JPS61250067A - Powder primer for molten zinc-plated steel material - Google Patents

Abstract

PURPOSE:To provide the titled primer capable of giving cured coating films of high performance in adhesivity to molten zinc-plated steel material, corrosion resistance, moisture resistance, etc., comprising specific epoxy resin, aromatic diamine and non-toxic basic rust-resisting pigment in specified proportion. CONSTITUTION:The objective primer comprising (A) an epoxy resin with a softening point 40-150 deg.C, (B) an aromatic diamine with a melting point 40-180 deg.C (e.g., m-phenylenediamine) and (C) a non-toxic basic rust-resisting pigment (e.g., calcium borosilicate) in such amounts as to be 1-4 equivalent of the active hydrogen in such amounts as to be 1-4 equivalent of the active hydrogen in the amino group of the component (B) per equivalent of the epoxy group of the component (A) and 0.1-20pts.wt. per 100pts.wt. of the component (A), of the component (C).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to the field of anti-corrosion technology, and relates to a powder primer that provides long-term corrosion protection to hot-dip galvanized steel.

[Conventional technology]

Conventionally, various types of coatings have been applied to hot-dip galvanized steel to improve its appearance and corrosion resistance.
Initially, it has excellent adhesion to plated steel, but after several months or years, a chemical reaction progresses between the coating and the plating, causing loss of adhesion, causing blistering, peeling, and scaling. This often causes phenomena such as oxidation, which has become a problem.

For example, “Lead and Zinc” No. 83, May 1978, No. 9
In order to improve these problems, the page states that linseed oil, alkyd resin, or phenolic resin is added with zinc powder/
Painting with primers such as zinc dust/zinc oxide primer containing zinc oxide, vinyl oxide primer (etching primer), etc. is shown.

It is also known to apply a top coat based on calcium leadate, or a primer such as a red lead primer, a zinc chromate primer, an epoxy primer, a urethane primer, a chlorinated rubber primer, or a vinyl primer.

[Problem that the invention seeks to solve]

However, since zinc powder/TgR-coated zinc primer is a two-component type, both have a limited pot life, and since both use zinc compounds, It decomposes due to moisture in the air, resulting in poor coating performance such as corrosion resistance. Etching primers use anti-rust pigments containing toxic heavy metal compounds such as lead chromate and zinc phosphate, so they must be handled with great care. Furthermore, when a thermosetting top coating is used, there is a drawback that spraying often occurs at the interface with the primer, and particularly at high temperatures, spraying and peeling often occur, resulting in a decrease in corrosion resistance.

Top coats based on calcium leadate have limited color matching and are difficult to spray paint.

Primers such as red lead primer, zinc chromate primer, epoxy primer, urethane primer, chlorinated rubber primer, and vinyl primer have large variations in adhesion due to slight variations in composition, and coating performance such as corrosion resistance and moisture resistance. The problem is that it is inferior.

Additionally, top coats based on calcium leadate, red lead primers, zinc chromate primers, epoxy primers, urethane primers, etc. contain toxic heavy metal compounds such as calcium leadate, trilead tetroxide, and chromic acid. Because it uses rust pigment, extreme care must be taken when handling it.

[Means for solving problems]

In view of the above-mentioned current situation, the present inventors have conducted extensive research and found that
The following (A), (B) and (C) components are the main components, (
Contains 1 to 4 equivalents of active hydrogen of 7 amino groups of component (B) per 1 wax of epoxy group of component A), and 0 parts of component (C) per 100 parts by weight of component (A). .1 to 20 parts by weight of a powder primer for hot-dip galvanized steel (hereinafter referred to as powder primer) (A) An epoxy resin with a softening point of 40C or more and 150C or less (B) A melting point of 40C As described above, by coating the hot-dip galvanized steel material with aromatic diamine (C) non-toxic basic rust-preventing pigment of 180C or less, an excellent effect on the corrosion prevention of hot-dip galvanized steel material has been discovered, and the present invention has been completed. reached.

The epoxy resin used in the present invention has a softening point of 4.
0C or more and 150C or less, epoxy equivalent is 400-2
500 bisphenol A type epoxy resin, for example, Epicor 1001.1 manufactured by Yuka Shell Epoxy Co., Ltd.
002.1003.1004.1007.1055, Ciba Geigy Araldite 6071.6084.6
Examples include 097.7072.

In addition, these epoxy resins, or those that can be mixed with solid epoxy resins and have a softening point within the range of
DOW Chemical Company DEN438 etc. Phenol novolak type epoxy resin, Ciba, Iggy Company 1EcN1235
Cresol novolak type epoxy resin such as Dainippon Ink Chemical Industry? ■Hydrogenated bisphere/-A type epoxy resin such as Ebikuron #50 manufactured by Dow Chemical Company! It! Polyglycol-type epoxy resins such as DER732, petroleum-based resins such as Adekal Resin LPH-1060 manufactured by Kadenka Kogyo ■, etc. can also be used.

It should be noted that if the softening point of component (A) is less than 40C, it is difficult to use the resin in powder form, and conversely, if it exceeds 150C, the viscosity when melted becomes high and it cannot be used.

As an aromatic diamine, 1. Melting point is 40C or higher, 180
C or less and an active hydrogen equivalent of 10 to 100,
metaphenylenediamine, diaminodiphenylmethane,
Examples include diaminodiphenylsulfone.

Examples of non-toxic basic antirust pigments that maintain the pH in a slightly alkaline range and have a strong effect of converting gold 4 faces to non-@4 include calcium borosilicate and barium metaborate.

In the present invention, if the amount of component (B) is less than 1 equivalent per 1 equivalent of component (A), the curing speed will be slow and the crosslinking density of the coating will be low, resulting in poor coating performance such as corrosion resistance and moisture resistance. If the amount of component (B) exceeds 4 equivalents, the curing speed will be high, and coating properties such as coating film visibility, corrosion resistance, and moisture resistance will be poor.

Component (C) is 0.1 per 1 part by weight of component (A).
If the amount is less than the heavy weight part or exceeds 20 parts by weight, coating film performance such as corrosion resistance and moisture resistance will be poor.

The powder primer of the present invention includes other components such as coloring pigments such as titanium dioxide, carbon dioxide, red iron, cobalt blue, and phthalocyanine green, extender pigments such as barium sulfate, mica, zinc white, calcium metacitate, and calcium carbonate, and others. packaging agents, dispersants,
Ultraviolet absorbers etc. can be added.

These components are sufficiently melt-kneaded at 45 to 130 C using a melt mixing device such as an extruder, heated roll, or heated kneader, and after cooling, are pulverized and filtered.

A cured coating film can be obtained from the powder primer obtained as described above by heating it after application by a coating method such as an electrostatic coating method, a fluidized dipping method, or a thermal spraying method.

Furthermore, if necessary, a cold curing type or heat curing top coat can be applied thereon.

[For production]

The powder primer of the present invention uses an epoxy resin, a large excess of aromatic diamine, and a non-toxic basic anti-1'# pigment, so that the surface of the hot-dip galvanized steel material has a pH of 8 after film formation.
Since the base ratio is maintained at ~12, the elution of zinc is suppressed, and excellent effects are exerted on coating film fE such as adhesion, corrosion resistance, and moisture resistance.

〔Effect of the invention〕

By using the powder primer of the present invention, it is possible to obtain a cured coating film with excellent coating properties such as adhesion with hot-dip galvanized steel, corrosion resistance, moisture resistance, and glabella adhesion with various top coats. .

Also, since it uses a non-toxic chlorinated anti-rust pigment, no special care is required when handling it.

Further, even if there are fluctuations in the coating environment such as moisture in the air, the powder primer of the present invention exhibits excellent effects.

〔Example〕

Next, the present invention will be explained in more detail by giving practical examples and comparative examples. In the examples, parts are parts by weight, and parts by weight.

Examples 1 to 5 and Comparative Examples 1 to 4 Epicote 1004 shown in Table 1. Diaminone phenylmethane and the pigment were mixed for 1 minute using a Henschel mixer manufactured by Mitsui Miike Kokoki ■, followed by adding Regimix L and mixing again for 1 minute.

Next, the mixture was melt-kneaded using a Busco Kneader PR46 manufactured by Buss Co., Ltd. under the conditions of a bunle temperature of 50 to LooC, a screw temperature of 40 to 42C, and a screw rotation speed of 45 #pm, and after cooling, it was pulverized and passed to a size of 105 μm or less. A powder primer whose particle size was adjusted was obtained.

The obtained powder primer was degreased and chemically treated.
, 2 x 50 x 150 fl 1 m hot-dip galvanized steel was electrostatically coated and baked at 150'C for 20 minutes to obtain a cured coating of 40 μm each.

The test results of the obtained powder primer cured coatings are shown in Table 4.

Comparative Examples 5 to 8 After dispersing the pigments in all the base ingredients shown in Table 2 using a paint shaker until the NS becomes 7 or less, add all the remaining hardeners and mix thoroughly to form the primer. Obtained.

The obtained primers were used in Examples 1 to 5 and Comparative Examples 1 to
After coating with a spray gun on the same hot-dip galvanized steel material as in 4, it was baked at 80C for 20 minutes to obtain a cured coating film of 40 μm.

The test results of the obtained primer cured coatings are shown in Table 4.

Preparation and painting of top coat paint Use a paint shaker to divide all the base ingredients shown in Table 3 into fractions until the NS is 7 or less, then add the remaining curing agent and mix thoroughly to prepare the top coat paint. I got it.

The obtained top coat was applied with a spray gun onto the primer cured coatings obtained in the same manner as in the above Examples and Comparative Examples, and then baked at 150C for 2v4m to obtain a cured coating of 30μm in each case. Table 4 shows the test results of the resulting cured top coat film.

As is clear from Table 4, Examples 1 to 5 are excellent in coating film appearance, corrosion resistance, moisture resistance, etc. for both the primer alone and the total coating film of the primer and top coat.

On the other hand, in Comparative Example 2, both the brimer alone and the primer and topcoat were inferior in film protection, corrosion resistance, moisture resistance, etc., and in Comparative Example 1 and Comparative Examples 3 to 8, the brimer alone and the primer and topcoat were inferior. Both the overall coating film has poor corrosion resistance and moisture resistance.

Claims (1)

[Scope of Claims] The following components (A), (B) and (C) are the main components, and (
The active hydrogen of the amino group of the component (B) is contained in a ratio of 1 to 4 equivalents per 1 equivalent of the epoxy group of the component (A), and the component (C) is 0.1 equivalent per 100 parts by weight of the component (A). A powder primer for hot-dip galvanized steel, characterized in that it contains ~20 parts by weight. (A) Epoxy resin with a softening point of 40°C or higher and 150°C or lower (B) Aromatic diamine with a melting point of 40°C or higher and 180°C or lower (C) Non-toxic basic rust preventive pigment