JPH05212816A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve a bead strength ratio and a strength utilization rate as well as reduce a bead member/tire weight ratio by adding a synthetic wire material as a bead core to the bead member which constitutes a tire bead part, and using a molten solid material of thermoplastic fiber obtained by fusing a high-rigidity non-metal fiber and fiber in a mixed woven state, as the synthetic wire material. CONSTITUTION:A synthetic wire material 1 used as a bead core for a bead member is composed of a non-metal fiber and a thermoplastic fiber 3. The thermoplastic fiber 3 is used as a curing agent of the non-metal fiber 2 by thermally fusing the fiber 3, and should be one which has a lower melting point than the fiber 2 and high compatibility with the non-metal fiber 2 for use through selection. The non-metal fiber 2 and the thermoplastic fiber 3 are mix-spun into a mix-spun yarn 4. The thermoplastic fiber 3 is thermally fused in a mix spun yarn 4, then a clearance between the non-metal fibers 2, 2... is fully impregnated with the heat-molten product of the thermoplastic fiber 3, and the molten product is cooled to be solidified in an impregnated state. Thus a high-ridigity synthetic wire material 1 without any internal flaw is obtained. The bead member is molded using the synthetic wire material 1 as one for the bead.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to improvement of a bead portion thereof.

[0002]

2. Description of the Related Art Conventionally, in a pneumatic tire, a bead core of a bead member is generally made of a metal material such as a steel wire or a metal plate, but the metal core is heavy and the tire weight increases. As a result, it is becoming incompatible with the recent reduction in fuel consumption and, in turn, tire weight reduction.

Recently, in order to reduce the weight of pneumatic tires, it is proposed to use a non-metallic fibrous wire made of an organic fiber such as aramid fiber or an inorganic fiber such as carbon fiber instead of a metal core. A pneumatic tire having a bead member obtained by integrally curing the above fibrous wire with a liquid thermosetting resin or liquid rubber (see, for example, Japanese Patent Laid-open No. Sho 5 (1999) -58242)
No. 7-66007) is proposed.

In the above-mentioned known pneumatic tire, the bead core of the bead member is made of a non-metallic fibrous wire, so that it is lighter in weight than the case where a metal material is used as the bead core. However, there has been a problem that the strength utilization factor of the wire is significantly reduced due to the following reasons (1) and (2).

(1) The non-metallic fibrous wire is not uniformly impregnated with the liquid thermosetting resin or liquid rubber, and voids are likely to be generated inside.

(2) The liquid substance impregnated in the wire is
Hardened after bead molding. Therefore, at the time of bead molding in which the wire is wound around the former, the liquid substance is simply impregnated in the wire and does not yet function as a hardening material, so the wire material is less rigid than steel wire etc. It will be wound up on the former, which tends to cause strong unevenness and molding disorder.

The present invention has been made for the purpose of eliminating such conventional problems.

[0008]

According to the present invention, a bead member constituting a tire bead portion includes a synthetic wire rod as a bead core, and the synthetic wire rod is mixed with a highly rigid non-metal fiber and the fiber. A pneumatic tire comprising a molten and solidified product of thermoplastic fibers melted in a state.

The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 shows an example of manufacturing a synthetic wire rod 1 used as a bead core of a bead member applied to a pneumatic tire of the present invention.

At the time of manufacturing the wire 1, the non-metal fiber 2 and the thermoplastic fiber 3 are used as shown in an enlarged view in FIG.

The non-metal fiber 2 may be either organic or inorganic (excluding metal), and one having high rigidity is selected from various materials and used. Examples of preferable high-rigidity fiber include aramid fiber, glass fiber, carbon fiber, whisker fiber, etc., and other tensile elastic modulus is 40 GP.
High modulus fibers of a or above are suitable.

The thermoplastic fiber 3 is used as a curing material for the above-mentioned non-metal fiber after being melted by heating, and is not particularly limited as long as it can function as a curing material. Examples of such a fiber 3 include polyamides such as nylon 6 and nylon 6,6, polyolefins such as polypropylene,
Among the polyester type, polypinyl chloride type, polyacrylonitrile type, fluorine and the like, one having a melting point lower than that of the fiber 2 and having a good compatibility with the fiber 2 is selected and used. By the way, when the fiber 2 is an aramid fiber, nylon 6 and nylon 6,6 are suitable.

The non-metal fiber 2 and the thermoplastic fiber 3 are mixed to form a mixed fiber 4. The mixing ratio of the former fiber 2 and the latter fiber 3 can be selected from a wide range, but when the mixing ratio of the latter fiber 3 is 20% by volume or less, the function as a hardening material becomes insufficient, and when it is 80% by volume or more, it is used as a strength material. Since the amount of the former fiber becomes too small and the strength becomes insufficient, 20 to 80
Volume% is suitable.

The thermoplastic fiber 3 is heated and melted in the state of the mixed fiber 4, that is, in the state in which the respective portions are uniformly mixed between the fibers 2. As a result, the heat-melted material of the fiber 3 is a non-metal fiber 2,2 ...
Therefore, each part is uniformly impregnated with no space between them, and by cooling and solidifying the melt under the impregnated state, it is reinforced by the function as a hardening material of the molten and solidified material and has no internal defect. A highly rigid synthetic wire 1 is obtained.

In the present invention, the above synthetic wire 1 is used as a bead wire, and a bead member is molded by a conventional method.

That is, as shown in FIG. 2, the matrix wire 7 is covered by a small extruder 6 while drawing and aligning the required number of the synthetic wire 1 from the reel 5 by a conventional method, and then the former 8 is wound a required number of times. After the bead molding, the rubber 7 is cured to obtain a ring-shaped bead member (not shown).

The synthetic wire 1 has the non-metallic fiber 3 as a main constituent element, but it functions as a hardening material for the molten and solidified material of the thermoplastic fiber 3 mixed therein and imparts high rigidity which is not different from that of steel wire or the like. Has been done. Therefore, tension unevenness and molding irregularity do not occur during bead molding, and it is possible to eliminate internal defects (voids, etc.) in the synthetic wire 1 and increase the strength utilization ratio of the non-metal fiber 3. it can. By constructing the tire bead portion from such a bead member, a lightweight, high-quality, and high-performance pneumatic tire can be obtained.

Table 1 shows the results of comparative tests between the pneumatic tire of the present invention and the comparative pneumatic tire.

[0020]

[Table 1]

Present Invention 1 ... Aramid Fiber (12000D)
And nylon 6 fibers were mixed at a mixing ratio of 70: 30% by volume, and then nylon 6 fibers were melted to form a synthetic wire rod, which was used as a bead wire rod, and the wire rod was grommeted using a matrix rubber to form a bead member. To get

Invention 2 ... The thermoplastic fiber is nylon 6,6
The same as the present invention 1 except that

Comparison 1 ... A bead wire (12000D) made of aramid fiber was impregnated with an epoxy resin, then bead-molded, and then a resin solution was cured to grommet to obtain a bead member.

Comparative 2 ... Conventional steel bead member As is apparent from Table 1, the invention 1 and 2 have a bead strength ratio and a strength utilization rate which are nearly 2.5 times higher than those of Comparative 1 (thermosetting resin type). In addition, the bead member and thus the tire are excellent in quality and performance, and the bead member weight ratio and the tire weight ratio are 25 in comparison with the comparison 2 (steel type).
%, The latter is about 4% lower, and is also lightweight.

[0025]

According to the present invention, a synthetic wire rod composed of a highly rigid non-metallic fiber and a melted and solidified product of a thermoplastic fiber melted in a state mixed with the fiber is used as a bead core of a tire bead member. Therefore, improvement of the bead strength ratio and strength utilization ratio and reduction of the bead member weight ratio and the tire weight ratio can be achieved at the same time, and it is possible to provide a pneumatic tire that is lightweight and has good quality and performance.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a production example of a synthetic wire rod applied to a pneumatic tire of the present invention.

FIG. 2 is a schematic explanatory view showing an example of manufacturing a bead member.

[Explanation of symbols]

 1 Synthetic wire 2 Non-metal fiber 3 Thermoplastic fiber 4 Mixed fiber

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Claims (1)

[Claims] 1. A bead member constituting a tire bead portion includes a synthetic wire rod as a bead core, and the synthetic wire rod comprises a highly rigid non-metallic fiber and a thermoplastic fiber melted in a state of being mixed with the fiber. A pneumatic tire comprising a molten and solidified product.