JPH0227161B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is a safety tire for light vehicles that has excellent wear resistance, ride comfort, road gripping force, and durability and is easy to manufacture, especially for motorcycles and ATVs that can be used on all road surfaces such as rough terrain and gravel. Regarding safety tires for light vehicles (All Terrain Vehicles). [Prior art] Conventional safety tires for light vehicles include toroidal urethane casting tires, which are obtained by injecting urethane raw materials into a mold and reaction-curing them, and tires in which polyurethane extomers are filled in the inner cavity between the outer skin and the rim. , so-called integrated polyurethane-filled tires are often used. [Problems to be solved by the invention] All of these have been developed as tires for heavy loads, such as tires for construction vehicles, industrial vehicles, trucks, and buses, and are designed to operate under low loads and at relatively low speeds. motorcycles, or
The technology cannot be directly applied to ATV tires. For example, the former type of toroidal urethane casting tires have excellent wear resistance, but the tires themselves generally have high rigidity, which impedes ride comfort, and they also have poor road grip and high raw material costs. Furthermore, the latter polyurethane-filled tire has a complicated outer skin structure, which requires time and effort to manufacture, resulting in a problem in that the manufacturing cost is high. The present invention aims to solve these problems and provide a safety tire for light vehicles that can be suitably employed as a tire for light vehicles such as tires for motorcycles and ATVs. [Means for solving the problem] A toroid-shaped support member formed by injecting a urethane raw material into the space of a mold and curing it, and a toroid-shaped support member placed on the outer surface of the crown part of the toroid-shaped support member in the circumferential direction. and an outer skin portion which is placed and integrated by vulcanization, the toroidal support member comprising:
It is made of polyurethane elastic foam having a JISA hardness of 40 degrees or more and 90 degrees or less and a density of 0.6 g/cm ³ or less and 0.3 g/cm ³ or more, and the outer skin is made of a rubber composition for tire tread. This is a safety tire for light vehicles characterized by the following: An embodiment of the present invention will be described below based on the drawings. FIG. 1 shows a sectional view of the safety tire for light vehicles of the present invention. In the figure, a light vehicle safety tire 1 of the present invention is shown.
is a toroidal support member (hereinafter referred to as support member)
2, and an outer skin 3 that is placed integrally on the outer surface of the crown portion of the support member 2 in the circumferential direction.
The support member 2 is made of polyurethane elastic material, and has a JISA hardness of 40° or more and 90° or less,
Preferably, the angle is 50° or more and 60° or less. If the hardness is too low, heat generation due to repeated deformation during running increases, causing thermal deterioration of the polyurethane elastic material and making it susceptible to damage and cracking. On the other hand, if the hardness becomes too high, the longitudinal spring constant becomes high, impairing riding comfort. By using the foam as the polyurethane elastic body and adjusting the expansion ratio, the weight and longitudinal spring constant of the tire can be adjusted. Therefore, 0.6
A material with a density of g/cm ³ or less and 0.3 g/cm ³ or more, particularly a density of 0.6 g/cm ³ to 0.3 g/cm ³ is desirable from the viewpoint of weight reduction and balance of riding comfort. The basis for limiting the hardness and density of the support member will be clear from the examples described later. Next, the outer skin part 3 is arranged and integrated in the circumferential direction on the outer surface of the crown part of the support member 2 to form a tread part. Here, the outer skin portion 3 is formed of a rubber composition for tire treads mainly consisting of diene rubber such as polybutadiene rubber and styrene-butadiene rubber, as well as natural rubber, synthetic polyisoprene rubber, etc., or a mixture thereof. The composition may include commonly used additives such as carbon, oil, sulfur, and the like. Further, in the present invention, as shown in FIG. 2, the outer skin part 3 is extended from one bead part through the crown part to the other bead part so as to cover the outer surface of the support member 2. It is also possible to form a tread portion and a sidewall portion. In this case, the sidewall portion can effectively prevent damage and cracks to the side portion during driving on rough terrain or rough roads strewn with rocks. Next, regarding the manufacturing of the support member 2 of the present invention, as shown in FIG. A mold is used which forms a space 7 for molding the support member together with a ring mold 8 to be attached. The ring mold 8 has an injection port 10 for injecting the urethane raw material, and an outer mold 5.
is provided with an exhaust hole 11, and the urethane raw material is injected into the space 7 through the injection port 10 and reacted and cured at room temperature or under heating, and after curing, the outer mold 5 and the ring mold 8 are removed to remove the support member 2. can get. After that, the outer skin part 3 is attached to the crown part of the support member 2.
That is, in order to apply the unvulcanized or vulcanized rubber sheet, the vulcanization-integrating technique employed in the so-called retort method used when retreading the tread of ordinary pneumatic tires can be used as is. Note that the outer skin part 3 can be attached to the tread part and the sidewall part as an integral part or as separate parts. Further, the support member 2 can be formed into an arch shape as shown in FIG. 1, or can be formed into a solid shape as shown in FIG. The former is applicable to both flat-bottomed rims and deep-bottomed rims, and is particularly preferred from the viewpoint of reducing the weight of the tire. [Example] For a tire with a tire size of 4.60S16 4P, a support member was provided with an outer skin formed of a tire tread rubber composition having the composition shown in Table 1, and a support member having the hardness and density shown in Table 2. Examples 1 to 6, which were formed into the shape shown in Figure 1 by integrating with the parts, and Comparative Example 1, which was manufactured according to conventional specifications.
A performance test was conducted on 4 to 4 and the two were compared. The performance test was conducted under the test conditions shown below to determine thermal deterioration of the polyurethane elastic material and ride comfort by conducting a durability test to confirm the occurrence of tire damage and cracks and a strength test after driving. . (a) Durability test Using a running test machine, the distance traveled until failure was determined under the following conditions: load: 290Kg (150% increase of JIS maximum load), speed: 65Km/H, internal pressure: 2.25Kg/cm ^, drum diameter: 760mm. By comparison

【table】

〔Effect of the invention〕

As mentioned above, the safety tire for light vehicles of the present invention has the following features:
The toroidal support member has a JISA hardness of 40° or more and 90°. The following range and density is 0.6g/ ^cm3 or less and 0.3
Since it is made of polyurethane elastic material with a range of g/cm ³ or more, it has the advantages of easy manufacture, improved wear resistance and road grip, excellent riding comfort, and light weight.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of the safety tire for light vehicles of the present invention, and FIG. 3 is a schematic cross-sectional view of a mold for manufacturing the safety tires for light vehicles. 2...Troid-shaped support member, 3...Outer skin part.

Claims (1)

[Claims] 1. A toroid-shaped support member formed by injecting a urethane raw material into the space of a mold and curing it, and a toroid-shaped support member placed in the circumferential direction on the outer surface of the crown part of the toroid-shaped support member and integrated by vulcanization. The toroidal support member is made of polyurethane elastic foam having a JISA hardness of 40 degrees or more and 90 degrees or less and a density of 0.6 g/cm ³ or less and 0.3 g/cm ³ or more. 1. A safety tire for a light vehicle, characterized in that the outer skin is made of a rubber composition for tire tread.