JPS5912847A - Manufacture of laminate of polyolefin having excellent brine resisting property and metal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a laminate of polyolefin and metal with excellent salt water resistance.In recent years, polyethylene, which has excellent chemical stability from the viewpoint of environmental hygiene, has been used for coating metals, particularly for coating steel pipes. Coatings using polyolefin resins such as , polypropylene, and polybutene have been implemented.
However, polyolefin resins are non-polar in their chemical structure, so in order to improve their adhesion to highly polar metal surfaces such as steel pipe surfaces, a modified mixture of polyolefins is inserted in the middle. . However, if immersed in solutions containing electrolytes such as seawater or saline, the adhesive strength will be low and rust will occur. Regarding the curing conditions of this epoxy resin adhesive, f! 4
Because the curing conditions for the epoxy resin adhesive were not certain because the judgment was based only on the adhesive strength of the layers, the work was often done empirically, and the epoxy resin adhesive was determined from the viewpoint of durability such as salt water resistance. The curing conditions for the agent had not been determined. In other words, because the curing conditions of the adhesive are not constant,
Do not over-cure the adhesive and lose thermal energy;
Insufficient curing resulted in defective products with low adhesive strength, and there were many variations in quality between laminates.

The present invention was made in view of the above circumstances, and provides a method for firmly adhering polyolefin to metal using an epoxy resin composition containing a curing agent as an adhesive, and particularly improves salt water resistance of a laminate of polyolefin and metal. The gist of the present invention is to fuse a polyolefin modified with an unsaturated carboxylic acid or its anhydride with a metal to form a laminated layer of polyolefin and gold 4. When manufacturing the body, a liquid epoxy resin composition containing a hardening agent is applied onto the metal phase, and after it solidifies, it becomes a gel and becomes a cured resin that exhibits a certain glass transition temperature. The purpose is to laminate and fuse a modified polyolefin heated to a temperature above its melting point on top of an epoxy resin composition.

The present invention will be explained in more detail below.

The present invention involves fusing modified polyolefin and metal.
When producing a laminate of J-olefin and metal, an epoxy resin composition containing a curing agent is applied onto the metal phase, and after it solidifies, it becomes a gel and becomes a cured resin that exhibits a certain glass transition temperature. During this process, modified polyethylene is fused onto the epoxy resin composition at a temperature higher than the melting point of the modified polyethylene.

The modified polyolefin used in the present invention is a polyolefin modified with an unsaturated carboxylic acid, its anhydride, or a derivative thereof.

Polyolefins used in the production of such modified polyolefins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, poly-1-butene, and ethylene-7''.

Typical examples include pyrene copolymer, ethylene-1-butene copolymer, pyrene-1-butene copolymer, and mixtures thereof. Also, unsaturated carboxylic acid or its anhydride used for modification of modified polyolefin. as,
Acrylic acid, meccrylic acid, 71. Typical examples include z-inic acid, freic anhydride, citraconic acid, citraconic anhydride, itaconic acid, and itaconic anhydride. The amount of such a modifier in the modified polyolefin is preferably 0.01 to 3 weight X. In the present invention, an epoxy resin adhesive is used to adhere the above-mentioned modified polyolefin to metal. Such adhesives include various conventionally known adhesives that have various functional groups and are used to fuse polyolefins or polyolefin compositions containing various polymers to metals. can be used. For example, it is possible to use a thermosetting epoxy resin having a molecular weight of about 300 to 4000 and containing a so-called epoxy resin curing agent such as amines, polyamides, acid anhydrides, and butylated urea formaldehyde resin. The epoxy resin used for this is generally a bisphenol A resin, but various other epoxy resins may also be used. However, preferably, an epoxy resin having a molecular weight of about 300 to 500 and being liquid at room temperature is easy to handle during work. The coating thickness of the epoxy resin is 1 to 200 microns, preferably 10 to 5 microns.
It has a diameter of about 0 micron and can be applied to metal surfaces using a roll rotor, bar coater, spray, etc.

In the present invention, the metal whose surface has been cleaned is preheated to ensure adhesion to the adhesive within 1 minute. Usually, it is carried out at 200° C. or lower in consideration of the thermal stability of the thermosetting epoxy resin adhesive. Preheating the metal is effective in lowering the viscosity of the epoxy resin adhesive to improve wetting with the metal and curing the adhesive. The present inventors have investigated the effects of the degree of curing of thermosetting epoxy resins on the adhesive strength and salt water resistance of metal-polyolefin laminates-9ii1
1. As a result of research on this issue, an adhesive made of liquid epoxy resin and a hardening agent is applied onto a preheated metal surface, and after the adhesive gels until it maintains a certain glass transition temperature, denaturation occurs. The polyolefin is heated to a temperature higher than its melting point, placed on the adhesive surface, and pressure bonded. At that time, the heat retained by the heated modified polyolefin causes a curing reaction within the adhesive to reach a certain glass transition temperature. It has been found that the laminate of metal and polyolefin obtained by such an operation not only has sufficient adhesive strength but also has excellent salt water resistance. In this case, if the modified polyolefin is thermocompressed before the epoxy resin adhesive gels,
Since the adhesive is in a flowable state, the thickness of the adhesive layer becomes non-uniform, causing a large variation in peel strength, which is undesirable because the peel strength also becomes low. Further, even if a modified polyolefin is thermocompression bonded onto an adhesive layer that has been heat-cured until a constant glass transition temperature is maintained, the peel strength does not change, but salt water resistance decreases, which is not preferable.

Methods for fusing strength of modified polyolefin include methods using powdered modified polyolefin such as fluid dipping method and electrostatic coating method, method of fusing modified polyolefin in sheet form, and method of extrusion coating of modified polyolefin. . Whichever method is used, it is important to heat the modified polyolefin to a temperature higher than its melting point. Even if the adhesive is applied and cured at a temperature below the melting point of the modified polyolefin and bonded under heat and pressure, it does not exhibit high adhesive strength and has excellent water resistance and I@
In addition, not only can a laminate be obtained by heat-sealing the modified polyolefin after heating the metal coated with the adhesive, but also an unmodified polyolefin can be applied on the fused modified polyolefin layer. May be laminated 〇 Examples of metals used in the present invention include iron, aluminum, tin, zinc, lead, chromium, nickel, alloys of these metals, and metal plates plated with these metals. , A common steel plate (8841) with a thickness of 3.2 mm was blasted with 40 mesh steel shot and heated in an electric furnace set at 80° C. for 30 minutes.
After heating for 0 minutes, the liquid epoxy resin composition was applied to a film thickness of 30 microns using a bar coater, and placed in an electric furnace at 150°C to harden the adhesive (gelling time: 6 minutes).
Next, a modified polyolefin (melting point 125°C) prepared by graft-polymerizing maleic anhydride onto polyethylene was added on top of this.
A film with a thickness of 50 microns and a film with a thickness of 2
A sheet of high-density polyethylene (melting point: 129°C) of M was placed and pressed using a hot press at 15 pt for 10 minutes.

After the pressure bonding, the laminate was left to cool at room temperature for about 3 hours to obtain a laminate. The thus obtained laminate was immersed in 3X saline solution at 80°C for 47 days, and the 90 degree peel strength of the film was measured. The results are as shown in the attached drawing. According to the degree of curing of the epoxy resin composition from applying the epoxy resin composition to fusing the modified polyolefin, the optimum curing conditions for the adhesive to obtain a laminate with excellent salt water resistance are determined until the epoxy resin composition gels. It is easily understood that this is the period from which the resin becomes a cured resin exhibiting a certain glass transition temperature. The glass transition temperature of the epoxy resin composition was measured using differential scanning calorimetry (DSC) at a temperature increase of 10°C/- from room temperature (23°C).

[Brief explanation of the drawing]

The attached drawing is a graph showing the optimal curing conditions for epoxy resin adhesive in a laminate of copper plate and polyolefin.〇Patent applicant: Kawasaki Steel Corporation

Claims (1)

[Claims] When manufacturing a laminate of polyolefin and metal by fusing a metal with a modified polyolefin modified with an unsaturated carboxylic acid or its anhydride, a liquid epoxy resin composition containing a curing agent is applied onto the metal phase. , the modified polyolefin is laminated and fused onto the epoxy resin composition by heating it to a temperature above the melting point until it becomes a cured resin exhibiting a certain glass transition temperature after it gels during solidification. Method C for producing a laminate of polyolefin and metal with excellent salt water resistance