JP2002096605A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which exhibits stable performances regardless of road surface conditions such as dry, wet, ice-covered or snow-covered and is improved in its wet performance and dry performance, while maintaining its superior performances against ice and snow. SOLUTION: This pneumatic tire is characterized by possessing at least a tread part composed of a tread pattern with a snow traction index(STI) of 150 or higher and by containing at least 0.5-10 pt.wts. of short fibers per 100 pt.wts. of rubber components in the tread part. Desirable short fibers are 0.01-0.1 mm in average diameter and 0.5-10 mm in average length, and consist of at least one type of polyethylene short fibers, polypropylene short fibers, aliphatic polyamide short fibers, aromatic polyamide short fibers, polyester short fibers and polyvinylacohol short fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides stable performance regardless of whether it is a dry road surface, a rainy road surface, an icy road surface, a snowy road surface, etc., while maintaining excellent ICE performance and SNOW performance while maintaining WET performance. The present invention relates to a pneumatic tire with improved DRY performance.

[0002]

2. Description of the Related Art Since spike tires have been regulated, IC
In order to improve E performance and SNOW performance (braking / driving performance of tires on icy roads and snowy roads), research on treads of pneumatic tires has been actively conducted. By the way, in the tread of a pneumatic tire, when the ICE performance / SNOW performance is improved, the block rigidity of the tread is reduced, and the DRY performance / WET performance (braking / driving performance of the tire on a dry road surface or a rainy road surface) is reduced. ) Tends to decrease. For this reason, it is desired to provide a pneumatic tire capable of maintaining these performances in a well-balanced and high level.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to meet the above-mentioned demands and achieve the following objects. That is,
The present invention provides air that exhibits stable performance regardless of whether it is a dry road surface, a rainy road surface, an icy road surface, a snowy road surface, etc., and has improved WET performance and DRY performance while maintaining excellent ICE performance and SNOW performance. It is intended to provide a tire including a tire.

[0004]

Means for solving the above problems are as follows. That is, <1> Snow Traction Index (ST
I) has at least a tread portion on which a tread pattern having 150 or more is formed, and the tread portion has
A pneumatic tire comprising at least 0.5 to 10 parts by weight of short fibers with respect to 100 parts by weight of a rubber component. <2> The pneumatic tire according to <1>, wherein the short fibers have an average diameter of 0.01 to 0.1 mm. <3> The pneumatic tire according to <1> or <2>, wherein the average length of the short fibers is 0.5 to 10 mm. <4> The above-mentioned <1>, wherein the short fibers are heat-meltable or thermosoftening.
> The pneumatic tire according to any one of <3>. <5> The pneumatic tire according to <4>, wherein the short fibers have a melting point or a softening point of 100 to 190 ° C. <6> The above <1>, wherein the staple fiber is at least one selected from polyethylene staple fiber, polypropylene staple fiber, aliphatic polyamide staple fiber, aromatic polyamide staple fiber, polyester staple fiber, and polyvinyl alcohol staple fiber.
To <5>. <7> The above <1> in which the short fibers are oriented in the tire circumferential direction.
To <6>.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pneumatic tire of the present invention will be described below in detail. The pneumatic tire of the present invention has a snow traction index (STI).
The other configuration is not particularly limited as long as it has at least a tread portion on which a tread pattern having a value of 150 or more is formed, and can be appropriately selected depending on the purpose.

-Tread portion- The tread portion is not particularly limited except that a tread pattern having a snow traction index (STI) of 150 or more is formed, and an appropriately selected structure or the like can be adopted. .

[0007] The snow traction index (STI) is an index indicating a performance level on snow calculated by a component in a tire section direction (tire width direction) of a groove and a calf length of a tread pattern surface and a groove depth. Meaning, SAE Technical Paper Ser
ies 820345.

[0008] The snow traction index (STI) must be 150 or more.
50 to 260 is preferable, and 150 to 200 is more preferable. The snow traction index (ST)
If I) is less than 150, the SNOW performance and the I
If the CE performance is not sufficient, on the other hand, if it is 150 or more, there is no such case, and the SNOW performance, the ICE performance, the WET performance, and the DRY performance are exhibited in a well-balanced manner. The rigidity of the tread portion may decrease, and the DRY performance and the WET performance may decrease.

The snow traction index (STI) can be calculated by the following equation. STI = −6.8 + 2202ρg + 672ρs + 7.6
Dg where ρg = (the total groove length projected in the lateral direction) / (contact width × perimeter) (1 / mm), ρs
= (Total sipe length projected in the lateral direction) / (contact width × perimeter) (1 / mm), and Dg = average groove depth (mm).

The tread pattern is not particularly limited as long as the snow traction index (STI) is 150 or more, and can be appropriately selected according to the purpose. For example, on the surface of the tread portion,
A plurality of blocks may be formed by a plurality of circumferential grooves and a plurality of transverse grooves intersecting with the circumferential grooves, and the blocks include, in order to improve braking performance and traction performance on ice, A sipe extending along the width direction of the tire may be formed. Further, the tread portion, an upper layer cap portion directly grounded to the road surface,
It may have a cap-base structure constituted by a lower-layer base portion disposed adjacent to the inside of the tire of the cap portion.

[0011] The tread portion contains at least 0.5 to 10 parts by weight of short fibers with respect to 100 parts by weight of the rubber component, and contains other components appropriately selected according to the purpose.

--Rubber Component-- The rubber component is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include natural rubber and synthetic rubber. These may be used alone or in combination of two or more. The synthetic rubber is not particularly limited and can be appropriately selected from known ones according to the purpose. For example, a diene-based synthetic rubber is preferably used.

As the diene-based synthetic rubber, for example,
Styrene-butadiene copolymer (SBR), polyisoprene (IR), polybutadiene (BR) and the like can be mentioned. Among these diene-based synthetic rubbers, the glass transition temperature is low, and in terms of the SNOW performance and the ICE performance,
Cis-1,4-polybutadiene is preferred, and those having a cis content of 90% or more are particularly preferred. In addition, as for the glass transition temperature of the said rubber component, -60 degreeC or less is preferable. When the glass transition temperature exceeds −60 ° C., the tread portion is advantageous in that it maintains sufficient rubber elasticity even in a low temperature range, and exhibits good SNOW performance and ICE performance.

In the present invention, the rubber component is a natural rubber (NR), a styrene-butadiene copolymer (SB)
R) and polybutadiene (BR).
More preferably, it contains 60 to 90% by weight of butadiene copolymer (SBR) and 10 to 40% by weight of polybutadiene (BR).

--Short Fibers-- The average length (L) of the short fibers is preferably 10 mm or less, more preferably 0.5 to 10 mm, and 1 to 5 m.
m is particularly preferred. If the average length (L) exceeds 10 mm, poor dispersion at the time of rubber kneading and orientation disorder at the time of extrusion occur, the rigidity of the tread portion does not sufficiently improve, and the WET performance and the DRY performance In some cases, the effect of improving shortness is not sufficient. On the other hand, if it is 10 mm or less, such a phenomenon does not occur. And the effect of blending the short fibers tends not to be sufficiently obtained. The average length (L) of the short fibers can be measured by, for example, an optical microscope or the like.

The short fibers have an average diameter (D) of 0.1.
01 to 0.1 mm is preferable, and 0.01 to 0.05 mm
Is more preferred. When the average diameter (D) is less than 0.01 mm, many yarn breaks occur during the production of the short fibers, and the effect of blending the short fibers tends not to be sufficiently obtained. In some cases, the rigidity of the portion is not sufficiently improved, and the effect of improving the WET performance and the DRY performance may not be sufficient. If it exceeds 0.1 mm, the average diameter (diameter) of the short fibers becomes too large, and Poor dispersion during kneading or orientation disturbance during extrusion may occur,
The rigidity of the tread portion may not be sufficiently improved, and the effect of improving the WET performance and the DRY performance may not be sufficient. On the other hand, when the average diameter (D) is 0.01 to 0.1 mm, such a situation does not occur, and the rigidity of the tread portion can be sufficiently improved, and the SNOW performance, the ICE performance, and the WET performance can be improved. This is preferable in that the performance and the DRY performance can be exhibited in a highly balanced manner. The average diameter (D) of the short fibers can be measured using an optical microscope.

The short fibers include organic short fibers and inorganic short fibers. The inorganic short fiber is formed of an inorganic material, and examples thereof include carbon fiber, glass fiber, and steel fiber.

The organic short fiber is formed of a synthetic resin, and examples thereof include a crystalline high-molecular short fiber and an amorphous high-molecular short fiber.

Examples of the crystalline polymer short fibers include polyolefin short fibers such as polyethylene, polypropylene and polybutylene, nylon 6, nylon 66, nylon 6-nylon 66 copolymer, nylon 610, nylon 612 and nylon 46. , Nylon 11, nylon 12, nylon MXD6, aliphatic polyamide staple fiber such as polycondensate of aliphatic diamine and aromatic dicarboxylic acid, aromatic polyamide staple fiber such as Kevlar / aramid staple fiber,
Polyester staple fiber such as polyethylene terephthalate, polybutylene terephthalate, polybutylene succinate, polyethylene succinate, aromatic polyester,
Polyvinyl alcohol staple such as vinylon, syndiotactic-1,2-polybutadiene (SPB) staple, polyether staple, polyurea staple, polyurethane staple, polyethylene sulfide staple, polyvinyl chloride staple, and the like. Can be These may be used alone or in combination of two or more.

Examples of the non-crystalline high-molecular short fibers include polymethyl methacrylate short fibers, acrylonitrile butadiene styrene copolymer short fibers, polystyrene short fibers, and polyacrylonitrile short fibers. These may be used alone or in combination of two or more.

When the short fibers are the organic short fibers,
The molecular weight of the resin constituting the organic short fiber varies depending on the chemical composition of the resin, the state of branching of the molecular chains, and the like, and cannot be specified unconditionally. However, the viscosity at the maximum vulcanization temperature of the rubber component (fluid viscosity) It is preferable to select within a range where the viscosity (melt viscosity) of the resin does not become higher than that of the above).

Among the short fibers, organic short fibers that are heat-fusible or heat-softening are preferable, and the crystalline high-molecular short fibers are more preferable. Short polyethylene fibers, short polypropylene fibers, short aromatic polyamide fibers, At least one selected from aliphatic polyamide short fibers, polyester short fibers and polyvinyl alcohol short fibers is particularly preferred.

When the short fibers are heat fusible or heat softening, the melting point or softening point of the short fibers is preferably at least 10 ° C. lower than the maximum vulcanization temperature of the rubber component, and 20 ° C. More preferably, it is lower than 1
00-190 ° C is preferable, and 135-180 ° C is more preferable. From the viewpoint that the melting point is low, the polyethylene short fiber (135 ° C.) and the polypropylene short fiber (1
70 ° C.) is preferred.

The melting point or thermal softening point can be measured by using a melting point measuring device known per se. For example, the melting peak temperature measured by using a DSC measuring device is calculated from the melting point or thermal softening point. It can be.

[0025] The content of the short fibers in the tread portion is preferably 0.5 to 100 parts by weight of the rubber component.
It is necessary to be 10 to 10 parts by weight, preferably 1 to 8 parts by weight, more preferably 1.5 to 5.0 parts by weight. When the content of the short fibers is less than 0.5 parts by weight, the effect of blending the short fibers cannot be sufficiently obtained, the rigidity of the tread portion does not sufficiently improve, and the WET performance and the DRY The effect of improving the performance may not be obtained, and if it exceeds 10 parts by weight, the dispersibility at the time of kneading the rubber is inferior and the extrusion becomes difficult.

As the short fibers, those which are appropriately manufactured may be used, or commercially available products may be used. In the former case, the method for producing the short fibers is not particularly limited,
Depending on the purpose, it can be appropriately selected from known spinning methods, but when the short fibers are the organic short fibers, for example, a solution spinning method, a gel spinning method, a melt spinning method and the like are preferably used. No.

In the case of these spinning methods, at a predetermined heating temperature, a filament material obtained by extruding a spinning solution obtained by dissolving or dispersing the resin constituting the organic short fibers in an organic solvent from a spinning nozzle is rapidly cooled. The organic short fibers can be produced by spinning after removing the solvent.

The heating temperature (the temperature in the step of producing the organic short fiber) is preferably from 40 to 180 ° C.
40-150 degreeC is more preferable, and 40-130 degreeC is especially preferable. In addition, when the said organic short fiber is a polyethylene short fiber, 100-150 degreeC is preferable as said heating temperature.

The organic solvent can be appropriately selected according to the type of the resin, and includes, for example, decalin, acetone, benzene and the like. These organic solvents may be used alone or in combination of two or more.

The spinning dope is obtained by dissolving or dispersing the resin in the organic solvent. The dissolution and the dispersion can be performed using a known device or device, for example, a stirring device or the like. The time for performing the dissolution or dispersion, specifically, the time for performing stirring and the like, the type and amount of each component in the spinning dope, stirring speed, fin shape,
It varies depending on the inner wall material of the stirrer and the like and cannot be specified unconditionally, but is preferably about 5 to 60 minutes.

In the case of the melt spinning method or the gel spinning method, the spinning solution is extruded from the spinning nozzle into a liquid such as water (wet) or into the air (dry). The fibrous body that has been spun (formed) into the form of a fibrous body and spun is wound using, for example, a winder or the like.

The spinning nozzle is not particularly limited and may be appropriately selected depending on the intended purpose. The diameter of the outlet of the spinning nozzle is, for example, 0.05 to 1
mm is preferable, and 0.1 to 0.8 mm is more preferable.
The spinning nozzle is usually mounted at a spinning solution outlet in a spinning device or an extrusion device. The spinning device is not particularly limited, and can be appropriately selected from known spinning devices and extrusion devices such as a screw type extrusion device.

The filament obtained as above is quenched and solidified. The quenching rate is not particularly limited and can be appropriately selected depending on the purpose. For example,
When quenched in water, the filament is instantaneously cooled. The filament is desolvated during or after the cooling. The method for removing the solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a method using a methanol bath and a method using a hot blast tube.

It is preferable to stretch the filament before or after the desolvation, but it is preferable to stretch the filament before the desolvation, since the stretching ratio of the filament can be increased. The stretching temperature is 40 to 180.
The heating is preferably performed at a temperature of 40 ° C. The stretching apparatus is not particularly limited, and can be appropriately selected from known stretching apparatuses.

Since the organic short fibers thus obtained are usually long fibers, they can be shortened by cutting them into a desired length using a cutting tool appropriately selected.

-Other components-Examples of the other components include reinforcing fillers such as carbon black and silica, vulcanizing agents such as sulfur, vulcanization accelerators such as dibenzothiazyl disulfide, and zinc white. Vulcanization aids, silane coupling agents, N-cyclohexyl-
Anti-aging agents such as 2-benzothiazyl-sulfenamide, N-oxydiethylene-benzothiazyl-sulfenamide, zinc oxide, stearic acid, an ozone deterioration preventing agent,
Lubricants such as colorants, antistatic agents, dispersants, waxes, antioxidants, softeners, additives such as inorganic fillers such as alumina, aluminum hydroxide, talc, clay, etc., as well as various types commonly used in the rubber industry And compounding agents. The other components can be appropriately selected according to the purpose within a range that does not impair the effects of the present invention, and commercially available products can be suitably used.

--Preparation of rubber composition of tread portion-- The rubber composition of the tread portion is prepared by mixing the above components, kneading, heating, extruding, etc. under appropriately selected conditions and methods. Is obtained by

The kneading is performed by:
There are no particular restrictions on the conditions such as the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, and the kneading apparatus, and they can be appropriately selected according to the purpose. As the kneading device, a commercially available product can be suitably used.

The heating or extrusion is not particularly limited with respect to various conditions such as heating or extrusion time, heating or extrusion equipment, and can be appropriately selected according to the purpose. As the heating or extruding device, a commercially available product can be suitably used.

In the tread portion, it is preferable that the short fibers are easily and sufficiently oriented in the tire circumferential direction by the extrusion or the like. In this case, it is advantageous in that drainage in the running direction of the pneumatic tire can be enhanced, and the ICE performance and the SNOW performance can be improved. When the short fibers are oriented in the tire circumferential direction in the tread portion, a plasticizer such as an aroma-based oil, a naphthene-based oil, a paraffin-based oil, or an ester-based oil is appropriately added to the rubber composition of the tread portion. be able to.

As a method of aligning the orientation of the short fibers, for example, a method of extruding the rubber component containing the short fibers from a die of an extruder in which a cross-sectional area of a flow path decreases toward an outlet is used. No.

-Other Configurations- Other configurations other than the tread portion in the pneumatic tire of the present invention are not particularly limited, and can be appropriately selected from known configurations according to the purpose. , A carcass that is connected to the pair of beads in a toroidal shape, a belt that buckles a crown portion of the carcass, and the like. The pneumatic tire may have a radial structure or a bias structure.

The method for manufacturing the pneumatic tire is as follows.
Although not particularly limited, for example, it can be manufactured as follows. That is, first, the rubber composition of the tread portion is prepared. In this rubber composition, the short fibers are oriented in one direction. The rubber composition is stuck on an unvulcanized base which has been stuck on the crown of the green tire case in advance. At this time, the orientation direction of the short fibers is made to coincide with the circumferential direction of the tire. Then, when vulcanization molding is performed in a predetermined mold under a predetermined temperature and a predetermined pressure, a pneumatic tire is manufactured.

The pneumatic tire of the present invention has at least a tread portion on which a tread pattern having a snow traction index (STI) of 150 or more is formed. For this reason, the tread portion is rich in an edge component, so that the SNOW performance and the IC
Excellent in E performance. Further, the tread portion has a rubber component 10
It contains at least 0.5 to 10 parts by weight of short fibers with respect to 0 parts by weight. For this reason, it is possible to improve the block rigidity in the tread portion where the rigidity tends to decrease due to the rich edge component, and in the tread portion, the WET performance and the DRY performance are improved.
As a result, in the case of the pneumatic tire of the present invention, a dry road surface,
Performance is stably exhibited regardless of whether it is a rainy road surface, an ice road surface, a snow road surface, etc., and the ICE performance, the SNOW performance,
The WET performance and the DRY performance can be highly and simultaneously exhibited.

The pneumatic tire of the present invention can be suitably applied not only to so-called passenger cars but also to various vehicles such as trucks and buses.

[0046]

EXAMPLES Hereinafter, examples of the pneumatic tire of the present invention will be described, but the present invention is not limited to these examples.

Examples 1 to 4 and Comparative Examples 1 to 3 Each rubber composition for a tread portion having the composition shown in Table 1 was produced. A tread portion of a pneumatic tire was formed using each of the obtained rubber compositions, and vulcanization conditions were set at 170 ° C. for 12 minutes to produce pneumatic tires for each test. This tire is a radial tire for a passenger car, and its tire size is 195 /.
65R15, the structure of which includes a pair of bead portions, a carcass connected to the pair of bead portions in a toroidal shape, and a belt for clapping a crown portion of the carcass,
This is a radial structure in which tread portions are sequentially arranged.

The obtained pneumatic tires for testing were evaluated for the SNOW performance, the ICE performance, the WET performance, and the DRY performance. The results are shown in Table 2.

<SNOW Performance> The pneumatic tire for each test was mounted on a domestic 1600CC class passenger car, and the passenger car was run on a general asphalt road for 200 km, and then on a flat road on snow at a speed of 40 km / h. At this point, the brake was depressed to lock the tire, and the distance until the tire stopped was measured. The result was expressed as an index with the reciprocal of the distance taken as 100 for the tire of Comparative Example 1. The flat road on snow is 0
The acceleration time when traveling for 走 行 100 m was measured. The results were indexed with the tire of Comparative Example 1 taken as 100. The average value of these results was taken as SNOW performance. The larger the value, the better the SNOW performance.

<ICE Performance> A pneumatic tire for each test was mounted on a domestically produced 1600CC class passenger car, and the passenger car was driven on a general asphalt road for 200 km, and then on a flat road on ice, at a speed of 20 km / h. At this point, the brake was depressed to lock the tire, and the distance to the stop was measured. The result was expressed as an index with the reciprocal of the distance taken as 100 for the tire of Comparative Example 1. The larger the value, the better the ICE performance.

<WET Performance> A pneumatic tire for each test was mounted on a domestically produced 1600CC class passenger car, and the passenger car was run 200 km on a general asphalt road, and then was run on a rainy flat road. Drivability, braking, straight running stability and controllability were comprehensively evaluated. The results were indexed with the tire of Comparative Example 1 taken as 100. The larger the numerical value, the better the WET performance.

<DRY Performance> The pneumatic tire for each test was mounted on a domestically produced 1600CC class passenger car, and the passenger car was run on a general asphalt road for 200 km, and then on a dry flat road. Drivability, braking, straight running stability and controllability were comprehensively evaluated. The results were indexed with the tire of Comparative Example 1 taken as 100. The larger the numerical value, the better the WET performance.

[0053]

[Table 1]

In Table 1, numerical values represent "parts by weight".
"SBR1712 (JSR)" means styrene-butadiene rubber (manufactured by JSR Corporation, 1712). “BR” means cis-1,4-polybutadiene (BR01, manufactured by JSR Corporation). "C / B N220" means carbon black (manufactured by Asahi Carbon Co., Ltd., carbon N220), and "silica" means Nipsil-VN3 manufactured by Nippon Silica Industry Co., Ltd. "Coupling agent" means a silane coupling agent (Si69, manufactured by Degussa). "Old defense 6
"C" means an antioxidant (Nocrack 6C, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.). “Accelerator DPG” means a vulcanization accelerator (Noxeller D, manufactured by Ouchi Shinko Chemical Co., Ltd.). “Accelerator DM” means a vulcanization accelerator (Noxeller DM manufactured by Ouchi Shinko Chemical Co., Ltd.). "Sul
"fur" means powdered sulfur. "Polyethylene fiber" has an average diameter of 0.02 to 0.03 mm, and "polypropylene fiber" has an average diameter of 0.02 to 0.03 m.
m.

[0055]

[Table 2]

[0056]

According to the present invention, a dry road surface, a rainy road surface,
Demonstrates stable performance irrespective of icy or snowy road surfaces, while maintaining excellent ICE performance and SNOW performance.
A pneumatic tire with improved ET performance and DRY performance can be provided.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4J002 AC011 AC021 AC031 AC061 AC081 BB032 BB122 BB172 BC032 BC062 BD052 BE022 BE062 BG062 BG102 BL002 CC162 CF032 CF042 CF062 CF072 CH002 CL012 CL032 CL062 CN012 DA016 DA066 DL006 FA

Claims (7)

[Claims] 1. A tire having at least a tread portion having a tread pattern having a snow traction index (STI) of 150 or more, wherein said tread portion has a short fiber content of 100 parts by weight of a rubber component. 5-1
A pneumatic tire comprising at least 0 parts by weight. 2. The short fiber has an average diameter of 0.01 to 0.1 mm.
The pneumatic tire according to claim 1, wherein 3. The pneumatic tire according to claim 1, wherein the short fibers have an average length of 0.5 to 10 mm. 4. The pneumatic tire according to claim 1, wherein the short fibers are heat-meltable or heat-softening. 5. The short fiber has a melting point or softening point of 100 to 19.
The pneumatic tire according to claim 4, which is at 0 ° C. 6. The staple fiber is at least one selected from polyethylene staple fiber, polypropylene staple fiber, aliphatic polyamide staple fiber, aromatic polyamide staple fiber, polyester staple fiber and polyvinyl alcohol staple fiber. 5. The pneumatic tire according to any one of 5. 7. The pneumatic tire according to claim 1, wherein the short fibers are oriented in the tire circumferential direction.