JPH1095211A - Bead material for bicycle tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance shape holding performance, so as to prevent a bead material from easily slipping off from a tire molding former, by forming a linear composite material by three layers of an innermost layer, an intermediate layer and an outermost layer, concerning a bead material for a bicycle tire, formed of a linear composite material formed by impregnating and coating thermoplastic resin in a reinforcing fiber bundle. SOLUTION: A bead material for a bicycle tire is composed of a linear composite material formed by impregnating resin into a reinforcing organic fiber bundle and coating the front surface, and this linear composite material is formed of three layers of an innermost layer formed of only reinforcing fibers, an intermediate layer in which resin is impregnated among single fibers for constituting a reinforcing fiber bundle 1, and an outermost layer formed of only coating resin. The radius of the innermost layer and the thickness of the intermediate layer and the outermost layer are respectively set in the range of 0.20 to 0.95 times, 0.04 to 0.50 times, and 0.01 to 0.30 times of radii of respective linear composite materials. The ratio of the minimum radius of curvature of the linear composite material and the radius of the bead material is set to 150 or less, para-Aramid fiber is suitable for a fiber for constituting the reinforcing organic fiber bundle, and the total size is in the range of 4000 to 20000 denier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bead material for a bicycle tire (which may be simply referred to as a bead material) comprising a linear composite material in which a reinforcing fiber bundle is impregnated and coated with a thermoplastic resin. It is a high-strength, lightweight, and significantly improved workability when molding a bicycle tire, and the resulting tire has good portability, durability and handleability.

[0002]

2. Description of the Related Art Generally, the role of a bead material of a bicycle tire is to fix a carcass ply and at the same time to fix a tire on a rim. Therefore, the bead material should have sufficient tensile strength, low elongation that does not elongate due to the internal pressure of the tire, high elastic modulus, and vulcanization or running of the tire. The material is required to be a thermally stable material that is unlikely to expand or contract due to heat. In addition, rubber comes into contact with the periphery of the bead material, and since compression and bending stiffness are significantly different between the rubber and the bead material, peeling generally tends to occur at the boundary surface, so that the interface adhesion is also important. Power factor.

Conventionally, steel wires have been overwhelmingly used as materials satisfying such requirements in consideration of cost. However, steel wire is so rigid that it cannot be folded when storing or carrying spare spare tires on a bicycle, etc.In addition, rim assembly at the time of replacement requires a large amount of force and needs to be replaced This has the disadvantage of requiring much time and effort. In particular, in recent years, bicycle touring has become widespread as leisure and competition, and there is a demand for development of tires that can be folded, carried, and easily replaced with a reduction in tire weight.

[0004] In order to solve such a problem, it has been studied to replace a bead wire for a bicycle, which has been mainly made of steel, with an organic fiber material having properties equal to or better than that. For example,
Japanese Unexamined Patent Publication No. 22722 discloses a tire using an organic fiber having a specified elastic modulus and strength as a bead core. However, since the bead material described in the above publication is not impregnated with a resin and has insufficient bending stiffness and hardly generates resistance to bending and compression, a shock is applied to the tire during driving with the tire mounted. When added, the bead portion is easily detached from the rim, and when molding the tire, it is easily detached from the molding former due to poor shape retention, and the productivity is significantly reduced as compared with the case where a steel wire is used. There was a disadvantage.

Further, Japanese Utility Model Laid-Open No. 1-16901,
A method of filling a fiber bundle of carbon fibers with a thermosetting resin to form a bead material is disclosed. However, inorganic fibers are generally brittle and covered with a highly rigid thermosetting resin, so the bead material is likely to be partially damaged while the tire is being folded and carried, However, there has been a problem that it is difficult to fix the tire to the tire, the tensile strength is insufficient, and in the case of a tubeless tire, it is difficult to maintain airtightness.

On the other hand, from the viewpoints of recent resource saving, energy saving, environmental protection on a global scale, etc., bicycle tires include:
It is desirable to reduce the weight and make it a completely organic composite material that does not leave any reinforcing material during incineration, and that it is foldable and has excellent handleability. There is a need for a bead material that has rigidity and does not easily come off the former.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to remove tires from tire formers because of their excellent shape retention during tire molding. Another object of the present invention is to provide a bead material for a bicycle tire which is excellent in durability, handleability (foldability, portability) and waste incineration.

[0008]

The above objects of the present invention are as follows.
"A linear composite material in which a reinforcing organic fiber bundle is impregnated with a resin and surface-coated, the cross section of which is the innermost layer made of only the reinforcing organic fiber, and the resin is impregnated between the single fibers of the reinforcing organic fiber. A bead material for a bicycle tire comprising a linear composite material formed of three intermediate layers consisting of an intermediate layer and an outermost layer consisting of only a coating resin. "

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As the organic fiber for reinforcement used in the present invention, polyparaphenylene terephthalamide (for example, Kevlar manufactured by DuPont) or copolyparaphenylene-3,4'-oxydiphenylene terephthalamide ( For example, organic fibers such as para-aramid fibers (para-fully aromatic polyamide fibers) such as Teijin's Technora), wholly aromatic polyester fibers, high-strength polyethylene fibers, and high-strength vinylon fibers can be mentioned. Aramid fibers are preferred. In general, inorganic fibers have a large specific gravity, so that it is difficult to reduce the weight. In addition, they are brittle, so that moldability during tire molding and handleability of the obtained tire are deteriorated.

The total fineness of the reinforcing organic fiber bundle (reinforcing fiber bundle) comprising the above organic fibers is preferably 4,000 to 20,000 denier, particularly preferably 6,000 to 15,000 denier. If it is less than this range, the stiffness of the bead material itself tends to decrease, and workability during tire molding tends to decrease, and if it exceeds this range, folding resistance after tire molding tends to deteriorate. Therefore, the effect of the present invention is reduced. In the present invention, the surface of the organic fiber may be appropriately subjected to an appropriate sizing treatment or a treatment such as a coupling agent treatment.

Next, the resin used for impregnating and covering the surface of the reinforcing fiber bundle may be either a thermoplastic resin or a thermosetting resin. However, since the obtained bead material is more flexible and has excellent handleability. Thermoplastic resins are preferred. For example, nylons such as nylon-6, nylon-66, nylon-46, nylon-8, nylon-10, nylon-612, nylon-12, and nylon-based elastomer (N
y) resin, polyethylene terephthalate (PET),
Polyester resin such as polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyester elastomer, olefin elastomer, polyacetal, polyphenylene sulfide (PP
S), resins such as polyethersulfone (PES) and polyetheretherketone (PEEK), among which nylon-based resins are preferred. These resins are used alone or in combination of two or more.

Further, these thermoplastic resins may contain various additives for improving their properties, for example, a heat-resistant agent, a light-resistance improver, an ultraviolet-ray deterioration inhibitor, an antistatic agent, a lubricant, a release agent, a dye, A coloring agent such as a pigment, a crystallization accelerator, a flame retardant, or the like, and an inorganic, organic, or metal powder such as calcium carbonate as a third component may be added.

The bead material for a bicycle tire of the present invention is a linear composite material obtained by impregnating a surface of the above-mentioned organic fiber bundle for reinforcement with a resin, and has an innermost layer having a cross section composed of only the reinforcing fiber. It is important that the fiber bundle is formed of three layers: an intermediate layer in which the resin is impregnated between the single fibers constituting the fiber bundle, and an outermost layer made of only the coating resin. In the case of a bead material in which the resin is impregnated up to the center of the bead material and the innermost layer does not exist, the rigidity of the bead material is excessively large, so that the groove is less likely to be removed during the molding former process during tire molding, and molding workability is improved. On the other hand, the strength retention of the reinforcing fiber bundle in the tire molding process is significantly reduced,
The resulting rim fit pressure (maximum air pressure when the tire is stably fixed to the rim when internal pressure is applied to the tire) and water pressure (fill with water instead of air and break the bead) This is not preferable because not only performance such as maximum water pressure when water is jetted out) is lowered, but also the tire becomes too rigid to be folded and carried.

In the case where only the outermost layer portion is covered with the resin without the intermediate layer portion impregnated with the resin between the single fibers of the reinforcing fiber bundle, the reinforcing organic fiber bundle has Mechanical properties, for example, low elongation, easy to use the characteristics of high elastic modulus, but in the forming former process during tire molding, the bead material is insufficient in rigidity, ring-shaped bead material is likely to twist, tire The molding speed is extremely lowered, and the molding workability is remarkably reduced.

Further, when there is no outermost layer made of only the coating resin, the RFL applied for improving the adhesion is used.
At the time of the adhesive treatment, it is difficult to uniformly attach the treating agent, and the adhesion to the tire becomes insufficient.

The radius of the innermost layer portion (in the case of a non-circular shape, the radius of a circle having the same area) and the thickness of the intermediate layer portion and the outermost layer portion are respectively the radius R of the linear composite material (in the case of a non-circular shape). Is the radius of a circle having the same area) of 0.20 to 0.95
Times, 0.04 to 0.50 times, 0.01 to 0.30 times, especially 0.70 to 0.90 times, 0.05 to 0.20 times, 0.
It is more preferable that the ratio be in the range of 05 to 0.10 times in order to achieve the object of the present invention.

In the bead material of the present invention, the ratio D / R between the minimum radius of curvature D and the bead material radius R that can maintain a circular shape without breaking at a specific location is preferably 150 or less, particularly preferably 50 to 120, By doing so, it is possible to further improve tire moldability due to appropriate rigidity while satisfying performance such as rim fitting pressure and water resistance.

A specific method for producing the above-described bead material for a bicycle tire according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a manufacturing process of the bead material of the present invention.

In FIG. 1, a continuous reinforcing fiber bundle 1 is shown.
A constant tension is applied by the front tension controller 4 and the rear tension controller 16 from the bobbin 2 via the guide 3. In this state, the fiber bundle is guided to the preheater 5, where it is heated to decompose and remove the moisture and excess oil agent of the reinforcing fiber bundle 1. Then, it is introduced into the polymer reservoir 8 from the introduction side nipple 7 attached to the die head 12 via the guide 6. Here, the remolding nozzle 13 melted by the screw 11, impregnated with the molten thermoplastic resin extruded through the throat 10, surface-coated, and then heated to a melting temperature of the thermoplastic resin or higher after passing through the outlet die 9. Formed by Subsequently, while being cooled by the cooling bath 15 via the guide guide roller 14, it is picked up by the pick-up roll 17. In this way, the reinforcing fiber bundle 1 impregnated and covered with the thermoplastic resin is wound up by the winder 18 to form a bead material.

At this time, the thickness of each layer is adjusted by controlling the melt viscosity of the resin used, the pressure of the molten resin in the outlet die 9, and the molding speed. Usually, the melting temperature of the resin is adjusted so that the viscosity of the molten resin is several thousand poise, but when the thickness of the intermediate layer is increased, the viscosity of the molten resin is lowered, and when the thickness is reduced, the viscosity of the molten resin is increased. . The pressure of the molten resin in the discharge side die 9 increases as the thickness of the intermediate layer increases, and as the pressure decreases, the thickness of the intermediate layer decreases. It will be thinner.

The thickness of the outermost layer (resin layer) can be substantially determined by the outer diameter of the reinforcing fiber bundle 1 and the outer diameter of the reshaping nozzle 13.

[0022]

The present invention will be described below in detail with reference to examples. The evaluation of the thickness, breaking strength, bending hardness, weight content Wf of the reinforcing fiber, torsion, groove detachment ratio, etc. of each layer shown in the examples was carried out according to the following methods.

<Measurement of Thickness of Each Layer> The bead material was cut in a direction perpendicular to the length direction, and the cross section was observed with an optical microscope. The thickness of each layer was measured at four points for one section, and the average value of each was determined to be the thickness of each layer. The fiber layer thickness (innermost layer), the fiber + resin layer thickness (intermediate layer), and the resin layer thickness (outermost layer) are as shown in the schematic diagram of FIG.

<Measurement of breaking strength of bead material> Intesc
o company tensile tester (Model Intesco Model
2005) and a test length of 6 using an SF chuck.
The measurement was performed under the condition of a 70 mm tensile speed of 268 mm / min.

<Bending Hardness> Using a Gurley type bending hardness tester manufactured by Tester Sangyo Co., Ltd., five points were measured for each sample, and the average value was defined as the bending hardness.

<Measurement of Weight Content Wf of Reinforcing Fiber> Weight of reinforcing fiber bundle before resin coating (W ₀ ) and weight of reinforcing fiber bundle after resin coating (W1 _: weight of bead material) Was measured and calculated by the following equation.

Wf = (W ₀ / W ₁ ) × 100 <Twist and Detachment Ratio when Forming a Bicycle Tire> A ring-shaped bead material sample is applied to a forming former used for forming a bicycle tire, and then a ring-shaped bead is formed. The width of the torsion generated when both ends were elongated in an elliptical shape from was measured and defined as the torsion width. Further, in this state, the forming former was spread, and a ratio of the forming former coming out of the groove was measured, and the ratio was defined as a groove coming-out ratio.

<Rim Fitting Pressure and Water Resistance During Molding of Bicycle Tire> Six 26-inch bicycle tires are prepared, and the bead portions of the tires are stuck to the rim and the tire is stably rimed. The maximum air pressure fixed to the sample was measured, and the average value was defined as the rim fit pressure. Also,
Water was filled instead of air, and the breaking water pressure at which the bead portion was broken and water spurted out was measured, and the average value was defined as the water pressure.

[Example 1] 1500 denier / 1000
Nine filament "Technola" yarns (para-aramid fiber manufactured by Teijin Limited) are aligned and twisted at a twist number of 25 turns / m to form one reinforcing fiber bundle. The reinforcing fiber bundle Was heated with a preheater heated to 350 ° C. for 60 seconds, and then led to a nipple for resin coating, where it was melted.
120 Nylon 66 resin controlled at 00 ° C
The fiber bundle was impregnated under a pressure of kg / cm ² and the surface was coated. Next, it was pulled out from a die having an inner diameter of 1.5 mm and a length of 5 mm, and then heated to 310 ° C. and had an inner diameter of 1.6 m.
Molding was performed using a remolding nozzle having a length of 5 mm and a length of 5 mm. Then, it was immediately cooled by circulating water to obtain a fiber bundle coated with the resin. The molding speed at this time was 2 m / min. The obtained resin-coated fiber bundle (bead material) is subjected to an adhesion treatment (hereinafter, referred to as RFL treatment) for enhancing the interfacial adhesion with the rubber of the bicycle tire, followed by 10
Heat treatment was performed at 5 ° C. for 30 seconds and at 195 ° C. for 1 minute to obtain a bead material (300 m) to which 1% by weight of the bonding agent had adhered. Various physical properties of the obtained bead material and characteristic values of a 26-inch tire molded using the bead material are as shown in Table 1, and are suitable as a bead material for a bicycle tire. The handleability was also good.

[Example 2] 1500 denier / 1000
Four "Technola" filaments (para-aramid fiber manufactured by Teijin Limited) were aligned and twisted at a twist number of 30 turns / m and used as one reinforcing fiber bundle. 1 mm, a die of 5 mm in length was pulled out, and then the same as in Example 1 except that the final shaping was performed with a reshaping nozzle having an inner diameter of 1.0 mm and a length of 5 mm. The obtained bead material was obtained. This bead material was also sufficiently practical.

Example 3 A bead material having the properties shown in Table 1 was obtained in the same manner as in Example 1 except that Ny-12 was used as the coating resin. This bead material was also sufficiently practical.

Example 4 Except that polybutylene terephthalate resin (PBT) was used as the coating resin,
A bead material having the properties shown in Table 1 was obtained by carrying out the same procedure as in Example 1. This bead material was also sufficiently practical.

Example 5 1500 as a reinforcing fiber
Except that nine denier / 1000 filament "Technola" yarns (para-aramid fiber manufactured by Teijin Limited) were aligned and twisted at a twist number of 40 turns / m to form one reinforcing fiber bundle. In the same manner as in Example 1, a bead material having the properties shown in Table 1 was obtained. This bead material was also sufficiently practical.

Example 6 As a coating resin, a nylon elastomer resin (manufactured by Daicel Huls Co., Ltd .: brand E-62M)
-S3), except that the resin extrusion temperature was changed.
A bead material having the properties shown in Table 1 was obtained by carrying out the same procedure as in Example 1. This bead material was also sufficiently practical.

Comparative Example 1 A reinforcing fiber bundle was heated for 60 seconds with a preheater heated to 200 ° C.
A bead material having the properties shown in Table 2 was obtained in the same manner as in Example 1 except that the nylon resin was impregnated and coated under a pressure of cm ² . For comparison, the results of Example 1 are also shown in Table 2. The obtained bead material had no resin impregnated layer in the single fiber, and only the surface portion of the fiber bundle was covered with the resin. For this reason, the twist width when applied to the forming former is as large as 32 mm, and the groove separation rate is 3 mm.
It was as high as 5%. In addition, the molded tire was warped and did not heal. Since the rim fit of the tire thus obtained was low and the breaking water pressure was low, the tire was unusable and could not be used.

Comparative Example 2 1500 denier / 1000
Except that two "Technola" yarns (para-aramid fiber manufactured by Teijin Limited) were prepared and twisted at a twist number of 20 turns / m to form one reinforcing fiber bundle. In the same manner as in Example 1, a bead material having various properties shown in Table 2 was obtained. When the obtained bead material was examined in detail, it was found that the fiber diameter was too small and the tensile strength was weak, and distortion was generated in the bicycle tire forming process, and was not corrected.
If a tire is to be formed using this bead, the bead material must be turned for 14 turns, which requires a very long time for the forming operation and cannot be put to practical use in terms of cost.

Comparative Example 3 1500 denier / 1000
Four "Technola" filament yarns (para-aramid fiber manufactured by Teijin Limited) are aligned and twisted at a twist rate of 20 twists / m to form one reinforcing fiber bundle, impregnated with epoxy resin, and dried. Except that it was made into one resin-impregnated fiber bundle.
By carrying out in the same manner as in Example 1, a bead material having various physical properties shown in Table 2 was obtained. The obtained bead material was very hard without a layer consisting only of fibers and a layer consisting only of resin. Also, the tensile strength was weak, and twisting occurred in the bicycle tire molding process, and the bicycle tire did not recover. Furthermore, the tire obtained from this bead material is bent when folded,
After that, even if it returned to the original circular state, it could not be restored. Such tires could not be put to practical use because of their low rim fit and low breaking water pressure.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

The bead material for a bicycle tire of the present invention is lightweight because it is made by coating a surface of a reinforcing organic fiber bundle with a resin impregnated surface, and has excellent folding properties because it has a three-layer structure as described above. As a result, the tire obtained therefrom has extremely good handleability. Further, when the tire is molded, the tire is hardly detached from the molding former and has excellent shape retention, so that the productivity of the tire is significantly improved. In addition, it is much lighter than conventional steel wires, does not rust, and has the same or better characteristics.
In addition, it can be completely incinerated at the time of disposal, which can greatly contribute to global environmental protection.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus for producing a bead material for a bicycle tire according to the present invention.

FIG. 2 is a schematic view of a cross section of a bead material for a bicycle tire of the present invention cut in a direction perpendicular to a length direction.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fiber bundle for reinforcement 2 bobbin 3 guide guide 4 front tension control device 5 preheater 6 guide guide 7 introduction nipple 8 resin pool 9 outlet die 10 throat 11 screw 12 die head 13 reshaping nozzle 14 guide guide roller 15 cooling bath 16 Rear tension control device 17 Take-up roll 18 Winding machine 21 Innermost layer (fiber layer) radius 22 Intermediate layer (fiber + resin layer) thickness 23 Outermost layer (resin layer) thickness

Claims (6)

[Claims] 1. A bicycle tire bead material comprising a linear composite material in which a reinforcing organic fiber bundle is impregnated with a resin and surface-coated, wherein the cross-section of the linear composite material is an innermost layer comprising only the reinforcing organic fiber, A bead material for a bicycle tire, comprising: an intermediate layer in which a resin is impregnated between single fibers of a reinforcing organic fiber; and an outermost layer consisting of only a coating resin. 2. The method according to claim 1, wherein the radius of the innermost layer and the thickness of the intermediate layer and the outermost layer are each 0.1 mm of the cross-sectional radius R of the linear composite material.
20 to 0.95 times, 0.04 to 0.50 times, 0.01 to
The bead material for a bicycle tire according to claim 1, which is 0.30 times. 3. The bead material for a bicycle tire according to claim 1, wherein a ratio D / R between a minimum radius of curvature D of the linear composite material and a cross-sectional radius R of the linear composite material is 150 or less. 4. The bead material for a bicycle tire according to claim 1, wherein the resin impregnated between the single fibers of the reinforcing organic fiber and coated on the surface is a thermoplastic resin. 5. The bead material for a bicycle tire according to claim 1, wherein the fibers constituting the reinforcing organic fiber bundle are para-aramid fibers. 6. The reinforcing organic fiber bundle has a total fineness of 4,000 to 6,000.
The bead material for a bicycle tire according to claim 1, which has a denier of 20,000.