JPH04300973A - Etching primer - Google Patents

Abstract

PURPOSE:To provide an etching primer containing a bisphenol epoxy resin, ortho phosphoric acid and aluminum condensed phosphate as essential components, exhibiting extremely prominent adhesivity to various metals, and maintaining the good adhesivity for a long period of time. CONSTITUTION:An etching primer contains (A) a bisphenol epoxy resin having an epoxy equivalent of 400-4000, (B) ortho phosphoric acid in an amount of 0.3-1.5 moles per gram equivalent of the epoxy group of the component A, and (C) aluminum condensed phosphate in an amount of 5-50 pts.wt. per 100 pts.wt. of the component A as an anticorrosive agent as essential components, and, if necessary, a body pigment, a coloring pigment, a silane coupling agent and an organic solvent.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an etching primer, and more particularly, the present invention relates to an etching primer.
This invention relates to an etching primer that exhibits high performance.

0002

[Prior Art] Conventionally, etching primers used for surface treatment of metals include: (1) wash primer (MIL-P-15328) whose main components are polyvinyl butyral resin, zinc chromate and phosphoric acid;
B), ■Bisphenol epoxy resin, aminosilane,
Primer made of epoxy silane and acid anhydride (Japanese Patent Application Laid-Open No. 1982-34774); ■ Primer made of bisphenol epoxy resin, aminosilane, monoepoxy compound, and isocyanate compound (Japanese Patent Application Laid-open No. 1-92275)
(No. Publication), ■Polyvinyl butyral resin, phenol resin, phosphoric acid-acetone-alcohol, heteropolyacid or metal salt thereof (Ca, Sr, Ni, Mn, Cu, Co)
(Japanese Unexamined Patent Publication No. 57-65763)
, (2) A primer consisting of polyvinyl butyral resin, phenol resin, epoxy, polyamide, aluminum phosphate, and phosphoric acid (Japanese Patent Application Laid-Open No. 109532/1983). All of these primers have good initial adhesion to metal, but when exposed to corrosive environments (e.g. underwater, high humidity environments, etc.), not only the primer itself but also the topcoat paint However, it has the disadvantage that it tends to cause blistering and reduce adhesion.

0003

[Problems to be Solved by the Invention] The present invention adheres well to various metals, and does not blister even when exposed to corrosive environments (for example, underwater, high humidity environments, etc.).
The object of the present invention is to provide a heat-drying etching primer that maintains good adhesion over a long period of time.

0004

[Means for Solving the Problems] As a result of extensive research to achieve the above object, the present inventors have developed a primer that is a mixture of bisphenol epoxy resin and orthophosphoric acid, and further contains condensed aluminum phosphate. It was discovered that the object could be achieved by coating the metal surface and heating it at 120 to 160°C for 10 to 30 minutes, thereby completing the present invention. That is, the present invention provides component (A): a bisphenol epoxy resin having an epoxy equivalent of 400 to 4,000, component (B): 0.3 to 1.5 mol of orthophosphoric acid per 1 gram equivalent of epoxy group in component A, and , (C
) Component: An etching primer containing 5 to 50 parts by weight of condensed aluminum phosphate as an essential component per 100 parts by weight of component A is provided.

The bisphenol epoxy resin used as component A of the etching primer of the present invention has an epoxy equivalent of 4.
00-4000, preferably 450-3000. As such A component, for example,
Epicote 1001 [Yuka Shell Epoxy Co., Ltd. trade name], Araldite 6084 [Ciba Geigy Co., Ltd. trade name],
DER667 [Dow Chemical Company product name], Epotote Y
D-019 [trade name of Toto Kasei Co., Ltd.] etc. can be used alone or in combination of two or more. If the epoxy equivalent of the bisphenol epoxy resin used in the etching primer of the present invention is less than 400, the storage stability of the etching primer and the water resistance of the coating film will decrease, and if it exceeds 4000, the adhesion to the substrate will decrease.

B used in the etching primer of the present invention
The action of orthophosphoric acid, which is a component, is that the epoxy groups at both ends of the epoxy resin react with the hydroxyl groups of orthophosphoric acid, which is an oxyacid, to form a type of chelated epoxy resin, which causes the bond between the coating film and the metal. Improves adhesion. It is important that the amount of orthophosphoric acid used is 0.3 to 1.5 moles, preferably 0.5 to 1.2 moles, per 1 gram equivalent of epoxy groups in the bisphenol epoxy resin as component A. If it is less than 0.3 mol, it will lack adhesion to the substrate, and 1.5
If the amount exceeds the molar amount, phosphoric acid becomes excessive, water resistance decreases, and blistering tends to occur. Condensed aluminum phosphate, component C, used in the etching primer of the present invention is used as a rust-preventing pigment. The amount used is 5 to 50 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the component A bisphenol epoxy resin. If it is less than 5 parts by weight, sufficient rust prevention and adhesion will not be obtained, and if it exceeds 50 parts by weight, the oil absorption will be large, resulting in a decrease in cohesive force when the top coat is applied over and over again, and will cause damage to the surface of the paint film. Gloss is often reduced.

[0007] In addition to the above-mentioned three essential components, the etching primer of the present invention may contain extender pigments, coloring pigments, silane coupling agents, organic solvents, and various additives, if necessary. Examples of extender pigments that may be added to the etching primer of the present invention if necessary include talc, barite, mica, calcium carbonate, and silica, which may be used alone or in combination of two or more. Examples of coloring pigments that may be added to the etching primer of the present invention as needed include titanium oxide, iron oxide,
Examples include chromium oxide and carbon black, which can be used alone or in combination of two or more.

Examples of the silane coupling agent to be added to the etching primer of the present invention, if necessary, include γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-(methacryloxypropyl)trimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N
-β (aminoethyl), γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, etc., and they can be used alone or in combination of two or more. Such a silane coupling agent acts as a binder between various components in the paint, such as pigments and resins, and as a component that improves the adhesion of the paint film to the object to be coated. Examples of organic solvents that may be added to the etching primer of the present invention as needed include aromatic hydrocarbons, ketones, esters, glycol ethers, alcohols, and aliphatic hydrocarbons, which may be used alone or in combination of two or more. can do.

[0009] Furthermore, various additives such as a lubricant, a suspending agent, and a plasticizer can be added. There are no particular limitations on the method for preparing the etching primer of the present invention, but for example, a mixture of bisphenol epoxy resin solution, condensed aluminum phosphate, pigment, etc. may be mixed with a ball mill, sand glider, etc. used for general paint manufacturing.
After dispersing to a particle size of 10 μm or less using an attritor, roll mill, etc., orthophosphoric acid and the remaining liquid raw materials may be mixed. The etching primer of the present invention may be applied by a known coating method such as spraying, brushing, dipping, shower coating, etc. to a dry film thickness of 1 to 10 μm, and then A good coating film can be formed by heating and drying at 160°C for about 10 to 30 minutes.

0010

[Examples] The present invention will be explained in more detail with reference to Examples and Comparative Examples. Examples 1 to 8 and Comparative Examples 1 to 7 Based on the compounding ratios shown in Table 1, epoxy resin solutions (
or PKHH solution), mix the pigment and condensed aluminum phosphate, and use a ball mill to reduce the particle size to 10 μm.
After dispersing until the concentration is below m, the remainder of the epoxy resin solution (or PKHH solution), additives, silane coupling agent, solvent, and 85% orthophosphoric acid aqueous solution are further mixed, and Examples 1 to 8 and Comparative Each primer of Examples 1 to 6 was prepared. Regarding Comparative Example 7, the primer used was US military standard,
A standardized product with a formulation based on MIL-P-15328B was applied.

[0011]

[Table 1]

0012

[Table 2]

Note 1) Bisphenol epoxy resin [trade name of Yuka Shell Epoxy Co., Ltd.] 90% xylene solution 2) Bisphenol epoxy resin [trade name of Yuka Shell Epoxy Co., Ltd.] 75% xylene solution 3) Bisphenol epoxy resin [ Dow Chemical Company product name] 40% xylene/cellosolve acetate solution 4) Bisphenol epoxy resin [Toto Kasei Co., Ltd. product name] 4
0% xylene/cellosolve acetate solution 5) Phenoxy resin [Union Carbide trade name] 40% methyl ethyl ketone solution 6) Teikoku Kako Co., Ltd.: K White #1057) γ-glycidoxypropyltrimethoxysilane [Shin-Etsu Chemical Co., Ltd.] Co., Ltd., KBM-403]

[0014] Each of the above primers was applied to a commercially available cold rolled steel plate (JIS G-3141
), hot-dip galvanized plate (JIS G-3141),
and aluminum plate (JIS H-4000A1050
P) was air-sprayed to a dry coating thickness of 3 to 5 μm, and then heated and dried at 140° C. for 30 minutes. Furthermore, the dry film thickness of melamine alkyd paint is 30~
After air spray painting to a thickness of 40 μm, 1
Each test piece was obtained by heating and drying at 50° C. for 30 minutes. The test piece obtained in this way was tested according to the following test method.
Initial adhesion test, moisture resistance test, and adhesion after moisture resistance test (
A secondary adhesion test was conducted. The physical properties of the coating films in Examples and Comparative Examples were measured using the following test method.

[0015] Initial adhesion test: grid test [JIS K
-5400 (1979) 6.15] and expressed as the number of remaining coating films. A score of 100 was considered a pass, and a score of 99 or less was a fail. Humidity resistance test: The appearance of the paint film was investigated after being exposed to a humid environment of 50°C and 100% RH (relative humidity) for one month.
．． The blistering density was shown according to the evaluation method of D-714-56, and evaluated as follows. ◎: No abnormality ○: Fair (pass) △: Medium (fail), * indicates a decrease in gloss. ×: Medium Dense XX: Dense Secondary adhesion test: Similarly, the adhesion after being exposed to a humid environment of 50°C and 100% RH for one month was tested and evaluated using the same method as the initial adhesion test. . The test results are shown in Table 2.

[0016]

[Table 3]

[0017]

[Table 4]

As is clear from the results in Table 2, the paints of the comparative examples did not give satisfactory results, but the examples of the present invention showed no improvement in the appearance of the paint film after the moisture resistance test or in the secondary adhesion. , it can be clearly understood that the performance of the etching primer of the present invention is excellent.

[0019]

[Effect of the invention] The etching primer of the present invention has extremely excellent adhesion to coated surfaces such as iron, zinc plating, aluminum, zinc-aluminum alloy, copper, copper alloy, and stainless steel. Moreover, even when exposed to a humid environment, it can maintain good adhesion without any blistering, making it very useful for surface treatment of various metal products under harsh conditions. In addition, as a convenient usage example when using a heat-drying paint as a top coat, first, apply the etching primer of the present invention,
It is also possible to apply a so-called two-coat, one-bake coating in which a top coat is applied after a few minutes and then heated and dried, which has the advantage of efficient coating.

Claims (1)

[Claims] Claim 1: Component (A): Epoxy equivalent is 400 to 40
00 bisphenol epoxy resin, component (B):
0.3 to 1.5 per gram equivalent of epoxy group in component A
An etching primer containing as essential components mol of orthophosphoric acid and component (C): 5 to 50 parts by weight of condensed aluminum phosphate per 100 parts by weight of component A.