JPH1161052A - Production of composite metal/rubber article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to improve environmental sanitation and safety and to accomplish improved productivity and reduction in energy cost by applying a water-based adhesive to a chemically converted metal surface at a high temperature directly without a step of leaving it for cooling. SOLUTION: In the production of a composite metal/rubber article comprising bonding a rubber to a chemically converted metal surface with an adhesive, the step of chemical conversion is followed by a step of applying a water-based adhesive to the metallic surface at the temperature raised by the conversion step. The rise in the temperature of the metal surface in the chemical conversion treatment results from washing with hot water and hot-air drying, and desirably the adhesive is applied to the surface when its temperature is 50-100 deg.C. The water-based adhesive is desirably an aqueous emulsion adhesive and is more desirably one prepared by emulsifying a halogenated elastomer, a phenolic resin or an epoxy resin in water. According to this method, the drying time of the adhesive or the energy consumption can be decreased to about 30 to 70% of that required in prior art.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a metal / rubber composite product, and more particularly to a method for producing a metal / rubber composite product using an aqueous adhesive.

[0002]

2. Description of the Related Art In the production of metal / rubber composite products, (a) direct vulcanization bonding in which a metal and an unvulcanized rubber are directly bonded in a vulcanization / molding process without using an adhesive, and (b) non-vulcanization. Indirect bonding is performed by using a vulcanized adhesive, and (c) indirect vulcanized bonding is performed by vulcanizing and bonding using a vulcanized adhesive. Direct vulcanization bonding is used in the manufacture of steel radial tires, etc., but requires brass plating or zinc plating on the metal surface. For this reason, indirect bonding or indirect vulcanization bonding is generally performed.

[0003] Adhesion of metal / rubber with an adhesive has conventionally been carried out.
It has been performed using an adhesive using an organic solvent as a solvent, such as a chlorinated rubber (halogenated rubber) or a phenol resin adhesive. FIG. 1A shows a typical example of a bonding process using an organic solvent-based adhesive. In FIG. 1A, the steps from the cleaning step to the adhesive application step are processing steps performed on the adhered surface (metal surface). The cleaning step is mainly intended to remove stains such as oils and fats, and the polishing step is intended to remove foreign substances and increase the adhesion area and the anchoring effect by roughening the adhered surface. The chemical conversion treatment step is performed for the purpose of improving the affinity of the adherend to the adhesive and the corrosion resistance, and includes sub-steps of forming a chemical conversion film, washing with hot water, and drying with hot air. In the hot air drying, the temperature is set to 100 ° C. or more to shorten the time, and the evaporation rate of water is increased. Immediately after the chemical conversion process, the adherend surface is hot,
If the adhesive is applied as it is, the solvent rapidly evaporates, causing a defect in the adhesive layer or uneven film formation. Therefore, the adhesive is allowed to cool in a dry atmosphere before being introduced into the adhesive applying step. In the adhesive application step, the adhesive is applied and the solvent is evaporated to dry the adhesive layer. After a while
Bonds with rubber to form a metal / rubber composite. In indirect vulcanization bonding, heat vulcanization is performed at or after the bonding step to complete the bonding process.

The bonding process using an organic solvent-based adhesive has a feature that a uniform bonding layer can be formed relatively easily. However, since a large amount of an organic solvent such as a halogenated hydrocarbon is released, work safety can be improved. There are serious problems in terms of environmental impact, occupational health, and environmental impacts such as depletion of the ozone layer. Legislation also tends to restrict the use of organic solvents.
For this reason, conversion to a water-based adhesive has recently been promoted. However, the water-based adhesive has a large latent heat of vaporization of water as a solvent as compared with an organic solvent, so that it takes a long time to dry, and the processing amount per unit time is limited. For this reason,
In the case of using a water-based adhesive using the conventional process, FIG.
As shown in (B), the metal material after the chemical conversion treatment was heated to a temperature of 50%.
It is necessary to maintain the temperature in the constant temperature chamber between 100 ° C and 100 ° C and adjust the metal material temperature to the set temperature to advance the process according to the processing capacity of the coating / drying process. descend. Although it is conceivable to raise the temperature of the drying step in order to shorten the drying time of the adhesive, such a measure causes an increase in energy cost. Also, the adhesive layer may be partially heated or unevenly dried.

[0005]

SUMMARY OF THE INVENTION The present invention aims to improve environmental hygiene and safety by replacing an organic solvent-based adhesive with a water-based adhesive in the production of a metal / rubber composite product. It is an object of the present invention to provide a safe and efficient method for producing a metal / rubber composite product by solving the problems of a decrease in productivity per unit time and an increase in energy cost, which have been problems when using an aqueous adhesive. Aim.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have directly connected a chemical conversion treatment step on an adherend surface and an adhesive application step which have been conventionally separated by a cooling step or the like. As a result, the inventors have found that the efficiency of the bonding process between metal and rubber can be improved, and have completed the present invention.

That is, the present invention provides the following method for producing a metal / rubber composite product. (1) In a method for producing a metal / rubber composite product in which rubber is adhered to a metal surface subjected to a chemical conversion treatment using an adhesive, an aqueous adhesive is applied to the metal surface whose temperature has been increased by the chemical treatment step following the chemical conversion treatment step. A method for producing a metal / rubber composite product. (2) The method for producing a metal / rubber composite product according to the above (1), wherein the aqueous adhesive is applied while the metal surface temperature is raised to 50 to 100 ° C. (3) The method for producing a metal / rubber composite product according to (2) above, wherein the temperature rise on the metal surface in the chemical conversion treatment step is caused by hot water washing. (4) The method for producing a metal / rubber composite product as described in (2) above, wherein the temperature rise on the metal surface in the chemical conversion treatment step is due to hot water washing and hot air drying. (5) The method for producing a metal / rubber composite product according to any one of (1) to (4) above, wherein the aqueous adhesive is an aqueous emulsion adhesive. (6) The method for producing a metal / rubber composite product as described in (5) above, wherein the aqueous emulsion adhesive is obtained by emulsifying a halogenated elastomer, a phenol resin or an epoxy resin in water.

[0008]

DETAILED DESCRIPTION OF THE INVENTION FIG.
The method for producing a rubber composite product is described. Hereinafter, each step will be described. (I) Cleaning Step The cleaning step in the present invention aims at removing stains such as oils and fats on the adhered surface (metal surface) as in the conventional method.
The cleaning may be performed in the same manner as in the known metal / rubber composite method. For example, an organic solvent such as acetone, hydrocarbon, or isopropyl alcohol, or a water-soluble cleaning agent such as an alkaline aqueous solution or a surfactant is used as a cleaning agent to remove oils and fats such as oil and grease. The water-soluble cleaning agent also has an effect of removing ionic impurities on the adhered surface. In the case of an organic solvent, degreasing with steam may be performed. A known method can be used for the washing method. For example, immersion, stirring, ultrasonic cleaning, spraying of a cleaning liquid, wiping with a cloth or the like can be used. These methods may be combined. After the washing, it is washed with a water-soluble cleaning agent, and further washed with hot water and dried with hot air. In the case of an organic solvent, hot air drying is performed directly after washing.

(II) Polishing Step As described above, in the polishing step, the adhering material on the adhered surface which could not be removed in the cleaning step is removed, and the surface area is appropriately roughened so that the bonding area and the bonding area can be reduced. It is intended to increase the anchoring effect, but it is not always necessary if the deposit on the surface to be adhered can be removed in the cleaning step. This step may be performed similarly to the polishing step in the conventional metal / rubber composite method. Examples of the means used for polishing include sandpaper (80-320 abrasive paper), buff, belt sander,
Sand blast, shot blast, grid blast, wire brush, high-pressure liquid, and the like. Any of them may be used, but a blast method in which inorganic powder or granules are blasted at high speed is preferable. As the abrasive used,
Examples include steel, alumina, green carbon random, silica, glass, ice and the like. Polishing is generally performed in the air, but blasting in a liquid such as an alkaline cleaning liquid is also effective.

(III) Chemical conversion treatment step In the chemical conversion treatment step, (a) formation of a chemical conversion film, (b) washing with hot water and hot-air drying are performed. In this step, a coating composed of an oxide, a phosphate, a chromate, a composite oxide, or the like is formed on the metal surface. For example, a stainless steel material is immersed in a solution in which an oxidizing agent such as oxalic acid or hydrogen peroxide is added together with an acid, and is treated at a temperature of room temperature to about 60 ° C. for several minutes to several tens of minutes.

The phosphating is mainly performed on steel. For example, steel is immersed in a mixed aqueous solution of zinc monophosphate, orthophosphoric acid, nitric acid and chloric acid as an oxidizing agent at 40 to 60 ° C. for about 5 minutes. Hopite
_{peite: Zn 3 (PO 4)} 2 · 4H 2 O) or phosphophyllite _{(Phosphophyllite: Zn 2 Fe (PO} 4) 2 · 4H 2
O) and the like, and further mixed with monocalcium phosphate, Scholzite Zn ₂
A coating such as Ca (PO ₄ ) ₂ .2H ₂ O) is formed. The chromic acid treatment is mainly performed on an aluminum alloy or a titanium alloy. A composite layer of chromic acid, chromium hydroxide and metal hydroxide is formed. For aluminum alloys, phosphoric acid / chromic acid treatment is also known, and a complex hydrous salt of aluminum oxide and chromium phosphate is formed. Various other methods are known, such as forming a composite oxide film of cobalt and chromium on a galvanized steel material. In the present invention, the type of the chemical conversion treatment is not particularly limited, but it is possible to suitably carry out the phosphating treatment on steel that is a general-purpose metal and has excellent rust prevention and adhesive-peeling prevention properties in a salt-damage environment.

[0012] To remove the chemicals used in the hot water washing and hot air drying conversion film formation, after the film formation, water washing is carried out, and in order to remove moisture, hot water washing and hot air drying are carried out. The processing temperature and the holding time will be described in the next section.

(IV) Temperature Control of Adhesive Coating Process In the conventional method for producing a metal / rubber composite product, after forming a chemical conversion coating, the adherend is allowed to cool down once, and is adjusted according to the processing capacity of the adhesive drying process. Although guided to the adhesive application step, in the present invention, the adherend is directly introduced to the adhesive application step after the chemical conversion treatment step. By adopting such a configuration, fixing of the aqueous adhesive proceeds rapidly, and energy efficiency is remarkably improved. The temperature at the time of introduction into the adhesive application step is preferably 50 to 100 ° C, more preferably 70 to 90 ° C. If the temperature is too low, drying and fixing of the aqueous adhesive do not proceed rapidly. If the temperature is too high, moisture evaporation can occur rapidly, causing defects in the adhesive layer or causing partial heating of the adhesive layer. The above temperature can be controlled by adjusting the temperature and heating time of hot water washing, steam bath or hot air drying in the above-mentioned chemical conversion treatment step. In the case of the conventional organic solvent-based adhesive, if moisture remains on the surface to be adhered, there is a problem that the adhesion of the adhesive to the portion is reduced and the adhesive layer becomes uneven. Since an aqueous adhesive is used in the invention, a small amount of water does not affect the adhesive application.

Application method The application of the adhesive is performed according to a conventional method. For example, a dipping method, a spraying method using a flow gun or a spray gun,
A coating method using a roller, a blade, or the like, or another coating method using a brush or the like can be used. The coating thickness is usually 5
About 20 μm (at the time of drying).

[0015] type of water-based adhesives used in the adhesive present invention is not particularly limited, less organic solvent aqueous emulsion adhesives are preferred. One-pack type or two-pack type may be used. The aqueous emulsion adhesive is an adhesive obtained by emulsifying a polymer component using a surfactant. In rubber-metal bonding,
An adhesive containing a halogenated elastomer, a phenol resin, an epoxy resin, or the like as a polymer component is particularly useful. Examples of the halogenated elastomer include chlorinated rubber, chlorosulfonated polyethylene, and brominated chlorinated polybutadiene. The phenolic resin includes novolak type, resol type and various modified phenolic resins. The polymer component is usually one of the basic components in the adhesive.
0 to 70% by weight. If it is less than 10% by weight, a sufficient adhesive effect cannot be obtained. Even if it is used in an amount exceeding 70% by weight, a sufficient effect cannot be obtained by cooperation with other components. In addition,
Here, the basic component means the entire solid content excluding solvent components such as water and cellosolve.

The adhesive includes various auxiliary components, fillers, thickeners,
It may contain a crosslinking agent and other additives / subcomponents.
Examples of fillers include calcium carbonate, siegrite,
Silica, kaolin clay, barium sulfate and the like. Examples of the thickener include polyacrylic acid, silica, bentonite and the like. Examples of crosslinking agents include polyvalent metal salts, polyisocyanate compounds, polyepoxy compounds,
Examples include polyamide compounds and nitroso compounds. Examples of subcomponents include metal oxides such as titanium oxide, lead oxide, and zinc oxide, carbon black, polyimide compounds, isocyanates, and the like.

The solids content is usually about 10 to 70% by weight, preferably about 30 to 50% by weight. 10% by weight
If it is less than 3, the liquid may be dripped when the adhesive is applied, or a sufficient thickness may not be obtained. Alternatively, a sufficient adhesive effect cannot be obtained, and it takes a long time to dry the adhesive. 70
If the content is more than 10% by weight, the emulsion is not stable. In addition, a commercial item can be used for such an adhesive.
For example, Lord Corporatio
n) and primers including Chemlock 805, Megam 23500 or cover coats including Chemlock 8200 and Megam 23800, sold by Chemmetall GmbH, etc. An aqueous adhesive used as a material is exemplified.

The dried adhesive is dried prior to bonding with rubber to remove the solvent (moisture). Various drying methods are known, and any of them may be used. For example, hot air drying, drying with an electric or infrared heater, etc. are useful. According to the method of the present invention, since the surface to be adhered has a temperature of 50 ° C. or more in advance, the drying time or the energy input can be reduced to about 30 to 70% of the conventional method.

(V) Adhesion Step A rubber is brought into contact with the adhered surface having undergone the above treatment, and the pressure and / or
Alternatively, the bonding step is completed by heating. The pressure is usually
It is about 5 to 30 MPa, and is heated to about 140 to 200 ° C. Hold for about 3 minutes to 1 hour. When an unvulcanized rubber is used, the above-described step is performed, for example, by injection molding a semi-molten rubber on the surface to be adhered. Pressure molding and transfer molding may be used. The types of rubber and metal that can be composited according to the present invention are not particularly limited. Examples of rubber materials include natural rubber (NR), polychloroprene (CR), polybutadiene (BR), and butyl rubber (II
R), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), ethylene propylene rubber (EPM, EPDM) and the like. Examples of the metal material include ordinary structural metals such as iron, steel (including stainless steel), lead, aluminum, copper, brass, nickel, and zinc.

[0020]

The present invention will be specifically described below with reference to Examples, Reference Examples and Comparative Examples. In the following Examples and Comparative Examples, the following adhesives were used. Test Adhesive (1) Aqueous Adhesive (Example) Chemlock 8007 and Chemlock 8200 manufactured by Road Corporation were used. This is a two-part aqueous vulcanizing adhesive, where the first part contains mainly phenolic resins and the second part contains mainly halogenated elastomers. (2) Organic solvent-based adhesive (Reference Example) Chemlock 205 and Chemlock 220 manufactured by Road Corporation were used. The first liquid contains a phenol resin, and the second liquid contains a chlorinated rubber as a main component.

Adhesion evaluation method The adhesion was evaluated according to JIS K6301 by using a φ3
Steel (SS4) having a flat part (adhered surface) of 5 mm
1) The rubber 3 was compounded between the metal fitting pair (1, 2), pulled in the direction of the arrow in the figure at a pulling speed of 100 mm / min, and observed by observing the tensile strength at the time of breaking and the state of breaking.
The rupture state is evaluated by observing the rate of occurrence of rupture at each site. For example, "R100" indicates that the rupture has progressed within the 100% rubber layer. "Rm, Mn" is the m of fracture
% Indicates that progress has occurred in the rubber layer, and n% has progressed at the interface between the rubber layer and the metal layer. In “RmCPn”, m% of the fracture is in the rubber layer, and n% is the lower layer (first liquid) and the upper layer (second liquid) of the adhesive layer.
This indicates that the process has progressed at the interface with.

EXAMPLE 1 A pair of steel metal fittings shown in FIG. 2 was immersed in a 5 wt% aqueous solution of sodium silicate complex at 60 ° C. to perform degreasing.
Washed and dried. The adhered surface was blasted with steel grit (average particle size: 0.7 mm).

[0023]

[Table 1]

Next, the surface to be adhered was immersed in a chemical conversion treatment solution having the composition shown in Table 1, held for 5 minutes, pulled up from the solution and washed with water, and then washed with hot water of 80 ° C. for 2 minutes. Then, it was dried with hot air of 90 ° C. for 2 minutes. Subsequently, the first liquid of the aqueous adhesive is spray-coated on the surface to be adhered, and the chemical liquid is dried by holding the liquid in a thermostatic dryer at 60 ° C. for 3 minutes, and then the second liquid is similarly spray-coated, Also 6
The solution was kept in a constant temperature dryer at 0 ° C. for 3 minutes to dry the drug solution. The thickness of the adhesive layer after drying was about 15 μm. Thereafter, a natural rubber compound having a JIS hardness of 60 is transfer-molded on the above-mentioned surface to be adhered, and is subjected to 1 hour at 150 ° C for 30 minutes.
The mixture was vulcanized and adhered while maintaining the pressure at 5 MPa (rubber layer thickness: 15 mm). When the obtained test piece was evaluated by the above-described breaking test, the breaking tensile strength was 9.8 MPa, and the breaking occurred (R100) in the 100% rubber layer.

REFERENCE EXAMPLES 1-2 After washing with hot water and hot air drying at the final stage of the chemical conversion treatment step, the adherend was held in a drying vessel and allowed to cool to about 20 ° C. A test piece (Reference Example 1) was prepared in the same manner as in Example 1 except that the organic solvent-based adhesive was applied, and a breaking test was performed. The breaking tensile strength was 9.9 MPa, and the breaking occurred in the 100% rubber layer. In addition, when the hot water washing and hot air drying were not performed in Reference Example 1 (Reference Example 2), the tensile strength at break was 5.
The pressure dropped to 7 MPa, and 10% of the fracture occurred at the interface between the rubber layer and the metal. From the results of Example 1 and Reference Example 1, it can be seen that according to the method of the present invention, the same adhesive performance as that of the conventional adhesive process using an organic solvent-based adhesive can be realized. In addition, from the results of Reference Example 2, it was confirmed that it was essential to remove moisture from the surface of the metal fitting by drying with the organic solvent-based adhesive.

Examples 2 and 3, Comparative Example 1 A test piece was prepared in exactly the same manner as in Example 1 except that the hot water washing temperature and the air drying temperature were changed as shown in Table 2, and a breaking test was performed.

[0027]

[Table 2]

From the results of Examples 2 and 3, it can be seen that according to the method of the present invention, good adhesion can be achieved only by washing with hot water without performing hot air drying. However, if the hot water washing temperature is too low, the effect is reduced (Comparative Example 1).

Comparative Example 2 After washing with hot water and hot air drying under the same conditions as in Example 1, the adherend was allowed to cool to about 20 ° C. in a drying vessel. Thereafter, a plurality of test pieces were prepared in the same manner as in Example 1 except that the drying time after the application of the first liquid was changed, and the breaking strength of each test piece was measured. As a result, the drying time to reach the same level of adhesive strength as that of the present invention was 6 minutes. According to the present invention, it was confirmed that the time required for drying the adhesive can be significantly reduced and the energy efficiency was improved. did it.

[0030]

According to the method for producing a metal / rubber composite product of the present invention, the chemical conversion treatment step and the adhesive application step are continuously performed, thereby increasing the energy cost, which has conventionally been a problem with water-based adhesives. To eliminate. As a result, there is no danger of fire, it is excellent in terms of occupational environment and sanitation, and it does not harm the global environment because it does not emit ozone depleting substances. The present invention also provides a method of manufacturing an excellent metal / rubber composite product. Further, in the conventional method, there is a possibility that a contaminant adheres to the adherend surface during the application of the adhesive after the chemical conversion treatment. However, the method of the present invention solves such a problem.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a bonding process according to a conventional method and the present invention.

FIG. 2 is a cross-sectional view schematically showing a test piece used for an adhesion test.

[Explanation of symbols]

 1, 2 metal material (substrate) 3 rubber layer

Claims (6)

[Claims] 1. A method for producing a metal / rubber composite product in which rubber is bonded to a metal surface subjected to a chemical conversion treatment by using an adhesive. A method for producing a metal / rubber composite product, characterized by applying a compound. 2. The method for producing a metal / rubber composite product according to claim 1, wherein the aqueous adhesive is applied while the metal surface temperature is raised to 50 to 100 ° C. 3. The method for producing a metal / rubber composite product according to claim 2, wherein the temperature rise on the metal surface in the chemical conversion treatment step is caused by washing with hot water. 4. The method for producing a metal / rubber composite product according to claim 2, wherein the temperature rise on the metal surface in the chemical conversion treatment step is caused by hot water washing and hot air drying. 5. The method for producing a metal / rubber composite product according to claim 1, wherein the aqueous adhesive is an aqueous emulsion adhesive. 6. The metal / emulsion according to claim 5, wherein the aqueous emulsion adhesive is obtained by emulsifying a halogenated elastomer, a phenol resin or an epoxy resin in water.
Manufacturing method of rubber composite products.