JP2010248671A - Rubber-steel cord composite material and pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber-steel cord composite material which holds good adhesiveness and can simultaneously sufficiently reduce the compounded amounts of an adhesive promoter and sulfur in a coating rubber, and to provide a pneumatic radial tire using the rubber-steel cord composite material as a reinforcing layer. <P>SOLUTION: This rubber-steel cord composite material produced by twisting a plurality of sheath filaments or sheath strands together around a core prepared by coating or filling a filling rubber (A) on the peripheries or spaces of one or more core filaments or core strands, thus forming a layer-twisted steel cord or composite twisted steel cord, and coating the outer surface of the layer-twisted steel cord or composite twisted steel cord with a coating rubber (C), is characterized in that the filling rubber (A) contains an adhesive promoter. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rubber-steel cord composite used as a reinforcing member for a pneumatic radial tire, and a pneumatic radial tire having a reinforcing layer formed by the rubber-steel cord composite.

  Since cords used to reinforce pneumatic radial tires are required to have high strength, cords in which a plurality of sheath filaments are twisted around a core filament and core strands in which a plurality of filaments are twisted are further added. A cord having a so-called layer twist structure in which a plurality of sheath strands are twisted together is used. These cords are aligned and coated with a sheet-like coating rubber to obtain a rubber-cord composite.

  Such a coating rubber contains an adhesion promoter component for promoting adhesion to a cord such as steel and a large amount of sulfur. As such an adhesion promoter, organic acid cobalt salt is typical, but if it is blended in a large amount, it reacts with a vulcanization accelerator, an anti-aging agent, etc., so that it can be left in an unvulcanized state and then adherence or rubber. There is a possibility that the aging resistance of the resin may decrease, and the cost increases. In addition, when a large amount of sulfur is blended, vulcanization proceeds excessively before the vulcanization step, and there may be a problem that the physical properties of rubber after vulcanization are deteriorated.

  Under such circumstances, various rubber-cord composites having a rubber layer covering the periphery of the cord have been developed in addition to the coating rubber in order to solve the above problems (see Patent Documents 1 to 3).

JP 2002-338749 A JP 2003-11613 A JP 2007-313944 A

  However, none of the rubber-cord composites can sufficiently solve the problems caused by the above-mentioned adhesion promoter and high sulfur content.

  Accordingly, the present invention provides a rubber-steel cord composite capable of sufficiently reducing the adhesion promoter and sulfur content in the coating rubber while maintaining good adhesion, and a pneumatic radial tire using the rubber-steel cord composite as a reinforcing layer. The purpose is to do.

  In order to solve the above problems, the present inventor paid attention to the phenomenon that adhesion promoter and sulfur diffused and transferred from the filled rubber to the coated rubber during vulcanization by providing a filled rubber layer on the core. The found rubber-steel cord composite was found and the present invention was completed.

That is, the rubber-steel cord composite of the present invention is provided around one or a plurality of core filaments or core strands, and around the core formed by coating or loading the filler rubber (A) in the gap.
A plurality of sheath filaments or sheath strands are twisted together to form a layer-twisted steel cord or a double-stranded steel cord,
A rubber-steel cord composite obtained by coating the outer surface of the layer-twisted steel cord or the double-twisted steel cord with a coating rubber (C),
The filled rubber (A) is characterized by containing an adhesion promoter.
The coating rubber (C) preferably contains an adhesion promoter in an amount smaller than the content of the adhesion promoter in the filled rubber (A), and more preferably does not contain an adhesion promoter.

Further, the filled rubber (A) and the coating rubber (C) contain sulfur, and the sulfur content in the coating rubber (C) is less than the sulfur content in the filled rubber (A). Is preferred.
The coated rubber (B) may be coated on the outer surface of the layer-twisted steel cord or the double-twisted steel cord in advance, and then the coated rubber (C) may be coated. It is preferable that the adhesion promoter is contained in an amount larger than the content of the adhesion promoter in the coating rubber (C), and the adhesion promoter is contained in an amount equal to or less than the content of the adhesion promoter in the filled rubber (A). Is preferred.
The pneumatic radial tire of the present invention has a reinforcing layer made of these rubber-steel cord composites.

According to the rubber-steel cord composite of the present invention, since the content of the adhesion promoter in the coating rubber (C) is reduced as much as possible, the cost can be reduced and the deterioration of the aging resistance of the coating rubber can be effectively prevented. can do.
Further, since the filled rubber (A) is present in the core, the contact area between the filament or strand in the core and the rubber can be increased, and a stronger and more durable bond can be achieved.

Furthermore, the sulfur content in the coating rubber (C) can also be effectively reduced, and it is possible to prevent a decrease in fatigue fracture resistance.
If such a rubber-steel cord composite of the present invention is employed as a reinforcing layer, a pneumatic radial tire excellent in durability can be realized.

It is a figure which shows the layer twist steel cord which twisted together the filament of the same diameter of 3 + 9 structure. It is a figure which shows the double twist steel cord which twisted together the strand of the same diameter of 3 + 9 structure. FIG. 3A is a schematic diagram showing a first embodiment of the rubber-steel cord composite of the present invention, and FIG. 3B is a schematic diagram showing a second embodiment of the rubber-steel cord composite of the present invention. is there. FIG. 3C is a schematic view showing a conventional rubber-steel cord composite. It is a figure shown about the common code | cord | chord manufacturing equipment used in order to manufacture the code | cord | chord used for this invention. It is a figure which shows the area A of the clearance gap between a core and a sheath, and the area B of the filling rubber (A) layer which occupies between a core and a sheath. It is a figure which shows a mode that a filling rubber (A) is coat | covered to a core filament using a rubber coating apparatus. It is a figure shown about the cord manufacturing equipment used in order to manufacture a double twist steel cord. It is a figure which shows the apparatus used for evaluation of corrosion fatigue resistance.

  Hereinafter, the present invention will be described in detail with reference to the drawings as necessary. FIG. 1 shows a cross section orthogonal to the axial direction of a cord according to the present invention.

  FIG. 1 shows a steel cord used for the rubber-steel cord composite of the present invention, and nine sheaths that become sheaths 2 around a core 1 composed of three core filaments (or core strands) 1a. This is a layer-twisted steel cord 3a in which filaments (or strands) of the same diameter formed by twisting filaments (or sheath strands) 2a are twisted. The layer-twisted steel cord 3a has a filled rubber (A) layer 4 between the core 1 and the sheath 2 as shown by the oblique lines in FIG. In addition, when using a core strand and a sheath strand, as shown to Fig.2 (a)-(c), the double twisted steel cord 3b is comprised by twisting together several strands. FIG. 2 (a) has a rubber (A) layer 4 around the core strand 5, and FIG. 2 (b) is a result of twisting a plurality of steel cords as shown in FIG. 2 (c) is formed by twisting a plurality of steel cords as shown in FIG. 1 and further coating with a filled rubber (A).

  In the first aspect of the rubber-steel cord composite of the present invention, the core or the core formed by coating or loading the filler rubber (A) around the one or plural core filaments (or core strands) and the gaps is provided. A plurality of sheath filaments (or sheath strands) are twisted to form a layer-twisted steel cord (or double-twisted steel cord), and the outer surface of the steel cord is coated with a coating rubber (C). That is, as shown in the schematic diagram of FIG. 3 (a), the rubber layer is a rubber-steel cord composite composed of two layers of a filled rubber (A) layer 4 and a coating rubber (C) layer 7. In the conventional rubber-steel cord composite, for example, as shown in FIG. 3 (c), the filler rubber (A) is not coated or loaded around and around the core filament (or core strand). It was. On the other hand, since the rubber-steel cord composite of the present invention is formed by coating or loading the filled rubber (A) as described above, stronger adhesion between the core filament (or core strand) and the rubber and High durability can be demonstrated. Further, the presence of the filled rubber (A) suppresses fretting and improves corrosion fatigue resistance.

  In the second embodiment of the rubber-steel cord composite of the present invention, the core or the core formed by coating or loading the filler rubber (A) around the one or plural core filaments (or core strands) and the gaps is provided. A plurality of sheath filaments (or sheath strands) are twisted to form a layer-twisted steel cord or a double-twisted steel cord, and the outer surface of the steel cord is coated with a coating rubber (B) in advance, and then a coating rubber (C ). That is, as shown in the schematic diagram of FIG. 3B, a rubber-steel cord in which the rubber layer is composed of three layers of a filled rubber (A) layer 4, a covering rubber (B) layer 8, and a coating rubber (C) layer 7. It is a complex. In this case, the filled rubber (A) and the coated rubber (B) are in direct contact with the filament (or core strand) everywhere, and the adhesiveness and the higher durability are stronger than the case of the coated rubber (B) alone. Can be realized.

  In any embodiment, it is sufficient that the filled rubber (A) is filled in at least a part of the circumference and gap of one or a plurality of core filaments (or core strands). It does not have to protrude to the outer surface of the filament (or core strand). In addition, FIG. 2 shows an embodiment in which the filler rubber (A) is not coated or loaded around and between the core filaments forming the core strand. It may be coated or loaded.

  Steel for forming the cord used in the present invention is not particularly limited, but it is brass-coated by using a usual method, for example, a plating method, various CVD methods, a PVD method, etc., and has an adhesive property with vulcanized rubber. Particularly preferred are raised filaments (or strands).

  The rubber component used for the filling rubber (A), the coating rubber (C) and the covering rubber (B) is not particularly limited as long as it is used for tires. For example, natural rubber (NR) or polybutadiene is used. Rubber (BR), styrene / butadiene copolymer rubber (SBR), styrene / isoprene copolymer rubber (SIR), polyisoprene rubber (IR), butyl rubber (IIR), acrylonitrile-butadiene rubber, chloroprene rubber and ethylene / propylene Synthetic rubbers such as copolymers are listed, but it is desirable to use natural rubber (NR) alone.

  In addition to the above rubber components, additives, adhesion promoters, and the like are appropriately blended according to the properties required for each of the filled rubber (A), coating rubber (C), and coating rubber (B).

  Examples of the additive include a filler. In addition to carbon black such as SRF, GPF, FER, HAF, and ISAF, silica, calcium carbonate, talc, and the like can be used. When carbon black is blended, it is desirable to blend in an amount of 40 to 60 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of the adhesion promoter include organic acid cobalt salts such as cobalt naphthenate, cobalt rosinate, and linear or branched monocarboxylic acid cobalt salts having about 5 to 20 carbon atoms.

As other additives, a vulcanizing agent such as sulfur, an anti-aging agent, a vulcanization accelerator, a processing aid such as zinc oxide, an ozone deterioration preventing agent, and a plasticizer can be blended.
Hereinafter, for each of the first aspect and the second aspect in the rubber-steel cord composite of the present invention, the specific compositions of the various filled rubbers (A), coating rubbers (C) and coating rubbers (B) will be described.

[First aspect]
In the first embodiment of the present invention, as shown in the schematic diagram of FIG. 3 (a), the filled rubber (A) and the coating rubber (C) are used.

<< First aspect: Filled rubber (A) >>
The filled rubber (A) is a rubber that is in direct contact with filaments (or strands) and contains an adhesion promoter because good adhesion to these is required. The content of the adhesion promoter is usually 1.0 to 5.0 parts by mass, preferably 3.0 to 5.0 parts by mass with respect to 100 parts by mass of the rubber component. That is, the content is preferably larger than the content of the adhesion promoter in the coating rubber (C) described later. If the amount is not less than the above lower limit value, even if the adhesion promoter diffuses and transfers to the coating rubber (C) during vulcanization, the adhesion promoter can remain in a sufficient amount in the filled rubber (A). There is no risk that the initial adhesiveness will be unnecessarily lowered while maintaining excellent deteriorated adhesiveness with the steel cord. On the other hand, when blended in excess of the above upper limit, it is difficult to obtain a remarkable adhesion promoting effect, causing an increase in cost and reacting with the vulcanization accelerator and anti-aging agent blended together, resulting in poor deterioration adhesion. May be sufficient.

  Moreover, when mix | blending sulfur with the said filling rubber (A), it is desirable that there is more content of sulfur in coating rubber (C) so that it may mention later. Specifically, the amount is usually 3.0 to 7.0 parts by mass, preferably 5.0 to 7.0 parts by mass with respect to 100 parts by mass of the rubber component. If the amount is not less than the above lower limit, even if sulfur diffuses and migrates to the coating rubber (C) during vulcanization, a sufficient amount of sulfur can remain in the filled rubber (A). It is possible to effectively exhibit excellent adhesiveness. On the other hand, when it mix | blends exceeding the said upper limit, there exists a possibility that the heat-resistant deterioration property of the rubber | gum after vulcanization may fall, and fatigue fracture resistance may fall.

<< First aspect: Coating rubber (C) >>
When the coating rubber (C) used in the present invention contains an adhesion promoter, the content is preferably less than the adhesion promoter content in the filled rubber (A), more preferably not. Specifically, it is 0.0-1.0 mass part normally with respect to 100 mass parts of rubber components, Preferably it is less than 0.5 mass part. Thus, even if the content of the adhesion promoter in the coating rubber (C) is reduced, the adhesion promoter diffuses and transfers from the filled rubber (A) or the coating rubber (B) during vulcanization. Adhesiveness can be sufficiently maintained. In addition, by setting the amount within the above range, the reaction with the vulcanization accelerator and anti-aging agent blended in the coating rubber (C) can be effectively reduced, and deterioration adhesiveness and aging resistance can be reduced. It is possible to suppress the decrease. In addition, it can greatly contribute to cost reduction. Furthermore, the freedom degree of the compounding design regarding an adhesion promoter including the said filling rubber (A) improves.

  Moreover, when mix | blending sulfur with the said coating rubber (C), it is desirable that it is a quantity smaller than the sulfur mix | blended with the said filling rubber (A). Specifically, the amount is usually 3.0 to 7.0 parts by mass, preferably 3.0 to 5.0 parts by mass with respect to 100 parts by mass of the rubber component. Even if the sulfur content is thus reduced, sulfur diffuses and transfers from the filled rubber (A) to the coating rubber (C) after vulcanization as described above. In addition, it is possible to introduce sulfur in a sufficient amount, and it is possible to avoid deterioration of fatigue fracture resistance more than necessary.

[Second embodiment]
In the second embodiment of the present invention, as shown in the schematic diagram of FIG. 3 (b), the filling rubber (A), the covering rubber (B), and the coating rubber (C) are used.

<< Second aspect: Filled rubber (A) >>
In the second aspect of the present invention, the content of the adhesion promoter in the filled rubber (A) is preferably larger than the content of the adhesion promoter in the coating rubber (C), and adhesion in the coated rubber (B) described later. It is desirable that the content is the same as or more than the content of the promoter. In the second aspect, since the coated rubber (B) not in the first aspect is adopted, the content of the adhesion promoter in the filled rubber (A) is reduced by the amount that the adhesion promoter is contained in the coated rubber (B). This makes it possible to further improve workability. Specifically, it is 1.0-5.0 mass parts normally with respect to 100 mass parts of rubber components, Preferably it is 3.0-5.0 mass parts. If the amount is not less than the above lower limit, even if the adhesion promoter diffuses and transfers to the coated rubber (B) during vulcanization, the adhesion promoter can remain in the filled rubber (A) in a sufficient amount, There is no risk that the initial adhesiveness will be unnecessarily lowered while maintaining excellent deteriorated adhesiveness with the steel cord. On the other hand, when it mix | blends exceeding the said upper limit, it is difficult to acquire the remarkable adhesion promotion effect, and there exists a possibility that deterioration adhesiveness may become inadequate while causing a cost increase. By setting the content of the adhesion promoter within the above range, the content of the adhesion promoter in the coating rubber (C) can be effectively reduced together with the content of the adhesion promoter in the coated rubber (B). It is possible to greatly contribute to the reduction.

  Moreover, when mix | blending sulfur with the said filling rubber (A), it is 3.0-7.0 mass parts normally with respect to 100 mass parts of said rubber components, Preferably it is the quantity of 3.0-5.0 mass parts. It is desirable. In this way, even if the sulfur content in the filled rubber (A) is reduced, sulfur diffuses and migrates from the coated rubber (B) during vulcanization, so that sufficient adhesiveness is fully exhibited. Can do. In this case, from the viewpoint of improving workability, it is preferable that the sulfur content in the filled rubber (A) is smaller than the sulfur content in the coating rubber (B) described later. In this case, the progress of vulcanization before vulcanization can be more effectively suppressed, which contributes to improved workability.

<< Second aspect: Coated rubber (B) >>
When the coating rubber (B) contains an adhesion promoter, it is desirable that the content of the adhesion promoter in the coating rubber (C) is larger than that of the filling rubber (A). It is desirable that the content is the same as or less than the promoter content. Moreover, the accompanying effect of supplementing the shortage of the adhesion promoter content in the filled rubber (A) with the adhesion promoter content in the coated rubber (B) is also obtained. Specifically, the amount is usually 1.0 to 5.0 parts by mass, preferably 3.0 to 4.0 parts by mass with respect to 100 parts by mass of the rubber component. If the amount is not less than the above lower limit value, even if the adhesion promoter diffuses and transfers to the coating rubber (C) or the filled rubber (A) after vulcanization, the adhesion promoter remains in a sufficient amount in the coating rubber (B). In addition, while maintaining excellent deterioration adhesion with the steel cord, there is no possibility that the initial adhesion is lowered more than necessary. On the other hand, when it mix | blends exceeding the said upper limit, it is difficult to acquire the remarkable adhesion promotion effect, and there exists a possibility that deterioration adhesiveness may become inadequate while causing a cost increase. In this way, the above-mentioned filled rubber (A) and coated rubber (B) containing the adhesion promoter are in direct contact with the steel cord, rather than in contact with the filled rubber (A) or the coated rubber (B) alone. The bonding area between the cord and the rubber becomes larger, which further contributes to the improvement of corrosion fatigue resistance. Further, coupled with the content of the adhesion promoter in the filled rubber (A), not only the content of the adhesion promoter in the coating rubber (C) but also the content of the adhesion promoter in the filled rubber (A) can be reduced. This can greatly contribute to the improvement of workability.

  Moreover, when mix | blending sulfur with the said coating rubber (B), it is the quantity of 3.0-7.0 mass parts normally with respect to 100 mass parts of said rubber components, Preferably it is the quantity of 5.0-7.0 mass parts. Is desirable. If the amount is not less than the above lower limit, even if sulfur diffuses and transfers to the coating rubber (C) or filled rubber (A) during vulcanization, a sufficient amount of sulfur remains in the coating rubber (B). It is possible to effectively exhibit excellent adhesiveness with the steel cord. On the other hand, when it mix | blends exceeding the said upper limit, there exists a possibility that fatigue fracture resistance may fall. At this time, it is desirable that the content of sulfur in the coating rubber (C) is larger than that in the filled rubber (A). In this case, the progress of vulcanization before vulcanization can be more effectively suppressed, which can contribute to improvement in workability.

<< Second aspect: Coating rubber (C) >>
The coating rubber (C) used in the second embodiment of the present invention is the same as the coating rubber (C) used in the first embodiment. The adhesion promoter and sulfur content in the coating rubber (C) are the same.

[Method for producing rubber-steel cord composite]
First, the rubber-steel cord composite of the present invention is manufactured by a cord manufacturing facility shown in FIG. Such a cord manufacturing facility is provided with a predetermined number of core unwinding portions 9 for unwinding a core portion 9a formed by twisting a plurality of core filaments and sheath unwinding portions 10 for unwinding a sheath filament 10a. There are provided a wire concentrator 11 for converging the filaments unwound from the outlet and a twisting machine 12 for twisting the converging filaments. And between the core unwinding part 9 and the wire concentrator 11, the rubber | gum coating apparatus 13 which coat | covers the unvulcanized filling rubber (A) to the core part 9a is installed.

  Next, in the method of manufacturing a cord with the above-described cord manufacturing facility, first, the core portion 9a wound around the core unwinding portion 9 is unwound and guided to the rubber coating device 13 side. The portion 9a is covered with the filled rubber (A) to form a rubber-coated filament 13a. Next, the rubber-coated filament 13a is supplied to the wire concentrator 11 installed on the entry side of the stranding machine 12, and is unwound from the sheath unwinding portion 10 around the rubber-coated filament 13a by the wire concentrator 11. The sheath filament 10a is converged to form a converging filament 11a, and the converging filament 11a is supplied to the stranding machine 12. After that, the cord 15 is formed by twisting the converging filaments 11 a with the stranded wire machine 12.

  Here, it is desirable that the core portion 9 a unwound from the core unwinding portion 9 is coated with a predetermined amount of filled rubber (A) as described below, and then supplied to the stranding machine 12. That is, by providing a predetermined amount of the filled rubber (A) layer 4, it is possible to prevent the filled rubber (A) from protruding more than necessary from between the sheath filaments constituting the twisted cords, and at an appropriate amount of the core Filling rubber (A) is loaded into the gap between the portions 9a. The predetermined amount in the filled rubber (A) is, in a cross section orthogonal to the axial direction of the cord, the area A of the gap between the core and the sheath and the area B of the filled rubber (A) layer occupied between the core and the sheath, An amount that satisfies the relationship of A ≦ B ≦ 10A.

  The area A of the gap between the core and the sheath is defined with reference to the closed cord. For example, as shown in FIG. 5A, a closed cord having the same structure as that shown in FIG. 1 has an area A {dotted line portion in FIG. 5) as a gap between the core and the sheath in a cross section orthogonal to the axial direction of the closed structure cord. . However, the gap between the sheaths 28 where the core 27 is not interposed is excluded.

  Further, the area B of the filled rubber (A) layer 4 occupying between the core 27 and the sheath 28 is a rubber portion (vertical line portion) covered around the core as shown in FIG. Here, in forming the cord shown in FIG. 1, in order to form the filled rubber (A) layer 4 that is 1 to 10 times the area A, the area B corresponds to the area B as shown in FIG. After covering the core filament with the filled rubber (A), the sheath filament may be twisted together.

  Furthermore, the rubber coating apparatus 13 for covering the core 9a with the filled rubber (A) includes, for example, a rubber extruder 16 and a rubber extrusion head 18 as shown in FIG. Here, as shown in FIG. 6, the rubber coating device 13 has a rubber extrusion screw 17 from the rubber extruder 16 side through the rubber extrusion screw 17 to the rubber extrusion head portion 18, as shown inside the rubber extruder 16 and the rubber extrusion head portion 18. 19 is extruded to fill the rubber extrusion head portion 18 with the filled rubber (A). Next, when the core portion 9a is supplied into the rubber extrusion head portion 18 from the cord guide 20 installed on the entry side of the rubber extrusion head portion 18, and passed through the rubber extrusion head portion 18, the peripheral surface of the core portion 9a. The filled rubber (A) 19 is coated. Thereafter, the core 9a coated with the filled rubber (A) 19 is passed through the base 21 installed on the exit side of the rubber extrusion head 18, and the rubber extrusion head 18 is adjusted while the thickness of the coated rubber (B) is adjusted. It is led out and becomes a filled rubber (A) coated filament 13a.

  In the present invention, when the core portion 9a is coated with the filled rubber (A) by the rubber coating apparatus 13, a plurality of core filaments are coated at the same time. May be.

  Then, if necessary, the coated rubber (B) is coated in the same manner, and the obtained plural cords are arranged in parallel at intervals of 1.5 to 2.0 mm, and the coated rubber (C) is coated from above and below. Then, the rubber-steel cord composite is obtained by cutting into a width and an angle corresponding to a desired portion.

FIG. 7 shows an example of a production facility used particularly when producing a double stranded steel cord. In this cord facility, a core strand unwinding portion 50 for unwinding the core strand 50a is installed, and the unvulcanized filled rubber (A) is cored between the core strand unwinding portion 50 and the sheath strand unwinding portion 55. A rubber coating device 53 including a rubber extruder 51 and a rubber extrusion head unit 52 for coating the strand 50a is installed.
Next, the core strand 50a guided from the rubber extrusion head portion 52 of the rubber coating device 52 is supplied to the sheath strand unwinding portion 55 installed for unwinding the sheath strand 55a on the other side, and the straightening jig 56 is connected to the straightness correcting jig 56. The double twisted cord 57 a is formed while being routed, and the double twisted cord winding portion 57 is transferred. Thereafter, the coated rubber (B) and the coated rubber (C) are coated in the same manner as described above to obtain a rubber-steel cord composite.

[Pneumatic radial tire]
By adopting the rubber-steel cord composite of the present invention as a reinforcing layer for a belt layer, a carcass layer, or a bead portion of a pneumatic radial tire, adhesion durability, aging resistance, and fatigue fracture resistance in the reinforcing layer Thus, a high-performance pneumatic radial tire having excellent durability can be realized while reducing costs.

  In addition, it becomes possible to improve the productivity and handleability of the layer-twisted steel cord and the double-twisted steel cord, and more efficient production of the rubber-steel cord composite and the pneumatic radial tire can be realized.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

[Examples 1 to 10, Comparative Example 1]
A rubber was produced according to the composition shown in Table 2, and a steel cord and a rubber-steel cord composite of the embodiment shown in the schematic diagram of FIG. 3A were produced and evaluated according to the following evaluation contents. As a control example 1 and a comparative example 1, conventional rubber-steel cord composites were prepared by simply coating a steel cord with a coating rubber (C) as shown in the schematic diagram of FIG. The results are shown in Table 3.

<Initial adhesiveness>
The steel cords of 3 + 9 × 0.22 mm shown in FIG. 1 are arranged in parallel at intervals of 2.0 mm, and each rubber composition is coated from the top and bottom of the steel cord, and this is vulcanized at 145 ° C. for 15 minutes to obtain a sample. Produced. The sample was allowed to stand at room temperature for 1 hour, and then the steel cord was pulled out and its rubber coverage was visually evaluated according to the evaluation criteria shown in Table 1.

<Deterioration adhesiveness>
The steel cords of 3 + 9 × 0.22 mm shown in FIG. 1 are arranged in parallel at intervals of 2.0 mm, and each rubber composition is coated from the top and bottom of the steel cord, and this is vulcanized at 145 ° C. for 40 minutes to obtain a sample. Produced. The sample was allowed to stand for 10 days at a temperature of 75 ° C. and a humidity of 90%, and then the steel cord was pulled out, and its rubber coverage was evaluated visually according to the evaluation criteria shown below as in the case of the evaluation of initial adhesion.

<< Evaluation of corrosion fatigue resistance >>
The steel cords of 3 + 9 × 0.22 mm shown in FIG. 1 were arranged in parallel at intervals of 1.5 mm, and each rubber composition was coated from the top and bottom of the steel cord, and vulcanized at 145 ° C. for 40 minutes. Next, a bundle of three steel cords (upper gauge: 1.0 mm, lower gauge: 2.0 mm, total gauge: 3.9 mm, cord pitch: 1.5 mm) was cut out as a sample and immersed in warm water at 70 ° C. for 12 hours. I let you. Thereafter, using the apparatus as shown in FIG. 8, each sample 30 is passed through a pulley 31 (diameter 22 mm), and the sample 30 is driven in the vertical X direction with a cord strength of 7.0% applied. The number of repetitions until rupture of was measured. The obtained results are shown as an index in Table 3 with 100 as the control example and in Tables 4 to 5 with Comparative Example 2 as 100. Higher values indicate higher corrosion fatigue resistance.

<Cost Evaluation>
The cost when producing rubber-steel cord composites of the same size was evaluated on a five-point scale based on numerical values 1 to 5 in ascending order.

According to the results in Table 3, the examples using the filled rubber (A) are superior in adhesion and corrosion fatigue resistance to the comparative example and the comparative example without the filled rubber (A), and cost reduction is also effective. It can be seen that it can be realized.
Especially, according to Examples 4-10, effective cost reduction can be aimed at, maintaining the adhesive performance equivalent to the comparative example 1 even if it does not contain an adhesion promoter in coating rubber (C). it is obvious.

[Examples 11 to 24, Comparative Example 2]
A rubber cord was produced in accordance with the composition shown in Table 4, and the steel cord and rubber-steel cord of the embodiment shown in the schematic diagram of FIG. 3B according to the above evaluation contents, except that each steel cord was arranged in parallel at intervals of 2.0 mm. Composites were made and evaluated. As a comparative example 2, a conventional rubber-steel cord composite in which a steel cord as shown in the schematic diagram of FIG. 3C is only coated with a coating rubber (C) is coated with only a coated rubber (B). Steel cord was made. The results are shown in Tables 4-5.

  * 1 to 4 are the same as in Table 2.

According to the results in Tables 4 to 5, the examples using the filled rubber (A) are superior in adhesion and corrosion fatigue resistance to the control example and the comparative example having no filled rubber (A), and cost reduction is also effective. It can be seen that it can be realized.
In Examples 20 to 24, in which the sulfur content in the filled rubber (A) is less than the sulfur content in the coated rubber (B), the progress of vulcanization before the vulcanization step is effectively suppressed. The workability was very good.

DESCRIPTION OF SYMBOLS 1 Core 1a Core filament 2 Sheath 2a Sheath filament 3a Layer twisted cord 3b Double twisted cord 4 Filled rubber (A) layer 5 Core strand 6 Sheath strand 7 Coating rubber (C) layer 8 Cover rubber (B) layer 9 Core unwinding part 9a Core part 10 Sheath unwinding part 10a Sheath filament 11 Wire concentrator 11a Converging filament 12 Stranding machine 13 Rubber coating device 13a Rubber coating filament 15 Code 16 Rubber extruder 17 Rubber extrusion screw 18 Rubber extrusion head part 19 Filling rubber (A )
20 Code Guide 21 Base 27 Core 28 Sheath 30 Sample 31 Pulley 32 Chuck 50 Core Strand Unwinding Section 50a Core Strand 51 Rubber Extruder 52 Rubber Extrusion Head Section 53 Rubber Coating Device 55 Sheath Strand Unwinding Section 55a Sheath Strand 56 Straight Straightening Jig 57 Double twisted cord winding part 57a Double twisted steel cord

Claims (8)

Around one or a plurality of core filaments or core strands and around the core formed by coating or loading the filler rubber (A) in the gap,
A plurality of sheath filaments or sheath strands are twisted together to form a layer-twisted steel cord or a double-stranded steel cord,
A rubber-steel cord composite obtained by coating the outer surface of the layer-twisted steel cord or the double-twisted steel cord with a coating rubber (C),
A rubber-steel cord composite, wherein the filled rubber (A) contains an adhesion promoter.   The rubber-steel cord composite according to claim 1, wherein the coating rubber (C) contains an adhesion promoter in an amount smaller than the content of the adhesion promoter in the filled rubber (A).   The rubber-steel cord composite according to claim 1, wherein the coating rubber (C) does not contain an adhesion promoter.   The filled rubber (A) and the coating rubber (C) contain sulfur, and the sulfur content in the coating rubber (C) is less than the sulfur content in the filled rubber (A). The rubber-steel cord composite according to any one of claims 1 to 3.   The rubber-steel according to any one of claims 1 to 4, wherein the outer surface of the layer-twisted steel cord or the double-twisted steel cord is coated with the coating rubber (B) in advance and then coated with the coating rubber (C). Code complex.   The rubber-steel cord composite according to claim 5, wherein the coating rubber (B) contains an adhesion promoter in an amount larger than the content of the adhesion promoter in the coating rubber (C).   The rubber-steel cord composite according to claim 5, wherein the coating rubber (B) contains an adhesion promoter in an amount equal to or less than the content of the adhesion promoter in the filled rubber (A).   A pneumatic radial tire having a reinforcing layer made of the rubber-steel cord composite according to claim 1.

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