JPS5833902B2 - Metal pretreatment paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for coating metal surfaces, particularly non-ferrous metals such as aluminum and zinc, with a layer of paint between the surface of the metal and the paint layer, for the purpose of anti-corrosion and aesthetics. A thermosetting water-based metal pretreatment coating composition for intervening and imparting adhesion to each other.

Conventionally, thermosetting paints such as melamine-alkyd resin paints, melamine acrylic resin paints, phenol-epoxy resin paints, epoxy-polyamide resin paints, and polyurethane resins have been applied to non-ferrous metal surfaces such as aluminum and zinc for corrosion prevention or aesthetic purposes. Room temperature drying type paints such as paints and acrylic resin lacquers are used.

However, the adhesion of these paints to non-ferrous metals is significantly inferior to that of steel, and if these paints are applied to non-ferrous metal surfaces without any treatment, the paint film may naturally peel off over time. , there is a defect that the coating film comes off with a slight impact.

To prevent these defects, pre-painting treatments are carried out, for example by etching the non-ferrous metal surface by chemical treatment or by using alcohol-soluble polyvinyl butyral resin, alcohol, chromate and phosphoric acid as the basic components. A so-called etching primer was applied to form an etching film.

However, the above-mentioned etching primer composition contains a large amount of organic solvent, and the solid content at the time of coating is only about 10% by weight, and most of the composition is occupied by the organic solvent.

This current situation is not favorable from the viewpoint of resource conservation, disaster prevention, and safety and health, and an etching primer using water as a solvent has been desired.

The present inventor has already filed an application for a composition comprising a water-soluble polyvinyl alcohol resin and/or a water-soluble polyvinyl acecool resin, an oxyacid salt and/or a metal oxide, and phosphoric acid. However, the long-term durability of the coated film was somewhat problematic.

Subsequently, as a result of intensive research, it was found that the metal paint of the present invention has excellent long-term durability and adhesion to non-ferrous metals, and contains either no organic solvent in the composition, or even if it does contain it, it contains significantly less organic solvent than known similar paints. This led to a treated coating composition.

That is, the present invention includes: (1) (a) (a) Water-soluble polyvinyl alcohol resin and/or water-soluble polyvinyl butyral resin having a degree of saponification of 86 moles or more and/or a water-soluble polyvinyl butyral resin of 99 to 50 moles or more.

(0) Water-soluble phenol resin or water-soluble melamine resin having a methylol group or an alkoxymethylol group 1
-50% by weight resin composition.

(b) at least one compound selected from aluminum phosphate, zinc phosphate, zinc molybdate, and zinc chromate; and (c) phosphoric acid. A thermosetting water-based metal pretreatment paint composition. and (2) (a) (a) water-soluble polyvinyl butyral resin 80 to 60% by weight, and water-insoluble polyvinyl acecool resin and/or water-insoluble polyvinyl alcohol resin with a saponification degree of 70 molar or less Water-soluble phenol resin or water-soluble melamine resin having a methylol group or alkoxymethylol group 1
A resin composition consisting of ~50 weight cakes.

(b) at least one compound selected from aluminum phosphate, zinc phosphate, zinc molybdate, and zinc chromate; and (c) a thermosetting water-based metal pretreatment paint characterized by being free from phosphoric acid. Regarding the composition.

The water-soluble polyvinyl alcohol resin used in the present invention has a degree of saponification of 86 moles or more and is soluble in cold or hot water.

Above all, from the viewpoint of coating work viscosity, the average degree of polymerization is 1,500.
The following are more preferred.

For example Solsiden DF-107, DF-108, DF-
605N, DF-690, DF-69ON, DF-4
02, Denka Poval -20, K-17, -05,
B-17R, W-24, B-24, B-20, B-
05, [trade names manufactured by Denki Kagaku Kogyo ■], Kuraray Bobber/1zPVA-105, PVA-107.

PVA-110, PVA-204, PVA-205.

PVA-210, PVA-217 [Jl±■ Kuraray product name], Hi-Selon H, Hi-Selon S, Gohsenol N
H-20, NH-18, GH-17.

Commercially available resins such as GH-05 (trade names manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) can be used.

These resins can be used alone or in combination.

The water-soluble polyvinyl butyral resin used in the present invention is
It is a resin that is soluble in cold water or hot water, and generally has a degree of butyralization of 9 moles φ or less.

For example, commercially available resins such as Eslec W2O1 and Eslec W2O2 (trade name, manufactured by Tsukizui Kagaku Kogyo) can be used.

The water-soluble polyvinyl butyral resins of the present invention can be used alone or in combination of two or more to bring out the characteristics of each resin.

The water-insoluble polyvinyl acecool resin and water-insoluble polyvinyl alcohol resin used in the present invention are those that can be dissolved or dispersed in a solvent containing an organic solvent as a main component.

The water-insoluble polyvinyl alcohol resin must have a saponification degree of 70 molar or less, and preferably an average polymerization degree of 1,500 or less from the viewpoint of solution viscosity.

Examples of the water-insoluble polyvinyl acecool resin include polyvinyl formal resin, polyvinyl acetoacetal resin, and polyvinyl butyral resin. degrees 250-2,000. Preferably 25
It is a polyvinyl butyral resin having a degree of butyralization of 0 to 1,000 degrees and a degree of butyralization of 57 to 707 mm, preferably 57 to 70 mm.

When the water-soluble polyvinyl butyral resin and water-insoluble resin are mixed and used, the ratio is 80 to 6
The amount of water-insoluble resin is 20 to 40 weight φ relative to 0 weight.

In the present invention, if the amount of water-insoluble resin increases by 40% by weight, the solvent content will inevitably increase, which will not meet the purpose of the present invention, which is not preferable.

Therefore, in practical terms, the content of the water-insoluble resin is preferably 40% by weight or less.

By using a water-insoluble resin in the present invention,
It has the effect of further stabilizing the adhesion of the film.

In the present invention, a water-soluble phenol resin or a water-soluble melamine resin having a methylol group or an alkoxydimethylol group, which reacts with a water-soluble polyvinyl alcohol resin and/or a water-soluble polyvinyl butyral resin during heating, is essential.

(Hereinafter, these resins will be referred to as reactive resins.

) The mixing ratio of these reactive resins and the water-soluble polyvinyl alcohol resin and/or polyvinyl butyral resin, or the resin of the reactive resin, the water-soluble polyvinyl butyral resin, and the water-insoluble polyvinyl alcohol resin and/or polyvinyl acecool resin. The mixing ratio with the mixture is 1 to 50 parts by weight for the former, 99 to 50 parts by weight for the latter, and preferably 10 to 300 to 30 parts by weight for the former, and 90 to 70 parts by weight for the latter.
0 to 70 parts by weight.

If the amount of the reactive resin is less than 1 part by weight within this range, the crosslinking density of the film during heating will not be sufficient and the effect of improving water resistance will not be observed.On the other hand, if more than 500 parts by weight is used, polyvinyl vinyl /L/ 7 /L/ The original flexibility of the coal resin and polyvinyl acecool resin is lost, and the coating becomes hard and brittle, resulting in poor mutual adhesion when a coating is applied over the coating. This is not preferable because it causes a decrease in adhesion to the metal surface.

Further, in the composition of the present invention, aluminum phosphoric acid (including condensed phosphoric acid) is used.

Contains at least one compound selected from zinc phosphate (including condensed phosphoric acid), zinc molybdate, and zinc chromate as an essential component.

The above compounds can be used alone or in combination in any proportion.

The amount of the above-mentioned compounds used in the present invention must be uniformly specified because there are differences in their water solubility, anticorrosion properties, etc. For example, zinc chromate has a large effect even in a small amount. However, for example, the amount of the compound added to 100 parts by weight of the resin composition is 1 to 350 parts by weight, preferably 1 to 200 parts by weight, and if the amount of the compound is less than 1 part by weight, no antirust effect can be expected. First, if the amount exceeds 350 parts by weight, the adhesion of the coating to the metal surface tends to be impaired.

Further, in the present invention, phosphoric acid is used as an essential component, and the amount of phosphoric acid added is 5 to 50 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the resin composition.

As described above, the present invention uses polyvinyl alcohol resin and/or polyvinyl butyral resin, the above-mentioned compound, phosphoric acid, and, if necessary, a reactive resin as essential components, so that each of these parts exhibits a chemical reaction with each other, and aluminum, zinc, etc. It is thought that this provides stronger adhesion to the plated surface.

In the present invention, the above-mentioned composition is an essential component, but it is also possible to add other resins that are compatible with the resin of the thin ice invention within a range that does not impair the purpose of the present invention. If desired, other pigments such as extender pigments or coloring pigments, anti-settling agents, anti-sagging agents, surfactants, preservatives, foaming agents, additives such as surface conditioners, and other additives to further enhance the rust prevention properties of the coating. Coupling agents, chelate compounds, etc. can also be added.

The thermosetting water-based metal pretreatment coating composition of the present invention is a base material made of a polyvinyl alcohol resin and/or a polyvinyl butyral resin, a reactive resin, the above compound, water, an organic solvent, and other materials if necessary. Then, prepare a separately prepared phosphoric acid solution by mixing it with the main ingredient before use, then brush or spray.

It is applied to objects to be coated, such as iron, aluminum, zinc, etc., by a conventional method such as a roll coater.

Next, after maintaining an appropriate setting time to allow the solvent in the film to scatter, it is heated under the conditions necessary for the reaction between the polyvinyl butyral resin and/or polyvinyl alcohol resin and the reactive resin, such as at 120 to 230°C for 10 to 30 minutes. Heat to a certain degree and solidify.

The film thus obtained provides an excellent rust-preventing film that firmly adheres to the metal due to the synergistic effect of the resin, the above-mentioned compound, and phosphoric acid.

Although it is possible to utilize the film thus obtained as a temporary rust-preventive film, it is also possible to overcoat another film on the film of the present invention, if desired.

At this time, it is possible to apply another coating on the coating obtained by solidifying by the above-mentioned method, or to apply another coating on the unreacted coating before heating and then heat it. It is also possible to simultaneously react and solidify the overcoated coatings on the coating.

The coating film obtained by the composition of the present invention has an etching effect on the surface of non-ferrous metals and an anti-corrosion effect (which is easily removed).The solvent in the composition does not contain any organic solvent, and even if it contains it, the Compared to conventional metal treatment paints, it has less pollution, prevents pollution, and saves resources.

Its industrial value in terms of disaster prevention is extremely high.

Hereinafter, the details of the present invention will be explained with reference to Examples.

In addition, "parts" or "φ" in actual cases and comparative examples indicate "parts by weight" or "weight φ".

[Creation of non-water soluble resin liquid A]

Polyvinyl butyral resin [manufactured by Tanemizu Chemical Industry ■Product name:
Eslec BL-2) 12.5 parts, ethanol 47.5 parts
A mixed solution containing 40.0 parts of isopropanol and 40.0 parts of isopropanol was prepared.

[Creation of paint A]

40 parts of phthalic acid resin [manufactured by Hitachi Chemical Co., Ltd. Part name: Phthal Gyutsudo 133-60: Non-volatile content 60] Melamine resin [Product name manufactured by Hitachi Chemical Co., Ltd.: Melan 22: Non-volatile content 60
%] 20 parts, titanium oxide 25 parts, t% silicon solution 0.
1 part, isobutyl alcohol 2 parts, Tsurpets #100
A composition obtained by uniformly mixing and dispersing 13 parts of
Paint A was obtained by adjusting the viscosity (viscosity measured by Ford cup #4 for 30 seconds) using a mixed solvent of 10 parts by weight.

[Creation of paint B]

Acrylic resin (manufactured by Inu Nippon Ink Chemical Co., Ltd., trade name: Niacridic A-125-50: non-volatile content 50%) 30 parts, dioctyl phthalate 2 parts, 1 part 4 seconds Nitrified cotton 8 parts, carbon black 1 part, toluene 15 parts, ethyl acetate 15
Paint B was obtained by uniformly mixing and dispersing 10 parts of inbutanol, 9 parts of butyl cellosolve, and 10 parts of methyl isobutyl ketone using a roll mill.

[Creation of paint C]

Acrylic resin [manufactured by Hitachi Chemical ■Product name: Hitaloid 2
405: 75 parts of non-volatile content 50%, 19 parts of melamine resin [same as paint A], 0.1 part of 1% silicone solution, 2 parts of isobutyl alcohol, and 4 parts of Tsurupetz #100 were uniformly dispersed by stirring with a disper. The resulting composition was mixed with Tsurpetz #100 Nibutyl Cellosolve-90:10
Paint C was prepared by adjusting the viscosity (viscosity measured by Ford Cup #4 in 25 seconds) using a mixed solvent mixed in parts by weight.

Example 1 A composition of /161 to 7 was coated with the formulation shown in Table 1 on a polished mild steel plate that had been degreased with a solvent to a dry film thickness of 15 microns, and after setting at room temperature for 60 minutes,
The film was solidified by heating at 80° C. for 15 minutes, and the resulting test material was exposed outdoors for 12 months, after which the degree of rust on the surface of the film was examined.

The results are shown in Table 2. Example 2 The compositions of 7F61 to 7 shown in Table 1 were coated on a solvent-degreased aluminum plate to a dry film thickness of 10 μm, and after setting at room temperature for 60 minutes, the coating was heated at 150°C.
The coating was solidified by heating for 10 minutes.

Next, the paint A was applied to the surface of the film to a dry film thickness of 25 microns, and after setting at room temperature for 30 minutes, it was heated at 140°C for 20 minutes to solidify the paint A film.

Using the thus obtained test material, a cutter knife was used to cut 11 vertical and 11 horizontal lines that reached the substrate on the surface of the coating film at intervals of 11 nm and 11 L to create a total of 100 squares.

Next, cellophane tape is pressed onto the squares, and the number of squares remaining after forced peeling is read and expressed as a percentage as the primary adhesion of the coating film.

Next, the test materials that had undergone the primary adhesion test were exposed outdoors for 12 months, and then an adhesion test was conducted according to the method described above to examine the secondary adhesion of the coating film.

The results are shown in Table 3. Example 3 The compositions Nos. 1 to 7 shown in Table 1 were coated on a solvent-degreased aluminum plate to a dry film thickness of 10 microns.
After setting at 50℃ for 30 minutes, set at 180℃ for 1
The coating was solidified by heating for 0 minutes.

Next, the paint B was applied to the surface of the film to a dry film thickness of 20 microns, and the paint B film was allowed to stand for 7 days at room temperature to solidify, thereby obtaining a test material of Example 3.

Using the thus obtained test material, secondary adhesion and secondary adhesion were evaluated according to the procedure and method of Example 2.

The results are shown in Table 3. Example 4 The compositions /161 to 7 shown in Table 1 were coated on a solvent-degreased aluminum plate to a dry film thickness of 10 microns, and after being left at room temperature for 24 hours, the paint C was applied to a dry film thickness of 10 microns. The film was coated to a thickness of 25 microns, set at room temperature for 30 minutes, and then heated at 150°C for 30 minutes to solidify the film of the present invention and the paint C film to obtain a test material of Actual Example 4.

Using the test material thus obtained, primary adhesion and secondary adhesion were evaluated in accordance with the procedure and method of Actual Example 2.

The results are shown in Table 3. Comparative Example 1 Using a composition consisting of 40 parts of Eslec W2O2 (same as the actual example), 8 parts of Pryophen P-138 (same as the actual example), and 52 parts of water, treated in the same procedure as the actual example 1,
It was subjected to a comparative test with Actual Example 1.

Comparative Example 2 10 parts of Kuraray Bobal PVA-107 (same as the actual example), 1.5 parts of Cymel #300 (same as the example), 88 parts of water
．． A composition consisting of 5 parts was processed in the same manner as in Example 1 and subjected to a comparative test with Actual Example 1.

Comparative Example 3 Main ingredient consisting of 8 parts of water-insoluble phenolic resin, 9 parts of water-insoluble polyvinyl butyral resin, 5 parts of zinc borate, 5 parts of zinc molybdate, 11 parts of butyl alcohol, 30 parts of isopropyl alcohol, and 32 parts of triol. After mixing 20% of an additive consisting of 18 parts of 85% phosphoric acid, 16 parts of water, and 66 parts of isopropyl alcohol with 80 strips, it was coated on a mild steel plate to a film thickness of 15 microns, and heated at 20°C and 75%
After drying in a RH room for 3 days, it was subjected to a comparative test.

Comparative Example 4 The composition of Comparative Example 1 was treated according to the same procedure as Example 2,
A comparative test with Actual Example 2 was provided.

Comparative Example 5 The composition of Comparative Example 2 was treated according to the same procedure as Example 3,
It was subjected to a comparative test with Example 3.

Comparative Example 6 Paint A was applied to a solvent-degreased aluminum plate to a dry film thickness of 25 microns, set at room temperature for 30 minutes, and then heated at 140°C for 20 minutes to solidify the paint A film. As a result, a sample material of Comparative Example 6 was obtained.

Using the thus obtained test material, secondary adhesion and secondary adhesion were evaluated in the same manner as in Example 2.

Comparative Example 7 The paint B was coated on a solvent-degreased aluminum plate to a dry film thickness of 20 microns, and the paint B film was allowed to solidify by being left at room temperature for 7 days to obtain a test material of Comparative Example 7. .

Using the sample material thus obtained, secondary adhesion and secondary adhesion were evaluated in the same manner as in Practical Example 2.

It is clear from the above comparison test result table that the coating film obtained from the coating composition of the present invention has excellent corrosion resistance and adhesion to nonferrous metals, and is a low-pollution water-based metal pretreatment coating. It is extremely useful industrially.

Claims (1)

[Scope of Claims] 1(a)(a) A water-soluble polyvinyl alcohol resin and/or a water-soluble polybutyral resin having a degree of saponification of 86 molar or more and 99 to 50% by weight. (b) Water-soluble phenol resin or water-soluble melamine resin having a methylol group or an alkoxymethylol group 1
A resin composition consisting of ~50 weight cakes. (b) at least one compound selected from aluminum phosphate, zinc phosphate, zinc molybdate, and zinc chromate; and (c) phosphoric acid. thing. 2 (a) K) Consists of 80 to 60 parts by weight of a water-soluble polyvinyl butyral resin and 20 to 40 parts by weight of a water-insoluble polyvinyl acecool resin and/or a water-insoluble polyvinyl alcohol resin with a degree of saponification of 70 moles or less Resin mixture 99-50% by weight. Most common) Water-soluble phenol resin or water-soluble melamine resin having methylol group or alkoxymethylol group 1
A resin composition consisting of ~50 weight φ. (b) at least one compound selected from aluminum phosphate, zinc phosphate, zinc molybdate, and zinc chromate; and (c) phosphoric acid. A thermosetting water-based metal pretreatment paint composition. thing.