JP2015229754A - Rubber composition and tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder blended rubber composition achieving environmental load reduction and having improved abrasion resistance compared to a conventional powder blended rubber composition, and a tire using the same.SOLUTION: There are provided a rubber composition manufactured by blending 5 pts.mass or more and less than 40 pts.mass of a powder rubber with 50 to 100 meshes [ASTM D5603-01(2008)] and more than 2.0 pts.mass of sulfur with respect to 100 pts.mass of a rubber component, and a tire using the rubber composition for a tread.

Description

  The present invention relates to a rubber composition and a tire using the rubber composition. More specifically, the present invention relates to a powder rubber-containing rubber composition capable of maintaining high fracture characteristics and improving the recycling rate of waste rubber obtained from rubber products such as used tires, and a tire using the same.

Waste tires have a higher recovery rate than ordinary plastic products, and are reused as fuel, especially in cement factories. However, in recent years, with the increase of environmental problems, there is a demand for improvement of so-called material recycling rate using tire rubber pieces or rubber powder as they are.
Patent Document 1 discloses an invention in which natural rubber and fine particle size powder rubber of 40 mesh or less are used as a master batch.
In Patent Document 2, vulcanized powder rubber having a particle size of 40 mesh or more and a softening agent 9 are blended with 100 parts by mass of diene rubber composed of natural rubber and / or synthetic isoprene rubber and butadiene rubber. A rubber composition for a tire cap tread is proposed.
However, although the above-mentioned powdered rubber compounded rubber composition can meet the demand for improving the material recycling rate of used rubber products from the viewpoint of reducing environmental burden in recent years, it has been difficult to ensure wear resistance.

Special table 2012-504185 gazette JP 2012-116977 A

  Under such circumstances, the present invention achieves a reduction in environmental burden, and a powder rubber compounded rubber composition with improved wear resistance compared to conventional powdered rubber compounded rubber compositions and tires using the same It is a problem to provide.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have made appropriate the relationship between the particle size of the powder rubber and the sulfur concentration in the rubber composition. The present inventors have found that the difference in sulfur concentration at the interface with the rubber composition can be reduced and the wear resistance of the rubber composition can be improved.
That is, the present invention
[1] 5-100 parts by mass of powder rubber of 50 to 100 mesh [ASTM D5603-01 (2008)] and more than 2.0 parts by mass of sulfur with respect to 100 parts by mass of the rubber component And a tire characterized by using the rubber composition according to [2] [1] for a tread,
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, while achieving environmental impact reduction, it can provide the powder rubber compound rubber composition and tire which were improved in abrasion resistance compared with the conventional powder rubber compound rubber composition. .

The rubber composition of the present invention has a powder rubber of 50 to 100 mesh [ASTM D5603-01 (2008)] of 5 parts by mass or more and less than 40 parts by mass and sulfur of 2.0 to 100 parts by mass of the rubber component. It is characterized by being blended more than part by mass.
Here, the 50-mesh [ASTM D5603-01 (2008)] powder rubber refers to a powder rubber that has passed through a 50-mesh sieve defined in ASTM D5603-01 (2008). Similarly, 100-mesh [ASTM D5603-01 (2008)] powdered rubber refers to powdered rubber that has passed through a 100-mesh sieve defined in ASTM D5603-01 (2008).
The reason why powder rubber of 50 mesh [ASTM D5603-01 (2008)] or more is used is to reduce the sulfur concentration step at the interface between the powder rubber and the rubber composition by reducing the surface area of the powder rubber. The use of powdered rubber of 100 mesh [ASTM D5603-01 (2008)] or less is to generate fracture nuclei at the interface between the powdered rubber and the rubber composition by limiting the number of powdered rubber particles in the same blending amount. This is to limit the number. From this viewpoint, it is preferably a powder rubber of 60 to 100 mesh [ASTM D5603-01 (2008)], and more preferably a powder rubber of 60 to 80 mesh [ASTM D5603-01 (2008)].
Hereinafter, [ASTM D5603-01 (2008)] is omitted, and simply referred to as “30 mesh”, “40 mesh”, “50 mesh”, “60 mesh”, “80 mesh”, “100 mesh”. Sometimes.
50 to 100 mesh [ASTM D5603-01 (2008)] powder rubber is blended in an amount of 5 parts by mass or more and less than 40 parts by mass with respect to 100 parts by mass of the rubber component. This is because it is difficult to meet the demand for improving the recycling rate, and when the blending amount is 40 parts by mass or more, it is difficult to improve the wear resistance. From this viewpoint, the blending amount of the powder rubber is preferably 5 to 35 parts by mass, more preferably 5 to 30 parts by mass, and 5 to 25 parts by mass with respect to 100 parts by mass of the rubber component. More preferably.

Although the manufacturing method of the powder rubber which concerns on this invention is not limited, For example, it manufactures as follows.
The raw rubber material processed into chips is finely pulverized by coarse pulverization, intermediate pulverization, and finish pulverization from coarse pulverized rubber to intermediate pulverized rubber, with the addition of anti-sticking agents as necessary. The finely pulverized rubber treatment method may include a finely pulverized step (A) and a classified and recovered step (B) in which the finely pulverized rubber is classified and at least part of the pulverized rubber is recovered as a finely powdered rubber product.
Furthermore, if it demonstrates in detail, it is preferable to provide the following 3 processes.
Pre-grinding step (Y): The rubber chips are processed into finely crushed rubber by a pre-grinding machine which is a pre-grinding means. However, the preliminary pulverization step is a selective step that is incorporated into the production method as necessary.
Fine pulverization step (A): The finely pulverized rubber is pulverized stepwise by a fine pulverizer as a fine pulverization means while adding an anti-sticking agent as necessary to finally finish the finely pulverized rubber.
Classifying and collecting step (B): Using the classifier as a classifying means, the finely pulverized rubber is powder rubber having a predetermined particle diameter (including fine powder rubber having a particle diameter smaller than the predetermined particle diameter) and the others. The product is classified (sorted) and collected as a product. For classification, a mesh sieve defined in ASTM D5603-01 (2008) having a predetermined sieve opening may be used.
In the preliminary pulverization step (Y), for example, a rubber chip (tire chip) obtained by crushing a cut tire obtained by cutting a waste tire (having removed a tire reinforcing material such as a beat wire, a steel belt, and a ply) into a predetermined size is obtained. The rubber raw material is put into a preliminary pulverizer and processed into a finely pulverized rubber by a pulverization section provided in the pulverization chamber. The rubber chip supplied to the preliminary pulverizer is appropriate, but cutting to a size of about 1 mm to 8 mm helps to reduce the particle size of the finely pulverized rubber. By pre-ripening the rubber chips, smoothing by the pre-pulverizer is smooth, but there is no problem in processing at normal temperature, and whether or not preheating is added is appropriately selected. Is done.
Further, finely pulverized rubber having a small particle diameter can be produced by repeatedly pulverizing the rubber chip with a preliminary pulverizer a plurality of times.
The range of the size of the rubber chip is not limited to 1 mm to 8 mm, but by setting the size of the rubber chip within the above range, the preliminary grinding step ( The reduction in the grinding efficiency in Y) is suppressed.
As the preliminary pulverizer, an appropriate one such as an extruder for stirring and pulverizing rubber chips or a roll pulverizer for pulverizing with a roll is selected.

  In the fine pulverization step (A), the finely pulverized rubber processed by the preliminary pulverizer is subjected to rough pulverization, intermediate pulverization, finish pulverization, and processed into pulverized rubber. The fine pulverizer is preferably a roll pulverizing means in which a rough pulverizing part, a medium pulverizing part and a finish pulverizing part are continuously arranged from the upper stage (or upstream) to the lower stage (or downstream). The finely pulverized rubber processed in the finish pulverization step is sent to the classifier in the classification recovery step (B).

In the pulverization step, the anti-sticking agent added as necessary is supplied to the stirrer arranged above the coarse pulverization unit, the medium pulverization unit and the finish pulverization unit, and uniformly with the pulverized rubber in the stirrer. The mixture is stirred and charged into the rough pulverization unit, the medium pulverization unit, and the finish pulverization unit.
As the anti-sticking agent, fillers (calcium carbonate, alumina, zinc oxide, etc.) and reinforcing materials (carbon black, talc, silica, etc.) are suitable. The type of the anti-sticking agent is appropriately selected in consideration of the manufacturing cost, the use of finely pulverized rubber, and the like.
By adding an anti-sticking agent, the surface of the pulverized rubber is coated, and the crushed rubber is prevented from adhering and bonding again, and there is an advantage that classification (selection) by a classifier becomes efficient and easy. While securing this type of advantage, a small amount of anti-sticking agent contributes to cost reduction and is convenient for reuse as a tire raw material.

  The powder rubber used in the powder rubber composition of the present invention is a vulcanized powder rubber (recycled powder rubber) obtained by recycling waste rubber products, and the types of waste rubber used as the raw material for the powder rubber are particularly limited. Instead, it may contain at least one selected from natural rubber and synthetic rubber. The synthetic rubber is preferably a diene rubber, for example, polyisoprene rubber, styrene-butadiene copolymer rubber, high cis-1,4-polybutadiene rubber, low cis-1,4-polybutadiene rubber, ethylene-propylene-diene. Examples include terpolymer rubber, chloroprene rubber, butyl rubber, halogenated butyl rubber, and acrylonitrile-butadiene rubber.

  The rubber component used in the powder rubber compounded rubber composition of the present invention is not limited as long as it is a rubber-like substance, but preferably contains a diene rubber selected from natural rubber and synthetic diene rubber. Synthetic diene rubbers include polybutadiene rubber (BR), polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), ethylene-propylene-diene terpolymer rubber, chloroprene rubber, butyl rubber, halogenated Examples include synthetic rubbers such as butyl rubber and acrylonitrile-butadiene rubber. These diene rubbers may be used alone or as a mixture of two or more.

The sulfur compounded in the rubber composition of the present invention is preferably powdered sulfur, and may be any of petroleum-derived powder sulfur, volcanic mine-based powder sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur and the like. Sulfur compounds capable of releasing sulfur such as morpholine disulfide; polysulfide polymer (polysulfide); sulfur-containing vulcanization accelerators such as tetramethylthiuram disulfide and 2- (4′-morpholinodithio) benzothiazole It may be. However, the compounding amount of sulfur in the case of a sulfur compound is calculated as sulfur that can be released from the sulfur compound as sulfur compounded in the sulfur rubber composition of the present invention.
In the rubber composition of the present invention, sulfur is added in an amount of more than 2.0 parts by mass with respect to 100 parts by mass of the rubber component, because the wear resistance of the rubber composition is lowered at 2.0 parts by mass or less of sulfur. From this viewpoint, it is preferable to blend 2.1 parts by mass or more of sulfur. Moreover, in the rubber composition of this invention, it is preferable to mix | blend 10 mass parts or less of sulfur with respect to 100 mass parts of rubber components. This is because if the amount of sulfur is 10 parts by mass or less, the fracture resistance of the rubber composition is improved. In this respect, the amount of sulfur is preferably 5 parts by mass or less with respect to 100 parts by mass of the rubber component.

It is preferable that at least one filler selected from carbon black and inorganic filler is blended with the rubber composition of the present invention as desired.
The carbon black is not particularly limited. For example, high, medium or low structure SAF, ISAF, IISAF, N339, HAF, FEF, GPF, SRF grade carbon black, especially SAF, ISAF, IISAF, N339, HAF, FEF Grade carbon black is preferably used. The nitrogen adsorption specific surface area (N ₂ SA, measured in accordance with JIS K 6217-2: 2001) is preferably 30 to 250 m ² / g. This carbon black may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of inorganic fillers include alumina (Al ₂ O ₃ ) such as silica, γ-alumina, α-alumina, alumina monohydrate (Al ₂ O ₃ .H ₂ O) such as boehmite and diaspore, gibbsite, Aluminum hydroxide such as bayerite [Al (OH) ₃ ], aluminum carbonate [Al ₂ (CO ₃ ) ₃ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium oxide (MgO), magnesium carbonate (MgCO ₃ ) Talc (3MgO · 4SiO ₂ · H ₂ O), attapulgite (5MgO · 8SiO ₂ · 9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [Ca (OH) _2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay _{(Al 2 O 3 · 2SiO 2} ), kaolin (Al ₂ O ₃ · ₂ iO ₂ · 2H ₂ O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate (Al ₂ SiO _5, Al ₄ / 3SiO ₄ / 5H ₂ O etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), calcium silicate (Ca ₂ · SiO ₄ etc.), aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO etc.) ₂ ), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ .nH ₂ O], zirconium carbonate [Zr (CO ₃ ) ₂ ], crystalline aluminosilicates containing hydrogen, alkali metals or alkaline earth metals that correct the charge, such as various zeolites, can be used.

Of the above inorganic fillers, silica is preferable from the viewpoint of achieving both low rolling properties and wear resistance. Any commercially available silica can be used. Among them, wet method silica, dry method silica, and colloidal silica are preferably used, and wet method silica is more preferably used. Among wet method silicas, precipitation method silica is used. Is particularly preferred. The BET specific surface area (measured in accordance with ISO 5794/1) of silica is preferably 40 to 350 m ² / g. Silica having a BET surface area within this range has an advantage that both rubber reinforcement and dispersibility in a rubber component can be achieved. In this respect, BET surface area is more preferably silica in the range of 80~350m ² / g, silica BET surface area in the range of 120~350m ² / g is particularly preferred. Examples of such silica include Tosoh Silica Co., Ltd., trade name “Nipsil AQ” (BET specific surface area = 205 m ² / g), “Nipsil KQ”, and Degussa's trade name “Ultra Gil VN3” (BET specific surface area = 175 m ² / g) can be used.

The filler used in the rubber composition of the present invention is preferably used in an amount of 20 to 150 parts by mass with respect to 100 parts by mass of the rubber component. If it is 20 parts by mass or more, it is preferable from the viewpoint of improving the wear resistance of the rubber composition, and if it is 150 parts by mass or less, it is preferable from the viewpoint of reducing rolling resistance.
In the filler, carbon black is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 70% by mass or more.
Moreover, it is preferable that an inorganic filler is 70 mass% or less in the said filler, It is more preferable that it is 60 mass% or less, It is still more preferable that it is 30 mass% or less.

  The rubber composition of the present invention is usually used in the rubber industry such as the above-mentioned powder rubber, rubber component, anti-aging agent, sulfur-free vulcanizing agent, vulcanization accelerator, zinc oxide, stearic acid and softening agent. The compounding agent used can be appropriately selected and blended within a range not contrary to the object of the present invention. As these compounding agents, commercially available products can be suitably used. The rubber composition of the present invention is produced by blending a rubber component with a powder rubber and various compounding agents appropriately selected as necessary, and kneading, heating, extruding, and the like. Can do.

The tire of the present invention is characterized by using the above-described rubber composition of the present invention for a tread. Since the rubber composition of the present invention in which the above-described powder rubber is blended has sufficient wear resistance, it can be suitably used for a tread.
Moreover, as gas with which the pneumatic tire which is the tire of this invention is filled, inert gas, such as nitrogen, argon, helium other than the air which adjusted normal or oxygen partial pressure, can be used.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. The abrasion resistance was evaluated based on the following method.
<Abrasion resistance>
A test tire with a half-buffed tread portion is attached to the vehicle, and after traveling 10,000 km, the travel distance per 1 mm 2 is obtained from the average value of the groove depth, and the travel distance of Comparative Example 1 is taken as 100. The index was expressed by the following formula. The higher the index value, the better the wear resistance.
Abrasion resistance index = [(travel distance per 1 mm groove depth of test tire) / (travel distance per 1 mm groove depth of tire of Comparative Example 1)] × 100

Examples 1-3 and Comparative Examples 1-7
The rubber compositions of Examples 1 to 3 and Comparative Examples 1 to 7 were prepared by an ordinary kneading method using a closed kneading apparatus (Banbury mixer) according to the formulation shown in Table 1.
Next, a pneumatic radial tire for trucks and buses (size: 11R22.5) using the rubber compositions of Examples 1 to 3 and Comparative Examples 1 to 7 as tire tread rubber was prototyped, and the wear resistance was measured as described above. It was evaluated by the method. The evaluation results are shown in Table 1.

[note]
The materials * 1 to * 11 used in Table 1 are as follows.
* 1) SBR: Emulsion-polymerized styrene-butadiene copolymer rubber, manufactured by JSR Corporation, trade name “SBR # 1500”
* 2) BR: Polybutadiene rubber, manufactured by JSR Corporation, trade name “BR01”
* 3) 80 mesh powder rubber: Powder rubber that passed through 80 mesh [ASTM D5603-01 (2008)] sieve, manufactured by Lehigh Technologies, Inc., trade name “PolyDyne 80”
* 4) 60 mesh powder rubber: Shinsei Rubber Co., Ltd., trade name “P-50”, and further passed through 60 mesh [ASTM D5603-01 (2008)] sieve * 5) 40 mesh powder Rubber: Powdered rubber that passed through a 40 mesh [ASTM D5603-01 (2008)] sieve, manufactured by Lehigh Technologies, Inc., trade name “PolyDyne 40”
* 6) 30 mesh powder rubber: Powder rubber that passed through a 30 mesh [ASTM D5603-01 (2008)] sieve, manufactured by Shinsei Rubber Co., Ltd., trade name “P-30”
* 7) Carbon black: N220, manufactured by Asahi Carbon Co., Ltd., trade name “Asahi # 80”
* 8) Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name “Noxeller CZ”

  As is clear from the results in Table 1, the rubber compositions of the present invention of Examples 1 to 3 are excellent in wear resistance as compared with the rubber compositions to be compared in Comparative Examples 4 to 7. I understand.

Since the rubber composition of the present invention is excellent in wear resistance, it is used as a tread member of a tire. In particular, heavy load air such as truck / bus tires, off-the-road tires (construction vehicle use, mining vehicle use, etc.), etc. It is suitably used for a tread member of a tire containing a tire, and the material recycling rate of waste rubber obtained from rubber products such as used tires can be improved.

Claims (5)

  50 to 100 mesh [ASTM D5603-01 (2008)] powder rubber is blended in an amount of 5 parts by mass or more and less than 40 parts by mass, and more than 2.0 parts by mass of sulfur with respect to 100 parts by mass of the rubber component. Rubber composition.   The rubber composition according to claim 1, wherein the powder rubber is a powder rubber of 60 to 80 mesh [ASTM D5603-01 (2008)].   The rubber composition of Claim 1 or 2 whose compounding quantity of the said powder rubber is 5-35 mass parts with respect to 100 mass parts of rubber components.   The rubber composition according to any one of claims 1 to 3, wherein the rubber component includes a diene rubber selected from natural rubber and synthetic diene rubber.   A tire comprising the rubber composition according to any one of claims 1 to 4 as a tread.