JP2733430B2 - Tire for tire roller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire for a tire roller capable of maintaining a substantially constant tread contact pressure from the beginning to the end of use.

[0002]

2. Description of the Related Art For example, in the secondary rolling work of asphalt pavement work, a so-called tire roller is often used, and the radius of curvature of a tread surface is extremely increased in order to finish a road surface smoothly. A large pneumatic tire is used. Also in this kind of tire,
In order to prevent asphalt from adhering to the tread surface during rolling, light oil is sprayed on the tread portion. Therefore, the tread portion is generally made of styrene-butadiene rubber (SBR) having excellent oil resistance. Is formed.

[0003]

However, even when styrene-butadiene rubber (SBR) is used, the light oil is absorbed into the rubber by repeated light oil spraying. As a result, as shown in FIG. 4, the tread shoulder region K1 on the tread end side is shifted to the inner tread central region K.
In this case, there is a problem that the swelling unevenly occurs as compared with No. 2, and two concave marks are formed on the rolling compaction path surface.

Accordingly, the present inventors have studied on the unevenness of the swelling. As a result, it was found that the unevenness of the swelling was greatly affected by the absorption of light oil from the buttress surface, in addition to the difference in rubber gauge thickness between the tread shoulder region K1 and the tread central region K2. In addition to reducing rubber swelling due to light oil from the buttress surface, by making the tread central region K2 reversely swellable with the rubber composition and rubber thickness with respect to the tread shoulder region K1, the concave marks can be effectively reduced. It was found that it could be reduced.

That is, according to the present invention, the cap rubber layer for forming the tread surface is made of a rubber composition having a relatively high volume expansion coefficient to light oil, and the rubber thickness of the cap rubber layer gradually increases from the equatorial plane of the tire toward the tread edge. It is an object of the present invention to provide a tire for a tire roller that can solve the above-described problem on the basis of a lighter tire.

[0006]

In order to achieve the above object, a tire for a tire roller according to the present invention comprises a tread portion having a cap rubber layer forming a tread surface, and a carcass radially inside the cap rubber layer. The cap rubber layer is formed of a rubber composition containing 50 parts by weight or more of natural rubber in 100 parts by weight of raw rubber, and has a rubber thickness on the equatorial plane of the tire. Is thickest and gradually diminishes toward both tread edges, and the thickness at the tread edge is zero or 1 / th of the thickness at the tire equatorial plane.
The thickness is 2 or less.

[0007] The raw rubber for the base rubber layer is preferably composed of a rubber composition containing 100 parts by weight of synthetic rubber.

[0008]

The cap rubber layer for forming the tread surface is made of a rubber composition containing 50 parts by weight or more of natural rubber in 100 parts by weight of raw rubber, and a base rubber layer is provided inside.
Therefore, the same scratch resistance and wear resistance as those of the conventional tire can be imparted to the tread surface, and the tire durability can be maintained.

In addition, since the cap rubber layer having a high volume expansion coefficient with respect to light oil is formed thickest on the equatorial plane of the tire, the cap rubber layer bulges more on the equatorial plane of the tire, and the bulge at the end of the tread is increased. The amount of protrusion can be balanced and the amount of rubber swelling can be made uniform over the entire tread surface, and the contact pressure can be kept uniform.

[0010] The light oil absorbed from the buttress surface decreases as its permeation rate moves away from the buttress surface, and a base rubber layer having a low volume expansion coefficient is formed along the buttress surface along the distribution of such permeation rate. It has a triangular cross section. As a result, bulging radially outward in the tread shoulder region can be suppressed, and the contact pressure can be maintained uniformly throughout the end of use.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. In the figure, a tire 1 for a tire roller includes a carcass 6 having a bias structure that is folded around a bead core 5 of a bead portion 4 from a tread portion 2 to a sidewall portion 3, and inside the carcass 6, A tube is provided to keep the filling air tight.

The carcass 6 is formed from a plurality of carcass plies in which carcass cords are arranged at an angle of 30 to 50 degrees with respect to the tire equator C.
The carcass cords are arranged in different directions as if they cross each other between plies.

The carcass 6 swells to a substantially circular shape approximating a natural cross-sectional shape due to a high filling internal pressure of 2.4 kgf / cm ² or more. It bends in a range of 0.5 to 0.6 times.

In the present embodiment, the tread portion 2 has a tread width WT substantially equal to the carcass width W6, and the tread surface S, which is the outer surface in the radial direction, has, for example, the curvature radius R6.
And has a radius of curvature RT that is at least five times larger than the radius of curvature RT.

The tread portion 2 includes a cap rubber layer 10 whose outer surface forms a tread surface S by being located outside the tire in the radial direction, and a base rubber layer 11 disposed radially inside the tread portion S. The cap rubber layer 10 is at least 50% and 70% of the total thickness T of the tread on the equatorial plane of the tire.
It has a rubber thickness Tc in the following range, and gradually becomes thinner as it approaches both tread ends e. At the tread end e, the thickness is in the range of 0 to 0.5 times the rubber thickness Tc.
The base rubber layer 11 has a tread shoulder region Y between the vicinity of the tread end e and a position P1 separated from the vicinity of the tread end e by a distance L that is １ ／ times the tread width WT.
It has the shape extending the thickest in O and extending radially inward along the buttress surface BS.

Accordingly, the tread portion 2 has a two-layer structure in which the cap rubber layer 10 is made thinner and the base rubber layer 11 is made thicker in the tread shoulder region YO in this example, and the tread in the tire axial direction inward. In the central region YI, the cap rubber layer 10 and the base rubber layer 11 form a two-layer structure having substantially the same thickness, and the cap rubber layer 10 is made of a rubber composition having a relatively high volume expansion coefficient, for example, 50 parts by weight of natural rubber. By forming from the rubber composition containing the above, the scratch resistance and abrasion resistance of the tread surface S can be maintained substantially equal to the conventional tire. Further, the base rubber layer 11 is made of a synthetic rubber having a relatively small volume expansion coefficient, for example, a rubber composition containing 100 parts by weight of SBR as a raw rubber, and in this example, in order to maintain trauma resistance or the like on the buttress surface BS, The outer surface 11b of the base rubber layer 11 in the tire axial direction is, for example, NRS.
It is covered with a sidewall rubber 12 made of BR.

In the present invention, the base rubber layer 11
Is formed of a rubber composition having a low volume expansion coefficient with respect to light oil, wherein the volume expansion coefficient when immersed in light oil at a temperature of 23 ± 2 ° C. for 1 hour is 8% or less. The volume expansion rate test was performed at the test temperature and the time other than the time of immersion in light oil.
According to the volume change test of SK6301 12, 5 and 2.

It is known that the volume expansion, ie, swelling, of a rubber with respect to a solvent is greatly affected by the type of the solvent, the type of the rubber, the crosslinking density, and the like.
The items No. to No. 4 are specified by JIS. However, they use the same main component of hydrocarbons, so that any of the light oils can be used to perform the volume expansion measurement.

It is known that the volume expansion can be suppressed by increasing the crosslink density. However, if the crosslink density is excessively increased, the rubber hardens, loses its elasticity and deteriorates the tire performance. Therefore, in this example, the expansion coefficient was 8 by using a rubber composition having low affinity for light oil.
Set to less than%.

That is, in general, the square root of the heat of evaporation per mole of a substance divided by its volume is referred to as SP (Soluub).
As shown in Table 1, for example, when the SP values of the polymer and the solvent are close to each other, the affinity increases. Accordingly, rubber compositions such as acrylonitrile-butadiene rubber (N) which are higher than the SP value of SBR and deviate from the SP values of isooctane and toluene
BR) alone or a mixture thereof with SBR or the like is used for the base rubber layer 11.

[0021]

[Table 1]

In addition to NBR, for example, oil-extended SBR (OE
P) can also be suitably used as the rubber B for the base rubber layer 11 having a low volume expansion. Table 2 shows an example of the components of the rubber B at this time together with the components of the rubber A for the cap rubber layer 10. FIG. 2 shows the relationship between the volume expansion coefficients of these rubbers A and B with respect to light oil and the immersion time.

[0023]

[Table 2]

Since the base rubber layer 11 is made of a rubber composition having a low volume expansion coefficient, the volume expansion is reduced even when light oil is absorbed from both the tread surface S and the buttress surface BS. I do. In particular, the permeability of light oil absorbed from the buttress surface BS gradually decreases as the distance from the buttress surface BS increases. Accordingly, the base rubber layer 11 has a triangular cross-section in the tread shoulder region YO, and the height of the cross-section in the radial direction increases as approaching the tread edge e, while the cap rubber layer 10 having a relatively high volume expansion coefficient is formed in the tread central region YI. 3, the radially outward bulging of the tread surface S can be made uniform as shown in FIG. 3, and a uniform ground surface shape TS is provided over the end of use.

Here, the base rubber layer 11 may have a structure extending only in the tread shoulder region YO. The base rubber layer 11 shown in FIG. 1 extends beyond the tread shoulder region YO and further into the tread central region YI on the inside thereof, and the left and right base rubber layers 11 having a substantially triangular cross section are formed on the tire equator C. The case where they are connected to each other is shown above.

[0026]

As described above, in the tire for a tire roller of the present invention, the cap rubber layer for forming the tread surface is made of a rubber composition having a relatively high volume expansion coefficient with respect to light oil, and has a large thickness in the central region of the tread. On the other hand,
Since the base rubber layer made of the rubber composition having a low volume expansion coefficient with respect to light oil is provided, the tread contact pressure can be kept uniform even by spraying light oil during rolling work, and a smooth pavement road surface can be formed.

[Brief description of the drawings]

FIG. 1 is a meridional sectional view showing one embodiment of a tire of the present invention.

FIG. 2 is a diagram showing a relationship between a volume expansion coefficient and a soaking time for light oil.

FIG. 3 is a diagram schematically showing a bulge of a tread surface of a tire of the present invention and a shape of a tread surface thereof.

FIG. 4 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 2 Tread portion 10 Cap rubber layer 11 Base rubber layer BS Buttress surface YO Tread shoulder region S Tread surface

Claims (2)

(57) [Claims] A cap rubber layer forming a tread surface; and a base rubber layer disposed between the cap rubber layer and a carcass on a radially inner side of the cap rubber layer. The layer is made of a rubber composition containing 50 parts by weight or more of natural rubber in 100 parts by weight of the raw rubber, and the rubber thickness of the tire equatorial plane is the thickest and gradually diminishes toward both tread ends, and the thickness at the tread end is A tire for a tire roller, wherein the thickness is zero or less than half the thickness at the tire equatorial plane. 2. The raw rubber for the base rubber layer is a synthetic rubber 1
2. The tire for a tire roller according to claim 1, comprising a rubber composition in an amount of 00 parts by weight.