JPH0676070B2 - Rubber crawler - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rubber crawler which has improved cut resistance and molding processability and has a lightweight product.

[Industrial application] The performance required especially for rubber crawlers that travel on rough terrain such as construction vehicles, agricultural tractors, tanks, snow vehicles, etc., is due to elastic tracks that come into contact with protrusions on the ground. Resistance to chipping and scratching of rubber material and abrasion resistance.

INDUSTRIAL APPLICABILITY The rubber crawler of the present invention has good cut resistance of the rubber material for elastic footwear, has large tear strength and abrasion resistance, and is excellent in moldability as compared with the conventional one.

[Prior Art] Various attempts have been made to improve the cut resistance and wear resistance of rubber materials for rubber crawlers, but improvement in cut resistance and wear resistance (evaluated by pico wear) is insufficient. In some cases, the Mooney viscosity of the rubber composition was increased, and the molding method was complicated, resulting in poor moldability of the rubber material, which was not satisfactory.

That is, in order to improve the cut resistance and wear resistance of the rubber material, even if a rubber composition containing a large amount of carbon black is used, the cut resistance and wear resistance are improved but it is not sufficient. On the contrary, there is a drawback that the Mooney viscosity of the composition increases and the weight of the product also increases, and conversely, when a rubber composition containing a small amount of carbon black is used, the cut resistance and abrasion resistance are deteriorated. is there.

In addition, nylon cut fiber should be 5-30 for rubber.
The method of adding PHR improves the durability to some extent compared to the method of adding no fiber, but because it uses cut fibers that do not bond with rubber at all, it is molded with the cut fibers oriented perpendicular to the ground plane. It is necessary and the moldability is extremely poor.

[Problems to be Solved by the Invention] The present invention solves the drawbacks such as poor moldability, low cut resistance and low abrasion resistance of the prior art by blending a special reinforced rubber composition, It is to provide a rubber crawler having excellent moldability and good durability.

[Means for Solving the Problems] In the present invention, fine vulcanizable short fibers of polyamide capable of forming fibers are embedded in a vulcanizable rubber, and the polyamide and the rubber contain a silane coupling agent. A rubber composition comprising a reinforced rubber composition (A), a diene rubber (B), and a carbon black (C), which are bonded together via an adhesive, and which satisfies the following conditions (I) to (IV): Is used to solve the problem of the rubber crawler.

(I) The amount of the polyamide is 1 to 20 parts by weight based on 100 parts by weight of all rubber components, and (II) the ratio of the total of natural rubber and / or polyisoprene in the components (A) and (B) is 60 to all rubber components
100% by weight, (III) the amount of carbon black is 30 to 60 parts by weight based on 100 parts by weight of the total rubber component, and (IV) the hardness of the vulcanizate measured by JIS K6301A type spring hardness test. 55 to 75 °.

In the present invention, the vulcanizable rubber is a continuous phase in which fine short fibers of polyamide capable of forming fibers are dispersed, and at the interface of the short fibers, the polyamide and the vulcanizable rubber are It is necessary to formulate a reinforced rubber composition which is bonded via a silane coupling agent,
Despite this blending polyamide fibers,
A rubber composition having excellent moldability can be produced, and a rubber crawler having excellent cut resistance can be produced by using this composition as a rubber material for elastic footwear.

Hereinafter, the rubber crawler of the present invention will be described in detail.

Examples of the vulcanizable rubber used in the reinforced rubber composition constituting the rubber crawler of the present invention include natural rubber, polyisoprene, isoprene-isobutylene copolymer, chlorinated butyl rubber, brominated butyl rubber, and mixtures thereof. You can Among these rubbers, natural rubber is preferable. When a synthetic rubber is used as the rubber, it is preferable to use a rubber containing a tackifier. As the above-mentioned tackifier, it has excellent compatibility with rubber and has a tackifying effect on synthetic rubber. It is non-reactive or extremely low in reactivity (that is, it does not substantially react with synthetic rubber when heated). ) All tackifiers can be used, for example, coumarone resin such as coumarone indene resin, non-reactive phenol formaldehyde resin such as non-reactive phenolic resin, alkylphenol acetylene resin, terpene / phenolic resin, polyterpene resin , Hydrocarbon-based tackifying resins, petroleum-based hydrocarbon resins such as polybutene, rosin derivatives such as zinc resinate, and mixtures thereof. The tackifier is rubber 100
It is preferably blended in a proportion of 0.5 to 20 parts by weight, particularly 0.5 to 10 parts by weight, relative to parts by weight.

Further, the polyamide used in the reinforced rubber composition,
It is capable of forming fibers and has a melting point of 150 to 260 ° C, preferably
190-235 ℃, Nylon 6, Nylon 610, Nylon 1
2, Nylon 611, Nylon 612, Nylon 66, copolymers thereof, and the like. The polyamide is not particularly limited as long as it has a fiber-forming ability,
The number average molecular weight is 5,000 or more, preferably 8,000 or more.
If the molecular weight is too low, the fiber-forming ability is poor and the strength is low.

Short fibers used in the reinforced rubber composition of the present invention,
The above-mentioned polyamide fine short fibers, which have a form in which molecules are arranged in the fiber axis direction, and whose average diameter is preferably 0.05 to 0.8 µ, and particularly the circular cross section and the shortest fiber length of 1 µ or more. Are preferred.

Further, the reinforcing rubber composition structure The silane coupling agent used in the formula Y-R ₁ SiX ₃ or Y-R ₁ SiX _2,
The compound shown by is used.

Here, Y, R ₁ , R ₂ and X respectively represent the following groups.

Y: R ₁ : ApCnH ₂ nBQCmH ₂ mBQClH ₂ l A: C ₆ H ₄ p = 0 to 2 n = 0 to 5 B: O, NH Q = 0 to 2 m = 0 to 5 l = 0 to 5 R ₂ : CnH ₂ n + 1 n = 1 to 4 X: DrCnH ₂ nEsCmH ₂ m + 1 D: O, Cl r = 0 to 2 n = 0 to 5 E: O s = 1 to 2 m = 1 to 5 Specifically, γ-aminopropyl Trimethoxysilane, γ
-Aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-
β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ- (diethylenetriamino) propyltrimethoxysilane, γ-ureate-propyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (βmethoxyethoxy) silane , Γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β
-(3.4 Epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-chloropropylmethoxysilane, γ-mercaptopropyltrimethoxysilane, N-phenyl-γ-aminopropyltriethoxysilane, N-β (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride group and the like can be preferably used.

Further, the ratio of the weight of the vulcanizable rubber to the weight of the fine polyamide short fibers embedded in the vulcanizable rubber (vulcanizable rubber / fine polyamide short fibers) is 10
It is preferable that the polyamide forming the short fibers and the vulcanizable rubber are bonded to each other via a silane coupling agent so that the content is -30% by weight, particularly 15-30% by weight.

In the present invention, the strength of the fine short fibers of the fiber-forming polyamide embedded in the vulcanizable rubber in the reinforced rubber composition to be used is high, and the vulcanization of the polyamide and the vulcanization is performed at the interface of the short fibers. Since it is bonded to possible rubber via a silane coupling agent, a rubber composition with a low Mooney viscosity and excellent moldability can be obtained. By using this composition as a rubber material, cut resistance and abrasion resistance can be improved. A rubber crawler with good properties can be manufactured.

The above-mentioned reinforced rubber composition used in the present invention is produced, for example, as follows. Vulcanizable rubber, 5-100 parts by weight of polyamide per 100 parts by weight of the vulcanizable rubber, and silane coupling agent 0.1-5.5 per 100 parts by weight of the polyamide.
0.5 parts by weight and, if necessary, 0.5 to 20 parts by weight of a viscosity-imparting agent per 100 parts by weight of the vulcanizable rubber are kneaded at a temperature equal to or higher than the melting point of the polyamide, and the resulting kneaded product is the melting point of the polyamide. It can be obtained by extruding at the above temperature, or further, by appropriately stretching the extrudate at a temperature higher than or lower than the melting point of the polyamide. Further, it can be obtained by using these stretching together.

The bead filler rubber composition of the present invention comprises the reinforced rubber composition (A) and a diene rubber (B) and carbon black (C).

Examples of the diene rubber (B) include natural rubber, polyisobrene, cis-1.4 polybutadiene, styrene-butadiene copolymer rubber, and isobrene-isobutylene copolymer.

As the carbon black, a particle size of 10 to 35 mμ,
A dibutyl phthalate (DBP) oil absorption amount of 90 to 130 ml / 100 g is preferably used. Especially as carbon black N
-110 to N-330 are preferably used.

Each of the above components, (I) the amount of the polyamide is the total rubber component
1 to 20 parts by weight, preferably 2 to 15 parts by weight, relative to 100 parts by weight, and the ratio of the natural rubber and / or polyisobutylene in the components (II), (A) and (B) is the total rubber component. 60 to 100% by weight, preferably 90% by weight or more, and the amount of (III) carbon black is 100
30 to 60 parts by weight, preferably 40 to 55 parts by weight with respect to parts by weight, (IV) the hardness of the vulcanizate measured by JIS K6301A type spring type hardness test is 55 to 75 °, preferably 65 to 75
It is blended so as to satisfy each of the conditions. If the amount of polyamide (fine short fibers) is less than the lower limit, the cut resistance and abrasion resistance of the rubber crawler will be reduced, and if it is more than the upper limit, the Mooney viscosity of the compound will increase and the rubber crawler moldability will tend to deteriorate. is there. If the amount of carbon black is less than the lower limit, the hardness and abrasion resistance of the vulcanized product will be reduced, and if it is more than the upper limit, the Mooney viscosity of the composition will be too high and the rubber crawler moldability will tend to deteriorate.
If the proportion of the rubber is outside the above range, the cut resistance of the vulcanizate will be reduced. Further, if the hardness of the vulcanized product is out of the above range, the running property of the rubber crawler is deteriorated.

The rubber composition used in the present invention is prepared by using a kneading machine such as a Banbury mixer or a roll extruder for each of the above components in an amount of 50 to 180.
It can be obtained by kneading at a temperature of 1 to 16 minutes. Additives such as a vulcanizing agent are added to the rubber composition.

As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxides, and sulfur-containing compounds can be used. The method of compounding the vulcanizing agent with the rubber composition is not particularly limited, and a compounding method known per se can be adopted. Along with the vulcanizing agent, white carbon, activated calcium carbonate, ultrafine magnesium silicate, high styrene resin, coumaroindene resin, phenol resin, lignin,
Reinforcing agents such as modified melamine resin, petroleum resin, various grades of calcium carbonate, basic gnesium carbonate, clay,
Accelerating vulcanization of zinc flower, diatomite, recycled rubber, powdered rubber, ebonite powder and other fillers, aldehydes, ammonia, aldehydes / amines, guanidines, thiazoles, thiurams, dithiocarbamates, xanthates, etc. Agents, vulcanization accelerators such as metal oxides and fatty acids, amines / aldehydes, amines / ketones, amines, phenols, imidazoles, sulfur-containing or phosphorus-containing antioxidants, naphthenes and aromatics The composition can be prepared by blending a system process oil and the like within a range that does not impair the effects of the present invention. The process oil may use a small amount (0 to 15 phr) of an aromatic system having good mechanical performance of the vulcanizate. As for the antioxidant, it is preferable to mainly use an ozone-resistant antioxidant together with paraffin wax. The amount may total from 1 to 5 phr. As the vulcanization system, it is preferable to use a vulcanization accelerator (a sulfenamide type and a thiazole type are preferable) and a sulfur (a slightly larger amount is preferable for chip-cut resistance). The rubber crawler of the present invention can be manufactured by a method known per se by combining a rubber material, a core metal, a cord and the like.

[Effects of the Present Invention] The composition of the present invention has a lower Mooney viscosity than conventional products and thus is excellent in moldability, and also has good cut resistance, large tear strength and abrasion resistance, Instead of the rubber material for the rubber crawler, it can be used for a rubber crawler that mainly travels on an irregular ground such as a construction vehicle, an agricultural tractor, a tank, and a snow vehicle.

[Examples of the Present Invention] Examples and comparative examples are shown below. In the following description, part means part by weight.

In each of the following examples, the Mooney viscosity of the rubber composition is JISK
According to 6300, the hardness and tear strength of the vulcanizate were measured according to JIS K6301, and the pico abrasion was measured according to ASTM D2228. The cut resistance was measured using a DuPont impact tester on a 30 × 30 × 2 mm test piece. However, the edge angle of the pedestal is 45 ° and the diameter is 1.
The weight was 27 cm, the falling weight was 300 g, and the point at which half of 10 test pieces were damaged was taken as the breaking point.

The compositions (compounding ratio) of the reinforced rubber composition, the composition (blending ratio) of the rubber composition for the rubber crawler of the present invention, and the rubber for rubber crawler of the present invention in Examples 1-10 and Comparative Examples 1-4 below. The physical properties and the like of the composition are collectively shown in Tables 1 and 2 below.

Example 1 100 parts of natural rubber (NR) having a viscosity of 1 × 10 ⁶ poise in a Brabender blast graph set at 22 ° C. and 50 rpm,
In addition, 1.0 part of N- (3-methacryloyloxy-2-hydroxypropyl) -N'-phenyl-P-phenylenediamine [trade name Nocrac G-1, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.] is added as an antioxidant. Then, after kneading these for 30 seconds, nylon 6 (trade name 1030B, manufactured by Ube Industries,
Melting point 221 ° C, molecular weight 30,000) 2 parts by weight of N per 100 parts by weight
51 parts of pellets in which β- (aminoethyl) γ-aminopropyltrimethoxysilane (trade name KBM603, manufactured by Shin-Etsu Chemical Co., Ltd., hereinafter referred to as Silane A) was kneaded in advance, and kneaded for 13 minutes (while mixing The temperature in lavender is 23
(Raised to 0 ° C.) to obtain a kneaded product. The resulting kneaded product was string-shaped at a die set temperature of 235 ° C using a 20 mmφ extruder (manufactured by Haake) having a circular die having an inner diameter of the nozzle of 2 mm and a ratio of the length of the nozzle to the inner diameter (L / D) of 2. Then, the extrudate was wound on a bobbin at a draft ratio of 10 (speed of 38.8 m / min) through a guide roll installed 3 m below the nozzle. Approximately 500 rolls are bundled into a sheet (thickness 2 mm, width 150 mm)
This sheet material was rolled about 10 times with a pair of rolling rolls having a roll gap of 0.2 mm and a temperature of 60 ° C. to obtain a reinforced rubber composition (masterbatch) (Sample 1).

Next, with Banbury set at 90 ° C and 77 rpm,
Of the compounding recipes shown in Table 2, compounding ingredients other than the vulcanization accelerator and sulfur are kneaded to obtain a kneaded product.
A vulcanization accelerator and sulfur were kneaded on a 10-inch roll, rolled out into a sheet, then placed in a mold for vulcanization,
A vulcanized product was obtained. Vulcanization was performed at 145 ° C. for 40 minutes.

Example 2 Instead of silane A, vinyltris (β-methoxyethoxy) silane (trade name KBC1003, manufactured by Shin-Etsu Chemical Co., Ltd.,
A reinforced rubber composition (Sample 2) was obtained in the same manner as in Example 1 except that silane B) was used. This rubber for rubber crawlers was obtained in the same manner as in Example 1 except that Sample 2 was used as the reinforced rubber composition. A composition was obtained.

Example 3 In place of silane A, γ-methacryloxypropyltrimethoxysilane (trade name KBM503, manufactured by Shin-Etsu Chemical Co., Ltd., silane C) was used in the same manner as in Example 1 except that a reinforced rubber composition (sample) was used. 3) was obtained, and a rubber composition for a rubber crawler was obtained in the same manner as in Example 1 except that this sample 3 was used as a reinforced rubber composition.

Example 4 A reinforced rubber composition (Sample 4) was prepared in the same manner as in Example 1 except that γ-mercaptopropyltrimethoxysilane (trade name KBM803, manufactured by Shin-Etsu Chemical Co., Ltd., Silane D) was used instead of silane A. 1) was obtained, and a rubber composition for a rubber crawler was obtained in the same manner as in Example 1 except that this sample 4 was used as a reinforced rubber composition.

Example 5 A reinforced rubber was obtained in the same manner as in Example 1 except that β- (3.4-epoxycyclohexyl) ethyltrimethoxysilane (trade name KBM303, manufactured by Shin-Etsu Chemical Co., Ltd., Silane E) was used instead of silane A. A composition (sample 5) was obtained, and a rubber composition for a rubber crawler was obtained in the same manner as in Example 1 except that this sample 5 was used as a reinforced rubber composition.

Example 6 Nylon 6 (trade name: 1013B, manufactured by Ube Industries, Ltd., melting point 221)
℃, molecular weight 13,000) 4 parts by weight of silane A per 100 parts by weight
Was carried out in the same manner as in Example 1 except that 52 parts of pellets which had been kneaded in advance were used to obtain a reinforced rubber composition (Sample 6), and this Sample 6 was used as a reinforced rubber composition. Similarly, a rubber composition for a rubber crawler was obtained.

Example 7 A reinforced rubber composition (Sample 7) was obtained in the same manner as in Example 1 except that the amount of 6-nylon added to natural rubber was changed to 100 parts, and this Sample 7 was used as the reinforced rubber composition. A rubber composition for a rubber crawler was obtained in the same manner as in Example 1 except for the above.

Example 8 A reinforced rubber composition (Sample 8) was obtained in the same manner as in Example 1 except that the amount of 6-nylon added to natural rubber was changed to 20 parts, and this Sample 8 was used as the reinforced rubber composition. A rubber composition for a rubber crawler was obtained in the same manner as in Example 1 except for the above.

Examples 9 to 10 Rubber compositions for rubber crawlers were obtained in the same manner as in Example 1 except that the composition (blending ratio) of each component was changed as shown in Table 2.

Comparative Examples 1 to 3 Rubber compositions for rubber crawlers were obtained in the same manner as in Example 1 except that the use ratio (composition) of each component was changed as shown in Table 2 without using the reinforced rubber composition.

Comparative Example 4 A rubber composition for a rubber crawler was obtained in the same manner as in Example 1 except that natural rubber and 5 parts of nylon cut fiber were used instead of the reinforced rubber composition. The results are summarized in Table 2.

The amount of bound rubber in each of Samples 1 to 8 (reinforced rubber composition) shown in Table 1 was measured as follows.

[Measurement of bound rubber amount]

2 g of the reinforced rubber composition was added to 200 ml of toluene at 80 ° C. to dissolve the rubber component in the reinforced rubber composition, and the resulting slurry was centrifuged at room temperature to separate it into a solution portion and a precipitation portion. The above operation was repeated 7 times for the precipitated portion, and then the precipitated portion was dried to obtain a nylon fiber. This nylon fiber was dissolved in a mixed solvent of phenol and orthodichlorobenzene and analyzed by ¹ H nuclear magnetic resonance spectrum (NMR) (tetramethylsilane internal standard).
From the chart, methyl group and methylene group due to rubber,
Methylene group, NH adjacent to CO group due to 6-nylon
For each peak of the methylene group adjacent to the group and each of the other three methylene groups, the bound rubber amount was calculated by obtaining the molar ratio of 6-nylon and natural rubber by the cut area method. In addition, the shape of the nylon fiber is approximately 200
The book was measured using a scanning microscope at a magnification of 10,000 times. The fibers were very fine short fibers with a circular cross section.

Further, (Note 1) to (Note 3) in Table 2 are as follows.

(Note 1) BR: Polybutadiene rubber (UBEPOL-BR100, manufactured by Ube Industries, Ltd.) (Note 2) Cut fiber: Nylon short fiber diameter 20μ
m, average length 2 mm (Note 3) Other compounding agents Zinc white 3 parts, steering acid 2 parts, antioxidant N-phenyl-N'-isopropyl-P-phenylenediamine 1
Part, paraffin wax 2 parts, vulcanization accelerator N-oxydiethylene-2-benzothiazoylsulfenamide 1 part,
2 parts of sulfur

Claims (1)

[Claims] 1. A reinforced rubber composition in which fine vulcanizable polyamide short fibers are embedded in a vulcanizable rubber, and the polyamide and the rubber are bonded via a silane coupling agent. Characterized in that a rubber composition comprising the compound (A), a diene rubber (B), and carbon black (C) and satisfying the following conditions (I) to (IV) is used as a rubber material: And rubber crawler. (I) The amount of the polyamide is 1 to 20 parts by weight based on 100 parts by weight of all rubber components, and (II) the ratio of the total of natural rubber and / or polyisoprene in the components (A) and (B) is 60 to all rubber components
100% by weight, (III) the amount of carbon black is 30 to 60 parts by weight based on 100 parts by weight of the total rubber component, and (IV) the hardness of the vulcanizate measured by JIS K6301A type spring hardness test. 55 to 75 °.