JP2008095073A - Rubber composition for crawler, crawler tread using it or rubber crawler with crawler base - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a crawler able to improve productivity owing to the superiority in processability and less in the degradation of physical properties with time, and to provide a crawler tread using the composition or a rubber crawler provided with a crawler base. <P>SOLUTION: The rubber composition for a crawler contains a para-benzoquinone di-imine type compound of 0.1-7.0 pts.wt. per a rubber component of 100 pts.wt. and the rubber crawler has a crawler tread or a crawler base using the rubber composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a rubber composition for a crawler and a rubber crawler having a crawler tread or a crawler base using the same.
About.

  Rubber crawlers used for excavators, tractors and the like are often left outdoors for a long time, and their running conditions are also used in extremely severe environments compared to automobile tires such as wasteland. Further, the rubber crawler has a structure that is particularly heavily loaded and easily deteriorated at the tip (bent portion) of the rubber crawler.

  As a result, the physical properties of the rubber composition deteriorate over time during storage and running, and further over time during the production of the rubber composition, so that sufficient performance can be obtained when used. There may be no.

  In addition, as mentioned above, rubber crawlers are used under conditions that require stronger cut resistance, such as traveling mainly on rough land.In addition, the crawler base is used between a wheel and a rubber when traveling on rough ground. In this case, the rubber composition for rubber crawlers is set to a high hardness because gravel enters the rubber and the rubber becomes tattered (insect erosion phenomenon). In particular, the total rubber crawler without a cored bar has a higher hardness than a rubber crawler with a cored bar (see, for example, Patent Document 1), so that the extrudability is very poor and production. Have the disadvantage of reduced performance.

JP 2005-335611 A

  INDUSTRIAL APPLICABILITY The present invention has a crawler rubber composition and a crawler tread using the crawler rubber composition, and a crawler base excellent in corrosion resistance, which can improve productivity by being excellent in processability and have little deterioration over time in physical properties. An object is to provide a rubber crawler.

  The present invention relates to a rubber composition for a crawler containing 0.1 to 7.0 parts by weight of a parabenzoquinone diimine-based compound with respect to 100 parts by weight of a rubber component.

  The present invention also relates to a rubber crawler having a crawler tread using the rubber composition for crawlers.

  The present invention also relates to a rubber crawler having a crawler base using the rubber composition for crawlers.

  According to the present invention, by containing a predetermined amount of a rubber component and a parabenzoquinone diimine compound, a rubber composition for a crawler having excellent processability, improved productivity, and little physical deterioration over time, and the use thereof A rubber crawler having a conventional crawler tread or crawler base can be provided.

  The rubber composition for a crawler of the present invention contains a rubber component and a parabenzoquinone diimine compound.

  The rubber component is not particularly limited. For example, natural rubber (NR), isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), butyl rubber (IIR), halogenated butyl rubber (X-IIR) Acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), ethylene propylene diene rubber (EPDM), halides of copolymers of isomonoolefin and paraalkyl styrene, etc. These rubber components are used alone. You may use it in combination of 2 or more types. Among these, SBR is preferable when used for a crawler tread of a rubber crawler that is often used in wasteland or the like because cut resistance is required. In addition, when used for a crawler base, SBR is preferred to obtain resistance to cutting by pebbles or the like that have entered between the wheel and rubber, and NR is blended to maintain adhesion to the core metal. It is preferable to use NR and SBR in combination.

  When NR and SBR are used in combination, the rubber component preferably contains NR at 40% by weight or more, more preferably 50% by weight or more, in order to obtain sufficient adhesion to the core metal. preferable. Further, from the reason that sufficient cut resistance can be obtained, the rubber component preferably contains NR of 80% by weight or less, and more preferably 70% by weight or less.

  When NR and SBR are used in combination, the rubber component preferably contains 20% by weight or more, and more preferably 30% by weight or more, because sufficient cut resistance can be obtained. Moreover, it is preferable to contain SBR 60 weight% or less in a rubber component from the reason that sufficient adhesive force with a metal core is obtained, and it is more preferable to contain 50 weight% or less.

  The parabenzoquinone diimine compound used in the present invention is blended as an anti-aging agent. By containing the parabenzoquinone diimine-based compound, deterioration of physical properties of the rubber composition with time can be suppressed, and the performance as a crawler tread or a crawler base can be maintained over a long period of time. Moreover, since the viscosity of a rubber composition is reduced and it is excellent in extrusion processability, the effect that productivity improves is also acquired.

  Specific examples of the parabenzoquinone diimine compound include N- (methylethyl) -N′-phenylquinone diimine, N- (1,3-dimethylbutyl) -N′-phenylquinone diimine, and the like. It is done. Among these, N- (1,3-dimethylbutyl) -N′-phenylquinonediimine is preferable because it can be stably supplied.

  When the rubber composition for a crawler of the present invention is used for a crawler tread, the content of the parabenzoquinone diimine-based compound is sufficient because the content is sufficient and the deterioration suppressing performance is sufficiently exhibited. The amount is 0.1 parts by weight or more, preferably 0.5 parts by weight or more with respect to parts by weight. Further, the content of the parabenzoquinone diimine-based compound is 7.0 parts by weight or less, preferably 5.0 parts by weight with respect to 100 parts by weight of the rubber component from the viewpoint that exudation and product discoloration are suppressed. Less than parts by weight.

  Further, when the rubber composition for a crawler of the present invention is used for a crawler base, the content of the parabenzoquinone diimine compound is based on 100 parts by weight of the rubber component because a sufficient deterioration suppressing effect can be obtained. 0.1 parts by weight or more, preferably 0.5 parts by weight or more, more preferably 1.0 parts by weight or more. Further, the content of the parabenzoquinone diimine-based compound is 7.0 parts by weight or less, preferably 5 parts by weight or less with respect to 100 parts by weight of the rubber component, because discoloration of the product is sufficiently suppressed.

  In the present invention, an anti-aging agent such as a phenylenediamine type conventionally used in the tire industry may be used in combination with the parabenzoquinone diimine type compound.

  When using an anti-aging agent other than a parabenzoquinone diimine compound, the content of the anti-aging agent other than the parabenzoquinone diimine compound is sufficient, and the anti-aging effect is sufficiently exerted. Therefore, 0.1 part by weight or more is preferable with respect to 100 parts by weight of the rubber component, and 0.5 part by weight or more is more preferable. In addition, the content of the anti-aging agent other than the parabenzoquinone diimine compound is preferably 7 parts by weight or less, and more preferably 5 parts by weight or less, for the reason that exudation to the outside and product discoloration are suppressed.

  The rubber composition for crawlers of the present invention can further contain carbon black.

  There is no restriction | limiting in particular as carbon black, SAF, ISAF, HAF, FEF, GPF etc. which are conventionally used in the tire industry can be used.

  The content of carbon black is 40 parts by weight or more because the rubber hardness is high and the rubber strength is strong and sufficient cut resistance and wear resistance are obtained with respect to 100 parts by weight of the rubber component. Preferably, 50 parts by weight or more is more preferable. Further, the content of carbon black is preferably 100 parts by weight or less, more preferably 80 parts by weight or less, with respect to 100 parts by weight of the rubber component, from the viewpoint of good rubber elongation performance and excellent crack growth resistance. .

  The rubber composition for crawlers of this invention can contain sulfur further.

  Examples of sulfur include oil-free sulfur and oil-extended insoluble sulfur, but there is no particular limitation.

  The sulfur content is preferably 0.5 parts by weight or more and more preferably 0.7 parts by weight or more with respect to 100 parts by weight of the rubber component from the viewpoint that sufficient rubber hardness can be obtained. Further, the sulfur content is preferably 4 parts by weight or less, more preferably 3 parts by weight or less, from the viewpoint of suppressing rubber aging and maintaining rubber strength.

  The rubber composition for a crawler of the present invention is a compound conventionally used in the tire industry in addition to the rubber component, parabenzoquinone diimine compound, anti-aging agent other than parabenzoquinone diimine compound, carbon black and sulfur. Agents such as process oil, wax, stearic acid, zinc oxide, various vulcanization accelerators and the like can be appropriately blended as necessary.

  When the rubber composition for a crawler of the present invention is used for a crawler base, it is preferable not to contain a process oil because the wear resistance is inferior particularly when the use conditions are severe.

  When the rubber composition for a crawler of the present invention is used for a crawler tread, the JIS-A hardness at 25 ° C. is preferably 55 or more from the viewpoint that the cut resistance required for the rubber crawler can be sufficiently improved. 60 or more. Moreover, when using the rubber composition for crawlers of this invention for a crawler tread, it is preferable that JIS-A hardness in 25 degreeC is 90 or less from the point that it is excellent in crack growth resistance, and is 85 or less. Is more preferable.

When the rubber composition for a crawler of the present invention is used for a crawler base, the JIS-A hardness at 25 ° C. is preferably 60 or more because the cut resistance and the wear resistance are sufficiently obtained. More preferably, it is 65 or more. Moreover, when using the rubber composition for crawlers of this invention for a crawler base, it is preferable that JIS-A hardness in 25 degreeC is 90 or less from the reason that it is excellent in crack growth resistance, and is 85 or less. Is more preferable.

  Using the rubber composition for a crawler of the present invention, the rubber crawler of the present invention can be produced by an ordinary method. That is, if necessary, an unvulcanized rubber composition to which the above compounding agent has been added is extruded according to the shape of the crawler tread or the crawler base, bonded to other rubber crawler members, and unextruded on a rubber crawler molding machine. Form a vulcanized rubber crawler. The rubber crawler of the present invention can be manufactured by heating and pressing the unvulcanized rubber crawler in a vulcanizer.

  In general, a rubber crawler is made of a rubber composition, is formed in an endless shape, and has a running lug on an outer peripheral surface. In addition, the rubber crawler of the present invention is further provided with a friction reducing member on both sides in the width direction of the rubber crawler body, a core bar embedded in the longitudinal direction of the crawler, and a tensile wire on the lug side. May be.

  The rubber crawler of the present invention is suitably used for excavators, tractors, combines, truck loaders and the like.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Natural rubber (NR): NR made in Indonesia
Styrene butadiene rubber (SBR): SBR1502 (trade name) manufactured by Sumitomo Chemical Co., Ltd.
Carbon Black: Dia Black I (N220) (trade name) manufactured by Mitsubishi Chemical Corporation
Process oil: Diana Process AH-24 (trade name) manufactured by Idemitsu Kosan Co., Ltd.
Wax: Sunnock wax (trade name) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Anti-aging agent 6C: Antigen 6C (trade name) manufactured by Sumitomo Chemical Co., Ltd. (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine)
Parabenzoquinone diimine compound: Q-FLEX QDI (trade name) manufactured by Flexis (N- (1,3-dimethylbutyl) -N′-phenylquinone diimine)
Stearic acid: Stearic acid “Kashi” (trade name) manufactured by Nippon Oil & Fats Co., Ltd.
Zinc oxide: Ginbae R (trade name) manufactured by Toho Zinc Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Noxeller NS (trade name) (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples 1-12 and Comparative Examples 1-6
In accordance with the formulation shown in Tables 1 and 2, chemicals other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 165 ° C. using a Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 3 minutes at 100 ° C. using an open roll to obtain an unvulcanized rubber composition. Furthermore, the obtained unvulcanized rubber composition was press-vulcanized for 30 minutes under the condition of 150 ° C. to prepare vulcanized rubber compositions of Examples 1 to 12 and Comparative Examples 1 to 6.

(Processability)
A test piece of a predetermined size was prepared from the unvulcanized rubber composition and heated by preheating for 1 minute using a Mooney viscosity tester according to JIS K 6300 “Testing method for unvulcanized rubber”. Under the temperature condition of 130 ° C., the small rotor was rotated, and the Mooney viscosity (ML _{1 + 4} , 130 ° C.) after 4 minutes was measured, and Examples 1 to 5 and Comparative Examples 1 to 3 were comparative examples. The Mooney viscosity index of 1 was designated as the Mooney viscosity index of Comparative Examples 4 in Examples 6-12 and Comparative Examples 4-6, and the Mooney viscosity of each formulation was indicated by the following formula. In addition, it shows that Mooney viscosity is so small that Mooney viscosity index is large and it is excellent in workability.
(Mooney viscosity index) = (Mooney viscosity of Comparative Example 1)
÷ (Mooney viscosity of each formulation) x 100

(Viscoelasticity test)
Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd., loss tangent tan δ (pre-aging tan δ) of the vulcanized rubber composition at 70 ° C. under conditions of initial strain 10%, dynamic strain 2%, and vibration frequency 10 Hz. Was measured. Next, the vulcanized rubber composition was aged at 70 ° C. for 4 days. The loss tangent tan δ (tan δ after aging) was measured using the aged vulcanized rubber composition in the same manner as the vulcanized rubber composition before aging. And using these, the tan-delta change rate of each compounding was computed with the following formula. Note that the closer the tan δ change rate is to 100, the smaller the change in physical properties, which is preferable.
(Tan δ change rate) = (tan δ after aging) / (tan δ before aging) × 100

(Property index)
A rubber test piece collected from the vulcanized rubber composition was subjected to a tensile test using a No. 3 dumbbell according to JIS K6251. Next, the vulcanized rubber composition was aged at 80 ° C. for 7 days. Using the aged vulcanized rubber composition, the elongation at break was measured in the same manner as the vulcanized rubber composition before aging. And using these, the physical property index | exponent of each mixing | blending was computed with the following formula. The closer this physical property index is to 100, the smaller the degree of deterioration and the better.
(Property index) = (Elongation at break after aging) / (Elongation at break before aging) × 100

(Durability)
The unvulcanized rubber composition was vulcanized to produce a rubber sample having a width of 10 cm, a length of 30 cm, and a thickness of 1 cm. Gravel was tightened on the prepared rubber sample, and a roller loaded with 10 kg was continuously run for 12 hours at a speed of 5 cm / sec. The magnitude of damage that occurred in the rubber sample was measured, the damage of the rubber sample of Comparative Example 1 was taken as 100, and the durability performance of each compound was displayed as an index. The larger the index, the smaller the scratch and the better the durability.

  The evaluation results are shown in Tables 1 and 2.

  Comparative Example 1 is a conventional rubber composition for crawler treads that does not contain a parabenzoquinone diimine compound.

  Comparative Example 4 is a conventional rubber composition for crawler bases that does not contain a parabenzoquinone diimine compound.

  In Examples 1 to 12 containing a predetermined amount of a parabenzoquinone diimine compound, processability was improved and deterioration of rubber physical properties could be suppressed.

  On the other hand, in Comparative Example 2 and Comparative Example 5 in which the content of the parabenzoquinone diimine compound is small, the effect of suppressing the deterioration of rubber physical properties was not sufficiently obtained.

  Moreover, in Comparative Example 3 and Comparative Example 6 in which the content of the parabenzoquinone diimine compound was large, the rubber physical properties were easily deteriorated, and the processability was also deteriorated.

Claims (3)

For 100 parts by weight of rubber component,
A rubber composition for crawlers containing 0.1 to 7.0 parts by weight of a parabenzoquinone diimine compound. A rubber crawler having a crawler tread comprising the rubber composition according to claim 1. A rubber crawler having a crawler base comprising the rubber composition according to claim 1.