JP4890035B2 - Pneumatic tire - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a tire reinforcing material and a pneumatic tire. More specifically, the present invention relates to a tire reinforcing material that is used to improve the durability of a belt layer of a tire and is formed by bonding a fiber cord or the like. And a pneumatic tire using the same.

In recent years, in passenger car tires, demands for performance such as high-speed durability, steering stability, and road noise are increasing. Currently, at least two angled steel belts are mainly used for the belt layer of the radial tire for passenger cars. In order to ensure safety during running, especially at high speeds, cap layers are generally employed to prevent belt layer peeling (especially peeling that occurs at the edge of the belt layer) and improve durability. (For example, refer to Patent Document 1).
For example, it has been proposed to reinforce the rigidity in the belt circumferential direction by sandwiching all or both ends of the cross belt with a cap layer disposed in the circumferential direction. It has also been proposed to wind the cap layer in a spiral shape in order to eliminate the joint on the tire circumference.

  The cap layer is formed from a tire reinforcing material obtained by rubberizing a fiber cord. Nylon fiber, aramid fiber, polyester fiber, or the like is used as the cord. For example, use of cords such as aramid fibers and polyester fibers has been proposed in order to improve performances such as high-speed durability, steering stability, and road noise properties in passenger car tires (see, for example, Patent Documents 2 and 3).

By the way, nylon cords are inexpensive and frequently used as the most common cords for such cap layers. Nylon fibers can be suitably used for the cord of the cap layer in terms of adhesion to rubber, elongation characteristics, heat shrinkability, and the like. However, when a cap layer made of a nylon cord is arranged in a spiral shape in the tire circumferential direction in current passenger car tires, air permeation in the cord is easier than in other fibers such as polyester. Therefore, when a plurality of cuts are provided on the tread surface of the tire tread due to running on a rough road, an air leakage phenomenon is caused by the installation of the cap layer in a portion between the cut portions. In particular, air leakage occurs remarkably in those using an inexpensive one-ply nylon cord frequently used for tire sizes having versatility and low cost represented by speed ranges such as S and T (tire speed range symbols). For this reason, a pneumatic radial tire is demanded that uses a nylon cord that is inexpensive and frequently used and does not cause air leakage as a tire reinforcing material.
JP-A-6-24208 Japanese Patent Laid-Open No. 2-147407 Japanese Patent Laid-Open No. 1-145203

In order to solve the above-described problems, the present invention provides a pneumatic tire using a tire reinforcing material that is versatile and inexpensive and does not cause air leakage.

The inventor applies an adhesive to nylon fibers, dries, heat fixes, further normalizes, and maintains the cord tension at a predetermined value during the heat fixing and normalizing treatments. It has been found that when the tension ratio is limited to a certain range, a tire reinforcing material composed of a general-purpose bonded stretch-treated nylon cord that does not cause air leakage of 100 sec / 10 mmHg or more can be obtained. Has been reached.
That is, the pneumatic radial tire using the tire auxiliary material of the present invention is characterized by the following configuration or structure.

(1) A tire reinforcing material comprising a nylon cord formed by bonding nylon fibers with an adhesive and having an air permeability of 100 seconds / 10 mmHg or more is continuously spirally wound in the circumferential direction of the tire. Pneumatic tire characterized by being used for cap layer.
(2) The pneumatic tire according to (1), wherein the nylon cord is a single twist.
(3) The pneumatic tire according to (1), wherein the nylon cord has a weaving degree of 800 to 2200 dtex and a twist coefficient R expressed by the following formula 1 is 0.1 to 0.3 .
R = N × {0.139 × D × (0.9 / ρ)} ^1/2 × 10 ⁻³ (Expression 1)
In the above formula, N represents the number of twisted cords (times / 10 cm). D represents the total number of display decitex in the cord, and ρ represents the specific gravity of the yarn constituting the cord.

  The tire reinforcing material of the present invention uses a versatile nylon fiber, and when used for a pneumatic radial tire, its air permeability becomes 100 seconds / 10 mmHg or more, and the versatility in the pneumatic radial tire and It can be applied as an inexpensive cap layer.

Hereinafter, embodiments of a tire auxiliary material and a pneumatic tire according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram relating to sample preparation in an air permeability test. FIG. 2 is an explanatory diagram regarding sample preparation in the air permeability test. FIG. 3 is an explanatory diagram relating to sample preparation in the air permeability test. FIG. 4 is an explanatory diagram relating to sample preparation in the air permeability test. FIG. 5 is an explanatory diagram regarding sample preparation in the air permeability test.

The tire reinforcing material of the present invention is a nylon cord formed by bonding nylon fibers with an adhesive, and has an air permeability of 100 seconds / 10 mmHg or more.
The air permeability of the tire reinforcing material needs to be 100 seconds / 10 mmHg or more, particularly preferably 200 to 500 seconds / 10 mmHg. If the air permeability is less than 100 seconds / 10 mmHg, an air leakage phenomenon due to the installation of the cap layer between the cut portions of the tire tread surface easily occurs. In particular, those using a single twisted nylon cord have a significantly worse air leakage. Therefore, the tire reinforcing material of the present invention satisfies the requirements of a pneumatic radial tire even if the nylon cord is a single twist.

  In the present invention, air permeability is a unit of seconds / 10 mmHg, which is a unit measured according to an air permeability test described in the examples described later. Specifically, using a Beck type air permeation measuring device, the amount of air that has permeated through the tire reinforcement is defined as the amount of mercury dropped from a height of 380 mm, and the time required for the mercury column to drop is measured. Can be calculated.

The tire reinforcement (cap layer) is made of an adhesive-treated nylon cord. The nylon cord may contain other fibers in part if necessary, but it is preferable that substantially 100% by mass is nylon fibers.
The nylon cord has a weaving degree D of 800-2200 dtex (decitex). Within such a weaving range, the air permeability of the tire reinforcing material is led to a favorable range, there is no poor air retention with the tread rubber at the time of tire manufacture, and there is no air leakage. The tire reinforcement can be made.

The nylon cord preferably has a twist coefficient R represented by the following formula 1 in the range of 0.1 to 0.3. More preferably, it is in the range of 0.2 to 0.3.
R = N × {0.139 × D × (0.9 / ρ)} ^1/2 × 10 ⁻³ (Expression 1)
Here, in Formula 1, N represents the number of twists of the cord (times / 10 cm). D represents the total number of display decitex in the cord, and ρ represents the specific gravity of the yarn constituting the cord.

  The twist coefficient R is highly correlated with the packing property of the nylon cord. When the twist factor R is less than 0.1, the packing property is low, and the adhesive is easily impregnated and the adhesive penetrates excessively into the cord. To do. When the twisting coefficient R exceeds 0.3, the packing property is strong, and the tire reinforcing member causes a poor air retention with the tread rubber at the time of manufacturing the tire.

Next, the manufacturing method of the tire reinforcing material of the present invention will be described. In the method for manufacturing a tire reinforcing material according to the present invention, when a nylon cord is obtained by applying an adhesive to nylon fibers and performing heat setting treatment and normalizing treatment, the tension (H) of the cord in the heat setting step And the cord tension (N) in the normalizing process is in the range of 0.55 to 1.30 g / dtex, and the ratio (H / N) of each cord tension is in the range of 0.9 to 1.2. It is characterized by that.
The bonding process of the nylon cord is performed by an adhesive application process and a heat treatment process including a heat setting process and a normalizing process. In addition, a heat stretching process is performed during the heat setting process and the normalizing process. Moreover, it is preferable to add a drying process after an application | coating process as needed.

There is no restriction | limiting in particular as an adhesive agent used in the said application | coating process, According to the objective, it can select suitably. The adhesive may be a two-component reactive adhesive or a one-component non-reactive adhesive.
When a two-component reactive adhesive is used, the periphery and the inside of the cord are covered or impregnated with a relatively hard adhesive layer, the entire cord is hardened, and the air permeability of the tire reinforcing material is generally lowered. On the other hand, when a one-pack type non-reactive adhesive is used, the periphery of the cord and the gap can be covered with an adhesive layer having an appropriate hardness.
In a two-component reactive adhesive, for example, after applying a first liquid containing an epoxy compound or a blocked isocyanate compound to a fiber, resorcin, formalin, various latexes, caustic soda, and at least one of ammonia water and A second liquid containing (hereinafter referred to as “RFL liquid”) is applied. In the case of a one-component reactive adhesive, a mixed solution of an RFL solution and a solution commonly called N3 generated from triallyl cyanurate, resorcin, formalin, and aqueous ammonia is applied to the fiber. a reaction product mainly composed of 2,6-bis (2 ′, 4′-dihydroxyphenylmethyl) -4-chlorophenol, which is produced from p-chlorophenol and formalin, resorcin, formalin, aqueous ammonia, A liquid obtained by mixing a liquid called PEXUL consisting of the above-mentioned RFL liquid is applied. Further, a solution obtained by mixing a polyphenol phenol sulfide disclosed in JP-A-60-72972, a condensate of resorcin and holymarin under an alkali and the RFL solution is applied. Specific examples include the coating method described in Example 1 of JP-A No. 63-12503.

  The coating method of the present invention is not particularly limited and may be appropriately selected depending on the purpose. For example, dip coating method, bar coating method, kneader coating method, curtain coating method, roller coating method, spin coating method Among them, the dip coating method is preferable among these. When the dip coating method is used, a coating solution such as a first solution or a second solution may be stored in a container such as various baths, and the fibers may be immersed in the coating solution.

In the production method of the present invention, a heat treatment step comprising heat setting treatment and normalizing treatment is performed. Each of these treatments can be performed according to a known method, and the heat setting treatment and the normalizing treatment are preferably carried out in this order, and if necessary, the drying treatment is preferably carried out at all stages of these treatments. Each of these treatments may be carried out continuously or batchwise, but is preferably carried out continuously in terms of production efficiency. The method for continuously performing each treatment is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a heating furnace for performing each treatment is disposed continuously, and the heating furnace A method of continuously passing the inside (zone) through a conveyor or the like.
As drying treatment conditions, the temperature is preferably about 160 to 170 ° C., and the time is preferably about 60 to 120 seconds. Moreover, as conditions of the heat setting process and the normalizing process, the temperature is preferably about 250 to 260 ° C., and the time is preferably about 60 to 120 seconds.

  The tension (H) of the cord in the heat setting treatment and the tension (N) of the cord in the normalizing treatment have a high correlation with the packing property of the cord. A range of 30 g / dtex is preferred. In particular, the range of 0.90 to 1.10 g / dtex is more preferable. When both tensions are less than 0.55 g / dtex, the packing effect is insufficient, air is easily transmitted, and air leakage occurs. On the other hand, if both tensions exceed 1.30 g / dtex, air permeation is difficult to occur, resulting in poor air retention between the reinforcing material and the tread rubber during tire manufacture.

  The ratio (H / N) between the tension (H) of the cord in the heat setting treatment and the tension (N) of the nylon cord in the normalizing treatment is highly correlated with the packing property of the cord, and the ratio (H / N) Is preferably 0.9 to 1.2. When the ratio (H / N) is less than 0.9, the packing property is low, the adhesive is easily impregnated, and the adhesive excessively penetrates into the inside of the cord. Air retention between the tread rubber and other parts may occur. When the ratio (H / N) exceeds 1.2, the tire has a strong packing and easily causes air leakage.

The pneumatic radial tire of the present invention uses a tire reinforcing material for a cap layer wound spirally continuously in the circumferential direction of the tire.
The pneumatic radial tire is usually disposed on the outer side in the tire radial direction of the belt layer disposed in the crown portion. It has a cap layer (belt reinforcement layer) that reinforces the belt layer. As long as the cap layer is formed of the tire reinforcing material of the present invention, other configurations are not particularly limited, and known ones can be employed.
The specific structure of the pneumatic tire of the present invention includes, for example, a pair of bead portions, a carcass connected in a toroidal shape to the bead portions, a belt layer for tightening a crown portion of the carcass, and the belt layer And a structure having a cap layer that reinforces a tread, and a tread, and other members appropriately selected as necessary. In the structure, the cap layer is formed by the tire reinforcing material of the present invention.

  The pneumatic tire according to the present invention is a radial tire, and the belt layer is covered with the cap layer as a whole, and / or the vicinity of both ends is spirally wound and covered. Embodiments are preferred. In each of the above embodiments, it is preferable that the tire reinforcing material is arranged in an endless manner so that the arrangement direction of the tire reinforcing material in the cap layer is substantially parallel to the tire circumferential direction. In this case, there is no joint on the tire circumference, the uniformity is good, and the absence of the joint is advantageous in that generation of separation due to strain concentration on the joint portion can be suppressed.

  In the pneumatic tire of the present invention, the cap layer formed of the tire reinforcing material of the present invention is wound in a spiral shape at positions close to the entire belt layer and / or side portions at both ends of the belt layer. If so, the tension rigidity in the circumferential direction of the crown portion is increased, and the so-called tagging effect of the belt layer is enhanced. For this reason, it is difficult for the tread surface to pick up vibrations of large and small irregularities on the road surface while the tire is traveling, and vibrations transmitted to the tire side part-rim part-wheel and transmitted to the inside of the vehicle are reduced as a whole, and road noise is reduced. In addition, the use of an inexpensive one-ply nylon cord makes it possible to reduce the cost of pneumatic tires.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Examples 1 and 2 and Comparative Examples 1 to 3)
Each pneumatic tire (radial tire) in each of Examples 1 and 2 and Comparative Examples 1 to 3 is a carcass that is folded and locked around the bead core from the inside to the outside of the tire, and a tread that is positioned at the crown of the carcass. Part, a side wall part of the carcass, two belt layers arranged inside the tread part, and cap layers at both ends of the belt layer on the outer peripheral side of the belt layer.
The pneumatic radial tire used in each example and comparative example has a tubeless structure of 205 / 65R15, and is manufactured at a vulcanization condition of 170 ° C. × 13 minutes, a post-cure inflation condition of an internal pressure of 2.5 kg / cm ² , and 26 minutes. I went there. As a carcass in a pneumatic radial tire, a polyethylene terephthalate cord having a twist number of 1100 dtex / 2 (twist of 1100 dtex) (primary twist x upper twist) 47 x 47 (times / 10 cm) is rubberized to form a sheet. Two things (the number of implants is 55.0 / 5cm) were used. The carcass is arranged in a direction substantially perpendicular to the tire circumferential direction, and is composed of a single layer.
The belt layer in the pneumatic radial tire is a sheet of rubber cord with a steel cord having a structure of 1 × 5 × 0.23 (the driving angle is 26 ° on the left and right with respect to the circumferential direction, the number of driving is 40.0) 2 pieces / 5 cm). In the belt layer, non-extensible cords represented by steel cords are arranged at an inclination angle of 10 ° to 30 ° with respect to the tire circumferential direction (or the equator plane of the tire), and the two cords have different directions. It is piled up so as to intersect.

The details of the cap layer are as shown in Table 1. The fibers shown in Table 1 are made of tire reinforcement by applying an adhesive treatment to the fibers shown in Table 1, and the cord is rubberized to form a sheet. It has become. The tire reinforcing material is wound endlessly in a spiral shape (spiral shape) so as to be substantially parallel (0 ° to 5 °) in the tire circumferential direction.
The cap layer was helically wound around the outer side of the belt layer at 0 to 5 ° with respect to the circumferential direction. The cap layer is formed by wrapping the strip so that it is 5 mm wide from both ends of the belt layer over the entire belt layer, and further, the strip is attached to both ends on the outer peripheral side of the belt layer. Each layer is composed of a layer layer formed by winding each layer to have a width of 30 mm. This strip was about 5-20 mm narrow.

The tire reinforcing material used for the cap layer was prepared by adjusting a nylon yarn so that the twist coefficient R was 0.1 to 0.3, thereby obtaining a twisted cord. The twisted cord was subjected to coating, drying, heat setting, and normalizing treatment steps under the following conditions to obtain a tire reinforcing material.
In the coating treatment, the cord was immersed in a liquid containing the one-liquid non-reactive adhesive in Example 1 of JP-A No. 63-12503 as an adhesive. The drying process is performed at 170 ° C. for 85 seconds, the heat setting process and the normalizing process are performed at 250 to 260 ° C. for 85 seconds, the tension in the heat setting process and the normalizing process is 0.55 to 1.30 g / dtex, and the heat setting process. The ratio (H / N) of the tension (H) in the film and the tension (N) in the normalizing process was set to 0.9 to 1.2.

The following air permeability tests were conducted on the tire reinforcing materials used for the belt reinforcing layers in the pneumatic tires (radial tires) in the examples and comparative examples, and the air permeability was evaluated.
<Air permeability test>
The tire reinforcing material used for the cap layer was buried in rubber and then vulcanized, and the time during which a certain amount of air permeated through the tire reinforcing material was measured. The equipment and materials used for this measurement are as follows.
(1) Beck type air permeation measuring machine The amount of air that permeated through the sample of the tire reinforcing material was defined as the amount of mercury dropped from a height of 380 mm, and the time required for the mercury column to drop was measured. The mercury-filled can in the Beck type air permeation measuring device is made of glass, has an inner diameter of 3.0 mm, and a length of 400 mm or more. The measurement accuracy of the Beck type air permeation measuring machine is 0.1 second.

(2) Material Two types of rubber sheet 1 and rubber sheet 2 were produced. The rubber sheet 1 has a thickness of 1.7 ± 0.1 mm, and the rubber sheet 2 has a thickness of 0.5 ± 0.1 mm.
(3) Sample preparation As shown in FIG. 1, ten cords of the tire reinforcing material are loaded on the sample preparation plate with a tension {about 10 N} that does not sag, and the ten cords of the tire reinforcing material are loaded. Were coated with the rubber sheet 2 and cut into the specified dimensions of 38 × 25 mm (length × width): (10 cords, 1 sheet), and this was used as a test piece.
Here, the rubber sheet 1 was cut into the dimensions shown in Table 2, and the number of sheets shown in Table 2 was prepared.

That is, two rubber members A having a thickness of 3.4 mm were produced by laminating two cut rubber sheets obtained by cutting the rubber sheet 1 into a predetermined size. Further, three rubber sheets obtained by cutting the rubber sheet 1 into a predetermined size were laminated to produce one rubber member B having a thickness of 5.1 mm. Further, three rubber sheets C obtained by cutting the rubber sheet 1 into a predetermined size were laminated to produce one rubber member C having a thickness of 5.1 mm. Further, the rubber member C was cut into the shape shown in FIG.

A test piece and rubber members A to C prepared in advance in a vulcanization mold were filled as shown in FIG. 3 (10 cords are arranged in one row). Next, this was vulcanized with a vulcanization press. The vulcanization mold was preheated at 160 ° C. for 10 minutes or more. As conditions for the vulcanization, the temperature is 160 ± 1 ° C., the time is 20 ± 0.1 minutes, and the pressure is 0.98 to 2.45 Mpa (mold surface pressure represented by the following formula 2). Met.
Mold surface pressure = {(cylinder radius) ² × π × cylinder pressure} ÷ mold area (21.6 × 21.6) Equation 2
After vulcanization, the test piece was quickly taken out from the vulcanization mold and allowed to cool for 4 hours or more. The rubber protruding from the test piece was removed, both ends (shaded portions) were cut off as shown in FIG. 4, and it was confirmed that all the cords were exposed on the cut surface. Then, a raw rubber sheet (the rubber sheet 1) having a thickness of 0.5 mm was used as a sealing material, which was attached to the test piece as shown in FIG. 5 and used as a sample.

(4) Test The part (12 mm protrusion) which protruded from the said sample was inserted in the sample holder lower part of the said Beck type air permeation | transmission measuring machine, and the upper holder was inserted in the other. Next, the pressure lever was lowered and lightly squeezed to take a horizontal level. Mercury was pulled up to a height of 380 mm, and the number of seconds required for the mercury column to descend to a height of 370 mm was measured. As measurement conditions, the initial mercury column height was 380 mm, and the measurement length was 10 mm (capacity: 70.68 mm). And about the measured number of seconds, the average value of four measured values was taken, the first decimal place was rounded off and rounded to the number of seconds of the positive number, and the number of seconds of the number of the positive number was shown in Table 3.

<Air permeability in tires>
(1) Prepare tires having cap layers of the examples and comparative examples. A hole reaching the layer from the inner liner side of the tire (a in FIG. 6) is opened using a drill (wood screw: φ5 mm). However, the hole stays through the layer and does not penetrate.
(2) The layer is cut from the position where the inner hole is formed to a position 3 cm in the tire circumferential length direction using a cutter from the tread side (b in FIG. 6). In addition, you may cut | disconnect the position until a blade edge | tip reaches | attains a steel belt.
(3) Cover the tread position cut in the above (2) with a funnel having a diameter of 40 mm upside down, and fill the periphery with clay so that the air leaking from the cut portion is collected at the mouth of the funnel.
(4) Connect an air flow meter to the funnel port and measure the amount of air leaking.
In the piercing process (1), it is assumed that the layer code is cut into two. If three cords are cut, the value of flow rate x 2/3 is applied for conversion in the evaluation. )

  From the results shown in Table 3, the pneumatic tire of the present invention using the tire reinforcing material of the present invention for the belt reinforcing layer has very little air leakage in the tire. In Comparative Examples 1 to 3, air leakage is likely to occur. The tire reinforcing material and the pneumatic radial tire of the present invention are not limited to the above-described examples and embodiments, and various modifications can be made without departing from the scope of the present invention. It is.

The tire reinforcing material used in the present invention is versatile and inexpensive, and when used in the pneumatic tire of the present invention, has high industrial applicability without causing air leakage.

FIG. 1 is an explanatory diagram relating to sample preparation in an air permeability test. FIG. 2 is an explanatory diagram regarding sample preparation in the air permeability test. FIG. 3 is an explanatory diagram relating to sample preparation in the air permeability test. FIG. 4 is an explanatory diagram relating to sample preparation in the air permeability test. FIG. 5 is an explanatory diagram regarding sample preparation in the air permeability test. FIG. 6 is an explanatory diagram for measuring air permeability in a tire.

Claims (3)

A cap layer consisting of a nylon cord made by bonding nylon fibers with an adhesive, and a tire reinforcing material with air permeability of 100 seconds / 10 mmHg or more that is continuously spirally wound in the circumferential direction of the tire Pneumatic tire characterized by being used for The pneumatic tire according to claim 1, wherein the nylon cord is a single twist. The pneumatic tire according to claim 1, wherein the nylon cord has a weaving degree of 800 to 2200 dtex, and a twist coefficient R represented by the following formula 1 is 0.1 to 0.3.
R = N × {0.139 × D × (0.9 / ρ)} ^1/2 × 10 ⁻³ (Expression 1)
In the above formula, N represents the number of twisted cords (times / 10 cm). D represents the total number of display decitex in the cord, and ρ represents the specific gravity of the yarn constituting the cord.

Images