JPH11334313A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire capable of exerting superior tire performance with a lightweight, inexpensive aliphatic polyketone effectively utilized. SOLUTION: A fiber cord for forming a carcass ply layer 4 has a structure -(CH2 -CH2 -CO)n -(R-CO)m -, (where, R is an alkylene group having a carbon number of 3 or more), and consists of a cord containing at least an aliphatic polyketone fiber having an n and m relation of 1.05>=(n+m)/n>=1.00. The fiber cord has a strength of 10 g/d or more, an elongation percentage of 2.25 g/d of 3.5% or less, and a fracture elongation of 5% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire using an aliphatic polyketone fiber as a reinforcing cord, and more particularly, to a lightweight and inexpensive tire by specifying the molecular skeleton and physical properties of the aliphatic polyketone fiber. TECHNICAL FIELD The present invention relates to a pneumatic radial tire capable of exhibiting excellent tire performance while effectively utilizing various aliphatic polyketone fibers.

[0002]

2. Description of the Related Art With an increasing interest in responding to global warming, products with high economical efficiency have been demanded. On the other hand, there is a high demand for further improvement of tire running performance in an advanced automobile society. From the viewpoint of economy, simplification and automation of the tire manufacturing process have been attempted. As an example of this, in a radial tire for a passenger car having a two-ply carcass, studies are being made to improve productivity and reduce materials used by using one ply.

In general, when a two-ply carcass tire is simply made into one ply, the steering stability and the high-speed durability are likely to be reduced due to a reduction in the rigidity of the carcass layer. In addition, from the viewpoint of productivity improvement, when forming a carcass cord as in the past, a fiber cord is formed into a woven fabric, further subjected to adhesive heat treatment, coated with rubber, cut into a predetermined width, and then molded into a tire. In order to omit the complicated process of forming a carcass cord, an attempt has been made to form a carcass layer by continuously knitting a carcass cord on the surface of a mold having a sectional shape of a tire in advance.

When such a continuous braided structure is used, the carcass cord is locked to the bead by winding up the cut end of the carcass cord at the tire bead portion, and the rolled-up portion is placed outside the tire as in the prior art. By arranging, it becomes substantially difficult to increase the rigidity near the bead portion and to secure the rigidity of the tire. Such a structure greatly improves tire productivity because the material preparation process is largely omitted, but since the carcass has no roll-up at the bead, rigidity around the bead is reduced and tire handling stability is reduced. The problem that the performance and high-speed performance are deteriorated is likely to occur.

[0005] In order to solve the above-mentioned problems, a carcass material having high rigidity and high strength and excellent in economic efficiency was required. Conventionally, rayon fibers and polyethylene terephthalate fibers have been favorably used as carcass cords for radial tires for passenger cars. However, the production scale of rayon fiber has been shrinking worldwide due to problems of raw material resources and environmental problems such as odor during production. In addition, since rayon fiber has low strength, it is necessary to greatly increase the fiber cord and increase the number of cords to be used to make a two-ply carcass tire into one ply, and as a result, the tire weight cannot be reduced. There's a problem. In addition, rayon has the trouble that humidity control must be sufficiently performed because not only the strength but also the tensile modulus of the rayon decrease due to moisture absorption.

[0006] On the other hand, polyethylene terephthalate fiber has recently been used in the largest amount since it has been used most frequently since its strength has been increased with the improvement of spinning technology and its price has been lower than other synthetic fibers. It is the mainstream reinforcement material for carcass layers in radial tires.

However, the polyethylene terephthalate fiber cord has a production problem that a so-called two-bath treatment, for example, an RFL treatment after an epoxy resin treatment has to be applied in order to enhance the adhesion to rubber. is there. Furthermore, since the polyethylene terephthalate fiber cord has a lower modulus than the rayon fiber, when a carcass layer is formed into a tire, the outer diameter of the tire tends to grow during high-speed running. When the tire outer diameter grows, the adhesive interface between the members is easily broken inside the tire, and the high-speed durability is apt to decrease. Therefore, it is not easy to convert a tire having a two-ply carcass using a polyethylene terephthalate fiber cord into a carcass layer to 1PLY without deteriorating performance.

It is known that aramid fiber has an extremely high potential in terms of strength and elastic modulus, and is used as a carcass cord for a special tire. However, aramid fibers are expensive and are not preferred in terms of economy. In addition, since aramid fiber is inferior in fatigue durability, it is necessary to increase the number of twists before use. When the number of twists is increased, the tensile elastic modulus decreases, and there is a disadvantage that it is difficult to effectively use the high elastic modulus inherent in aramid fibers.

For this reason, there has been a demand for the development of a new material having excellent strength, elastic modulus and economy as a carcass cord for a pneumatic radial tire. On the other hand, a steel belt layer is used for a belt portion of a pneumatic radial tire due to its excellent strength and elastic modulus. In this steel belt layer, the cords between the plies cross each other at a relatively small angle (10 degrees to 30 degrees) with respect to the tire circumferential direction, and the belt layer has cut surfaces at both ends in the width direction.
The structure was composed of layers. However, since the steel belt layer has a large specific gravity, the tire weight becomes large, and further, stress is concentrated on the cut surface, separation easily occurs between the steel layer and the rubber layer, and high-speed durability is deteriorated. there were.

As a method for improving the high-speed durability of a tire having a steel belt layer, an attempt has been made to improve the high-speed durability by arranging an organic fiber cord substantially parallel to the tire circumferential direction above the tread side of the steel belt layer. It has been done. However, there is a disadvantage that adding an organic fiber cord layer in addition to the steel belt layer further increases the tire weight.

As a method of avoiding the problem of the belt layer using such a steel cord, a lightweight, high-strength steel is used.
Attempts have been made to use a high elastic modulus aramid fiber for the belt layer. However, aramid fibers have the disadvantages of poor adhesion to rubber and poor bending fatigue resistance. Therefore, in order to adhere the aramid fiber to the rubber, a complicated process such as performing an RFL process after treating with an epoxy resin or an isocyanate in advance is required. Further, when twisting the fiber into a cord in order to improve the bending fatigue resistance, as a result of imparting a high twist number, a method such as increasing the number of cords to be driven in order to reduce the strength and the elastic modulus occurs. Necessary and not economical.

Therefore, there has been a demand for the development of a new organic fiber material having good adhesiveness and excellent strength and elasticity as a belt cord for a pneumatic radial tire. In recent years, JP-A-1-124617, JP-A-2-112413, U.S. Pat. No. 5,194,210, and JP-A-9-3
The aliphatic polyketone fiber disclosed in Japanese Patent No. 24377 has high strength and high modulus properties, has good adhesion to rubber, and is inexpensive because it uses carbon monoxide and olefin. For this reason, the possibility as a tire cord has been pointed out.

However, in applying the aliphatic polyketone fiber to a tire, no specific technique for effectively exhibiting tire performance has been disclosed.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to use a novel aliphatic polyketone fiber cord instead of a polyethylene terephthalate fiber cord as a reinforcing material for a carcass layer, that is, a carcass cord, which is lightweight and economical. Excellent in high-speed durability, load durability, handling stability, riding comfort, and also capable of maintaining trauma resistance.
An object of the present invention is to provide an excellent pneumatic radial tire as a plykercass tire.

Another object of the present invention is to use a novel aliphatic polyketone fiber cord for the belt layer to achieve high-speed durability, light weight without impairing maneuverability, excellent ride comfort, and high economic efficiency. An object of the present invention is to provide a pneumatic radial tire.

[0016]

A pneumatic radial tire according to the present invention for achieving the above object has a structure in which a fiber cord forming a carcass layer has a structure represented by the following formula (1):
And m, a cord containing at least an aliphatic polyketone fiber in which 1.05 ≧ (n + m) /n≧1.00, and the fiber cord has a strength of 10 g / d or more and 2.25 g.
/ D is 3.5% or less and the elongation at break is 5%
% Or more.

(1) Formula — (CH ₂ —CH ₂ —CO) n— (R—CO) m— where R is an alkylene group having 3 or more carbon atoms. We focused on the characteristics of high strength and high elastic modulus, and studied to apply this to the carcass layer of a pneumatic radial tire. As a result, aliphatic polyketone fibers having a specific molecular skeleton can achieve a high balance between economy and tire performance, and exhibit more excellent tire performance by optimizing the properties of the rubber covering the fibers. The inventors have found that it is possible, and have accomplished the present invention.

According to another aspect of the present invention, there is provided a pneumatic radial tire in which a carcass layer is suspended between a pair of left and right bead portions, and a belt layer is disposed outside the carcass layer in a tread portion. In the filled radial tire, the fiber cord forming at least one belt layer has a structure represented by Formula (1), and the relationship between n and m is 1.05 ≧ (n + m) /n≧1.00. It is made of a cord containing at least a certain aliphatic polyketone fiber, and has an elongation of not less than 10 g / d and not more than 3.0% at 2.25 g / d.

(1) Formula — (CH ₂ —CH ₂ —CO) n— (R—CO) m— where R is an alkylene group having 3 or more carbon atoms The present inventor has proposed a novel aliphatic polyketone fiber. Focusing on the characteristics of high strength and high modulus of elasticity, we studied to apply this to the belt layer of pneumatic radial tires. As a result, aliphatic polyketone fibers having a specific molecular skeleton can achieve a high balance between economy and tire performance, and exhibit more excellent tire performance by optimizing the properties of the rubber covering the fibers. The inventors have found that it is possible, and have accomplished the present invention.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 illustrates a pneumatic radial tire according to an embodiment of the present invention. In FIG. 1, a pair of left and right bead portions 1 and a sidewall portion 2 and a tread portion 3 connected to both sidewall portions are provided. A carcass layer 4 is mounted between the bead portions 1 and 1, and an end of the carcass layer 4 is The tire is wound around the bead core 5 from the inside of the tire to the outside. In the tread portion 3, a belt layer 6 is arranged outside the carcass layer 4 over one circumference of the tire.

In the present invention, the carcass layer 4 is formed of a cord containing at least an aliphatic polyketone fiber.
The aliphatic polyketone fiber used here is disclosed in JP-A-1-124.
No. 617, JP-A-2-112413, US Pat. No. 5,194,210, JP-A-9-324377, etc. can be obtained by melt spinning or wet spinning. Having the structure
In the present invention, it is essential to use an aliphatic polyketone fiber in which the relationship between n and m is 1.05 ≧ (n + m) /n≧1.00.

(1) Formula — (CH ₂ —CH ₂ —CO) n— (R—CO) m— where R is an alkylene group having 3 or more carbon atoms, wherein m is a fraction (alkylene unit other than ethylene) )
When the number of tires increases, the running growth of the tire increases, and the durability decreases. This is probably because the crystal structure of the spun fiber changes due to the increase in m units, and the secondary bonding force between molecular chains decreases. In addition, when the strength of the fiber is reduced, the strength is further reduced when the twisted cord is used, so it is necessary to use a large amount of cord to secure the breaking strength of the tire, and it is possible to provide a lightweight and highly economical tire. It will be difficult.
Here, it is more preferable to use an alternating copolymer consisting essentially of ethylene and carbon monoxide, where m = 0. To produce such fibers, it is preferred to use wet spinning.

Further, as the carcass cord used in the present invention, the tensile strength of the fiber cord in a tire is 10 g / g.
It is necessary to use a fiber cord having an elongation at 3.5 d or more and 2.25 g / d at 3.5% or less and a breaking elongation of 5% or more.

[0024] The reason is that, when a two-ply carcass is used, when one ply is used, lightness is exhibited while maintaining tire performance equivalent to that of a conventional two-ply structure, and furthermore, it is economically excellent. This is to provide tires. If the tensile strength of the carcass cord is less than 10 g / d, it is necessary to increase the number of carcass cords to be driven or to increase the thickness of the cord. However, if the number of drivings is too large, the rubber between the curse cords is substantially absent, and the adhesive breakdown between the carcass layer and the surrounding rubber layer is likely to occur, resulting in a decrease in durability. On the other hand, as the cord becomes thicker, the carcass layer becomes thicker, making it difficult to secure lightness. When the elongation at 2.25 g / d exceeds 3.5%, 1
When a ply carcass is used, the tire radial growth during high-speed running due to insufficient rigidity of the tire is increased, and high-speed durability is reduced, and steering stability is likely to be reduced. Further, when the elongation at break is less than 5%, there is a problem that the breaking resistance due to an external impact on the tire side portion is reduced.

In the present invention, the tan δ at 60 ° C. of the coated rubber covering the carcass cord is 0.08 to 0.1.
It is preferably in the range of 3. This is based on the finding that the aliphatic polyketone fiber used in the present invention has a low glass transition temperature, and the tensile modulus decreases as the temperature rises from a normal temperature range. In addition, the fibers are based on the finding that the compression properties decrease and the creep properties increase in a higher temperature range. These phenomena occur only for 100
It is considered that the transition of the crystal structure of the fiber occurs in a temperature range of a little over ℃ and the secondary bonding force between molecular chains is reduced.

Therefore, if the heat generated by the coating rubber in which the carcass cord is embedded is high, the steering performance of the tire and the durability at high speed tend to be reduced. When tan δ exceeds 0.13, the heat generation of the carcass coat rubber increases, and the heat generation causes a large decrease in the tensile modulus of the fiber cord in the tire, resulting in a decrease in high-speed durability and steering stability performance. Meanwhile, tan
When δ is less than 0.08, the vibration riding comfort characteristics of the tire deteriorate. Where tan δ is 10% initial strain, ± 2% dynamic strain, and 20% frequency using a viscoelastic spectrometer.
Hz and a temperature of 60 ° C.

Further, in the present invention, the carcass cord is made of aliphatic polyketone fiber having a glass transition temperature of 60 ° C. or more, a strength of 8 g / d or more, and an initial tensile modulus of 100 g / d.
It is preferable to use a cord obtained by twisting fibers having a breaking elongation of 5% or more with d or more.

This is based on the finding that the tensile modulus of the aliphatic polyketone fiber decreases as the temperature rises as described above. Normally, the temperature at the time of running the tire is 60 to 80 ° C. The degree of decrease in the tensile modulus can be suppressed by combining with a fiber material having a glass transition temperature higher than this temperature range. It is possible to suppress performance degradation to a higher degree. However, even if the fiber to be twisted has a high glass transition temperature, if the strength is low, it is difficult to secure the strength as a tire. On the other hand, when the elastic modulus is low, the effect of suppressing the decrease in steering stability performance and high-speed durability is reduced. Further, when the elongation at break of the fiber to be twisted is less than 5%, it is insufficient to secure the trauma resistance of the tire side portion.

Examples of such fibers include polyethylene terephthalate fiber, polyethylene-2,6-naphthalate fiber, and polyvinyl alcohol fiber, and polyethylene-2, which has a higher tensile modulus and glass transition temperature.
6-Naphthalate fibers and polyvinyl alcohol fibers are more preferred. In addition, as a method of twisting these fibers and the aliphatic polyketone fiber, a method in which each fiber is separately twisted and then twisted together, and the respective fibers are firstly twisted together. In addition,
Further, a method of adding a twist to these composite twisted yarns is used.

Further, in the present invention, a carcass layer formed by locking the end of the carcass layer formed of the fiber cord at the bead portion without winding up from the inside to the outside of the tire at the bead portion is formed. Is preferred. Normally, in a pneumatic radial tire, the end of the carcass layer 4 is wound around the bead core 5 from the inside of the tire to the outside as shown in FIG.

However, from the viewpoint of using the carcass cord used in the present invention to provide a tire that is highly economical, lightweight, and excellent in tire performance, the structures shown in FIGS. 2A to 2C are applied. Is more preferable. That is, FIG.
In the structure of (1), the bead core 5 is formed in two layers in the tire radial direction, and the end of the carcass layer 4 is sandwiched between the upper bead layer 5a and the lower bead layer 5b of the bead core 5 from the inside to the outside of the tire, The end of the carcass layer 4 is locked without being wound up outside the bead core 5. The carcass layer 4 is knitted by reciprocating the carcass cord in the tire width direction, and has a structure having no cut end at its end.

FIGS. 2B and 2C illustrate another structure in which the end of the carcass layer 4 is locked along the bead core 5 without being rolled up outside the bead core 5. FIG. In this case, the end of the carcass cord passes through the inside of the tire from the bead core 5 and is locked at a position on the inner end side of the bead core 5. In particular, since the carcass cord of the present invention has a high tensile modulus of elasticity, it is possible to avoid a decrease in the rigidity of the tire even if the carcass layer does not have a rolled-up structure. A tire having excellent properties can be provided.

Further, the aliphatic polyketone fiber used in the carcass cord of the present invention tends to change its crystal morphology and decrease in compression characteristics when the temperature used increases. Therefore, FIG. 2 shows that the carcass layer is not disposed outside the tire.
By applying the structures (a) to (c), it is possible to prevent the carcass cord from receiving compressive stress, and it is possible to suppress a decrease in the load durability of the tire.

Further, the fiber cord used for the carcass cord in the present invention has a twist coefficient K represented by K = T√D of 12
It is preferably in the range of 00 to 2200, and the total denier of the code is preferably 2000D to 4000D. If the twist coefficient K is less than 1200, it is not only difficult to secure fatigue resistance, but also the elongation at break is reduced and the damage resistance is deteriorated. 2
If it exceeds 200, the modulus is greatly reduced, and it is difficult to secure steering stability and high-speed durability. If the total denier number of the cord is less than 2000D, the number of strikes increases and the productivity deteriorates. On the other hand, if it exceeds 4000D, the number of ends is reduced, the trauma resistance is reduced, and the thickness of the carcass layer is increased, so that the tire weight is increased. Here, K is a twist coefficient, T is the number of twists of the cord (twice / 10 cm), and D is the total denier of the cord.

FIG. 3 illustrates a pneumatic radial tire according to another embodiment of the present invention. The pneumatic radial tire of the present invention includes a pair of left and right bead portions 1, a sidewall portion 2, and a tread portion 3 connected to both sidewall portions, and a carcass layer 4 is mounted between the bead portions 1, 1, and a carcass layer The end of the tire 4 is wound around the bead core 5 from the inside to the outside of the tire.
In the tread portion 3, the outside of the carcass layer 4 is
A belt layer 6 is arranged over one circumference of the tire.

In the present invention, at least one belt layer 6 is formed of a cord containing at least an aliphatic polyketone fiber. The aliphatic polyketone fibers used here are disclosed in JP-A-1-124617 and JP-A-2-112413.
Gazette, U.S. Pat.
It can be obtained by melt spinning or wet spinning disclosed in, for example, Japanese Patent No. 324377, and has a structure represented by the following formula (1), and the relationship between n and m is 1.05 ≧ (n + m) /
In the present invention, it is essential to use an aliphatic polyketone fiber having n ≧ 1.00.

(1) Formula — (CH ₂ —CH ₂ —CO) n— (R—CO) m— where R is an alkylene group having 3 or more carbon atoms, where m is a fraction (alkylene unit other than ethylene) )
When the number of tires increases, the growth of the belt portion during tire running increases, and the durability also decreases. This is probably because the crystal structure of the spun fiber changes due to the increase in m units, and the secondary bonding force between molecular chains decreases. In addition, when the strength of the fiber is low, the strength is further reduced when a twisted cord is used, so it is necessary to use a large amount of the cord in order to secure the breaking strength of the tire, and it is possible to provide a lightweight and economical tire. It will be difficult. Here, it is more preferable to use an alternating copolymer consisting essentially of ethylene and carbon monoxide, where m = 0. To produce such fibers, it is preferred to use wet spinning.

Further, the belt cord used in the present invention has a fiber cord having a tensile strength of 10 g / d in a tire.
As described above, it is necessary to use a fiber cord whose elongation at 2.25 g / d is 3.0% or less.

If the tensile strength of the belt cord is less than 10 g / d, it is necessary to increase the number of belt cords to be driven or to increase the thickness of the cord. However, if the number of drivings is too large, the rubber between the belt cords is substantially absent, and the adhesion between the belt layer and the surrounding rubber layer is likely to occur, and the durability is reduced. On the other hand, when the cord is thick, the belt layer becomes thick, and it is difficult to secure the lightness. On the other hand, if the elongation at 2.25 g / d exceeds 3.0%, there is a problem that the growth in the radial direction of the tire at the time of high-speed running becomes large due to insufficient rigidity of the belt layer, and the high-speed durability is reduced. Is likely to be reduced.

In the present invention, the 100% modulus at 100 ° C. of the coated rubber covering the belt cord is 3.5.
It is preferably at least MPa. This is based on the finding that the aliphatic polyketone fiber used in the present invention has a low glass transition temperature, and the tensile modulus decreases as the temperature rises from a normal temperature range. In addition, the fibers are based on the finding that the compression properties decrease and the creep properties increase in a higher temperature range. These phenomena occur in 10
It is considered that the transition of the crystal structure of the fiber occurs in a temperature range slightly higher than 0 ° C., and the secondary bonding force between molecular chains is reduced.

[0041] 10 of the coated rubber for embedding the belt cord
If the modulus at 0 ° C. is less than 3.5 MPa, it becomes difficult to suppress a decrease in tire steering performance and a decrease in high-speed durability due to a decrease in the elastic modulus of the fiber cord due to heat generated during tire running. However, the modulus of the rubber was measured according to the tensile test of the vulcanized rubber physical test method described in K6301 of JIS (1995 version).

Further, the tan δ at 60 ° C. of the coated rubber in which the belt cord is embedded is preferably in the range of 0.16 to 0.22. When the tan δ exceeds 0.22, the heat generation of the tire belt layer increases, and it is difficult to sufficiently suppress the decrease in the rigidity of the belt layer even if the modulus of the coated rubber is large. On the other hand, when tan δ is less than 0.16, the vibration riding comfort characteristics of the tire deteriorate. Where ta
nδ is an initial strain of 10 using a viscoelastic spectrometer.
%, Dynamic strain ± 2%, frequency 20 Hz, temperature 60 ° C.

Further, in the present invention, the belt cord is made of an aliphatic polyketone fiber having a glass transition temperature of 60 ° C. or more, a strength of 8 g / d or more, and an initial tensile modulus of 100 g / d.
It is preferable to use a cord obtained by twisting fibers of d or more. This is based on the finding that the tensile modulus of the aliphatic polyketone fiber decreases as the temperature rises as described above. Normally, the temperature at the time of running the tire is 60 to 80 ° C. The degree of decrease in the tensile modulus can be suppressed by combining with a fiber material having a glass transition temperature higher than this temperature range. It is possible to suppress performance degradation to a higher degree. However, even if the fiber to be twisted has a high glass transition temperature, if the strength is low, it is difficult to secure the strength as a tire. On the other hand, when the elastic modulus is low, the effect of suppressing the decrease in steering stability performance and high-speed durability is reduced.

Examples of such fibers include aramid fiber, polyparaphenylene benzobisoxazole fiber, polyethylene terephthalate fiber, polyethylene-2,6-naphthalate fiber, and polyvinyl alcohol fiber, and have higher tensile modulus and glass transition temperature. Polyethylene-2,6-naphthalate fibers and aramid fibers are more preferred. In addition, as a method of twisting these fibers and the aliphatic polyketone fiber, a method in which each fiber is separately twisted and then twisted together, and the respective fibers are firstly twisted together. In addition, a method of adding a twist to these composite twisted yarns is used.

Further, in the present invention, FIG.
As shown in (b), a tape 6a in which one or a plurality of fiber cords are buried in a rubber matrix in parallel is provided on the outer periphery of the carcass layer 4 at an angle of 10 to 35 degrees with respect to the tire circumferential direction. It is preferable to form a substantially two-layer belt layer 6 by continuously turning while bending or folding at both ends in the width direction. By forming the belt layer 6 in this manner, the cut ends of the cords are substantially eliminated, so that not only the adhesive breakage at the end of the belt does not easily occur but also the rigidity in the circumferential direction of the tire is increased. It is possible to more effectively suppress the growth in the tire circumferential direction due to the decrease in tensile modulus due to temperature rise, which is a drawback of the used fiber cord, and to provide tires that are lighter, have high-speed durability, and have high steering stability. It becomes possible. Note that other examples of such a structure are shown in FIGS. 5A to 5C, but the present invention is not limited to this. R in the figure indicates the tire circumferential direction.

Further, it is more preferable that a belt cover layer 7 having an organic fiber cord disposed substantially parallel to the tire circumferential direction is provided on the tread side of the belt layer 6. By doing so, it is possible to suppress a reduction in the vibration riding comfort due to the periodicity of the belt layer formed by continuously bending or folding, and it is possible to provide a tire with more comfortableness. . The organic fiber cord used here is not particularly limited.
Nylon fiber, polyethylene terephthalate fiber, aramid fiber, etc. can be used, but by using the fiber cord used for the belt layer of the present invention, the belt layer and the belt cover layer can be formed continuously, so that productivity is increased and more economical It is possible to provide a highly reliable tire.

Further, the fiber cord used for the belt cord in the present invention has a twist coefficient K represented by K = T√D of 100.
0 to 2000, and the total denier number of the code is 3
It is preferably from 000D to 5000D. If the twist coefficient K is less than 1000, not only is it difficult to ensure fatigue resistance, but also the elongation at break decreases and the scratch resistance deteriorates. 20
If it exceeds 00, the modulus is greatly reduced, and it is difficult to secure steering stability and high-speed durability. If the total denier number of the cord is less than 3000D, the number of shots increases and the productivity deteriorates. On the other hand, if it exceeds 5000D, the weight of the tire increases because the thickness of the belt layer increases. Here, K is a twist coefficient, T is the number of twists of the cord (twice / 10 cm), and D is the total denier of the cord.

[0048]

[Embodiments] First, evaluations were made using various tire sizes of 195 / 65R15 for various carcass cords. Conventional example 1 uses a 1000 d / 2 polyethylene terephthalate fiber cord as a conventional carcass cord in a two-ply carcass structure.
The tire structure is a structure in which the end portion of the carcass shown in FIG. Comparative Example 1 is an example in which a polyethylene terephthalate fiber cord is used in a one-ply structure at 2000 d / 2, which is twice the thickness of Conventional Example 1. The tire structure is the structure shown in FIG.
In Comparative Example 2, 100 aramid fibers having excellent strength and elastic modulus were used.
This is an example using the structure shown in FIG. 1 as a one-ply carcass structure as a code of 0d / 2. Comparative Example 3 is an aliphatic polyketone fiber (abbreviated as POK-1 in the table).
(N + m) / n in the expression (1) is 1.07. Also,
R in the formula (1) is a propylene unit. The fiber has a yarn strength of 13.0 g / d and an initial modulus of 160 g.
/ D. 1000d / 3 due to low fiber strength
Is used as a one-ply carcass. FIG. 1 is applied to the carcass structure.

Example 1 is an aliphatic polyketone fiber (abbreviated as POK-2 in the table) of the present invention, wherein m in the formula (1)
0, that is, (n + m) / n = 1. The fiber has a raw yarn strength of 18.5 g / d and an initial modulus of 240 g / d. This is 1000d / 2 because of high fiber strength
Is used as one ply and the structure of FIG. 1 is used.

The cords of Conventional Example 1, Comparative Examples 1 to 3, and Example 1 are embedded in rubber having a tan δ of 0.15 at 60 ° C. The number of carcass shots was adjusted so that the total carcass strength of the tires was substantially equivalent. That is, the strength per fixed width is made constant.
In Example 2, the t of the carcass coat rubber of Example 1 was t
This is an example in which one different by an δ is used.

In the third embodiment, the tire structure is shown in FIG.
In this example, a structure in which the end portion of the carcass layer is not wound around the tire outside at the bead portion, and a cord having a lower twist coefficient is applied. Others are the same as the second embodiment. In Example 4, two ply-twisted yarns obtained by adding ply twist to the aliphatic polyketone fiber 1000d used in Example 1 as a carcass cord, and polyethylene-2,6-naphthalate fiber 1000d (glass transition temperature 120 ° C, strength 9.2 g /
d, the same as in Example 3, except that a twisted yarn obtained by adding a twist to the tensile elastic modulus of 220 g / d) was twisted to form a composite cord having a 1000 d / 3 structure.

The following method was used for the tire test. Tire high-speed durability test method: Using a drum tester having a smooth drum surface made of steel and having a diameter of 1707 mm, controlling the ambient temperature to 38 ± 3 ° C., rim size 15 × 6JJ,
Under the conditions of a test internal pressure of 210 KPa and a speed of 81 km / h,
8 of the load corresponding to the pneumatic condition specified by JATMA
After running at 8% for 120 minutes, and then let cool for 3 hours or more, readjust the test air pressure and start the actual running. The actual running starts at a speed of 121 km / h, and the speed is increased stepwise by 8 km / h every 30 minutes until the breakdown occurs. The distance until the tire failure occurs is defined as an index, with the failure distance of the reference tire (conventional example 1) being 100, represented by an index, which is defined as high-speed durability. The higher the index value, the better the high-speed durability.

Tire load durability test method: Using a drum tester having a smooth drum surface made of steel and having a diameter of 1707 mm, controlling the ambient temperature to 38 ± 3 ° C. and setting the rim size to 1
5 × 6JJ, test internal pressure 180KPa, speed 81km / h
Under the conditions described above, the vehicle travels at 85% of the load corresponding to the pneumatic condition specified by JATMA for 4 hours, then at 90% of the maximum load for 6 hours, and then at the maximum load for 24 hours. Here, the driving is stopped once, and if there is no abnormality in the external appearance, the load is further increased to 115% of the maximum load for 4 hours, and then to 130% of the maximum load for 2 hours.
Run for hours. At this time, if an abnormality occurs in the appearance or inside, the test is rejected and the test is terminated. If no abnormality occurred, the vehicle was further run at 130% of the maximum load for 2 hours, then at 145% of the maximum load for 4 hours, and then at 16% of the maximum load.
Run until it breaks at 0%. As a result, a value expressed by an index when the running distance until breaking is set to 100 in Conventional Example 1 is defined as load durability. The larger the index value, the better the load durability.

Driving stability test method: Displacement of a test tire incorporated in a 15 × 6JJ rim at an internal pressure of 210 KPa.
Trained on a 5-liter class domestic car and trained
A driver runs on a test course and evaluates the feeling. The results were scored by a 5-point scale based on the following criteria based on a relative comparison with the reference tire (conventional example 1), and expressed as an average score of three people excluding the highest point and the lowest point. Judgment criteria 5: Excellent, 4: Excellent, 3.5: Somewhat excellent, 3: Equivalent to standard, 2.5: Somewhat inferior (lower practical limit), 2: Inferior, 1: Inferior

Test method for riding comfort in a real vehicle: A test tire assembled in a 15 × 6JJ rim at an internal pressure of 210 KPa was mounted on a 2.5-liter class domestic passenger car, and the test course was trained by five trained drivers. Run and evaluate the feeling. The results were scored by a 5-point scale based on the following criteria based on a relative comparison with the reference tire (conventional example 1), and expressed as an average score of three people excluding the highest point and the lowest point. Judgment criteria 5: Excellent, 4: Excellent, 3.5: Somewhat excellent, 3: Equivalent to standard, 2.5: Somewhat inferior (lower practical limit), 2: Inferior, 1: Inferior

Evaluation method of the scratch resistance of the carcass layer: 70 cm height at the tire maximum width position using an indoor scratch resistance tester.
m, impact load 20Kg, cutter impact area 5mm × 2
Measure the number of times until it is broken by repeatedly applying an impact at 5 mm. X indicates that the sample was broken by 5 or less impacts, × indicates the sample was broken by 6 to 10 impacts, and ○ indicates that the sample was exceeded 10 times.

Table 1 shows the test results obtained by the above test methods.

[0058]

[Table 1]

As is apparent from Table 1, in Comparative Example 1 in which the polyethylene terephthalate fiber of the two-ply carcass of the conventional example 1 was simply made into a thick denier to be made into one ply, the tire weight could be reduced, but the high speed of the tire could be reduced. durability,
Load durability and steering stability are reduced. On the other hand, Comparative Example 2 uses an aramid fiber having a high tensile modulus, so that the high-speed durability is equal to or higher than that of Conventional Example 1.
However, since the aramid fiber is inferior in compression fatigue resistance, the load durability of the tire decreases. Further, it can be seen that the aramid fiber has a low elongation and cannot withstand a strong impact from the outside, so that its abrasion resistance is reduced.

In Comparative Example 3, an aliphatic polyketone fiber was used for the carcass cord, but (n + m) / n was 1.0.
It is more than five. As is clear from the table, the high-speed durability, the load durability, and the steering stability are lower than those of the conventional example 1, and the improvement effect is smaller than that of the comparative example 1. This is because (n + m) / n of the fiber cord is 1.0
It is considered that, since it exceeds 5, the creep property due to the crystal structure of the fiber promotes tire running growth and does not provide improvement in high-speed durability. In addition, it is considered that the improvement in load durability cannot be obtained because the interaction between molecular chains derived from the crystal structure is small. Further, the fiber cord has a low strength and a thick denier is used as the cord, so that the lightness is reduced.

On the other hand, the first embodiment of the present invention is (n + m) / n
Since there is no problem caused by the crystal structure as described above, high-speed durability and load durability are improved as compared with Comparative Example 1, and the two-ply carcass of Conventional Example 1 is used. The same level of tire performance is obtained, and weight reduction is achieved by using one ply.

In Example 2, the coated rubber of Example 1 was used.
This is an example in which tan δ at ° C. is significantly reduced. Compared with the first embodiment, a clear improvement in high-speed durability and an improvement in steering stability are obtained. Because the temperature rise of the carcass layer due to running is reduced, particularly when the cord having a low glass transition temperature is used, the change in the elastic modulus of the cord is suppressed,
It is considered that such an effect can be obtained. In Comparative Example 4, as in Comparative Example 1, polyethylene terephthalate fiber was used for the carcass cord, and the tan δ of the coated rubber was changed to that of Example 2.
However, in this example, there is almost no improvement effect in comparison with Comparative Example 1. This is presumably because the glass transition temperature of the polyethylene terephthalate fiber is high, so that the carcass coat rubber hardly contributes to lower heat generation.

Example 3 is different from Example 2 in that the structure in which the number of twists of the cord is reduced is applied to the structure shown in FIG. 2A in which the end of the carcass layer is not substantially wound up outside the bead portion. This is an example similar to. By reducing the number of twists, the strength and elastic modulus of the cord are further improved, but the fatigue durability generally decreases. However, by applying the cord to the structure shown in FIG. 2A, it is possible to further reduce the weight without reducing the fatigue durability.

Example 4 is different from the carcass cord of Example 3 in that one strand of polyethylene-2,6-naphthalate fiber having a glass transition temperature of 120.degree. This is an example in which two cords are prepared by adding a lower twist to a fiber 1000d, and the cord is used as a carcass cord as 1000D / 3 obtained by adding the twists together. Since the thickness of the cord was set to 1000 D / 3 to compensate for the decrease in strength, the lightness was slightly reduced as compared with Example 3, but it was found that high-speed durability and steering stability were further improved.

Next, when the belt cords were made variously different, evaluation was made using 195 / 65R15 as the tire size. All tires have a two-ply carcass structure of a 1000 d / 2 polyethylene terephthalate fiber cord as a carcass cord (50 pieces / 5
cm) and only the belt layer was changed.

Conventional Example 11, Comparative Example 11, Examples 11 to 1
2 has a belt structure shown in FIG. Conventional example 11 uses a steel cord for the belt layer. Comparative Example 11 is an aliphatic polyketone fiber (abbreviated as POK-1 in the table).
Where (n + m) / n in the expression (1) is 1.07. Further, R in the formula (1) is composed of a propylene unit. The original yarn strength of this fiber is 13.0 g /
d, the initial modulus is 160 g / d. Since the fiber strength is low, a cord of 3000 d / 2 is used.

On the other hand, Examples 11 and 12 are aliphatic polyketone fibers of the present invention (abbreviated as POK-2 in the table), and m = 0 in the formula (1), that is, (n + m) / n = 1. It is. The fiber has a yarn strength of 18.5 g / d and an initial modulus of 240 g / d. Since it has a high fiber strength, it is used as a cord of 2000 d / 2 in the belt layer.

The belt coat rubbers of Conventional Example 11, Comparative Example 11, and Example 11 had a 100% modulus at 100 ° C. of 3.0 MPa, and tan δ at 60 ° C. was 0.1 MPa.
7 The belt coat rubber of Example 12 was 10
100% modulus at 0 ° C is 4.0MPa and 6%
The tan δ at 0 ° C. is 0.19.

The thirteenth embodiment uses the tire structure shown in FIG.
As shown in (a), a tape formed by embedding a plurality of fiber cords in parallel in a rubber matrix is continuously wound around the outer periphery of the carcass layer at both ends in the belt width direction at a predetermined angle with respect to the tire circumferential direction. And a belt layer substantially consisting of two layers formed by rotating the belt. However, no belt cover layer was provided.

The fourteenth embodiment uses the belt cord according to the first embodiment.
Aliphatic polyketone fiber 1500D having the same skeleton as that of No. 1
2 twisted yarns with added twist and polyethylene 2,6
-Naphthalate fiber 1500D (glass transition temperature 120
Example 13 except that a single twisted twisted yarn obtained by adding twisting to a temperature of 9.2 g / d and a tensile modulus of elasticity of 220 g / d) was twisted into a composite yarn of 1500 D / 3 having a three-strand structure.
Is the same as

Example 15 is an example in which the belt structure shown in FIG. That is, the belt layer is exactly the same as that of Example 14, but a so-called belt cover layer in which an organic fiber cord is continuously wrapped around one layer substantially parallel to the tire circumferential direction is disposed thereon. The belt cover cord used here uses the same aliphatic polyketone fiber cord 1000d / 2 as that used in Example 11. Otherwise, it is exactly the same as the thirteenth embodiment.

The number of cords of the belt layer was adjusted so that the total belt strength of the tires was substantially equivalent.
That is, the strength per fixed width is made constant. Further, the angles of the belt cords with respect to the tire circumferential direction were all 24 degrees.

The following method was used for the tire test. Tire high-speed durability test method: Using a drum tester having a smooth drum surface made of steel and having a diameter of 1707 mm, controlling the ambient temperature to 38 ± 3 ° C., rim size 15 × 6JJ,
Under the conditions of a test internal pressure of 210 KPa and a speed of 81 km / h,
8 of the load corresponding to the pneumatic condition specified by JATMA
After running at 8% for 120 minutes, and then let cool for 3 hours or more, readjust the test air pressure and start the actual running. The actual running starts at a speed of 121 km / h, and the speed is increased stepwise by 8 km / h every 30 minutes until the breakdown occurs. The high-speed durability is defined as the distance until the failure of the tire occurs, where the failure distance of the reference tire (conventional example 11) is 100 and the index is expressed as an index. The higher the index value, the better the high-speed durability.

Maneuvering stability test method: A test tire assembled in a 15 × 6JJ rim at an internal pressure of 210 KPa has a displacement of 2.
Trained on a 5-liter class domestic car and trained
A driver runs on a test course and evaluates the feeling. The results were scored on a 5-point scale based on the following criteria based on a relative comparison with a reference tire (conventional example 11).
It is represented by the average score of three people excluding the highest score and the lowest score. Judgment criteria 5: Excellent, 4: Excellent, 3.5: Somewhat excellent, 3: Equivalent to standard, 2.5: Somewhat inferior (lower practical limit), 2: Inferior, 1: Inferior

Test method for riding comfort on a real vehicle: A test tire assembled with a 15 × 6JJ rim at an internal pressure of 210 KPa was mounted on a 2.5-liter class domestic passenger car, and a test course was trained by five trained drivers. Run and evaluate the feeling. The results were scored by a 5-point scale based on the following criteria based on a relative comparison with a reference tire (conventional example 11), and represented by an average score of three persons excluding the highest point and the lowest point. Judgment criteria 5: Excellent, 4: Excellent, 3.5: Somewhat excellent, 3: Equivalent to standard, 2.5: Somewhat inferior (lower practical limit), 2: Inferior, 1: Inferior Table 2 shows the test results by the above test methods. Shown in

[0076]

[Table 2]

As is clear from Table 2, the conventional example 11
Comparative Example 11 using an aliphatic polyketone fiber for the belt cord instead of the steel cord belt of (1), in which (n + m) / n exceeds 1.05, achieved a reduction in weight and improved ride comfort. The performance is also improved, but the high-speed durability is greatly reduced as compared with the conventional example 11. Example 1
Since the fiber strength is lower than that of No. 1 and a thick cord is used, the lightness is also reduced. On the other hand, the eleventh embodiment of the present invention uses a cord in which (n + m) / n is 1.0, so that the high-speed durability maintains the same level of performance as that of the conventional example 11 while improving the lightness and ride comfort. Have been obtained. Example 11 was improved in controllability and high-speed durability compared to Comparative Example 11 because the ratio of (n + m) / n was optimized.
It is considered that the decrease in the interaction between molecular chains caused by the crystal structure of the fiber was suppressed, the growth of the fiber was reduced, and the tire running growth was reduced.

In Example 12, the 100% modulus at 100 ° C. of the coated rubber of Example 11 was increased.
As a result, a clear improvement in steering stability is obtained as compared with the eleventh embodiment. For this reason, the tire is lightweight and has excellent ride comfort without impairing high-speed durability and steering stability as compared with Conventional Example 11. In Example 13, the belt layer was continuously formed, and as a result, high-speed durability and steering stability were greatly improved as compared with Example 12.

Example 14 is an example in which a polyethylene-2,6-naphthalate fiber having a glass transition temperature of 120 ° C. and an aliphatic polyketone fiber are twisted and used as a carcass cord instead of the belt cord of Example 13. is there. In this case, the thickness of the cord is set to 1500D to compensate for the decrease in strength.
As a result, the lightness was slightly reduced as compared with Example 13, but it was found that the high-speed durability and the steering stability were further improved.

Example 15 is an example in which a belt cover layer is disposed using the same code as the belt code in Example 13. Although the lightness is impaired by the arrangement of the belt cover layer, it can be seen that high-speed durability and steering stability are also improved, and that riding comfort is greatly improved. This is presumably because the periodicity of the belt layer caused by the continuous formation of the belt layer was alleviated by using the belt cover layer in combination, so that the riding comfort was greatly improved.

[0081]

As described above, according to the present invention, an aliphatic polyketone fiber is used for a reinforcing cord of a carcass layer or a belt layer, and the molecular skeleton of the aliphatic polyketone fiber and the physical properties of the cord are specified. In addition, excellent tire performance can be exhibited while effectively using inexpensive aliphatic polyketone fibers.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pneumatic radial tire according to an embodiment of the present invention.

2A is a cross-sectional view showing a modified example of the pneumatic radial tire of FIG. 1, and FIGS. 2B and 2C are cross-sectional views showing further modified examples.

FIG. 3 is a perspective sectional view showing a pneumatic radial tire according to another embodiment of the present invention.

4A is a sectional view showing a modification of the pneumatic radial tire shown in FIG. 3, and FIG. 4B is a perspective view showing a belt structure thereof.

5 (a) to 5 (c) are plan views showing modified examples of a belt layer in the pneumatic radial tire of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Carcass layer 5 Bead core 6 Belt layer 6a Tape 7 Belt cover layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B60C 15/00 B60C 15/00 DH D02G 3/48 D02G 3/48

Claims (10)

[Claims] 1. A fiber cord forming a carcass layer has a structure represented by formula (1), and the relationship between n and m is 1.0.
It is made of a cord containing at least an aliphatic polyketone fiber satisfying 5 ≧ (n + m) /n≧1.00, and the fiber cord has a strength of 10 g / d or more and an elongation of 3.5% or less at 2.25 g / d. And a pneumatic radial tire having a breaking elongation of 5% or more. (1) _{- (CH 2 -CH 2 -CO)} n- (R-CO) m- wherein R is an alkylene group having 3 or more carbon atoms 2. The pneumatic radial tire according to claim 1, wherein the carcass layer has a one-ply structure. 3. The pneumatic radial tire according to claim 1, wherein the tan δ at 60 ° C. of the coated rubber covering the fiber cord is in a range of 0.08 to 0.13. 4. The fiber cord has a glass transition temperature of at least 60 ° C. and a strength of 8 g / d with the aliphatic polyketone fiber.
The pneumatic radial tire according to any one of claims 1 to 3, wherein a fiber having an initial tensile modulus of 100 g / d or more is twisted. 5. The pneumatic radial tire according to claim 1, wherein the carcass layer has a structure in which a bead portion has substantially no winding end. 6. A pneumatic radial tire in which a carcass layer is suspended between a pair of left and right bead portions and a belt layer is disposed outside the carcass layer in a tread portion, a fiber cord forming at least one belt layer is ( 1) having a structure represented by the formula, wherein the relationship between n and m is 1.05 ≧ (n +
m) / n ≧ 1 and a cord containing at least an aliphatic polyketone fiber with a fiber cord strength of 10
A pneumatic radial tire having an elongation at a g / d of 2.25 g / d of 3.0% or less. (1) _{- (CH 2 -CH 2 -CO)} n- (R-CO) m- wherein R is an alkylene group having 3 or more carbon atoms 7. The pneumatic radial tire according to claim 6, wherein the coated rubber covering the fiber cord has a 100% modulus at 100 ° C. of 3.5 MPa or more. 8. The fiber cord has a glass transition temperature of at least 60 ° C. and a strength of 8 g / d with the aliphatic polyketone fiber.
The pneumatic radial tire according to claim 6 or 7, wherein a fiber having an initial tensile modulus of 100 g / d or more is twisted. 9. A tape in which one or a plurality of fiber cords are buried in a rubber matrix in parallel with each other at both ends in the belt width direction at an angle of 10 ° to 35 ° with respect to the tire circumferential direction on the outer periphery of the carcass layer. The pneumatic radial tire according to any one of claims 6 to 8, wherein the belt is continuously wound while being bent or folded at a portion to form a substantially two-layered belt layer. 10. The pneumatic radial tire according to claim 9, wherein a belt cover layer having an organic fiber cord disposed substantially parallel to a tire circumferential direction is provided on a tread side of the belt layer.