JPH1121389A - Method for bonding galvanized steel cord to rubber and conveyer belt made by using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bonding method excellent in moisture-resistant adhesion and initial adhesion between a galvanized steel cord and a rubber, by using a rubber composition containing a sulfur-vulcanizable rubber, a rosin or its derivative, an organocobalt salt, and an organic chlorine compound as an adhesive composition. SOLUTION: The rubber composition serving as a composition for bonding to a galvanized steel cord is obtained by mixing 100 pts.wt. sulfur-vulcanizable rubber, 3-15 pts.wt. rosin or derivative thereof, 0.2-1.0 pt.wt., in terms of cobalt, organocobalt salt, and 3-50 pts.wt. organic chlorine compound. This rubber composition is used for bonding a galvanized steel cord to a rubber. For example of practical use, a galvanized steel cord 2 installed as a core is coated with this composition to form a coating rubber layer 4, and a covering rubber layer 6 is provided of the surface thereof, thus forming a steel cord conveyer belt 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of bonding a galvanized steel cord and rubber using a rubber composition having excellent adhesion to a galvanized metal material, and a conveyor using the bonding method. About the belt.

[0002]

2. Description of the Related Art Conventionally, galvanized steel cord has been used as a reinforcing material for a rubber composition, and is superior in rust prevention as compared with brass-plated steel cord and the like. It is used as a reinforcing material for steel cord conveyor belts used in the environment, for example, in pits, and has been bonded to rubber compositions by various methods. As a method of bonding both, for example, JP-A-57-70138 discloses a method of blending a rubber composition with a resorcinol-formaldehyde resin, sulfur, a cobalt salt of an organic acid, etc., and bonding the rubber composition to a galvanized steel cord. Are described. However, this method has a problem that the rubber composition does not have sufficient water-resistant adhesiveness to the galvanized steel cord, and requires a cost and labor for maintenance such as inspection and repair for ensuring the reliability of the adhesiveness. was there.

On the other hand, JP-A-56-32530 describes a method in which a rosin acid derivative resin and a cobalt salt are blended in a rubber composition to improve the adhesion to a galvanized steel cord. However, this method has a problem that the adhesiveness immediately after vulcanizing and joining the galvanized steel cord and the rubber composition (hereinafter referred to as initial adhesiveness) is not sufficient.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of bonding a galvanized steel cord to rubber using a rubber composition having excellent moisture resistance and initial adhesion to a galvanized steel cord, and An object of the present invention is to provide a steel cord conveyor belt manufactured using the bonding method.

[0005]

That is, according to the present invention, 3 to 15 parts by weight of rosin or a rosin derivative and 0.2 parts by weight of an organic cobalt salt relative to 100 parts by weight of a sulfur-vulcanizable rubber are used. A method of bonding a galvanized steel cord and rubber, comprising bonding a rubber composition containing 1.0 to 1.0 part by weight, and an organic chlorine compound at 3 to 50 parts by weight, and a galvanized steel cord. provide.

Further, the present invention is a conveyor belt in which a steel cord covered with a coat rubber layer is provided as a core between cover rubber layers, wherein the coat rubber layer comprises:
3 to 15 parts by weight of rosin or a rosin derivative, 0.2 to 1.0 parts by weight of an organic cobalt salt in terms of cobalt, and 3 to 50 parts by weight of an organic chlorine compound, relative to 100 parts by weight of the sulfur vulcanizable rubber. The present invention provides a conveyor belt which is a rubber composition containing:

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The method of bonding a galvanized steel cord and rubber of the present invention (hereinafter, referred to as the bonding method of the present invention) is a rubber composition having excellent adhesion to a galvanized steel cord, which is obtained by adding a rosin or A rubber composition containing a rosin derivative, an organic cobalt salt, and an organic chlorine compound (hereinafter, also referred to as a rubber composition of the present invention) is used.

[0008] In the present invention, a sulfur vulcanizable rubber is used as the rubber. At the time of vulcanization, it is not preferable to use a rubber that is vulcanized with, for example, a peroxide other than sulfur, because the adhesiveness to a galvanized steel cord described later is not improved. The sulfur vulcanizable rubber used in the present invention is:
There is no particular limitation as long as the rubber can be vulcanized using sulfur,
Natural rubber or synthetic rubber may be used. Also,
These mixtures may be used. Specifically, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR)
And the like can be used alone or as a mixture.

The rosin used in the present invention is a kind of natural resin also referred to as rosin, and the rosin derivatives include wood rosin extracted from pine wood with a solvent, tall oil rosin, hydrogenated rosin and its processing. Goods and the like. In the present invention, rosin esters are not used as rosin derivatives because they are inferior in imparting tackiness. The content of rosin or a rosin derivative in the rubber composition of the present invention is 3 to 15 parts by weight based on 100 parts by weight of the sulfur-vulcanizable rubber. If the amount is less than 3 parts by weight, the moisture resistance between the rubber composition and the galvanized steel cord is not sufficient. If the amount is more than 15 parts by weight, the vulcanization of the rubber composition is slow and a practical vulcanization rate cannot be obtained. Because. In particular, the content of rosin or a rosin derivative is preferably from 5 to 10 parts by weight from the viewpoint of achieving both moisture resistance and practical vulcanization rate.
Since the rubber composition of the present invention contains rosin or a rosin derivative, it has the property of being excellent in moisture-resistant adhesion to galvanized steel cord. In addition, rosin and rosin derivatives are generally used as a tackifier,
By containing rosin or a rosin derivative, the rubber composition of the present invention has good adhesiveness and processability of the uncured rubber composition.

The organic cobalt salt used in the present invention is generally used as a liquid phase oxidation catalyst. A method of adding a cobalt acetate solution to an aqueous alkali soap solution of a corresponding organic acid to cause double decomposition precipitation, an organic acid and a cobalt oxide (II)
And a method of adding an aqueous solution of cobalt sulfate or cobalt nitrate to a benzine solution of an organic acid. Specific examples of the organic cobalt salt used in the present invention include cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt orthoborate, cobalt octylate, and cobalt boron complex. Among them, it is preferable to use cobalt naphthenate, cobalt neodecanoate, cobalt boron complex or the like because high adhesiveness can be obtained. The content of the organic cobalt salt is set to 0.2 to 1.0 part by weight as a cobalt amount based on 100 parts by weight of the sulfur-vulcanizable rubber. If the amount is less than 0.2 part by weight, the moisture resistance and initial adhesion to the galvanized steel cord deteriorate, and if it exceeds 1.0 part by weight, the aging resistance of the rubber composition deteriorates. In particular, the content of the organic cobalt salt is preferably 0.3 to 0.7 parts by weight from the viewpoint of achieving both moisture resistance and initial adhesion and rubber properties.

As the organic chlorine compound used in the present invention, an organic chlorine compound generally used as a chlorine-based flame retardant can be used. In the present invention, among these, a linear organic chlorine compound is used. Such compounds include, for example, chlorinated paraffin, chlorinated polyethylene and the like. As these compounds, commercially available products can be used. For example, in the case of chlorinated paraffin, the chlorine content is 40%.
%, 45%, 50%, 65%, 70% are commercially available, and all of them can be used. The content of the organic chlorine compound is based on 100 parts by weight of the sulfur-vulcanizable rubber.
3 to 50 parts by weight. If the amount is less than 3 parts by weight, the adhesion will not be stable, and if it exceeds 50 parts by weight, the tackiness of the rubber composition will be excessive and processing will be difficult. In particular, the content of the organic chlorine compound is preferably from 3 to 30 parts by weight from the viewpoint of achieving both the adhesion and the workability. When the rubber composition of the present invention contains an organic chlorine compound, the adhesiveness, particularly the initial adhesiveness, is improved. Further, since the organochlorine compound imparts flame retardancy, the rubber composition of the present invention containing the organochlorine compound in an amount in the above range is excellent in flame retardancy. For this reason,
A steel cord conveyor belt manufactured by using the bonding method of the present invention described later sufficiently satisfies the flame retardancy required for a steel cord conveyor belt used in a pit or the like. When importance is placed on the flame-retarding effect, it is preferable to use one having a large chlorine content, and when importance is placed on workability, it is preferable to use one having a small chlorine content.

The rubber composition used in the bonding method of the present invention may be a phenol resin, a carboxyl group-containing liquid isoprene rubber (an isoprene produced by a solution polymerization method) in addition to the above essential components, as long as the object of the present invention is not impaired. (In which a carboxyl group is introduced into a polymer rubber) or the like. In addition, a filler such as carbon black; a vulcanization accelerator such as zinc white and stearic acid; a vulcanization accelerator such as dibenzothiazyl disulfide; an amine-based compound;
A phenolic or wax-based antioxidant; sulfur; a vegetable oil-based or mineral oil-based softening agent; and other commonly used compounding agents can be included.

The rubber composition used in the bonding method of the present invention is produced as follows. A rosin or a rosin derivative is added to 100 parts by weight of the above-mentioned sulfur vulcanizable rubber.
To 15 parts by weight, 0.2 to 1.0 parts by weight of an organic acid cobalt salt as a cobalt amount, 3 to 50 parts by weight of an organic chlorine compound, and a predetermined amount of sulfur, and further the above-mentioned filler and vulcanization accelerator , An anti-aging agent, a softening agent and the like are appropriately selected and added in a predetermined amount, and are kneaded at a predetermined temperature for a predetermined time using a roll mill or Banbury mixer to obtain a rubber composition.

The rubber composition used in the bonding method of the present invention is brought into close contact with a galvanized steel cord described below, and sulfur-vulcanized at a predetermined temperature for a predetermined time to form a rubber and a galvanized steel cord. Can be obtained.

As the steel cord to be adhered to the above-mentioned rubber composition by the adhesion method of the present invention, a steel cord whose surface is not treated is galvanized. As a plating method, electroplating, hot-dip plating, and the like are possible. Some steel cords are brass-plated, but they are galvanized from the perspective of rust resistance and durability as steel cords used for conveyor belts, etc., where use environment management is difficult and durability is required. Use something. The element wire diameter and the cord diameter of the galvanized steel cord are appropriately selected according to the use of the rubber composition of the present invention when bonded to form a composite.

In the bonding method of the present invention, the rubber composition of the present invention is brought into close contact with a galvanized steel cord at a predetermined thickness, and is subjected to batch vulcanization at 150 ° C. for 30 hours to obtain a rubber composition of the present invention. Complex with galvanized steel cord. The bonding method of the present invention is bonding with a galvanized steel cord, and can be used for those using a galvanized steel cord as a reinforcing material, and can be used for not only a steel cord but also a galvanized metal material. It is.

Since the bonding method of the present invention has the above-described structure, the moisture-resistant adhesiveness is greatly improved and the initial adhesiveness is also good as compared with the conventional method of bonding galvanized steel cord and rubber. . For this reason, if the bonding method of the present invention is used for a steel cord conveyor belt that is used in a humid environment, extremely long-term reliability can be obtained, and maintenance costs and labor such as inspection and repair can be reduced. Bring effect. Such a bonding method of the present invention is suitably used for the production of a steel cord conveyor belt, but can also be suitably used for the production of hoses, crawler belts, marine hoses, tires and the like.

Next, a steel cord conveyor belt manufactured by using the bonding method of the present invention will be described. FIG. 1 shows a steel cord conveyor belt of the present invention (hereinafter, referred to as a steel cord conveyor belt).
FIG. 2 is a partial cross-sectional perspective view of a conveyor belt according to the present invention). The surface layer of the conveyor belt 1 is composed of a cover rubber layer 6 and two layers, and a coated rubber layer 4 having a galvanized steel cord 2 as a core between the two layers of the cover rubber layer 6.
There is. The conveyor belt 1 of the present invention has a coating rubber layer 4
The present invention is characterized in that the steel cord 2 provided in the above and the rubber composition of the present invention forming the coat rubber layer 4 are bonded by the bonding method of the present invention. After the rubber composition of the present invention is formed into a desired shape on the coated rubber layer 4, the galvanized steel cord 2 is provided as a core and vulcanized. The rubber composition and the galvanized steel cord 2 surface are firmly joined,
It becomes the coat rubber layer 4. The coating rubber layer 4 serves as an adhesive layer between the galvanized steel cord 2 and the cover rubber 6, and also serves as a buffer for the galvanized steel cord 2. The cover rubber layer 6 may be made of a rubber composition containing a component having excellent heat resistance, oil resistance, abrasion resistance, or weather resistance, depending on the use of the conveyor belt 1. Since the steel cord conveyor belt of the present invention has the above configuration, it has excellent water resistance, adhesion to galvanized steel cord, durability, and long-term reliability.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. (Examples 1 to 4, Comparative Examples 1 to 7) The compounds shown in the following Table 1 were blended in the amounts shown in the table, and kneaded using a Banbury mixer to obtain a rubber composition.

The rubber compositions obtained in Examples and Comparative Examples,
A test piece was prepared by vulcanization bonding with a galvanized steel cord by the following method, and the initial adhesion and the water resistance were measured and evaluated by the following method. (1) Preparation of test piece As a steel cord to be bonded to the rubber composition obtained in each of Examples and Comparative Examples, a galvanized steel cord having a diameter of 4.1 mm, which is stored in a desiccator and subjected to dustproof and moistureproof treatment, was used. used. On this steel cord, the rubber compositions of the above Examples and Comparative Examples were brought into close contact with each other to a thickness of 15 mm to form a composite of each of the above rubber compositions and a steel cord. Pressure vulcanization was performed to produce a test piece.

(2) Initial Adhesion The initial adhesion was evaluated by extracting a steel cord from each test piece prepared in (1) and examining the pulling force (kN / m) and the rubber coverage (%). Pull-out test is DIN221
31. The rubber coverage (%) was calculated as the ratio (%) of the rubber coating area remaining on the surface of the steel cord after drawing to the surface area of the steel cord. Table 1 shows the results.

(3) Water-Resistant Adhesion A portion of the rubber surface of each test piece closely adhered and vulcanized by the production method of (1) is sealed with a beeswax at a portion where the steel cord projects, and the temperature is 50 ° C. and the relative humidity is 95 % In a constant temperature / humidity bath for 28 days. Thereafter, the steel cord was pulled out from each test piece, and the water-resistant adhesiveness was evaluated based on the pulling force (kN / m) and the rubber coverage (%). Pull test is D
Performed according to IN22131. Table 1 shows the results.

[0023]

[Table 1]

[0024]

The compounds shown in Table 1 are as follows. Natural rubber (NR): TSR 20 Synthetic rubber (SBR): NIPOL 1502 (manufactured by Zeon Corporation) Filler: HAF carbon black Vulcanization accelerator: Zinc Hua No. 3 Stearic acid Vulcanization accelerator (dibenzothiazyl disulfide) ): Noxeller DM-PO (Ouchi Shinko Chemical Co., Ltd.) Antioxidant: Nonflex OD-3 (Seiko Chemical Co., Ltd.) Vulcanizing agent: Sulfur Rosin derivative: Wood rosin (Arakawa Chemical Co., Ltd.) Tall oil rosin (Harima Hydrogenated rosin (manufactured by Hercules) Organic cobalt salt: cobalt naphthenate (cobalt content: 10%, manufactured by Dainippon Ink) Organic chlorine compound: chlorinated paraffin (chlorine content: 70%, manufactured by Ajinomoto Co.) )

[0026]

According to the bonding method of the present invention, a rubber composition containing a specific compound in a specific amount is used for bonding to a galvanized steel cord. It is possible to obtain a composite of a rubber composition having excellent moisture resistance (water resistance) adhesion and initial adhesion and a galvanized steel cord, which cannot be obtained by the method. Therefore, a steel cord conveyor belt or the like manufactured by using the bonding method of the present invention has high reliability over a long period of time, and maintenance costs and labor are reduced. Further, the steel cord conveyor belt of the present invention obtained by using such an adhesion method has excellent durability and water resistance.

[Brief description of the drawings]

FIG. 1 is a sectional view of a steel cord conveyor belt of the present invention.

[Explanation of symbols]

 1 Steel Cord Conveyor Belt 2 Galvanized Steel Cord 4 Coated Rubber Layer 6 Cover Rubber Layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 93:04)

Claims (2)

[Claims] 1 to 3 parts by weight of a rosin or a rosin derivative, 0.2 to 1.0 parts by weight of an organic cobalt salt in terms of cobalt amount, and 100 parts by weight of a sulfur vulcanizable rubber. A method of bonding galvanized steel cord and rubber, comprising bonding a rubber composition containing 3 to 50 parts by weight of a compound to a galvanized steel cord. 2. A conveyor belt provided between a cover rubber layer and a core of a galvanized steel cord covered with a coat rubber layer, wherein the coat rubber layer is based on 100 parts by weight of sulfur-vulcanizable rubber. A rubber composition containing 3 to 15 parts by weight of rosin or a rosin derivative, 0.2 to 1.0 part by weight of an organic cobalt salt in terms of cobalt, and 3 to 50 parts by weight of an organic chlorine compound. Conveyor belt.