JPS5920449B2 - 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 for producing a salt water peel-resistant laminate in which surface-treated iron or iron-containing alloy is laminated with modified polyolefin. 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, there is a drawback that the adhesion to metal is extremely poor. In order to improve this drawback, a method has been proposed that improves adhesion to metal by using polyolefin modified with unsaturated carboxylic acid or its anhydride, or a primer that has affinity for both metal and polyolefin. A method has been adopted in which the adhesion to the metal is improved by applying polyolefin to the surface of the metal and then laminating polyolefin. 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 metals such as iron, it is well known that in order to improve the adhesion of the paint film, the metal surface is subjected to a chemical conversion treatment in advance with a treatment solution containing phosphoric acid and phosphates. It has been widely adopted.

However, the poorly soluble film formed on the surface of metal by this chemical conversion treatment itself has little effect on imparting corrosion resistance to metal, and moreover, it has no effect on improving the adhesion of the paint film when used as a base for paint film. It wasn't enough. The present inventors have discovered that when modified polyolefin is laminated onto iron or iron-containing metal whose surface has been subjected to a specific chemical conversion treatment, it can be used satisfactorily without peeling even under harsh corrosive usage conditions such as in salt water. We discovered what we could do and arrived at the present invention.

That is, in the present invention, iron or an iron-containing alloy is surface-treated with a surface treatment liquid containing phosphoric acid, a zinc compound, and a calcium compound, and then a modified polyolefin or a composition of a modified polyolefin and an unmodified polyolefin is laminated. This is a lamination method with excellent salt water peeling resistance.

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 treatment solution containing phosphoric acid, a zinc compound, and a calcium compound.

As the surface treatment liquid, an aqueous solution in which phosphoric acid, a zinc compound, and a calcium compound are dissolved 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; diphosphoric acid pentoxide,
Phosphorus compounds that produce orthophosphoric acid in an aqueous solution include phosphorus oxides such as niline tetroxide and niline trioxide; and 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 monohydrogen phosphate, zinc dihydrogen phosphate: metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, polyphosphoric acid, peroxophosphoric acid, etc. Zinc salts of: zinc oxide; zinc salts of inorganic acids such as zinc halides, zinc sulfate, zinc nitrate, and zinc carbonate; and 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. Further, as the calcium compound used in the surface treatment liquid, a calcium compound that dissolves in an aqueous phosphoric acid solution is preferable.

More specifically, in addition to calcium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate; similar calcium salts such as metaphosphate, pyrophosphate, triphosphate, tetraphosphate, polyphosphate, peroxophosphate: oxidation Calcium; calcium salts of inorganic acids such as calcium nilogenide, calcium sulfate, calcium nitrate, and calcium carbonate:
Examples include calcium salts of organic acids such as calcium acetate and calcium oxalate. Among these calcium compounds, it is preferable to use calcium salts of phosphoric acids, calcium oxides, or calcium salts of inorganic acids. The surface treatment solution further contains nitrate salts such as sodium nitrate, potassium nitrate, calcium nitrate, sodium nitrite, potassium nitrite, etc. as a surface treatment accelerator.
Nitrite salts such as calcium nitrite, sodium chlorate,
Chlorates such as potassium chlorate, copper compounds such as copper carbonate, and copper oxide 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.

In addition, the concentration of the zinc compound in the surface treatment solution is usually in the range of 1 to 10 g ions/l as zinc ions,
The concentration of calcium compounds usually ranges from 0.1 to 5 gram ions/l of calcium ions. Also,
The ratio of calcium to zinc in the surface treatment liquid is preferably in the range of 0.1 to 1 as an atomic ratio of each ion. The zinc compound and calcium compound added to the surface treatment solution usually react with phosphoric acid and change into zinc and calcium salts of phosphoric acid. The ratio of both phosphates to the free phosphoric acid present in the surface treatment solution (for example, expressed as the "acidity ratio", the ratio of "total acidity" to "free phosphoric acidity" measured by the method described below). is preferably in the range of 2 to 20, particularly preferably in the range of 5 to 10. Also,
Although it is not necessary that the surface treatment accelerator be present in the surface treatment solution, it is usually in a molar ratio of 0.2 to 1 with respect to the sum of the zinc compound and calcium 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 treatment liquid,
Usually, immersion or spraying methods are used.

Processing temperatures are usually in the range of 20 to 100°C. The surface-treated iron or iron-containing alloy is washed with water, dried, and then used in the laminate of the present invention. The iron or iron-containing alloy subjected to such surface treatment may be subjected to various post-treatments as necessary. For example, the salt water peeling resistance can be further improved by performing chromate treatment with a treatment liquid containing a hexavalent chromium compound such as chromium trioxide or dichromic hydrochloric acid as a post-treatment. 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-benzene, 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 above-mentioned polyolefin.

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-melhorne-2,3-dicarboxylic acid, 5-norbornene-2,3-dicarboxylic anhydride; acrylic acid, methacrylic acid acids, metal salts of unsaturated carboxylic acids such as maleic acid and hepatomaric acid; methyl acrylate, methyl methacrylate,
Unsaturated carboxylic acid esters such as monomethyl maleate, dimethyl maleate, monomethyl fumarate, dimethyl fumarate; acrylamide, methacrylic acid amide,
Unsaturated carboxylic acid amides such as unsaturated diamides such as maleic acid monoamide and maleic acid diamide; Unsaturated carboxylic acid imides such as maleimide and itaconimide; Hydroxy group-containing unsaturated compounds such as β-hydroxyethyl methacrylate; vinyl glycidyl ether, allyl glycidyl ether,
Examples include unsaturated epoxies 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 acid. Modified polyolefins are usually produced by graft copolymerization of these modified monomer components onto polyolefins, or by a direct copolymerization method in which these modified monomer components are added in advance to the polyolefin polymerization stage and polymerized. Ru. 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, preferably 5 mmol per 1y of polyolefin. ×10-3 to 1
It is preferable that the amount is in the millimole range (.o) 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 applied to iron or iron-containing alloy that has been surface-treated by a powder coating method such as an electrostatic coating method or a fluidized dipping method. (3) Method of laminating modified polyolefin or a composition of modified polyolefin and unmodified polyolefin by melt extrusion method; (3) Modified polyolefin
(4) Applying a solution or emulsion of a composition of a modified polyolefin and an unmodified polyolefin. It is also possible to implement this method. 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 cotton-like objects made of iron or iron-containing alloys, as well as 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 peel 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 mm x 1 mm) 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.

(Support) Surface treatment method Add and dissolve sodium nitrate or sodium nitrite as a surface treatment accelerator as necessary to a specified concentration in an aqueous solution containing phosphoric acid, a zinc compound, and a calcium compound at specified concentrations. This was used as 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 for titration with aqueous solution
The number of Me in the required 0.1N NaOH aqueous solution was determined by titrating with a 0.1N NaO aqueous solution using phenolphthalene (changes color at pH 8.4) as an indicator. The ratio of total acidity to free phosphoric acidity was expressed as [acidity ratio].The measured value of PH of the treatment solution was also recorded. The above-mentioned iron plate test piece, which had been dried in a preheated oven at 70°C, was immersed for 5 minutes, then taken out, immediately washed with water, and dried in an oven at 70°C.

Further, the phosphate-treated test piece was further subjected to chromate treatment as a post-treatment, if necessary.

The method was to immerse it in a 70°C aqueous solution containing chromium trioxide at a concentration of 0.01 mol/l for 1 minute, then air dry it for 5 minutes without washing with water, and then heat it in an oven at 70°C. dried inside. (3) Lamination test 1 test method The test piece subjected to the above surface treatment is placed on a hot plate of a compression molding machine set at 200°C, and about 28 y of a composition of modified polyolefin or unmodified polyolefin such as the modified polyolefin is placed on it. Spread out almost horizontally on a metal plate and preheat for 5 minutes to melt the resin and remove air.
By pressing at a pressure of 40 kg/Cd-G for 5 minutes and then cooling, a laminate in which a resin layer with a thickness of about 1 mm was bonded to a metal plate was obtained.

(4) Method for measuring initial peel strength The laminate prepared by the method (3) above was cut into a width of 20 mm in the rolling direction of the iron, and the peel angle was 1 in an atmosphere of 25°C.
The peel strength was measured when the laminated resin layer was peeled off at a tensile rate of 80 mm and a tensile speed of 50 mm/min, and the average value of the three measurement results was expressed in units of K9/(177!).

(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 (3) above in the rolling direction of the iron, was subjected to 1000 rpm at a temperature of 60°C. p. The sample was immersed in a bath of saline solution with a concentration of 3% by weight, which was stirred at a speed of m.

After 240 hours of immersion, the test piece was taken out and subjected to this test at a peel angle of 1800 and a tensile speed of 50 mm/
MT! The peel strength when peeled off at t was measured, and the average value of the three measurement results was determined as K9/? Shown in units. Examples 1-2 Phosphoric acid is 0.011 mol/l, zinc phosphate is 1.71 gram ion/l as zinc ion, and calcium dihydrogen phosphate is 0.27 gram ion/l as calcium ion.
1 and sodium nitrate as a surface treatment accelerator.
Dissolve it in water to a concentration of 39 mol/l and add it to the surface treatment solution (
PH2.75, free phosphoric acidity 1.1, total acidity 10.4,
An acidity ratio of 9.5) was prepared.

A test piece of SS-41 whose surface had been polished by the method (1) above was immersed in this surface treatment solution, and the surface was treated by the method (2) above.

The test piece of Example 2 was subjected to chromate treatment as a post-treatment. High-density polyethylene (
Manufactured by Mitsui Petrochemical Industries, Ltd., product name Hi-Zex 15
Modified polyethylene (containing 0.10 mmol of maleic anhydride component units per 17) obtained by graft copolymerizing maleic anhydride to 00J1 density 0.96, M3O) by melt-kneading method was added to unmodified medium density polyethylene. Using a composition (containing 0.01 mmol of maleic anhydride component units per 17) blended so that the amount was 10% by weight,
A laminate was produced according to method (3) above, and evaluated according to methods 4) and (5).

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 Examples 2 to 3 The same procedures as Examples 1 and 2 were carried out except that no surface treatment was performed in Examples 1 and 2.

The results are shown in Table 1. Examples 3 to 4, Comparative Examples 4 to 5 The same procedures as in Examples 1 and 2 were carried out except that in Examples 1 and 2, a treatment liquid having the composition shown in Table 1 was used as the surface treatment liquid.

The results are shown in Table 1. Examples 5 to 6 In Examples 1 and 2, medium density polyethylene (manufactured by Mitsui Petrochemical Industries, Ltd., trade name: NEOSEX 45150, density 0.944, M
Modified polyethylene obtained by graft copolymerizing maleic anhydride with Il5) by a melt-kneading method (1 maleic anhydride component unit
Example 1 except that 0.01 mmol per 7 was used alone and a surface treatment liquid with the composition shown in Table 1 was used.
and 2.

Claims (1)

[Claims] 1. Surface treatment of iron or iron-containing alloy with a surface treatment liquid containing phosphoric acid, a zinc compound, and a calcium compound, followed by lamination of a modified polyolefin or a composition of modified polyolefin and unmodified polyolefin. A lamination method with excellent salt water peeling resistance. 2. The method according to claim 1, wherein an aqueous solution containing phosphoric acid, a zinc compound, and a calcium compound is used as the surface treatment liquid. 3. The method according to claim 1 or 2, characterized in that a zinc salt of phosphoric acids, a zinc salt of an inorganic acid, or zinc oxide is used as the zinc compound contained in the surface treatment liquid. 4. The method according to any one of claims 1 to 3, characterized in that a calcium salt of phosphoric acids, a calcium salt of an inorganic acid, or calcium oxide is used as the calcium compound contained in the surface treatment liquid. 5. The method according to claims 1 to 4, characterized in that a surface treatment liquid having a pH in the range of 2.0 to 3.7 is used. 6 As a surface treatment liquid, the pH is in the range of 2.0 to 3.7, the concentration of the zinc compound is in the range of 1 to 10 g ions/l as zinc ions, and the concentration of calcium ions is in the range of 0.0 to 10 g ions/l as calcium ions. 6. A method according to claims 1 to 5, characterized in that a surface treatment liquid is used in which the atomic ratio of calcium to zinc is in the range 1 to 5 gram ions/l and in the range 0.1 to 1. 7. The method according to claims 1 to 6, 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. 8. The method according to any one of claims 1 to 7, characterized in that a surface treatment liquid containing a surface treatment accelerator in addition to phosphoric acid, a zinc compound, and a calcium compound is used as the surface treatment liquid. 9. The method according to any one of claims 1 to 8, characterized in that a chromate treatment is performed as a post-treatment after surface treatment of iron or an iron-containing alloy. 10. The method according to claims 1 to 9, characterized in that a modified polyolefin produced by graft copolymerization of an unsaturated carbonic acid or its anhydride is used as the modified polyolefin. 11. The method according to claims 1 to 10, characterized in that a modified polyolefin produced by graft copolymerization of maleic anhydride is used as the modified polyolefin. 12 Add a modified polyolefin or a composition of a modified polyolefin and an unmodified polyolefin containing a modified monomer component in the range of 5 x 10^-^3 to 1 mmol per gram to surface-treated iron or iron-containing alloy. The method according to any one of claims 1 to 11, characterized in that the method comprises laminating layers. 13 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. 12 ways.