JP2009067323A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire attaining sure enhancement of traveling durability without causing weight increase of the tire by applying a reinforcement material using a polyketone fiber as cord fabric to the tire. <P>SOLUTION: The pneumatic tire is provided with a carcass ply 4 comprising a cord layer extending from a tread part 3 to both bead parts 1 via both side parts 2, fastened to the bead part 3 and arranged in an approximately radial direction. The cord of the carcass ply 4 contains at least 90 mass% or more of the polyketone fiber. The maximum thermal contraction stress as a dip-treated cord is within a range of 0.4-1.5 cN/dtex, and the thermal contraction ratio at 177°C×30 min. dry heat treatment is within a range of 1.8-3.6%. A deviation amount of a weft yarn cord approximately concentrically arranged at the inside of the tire in the form that it is approximately perpendicular to the cord of the carcass ply 4 from a concentric circle position at a tire side part is 50 mm or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more particularly to a pneumatic tire according to an improvement of a carcass ply forming a skeleton.

  A pneumatic tire generally includes a bead core provided in a pair of left and right bead portions and a cord layer arranged in a substantially radial direction, extends from the crown portion to both bead portions via both side portions, and is moored to the bead portion. It includes a carcass ply, and a belt and a tread that are disposed radially outward of the crown portion.

  Of these, various reinforcing cords such as rayon, nylon, polyester (polyethylene terephthalate (PET), etc.) have been studied and used as a reinforcing cord used for a carcass ply forming a tire skeleton. Recently, as an alternative to these conventional organic fiber materials, carbon monoxide and olefins obtained by polymerizing carbon monoxide and olefins such as ethylene and propene using palladium or nickel as a catalyst are substantially completely alternate. Studies are also being conducted on fiberizing a polymerized aliphatic polyketone and using it as a cord material. Polyketone fibers are known to have a higher melting point than conventional polyolefin fibers, and to have high strength and high elastic modulus. Utilizing these excellent physical properties, they can be used for industrial materials, especially tires, belts, hoses, etc. Development as a rubber reinforcing material is expected.

Regarding the reinforcing material using such polyketone fibers, for example, in Patent Document 1, in a weft fabric composed of warps and wefts, 50% by mass or more of the fibers constituting the warps are used as polyketone fibers, and warp and wefts An interwoven fabric having a fiber-fiber static coefficient of friction (μs) of 0.2 or more is disclosed.
JP 2003-49339 A

  However, even if a conventional reinforcing cord or reinforcing material made of tinted fabric using polyketone fibers is applied to a tire, there is a case where a sufficient improvement in performance may not always be expected.

  Therefore, an object of the present invention is to apply a reinforcing material made of a braided fabric using polyketone fibers to a tire, thereby realizing a pneumatic improvement in which the running durability is surely improved without causing deterioration of various performances of the tire. To provide tires.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the interwoven fabric using polyketone fibers has the following problems.
(A) The polyketone fiber itself having high strength and high elastic modulus, and the cord made of the polyketone fiber using the same have high heat shrinkage stress, and the weft constituting the weave fabric by the shrinkage during the heat treatment after weaving the fabric Susceptible to damage.
(B) After the cord made of polyketone fiber and polyketone fiber having high strength and high elastic modulus is rubberized as an interwoven fabric, a part of the weft breaks earlier than the other part during expansion during tire manufacture As a result, the carcass cord arrangement is disturbed (code open), which causes deterioration in tire durability.

  These problems are not mentioned at all in the prior art, so the present inventors have solved this problem and further realized a high-performance and high-quality interwoven fabric, which is applied to the tire carcass ply. As a result of intensive studies, the present inventors have found that the object can be achieved and have completed the present invention.

That is, the pneumatic tire of the present invention is a pneumatic tire provided with a carcass ply that is formed of a cord layer that extends from a tread portion to both bead portions through both side portions and is anchored to the bead portions and arranged in a substantially radial direction. ,
The carcass ply cord contains at least 90% by mass of polyketone fiber, the maximum heat shrinkage stress as a dip-treated cord is in the range of 0.4 to 1.5 cN / dtex, and is 177 ° C. × 30 minutes dry heat treatment The heat shrinkage rate is in the range of 1.8 to 3.6%,
The amount of deviation from the concentric position at the tire side portion of the weft cord arranged substantially concentrically inside the tire so as to be substantially orthogonal to the cord of the carcass ply is within 50 mm.

  In the pneumatic tire of the present invention, it is preferable that the run-flat tire includes a side reinforcing rubber layer having a crescent-shaped meridional shape over the entire region or almost the entire region of both side portions along the inner surface of the carcass ply. . Each of the weft cords preferably has a fineness of 200 dtex to 400 dtex, a tensile strength of 200 g to 1000 g, and a cut elongation of 5% to 20%, and the distance between the substantially parallel weft cords is preferably Is 10-30 mm. Furthermore, as the polyketone fiber contained in the fiber cord forming the carcass ply cord, those having a tensile strength of 14 cN / dtex or more and an elastic modulus of 280 cN / dtex or more are preferably used. Furthermore, the weft cord is preferably a cord made of multifilament yarn, monofilament yarn or spun yarn, or a cord in which these are mixed, polynosic, rayon, cotton, polyester, nylon or lyocell, or these The cord is preferably a twisted or blended cord.

Here, the maximum heat shrinkage stress of the cord means that a 25 cm long fixed sample of a carcass ply cord before vulcanization subjected to a general dip treatment is heated at a heating rate of 5 ° C./min. It is the maximum stress (unit: cN / dtex) generated in the cord at ° C. The heat shrinkage rate during dry heat treatment is the same dip-treated cord after dry heat treatment at 177 ° C. for 30 minutes in an oven, and the cord length before and after heat treatment is 1/30 (cN / dtex) load. This is a value obtained by measuring with
Thermal shrinkage during dry heat treatment (%) = {(Lb−La) / Lb} × 100
However, Lb is the cord length before heat treatment, and La is the cord length after heat treatment. The tensile strength and tensile modulus of the polyketone fiber are values obtained by measurement according to JIS-L-1013. The tensile modulus is the load at an elongation of 0.1% and the elongation of 0.2%. It is the value of the initial elastic modulus calculated from the load at.

  According to the present invention, a pneumatic tire that achieves a reliable improvement in running durability without causing deterioration in various performances of the tire by applying to the tire a reinforcing material made of a braided fabric using polyketone fibers. Can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial cross-sectional view of a preferred example of the pneumatic tire of the present invention. The tire shown in FIG. 1 is a run-flat tire, and has a pair of left and right bead portions 1 and a pair of sidewall portions 2 and a tread portion 3 connected to both side portions 2, and a toroidal shape between the pair of bead portions 1. A carcass ply 4 composed of one or more sheets that reinforce each of the parts 1, 2, and 3, and a pair of crescent side reinforcing rubber layers 5 disposed inside the carcass ply 4 of the side part 2. Prepare.

  In the illustrated tire, a bead filler 7 is disposed on the outer side in the tire radial direction of each of the ring-shaped bead cores 6 embedded in the bead portion 1, and the outer side in the tire radial direction of the tread portion of the carcass ply 4. Further, a belt 8 composed of two belt layers is disposed, and a belt reinforcing layer 9A is disposed so as to cover the entire belt 8 on the outer side in the tire radial direction of the belt 8, and further, the belt reinforcing layer 9A. A pair of belt reinforcing layers 9B are arranged so as to cover only both ends of the belt. Here, the belt layer is usually composed of a rubberized layer of a cord extending in an inclined manner with respect to the tire equatorial plane, preferably a rubberized layer of a steel cord, and the two belt layers constitute the belt layer. The belt 8 is formed by laminating the cords so as to cross each other with the equator plane interposed therebetween. The belt reinforcing layers 9A and 9B are usually made of rubberized layers of cords arranged substantially parallel to the tire circumferential direction.

  The carcass ply 4 in the illustrated example is composed of a single carcass ply formed by coating a plurality of reinforcing cords arranged in parallel with a coating rubber, and the carcass ply 4 is respectively disposed in the bead portion 1. The present invention comprises a main body portion extending in a toroidal shape between a pair of embedded bead cores 6 and a folded portion wound around each bead core 6 radially outward from the inner side to the outer side in the tire width direction. In the pneumatic tire, the number of plies and the structure of the carcass ply 4 are not limited thereto. Furthermore, although the belt 8 in the illustrated example comprises two belt layers, the number of belt layers constituting the belt 8 is not limited to this in the pneumatic tire of the present invention. Furthermore, in the pneumatic tire of the present invention, it is not essential to dispose the belt reinforcing layers 9A and 9B, and a belt reinforcing layer having a different structure can be disposed.

  In the present invention, the cord of the carcass ply 4 (hereinafter referred to as “carcass cord”) contains at least 90 mass%, preferably 100 mass% of polyketone fibers. If it is less than 90% by mass, any of the strength, heat resistance, and adhesion to rubber as a tire will be insufficient.

  In addition, the carcass cord is a dip-treated cord, and the heat shrinkage rate during dry heat treatment at 177 ° C. for 30 minutes is in the range of 1.8% to 3.6%, preferably 2.2% to 3.0%. When the heat shrinkage rate during dry heat treatment at 177 ° C. for 30 minutes is less than 1.8%, the alignment efficiency due to heating during tire production is significantly reduced, and the strength as a tire becomes insufficient. On the other hand, if the thermal shrinkage rate during dry heat treatment at 177 ° C. for 30 minutes exceeds 3.6%, the cord is significantly shrunk due to heating during tire manufacture, so that the finished tire shape may be deteriorated.

  Further, the maximum heat shrinkage stress of the carcass cord as a dipped cord is 0.4 to 1.5 cN / dtex, preferably 0.6 to 1.3 cN / dtex, more preferably 0.8 to 1.1 cN / dtex. It is. When this maximum heat shrinkage stress is less than 0.4 cN / dtex, the alignment efficiency by heating at the time of tire manufacture is remarkably lowered, and the strength as a tire becomes insufficient. On the other hand, if the maximum heat shrinkage stress exceeds 1.5 cN / dtex, the cord is remarkably contracted by heating at the time of tire manufacture, so that there is a concern that the finished tire shape is deteriorated.

  Furthermore, the amount of deviation from the concentric position at the tire side portion of the weft cord disposed substantially concentrically inside the tire so as to be substantially orthogonal to the carcass cord is within 50 mm, preferably within 35 mm, more preferably within 15 mm. It is. If the amount of displacement of the weft cord from the concentric position at the tire side is larger than 50 mm, the tire cannot be uniformly expanded in the circumferential direction, resulting in uneven spacing of the carcass ply 4 cord. As a result, the reinforcing rubber disposed on the inner side of the tire of the carcass cord is bitten, resulting in a decrease in durability. In addition to changes in physical properties such as the fineness of the weft, the amount of deviation varies depending on processing conditions (particularly, distribution in the width direction, etc.) at the time of dipping, variation in the weft tension and warp tension.

  Furthermore, the fineness of the weft cord disposed inside the tire in a form substantially orthogonal to the carcass cord is preferably in the range of 200 dtex to 400 dtex, more preferably 250 dtex to 350 dtex. When the fineness is less than 200 dtex, there is a concern that weft cord breakage frequently occurs in processes from low cost manufacturing to tire manufacturing. On the other hand, when the fineness exceeds 400 dtex, there is a concern that the carcass cord arrangement may be greatly disturbed in the expansion process of tire manufacture because the fiber is not broken uniformly.

  Furthermore, the tensile strength of the weft cords arranged inside the tire in a form substantially orthogonal to the carcass cords is preferably 200 g to 1000 g, more preferably 300 g to 900 g, still more preferably 400 g to 800 g. When the tensile strength is less than 200 g, there is a concern that weft cord breakage frequently occurs in a process from low cost manufacturing to tire manufacturing. On the other hand, when the tensile strength exceeds 1000 g, there is a concern that the carcass cord arrangement may be greatly disturbed because the tensile strength does not break uniformly in the expansion process of tire manufacture.

  Furthermore, the cut elongation of the weft cord disposed inside the tire in a form substantially orthogonal to the carcass cord is preferably in the range of 5% to 20%, more preferably 7% to 15%. When the cut elongation is less than 5%, there is a concern that weft breaks frequently occur in processes from low cost manufacture to tire manufacturing. On the other hand, when the cut elongation exceeds 20%, there is a concern that the carcass cord arrangement may be greatly disturbed because the carcass cord arrangement is not uniformly broken in the expansion process of tire manufacture.

  Furthermore, the distance between the weft cords substantially parallel to each other is preferably 10 to 30 mm, more preferably 15 to 25 mm. When this distance is less than 10 mm, the productivity of low-cost fabrics is deteriorated. On the other hand, if this distance exceeds 25 mm, the properties of the low-cost fabric are deteriorated.

  Furthermore, the tensile strength of the polyketone fiber contained in the carcass cord is preferably 14 cN / dtex or more, more preferably 17 cN / dtex or more. When the tensile strength is less than 14 cN / dtex, the strength as a tire is insufficient.

  Furthermore, as a polyketone fiber contained in a carcass cord, the elastic modulus is preferably 280 cN / dtex or more, more preferably 320 cN / dtex or more. When this elastic modulus is less than 280 cN / dtex, the shape retention as a tire is insufficient.

  Furthermore, the weft cord is preferably a cord made of multifilament yarn, monofilament yarn or spun yarn, or a cord obtained by blending them, and polynosic, rayon, cotton, polyester, nylon or lyocell, or these. It is preferable that the cord is a mixed twist or a mixed spun cord. By using such a cord, good physical properties as a weft cord can be obtained.

  Next, a carcass cord containing at least 50% by mass or more of polyketone fibers (hereinafter abbreviated as “PK fibers”) that can be used in the present invention will be described in detail.

  Examples of fibers other than PK fibers that can be used in the present invention include nylon, ester, rayon, polynosic, lyocell, and vinylon.

（式中、Ｔは撚り数（回／１００ｍｍ）、Ｄはコードの総繊度（ｄｔｅｘ）、ρはコードに使用される繊維素材の密度（ｇ／ｃｍ^３）である）で定義される撚り係数αが０．２５〜１．２５の範囲であることが好ましい。ＰＫ繊維コードの撚り係数αが０．２５未満では、熱収縮応力が十分に確保できず、一方、１．２５を超えると、弾性率が十分に確保できず、補強能が小さくなる。 Further, the above code further includes the following formula (I),

(Where T is the number of twists (times / 100 mm), D is the total fineness of the cord (dtex), and ρ is the density of the fiber material used in the cord (g / cm ³ )) α is preferably in the range of 0.25 to 1.25. If the twist coefficient α of the PK fiber cord is less than 0.25, the heat shrinkage stress cannot be sufficiently ensured. On the other hand, if it exceeds 1.25, the elastic modulus cannot be sufficiently ensured and the reinforcing ability is reduced.

（式中、Ａは不飽和結合によって重合された不飽和化合物由来の部分であり、各繰り返し単位において同一であっても異なっていてもよい）で表される繰り返し単位から実質的になるものが好適であり、その中でも、繰り返し単位の９７モル％以上が１−オキソトリメチレン［−ＣＨ_２−ＣＨ_２−ＣＯ−］であるポリケトンが好ましく、９９モル％以上が１−オキソトリメチレンであるポリケトンが更に好ましく、１００モル％が１−オキソトリメチレンであるポリケトンが最も好ましい。 As a polyketone as a raw material of the PK fiber, the following general formula (II),

(In the formula, A is a portion derived from an unsaturated compound polymerized by an unsaturated bond, and each repeating unit may be the same or different). Among them, a polyketone in which 97 mol% or more of repeating units is 1-oxotrimethylene [—CH ₂ —CH ₂ —CO—] is preferable, and a polyketone in which 99 mol% or more is 1-oxo trimethylene is preferable. Is more preferable, and a polyketone in which 100 mol% is 1-oxotrimethylene is most preferable.

  In such polyketones, the ketone groups may be partially bonded to each other and the portions derived from the unsaturated compound may be bonded to each other, but the proportion of the portions in which the unsaturated compound-derived portions and the ketone groups are alternately arranged is 90 mass. % Or more, preferably 97% by mass or more, and most preferably 100% by mass.

  In the formula (II), the unsaturated compound forming A is most preferably ethylene, but propylene, butene, pentene, cyclopentene, hexene, cyclohexene, heptene, octene, nonene, decene, dodecene, styrene, acetylene. , Unsaturated hydrocarbons other than ethylene such as allene, and methyl acrylate, methyl methacrylate, vinyl acetate, acrylamide, hydroxyethyl methacrylate, undecenoic acid, undecenol, 6-chlorohexene, N-vinylpyrrolidone, diethyl ester of sulphonylphosphonic acid Further, it may be a compound containing an unsaturated bond such as sodium styrene sulfonate, sodium allyl sulfonate, vinyl pyrrolidone and vinyl chloride.

（上記式中、ｔおよびＴは、純度９８％以上のヘキサフルオロイソプロパノールおよび該ヘキサフルオロイソプロパノールに溶解したポリケトンの希釈溶液の２５℃での粘度管の流過時間であり、ｃは、上記希釈溶液１００ｍＬ中の溶質の質量（ｇ）である）で定義される極限粘度［η］が、１〜２０ｄＬ／ｇの範囲内にあることが好ましく、３〜８ｄＬ／ｇの範囲内にあることがより一層好ましい。極限粘度が１ｄＬ／ｇ未満では、分子量が小さ過ぎて、高強度のポリケトン繊維コードを得ることが難しくなる上、紡糸時、乾燥時および延伸時に毛羽や糸切れ等の工程上のトラブルが多発することがあり、一方、極限粘度が２０ｄＬ／ｇを超えると、ポリマーの合成に時間およびコストがかかる上、ポリマーを均一に溶解させることが難しくなり、紡糸性および物性に悪影響が出ることがある。 Furthermore, as a polymerization degree of the said polyketone, following formula (III),

(In the above formula, t and T are the flow time of a viscosity tube at 25 ° C. of a diluted solution of hexafluoroisopropanol having a purity of 98% or more and a polyketone dissolved in the hexafluoroisopropanol, and c is the diluted solution. The intrinsic viscosity [η] defined by the mass (g) of solute in 100 mL) is preferably in the range of 1 to 20 dL / g, more preferably in the range of 3 to 8 dL / g. Even more preferred. If the intrinsic viscosity is less than 1 dL / g, the molecular weight is too small to obtain a high-strength polyketone fiber cord, and troubles such as fluff and yarn breakage occur frequently during spinning, drying and stretching. On the other hand, if the intrinsic viscosity exceeds 20 dL / g, it takes time and cost to synthesize the polymer, and it becomes difficult to uniformly dissolve the polymer, which may adversely affect the spinnability and physical properties.

  Furthermore, the PK fiber preferably has a crystal structure with a crystallinity of 50 to 90% and a crystal orientation of 95% or more. If the degree of crystallinity is less than 50%, the structure of the fiber is not sufficiently formed and sufficient strength cannot be obtained, and the shrinkage characteristics and dimensional stability during heating may be unstable. For this reason, the crystallinity is preferably 50 to 90%, more preferably 60 to 85%.

  As the method for fiberizing the polyketone, (1) after spinning an unstretched yarn, performing multistage hot drawing, and drawing at a specific temperature and magnification in the final drawing step of the multistage hot drawing, (2 ) A method in which after the undrawn yarn is spun, hot drawing is performed, and the fiber after completion of the hot drawing is rapidly cooled with high tension applied. A desired filament suitable for the production of the polyketone fiber cord can be obtained by fiberizing the polyketone by the method (1) or (2).

  Here, the spinning method of the unstretched yarn of the polyketone is not particularly limited, and a conventionally known method can be employed. Specifically, JP-A-2-112413, JP-A-4-228613, Wet spinning method using an organic solvent such as hexafluoroisopropanol and m-cresol as described in JP-A-4-505344, WO99 / 18143, WO00 / 09611, JP2001 -164422, JP-A-2004-218189, JP-A-2004-285221, and the wet spinning method using an aqueous solution of zinc salt, calcium salt, thiocyanate, iron salt, etc. Among these, the wet spinning method using an aqueous solution of the above salt is preferable.

  For example, in a wet spinning method using an organic solvent, a polyketone polymer is dissolved in hexafluoroisopropanol, m-cresol, or the like at a concentration of 0.25 to 20% by mass, extruded from a spinning nozzle to be fiberized, and then toluene, ethanol, isopropanol The unstretched yarn of polyketone can be obtained by removing and washing the solvent in a non-solvent bath such as n-hexane, isooctane, acetone or methyl ethyl ketone.

  On the other hand, in the wet spinning method using an aqueous solution, for example, a polyketone polymer is dissolved in an aqueous solution of zinc salt, calcium salt, thiocyanate, iron salt or the like at a concentration of 2 to 30% by mass, and a spinning nozzle is formed at 50 to 130 ° C. Then, it is extruded into a coagulation bath and subjected to gel spinning, and further desalting and drying can be performed to obtain unstretched polyketone. Here, in the aqueous solution in which the polyketone polymer is dissolved, it is preferable to use a mixture of zinc halide and a halogenated alkali metal salt or a halogenated alkaline earth metal salt. An organic solvent such as an aqueous solution, acetone, or methanol can be used.

  Further, as a drawing method of the obtained undrawn yarn, a hot drawing method in which the undrawn yarn is heated and drawn to a temperature higher than the glass transition temperature of the undrawn yarn is preferable. The method (2) may be carried out in one stage, but it is preferably carried out in multiple stages. There is no restriction | limiting in particular as a method of heat drawing, For example, the method etc. which run a thread | yarn on a heating roll or a heating plate are employable. Here, the heat stretching temperature is preferably in the range of 110 ° C. to (melting point of polyketone), and the total stretching ratio is suitably 10 times or more.

  When polyketone fiberization is carried out by the method of (1) above, the temperature in the final stretching step of the multistage hot stretching is in the range of 110 ° C. to (the stretching temperature of the stretching step one step before the final stretching step). Moreover, the draw ratio in the final drawing step of multistage hot drawing is preferably in the range of 1.01 to 1.5 times. On the other hand, when polyketone fiberization is carried out by the method of (2) above, the tension applied to the fiber after completion of the hot drawing is preferably in the range of 0.5 to 4 cN / dtex, and the cooling rate in rapid cooling is 30 The cooling end temperature in the rapid cooling is preferably 50 ° C. or less. There is no restriction | limiting in particular as a rapid cooling method of the heat-stretched polyketone fiber, A conventionally well-known method can be employ | adopted, Specifically, the cooling method using a roll is preferable. In addition, since the polyketone fiber obtained in this way has a large residual elastic strain, it is usually preferable to perform relaxation heat treatment so that the fiber length is shorter than the fiber length after hot drawing. Here, the temperature of the relaxation heat treatment is preferably in the range of 50 to 100 ° C., and the relaxation ratio is preferably in the range of 0.980 to 0.999 times.

  In order to make the most effective use of the high heat shrinkage characteristics of PK fiber cords, the processing temperature during processing and the temperature of the molded product during use are close to the temperature indicating the maximum heat shrinkage stress (maximum heat shrinkage temperature). It is desirable to be temperature. Specifically, the processing temperature such as the RFL processing temperature and the vulcanization temperature in the adhesive processing performed as necessary is 100 to 250 ° C., and when the tire material generates heat due to repeated use or high speed rotation. Since the temperature can be as high as 100 to 200 ° C, the maximum heat shrink temperature is preferably in the range of 100 to 250 ° C, more preferably in the range of 150 to 240 ° C.

  The coating rubber for covering the carcass cord according to the present invention can have various shapes. Typically, it is a film, a sheet or the like. Moreover, a known rubber composition can be appropriately employed as the coating rubber, and it is not particularly limited.

  The pneumatic tire of the present invention can be manufactured by a conventional method using the above-mentioned carcass ply as the carcass ply 4. In the pneumatic tire of the present invention, as the gas filled in the tire, normal or air with a changed oxygen partial pressure, or an inert gas such as nitrogen can be used.

Hereinafter, the present invention will be specifically described based on examples.
(Preparation example of PK fiber)
A polyketone polymer with an intrinsic viscosity of 5.3, which is a completely alternating copolymer of ethylene and carbon monoxide, prepared by a conventional method is added to an aqueous solution containing 65% by weight of zinc chloride / 10% by weight of sodium chloride and stirred at 80 ° C. for 2 hours. It melt | dissolved and the dope with a polymer concentration of 8 weight% was obtained.

  This dope is heated to 80 ° C., filtered through a 20 μm sintered filter, passed through a 10 mm air gap from a 50-hole nozzle with a diameter of 0.10 mmφ kept at 80 ° C., and 5% by weight of zinc chloride. Was extruded at a rate of discharge of 2.5 cc / min into water at 18 ° C. containing a coagulated yarn while being drawn at a speed of 3.2 m / min.

Subsequently, the coagulated yarn was washed with an aqueous sulfuric acid solution having a concentration of 2% by weight and a temperature of 25 ° C., and further washed with water at 30 ° C., and then the coagulated yarn was wound at a speed of 3.2 m / min.
The coagulated yarn was impregnated with IRGANOX 1098 (manufactured by Ciba Specialty Chemicals) and IRGANOX 1076 (manufactured by Ciba Specialty Chemicals) in an amount of 0.05% by weight (based on polyketone polymer), and then dried at 240 ° C. or higher. A finishing agent was added to obtain an undrawn yarn. It should be noted that the heat shrinkage rate, strength, elastic modulus, and elongation can be adjusted by appropriately controlling the drying temperature.

A finishing agent having the following composition was used.
Oleic acid lauryl ester / bisoxyethyl bisphenol A / polyether (propylene oxide / ethylene oxide = 35/65: molecular weight 20000) / polyethylene oxide 10 mol addition oleyl ether / polyethylene oxide 10 mol addition castor oil ether / sodium stearylsulfonate / dioctyllin Sodium acid = 30/30/10/5/23/1/1 (weight% ratio).

The obtained undrawn yarn was drawn at 240 ° C. in the first stage, followed by the second stage at 258 ° C., the third stage at 268 ° C., the fourth stage at 272 ° C., and then the second stage at 200 ° C. The film was stretched five times at 1.08 times (stretching tension 1.8 cN / dtex) and wound with a winder. The total draw ratio from the undrawn yarn to the five-stage drawn yarn was 17.1 times. This fiber yarn had high physical properties of a strength of 18.6 cN / dtex, an elongation of 4.6%, and an elastic modulus of 367 cN / dtex. The PK fiber thus obtained was used as a cord under the following conditions.
The PK fiber obtained as described above was used as a cord under the following conditions.

(Examples 1-6, Comparative Examples 1-3, Conventional Examples 1-3)
A tire having a tire size of 245 / 40R18 was manufactured using a carcass ply obtained by coating various tinted fabrics having carcass ply cords and weft cords shown in Tables 1 to 3 with a coating rubber. For each prototype tire, the distance between the carcass cord and the reinforcing rubber arranged on the inner side of the tire was measured over the entire circumference at the maximum width portion and quantified as the amount of biting. In addition, an actual vehicle evaluation of a run flat durability test was conducted by the following test method.

(Run flat durability)
A test tire is mounted on the right front wheel of an FR vehicle with a rim (16 × 7.5JJ) and an internal pressure of 0 kgf / cm ² and traveled at a speed of 80 km / h. Compared. The load applied to the tire during running was 585 kg.

It is sectional drawing of the right half of an example of the pneumatic tire of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Radial carcass 5 Side reinforcement rubber layer 6 Bead core 7 Bead filler 8 Belt 9A, 9B Belt reinforcement layer

Claims (9)

In a pneumatic tire provided with a carcass ply made of a cord layer arranged in a substantially radial direction, extending from a tread portion to both bead portions through both side portions and anchored to the bead portion.
The carcass ply cord contains at least 90% by mass of polyketone fiber, the maximum heat shrinkage stress as a dip-treated cord is in the range of 0.4 to 1.5 cN / dtex, and is 177 ° C. × 30 minutes dry heat treatment The heat shrinkage rate is in the range of 1.8 to 3.6%,
A pneumatic tire characterized in that a displacement amount from a concentric position at a tire side portion of a weft cord arranged substantially concentrically inside a tire in a shape substantially orthogonal to the cord of the carcass ply is within 50 mm.   2. The pneumatic tire according to claim 1, wherein the pneumatic tire is a run-flat tire including a side reinforcing rubber layer having a crescent-shaped meridional section over the entire region of both side portions or substantially the entire region along the inner surface of the carcass ply.   The pneumatic tire according to claim 1 or 2, wherein the weft cord has a fineness of 200 to 400 dtex.   The pneumatic tire according to claim 1, wherein the weft cord has a tensile strength of 200 g to 1000 g.   The pneumatic tire according to any one of claims 1 to 4, wherein the cut elongation of the weft cord is 5% to 20%.   The pneumatic tire according to any one of claims 1 to 5, wherein a distance between the substantially parallel weft cords is 10 to 30 mm.   The pneumatic tire according to claim 1, wherein a polyketone fiber contained in the fiber cord forming the carcass ply cord has a tensile strength of 14 cN / dtex or more and an elastic modulus of 280 cN / dtex or more.   The pneumatic tire according to any one of claims 1 to 7, wherein the weft cord is a cord made of a multifilament yarn, a monofilament yarn or a spun yarn, or a cord obtained by mixing them.   The pneumatic tire according to any one of claims 1 to 8, wherein the weft cord is polynosic, rayon, cotton, polyester, nylon, lyocell, or a cord obtained by blending or spinning these.

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