JP2008290503A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire in which an elongation of a carcass layer follows lift at vulcanization even when a highly elastic organic fiber code with an elastic modulus of 6.0 GPa or more is used for the carcass layer in order to improve tire durability, so that a uniformity of manufactured tires is extremely good. <P>SOLUTION: The pneumatic radial tire has at least one or more carcass layers, and a belt layer at the outer periphery of the carcass layer. The pneumatic radial tire is characteristic in that an organic fiber code with the elastic modulus of 6.0 GPa or more is used for the carcass layer, the carcass layer has a configuration of being divided in a tire equatorial direction at a crown part, the respective carcass layers are comprised so that width direction lengths W<SB>1</SB>, W<SB>2</SB>laid over a maximum width belt layer are at least 40 mm or more, and or less (the maximum belt width -40 mm). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire suitable for a passenger car having excellent durability while having excellent tire uniformity.

  Conventionally, in general, polyethylene terephthalate fiber cords have been widely used for carcass of passenger car tires.

  On the other hand, in recent years, there is a case where a high elastic modulus organic fiber cord is used for the purpose of improving tire durability. Generally, when a high elastic modulus organic fiber cord having an elastic modulus of 6.0 GPa or more is used, Due to the fact that the high modulus organic fiber is not easily stretched, the elongation of the carcass layer cannot follow the lift during vulcanization, and as a result, there is a drawback that the uniformity of the manufactured tire is very likely to deteriorate. .

  In view of such points, the present inventors have studied the structure of the carcass layer so that the elongation of the carcass layer follows the lift during vulcanization.

  As a prior patent focused on the structure of carcass, in pneumatic radial tires for passenger cars and light trucks, by separating the steel carcass with a wire diameter of 0.125 to 0.25 mm in the tire width direction with the crown as a boundary, There is a proposal to improve the cord durability at the crown (Patent Document 1).

  However, the invention proposed in Patent Document 1 is a steel cord having a twist structure of 1 × N, 1 + N or 2 + N (N: 2 to 7), which is used as a cord. There were no problems inherent to the organic fiber cord.

  In addition, a split portion is provided in the belt arrangement region using an organic fiber cord carcass such as polyester, the split width is 90% or less of the belt width, and the height of the folded portion of the carcass is 35 mm or less. A radial tire has been proposed (Patent Document 2).

However, the proposal of this patent document 2 is to use an organic fiber for the carcass to make the carcass ply easy to extend, and to achieve both steering stability, riding comfort performance and in-vehicle noise performance, and has a high elastic modulus.・ It was not related to the one using high-strength organic fiber cord.
JP 2001-39110 A JP 2001-187511 A

  In view of the above points, the object of the present invention is to improve the tire durability even when a high elastic modulus organic fiber cord having an elastic modulus of 6.0 GPa or more is used for the carcass layer. The elongation of the layer can follow the lift during vulcanization, and as a result, the tires produced are intended to provide a pneumatic radial tire with very good uniformity.

  The pneumatic radial tire of the present invention that achieves the above-described object has the following configuration (1).

(1) In a pneumatic radial tire having at least one carcass layer and a belt layer on the outer peripheral side of the carcass layer, an organic fiber cord having an elastic modulus of 6.0 GPa or more is formed on the carcass layer. And the carcass layer has a configuration in which the carcass layer is divided along the tire equator direction at the crown portion, and each of the carcass layers has a width direction length that overlaps the maximum width belt layer of at least 40 mm or more. A pneumatic radial tire characterized by having a maximum belt width of 40 mm or less.

  In the pneumatic radial tire of the present invention, preferably, the pneumatic radial tire has any one of the following configurations (2) to (5).

(2) The organic fiber cord includes one or more kinds of fibers selected from 6 nylon, 66 nylon, polyethylene terephthalate, polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers. The pneumatic radial tire according to the above (1), characterized by comprising:

(3) The organic fiber cord is formed by twisting a plurality of organic fiber yarns composed of one or more kinds of fibers selected from polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers. The pneumatic radial tire according to (1) or (2), wherein the pneumatic radial tire is a tire.

(4) The organic fiber cord is made of one or more kinds of fibers selected from polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers, 6 nylon, 66 (1) or (2) above, wherein a plurality of organic fiber yarns composed of one or more kinds of fibers selected from nylon and polyethylene terephthalate fibers are twisted together. Pneumatic radial tires.

(5) The pneumatic radial tire according to any one of (1) to (4), wherein the pneumatic radial tire is a tire for a passenger car.

  According to the present invention, even when a high elastic modulus organic fiber cord having an elastic modulus of 6.0 GPa or more is used for a carcass layer for the purpose of improving tire durability, the elongation of the carcass layer is As a result, it is possible to provide a pneumatic radial tire with extremely good uniformity.

  Hereinafter, the present invention will be described in more detail.

  Hereinafter, the pneumatic radial tire of the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a tire meridian direction sectional view showing the structure of a carcass of a pneumatic radial tire according to the present invention, and FIG. 2 is an enlarged view of a main part, particularly explaining the overlap of a carcass layer and a belt layer.

1 and 2, a pneumatic radial tire 1 according to the present invention is a pneumatic radial tire having at least one or more carcass layers 4a and 4b and a belt layer 6 on the outer peripheral side of the carcass layer. The carcass layer uses an organic fiber cord having an elastic modulus of 6.0 GPa or more, and the carcass layer is divided along the tire equator direction at the crown portion (carcass layers 4a and 4b). In addition, each of the carcass layers 4a and 4b is configured such that the widthwise lengths W ₁ and W ₂ overlapping the maximum width belt layer are at least 40 mm or more (maximum belt width −40 mm) or less. It is characterized by this. The left and right overlapping width direction lengths W ₁ and W ₂ may be the same length, or one length may be increased and the other length may be decreased.

  In FIGS. 1 and 2, 2 is a sidewall portion, 3 is a bead portion, 5 is a bead core, 7 is a gap between end portions of both carcass layers 4a and 4b, and 8 is a bead filler.

  As described above, the carcass layer that is originally formed between the bead cores is divided along the tire equator so that the carcass layer can easily extend at the divided portions during vulcanization. The elongation of the layer can follow the lift during vulcanization, and as a result, a tire with extremely good uniformity of the manufactured tire can be obtained.

  The high-modulus organic fiber cord used in the present invention has an elastic modulus of 6.0 GPa or more, preferably 7 GPa or more, and the upper limit of the elastic modulus value is about 20 GPa. is there. An organic fiber cord having an elastic modulus of less than 6.0 GPa has low durability and cannot achieve the intended purpose of the present invention.

  The high-modulus organic fiber is preferably one or more types of fibers selected from polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers.

  In the present invention, since the cord has only to have an elastic modulus of 6.0 GPa or more, a fiber having a normal elastic modulus such as 6 nylon, 66 nylon or polyethylene terephthalate fiber is partially twisted with the above fiber, for example, It may be used as a hybrid code.

  In one preferred embodiment of the present invention, the organic fiber cord is composed of one or more kinds of fibers selected from polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers. This is an embodiment in which a plurality of yarns are twisted together. In such an embodiment, the uniformity is excellent, but the durability is remarkably excellent.

  Alternatively, in another preferred embodiment, the organic fiber cord is composed of one or more kinds of fibers selected from polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers. In this embodiment, the yarn and a plurality of organic fiber yarns made of one or more kinds of fibers selected from 6 nylon, 66 nylon and polyethylene terephthalate fibers are twisted together. And uniformity will be very well balanced and excellent.

  The manufacturing method of the pneumatic radial tire of the present invention is not particularly limited. For example, a conventional manufacturing method using a member in which a carcass layer is attached to an inner liner separately on the right and left sides is prepared. Therefore, it can be manufactured by performing tire molding and vulcanization according to the above.

  In particular, the pneumatic radial tire of the present invention is most effective in terms of uniformity, durability, etc. when used for a tire for passenger cars, but the vehicle type is not particularly limited.

  As shown in Table 1, for each carcass layer using various organic fiber cords, the carcass layer was divided (Examples 1 to 4), the carcass layer was not divided (Conventional Example 1), and the carcass layer was divided. Although the width in the width direction where the carcass layer overlaps the maximum width belt layer is short (Comparative Example 1), the length in the width direction where the carcass layer overlaps the maximum width belt layer is too long (Comparison For each of the examples 2), tires having a tire size of 175 / 65R14 were actually manufactured and subjected to various evaluations. The maximum width of the belt layer is 140 mm.

  For details of the carcass structure, each test tire was manufactured by adjusting the cord weight, the number of ends, and the gauge. The specific belt structure is 2 + 2 × 0.25HT, the number of ends (number of cords) 40/50 mm width, angle 27 °, width: lower belt 140 mm, upper belt 130 mm.

  The rim size is 14 × 5.5JJ.

  The results of the evaluation are as shown in Table 1. The pneumatic radial tire according to the present invention was good in both uniformity and running durability.

  In the present invention, each characteristic is evaluated as follows.

(1) Elastic modulus (GPa) of organic fiber cord:
Disassemble the tire and collect the organic fiber cord. In accordance with JIS L-1017, the cord diameter is measured and a tensile test is performed, a stress-strain curve is drawn, the points of 10N and 67N are drawn in a straight line, and the slope of the straight line is obtained to obtain the elastic modulus (GPa) Ask for.

  The measurement was performed on 20 cords, and the average value was defined as the elastic modulus (GPa) of the organic fiber cord.

(2) Uniformity:
After assembling the manufactured tire for evaluation, the magnitude of force variation in the tire radial direction (N, radial force variation) is measured under the conditions of a test internal pressure of 200 kPa, a load of 3 kPa, and a tire rotation speed of 60 rpm. The measured values of the 10 tires were summed up, and the reciprocal number was calculated. The larger the index value, the better the uniformity.

(3) Tire durability performance:
The manufactured tire for evaluation is assembled with a rim, and then subjected to dry heat deterioration at an oxygen pressure of 350 kPa and a temperature of 80 ° C. for 5 days. After the dry heat deterioration, the charged oxygen is replaced with air, the air pressure is set to 200 kPa, and running is started at a speed of 120 km / hour and a load of 5 kN on a rotating drum having a diameter of 1707 mm. Every 24 hours running, the speed was increased by 10 km / hour, the running test was continuously carried out until the tire broke down, and the evaluation was expressed by an index with the running distance until the failure in Conventional Example 1 being 100. . The larger the index value, the better the tire durability performance.

FIG. 1 is a tire meridian direction sectional view showing a carcass structure of a pneumatic radial tire according to the present invention. FIG. 2 is a tire meridian direction cross-sectional view showing the structure of the carcass of the pneumatic radial tire according to the present invention, and in particular, the division of the carcass layer and the overlap of the belt layer of the divided carcass layer have been described. It is a principal part enlarged view.

Explanation of symbols

1: pneumatic radial tire 2: sidewall portion 3: bead portion 4a, 4b: carcass layer 5: bead core 6: belt layer 7: gap between end portions of both carcass layers 8: bead filler W ₁ : maximum width of carcass layer The length in the width direction that overlaps the belt layer (left side)
W ₂ : Length in the width direction (right side) where the carcass layer overlaps the maximum width belt layer

Claims (5)

  In a pneumatic radial tire having at least one carcass layer and a belt layer on the outer peripheral side of the carcass layer, an organic fiber cord having an elastic modulus of 6.0 GPa or more is used for the carcass layer, In addition, the carcass layer has a configuration in which the carcass layer is divided along the tire equator direction at the crown portion, and each of the carcass layers has a width direction length that overlaps the maximum width belt layer of at least 40 mm or more (maximum A pneumatic radial tire characterized by being configured to have a belt width of -40 mm or less.   The organic fiber cord comprises one or more kinds of fibers selected from 6 nylon, 66 nylon, polyethylene terephthalate, polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers. The pneumatic radial tire according to claim 1.   The organic fiber cord is formed by twisting a plurality of organic fiber yarns composed of one or more kinds of fibers selected from polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers. The pneumatic radial tire according to claim 1, wherein the pneumatic radial tire is provided.   The organic fiber cord is made of one or more kinds of fibers selected from polyethylene naphthalate, polyolefin ketone, polyvinyl alcohol, aramid, and rayon fibers, 6 nylon, 66 nylon and polyethylene The pneumatic radial tire according to claim 1 or 2, wherein a plurality of organic fiber yarns made of one or more kinds of fibers selected from each of the terephthalate fibers are twisted together.   It is a tire for passenger cars, The pneumatic radial tire in any one of Claims 1-4 characterized by the above-mentioned.

Images