JP6334374B2 - Rubber composition for rubber crawler and rubber crawler - Google Patents

Description

  The present invention relates to a rubber composition for a rubber crawler and a rubber crawler.

  A rubber crawler usually has a structure in which a steel cord for holding and reinforcing the tension of the rubber elastic body is embedded in an endless rubber elastic body, and a large number of protrusions called lugs are formed on the outer peripheral surface. Take. These rubber crawlers are mainly used as traveling parts of civil construction machines, agricultural machines, industrial machines and the like.

  When the elastic modulus of the rubber elastic body on the outer surface of the rubber crawler is low, the end of the rubber elastic body on the outer surface of the rubber crawler in the width direction of the rubber crawler is wound on the grounding side due to friction with the road surface when turning There is. Due to this entrainment, a large tensile deformation force is applied to the rubber elastic body on the inner peripheral surface side of the rubber crawler, and a crack is generated at the end of the rubber elastic body in the rubber crawler width direction (hereinafter also referred to as a rubber crawler ear). In some cases, means for preventing entrainment have been studied. For example, means for improving the elastic modulus of the rubber elastic body by increasing the reinforcing effect by increasing the compounding ratio of black filler such as carbon black in the rubber composition or white filler such as silica, talc, calcium carbonate, Means for improving the elastic modulus of the rubber elastic body by increasing the vulcanization density by increasing the mixing ratio of sulfur in the rubber composition, and improving the rigidity and durability of the rubber elastic body by adding short crystal fibers (Patent Document 1), means for reinforcing the end of the outer peripheral surface of the rubber crawler, and the like have been considered.

JP 2009-227696 A

  However, if the blending ratio of the filler is increased, the dispersion of the filler may be insufficient and the quality may become non-uniform, or the viscosity of the unvulcanized rubber composition may increase and workability may deteriorate. There is. Moreover, since the heat aging is accelerated | stimulated when the compounding rate of sulfur is raised, it may lead to the performance fall of a rubber crawler.

  In a paving construction machine such as a paver, a rubber crawler may be driven under a high temperature condition as in asphalt paving. When the grounding surface of the rubber crawler becomes high temperature, the physical properties of the rubber elastic body of the rubber crawler are deteriorated, and the ear portion of the rubber crawler is more easily caught on the grounding side during turning. Therefore, there is a case where a sufficient effect cannot be obtained when the road surface is hot under the condition that the road surface is hot and the means for preventing the rubber crawler ears from being caught on the ground side during turning.

  Therefore, the present invention relates to a rubber composition for a rubber crawler that can obtain a rubber crawler that can prevent the ear portion of the rubber crawler from being caught on the ground side during turning, and the turning It is an object of the present invention to provide a rubber crawler that can prevent the ear portion of the rubber crawler from being caught on the ground side.

  The rubber composition for a rubber crawler of the present invention is characterized by containing a diene rubber and a high styrene rubber having a styrene content of 50% by mass or more as rubber components. According to the rubber composition for a rubber crawler of the present invention, it is possible to increase the elastic modulus after vulcanization even under a high temperature condition, so that the ear part of the rubber crawler is wound to the ground side during turning. Can be suppressed.

  In the rubber composition for a rubber crawler of the present invention, the blending amount of the high styrene rubber is preferably 30 parts by mass or less per 100 parts by mass of the rubber component. With this configuration, the fatigue resistance and wear resistance after vulcanization can be improved while maintaining the mixing property with other rubber components such as diene rubber and the workability during kneading. This is because the elastic modulus after vulcanization can be further increased.

  In the rubber composition for a rubber crawler of the present invention, the mass blending ratio of the diene rubber and the high styrene rubber (diene rubber / high styrene rubber) is preferably 95/5 to 80/20. By adopting this configuration, while maintaining mixing with other rubber components such as diene rubber, workability during kneading, elongation at break after vulcanization, tensile strength and tearing force, This is because the fatigue resistance and wear resistance of can be improved.

  In the rubber composition for a rubber crawler of the present invention, the styrene content of the high styrene rubber is preferably 60 to 70% by mass. By adopting this configuration, while increasing the elastic modulus after vulcanization, mixing with other rubber components such as diene rubber, workability at the time of kneading, elongation at break after vulcanization, tensile strength and This is because the tearing force can be maintained.

  The rubber crawler of the present invention is characterized by using the rubber composition for a rubber crawler. According to the rubber crawler of the present invention, even under high temperature conditions, the rubber elastic body exhibits a high elastic modulus, and it is possible to prevent the ear part of the rubber crawler from being caught to the ground side during turning.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition for rubber crawlers which can obtain the rubber crawler which can suppress that the ear | edge part of a rubber crawler is wound in the grounding side at the time of turning, and the time of turning are high temperature conditions. It is possible to provide a rubber crawler that can suppress the ear portion of the rubber crawler from being caught on the ground side.

Embodiments of the present invention will be described below.
The rubber composition for a rubber crawler of the present invention contains a diene rubber and a high styrene rubber as rubber components. This is because the diene rubber can be sulfur vulcanized and has excellent wear resistance after vulcanization. The diene rubber is not particularly limited, but natural rubber, synthetic isoprene rubber, butadiene rubber, styrene-butadiene copolymer rubber (SBR) having a styrene content of less than 50% by mass, and styrene-isoprene having a styrene content of less than 50% by mass. Examples thereof include copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, styrene-butylene copolymer rubber having a styrene content of less than 50% by mass, and styrene-chloroprene copolymer rubber having a styrene content of less than 50% by mass. A diene rubber may be used individually by 1 type, and may be used in combination of 2 or more type.

  The rubber composition for a rubber crawler of the present invention includes a high styrene rubber in addition to a diene rubber, thereby increasing the elastic modulus after vulcanization, so that the rubber crawler can be used under a wide range of temperature conditions, particularly high temperature conditions. It is possible to suppress the ear portion of the rubber crawler from being caught on the ground side during turning. The high styrene rubber is a rubber having a styrene content of 50% by mass or more. For example, a styrene-butadiene copolymer rubber having a styrene content of 50% by mass or more, a styrene-isoprene copolymer rubber having a styrene content of 50% by mass or more, Examples thereof include a styrene-butylene copolymer rubber having a styrene content of 50% by mass or more and a styrene-chloroprene copolymer rubber having a styrene content of 50% by mass or more. A high styrene rubber may be used individually by 1 type, and may be used in combination of 2 or more type.

  The high styrene rubber can be obtained, for example, by drying or coagulating with an organic acid a high styrene resin latex composed of 85 to 87% by mass of styrene and 13 to 15% by mass of butadiene. Alternatively, a high styrene resin latex composed of 85 to 87% by mass of styrene and 13 to 15% by mass of butadiene and styrene-butadiene rubber latex are uniformly mixed at a predetermined ratio and dried or using an organic acid. It can be obtained by co-coagulation. A commercially available high styrene rubber may be used and is not particularly limited. Examples thereof include JSR0061 (styrene content 67 mass%) and JSR0051 (styrene content 56%) manufactured by JSR Corporation. The high styrene rubber preferably has a styrene content of 60 to 70% by mass. It is because the elastic modulus after vulcanization can be increased when the styrene content is 60% by mass or more. Further, when the styrene content is 70% by mass or less, the mixing property with other rubber components such as diene rubber, workability at the time of kneading, elongation at break after vulcanization, tensile strength and tearing force are reduced. This is because it can be maintained.

  In the rubber composition of the present invention, the blending amount of the high styrene rubber is preferably 30 parts by mass or less per 100 parts by mass of the rubber component, and more preferably 5 to 20 parts by mass per 100 parts by mass of the rubber component. If the blending amount of the high styrene rubber is 30 parts by mass or less per 100 parts by mass of the rubber component, the mixing with other rubber components such as diene rubber and the workability at the time of kneading the rubber composition can be maintained. Further, if it is 20 parts by mass or less per 100 parts by mass of the rubber component, it is possible to maintain elongation at break, tensile strength and tearing force after vulcanization. Moreover, it is because the elasticity modulus after a vulcanization | cure can be raised further because the compounding quantity of a high styrene rubber is 5 mass parts or more per 100 mass parts of rubber components.

  In the rubber composition of the present invention, the mass blending ratio of diene rubber and high styrene rubber (diene rubber / high styrene rubber) is preferably 95/5 to 80/20. This is because, if the mass blending ratio of the high styrene rubber to the diene rubber is 5% or more, the fatigue resistance and wear resistance after vulcanization can be increased, and the elastic modulus can be further increased. Further, if the mass blending ratio of the high styrene rubber to the diene rubber is 20% or less, the miscibility with other rubber components such as diene rubber, workability during kneading, and elongation at cutting after vulcanization, This is because the tensile strength and tearing force can be maintained.

  The rubber composition of the present invention may contain only a diene rubber and a high styrene rubber as the rubber component, or may further contain a non-diene synthetic rubber usually used in the rubber composition. Such non-diene synthetic rubber is not particularly limited, and examples thereof include butyl rubber and halogenated butyl rubber. These may be used individually by 1 type and may be used in combination of 2 or more type. Further, the rubber component may include a rubber that has been modified in whole or in part by using a modifying agent such as a nitrogen-containing compound, a silicon-containing compound, or a tin-containing compound.

  The rubber composition of the present invention can contain, as a reinforcing filler, at least one filler selected from black fillers such as carbon black and white fillers such as silica and inorganic compounds. The blending amount of the reinforcing filler of the present invention is not particularly limited, and is preferably 40 to 80 parts by mass with respect to 100 parts by mass of the rubber component, although it varies depending on the type and composition of the reinforcing filler and rubber component to be used. This is because when the reinforcing filler is 40 parts by mass or more, a sufficient elastic modulus can be obtained for the rubber for a rubber crawler. Further, when the reinforcing filler is 80 mass or less, bending durability and crack resistance can be maintained, and cracks due to a decrease in bending durability or crack resistance can be prevented.

  The type of carbon black that can be used as the black filler is not particularly limited, and examples thereof include SAF, ISAF, HAF (N330), FF, FEF, GPF, SRF, CF, FT, and MT grade carbon black. . These carbon blacks may be used alone or in combination of two or more. Moreover, you may use together with a white filler.

As the white filler, silica and general formula: mM · xSiO _y · zH ₂ O (I)
[Wherein, M is selected from a metal selected from the group consisting of aluminum, magnesium, titanium, calcium and zirconium, an oxide or hydroxide of the metal, and a hydrate thereof, and a carbonate of the metal. M, x, y, and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10]. Can be mentioned. The silica is not particularly limited, and for example, wet silica, dry silica, colloidal silica, and the like can be used.

The inorganic compound of the general formula (I) is not particularly limited, but alumina (Al ₂ O ₃ ) such as γ-alumina and α-alumina; alumina monohydrate such as boehmite and diaspore (Al ₂ O _3. H ₂ O); aluminum hydroxide [Al (OH) ₃ ] such as gibbsite and bayerite; 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 ], aluminum magnesium oxide (MgO.Al ₂ O ₃ ), clay (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ · 2SiO 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 ₂ etc.), 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 ]; such as crystalline aluminosilicates containing hydrogen, alkali metals or alkaline earth metals that correct the charge, such as various zeolites. The These white fillers may be used alone or in combination of two or more.

  The rubber composition for a rubber crawler of the present invention is a compounding agent usually used in the rubber industry in addition to a reinforcing filler, such as a vulcanizing agent, a vulcanization aid, a vulcanization accelerator, a softening agent, and anti-aging. An agent, a scorch inhibitor, a processing aid, a filler modifier, a tackifier, a foaming agent, a colorant and the like can be appropriately blended depending on the purpose. The order and stage of adding these compounding agents are not particularly limited, but it is preferable to add the vulcanizing agent in the final step. Moreover, a commercial item can be used for these compounding agents.

  The rubber composition for a rubber crawler of the present invention can be obtained by kneading a rubber component containing a diene rubber and a high styrene rubber, a reinforcing filler, and a necessary compounding agent as appropriate. The kneading can be performed according to a method that is usually performed to obtain a rubber composition. For example, although not particularly limited, the rubber component is masticated as necessary using a commonly used rubber kneader such as a Banbury mixer, Brabender plastograph, roll, kneader, etc. After adding and kneading the necessary compounding agents other than the vulcanizing agent, zinc oxide, and vulcanization retardant, kneading by adding the vulcanizing agent, zinc oxide and vulcanization retardant, heat as needed. It can be manufactured by placing, extruding and the like.

  The rubber crawler of the present invention is characterized by using the rubber composition for a rubber crawler of the present invention. Using the rubber composition for a rubber crawler of the present invention manufactured as described above, the rubber crawler of the present invention can be manufactured according to a normal rubber crawler manufacturing method. Although not particularly limited, for example, the rubber composition for a rubber crawler of the present invention is placed in a heating mold for a rubber crawler, and a steel cord or a core metal is embedded as necessary, and is heated and vulcanized at a necessary temperature as appropriate. Thus, the rubber composition can be cured to produce the rubber crawler of the present invention.

  The rubber composition for a rubber crawler of the present invention is not particularly limited, but dynamic storage elasticity after vulcanization measured at a frequency of 10 Hz and an amplitude of 2% using a viscoelastic spectrometer in accordance with JIS K6394: 2007. The rate (E ′) is preferably 8 to 13 MPa under a temperature condition of 23 ° C., and preferably 5 to 7 Pa under a temperature condition of 80 ° C. When the dynamic storage elastic modulus (E ′) under a temperature condition of 23 ° C. is 8 MPa or more, the elastic crawler has a sufficient elastic modulus under normal temperature conditions, and the rubber crawler ear at the time of turning is caught on the ground side. It is because it can suppress. On the other hand, when the dynamic storage elastic modulus (E ′) under the temperature condition of 23 ° C. is 13 MPa or less, the bending durability or the crack resistance characteristics can be satisfactorily maintained under normal temperature conditions, and cracks are generated. It is because it can prevent. Further, when the dynamic storage elastic modulus (E ′) under a temperature condition of 80 ° C. is 5 MPa or more, the rubber has a sufficient elastic modulus even under a high temperature condition such as when asphalt pavement, and rubber during turning This is because the crawler ears can be prevented from being caught on the grounding side. On the other hand, when the dynamic storage elastic modulus (E ′) under a temperature condition of 80 ° C. is 7 MPa or less, the bending durability or crack resistance can be maintained well even under a high temperature condition, and cracks are generated. It is because it can prevent.

  Further, the rubber composition for a rubber crawler of the present invention is not particularly limited, but preferably 100% modulus (Md100) after vulcanization measured according to JIS K6251: 2007 is 23 ° C. It is 2.6 MPa or more, more preferably 2.8 to 4.5 MPa. When the 100% modulus (Md100) at a temperature of 23 ° C. is 2.6 MPa or more, the elastic modulus is sufficient to prevent the rubber crawler ears from being caught on the ground side during turning under normal temperature conditions. This is because the effect can be further enhanced when the pressure is 2.8 MPa or more. On the other hand, when the 100% modulus (Md100) under the temperature condition of 23 ° C. is 4.5 MPa or less, the bending durability or the crack resistance can be favorably maintained, and the generation of cracks can be prevented. Because.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, these do not limit the scope of the present invention.

  The rubber compositions of Examples and Comparative Examples were prepared with the formulations shown in Table 1 below, and (1) Mooney viscosity, (2) Tensile properties (elongation at break, tensile strength, 100% modulus) according to the method shown below. ), (3) tearing force, (4) wear resistance, (5) fatigue resistance, (6) dynamic storage modulus (E '), and (7) amount of entrainment during turning.

(1) Mooney viscosity In accordance with JIS K6300-2: 2001, a Mooney viscosity test was performed on an unvulcanized rubber composition. The Mooney viscosity [ML1 + 4 (127 ° C.)] was measured at 127 ° C. using a rotorless Mooney viscometer (rotorless Mooney viscometer manufactured by Toyo Seiki Co., Ltd.) without a rotating disk. Table 1 shows the measured values. The smaller the measured value, the better the flowability of the unvulcanized rubber composition and the better the workability.

(2) Tensile properties After the rubber composition was vulcanized and cured at 155 ° C. for 30 minutes, a dumbbell-shaped JIS No. 3 test piece was prepared in accordance with JIS K6251: 2007, and a tensile tester (Oriente Co., Ltd.) was produced. Tensilon RTC-1225 (manufactured by Kusha) was used to measure elongation at break (Eb), tensile strength (Tb), and 100% modulus (Md100) at 23 ° C. Table 1 shows the measured values.

(3) Tear force After the rubber composition was vulcanized and cured at 155 ° C. for 30 minutes, a trouser-type tear test piece having a thickness of 2.0 ± 0.2 mm was prepared in accordance with JIS K6252: 2007. The tearing force was measured. In Table 1, the reciprocal number of the actual measurement value of Comparative Example 1 is set to 100, and the reciprocal number of the actual measurement value of the other Comparative Examples and Examples is displayed as an index. The larger the index value, the better the tearing force.

(4) Abrasion resistance After the rubber composition was vulcanized and cured at 155 ° C. for 30 minutes, a DIN abrasion test was performed in accordance with JIS K6264: 2007 (DIN abrasion tester: DIN abrasion tester manufactured by Toyo Seiki Co., Ltd.) ), The amount of wear was measured. In Table 1, the actual measurement values of Comparative Example 1 were set to 100, and the actual measurement values of other Comparative Examples and Examples were displayed as indices. The larger the index value, the smaller the wear amount and the better the wear resistance.

(5) Fatigue resistance After the rubber composition was vulcanized and cured at 155 ° C. for 30 minutes, a demacha-type flex crack growth test was conducted in accordance with JIS K6260: 2007 (Demacha-type flex tester: manufactured by Ueshima Seisakusho Dematcher bending tester FT-1500), and the crack length was measured. In Table 1, the actual measurement values of Comparative Example 1 were set to 100, and the actual measurement values of other Comparative Examples and Examples were displayed as indices. The larger the index value, the shorter the crack length and the better the fatigue resistance.

(6) Dynamic storage elastic modulus (E ')
After the rubber composition was vulcanized and cured at 155 ° C. for 30 minutes, a test piece having a length of 50 mm × width of 5 mm × thickness of 2.0 mm was produced. About this test piece, in accordance with JIS K6394: 2007, using a viscoelastic spectrometer (automatic viscoelasticity analyzer manufactured by Ueshima Seisakusho Co., Ltd.) at a frequency of 10 Hz and an amplitude of 2% at 23 ° C. and 80 ° C. The dynamic storage elastic modulus (E ′) was measured. In Table 1, the actual measurement values of Comparative Example 1 were set to 100, and the actual measurement values of other Comparative Examples and Examples were displayed as indices. The higher the index value is, the harder it is, and it is possible to suppress the rubber crawler ear portion from being caught on the ground side during turning.

(7) Entrainment amount during turning The rubber composition is placed in a heating mold for a rubber crawler, 37 steel cords are embedded along the circumferential direction of the crawler, and the rubber composition is heated at 160 ° C. for 60 minutes. Was vulcanized and cured to produce a rubber crawler of 280 × 47 × 117.5 size. This rubber crawler was attached to the right foot of a mini hydraulic excavator (CAT305CCR manufactured by Caterpillar) and pivoted 90 °. The amount of entrainment during turning was measured by measuring the length from the crawler contact surface to the maximum entrainment portion. Table 1 shows the measured value at 23 ° C. of Comparative Example 1 as 100, the measured value at 80 ° C. of Comparative Example 1 and the measured values at 23 ° C. and 80 ° C. of other Comparative Examples and Examples as indices. did. The lower the index value, the more the rubber crawler ears can be prevented from being caught on the grounding side during turning.

* 1: JSR 0061 manufactured by JSR (styrene content 67% by mass)
* 2: JSR 0202 manufactured by JSR (styrene content 46% by mass)
* 3: JSR BR01 manufactured by JSR
* 4: JSR RB820 made by JSR
* 5: Asahi Carbon HAF (Asahi # 70)
* 6: 2,2,4-trimethyl-1,2-dihydroquinoline polymer (Nocrack 224 manufactured by Ouchi Shinsei Chemical Industry)
* 7: N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine (Nouchi 6C manufactured by Ouchi Shinsei Chemical Industry)
* 8: N-tert-butyl-2-benzothiazolylsulfenamide (Noxeller NS-P manufactured by Ouchi Shinsei Chemical Industry)
* 9: N-cyclohexylthiophthalimide (retarder-CTP manufactured by Ouchi Shinsei Chemical Industry)

  From the results shown in Table 1, the rubber composition for rubber crawlers according to the present invention can be obtained after vulcanization while maintaining workability in an unvulcanized state, elongation at break after vulcanization, tensile strength, and tearing force. It can be seen that it has excellent wear resistance and fatigue resistance and exhibits a high elastic modulus from room temperature to high temperature. In other words, the rubber crawler of the present invention manufactured using the rubber composition for a rubber crawler of the present invention has a high elastic modulus even under high temperature conditions, Entrainment to the ground side can be suppressed.

  The rubber composition for a rubber crawler of the present invention can be used for a rubber elastic body of a rubber crawler or a lug portion of a rubber crawler. Further, the rubber crawler of the present invention can be used for traveling parts such as civil engineering and construction machines, industrial machines, and agricultural machines, and particularly preferably used for the traveling parts of the machinery that can be used under high temperature conditions. be able to.

Claims (5)

A rubber composition for a rubber crawler comprising a diene rubber excluding SBR and a high styrene rubber having a styrene content of 50% by mass or more as a rubber component.   2. The rubber composition for a rubber crawler according to claim 1, wherein the blending amount of the high styrene rubber is 30 parts by mass or less per 100 parts by mass of the rubber component.   The rubber crawler according to claim 1 or 2, wherein a mass blending ratio of the diene rubber and the high styrene rubber (diene rubber / high styrene rubber) is 95/5 to 80/20. Rubber composition.   The rubber composition for a rubber crawler according to any one of claims 1 to 3, wherein the high styrene rubber has a styrene content of 60 to 70 mass%.   A rubber crawler using the rubber composition for a rubber crawler according to any one of claims 1 to 4.