JPH09136999A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber compsn. suitable as a tire tread rubber capable of improving a wet performance on an asphalt road by using a specific rubber reinforcement in a foamed rubber blended with microspike particles. SOLUTION: This rubber compsn. is a closed-cell compsn. comprising 100 pts.wt. rubber component blended with 3-30 pts.wt. particles having a hardness of at least 75 deg. according to JIS-K6301-C and an average particle size of 5 to 250μm, having aluminum-bonded hydroxyl groups and/or silicon-bonded hydroxyl groups on the surfaces thereof, and contg. at least 20wt.% of at least one selected fro between Al(OH)3 and SiO2 , a coupling agent of the formula I [wherein Y is alkoxy or the like, n is 1 to 6, and A is -Sm Cn H2n Si-Y3 , -Sm Z (wherein Z is of the formula II, and m is 1 to 6), or the like], the amt. α (pts.wt.) of which satisfies the following formula: 0.09+0.05β<α<15+0.1β (wherein βis the amt. (pts.wt.) of silica), and 10-100 pts.wt. reinforcement comprising carbon black having properties such as a specific surface area of 100 to 180m<2> /g according to the nitrogen absorption method and silica having a specific surface area of 100 to 300m<2> /g according to the BET method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition, which can be suitably used as a tire tread rubber that can be mounted on vehicles including small cars and large cars such as passenger cars, trucks and buses used on ice and snow roads. Regarding things.

[0002]

2. Description of the Related Art When a vehicle travels on a cold road surface in winter, especially when the water or snow on the road surface freezes to form an ice surface, the tread rubber of a tire mounted on the car and the ice surface The frictional force is much lower than the frictional force on a dry and normal road surface which is not ice. For this reason, in order to safely drive on a road surface having an ice surface, a spike tire may be attached to the vehicle, or a tire chain may be attached to the outer circumference of the tire so that the tread rubber between the tire and the ice surface The frictional force is maintained so that it does not become low.

However, when a tire with a tire chain attached or a spike tire is attached to a vehicle, the spike of the spiked tire or the tire chain damages the road surface when the vehicle runs on a curve, suddenly starts or stops suddenly. ,
There is a problem that a part of the damaged road surface is cut out to become powder, and when the road surface is dried, the powder is blown up by the wind to scatter dust. In addition, when a vehicle equipped with the spiked tire or the tire with a tire chain travels on a road surface, the spike of the spiked tire or the tire chain hits the road surface to generate noise.

On the other hand, in recent years, a technique has been adopted in which the tread rubber itself is devised to improve the frictional force. As a first method, there is a method in which a tread rubber is foamed by an appropriate method to generate closed cells (JP-A-63-89547). That is, since the ground contact surface of the tread rubber thus obtained is covered with a large number of bubbles, the water removal effect on the ice surface and the edge effect of scraping the ice due to the microscopic movement of the pores cause the effect on the ice. Express high friction. This technique has been incorporated into actual tire treads and is commercially available as studless tires. In addition, a method of mixing various foreign substances (natural substances such as sand and rice husk) into the tread rubber and causing the foreign substances to fall off during tire running to generate pores has been studied. This method is the same as foaming as a mechanism for increasing friction on ice.

As a second method, various high-hardness materials are mixed in the tread rubber, and an attempt is made to achieve high friction on ice of the tread rubber by utilizing the scratching effect on the ice surface in the high-hardness material. There is (Japanese Examined Sho 46-3173)
No. 2, JP-A-51-147803, JP-B-56-52
No. 057). This method is a method for increasing the friction of the tread rubber on ice by a mechanism different from the first method. In fact, in many cases, the more these hard materials are mixed, the more the tread rubber tends to have higher friction on ice.

[0006]

Among the above-mentioned prior arts, the convex portions of the surface irregularities after the foamed or mixed foreign matter of the tread rubber is released, scratch the ice, and the concave portions absorb and discharge the water on the ice surface. The disadvantage of the first method is that the hardness of the rubber is relatively lower than that of the ice surface, and the scratching effect at low temperatures (usually -3 ° C or less) cannot be expected.

On the other hand, the disadvantage of the second method in which the high hardness material having a high scratching effect is mixed in the matrix rubber of the tread is that the effect on the ice performance improvement at around 0 ° C. where the water content is high is small, and the high hardness material is used as the rubber. Since it is present as a foreign substance having no affinity, the abrasion resistance and the fracture property are significantly deteriorated. In order to improve the affinity, Japanese Patent Laid-Open No. 4-365606 discloses a treatment method such as an adhesive, plating, plasma treatment, sputtering treatment, coating with a rubber material, resin coating and the like, which has an improving effect but is still insufficient. But that is not the case.

Further, if micro spikes are mixed into the foamed rubber, the performance on ice is improved, but the wet performance on the asphalt road surface is deteriorated. By setting the hardness of the micro spike particles to a material harder than ice, the performance on ice is improved by the effect of digging up the ice surface by micro spikes,
In consideration of environmental issues such as asphalt dust, the hardness of asphalt is set so that it does not dig up, so it is not possible to dig up asphalt, and the wet performance on asphalt deteriorates. .

On the other hand, as a method for improving wet performance on a general asphalt road surface, it is known to add silica. The addition of silica improves the microscopic ground contact property on the asphalt road surface, so that an increase in the effective ground contact area required for friction brings about an effect. However, since the surface of the icy road is extremely smooth, the effect of improving the performance on ice is extremely small even if the microscopic grounding property is improved.

The object of the present invention is to provide a wide temperature range,
Providing a rubber composition that exhibits stable on-ice performance, suppresses deterioration of wear resistance and durability, and also improves wet performance on asphalt, thereby exhibiting a stable friction coefficient under a wide range of road surface conditions It is to be.

[0011]

[Means for Solving the Problems]
As a result, in the foamed rubber containing micro spike particles,
Use silica together with carbon black as a rubber reinforcing agent.
By improving the wet performance on the asphalt road surface
It is confirmed that it can be done, and as a new effect, it is on ice
Completed the present invention by discovering that Noh can be greatly improved.
Reached. The configuration of the present invention is as follows. Of the present invention
The rubber composition is JIS-based on 100 parts by weight of the rubber component.
K6301-C type hardness is 75 degrees or more, average particle size is 5
250 μm, with aluminum-bonded hydroxyl groups and
/ Or has a silicon-bonded hydroxyl group, Al (OH)_Threeand
SiO _TwoParticles of at least one selected from the group consisting of
3 to 30 parts by weight of particles containing 20% by weight or more
General formula Y_Three-Si-CnH_TwonA (In the formula, Y is an alkyl group having 1 to 4 carbon atoms, alkoxyl
In a group or chlorine atom, three Ys may be the same or different,
n is an integer of 1 to 6, A is -SmCnH_TwonSi-
Y_ThreeGroup selected from the group consisting of a group, an X group and a -SmZ group
Where X is nitroso group, mercapto group, amino
Group, epoxy group, vinyl group, chlorine atom or imide group, Z
Is

Embedded image M and n each represent an integer of 1 to 6;
Is as described above. ), At least one of the coupling agents represented by the formula (α) is added to satisfy the relationship of the following formula: 0.09 + 0.05β <α <15 + 0.1β (where β is the amount of silica to be described later) The unit is α
And β are parts by weight. ) A nitrogen adsorption specific surface area (N ₂ SA) of 100 as a reinforcing agent
~ 180 m ² / g, dibutyl terephthalate oil absorption (D
Carbon black having a BP of 120 to 180 ml / 100 g and a BET specific surface area of 100 to 300 m ^2.
It is characterized in that 10 to 100 parts by weight of silica of 10 g / g is blended, and silica accounts for 20% by weight or more of these reinforcing agents and has closed cells.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION When the foaming means is applied to a tread rubber, for example, it is possible to control the foaming ratio from the surface layer of the tread to the innermost layer, and change the performance on ice until complete wear. Can be reduced. Either a foaming method or a high pressure gas mixing method may be used.

When used as a tread rubber, the foaming rate is 5
It is preferably about 35%. This is because when the rubber composition according to the present invention is used as a tread rubber for a pneumatic tire, the microscopic drainage effect due to the pores is increased in a state in which a large amount of water is melted on the ice surface near 0 ° C., which is excellent. This is because such closed cells are desirable in order to exert the ice and snow performance.

Here, the foaming rate V _s of foaming is represented by the following formula V ₁ = {(ρ ₀ −ρ _g ) / (ρ ₁ −ρ _g ) −1} × 100 (%) ... (1) , Ρ ₁ is the density of foamed rubber (g / cm ³ ), ρ
₀ Density of solid phase part of foamed rubber (g / cm ³ ), ρ _g is density of gas part in bubbles of foamed rubber (g / cm ³ ). The foamed rubber is composed of a solid phase portion and a cavity (closed cell) formed by the solid phase portion, that is, a gas portion in the bubble. The density ρ _{g of the} gas part is extremely small, close to zero,
Moreover, since it is extremely small with respect to the density ρ _{1 of the} solid phase portion, the formula (1) is almost equivalent to the following formula V _s = {(ρ ₀ / ρ ₁ ) −1} × 100 (%) (2) Become.

The particles mixed in the foamed rubber are JI
The hardness measured by the SK6301-C type hardness meter is 75.
It is specified that the hardness is high or higher, but if it is less than 75 degrees, a sufficient scratching effect cannot be obtained. Preferably 90 or more, most preferably 95 or more particles.
The present invention is intended to improve scratch resistance and the like by obtaining a scratching effect at a low temperature in which the hardness of ice is higher than the hardness of rubber by mixing particles of high hardness into the foamed rubber.

The average particle size of the high hardness particles is 5 to 5.
It is specified to be 250 μm, but this is because if it is less than 5 μm, a sufficient scratching effect cannot be obtained.
This is because if it exceeds 0 μm, there are problems in durability performance such as abrasion resistance and crack resistance.

The average particle diameter is measured by laser diffraction measurement (light scattering method) using Microtrac. It was measured by a conventional method using a NIKKISO Microtrac MK11 particle size analyzer manufactured by Nikkiki Co., Ltd.

Furthermore, Al (OH) ₃ and / or
Alternatively, it is preferable to contain SiO ₂ in an amount of 20% by weight or more based on the weight of the particles, but if it is less than 20% by weight, the adhesiveness cannot be ensured because the reaction points of the particles with the coupling agent are small, and therefore the ability to scratch ice is greatly enhanced. It is not preferable because it decreases.

As the binder that constitutes the particles, PM
MA (polymethylmethacrylate), PVA (polyvinyl alcohol), polyvinyl acetate, polyacrylic acid, styrene-butadiene resin, polyester, epoxy resin, acrylic resin, phenol resin, melamine resin, P
It can be selected from resins conventionally used as binders such as P resin and syn-1,2-polybutadiene resin.

Next, examples of the silane coupling agent compounded in the rubber composition in the present invention are as follows. Bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3- Mecaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 3
-Nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane,
2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3 -Trimethoxysilylpropyl methacrylate monosulfide, bis (3-triethoxysilylpropyl) tetrasulfide, 3-trimethoxysilylpropylbenzene Such as thiazole tetrasulfide are preferable. Further, three Y's may not be the same, and examples thereof include bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, 3-nitropropyldimethoxymethylsilane, and 3-chloro. Examples thereof include propyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, and dimethoxymethylsilylpropylbenzothiazoletetrasulfide.

The carbon black used in the present invention is N ₂
SA is 100 to 180 m ² / g, and DBP is 120 to
It is specified to be in the range of 180 ml / 100 g. N
₂ SA 180 m ² / g and DBP 180 ml / 10
When it exceeds 0 g, workability during rubber kneading and extrusion processability are deteriorated, which is not preferable.

If the N ₂ SA is less than 100 m ² / g and the DBP is less than 120 ml / 100 g, the abrasion resistance is lowered and the advantages of durability and performance on ice are lost, which is not preferable.

The carbon black N ₂ SA is AST
M D3037-89, DBP is ASTM D2414
-90, the BET specific surface area of silica is AMT
According to MD3037.

It is specified that the particles have an average particle size of 5 to 250 μm, and the compounding amount is 3 to 30 parts by weight with respect to 100 parts by weight of the rubber component, but when the amount is less than 5 μm or less than 3 parts by weight, The performance improvement effect on ice was not obtained, and
If it exceeds 0 μm or exceeds 30 parts by weight, durability such as abrasion resistance and groove bottom cracking is deteriorated.

When the total amount of Al (OH) ₃ and / or SiO _{2 in} the particles is less than 20% by weight, there are few reaction points with the coupling agent on the particles and it becomes difficult to secure the adhesiveness. Not preferable.

When used in a tread rubber, the foaming rate is preferably 5 to 35%, but if it is less than 5%, the effect of foaming (performance on ice) cannot be obtained, and if it exceeds 35%, abrasion resistance, This is because the durability is reduced.

Further, the BET specific surface area of silica is 100.
When it is less than m ² / g, the reinforcing property is low and the wear resistance and durability are lowered. When it is more than 300 m ² / g, the workability is remarkably lowered and the dispersibility is deteriorated.

The silane coupling agent according to the present invention is
5 to 10% of the silica compounding amount is required for reinforcing silica, and 3 to 50% of the particle compounding amount is required for bonding the particles and the matrix rubber. When the amount is less than the lower limit of the amount specified by the present invention, the adhesion between the particles and the matrix becomes insufficient, and the desired scratching effect cannot be obtained due to desorption during traveling, and when the amount is large, excessive coupling occurs. Since a large amount of sulfur atoms are released from the A group of the agent, the rubber elastic modulus is greatly increased, the performance on ice is lowered, and the cost is also greatly increased, which is not economical.

As the rubber component, those commonly used as tread rubbers can be used. For example, natural rubber, isoprene rubber, styrene-butadiene copolymer rubber, butadiene rubber, butyl rubber and the like can be used alone or in a blend. can do. Further, a compounded drug or the like usually used in the rubber industry can be appropriately used.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
Based on the formulation shown in Table 1, each Example and each Comparative Example
A rubber composition was prepared and each performance described in the table was measured.
In addition, it depends on a normal vulcanization condition.

The braking performance on ice is tire size 205/6.
A tire of 0 R15 was manufactured, and ice temperatures of -2 ° C and -8 ° C
In the case of, after traveling 200 km straight, speed 20 km / h
The vehicle was braked, and Comparative Example 1 was used as a control and displayed as an index. The larger the value, the better.

The wear resistance performance was evaluated by running on a general road, and the comparative example 1 was used as a control and expressed as an index. The larger the value, the better. The crack appearance test was observed on the tire tread rubber circumference after 7,000 km of running on general roads. ⊚ indicates that no crack occurred, and ∘ indicates a crack length of 0.5.
The crack length was within 1 mm, the crack length was within 1 mm, and the crack length was within 1 mm.

Wet performance (driving performance on wet road surface) is
According to the method specified in the United States UTQGS (tire quality grade standard), the tire was mounted on a test trailer, run on a wet asphalt dense grain road surface, and the friction resistance when the rotation of the tire was locked was measured and compared. Example 1 was set to 100 and indexed. The higher the value, the better.

[0034]

[Table 1] * 1: Dibenzothiazyl disulfide (vulcanization accelerator) * 2: N-cyclohexyl-2-benzothiazyl-sulfenamide (vulcanization accelerator) * 3: Dinitrosopentamethylenetetramine: urea =
1: 1 (weight ratio)

[0035]

[Table 2] Particle A: Showa Denko Co., Ltd. Heidilite H-10A Particles B, D, E: Prototype Particle C: Artificial marble crushed product Particle F: Showa Denko Co., Ltd. Alumina A-12C Particle size is all by sieve classification , 40 to 60 μm.

[0036]

[Table 3]

The method for preparing carbon black (a) is as follows. That is, carbon black is generally a cylindrical-shaped introduction chamber for a combustible fluid for generating high-temperature combustion gas and an oxygen-containing gas fluid, and oxygen that is coaxially connected to the downstream side of this introduction chamber and has a smaller diameter than that. Cylinder for containing gas, a plurality of radial straightening plates provided on the outer periphery of the cylinder, a combustion gas converging chamber having an upstream end connected to the introducing chamber and gently converging toward the downstream side, downstream of the converging chamber And a cylindrical reaction having a diameter larger than the diameter of the downstream end of the raw oil introduction chamber having a plurality of raw oil spray devices and having at least one plane. Chamber, connected to the reaction chamber and inserted-
Carbon entirely covered with a refractory material consisting of a reaction continuation and rapid cooling chamber in which a plurality of cooling water injection spray devices that can be drawn out are installed, and a flue part connected to the rear end of the reaction continuation and rapid cooling chamber It is manufactured using a black manufacturing device.

First, the surface area is adjusted by the ratio of the raw fuel introduction amount and the air introduction amount, and the surface area is increased by increasing the air introduction amount. The DBP oil absorption is adjusted mainly by the feed position of the feed oil, that is, the use position of a plurality of feed oil introduction planes, and the feed oil is introduced at the upstream side of the convergence chamber, in other words, at a position close to the feed chamber. By doing so, the DBP can be increased. Carbon black (a) was produced by combining the above production control conditions with the respective requirements of the present invention.

The coupling agents a and b in the table are as follows.

Embedded image

The measurement results and the like shown in Table 1 are considered as follows. Comparative Example 1 serves as a control for the entire foamed rubber, and Comparative Example 2 is obtained by adding particles to Comparative Example 1. The performance on ice is improved, but the wet performance is poor, and Comparative Example 3 is compared to Comparative Example 2. Although silica is added, wet performance is improved, but wear resistance is reduced and the merit of improving performance on ice is diminished.

Comparative Example 4 is a combination of carbon black (a) and silica, which has no merit in on-ice performance, but shows improvement in wet performance as compared with Comparative Example 1. Example 1 is an expanded + particle system modified with carbon black (a) and silica. Compared to Comparative Example 3, the effect of carbon black (a) appears to improve wear resistance, and Comparative Example 4 In comparison, the braking performance on ice is significantly improved, and the improvement range is remarkably larger than the on-ice improvement effect of Comparative Example 2 with respect to Comparative Example 1. In Example 2, Example 3 and Example 4, the particles of Al (O
H) Since the amount of ₃ or SiO ₂ is 20% by weight or more, the adhesion between the particles and the rubber matrix at the particle interface is good,
Greatly improves the performance on ice.

In Comparative Examples 5 and 6, the braking performance on ice is not improved as compared with Examples 2, 3 and 4 due to insufficient adhesion of particles. Example 5 is an example in which the coupling agent type was changed from a to b. Comparative Example 7 is an example in which the particle size is too small and the braking performance on ice is not improved. In Example 6 and Example 7, the particle diameter is within the specified range, and each performance is good. Comparative Example 8 is an example in which the wear resistance and crack resistance (durability) are reduced when the particle size is too large.

Comparative Example 9 is an example in which the amount of particles blended is too small and the braking performance on ice is not improved. In each of Example 8 and Example 9, the performance was good in each performance, because the amount of particles blended was not within the specified range. Comparative Example 10 is an example in which the amount of particles blended is too large and the wear resistance and crack resistance are poor. In Comparative Example 11, the silica content was 2 of the total amount of the reinforcing agent (42 + 8 = 50 parts by weight).
This is an example of less than 0% by weight, and Example 10 is an example of the case where the amount of silica compounded satisfies this regulation.

As described above, in each of the examples, in the carbon-reinforced foam rubber, the deterioration of the wet performance on the Alfart road surface due to the blending of particles is not compensated by using silica in combination, and the braking performance on ice is further improved. It shows that the improvement effect is obtained.

[0045]

EFFECTS OF THE INVENTION According to the present invention, stable ice performance is exhibited over a wide temperature range, abrasion resistance and durability are prevented from deteriorating, and wet performance on asphalt is also improved, so that a wide range of road surfaces can be obtained. An effect that a rubber composition that exhibits a stable friction coefficient under the conditions can be provided can be obtained.

Claims (1)

[Claims] 1. JIS-based on 100 parts by weight of a rubber component
K6301-C type hardness is 75 degrees or more, average particle size is 5
It is 250 μm, has 3 to 3 particles having an aluminum-bonded hydroxyl group and / or a silicon-bonded hydroxyl group on the surface, and containing 20% by weight or more of the particle weight of at least one selected from the group consisting of Al (OH) ₃ and SiO _2. 30 parts by weight are compounded and represented by the general formula Y ₃ —Si—CnH ₂ nA (wherein Y is an alkyl group having 1 to 4 carbon atoms, an alkoxyl group or a chlorine atom, and three Ys may be the same or different,
n represents an integer of 1 to 6, A is -SmCnH ₂ nSi-
A group selected from the group consisting of a Y ₃ group, an X group and a —SmZ group, wherein X is a nitroso group, a mercapto group, an amino group, an epoxy group, a vinyl group, a chlorine atom or an imide group, Z
Is M and n each represent an integer of 1 to 6;
Is as described above. ), At least one of the coupling agents is blended in an amount (α) that satisfies the relationship of the following formula: 0.09 + 0.05β <α <15 + 0.1β The unit is α
And β are parts by weight. ) A nitrogen adsorption specific surface area (N ₂ SA) of 100 as a reinforcing agent
~ 180 m ² / g, dibutyl terephthalate oil absorption (D
Carbon black having a BP of 120 to 180 ml / 100 g and a BET specific surface area of 100 to 300 m ^2.
10 to 100 parts by weight of silica of 10 g / g, and silica having 20% by weight or more of these reinforcing agents has closed cells.