JPH09124850A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition having a stable performance on ice within a wide range of temperature and excellent in abrasion resistance, useful as tread rubber by compounding specific particles, a silane coupling agent and carbon black with a rubber composition. SOLUTION: This composition comprising (A) 100 pts.wt. of rubber component, (B) 3-30 pts.wt. of particles having more than 75 deg.C hardness according to JIS-K 6301-C, average particle size of 5-250μm and having hydroxyl group bonded with aluminum and/or hydroxyl group bonded with silicone and (C) 3-50wt.%, based on component (B), of a silane coupling agent of the formula Y3 -Si-CnH2m A [Y is a 1-4C alkyl or Cl, etc.; (n) is 1-6; A is X1 -Sn Z (X is an amino, vinyl, etc.; Z is formula I or II, etc.; (n) is 1-6)] and as a rubber reinforcing material (D) 10-100 pts.wt. of carbon black having 100-180m<2> /mg of a specific surface area measured by N2 absorption method and 120-180ml/100g of dibutylterephthalate absorption. The component (B) preferably contains more than 20wt.% of Al(OH)3 and/or SiO2 .

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 tread rubber for a tire 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. It relates to a composition.

[0002]

2. Description of the Related Art When a vehicle travels on a cold road surface in winter, particularly on a road surface where ice or snow on the road is frozen 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 the road surface, the spike of the spiked tire or the tire chain may generate a noise that hits the road surface.

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 pores, the water-removing effect on the ice surface and the edge effect of shaving off the ice due to the microscopic movement of the pores cause the effect on the ice. Exhibits 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 material having no affinity, the wear resistance and the fracture characteristics are significantly deteriorated. In order to improve 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, and resin coating, which has an improving effect but is still not sufficient. But that is not the case.

Since the actual ice surface temperature changes variously from daytime to nighttime, a tire tread that exhibits more stable performance on ice in a wide temperature range and does not significantly deteriorate wear resistance and fracture characteristics is desired. ing.

Further, compared to when the tire is new, rigidity is increased at the end of running as the rubber hardens with time and the pattern groove depth is reduced, and the performance on ice is deteriorated. Is.

Therefore, an object of the present invention is to provide a rubber composition suitable for a tread rubber which exhibits stable on-ice characteristics over a wide temperature range and more stable on-ice performance under all conditions of use up to complete wear. It is to provide things.

[0011]

To achieve the above object, the present invention has the following constitution. The rubber composition of the present invention has a JIS-K 6301-C type hardness of 75 degrees or more and an average particle diameter of 5 to 250 μm with respect to 100 parts by weight of the rubber component.
Surface particles having aluminum bonded hydroxyl and / or silicon-bonded hydroxyl groups is blended 3 to 30 parts by weight, in the general formula _{Y 3 -Si-C n H 2n} A ( wherein, Y is an alkyl group having 1 to 4 carbon atoms, In the alkoxyl group or chlorine atom, three Ys may be the same or different,
n represents an integer of 1 to 6, A is _{-S m C n H 2n Si-} Y
₃ group, a group selected from the group consisting of X group and -S _m Z 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

Embedded imageA group, m and n each represent an integer of 1 to 6, and Y
Is as described above. ) Coupling agent
And at least one kind is used in an amount of 3 to 50% by weight based on the weight of the particles.
It is a rubber composition having closed cells formed by combining
Specific surface area by deposition (N _TwoSA) is 100-180m^Two/ G, di
Butyl terephthalate oil absorption (DBP) is 120-18
0-100ml of carbon black which is 0ml / 100g
It is characterized by being mixed with parts by weight.

The rubber composition of the present invention is characterized in that the particles contain at least one selected from the group consisting of Al (OH) ₃ and SiO _{2 in} an amount of 20% by weight or more based on the weight of the particles. And

[0013]

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 for 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 is expressed by the following equation V _s = {(ρ ₀ −ρ _g ) / (ρ ₁ −ρ _g ) −1} × 100 (%) --- (1). Where ρ ₁ is the density of the foamed rubber (g / cm ³ ), ρ ₀ is the density of the solid phase part of the foamed rubber (g / cm ³ ), and ρ _g is the density of the gas part inside the bubbles of the foamed rubber (g / 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. Since the density ρ _{g of the} gas portion is extremely small, close to zero, and extremely small with respect to the density ρ _{1 of the} solid phase portion, the equation (1) is expressed by the following equation V _s = {(ρ ₀ / ρ ₁ ) − 1} × 100 (%) --- (2).

The average closed cell diameter is measured by cutting a block-shaped sample out of a tread rubber made of foamed rubber and photographing it with an optical microscope at a magnification of 100 to 400.
The diameter of more than one closed cell was measured and expressed as an arithmetic mean value.

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 high hardness particles have an average particle size of 5 to 5.
It is specified that the thickness is 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 of durability such as abrasion resistance and crack resistance.

The content of the particles is specified to be 3 to 30 parts by weight with respect to 100 parts by weight of the rubber component.
This is because if the amount is less than 3 parts by weight, sufficient scratching effect cannot be obtained, and if the amount exceeds 30 parts by weight, durability problems occur. The average particle diameter is measured by laser diffraction measurement (light scattering method) using a microtrack. NIKKI made by Nikkiso Co., Ltd.
It was measured by a conventional method using an SO Microtrac MK11 particle size analyzer.

Further, in the particles, Al (OH) ₃ and / or
Alternatively, it is preferable to contain SiO ₂ in an amount of 20% by weight or more of the particle weight, but if it is less than 20% by weight, the adhesiveness cannot be secured because the reaction points of the particles with the coupling agent are small, and therefore the ability to scratch ice is significantly reduced. Therefore, it is not preferable.

As the binder, PMMA (polymethylmethacrylate), PVA (polyvinyl alcohol), polyvinyl acetate, polyacrylic acid, styrene-butadiene resin, polyester, epoxy resin, acrylic resin, phenol resin, melamine resin, PP resin, sy
It can be selected from resins conventionally used as binders such as n-1,2-polybutadiene resin.

The amount of the coupling agent used in combination is 3 to 50% by weight based on the weight of the particles, but if it is less than 3% by weight, sufficient adhesive force cannot be obtained. In addition, 50% by weight
When the amount is larger, a large amount of sulfur atom is released from the excess A group of the coupling agent, which increases the rubber elastic modulus, and
This is because the cost will be greatly increased and it will not be economical.

Next, examples of the silane coupling agent blended 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 10
However, if the amount is less than 10 parts by weight, the effect as a reinforcing agent is not exhibited, and if it exceeds 100 parts by weight, the dispersion of carbon black due to kneading cannot be ensured.
Moreover, since the viscosity becomes extremely high, the workability is significantly lowered, which is not preferable. Carbon black has N ₂ SA of 100 to 180 m ² / g and DBP of 120 to 180 ml.
It is specified to be within the range of / 100 g. When N ₂ SA exceeds 180 m ² / g and DBP exceeds 180 ml / 100 g, workability during rubber kneading and extrusion processability are deteriorated, which is not preferable. Also, N ₂ SA is less than 100 m ² / g and DBP
Is less than 120 ml / 100 g, it is not preferable because the wear resistance is lowered and the merit in terms of performance on ice is lost. In addition, N ₂ SA of carbon black is AST
M D3037-89, DBP is ASTM D2414
Compliant with -90. As the rubber component, those normally used as tread rubber 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. Further, a compounded drug or the like usually used in the rubber industry can be appropriately used.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
In each of the examples and the comparative examples, a rubber composition was prepared based on the formulations shown in Table 1, Table 2 and Table 3, and each performance shown in Table 1 was measured. In addition, it depends on a normal vulcanization condition.

The braking performance on ice is tire size 195/6.
A tire of 5R14 was produced, and even when the ice temperature was −2 ° C. and −8 ° C., after traveling straight for 200 km, braking was performed at a speed of 20 km / h, 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 ordinary roads, 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 running on general roads. ⊚ indicates no cracks, ∘ indicates a crack length of 0.5 mm.
Within, Δ is crack length within 1 mm, × is crack length 1
It was evaluated by classifying it as mm or more.

[0028]

[Table 1]

Particles A: Aluminum hydroxide crystals (manufactured by Showa Denko) Particles B: Crushed artificial marble Particles C, D, E, F: Prototypes Each particle was sieved and used to classify it into a desired particle size. .

[0030]

[Table 2]

[0031]

[Table 3]

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

[Table 4]

As described above, according to the present invention, the rubber composition reinforced with the predetermined carbon black has an ice temperature of -2.
It can be seen that excellent performance on ice is exhibited even on a road surface having a large amount of water at ℃, and also on a road surface (ice surface) at −8 ° C. where the ice hardness becomes higher.

Further, it can be seen that the wear resistance is not impaired, cracks are not generated, and the durability is good.
Since the artificial marble satisfies the various conditions required for the particles used in the present invention, the waste of building materials can be effectively used.

[0035]

According to the present invention, Al-OH, S is formed on the surface.
Particles having i-OH and having a hardness equal to or higher than a predetermined value are mixed in the foamed rubber, and a specific coupling agent is used to ensure the bonding between the particles and the rubber, which is a conventional problem. By avoiding the separation of the mixed particles that have been mixed together with the high structure carbon black that has excellent wear resistance,
It is possible to provide a rubber composition capable of further improving the performance on ice while maintaining the merit of abrasion resistance.

Claims (2)

[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
250 μm, 3 to 30 parts by weight of particles having an aluminum-bonded hydroxyl group and / or a silicon-bonded hydroxyl group on the surface are blended, and a compound represented by the general formula Y ₃ —Si—C _n H _2n A (wherein Y represents 1 to 4 carbon atoms) In the alkyl group, alkoxyl group or chlorine atom, the three Y's may be the same or different,
n represents an integer of 1 to 6, A is _{-S m C n H 2n Si-} Y
₃ group, a group selected from the group consisting of X group and -S _m Z 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. 3 to 50% by weight based on the weight of the particles, at least one of the coupling agents represented by the formula (1) is blended, and a nitrogen adsorption method specific surface area (N ₂ S) is added as a rubber reinforcing agent.
A rubber composition having closed cells, which comprises 10 to 100 parts by weight of carbon black having A) of 100 to 180 m ² / g and dibutyl terephthalate oil absorption (DBP) of 120 to 180 ml / 100 g. 2. Al (OH) ₃ and Si in the particles
The rubber composition according to claim 1, wherein at least one selected from the group consisting of O ₂ is contained in an amount of 20% by weight or more based on the weight of the particles.