JPH083369A - Rubber composition for base tread - Google Patents

Abstract

PURPOSE:To obtain a rubber composition, comprising a specific composition, having a low Mooney viscosity and a small die swell and low exothermic characteristics of the valcenizate and excellent in processability. CONSTITUTION:This rubber composition for a base tread is obtained by blending (A) a fiber-reinforced thermoplastic composition containing (iii) a thermoplastic polymer, having amide groups in its main chain and dispersed as fine fibers in a matrix consisting of (i) a polyolefin and (ii) a vulcanizable rubber and the component (iii) bonded to the components (i) and (ii) with (B) a natural rubber and/or a polyisoprene, (C) a dienebased rubber except for the component (B) and (D) carbon black. The amounts of the components based on 100 pts.wt. total amount of the rubber components are l-15 pts.wt. component (iii) and 35-45 pts.wt. component (D). The total amount of the natural rubber or the polyisoprene in the component (A) and the component (B) is 100-50wt.% based on the rubber components. The modulus of repulsion elasticity of a vulcanizate of the composition prescribed in BS 903 is >=60%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to the Mooney viscosity (M
L) and the die swell are small, the processability is excellent, and the vulcanized product has a low exothermic property. The composition of the present invention is further tread in tires, tire external members such as sidewalls, carcass, beads, belts, tire internal members such as chafers, and industrial products such as hoses, belts, rubber rolls and rubber crawlers. Can be used.

[0002]

2. Description of the Related Art Generally, tires are required to have excellent handling properties, durability, etc., and in particular, they are required to have excellent wet skid resistance on wet roads in terms of safety. Further, based on the social demand for resource saving in recent years, in order to reduce dynamic loss in tires, research and development of tires with low rolling resistance, that is, tires with low energy loss are being conducted. The energy loss consumed by the freely rotating tire varies depending on the tire structure and the like, but about 1/2 of the total energy is consumed in the tread portion. Therefore, if the internal consumption of the tread rubber is reduced, the energy loss at the time of rolling of the tire is reduced, and a tire with low rolling resistance can be obtained.

Therefore, it has been attempted to modify the tread rubber so as to reduce the energy loss. However, such rubber modification tends to reduce wet skid resistance. Since the improvement of rolling resistance and the improvement of wet skid resistance are generally contradictory matters, various attempts have been made to improve the tire structure in order to make them compatible. One of the ideas is to make the tread into two layers, a cap tread and a base tread. That is, a cap tread having good wet skid resistance and a base tread having small energy loss are provided in two layers to improve wet skid resistance of the tire and reduce energy loss as a whole.

As the rubber for the base tread, a rubber having a low heat buildup is required. As the rubber having a low heat buildup, natural rubber, isoprene rubber, cis 1,4-polybutadiene rubber may be used alone, or these rubbers may be mixed with carbon black. To reduce the heat buildup, it is conceivable to use carbon black having a large particle size and reduce the amount of carbon black compounded, but these methods lower the elastic modulus and fatigue resistance of rubber.

On the other hand, there is also a method in which short fibers such as nylon and vinylon are blended to make the rubber highly elastic, but since the short fibers do not adhere well to the rubber, the fracture progresses along the interface of the short fibers. It has a drawback that it is easy and has a short fatigue life under repeated elongation. When adopting the cap / base method for passenger car tires, there are manufacturing technical problems not found in large tires. Since the tread gauge is thin, it must be extruded carefully from the extruder without causing edge breakage and with dimensional stability. Moreover, since the cap tread rubber and the base tread rubber have different die swells, caution is required in the case of multilayer extrusion. These problems tend to be solved as the die swell of the base tread rubber becomes smaller. When a large amount of carbon black having a high reinforcing property is blended, the die swell becomes small, but the heat generation becomes large. Therefore, a method for simultaneously satisfying the die swell and the low heat generation has not been found.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a rubber composition for a base tread in which a vulcanized product has low heat buildup and has a small Mooney viscosity and a small die swell.

[0007]

The present invention is directed to a fiber reinforced thermoplastic composition, that is, (1) polyolefin ((1) component) (2) vulcanizable rubber ((2) component) (3) main Thermoplastic polymer having amide groups in the chain
(Component (3)), wherein component (1) and component (2) constitute a matrix, and (3) is contained in the matrix.
A composition in which the components are dispersed as fine fibers, and the component (3) is combined with the components (1) and (2), natural rubber, polyisoprene, or a mixture of both (B). ), A natural rubber and a diene rubber (C) excluding polyisoprene, and carbon black (D), and satisfying the following conditions (i) to (iv): The present invention relates to a rubber composition for use. (I) The amount of the thermoplastic polymer (1) is 1 to 15 parts by weight based on 100 parts by weight of the total of the rubber component, and (i)
i) The total amount of the natural rubber or polyisoprene in the component (A) and the component (B) in the rubber component is 100 to 50% by weight.
And (iii) the amount of carbon black (D) is 35 to 45 parts by weight with respect to 100 parts by weight of the total of the rubber component, and the vulcanized product of the (iv) composition is the impact resilience specified in BS903. The rate is 60% or more.

In the present invention, the fine fibers of the thermoplastic polymer (component (3)) having an amide group in its main chain in the fiber-reinforced thermoplastic composition (A) have a fine fiber content of 0.05 to 1. 0μ
It relates to a rubber composition for a base tread having an average diameter of m.

In the present invention, the polyolefin ((1) component) in the fiber reinforced thermoplastic composition (A) is 50 ° C.
The present invention relates to a rubber composition for a base tread having a softening point or a melting point in the range of 80 to 250 ° C.

Furthermore, in the present invention, the vulcanizable rubber (component (2)) in the fiber-reinforced thermoplastic composition (A) is 10 to 100 parts by weight of polyolefin (component (1)).
It relates to a rubber composition for a base tread which is 400 parts by weight.

The rubber composition for base tread of the present invention has a small Mooney viscosity ML _{1 + 4} (100 ° C.), a swell ratio of 1.8 or less, and a vulcanized product ASTM D62.
Exothermic ΔT due to Method A of 3 is 25 ° C. or less, excellent workability, and low heat buildup of the vulcanized product.

In the present invention, a composition comprising (1) a polyolefin, (2) a vulcanizable rubber, and (3) a thermoplastic polymer having an amide group in the main chain,
The component (1) and the component (2) constitute a matrix, the component (3) is dispersed as fine fibers in the matrix, and the component (3) is the component (1) and the component (2). ) It is essential to blend a fiber-reinforced thermoplastic composition combined with the component, and thereby a rubber composition having excellent processability can be obtained in spite of blending the fibers of the thermoplastic polymer. Of.

First, the fiber-reinforced thermoplastic composition of the present invention will be described. This fiber reinforced thermoplastic composition,
(1) Polyolefin, (2) Vulcanizable rubber, and (3) Thermoplastic polymer having an amide group in the main chain are main constituent components, and (1) component and (2) component form a matrix. Most of the component (3) is dispersed as fine fibers in the matrix. Then, the fine short fibers of the component (3) are bonded to the matrix.

The components (1), (2), and (3) of this fiber-reinforced thermoplastic composition will be described below. The component (1) is a polyolefin, and is 80-
It has a melting point of 250 ° C. Further, those having a Vicat softening point of 50 ° C. or higher, particularly those having a Vicat softening point of 50 to 200 ° C. are also preferably used.

Examples of such polyolefin include C ₂
To C ₈ olefin homopolymers and copolymers, and C
Of ₂ -C ₈ olefin and styrene or chlorostyrene, alpha
A copolymer with an aromatic vinyl compound such as methylstyrene, a copolymer with a C _{2 to} C ₈ olefin and vinyl acetate, a copolymer with a C _{2 to} C ₈ olefin and acrylic acid or its ester, Copolymers of C _{2 to} C ₈ olefins with methacrylic acid or its esters, and C ₂ to
A copolymer of a C ₈ olefin and a vinylsilane compound is preferably used.

Specifically, for example, high density polyethylene, low density polyethylene, polypropylene, ethylene
Propylene block copolymer, ethylene / propylene random copolymer, linear low density polyethylene, poly-4-methylpentene-1, polybutene-1, polyhexene-
1, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / methyl acrylate copolymer,
Ethylene / ethyl acrylate copolymer, ethylene / propyl acrylate copolymer, ethylene / butyl acrylate copolymer, ethylene / 2-ethylhexyl acrylate copolymer, ethylene / hydroxyethyl acrylate copolymer, ethylene / Examples thereof include a vinyltrimethoxysilane copolymer, an ethylene / vinyltriethoxysilane copolymer, an ethylene / vinylsilane copolymer, an ethylene / styrene copolymer, and a propylene / styrene copolymer. or,
Halogenated polyolefins such as chlorinated polyethylene, brominated polyethylene and chlorosulfonated polyethylene are also preferably used. These polyolefins may be used alone or in combination of two or more.

Next, the component (2) will be described.
The component (2) is a vulcanizable rubber, and examples thereof include natural rubber, polyisoprene, polybutadiene, styrene-butadiene rubber, butyl rubber, chlorinated butyl rubber, brominated butyl rubber, and acrylonitrile-butadiene rubber. Of these, natural rubber is preferable. Further, those obtained by subjecting these rubbers to epoxy modification, silane modification, or maleation are also used.

Next, the component (3) will be described.
The component (3) is a thermoplastic polymer having an amide group in the main chain and modified with a silane coupling agent.

Examples of the thermoplastic polymer having an amide group in the main chain include thermoplastic polyamide and urea resin. Of these, the melting point is preferably 135 ° C.
To 350 ° C., and particularly preferable is a thermoplastic polyamide having a melting point of 150 ° C. to 300 ° C.

As the thermoplastic polyamide, nylon 6, nylon 66, nylon 6-nylon 66 copolymer, nylon 610, nylon 612, nylon 46,
Nylon 11, Nylon 12, Nylon MXD6, Polycondensate of xylylenediamine and adipic acid, Polycondensate of xylylenediamine and pimelic acid, Polycondensate of xylylenediamine and speric acid, Xylylenediamine and azelaine Polycondensate with acid, Polycondensate with xylylenediamine and sebacic acid, Polycondensate with tetramethylenediamine and terephthalic acid, Polycondensate with hexamethylenediamine and terephthalic acid, Polycondensation with octamethylenediamine and terephthalic acid Body, polycondensate of trimethylhexamethylenediamine and terephthalic acid, polycondensate of decamethylenediamine and terephthalic acid, polycondensate of undecamethylenediamine and terephthalic acid, polycondensate of dodecamethylenediamine and terephthalic acid, tetramethylene Hexane, a polycondensate of diamine and isophthalic acid Polycondensate of methylenediamine and isophthalic acid, Polycondensate of octamethylenediamine and isophthalic acid, Polycondensate of trimethylhexamethylenediamine and isophthalic acid, Polycondensate of decamethylenediamine and isophthalic acid, Undecamethylenediamine and isophthalic acid Examples thereof include polycondensates of acids and polycondensates of dodecamethylenediamine and isophthalic acid.

Among these thermoplastic polyamides, the most preferable one is a thermoplastic polyamide having a melting point of 160 to 265 ° C., specifically, nylon 6, nylon 66, nylon 6-nylon 66 copolymer, nylon 6
10, nylon 612, nylon 46, nylon 11,
And nylon 12 and the like.

In the thermoplastic composition used in the present invention, the component (1) and the component (2) form a matrix. This matrix may have a structure in which the component (2) is dispersed in the component (1) in an island shape, and conversely, a structure in which the component (1) is dispersed in the component (2) in an island shape. May be taken. The component (1) and the component (2) are preferably bonded to each other at the interface.

Most of the component (3) is dispersed in the matrix as fine fibers. Specifically, 70% by weight, preferably 80% by weight, and particularly preferably 90% by weight or more are dispersed as fine fibers.
The average fiber diameter of the fibers of the component (3) is preferably 1 μm or less, and a particularly preferable range is 0.05 to 0.8 μm.
m. Aspect ratio (fiber length / fiber diameter) is 1
It is preferably 0 or more. And the component (3) is
The matrix composed of the components (1) and (2) is bonded to the interface. This can be confirmed, for example, as follows. First, the fiber-reinforced thermoplastic composition is refluxed in a solvent that dissolves only the components (1) and (2), such as xylene, to remove the components (1) and (2). When the remaining fiber of the component (3) was dissolved in a solvent and the NMR was measured, the components (1) and (2)
The peaks derived from the components can be observed. This is considered to indicate that the component (1) and the component (2) are bound to the surface of the fiber in some form.

The proportions of the component (1), the component (2), and the component (3) are preferably as follows. The component (2) is preferably in the range of 10 to 400 parts by weight, particularly preferably in the range of 20 to 250 parts by weight, and most preferably in the range of 50 to 200 parts by weight, relative to 100 parts by weight of the component (1).
The ratio of the component (2) is 30 with respect to 100 parts by weight of the component (1).
If it is more than 0 parts by weight, only a fiber-reinforced thermoplastic composition which is difficult to pelletize can be obtained, which is not preferable. The ratio of the component (3) is 10 to 40 with respect to 100 parts by weight of the component (1).
It is preferably in the range of 0 parts by weight, particularly 5 to 300
A range of parts by weight is preferred and a range of 10 to 300 parts by weight is most preferred. The ratio of (3) component is (1) component 100
When it exceeds 400 parts by weight, fine fibers of the component (3) are not formed in the fiber-reinforced thermoplastic composition, so that a fiber-reinforced elastic body is produced using such a fiber-reinforced thermoplastic composition. This is because a fiber-reinforced elastic body having high strength cannot be obtained.

The fiber-reinforced thermoplastic composition can be manufactured by the following steps. The fiber-reinforced thermoplastic composition of the present invention comprises the following steps, namely, step 1: a step of preparing a matrix comprising the components (1) and (2), step 2: the component (3) is reacted with a binder. Step, Step 3: A step of melting and kneading the matrix and the component (3) reacted with the binder, Step 4: The obtained kneaded product is extruded at a temperature equal to or higher than the melting point of the component (3), and then It can be produced by a step of stretching and / or rolling at a temperature lower than the melting point of the component (3).

First, the step of preparing a matrix comprising the components (1) and (2) will be described. To prepare a matrix composed of the components (1) and (2),
For example, the component (1) may be first melt-kneaded together with the binder to react, and this may be melted and kneaded with the component (2).
Further, the component (1) and the component (2) are melted together with a binder,
You may knead. The melting and kneading can be performed by an apparatus that is usually used for kneading resins and rubber. As such an apparatus, a Banbury type mixer, a kneader, a kneader extruder, an open roll, a uniaxial kneader,
A biaxial kneader or the like can be used.

The amount of the binder is preferably in the range of 0.1 to 2.0 parts by weight, and particularly preferably in the range of 0.2 to 1.0 part by weight, relative to 100 parts by weight of the component (1). When the amount of the binder is less than 0.1 part by weight, a composition having high strength cannot be obtained, and when it is more than 2.0 parts by weight, a composition having an excellent modulus cannot be obtained.

As the binder, a silane coupling agent,
Titanate coupling agent, novolac type alkylphenol formaldehyde initial condensation product, resol type alkylphenol formaldehyde initial condensation product, novolac type phenolformaldehyde initial condensation product, resole type phenolformaldehyde initial condensation product, unsaturated carboxylic acid and its derivatives, organic peroxides, etc. Any of the commonly used polymer coupling agents can be used. Among these binders, the silane coupling agent is preferable because it hardly gels the component (1) or the component (2) and can form a strong bond at the interface between these components. Examples of the silane coupling agent include vinylalkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris (β-methoxyethoxy) silane, vinyltriacetylsilane, γ-methacryloxypropyltrimethoxysilane, γ- [N- (Β-
Methacryloxyethyl) -N, N-dimethylammonium (chloride)] propylmethoxysilane, styryldiaminosilane, etc., having a group and / or a polar group that easily desorbs a hydrogen atom from other groups such as vinyl group and alkyloxy group. Silane coupling agents are preferably used.

When using a silane coupling agent as a binder, an organic peroxide can be used together. As the organic peroxide, one having a one-minute half-life temperature in the range of the same temperature as the melting point of the component (1) or the melting point of the component (2), whichever is higher, or about 30 ° C. higher than this temperature. It is preferably used. Specifically, the one-minute half-life temperature is 110
Those having a temperature of about 200 ° C. are preferably used. Examples of the organic peroxide include 1,1-di-t-butylperoxy-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-
Bis (4,4-di-t-butylperoxycyclohexane) propane, 2,2,4-trimethylpentyl peroxyneodecanoate, α-cumyl peroxyneodecanoate, t-butyl peroxyneohexanoate, peroxypivalin T-butyl acid, t-butyl peroxyacetate, t-butyl peroxylaurylate, t-peroxybenzoic acid
-Butyl, t-butyl peroxyisophthalate and the like can be mentioned.

The amount of the organic peroxide used is (1) component 10
The range of 0.01 to 1.0 parts by weight is preferable with respect to 0 parts by weight.

However, when the components (1) and (2) are melted and kneaded together with a silane coupling agent to modify the silane, the component (2) includes natural rubber and polyisoprene.
Alternatively, when the styrene / isoprene / styrene block copolymer is used, the organic peroxide may not be used.
Rubber having an isoprene structure, such as natural rubber, polyisoprene, and styrene / isoprene / styrene block copolymers, is a type that has a -COO / group at the end of the main chain due to the main chain breaking due to a mechanochemical reaction during kneading. This is because it is considered that the above-mentioned peroxide is generated, and that this acts almost in the same manner as the above-mentioned organic peroxide.

Next, the step of kneading the component (3) with the above matrix will be described. The component (3) may be melt-kneaded with the binder in advance and reacted, and then melt-kneaded with the matrix, or may be melt-kneaded with the matrix in the presence of the binder. Melt kneading can be carried out with an apparatus usually used for kneading resins and rubbers, for example, Banbury type mixer, kneader, kneader extruder, open roll, uniaxial kneader, and biaxial kneader. The same as in the case of preparation.

In the case of the binder for the component (3),
When the total amount of the component (3) and the binder is 100% by weight, the range of 0.1 to 5.5% by weight is preferable, and the range of 0.2 to
A range of 5.5% by weight is particularly preferable, 0.2 to 3% by weight
Is most preferable.

As the binder, a silane coupling agent,
Titanate coupling agent, novolac type alkylphenol formaldehyde initial condensation product, resol type alkylphenol formaldehyde initial condensation product, novolac type phenolformaldehyde initial condensation product, resole type phenolformaldehyde initial condensation product, unsaturated carboxylic acid and its derivatives, organic peroxides, etc. Any of the commonly used polymer coupling agents can be used. Among these binders, the silane coupling agent is the most preferable in that it hardly gels the component (3) and can form a strong bond at the interface with the matrix.

Examples of the silane coupling agent include those having an alkyloxy group or the like and a group capable of forming a bond with the nitrogen atom of the —NHCO— bond of the component (3) by a dehydration reaction or dealcoholization reaction. Specific examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β
-Methoxyethoxy) silane, etc., vinylalkoxysilane, vinyltriacetylsilane, γ-methacryloxypropyltrimethoxysilane, γ- [N- (β-methacryloxyethyl) -N, N-dimethylammonium (chloride)] propylmethoxy Examples thereof include silane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, styryldiaminosilane, and γ-ureidopropyltriethoxysilane.

In this step, the matrix and (3)
The temperature for melting and kneading the components must be at least the melting point of the component (3). Even if melting and kneading are 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 dispersed in the matrix, and thus the kneaded product is spun. The reason for this is that the component (3) cannot be made into fine fibers even when stretched. The kneading temperature is
It is preferable that the temperature is equal to or higher than the melting point or Vicat softening point of the component (1) polyolefin.

The kneaded material obtained in the above step is extruded from a spinneret, an inflation die or a T die, and then stretched or rolled.

In this step, the fine particles of the component (3) in the kneaded material are transformed into fibers by spinning or extrusion.
This fiber is subjected to a drawing treatment by subsequent drawing or rolling to become a stronger fiber. Therefore, spinning and extrusion must be carried out at a temperature above the melting point of component (3),
Stretching and rolling must be carried out at a temperature lower than the melting point of component (3).

Spinning or extrusion, and subsequent stretching or rolling may be carried out, for example, by extruding the kneaded product from a spinneret, spinning it into a string or thread, and winding it on a bobbin while drafting it. Can be implemented. Here, "drafting" means that the winding speed is higher than the spinning speed. The winding speed / spinning speed ratio (draft ratio) is 1.5 to
The range of 100 is preferable, and the range of 2 to 50 is particularly preferable. The most preferable draft ratio range is 3 to 30.

This step can also be carried out by continuously rolling the spun kneaded material with a rolling roll or the like. Further, the kneaded product can be extruded from an inflation die or a T die and wound on a roll or the like while being drafted. Further, instead of winding a draft while winding it on a roll, it may be rolled by a rolling roll or the like.

The fiber-reinforced thermoplastic composition (A) after stretching or rolling is preferably pelletized. The fiber-reinforced thermoplastic composition is made into pellets, such as natural rubber, polyisoprene or a mixture of both (B), diene rubber (C) excluding natural rubber and polyisoprene, and carbon black (D), This is because they can be kneaded uniformly.

Next, the rubber composition for a base tread of the present invention comprises the above-mentioned fiber reinforced thermoplastic composition (A), natural rubber, polyisoprene or a mixture of both (B), diene excluding natural rubber and polyisoprene. It is made by blending a system rubber (C) and carbon black (D).

Examples of the above-mentioned diene rubber (C) include polybutadiene, styrene-butadiene copolymer rubber, isoprene-isobutylene copolymer and the like. As the carbon black (D), those having a particle size of 90 mμ or less and a dibutyl phthalate (DBP) oil absorption amount of 70 ml / 100 g or more are preferably used. Examples of carbon black include FEF, FF, GPF, SAF, ISAF,
Various carbon blacks such as SRF and HAF are used.

In each of the above components, (i) the amount of the thermoplastic polymer (component (3)) is 1 to 15 parts by weight based on 100 parts by weight of the total of the rubber components, and (ii) the rubber component,
The total amount of the natural rubber or polyisoprene in the component (A) and the component (B) is 100 to 50% by weight, (iii)
The amount of carbon black (D) is 35 to 45 parts by weight based on 100 parts by weight of the total rubber component, and the vulcanized product of the composition (iv) has a repulsion elastic modulus of 6 defined in BS903.
It is blended so as to satisfy each condition that it is 0% or more.

If the amount of the thermoplastic polymer is less than the above lower limit, a Mooney viscosity and die swell are small, and a rubber composition having a large repulsion elastic modulus of a vulcanized product cannot be obtained, and the amount of the thermoplastic polymer is more than the above upper limit. And the Mooney viscosity and die swell of the composition tend to increase. If the blending ratio of the natural rubber or polyisoprene is outside the above range, the exothermic property of the vulcanized product tends to deteriorate. If the amount of carbon black is less than the lower limit, the impact resilience of the vulcanizate will be small, and if the amount of carbon black is more than the upper limit, the Mooney viscosity and die swell of the rubber composition will be large and the exothermicity of the vulcanizate will be high. It tends to get worse. Further, if the impact resilience of the vulcanized product is outside the above range, it is not suitable as a rubber composition for a base tread.

The rubber composition for a base tread of the present invention can be obtained by mixing the above components using a kneading machine such as a Banbury mixer, a kneader, an open roll, and a twin-screw kneader. The kneading temperature needs to be lower than the melting point of the thermoplastic polymer that constitutes the fine short fibers in the fiber-reinforced thermoplastic composition. Kneading at a temperature higher than the melting point of this thermoplastic polymer is not preferable because the fine short fibers in the fiber-reinforced thermoplastic composition are melted and transformed into spherical particles or the like.

Further, it is preferable to use pellets as the fiber-reinforced thermoplastic composition. When the pellet-shaped fiber-reinforced thermoplastic composition is used, the fiber-reinforced thermoplastic composition (A) can be uniformly kneaded with the components (B), (C) and (D), and fine fibers are uniformly dispersed. This is because the rubber composition for the base tread can be easily obtained.

Additives such as a vulcanizing agent are added to the rubber composition for a base tread of the present invention. As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxides, and sulfur-containing compounds can be used. The method of compounding the vulcanizing agent with the rubber composition is not particularly limited, and a compounding method known per se can be adopted. With the vulcanizing agent,
White carbon, activated calcium carbonate, ultrafine magnesium silicate, high styrene resin, coumarone indene resin, phenol resin, lignin, modified melamine resin,
Reinforcing agents such as petroleum resin, various grades of calcium carbonate,
Fillers such as basic magnesium carbonate, clay, zinc white, diatomaceous earth, recycled rubber, powdered rubber, and ebonite powder,
Vulcanization accelerators for aldehydes, ammonias, aldehydes / amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates, xanthates, etc., vulcanization accelerators for metal oxides, fatty acids, amines, etc.
Aldehydes, amines / ketones, amines, phenols, imidazoles, sulfur-containing or phosphorus-containing antioxidants, naphthene-based or aromatic process oils, etc. are added within the range that does not impair the effects of the present invention. Can be used to prepare the composition. In particular, it is preferable to add 1 to 30 parts by weight of process oil to 100 parts by weight of rubber in the composition of the present invention.

The vulcanization temperature of the rubber composition of the present invention is 100-.
About 190 ° C is preferable. 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 preparing the bent-angle fiber-reinforced thermoplastic composition are melted, and the workability is excellent, and the exothermic property of the vulcanized product is small. This is because a rubber composition cannot be obtained.

Since the rubber composition of the present invention has a small die swell and the vulcanized product has a low heat-generating property, it is used as a tire member for passenger cars, buses, trucks, airplanes, etc. in place of the conventionally known rubber composition for base tread. As other tire components (cap tread, sidewalls, chafers, rims,
Bead etc.).

[0051]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. In Examples and Comparative Examples,
Observation of dispersion shape of (component (3)) in the fiber-reinforced thermoplastic composition, and Mooney viscosity, swell ratio, tensile modulus, tensile strength, hardness, repulsion of the obtained rubber composition for base tread The elastic modulus and heat generation characteristics were measured as follows.

(1) (3) in the fiber reinforced thermoplastic composition
Observation of dispersion form of components: Pellets of each sample were mixed with a mixed solvent of o-dichlorobenzene and xylene (volume ratio 50: 5).
The mixture was refluxed in 0) at 100 ° C. to extract and remove the polyolefin and elastomer therein, and the remaining fibers were observed with an electron microscope. (2) Mooney viscosity According to JIS K6300, Mooney viscosity M at 100 ° C.
L _{1 + 4} was measured. (3) Die swell The unvulcanized rubber composition was measured using a capillary rheometer at a die L / D of 2 mm / 1 mm, an extrusion temperature of 100 ° C., and a shear rate of 360 sec ⁻¹ . (4) Tensile Elastic Modulus, Tensile Strength, Hardness Tensile elastic modulus M ₁₀₀ , tensile strength, and hardness were measured according to JIS K6301. (5) Repulsion elastic modulus It measured according to BS903 using a Dunlop trypsometer. (6) Exothermic characteristics It was measured according to Method A of ASTM D623.

[Sample 1] As the component (1), polypropylene (Ube Polypro JI0 manufactured by Ube Industries, Ltd.)
9, melting point 165 to 170 ° C., melt flow index 9 g / 10 min), and natural rubber (N) as component (2)
R, SMR-L) as component (3), nylon 6 (manufactured by Ube Industries, Ube nylon 1030B, melting point 21)
5 to 220 ° C. and a molecular weight of 30,000) were used. (1)
The components are 0.5 parts by weight of γ-methacryloxypropyltrimethoxysilane and 0.1 parts by weight of 4,4-di-t-butylperoxyvaleric acid n based on 100 parts by weight of the component (1). -Modified by melt-kneading with butyl ether. The component (3) was modified by melt-kneading with 1.0 part by weight of N-β (aminoethyl) γ-aminopropyltrimethoxysilane with respect to 100 parts by weight of the component (3).

First, 100 parts by weight of the component (1) modified as described above was kneaded with 100 parts by weight of the component (2) in a Banbury type mixer to prepare a matrix. This was dumped at 170 ° C. and pelletized. Next, this matrix and 100 parts by weight of the component (3) were kneaded with a biaxial kneader heated to 240 ° C. to pelletize the kneaded product. The obtained kneaded product was extruded in a string shape by a uniaxial extruder set at 245 ° C., and pelletized by a pelletizer while being taken at a draft ratio of 10. The obtained pellets were refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polyolefin and NR, and the shape and diameter of the remaining fibers were observed with an electron microscope. It was confirmed that it was a fiber.

[Sample 2] Sample 2 was prepared in the same manner as Sample 1 except that the proportion of nylon 6 as the component (3) was increased to 200 parts by weight relative to 100 parts by weight of the polypropylene as the component (1). , This was pelletized. The obtained pellets were refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polyolefin and NR, and the shape and diameter of the remaining fibers were observed with an electron microscope. It was confirmed that it was a fiber.

[Sample 3] Sample 1 except that the polypropylene as the component (1) was 100 parts by weight, the natural rubber as the component (2) was 75 parts by weight, and the nylon 6 as the component (3) was 87.5 parts by weight. Sample 3 was prepared in the same manner as in 1. and pelletized. The obtained pellets were refluxed in a mixed solvent of o-dichlorobenzene and xylene to remove polyolefin and NR, and the shape and diameter of the remaining fibers were observed with an electron microscope. It was confirmed that it was a fiber. Table 1 shows the ratio of each component of Samples 1 to 3 and the shape of the nylon 6 fiber.

Example 1 A B type Banbury (volume: 1.7 liters) set at 100 ° C. and 77 rpm was used, and Sample 1 was used as the fiber reinforced thermoplastic composition. A compounding agent other than the accelerator and sulfur was kneaded to obtain a kneaded product which was a rubber composition for a base tread. 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 placed in a mold for vulcanization to obtain a vulcanized product. Vulcanization is 1
It was carried out at 45 ° C. for 40 minutes. The results are summarized in Table 2.

[Examples 2 and 3] A rubber composition for a base tread was obtained in the same manner as in Example 1 except that the fiber-reinforced thermoplastic composition used was changed to the sample shown in Table 2.
The results are summarized in Table 2.

[Examples 4 to 6] Table 2 shows the blending ratio of each component.
A rubber composition for a base tread was obtained in the same manner as in Example 1 except that the rubber composition was changed as shown in FIG. The results are summarized in Table 2.

[Examples 7 to 10] The same procedure as in Example 1 was carried out except that the kind of carbon black blended was changed. The results are summarized in Table 2.

Comparative Example 1 A rubber composition for a base tread was obtained in the same manner as in Example 1 except that the ratio of each component was changed as shown in Table 2 without using the fiber reinforced thermoplastic composition. . The results are summarized in Table 2.

[0062]

[Table 1]

[0063]

[Table 2]

(Note 1) BR: polybutadiene (UBEP
OL-BR100, manufactured by Ube Industries, Ltd. (Note 2) SBR: styrene-butadiene copolymer rubber (SBR-1500, manufactured by Nippon Synthetic Rubber Co., Ltd.) (Note 3) N-330: HAF, particle diameter 30 mμ , DBP
Oil absorption 110ml / 100g N-440: FF, particle size 38mμ, DBP oil absorption
75ml / 100g N-550: FEF, particle size 41mμ, DBP oil absorption 1
22ml / 100g N-660: GPF, particle size 84mμ, DBP oil absorption
81ml / 100g N-770: SRF, particle size 71mμ, DBP oil absorption
76ml / 100g (Note 4) Other compounding agents Zinc white: 3 parts, stearic acid: 2 parts, anti-aging agent N-
Phenyl-N'-isopropyl-p-phenylenediamine: 1 part, vulcanization accelerator N-oxydiethylenebenzothiazyl-2-sulfenamide: 0.8 part, sulfur:
1.5 copies

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C08L 23/02 LCV 77/00 LQS // (C08L 21/00 77:00)

Claims (4)

[Claims] 1. A fiber reinforced thermoplastic composition, that is, (1) polyolefin (hereinafter referred to as (1) component) (2) vulcanizable rubber (hereinafter referred to as (2) component) (3) main chain Thermoplastic Polymer Having Amido Group
(Hereinafter, referred to as (3) component), wherein the (1) component and the (2) component form a matrix, and the (3) is contained in the matrix.
A composition in which the components are dispersed as fine fibers, and the component (3) is combined with the components (1) and (2), natural rubber, polyisoprene, or a mixture of both (B). ), A natural rubber and a diene rubber (C) excluding polyisoprene, and carbon black (D), and satisfying the following conditions (i) to (iv): Rubber composition. (I) The amount of the thermoplastic polymer (3) is 1 to 15 parts by weight based on 100 parts by weight of the total rubber component, (ii) the natural rubber or polyisoprene in the component (A) in the rubber component. And (B) component is 100 to 50% by weight, (iii) the amount of carbon black (D) is 35 to 45 parts by weight based on 100 parts by weight of rubber component, and (iv) The vulcanized product of the composition has a rebound resilience of 60% or more as defined by BS903. 2. Fine fibers of a thermoplastic polymer (component (3)) having an amide group in its main chain in the fiber-reinforced thermoplastic composition (A) have an average diameter of 0.05 to 1.0 μm. The rubber composition for a base tread according to claim 1, which comprises: 3. The polyolefin (component (1)) in the fiber-reinforced thermoplastic composition (A) has a softening point of 50 ° C. or higher or a melting point in the range of 80 to 250 ° C.
Alternatively, the rubber composition for a base tread according to claim 2. 4. The vulcanizable rubber (component (2)) in the fiber-reinforced thermoplastic composition (A) is 10 to 400 parts by weight based on 100 parts by weight of the polyolefin (component (1)). The rubber composition for a base tread according to any one of claims 1 to 3.