JPS5920450B2 - Lamination method with excellent salt water peeling resistance - Google Patents

Description

[Detailed description of the invention] The present invention relates to a lamination method with excellent salt water peeling resistance.

More specifically, the present invention relates to a method of laminating a surface-treated iron or iron-containing alloy with a modified polyolefin, which has excellent salt water peeling resistance. Conventionally, a method has been used in which the surface of metal is coated with resin in order to prevent corrosion of the metal surface.

However, when a non-polar resin such as polyolefin is used as the coating resin, the adhesiveness to metals is extremely poor. In order to improve this drawback, there is a method of improving adhesion to metal by using polyolefin modified with unsaturated carboxylic acid or its anhydride, or a method of improving adhesion to metal by using a primer that has affinity for both metal and polyolefin. A method has been adopted in which the adhesion to metal is improved by laminating polyolefin on the surface of the metal. However, even in the former method using modified polyolefin, peeling easily occurs under severe usage conditions such as contact with salt water, and a sufficient adhesive effect has not been obtained. In addition, although the latter method of applying a primer treatment provides a salt water peel-resistant coating, the process becomes complicated, leading to a decrease in productivity and an increase in product price. On the other hand, when painting the surface of metal such as iron, in order to improve the adhesion of the paint film, there is a method in which the metal surface is subjected to a chemical conversion treatment in advance with a treatment solution containing phosphoric acid and phosphates, or a method in which dichromium is further applied to the surface of the metal. The method of performing chromate treatment with a treatment solution containing an acid compound is well known and generally widely adopted.

However, the poorly soluble coating formed on the metal surface by this chemical conversion treatment itself has little effect on imparting corrosion resistance to the metal, and is also effective in improving the adhesion of the paint film when used as a base for paint coating. It wasn't enough either. The present inventors have discovered that by laminating modified polyolefin on iron or iron-containing alloys whose surfaces have been subjected to a specific chemical conversion treatment, they can be used satisfactorily without peeling even under harsh corrosive usage conditions such as in salt water. They discovered this and arrived at the present invention.

That is, the present invention applies surface treatment to iron or an iron-containing alloy with a surface treatment liquid containing phosphoric acid and a zinc compound or a manganese compound, and further performs chromate treatment, and then forms a modified polyolefin or a modified polyolefin and an unmodified polyolefin. This is a lamination method with excellent salt water peeling resistance, which is characterized by laminating a composition of the following.

The metal used in the method of the present invention is iron or an iron-containing alloy, and specifically includes steel, cast iron, and various stainless steels.

The surfaces of these metals to be coated by lamination are preferably clean. For example, it is preferable to remove rust, dirt, etc. by mechanical polishing or the like, and then perform a degreasing treatment. The iron or iron-containing alloy used in the method of the present invention requires surface treatment with a surface treatment solution containing phosphoric acid and a zinc compound or a manganese compound, and then further chromate treatment.

As the surface treatment liquid, an aqueous solution containing phosphoric acid and a zinc compound or a manganese compound dissolved in the phosphoric acid is usually used. In addition to orthophosphoric acid, the phosphoric acids used here include phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, polyphosphoric acid, and peroxophosphoric acid; diphosphorus pentoxide, diphosphorus tetroxide, Phosphorus compounds that produce orthophosphoric acid in aqueous solution can also be used, such as phosphorus oxides such as diphosphorus trioxide: phosphorus chloride compounds such as phosphorus pentachloride, phosphorus trichloride, and phosphorus oxychloride. The zinc compound used in the surface treatment liquid is preferably a zinc compound that dissolves in an aqueous phosphoric acid solution.

More specifically, in addition to zinc phosphate, similar phosphoric acids such as zinc monohydrogen phosphate, zinc dihydrogen phosphate; metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, polyphosphoric acid, peroxophosphoric acid, etc. Zinc salt; zinc oxide, zinc halide,
Zinc salts of inorganic acids such as zinc sulfate, zinc nitrate, zinc carbonate;
Examples include zinc salts of organic acids such as zinc acetate and zinc oxalate. Among these zinc compounds, it is preferable to use zinc salts of phosphoric acids, zinc oxide, and zinc salts of inorganic acids. Furthermore, as the manganese compound used in the surface treatment liquid, a manga compound that dissolves in an aqueous phosphoric acid solution is preferable.

More specifically, in addition to manganese phosphate, similar manganese salts such as monohydrogen manganese phosphate, dihydrogen manganese phosphate; metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, polyphosphoric acid, peroxophosphoric acid, etc. ; Manganese oxide; Manganese salts of inorganic acids such as manganese halides, manganese sulfate, manganese nitrate, and manganese carbonate; Manganese salts of organic acids such as manganese acetate and manganese oxalate. Among these manganese compounds, it is preferable to use manganese salts of phosphoric acids, manganese oxide, and manganese salts of inorganic acids. The surface treatment solution usually contains nitrates such as sodium nitrate, potassium nitrate, and calcium nitrate, nitrites such as sodium nitrite, potassium nitrite, and calcium nitrite, and sodium chlorate and potassium chlorate as surface treatment accelerators. Copper compounds such as chlorates, copper oxide, and copper carbonate are added.

The concentration of phosphoric acid in the surface treatment solution is usually in the range of 0.05 to 0.5 mol/l, and the hydrogen ion concentration of the surface treatment solution is in the range of 2.0 to 3.7 in terms of pH. is preferred.

Further, the concentration of the zinc compound or manganese compound in the surface treatment solution is usually in the range of 1 to 10 g ions/l as zinc ions or manganese ions. The zinc compound or manganese compound added to the surface treatment solution usually reacts with phosphoric acid and changes into a zinc salt or manganese salt of phosphoric acid. The ratio of zinc compounds or manganese compounds to free phosphoric acid present in this surface treatment solution (for example, the ratio of "total acidity" to "free phosphoric acidity" measured by the method described below, expressed as "acidity ratio") .) is preferably in the range of 2 to 20,
In particular, it is preferably in the range of 5 to 10. Although it is not necessary that the surface treatment accelerator be present in the surface treatment solution, it is usually in the range of 0.2 to 1 in molar ratio to the zinc compound or manganese compound. It is added in In order to surface-treat the iron or iron-containing alloy used in the method of the present invention with the above-mentioned surface treatment liquid, a method using immersion or spraying is employed. Processing temperatures are usually in the range of 40 to 100°C.
Iron or iron-containing alloys that have been surface-treated by the above method must be subjected to chromate treatment. In the chromate treatment, iron or an iron-containing alloy that has been surface-treated by the method described above is usually treated with an aqueous solution containing a dichromate compound. As a treatment method, a method of immersing in an aqueous solution containing a dichromic acid compound or a method of spraying an aqueous solution containing a dichromic acid compound is adopted.
In addition to dichromate, dichromate compounds in the aqueous solution for chromate treatment include lithium dichromate, sodium dichromate, potassium dichromate, calcium dichromate, magnesium dichromate, and ammonium dichromate. Compounds that produce dichromic acid when dissolved in water are used, such as dichromate, chromium trioxide, etc.
Its concentration usually ranges from 0.001 to 0.1 mol/l, preferably from 0.005 to 0.02 mol/l. The temperature during chromate treatment is usually 60 to 9
The temperature is in the range of 0°C, and the treatment time varies depending on the treatment temperature, but is 1 to 5 minutes. Chromate-treated iron or iron-containing alloys should be washed with water and dried if necessary.
Provided for the laminate of the present invention. In the method of the present invention, a modified polyolefin or a composition of a modified polyolefin and an unmodified polyolefin is used as a laminated resin to be laminated to iron or an iron-containing alloy.

Examples of the polyolefin used after modification or the polyolefin used in combination with the modified polyolefin include ethylene, propylene, 1-butene, 4-methyl-
Homopolymers such as 1-pentene, copolymers containing these components as main components and different olefins among these components, or copolymers containing these components as main components with other diene components or conjugated diene components Alternatively, a copolymer containing a carboxylic acid unsaturated ester component can be mentioned.
More specifically, these polyolefins include high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene, poly-1-butene, poly-4
-Methyl-1-benzene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-butadiene copolymer, ethylene-monovinyl acetate copolymer, propylene-ethylene copolymer, propylene-1-butene Examples include copolymers, propylene monovinyl acetate copolymers, and mixtures thereof may also be used. Although high molecular weight polymers or rubbery polymers of these polyolefins are usually used in the laminate of the present invention, low molecular weight waxy polymers can also be used. The modified polyolefin used in the method of the present invention is a modified product of the polyolefin described above.

Specifically, the modifying monomer components used for modifying polyolefins include acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, itaconic acid, and anhydride. Unsaturated carboxylic acids or their anhydrides such as itaconic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic acid, 5-norbornene-2,3-dicarboxylic anhydride; acrylic acid, methacrylic acid Metal salts of unsaturated carboxylic acids such as , maleic acid, and fumaric acid: Unsaturated carboxylic acid esters such as methyl acrylate, methyl methacrylate, monomethyl maleate, dimethyl maleate, monomethyl fumarate, and dimethyl fumarate; acrylic acid Unsaturated carboxylic acid amides such as amide, methacrylic acid amide, maleic acid monoamide, maleic acid diamide, fumaric acid diamide; maleimide,
Unsaturated carboxylic acid imide such as itaconimide, lylyl alcohol, 3-buten-1-ol, acrylic acid-
Hydroxyl group-containing unsaturated compounds such as β-hydroxyethyl, mono-β-hydroxyethyl methacrylate; vinyl glycidyl ether, allyl glycidyl ether,
Examples include unsaturated epoxides such as glycidyl acrylate and glycidyl methacrylate. Among these modified monomer components, it is preferable to use unsaturated carboxylic acids or their anhydrides, and it is particularly preferable to use maleic anhydride. In order to produce a modified polyolefin, there is usually a method of graft copolymerizing these modified monomer components onto a polyolefin, or a copolymerization method in which these modified monomer components are added in advance to the polyolefin polymerization stage and polymerized. manufactured by Among these modification methods, it is preferable to use a modified polyolefin produced by a graft copolymerization method in the method of the present invention. In the method of the present invention, the modified polyolefin described above can be used alone as a laminated resin, or a composition of the modified polyolefin and an unmodified polyolefin can be used as a laminated resin.

In either case, the content of modified monomer component units contained in the modified polyolefin or the composition of modified polyolefin and unmodified polyolefin to be laminated is usually in the range of 10-3 to 10 mmol per 1 ton of polyolefin;
It is preferably in the range of 5 x 10-3 to 1 mmol. Various conventional methods can be used to laminate the modified polyolefin on the surface-treated iron or iron-containing alloy. For example, (1) powder of modified polyolefin or a composition of modified polyolefin and unmodified polyolefin is laminated on surface-treated iron or an iron-containing alloy by a powder coating method such as an electrostatic coating method or a fluidized dipping method. (2) a method of laminating a modified polyolefin or a composition of a modified polyolefin and an unmodified polyolefin by a melt extrusion method; (3) a method of heating a film formed from a modified polyolefin or a composition of a modified polyolefin and an unmodified polyolefin. This can be carried out by any method such as (4) applying a solution or emulsion of a composition of a modified polyolefin and an unmodified polyolefin. Among these lamination methods, it is preferable to employ a powder coating method or a melt extrusion method. The method of the present invention can be applied to plate-like objects, foils, tube-like objects, and linear objects made of iron or iron-containing alloys, as well as to instruments and equipment with complicated shapes.

Next, the method of the present invention will be specifically explained using examples.

The test pieces, surface treatment methods, lamination test methods, evaluation methods, and adhesive strength measurement methods used in Examples and Comparative Examples are shown below. (1) Test piece As a test piece of iron or iron-containing alloy, an SS-41 iron plate (140 mm x 140 m foot x 1 m 1 L) with a mechanically polished surface was immersed in acetone to degrease it, and then the surface was sandpapered with 120# sandpaper. Specimens were used that were sanded and sanded with 400# sandpaper, cleaned with acetone, and stored in acetone.

(2) Surface treatment method To an aqueous solution containing phosphoric acid and a zinc compound or a manganese compound at a predetermined concentration, add sodium nitrate or sodium nitrite to a predetermined concentration as a surface treatment accelerator, if necessary. This was dissolved to obtain a surface treatment solution.

10 ml of this surface treatment liquid was added to Promphenol Blue (P
Discoloration at H3.8) as an indicator with 0.1N NaOH
m of 0.1N NaOH aqueous solution required
The WLI number of the 0.1 N NaOH aqueous solution was titrated with 0.1 N NaOH aqueous solution using phenolpthalene (changes color at pH 8.4) as an indicator, and the WLI number of the required 0.1 N NaOH aqueous solution was determined as the "total phosphoric acid level". "acidity". The ratio of total acidity to free phosphoric acidity was expressed as "acidity ratio". Furthermore, the measured value of PH of the treatment liquid was also recorded. The above-mentioned iron plate test piece, which had been previously dried in a preheated oven at 70°C, was immersed in this surface treatment solution heated to 70°C for 5 minutes, then taken out, immediately washed with water, and dried in an oven at 70°C.

Further, the test piece subjected to the phosphate treatment was further subjected to a chromate treatment as a post-treatment. The method involved immersing the product in an aqueous solution containing chromium trioxide at a concentration of 0.01 mol/l at 70°C for 1 minute, leaving it to air dry for 5 minutes without washing with water, and then placing it in an oven at 70°C. Dry. (3) Lamination test method The surface-treated test piece is placed on a hot plate of a compression molding machine set at 200°C, and about 287% of the modified polyolefin or a composition of the modified polyolefin and unmodified polyolefin is placed on top of the metal. Spread out almost horizontally on a plate and preheat for 5 minutes to melt the resin and remove air.
By pressing at a pressure of 40k9/C77l-G for 5 minutes and then cooling, a laminate in which a resin layer with a thickness of about 11 Lm was pressed onto a metal plate was obtained.

(4) Method for measuring initial peel strength The laminate prepared using the method described in 3) was
Cut to 0 mm and peel at a peel angle of 18 in an atmosphere of 25°C.
The peel strength was measured when the laminated resin was peeled off at a tensile speed of 50 mm/Mm, and the average value of the three measurement results was calculated as Kg/Mm.
It is expressed in C7rL units.

(5) Method for measuring salt water peel strength A test piece with a width of 20 mm, obtained by cutting the laminate prepared by the method described in α3) in the rolling direction of the iron, was subjected to 1000 rpm at a temperature of 60°C. p. m. The sample was immersed in a bath of saline solution with a concentration of 3% by weight, which was stirred at a speed of .

After 240 hours of immersion, the test piece was taken out and subjected to this test at a peel angle of 180 and a tensile speed of 50 m.
The peel strength upon peeling was measured in m/Mm, and the average value of the three measurement results was shown in K9/Cm. Example 1 Phosphoric acid was added at 0.037 mol/l, zinc phosphate was added at 2.55 gram ions/l as zinc ions, and sodium nitrite was added as a surface treatment accelerator at 0.029 mol/l. A surface treatment solution (PH 2.92, free phosphoric acidity 3.7, total acidity 13.0, acidity ratio 3.5) was prepared by dissolving it.

Further, a 0.01 mol/l aqueous solution of chromium trioxide was used as a chromate treatment solution. S whose surface was polished by the method of Maeki 1)
A test piece of S-41 was immersed in this surface treatment solution and
) The surface treatment was performed using the method described in . High-density polyethylene (manufactured by Mitsui Petrochemical Industries, Ltd.,
Product Name Hi-Zex 1500J1 Density 0.95, MI3
Modified polyethylene obtained by copolymerizing maleic anhydride with O) using a melt-kneading method (containing 17 maleic anhydride component units)
A composition containing 0.10 mmol of maleic anhydride component units per 17% by weight of unmodified medium density polyethylene (0.01 mmol of maleic anhydride component units per 17
A laminate was prepared according to the method (3) above and evaluated according to the methods described in 4) and (5) above.

The results are shown in Table 1. Comparative Example 1 The same procedure as in Example 1 was conducted except that only unmodified medium-density polyethylene was used without blending maleic anhydride-modified polyethylene.

The results are shown in Table 1. Comparative Example 2 The same procedure as in Example 1 was carried out except that no surface treatment was applied.

The results are shown in Table 1. Comparative Example 3 Same as Example 1 except that in Example 1, the surface treatment was performed only with a treatment solution containing phosphoric acid and zinc phosphate, and the surface treatment was not performed with a treatment solution containing 50 μm trioxide. I went to

The results are shown in Table 1. Comparative Example 4 Same as Example 1 except that the surface treatment was not performed with the treatment solution containing phosphoric acid and zinc phosphate, but only with the treatment solution containing chromium trioxide. I went.

The results are shown in Table 1. Example 2 In Example 1, 0.01% of phosphoric acid was used as the surface treatment liquid.
9 mol/11 manganese dihydrogen phosphate 3.26 mol/l
and an aqueous solution containing 0.059 mol/l of sodium nitrate (PH 2.7O, free phosphoric acidity 1.9, total acidity 16.
Example 1 was carried out in the same manner as in Example 1, except that the acidity ratio was 0.0 and the acidity ratio was 8.4).

The results are shown in Table 1. Comparative Example 5 The same procedure as in Example 2 was carried out except that the chromate treatment with an aqueous chromium trioxide solution was not performed.

The results are shown in Table 1. ☆★Example 3 In Example 1, medium-density polyethylene (manufactured by Mitsui Petrochemical Industries, Ltd., trade name: NEOSEX 451) was used as the laminated resin.
Modified polyethylene (containing 0.01 mmol of maleic anhydride component units per 17 units) obtained by graft copolymerizing maleic anhydride using a melt-kneading method on 501 density 0.944, Ml5) was used solely as a surface treatment liquid. The same procedure as in Example 1 was carried out except that the treatment liquid having the composition shown in Table 1 was used.

Claims (1)

[Claims] 1. After surface treatment of iron or iron-containing alloy with a surface treatment liquid containing phosphoric acid and a zinc compound or a manganese compound, and further chromate treatment, the iron or iron-containing alloy is treated with a modified polyolefin or an unmodified polyolefin. A lamination method with excellent salt water peeling resistance characterized by laminating polyolefin compositions. 2. The method according to claim 1, wherein an aqueous solution in which phosphoric acid and a zinc compound or a manganese compound are dissolved is used as the surface treatment liquid. 3. As zinc compounds or manganese compounds contained in the surface treatment solution, salts of zinc or manganese phosphates,
The method according to claim 1 or 2, characterized in that an inorganic acid salt or oxide is used. 4. The method according to claims 1 to 3, characterized in that a surface treatment liquid having a pH in the range of 2.0 to 3.7 is used. 5. As a surface treatment solution, use a surface treatment solution with a pH in the range of 2.0 to 3.7 and a concentration of zinc compounds or manganese compounds in the range of 1 to 10 g ions/l as zinc ions or manganese ions. A method according to claims 1 to 4, characterized in that it is used. 6. The method according to claims 1 to 5, characterized in that a surface treatment liquid having an acidity ratio in the range of 2 to 20 is used as the surface treatment liquid. 7. The method according to any one of claims 1 to 6, characterized in that a surface treatment liquid containing a surface treatment accelerator in addition to phosphoric acid and a zinc compound or a manganese compound is used as the surface treatment liquid. 8. Claims 1 to 7 characterized in that the chromate treatment involves treating the surface-treated iron or iron-containing alloy with an aqueous solution containing a dichromate compound.
the method of. 9. The method according to claims 1 to 8, characterized in that the modified polyolefin is a modified polyolefin produced by graft copolymerization of an unsaturated carboxylic acid or its anhydride. 10. The method according to claims 1 to 9, characterized in that a modified polyolefin produced by graft copolymerization of maleic anhydride is used as the modified polyolefin. 11 A modified polyolefin or a composition of a modified polyolefin and an unmodified polyolefin containing a modified monomer component in a range of 5 x 10^-^3 to 1 mmol per gram is applied to surface-treated iron or an iron-containing alloy. The method according to any one of claims 1 to 10, characterized in that the method comprises laminating layers. 12 Claims 1 to 1, characterized in that a modified polyolefin or a composition of a modified polyolefin and an unmodified polyolefin is laminated on surface-treated iron or an iron-containing alloy by a powder coating method or a melt extrusion method. 11 methods.