JP6681704B2 - Steel cord for tire reinforcement and tire using the same - Google Patents

Description

  The present invention relates to a tire-reinforcing steel cord (hereinafter, also simply referred to as “steel cord”) and a tire using the same, and more specifically, to a tire-reinforcing steel capable of providing a tire having better durability than before. The present invention relates to a cord and a tire using the cord.

  In recent years, there has been an increasing demand for reducing the weight of tires in order to improve the fuel efficiency of automobiles. Here, when considering the weight reduction of the belt portion using the steel cord, it is necessary to thin the gauge of the coating rubber of the steel belt layer on the assumption that a certain tensile strength is secured. From such a viewpoint, a technique of using a steel filament as a cord for a belt without twisting has been developed, and various proposals have been made so far.

  Currently, as a tire using a bundled cord in which steel filaments are bundled without twisting, for example, Patent Document 1 can be cited. In Patent Document 1, 5 to 7 steel filaments having a filament diameter of 0.18 to 0.26 mm are aligned to form a bundle cord, and the bundle cord is arranged in parallel in the belt width direction on the first belt layer and the second belt layer. A tire that is embedded in coating rubber has been proposed. In this tire, the gauge of the rubber layer between the filament cords of the first belt layer and the second belt layer at the end portion of the second belt layer is 1.3 to 2.5 times the gauge in the belt central region, In at least a part of the steel filaments in each belt layer, the angle of the steel filament with respect to the tire circumferential direction is different between the belt center region and the belt end region, and the angle θ1 in the belt center region is the belt end. The angle is smaller than the angle θ2 in the partial area.

JP, 2011-173455, A

  The tire proposed in Patent Document 1 uses a bundle cord in which steel filaments are not twisted and aligned and is used as a reinforcing material for the belt, so that the belt layer is thin and excellent in lightness. The belt durability is improved by increasing the gauge of the rubber layer at the end of the belt layer while adjusting the cord angle to reduce the strain at the end of the belt layer. However, it is expected that the demand for tire durability will continue to increase in the future.

  Therefore, an object of the present invention is to provide a tire-reinforcing steel cord capable of providing a tire that is more durable than before and a tire using the same.

  The present inventor has obtained the following findings as a result of earnest studies to solve the above problems. That is, if the permeability of the rubber between adjacent steel filaments in the bundle cord is insufficient, the adjacent steel filaments are not bound to each other and cracks occur between the adjacent steel filaments due to the input during tire rolling. It may happen. In such a state, adjacent steel filaments rub against each other to cause fretting, and if water penetrates into them due to cutting or the like, corrosion of the steel filaments may progress and the steel filaments may disappear. Such a problem can occur not only in bundled cords but also in twisted cords having insufficient rubber penetration. Based on such knowledge, the present inventor has further earnestly studied, and as a result of applying a predetermined adhesive to a steel filament forming a steel cord, found that the above problems can be solved, and completes the present invention. Came to.

That is, the tire-reinforcing steel cord of the present invention is a tire-reinforcing steel cord comprising one or a plurality of steel filaments,
On the surface of the steel filament, an adhesive containing a halogenated polymer or a phenolic resin is applied as an undercoating adhesive, and an adhesive containing a halogenated polymer is applied as an overcoating adhesive. To do.

  In the steel cord of the present invention, the coating layer of the undercoat adhesive and the coating layer of the overcoat adhesive each preferably have a thickness of 5 to 20 μm. As the structure of the steel cord of the present invention, 1 × N (N = 2 to 6), M + N (M = 1 to 4, N = 2 to 10), or L + M + N (L = 1 to 4, M = 5 to 10). , N = 11 to 15), or a multi-twisted cord formed by twisting any of the above-mentioned twisted cords, or a bundled cord formed by aligning 3 to 7 of the steel filaments.

  The tire of the present invention is characterized in that the steel cord for tire reinforcement of the present invention is embedded.

  ADVANTAGE OF THE INVENTION According to this invention, the steel cord for tire reinforcement which can provide the tire more durable than before, and the tire using this can be provided.

It is sectional drawing of the steel cord for rubber article reinforcement which concerns on one suitable embodiment of this invention. It is sectional drawing of the steel cord for rubber article reinforcement which concerns on other suitable embodiment of this invention. It is sectional drawing of the steel cord for rubber article reinforcement which concerns on other suitable embodiment of this invention. 1 is a one-sided sectional view of a tire according to a preferred embodiment of the present invention. 6 is a graph showing the relationship between the steel filament diameter d and the number of filaments in the bundle n. It is an example of a width direction partial sectional view of a belt layer using the steel cord of the present invention as a reinforcing material.

Hereinafter, the steel cord of the present invention will be described in detail with reference to the drawings.
The steel cord of the present invention comprises one or more steel filaments. 1 to 3 are sectional views of a steel cord according to a preferred embodiment of the present invention, FIG. 1 is a steel cord having a 1 + 6 structure, and FIG. 2 is a double twist having a 7 × (3 + 9) structure. It is a steel cord, and FIG. 3 is a bundle cord in which five steel filaments are aligned without being twisted.

  As shown in FIGS. 1 to 3, in the steel cords 10, 20, and 30 of the present invention, a halogenated polymer or a phenol resin is used as the undercoat adhesive 12, 22, and 32 on the surface of the steel filaments 11, 21, and 31. And an adhesive containing a halogenated polymer is applied as the overcoat adhesive 13, 23, 33. As described above, the undercoat adhesives 12, 22, 32 having a high affinity with the metal are applied to the surfaces of the steel filaments 11, 21, 31 and the overcoat adhesives 13, 23, 33 having a high affinity with the rubber are applied thereon. Is applied to secure the adhesiveness between the steel cords 10, 20, 30 and the rubber, and the adjacent steel filaments 11, 21, 31 are adhered to each other to thereby fix each other, and the steel caused by fretting. The filaments 11, 21 and 31 are prevented from being deteriorated in durability. The undercoating adhesive and the topcoating adhesive preferably have bending durability, which exhibits flexibility close to that of rubber, heat resistance, and moisture resistance.

  As the undercoat adhesive, an adhesive containing a halogenated polymer or a phenol resin is used. Examples of halogenated polymers include chlorinated natural rubber, chlorinated polyethylene, chlorosulfonated polyethylene, chlorinated polybutadiene, brominated polymers and the like. Specific examples of commercially available adhesives containing a halogenated polymer include "CHEMLOK 205" and "CHEMLOK 200" manufactured by Rhode. Examples of the phenol resin include novolac type, resol type and various modified phenol resins. Specific examples of the adhesive made of a phenolic resin include "Metaloc PH-56" manufactured by Toyo Kagaku Kenkyusho Co., Ltd.

  As the overcoat adhesive, an adhesive containing a halogenated polymer is used. Examples of halogenated polymers include chlorinated natural rubber, chlorinated polyethylene, chlorosulfonated polyethylene, chlorinated polybutadiene, brominated polymers and the like. Examples of commercially available products include "CHEMLOK 6108" manufactured by Lord Co., Ltd., "Metalock F-112" manufactured by Toyo Kagaku Kenkyusho Co., Ltd., and the like. Suitably, a combination of "CHEMLOK 205" as the undercoat adhesive and "CHEMLOK 6108" as the overcoat adhesive, a combination of "Metalloc PH-56" as the undercoat adhesive and "Metalloc F-112" as the overcoat adhesive. .

  In the steel cord of the present invention, the thickness of the coating layer of the undercoat adhesive and the thickness of the coating layer of the topcoat adhesive are each preferably 5 to 20 μm. This is because if the thickness of the coating layer of the adhesive exceeds 20 μm, foaming may occur. On the other hand, when the thickness of the coating layer is less than 5 μm, the performance as an adhesive may not be sufficiently exhibited, and salt damage may occur.

  In the steel cord of the present invention, the steel filament may or may not be plated with brass or the like. Generally, a steel cord for reinforcing rubber articles has brass plating on its surface from the viewpoint of adhesiveness with rubber, but with the steel cord of the present invention, sufficient adhesion with rubber is obtained with an adhesive. The brass plating is not always necessary because it can ensure the quality. Therefore, with the steel cord of the present invention, the brass plating step in the manufacturing process can be omitted, and the manufacturing cost and workability are improved. Further, there is a problem that the adhesiveness to rubber differs depending on the ratio of copper and zinc in the brass plating, the thickness of the brass plating, etc. However, such a problem does not occur with an adhesive. Furthermore, the brass plating method requires plating equipment that requires a large investment and sophisticated plating processing technology. From these facts, the indirect adhesion method of applying an adhesive without plating the steel filament is preferable.

  In the steel cord of the present invention, the method of applying the undercoat adhesive and the topcoat adhesive to the steel filament is not particularly limited, and may be applied using a brush, or a known method such as dip coating or spray coating. Any of these may be used. At this time, it is preferable that the undercoat adhesive and the topcoat adhesive have such a viscosity that they can be easily applied to the steel filament and easily penetrate into the irregularities of the steel cord, and that the drying after application is short. . From such a viewpoint, it is preferable to use the undercoating adhesive and the topcoating adhesive diluted with a solvent. For example, the undercoat adhesive is preferably diluted with methyl ethyl ketone, methyl isobutyl ketone, or the like, and the overcoat adhesive is preferably diluted with toluene, xylene, ethylbenzene, or the like. Prior to the application of these adhesives, it is preferable that the surface of the steel filament be subjected to an appropriate cleaning treatment such as degreasing treatment with an organic solvent to remove rust, oil, water, dirt and the like in advance. The adhesive can be dried by natural drying or warm air drying, and the steel filament may be heated in advance and dried by residual heat.

  The timing of applying the undercoat adhesive and the topcoat adhesive to the steel filament is preferably after twisting the steel filament in the case of a twisted cord and after twisting the strands in the case of a double twisted cord. This is because even if the undercoating adhesive and the topcoating adhesive are applied before the twisted cords and strands are twisted together, the adhesive may peel off with the guide of the twisting machine when twisting the steel filaments and strands. . In the case of a bundle cord, it is preferable to apply an undercoat adhesive and an overcoat adhesive before bundling the steel filaments. This allows adjacent steel filaments in the bundle to be bonded together.

  The steel cord of the present invention comprises a steel filament surface coated with an adhesive containing a halogenated polymer or a phenolic resin as an undercoating adhesive, and an adhesive containing a halogenated polymer as an overcoating adhesive. Yes, there is no particular limitation other than this. For example, the filament diameter of the steel filament, its composition, its physical properties, and the like can be appropriately designed according to the purpose. Further, the adhesion between the steel cord and the rubber of the present invention can be performed by heating and pressurizing as in the conventional case.

  The steel cord of the present invention can be used as a reinforcing material for rubber products such as tires, belts and hoses, and can be used as a reinforcing material for carcasses and belts as long as it is a tire. For example, in addition to using one steel filament as a steel cord as it is, 1 × N (N = 2 to 6), M + N (M = 1 to 4, N = 2 to 10), or L + M + N (L = 1 to 4, M = 5 to 10, N = 11 to 15) twisted cords, or a double twisted cord formed by twisting any of these twisted cords. In addition to these twisted cords, a bundled cord in which 3 to 7, in the example shown in FIG. 3, five steel filaments are aligned without being twisted may be used.

  The belt is composed of a belt layer composed of a steel cord and coating rubber, and examples of the rubber component of the rubber composition for coating rubber include natural rubber and synthetic rubber. Examples of the synthetic rubber include polybutadiene rubber, isoprene rubber, styrene / butadiene copolymer rubber, butyl rubber, halogenated butyl rubber, preferably brominated butyl rubber, butyl rubber having a paramethylstyrene group (specifically isobutylene and p-halogenated rubber). Copolymers with methylstyrene), ethylene / propylene / diene rubber (EPDM) and the like. The rubber component may be used singly or in combination of two or more, but from the viewpoint of the adhesiveness with the steel cord and the destructive property of the coating rubber, at least one of natural rubber and isoprene rubber is used. It is preferable that the content is at least mass%.

  If the steel cord of the present invention is used, the coating rubber composition contains a compounding amount of an adhesion promoter comprising a heavy metal salt, such as cobalt salts of organic acids such as cobalt naphthenate, cobalt rosinate, and cobalt stearate. Since it can be reduced, deterioration of rubber can be suppressed.

Next, the tire of the present invention will be described.
The tire of the present invention is one in which the steel cord for reinforcing a rubber article of the present invention is embedded. FIG. 4 shows a one-sided sectional view of a tire according to a preferred embodiment of the present invention. The illustrated tire 100 is a passenger car tire, and as shown in the drawing, a tread portion 101 that is disposed in a crown region of a carcass to form a ground contact portion, and a tire radial direction inward direction continuous to both sides of the tread portion 101. It is provided with a pair of sidewall portions 102 extending to the side and a bead portion 103 continuous to the inner peripheral side of each sidewall portion 102. Further, a carcass 104 made of one carcass layer extending in a toroidal shape from one bead portion 103 to the other bead portion 103 is arranged, and at least two layers are provided on the tire radial direction outer side of the crown region of the carcass 104. In the illustrated example, it is reinforced by a belt 105 including two layers of a first belt layer 105a and a second belt layer 105b. Here, the carcass layer of the carcass 104 may be plural.

  In the case of a passenger car tire as illustrated, from the viewpoint of weight reduction, a bundle cord obtained by bundling a plurality of steel filaments without twisting can be suitably used as a reinforcing material for the belt, and for example, 3 to 7 It is possible to use a bundle cord formed by aligning the steel filaments. In addition to this, in the case of truck / bus tires and off-road tires, cords made by twisting multiple steel filaments and strands made by twisting multiple steel filaments are further twisted. A multi-twisted cord formed by combining the cords may be used as a reinforcing material for a belt or a carcass, but is not limited thereto.

  In the case of the bundle cord in the tire of the present invention, the diameter d (mm) of the steel filament is preferably 0.18 mm or more and 0.30 mm or less. If the filament diameter is less than 0.18 mm, it is difficult to secure the strength and rigidity of the belt layer as a tire, and if the filament diameter exceeds 0.30 mm, the strain on the steel filament surface during repeated bending deformation during tire running. Is large, and when a large bending deformation is applied during traveling on a bad road or the like, the steel filament is likely to be broken and durability may be deteriorated.

When the bundle cord is used as a reinforcing material for the belt 105, the tensile strength TS (N / mm ² ) and the diameter d (mm) of the steel filament are expressed by the following formula:
TS ≧ -2625d + 3853 (1)
It is preferable that the relationship represented by This is because when the steel cord of the present invention is used as a reinforcing material for the belt 105, the steel filament is required to have high tensile strength.

Further, when the bundle cord is used as a reinforcing material for the belt 105, the diameter d (mm) of the steel filament and the number n (steel) of the steel filament per bundle are expressed by the following formula:
1.0 / n ≦ 270.6d ⁵ −293.6d ⁴ + 74.7d ³ + 18.9d ² −3.3d ≦ 4.3 / n (2)
It is preferable that the relationship represented by With respect to the number n of steel filaments in the bundle, the filament diameter d (mm) was analyzed as a variable, and the results shown in FIG. 5 were obtained as a region showing the proper number of steel filaments in the bundle.

  That is, if the number of steel filaments in the bundle is too small, in order to secure the required strength of the belt layer, the number of hammers must be increased, and the interval between the bundles becomes narrow, and the coating rubber and steel filament Peeling is likely to occur. In order to prevent this, the proper region of the number n of filaments in the bundle is above the lower curve in FIG. On the other hand, if the number of filaments in the bundle is too large, the rolling (calendering) work for embedding the filaments in the coated rubber becomes difficult and the mass productivity is reduced. It is required to be below the curve above. From the above, it was deduced that the proper region of the number n of filaments in the bundle with respect to the diameter d (mm) of the steel filament is a region between the two curves in FIG. This is expressed by a mathematical formula and it is necessary to satisfy.

Furthermore, when the bundle cord is used as a reinforcing material for the belt 105, when the thickness of the belt ply is T and the diameter of the steel filament bundle in the thickness direction of the belt ply is DT, formula,
0.13 ≦ DT / T ≦ 0.49 (3)
It is preferable that the relationship represented by Here, FIG. 6 is an example of a partial cross-sectional view in the width direction of a belt layer using the steel cord of the present invention as a reinforcing material. When DT / T is less than 0.13, the rigidity of the belt layer may be insufficient. On the other hand, if DT / T exceeds 0.49, the thickness of the rubber layer may be insufficient and durability may be reduced.

  The thickness T of the belt ply is preferably 1.0 mm or less. When T exceeds 1.0 mm, it is not preferable for reducing the weight of the tire. Further, the interval δG between the bundles is preferably 0.3 to 1.3 mm. The interval δG between the bundles is 0.3 to 1.3 mm in order to prevent the occurrence of separation (separation) within the belt ply and between belt plies due to large deformation during tire running and to suppress the propagation of separation. Is advantageous.

  The tire 100 of the present invention is not particularly limited except that the steel cord of the present invention is embedded. For example, as shown in the drawing, a bead core 106 is embedded in each of the pair of bead portions 103 of the tire 100 of the present invention, and the carcass 104 is folded around the bead core 106 from the inside of the tire to the outside and locked. A tread pattern is appropriately formed on the surface of the tread portion 101, and an inner liner (not shown) is formed on the innermost layer. Further, in the tire 100 of the present invention, as the gas to be filled in the tire, normal air or air having a changed oxygen partial pressure, or an inert gas such as nitrogen can be used.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Examples 1 to 8 and Comparative Examples 1 to 10>
Steel cords were produced using the steel filaments shown in Tables 1 to 3 below. Metallock PH-56 manufactured by Toyo Kagaku Kenkyusho Co., Ltd. was used as the undercoat adhesive, and Metalloc F-112 manufactured by Toyo Kagaku Kenkyusho Co., Ltd. was used as the topcoat adhesive. Two belt plies were produced using the obtained steel cord, and a tire of the type shown in FIG. 5 (tire size 175 / 70R14) was produced. Using the obtained tire, a belt peeling resistance test, a filament disappearance test, and a belt breakability test were performed, and the rolling workability was evaluated. The detailed procedure is as follows. The proper number of filaments in the table is a value calculated from the equation (2).

<Belt peeling resistance test>
After mounting the test tire on the regular rim, filling it with an internal pressure of 150 kPa (1.5 kgf / cm ² ) and mounting it on a test passenger car, running it on an open road for 60,000 km, dissecting the test tire, The length of the crack occurring in the slab was measured. The reciprocal of the crack length of each test tire is calculated, and the tire of Comparative Example 1 is expressed as an index with 100 as the index. The larger this index, the better the belt peeling resistance. If it is 75 or more, there is no practical problem. The obtained results are also shown in Tables 1 to 3.

<Filament disappearance test>
From the inner surface side of the test tire, a hole having a diameter of 3.5 mm that reaches the belt layer is formed near the end of the belt, 120 mL of 5% concentration salt water is injected inside the tire, and the tire is assembled to a regular rim, and 150 kPa (1.5 kgf / Cm ² ), and was mounted on a test passenger car and run on a general road for 10,000 km. Then, the test tire was dissected to measure the length of filament disappearance occurring in the belt. The reciprocal of the filament vanishing length of each test tire was calculated, and the tire of Comparative Example 1 was represented by 100 as an index. The larger this index, the better the belt peeling resistance. If it is not more than 110, problems will occur in practical use. The obtained results are also shown in Tables 1 to 3.

<Belt break test>
After mounting the test tire on the actual vehicle and running on a winding road that bends at a constant speed of 20,000 km at a speed of 60 km per hour, the test tire was dissected and the steel cord in the belt layer was sampled and broken. The number of reinforcing materials in the state was checked, the reciprocal thereof was calculated, and the tire of Comparative Example 1 was set as 100 and indicated by an index. The larger this index, the more excellent the belt fold resistance. No problem if 100 or more. The obtained results are also shown in Tables 1 to 3.

<Rolling workability test>
The time required for the preparatory work and the rolling (calendering) work of the cord before coating the cord for the belt with the coated rubber was measured, and when 20% or more of the working time of Comparative Example 1 was taken as poor workability, Within 20%, the workability was evaluated as good. The obtained results are also shown in Tables 1 to 3.

<Comparison between Example 1 and Comparative Example 1 and Comparative Example 2>
Compared to Example 1, Comparative Example 1 is inferior in filament disappearance property because no adhesive is applied to the filament. In Comparative Example 2, the result was that the rolling workability of the belt ply as a member was poor.

<Comparison between Example 2 and Comparative Example 3 and Comparative Example 4>
Compared to Example 2, Comparative Example 3 is inferior in filament disappearing property because the filament is not coated with the adhesive. Comparative Example 4 resulted in further poor belt peeling resistance.

<Comparison between Example 3 and Comparative Example 5 and Comparative Example 6>
It can be seen that Example 3 is lighter than Comparative Example 6 and has improved belt peeling resistance, filament disappearance property, and belt fold resistance. However, in Comparative Example 5, the filament disappearance property was not improved because the adhesive was not applied to the filament.

<Comparison between Example 4 and Comparative Example 7>
In Example 4, which uses a small diameter and high strength steel filament, the effect of weight reduction is most remarkable. Comparative Example 7 has the effect of reducing the weight, but the filament disappearance property is not improved.

<Comparison between Example 1 and Example 5>
It is understood that the effects of the present invention can be obtained by using the undercoating adhesive and the topcoating adhesive according to the present invention regardless of the presence or absence of brass plating on the surface of the steel filament.

<Comparison between Examples 6 to 8 and Comparative Examples 8 to 10>
Comparing Comparative Examples 8 to 10 with Examples 6 to 8, it can be seen that even with steel cords formed by twisting steel filaments, the steel cords of Examples 6 to 8 have improved belt peeling resistance. Recognize. In addition, since Examples 6 to 8 and Comparative Examples 8 to 10 are twisted cords, filament disappearance property is not evaluated. In addition, since Examples 7 and 8 and Comparative Examples 9 and 10 are cords that are usually used for heavy-duty tires, belt fold resistance is not evaluated.

11, 21, 31 Steel filament 12, 22, 32 Undercoat adhesive 13, 23, 33 Topcoat adhesive 10, 20, 30 Steel cord 100 Tire 101 Tread portion 102 Sidewall portion 103 Bead portion 104 Carcass 105 Belt 105a First belt Layer 105b Second belt layer 106 Bead core

Claims (5)

In a steel cord for tire reinforcement consisting of one or more steel filaments,
On the surface of the steel filament, an adhesive containing a halogenated polymer or a phenolic resin is applied as an undercoating adhesive, and an adhesive containing a halogenated polymer is applied as an overcoating adhesive. Steel cord for tire reinforcement. The tire reinforcing steel cord according to claim 1, wherein the undercoat adhesive coating layer and the overcoat adhesive coating layer each have a thickness of 5 to 20 µm. 1 × N (N = 2 to 6), M + N (M = 1 to 4, N = 2 to 10), or L + M + N (L = 1 to 4, M = 5 to 10, N = 11 to 15) twisted cords The steel cord for tire reinforcement according to claim 1 or 2, which is a double twist cord formed by twisting one of the twist cords. The steel cord for tire reinforcement according to claim 1 or 2, wherein the steel filament is a bundle cord in which 3 to 7 filaments are aligned. A tire comprising the steel cord for tire reinforcement according to any one of claims 1 to 4 embedded therein.

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