JP2006192914A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire allowing improving of a reduction effect of road noise without deteriorating uniformity and high speed durability. <P>SOLUTION: In this tire, a belt reinforcing layer 7 is arranged on an outer peripheral side of a belt layer 6. The belt reinforcing layer 7 is divided into a center part 7a and both end parts 7b in the tire width direction. As the reinforcing cord at the center part 7a of the belt reinforcing layer 7, a polyester fiber cord satisfying a formula (1): 0.5≤light absorbance ratio (1,510 cm<SP>-1</SP>absorption/2,920 cm<SP>-1</SP>absorption)≤6.0 or a formula (2): 2.0≤light absorbance ratio (1,510 cm<SP>-1</SP>absorption/700 cm<SP>-1</SP>absorption)≤25.0 and having resin coating weight of 3 to 15 wt% and Gurley cord stiffness of 6,000 to 20,000 mg is used. As the reinforcing cords at both the end parts 7b of the belt reinforcing layer 7, polyethylenenaphthalate fiber cords having lower Gurley cord stiffness than that of the polyester fiber cord are used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic radial tire using a polyester fiber cord excellent in heat-resistant adhesion as a belt reinforcement layer. More specifically, the present invention improves road noise reduction effect without deteriorating uniformity and high-speed durability. The present invention relates to a pneumatic radial tire.

  In pneumatic radial tires, for the purpose of improving high-speed durability, rolling resistance and road noise, it is possible to arrange a belt reinforcement layer formed by arranging reinforcement cords to extend in the tire circumferential direction on the outer circumference side of the belt layer Has been done. Nylon fiber cords and polyester fiber cords are generally used as the reinforcement cords for such belt reinforcement layers (see, for example, Patent Documents 1 to 3). However, in recent years, the demand for improvement in road noise has been increasing, and when the conventional nylon fiber cord or polyester fiber cord is used, the required characteristics cannot always be satisfied.

On the other hand, as a rubber reinforcing material, a polyester fiber cord having improved heat-resistant adhesiveness by a specific dip treatment has been proposed (see, for example, Patent Document 4). However, such a polyester fiber cord has good adhesion to rubber, but the cord hardness becomes higher than necessary, so that it is difficult to apply it as it is to the belt reinforcing layer. In other words, if the reinforcing cord used for the belt reinforcing layer does not have a certain degree of flexibility, the belt reinforcing layer in the green tire will undulate in the radial direction of the tire, and the uniformity of the pneumatic radial tire will deteriorate. .
Japanese Patent Laid-Open No. 11-208212 JP 2002-79806 A JP 2002-29214 A JP 2000-212875 A

  The object of the present invention is to provide an air that can improve the reduction effect of road noise without deteriorating uniformity and high-speed durability when using a polyester fiber cord excellent in heat-resistant adhesion for a belt reinforcing layer. The purpose is to provide a radial tire.

In order to achieve the above object, the pneumatic radial tire of the present invention has at least one belt layer disposed on the outer peripheral side of the carcass layer in the tread portion, and a reinforcing cord is extended in the tire circumferential direction on the outer peripheral side of the belt layer. In a pneumatic radial tire having a belt reinforcing layer arranged so as to
The belt reinforcing layer is divided into a center portion and both end portions in the tire width direction, and the absorbance ratio of the infrared absorption spectrum satisfies the following formula (1) or (2) as a reinforcing cord at the center portion of the belt reinforcing layer. A polyester fiber cord having a resin adhesion amount of 3 to 15% by weight and a Gurley cord hardness of 6000 to 20000 mg is used as a reinforcement cord at both ends of the belt reinforcement layer. Also, a polyethylene naphthalate fiber cord having a low Gurley cord hardness is used.
Formula (1) 0.5 ≦ absorbance ratio (1510 cm ⁻¹ absorption / 2920 cm ⁻¹ absorption) ≦ 6.0
Equation (2) 2.0 ≦ absorbance ratio (1510 cm ^-1 absorption / 700 cm ^-1 absorption) ≦ 25.0

  In the present invention, the belt reinforcing layer is divided into a central portion and both end portions in the tire width direction, and a specific resin attached based on the absorbance ratio of the infrared absorption spectrum is used as a reinforcing cord in the central portion of the belt reinforcing layer. While using a polyester fiber cord having an amount of 3 to 15% by weight and a Gurley-type cord hardness of 6000 to 20000 mg and excellent in heat-resistant adhesiveness, A polyethylene naphthalate fiber cord which is an elastic material and has a lower Gurley cord hardness than the polyester fiber cord is used. In other words, the use of a polyester fiber cord with excellent heat-resistant adhesion at the center of the belt reinforcement layer ensures the effect of improving road noise and high-speed durability, and the polyethylene reinforcement has flexibility at both ends of the belt reinforcement layer. By using a phthalate fiber cord, it is possible to achieve both road noise and uniformity improvement effects.

  In the present invention, when both ends in the tire width direction of the belt layer located on the outermost side in the tire radial direction are used as the base points, both ends of the belt reinforcing layer have a width a (mm) protruding inward in the tire width direction from the base point The relationship with the width b (mm) protruding outward in the tire width direction from the base point is preferably 0 ≦ a ≦ 50, 0 ≦ b ≦ 20, and 20 ≦ a + b ≦ 70. Further, the Gurley cord hardness c (mg) of the polyester fiber cord used in the central portion of the belt reinforcing layer and the Gurley cord hardness d (mg) of the polyethylene naphthalate fiber cord used in both ends of the belt reinforcing layer. ) Is preferably c / d ≧ 2. Thereby, uniformity, high-speed durability, and the improvement effect of road noise can be expressed with sufficient balance.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a pneumatic radial tire according to an embodiment of the present invention. In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 is mounted between the pair of left and right bead portions 3 and 3, and an end portion of the carcass layer 4 is folded around the bead core 5 from the inside to the outside of the tire. The carcass layer 4 is composed of a plurality of reinforcing cords extending in the tire radial direction. On the outer peripheral side of the carcass layer 4 in the tread portion 1, two belt layers 6 are arranged over the entire circumference of the tire. These belt layers 6 include reinforcing cords that are inclined with respect to the tire circumferential direction, and are arranged such that the reinforcing cords cross each other between the layers. A steel cord is used as the reinforcing cord of the belt layer 6. On the outer peripheral side of the belt layer 6, a belt reinforcing layer 7 in which reinforcing cords are arranged so as to extend in the tire circumferential direction is disposed. The belt reinforcing layer 7 is formed by winding a reinforcing cord around the outer circumferential side of the belt layer 6 along the tire circumferential direction.

In the pneumatic radial tire, the belt reinforcing layer 7 is divided into a central portion 7a and both end portions 7b in the tire width direction. As the reinforcing cord of the central portion 7a of the belt reinforcing layer 7, the adhesion amount of the resin (dip resin) satisfying the following formula (1) or (2) in the absorbance ratio of the infrared absorption spectrum is 3 to 15% by weight. In addition, a polyester fiber cord excellent in heat-resistant adhesion having a Gurley-type cord hardness of 6000 to 20000 mg is used. In particular, it is preferable to use a polyethylene terephthalate fiber cord (PET) as the polyester fiber cord.
Formula (1) 0.5 ≦ absorbance ratio (1510 cm ⁻¹ absorption / 2920 cm ⁻¹ absorption) ≦ 6.0
Equation (2) 2.0 ≦ absorbance ratio (1510 cm ^-1 absorption / 700 cm ^-1 absorption) ≦ 25.0

  On the other hand, a polyethylene naphthalate fiber cord (PEN) having a lower Gurley cord hardness than the polyester fiber cord is used as the reinforcement cord of the both end portions 7b of the belt reinforcing layer 7. Here, the Gurley-type cord hardness is a bending hardness measured in accordance with JIS-1096.

  Thus, by using the polyester fiber cord excellent in heat-resistant adhesiveness at the central portion 7a of the belt reinforcing layer 7, it is possible to ensure the effect of improving road noise and high-speed durability. However, if a polyester fiber cord excellent in heat-resistant adhesiveness is applied to both end portions 7b of the belt reinforcing layer 7, the cord bending hardness is too high, so that both end portions 7b of the belt reinforcing layer 7 in the tire radial direction in the green tire. It will undulate and the uniformity will deteriorate. Therefore, a polyethylene naphthalate fiber cord having flexibility is used for both end portions 7b of the belt reinforcing layer 7 to achieve both road noise and uniformity improvement effects.

  When a polyethylene naphthalate fiber cord is applied to both the central portion 7a and both end portions 7b of the belt reinforcing layer 7, an effect of reducing road noise appears, but the raw material cost increases. Therefore, a polyethylene naphthalate fiber cord is applied only to both end portions 7b of the belt reinforcing layer 7 having high sensitivity to road noise and uniformity, and the central portion 7a has higher elasticity than the 66 nylon fiber cord used conventionally. Moreover, it is preferable to apply a heat-resistant polyethylene terephthalate fiber cord that is cheaper than the polyethylene naphthalate fiber cord.

  In the pneumatic radial tire, when both ends in the tire width direction of the belt layer 6 located on the outermost side in the tire radial direction are set as the base points X, both end portions 7b made of polyethylene naphthalate fiber cords of the belt reinforcing layer 7 are The relationship between the width a (mm) projecting inward in the tire width direction from the base point X and the width b (mm) projecting out in the tire width direction from the base point X is 0 ≦ a ≦ 50, 0 ≦ b ≦ 20, and 20 ≦ It is preferable that a + b ≦ 70. If the widths a and b do not satisfy the above relationship, the uniformity improvement effect is reduced.

  Further, the Gurley cord hardness c (mg) of the polyester fiber cord used for the central portion 7a of the belt reinforcing layer 7 and the Gurley cord hardness of the polyethylene naphthalate fiber cord used for both ends 7b of the belt reinforcing layer 7 are used. The relationship with the length d (mg) is preferably c / d ≧ 2. If the cord hardness c, d does not satisfy the above relationship, the effect of improving uniformity is reduced.

The dip resin of the polyester fiber cord excellent in heat-resistant adhesiveness is characterized by the above formulas (1) and (2). Here, the absorption at 1510 cm ^{−1 is} the absorption of polyurethane urea using aromatic isocyanate, and is the absorption in which the bending vibration of the N—H group of the urethane bond and urea bond overlaps with the absorption of the aromatic ring. Absorption at 2920 cm ⁻¹ is absorption of C—H stretching vibration, mainly absorption by styrene / butadiene copolymer. Absorption at 700 cm ⁻¹ is absorption of the C—H out-of-plane bending angle of monosubstituted benzene, and is absorption by polystyrene.

  That is, both formulas (1) and (2) are formulas representing the absorbance ratio of the absorption derived from isocyanate and the absorption derived from latex in the dip solution. If the absorbance ratio is smaller than the above range and there are few components derived from isocyanate, sufficient heat-resistant adhesiveness cannot be ensured. Conversely, if there are few components larger than the above range and derived from latex, the cord becomes hard and the strength decreases and fatigue resistance Cause a decline.

  The resin adhesion amount of the polyester fiber cord is required to be 3 to 15% by weight. The resin adhesion amount is a percentage of the resin weight with respect to the weight of the polyester fiber cord in a state where the resin is adhered. If the resin adhesion amount is less than 3% by weight, sufficient heat-resistant adhesiveness cannot be ensured, and if it is more than 15% by weight, the cord becomes hard, resulting in reduced strength and fatigue resistance.

  The polyester fiber cord needs to have a Gurley cord hardness of 6000 to 20000 mg. By setting the Gurley-type cord hardness of this polyester fiber cord within the above range, the heat-resistant adhesion can be improved without sacrificing the strength and fatigue resistance.

Next, the manufacturing method of the said polyester fiber cord is demonstrated. As the polyester fiber cord, a yarn obtained by twisting a yarn obtained by heat treatment at 150 to 260 ° C. after treatment with an epoxy compound having two or more epoxy groups in a spinning or drawing process can be used. When imparting adhesiveness to rubber to the polyester fiber cord, a treatment liquid containing the following (A) to (D) is used.
(A) Treatment liquid containing carrier (B) Blocked isocyanate aqueous solution (C) Epoxy resin dispersion (D) Resorcin-formaldehyde-latex (RFL) mixed liquid

  These four components are combined so that the weight ratio of blocked isocyanate / latex is 0.5 / 1 to 3.0 / 1, and the cord processing is performed by one or more stages. . In order to achieve both strength and fatigue resistance and heat resistant adhesiveness, the solid content weight ratio of the blocked isocyanate aqueous solution and the latex component in RFL is blocked isocyanate / latex = 0.5 / 1 to 3.0 / 1. There is a need. In particular, blocked isocyanate / latex = 1.0 / 1 to 2.5 / 1 is preferable. If there are few blocked isocyanate components, sufficient heat-resistant adhesiveness cannot be ensured, and if there are few latex components, a code | cord will become hard and will lead to a fall of strength and fatigue resistance.

  The number of treatment stages may be either one-stage treatment or multistage treatment of two or more stages, but the first-stage treatment bath contains at least the treatment liquid (A) and the final-stage treatment bath contains at least the treatment liquid (D). Preferably, the number of treatment stages is two, the first treatment bath is treatment solution (A) and treatment solution (B), the second treatment bath is treatment solution (B), and treatment solution. It is preferable to contain (C) and a processing liquid (D).

  The treatment liquid (A) containing a carrier is obtained by dissolving, dispersing or emulsifying the carrier in water. Among them, auxiliary agents such as solvents, dispersions, emulsifiers or stabilizers other than the carrier, spinning oils, etc. May be contained. Examples of the carrier include phenol derivatives such as p-chlorophenol and o-phenylphenol, halogenated benzenes such as monochlorobenzene and trichlorobenzene, and a reaction product of resorcin, p-chlorophenol and formaldehyde.

  When the blocked isocyanate aqueous solution (B) is a mixture of polymethylene polyphenyl isocyanate having 3 or more functional groups, more preferably 4 or more functional groups, excellent heat resistant adhesiveness can be obtained. That is, when the isocyanate group is polyfunctionalized, there is an advantage that excellent heat resistant adhesiveness can be obtained even if the resin adhesion amount is lowered.

  About the dispersion liquid (C) of an epoxy resin, the crosslinking density of resin becomes high by using polyfunctional epoxy more than bifunctional, and the outstanding heat resistant adhesiveness is obtained. A preferred example is a polyglycidyl ether compound of an aliphatic polyhydric alcohol.

  Resorcin-formaldehyde-latex mixed liquid (D) is an initial condensate obtained by reacting resorcin and formalin in the presence of an acid or alkali catalyst, styrene butadiene latex, carboxyl group-containing styrene butadiene latex, styrene butadiene vinyl pyridine latex, acrylonitrile It is a mixed aqueous solution with two or more types such as butadiene latex. A known ratio of resorcin, formalin and latex can be employed.

  Various reinforcing cords with different Gurley type cord hardness are produced based on the cord material and dip liquid, and these types of reinforcing cords are used at the center and both ends of the belt reinforcing layer to provide five types of pneumatic radial tires (conventional example, Examples 1-2 and comparative examples 1-2) were produced respectively. These pneumatic radial tires have a tire size of 195 / 65R15 and share a structure other than the belt reinforcing layer.

  As the cord, a 1100 dtex / 2 polyethylene terephthalate fiber cord (PET), a 1100 dtex / 2 polyethylene naphthalate fiber cord (PEN), and a 940 dtex / 2 nylon fiber cord (66N) were used. The dip solution includes a carrier-containing treatment solution (D1), a blocked isocyanate aqueous solution (D2), an epoxy resin dispersion (D3), a resorcin-formaldehyde-latex (RFL) mixed solution (D4), and a pexel dip solution. (D5) and an epoxy dip solution (D6) were prepared.

  When both ends in the tire width direction of the belt layer located on the outermost side in the tire radial direction are used as base points, the width a (mm) at which both end portions of the belt reinforcing layer protrude from the base point in the tire width direction and the tire width from the base point The width b (mm) protruding outward in the direction is as shown in Table 1. Further, the Gurley-type cord hardness c (mg) of the polyethylene terephthalate fiber cord used for the central portion of the belt reinforcing layer and the Gurley-type cord hardness of the polyethylene naphthalate fiber cord used for both ends of the belt reinforcing layer d ( The ratio c / d to mg) is as shown in Table 1.

  For these test tires, road noise, radial force variation (RFV), and high-speed durability were evaluated by the following test methods, and the results are also shown in Table 1.

Road noise:
The test tire was mounted on the vehicle with an air pressure of 200 kPa, a microphone was installed at the position of the driver's seat window side ear, and the sound pressure when traveling on a rough road surface at a speed of 100 km / h was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. A larger index value means a greater road noise reduction effect.

Radial force variation (RFV):
Radial force variation was measured according to JASO C607 automotive tire uniformity test method. The evaluation results are shown as an index with the conventional example being 100. The smaller the index value, the better the uniformity.

High speed durability:
After the endurance test was carried out in accordance with the high speed endurance performance test method for automobile tires of JIS D4230, the test was continued and the travel distance until the failure of the tire occurred was measured. The evaluation results are shown as an index with the conventional example being 100. It means that high speed durability is excellent, so that this index value is large.

  As shown in Table 1, the tires of Examples 1 and 2 improve the reduction effect of road noise without deteriorating uniformity and high-speed durability in comparison with conventional examples using nylon fiber cords. I was able to. On the other hand, in the tire of Comparative Example 1, although good results were obtained with respect to high-speed durability and road noise, the decrease in uniformity was remarkable. In the tire of Comparative Example 2, although good results were obtained with respect to uniformity and road noise, the decrease in high-speed durability was significant.

1 is a meridian half cross-sectional view showing a pneumatic radial tire according to an embodiment of the present invention.

Explanation of symbols

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

Claims (3)

A pneumatic radial in which at least one belt layer is disposed on the outer circumferential side of the carcass layer in the tread portion, and a belt reinforcing layer is disposed on the outer circumferential side of the belt layer so as to extend the reinforcing cord in the tire circumferential direction. In the tire,
The belt reinforcing layer is divided into a center portion and both end portions in the tire width direction, and the absorbance ratio of the infrared absorption spectrum satisfies the following formula (1) or (2) as a reinforcing cord at the center portion of the belt reinforcing layer. A polyester fiber cord having a resin adhesion amount of 3 to 15% by weight and a Gurley cord hardness of 6000 to 20000 mg is used as a reinforcement cord at both ends of the belt reinforcement layer. Pneumatic radial tire using polyethylene naphthalate fiber cord with low Gurley cord hardness.
Formula (1) 0.5 ≦ absorbance ratio (1510 cm ⁻¹ absorption / 2920 cm ⁻¹ absorption) ≦ 6.0
Equation (2) 2.0 ≦ absorbance ratio (1510 cm ^-1 absorption / 700 cm ^-1 absorption) ≦ 25.0 When both ends in the tire width direction of the belt layer positioned on the outermost side in the tire radial direction are used as the base points, the width a (mm) and the base points at which both end portions of the belt reinforcing layer protrude from the base point in the tire width direction 2. The pneumatic radial tire according to claim 1, wherein a relationship with a width b (mm) protruding outward in the tire width direction from 0 ≦ a ≦ 50, 0 ≦ b ≦ 20, and 20 ≦ a + b ≦ 70. Gurley-type cord hardness c (mg) of the polyester fiber cord used in the central portion of the belt reinforcing layer and Gurley-type cord hardness d (mg) of the polyethylene naphthalate fiber cord used at both ends of the belt reinforcing layer. The pneumatic radial tire according to claim 1 or 2, wherein c / d ≧ 2 is satisfied.

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