JP5035952B2 - Run flat tire - Google Patents

Description

  The present invention relates to a so-called side-reinforced runflat tire that can run flatly when the tire internal pressure is abnormally lowered or punctured. More specifically, the runflat durability and ride comfort during normal internal pressure are highly enhanced. The present invention relates to a run-flat tire that is improved in safety and comfort by being balanced.

  The tires are damaged by road surface projections and holes that can occur when the vehicle is running, or by the impact input to the tires due to sharp foreign objects, and as a result, the air inside the tires leaks rapidly, losing the load carrying capacity, and the vehicle motion May significantly harm the stability of

  In order to avoid such a phenomenon, the sidewall portion of a tire having flexibility is usually reinforced with a relatively high modulus rubber as a thick gauge, and even when the internal pressure becomes almost zero, Conventionally, a structure capable of applying a load without extremely increasing the deflection has been proposed. For example, in Patent Document 1, a run-flat tire having a structure in which a meridional cross-section side reinforcing rubber layer is provided so that the entire side portion of the tire has a substantially uniform thickness over the entire region or both regions of both side portions. Has been proposed, and even if the filling pressure of the tire decreases due to puncture or the like, the tire can continue to run while supporting the load.

In addition, side-reinforced run-flat tires that improve tire life, vehicle handling characteristics, and ride comfort by providing various inserts that support compressive and tensile loads in the run-flat operation state have also been proposed (patented) Reference 2).
Japanese Patent Application Laid-Open No. 2000-309211 JP-T-2002-519238

  However, in conventional run-flat tires, the rubber at the side portion bears the load during run-flat running, so the temperature of the rubber becomes very high, and the rigidity of the side portion decreases due to softening of the rubber, so that run-flat running At the end, for example, in a run flat tire provided with a side reinforcing rubber layer having a crescent-shaped cross section, there is a problem that the side reinforcing rubber layer is broken.

  In order to solve this problem, it is conceivable to increase the gauge of the side reinforcing rubber layer, but in that case, there is a possibility that the riding comfort during normal driving is deteriorated and the durability of the vehicle is also deteriorated. .

  Accordingly, an object of the present invention is to provide a run-flat tire having improved safety and comfort by combining the durability during running in a run-flat state and the vibration / riding comfort under normal internal pressure, in particular, the flatness ratio ( An object of the present invention is to provide a run-flat tire for a passenger car having a cross-sectional shape with a tire height / tire width of 60% or less.

  As a result of earnest study to achieve both the run-flat durability performance of a pneumatic tire and the riding comfort performance during normal driving, the present inventor has found that the cross-section of the crescent-shaped side reinforcing rubber is not thickened and the run-flat deflection is achieved. In order to suppress this, it is effective to place a reinforcing layer using a high-rigidity cord inside the carcass ply using an organic fiber cord. It turned out that the combination with the code which demonstrates is essential.

  That is, when the tire side is bent in the run-flat running state, the carcass ply has a compressive input acting on the inner cord and a tensile input acting on the outer cord. When a reinforcing layer consisting of a highly rigid cord is placed inside the carcass ply, the neutral axis of bending is located just outside the reinforcing layer, and the carcass ply has a larger tensile strength than when no reinforcement is applied. Stress will act.

  However, this alone did not provide sufficient run-flat durability. This is because tires become extremely hot during run-flat driving, and the conventional organic fiber cord carcass ply cannot obtain sufficient rigidity under high-temperature conditions during run-flat driving. This is because sufficient rigidity was not exhibited and satisfactory run-flat durability could not be obtained.

  Therefore, as a result of further earnest research, the present inventor has arranged a steel cord reinforcing layer inside the carcass ply and a specific organic mainly composed of polyketone fibers outside the bend in the run-flat state at the tire side portion. When a carcass ply using fiber cords is placed, the organic fiber cords present on the outer side of the neutral shaft exhibit good tensile rigidity, exhibit sufficient bending rigidity even in run-flat running conditions, and satisfactory durability I found out that I can secure it.

  In addition, these organic fiber cords exhibit high tensile rigidity only at high temperatures, and the increase in longitudinal springs can be minimized when running under normal pressure, so the gauge of the side reinforcing rubber layer with a crescent-shaped cross section is made thinner. It has become possible to provide run-flat tires that were not possible with the conventional technology, improving the ride comfort during normal driving and ensuring durability during run-flat driving.

  The same thing happens in the tire bead part. In the run-flat state, the inner side of the tire side part is on the inner side of the bend, whereas the outer surface side of the bead part is on the inner side of the bend. It was also found that the same effect as that of the side portion can be obtained by disposing the organic fiber cord on the outer surface and disposing the steel cord reinforcing layer on the outer surface side. The present invention has been completed based on the above findings.

That is, the run flat tire of the present invention has a pair of left and right bead portions, a pair of sidewall portions that are continuous from the bead portion to the outside in the tire radial direction, and a tread portion that is continuous with both sidewall portions. A carcass layer composed of one or more carcass plies extending in a toroidal shape between the bead portions of the carcass and reinforcing the respective portions, a belt layer disposed on the outer side in the tire radial direction of the carcass, and the sidewall portion In a run flat tire provided with a side reinforcing rubber layer having a crescent-shaped cross section disposed inside the carcass,
At least one region of the sidewall portion region and the bead portion region is reinforced with a combination structure of these layers so that the outside of the curved portion is an organic fiber cord layer and the inside is a steel cord layer,
The organic fiber cord layer contains at least 50% by mass of polyketone fiber, the maximum heat shrinkage stress of the cord is in the range of 0.1 to 1.8 cN / dtex, and the polyketone fiber is dried at 150 ° C. for 30 minutes. It consists of a cord layer in which an organic fiber cord having a heat shrinkage rate in the range of 1% to 5% during heat treatment is covered with rubber,
The steel cord layer is composed of a cord layer in which a steel cord obtained by twisting steel filaments is covered with rubber,
At least one layer of the carcass ply is made of the organic fiber cord layer, and an insert made of at least one steel cord layer is disposed in the sidewall region and inside the organic fiber cord layer. It is a feature.

  In the present invention, it is preferable that the inner end in the tire radial direction of the insert is located at a position 20 to 40% of the tire height h from the bead base portion, and the outer end is located near the belt end of the belt layer.

  In the present invention, preferably, at least one layer of the carcass ply folded back from the inside to the outside of the bead core and the bead filler embedded in the bead portion is formed of the organic fiber cord layer, and the bead portion In the run-flat tire, an insert made of at least one steel cord layer is disposed in a region and outside the organic fiber cord layer. In this case, the inner end in the tire radial direction of the insert disposed in the bead portion region is preferably at a position of 10 to 25% of the tire height h from the bead base portion, and the outer end is at a position of 20 to 35%. It is preferable that it exists in.

Further, another run flat tire of the present invention has a pair of left and right bead portions, a pair of sidewall portions that are continuous from the bead portion to the outside in the tire radial direction, and a tread portion that is continuous with both sidewall portions, A carcass layer composed of one or more carcass plies extending in a toroidal shape between the pair of bead portions to reinforce each of the portions, a belt layer disposed on the outer side in the tire radial direction of the carcass, and the sidewall portion In a run flat tire comprising a side reinforcing rubber layer having a crescent-shaped cross section disposed inside the carcass in
At least one region of the sidewall portion region and the bead portion region is reinforced with a combination structure of these layers so that the outside of the curved portion is an organic fiber cord layer and the inside is a steel cord layer,
The organic fiber cord layer contains at least 50% by mass of polyketone fiber, the maximum heat shrinkage stress of the cord is in the range of 0.1 to 1.8 cN / dtex, and the polyketone fiber is dried at 150 ° C. for 30 minutes. It consists of a cord layer in which an organic fiber cord having a heat shrinkage rate in the range of 1% to 5% during heat treatment is covered with rubber,
The steel cord layer is composed of a cord layer in which a steel cord obtained by twisting steel filaments is covered with rubber,
The carcass ply includes two or more layers, the carcass ply including the organic fiber cord layer is disposed on the outer side in the tire radial direction, and the carcass ply including the steel cord layer is disposed on the inner side. .

（ｎは撚り数（回／１０ｃｍ）、Ｄはトータル表示デシテックス数、ρは繊維の比重（ｇ／ｃｍ³）である）で定義される撚り係数Ｎが下記式（ＩＩ）、
０．６ ≦ Ｎ ≦ ０．９ ・・・ （ＩＩ）
を満たすことが好ましく、さらに、前記有機繊維コード層のコード打込み数は、好ましくは５〜６０本／５０ｍｍである。 In the present invention, in the polyketone fiber, the tensile strength of the raw yarn is preferably 10 cN / dtex or more and the elastic modulus is preferably 200 cN / dtex or more, and the organic fiber cord layer has the following formula (I): ,

The twist coefficient N defined by (where n is the number of twists (times / 10 cm), D is the total display decitex number, and ρ is the specific gravity of the fiber (g / cm ³ )) is represented by the following formula (II):
0.6 ≦ N ≦ 0.9 (II)
Preferably, the number of cords driven in the organic fiber cord layer is preferably 5 to 60/50 mm.

  According to the present invention, a run-flat tire, particularly a flatness ratio (tire height) that has improved safety and comfort by highly balancing running durability in a run-flat state and vibration and ride comfort at normal internal pressure. It is possible to provide a run-flat tire for a passenger car having a cross-sectional shape with a thickness / tire width) of 60% or less.

(Embodiment 1)
FIG. 1 shows a typical half-section in the width direction of a run flat tire according to a preferred embodiment 1 of the present invention. The run-flat tire shown in FIG. 1 is substantially radially arranged (specifically, arranged at an angle of 70 to 90 ° with respect to the tire equatorial plane E) between the bead cores 1 embedded in the pair of bead portions C. A carcass ply 2 is formed by folding one ply having a cord around the bead core 1 and the bead filler 5 from the inside to the outside.

  Further, in this tire, at least two inclined belt layers (in the illustrated example, two inclined belts) in which cords extending incline with respect to the tire equatorial plane E are arranged in parallel on the outer peripheral side of the crown portion of the carcass ply 2. A tread portion A reinforced by the main belt 3 comprising the layers 31, 32) is arranged.

  The main belt 3 may constitute an intersecting belt in which at least two inclined belt layers 31 and 32 among the inclined belt layers constituting the main belt 3 are laminated so that the cords intersect with each other across the tire equatorial plane E. preferable.

  Although not shown in the tread portion A, like a general tire, a plurality of circumferential grooves extending in the tire circumferential direction and / or a plurality of grooves extending in a direction crossing the circumferential groove are provided. A tread groove such as a transverse groove, a plurality of sipes, and the like are appropriately arranged depending on the application.

  In FIG. 1, a belt protective layer 7 in which a cord is arranged substantially parallel to the tire equatorial plane E is provided between the main belt 3 and the tread portion A so as to cover almost the entire width of the main belt 3. Is shown. The belt protective layer 7 is provided to prevent a tire failure due to belt end separation, and can be appropriately disposed as necessary, and may be disposed at least at both ends of the main belt 3. .

  Between the both end portions of the tread portion A and the bead portion, there is provided a sidewall portion B that connects them, and at least on the inner surface side of the carcass ply 2 across the sidewall portion B, a substantially crescent-shaped cross-sectional shape is provided. The side reinforcing rubber layer 6 is provided, and a so-called side reinforcing type run-flat tire structure is formed.

  In the first embodiment, the carcass ply 2 includes a fiber cord and a coating rubber that covers the fiber cord. That is, add a certain twist to the fiber, twist 2 to 3 strands, draw multiples of these as warp yarns, roughly smash thin and weak wefts into a sled, and then adhesive treatment to adhere to rubber I do. Thereafter, a topping rubber having a constant thickness is coated to obtain a rubber-coated cord.

  In Embodiment 1, the cord of the carcass ply 2 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, the performance of any of the strength, heat resistance, and adhesion to rubber as a tire becomes insufficient.

  The maximum heat shrinkage stress of the carcass ply 2 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 to be in When the maximum heat shrinkage stress is less than 0.1 cN / dtex, the run flat running durability cannot be sufficiently improved. 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 polyketone fiber contained in the cord of the carcass ply 2 has a heat shrinkage ratio in the range of 1% to 5%, preferably in the range of 2% to 4% at 150 ° C. for 30 minutes. 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.

  Furthermore, the tensile strength of the polyketone fiber contained in the cord of the carcass ply 2 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 cord of the carcass ply 2, 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, the run-flat running durability cannot be sufficiently improved.

（ｎは撚り数（回／１０ｃｍ）、Ｄはトータル表示デシテックス数、ρは繊維の比重（ｇ／ｃｍ³）である）で定義される撚り係数Ｎが下記式（ＩＩ）、
０．６ ≦ Ｎ ≦ ０．９ ・・・ （ＩＩ）
を満たすことが好ましく、さらには下記式（ＩＩＩ）、
０．７ ≦ Ｎ ≦ ０．８５ ・・・ （ＩＩＩ）
を満たすことが、より好ましい。この係数が０．６未満の場合にはカーカスプライコードに要求される耐疲労性が低下し、結果としてタイヤ耐久性が低下するという問題が生じる。一方、０．９より大きい場合には撚糸の撚り戻りが大きく、作業性が著しく悪化する。 Next, the following formula (I) of the carcass ply 2 cord:

The twist coefficient N defined by (where n is the number of twists (times / 10 cm), D is the total display decitex number, and ρ is the specific gravity of the fiber (g / cm ³ )) is represented by the following formula (II):
0.6 ≦ N ≦ 0.9 (II)
Preferably, the following formula (III),
0.7 ≦ N ≦ 0.85 (III)
It is more preferable to satisfy. When this coefficient is less than 0.6, the fatigue resistance required for the carcass ply cord is lowered, resulting in a problem that the tire durability is lowered. On the other hand, when it is larger than 0.9, the twist back of the twisted yarn is large, and the workability is remarkably deteriorated.

  An insert 4 made of at least one steel cord layer (one layer in the illustrated example) is disposed in the side wall portion B region and inside the carcass ply 2.

  By disposing the insert 4, it is possible to suppress deformation of the side reinforcing rubber layer 6 during run-flat traveling while suppressing an increase in the vertical spring coefficient during normal traveling. Durability during run-flat can be improved while maintaining ride comfort.

  That is, since the steel cord layer having high bending rigidity is arranged inside the carcass ply 2 by the arrangement of the insert 4, the neutral axis of bending exists between the carcass ply 2 and the insert 4, and the carcass ply 2 Is the tension side, and the insert 4 is the compression side. Thereby, since the tensile rigidity of the carcass ply 2 made of the organic fiber cord is large at the time of run flat running, the side reinforcing rubber layer 6 acts in a direction in which the side reinforcing rubber layer 6 is not easily crushed, and as a result, run flat durability is improved. Further, since the insert 4 made of steel cord has a high bending rigidity, the side reinforcing rubber layer 6 acts in a direction in which the side reinforcing rubber layer 6 is not easily crushed in conjunction with the carcass ply 2.

  This insert 4 is a cord layer in which a steel cord twisted with steel filaments is covered with rubber. The diameter of the steel filament is preferably 0.1 to 0.4 mm, and the twisted structure may be 1 × 3, 1 × 4, 1 × 5, or the like. The number of cords to be driven is preferably 5 to 30/50 mm.

  The width and arrangement location of the insert 4 are determined as appropriate so that the above-described effect can be satisfactorily exhibited. Preferably, the height E1 of the insert 4 from the bead base portion to the inner end in the tire radial direction is set to a position of 20 to 40% of the tire height h. If this value is less than 20%, the steel cord reaches the bead portion C, and the bending direction is reversed at this point and becomes the pulling side. Can't be used. However, since the steel cord has high tensile rigidity, there is no particular problem even if the steel cord reaches the bead portion C. On the other hand, if it exceeds 40%, the curved portion of the sidewall B region cannot be sufficiently covered, which is not preferable. The outer end of the insert 4 in the tire radial direction preferably reaches the vicinity of the belt end of the belt 3. However, even if the height E2 from the bead base portion to the outer end is larger than 80% of the tire height h, the side reinforcing rubber layer 6 has already been sufficiently covered, so that an increase in the effect can no longer be expected. That is, even if it reaches the inner side in the width direction than the belt 3, the effect of suppressing the collapse of the side reinforcing rubber layer 6 is not enhanced.

(Embodiment 2)
In the second embodiment, instead of the insert 4 (see FIG. 1) of the first embodiment, as shown in FIG. 2, the insert 41 is arranged in the region of the bead portion C and outside the carcass ply 2. Are all the same as in the first embodiment. In addition, you may apply the insert 4 and the insert 41 of Embodiment 1 together.

  As described above, when the steel cord insert 41 having a high bending rigidity is arranged outside the carcass ply 2 in the bead portion C, the steel cord becomes the compression side and the side reinforcing rubber layer 6 tends to be crushed (sidewall portion B). As a result, the run-flat durability is improved.

  At this time, the height E11 of the insert 41 from the bead base portion to the inner end in the tire radial direction is preferably set to a position of 10 to 25% of the tire height h. Even if it is put in a place smaller than 10%, the vicinity is pressed by the rim, so there is almost no deformation and there is no point in putting it. On the other hand, if it exceeds 25%, the curved portion of the bead portion C region cannot be sufficiently covered, which is not preferable. Further, the height E12 of the insert 41 from the bead base portion to the outer end in the tire radial direction is preferably set to a position of 20 to 35% of the tire height h. If it is less than 20%, the curved portion of the bead portion C cannot be sufficiently covered. On the other hand, if it is larger than 35%, the insert 41 reaches the side wall portion B. However, in this portion, the carcass ply is resistant to pulling at high temperatures. This is because it is more efficient to let 2 pay.

  In the second embodiment, it is only necessary that the insert 41 is disposed outside the carcass ply 2. Therefore, as in the inserts 42 and 43 shown in FIGS. 3 and 4, respectively, the inner carcass ply 2 of the folded carcass ply 2 is used. However, the same effect can be obtained even outside.

(Embodiment 3)
In the third embodiment, the carcass ply 20 shown in FIG. 5 includes a cord layer in which a steel cord twisted with steel filaments is covered with rubber. The diameter of the steel filament of this cord, the twisted structure, and the number of cords to be driven can be the same as in the insert of the first embodiment.

  Further, an insert 44 made of at least one layer (one layer in the illustrated example) of organic fiber cord layers in the circumferential direction is disposed in the region of the sidewall portion B and outside the carcass ply 20. This organic fiber cord layer is the same as the organic fiber cord layer of the carcass ply in the first embodiment.

  By disposing the insert 44, the deformation of the side reinforcing rubber layer 6 can be suppressed during run-flat traveling while suppressing an increase in the vertical spring coefficient during normal traveling, as in the above embodiment. In addition, durability during run-flat can be improved while maintaining vibration and ride comfort during normal driving.

  That is, the organic fiber cord insert 44 is disposed outside the steel cord carcass ply 20 so that a neutral axis of bending exists between the carcass ply 20 and the insert 44, and the carcass ply 20 is the compression side insert. The 44 side is pulled. Thereby, since the tensile rigidity of the insert 44 made of the organic fiber cord is large at the time of run flat running, the side reinforcing rubber layer 6 acts in a direction in which the side reinforcing rubber layer 6 is not easily crushed. As a result, run flat durability is improved. Further, since the carcass ply 20 made of steel cord has a high bending rigidity, it acts in a direction in which the side reinforcing rubber layer 6 is not easily crushed in conjunction with the insert 44.

  The width and arrangement location of the insert 44 are determined as appropriate so that the above-described effect can be satisfactorily exhibited. Preferably, the height E21 of the insert 44 from the bead base portion to the inner end in the tire radial direction is set to a position of 20 to 40% of the tire height h. If this value is less than 20%, it reaches the bead portion C and here enters the compression region, so that it is counterproductive to put an organic fiber cord layer that is weak against compression. On the other hand, if it exceeds 40%, the curved portion of the sidewall B region cannot be sufficiently covered, which is not preferable. Further, it is preferable that the outer end of the insert 44 in the tire radial direction reaches the vicinity of the belt end of the belt 3. However, even if the height E22 from the bead base portion to the outer end is larger than 80% of the tire height h, the side reinforcing rubber layer 6 has already been sufficiently covered, so that the effect can no longer be expected. That is, even if it reaches the inner side in the width direction than the belt 3, the effect of suppressing the collapse of the side reinforcing rubber layer 6 is not enhanced.

  In the third embodiment, the structure is the same as that of the first embodiment except for the carcass ply and the insert.

(Embodiment 4)
In the fourth embodiment, instead of the insert 44 (see FIG. 5) of the third embodiment, as shown in FIG. 6, the insert 45 is arranged in the region of the bead portion C and inside the carcass ply 20. Are all the same as in the third embodiment. Note that the insert 44 and the insert 45 of the third embodiment may be applied simultaneously.

  Thus, when the insert 45 made of an organic fiber cord layer is arranged inside the carcass ply 20 made of a steel cord layer in the bead portion C, the steel cord becomes the compression side and the side reinforcing rubber layer 6 tends to be crushed ( Since it acts in a direction to resist against the side wall portion B), the run-flat durability is improved.

  At this time, the height E31 of the insert 45 from the bead base portion to the inner end in the tire radial direction is preferably set to a position of 10 to 25% of the tire height h. Even if it is put in a place smaller than 10%, the vicinity is pressed by the rim, so there is almost no deformation and there is no point in putting it. On the other hand, if it exceeds 25%, the curved portion of the bead portion C region cannot be sufficiently covered, which is not preferable. Further, the height E32 of the insert 45 from the bead base portion to the outer end in the tire radial direction is preferably set to a position of 20 to 35% of the tire height h. If it is larger than 35%, it reaches the side wall portion B and becomes on the compression side, so even if an organic fiber cord layer is inserted here, there is almost no effect in suppressing the crushing deformation of the side reinforcing rubber layer 6.

(Embodiment 5)
Although not shown, the carcass ply has two or more layers without using an insert, the carcass ply made of the organic fiber cord layer is arranged on the outer side in the tire radial direction, and the carcass ply made of the steel cord layer is arranged on the inner side. Even in a reinforced run-flat tire, the side reinforcing rubber layer 6 can be prevented from being crushed and deformed. In this case, in the bead portion C, the arrangement of the organic fiber cord layer and the steel cord layer in the curved portion is opposite to the arrangement intended in the present invention, but the effect of suppressing the deformation of the side reinforcing rubber layer 6 is suppressed. Since the side wall portion B is more effective than the bead portion C, such an arrangement can be achieved.

  Next, fibers containing at least 50% by mass 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.

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 carcass ply 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 1000 to 20000 dtex. If the total decitex per cord is in the range of 1000 to 20000 decitex, it is possible to achieve high rigidity and light weight compared to the steel cord, which is a merit of organic fibers. If the total decitex is less than 1000 decitex, sufficient high rigidity as a carcass ply cannot be obtained. On the other hand, if it exceeds 20000 decitex, the ply gauge becomes thick, resulting in an increase in tire mass and deterioration in tire quality. .

  Further, the maximum heat shrinkage stress of the cord is 177 ° C. obtained by heating a 25 cm long fixed sample of a 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) sometimes generated in the cord.

（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, the following general formula (IV),

(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 (IV), 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 (V),

(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 covering the carcass ply or the insert 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 run flat tire of the present invention is particularly effective in a passenger car run flat tire having a cross-sectional shape with a flatness ratio (tire height / tire width) of 60% or less.

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 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 weight (with respect to 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 stearyl sulfonate / 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 strength 15.6 cN / dtex, elongation 4.2%, and elastic modulus 347 cN / dtex. When this PK fiber was corded with a twist coefficient of 0.84 at a thickness of 1670 dtex / 2, it had a heat shrinkage stress of 0.9 cN / dtex and a dry heat shrinkage of 3.1%.

(Examples 1-3, Reference Examples 1-2, Comparative Examples 1-2, Conventional Examples 1-2)
Tires with a tire size of 225 / 60R17 were prototyped according to the specifications shown in Table 1 below, and run-flat durability and riding comfort during normal running were evaluated by the following test methods. In the table, “rayon” means a cord layer in which a rayon fiber cord of 1650 dtex / 3 is implanted with a number of implantations of 48, and “PK fiber” means the number of implantations of the PK fiber cord manufactured in the above preparation example. 48 is a cord layer in which a cord made by twisting five 1 × 3 × 0.22 (mm) steel filaments into a single layer is driven in 12 times. Respectively. In the test tire, these cord layers were used as carcass ply cords or inserts.

  The test tire is usually used under an air filling pressure of 230 kPa and a loaded load of 6.17 kN, but a crescent-shaped side section on the inside of the carcass ply so that it can withstand use at zero internal pressure. The reinforcing rubber layer 6 is provided with the thickness (maximum thickness) shown in Table 1 below. Furthermore, two steel belt layers 31 crossing each other, in which cords formed by twisting five 0.22 mm steel filaments in parallel are arranged in parallel, and an angle of 15 to 30 degrees with the axis line of the tire equator direction. , 32, and a belt protective layer 7 made of a ribbon-like aromatic polyamide fiber cord layer disposed on the outer side in the tire radial direction and wound substantially in the circumferential direction.

(Run flat durability)
Run-flat durability is a load test by pressing against a drum with a constant radius in a state where the internal pressure of the tire is 0 kPa (run-flat state) on a drum testing machine at a constant room temperature (38 ° C), and the speed is 80 km / h. The running time until the tire breaks down is measured. The load and speed during drum running are constant, and the longer the tire running time, the higher the durability effect. In the table, the drum running time of the conventional example 1 is set to 100, and the numerical values of the comparative example and the example are displayed as indexes. The higher the value, the greater the run-flat durability.

(Riding comfort during normal driving)
The normal spring constant (riding comfort index) for normal internal pressure is that the tire is filled with air pressure of 230 kPa, then a constant load is applied to the tire, and the deflection under the specified load is based on the relationship between the deflection in the load axis direction and the load. The slope of the load diagram is calculated. The lower this value, the smaller the input to the vehicle and the better the ride comfort. In the table, the longitudinal spring constant (kN / mm) of Conventional Example 1 was set to 100, and the numerical values of the comparative example and the example were displayed as an index. The larger the value, the better the ride comfort.

1 is a cross-sectional view of a run flat tire according to Embodiment 1 of the present invention. It is sectional drawing of the run flat tire which concerns on Embodiment 2 of this invention. It is sectional drawing of the other run flat tire which concerns on Embodiment 2 of this invention. It is sectional drawing of the further another run flat tire which concerns on Embodiment 2 of this invention. 2 is a cross-sectional view of a run flat tire according to Reference Example 1. FIG. 5 is a cross-sectional view of a run flat tire according to Reference Example 2. FIG.

Explanation of symbols

1 Bead core 2 Carcass ply 3 Belts 4, 41, 42, 43, 44, 45 Insert 5 Bead filler 6 Side reinforcing rubber layer 7 Belt protective layer A Tread part B Side wall part C Bead part

Claims (8)

It has a pair of left and right bead portions, a pair of sidewall portions that are continuous from the bead portion to the outside in the tire radial direction, and a tread portion that is continuous to both sidewall portions, and extends in a toroidal shape between the pair of bead portions. A carcass layer comprising one or more carcass plies that reinforce each of these parts, a belt layer disposed on the outer side in the tire radial direction of the carcass, and a crescent-shaped cross section disposed on the inner side of the carcass in the sidewall portion. In the run flat tire provided with the side reinforcing rubber layer,
At least one region of the sidewall portion region and the bead portion region is reinforced with a combination structure of these layers so that the outside of the curved portion is an organic fiber cord layer and the inside is a steel cord layer,
The organic fiber cord layer contains at least 50% by mass of polyketone fiber, the maximum heat shrinkage stress of the cord is in the range of 0.1 to 1.8 cN / dtex, and the polyketone fiber is dried at 150 ° C. for 30 minutes. It consists of a cord layer in which an organic fiber cord having a heat shrinkage rate in the range of 1% to 5% during heat treatment is covered with rubber,
The steel cord layer, Ri a steel cord twisting steel filaments Do from the code layer coated with rubber,
At least one layer of the carcass ply is made of the organic fiber cord layer, and an insert made of at least one steel cord layer is disposed in the sidewall region and inside the organic fiber cord layer. A characteristic run-flat tire. Run-flat tire according to claim 1, wherein the radially inner end of said insert has a bead base portion 20 to 40% of the position of the tire height h, and the outer end is located at the belt end vicinity of the belt layer. At least one layer of the carcass ply folded back from the inside to the outside from the bead core and the bead filler embedded in the bead portion is composed of the organic fiber cord layer, and is in the bead portion region and outside the organic fiber cord layer. The run flat tire according to claim 1 or 2 , wherein an insert made of at least one steel cord layer is disposed. There radially inner end of said insert disposed in the bead region from the bead base portion to 10% to 25% of the position of the tire height h, and claim 3, wherein the outer end is at the position of 20 to 35% Run flat tires. It has a pair of left and right bead portions, a pair of sidewall portions that are continuous from the bead portion to the outside in the tire radial direction, and a tread portion that is continuous to both sidewall portions, and extends in a toroidal shape between the pair of bead portions. A carcass layer comprising one or more carcass plies that reinforce each of these parts, a belt layer disposed on the outer side in the tire radial direction of the carcass, and a crescent-shaped cross section disposed on the inner side of the carcass in the sidewall portion. In the run flat tire provided with the side reinforcing rubber layer,
At least one region of the sidewall portion region and the bead portion region is reinforced with a combination structure of these layers so that the outside of the curved portion is an organic fiber cord layer and the inside is a steel cord layer,
The organic fiber cord layer contains at least 50% by mass of polyketone fiber, the maximum heat shrinkage stress of the cord is in the range of 0.1 to 1.8 cN / dtex, and the polyketone fiber is dried at 150 ° C. for 30 minutes. It consists of a cord layer in which an organic fiber cord having a heat shrinkage rate in the range of 1% to 5% during heat treatment is covered with rubber,
The steel cord layer is composed of a cord layer in which a steel cord obtained by twisting steel filaments is covered with rubber,
The run-flat tire characterized in that the carcass ply is composed of two or more layers, the carcass ply consisting of the organic fiber cord layer is arranged outside in the tire radial direction, and the carcass ply consisting of the steel cord layer is arranged inside. . The run-flat tire according to any one of claims 1 to 5 , wherein in the polyketone fiber, the tensile strength of the raw yarn is 10 cN / dtex or more and the elastic modulus is 200 cN / dtex or more. The organic fiber cord layer has the following formula (I),

The twist coefficient N defined by (where n is the number of twists (times / 10 cm), D is the total display decitex number, and ρ is the specific gravity (g / cm ³ ) of the fiber) is expressed by the following formula (II):
0.6 ≦ N ≦ 0.9 (II)
The run flat tire according to any one of claims 1 to 6 , wherein The run-flat tire according to any one of claims 1 to 7 , wherein the organic fiber cord layer has 5 to 60 cords / 50 mm.

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