JPH0630723B2 - Long-term anticorrosion coating method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a long-term anticorrosion coating method for existing steel structures and facility atmospheric parts in, for example, marine areas and beach areas.

(Prior Art) First, to explain from the background of the present invention, repair painting of the atmospheric portion of offshore facilities such as oil drilling rigs, for example, living quarters, decks, various equipment, etc. is performed by the crew. Normally, these repair coatings are subject to environmental restrictions such as time, tools and pollution, and use hand tools and power tools to remove rust,
It is carried out in a process of applying a paint after cleaning the deteriorated coating film with a low-grade base material, cleaning it with air blow, dust blast, or the like. Most of the paints used are oil-based paints, and the number of times of application is 4 to 6 times because a thick film is advantageous.

However, the repair effect is not sufficient under severe conditions,
It is the actual situation that the repaired parts also have defects such as rusting and peeling within 1-2 years.

There are paints having higher corrosion resistance than oil-based paints, such as epoxy resin paints, polyurethane resin paints, and paints containing zinc dust. However, in order to exert its excellent anticorrosion property, careful surface treatment such as blasting to completely remove rust and old coating film is necessary, and even if these coating materials are applied to a low-grade surface treatment surface. It is not commonly used because it markedly reduces durability.

Therefore, conventionally, in consideration of repair coating, research on coating methods for bad ground such as rust surface has proposed various methods for directly applying a coating to a metal surface having a rust layer to prevent corrosion. The main ones of the mechanism are, for example, permeation-encapsulated form, ketimine, in which oil or resin having good fluidity such as animal oil, vegetable oil, fish oil, alkyd, petroleum resin, etc. is put in the composition to improve the permeability to rust layer. Using compounds and isocyanate compounds,
Moisture in the rust layer is removed to passivate the rust. Dehydrated, tannic acid, phenol derivative, chelate group-introduced epoxy, polyol resin is used to stabilize rust by chelation. Chelate conversion type, magnetic iron oxide is used to stabilize rust by magnetite conversion. There is a magnetite conversion type.

(Problems to be Solved by the Invention) However, although many paints incorporating these single or plural methods are commercially available, it is the current situation that they do not reach a stable effect and are not generally popular. .

The various proposals and commercial products, as a cause of not showing a stable effect, common proposals and coating compositions are due to air blow, dust baldness, etc. after a low-grade base treatment that leaves a rust layer or an old active film. This is considered to be due to the construction method in which cleaning is performed and the coating composition is immediately applied.

Explaining in detail in this respect, the first cause is that the cleaning method alone does not sufficiently remove harmful substances such as treated rust powder and deteriorated coating powder and sea salt particles contained in the residual rust layer and on the active film, Therefore, the treated rust powder and the deteriorated coating film remaining on the coated surface may hinder the adhesion, or the harmful substances may dissolve in the water that has penetrated the coating film.
It is considered that a corrosive liquid is generated to accelerate the deterioration of the coating film. It is also considered that, as another cause, in the case of this repair coating, the active film of the old coating film always remains, and a certain composition has poor adhesion to the old coating film.

In the known examples close to the conventional contents, there is no mention of the adhesion with the old coating film. Concerning the above-mentioned first cause, however, paying attention to the fact that washing with water is easy and effective as a pre-painting foundation adjustment, and also see the guideline (steel road bridge painting handbook) described in the construction manual. To be
However, when washing is performed with water, water remains in the residual rust layer and on the surface to be coated, which impedes the adhesion of the coating material, and thus often causes defects earlier.

Regarding the coating method for the above-mentioned bad ground surface, a method including adjustment of the base material has also been proposed (Japanese Patent Laid-Open No. 60-222176). However, this proposal also describes that a cleaning solution is applied, washed with high-pressure water, and then completely dried.

Many paints are sensitive to the wet state of the surface to be coated, and oil-based paints that are generally used at present have drastically reduced durability when applied to the wet surface. After washing with water, there is a problem in that it takes time to apply it after waiting for it to completely dry, and it does not meet the labor saving of the construction time required for repair painting.

Therefore, an object of the present invention is to propose a repairing method, that is, a long-term anticorrosion coating method, which can obtain a long-term anticorrosion effect within a range that can be applied in a simple and short-term manner required for repair coating.

(Means for Solving the Problem) A feature of the present invention is that after a low-grade base treatment, harmful substances on the surface to be coated are removed by washing with clean water, complete drying is not required, and coating is possible. The purpose is to apply a coating composition having good adhesion to both the active film and the active film.

Explaining this feature in detail, the rusting part and the deteriorated coating film part are subjected to a low-grade base treatment without using the blasting method, followed by washing with fresh water, and then applying the coating composition after this washing with water and before completely drying. The above-mentioned coating composition is a modified epoxy resin which is a reaction product of (A) an epoxy resin and an ester of a polyhydric phenolcarboxylic acid having an adjacent hydroxyl group or a formalin condensate, and (B) a polyvalent fatty acid. A polyamidoamine which is a reaction product with an aliphatic amine, (C) a scaly pigment, and (D) a solvent having an alcohol or glycol ether solvent having a solubility in water.

As described above, the present invention, after performing a low-grade base treatment on the repair part,
By washing with clean water, the treated rust powder, deteriorated coating film, and harmful substances such as sea salt particles are sufficiently removed, and then a solvent or polyamidoamine that has the ability to dissolve and replace water and the rust layer that adheres to the steel and chelate forming ability The gist of the invention is to apply a coating composition containing a modified epoxy resin having good adhesion to various old coating films and a scaly pigment excellent in blocking external factors.

The modified epoxy resin of the present invention is obtained by heat-treating an epoxy resin and a polyhydric phenolcarboxylic acid ester or formalin condensate containing an adjacent hydroxyl group in the presence of a solvent in a proportion such that an epoxy group remains.

As the epoxy resin, one having more than one glycidyl ether group in the molecule can be used, and the equivalent weight is not particularly limited, but preferably the epoxy equivalent weight is 200 to 10
Things around 00 are good. Examples of the phenolcarboxylic acid having an adjacent hydroxyl group include catechol-3-carboxylic acid, catechol-4-carboxylic acid, gallic acid m-digallic acid, pyrogallol-4-carboxylic acid, and pyrogallol-4,6-.
A carboxylic acid can be used, and these esters or formalin condensate derivatives are mixed in advance.

The reaction rate with the epoxy resin is the modified epoxy resin 1 produced.
The ratio should be such that an average of 0.05 mol or more, preferably 0.1 mol or more of the derivative is reacted and contained per molecule,
Also, the epoxy equivalent of the obtained modified epoxy resin is 3000
The following should be set. As such a modified epoxy resin, Adeka Resin EP manufactured by Asahi Denka Co., Ltd.
X-50-1, EPX-50-2, etc. can be used.

The polyamidoamine of the present invention is obtained by heat-treating a polyvalent fatty acid and an aliphatic amine.

Formula when using dimer _{acid, nHOOC-R-COOH + n} + 1 H 2 N-R'-NH 2 → NH 2 -R'-NH (DC-R CONH-R'-NH) nH + 2nH 2 O (R = C ₃₄ , R ′ = C _{2 to} C ₈ ), and mixed in a ratio of n mol of dimer acid and n + 1 mol of aliphatic amine. The molecular weight can be set by the n number.

As the fatty acid used in the present invention, dimer acid and trimer acid can be used, and a monomer acid may be added to adjust the amine value during the production of polyamidoamine.

As the aliphatic amine used in the present invention, ethylenediamine, diethylenetriamine, triethylenetetramine aliphatic amine and metaxylenediamine, an aliphatic amine having a ring structure of isophorone amine can be used, selected from these, Polyamides made from combinations of fatty acids and amines can be used.

The polyamidoamine thus produced has a number average molecular weight of about 1000 to 9,000. As a polyamidoamine that can be preferably used, the number average molecular weight is 6000 because of the viscosity of the coating composition and the coating composition design having a high nonvolatile content.
The following is preferable, and 2000 to 5000 is more preferable.

The coating composition of the present invention is formed into a coating film by the reaction of the modified epoxy resin and polyamidoamine, and the mixing ratio thereof is 1 equivalent of the epoxy group of the modified epoxy resin to the active amine hydrogen equivalent in the polyamidoamine. Is 0.5 to 1.5
It is preferable to use it at an equivalent ratio, preferably 0.7 to 1.3 equivalents. If it is less than 0.5 equivalents, the curing will be insufficient, and if it is more than 1.5 equivalents, tackiness may remain in the cured coating film, which may cause a problem in corrosion resistance.

Further, in order to improve the drying property and tightness, other modified amines such as amine adducts and Annich modified amines may be mixed and used.

Further, as the scale-like pigment, aluminum, titanium,
It is preferable to use chromium metal flakes and mica, and one kind or a mixture of two or more kinds thereof may be used. As for the shape, the aspect ratio (diameter / thickness) is 10 to 200.
It is preferable to use one having a maximum diameter of up to 100 μm. The mixing ratio in the composition is important for improving the durability of the coating film, and a ratio of 3 to 20% by volume concentration in the dry coating film is preferable. Optimally, 5 to 15% is good. If it is less than 3%, the blocking effect is small,
A composition exceeding 20 cannot be used because the viscosity of the paint becomes high.

Known extender pigments, coloring pigments, and rust preventive pigments may be appropriately mixed and used in order to adjust the volume concentration, color the paint, and improve the anticorrosive effect on the steel surface having no locally exposed rust layer.

Further, as a solvent of alcohols or glycol ethers having any solubility in water, alcohols such as methanol, ethanol, positive propyl alcohol, isopropyl alcohol, and glycol ethers such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve can be used. It is also possible to use one kind or a mixture of two or more kinds of solvents. The mixing ratio in the paint is preferably in the range of 5 to 30% by weight. When it is 5% or less, the effect of substitution with water is weak, and when it exceeds 30%, the nonvolatile content of the coating composition is small, and it becomes difficult to obtain a thick film by one coating.

It is generally used in epoxy resin paints as a drying property, pot life, a true solvent and a cosolvent for the modified epoxy resin.
A hydrocarbon solvent such as toluene or xylene, or a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone may be mixed and used.

A known means can be used to mix each of these components into a coating material, but a high-speed disperse dispersion structure in which only stirring is performed is preferable because the shape of the scaly pigment is not destroyed.

In addition, various known additives such as diluent (reactive or non-reactive) plasticizer, anti-flow agent, antifoaming agent, cissing agent, pinhole inhibitor, stabilizer, dispersant, etc. are appropriately added to the coating composition. You may.

The present invention is characterized in that the base material for the low-grade base treatment is adjusted, that is, after the treatment, it is washed with water before painting.

A low-grade surface treatment that does not use the blast method is a hammer, scraper, wire brush, force rod, tack, hand tool such as a chisel, and power tools such as a disk sander and a power brush. It is to treat the deteriorated coating film part.

The degree of treatment is, for example, Swedish standard grade SIS St2.0 equivalent for steel foundation, equivalent to 2-3 cleanliness of Steel Road Bridge Handbook when active membrane remains, or replacement keren for Japanese National Railways 2-3 It is a process corresponding to the seed.

For clean water, clean water that can be procured by hand, for example, tap water, miscellaneous water at marine facilities, etc., or corresponding clean water with few impurities is used to wash the coated surface.

To remove corrosive substances such as treated rust powder and invisible sea salt particles that cannot be removed by air blow, the selection of the cleaning method and the amount of water used have a great influence on the effect. In that respect, a washing method using high-pressure water is preferable.

After washing with water, the water collected on the horizontal surface may be wiped off with a waste cloth or mop, and the surface to be coated may not be safely dried.

The coating composition is applied to the treated surface in this manner, and the coating method may be a conventionally known means such as brush coating, spray coating or roller coating. The coating film thickness is not particularly limited, but it is usually 100 to 300 μm, preferably 150 to 250 μm as a dry film thickness, which is equivalent to the coating amount of other conventional paints and provides long-term corrosion resistance. To be

(Function) In the applied coating composition, the solvent and the polyamidoamine, which are optionally mixed with water, replace water molecules, and the water molecules taken into the coating composition to dry the surface to be coated are dried. Evaporates with the solvent. The modified epoxy resin having the ability to form a chelate firmly adheres to the rust steel plate to form a coating film. The scaly pigment in the coating composition is excellent in blocking external factors and exhibits a long-term anticorrosion effect. Furthermore, the coating film formed with the present coating composition has good adhesion to other known general coating materials such as oil-based coating materials, chlorinated rubber-based coating materials, epoxy resin-based coating materials, polyurethane resin-based coating materials, etc. Depending on the environmental color around the area, it is possible to appropriately apply makeup or topcoat with these different paints.

(Effect) According to the present invention, an excellent anticorrosion effect can be obtained even with a steel structure existing in a sea area or a beach area or a low-grade surface treatment of an atmospheric part of a facility.

(Example) The present invention will be further clarified with reference to the following examples and comparative examples.

The formulations of the examples are shown in Table 1. A commercially available paint was used for the comparative example.

Test 1 Corrosion resistance durability test 1-1 Adjustment of test plate (1) A steel plate (SS41 material) of size 70 × 200 × 3.2 mm was sandblasted and exposed to the beach area for 6 months to prepare a rust generating plate. .

(2) The rust generating plate was processed with a power brush and adjusted to Swedish standard SIS St2.0.

(3) After treatment of (2), 1 with air blow only and tap water
Two types of substrate preparations were performed, one that was washed with water for 0 seconds.

1-2 Preparation of test piece The test plate prepared in 1-1 was washed with water (
While not sufficiently dry yet), the coating composition was applied with an air spray so that the dry film thickness was 200 ± 20 μm, and then dried in a room for 7 days to obtain a test plate.

1-3 Test A salt-wet combined cycle test was conducted under the following conditions.

Model Suga ISO-3-CY Dry / wet combined cycle tester conditions 35 ° C, 5% salt spray… 6 hours 60 ° C, hot air… 3 hours 1 cycle 50 ° C, high humidity (98%)… 3 hours repeated, 100 cycles 1 -4 Evaluation method Appearance observation Defects such as rust generation and blistering Adhesion Adhesion test is performed using an Adhirople cage manufactured by Motofuji Co., Ltd. to measure adhesion with the substrate.

1-5 Evaluation Criteria Appearance ◎ ... No defects such as rust and blister generation ○ ... Less than 0.3% defect area such as rust and blister generation △ ... 0.3% to less than 3% defect area such as rust and blister formation × ... Rust and blister generation Defect area 3% or more Adhesion ◎… No peeling from the substrate ○… Peeling percentage from the substrate less than 30% △… Peeling percentage from the substrate 30% to less than 80% ×… Peeling percentage from the substrate 80% or more As is clear from the test results, the compositions 1 and 2 of the present composition corresponding to the present coating exhibited good anticorrosion properties even on the lower surface-treated surface, and further improved adhesion when the substrate was adjusted by washing with water after the surface treatment. And shows anticorrosive properties.

Test 2 Adhesion with various old coatings 2-1 Adjustment of test plate A sandblasted 70 × 200 × 3.2 mm steel plate (SS41 material) was used to make a coated plate with the following practical specifications, and it was used for 1 year in the beach area. Exposure Coating specifications (a) Oil-based rust preventive x2 + Topcoat x2 (b) Chlorinated rubber rustproof x2 + Topcoat x2 (c) Epoxy-based rustproof x2 + Intermediate coat x1 + Topcoat x1 (d) Epoxy / urethane type Epoxy rust prevention x 2 + Epoxy intermediate coat x 1 + Urethane top coat x 1 (e) Inorganic zinc / vinyl type Inorganic zinc x 1 + Sealer coat x 1 + Vinyl top coat x 2 After the exposure, lightly brush the wire brush and wash it with water to make a test plate did.

Note) All the test plates after exposure were glossy, sinked, and slightly soiled, with no defects such as rust and blistering.

2-2 Preparation of test piece The coating composition was applied to the test plate prepared in 2-1 by air spraying so that the dry film pressure was 200 ± 20 μm, and then dried indoors for 7 days to give a test plate. .

2-3 test JIS K-5400 6.17 Accelerated weathering test Sunshine weatherometer 1000 hours 2-4 Evaluation method JIS K-5400 6.15 Conforms to the cross-cut test Cut 25 squares at 2 mm intervals and peel off with adhesive tape Perform the test 2-5 Evaluation standard Conforms to the coating film evaluation standard of the Japan Paint Inspection Association Evaluation score 10 Percentage of peeling from old coating film 0% 8 〃 5% or less 6 〃 5% to less than 15% 4 〃 15 % To less than 35% 2〃 35% to less than 65% 0〃 65% or more From the above results, the coating compositions Examples 1 and 2 of the present application have good adhesion to various old coating films. On the other hand, Comparative Examples A, B, and C have poor adhesion, and do not show stable adhesion with various old coating films.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minor Hoshino 1-26 Moto-Akasaka, Minato-ku, Tokyo 1-26, Japan Society of Paint Industry (72) Inventor Tajin Nishimura 1-chome, Moto Akasaka, Minato-ku, Tokyo No. 5-26 Incorporated Hojin Japan Paint Industry Association (72) Inventor Shunichi Sano 1-526 Moto-Akasaka, Minato-ku, Tokyo Incorporated Hojin Japan Paint Industry Association (72) Inventor Satoru Furumoto Saiki-gun, Hiroshima Prefecture 18-19 Suginamidai, Yuki Town

Claims (5)

[Claims] 1. A method of applying a coating composition to a rusted portion and a deteriorated coating film portion after a low-grade base treatment which does not use a plast method, followed by washing with fresh water and before drying completely. The coating composition is a modified epoxy resin which is a reaction product of (A) an epoxy resin and a polyhydric phenolcarboxylic acid ester having an adjacent hydroxyl group or a formalin condensate, and (B) a polyvalent fatty acid and an aliphatic compound. A long-term anticorrosion coating method comprising a polyamidoamine which is a reaction product with an amine, (C) a scaly pigment, and (D) a solvent of an alcohol or glycol ether having an arbitrary solubility in water. 2. The modified epoxy resin according to claim 1, wherein An epoxy resin having at least one or more substituted or unsubstituted glycidyl ether groups represented by catechol-3-carboxylic acid, catechol-4-carboxylic acid, gallic acid, m-digallic acid, and pyrogallol-4 A long-term anticorrosion coating method, which is a modified epoxy resin formed by reaction with an ester of a polyhydric phenolcarboxylic acid selected from carboxylic acid and pyrogallol-4,6-dicarboxylic acid or a formalin condensate. 3. The polyamidoamine according to claim 1, wherein
Polyamine amine which is a reaction product of dimer acid, polyvalent fatty acid of trimer acid, and ethylene diamine, diethylene triamine, triethylene tetramine, metaxylene diamine, amine of isophorone diamine, and a mixing ratio in the coating composition. However, the active amine hydrogen equivalent of (B) polyamidoamine is in the range of 0.5 to 1.5 equivalent to 1 equivalent of epoxy group of (A) modified epoxy resin. 4. The scale-like pigment according to claim 1, wherein the scale-like pigment is one or a plurality of scale-like pigments selected from metal flakes of aluminum, titanium and chromium, and mica, and has a mixing ratio in the paint. A long-term anticorrosion coating method, characterized in that the volume concentration in the dry coating film is in the range of 3 to 20%. 5. The solvent of alcohols or glycol ethers having any solubility in water according to claim 1, wherein glycols of methanol, ethanol, positive propyl alcohol, isopropyl alcohol and methyl cellosolve, ethyl cellosolve, butyl cellosolve. A long-term anticorrosion coating method, which comprises one or more solvents selected from ethers, and a weight mixing ratio in the coating composition is in the range of 5 to 30%.