JPH01278580A - Under-coating composition - Google Patents

Abstract

PURPOSE:To provide the subject composition containing amorphous alloy powder and a binder, capable of giving a resin-coating layer having excellent adhesivity to metals and useful for the coating of a metal with a resin. CONSTITUTION:The objective composition contains (A) amorphous metal powder (e.g. Fe-Cr-Mo alloy containing amphoteric element such as P, C or Si) and (B) a binder (e.g. crosslinkable oligomer such as polyimide or polyester, or lithium polysilicate) at a weight ratio of preferably 100:25-400. A coated metal having excellent adhesivity between a coating resin and the metal can be produced by coating the surface of a metal with a resin using the above composition as an under-coating agent. The coated metal is suitable as a material required to have chemical resistance, e.g. pipes and containers of chemical plants.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an undercoat composition that provides a resin coating layer with excellent adhesion to metal.

(Prior Art) When coating a metal with a resin, there is a method of, for example, subjecting the metal to a chemical conversion treatment in order to improve the adhesion of the resin to the metal. Zinc phosphate or the like is used for chemical conversion treatment.

However, a treated layer formed by chemical conversion treatment lacks heat resistance. For this reason, after coating the metal surface with a chemical conversion treatment with a resin, the treatment layer deteriorates due to the heating during baking.
Adhesion between resin and metal is impaired.

In order to solve these drawbacks, a method has been proposed in which the metal is undercoated using an undercoat. Special Public Service 1984-
Japanese Patent No. 44912 discloses an organic primer such as a polyamide-imide resin or a polyimide resin as an undercoat composition for coating metal with a fluororesin.

However, since these organic primers are composed only of organic materials, there is a large difference in coefficient of linear expansion from that of metals.

Therefore, after undercoating with this organic primer,
If the resin is coated, long-term adhesion between the resin and the metal cannot be obtained.

Also, as a basecoat composition, a mixture of micronized particles of zinc and a heat-stable binder such as a polyalkyl silicate (
Also known are compositions containing granular aluminum powder, granular zinc powder, and alkyl silicate condensate (disclosed in JP-A-54-29340). An undercoat composition in which metal powder, especially aluminum powder, is added to polyalkyl silicate or the like improves the adhesion between fluororesin or polyphenylene sulfide resin and metal. However, since aluminum and zinc do not have very good corrosion resistance or water resistance, they do not provide sufficient long-lasting adhesion between the resin and the metal. Even if metal oxide powder such as iron oxide or titanium oxide is used instead of metal powder, corrosion resistance of the coating layer can be obtained, but the adhesion to the metal is insufficient.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and its purpose is to provide an undercoat composition that provides a resin coating layer with excellent adhesion to metal. It is about providing.

(Means for Solving the Problems) The present invention uses an amorphous alloy powder instead of metals and metal oxides contained in conventional undercoating compositions, thereby providing excellent adhesion to metals, corrosion resistance, and heat resistance. This invention was completed based on the inventor's knowledge that an undercoat layer having good properties, water resistance, and chemical resistance can be obtained, thereby improving the adhesion between the coating resin and the metal.

The undercoat composition of the present invention is an undercoat composition for coating a metal with a resin, and contains an amorphous alloy powder and a binder, thereby achieving the above object.

As the amorphous alloy powder, Fe-Cr-Mo series containing amphoteric elements such as P, C, and Si (Japanese Patent Application Laid-Open No.
113354), etc. are used.

These amorphous alloy powders have excellent corrosion resistance, heat resistance, and chemical resistance. Such an alloy powder can be produced by heating and melting a compounded material, injecting it by a method such as a spray method, a cavitation method, or a rotary liquid injection method, and then cooling it.

The particle size of the amorphous alloy powder is 100 μm or less, preferably in the range of 0.5 to 20 μm.

When the diameter exceeds 100 μm, the dispersibility of the amorphous alloy powder in the undercoat composition decreases. If the particle size is too small, the anchoring effect with the coating resin may be lost and adhesiveness may be reduced.

Examples of the binder include organic binders such as crosslinkable oligomers such as 3-polyimide, polyamideimide, epoxy resin, phenol resin, and polyester; polyetherketone, polysulfone, polyparabanic acid, polyetherimide, and polyester. Linear polymers such as ether ketone, polyphenylene sulfide, and nylon; and fluororesins. Inorganic binders include lithium polysilicate, aminosilicate, alkyl silicate,
Examples include silicon dioxide colloid. The binder includes
It is preferable that the resin contains the same type of resin as the resin coated on the metal. For example, if the coating resin is a fluororesin, the fluororesin is used as the binder.

1 part by weight of binder per 100 parts by weight of amorphous alloy powder
It is contained in a range of 5 to 900 parts by weight, preferably 25 to 400 parts by weight. If the amount is less than 15 parts by weight, the adhesion of the undercoat composition to metal will decrease. If it exceeds 900 parts by weight, lasting adhesion cannot be obtained. The amorphous alloy powder and binder are generally dissolved in a solvent for the binder to form an undercoat composition.

The undercoat composition of the present invention is used as an undercoat for coating metals (eg, iron, aluminum, stainless steel, various alloys) with resin.

Examples of the resin include resins used in the above organic binders, such as fluororesins, engineering plastics, special engineering plastics, epoxy resins, and phenol resins.

Using this undercoat composition, a metal is coated with a resin in the following manner, for example, to form a coated metal body.

A metal surface is coated with an undercoat composition of the present invention. The coated surface is then baked to form an undercoat layer.

The baking temperature is preferably 100 to 250°C. The layer thickness of the undercoat layer is 5 to 100 μm, preferably 10 to 30 μm
The range of If it is less than 5 to .mu.m, the undercoat layer will not be formed uniformly, and pinholes and cranks will likely occur. When it exceeds 100μm, the adhesion between the undercoat layer and the metal =
6- Sexuality decreases. The undercoat layer is further coated with a resin. As a coating method, a powder coating method using resin powder, a coating method using a resin solution or an organosol, etc. are adopted. The coated surface is baked (-t LJ) to form a resin coating. The thickness of the coating layer is in the range of 50 to 2000 μm, preferably 250 to 750 pm. If it is less than 50 μm, the coating layer is not formed uniformly, and pinballs and cranks are likely to occur.If the thickness exceeds 2,000 μm, it will take time to bake, etc., and foaming will occur, making it impossible to obtain a dense resin coating layer.

(Function) Amorphous alloy powder has excellent m1 corrosion resistance, heat resistance, water resistance, and chemical resistance. Therefore, the layer of the undercoat composition obtained by binding such alloy powders with the binder as described above maintains its adhesion to the metal and the coating resin.

(Example) The present invention will be described below with reference to examples.

Mottled amorphous alloy powder (particle size 5 μm or less) (component weight ratio; Fe/Cr/Mo/P/C=69/11/9/9/
2. Manufactured by Kobe Steel) 20 parts by weight Tetrafluoroethylene-hexafluoropropylene copolymer (pulverized to an average particle size of 10 μm or less by freeze-pulverization) 5 parts by weight Amino bismaleimide resin 5 parts by weight N-methyl-- 2-pyrrolidone
10 parts by weight of the above formulation was blended and mixed uniformly to prepare an undercoat composition.

A 100 mm x 100 mm x 3 mm iron plate was grid blasted and then cleaned by blowing compressed air.

The above-mentioned undercoat composition was applied to this iron plate with a brush, and the coated surface was dried and baked at 200°C for 1 hour and 34°C for 30 minutes. The average layer thickness of the obtained undercoat layer was 30 μm. In this undercoat layer, a powder of a lafluoroethylene-hexafluoro-copropylene copolymer was applied at an electrostatic voltage of 6
(After powder coating with EV and baking at 340°C for 1 hour,
A resin coating layer was formed by cooling with water. The average thickness of the coating layer is 5
The peak was 00μ.

The adhesion between the resin coating layer of the obtained coated metal body and the metal was evaluated as follows.

(1) Peeling test Paint film peeling test (90°C peel strength test, JIS K-
6555), the peel strength of the coated metal body was measured at room temperature. As a result, the peel strength was 2.3 kg/cm.

(2) Hot water test After the coated metal body was immersed in hot water at 95°C for 100 hours, the state of the coating layer was observed, and no abnormality was observed.

Chinitis I Ethyl silicate #40 (Ethyl silicate monomer 5
100 parts by weight of molecular condensate, content calculated as S+Oz: 40% by weight) and 40 parts by weight of ethyl alcohol were placed in a glass reaction vessel, and while stirring and stirring, IN
After 1 part by weight of hydrochloric acid and 9 parts by weight of water were continuously added dropwise over 2 hours, the mixture was further stirred for 3 hours and left to stand for 20 hours to obtain an ethylsilicate condensate solution. Is this ethyl silicate metal shrinkage? The 8 liquid contains 5 ethyl silicate condensates.
It contained 0 parts by weight.

Ethylsilige I condensate solution 15 parts by weight Amorphous alloy powder 40 parts by weight Butyl cellosolve 5 parts by weight The above formulations were blended and mixed to obtain an undercoat composition.

Using this undercoat composition, an undercoat layer was formed on an iron plate in the same manner as in Example 1. However, the baking time at 200°C was 30 minutes. This undercoat layer was powder-coated with polyphenylene sulfide resin, baked at 380°C for 40 minutes, and then cooled with water to form a resin coating layer. The layer thickness of the coating layer was 500 μm.

The adhesion between the resin coating layer of the obtained coated metal body and the metal was determined by
When evaluated using the same method as in Example 1, the peel strength was 3.6 kg/cm, and no abnormality was observed in the hot water test.

Comparative Example ↓ A coated metal body was formed in the same manner as in Example 1, except that no amorphous alloy powder was used in the undercoat composition.

The adhesion between the resin coating layer of the obtained coated metal body and the metal was determined by
When evaluated using the same method as in Example 1, the peel strength was 1.4 kg/cm, and some blisters occurred in the hot water test.

Comparison fl A coated metal body was formed in the same manner as in Example 1, except that 5 parts by weight of titanium oxide was added to the undercoat composition instead of the amorphous alloy powder.

The adhesion between the resin coating layer of the obtained coated metal body and the metal was determined by
When evaluated by the same method as in Example 1, the peel strength was 1.2 kg/cm, and some blisters occurred in the hot water test.

Comparative Example λ A coated metal body was formed in the same manner as in Example 1, except that 5 parts by weight of aluminum powder (average particle size: 0 to 2071 m) was added to the undercoat composition instead of the amorphous alloy powder. .

The adhesion between the resin coating layer of the obtained coated metal body and the metal was determined by
When evaluated using the same method as in Example 1, the peel strength was 1.5 kg/cm, and some blisters occurred in the hot water test.

Comparison F1 A coated metal body was formed in the same manner as in Example 2, except that no undercoat composition was used and the iron plate was treated with a zinc phosphate solution.

The adhesion of the obtained coated metal body to the metal on the resin coating layer was determined by
When evaluated using the same method as in Example 1, the peel strength was 1.9 kg/cm, and in the hot water test, the coating layer was partially peeled off.

As is clear from the Examples and Comparative Examples, the undercoat composition of the present invention provides a coated metal body with excellent adhesion between the resin coating layer and the metal.

This coated metal body does not peel off the coating layer or generate blisters even in peel tests and hot water tests. A coated metal body formed using an undercoat composition that does not contain an amorphous alloy powder or an undercoat composition that contains a metal powder or a metal oxide in place of the amorphous alloy powder has a resin coating layer with a peel strength of 11 = It is small and causes blisters during hot water tests. Conventional coated metal bodies obtained by zinc phosphate treatment also have low peel strength of the resin coating layer, and part of the coating layer peels off in a hot water test.

(Effects of the Invention) Since the undercoat composition of the present invention contains the amorphous alloy powder as described above, it has good adhesion to metal.

Therefore, using this primer composition as a primer,
By coating a metal surface with a resin, a coated metal body with excellent adhesion between the resin and the metal can be obtained. This coated metal body is suitably used as a material that requires chemical resistance, such as pipes and containers for chemical plants.

Claims (1)

[Claims] 1. An undercoat composition for coating metal with a resin, the undercoat composition containing an amorphous alloy powder and a binder.