JP2882905B2 - Endless crawler track - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white endless crawler track containing no carbon black, among endless crawler tracks for crawlers used in construction machines and the like.

[0002]

2. Description of the Related Art Rubber materials used for endless crawler tracks for crawlers are required to have properties such as weather resistance and bending resistance, durability, and crack resistance, depending on the conditions of use of the crawlers.
To meet these requirements, the crawler endless track
Generally, a black rubber material obtained by blending carbon black with a diene rubber is used.

However, with the increase in urban construction in recent years, crawlers often travel on roads such as cobblestones, tiled grounds, brick sites, or appropriately colored concrete. There is a problem that black marks remain. For this reason, endless crawler tracks for crawlers made of a white rubber material mixed with a white filler tend to be used favorably for crawlers traveling on a road surface such as a tiled ground, instead of carbon black.

[0004]

However, an endless crawler belt for crawlers made of a white rubber material cannot expect an excellent light shielding effect of carbon black. In addition, amine-based antioxidants having excellent antiaging effects are themselves colored and cannot be used for white rubber materials because they are further colored when oxidized by light or ozone. For this reason, a large amount of a phenolic antioxidant and a wax are added to the white rubber material in place of the amine antioxidant. No anti-aging effect is obtained. Therefore, if the crawler endless crawler made of white rubber material is stored outdoors for a long period of time, it will be degraded by ozone, light, etc.
There is a problem that cracks occur on the endless crawler belt surface.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an endless crawler belt for a crawler which is a white rubber crawler and has excellent weather resistance.

[0006]

An endless crawler belt for a crawler according to the present invention comprises a crawler belt body made of a rubber material mainly composed of a diene rubber to which a white filler is added, and a crawler belt body formed on the surface of the crawler belt body. An endless crawler track for a crawler comprising a coated layer, wherein the coating layer comprises 20 to 40 parts by weight of EPDM and 60 to 80 parts by weight of a diene rubber.
It is made of a rubber material containing 0 parts by weight, and the thickness of the coating layer is 0.5 to 5 mm.

[0007]

The covering layer constituting the surface of the endless crawler according to the present invention is:
20-40 EPDM stable against heat, light, ozone, etc.
Since it contains a rubber component blended by weight, it has excellent weather resistance. Therefore, although the crawler belt main body is made of a white rubber material having poor weather resistance, the endless crawler belt has weather resistance and can withstand long-term outdoor storage.

On the other hand, the EPDM-containing rubber material constituting the covering layer is inferior to the Cien rubber material constituting the crawler belt main body in terms of strength, but the thickness of the covering layer is 0.5 to 0.5%.
By setting it to 5 mm, the strength of the crawler endless crawler belt does not need to be reduced.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of an endless crawler belt for a crawler according to an embodiment of the present invention. In FIG. 1, an endless crawler belt 1 for a crawler includes a crawler belt main body 2 and a coating layer 3 formed on a tread surface of the crawler belt main body 2.

The crawler belt body 2 is made of a rubber material mainly composed of a diene rubber to which a white filler such as white carbon is added. Examples of the diene rubber include natural rubber (abbreviated as NR) and styrene butadiene rubber (SBR) which have an unsaturated bond in the main chain and are excellent in strength.
, Nitrile rubber (abbreviated as NBR), butadiene rubber (abbreviated as BR), and the like, and mixtures thereof.

The coating layer 3 comprises a rubber component 10 consisting of 20 to 40 parts by weight of EPDM and 60 to 80 parts by weight of a diene rubber.
It is composed of a rubber material in which additives such as a white filler, a softening agent, a vulcanizing agent, and a vulcanization accelerator are appropriately added to 0 parts by weight. The diene rubber in the rubber material constituting the coating layer 3 includes:
The same rubber as the diene rubber constituting the crawler belt main body 2 can be used.

EPDM is a terpolymer of ethylene, propylene and a small amount of a diene component such as hexadiene, and is a rubber having no unsaturated bond in the main chain, such as a diene rubber. EPDM is blended to impart weather resistance to the rubber material, and the type thereof is not particularly limited.
Those having about 30 are preferred. The content of EPDM with respect to 100 parts by weight of the rubber component is 20 to 40 parts by weight, preferably 30 to 35 parts by weight. EPDM content of 20
If the amount is less than the weight part, improvement of weather resistance by EPDM cannot be expected. On the other hand, when the content of EPDM exceeds 40 parts by weight, the content of the diene rubber in the rubber component becomes relatively small, so that the adhesion to the crawler belt body 2 is reduced.

The covering layer 3 is formed on the surface of the crawler belt main body 2 by the EP.
It is formed by flowing and vulcanizing and molding a rubber material containing DM. In the vulcanization molding, the diene rubber in the rubber component constituting the covering layer 3 is bonded to the rubber material constituting the crawler belt body 2 by cross-linking.

The thickness of the coating layer 3 is 0.5 to 5 mm, preferably 1 to 3 mm. The thickness of the coating layer 3 is 0.5 mm
When the temperature is below the range, the rubber material flows during the vulcanization molding, and the thickness of the coating layer 3 is not uniform. On the other hand, the coating layer 3
When the thickness exceeds 5 mm, the rubber material containing EPDM is inferior in strength compared to the diene rubber material, so that the coating layer 3 is damaged by stones or the like and cracks during traveling on the road.

The crawler endless crawler having the above-described structure has a coating layer 3 made of a rubber material having excellent weather resistance even if the crawler belt body 2 is made of a white rubber material having poor weather resistance. Constitutes the tread surface, so that the endless crawler belt 1 has weather resistance and withstands long-term outdoor storage. In addition, since neither the crawler belt main body 2 nor the coating layer 3 contains carbon black, even when the vehicle travels on a road surface such as a tile, no black mark that impairs aesthetic appearance is left. On the other hand, the tread surface of the rubber crawler is made of a rubber material that is inferior to a rubber material mainly composed of diene rubber in terms of strength,
By setting the thickness of the coating layer 3 to 0.5 to 5 mm, the same strength as a conventional white crawler is maintained.

In this embodiment, the covering layer 3 is formed only on the tread surface of the crawler endless crawler belt. However, the present invention is not limited to this, and the entire surface of the crawler belt main body 2 is made of a rubber material containing EPDM. Coating is preferable because weather resistance can be imparted not only to the tread surface but also to the entire crawler endless crawler belt.

In this embodiment, the white endless crawler belt using white carbon as a filler is used. However, the crawler endless crawler belt of the present invention is not limited to a white crawler belt, but may be a red crawler belt.
It can also be applied to crawler endless tracks that are colored blue.

[Specific Examples] (Examples 1 to 4) The amounts of the diene rubber (NR and / or BR) and EPDM in the rubber component were adjusted within the range of 20 to 40 parts by weight as shown in Table 1.
And the following additives are blended to form the coating layer 3
Example 1 was prepared by preparing a rubber material containing EPDM,
~ 4 test pieces were prepared.

White carbon 50 parts by weight Zinc oxide 5 parts by weight Stearic acid (plasticizer) 2 parts by weight Naphthene oil 5 parts by weight CBS (vulcanization accelerator) 2 parts by weight Sulfur 1.75 parts by weight

(Examples 5 to 9) The covering layer 3 was formed on the tread surface of the crawler belt main body 2 using the rubber material of Example 2 described above. The thickness of the coating layer 3 is 0.5 to
Endless crawler tracks for crawlers of Examples 5 to 9 were prepared by changing the range as shown in Table 2 within the range of 5.0 mm.

(Comparative Examples 1 to 5) A rubber material was prepared in the same manner as in the Examples except that the amounts of the diene rubber (NR and / or BR) and EPDM were changed as shown in Table 1. Test pieces of Examples 1 to 5 were prepared. Since Comparative Example 1 did not contain EPDM, styrenated phenol and paraffin wax were added as antioxidants.

Comparative Examples 6 and 7 The covering layer 3 was formed on the tread surface of the crawler belt main body 2 using the rubber material of the above-described Example 2. The thickness of the coating layer 3 is 0.3 m
m (Comparative Example 6), an endless crawler crawler of 7.0 mm (Comparative Example 7) was prepared.

(Evaluation) (a) Ozone resistance: According to JIS K6301, a temperature of 40 ° C. and an ozone concentration of 5
The ozone deterioration test was performed on the test pieces prepared in Examples 1 to 4 and Comparative Examples 1 to 5 under the conditions of 0 pphm and an elongation of 20%. After 100 hours, the deterioration state of the test piece was observed and evaluated based on the following criteria. According to the number of generated cracks, evaluation was made in three stages from A (small number of cracks) to C (infinite number of cracks). In addition, depending on the size and depth of the crack, 1 to 5 (not visible to the naked eye, but can be confirmed with a magnifying glass of 10 times)
(Three cracks or cuts of 3 mm or more are likely to occur) 5
It was evaluated on a scale. Table 1 shows the results.

(B) Adhesive force to crawler belt main body: The test pieces prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were vulcanized and molded with the crawler belt main body test pieces, and a peel test was performed on the molded product. . The peeling force when the test piece was peeled was expressed as the adhesive force (kgf / cm) with the crawler belt main body. Table 1 shows the results
Shown in

(C) Relationship with coating layer thickness: The above-mentioned ozone deterioration test was performed to evaluate the ozone resistance of the crawler endless crawler belts prepared in Examples 5 to 9 and Comparative Examples 6 and 7. Table 2 shows the results. Further, in order to evaluate the crack resistance, the crawler equipped with the endless crawler belt for crawler was run on a grindstone, and the appearance of the tread surface of the endless crawler belt was observed after 25 hours. Table 2 shows the results.

(Evaluation results)

[Table 1]

As can be seen from Table 1, EP in the rubber component
Rubber material having a DM content of 20 to 40 parts by weight (Example 1)
4) are excellent in both ozone resistance and adhesion to the crawler belt body. On the other hand, if the content of EPDM is too large (Comparative Examples 4 and 5), the adhesion to the crawler belt body is inferior, and EPD
When the content of M is too small (Comparative Examples 1 to 3), the ozone resistance decreases.

[0028]

[Table 2]

As can be seen from Table 2, the endless crawler belt (Examples 5 to 9) in which the thickness of the coating layer falls within the range of the present invention is excellent in both ozone resistance and crack resistance. On the other hand, when the thickness of the coating layer was small (Comparative Example 6), the ozone resistance was poor, and when the thickness of the coating layer was large (Comparative Example 7), cracks were observed after running.

[0030]

According to the endless crawler belt for crawlers of the present invention, the surface covering layer is made of a rubber material containing EPDM having excellent weather resistance. It has weather resistance as an endless track. Therefore, it can withstand long-term outdoor storage. The rubber material constituting the coating layer is inferior to the rubber material containing diene rubber as a main component in strength, but the thickness of the coating layer is in the range of 0.5 to 5.0 mm. By doing so, the strength of the tread surface of the crawler endless crawler belt does not need to be reduced.

Therefore, the crawler endless crawler of the present invention is
A white crawler endless crawler belt that does not leave black marks even when traveling on a tiled ground or the like, is stable against light and ozone, and does not decrease in tread surface strength.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of an endless crawler belt for a crawler according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Endless track for crawler 2 Track body 3 Cover layer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 55/253

Claims (1)

(57) [Claims] 1. An endless crawler track for a crawler, comprising: a crawler belt main body made of a rubber material mainly composed of a diene rubber to which a white filler is added; and a coating layer formed on the surface of the crawler belt main body. The coating layer is made of a rubber material containing 100 to 40 parts by weight of a rubber component composed of 20 to 40 parts by weight of EPDM and 60 to 80 parts by weight of a diene rubber; and
An endless crawler belt for a crawler, wherein the thickness of the coating layer is 0.5 to 5 mm.