 1.0 μm.
Provided is a rubber composition for a power transmission belt, wherein the rubber composition having an average diameter of m is used for at least a part of a rubber portion constituting a belt. Further, according to the present invention, the polyolefin of the component (2) in the rubber composition for a power transmission belt is 0.2.
For a transmission belt in which a rubber composition having a softening point of 50 ° C. or higher or a melting point in the range of 80 to 250 ° C. dispersed as fine particles of μm or less is used for at least a part of a rubber portion constituting the belt. A rubber composition is provided. Furthermore,
The thermoplastic polymer having an amide group in the main chain of the component (2) and the polyolefin of the component (2) in the fiber-reinforced thermoplastic composition (A) is the vulcanizable rubber (first) of the component (1).
Rubber of 30 to 500 parts by weight and 10 to 500 parts by weight with respect to 100 parts by weight of rubber.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the constituent components of the present invention will be specifically described. The component (1) will be described. Component (1) is preferably a vulcanizable rubber (first rubber), which is a rubber-like polymer having a glass transition temperature of 0 ° C. or lower. Particularly preferably, the glass transition temperature is −20 ° C. or lower. Mooney viscosity (ML _{1 + 4} , 100 ℃)
Is usually about 20 to 150, preferably 30 to 80
If it is less than 20, the physical properties of the vulcanized rubber are inferior, and if it exceeds 150, the processability is inferior, so the above range is preferable. As such a specific example, polybutadiene (B
R), natural rubber (NR), polyisoprene (IR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile rubber (HNBR),
Examples thereof include chlorosulfonated polyethylene (CSM), styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPM, EPDM), butyl rubber (IIR), chlorinated butyl rubber, brominated butyl rubber and the like. Among these, hydrogenated nitrile rubber (HNB
R), chloroprene rubber (CR) and chlorosulphonated polyethylene (CSM) are preferred.

The component (2) will be described. Ingredient (2)
Is a polyolefin having a melting point of 80 to 250
° C. Further, those having a Vicat softening point of 50 ° C. or higher, particularly a Vicat softening point of 50 to 200 ° C. are also preferable. Above all, the melt flow index is 0.2-50g
Those having a range of / 10 minutes are preferred. As such a polyolefin, a homopolymer or copolymer of an olefin having 2 to 8 carbon atoms and 2 to 8 carbon atoms
Copolymer of olefin of 8 and acrylic acid or its ester, copolymer of olefin of 2 to 8 carbon atoms and aromatic vinyl compound such as styrene, chlorostyrene and α-methylstyrene, carbon number of 2 A copolymer of an olefin having 8 carbon atoms and vinyl acetate and a copolymer of an olefin having 2 to 8 carbon atoms and a vinylsilane compound are preferably used. Specifically, for example, high density polyethylene (HDP
E), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polypropylene (PP),
Ethylene-propylene block copolymer, ethylene-propylene random copolymer, poly-4-methylpentene-1 (P4MP1), polybutene-1, polyhexene-
1, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer,
Ethylene-styrene copolymer, propylene-styrene copolymer, ethylene-vinylsilane copolymer, ethylene-
Examples thereof include vinyltriethoxysilane copolymer. Further, halogenated polyolefins such as chlorinated polyethylene, brominated polyethylene, chlorosulfonated polyethylene are also preferably used. These polyolefins may be used alone or in combination of two or more.

Next, the component (3) will be described. The component (3) is a thermoplastic polymer having an amide group in the main chain and has a melting point of 135 ° C to 350 ° C.
A thermoplastic polyamide of 150 to 300 ° C. is preferable. These thermoplastic polyamides have 1
It preferably has a molecular weight in the range of 20,000 to 200,000. Specifically, nylon 6, nylon 6
6, nylon 6-nylon 66 copolymer, nylon 61
0, nylon 612, nylon 46, nylon 11, nylon 12, nylon MXD6 and the like. Further, a polycondensate of a diamine compound and a dicarboxylic acid compound, for example, a polycondensate of xylenediamine and adipic acid, a polycondensate of xylenediamine and pimelic acid, a polycondensate of xylenediamine and speric acid, and xylenediamine. Polycondensates of azelaic acid and xylenediamine and sebacic acid, such as polycondensates of tetramethylenediamine and terephthalic acid, polycondensates of hexamethylenediamine and terephthalic acid, and octamethylenediamine and terephthalic acid Polycondensates of tetramethylenediamine and isophthalic acid, polycondensates of hexamethylenediamine and isophthalic acid, polycondensates of octamethylenediamine and isophthalic acid, and trimethylhexamethylenediamine and isophthalic acid. As a polycondensation product with It is below. As the thermoplastic polyamide, the most preferable one is a thermoplastic polyamide having a melting point of 160 to 265 ° C., and specifically, nylon 6, nylon 66, nylon 6-nylon 66 copolymer, nylon 610, nylon 612. , Nylon 46,
Examples thereof include nylon 11 and nylon 12. One or more of these may be used.

Component (1) in the fiber reinforced thermoplastic composition,
The ratios of the component (2) and the component (3) are as follows. Component (2) is 30 to 50 relative to 100 parts by weight of component (1).
The amount is 0 parts by weight, preferably 30 to 300 parts by weight, and particularly preferably 40 to 200 parts by weight. If the ratio of the component (2) is less than 30 parts by weight, pelletization cannot be performed. If the ratio of the component (2) exceeds 500 parts by weight, workability becomes poor. Ingredient (3) is 1 per 100 parts by weight of ingredient (1).
The range is 0 to 500 parts by weight, preferably 20 to 400 parts by weight, and particularly preferably 30 to 300 parts by weight. When the ratio of the component (3) is less than 10 parts by weight, the productivity is low and the cost is increased. On the other hand, when the ratio of the component (3) exceeds 500 parts by weight, the ratio of the component (3) existing as fine fibers in the composition becomes too small,
Even if such a composition is molded, it becomes difficult to obtain a molded product having a smooth surface and the strength is significantly reduced.

Most of the component (3) is finely dispersed in the matrix of the components (1) and (2) as fine fibers. Specifically, 70% by weight, preferably 80% by weight, particularly preferably 90% by weight or more are uniformly dispersed as fine fibers. The fiber of the component (3) has an average fiber diameter of 1 μm or less, preferably 0.05.
˜1.0 μm range. The aspect ratio (fiber length / fiber diameter) is preferably 10 or more. The component (3) is bound to both the component (1) and the component (2) at the interface. The sum of the component (1) and the component (2) of the component (3) is preferably 1 to 20% by weight, particularly preferably 5 to 15% by weight.

The vulcanizable rubber (B) is the second rubber, preferably a rubber-like polymer having a glass transition temperature of 0 ° C. or lower. Particularly preferably, the glass transition temperature is -2.
It is 0 ° C. or less. Mooney viscosity (ML _{1 + 4} , 10
(0 ° C.) is usually in the range of about 20 to 150, preferably in the range of 30 to 80. If it is less than 20, the physical properties of the vulcanized rubber are inferior, and if it exceeds 150, the processability is inferior, so the above range is preferable. Specific examples thereof include polybutadiene (BR), natural rubber (NR), and polyisoprene (I).
R), chloroprene rubber (CR), acrylonitrile-
Butadiene rubber (NBR), hydrogenated nitrile rubber (HN
BR), chlorosulfonated polyethylene (CSM),
Styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPM, EPDM), butyl rubber (II
R), chlorinated butyl rubber, brominated butyl rubber and the like. Among these, hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), and chlorosulfonated polyethylene (CSM) are preferable. These rubbers may be used alone or in combination of two or more.

When the second rubber of the vulcanizable rubber (B) is kneaded with the fiber-reinforced thermoplastic composition (A), a phase transition occurs in the rubber composition produced, and the fiber-reinforced thermoplastic composition (A The polyolefin of the component (2) having the sea structure in () is dispersed as an island structure, that is, fine particles. The polyolefin fine particles have a particle size of 0.2 μm or less, preferably 0.
It is 1 μm or less. With fine particles of 0.2 μm or more, the bending resistance, which is a characteristic of the present invention, deteriorates and it becomes impossible to prevent the propagation of cracks generated by bending, so 0.2 μm or less is preferable as described above.

As the carbon black (C), those having a particle size of 100 mμ or less and a dibutyl phthalate (DBP) oil absorption amount of 60 mμ / 100 g or more are preferably used. Examples of carbon black varieties include SAF, ISAF,
IISAF-HS, HAF, FEF, GPF, SRF,
Various carbon blacks such as FT are appropriately used.

Each component of the rubber composition for a power transmission belt is a total of vulcanizable rubber components (first rubber and second rubber) 10
The amount of the component (2) polyolefin is 1 with respect to 0 part by weight.
To 20 parts by weight, the amount of component (3) thermoplastic polymer is 1 to 20 parts by weight, and the amount of (C) carbon black is 30 to 70 parts by weight. If the amount of the component (2) polyolefin is less than 1 part by weight, the durability of the vulcanizate (flexibility,
If the amount of component (2) is more than 20 parts by weight, the resulting rubber composition will have poor rubber elasticity, and the Mooney viscosity will be too high and the vulcanizate will have poor abrasion resistance. The range described above is preferred. If the amount of the component (3) thermoplastic polymer is less than 1 part by weight, the processability is poor and the hardness / strength is lowered, so that a rubber composition having excellent durability cannot be obtained. When the amount of the component (3) thermoplastic polymer is more than 20 parts by weight, the Mooney viscosity becomes too high and it becomes difficult to process. The range described above is preferred. If the amount of carbon black (C) is less than 30 parts by weight, the strength and wear resistance of the vulcanizate will be reduced,
If the amount of carbon black (C) is more than 70 parts by weight, the Mooney viscosity of the rubber composition will be too high and it will be difficult to process, and the specific gravity will be too high. As long as each component of the rubber composition for a power transmission belt of the present invention is within the range described above, the rubber composition for a power transmission belt of the present invention has a matrix in which a vulcanizable rubber and a polyolefin constitute a matrix. The thermoplastic polyamide is uniformly dispersed as fine fibers of 0.2 μm, and the thermoplastic polyamide is bonded to the vulcanizable rubber and the polyolefin. The polyolefin bonded to the polyamide forms a crystalline lamella from the fiber surface, and this formed lamella plays the role of an anchor effect, and further strengthens the interfacial bond between the fiber and the rubber of the matrix. On the other hand, the polyolefin combined with rubber is 0.2μ
As fine particles of m or less, they are evenly dispersed in the rubber and exhibit the effect of a reinforcing filler.

The rubber composition for a power transmission belt is manufactured by the following steps. (A) a step of preparing a matrix comprising the component (1) and the component (2), (b) the matrix and the component (3)
And the step of extruding the obtained kneaded product at a temperature equal to or higher than the melting point of the component (3), (c) stretching and / or rolling the extruded product at a temperature lower than the melting point of the component (3). A step of: (d) cutting the string-shaped or band-shaped material obtained by stretching and / or rolling to obtain a fiber-reinforced thermoplastic composition; and (e) adding the fiber-reinforced thermoplastic composition obtained. It can be produced by a step of blending vulcanizable rubber (B) and carbon black (C).

Each step in the method for producing the rubber composition for a power transmission belt of the present invention will be described below. Step (a): A step of preparing a matrix composed of the vulcanizable rubber of the component (1) and the polyolefin of the component (2). The matrix may be prepared by melt kneading component (1), component (2) and coupling agent, melt kneading component (2) and coupling agent, and then melt kneading with component (1). Is mentioned. The melt-kneading temperature is higher than the melting point of the component (2), and the melt-kneading can be performed by an apparatus usually used for kneading resins and rubbers. As such a device, a Banbury type mixer, a kneader, a kneader extruder, an open roll, a single-screw kneader, a twin-screw kneader, or the like is used. Among these devices, the twin-screw kneader is most preferable in that melt kneading can be performed continuously in a short time.

As the coupling agent, a silane coupling agent, a titanate coupling agent, a novolac type alkylphenol formaldehyde initial condensation product, a resol type alkylphenol formaldehyde initial condensation product, a novolac type phenolformaldehyde initial condensation product, a resole type phenol form. The aldehyde initial condensates, unsaturated carboxylic acids and their derivatives, organic peroxides, and the like, which are commonly used as polymer coupling agents, may be used. Of these coupling agents, less vulcanizable rubber or polyolefin gels,
In addition, the silane coupling agent is preferable in that a strong bond is formed at the interface of these components.

Specific examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane,
Vinyltris (β-methoxyethoxy) silane, vinyltriacetoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ -Glycidoxypropylethyldimethoxysilane, γ-glycidoxypropylethyldiethoxysilane, N-β- (aminoethyl)
Aminopropyltrimethoxysilane, N-β- (aminoethyl) aminopropyltriethoxysilane, N-β-
(Aminoethyl) aminopropylmethyldimethoxysilane, N-β- (aminoethyl) aminopropylethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropylmethoxysilane, γ- [N- ( β-methacryloxyethyl) -N, N-
Dimethyl ammonium (chloride)] propyl methoxysilane, styryl diamino silane, etc. are mentioned. Of these, those having a vinyl group and a group and / or a polar group that easily desorbs a hydrogen atom from an alkoxy group and the like are particularly preferable.

The silane coupling agent is preferably 0.1 to 100 parts by weight of the component (2) polyolefin.
The range is 2.0 parts by weight, particularly preferably 0.2 to 1.0 parts by weight. The amount of silane coupling agent is 0.1
When the amount is less than the weight part, a composition having high strength cannot be obtained,
If it is more than 2.0 parts by weight, a composition excellent in modulus cannot be obtained. When the amount of the silane coupling agent is within the above range, a strong bond is formed between the components (1) and (2).

When a silane coupling agent is used,
An organic peroxide can be used together. A radical is formed on the molecular chain of the polyolefin of the component (2) by using the organic peroxide together, and the radical reacts with the silane coupling agent, whereby the radical between the component (2) and the silane coupling agent is formed. Is thought to accelerate the reaction. The amount of the organic peroxide used at this time is 10
The range of 0.01 to 1.0 parts by weight is preferable with respect to 0 parts by weight. When using natural rubber or polyisoprene as the component (1) (rubber having an isoprene structure), it is not necessary to use an organic peroxide. This is because the above reaction occurs due to shearing during kneading.

Organic peroxides having a half-life temperature of 1 minute in the range of the melt-kneading temperature or a temperature about 30 ° C. higher than this temperature, specifically, the half-life temperature of 1 minute is 8.
Those having a temperature of about 0 to 260 ° C. are preferably used. Specific examples of the organic peroxide include 1,1-di-t-butyl-oxy-3,3,5-trimethylcyclohexane and 1,1.
-Di-t-butylperoxycyclohexane, 2,2-
Di-t-butylperoxybutane, 4,4-di-t-butylperoxyvaleric acid n-butyl ester, 2,2
-Peroxyketals such as bis (4,4-di-t-butylperoxycyclohexane) propane, 2,2,4-trimethylpentyl peroxyneodecanoate, α-cumyl peroxyneodecanoate, peroxyneohexanoic acid t-Butyl, t-butyl peroxyneobivalate, t-butyl peroxyacetate, t-butyl peroxylaurylate, t-butyl peroxybenzoate, t-butyl peroxyphthalate, t-butyl peroxyisophthalate. And alkyl peresters.

Step (b): The matrix of the component (1) and the component (2) and the thermoplastic polymer having an amide group in the main chain of the component (3) are used as the component (1), the component (2) and the component (2). 3) A step of melt-kneading and extruding at a temperature higher than any of the melting points. The melt-kneading in step (b) may or may not add a silane coupling agent. Considering productivity, it is preferably not added. Therefore ingredient (3)
In the step of melt-kneading with, a device such as a Banbury type mixer and a twin-screw kneader capable of kneading at a high shear rate is used. The kneaded product obtained in the extrusion step is extruded from a spinneret, an inflation die or a T die. Both spinning and extrusion must be carried out at a temperature above the melting point of component (3). Specifically, it is preferably carried out in a temperature range higher than the melting point of the component (3) by 30 ° C. Even if the melt-kneading is performed at a temperature lower than the melting point of the component (3), the kneaded product does not have a structure in which the fine particles of the component (3) are mixed in the matrix composed of the component (1) and the component (2). Therefore, the component (3) does not form a fine fiber structure even when the kneaded product is spun or drawn.

Stretching and / or rolling step (c): comprises a step of stretching and / or rolling the extrudate at a temperature lower than the melting point of component (3). The string-like or thread-like extrudate obtained in step (b) is stretched and / or rolled to convert the component (3) into a fiber shape to obtain a fiber-reinforced thermoplastic composition. The fine particles of the component (3) in the kneading component are transformed into fibers by extrusion from a spinneret, an inflation die or a T die, and then stretching and / or rolling. This fiber is drawn by subsequent drawing or rolling, and becomes a stronger fiber. Therefore, spinning and extrusion are performed at a temperature equal to or higher than the melting point of component (3), and stretching and rolling are performed at a temperature equal to or lower than the melting point of component (3), specifically, at a temperature lower than the melting point of component (3) by 10 ° C. or less. There is a need to. The drawing or rolling subsequent to the spinning and the extrusion is carried out, for example, by a method in which the yarn extruded from the spinneret is wound on a hobbin while being drafted. Drafting means making the winding speed higher than the spinneret speed. The ratio of take-up speed / spinneret speed (draft ratio) is
It is preferably in the range of 1.5 to 100. The range is more preferably 2 to 70, and particularly preferably 3 to 50. The extruded string-like or thread-like spinning is continuously cooled, drawn or rolled. By cooling, stretching or rolling, a stronger fiber is formed, so that the characteristics of the fiber-reinforced thermoplastic composition can be more exerted, which is preferable.

Step (d): A step of cutting the string-shaped or band-shaped material obtained by stretching and / or rolling to obtain a fiber-reinforced thermoplastic composition. The stretched or rolled fiber reinforced thermoplastic composition is usually pelletized into pellets. By pelletizing, compounding, kneading, and dispersion with rubber, carbon black, etc. added can be performed uniformly and easily.

In the fiber-reinforced thermoplastic composition of the present invention, the component (1) and the component (2) form a matrix,
The component (1) has a structure in which the component (2) is dispersed in an island shape, and the component (1) and the component (2) are bonded to each other at the interface. Furthermore, it is composed of component (1), component (2) and component (3), and component (1) and component (2) form a matrix, and most of component (3) is uniform as fine fibers in the matrix. The fine fibers of the component (3) are bonded to the matrix. The component (3) binds to both the component (1) and the component (2) at the interface. The presence of this interfacial bond causes the component (1) and the component (2) to be extracted when the fiber-reinforced thermoplastic composition is thermally extracted in a solvent that dissolves in both the component (1) and the component (2), such as xylene. Extracted and removed. When the remaining fine fibers of component (3) are dissolved in an o-dichlorobenzene-phenol mixed solvent (85:15) and measured by NMR, peaks derived from component (1) and component (2) are observed. Proved by

Step (e): A step of blending the obtained fiber-reinforced thermoplastic composition (A) with vulcanizable rubber (B) and carbon black (C). 3 to 60 parts by weight of the fiber-reinforced thermoplastic composition and 30 to 70 parts by weight of carbon black (C) are added to 100 parts by weight of a vulcanizable rubber component (first rubber and second rubber). Melt-kneading is performed at a temperature at which the fine fibers of 3) are not melted, at a temperature equal to or lower than the melting point of the component (3), 10 ° C. lower than the melting point, and higher than the melting point of the component (2) and 10 ° C. higher than the melting point. When the amount of the fiber-reinforced thermoplastic composition (A) is less than 3 parts by weight, a rubber composition for a power transmission belt having excellent processability, high hardness, high strength and excellent durability cannot be obtained. On the other hand, if the amount is more than 60 parts by weight, the Mooney viscosity will be excessively increased and the rubber elasticity will be poor, so that a rubber composition for a power transmission belt which is excellent in workability and has high hardness, high strength and excellent durability cannot be obtained. The above range is preferable. If the amount of carbon black (C) is less than 30 parts by weight, the strength and wear resistance of the vulcanizate will be low. On the other hand, if the amount is more than 70 parts by weight, the Mooney viscosity of the rubber composition will be too high, and it will be difficult to process, and the specific gravity will be too high. The rubber composition for a power transmission belt of the present invention can be obtained by melt-kneading within the above range. Melt kneading can be performed by an apparatus usually used for kneading resins and rubbers, and as such an apparatus, a Banbury type mixer, a kneader, a kneader extruder, an open roll, a single-screw kneader, a twin-screw kneader or the like is used. .

Thus, the rubber composition for a power transmission belt of the present invention comprises the above fiber reinforced thermoplastic composition (A), vulcanizable rubber (B), and carbon black (C). Can be used for at least a part of the rubber portion constituting the.

Further, ordinary rubber fibers can be added to the rubber composition for a power transmission belt of the present invention. As short fibers,
Nylon, polyester, aramid, cotton, vinylon,
Rayon, natural cellulose, acrylic, etc. can be used.

In step (e), process oil,
Add zinc white, stearic acid, and anti-aging agent and knead. At this time, the kneading temperature rises, so the temperature is controlled to be not higher than the melting point of the thermoplastic polyamide of component (3), if necessary. The temperature is preferably 120 to 180 ° C., and the kneading time is 1 to 5 minutes. , At this time, the vulcanizing agent and the vulcanization auxiliary together at room temperature to 10
The required amount can be kneaded at 0 ° C. Disperse it evenly and pull it out into a sheet. When the obtained sheet is molded and vulcanized, a vulcanized product of the rubber composition for a power transmission belt is obtained. At this time, the amount of the vulcanizing agent is preferably in the range of 0.1 to 5.0 parts by weight, particularly 0.5 to 3.0 parts by weight, based on 100 parts by weight of the first and second rubbers. The amount of the vulcanization aid is preferably 0.01 to 2.0 parts by weight, and particularly preferably 0.1 to 1.0 part by weight, based on 100 parts by weight of the first and second rubbers. As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxides, resin vulcanizing agents, and metal oxides such as magnesium oxide are used. The vulcanization aid is selected from known vulcanization aids such as aldehydes / ammonias, aldehydes / amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates and xanthates.

In addition to the above, the rubber composition for a power transmission belt of the present invention includes white carbon, activated calcium carbonate, ultrafine magnesium silicate, high styrene resin, phenol resin, lignin, modified melamine resin, coumarone indene resin, petroleum oil. Reinforcing agents such as resins, calcium carbonate, basic magnesium carbonate, clay, Lissajous, diatomaceous earth, recycled rubber, various fillers such as powdered rubber, amines / aldehydes, amines / ketones, amines, phenols, imidazoles, Stabilizers such as sulfur-containing antioxidants and phosphorus-containing antioxidants may be included.

The vulcanization temperature of the rubber composition for a power transmission belt of the present invention is preferably about 100 to 190 ° C. However, the vulcanization temperature needs to be lower than the melting point of the thermoplastic resin forming the fine fibers in the rubber composition. When vulcanization is performed at a temperature equal to or higher than the melting point of this thermoplastic resin, the fibers formed in the stage of adjusting the bent-angle fiber-reinforced thermoplastic composition are melted, excellent in processability, and the hardness and strength of the vulcanized product are high. This is because a rubber composition that is large and has excellent durability cannot be obtained.

[0032]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In Examples and Comparative Examples,
Component (A) Observation of dispersion shape of each component in the fiber reinforced thermoplastic composition, and Mooney viscosity, hardness, tensile elastic modulus, tensile strength, flex resistance and resistance of the obtained rubber composition for a transmission belt. Abrasivity was measured as follows. Observation of dispersion shape: Component (A) fiber-reinforced thermoplastic composition 5
g was refluxed at 100 ° C. in a mixed solvent of o-dichlorobenzene and xylene (volume ratio 50:50) to extract and remove the components (1) and (2), and the remaining fibers were observed with an electron microscope. The average fiber diameter was determined from the obtained image. Mooney viscosity: Mooney viscosity (ML _{1 + 4} , 100 ° C.) was measured according to JIS K6300. Tensile elastic modulus, tensile strength, hardness: The tensile elastic modulus M ₁₀₀ tensile strength and hardness were measured according to JIS K6301. Bending resistance: 2 mm scratch is 1 according to JIS K6301
The number of times until the length became 5 mm was measured, and the index was displayed with Example 3 or Example 9 as 100. The higher the number,
Flex resistance is good. Abrasion resistance: Pico abrasion index was measured according to ASTM D2228. Indexing was performed with Example 3 or Example 9 as 100. The higher the value, the better the wear resistance.

[Sample 1] Hydrogenated nitrile rubber (HNBR, manufactured by Bayer Co., Ltd., Telban 170) as the component (1)
7S HRD, hydrogenation rate 94.5%, acrylonitrile amount 33%, Mooney viscosity ML _{1 + 4} 100 ° C. 74) as component (2) polypropylene (PP, Ube PolyPro J109, melting point 165 ° C., melt) Nylon 6 (Ube Industries, Ube nylon 1030B, melting point 2) as component (3) using flow index 9 g / 10 min)
15-220 degreeC and the molecular weight 30,000) were used. First, 100 parts by weight of component (1), 75 parts by weight of component (2) and 0.5 parts by weight of γ-methacryloxypropyltrimethoxysilane, and 0.1 parts by weight of 4,4-di-t-butyl. Peroxyvaleric acid n-butyl ester was melt-kneaded with a Banbury type mixer, dumped, and then pelletized. Then this matrix and component (3) 87.5
The parts were kneaded with a twin-screw kneader heated to 240 ° C. to pelletize the kneaded product. The obtained kneaded product was extruded into a string shape with a uniaxial extruder set at 245 ° C., and was pelletized with a pelletizer while taking it at a draft ratio of 10. The obtained pellets were refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polypropylene and hydrogenated nitrile rubber, and the shape and diameter of the remaining fibers were observed with an electron microscope,
It was confirmed that the fibers had an average fiber diameter of 0.2μ.

[Sample 2] Sample 1 except that high-density polyethylene (HDPE, manufactured by Maruzen Polymer, Chemilets-HD3070, melting point 130 ° C., melt flow index 8.0 g / 10 minutes) was used as the component (2). Similarly, Sample 2 was prepared and pelletized. The obtained pellets were refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polyethylene and hydrogenated nitrile rubber, and the shape and diameter of the remaining fibers were observed with an electron microscope. It was confirmed that the fiber was 0.2 μm.

[Sample 3] Sample 1 except that low density polyethylene (LDPE, Ube polyethylene F522, melting point 106 ° C., melt flow index 5.0 g / 10 min) was used as the component (2). Similarly, Sample 3 was prepared and pelletized.
The obtained pellets were refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polyethylene and hydrogenated nitrile rubber, and the shape and diameter of the remaining fibers were observed with an electron microscope to determine the average fiber diameter. It was confirmed that the fiber was 0.2μ.

[Sample 4] Sample 1 except that 100 parts by weight of the low density polyethylene of the component (2), 100 parts by weight of the hydrogenated nitrile rubber of the component (1) and 100 parts by weight of the component (3) were used. Sample 4 was prepared in the same manner and pelletized. The obtained pellets were refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polyethylene and hydrogenated nitrile rubber, and the shape and diameter of the remaining fibers were observed with an electron microscope. It was confirmed that the fiber was 0.2 μm.

[Sample 5] As the component (2), 75 parts by weight of low-density polyethylene (LDPE, Ube polyethylene F522, melting point 106 ° C., melt flow index 5.0 g / 10 min) was used, and the component (1 ), Chlorosulfonated polyethylene (CSM, manufactured by DuPont, Hypalon # 40, Mooney viscosity ML _{1 + 4} 100 ° C.)
55) 100 parts by weight, and nylon 6 (manufactured by Ube Industries, Ube nylon 1030B, melting point 215) as component (3)
The sample 5 was prepared in the same manner as the sample 1 using 87.5 parts by weight of ˜220 ° C., molecular weight 30,000) and pelletized. The obtained pellets were refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polyethylene and chlorosulfonated polyethylene, and the shape and diameter of the remaining fibers were observed with an electron microscope to find that the average fiber diameter was 0. It was confirmed that the fiber was 0.2 μm.

Table 1 shows the ratio of each component of Samples 1 to 5 and the shape of the nylon 6 fiber.

[0039]

[Table 1]

Example 1 Using a B type Banbury mixer (capacity: 1.7 L) set at 100 ° C. and 77 rpm, Sample 1 was used as the fiber reinforced thermoplastic composition, and one of the compounding recipes shown in Table 2 was added. A sulfur accelerator and a compounding agent excluding sulfur were kneaded to obtain a kneaded product which was a rubber composition for a power transmission belt. At this time, the maximum kneading temperature was adjusted to 170 to 180 ° C. Next, this kneaded product was kneaded with a vulcanization accelerator and sulfur on a 10-inch roll, rolled out into a sheet, and then put into a mold for vulcanization to obtain a vulcanized product. Vulcanization is 16
It was carried out at 0 ° C. for 20 minutes. The results are shown in Table 2 and other formulations are shown in Table 3.

Examples 2 to 4 The fiber-reinforced thermoplastic composition used was changed as shown in Table 2, and the maximum kneading temperature was 1
It carried out like Example 1 except having changed into 50-160 ° C. The results are shown in Table 2, and other formulations are shown in Table 3.

[Examples 5 and 6] The blending ratio of each component was set to the second
Example 2 was carried out in the same manner as in Example 2 except that the changes were as shown in the table. The results are shown in Table 2 and other formulations are shown in Table 3.

[Examples 7 and 8] The same procedure as in Example 2 was carried out except that the kind of carbon black blended was changed.

Comparative Examples 1 to 5 Compositions were obtained in the same manner as in Example 2 except that the fiber reinforced thermoplastic composition was not used and the components were changed as shown in Table 2. The results are shown in Table 2 and other formulations are shown in Table 3.

[0045]

[Table 2]

[0046]

[Table 3]

Example 9 Using a B-type Banbury mixer (capacity: 1.7 L) set at 100 ° C. and 77 rpm, Sample 5 was used as the fiber-reinforced thermoplastic composition, and one of the compounding recipes shown in Table 2 was added. The compounding ingredients excluding the sulfur accelerator were kneaded to obtain a kneaded product which was a rubber composition for a power transmission belt. At this time, the maximum kneading temperature was adjusted to 150 to 160 ° C. Then, this kneaded product was kneaded with a vulcanization accelerator on a 10-inch roll, rolled out into a sheet, and then placed in a mold and vulcanized at 153 ° C. for 30 minutes to obtain a vulcanized product. . The results are shown in Table 4, and other formulations are shown in Table 5.

[Examples 10 and 11] The same procedure as in Example 9 was carried out except that the mixing ratios of the respective components were changed as shown in Table 3. The results are shown in Table 4, and other formulations are shown in Table 5.

[Comparative Examples 6 to 8] Compositions were obtained in the same manner as in Example 9 except that the fiber reinforced thermoplastic composition was not used and the components were changed as shown in Table 3. The results are shown in Table 4, and other formulations are shown in Table 5.

[0050]

[Table 4]

[0051]

[Table 5]

[0052]

The present invention is a composition comprising a vulcanizable rubber, a polyolefin and a thermoplastic polyamide, wherein the vulcanizable rubber and the polyolefin constitute a matrix, and the thermoplastic polyamide is contained in the matrix. Is uniformly dispersed as fine fibers of 0.2 μm, and the thermoplastic polyamide is bonded to the vulcanizable rubber and the polyolefin. The polyolefin bonded to the polyamide forms a crystalline lamella from the fiber surface, and this formed lamella plays the role of an anchor effect, and further strengthens the interfacial bond between the fiber and the rubber of the matrix. On the other hand, the polyolefin bonded to the rubber is uniformly dispersed in the rubber as fine particles of 0.2 μm or less, and the effect of the reinforcing filler is exhibited. As a result, compared to comparative examples in which carbon black or carbon black and short fibers are blended, a blended belt having a low Mooney viscosity and excellent workability, high hardness, high strength, bending resistance, and abrasion resistance is obtained. Can be provided. Especially, rubber on the transmission belt, adhesive rubber layer,
Applicable to lower rubber, tooth rubber, back rubber, etc. Furthermore, it can be used not only for transmission rubber belts, but also for industrial products such as conveyor belts, hoses, rubber rolls, rubber crawlers, bushes, packings and boots.

Claims (4)

[Claims] 1. A rubber composition for a power transmission belt is (A) a fiber reinforced thermoplastic composition, that is, (1) vulcanizable rubber (first rubber), (2) polyolefin, (3).
A composition comprising a thermoplastic polymer having an amide group in its main chain, wherein component (1) and component (2) form a matrix, and component (3) is dispersed as fine fibers in the matrix. And the component (3) is the component (1)
And a fiber-reinforced thermoplastic composition combined with the component (2), (B) vulcanizable rubber (second rubber), and (C) carbon black, and a vulcanizable rubber 1 to 20 parts by weight of the polyolefin of the component (2) based on 100 parts by weight of the components (the first rubber and the second rubber) in total, and the heat having an amide group in the main chain of the component (3). A rubber composition for a power transmission belt, wherein the amount of the plastic polymer is 1 to 20 parts by weight and the amount of the carbon black (C) is 30 to 70 parts by weight. 2. A patent in which fine fibers of a thermoplastic polymer having an amide group in the main chain of component (3) in a fiber-reinforced thermoplastic composition (A) have an average diameter of 0.05 to 1.0 μm. The rubber composition for a power transmission belt according to claim 1. 3. The polyolefin of the component (2) is 30 to 500 parts by weight and the component (3) with respect to 100 parts by weight of the vulcanizable rubber of the component (1) in the fiber reinforced thermoplastic composition (A). The rubber composition for a power transmission belt according to claim 1, wherein the thermoplastic polymer having an amide group in its main chain is 10 to 500 parts by weight. 4. The component (2) polyolefin is 0.2 μm
The rubber composition for a power transmission belt according to claim 1, which is dispersed as the following fine particles and has a softening point of 50 ° C or higher or a melting point of 80 to 250 ° C.