JPH0415107A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve performance on snow and ice while maintaining wear resistance by forming tread by a base rubber which is located on the outside of a belt layer and a cap rubber which is located on the outside of it, and specifying surface thickness and side wall thickness on the surface of tread of cap rubber. CONSTITUTION:A tread 2 of a tire 1 is formed by a base rubber 2A which is arranged on the outside of direction of radius of a belt layer 7 and a cap rubber 2B which is arranged on the outside of direction of radius. A main groove 10 is provided by denting the surface of tread which is formed by the cap rubber 2B. The cap rubber 2B uses rubber which excels in performance on snow and ice, and the base rubber 2A uses rubber which excels in wear resistance. Thickness T1 of the cap rubber 2B on the surface of tread is in the range of 20 to 50% of depth PD of the main groove 10. Thickness T2 of the cap rubber 2B on the side wall of main groove 10 is above 5% and below 25% of thickness T1 on the surface of tread.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a pneumatic tire that has excellent performance on snow and ice in winter and wear resistance in summer, and can be suitably used for trucks and buses. Regarding.

[Conventional technology]

In order to prevent damage to road surfaces caused by spiked tires, studless tires are increasingly being used, and these tires are used not only for passenger cars but also for trucks and buses. However, since truck and bus tires are for commercial use, wear resistance is particularly important compared to passenger car tires, and because they are used more frequently, they are often used up within one to two years, especially for trucks.・There are so-called snow tires that are used as studless tires for buses, but they are best installed before the snow starts to last until the next snowfall.
Therefore, in addition to performance on snow and ice during snowfall in winter, wear resistance performance during non-snowfall is required. Conventionally, spikes are often driven into tires, especially when driving on ice.

[Problem to be solved by the invention]

However, tires with spikes are regulated, and on the other hand, there is no technology to improve the performance on snow and ice of passenger car tires that use rubber with good low-temperature properties that maintain flexibility even at low temperatures and foam rubber etc. in the tread rubber compound. , which are used under high load and high frequency such as truck and bus tires.
Uruchino could not be used as is for tires, where wear resistance is an important requirement.

An object of the present invention is to provide a pneumatic tire that has improved performance on snow and ice while maintaining wear resistance.

[Means to solve the problem]

In the present invention, the tread has a two-layer structure including a base rubber located outside the belt layer and a cap rubber located outside the base rubber forming the tread surface, and the surface thickness of the cap rubber on the tread surface (T I) is in the range of 20% to 50% of the depth (PD) of the main groove provided in the tread, the camp rubber covers the sidewall of the main groove, and the sidewall thickness (T2) of the sidewall of the cap rubber is This pneumatic tire has a thickness of 25% or less of the surface thickness (T1), and uses a rubber with excellent on-ice performance as the cap rubber and a rubber with excellent wear resistance as the base rubber.

[Effect]

The tread 2 consists of a base rubber on the outside of the belt layer and a cap rubber on the outside in the radial direction.The cap rubber uses rubber with excellent performance on snow and ice, and the base rubber uses rubber with excellent wear resistance. use.

In addition, the thickness T1 of the camp rubber on the tread surface is set in a range of 20% to 50% of the depth PD of the main groove to prevent early disappearance of the cap rubber and maintain performance on snow and ice during snowfall. Prevents the volume of the base rubber from decreasing and prevents deterioration of wear resistance during non-snowy conditions.

Furthermore, since the cap rubber covers the side walls of the main groove with a thickness T2 that does not expose the base rubber (and is less than 25% of the thickness TI), it can be used even after the camping rubber is worn out, for example in areas with shallow snow. Travel is made possible to some extent by the cap rubber remaining on the side walls of the main groove.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In FIG. 141, the tire 1 has a carcass 6 that extends from the tread portion 2 through the sidewall portion 3 and is rolled up around the bead core 5 of the bead portion 4 from the inside to the outside of the tire. The carcass 6 consists of one or more braids with cords arranged radially and in parallel, and the cords are mainly made of steel cords made of a plurality of twisted metal filaments, or aromatic polyamide cords having strength and modulus similar to steel cords, for example. . In addition, when using a plurality of braais, braais rolled up from the outside of the tire to the inside of the bead core may be included.

A belt layer 7 is disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2, and in this example, the belt layer 7
consists of four layers of braai. The upper three braais include a plurality of cords inclined at a relatively small angle of 10 to 30 degrees with respect to the tire equator C, and the cord of the braai closest to the carcass 6 is made at an angle of 50 to 80 degrees. A triangular structure is formed within the belt layer 7 to increase the rigidity of the belt.

A tapered apex 8 extending outward in the tire radial direction is arranged on the bead core 5. The apex 8 fills the space between the toroidal main body part of the carcass and the winding part and integrates it, and by using relatively hard rubber, it increases the rigidity of the bead part 4 and improves the steering stability of the tire. Improve durability performance. Therefore, Apex 8 is J
Hard rubber having an ISA hardness of about 70 to 90° is used.

In order to reduce the shear strain between the guide and the scraps 6, it may be formed into a two-layered structure consisting of a soft rubber layer and a hard rubber layer.

A reinforcing layer 9 is provided on the outer surface of the rolled-up portion of the carcass 6 in the tire axial direction.
is placed. The reinforcing layer 9 includes a plurality of cords arranged at an angle and parallel to the inner circumferential direction of the tire. For the cords, a raw steel cord is used, but an aromatic polyamide cord or a nylon cord can also be used. They can also be used together.

The tread 2 consists of a base rubber 2A disposed on the radially outer side of the belt layer 7, and a cap rubber 2B disposed on the radial outer side of the base rubber 2A, and the cap rubber 2B forms the tread surface and also dented,
A main groove 10 is provided.

Further, a rubber with excellent performance on snow and ice is used for the cap rubber 2B, and a rubber with excellent abrasion resistance is used for the base rubber 2A.

The thickness T1 of the trend surface of the cap rubber 2B is in the range of 20% to 50% of the depth FD of the main groove 10.

If it is less than 20%, the cap rubber 2B disappears early, making it impossible to ensure performance on snow and ice during snowfall.If it exceeds 50%, the volume of base rubber 2A decreases, resulting in poor wear resistance performance in non-snowy conditions. . Camp rubber 2B has main groove 10
The side wall of the main groove 10 is covered without exposing the base rubber 2A, so that even after the cap rubber 2B is worn out, the cap rubber 2B remaining on the side wall of the main groove 10 makes it possible to run, for example, in a shallow lightning area to some extent. do.

The thickness T2 of the cap rubber 2B at the side wall of the main groove 10 is set to be 5% or more and 25% or less of the thickness T1 at the tread surface. When it exceeds 25%, the volume of the base rubber 2A decreases, and the wear resistance performance decreases. Preferably 10-2
Set to a range of 0%.

Furthermore, cap rubber 2B is JISAt at -5℃ or below.
! Rubber with a degree of 55 to 671 is used. If it exceeds 67", grip performance will be poor, especially on ice, as the tread surface will dig into the unevenness of the ice surface. If it is less than 55 degrees, the tread will lack rigidity, resulting in insufficient performance such as pitching force on snowy roads. .

Diene rubber is preferably used to ensure properties at low temperatures.

On the other hand, as the base rubber 2A, a rubber that has good adhesion to the cap rubber 2B and has excellent abrasion resistance is used.

Rubber containing a large amount of BR generally has high wear resistance, but due to the high load conditions of truck and bus tires, they generate a large amount of heat and may be damaged by heat, such as failure of the adhesion between the steel cord of the belt layer and the rubber component. occurs. Therefore,
In order to satisfy both, natural rubber/BR is 50150~80/
20 parts by weight is applied. Especially high-cis Bl, which contains a lot of cis structure? Carbon black is preferably fine-grained, such as SAF or 15AF, with a carbon black of 40 to 60
! If the amount exceeds 60 parts by weight, heat generation will increase, leading to the above-mentioned adhesion failure due to heat.

In addition, it is preferable to mix a processed powder product whose main component is cellulose material into the cap rubber 2B. By mixing such a processed powder product into the cap rubber 2B, it is possible to maintain the abrasion resistance performance while retaining snow, snow, etc. On-ice performance, especially on-ice performance, can be further improved.

The cellulose material contained in the processed powder product is preferably a powder with an average particle size of 20 to 600 us.This trend is due to the fact that with wear, the cellulose powder is exposed on the tread surface, and the water surface By scratching the tread, it produces a spike effect, and when the powder falls off the trend as wear progresses, the voids, unevenness, and edges on the tread surface increase the resistance on the ice surface and improve the grip on the ice. Improve performance.

By using a cellulose material in the powder, it becomes easier to disperse in the fA and sm of the tread rubber, and it forms a loose bond with the rubber component, so that it easily falls off as the wear progresses during running. , which does not easily reduce the tear strength of the rubber, and prevents, for example, the occurrence of groove bottom cracks.

If the particle size of the powder is less than 20μ, it is difficult to exhibit the spike effect, and if it exceeds 600μ, the contact area of the rubber itself with the water surface decreases, resulting in a decrease in grip performance on ice. More preferably 100 to 200tI-
This powder processed product containing cellulose as a main component can be produced by, for example, pulverizing rice husks. This powder processed product is preferably blended in an amount of 3 to 25 parts by weight per 100 parts by weight of the rubber component.

If the amount is 3 parts by weight, the effect will be small, and if it exceeds 25 parts by weight, the contact area of the rubber itself with the water surface will decrease, resulting in a decrease in grip performance on ice.

〔Concrete example〕

Five types of tires were prototyped according to the specifications shown in Tables 1 and 2, and an ice braking test and a wear resistance test were conducted. The results are also shown in the same table.

The braking distances in Table 1 were measured under the following conditions.

Test location: Hokkaido frozen road test course ice surface temperature Knee 3
～-2℃ Test method: Installed on a 10-ton vehicle and measured the distance from when the wheels are locked at a speed of 30 km/h until the wheels stop. 45 m or less is a passing level for normal use. Also, wear according to the same table The lifespan is measured by driving each tire on a 10-ton vehicle in winter and measuring the distance until the main groove becomes shallower than 1.8 wm. A passing level is 50,000 b or more.

In Example 1, both wear life and performance on ice were at a satisfactory level. Furthermore, Example 2, in which the cap rubber was mixed with a processed powder product mainly composed of cellulose material, showed a remarkable improvement in performance on ice.

Liquid BR in Table 1: Trade name LBR260 [Effects of the Invention] As described above, the tire of the present invention has sufficient wear life and performance on snow and ice, and can be particularly suitably used for trucks and buses.

[Brief explanation of the drawing]

FIG. 1 is a new view in the width direction of a tire showing one embodiment of the present invention, and FIG. 2 is a sectional view of the tread portion thereof. 2~・Tread, 2A-Base rubber, 2B-・・
Ki+rubber, 6-carcass, 7-belt,
8.- Bead Apex. Patent issued by 1 person: Agent of Sumitomo Rubber Industries Co., Ltd.
Patent Attorney Tadashi Naemura 1st

Claims (1)

[Claims] 1. A base rubber whose tread is located outside the belt layer,
This base rubber has a two-layer structure with the cap rubber located outside and forming the tread surface, and the surface thickness (TI) of the cap rubber on the tread surface is 20% of the depth (PD) of the main groove provided in the tread. % to 50%, and the cap rubber covers the side wall of the main groove, and the side wall thickness (T2) of the side wall of the cap rubber is 25% or less of the surface thickness (T1), and the cap rubber is a pneumatic tire made of rubber with excellent performance on snow and ice, and the base rubber is rubber with excellent wear resistance.