High-rubber-permeability steel cord and off-road tire

Abstract

The steel cord comprises a core strand and a plurality of outer strands twisted on the periphery of the core strand, each of the core strand and the outer strands is formed by weaving and twisting N monofilaments, and the value of N ranges from 2 to 6. A coreless monofilament structure is adopted, a plurality of monofilaments are twisted into strands to form a more open structure, the diameter of each monofilament is larger than 0.3 mm, the monofilaments are suitable for a belted layer of an OTR tire, the rigidity of the cord thread is improved, protection of the belted layer is enhanced, meanwhile, a single-layer structure replaces a multi-layer structure, the better rubber permeation effect is achieved, and the service life of the tire is prolonged. The problem of center steel wire migration is well solved, and the safety of the tire becomes better.

Description

Technical Field

[0001] The present invention relates to the technical field of steel cord, and particularly to a high-permeability adhesive steel cord and a corresponding off-road tire. Background Art

[0002] Steel cord used for reinforcing heavy-duty tires such as off-road tires needs to have high strength. Therefore, the steel cord has multiple strands including multiple single filaments to achieve high strength, forming a corresponding OTR cord. The current OTR cords, such as the steel cord for rubber reinforcement and off-road tires disclosed in the patent No. CN209854313U, have a structure where both the core strand and the outer strands are twisted by one core single filament and six outer single filaments, that is, a 1 + 6 structure. The six outer single filaments on the outer layer tightly wrap around one core single filament, resulting in poor penetration of rubber into the core single filament. During the driving of heavy-duty tires, the OTR cord undergoes very heavy loads, and this load exerts a strong force on the core single filament in the core strand of the OTR cord. If the rubber adhesion is not good and the anchoring is not firm, the core single filament migrates out of the rubber layer, and in severe cases, it will pierce the outer rubber and be exposed, forming corrosion and driving moisture into the rubber layer to corrode the steel cord, seriously affecting the service life and safety of the tire. Moreover, the multi-layer structure will lead to an increase in production costs, and there is room for improvement. Summary of the Invention

[0003] The present invention is to avoid the deficiencies of the prior art and provides a high-permeability adhesive steel cord and a corresponding off-road tire.

[0004] The present invention solves the technical problems by adopting the following technical solutions: A high-permeability adhesive steel cord, characterized in that it includes a core strand and a plurality of outer strands twisted around the periphery of the core strand, and both the core strand and the outer strands are twisted by N single filaments, and the value of N is between 2 and 6.

[0005] In several embodiments, an outer winding wire is wound around the outside of the outer strands.

[0006] In several embodiments, the core strand, the outer strands and the outer winding wire have the same twist direction, and the twist direction of the steel cord is opposite to the twist direction of the outer winding wire.

[0007] In several embodiments, the twist pitch of the core strand and the outer strands is between 12.5 mm and 24 mm, and the twist pitch of the steel cord is between 16 mm and 32 mm.

[0008] In several embodiments, the diameter of the single filament is between 0.3 mm and 0.4 mm.

[0009] In several embodiments, the average tensile strength Ts of the single filament is in the following range: 3800 - 2000×Ds < Ts < 4400 - 2000×Ds, where Ds is the diameter of the single filament.

[0010] And, an off-road tire, comprising a carcass and a plurality of belt layers, wherein the belt layers have the above-mentioned steel cord structure.

[0011] The effective effects of the present invention are:

[0012] The present invention adopts a coreless monofilament structure, in which multiple monofilaments are twisted into strands to form a more open structure, and the monofilament diameter is greater than 0.3 mm. It is suitable for the belt layer of the OTR tire, improves the stiffness of the cord, and enhances the protection of the belt layer. At the same time, the single-layer structure replaces the multi-layer structure, has a better glue penetration effect, and well solves the problem of center steel wire migration, and the tire safety becomes better. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings described herein are for illustrative purposes only of selected embodiments and do not represent all possible implementations, and should not be considered to limit the scope of the present invention.

[0014] Figure 1 The overall structure of the steel cord for rubber reinforcement in Example 1 is schematically shown. DETAILED DESCRIPTION

[0015] Below, embodiments of the present invention are described in detail with reference to the accompanying drawings. To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0016] Therefore, the following detailed description of the embodiments of the present invention provided in conjunction with the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. All other embodiments obtained by ordinary technicians in the field based on the embodiments of the present invention without making any creative work are within the scope of protection of the present invention.

[0017] The steel cord for rubber reinforcement mainly includes a core strand 10, a plurality of outer strands 20 twisted around the core strand 10, and an outer winding 30 wound around the outer sides of the outer strands 20. The core strand 10 and the outer strands 20 are both twisted from N single filaments 101, and the value of N is between 2 and 6.

[0018] Among them, the twist direction of the core strand 10, the outer strand 20 and the outer winding wire 30 is the same, the twist direction of the steel cord is opposite to the twist direction of the outer winding wire 30, the twist pitch of the core strand 10 and the outer strand 20 is between 12.5mm and 24mm, and the twist pitch of the steel cord is between 16mm and 32mm.

[0019] Moreover, the diameter of the monofilament 101 is between 0.3 mm and 0.4 mm, and the average tensile strength Ts of the monofilament 101 is in the following range: 3800 - 2000×Ds < Ts < 4400 - 2000×Ds, where Ds is the diameter of the monofilament 101.

[0020] Example 1

[0021] As Figure 1 shown, in this embodiment, it includes a core strand 10 and 6 outer strands 20 twisted around the periphery of the core strand 10. Both the core strand 10 and the outer strands 20 are first formed by twisting 3 monofilaments 101, with a twist pitch of 16 mm and a twist direction of S. Subsequently, 1 core strand 10 and 6 outer strands 20 are twisted, with a twist direction of Z and a twist pitch of 20 mm. Subsequently, an outer winding wire is wound around the periphery of the outer strands 20, with a twist pitch of 5 mm and a twist direction of S. The diameter of the monofilament 101 is 0.32 mm, and the diameter of the outer winding wire is 0.15 mm.

[0022] Comparative Example 1

[0023] Such as the structure of the steel cord for rubber reinforcement disclosed in the patent No. CN209854313U in the background art.

[0024] The steel cords in Example 1 and Comparative Example 1 are combined with rubber to form rubberized samples. After intercepting 200 mm in length and sealing and clamping both ends, a gas with a set pressure is passed through one end (input end). After a certain period of time, the pressure at the other end (output end) is detected. The ratio of the pressure at the output end to the pressure at the input end is the air permeability.

[0025] According to the above test method, the obtained data are shown in the following table:

[0026]

[0027] According to the above test results, it can be known that the steel cord in this embodiment has a lower air permeability, indicating less gas passage, better anti-gel penetration performance, a significant improvement in corrosion resistance, and a lower linear density.

[0028] All the ways described herein can be carried out in any suitable order. Any and all examples used, or the exemplary language provided herein (such as "for example") are only used to better illustrate the present invention and do not limit the scope of the present invention, unless otherwise claimed. The language in the detailed description should not be construed as indicating any essential elements for practicing the present invention that are not claimed.

[0029] The present invention describes preferred embodiments, including the best mode of carrying out the invention known to the inventors. Of course, variations of these preferred embodiments will be apparent to those skilled in the art. The inventors anticipate that the skilled artisan may use such variations as appropriate, and the inventors indicate that the present invention may be implemented in other ways than those specifically described herein. Therefore, the present invention includes all modifications encompassed by the spirit and scope of the invention as defined by the claims. Furthermore, unless otherwise stated or clearly contradictory in context, the present invention includes any of the above-described factors and all possible variations thereof.

Claims

1. A high-permeability rubber steel cord, characterized in that: It includes a core strand (10) and a plurality of outer strands (20) twisted around the periphery of the core strand (10). Both the core strand (10) and the outer strands (20) are formed by twisting N single filaments (101), and the value of N is between 2 and 6.

2. A high-permeability rubber steel cord according to claim 1, characterized in that: An outer winding wire (30) is wound around the outside of the outer strand (20).

3. A high-permeability rubber steel cord according to claim 2, characterized in that: The twisting directions of the core strand (10), the outer strands (20) and the outer winding wire (30) are the same, and the twisting direction of the steel cord is opposite to that of the outer winding wire (30).

4. The high-permeability rubber steel cord according to claim 1, characterized in that: The pitch of the core strand (10) and the outer strands (20) is between 12.5 mm and 24 mm, and the pitch of the steel cord is between 16 mm and 32 mm.

5. The high-permeability rubber steel cord according to claim 1, characterized in that: The diameter of the single filament (101) is between 0.3 mm and 0.4 mm.

6. The high-permeability rubber steel cord according to claim 1, characterized in that: The average tensile strength Ts of the single filament (101) is in the following range: 3800 - 2000×Ds < Ts < 4400 - 2000×Ds, where Ds is the diameter of the single filament (101).

7. An off-road tire, characterized in that: The off-road tire includes a carcass and a plurality of belt layers, and the belt layer includes the steel cord according to any one of claims 1-6.

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