JP4974572B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more specifically, a reinforcing cord for a carcass layer or a belt layer using a woven fabric using a cord containing polyketone fiber having high strength and high elastic modulus as a warp. The present invention relates to a pneumatic tire that exhibits excellent uniformity with little disturbance of the reinforcing cord due to heating during manufacture of the tire.

  As a material that can replace conventional organic fiber materials, carbon monoxide and olefins such as ethylene and propene are polymerized using palladium or nickel as a catalyst, so that carbon monoxide and olefin are almost completely alternately copolymerized aliphatic. It has been found that a polyketone can be obtained (Non-patent Document 1), and today, research on making such a polyketone into a fiber is being conducted.

  Polyketone fibers are known to have a higher melting point than conventional polyolefin fibers, and have high strength and high elastic modulus. Utilizing these excellent physical properties, they are used for industrial materials, especially tires, belts, hoses. As such, it is expected to be developed as a rubber reinforcing material. From this viewpoint, various techniques have been proposed for polyketone fibers.

  For example, technologies relating to polyketone fibers having high strength and high elastic modulus are disclosed in Patent Documents 1 to 9 and the like. However, in these patent documents, there is no description about using such polyketone fiber as a woven fabric and using it as a rubber reinforcing material.

Usually, when a fiber cord reinforcing material is used as a rubber reinforcing material, a fiber is twisted and then an adhesive is applied to form a cord, or a woven fabric is embedded in a rubber material such as a tire. In this regard, Patent Documents 10 to 17 and the like disclose a technique related to a woven fabric using a polyketone fiber cord as a warp.
JP-A-1-124617 JP-A-2-112413 Japanese National Patent Publication No. 4-505344 JP-A-4-228613 Japanese National Patent Publication No. 7-508317 Japanese National Patent Publication No. 8-507328 US Pat. No. 5,955,019 WO99 / 18143 pamphlet International Publication No. 00/09611 Pamphlet etc. Japanese Patent Laid-Open No. 9-324377 JP-A-9-329198 JP-A-11-334313 JP 11-336957 A JP 2000-142024 A JP 2000-142525 A JP 2000-190705 A JP 2000-264012 A Industrial materials (December issue, page 5, 1997)

However, it has been found that the woven fabric using the polyketone fiber cord disclosed in the above prior art as the warp has the following problems (a) and (b).
(A) A cord made of polyketone fiber having high strength and high elastic modulus has a high heat shrinkage stress, and the warp woven fabric is distorted by heat shrinkage after weaving, and flatness is impaired.
(B) Cords made of polyketone fibers having high strength and high elastic modulus are crushed as rubber fabrics and then heated during tire production, resulting in disorder of the cord arrangement due to the shrinkage of the polyketone fibers, resulting in tire uniformity. Worsen. For this reason, there is a concern that the durability of the tire is lowered in a high performance tire, an ultra flat tire, and a heavy load tire that require high durability.

  In the prior art, there is no description or suggestion regarding these problems, and moreover, as means for solving these problems, that is, as reinforcing cords for tires using cords including polyketone fibers having high strength and high elastic modulus. There is no description about making high-performance and high-quality silk fabrics.

  Accordingly, an object of the present invention is to obtain a high-performance and high-quality koji fabric as a reinforcing cord for a carcass layer or a belt layer using a cord containing polyketone fibers having high strength and high elastic modulus, It is to provide a pneumatic tire excellent in uniformity when applied to a layer or a belt layer.

  As a result of intensive studies to solve the above problems, the present inventor applied a weft satisfying a predetermined condition in the carcass layer or the belt layer to a warp of a cord including a polyketone fiber having high strength and high elastic modulus. As a result, the inventors have found that the above object can be achieved and have completed the present invention.

That is, the pneumatic tire of the present invention includes a tread portion, a pair of sidewall portions extending inward in the tire radial direction from both ends thereof, and a pair of bead portions positioned at the inner ends of the sidewall portions, A carcass layer composed of at least one carcass ply extending in a toroidal shape between a pair of bead cores embedded in the bead portion, and at least one belt ply disposed on the radially outer side of the crown portion of the carcass. In a pneumatic tire having a belt layer,
As the carcass ply cord of at least one carcass layer, a cord containing at least 50% by mass of polyketone fiber and having a maximum heat shrinkage stress in a range of 0.1 to 1.8 cN / dtex is used, and the carcass As weft cords arranged inside the tire in a shape substantially perpendicular to the ply cord, cords having a fineness of 60 dtex to 600 dtex, a cut elongation of 60% or more and a tensile strength of 200 g or more are used and are substantially parallel to each other. The distance between the weft cords is between 5 and 50 mm, and the weft cord has an initial elastic modulus at 25 ° C. of 2.5 cN / dtex or more and an initial elastic modulus at 150 ° C. of 0.8 cN. / Dtex or more.

Another pneumatic tire of the present invention includes a tread portion, a pair of sidewall portions extending inward in the tire radial direction from both ends thereof, and a pair of bead portions positioned at the inner ends of the sidewall portions, A carcass layer composed of at least one carcass ply extending in a toroidal shape between a pair of bead cores embedded in the bead portion, and at least one belt ply disposed on the radially outer side of the crown portion of the carcass. In a pneumatic tire having a belt layer,
As the at least one belt ply cord of the belt layer, a cord containing at least 50% by mass of polyketone fiber and having a maximum heat shrinkage stress in a range of 0.1 to 1.8 cN / dtex is used, and the belt As the weft cords arranged inside the tire in a shape substantially orthogonal to the ply cord, cords having a fineness of 200 dtex to 1000 dtex, a cut elongation of 60% or more, and a tensile strength of 200 g or more are used, and the wefts substantially parallel to each other The distance between the cords is between 5 and 50 mm, and the weft cord has an initial elastic modulus at 25 ° C. of 2.5 cN / dtex or more and an initial elastic modulus at 150 ° C. of 0.8 cN / dtex or more. It is characterized by being.

  In the tire according to the present invention, the polyketone fiber has a tensile strength of 10 cN / dtex or more, an elastic modulus of 200 cN / dtex or more, and a heat shrinkage ratio in the range of 1% to 5% at 150 ° C. × 30 minutes in the dry heat treatment. Is preferably used.

  In the present invention, the weft cord may be a cord made of a multifilament yarn, a monofilament yarn or a spun yarn, or a cord in which these are mixed, and is preferably a polyamide undrawn yarn or semi-drawn yarn. Yarn or partially oriented yarn (POY) or polyester undrawn yarn, semi-drawn yarn or partially oriented yarn multifilament yarn, monofilament yarn or blended cord, or these cords and polynosic, rayon, cotton, polyester, nylon or The cord which mixedly twisted the lyocell can be mentioned. Alternatively, a cord in which a polyamide or polyester multifilament having a breaking elongation of 60% or more and a cellulosic multifilament are entangled and a large number of loop fluffs are provided on the surface thereof can also be suitably exemplified.

  According to the present invention, a high-performance and high-quality warp woven fabric is obtained as a reinforcing cord for a carcass layer or a belt layer using a cord including polyketone fibers having high strength and high elastic modulus. A pneumatic tire excellent in uniformity can be provided by applying the belt layer as a reinforcing cord.

Hereinafter, specific embodiments of the present invention will be described in detail.
(First embodiment)
FIG. 1 shows a schematic cross-sectional view of an example of a pneumatic tire according to the first embodiment of the present invention. The illustrated tire 10 includes a tread portion 1, a pair of sidewall portions 2 extending inward in the tire radial direction from both ends thereof, and a pair of bead portions 3 positioned at the inner ends thereof. A carcass layer 5 composed of a single carcass ply (in the illustrated example) is extended between a pair of bead cores 4 embedded in the bead portion 3 in a toroidal shape. Here, reference numeral 8 denotes a bead filler. Further, the tire 10 is disposed on the outer side in the radial direction of the crown portion of the carcass layer 5, and is disposed on the outer side in the tire radial direction of the belt layer 6 including at least one belt ply (two in the illustrated example). And at least one belt protective layer 7 (in the illustrated example).

In the present embodiment, as the carcass ply cord of the carcass layer 5 in the illustrated tire 10, a cord that includes at least 50 mass% of polyketone fibers and has a maximum heat shrinkage stress in a range of 0.1 to 1.8 cN / dtex. As a weft cord that is used and arranged inside the tire in a shape substantially orthogonal to the carcass ply cord, a cord having a fineness of 60 dtex to 600 dtex, a cut elongation of 60% or more, and a tensile strength of 200 g or more It is important that the distance between the weft cords substantially parallel to each other is between 5 and 50 mm. As a result, a high-performance and high-quality woven fabric is used as a reinforcing cord for the carcass layer, and a pneumatic tire in which this woven fabric is applied to the carcass layer exhibits excellent uniformity.
In the illustrated tire, the belt protective layer 7 is disposed. However, in the present embodiment, the belt protective layer 7 may or may not be disposed as appropriate.

  The carcass ply cord of the carcass layer 5 desirably contains at least 50% by mass of polyketone fibers, preferably 70% by mass or more, and more preferably 100% by mass. If it is less than 50% by mass, any of the strength, heat resistance, and adhesion to rubber as a tire will be insufficient.

  The maximum heat shrinkage stress of the carcass ply cord is in the range of 0.1 to 1.8 cN / dtex, preferably 0.4 to 1.6 cN / dtex, more preferably 0.6 to 1.4 cN / dtex. It is desirable. When the maximum heat shrinkage stress is less than 0.1 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, when the maximum heat shrinkage stress exceeds 1.8 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 may be deteriorated.

  Further, the tensile strength of the polyketone fiber contained in the carcass ply cord is preferably 10 cN / dtex or more, more preferably 15 cN / dtex or more. When the tensile strength is less than 10 cN / dtex, the strength as a tire is insufficient.

  Furthermore, as a polyketone fiber contained in the carcass ply cord, the elastic modulus is preferably 200 cN / dtex or more, more preferably 250 cN / dtex or more. When this elastic modulus is less than 200 cN / dtex, shape retention as a tire is insufficient.

  Furthermore, as the polyketone fiber contained in the carcass ply cord, the heat shrinkage rate at 150 ° C. for 30 minutes during the dry heat treatment is preferably in the range of 1% to 5%, more preferably in the range of 2% to 4%. When the heat shrinkage rate at the time of dry heat treatment at 150 ° C. for 30 minutes is less than 1%, the alignment efficiency by heating at the time of tire production is remarkably lowered, and the strength as a tire becomes insufficient. On the other hand, when the thermal shrinkage rate at the time of dry heat treatment at 150 ° C. for 30 minutes exceeds 5%, the cord is significantly shrunk by heating at the time of manufacturing the tire, so that the finished tire shape may be deteriorated.

  Next, it is desirable that the weft cord disposed inside the tire in a form substantially orthogonal to the above-mentioned carcass ply cord has a fineness in the range of 60 dtex to 600 dtex, preferably 100 dtex to 400 dtex. If the fineness is less than 60 dtex, there is a concern that weft breaks frequently occur in the process from the kite manufacturing to the tire manufacturing. On the other hand, when the fineness exceeds 600 dtex, there is a concern that the carcass cord arrangement may be greatly disturbed because the tire does not break uniformly in the expansion process of tire manufacture.

  The weft cord has a tensile strength of 200 g or more, preferably 300 g or more. When this tensile strength is less than 200 g, there is a concern that weft breaks frequently occur in the process from the kite manufacturing to the tire manufacturing.

  Further, the weft cord has a cut elongation of 60% or more, preferably 80% or more. If the cut elongation is less than 60%, the carcass ply cord arrangement may be disturbed in a tire manufacturing expansion process, and the carcass ply cord arrangement may be disturbed.

  Furthermore, it is desirable that the distance between the weft cords substantially parallel to each other is 5 to 50 mm, preferably 20 to 35 mm. When this distance is less than 5 mm, the productivity of the woven fabric is deteriorated. On the other hand, when it exceeds 50 mm, the properties of the woven fabric are deteriorated.

  Furthermore, the weft cord preferably has an initial elastic modulus at 25 ° C of 2.5 cN / dtex or more, and an initial elastic modulus at 150 ° C of 0.8 cN / dtex or more, more preferably at 25 ° C. The initial elastic modulus is 3.5 cN / dtex or higher, and the initial elastic modulus at 150 ° C. is 1.2 cN / dtex or higher. When the initial elastic modulus at 25 ° C. is less than 2.5 cN / dtex and the initial elastic modulus at 150 ° C. is less than 0.8 cN / dtex, the carcass cord arrangement disorder caused by heating / shrinkage during tire manufacture There are concerns that cannot be adequately controlled.

(Second embodiment)
In the second embodiment, the at least one belt ply cord of the belt layer 6 in the illustrated tire 10 includes at least 50% by mass of polyketone fibers and has a maximum heat shrinkage stress of 0.1 to 1.8 cN / dtex. As a weft cord that is arranged in the tire in a shape substantially perpendicular to the belt ply cord, the fineness is 200 dtex to 1000 dtex, the cut elongation is 60% or more, and the tensile strength is 500 g or more. It is important that the distance between the weft cords substantially parallel to each other is between 5 and 50 mm. As a result, a high-performance and high-quality woven fabric is used as a reinforcing cord for the belt layer 6, and a pneumatic tire in which this woven fabric is applied to the carcass layer exhibits excellent uniformity.
In the second embodiment as well, the belt protective layer 7 may be appropriately disposed as necessary.

  The belt ply cord of the belt layer 6 desirably contains at least 50% by mass of polyketone fibers, preferably 70% by mass or more, and more preferably 100% by mass. If it is less than 50% by mass, any of the strength, heat resistance, and adhesion to rubber as a tire will be insufficient.

  The maximum heat shrinkage stress of the belt ply cord is in the range of 0.1 to 1.8 cN / dtex, preferably 0.4 to 1.6 cN / dtex, more preferably 0.6 to 1.4 cN / dtex. It is desirable. When the maximum heat shrinkage stress is less than 0.1 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, when the maximum heat shrinkage stress exceeds 1.8 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 may be deteriorated.

  Furthermore, the tensile strength of the polyketone fiber contained in the belt ply cord is preferably 10 cN / dtex or more, more preferably 15 cN / dtex or more. When the tensile strength is less than 10 cN / dtex, the strength as a tire is insufficient.

  Furthermore, as a polyketone fiber contained in the belt ply cord, the elastic modulus is preferably 200 cN / dtex or more, more preferably 250 cN / dtex or more. When this elastic modulus is less than 200 cN / dtex, shape retention as a tire is insufficient.

  Furthermore, as the polyketone fiber contained in the belt ply cord, the heat shrinkage rate during dry heat treatment at 150 ° C. for 30 minutes is preferably in the range of 1% to 5%, more preferably in the range of 2% to 4%. When the heat shrinkage rate at the time of dry heat treatment at 150 ° C. for 30 minutes is less than 1%, the alignment efficiency by heating at the time of tire production is remarkably lowered, and the strength as a tire becomes insufficient. On the other hand, when the thermal shrinkage rate at the time of dry heat treatment at 150 ° C. for 30 minutes exceeds 5%, the cord is significantly shrunk by heating at the time of manufacturing the tire, so that the finished tire shape may be deteriorated.

  Next, it is desirable that the weft cords arranged inside the tire in a form substantially orthogonal to the belt ply cord described above have a fineness in the range of 200 dtex to 1000 dtex, preferably 300 dtex to 600 dtex. When the fineness is less than 200 dtex, there is a concern that weft breaks frequently occur in the process from the kite manufacturing to the tire manufacturing. On the other hand, when the fineness exceeds 1000 dtex, there is a concern that the belt ply cord arrangement is greatly disturbed in the expansion process of tire manufacture, and the belt ply cord arrangement is greatly disturbed.

  The weft cord has a tensile strength of 200 g or more, preferably 300 g or more. When this tensile strength is less than 200 g, there is a concern that weft breaks frequently occur in the process from the kite manufacturing to the tire manufacturing.

  Further, the weft cord has a cut elongation of 60% or more, preferably 80% or more. When the cut elongation is less than 60%, there is a concern that the belt ply cord arrangement is greatly disturbed in the expansion process of tire manufacture, and the belt ply cord arrangement is greatly disturbed.

  Furthermore, it is desirable that the distance between the weft cords substantially parallel to each other is 5 to 50 mm, preferably 20 to 35 mm. When this distance is less than 5 mm, the productivity of the woven fabric is deteriorated. On the other hand, when it exceeds 50 mm, the properties of the woven fabric are deteriorated.

  The weft cord preferably has an initial elastic modulus at 25 ° C. of 2.5 cN / dtex or more, an initial elastic modulus at 150 ° C. of 0.8 cN / dtex or more, more preferably an initial elastic modulus at 25 ° C. of 3 The initial elastic modulus at 150 ° C. is 1.2 cN / dtex or more at 0.5 cN / dtex or more. When the initial elastic modulus at 25 ° C. is less than 2.5 cN / dtex and the initial elastic modulus at 150 ° C. is less than 0.8 cN / dtex, belt cord alignment disorder caused by heating / shrinkage during tire manufacture may occur. There are concerns that cannot be adequately controlled.

  In the present invention, in addition to the first and second embodiments described above, it is a matter of course that a tire appropriately combining these embodiments is also included. The weft cords that can be used in the present invention can be multifilament yarns, monofilament yarns, spun yarn cords, or cords in which these are mixed, preferably polyamide undrawn yarns, Drawn yarn or partially oriented yarn (POY), polyester undrawn yarn, semi-drawn yarn or partially oriented yarn multifilament yarn, monofilament yarn or blended cord, or these cords and polynosic, rayon, cotton, polyester, nylon Or the cord which mixedly twisted the lyocell can be mentioned. Alternatively, a cord in which a polyamide or polyester multifilament having a breaking elongation of 60% or more and a cellulosic multifilament are entangled and a large number of loop fluffs are provided on the surface thereof can also be suitably exemplified.

  Next, polyketone fibers (hereinafter abbreviated as “PK fibers”) that can be used in the present invention will be described in detail.

  In the present invention, the fibers other than PK fibers of the fiber yarn containing at least 50% by mass or more of PK fibers can include nylon, ester, rayon, polynosic, lyocell, vinylon, and the like, and should be particularly limited. is not.

The dry heat shrinkage of the PK fiber in the present invention is measured by subjecting the fiber length before and after the heat treatment to 1/30 (cN / dtex) by performing a dry heat treatment at 150 ° C. for 30 minutes in an oven. The value obtained from the following formula.
Dry heat shrinkage (%) = (Lb−La) / Lb × 100
However, Lb is the fiber length before heat treatment, and La is the fiber length after heat treatment. Further, the tensile strength and tensile modulus of the PK fiber are values obtained by measurement according to JIS-L-1013, and the tensile modulus is a load at an elongation of 0.1% and an elongation of 0.2%. It is the value of the initial elastic modulus calculated from the load at.

  Specifically, the PK fiber cord that can be used in the present invention is preferably a PK fiber cord described in detail below. That is, it is a multifilament twisted PK fiber having a total decitex per cord of 3000 to 17000 dtex. If the total decitex per one cord is in the range of 3000 to 17000 dtex, it is possible to achieve high rigidity and light weight compared to steel cord, which is an advantage of organic fibers. If the total decitex is less than 3000 decitex, sufficient high rigidity cannot be obtained as the carcass ply 3. On the other hand, if the total decitex exceeds 17000 decitex, the ply gauge becomes thick and the tire mass increases.

  Further, the maximum heat shrinkage stress of the PK fiber cord is determined by heating a 25 cm long fixed sample of the PK fiber cord before vulcanization subjected to a general dip treatment at a heating rate of 5 ° C./min. It is the maximum stress (unit: cN / dtex) generated in the cord at ° C.

In addition, the PK fiber cord further includes the following formula (I),
α = T × D ^1/2 (I)
(Where T is the number of twists (times / 100 mm) and D is the total fineness (dtex) of the cord), and the twist coefficient α is preferably in the range of 850 to 4000. If the twist coefficient α of the PK fiber cord is less than 850, the heat shrinkage stress cannot be secured sufficiently. On the other hand, if it exceeds 4000, the elastic modulus cannot be secured sufficiently 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［−ＣＨ₂−ＣＨ₂−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 cord, 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 the repeating units is 1-oxotrimethylene [—CH ₂ —CH ₂ —CO—] is preferable, and a polyketone in which 99 mol% or more is 1-oxotrimethylene. 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-vinyl pyrrolidone, 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%.

  The polyketone fiberization method includes (1) a method in which unstretched yarn is spun and then subjected to multistage hot stretching and stretched at a specific temperature and magnification in the final stretching step of the multistage hot stretching, (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 knit fabric according to the present invention can have various shapes as long as this knit fabric can be coated. Typically, it is a film, a sheet or the like. Moreover, if it is the belt protective layer 7, it can be made into ribbon shape. Furthermore, a known rubber composition can be appropriately employed as the coating rubber, and it is not particularly limited.

  The woven fabric according to the present invention is coated with a rubber composition according to a known method such as dipping, coating, and bonding.

(Preparation example of PK fiber)
A polyketone polymer with an intrinsic viscosity of 5.3, which is prepared by a conventional method and is completely alternatingly copolymerized with ethylene and carbon monoxide, is added to an aqueous solution containing 65% by mass of zinc chloride / 10% by mass of sodium chloride and stirred at 80 ° C. for 2 hours. It melt | dissolved and obtained dope with a polymer concentration of 8 mass%.

  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 spout diameter maintained at 80 ° C., and 5% by mass 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 a sulfuric acid aqueous solution having a concentration of 2 mass% 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 solidified 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 mass (based on polyketone polymer), and then dried at 240 ° C. A finishing agent was applied to obtain an undrawn yarn.

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 (mass% 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 strength 15.6 cN / dtex, elongation 4.2%, and elastic modulus 347 cN / dtex. In addition, it had high heat shrinkage characteristics of 150% at 30 ° C. for 30 minutes and heat shrinkage during heat treatment of 4.3% and maximum heat shrinkage stress of 0.92 cN / dtex. The PK fiber cord thus obtained was used in the following examples and the like.

(Examples 1-1 to 1-9, Comparative Examples 1-1 to 1-5)
Each test tire (size: 305 / 30ZR19) was prototyped using the carcass cords having the cord physical properties shown in Tables 1 to 3 below and the wefts shown in the same table, the strength test by water pressure fracture, and the uniformity by the uniformity measuring machine. Measurements were performed. In addition, weft breakage and carcass cord disturbance during tire production were also evaluated. The obtained results are shown in Tables 1 to 3 below.

(Examples 2-1 to 2-7, Comparative Examples 2-1 to 2-2, Conventional Example 2-1)
Consists of a belt layer composed of two belt plies (first belt ply: steel cord, second belt ply: second belt cord shown in Tables 4 and 5 below), and further reinforced with one belt protective layer Test tire (size: 225 / 45R17) was prototyped, outer circumference growth test under internal pressure, uniformity measurement with uniformity measuring machine and tire durability test with drum testing machine (drum conditions: internal pressure 250 kPa, load 1125 kg, speed 180 km / Carried out). In addition, weft breakage and second belt cord disturbance during production were also evaluated. A very good case was evaluated as ◎, a good case as ○, and a poor case as ×. The obtained results are shown in Tables 4 and 5 below.

1 is a cross-sectional view in the width direction of a pneumatic tire according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass layer 6 Belt layer 7 Belt protective layer 8 Bead filler 10 Pneumatic tire

Claims (6)

A tread portion, a pair of sidewall portions extending inward in the tire radial direction from both ends thereof, and a pair of bead portions positioned at the inner ends of the sidewall portions, and a pair of bead cores embedded in the bead portion In a pneumatic tire having a carcass layer made of at least one carcass ply extending in a toroidal space, and a belt layer made of at least one belt ply disposed on the outer side in the crown portion radial direction of the carcass,
As the carcass ply cord of at least one carcass layer, a cord containing at least 50% by mass of polyketone fiber and having a maximum heat shrinkage stress in a range of 0.1 to 1.8 cN / dtex is used, and the carcass As weft cords arranged inside the tire in a shape substantially perpendicular to the ply cord, cords having a fineness of 60 dtex to 600 dtex, a cut elongation of 60% or more and a tensile strength of 200 g or more are used and are substantially parallel to each other. Ri near between distance is 5~50mm between Do the weft cord, said weft cord, the initial modulus at 25 ° C. is 2.5 cN / dtex or more and an initial modulus of at 0.99 ° C. 0. A pneumatic tire characterized by being 8 cN / dtex or more . A tread portion, a pair of sidewall portions extending inward in the tire radial direction from both ends thereof, and a pair of bead portions positioned at the inner ends of the sidewall portions, and a pair of bead cores embedded in the bead portion In a pneumatic tire having a carcass layer made of at least one carcass ply extending in a toroidal space, and a belt layer made of at least one belt ply disposed on the outer side in the crown portion radial direction of the carcass,
As the at least one belt ply cord of the belt layer, a cord containing at least 50% by mass of polyketone fiber and having a maximum heat shrinkage stress in a range of 0.1 to 1.8 cN / dtex is used, and the belt As the weft cords arranged inside the tire in a shape substantially orthogonal to the ply cord, cords having a fineness of 200 dtex to 1000 dtex, a cut elongation of 60% or more, and a tensile strength of 200 g or more are used, and the wefts substantially parallel to each other Ri near between distance is 5~50mm between codes, the weft cord, the initial modulus at 25 ° C. is 2.5 cN / dtex or more and an initial modulus of at 0.99 ° C. is 0.8cN / dtex A pneumatic tire characterized by the above . As the polyketone fiber, the tensile strength of 10 cN / dtex or more, an elastic modulus 200 cN / dtex or more, 0.99 ° C. × 30 minutes dry heat treatment at thermal shrinkage used as in the range of 1% to 5% claim 1 or 2 The described pneumatic tire. The pneumatic tire according to any one of claims 1 to 3 , 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 weft cord is polyamide undrawn yarn, semi-drawn yarn or partially oriented yarn (POY), polyester undrawn yarn, semi-drawn yarn or partially oriented yarn multifilament yarn, monofilament yarn or mixed twist cord, or these The pneumatic tire according to claim 4 , wherein the cord is a cord in which a cord and polynosic, rayon, cotton, polyester, nylon, or lyocell are mixed and twisted. The weft cord, a multi-filament and cellulose multifilament polyamide or polyester having a breaking elongation of 60% or more entangled, many of claim 4, wherein loop fluff is code given to the surface Pneumatic tire.

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