JPH0422624A - Corrosion resistant coating method - Google Patents

Abstract

PURPOSE:To form a thick film by coating and to enhance the corrosion resistance, impact resistance or the like by respectively applying the first and second solventless type epoxy resin coatings one of which contains predetermined flaky metallic pigment and the other one of which contains hollow balloons having a predetermined particle size in predetermined dry film thicknesses. CONSTITUTION:The solventless epoxy resin coating containing flaky pigment composed of titanium, chromium or an alloy thereof is applied on a zinc rich primer layer applied on the surface of a metal in dry film thickness of about 500mum or more and the solventless epoxy resin coating containing hollow balloons having a particle size of about 10-100mum is applied thereon in dry film thickness of about 1000mum. The flaky pigment is compounded in an amount of about 30-60wt.% in order to impart the function as a shielding protective layer preventing the penetration of the corrosive substance from corrosive environment. When the content of said pigment becomes excessive, the physical strength of a film is lowered. the hollow balloons are compounded in an amount of 25-50vol.% in order to impart the function as a buffer layer for the impact of waves to the topcoating film.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a method for anti-corrosion coating of metals, especially for natural gas and oil mining platforms, rigs, sea berths, offshore plant barges, etc. The present invention relates to an anti-corrosion coating method suitable for preventing corrosion of marine steel structures in areas that are in contact with each other and repeatedly wet and dry.

<Prior Art and Problems to be Solved> As methods for anticorrosive coating of marine steel structures, the methods of applying tar epoxy resin paint and the method of applying resin mortar are conventionally known.

In order to maintain long-term corrosion protection in marine steel structures, especially in splash zones, an ultra-thick anticorrosion coating of 2 to 5 mm is usually required, and even higher impact resistance is required.

However, in the conventional method of applying tar epoxy resin paint, the film thickness is about 100 to 500 μm/coat, and therefore, the thickness is usually 4 to 10 μm/coat.
This has caused problems such as the need to apply it several times.

Further, there was also a problem that the resulting coating had insufficient impact resistance and the like.

On the other hand, the lining method using resin mortar is as follows:
Although it has the feature that the film can be thickened in one step, requiring fewer applications, it has poor painting workability, and the resulting film contains a large amount of aggregate, making it prone to voids, pinholes, etc. Therefore, it has become a problem that it is difficult to prevent the penetration of corrosive substances. Furthermore, since it lacks flexibility, it has had problems such as poor impact resistance in low-temperature environments.

In view of the current situation, the inventors of the present invention have made extensive studies to solve the problems of the conventional methods described above, and have developed an anti-corrosion coating method that enables thick film coating and has excellent impact resistance as well as corrosion resistance. This discovery led to the present invention.

<Means for solving the problem> That is, the present invention applies a zinc-rich primer to a metal surface, and applies a sweetened solvent-free epoxy resin paint containing flaky titanium, chromium, or an alloy pigment thereof. Apply a solvent-free epoxy resin paint containing hollow balloons with a particle size of about 10 to 100 μm to a dry film thickness of at least about 1000 μm. The present invention relates to an anticorrosion coating method characterized by the following.

The present invention will be explained in detail below.

The zinc-rich primer used in the present invention contains about 10 to 50% by weight (in terms of solid content) of an organic binder such as epoxy resin, chlorinated rubber, or silicone resin, or an inorganic binder such as alkali silicate or alkyl silicate. It is a primer containing about 90 to 50% by weight of zinc-rich primer, and any conventionally commonly used zinc-rich primer can be used without any particular restriction.

The solvent-free epoxy resin paint containing flake-like titanium, chromium, or their alloy pigments (hereinafter referred to as intermediate paint) used in the present invention consists of an epoxy resin, a curing agent, and the flake-like pigment, Furthermore, the paint contains other pigments, modifiers, additives, etc. as necessary.

The epoxy resin has at least two epoxy groups in one molecule, and is liquid at room temperature (preferably with a viscosity of 3 to 60).
PS) epoxy resin, specifically bisphenol
F-type epoxy resin, bisphenol F-type epoxy resin 1. Typical examples include novolac type epoxy resins, cycloaliphatic epoxy resins, glycidyl ester type resins, glycidyl amine type resins, or modified epoxy resins such as urethane modified epoxy resins, acrylic modified epoxy resins, and rubber modified epoxy resins.

Commercially available products include Epicron 840, 855, and S-129.
, 830 (manufactured by Dainippon Ink and Chemicals), Nipicote 801.802.807.815.819.825
．． 827.828.815XA, YL-983 (and above,
(manufactured by Yuka Shell Epoxy Co., Ltd.), Araldite GY250.
GY255, GY257, PY302-2, XB533
7, XB4122, XB5674, XJ4100, MY
790 (manufactured by Ciba Geigy), γ Dekaresin EP
-4200, EP-4400, EP-4520, EP-
4900 (manufactured by Asahi Denka Kogyo Co., Ltd.), Evotote YD-
124, YD-125, YD-126, YDF-16i
5, YDF-170 (D top, manufactured by Tobu Kasei Co., Ltd.), etc. It is appropriate that the epoxy resin be blended in an amount of about 15 to 45% by weight of the intermediate coating. Examples of the curing agent include aliphatic polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and dipropylene diamine; xylylene diamine, diaminodiphenylmethane,
Typical examples include aromatic polyamines such as phenylene diamine; alicyclic polyamines such as isophorone diamine and N-amine ethylpiperazine; polyamine epoxy resin adducts, polyamine-ethylene oxide adducts, ketimine, and polyamide resins.

The flake pigment is titanium, chromium, or an alloy containing these as main components, and has an average major diameter of 5 to 150 μm and an aspect ratio of 5 to 100. Incidentally, the flake-like pigment is preferably surface-treated with a titanium-based or silane-based coupling agent in order to improve adhesion and the like.

These flake pigments are blended to provide the intermediate paint film with the function of a barrier protective layer that prevents the penetration of corrosive substances from the corrosive environment. It is appropriate that the amount is about 30 to 60% by weight of the intermediate coating. If the blending amount is less than the above range, the above functions will not be fully exhibited, while if it is in excess, the physical strength etc. of the resulting film will tend to decrease.

In addition, aluminum,
Flake-like pigments such as stainless steel and nickel are known, but aluminum and stainless steel have poor salt water resistance, and nickel has a high specific gravity and impairs painting workability, so they are not preferred. The pigments that may be blended as necessary include anticorrosive pigments such as zinc chromate, strontium chromate, lead cyanamide, zinc tungstate, calcium tungstate, zinc molybdate, lead molybdate, aluminum phosphomolybdate, and condensed phosphate; Coloring pigments such as titanium oxide, carbon black, red iron, yellow lead; precipitated barium sulfate, calcium carbonate, talc,
Typical examples include extender pigments such as silica, bentonite, mica, graphite, glass flakes, and glass fibers. These pigments are used in intermediate coatings.
It is possible to mix up to about 0% by weight.

Typical self-modifiers include coumaron indene resin, xylene resin, chloroprene rubber, nitrile butadiene rubber, and petrolatum. These modifiers can be incorporated up to about 30% by weight in the intermediate coating. As the additives, various commonly used additives such as a silane coupling agent, a thixotropic agent, a surface conditioner, an antisettling agent, an antifoaming agent, and a curing accelerator can be blended.

The solvent-free epoxy resin paint containing hollow balloons (hereinafter referred to as top coat) used in the present invention consists of an epoxy resin, a curing agent, and hollow balloons, and further includes pigments, modifiers, and additives as necessary. It is a paint that contains additives, etc.

The composition of the top coat is the same as that of the intermediate coat, except that it contains hollow balloons as described below, removes (or reduces the amount of) the flake pigment, and contains about 20 to 80% by weight of epoxy resin. It consists of almost the same composition.

As the hollow balloon, a plastic balloon made of vinylidene chloride-acrylonitrile resin, acrylic resin, etc., or a glass balloon having a particle size of about 10 to 100 μm can be used. These hollow balloons are blended in order to provide the top coat with a function as a buffer layer for mitigating the impact of waves and the like.

The appropriate amount is 25 to 50% by volume in the top coat.

If the amount is less than the above range, the above functions will not be fully exhibited, and if it is in excess, the physical strength etc. of the resulting film will tend to decrease.

As mentioned above, since the top coat forms a film as a buffer layer, a flexible plastic balloon is particularly suitable as the hollow balloon. Furthermore, the elongation rate of the cured product of the epoxy resin as a binder and the curing agent is at least 5.
% or more is desirable.

Next, the anticorrosive coating method of the present invention will be explained.

First, as a first step, a zinc-rich primer is applied to a metal surface that has been subjected to a surface treatment such as blasting by means such as spraying so that the dry film thickness becomes 10 to 100 μm, and then dried.

Next, in a second step, the intermediate coating is applied onto the zinc-rich primer film by means such as spraying or using a roller to form a dry film thickness of at least about 500 μm or more, preferably 50 μm or more.
Paint to a thickness of 0 to 1000 μm and dry. In the film thus obtained, the flake-like pigments are stacked one on top of the other in the film and become dense, exhibiting a so-called barrier effect and preventing the penetration of corrosive substances and the like. The film thickness needs to be approximately 50'OA1 m or more in order to prevent the penetration of corrosive substances in seawater. On the other hand, even if the film thickness is 1000 μm or more, it is preferable from the perspective of preventing the penetration of corrosive substances, etc. However, even if the film thickness is 1000 μm or more, it is likely to be economically disadvantageous compared to the effects associated with an increase in thickness. , preferably 1000 μm or less.

Next, in a third step, the top coat is applied onto the intermediate coat by means of spraying, rollers, etc. in a dry film thickness of at least about 1000 μm or more, preferably 1000 to 20 μm.
Paint to a thickness of 00 μm and dry. In the coating obtained in this manner, the hollow balloon exerts a buffering effect, alleviating the impact of waves and the like, and preventing damage to the coating. The film thickness is approximately 1000 μm for impact resistance and prevention of damage to the film.
It is necessary that the number is greater than or equal to m. On the other hand, the film thickness is 2000
Even if it is 2000 μm or more, it is excellent in terms of improving impact resistance, but it is likely to be economically disadvantageous compared to the improvement effect obtained by making it 2000 μm or more.
The following are preferred.

<Effects of the Invention> The anticorrosion coating method of the present invention enables thick film coating with a small number of coatings by using a solvent-free epoxy resin paint, and also contains flakes of titanium, chromium, or chromium with good corrosion resistance in the intermediate coating. The combination of these alloy pigments prevents corrosive substances from penetrating into the metal surface, and the addition of hollow balloons in the top coat reduces external impact. Due to the synergistic effect of the coating, it has good long-term corrosion protection and durability, and is therefore an excellent method for coating objects under severe conditions such as marine steel structures.

<Examples> Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, "parts" and "%" are expressed on a weight basis.

A solvent-free epoxy resin paint was prepared by thoroughly stirring and mixing the base ingredients shown in Table 1 below, and then mixing the curing agent component before coating.

Note 1) Bisphenol F type epoxy resin [[Ehiclone #830J (manufactured by Dainippon Ink & Chemicals Co., Ltd.], epoxy equivalent 175, viscosity 30-40PS) Mixed epoxy resin of bisphenol F type epoxy resin and bisphenol A type epoxy resin [[ Araldite X
J4100J (manufactured by Ciba Geigy), epoxy equivalent 17
o1 viscosity 12-25PS] Acrylic modified epoxy resin [Cascon KR810J
(manufactured by Koei Chemical Co., Ltd.), epoxy equivalent: 225, viscosity: 3~
4PSE "Alpaste RTAO30J (manufactured by Toyo Aluminum Co., Ltd.), average particle size 20.1 μm [Alpaste RRA
030J (manufactured by Toyo Aluminum Co., Ltd.), average particle size 8.
8 μm Alpaste 1900XsJ (manufactured by Toyo Aluminum Co., Ltd.), average particle size 25 μm Vinylidene chloride-acrylonitrile copolymer balloon, average particle size 40 μm, specific gravity 2) Note 3) Note 4) Note 5) Note 6) Note 7) 0 .04 Note 8) Acrylic copolymer balloon, average particle size TOt
tm, specific gravity 0.02 Note 9) [Silicate glass balloon, average particle size 80 μm 1 specific gravity 0.15 Note 10) "Versamine DSx N5170" (manufactured by Henkel Hakusuisha), active hydrogen equivalent 60 Note) "Gascamin GE-03BJ (Mitsubishi (manufactured by Gas Kagaku Co., Ltd.), active hydrogen equivalent: 62 Examples 1 to 9
and Comparative Examples 1 and 2 Sandblasted steel plate (0.32X 150X 7
Apply epoxy resin-based zinc rich paint [Zettaal EP2J (manufactured by Dainippon Toyo Co., Ltd.)] to the film with a dry film thickness of 3.
It was airless spray coated to a thickness of 0 μm and dried at 20° C. for 1 day.

Next, apply intermediate coating paint (Table 2) in the order shown in Table 2.
1) was coated with airless spray, and 1 was applied at 20℃.
After drying for a day, a top coat (Table 1) was applied using an airless sprayer, and the surface was dried at 20°C for 1 day.
I created a painted board.

Comparative Example 3 Zinc-rich paint was applied and dried in the same manner as in Example 1, and then intermediate coat ■ was applied by airless spray to a dry film thickness of 1000 μm, dried, and then intermediate coat 1 was applied by airless spray. Dry film thickness 10
A coated plate was prepared by applying multiple coats to a thickness of 00 μm and drying.

Comparative Example 4 Zinc-rich paint was applied and dried in the same manner as in Example 1 using JISI, which is commonly used in the past.
A tar epoxy resin paint corresponding to the seed was applied by airless spraying to a dry film thickness of 500 μm and dried to prepare a coated plate.

The coated plates obtained in Examples 1 to 9 and Comparative Examples 1 to 4 were subjected to impact resistance tests and salt spray resistance tests, and the results are shown in Table 2.
It is shown in the bottom column.

As is clear from the test results, the coated plates of Examples 1 to 9 obtained by the method of the present invention all had good impact resistance and corrosion resistance.

On the other hand, in Comparative Example 1 where the top coat containing hollow balloons had a thin film thickness, rust occurred from the striking marks.

Furthermore, in Comparative Example 2 in which an aluminum pigment was used as the flake pigment, the impact resistance was good, but rust occurred from the striking marks.

Furthermore, in Comparative Example 3 in which the top coat containing hollow balloons was not applied, the impact resistance was poor.

Furthermore, in Comparative Example 4, which was coated with a conventional tar epoxy resin paint, the impact resistance was poor.

Claims (2)

[Claims] (1) Apply a zinc-rich primer to the metal surface, and apply a solvent-free epoxy resin paint containing flake-like titanium, chromium, or their alloy pigments to a dry film thickness of at least about 500 μm, An anti-corrosion coating method comprising: then applying a solvent-free epoxy resin paint containing hollow balloons with a particle size of about 10 to 100 μm to a dry film thickness of at least about 1000 μm or more. (2) The anticorrosive coating method according to claim (1), wherein the hollow balloon is a plastic balloon.