JP2019107947A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire, which can improve high-speed durability and impact resistance without increasing mass of a belt reinforcing layer.SOLUTION: The pneumatic tire comprises a carcass, a belt arranged at an outer periphery of a crown part of the carcass and a belt reinforcing layer arranged at an outer periphery of the belt. The belt reinforcing layer comprises a belt reinforcing ply that has a cord having a double-twist structure made by intertwisting two primarily twisted yarn made of filament bundles of aliphatic polyamide fiber, which is an organic fiber cord whose nominal fineness is 4000 dtex or less and whose tension toughness (J) for one cord is 5J or more, which is arranged so that a long diameter direction of the organic fiber cord is in parallel to an outer peripheral surface of the belt, where products of the tension toughness (J) and the number of driving (number/25 mm) for one organic fiber cord are 130-180.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire.

  When using an organic fiber cord such as nylon 66 for the belt reinforcing layer of the pneumatic tire, as a method of improving the impact resistance, for example, increasing the number of the cords to be inserted and increasing the cord diameter are cited. Be However, when such means are adopted, there is a problem that it leads to an increase in tire mass due to a decrease in high-speed durability and an increase in member mass.

  With respect to such problems, Patent Document 1 aims to provide a pneumatic radial tire capable of achieving both high speed durability and load durability, and the outer peripheral side of the carcass layer 4 in the tread portion 1 In a pneumatic radial tire in which at least one belt layer 6 is disposed and the belt reinforcing layer 7 formed by winding reinforcing cords in the tire circumferential direction on the outer peripheral side of the belt layer 6 is provided. As a hybrid cord in which a rayon lower yarn and a lyocell lower yarn are twisted together, wherein the twist coefficient α of the upper twist is 1400 ≦ α ≦ 3800, the breaking elongation is 10% or more, and the toughness coefficient β is 1260 or more It is disclosed to use a code that is

  However, there is room for further improvement in high-speed durability and impact resistance.

JP 2008-265688 A JP, 2017-19461, A

  An object of the present invention is to provide a pneumatic tire which can improve high-speed durability and impact resistance without increasing the mass of the belt reinforcing layer.

  In Patent Document 2, a belt layer 7 in which cords are obliquely arranged with respect to the tire circumferential direction on the outer circumferential side of the carcass layer 4 in the tread portion 3 and an organic fiber cord on the outer circumferential side of the belt layer in the tire circumferential direction In a pneumatic tire provided with a belt reinforcing layer 9 arranged along a line, the cord is made of an aliphatic polyamide fiber as an organic fiber cord of the belt reinforcing layer, and a load at 2% elongation (cN / dtex) and a temperature Although it is disclosed to use a cord whose product with loss tangent tan δ at 100 ° C. is 0.035 to 0.044, a pneumatic tire capable of reducing rolling resistance while improving flat spot resistance. It is intended to provide no reference to high speed durability and impact resistance.

  A pneumatic tire according to the present invention is a pneumatic tire having a carcass, a belt disposed on the outer periphery of a crown portion of the carcass, and a belt reinforcing layer disposed on the outer periphery of the belt, wherein the belt reinforcing layer is A cord having a twin-twist structure in which two pretwisted yarns composed of filament bundles of aliphatic polyamide fibers are twisted together, having a nominal fineness of 4000 dtex or less, and a tensile toughness (J) per cord of 5 J or more The belt has an organic fiber cord, and the belt reinforcement ply is disposed so that the major axis direction is parallel to the outer peripheral surface of the belt, and the tension toughness (J) per one organic fiber cord and the number of punched pieces (wire / 25 mm) The product of and is assumed to be 130 to 180.

  The aliphatic polyamide fiber can be made of nylon 66.

  According to the pneumatic tire of the present invention, excellent high-speed durability and impact resistance can be obtained without increasing the weight of the belt reinforcing layer.

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

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  The pneumatic tire T of the embodiment shown in FIG. 1 is a pneumatic radial tire, and connects radially outer end portions of the left and right bead portions 1 and the sidewall portions 2 with the left and right sidewall portions 2. And a tread portion 3 provided between the side wall portions, and a carcass 4 is provided which extends between a pair of bead portions.

  The carcass 4 is composed of at least one carcass ply having its both ends locked by an annular bead core 5 embedded in the bead portion 1 from the tread portion 3 to the sidewall portion 2. The carcass ply is formed by arranging carcass cords made of an organic fiber cord or the like substantially at right angles to the circumferential direction of the tire.

  A belt 6 is disposed between the carcass 4 and the tread rubber portion 7 on the outer peripheral side (that is, the outer side in the tire radial direction) of the carcass 4 in the tread portion 3. The belt 6 is provided on the outer periphery of the crown portion of the carcass 4 and can be constituted by one or a plurality of belt plies, usually at least two belt plies, and in the present embodiment, the carcass side The first belt ply 6A and the second belt ply 6B on the tread rubber portion side are composed of two belt plies. The belt plies 6A and 6B are formed by inclining steel cords at a predetermined angle (for example, 15 to 35 degrees) with respect to the tire circumferential direction and arranging the steel cords at predetermined intervals in the tire width direction. Each belt ply has a steel cord coated with a coating rubber. The steel cords are disposed to intersect each other between the two belt plies 6A and 6B.

  A belt reinforcing layer 8 is provided between the belt 6 and the tread rubber portion 7 on the outer peripheral side of the belt 6 (that is, on the outer side in the tire radial direction). The belt reinforcing layer 8 is a cap ply which covers the belt 6 with its entire width by a belt reinforcing ply, and is made of an organic fiber cord whose major axis direction is arranged substantially parallel to the tire outer peripheral direction. That is, the belt reinforcing layer 8 has organic fiber cords arrayed along the tire circumferential direction, and the organic fiber cords have an angle of 0 to 5 degrees with respect to the tire circumferential direction so as to cover the entire width direction of the belt 6 Can be formed by spiral winding.

  The belt reinforcing layer 8 of the present embodiment is a cord of a twin-twist structure formed by twisting two lower-twisted yarns composed of filament bundles of aliphatic polyamide fibers, having a nominal fineness of 4000 dtex or less, per cord Has an organic fiber cord having a tensile toughness (J) of 5 J or more. Here, "tensile toughness (J)" was obtained by performing a tensile test using a tensile tester after leaving for 24 hours under a constant temperature condition of 20 ° C and 65% RH according to JIS L 1017. It is the amount of work (breaking energy) to be performed until the fiber breaks with elongation from the stress-strain curve (hereinafter, also referred to as an S-S curve). The tensile toughness can be adjusted by the nominal fineness of the organic fiber cord or the like.

  The resin used as the aliphatic polyamide fiber is not particularly limited. For example, nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66 copolymer, nylon 6/66 And aliphatic polyamide resins such as nylon / MXD6, nylon 6T, and nylon 6 / 6T copolymers, among which nylon 66 is preferred.

  The organic fiber cord is obtained by pretwisting a filament bundle of aliphatic polyamide fibers and twisting two yarns obtained thereby. For example, it can be produced by drawing and aligning two lower twisted yarns obtained by twisting filament bundles of aliphatic polyamide fibers in the Z direction, and twisting them in the S direction which is the reverse direction of the twist direction of the first twist. The number of twists of the upper twist and the lower twist is not particularly limited, but is preferably 20 to 40 times / 10 cm, and the number of the upper twist and the number of the lower twist are preferably set to the same value. .

  The cord thus stranded is usually subjected to a dip treatment using a known adhesive treatment solution, whereby an organic fiber cord as a dip treated cord is obtained.

  The nominal fineness of the organic fiber cord is not particularly limited as long as it is 4,000 dtex or less, but preferably 2,000 to 3,500 dtex, and more preferably 2,000 to 3,000 dtex. When the nominal fineness is 4000 dtex or less, the increase in tire mass can be easily suppressed. The nominal fineness of the organic fiber cord is a value obtained by adding the fineness of two yarns to be twisted together.

  The tensile toughness (J) per organic fiber cord is not particularly limited as long as it is 5 J or more, but is preferably 5 to 10 J. When the tensile toughness (J) is 5 J or more, excellent impact resistance is easily obtained.

  The method of forming the belt reinforcing layer 8 on the belt 6 using an organic fiber cord is not particularly limited. For example, a plurality of organic fiber cords aligned and rubber-coated may be spirally wound on the belt 6 of a raw tire, or alternatively, a wide rubberized sheet in which the organic fiber cords are aligned may be belt 6 It may be wound around the top. In this manner, a green tire (green tire) is manufactured in a state in which the belt reinforcing layer 8 is wound around the outer periphery of the belt 6, and the obtained green tire is vulcanized and molded to obtain a pneumatic tire.

  The product of the tensile toughness (J) per organic fiber cord and the number of punched pieces (piece / 25 mm) is 130 to 180, preferably 140 to 170. Excellent impact resistance can be easily obtained when the product of the tensile toughness (J) and the number of punched pieces (piece / 25 mm) is 130 or more, and by 180 or less, the number of punched pieces does not become too large, which is excellent High speed durability is easy to be maintained.

  The cord occupancy per unit width in the belt reinforcing ply is not particularly limited, but is preferably 85% or less, more preferably 55 to 85%. When the code occupancy rate is 85% or less, excellent high-speed durability is easily maintained.

  The type of pneumatic tire according to the present embodiment is not particularly limited, and various types of tires such as tires for passenger cars, heavy duty tires used for trucks, buses and the like can be mentioned.

  In the above-mentioned embodiment, although belt reinforcement layer 8 explained what is a cap ply which covers belt 6 with the full width, it is not limited to this, but covers the end of the tire width direction outside of belt 6, and its circumference The edge ply may be an edge ply, and the edge ply may be a portion in which both ends in the tire width direction of the cap ply are folded back.

  Hereinafter, although the example of the present invention is shown, the present invention is not limited to these examples.

  An organic fiber cord having a structure shown in Table 1 below was produced. The measurement method for the organic fiber cord is as follows.

Cord diameter (mm): Four of the obtained organic fiber cords were arranged in parallel so as not to be slack, and were measured with a dial gauge (diameter of leg 9.5 mm).

Tensile toughness (J): A tensile test is conducted using a tensile tester after standing for 24 hours under a constant temperature condition of 20 ° C. and 65% RH in accordance with JIS L 1017, and stretching from the obtained S-S curve The amount of work (breaking energy) to be done until the fiber breaks with it was determined.

  Further, using the obtained organic fiber cord as a cord for a belt reinforcing layer, a radial tire having a tire size of 225/60 R17 was vulcanized and formed according to a conventional method. About each tire, all the configurations other than the belt reinforcing layer were common. The steel cord in the belt ply had a 2 + 1 × 0.27 structure, and the number of strikes was 19 / inch. The angle of the steel cord in the belt ply (6A) / (6B) was + 25 ° / -25 ° with respect to the tire circumferential direction. The belt reinforcing ply was prepared by arranging the cords in the number of the driving in accordance with Table 1 so that the major axis direction was parallel to the belt surface, and then making the topping opposite using a calender device.

  The carcass ply was formed of 2 plies of polyethylene terephthalate cord 1100 dtex / 2 and the number 22 of the punched sheets / 25 mm.

  The thickness of the belt reinforcing ply was determined for the obtained toppings. The measuring method is as follows.

-Thickness of belt reinforcing ply: A thickness as a belt reinforcing ply obtained by coating an organic fiber cord with a covering rubber, which is measured by a dial gauge (diameter of leg 9.5 mm).

  The weight, impact resistance, and high-speed durability of the belt reinforcing layer were evaluated for each of the obtained pneumatic tires. The evaluation method of each evaluation item is shown below. In Comparative Examples 2 and 3, the mass of the belt reinforcing ply increased, and Comparative Example 3 was inferior in impact resistance as compared with the conventional example, and therefore, high speed durability was not evaluated.

The weight of the belt reinforcing layer: The total weight of the belt reinforcing ply used per tire, and the total weight of the belt reinforcing ply of the conventional example is indicated as an index of 100. The smaller the number, the lighter.

Impact resistance: A topping reaction in which an organic fiber cord is topped with rubber is vulcanized, and the obtained rubber composite is used as a sample. Using a tensile tester (Autograph manufactured by Shimadzu Corporation), the organic fiber cord breaks or the sample at a speed of 5 mm / min with a metal rod (tip shape: hemispherical, diameter: 1 cm) I pushed until it penetrated. The test was ended when the above condition was reached, and the total amount of energy up to the maximum point was measured. The conventional example is expressed as an index of 100. The larger the index, the better the impact resistance.

High-speed durability: Measured by a drum tester having a 1700 mm diameter rotating drum made of steel having a smooth surface according to FMVSS 109 (UTQG) as follows. The test tire was attached to a standard rim specified by JIS at an internal pressure of 220 kPa (2.2 kgf / cm ² ), and the load was 88% of the maximum load specified by JATMA. After running-in at a speed of 80 km / h, it was allowed to cool once, and after the air pressure was adjusted again, main running was performed. The main run started from 120 km / h, and thereafter, the speed was increased by 8 km / h every 30 minutes, and the vehicle was run until a failure occurred. The total travel distance of the main run until the occurrence of a failure is indexed as 100 for the conventional example. The higher the index, the better the high-speed durability.

  The results are as shown in Table 1, and Examples 1 and 2 were superior in impact resistance and high speed durability while maintaining the lightness of the belt reinforcing ply as compared with the conventional example.

  In Comparative Example 1, the tensile toughness (J) per organic fiber cord was outside the predetermined range, and the high-speed durability was inferior to that of the conventional example.

  In Comparative Example 2, the nominal fineness of the organic fiber cord was outside the predetermined range, and the mass of the belt reinforcing ply increased as compared with the conventional example.

  In Comparative Example 3, the product of the tensile toughness (J) per organic fiber cord and the number of strikes (pieces / 25 mm) is outside the predetermined range, and the mass of the belt reinforcing ply is increased compared to the conventional example. Impact resistance was inferior.

  In Comparative Example 4, the product of the tensile toughness (J) per organic fiber cord and the number of punched pieces (piece / 25 mm) was outside the predetermined range, and the high-speed durability was inferior to that of the conventional example.

  The pneumatic tire of the present invention can be used for various vehicles such as passenger cars, light trucks, buses and the like.

T ... tire 1 ... bead portion 2 ... sidewall portion 3 ... tread portion 4 ... carcass 5 ... bead core 6 ... belt 6A ... first belt ply 6B ... second belt ply 7 ... tread rubber portion 8 ...... Belt reinforcement layer

Claims (2)

A pneumatic tire comprising a carcass, a belt disposed on an outer periphery of a crown portion of the carcass, and a belt reinforcing layer disposed on an outer periphery of the belt,
The belt reinforcing layer is a cord of a twin-twist structure formed by twisting two lower-twisted yarns composed of filament bundles of aliphatic polyamide fibers, and having a nominal fineness of 4000 dtex or less, and a tensile toughness per cord ( J) has a belt reinforcing ply having an organic fiber cord having a length of 5 J or more, and arranged so that the major axis direction of the organic fiber cord is parallel to the outer peripheral surface of the belt,
A pneumatic tire characterized in that the product of the tensile toughness (J) per one organic fiber cord and the number of impacted pieces (piece / 25 mm) is 130 to 180. The pneumatic tire according to claim 1, characterized in that the aliphatic polyamide fiber is made of nylon 66.