Patent Description:
The present invention relates to a reinforcing ply capable of enhancing fracture resistance of a bicycle tire and to a bicycle tire having excellent fracture resistance.

Bicycle tires include a carcass part that forms a frame of the tire thereinside and a tread part on a side of a ground contact surface between the ground and the tire. In addition, a reinforcing ply is provided on the bicycle tire to protect the tire from stones, glass, metal pieces, etc. existing on the ground. However, there is a likelihood that lightweight properties required for a bicycle tire cannot be realized due to the presence of the reinforcing ply. Taking this problem into consideration, for example, Patent Document <NUM> (<CIT>) discloses a bicycle tire comprising: a reinforcing ply which comprises multi filament threads of more than <NUM> thermoplastic liquid crystal polyester filaments; a tread portion; and a carcass portion.

The Patent Document <NUM> teaches that, since the reinforcing ply is constituted by multifilament threads of more than <NUM> thermoplastic liquid crystal polyester filaments, the bicycle tire has improved resistance to perforation with a reduced weight.

Another bicycle tire is known from <CIT>, which is prio art according to Article <NUM>(<NUM>) EPC. This bicycle tire is provided with a reinforcing ply comprising a woven fabric made of polyvinyl alcohol-series fiber yarns , wherein each of the yarns includes a plurality of single fibers having an average fiber diameter of <NUM> or smaller.

Patent Document <NUM>, however, merely confirms the puncture resistance by pressing a blade-shaped stylus (Stichel) to the tire. On the other hand, there are many causes for puncture of tires (flat tire). For example, where a bicycle runs on an uneven surface or a step on the road surface, a tire puncture so-called pinch flat may occur, or the tire itself may be destroyed. Such a tire puncture/destruction occurs because fracture resistance of the bicycle tire is not good enough. Therefore, there is a demand for tires that are less likely to break down even when running on rough roads with obstacles such as stones and protrusions. In other words, development of a tire with high fracture resistance is desired.

Therefore, an object of the present invention is to provide a reinforcing ply contributing to improved fracture resistance of bicycle tires and to provide a bicycle tire having excellent fracture resistance.

The inventors of the present invention have conducted intensive studies to achieve the above object and have found that where a woven fabric comprising liquid crystalline polyester fiber yarns is used as a reinforcing ply for a bicycle tire in a condition that the liquid crystalline polyester fiber yarns have not only a specific average fiber diameter of single fibers but also a specific relationship between this average fiber diameter and the number of the single fibers in the fiber yarn, the woven fabric comprising liquid crystalline polyester fiber yarns can unexpectedly enhance fracture resistance of the bicycle tire.

Based on these findings, the present inventors have accomplished the present invention by providing a bicyle-tire reinforcing ply according to claim <NUM>.

Preferably, when both surfaces of the woven fabric are provided with unvulcanized rubber sheets and are heated so as to be vulcanized under pressure to give a specimen having a thickness of <NUM>, the specimen has a maximum load of <NUM> N or more (preferably <NUM> N or more, more preferably <NUM> N or more, for example, <NUM> N or less) in a penetration test.

Preferably, the woven fabric is a plain weave fabric or a cord fabric.

Preferably, the woven fabric is constituted by mutually intersecting the liquid crystalline polyester fiber yarns.

Preferably, the crystalline polyester fiber yarn has a twist number of <NUM> to <NUM> turns110 cm (preferably <NUM> to <NUM> turns/<NUM>, more preferably <NUM> to <NUM> turns/<NUM>).

Preferably, the number of single fibers per said fiber yarn is <NUM> or less.

Preferably, the single fibers have an average fiber diameter of <NUM> or larger.

Preferably, the reinforcing ply further comprising a woven fabric comprising polyvinyl alcohol-series fiber yarns, each of the fiber yarns comprising a plurality of single fibers having an average fiber diameter of <NUM> or smaller.

A bicycle tire at least comprising a tread part provided to a ground contact surface of the bicycle tire; and a carcass part provided inside the tread part, wherein the bicycle tire comprises a reinforcing ply as defined by any of claims <NUM>-<NUM> in at least one position selected from between the tread part and the carcass part, inside the carcass part, and inside the tread part.

According to a reinforcing ply of the present invention, the liquid crystalline polyester fiber yarns comprise single fibers having a specific average fiber diameter, and the number of single fibers included in the fiber yarn has a specific relationship with the average fiber diameter. Since such liquid crystalline polyester fiber yarns constitute the woven fabric, the reinforcing ply comprising the woven fabric can enhance fracture resistance of a bicycle tire. As a result, tire punctures caused by insufficient fracture resistance of bicycle tires, in particular pinch flat (punctures caused by making rim hit), can be advantageously prevented. In particular, the reinforcing ply of the present invention can further improve the fracture resistance of bicycle tires where the fiber diameter of the single fibers constituting the liquid crystalline polyester fiber yarn is larger.

The present invention will be more clearly understood from the following description of preferred examples thereof, when taken in conjunction with the accompanying drawings. However, the examples and the drawings are given only for the purpose of illustration and explanation, and are not to be taken as limiting the scope of the present invention in any way whatsoever, which scope is to be determined by the appended claims. In the figures,.

A reinforcing ply of the present invention is a bicycle-tire reinforcing ply (plies), the reinforcing ply at least comprising a woven fabric that comprises liquid crystalline polyester fiber yarns, each of the fiber yarns being formed from <NUM> or more single fibers. It should be noted that the reinforcing ply or plies may comprise one or more layers of woven fabrics. Where a plurality of layers of woven fabrics are included in a reinforcing ply, it may only include woven fabrics comprising liquid crystalline polyester fiber yarns or may include a combination of a woven fabric comprising liquid crystalline polyester fiber yarns and a woven fabric comprising a material other than the liquid crystalline polyester fiber yarns.

The liquid crystalline polyester fiber yarn comprises <NUM> or more single fibers of liquid crystalline polyester. The liquid crystalline polyester fiber may be any fiber of a thermoplastic polymer capable of forming an optically anisotropic molten phase. For example, preferable one may include a wholly aromatic polyester fiber (polyarylate fiber) having a thermoplastic property.

The liquid crystalline polyester fiber (for example, wholly aromatic polyester fiber) can be obtained by melt spinning the liquid crystalline polyester (for example, wholly aromatic polyester). The wholly aromatic polyester comprises repeating structural units derived from, for example, aromatic diols, aromatic dicarboxylic acids, aromatic hydroxycarboxylic acids, etc. The chemical structure of the repeating structural units derived from aromatic diols, aromatic dicarboxylic acids, or aromatic hydroxycarboxylic acids is not limited to a specific one as long as it does not undermine the effects of the present invention. Further, the wholly aromatic polyester may contain structural units derived from aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids in a range which does not spoil the effect of the present invention. Examples of preferable structural units may include units shown in Table <NUM>.

In the structural units of Table <NUM>, m is an integer of <NUM> to <NUM>. Further, Y in the formulae independently represents, as from one substituent to a replaceable maximum number of substituents, hydrogen atom, a halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), an alkyl group (for example, an alkyl group having <NUM> to <NUM> carbon atoms such as methyl group, ethyl group, isopropyl group, t-butyl group, etc.), an alkoxy group (for example, methoxy group, ethoxy group, isopropoxy group, n-butoxy group, etc.), an aryl group (for example, phenyl group, naphthyl group, etc.), an aralkyl group [benzyl group (phenylmethyl group), phenethyl group (phenylethyl group), etc.], an aryloxy group (for example, phenoxy group, etc.), an aralkyloxy group (for example, benzyloxy group, etc.), and the like.

More preferable structural units may include the structural units described in Examples (<NUM>) to (<NUM>) shown in Tables <NUM>, <NUM>, and <NUM> below. Where the structural unit in the formula is a structural unit capable of configuring a plurality of structures, two or more such structural units may be combined and used as the structural unit constituting the polymer.

In the structural units of Tables <NUM>, <NUM>, and <NUM>, n is an integer of <NUM> or <NUM>, among each of the structural units, n = <NUM> and n = <NUM> may independently exist, or may exist in combination; each of the Y<NUM> and Y<NUM> independently represents, hydrogen atom, a halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), an alkyl group (for example, an alkyl group having <NUM> to <NUM> carbon atoms such as methyl group, ethyl group, isopropyl group, t-butyl group, etc.), an alkoxy group (for example, methoxy group, ethoxy group, isopropoxy group, n-butoxy group, etc.), an aryl group (for example, phenyl group, naphthyl group, etc.), an aralkyl group [benzyl group (phenylmethyl group), phenethyl group (phenylethyl group), etc.], an aryloxy group (for example, phenoxy group, etc.), an aralkyloxy group (for example, benzyloxy group, etc.), and the like. Of these, preferable one may include hydrogen atom, chlorine atom, bromine atom, or methyl group.

Further, Z may include substituents represented by the following formulae.

Preferable wholly aromatic polyester may comprise a combination of a structural unit having a naphthalene skeleton. Especially preferable one may include both the structural unit (A) derived from hydroxybenzoic acid and the structural unit (B) derived from hydroxynaphthoic acid. For example, the structural unit (A) may have a following chemical formula (A), and the structural unit (B) may have a following chemical formula (B). From the viewpoint of improving melt-spinnability, the ratio of the structural unit (A) and the structural unit (B) may be preferably in the range of former/latter of from <NUM>/<NUM> to <NUM>/<NUM>, more preferably from <NUM>/<NUM> to <NUM>/<NUM>, and even more preferably from <NUM>/<NUM> to <NUM>/<NUM>. <CHM>
<CHM>.

Further, the total proportion of the structural units of (A) and (B) may be, based on all the structural units, for example, for example, <NUM> mol% or more, more preferably <NUM> mol% or more, and further preferably <NUM> mol% or more. Among the liquid crystalline polyester, a wholly aromatic polyester having the structural unit (B) at a proportion of from <NUM> to <NUM> mol% is particularly preferable.

The melting point of the wholly aromatic polyester preferably used in the present invention is preferably in the range of from <NUM> to <NUM>, more preferably from <NUM> to <NUM>. The melting point referred to here is a main absorption peak temperature observed by measuring using a differential scanning calorimeter (DSC) in accordance with JIS K <NUM> test method. Specifically, after taking <NUM> to <NUM> of a sample encapsulated in an aluminum pan into the DSC device, nitrogen is introduced as a carrier gas at a flow rate of <NUM>/min. and a heating rate of <NUM>/min. , the position of an appearing endothermic peak is measured. In some kinds of polymer, where a clear peak does not appear in the first run in the DSC measurement, it is advisable that after heating the sample to a temperature <NUM> higher than the flow temperature expected with a heating rate of <NUM>/min. and retaining at that temperature for <NUM> minutes so as to make the sample to be completely molten, and the melt is quenched to <NUM> at a rate of -<NUM>/min. Subsequently, the quenched material is reheated at a heating rate of <NUM>/min. , and the position of an appearing endothermic peak may be recorded.

As long as the effects of the present invention are not impaired, the above liquid crystalline polyester (particularly, wholly aromatic polyester) may be blended with thermoplastic polymers such as a polyethylene terephthalate, a modified polyethylene terephthalate, a polyolefin, a polycarbonate, a polyamide, a polyphenylene sulfide, a polyether ether ketone, a fluoro-resin, etc. Further, the above liquid crystalline polyester may be combined with various additives such as inorganic substances (for example, titanium oxide, kaolin, silica, barium oxide), carbon black, colorants such as dyes and pigments, antioxidants, ultraviolet absorbers, and light stabilizers.

In the present invention, method of producing fibers from the liquid crystalline polyester is not limited to a specific one as long as liquid crystalline fibers have a property of being meat-meltable at least at a part of the fiber surface. Usually, fibers obtained by melt spinning can be used. Melt spinning can be performed by a known or conventional method, for example, in the melt spinning, a fiber-formable resin is melted in an extruder and thereafter the melt is discharged from a nozzle at a predetermined spinning temperature so as to obtain a liquid crystalline polyester fiber.

The liquid crystalline polyester fiber yarn comprises three or more single fibers, and the average fiber diameter of the single fibers is <NUM> or larger. In order for the liquid crystalline polyester fiber yarn to exhibit fracture resistance when used as a reinforcing ply, the average fiber diameter of the single fibers constituting the liquid crystalline polyester fiber yarn and the number of single fibers have a specific relationship such that the product of the number of single fibers and the average fiber diameter (µm) is <NUM> or less. That is, [No. of single fibers per fiber yarn] × [average fiber diameter (µm)] ≤ <NUM>. This indicates that an inverse proportional relationship is established between the average fiber diameter and the number of single fibers in order to exhibit fracture resistance when used as a reinforcing ply.

That is, in the present invention, where the average fiber diameter of the single fibers is <NUM> or larger, the load that can be supported by the fiber yarns constituted by these single fibers can be increased. On the other hand, since this reinforcing ply is used for bicycle tires, there is an upper limit to the size of the average fiber diameter and the number of single fibers constituting the fiber yarn in forming the fiber yarn. However, by adjusting the size of the average fiber diameter and the number of single fibers constituting the fiber yarn within a specific range, it is possible to improve the fracture resistance when used as a reinforcing ply while well-enabling forming a woven fabric as the fiber yarn.

The average fiber diameter of the liquid crystalline polyester single fibers constituting the liquid crystalline polyester fiber yarn may be preferably <NUM> or larger, more preferably <NUM> or larger, still more preferably <NUM> or larger, and particularly preferably <NUM> or larger. The upper limit of the average fiber diameter of the liquid crystalline polyester single fibers can be appropriately set depending on the number of the liquid crystalline polyester single fibers, and may be, for example, <NUM> or smaller, preferably <NUM> or smaller, more preferably <NUM> or smaller, still more preferably about <NUM> or smaller. The average fiber diameter is a value measured by the method described in Examples below. It should be noted that where the liquid crystalline polyester single fiber has a modified cross section, the fiber diameter of the single fiber may be a value measured from a circumscribed circle diameter of the cross-sectional shape.

The number of liquid crystalline polyester single fibers constituting the liquid crystalline polyester fiber yarn can be appropriately set depending on the average fiber diameter of the liquid crystal polyester single fibers, and may be preferably <NUM> or more, and more preferably <NUM> or more. The upper limit of the number of single fibers can be appropriately set depending on the average fiber diameter of the liquid crystalline polyester single fibers, and may be, for example, <NUM> or less, preferably <NUM> or less, more preferably <NUM> or less.

The product of the number of single fibers in the fiber yarn and the average fiber diameter (µm) can be appropriately set depending on the values of the average fiber diameter and the number of single fibers, and may be preferably about <NUM> to <NUM>, more preferably about <NUM> to <NUM>.

The fiber yarns are not particularly limited as long as they can be used as weaving yarns, and may be any of filament yarns, spun yarns, and composite yarns, and the fiber yarns are preferably filament yarns.

The fiber yarns may be untwisted or twisted to have the number of twists of, for example, <NUM> to <NUM> turns/<NUM>, preferably <NUM> to <NUM> turns/<NUM>, more preferably <NUM> to <NUM> turns/<NUM>. Although the warp yarns and the weft yarns may be twisted in the same direction or in different directions, they may preferably be twisted in the same direction. It should be noted that the number of twists (times/cm) indicates the number of twists included in the fiber yarns of <NUM>, which is a value measured by the method described in Examples below.

For example, the liquid crystalline polyester fiber yarns may have a fiber tenacity of, for example, <NUM> cN/dtex or higher, preferably <NUM> cN/dtex or higher, and more preferably <NUM> cN/dtex or higher. Although an upper limit for the fiber tenacity is not particularly limited, the fiber tenacity may be, for example, <NUM> cN/dtex or lower, or <NUM> cN/dtex or lower. It should be noted that the fiber tenacity is measured in accordance with the method described in the Examples below.

The liquid crystalline polyester fiber yarns may be subjected to post-processing if needed. Preferable post-processing may include bulk texturing such as, for example, twisting/thermally fixing/untwisting, false twisting, stuffing, shaping, edge-crimping, and taslanizing. Of these post-processing, taslanizing is preferred which does not cause stretching and/or shrinkage of fibers. In the taslanizing texturing, high-pressure turbulent air is applied to bundle of filaments in parallel to make the filaments entangled, so that bulky texture can be imparted to the filaments.

The woven fabric may have a sheet form in which warp yarns and weft yarns are interlaced in accordance with a predetermined rule. For example, woven fabric weaves may include a plain weave, a twill weave, a satin weave, and a cord weave, and the plain weave and the cord weave are preferred. The liquid crystalline polyester fiber yarns may be used for both warp yarns and weft yarns or either warp yarns or weft yarns. The liquid crystalline polyester fiber yarns are preferably used at least for warp yarns; more preferably, the liquid crystalline polyester fiber yarns are interlaced with each other; and, most preferably, the whole woven fabric is made of the liquid crystalline polyester fiber yarns.

Further, the warp and/or weft yarns constituting the woven fabric preferably have a flattened shape [for example, a shape in which the yarn width (the maximum diameter of the fiber yarn) of the warp and/or weft yarns is <NUM> to <NUM> times larger than the yarn thickness (the minimum diameter of the fiber yarn) of the warp and/or weft yarns]. For example, the yarn width of the warp and/or weft yarns may be about <NUM> to <NUM>, more preferably about <NUM> to <NUM>.

In order to suppress gaps appeared in a weave, the woven fabric may have a warp yarn density of, for example, <NUM> yarns/<NUM> or greater and preferably <NUM> yarns/<NUM> or greater. Although the upper limit of the warp yarn density may be suitably selected depending on types of woven fabrics, the warp yarn density may be, for example, <NUM> yarns/<NUM> or less. The warp yarn density is measured in accordance with the method described in the Examples below.

In order to achieve a desired fracture resistance, the woven fabric may have a basis weight of preferably <NUM>/m<NUM> or greater, more preferably <NUM>/m<NUM> or greater, and still more preferably <NUM>/m<NUM> or greater. On the other hand, in terms of weight reduction of the tire, the woven fabric may have a basis weight of preferably <NUM>/m<NUM> or lower, preferably <NUM>/m<NUM> or lower, and still more preferably <NUM>/m<NUM> or lower. The basis weight is measured in accordance with the method described in the Examples below.

In terms of weight lightening, the woven fabric used per one tire may have a weight (unit: g) of, for example, <NUM> × L or lower, preferably <NUM> × L or lower, and more preferably <NUM> × L or lower and may be, for example, <NUM> × L or greater, where L denotes a circumference (unit: m) of the tire. For general bicycles, the weight of the woven fabric may be, for example, <NUM> or lower, more preferably <NUM> or lower, and even more preferably <NUM> or lower, and may be, for example, <NUM> or greater.

In order to achieve a desired fracture resistance and a desired thinness in a compatible manner, the woven fabric may have a thickness of, for example, about <NUM> to <NUM>, preferably about <NUM> to <NUM>, and more preferably about <NUM> to <NUM>.

Further, in addition to the woven fabric constituted by the liquid crystalline polyester fiber yarns, a woven fabric of polyvinyl alcohol-series (PVA-series) fiber yarns constituted by a plurality of single fibers having an average fiber diameter of <NUM> or less may be further included in the reinforcing ply. Since the woven fabric of the PVA-series fiber yarns has excellent puncture resistance, such a reinforcing ply can exhibit a desired fracture resistance and a desired puncture resistance in a compatible manner. The woven fabric constituted by the PVA-series fiber yarns can be produced depending on the production conditions of the woven fabric constituted by the liquid crystal polyester fiber yarns.

The obtained woven fabric may be directly used as a reinforcing ply, or, if needed, the woven fabric (i) may be subjected to pretreatment, such as resorcinol formalin (formaldehyde) latex (RFL) treatment to be used as a reinforcing ply, and/or (ii) may be provided with a rubber layer on at least one surface of the woven fabric to be used as a reinforcing ply. By performing the pretreatment of (i) above, the adhesiveness with the rubber layer can be improved.

The RFL treatment can be performed by immersing the woven fabric into a solution for RFL treatment (or RFL solution) or applying the RFL solution to the woven fabric. An adhesiveness improver for polyester fibers, such as a chlorphenol-based adhesive, may be added to the RFL solution. Such an adhesive improver for polyester fibers is marketed as, for example, Denabond (trade name) from Nagase ChemteX Corporation. The molar ratio of [R (resorcinol)IF (formaldehyde)] in the RFL solution may be in a range of, for example, from <NUM>/<NUM> to <NUM>/<NUM>, preferably from <NUM>/<NUM> to <NUM>/<NUM>, and more preferably from <NUM>. <NUM> to <NUM>/<NUM>. Further, a weight ratio of [RF (resorcinol and formaldehyde)/L (latex)] may be in a range of, for example, from <NUM>/<NUM> to <NUM>/<NUM>, preferably from <NUM>/<NUM> to <NUM>/<NUM>, and more preferably from <NUM>/<NUM> to <NUM>/<NUM>. The solid content weight ratio of [RFL / adhesiveness improver for polyester fiber] may be in a range of, for example, from <NUM>/<NUM> to <NUM>/<NUM>, and preferably from <NUM>/<NUM> to <NUM>/<NUM>.

Various types of rubber latex may be used as the latex, including, for example, a natural rubber latex, a styrene-butadiene rubber latex, an acrylonitrile-butadiene rubber latex, a chloroprene rubber latex, a vinyl pyridine-styrene-butadiene rubber latex, and an ethylene-propylene-nonconjugated diene terpolymer rubber latex. These types of rubber latex may be used singly or in combination. Among these, it is preferred to use a styrene-butadiene rubber latex or a vinyl pyridine-styrene-butadiene terpolymer rubber latex.

It should be noted that preprocessing may be performed using an epoxy compound and/or an isocyanate compound prior to the RFL treatment, if needed. In such preprocessing, the epoxy compound and/or the isocyanate compound may be applied by mixing a known or conventional compound into an organic solvent or water and immersing the woven fabric into the obtained treatment solution or coating the solution to the woven fabric. As the water-soluble aliphatic epoxy resin, for example, the Denacol series manufactured by Nagase ChemteX Corporation can be used.

Where the woven fabric in combination with a rubber layer(s) is used as a reinforcing ply, the rubber layer may be provided to, for example, only one surface or both surfaces of the woven fabric. The rubber layer may be, for example, in the form of a sheet-like product having a thickness in a range from about <NUM> to <NUM>, preferably from about <NUM> to <NUM>, and even more preferably from about <NUM> to <NUM>. The rubber layer preferably covers the whole woven fabric.

Examples of rubber constituting the rubber layer may include a natural rubber, a styrene-butadiene rubber, an acrylonitrile-butadiene rubber, a chloroprene rubber, a vinyl pyridine-styrene-butadiene rubber, and an ethylene-propylene-nonconjugated diene terpolymer rubber as a single body or a blend of two or more rubbers. The rubber is preferably a vulcanizable rubber. From the viewpoint of adhesive property, the rubber layer is preferably a layer of vulcanized rubber that is heated under pressure.

Where the reinforcing ply comprises an RFL-treated woven fabric in combination with a rubber layer(s), the rubber latex used in the RFL treatment may be the same type as the rubber(s) of the rubber layer(s), or may be different type from the rubber(s) of the rubber layers. Preferably, the rubber latex used in the RFL treatment may be the same type as the rubber(s) of the rubber layer(s).

Where the rubber layer is provided, the reinforcing ply including the woven fabric and the rubber layer(s) may have a total thickness, for example, in a range from <NUM> to <NUM>, preferably from <NUM> to <NUM>, and even more preferably from <NUM> to <NUM>.

For example, where a specimen is prepared by superposing unvulcanized rubber sheets on both surfaces of the woven fabric and heating the superposed material under pressure to make the rubber sheets vulcanized, the specimen (<NUM> long × <NUM> wide, about <NUM> thick) in which the rubber sheets are integrated to the woven fabric may have a maximum load of, for example, preferably <NUM> N or higher, more preferably <NUM> N or higher, and even more preferably <NUM> N or higher in the penetration test in which a plunger (a cylindrical object with a spherical tip with a diameter of <NUM>) is applied to the center of the woven fabric in the condition that the periphery of the specimen, excluding a circle having a diameter of <NUM> at the center of the specimen, is fixed. Although the higher maximum load is more preferable, the usual maximum load is about <NUM> N. The maximum load may be measured in accordance with the method described in the Examples below. It should be noted that the specimen is heated under pressure in a mold so as to have a thickness adjusted to about <NUM> (<NUM> to <NUM>).

A bicycle tire according to the present invention at least comprises: a tread part provided to a ground contact surface of the bicycle tire; and a carcass part provided inside the tread part, wherein the bicycle tire comprises the reinforcing ply in at least one position selected from between the tread part and the carcass part, inside the carcass part, and inside the tread part. The bicycle tire may have a thickness, for example, from <NUM> to <NUM>, preferably from <NUM> to <NUM>, more preferably from <NUM> to <NUM>, where the thickness of the bicycle tire is measured at the ground contact surface.

The tread part is typically made of rubber. The carcass part at least includes a woven fabric, and if necessary, the woven fabric may be surrounded by a rubber layer(s) as a cover. The rubber constituting the rubber layer of the reinforcing ply may be the same type as the rubber(s) constituting the tread part and/or the carcass part, or may be different type from the rubber(s) constituting the tread part and/or the carcass part. Preferably, the rubber constituting the rubber layer of the reinforcing ply may be the same type as the rubber(s) constituting the tread part and/or the carcass part.

The reinforcing ply is preferably disposed such that a direction of the warp yarns of the woven fabric is diagonal to a center line of the tire cross section in a circumferential direction. The direction of the warp yarns of the woven fabric may be angled relative to the center line at an angle, for example, from <NUM> to <NUM>° and preferably from <NUM> to <NUM>°.

Hereinafter, embodiments of the bicycle tire of the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the illustrated embodiments. In <FIG>, like reference numerals are used to denote like features, and description thereof is omitted.

<FIG> shows a schematic sectional view of a bicycle tire according to a first embodiment of the present invention. As shown in <FIG>, a bicycle tire <NUM> according to the first embodiment of the present invention includes: a tread part <NUM> configured to be in contact with the ground; and a carcass part <NUM> that is a frame part of the tire. The carcass part <NUM> is provided under the tread part <NUM> towards a direction of a rotary shaft of the bicycle tire, and the reinforcing ply <NUM> is disposed between the tread part <NUM> and the carcass part <NUM>.

The carcass part <NUM> may be, for example, formed in such a way that one or more layers of carcass woven fabrics are covered by a rubber layer(s) each having a predetermined thickness. If needed, the carcass woven fabric(s) may embrace bead wires <NUM> at opposite ends of the carcass part <NUM>. Examples of the bead wires <NUM> may include metal wires, and organic-fiber ropes or inorganic-fiber ropes.

For example, the bicycle tire <NUM> shown in <FIG> is a skin sidewall tire, and the carcass part <NUM> include: sidewall parts <NUM> that are side surfaces of the tire; and bead parts <NUM> that are fixing parts to a rim (not illustrated). In the bead parts <NUM>, opposite parts of the carcass woven fabric (not illustrated) constituting the carcass part <NUM> embrace the bead wires <NUM>, respectively, and the carcass woven fabric and the bead wires <NUM> are integrated by allowing them to be covered with rubber from outside to form the bead parts <NUM>.

Although the tread part <NUM> only needs to be provided to a portion that comes into direct contact with the road, it may extend toward the sidewall parts <NUM>, if needed. In terms of weight reduction, it is preferable that the tread part is principally provided to the ground contact part of the tire, and that the tread part may have extended parts toward each sidewall part in a width direction, in which each of the extended part has a width of equal to or smaller than a half of the width of the sidewall part.

Where the reinforcing ply <NUM> is provided outside the carcass part <NUM> and inside the tread part <NUM> (i.e., where the reinforcing ply <NUM> is provided between the carcass part <NUM> and the tread part <NUM>), the reinforcing ply <NUM> is preferably provided within a range smaller than the width of the tread part <NUM> such that the reinforcing ply is substantially centered at the center line Y of the tire cross section shown in <FIG> in the circumferential direction X. For example, the reinforcing ply <NUM> may have a width in a range from <NUM> to <NUM>% of the width of the tread part <NUM>, preferably from <NUM>% to <NUM>%, and more preferably from <NUM> to <NUM>%. It should be noted that each of these widths refers to a length between opposite ends of each part in the circumferential direction X in the tire cross section shown in <FIG> (that is, the longitudinal length of the width when the part in the width direction is longitudinally straightened).

<FIG> shows a schematic sectional view of a bicycle tire according to a second embodiment of the present invention. As shown in <FIG>, a bicycle tire <NUM> according to the second embodiment of the present invention includes: a tread part <NUM> configured to be in contact with the ground; and a carcass part <NUM> that is a frame part of the tire. The reinforcing ply <NUM> is disposed inside the carcass part <NUM>.

The carcass part <NUM> may include a plurality of carcass woven fabrics (not illustrated) in at least a position where the reinforcing ply <NUM> is disposed. In such a case, the reinforcing ply <NUM> may be interposed between the carcass woven fabrics inside the carcass part <NUM>. Preferably, the reinforcing ply <NUM> is provided inside the carcass part <NUM> such that the reinforcing ply <NUM> is substantially centered at the center line Y of the tire cross section shown in <FIG> in the circumferential direction X. For example, the reinforcing ply <NUM> may have a width in a range from <NUM> to <NUM>% of the width of the tread part <NUM>, preferably from <NUM> to <NUM>%, and more preferably <NUM> to <NUM>%. It should be noted that each of these widths refers to a length between opposite ends of each part of the tire cross section in the circumferential direction X.

<FIG> shows a schematic sectional view of a bicycle tire according to a third embodiment of the present invention. As shown in <FIG>, a bicycle tire <NUM> according to the third embodiment of the present invention includes: a tread part <NUM> configured to be in contact with the ground; and a carcass part <NUM> that is a frame part of the tire. The reinforcing ply <NUM> is disposed inside the tread part <NUM>.

The reinforcing ply <NUM> may be provided inside the tread part <NUM> such that the reinforcing ply <NUM> is substantially centered at the center line Y of the tire cross section shown in <FIG> in the circumferential direction X. For example, the reinforcing ply <NUM> may have a width in a range from <NUM> to <NUM>% of the width of the tread part <NUM>, preferably from <NUM> to <NUM>%, and more preferably from <NUM> to <NUM>%. It should be noted that each of these widths refers to a length between opposite ends of each part of the tire cross section in the circumferential direction X.

Where the tread part <NUM> is provided with groove parts, the reinforcing ply <NUM> is preferably disposed to such an extent that the reinforcing ply <NUM> is not exposed outside the groove part.

Hereinafter, the present invention will be further described in detail with reference to Examples, which are not to be construed as limiting the scope of the present invention. In the following Examples and Comparative Examples, various physical properties were measured by the following methods.

Using an X-ray CT apparatus, cross sections of <NUM> fiber yarns that were randomly sampled from warp yarns and weft yarns of a woven fabric were observed to take two-dimensional images of the cross sections of <NUM> fiber yarns. In the two-dimensional images, <NUM> single fibers were randomly selected from each of the <NUM> fiber yarns, and fiber diameter of each of the single fibers were measured, and the resulting <NUM> fiber-diameter data were averaged up so as to obtain an average fiber diameter. When the number of single fibers constituting one fiber yarn is less than <NUM>, all of the single fibers constituting the fiber yarn are subjected to measurement of fiber diameter, and all the resulting fiber-diameter data obtained from <NUM> fiber yarns were averaged up so as to obtain an average fiber diameter.

In accordance with section <NUM>. <NUM> of JIS L <NUM> "Testing methods for chemical fiber filament yarns," a fiber tenacity was measured.

A woven fabric was placed on a flat table to remove unnatural wrinkles and tension, and thereafter, three different locations of the woven fabric were observed using a digital microscope (VHX-<NUM>, manufactured by Keyence Corporation) that had a measurement function. In such a manner, thread width of <NUM> fiber yarns per one location were measured, and the resulting <NUM> thread-width data were averaged up so as to obtain a thread width per fiber yarn.

In accordance with section <NUM>. <NUM> of JIS L <NUM> "Testing methods for general woven fabrics," a warp yarn density was measured.

Referring to section <NUM> of JIS L <NUM> "Testing methods for chemical fiber filament yarns," number of twists included in <NUM> fiber yarn was measured by setting the gripping interval of the twisting machine to <NUM>.

In accordance with section <NUM>. <NUM> of JIS L <NUM> "Testing methods for general woven fabrics," a basis weight of a woven fabric was measured.

In accordance with section <NUM> of JIS L <NUM> "Testing methods for general woven fabrics," a thickness of a woven fabric was measured.

A specimen (<NUM> long × <NUM> wide, <NUM> thick) was obtained by preparing a woven fabric and unvulcanized rubber sheets each having a thickness of <NUM> and containing sulfur (containing natural rubber (RSS#<NUM>) and SBR rubber (commercial name "Nipol <NUM>") mixed at a weight ratio of <NUM>/<NUM>); arranging the rubber sheets on both sides of the woven fabric; placing the woven fabric and the rubber sheets in a mold capable of producing a specimen having a thickness of <NUM>; and heating them at a temperature of <NUM> and pressure of <NUM>/cm<NUM> for <NUM> minutes such that the rubber sheets were vulcanized and bonded to the woven fabric by thermocompression to be integrated together. The woven fabric was previously subjected to the RFL treatment (the molar ratio of R/F: <NUM>/<NUM>; the weight ratio of RF/L: <NUM>/<NUM>). For "Vectran" ™ and "Kevlar" ™, Denabond (trade name) manufactured by Nagase ChemteX Corporation was added to the RFL treatment liquid as an adhesion improver for polyester ([RFL/Denabond solid content weight ratio] = <NUM>/<NUM>). A penetration test was performed to the obtained specimen, as shown in <FIG>, using a constant-speed penetration test machine with a plunger (diameter of spherical tip: <NUM>).

<FIG> shows a schematic sectional view of the constant-speed penetration test machine. A specimen <NUM> includes: a woven fabric <NUM> and vulcanized rubber layers <NUM>, <NUM> on upper and lower surfaced of the woven fabric <NUM>. The constant-speed penetration test machine includes: a plunger <NUM> that moves down at a constant speed, and fixing plates <NUM>, <NUM> that fix the specimen <NUM> on the upper and lower surfaces, respectively. The periphery of the specimen <NUM>, excluding a circle having a diameter of <NUM> at the center of which the plunger <NUM> penetrates, is fixed with the fixing plates <NUM>, <NUM>. A force with which the plunger <NUM> moving down at a speed of <NUM> per minute penetrated the specimen <NUM> was measured as a maximum load.

A plain weave fabric was prepared from "Vectran" ™ filaments (average single fiber diameter: <NUM>; number of single fibers per fiber yarn: <NUM>; twist number: <NUM> turns/<NUM>; fiber tenacity: <NUM> cN/dtex; manufactured by Kuraray Co. ) as liquid crystalline polyester fiber yarns for warp yarns and weft yarns. The obtained plain weave fabric had flattened shaped warp yarns and weft yarns. Table <NUM> shows performance evaluation of the obtained plain weave fabric.

A cord fabric was prepared from "Vectran" ™ filaments (average single fiber diameter: <NUM>; number of single fibers per fiber yarn: <NUM>; twist number: <NUM> turns/<NUM>; fiber tenacity: <NUM> cN/dtex; manufactured by Kuraray Co. ) as liquid crystalline polyester fiber yarns for warp yarns and weft yarns. The obtained cord fabric had flattened shaped warp yarns. Table <NUM> shows performance evaluation of the obtained cord fabric.

A plain weave fabric was prepared from "Vectran" ™ filaments (average single fiber diameter: <NUM>; number of single fibers per fiber yarn: <NUM>; twist number: <NUM> turns/ <NUM>; fiber tenacity: <NUM> cN/dtex; manufactured by Kuraray Co. ) as liquid crystalline polyester fiber yarns for warp yarns and weft yarns. The obtained plain weave fabric had flattened shaped warp yarns and weft yarns. Table <NUM> shows performance evaluation of the obtained plain weave fabric.

A plain weave fabric was prepared from Nylon <NUM> filaments (average single fiber diameter: <NUM>; number of single fibers per fiber yarn: <NUM>; twist number: <NUM> turns/<NUM>; fiber tenacity: <NUM> cN/dtex; manufactured by Toray Industries, Inc. ) as polyamide series fiber yarns for warp yarns and weft yarns. The obtained plain weave fabric had flattened shaped warp yarns and weft yarns. Table <NUM> shows performance evaluation of the obtained plain weave fabric.

A plain weave fabric was prepared from "Kevlar" ™ filaments (average single fiber diameter: <NUM>; number of single fibers per fiber yarn: <NUM>; twist number: <NUM> turns/<NUM>; fiber tenacity: <NUM> cN/dtex; manufactured by DU PONT-TORAY CO. ) as aromatic polyamide series fiber yarns for warp yarns and weft yarns. The obtained plain weave fabric had flattened shaped warp yarns and weft yarns. Table <NUM> shows performance evaluation of the obtained plain weave fabric.

A plain weave fabric was prepared from Vinylon filaments (average single fiber diameter: <NUM>; number of single fibers per fiber yarn: <NUM>; twist number: <NUM> turns/<NUM>; fiber tenacity: <NUM> cN/dtex; manufactured by Kuraray Co. ) as polyvinyl alcohol series fiber yarns for warp yarns and weft yarns. The obtained plain weave fabric had flattened shaped warp yarns and weft yarns. Table <NUM> shows performance evaluation of the obtained plain weave fabric.

As shown in Table <NUM>, in comparison of Examples <NUM> and <NUM> with Comparative Example <NUM>, Examples <NUM> and <NUM> exhibited higher fracture resistance than Comparative Example <NUM> although all of them were plain weave fabrics constituted by liquid crystalline polyester fiber yarns and had similar basis weight from each other. Considering of Patent Document <NUM> recitation that thinner single fibers led to better adhesiveness with the rubber compound, resulting in improvement in perforation, it is surprising that Examples <NUM> and <NUM> each comprising fiber yarns having thicker fiber diameter than that of Comparative Example <NUM> unexpectedly achieved higher fracture resistance of the plain weave fabrics in which vulcanized rubber layers were provided on both sides of the plain weave fabrics.

In addition, in comparison of Examples <NUM> and <NUM> with Comparative Example <NUM>, Examples <NUM> and <NUM> exhibited higher fracture resistance than Comparative Example <NUM> although all of them were cord fabrics constituted by liquid crystalline polyester fiber yarns and had similar basis weight from each other. In particular, it is unexpected results that although the number of single fibers was increased in order to overcome the fineness of the single fibers in Comparative Example <NUM>, fracture resistance of Examples <NUM> and <NUM> was higher than that of Comparative Example <NUM>.

As was expected, Comparative Examples <NUM> and <NUM> exhibited inferior fracture resistances compared to Examples <NUM> and <NUM> with higher tenacity than Comparative Examples <NUM> and <NUM>. On the other hand, although Comparative Example <NUM> exhibited similar fiber tenacity with that of Examples <NUM> and <NUM>, Examples <NUM> and <NUM> showed unexpectedly higher fracture resistance than that of Comparative Example <NUM>.

In addition, although the woven fabric constituted by Vinylon fiber yarns was recited as Comparative Example <NUM>, the woven fabric shows excellent puncture resistance subjected to penetration test using injection needle (diameter: <NUM> in which outer diameter of the needle of <NUM>; length: <NUM>, needle tip shape: regular bevel in which angle of a blade surface at a tip end portion of <NUM> degree) instead of plunger. Accordingly, when such a woven fabric is used together with a woven fabric constituted by liquid crystalline polyester fiber yarns, a reinforcing ply which has fracture resistance and puncture resistance in a compatible manner can be achieved.

Claim 1:
A bicycle-tire reinforcing ply (<NUM>, <NUM>, <NUM>) comprising a woven fabric that comprises liquid crystalline polyester fiber yarns, wherein each of the fiber yarns comprises three or more single fibers having an average fiber diameter of <NUM> or larger, and the fiber yarns satisfies the following formula: <MAT> wherein the reinforcing ply (<NUM>, <NUM>, <NUM>) comprises the liquid crystalline polyester fiber yarns as flattened warp yarns and/or flattened weft yarns, and the warp yarns and/or weft yarns have a thread width of <NUM> to <NUM>.