JP2005139406A - Rusty surface coating and method of preventing corrosion using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating with good anti-corrosion property even when it is used in simple surface treatment for rusty steel plate surfaces and to provide a method of preventing corrosion using the same. <P>SOLUTION: A non-epoxy resin-based coating for rusty steel plate surfaces contains a lipophilic surfactant, liquid oil, and a thermoplastic resin. The method of preventing corrosion uses the coating. By the use of the above composition, a coating that has good anti-corrosion property even when it is used in simple surface treatment can be obtained. The coating enables operation in narrow spaces with poor workability, such as ballast tanks of ships; and can be used in simple surface treatment, thereby shortening the construction period. Hence, the use of the coating is economically effective. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for preventing corrosion of a rusted steel sheet such as a tank.

  The inner surfaces of tanks such as ships and bridges are very corrosive due to the influence of salt and humidity, and rust and rusting of several millimeters in thickness due to deterioration over the years has been caused, and anticorrosion maintenance has been performed. As an anticorrosion method, an epoxy resin-based paint or the like has been used because of its excellent anticorrosion properties. However, in order to ensure adhesion with the steel surface, it was necessary to completely remove rust by a base treatment.

  However, it takes a lot of time and labor to perform blasting as a complete ground treatment, and there are problems in the work environment due to the generation of dust and noise. It was rare. Especially in narrow spaces such as ship ballast tanks and bridge tanks, the workability was very difficult.

As measures for improvement, there are a method of controlling the thickness of the rust layer of rust steel to a certain level or less by a film thickness meter, a method of ensuring the permeability to the rust layer and the film thickness by setting the coating liquid to a specific viscosity, etc. Although known, all are epoxy resin-based paints and have insufficient adhesion to the rust surface, and the effect is not satisfactory.
Japanese Patent Laid-Open No. 6-206046 JP-A-9-206675

  Providing paints with excellent anticorrosion properties even with simple surface treatment for rusted steel sheets, and anticorrosion methods using the same

As a result of intensive studies to solve the above problems, the present inventors have found that a non-epoxy resin-based paint containing a lipophilic surfactant, a liquid oil and a thermoplastic resin is a simple ground treatment for a rust surface of a steel sheet. And found that a coating film having excellent anticorrosion properties was produced, and the present invention was completed.
That is, the present invention is a non-epoxy resin-based paint for a rust surface of a steel plate containing a lipophilic surfactant, liquid oil and a thermoplastic resin, and a corrosion prevention method for a rust surface steel plate such as a tank using the same.

  The anticorrosion method of the present invention has an advantage of obtaining a coating film having excellent anticorrosion properties by simply coating a rust surface after simple surface treatment. Since the surface treatment is simple, the construction time and cost are small, the working environment is good, and it is particularly convenient for construction of narrow tanks.

  Examples of the lipophilic surfactant contained in the paint of the present invention include carboxylic acids, carboxylates, alcohols, oil-soluble sulfonates, phosphate esters, and nonionic surfactants.

The carboxylic acids are not particularly limited as long as they are monocarboxylic acids having 8 to 34 carbon atoms, but preferably 12 to 32 carbon atoms. Examples of monocarboxylic acids used in the present invention include linear saturated acids such as dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, docosanoic acid, and tetracosanoic acid. , Isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isopentadecanoic acid, isohexadecanoic acid, isoheptadecanoic acid, isooctadecanoic acid, isononadecanoic acid, isoeicosanoic acid, 2-ethylhexanoic acid, 2-butyloctanoic acid, 2-hexyldecanoic acid, 2 -Branched acids such as octyldodecanoic acid, 2-decyltetradecanoic acid, 2-dodecylhexadecanoic acid, 2-tetradecyloctadecanoic acid, 2-hexadecyloctadecanoic acid, long-chain branched fatty acids obtained from lanolin, Linderic acid, myris Rheic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid, gadrenic acid, eicosapentaenoic acid, docosahexaenoic acid, erucic acid, brassic acid, arachidonic acid and other linear unsaturated fatty acids, 2-hydroxydodecanoic acid, 2-hydroxytridecanoic acid, 2-hydroxytetradecanoic acid, 2-hydroxyheptadecanoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyheptadecanoic acid, 2-hydroxyoctadecanoic acid, 12-hydroxyoctadecanoic acid, 2-hydroxynonadecane Acid, 2-hydroxyeicosanoic acid, 2-hydroxydocosanoic acid, 2-hydroxytetracosanoic acid, hydroxy acids such as long-chain branched 2-hydroxy fatty acids obtained from lanolin, hydrogenated rosin, rosin, abietic acid, hydrogenated Abietic acid Butanoic acid, cyclic acids such as. In addition, orange oil fatty acid, avocado oil fatty acid, macadamia nut oil fatty acid, olive oil fatty acid, hydrogenated soybean oil fatty acid, jojoba oil fatty acid, coconut oil fatty acid, hydrogenated coconut oil fatty acid, palm kernel oil fatty acid, castor oil fatty acid, safflower oil fatty acid Since natural fatty acids such as cottonseed oil fatty acid, beef tallow fatty acid, hydrogenated beef tallow fatty acid, lanolin fatty acid, mink oil fatty acid, oxidized paraffin wax fatty acid and oxidized petrolatum fatty acid also contain monocarboxylic acids having 8 to 34 carbon atoms, the present invention Can be used. As dicarboxylic acid, dimer acid obtained by polymerizing vegetable oil fatty acid or hydrogenated dimer acid can also be used. Among these carboxylic acids, particularly preferred are abietic acid, lanolin fatty acid, oxidized paraffin fatty acid, and oxidized petrolatum fatty acid.

  As the carboxylic acid salts, salts of the above carboxylic acids such as alkali metals (Li, Na, K), alkaline earth metals (Ca, Mg, Ba), zinc, aluminum, iron, amine and the like can be used. Of these salts, Li, Ca, Mg, Ba, Zn, and Al salts are preferred. Particularly preferred are calcium octadecanoate, lanolin fatty acid calcium, lanolin fatty acid barium, lanolin fatty acid zinc, and petrolatum barium oxide salt.

  Examples of alcohols include C10-30 aliphatic or alicyclic alcohols such as oleyl alcohol, isostearyl alcohol, stearyl alcohol, lanolin alcohol, and rosin alcohol. Of these, oleyl alcohol and lanolin alcohol are preferred.

  Oil-soluble sulfonates include natural petroleum sulfonates obtained as a by-product of oil refining, synthetic sulfonates obtained by sulfonated dialkylbenzene and nonylnaphthalene, and highly basic sulfonates in which calcium carbonate and barium carbonate are highly dispersed. Etc. are used. As salts of these oil-soluble sulfonates, salts such as sodium, calcium, magnesium, barium, and amines are commercially available, and any of them can be used, but calcium salts are preferable in terms of stability and safety. Highly basic sulfonates are particularly preferred.

  As phosphoric acid esters, monoalkyl phosphoric acid ester, dialkyl phosphoric acid ester, trialkyl phosphoric acid ester which are esters of phosphoric acid and C8-20 aliphatic alcohol, and metal salts, amine salts and the like thereof, and Lecithin can also be used.

As the nonionic surfactant, a nonionic surfactant having an HLB of 10 or less, more preferably an HLB of 8 or less is used. As such, ester type nonionic surfactants which are partial esters of the above carboxylic acids and polyhydric alcohols, such as oleic acid monoglyceride, sorbitan monooleate, sorbitan sesquioleate, lanolin fatty acid pentaerythritol ester, lanolin fatty acid trimethylol Propane ester, soybean fatty acid trimethylolpropane ester, etc., polyoxyalkanol ether type nonionic surfactant, such as oleyl alcohol EO2 molar adduct, hydroxy fatty acid ester type nonionic surfactant, such as stearyl lactate,
Examples include oleyl malate and lanolin. Of these, lanolin, lanolin fatty acid pentaerythritol ester, and lanolin fatty acid trimethylolpropane ester are particularly preferable.

  The content of the lipophilic surfactant in the coating composition of the present invention can be appropriately selected, but as a guideline, about 1 to 50% by weight in the nonvolatile component is appropriate, and 5 to 20% by weight is preferable.

The liquid oil contained in the paint of the present invention may be any water-repellent liquid oil that can dissolve or finely disperse the lipophilic surfactant, and includes hydrocarbon oils such as mineral oil and liquid paraffin. Polyolefin oils and the like, and ester-based liquid oils include animal and vegetable oils such as soybean oil, rapeseed oil, jojoba oil, chicken oil, menhaden oil and the like.
The content of the liquid oil in the paint of the present invention is suitably about 1 to 50% by weight of the non-volatile component, and preferably 5 to 30% by weight.

As the thermoplastic resin in the paint of the present invention, petroleum resin, coumarone resin, vinyl acetate resin, acrylic resin, low molecular weight polyethylene resin, asphalt and the like can be used, among which petroleum resin, coumarone resin and asphalt are preferable.
The thermoplastic resin is necessary to increase the strength of the coating film, and its content is suitably about 5 to 50% by weight, preferably 10 to 30% by weight in the nonvolatile content. If the amount is too large, the film strength is increased, but the film becomes inflexible and the adhesiveness is lowered.

In the coating material of the present invention, additives used in general coating materials such as a solvent, a pigment, a sag preventing agent, and the like can be used as necessary.
Examples of the solvent include toluene, xylene, gasoline, ether, tetrahydrofuran, acetone, MEK, MIBK, IPA, isobutanol, and ethyl acetate.

  Examples of the pigment include talc, kaolin, titanium oxide, calcium carbonate, calcium phosphate, bengara, zinc powder, aluminum powder, and powders of these powders treated with organic substances.

  Examples of the anti-sagging agent include organic bentonite, finely divided silica, castor oil derivatives and the like.

The coating material of the present invention can be obtained by charging an oleophilic surfactant, liquid oil, thermoplastic resin, solvent and, if necessary, an additive such as a pigment into a stirrer such as a kneader and mixing and stirring. As the thermoplastic resin that requires heating for dissolution, a resin previously dissolved in a solvent may be used, or the whole amount may be heated during mixing and stirring. The viscosity of the coating is preferably 3000 to 20000 mPs, more preferably 4000 to 10000 mPs in view of the workability of coating. When the viscosity is lower than 3000 mPs, the film thickness of one-time coating becomes thin, and when it is overcoated, there is a drying interval and the working time becomes significantly longer. Further, if it is 20000 mPs or more, the permeability becomes poor, and the coating apparatus becomes a special coating such as a special high-pressure spray or a warming spray, resulting in poor workability.

  As a simple ground treatment in the anticorrosion method of the present invention, first, floating rust (corrosion progresses considerably and rust that easily peels off when touched or polished lightly by hand) is removed by a scraper, an electric sander or the like. Next, when there is a lot of powder rust, dust, salt, etc. on the surface, it is preferable to remove the dust and water by showering. If washed with water, perform painting after drying.

  Brush painting, roll coating, and airless spraying can be applied to the coating, but airless spraying is preferable from the viewpoint of workability. Such airless sprayers include Premier 45: 1 (Graco's air-driven airless sprayer). In the anticorrosion method of the present invention, the paint is applied in a wet amount of about 300 to 1000 μm in consideration of the rust condition and the like. The paint contains an oleophilic surfactant and liquid oil. The paint penetrates deep into the rust layer and replaces the air in the rust layer, or the moisture in the rust layer is taken into the paint. It is presumed that the progress of rust is suppressed by blocking oxygen and moisture necessary for the progress of rusting of the surface from the iron surface. It is expected that pinholes can be prevented and oxygen and moisture can be prevented from penetrating by ensuring a sufficient coating film thickness.

EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to these Examples.

Examples 1-3, Comparative Example 1
The components shown in Table 1 were charged into a kneader, heated and mixed to 110 ° C., then cooled to room temperature to prepare each paint, and the viscosity, sag test, and salt spray test were performed by the following methods.
The results are shown in Table 2.

Test method

1. Salt spray test (according to JIS-Z2371)
Salt spray tester: Suga Tester Co., Ltd. ST-90
Test conditions
Test room temperature: 35 ° C
5% saline, spray amount 1-2 ml / hr, 80 cm2
Spray pressure 0.098 mPa
Test plate 70x150x3.2mm black skin steel plate is exposed to the seaside splash zone, and lightly rubbed with a scraper on the rust steel plate that has generated layered rust, hump rust, etc. Rust was removed. Subsequently, the surface was washed with tap water and air-dried. A test paint was applied to the rust steel sheet with a film thickness of wet 500 μm with an airless spray ALS-431 (manufactured by Anest Iwata Co., Ltd.), and was dried and subjected to a salt spray test. Example 4 and Comparative Example 1 were overcoated to a predetermined film thickness.
2. Viscosity BM type rotational viscometer No.4 rotor 30rpm Measured at room temperature.
3. Sagging test A cold rolled dull steel plate (70 × 150 × 1.2 mm) is placed vertically, and a test paint is applied to a predetermined film thickness by airless spraying, and sagging property is observed.

Evaluation Sagging test ○: No sagging of the film △: Sagging is within 3 mm ×: Sacrifice of 3 mm or more

Salt spray test After 2000 hours 〇: No rust juice on the coating film surface △: A little rust juice on the coating film surface ×: A rust juice spread on the coating film surface

  From Table 2, the inventions of the examples are excellent in rust prevention property to rusted surface steel sheets, and the paint is excellent in dripping property, so that thick coating can be easily performed.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an anticorrosion paint for a rusted surface steel plate such as a ship ballast tank and a bridge tank, and an anticorrosion method.

Claims (4)

  A non-epoxy resin-based paint for a rust surface of a steel sheet containing a lipophilic surfactant, liquid oil, and a thermoplastic resin.   The non-epoxy resin-based paint for a rust surface according to claim 1, wherein the lipophilic surfactant is at least one selected from the group consisting of lanolin, lanolin derivatives and oil-soluble sulfonates.   The non-epoxy resin-based paint according to claim 1 or 2, wherein the viscosity is 3000 to 50000 mPs. An anticorrosion method using the non-epoxy resin paint according to any one of claims 1 to 3.