JPH05293931A - Production of laminate - Google Patents

Abstract

PURPOSE:To produce a metal-resin laminate rich in corrosion resistance and water resistance and hard to generate the release of a metal layer and a resin layer in high yield by adding a substance discharging water of crystallization at the time of melt bonding before silane modified polyethylene is bonded to the surface of a metal plate in a molten state. CONSTITUTION:A laminate is produced by bonding silane modified polyethylene to the surface of a metal plate. As silane modified polyethylene, a copolymer of ethylene and an unsaturated organosilane compd. or a substance obtained by grafting silane to polyethylene by kneading polyethylene, org. peroxide and an unsaturated organosilane compd. is used. As an additive added to the resin, ammonium aluminum sulfate dihydrate (discharge temp. of water of crystallization; 200 deg.C) is employed. When this resin is heated, water of crystallization is discharged from the additive and moisture is dispersed in silane modified polyethylene and silane modified polyethylene is homogenously hydrolyzed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminate of a resin and a metal, which has excellent corrosion resistance and adhesiveness, and is used, for example, for roofing materials, wall materials, rain gutters, metal-resin composite pipes and the like. The present invention relates to a method for producing a laminate suitable for

[0002]

2. Description of the Related Art In order to improve the corrosion resistance of metals,
A laminated body in which the surface of a metal plate is coated with a synthetic resin is known, and as a coating method thereof, a method of adhering a synthetic resin layer to a metal plate via an adhesive layer and a resin without using an adhesive agent There is known a method of directly fusion bonding the.

Utilizing its excellent corrosion resistance, such a laminate is used for roof materials, wall materials, rain gutters, etc. of buildings, and at least the inner surface of a metal tube is coated with a resin. As a so-called metal-resin composite pipe, it is used as a hot water supply / water supply pipe. As a method for producing a metal-resin composite pipe, for example, as disclosed in Japanese Patent Laid-Open No. 62-198447, a strip-shaped metal plate is continuously formed into a cylindrical shape by overlapping or abutting both side edges. A method is known in which a molten resin is extruded cylindrically on the inner surface of the metal tube by coating and molding the metal tube with resin while continuously forming the metal tube by molding and joining the overlapped portion or the butted portion. ing.

In the above-mentioned laminate, polyolefin, particularly polyethylene is often used as a coating resin due to factors such as elongation of resin, deterioration rate, chemical resistance and versatility. However, polyethylene has no adhesive force to metal, and there are very few adhesives that can adhere polyethylene.

Therefore, in order to impart adhesiveness to polyethylene, introduction of a functional group has been adopted as a known method. Specifically, a copolymer of a functional monomer such as acrylic acid and ethylene, or an unsaturated carboxylic acid such as maleic acid or an unsaturated organic silane compound such as vinyltrimethoxysilane is added to polyethylene. Grafting is often used.

Of these, it is known that those having a carboxylic acid introduced as a functional group are inferior in water resistance. Therefore, a laminate used for an application requiring water resistance is disclosed in As disclosed in JP-A No. 52-78983, many of them are silane-modified by grafting the above-mentioned unsaturated organic silane compound.

[0007]

By the way, it is necessary to hydrolyze the silane-modified polyethylene in order to develop its adhesiveness to metal. This hydrolysis proceeds in the presence of water or a catalyst.

Of these, the method of hydrolysis by addition of a catalyst has a drawback that the hydrolysis proceeds too much to cause cross-linking, and on the contrary, the adhesive strength is often reduced.
Further, in the case of the method of hydrolyzing with water, according to a natural reaction utilizing water vapor in the atmosphere, since the resin is hydrophobic, it is difficult for water to be contained in the resin, and there is a problem that the hydrolysis rate is very slow. .. In addition, because of seasonal fluctuations in humidity, it was necessary to forcibly replenish water by a method such as humidification when it was dry.

The present invention has been made in view of the above points, and it is possible to always stably and firmly bond silane-modified polyethylene to the surface of a metal plate without using a catalyst and without humidifying from the outside. To provide a method capable of producing a metal-resin laminate having a high yield, which is excellent in corrosion resistance and water resistance, and which is rich in durability in which the metal layer and the resin layer are difficult to separate from each other. Has a purpose.

[0010]

In order to achieve the above-mentioned object, the method for producing a laminate of the present invention is such that the silane-modified polyethylene is melted and adhered to the surface of the metal plate before the silane-modified polyethylene is melt-bonded to the surface of the metal plate. It is characterized by adding a substance which releases water of crystallization under heating temperature during melt bonding to the plate.

In the present invention, as the material of the metal plate,
Steel, stainless steel, aluminum, copper, etc. can be used. The surface of the metal is preferably subjected to a known surface treatment, for example, for steel, primer coating, blast treatment,
Examples include degreasing treatment by alkali treatment, acid treatment by hydrochloric acid, sulfuric acid, nitric acid, etc., chemical conversion coating treatment by phosphate, etc.

As the silane-modified polyethylene in the present invention, a copolymer of ethylene and an unsaturated organic silane compound, or polyethylene, an organic peroxide and an unsaturated organic silane compound are kneaded to silane-graft polyethylene. The thing etc. can be used. The unsaturated organosilane compound used here has both an unsaturated site such as a vinyl group, an allyl group and a methacryl group and a hydrolyzable site such as an alkoxyl group, an oxime group and a chloro group in one molecule. You can list things like Specifically, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane and the like can be preferably used.

In the present invention, as additives to be added to the resin, ammonium aluminum sulfate dihydrate (crystal water release temperature 200 ° C), ammonium iron sulfate dodecahydrate (230 ° C), calcium oxalate are used. Monohydrate (at 200 ° C.) and the like can be preferably used.

In the present invention, the cohesive strength is improved,
In order to reduce the linear expansion coefficient or suppress molding shrinkage, known inorganic fillers such as short glass fibers, talc, mica, wollastonite and potassium titanate whiskers may be further added to the resin layer.

It is needless to say that the metal plate in the present invention includes not only a flat plate-shaped plate but also a plate molded into any shape, and a tubular plate such as the above-mentioned metal-resin composite pipe or other. It is needless to say that the silane-modified polyethylene can be laminated on the molded product having the above-mentioned shape, and further, it can be molded into an arbitrary shape by an appropriate secondary processing after the lamination.

[0016]

When the resin is heated in, for example, an extruder in order to melt-bond the silane-modified polyethylene to the metal plate, crystallization water is released from the additive and water is dispersed inside the silane-modified polyethylene. The modified polyethylene is homogeneously hydrolyzed to achieve the intended purpose.

[0017]

According to the method for producing a laminated body of the present invention, when the silane-modified polyethylene is melt-bonded to the metal plate, crystal water is released from the additive inside the silane-modified polyethylene, and the silane-modified polyethylene contains moisture inside. Is supplied and undergoes hydrolysis, and compared with the case of supplying water from the surface as in the conventional method using water vapor in the atmosphere, the entire resin is homogeneous and in a short time. As it is hydrolyzed, there is no need to humidify it from the outside, and moreover, a constant amount of water is supplied regardless of the humidity of the atmosphere, so it is always stable and has good adhesion without being affected by seasonal fluctuations. You can get power.

Further, since no catalyst is used, hydrolysis does not proceed too much to cause cross-linking, resulting in no decrease in adhesive strength. From the above, it has become possible to stably produce a laminate having high corrosion resistance and water resistance, and having excellent durability in which peeling of the resin layer does not easily occur, with a high yield.

[0019]

EXAMPLES Hereinafter, a concrete explanation will be given with reference to an example in which a laminate is actually produced by using the method of the present invention.

(Example 1) Linear low density polyethylene 10
180 parts by weight of 1 part by weight of vinyltrimethoxysilane and 0.04 parts by weight of organic peroxide (perbutyl D) per 0 part by weight.
Kneading was performed at ° C to prepare silane-grafted polyethylene. To this silane-grafted polyethylene, 5 parts by weight of calcium oxalate was added and kneaded at 150 ° C. to prepare an additive-containing silane-grafted polyethylene.

Dimension 150 mm × 150 mm, wall thickness 1 mm
The aluminum plate of No. 1 is prepared, and the aluminum plate is sequentially subjected to surface treatment with a degreasing detergent, an aqueous solution of sodium hydroxide, and nitric acid, and then the above-mentioned silane-grafted polyethylene containing additives is placed on the plate at 230 °
C and 40 kgf / cm ² were laminated and bonded by pressing to obtain a laminate having a resin layer thickness of 2 mm.

This laminate was cut to a width of 10 mm, and each piece was cut in accordance with JIS K6854 "Peeling adhesive strength test method for adhesives" (however, "T type peel test piece with a width of 10 mm"). The peel adhesion strength between the aluminum plate and the synthetic resin layer was measured to be 20 kgf / 1.
It was 0 mm.

(Example 2) Silane-grafted polyethylene containing additives exactly the same as in Example 1 was placed on a chromate-treated galvanized steel plate having a thickness of 150 mm x 150 mm and a thickness of 0.5 mm, and the same temperature and pressure were applied. Then, they were laminated and adhered by a press to obtain a laminate having a resin layer of 2 mm. When a peeling test similar to that in Example 1 was performed on this laminated body, the peeling strength was 23 kgf / 10 mm.

(Comparative Example 1) An aluminum plate exactly the same as in Example 1 was prepared, the same surface treatment was performed, and the same silane-grafted polyethylene before the addition of the above-mentioned additives was treated at the same temperature and the same pressure. Originally laminated by press,
A laminate having a resin layer of 2 mm was obtained. Also for this stack,
As a result of measuring the peel adhesion strength by the same method as in Example 1, 1
It was 3 kfg / 10 mm.

Comparative Example 2 On the same chromate-treated galvanized steel sheet as in Example 2, 0.005 parts by weight of dibutyltin dioxide as a catalyst was added and kneaded to the silane-grafted polyethylene as in Comparative Example 1, and kneaded. Attempts were made to laminate and bond under the same temperature and the same pressure, but they could not be bonded.

Claims (1)

[Claims] 1. A method for producing a laminate in which at least one surface of a metal plate is coated with a silane-modified polyethylene, wherein the silane-modified polyethylene is melt-bonded to the surface of the metal plate before the silane-modified polyethylene is melt-bonded to the surface of the metal plate. A method for producing a laminate, comprising adding a substance that releases water of crystallization at a heating temperature at the time of fusion bonding to the metal plate.