JP2016203684A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which can achieve both lightweight property and cutting resistance and is excellent in workability during production and production cost.SOLUTION: There is provided a pneumatic tire 10 which comprises a cross belt 5 in which at least two belt layers 5a and 5b formed by embedding a plurality of steel monofilaments aligned without being twisted in a rubber are disposed so as to cross each other between the layers. A belt reinforcement layer 6 which has at least one layer and is formed by embedding a reinforcement element in a rubber between the layers of the cross belt 5, the steel monofilament of the cross belt 5 has an angle of 35° or more with respect to the tire circumferential direction, and the reinforcement element of the belt reinforcement layer 6 is formed of an organic fiber cord.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more specifically, a pneumatic tire that is highly compatible with light weight and cut resistance and that is excellent in workability and manufacturing cost during manufacturing. About.

  In recent years, there has been an increasing demand for lighter tires in order to improve the fuel efficiency of automobiles. Conventionally, in order to reduce the weight of tires, a technology that uses a steel cord as a belt cord without twisting steel monofilament is known instead of a twisted cord in which a plurality of steel filaments are twisted as a belt cord. A cross belt has been developed in which at least two belt layers are arranged so as to cross each other. When the belt cord is made into a monofilament in this way, the belt layer can be thinned, and the weight of the tire can be reduced.

  However, when a belt layer made of steel monofilament is used, there is a problem that the bending rigidity (in-plane bending rigidity) in the belt surface is lowered. Therefore, in Patent Document 1, a pneumatic radial tire for a passenger car provided with a belt auxiliary layer made of a steel cord embedded at an angle of 80 to 90 ° with respect to the tire circumferential direction in order to compensate for the insufficient in-plane bending rigidity. Has been proposed. According to Patent Document 1, by providing the belt auxiliary layer, it is possible to suppress the buckling of the belt cord and to compensate the fatigue property against bending that is reduced due to monofilament formation.

JP 2012-254668 A

  However, if a belt reinforcing layer made of steel cord is provided, the amount of steel used increases, leading to an increase in tire weight. Therefore, in the tire described in Patent Document 1, the advantage of reducing the weight of the tire by configuring the cross belt with a belt layer made of steel monofilament cannot be fully utilized, and the weight reduction of the tire is not always satisfactory. This is not the case. Further, in the belt layer made of steel monofilament, if the belt angle is set to 35 ° or more with respect to the circumferential direction in order to give in-plane bending rigidity, the rigidity in the tire circumferential direction is lowered, so that the cut resistance is reduced. It may decrease. Furthermore, improvement in workability and manufacturing cost at the time of manufacturing a tire is also desired.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire that is highly compatible with light weight and cut resistance, and that is excellent in workability and manufacturing cost during manufacturing.

  As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by making the arrangement and materials of the belt layer and the belt auxiliary layer predetermined. It came to complete.

That is, the pneumatic tire of the present invention is formed by arranging at least two layers so that a belt layer in which a plurality of steel monofilaments arranged without being twisted are embedded in rubber intersects each other. In pneumatic tires with crossed belts,
Comprising at least one belt reinforcing layer in which a reinforcing element is embedded in rubber between layers of the cross belt;
An angle of the cross belt with respect to the tire circumferential direction of the steel monofilament is 35 ° or more, and the reinforcing element of the belt reinforcing layer is made of an organic fiber cord.

In the tire of the present invention, the organic fiber cord is preferably a cord made of at least one selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, nylon, polyketone, and rayon. In the tire of the present invention, the thickness of the belt layer is S (mm), the diameter of the steel monofilament is s (mm), the thickness of the belt reinforcing layer is T (mm), and the organic fiber cord When the diameter is t (mm), the following formula (1),
1.24 <(T + S) / (t + s) <3.63 (1)
It is preferable to satisfy the relationship represented by these.

  According to the present invention, it is possible to provide a pneumatic tire that is highly compatible with light weight and cut resistance, and that is excellent in workability and manufacturing cost during manufacturing.

1 is a cross-sectional view in the width direction of a pneumatic tire according to one preferred embodiment of the present invention. It is a schematic plan view which shows the relationship between the belt layer and belt reinforcement layer of the pneumatic tire which concerns on one preferable embodiment of this invention. 1 is a cross-sectional view in the tire width direction of a cross belt and a belt reinforcing layer of a pneumatic tire according to a preferred embodiment of the present invention.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view in the width direction of a pneumatic tire according to one preferred embodiment of the present invention. As shown in the figure, a tire 10 of the present invention includes a tread portion 1 that forms a ground contact portion, a pair of sidewall portions 2 that extend inward in the tire radial direction continuously to both sides of the tread portion 1, and each side. And a bead portion 3 continuous on the inner peripheral side of the wall portion 2. The tread portion 1, the sidewall portion 2, and the bead portion 3 are reinforced by a carcass 4 including a single carcass ply extending in a toroidal shape from one bead portion 3 to the other bead portion 3.

  In the tire 10 of the present invention, at least two layers (two layers in the illustrated example), preferably two layers of the first belt layer 5a and the second belt layer 5b, are formed on the outer side of the crown region of the carcass 4 in the tire radial direction. A belt is provided. The first belt layer 5a and the second belt layer 5b are formed by embedding a plurality of steel monofilaments arranged in parallel in the tire width direction without being twisted in the rubber. The two belt layers 5b are arranged so as to intersect with each other between the layers to form the intersecting belt 5.

  In the tire of the present invention, the angle of the steel monofilament of the cross belt 5 with respect to the tire circumferential direction is 35 ° or more. By arranging the steel monofilament at a high angle with respect to the tire circumferential direction, in-plane bending rigidity is imparted to the cross belt 5, and the durability and wear resistance of the tire 10 are ensured. Preferably, the angle of the steel monofilament with respect to the tire circumferential direction is 45 ° or more.

  Furthermore, in the tire 10 of the present invention, at least one belt reinforcing layer 6 in which a reinforcing element is embedded in rubber is embedded between the layers of the cross belt 5. FIG. 2 is a schematic plan view showing the relationship between the belt layer and the belt reinforcing layer of the pneumatic tire according to one preferred embodiment of the present invention. Since the belt layers of the tire of the present invention (the first belt layer 5a and the second belt layer 5b in the illustrated example) have an angle of 35 ° or more with respect to the tire circumferential direction, the tensile stiffness in the tire circumferential direction is Not enough. Therefore, the belt reinforcing layer 6 is disposed between the layers of the cross belt 5 to compensate for the insufficient tensile rigidity in the tire circumferential direction. Further, by inserting the belt reinforcing layer 6 between the layers of the cross belt 5, the cross belt layer (second belt layer 5b in the illustrated example) made of steel monofilament serves as a protective layer and improves cut resistance. be able to. Note that the angle of the organic fiber cord of the belt reinforcing layer 6 is preferably 0 ° to 10 ° with respect to the tire circumferential direction because the purpose is to supplement the tensile rigidity in the tire circumferential direction which lacks the purpose.

  Furthermore, in the tire 10 of the present invention, the reinforcing element of the belt reinforcing layer 6 is made of an organic fiber cord. By using a cord made of organic fiber as the reinforcing element, the weight of the tire can be reduced as compared with the case where steel is used. In the tire 10 of the present invention, the reinforcing element constituting the belt reinforcing layer 6 is intended to ensure tensile rigidity in the tire circumferential direction, and therefore, a cord made of highly elastic organic fibers is preferably used. Organic fiber cords include aromatic polyamide (aramid), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), rayon, Zylon (registered trademark) (polyparaphenylene benzobisoxazole (PBO) fiber), aliphatic polyamide ( Nylon) or the like can be used.

FIG. 3 shows a cross-sectional view in the tire width direction of a crossing belt and a belt reinforcing layer of a pneumatic tire according to a preferred embodiment of the present invention. In the tire 10 of the present invention, the thickness of the belt layers (first belt layer 5a and second belt layer 5b in the illustrated example) is S (mm), the diameter of the steel monofilament 7 is s (mm), and the belt reinforcing layer 6 is used. When the thickness of T is (mm) and the diameter of the organic fiber cord 8 is t (mm) (see FIG. 2), the following formula (1),
1.24 <(T + S) / (t + s) <3.63 (1)
It is preferable to satisfy the relationship represented by these. Here, T = 0.5 to 2.0, t = 0.2 m to 1.8, S = 0.66 to 1.2, and s = 0.12 to 0.45. By setting (T + S) / (t + s) to be 1.25 or more, belt edge separation (BES) in which the interlayer gauge is maintained and rubber peeling starting from the cord end of the belt width direction end portion easily propagates between adjacent cords. ) Can be satisfactorily prevented. On the other hand, by using less than 3.63, the amount of rubber used can be reduced, and both belt edge separation resistance (hereinafter referred to as “BES resistance”) and light weight can be achieved.

  Furthermore, in the tire 10 of the present invention, the width of the belt reinforcing layer 6 is preferably 60% or more of the tread width. By setting the width of the belt reinforcing layer 6 to 60% or more of the tread width, the tensile rigidity in the tire circumferential direction can be effectively improved. Preferably, the belt reinforcing layer 6 is disposed over the entire tread width. The tread width is the maximum width in the tire axial direction of the tire contact surface when a tire is mounted on a regular rim, filled with a regular internal pressure, placed perpendicular to the flat plate in a stationary state, and a regular load is applied. Say.

  Furthermore, in the tire 10 of the present invention, the number of driven organic fiber cords 8 in the belt reinforcing layer 6 is preferably 20 to 80/50 mm. By setting the number of drivings to 20/50 mm or more, the tensile rigidity in the tire circumferential direction can be sufficiently secured. On the other hand, by setting the number of drivings to 80/50 mm or less, both the tensile rigidity in the tire circumferential direction and the BES resistance can be achieved.

  In the tire 10 of the present invention, the total fineness of the organic fiber cord 8 in the belt reinforcing layer 6 is preferably 500 to 8000 dtex. By setting the total fineness of the organic fiber cord to 500 dtex or more, the circumferential tensile rigidity of the belt reinforcing layer 6 can be sufficiently ensured. On the other hand, the total fineness of the organic fiber cord 8 is preferably 8000 dtex or less. By setting the total fineness to 8000 dtex or less, the belt reinforcing layer 6 can be thinned, and both the circumferential tensile rigidity and the weight reduction can be achieved.

  Furthermore, in the tire 10 of the present invention, it is preferable that the wire diameter of the steel monofilament 7 constituting the cross belt 5 is 0.12 to 0.45 mm. By setting the wire diameter of the steel monofilament 7 to 0.12 mm or more, the in-plane bending rigidity of the cross belt 5 can be sufficiently secured. On the other hand, by setting the wire diameter of the steel monofilament 7 to 0.45 mm or less, an increase in the thickness of the belt layer can be prevented, and both in-plane bending rigidity and weight reduction of the belt layer can be achieved. More preferably, it is 0.25 to 0.35 mm.

  Furthermore, it is preferable that the steel monofilament 7 constituting the cross belt 5 and the organic fiber cord 8 constituting the belt reinforcing layer 6 have straightness that is not subjected to any type. This is because a straight cord does not have initial elongation, so that sufficient rigidity can be obtained immediately after input from the outside.

  Furthermore, in the tire 10 of the present invention, it is preferable that the intervals between the steel monofilaments 7 are equal. By making the intervals between the steel filaments 7 uniform, the manufacture of the belt treat is facilitated and the productivity is improved. Further, since there is no extremely narrow portion between the steel filaments 7, the BES resistance is excellent.

  In the illustrated tire 10 of the present invention, the steel monofilaments constituting the first belt layer 5a and the second belt layer 5b are preferably symmetric with respect to the tire circumferential direction. By adopting such a configuration, the productivity of the tire is improved and the stress can be shared equally, which is preferable from the viewpoint of the durability of the tire.

  The tire 10 of the present invention has at least a belt layer in which a plurality of steel monofilaments aligned without being twisted are embedded in rubber on the outer side in the tire radial direction of the carcass 4 so as to intersect each other between the layers. A cross belt 5 having two layers is provided, and at least one belt reinforcing layer 6 in which a reinforcing element is embedded in rubber is provided between the layers of the cross belt 5. It is only important that the angle with respect to the direction is 35 ° or more and the organic fiber cord is used as the reinforcing element, and a known structure can be adopted as the other structure.

  For example, as shown in the figure, a bead core 9 is embedded in each of the pair of bead portions 3 of the tire of the present invention, and the carcass 4 is folded around the bead core 9 from the inside of the tire to the outside and locked. The carcass is usually composed of at least one layer (one layer in the illustrated example) of carcass plies made of a plurality of organic fiber cords arranged at a cord angle of 70 ° to 90 ° with respect to the tire equatorial plane. The organic fiber cord used for the carcass can be a single twisted cord, a double twisted cord, or a multi-twisted cord of three or more. Moreover, the organic fiber cord used for the carcass may be one in which filaments of one kind of organic fiber are twisted or may be one in which filaments of two or more kinds of organic fibers are twisted together. Further, the number of organic fiber cords used for the carcass is preferably 40 to 70 per 50 mm.

  In the tire according to the present invention, a tread pattern is appropriately formed on the surface of the tread portion 1, and an inner liner (not shown) is formed in the innermost layer. Further, in the tire 10 of the present invention, as the gas filled in the tire, normal or air having a changed oxygen partial pressure, or an inert gas such as nitrogen can be used. The tire of the present invention is suitable for a pneumatic tire for passenger cars.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Examples 1-5>
A tire of the type shown in FIG. 1 was produced with a tire size of 145 / 65R15. A cross belt was constituted by the first layer (first belt layer) and the third layer (second belt layer), and the second layer was a belt reinforcing layer. The wire diameter of the steel filaments constituting the first layer and the third layer is 0.3 mm, the number of driven wires is 45/50 mm, and the angle with respect to the tire circumferential direction is + 45 ° for the first belt layer and −45 for the second belt layer. °. The second layer is a belt reinforcing layer and is arranged so that the reinforcing element is substantially parallel to the tire circumferential direction over the entire width in the tread width direction. The reinforcing elements and structures of the second layer (belt reinforcing layer) are as shown in Tables 1 and 2. The number of reinforcing elements to be driven in the second layer (belt reinforcing layer) was 50/50 mm.

<Conventional example>
A pneumatic tire having a cross belt composed of a first layer and a second layer was produced at a tire size of 145 / 65R15. The reinforcing element of the cross belt is a steel cord having a 1 × 3 structure made of a steel filament having a wire diameter of 0.30 mm, the number of driven wires is 45/50 mm, and the angle with respect to the tire circumferential direction is ± 45 °. The conventional tire does not include a belt reinforcing layer.

<Comparative Example 1>
The tire of Comparative Example 1 has a tire size of 145 / 65R15, and the first layer (first belt layer) and the second layer (second belt layer) constitute a cross belt, and the steel filaments constituting these belt layers The wire diameter was 0.3 mm, the number of driving was 45/50 mm, and the angle with respect to the tire circumferential direction was + 45 ° for the first belt layer and −45 ° for the second belt layer. The third layer is a belt reinforcing layer and is arranged so that the reinforcing element is substantially parallel to the tire circumferential direction over the entire width in the tread width direction. The reinforcing elements and the structure of the third layer (belt reinforcing layer) are as shown in Table 2, and the number of driving is 50/50 mm.

<Comparative example 2>
The tire of Comparative Example 2 has a tire size of 145 / 65R15, and the first layer (first belt layer) and the second layer (second belt layer) constitute a cross belt, and the steel filaments constituting these belt layers The wire diameter was 0.3 mm, the number of driving was 45/50 mm, and the angle with respect to the tire circumferential direction was + 45 ° for the first belt layer and −45 ° for the second belt layer. The third layer and the fourth layer are belt reinforcing layers, and are arranged so that the reinforcing elements are substantially parallel to the tire circumferential direction over the entire width in the tread width direction. Reinforcing elements and structures of the third layer and the fourth layer (belt reinforcing layer) are as shown in Table 2, and the number of driving is 50/50 mm.

  About each obtained tire, tire weight was evaluated according to the following procedure.

<Tire weight>
The weight per tire was measured, and a case where the weight was equivalent to that of the conventional tire was Δ, a case where the weight was reduced by less than 50 g compared to the conventional example, and a case where the weight was reduced by 50 g or more were marked ◎. The results are shown in Tables 1 and 2.

<Cut resistance>
The drum was assembled to a rim specified by JATMA, subjected to an indoor drum test with a load twice the normal load, and a protrusion on the surface of the drum, and the evaluation was made based on the distance to tire destruction. When the tire of the conventional example was used as a reference (index: 100), the case of less than 100 was indicated by Δ, the case of 100 to 110 was indicated by ◯, and the case of exceeding 110 was indicated by ◎. The results are shown in Tables 1 and 2.

<Decisive workability>
With reference to the replacement frequency of the cutting blade in manufacturing the tire of the conventional example as a reference (index: 100), the case of less than 100 is Δ, the case of 100 to 120 is ◯, and the case of more than 120 is ◎. The results are shown in Tables 1 and 2.

<Cost>
The tire cost of the conventional example was set as a standard (index: 100), 101 or more was Δ, 100 was ◯, and less than 100 was 未 満. The results are shown in Tables 1 and 2.

  From the above Tables 1 and 2, it can be seen that the tire of the present invention is highly compatible with light weight and cut resistance. It can also be seen that by using a cord made of PEN, PET, nylon, polyketone, and rayon as the organic fiber cord of the belt reinforcing layer, it is excellent in terms of workability and cost.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass 5 Cross belt 5a 1st belt layer 5b 2nd belt layer 6 Belt reinforcement layer 10 Pneumatic tire (tire)

Claims (3)

In a pneumatic tire comprising a cross belt in which a belt layer in which a plurality of steel monofilaments arranged without being twisted are embedded in rubber is arranged at least two layers so as to cross each other,
Comprising at least one belt reinforcing layer in which a reinforcing element is embedded in rubber between layers of the cross belt;
A pneumatic tire characterized in that an angle of the steel monofilament of the cross belt with respect to the tire circumferential direction is 35 ° or more, and a reinforcing element of the belt reinforcing layer is made of an organic fiber cord.   The pneumatic tire according to claim 1, wherein the organic fiber cord is a cord made of at least one selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, nylon, polyketone, and rayon. When the thickness of the belt layer is S (mm), the diameter of the steel monofilament is s (mm), the thickness of the belt reinforcing layer is T (mm), and the diameter of the organic fiber cord is t (mm) , The following formula (1),
1.24 <(T + S) / (t + s) <3.63 (1)
The pneumatic tire according to claim 1 or 2, satisfying a relationship represented by:

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