JPH02274602A - Studless tire and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the antislipping performance by dispersing powders or short fibers formed into bar-shaped particles into a tread surface layer with the particles oriented in the direction of thickness of the tread. CONSTITUTION:A rubber composite obtained by mixing a rubber composite for use on the tread of a ordinary tire with steel short fibers about 0.1mm long with average gage of about 0.01mm, and further by blending resorsinformaldehyde condensate and methylolmelamine as bonding agents, is extruded by a tread extruder 1 to form a cylindrical body 2. A rotary knife whose blade width is larger than the wall thickness t of the side wall 3 of the cylindrical body 3 is applied to the cylindrical body at about right angles to the body, and cuts off the body into a helical shape with a pitch d smaller than the wall thickness to form a strip 4 while it moves in the direction of length of the cylinder 2. The plural strips 4 are juxtaposed on the upper surface of a base tread 5 to form a trad surface layer 7. The antislipping performance can be improved by this configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a studless tire and a method for manufacturing the same.

[Conventional technology] Conventionally, so-called spiked tires used on icy roads had spikes buried in the tread surface to prevent slipping, so when this type of tire was used on regular roads, the spikes dug up the road surface. , causing dust pollution.

Therefore, today, studless tires with a large anti-slip effect are being used in order to exhibit ice-L performance without embedding spikes.

In general, studless tires have a tread made of a rubber composition that does not harden even at low temperatures, and in order to improve the anti-slip effect, the tread rubber composition contains powder with relatively large particles, especially in a shape other than spherical, which has a large anti-slip effect. A combination of these was used.

[Problems to be Solved by the Invention] However, in the tread extrusion process, these particles are oriented in the direction of decreasing extrusion resistance, that is, in the chisel direction where the extrusion direction and the length direction of the particles are the same. In tires that are extruded and molded and vulcanized using this rubber, the particles that should not have an anti-I'II effect are placed on the tread surface at right angles to the thickness direction. In other words, the particles are dispersed in an orientation along the circumferential direction of the tire, which causes problems such as a low anti-slip effect and a tendency to fall off the tread during use.

The purpose of this invention is to solve the following problems: 1. An object of the present invention is to provide a studless tire that can sufficiently exhibit an anti-slip effect and a method for manufacturing the same.

[Means for Solving the Problems] As a result of intensive studies to achieve the objective 11x, we found that a studless tire having a tread surface layer on the bottom surface of the base tread has a rod-shaped particle shape in the tread surface layer. We have developed a studless tire in which powder or short fibers with large particles are dispersed in an orientation state that is substantially the same as the thickness direction of the tread.

In manufacturing such tread rubber, rather than simply extruding a rubber composition in powder form using an extruder as in the past, relatively large particles of powder or short fibers having a rod-shaped particle shape are mixed. 1. First, the rubber composition was extruded into a cylindrical shape, and then the side wall of this extruded cylinder was
A strip is formed by cutting it spirally with a pitch length (d) smaller than the wall thickness (1) of the cylindrical body, and then this strip is placed on the -1-face of the previously extruded base thread by applying the plate in the strip. When cutting, align the cut surfaces to form one or more rows of lips 4 and 1. at least 1
We have developed a method of forming and vulcanizing tread rubber by rolling it nine times and using this.

[Effect J] Accordingly, in this manufacturing method, a gono-composition containing relatively large powder particles or short fibers having a rod-like particle shape is extruded into a cylindrical shape. The powder or short fibers are oriented in the same direction as the extrusion direction, but this cylindrical body is spirally shaped with a pitch length (d) smaller than the wall thickness (L) of the cylindrical body. In the strip formed by cutting into strips, the powder or short fibers are oriented in the thickness direction of the strip, perpendicular to the cut plane when the strip is formed. So base this strip!・If you mold and vulcanize using the tread rubber that was laminated on the surface of the red (7) to form the surface layer,
In the surface layer of the tire tread, the above-mentioned powder or short fibers are dispersed and oriented in almost the same direction as the tread thickness direction, resulting in a state similar to that of buried with minute spikes standing at right angles. .

Therefore, when these powders or short fibers are made of a material with good wear resistance, the rubber wears out first [7], resulting in fine spikes slightly protruding from the tire surface. Even if the amount of protrusion increases, the powder or short fibers are thin, so they are easily worn away, and the amount of protrusion is always constant, and since the amount is small, the asphalt road surface is rarely dug up due to elastic deformation. However, on an icy road surface, almost no elastic deformation occurs, so an anti-slip effect is produced by penetrating the icy surface. In addition, the inner end of the powder or short fiber is stuck deeply into the rubber and cannot be easily removed, so it may fall off from the 1- + knot during running.
The anti-slip effect will not disappear in a short period of time.

The gauge of powder or short fiber to be blended is 0.01~], m
The length is preferably 1.5 times the gauge.

Furthermore, it is preferable to include an adhesive for powder or short fibers in the composition. For example, when short steel fibers are used, a composition containing silica and mercaptopenzothiazyl cisulfide or mercaptobenzothiazole as a vulcanization accelerator is preferred from the viewpoint of adhesion.

[Example] Steel trout fibers with an average gauge of 0.01 mm and a length of 0.1 mm were mixed into a commonly used rubber composition for tire treads117, and a resorcinol-formaldehyde condensate and methylolmelamine were further added as adhesives. The additionally compounded rubber composition was extruded by tread extrusion (as shown in Fig. 1) (2 machines 18
A cylindrical body 2 having a cylindrical shape filled with 1511 was extruded.

Next, as shown in FIG. 1, a rotary blade (not shown) having a blade width wider than the thickness t of the side wall 3 of the cylindrical body 2 is erected almost at right angles to the cylindrical body 2. The strip 4 was formed by cutting it in a spiral shape with a pitch length d smaller than the wall thickness t of the side wall 3 while shifting it in the length direction.

Next, as shown in FIG. 2, a tread surface layer 7 was formed by arranging a plurality of strips 4 in parallel on the upper surface 6 of a base tread 5 which had been extruded in advance and had a substantially trapezoidal cross section.

Subsequently, it was assembled into a green tire and molded and vulcanized so as to cover the crown part of the carcass ply according to a conventional manufacturing method.

As a result, a tire was obtained that had a tread surface layer on the upper surface of the base tread in which short steel fibers were oriented and dispersed in substantially the same direction as the thickness direction of the tread.

When this tire was used, short steel fibers slightly protruded from the tread surface as the tread rubber wore down, and when the tire was driven on an icy road surface, they pierced the road surface and exerted an anti-slip effect. Compared to a conventional tire in which short steel fibers are oriented in the longitudinal direction of the tread, the tire of the present invention has a traction performance of about 5%.
An improvement of 0% was observed.

However, the present invention is not limited to the above embodiments. In other words, in a tire that has a tread surface layer on the upper surface of a base tread, relatively large particle powder or short fibers having a rod-like particle shape are oriented in almost the same direction as the tread thickness direction in the tread surface layer. Although any dispersed tire and manufacturing method may be used, the above embodiment is particularly suitable for manufacturing the present tire.

[Effect of the invention] As described above, in the case of a rubber composition containing particles or short fibers having anisotropy in length, when the rubber composition is extruded, the particles or short fibers reduce the flow resistance of the rubber. Based on the knowledge that the rubber is oriented in the same direction as the flow direction so that the amount of particles decreases, the rubber is cut in the direction perpendicular to the flow direction to create a strip in which the particles or short fibers are oriented in the thickness direction. Since the particles or short fibers are constructed so as to stand up and protrude in the thickness direction of the tread, it is possible to provide a tire that pierces the icy road surface and exhibits a large anti-slip effect.

In addition, the particles or short fibers are dispersed and oriented within the tread rubber, and one end is firmly held in the rubber, so they are difficult to fall off and can always provide an anti-slip effect. Since it is a fiber, it does not run on a general asphalt road surface and dig it up like so-called spiked tires, and it contributes greatly to this technical field.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing the extrusion state of a cylindrical body for manufacturing strips extruded from a tread extruder, and FIG. 2 is a schematic cross-sectional view showing the state in which the strips are laminated on a base tread.

Claims (2)

[Claims] (1) In a tire having a tread surface layer on the upper surface of the base tread, relatively large particle powder or short fibers having a rod-like particle shape are oriented in the same direction as the tread thickness direction in the tread surface layer. A studless tire characterized by being dispersed in a state. (2) extruding a rubber composition blended with relatively large particle powder or short fibers having a rod-like particle shape into a cylindrical shape;
The side wall of this cylindrical body is helically cut at a pitch length (d) smaller than the wall thickness (t) of the cylindrical body to form a strip, and the strip is cut when making the strip on the upper surface of the pre-extruded base tread. 1. A method for manufacturing a studless tire, which comprises the steps of: rolling one row or a plurality of strips in parallel at least once to form a tread rubber, and then molding and vulcanizing the strips.