JPH03260130A - Pneumatic radial tire having high maneuverability - Google Patents

Abstract

PURPOSE:To obtain the subject tire having excellent adhesivity to rubber, heat- resistance, fatigue resistance, etc., suppressed bulging tendency in high-speed running and good high-speed durability by using a filament having a specific structure in a cord layer and reinforcing a belt layer with the cord layer. CONSTITUTION:A cord member is produced by twisting filaments having sheath- core conjugate structure consisting of a sheath part composed of a mixture of a polyamide and 1-30 pts.wt. of a polyester and a core part composed of a polyester, wherein the ratio of the core part in the filament is 30-90wt.%. Cords (e.g. aromatic polyamide fiber cord having a tenacity of >=10 g/d) of the belt layers 2, 3 are arranged on the outside of a carcass layer 4 reinforced with a rayon fiber cord. The direction of the cord is inclined by 10-40 deg. relative to the circumferential direction of the tire. The cord layer 5 of the above cord member is arranged to the end parts of the belt layers 2, 3 to obtain the objective tire.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a pneumatic radial tire with improved belt layer durability, and more specifically, a pneumatic radial tire with improved adhesiveness to rubber and with improved heat resistance and resistance in the rubber. This invention relates to a high-motion performance pneumatic radial tire that is reinforced with high-strength tire-reinforcing fibers that have excellent properties such as fatigue resistance, dramatically suppresses the amount of protrusion at high speeds, and has improved high-speed durability.

(Prior Art and Problems to be Solved by the Invention) Polyester fibers, typified by polyethylene terephthalate fibers, have the characteristics of high strength and high elastic modulus, and are therefore considered useful as tire reinforcing materials.

However, polyester fibers generally have poor heat resistance in rubber, and at high temperatures, the ester bonds in polyester fibers are severed by the action of moisture and amine compounds in the rubber, causing a decrease in strength and resistance to rubber. Adhesive properties are also poor, especially when repeatedly exposed to a high temperature atmosphere for a long period of time, resulting in a decrease in adhesive strength with rubber.

In response to this, many attempts have been proposed to improve the adhesiveness, which is a drawback of polyester, and one known method is to coat the surface of a rubber reinforcing material made of polyester fibers with polyamide. . for example,
JP-A No. 49-85315 discloses a method for manufacturing composite fibers having polyester fibers as a core and nylon-6 as a sheath, and describes rubber reinforcing fibers in which the degree of polymerization of each component polymer and the ratio of the core polymer are specified. It is described that it is used as a tire reinforcing material.

Similarly, Japanese Patent Publication No. 62-42061 discloses a fiber having a core-sheath type composite structure in which the core is made of polyester and the sheath is made of polyamide, and the polyamide-sheath component is 70 to 30% by weight.
It is also described that a rubber reinforcing material fiber whose surface is adhered with an epoxy adhesive is used as a tire reinforcing material.

In JP-A-1-97211, polyester is used for the core and 66/6T copolyamide is used for the sheath.
If the copolymerization ratio of hexamethylene diammonium terephthalate in the copolyamide is 5% by weight or more, preferably 10 to 40% by weight, the core polyester and the sheath 66
/6T copolyamide is improved, so
It is described that this is used as a tire reinforcing material.

In JP-A-1-97212, the core polyester and the sheath hexamethylene diammonium terephthalate polyamide are made into a highly oriented, highly crystalline fiber structure to improve the adhesion at the interface, and by using this fiber, the tire It is stated that the performance can be improved.

Special Publication No. Sho 49-85315, Special Publication No. Sho 62-4206
Publication No. 1 states that the use of polyamide in the sheath improves the adhesion with rubber, which is a disadvantage of polyester fibers, and also has the effect of suppressing amine decomposition. In JP-A-1-97211 and JP-A-1-97212, the boundary adhesion between the polyester core and the polyamide sheath is improved, but a sufficient improvement effect is not recognized.

Therefore, when fibers with a conventional composite structure are used as reinforcing materials in pneumatic tires, the core-sheath polymer interface is destroyed due to repeated elongation and compression fatigue during tire running.
Next, since the sheath part is separated and destroyed, the original performance of the core-sheath composite fiber is not exhibited.

The object of the present invention is to use high-strength composite fibers that have excellent adhesion to rubber, Young's modulus, dimensional stability, heat resistance in rubber, and fatigue resistance, and are suitable as rubber reinforcing materials. The purpose is to provide a pneumatic radial tire by using it in the camp layer or carcass layer, and in particular improves the bonding force at the filament interface of the core-sheath composite structure and has sufficient durability against interfacial peeling between the core-sheath polymers. This is a high-performance pneumatic pump that is reinforced with rubber-reinforcing composite fibers that fully exhibit the characteristics of composite fibers over a long period of time.The amount of protrusion at high speeds is dramatically suppressed and high-speed durability is improved. Our goal is to provide radial tires.

(Means for Solving the Problems) As a result of intensive research to solve the above problems, the present inventors discovered that the cords were arranged parallel to the circumferential direction between the belt layer and the trend layer. It has been confirmed that the above problem can be solved by further reinforcing at least the end portion of the belt layer with one or more cord layers, and by using a cord member of the cord layer having a core-sheath composite structure made of a specific component, and the present invention has been made. The invention was completed.

That is, the present invention provides at least one carcass layer reinforced with rayon fiber cords, a trend layer covering the outside of this carcass layer, and an inner crown portion of the tread outside the carcass layer having a diameter of 10 mm in the tire circumferential direction. ~40°,
Preferably, the belt layer comprises an aromatic polyamide fiber cord having a tenacity of 10 g/d or more, a steel cord, and/or a polyvinyl alcohol having a tenacity of 15 g/d or more. In a pneumatic radial tire reinforced with fiber cords, at least the ends of the belt layer are further reinforced by one or more cord layers arranged in parallel, and the sheath portion is mainly made of polyamide as a cord member of the cord layers. 1 polyester component
~30% by weight mixture, which has a core-sheath composite structure in which the core is made of polyester, and the ratio of the core component to the core component and the sheath component is 30 to 90% by weight. The present invention relates to a high maneuverability pneumatic radial tire characterized by being applied by twisting them together as filaments.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 is a partially cutaway perspective view of the right half showing the structure of a pneumatic radial tire according to a first preferred embodiment of the present invention, in which 1 is a tread rubber layer, 2 and 3 are belt layers, 4 is a carcass, and 5 is a The code layer is shown. In the illustrated tire, the belt layer has a cord arrangement of 10 to 40 degrees, preferably 2 degrees to the tire circumferential direction.
It has two belt layers intersecting at an angle of 0 to 35 degrees, and has one coat layer 5 between the belt layer 2 near the road surface and the trend layer 1. The convergence is made larger than that of belt cords N2 and N3, and the full cap layer covers the entirety of belt cords N2 and N3. The number of belt layers and cord layers is not limited to this preferred example;
It goes without saying that the number can be increased further if necessary, and the width of the code layer can also be changed as necessary.

FIG. 2 shows a tire of a second preferred example. In the illustrated tire, the cord layer 5 is a separate piece obtained by removing the center part of the cord layer of the tire shown in FIG.
as a cap layer covering each end of the wafer. The width and number of the cord layers can be changed as necessary, and the cord layer can also be used in combination with the tire cord layer shown in FIG. 1.

In the present invention, the core component of the composite fiber having a core-sheath composite structure used for reinforcing the cord layer is made of polyester, while the sheath component is mainly composed of polyamide and contains 1 to 30% by weight of polyester. The blending of polyester is effective in improving the adhesion at the interface with the polyester core component. Preferably, it is mixed in an amount of 5 to 30% by weight. If the amount exceeds 30% by weight, the polyamide fiber properties expected of the sheath component, especially the adhesive properties with rubber, will not be exhibited, resulting in a decrease in high-speed durability. On the other hand, if the polyester content is less than 5% by weight, the adhesion at the composite interface between the core component and the sheath component may not be sufficiently improved, which poses a problem in terms of durability.

The core component of the composite fiber according to the present invention is substantially a polyester containing ethylene terephthalate units as a main component. The copolymer component may be contained to an extent that does not substantially reduce the physical and chemical properties of the polyethylene terephthalate polymer, for example less than 10%. The copolymer component may include dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, and diphenyldicarboxylic acid, diol components such as propylene glycol and butylene glycol, and ethylene oxide.

In order to obtain a strength of 7.5 g/d or more for the composite fiber according to the present invention, the core component polyethylene terephthalate fiber has an intrinsic viscosity ([μm)] of 0.8 or more, preferably 0.8 g/d or more.
It has a high viscosity of 9 or more. In addition, in order to obtain excellent heat resistance in rubber of this composite fiber, the concentration of carboxyl terminal groups of polyester, which is the main component of the core, is 20ep/10bg.
It is preferable that it is below.

Next, the polyamide used as the sheath component is polycapramide,
Consists of ordinary polyamides such as polyhexamethylene adipamide, polytetramethylene adipamide, polyhexamethylene dodecamide, polyhexamethylene dodecamide, etc. Blends or partially copolymerized polymers of these polymers are also used. However, polyhexamethylene adipamide is particularly preferred. The polyamide sheath component polymer also needs to have a high degree of polymerization in order to obtain the composite fiber according to the present invention, and has a relative viscosity of sulfuric acid (ηr) of 2.8 or more, preferably 3.
．． It is 0 or more.

The polyester polymer used as part of the sheath component is preferably the same as the polymer used as the core component described above, but does not necessarily have to be the same.

The proportion of the core component of the composite fiber according to the present invention is 30 to 90% by weight. If the core component is less than 30% by weight, it is difficult to maintain the desired modulus and dimensional stability as a composite fiber at the level of polyester. On the other hand, if the polyester core component exceeds 90% by weight, improvements in adhesion between the composite fiber and rubber, heat resistance in rubber, etc. cannot be sufficiently achieved, and the effects of the present invention are insufficient.

Further, the composite fiber according to the present invention is characterized in that both the polyester core component and the sheath component consisting of a polyamide and polyester mixed polymer are highly oriented and crystallized. That is, the birefringence (Δn) of the polyester core component is 160
Xl0-' ~ 190 Xl0-''.160
If it is less than Xl0-', the strength (T/D) of the composite fiber is 7.5.
g/d or more, the initial tensile resistance (Mi) is 60 g/d
It cannot be greater than d. On the other hand, 190 Xl0-”
If it exceeds , dimensional stability and fatigue resistance will not be improved.

On the other hand, the birefringence (Δn) of the polyamide component, which is the main component constituting the sheath, is 50 x 10-'' or more, usually 55 x 10-
3 or more, indicating high orientation. If the birefringence is less than 50 x 10-'', a composite fiber with high strength and high initial tensile resistance cannot be obtained.

The birefringence of the core-sheath composite fiber can be measured as follows. That is, the sheath was measured as it was using a transmission interference microscope, and the core was sampled by dissolving the polyamide component, which is the main component of the sheath, in formic acid, sulfuric acid, fluorinated alcohol, etc. Measure using a transmission interference microscope or the standard Berek compensator method.

Although the composite fiber according to the present invention contains a considerable amount of a polyamide component, it is characterized in that the presence of the polyamide component is not felt in terms of creep properties. The above creep behavior cannot be explained simply by combining the respective characteristics of conventional polyester fibers and polyamide fibers, but can be said to be a unique effect developed by combining the polymers of both components.

The composite fiber according to the present invention characterized by the above fiber structure has a high strength of 7.5 g/d or more, an initial tensile resistance of 60 g/d or more, and a dry heat shrinkage rate (ΔSIS) measured at 150°C. ) exhibits fiber properties of 7% or less.

More preferable composite fiber properties include strength of 8 g/d or more, initial tensile resistance of 70 g/d or more, and dry heat shrinkage rate (Δ515
) is less than 5%, which is achieved by a suitable combination of the fiber structure properties mentioned above.

The composite fiber according to the present invention having the above characteristics can be produced by the method shown below.

In order to obtain the polyester fiber physical properties of the core, a polymer consisting essentially of polyethylene terephthalate and having an ultimate viscosity ([η]) of 068 or higher, usually 0685 or higher is used. Furthermore, in order to obtain fibers with excellent heat resistance, it is preferable to spin a polymer having a low concentration of carboxyl terminal groups.

The polyamide polymer used as the main component of the sheath is a high polymerization degree polymer with a sulfuric acid relative viscosity of 2.8 or higher, usually 3.0 or higher.

(Example) Next, the present invention will be further specified and explained in detail using Examples and Comparative Examples.

In order to obtain a double-structured filament having a core-sheath composite structure, two extruder-type spinning machines were used for melt spinning the polymer. Polyethylene terephthalate (PUT) for the core component melted in one extruder
and nylon-6,6 (66Ny) mixed polymer, and nylon-6 for the sheath component melted in the other extruder.
, 6 are respectively guided into composite spinning packs, and
Using spinning equipment similar to the spinning equipment described in Japanese Patent No. 18369, a core-sheath type filament of 1,500 denier toqueluanil was prepared with a core of PET and a sheath of 66Ny + PET at a core/sheath weight ratio of 50,150. in this case,
The weight ratio of 66Ny + PET to PET was controlled by adjusting the diameter of the spinneret hole and the amount of polymer discharged.

Next, the 1500 tenier filaments are twisted together to form a 1500 d/2 (40 x 40 times/10
c:m) code. The cord thus produced was used as a coat for the cord layer of a 195/70R14 size radial tire.

As shown in FIG. 2, this tire has a reinforcing structure with belt layers 2 and 3 on a carcass layer 4, and a cord layer 5 as a camp layer layer thereon.

The number of embedded cords in the cord layer is 50 cords/5 cm, and the cords in the belt layer are steel cords (IX
5 Xo, 231W+) was used. In addition, the carcass layer (
The ply layer) is made of polyethylene terephthalate (PET
) One-layer structure of cord (1500d/3.30 x 30).

A tire reinforced with the cord layer 5 as a camp layer layer or a full camp layer (Fig. 1) as described above was trial-produced using each of the cord layers having the six types of prototype filaments shown in Table 1 below. The characteristics of the components and various tire performances of the tires were evaluated. The results obtained are shown in Table 1.

In addition, the percentage of the core to the total including the core and sheath is:
Determine the area ratio from the cross-sectional micrograph of the filament sample,
It was calculated from this and the density.

The polyamide percentage in the core was calculated from the previously determined percentage of the core component by treating the filament sample with formic acid, dissolving and removing the polyamide component, and measuring the polyester component (core ten sheaths).

Furthermore, the intrinsic viscosity of PET is orthochloroenol (2
5°C).

As is clear from the test results in Table 1, when the composite fiber according to the present invention is applied to the cord layer as a cap layer layer or a full cap layer, the protrusion at high speed is lower than that of the conventional composite fiber cord (comparative example). Compared to 1), it was sufficiently suppressed and the high-speed durability was greatly improved.

In the above example, two carcass layers reinforced with rayon fiber cords are used, but even if the carcass layers are reinforced with the composite fiber according to the present invention, high-speed durability can be dramatically improved. W! It has been certified.

(Effects of the Invention) As explained above, in the high motion performance pneumatic radial tire of the present invention, between the heald layer and the trend layer, one or more layers of cords are arranged parallel to the circumferential direction. By further reinforcing at least the end of the heald layer with the layer, and by using a cord member of the cord layer having a core-sheath composite structure made of a specific component, the amount of protrusion at high speeds can be dramatically suppressed. The effect is that high-speed durability is improved.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of the right half showing the structure of a pneumatic radial tire as an example of the present invention, and FIG. 2 is a part of the right half showing the structure of a pneumatic radial tire as another example of the present invention. FIG. 1...Tread rubber layer 2...Belt layer 3...
Heald layer 4... Carcass layer 5... Cord layer

Claims (1)

[Claims] 1. At least one carcass layer reinforced with rayon fiber cord, a tread layer covering the outside of this carcass layer, and a tread layer extending in the tire circumferential direction on the inner crown part of the tread outside the carcass layer. It is equipped with a belt layer in which cords are arranged at an angle of 10 to 40 degrees, and the belt layer has a strength of 10 g.
In a pneumatic radial tire reinforced with an aromatic polyamide fiber cord having a strength of 15 g/d or more, a steel cord, and/or a polyvinyl alcohol fiber cord having a tenacity of 15 g/d or more, at least the belt layer is formed by one or more cord layers arranged in parallel. The cord member of the cord layer is further reinforced at the end, and the sheath is made of a mixture mainly composed of polyamide and 1 to 30% by weight of a polyester component;
A core-sheath composite structure in which the core is made of polyester, and the ratio of the core component to the core component and the sheath component is 30 to 9.
A high motion performance pneumatic radial tire characterized by applying filaments composed of 0% by weight twisted together as filaments.