JP2009179860A - Surface preparation process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface preparation process with the working environment improved which is harmless to the natural environment, and further has reduced generation of dust and noise for performing recoating after the peeling of old coating films and the removal of an oxide film to a building steel structure or the like. <P>SOLUTION: Regarding the surface preparation process for removing an oxide film and old coating films such as an organic film and an inorganic film which does not require blast treatment, the process comprises: a stage where a coating film infiltration softener is applied to the surface of the old coating films; a stage where the old coating films are peeled and removed together with the coating film infiltration softener; a stage where the surface of the metal base material freed of the old coating films is coated with a black skin removing agent; and a stage where the oxide film is removed together with the black skin removing agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a black skin or old paint film for repainting civil steel structures such as bridges, pedestrian bridges, harbor cranes, and other construction steel structures such as general buildings, plant equipment, and mechanical parking equipment. It is related with the substrate adjustment construction method for removing.

  For civil engineering steel structures such as bridges, pedestrian bridges, harbor cranes, etc., and construction steel structures such as general buildings, plant facilities, and mechanical parking facilities, it is necessary to extend the life of social capital based on the concept of life cycle costs. For the maintenance, repainting is generally performed after removing the old paint film and removing the oxide film. The removal of the old paint film and the removal of the oxide film for preparation before repainting required time and a lot of labor for the removal and removal work.

  In recent years, coatings containing harmful components such as lead, chromium and PCB are also present in many structures. The old paint film peeling method involves physical removal of kelen, blast, etc., but the work involves problems such as generation of dust and noise, resulting in a worse working environment.

In recent years, in order to chemically remove the old coating film, the use of a peeling agent for the coating film has been studied. For example, a release agent mainly composed of methylene chloride has been studied (for example, see Patent Documents 1 and 2). However, the use of methylene chloride is not environmentally desirable. Further, a release agent using a special compound, a solvent, or the like other than methylene chloride has been studied (for example, see Patent Documents 3 and 4).
JP 61-98776 A JP-A-8-48920 JP 2001-98191 A JP 2004-168788 A

  The purpose of the present invention is to perform repainting after peeling off the old paint film and removing the oxide film, mainly on construction steel structures, etc., which is friendly to the natural environment and generates less dust and noise. Provide a substrate preparation method that improves the environment.

In accordance with the present invention, in the substrate preparation method for removing the oxide film on the metal substrate and the old film of the organic film or inorganic film,
Applying a coating-penetrating softener on the old coating;
A step of peeling and removing the old coating film together with the coating film softening agent,
Applying a black skin remover on the metal substrate from which the old coating film has been removed,
Removing the oxide film together with the black skin remover;
There is provided a substrate adjustment method characterized by not requiring a blast treatment having

  According to the substrate preparation method of the present invention, it is not necessary to physically remove the old coating film by means of keren, blasting, etc., and there is little generation of noise, dust, etc., and the working environment is excellent. Moreover, since the peeled / removed film can be collected, harmful substances are hardly discharged.

  Further, since the blasting process is not performed, the metal substrate is not damaged. Moreover, since the oxide film (black skin, mill scale) on the surface of the metal substrate can be removed by the black skin remover, it can contribute to the improvement of the adhesion and anticorrosion performance of the coating film after repainting.

  The substrate adjustment method of the present invention will be described in detail below.

  The present invention uses a coating-penetrating softener and a black skin remover in order to remove an oxide film (black skin, mill scale) on a metal substrate and an organic coating or inorganic coating of an old coating.

  The coating-penetrating softening agent can be easily peeled and removed by penetrating into the organic coating or inorganic coating of the old coating to swell and soften the old coating. The composition is a liquid containing aromatic alcohols, glycols, alcohols, silica and water.

  Examples of aromatic alcohols include benzyl alcohol, phenylethanol, phenoxyethanol, phenoxypropanol, phenethyl alcohol, hydroxybenzyl alcohol, hydroxyphenethyl alcohol, and the like, preferably benzyl alcohol from the viewpoint of swelling and softening the old coating film. .

  Examples of glycols include ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, with diethylene glycol monomethyl ether being preferred.

  Examples of the alcohols include methanol, ethanol, butanol, etc., preferably methanol.

  Silica has a viscosity of a coating film penetrating softener and is added to prevent the liquid from flowing down when applied to a vertical surface or the like. The type of silica can be used without particular limitation, such as vapor phase silica and colloidal silica.

  Water can be used without particular limitation, such as tap water, distilled water, and ion exchange water.

  The composition of the coating-penetrating softener is preferably 50 to 60 wt% aromatic alcohol, 10 to 20 wt% glycol, 0.1 to 10 wt% methanol, 0.1 to 10 wt% silica, and 10 to 40 wt% water. . In addition to this, additives can be included in a small amount.

  The pH of the coating penetration softener is preferably 6.5 to 7.5.

  Black skin remover dissolves and removes black skin, mill scale and other oxide films on metal substrates, which can contribute to improving the adhesion and anticorrosion performance of the coating after repainting. it can. Its composition is a viscous liquid containing inorganic acid, organic acid, surfactant, thickener and water.

  The inorganic acid includes at least one of sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, and phosphoric acid, and it is particularly preferable to include phosphoric acid from the viewpoint of dissolving and removing the oxide film.

  As the organic acid, carboxylic acid is the main one, formic acid, acetic acid, propionic acid, butanoic acid, valeric acid, acrylic acid, crotonic acid, vinyl acetic acid, butyric acid, isobutyric acid, oxalic acid, malonic acid, succinic acid, Maleic acid, fumaric acid, lactic acid, gluconic acid, tartaric acid, malic acid, citric acid, methoxyacetic acid, benzoic acid, terephthalic acid, trimellitic acid, glycine, glutamic acid, pyroglutamic acid, etc., among which citric acid, apple It is preferable to include at least one of acid, lactic acid, valeric acid, acetic acid, formic acid, pyroglutamic acid, propionic acid, and butyric acid. More preferably, it contains formic acid or lactic acid.

  The surfactant preferably contains at least one of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.

  Examples of anionic surfactants include alkylbenzene sulfonate, higher alcohol sulfate, polyoxyethylene alkyl ether sulfate, α-sulfo fatty acid ester, α-olefin sulfonate, monoalkyl phosphate, alkane sulfone. Examples include acid salts.

  Examples of the cationic surfactant include alkyltrimethylammonium salts, alkyldimethylbenzylammonium salts and amine salts.

  Examples of amphoteric surfactants include alkylamino fatty acid salts, alkylbetaines, and alkylamine oxides.

  Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, alkyl glucosides, polyoxyethylene fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkanolamides, etc. Can be mentioned.

  As the surfactant used in the present invention, an amphoteric surfactant is particularly preferable.

  A thickener is added to prevent the liquid from flowing down when applied to a vertical surface, etc., such as carboxymethylcellulose, polyacrylic acid, hydroxypropylcellulose, polyvinyl alcohol. , Polyvinyl pyrrolidone, hydroxypropyl methylcellulose, fumed silica, alumina sol, and Kelzan (xanthan gum). Among them, polyvinyl pyrrolidone is preferable.

  The composition of the black skin remover is 0.1-25 wt% inorganic acid, 0.1-25 wt% organic acid, 0.1-5 wt% surfactant, 10-20 wt% thickener, 50-70 wt% water. Preferably there is.

  The pH of the black skin removing agent is preferably 4.0 or less from the viewpoint of removing oxide films such as black skin and mill scale.

The substrate preparation method of the present invention is a method of applying a coating film softening agent to an old coating film on a metal substrate and removing the swollen coating film by peeling and removing by high-pressure water washing at 200 to 1500 Kg / cm ^2. Furthermore, it is preferable to recover the peeled / removed coating film and washing water.

The coating-penetrating softener is applied using a brush or a roller so as to be 300 to 800 g / m ² and cured for 1 to 7 days. In the meantime, it is preferable to wrap the applied surface with a film or the like in order to prevent drying of the coating-penetrating softener and intrusion of rainwater or the like. A film that has been swollen and softened by applying a coating-penetrating softening agent can be scraped off and removed with a scraper or the like. .

The removal of the film by high-pressure water washing is performed using an ultra-high pressure washing machine, 200 to 1500 Kg / cm ² of high-pressure water, more preferably a multi-head rotary nozzle type and / or a vacuum type (with a simultaneous cleaning and recovery function). The ultra-high pressure washer is used, and the cleaning operation is performed with high pressure water of 500 to 1000 kg / cm ² .

  Peeling of the old paint film is usually done by blasting such as sand blasting, but the blasting work costs a lot of money to install the work environment (dustproof equipment, scaffolding, etc.), but according to the substrate preparation method of the present invention, dust etc. Therefore, it is not necessary to install such equipment and the cost can be minimized.

  The peeled / removed old paint film does not scatter and is almost 100% recovered. The washing water used for the high-pressure water washing is collected in a tank or the like and reused or drained.

  As the organic coating of the old coating, chlorinated rubber coating, alkyd resin coating, unsaturated polyester resin coating, epoxy resin coating, acrylic resin coating, urethane resin coating, fluorine resin coating A coating film etc. are mentioned.

  Examples of the inorganic coating of the old coating include a silicone resin coating and an acrylic silicone resin coating.

  The black skin removing agent is applied onto a dried metal substrate after applying a coating-penetrating softener to the organic coating or inorganic coating of the old coating, peeling off and removing the swollen coating.

The black skin removing agent is applied on a metal substrate using a brush or a roller so as to be 100 to 500 g / m ² and cured for several hours to one day. There is no problem even if some old paint film remains.

  Thereafter, the oxide film such as black skin and mill scale on the metal substrate can be removed by wiping with a waste with a black skin removing agent or by washing away with high pressure water washing or the like.

  In the substrate preparation method of the present invention, the metal substrate is preferably any one of an iron-based metal substrate, an aluminum-based metal substrate, and an aluminum alloy substrate.

  The base adjustment method of the present invention can be applied to civil engineering steel structures such as bridges, footbridges, harbor cranes, general buildings such as outer walls and stairs, plant facilities such as tanks, boilers and piping, mechanical parking facilities, etc. It can be applied without limitation as long as it has an organic coating or an inorganic coating on a metal substrate such as a construction steel structure or a large vehicle.

  Hereinafter, although this invention is demonstrated in detail, the scope of the present invention is not limited at all by these Examples and Comparative Examples.

Example 1
<Base material and old paint film>
Metal base: Iron structure (spherical gas folder)
Old paint film: Chlorinated rubber paint film (film thickness 400μm)
<Coating softener>
Aromatic alcohols (benzyl alcohol): 60 wt%
Glycols (diethylene glycol monomethyl ether): 10 wt%
Methanol: 2.5wt%
Silica: 3.0wt%
Water: 24.5wt%
<Black skin remover>
Inorganic acid (phosphoric acid): 10.0wt%
Organic acid (formic acid): 10.0wt%
Surfactant (polyoxyethylene alkylene ether): 1.5 wt%
Thickener (polyvinylpyrrolidone): 10.0wt%
Water: 68.5 wt%
pH: 0.5

<Method and evaluation>
On the old coating film, 400 g / m ² of a coating film softening agent having the above composition was applied using a roller, and wrapping curing was performed for 3 days in order to prevent penetration and drying. Thereafter, the old coating film was peeled off with a scraper, and a black skin removing agent was applied at 300 g / m ² using a roller. After 8 hours, cleaning and recovery were performed with a vacuum water jet (1000 kg / cm ² · 100 MPa).

  After drying, the state of the substrate surface was visually observed to evaluate the remaining state of the old paint film and black skin. The evaluation results are shown in Table 1.

(Example 2)
<Base material and old paint film>
Metal base: Iron structure (steel stairs)
Old coating film: Alkyd resin coating film (film thickness 350μm)
<Coating softener>
Aromatic alcohols (β-phenylethanol): 50 wt%
Glycols (diethylene glycol monomethyl ether): 20 wt%
Methanol: 2.5wt%
Silica: 3.0wt%
Water: 24.5wt%
<Black skin remover>
Inorganic acid (hydrofluoric acid): 8.0 wt%
Organic acid (lactic acid): 20.0 wt%
Surfactant (polyoxyethylene alkylene ether): 1.5 wt%
Thickener (polyvinylpyrrolidone): 10.0wt%
Water: 60.5wt%
pH: 0.5

<Method and evaluation>
On the old coating film, 400 g / m ² of a coating film softening agent having the above composition was applied using a roller, and wrapping curing was performed for 2 days in order to prevent penetration and drying. Then, the old coating film was peeled off with a water jet (600 kg / cm ² ), and a black skin removing agent was applied at 300 g / m ² using a roller. After 8 hours, it was washed with a water jet (600 kg / cm ² ). After drying, evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

(Example 3)
<Base material and old paint film>
Metal substrate: Iron structure (tank)
Old paint film: Acrylic silicone resin paint film (film thickness 300μm)
<Coating softener>
Aromatic alcohols (benzyl alcohol): 50 wt%
Glycols (diethylene glycol monomethyl ether): 10 wt%
Glycols (diethylene glycol dimethyl ether): 10 wt%
Methanol: 5.0 wt%
Silica: 3.0wt%
Water: 22.0wt%
<Black skin remover>
Inorganic acid (phosphoric acid): 10.0wt%
Organic acid (citric acid): 10.0wt%
Surfactant (sodium alkylamino fatty acid): 2.5 wt%
Thickener (polyvinylpyrrolidone): 10.0wt%
Water: 67.5wt%
pH: 0.6

<Method and evaluation>
On the old coating film, 400 g / m ² of a coating film softening agent having the above composition was applied using a roller, and wrapping curing was performed for 3 days in order to prevent penetration and drying. Then, the old coating film was peeled off with a water jet (500 kg / cm ² ), and a black skin removing agent was applied at 300 g / m ² using a roller. After 8 hours, it was washed with a water jet (500 kg / cm ² ). After drying, evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

Example 4
<Base material and old paint film>
Metal substrate: Aluminum (outer wall panel)
Old paint film: Fluororesin paint film (film thickness 300μm)
<Coating softener>
Aromatic alcohols (benzyl alcohol): 40 wt%
Aromatic alcohols (phenoxyethanol): 20 wt%
Glycols (diethylene glycol monomethyl ether): 10 wt%
Methanol: 2.5wt%
Silica: 2.5wt%
Water: 25.0wt%
<Black skin remover>
Inorganic acid (hydrofluoric acid): 8.0 wt%
Organic acid (formic acid): 10.0wt%
Surfactant (sodium alkylbenzene sulfonate): 2.5 wt%
Thickener (polyvinylpyrrolidone): 10.0wt%
Water: 69.5 wt%
pH: 0.5

<Method and evaluation>
On the old coating film, 400 g / m ² of a coating film softening agent having the above composition was applied using a roller, and wrapping curing was performed for 3 days in order to prevent penetration and drying. Then, the old coating film was peeled and collected with a vacuum water jet (800 kg / cm ² ), and a black skin removing agent was applied at 300 g / m ² using a roller. After 8 hours, it was washed with a water jet (800 kg / cm ² ). After drying, evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 1)
<Base material and old paint film>
Metal base: Iron structure (spherical gas folder)
Old paint film: Chlorinated rubber paint film (film thickness 400μm)
<Coating softener>
Same as Example 1 above.

<Method and evaluation>
On the old coating film, 400 g / m ² of a coating film softening agent having the above composition was applied using a roller, and wrapping curing was performed for 3 days in order to prevent penetration and drying. Then, the old coating film was peeled off with a scraper and washed with a vacuum water jet (1000 kg / cm ² · 100 MPa). After drying, evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 2)
<Base material and old paint film>
Metal base: Iron structure (steel stairs)
Old coating film: Alkyd resin coating film (film thickness 350μm)
<Film remover>
Glycols (diethylene glycol monomethyl ether): 20.0 wt%
Methanol: 3.0wt%
Silica: 5.0wt%
Water: 72.0wt%
<Black skin remover>
Same as Example 2 above.

<Method and evaluation>
A 400 g / m ² coating film peeling agent having the above composition was applied onto the old coating film using a roller, and wrapping curing was performed for 2 days in order to prevent penetration and drying. Thereafter, the old coating film was peeled off with a water jet (400 kg / cm ² ), and a black skin removing agent was applied at 300 g / m ² using a roller. After 8 hours, it was washed with a water jet (400 kg / cm ² ). After drying, evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 3)
<Base material and old paint film>
Metal base: Iron structure (steel stairs)
Old coating film: Alkyd resin coating film (film thickness 350μm)
<Film remover>
Glycols (diethylene glycol monomethyl ether): 10.0wt%
Methanol: 60.0 wt%
Silica: 5.0wt%
Water: 25.0wt%
<Film remover>
Inorganic acid (phosphoric acid): 15.0 wt%
Surfactant (polyoxyethylene alkylene ether): 2.5 wt%
Thickener (polyvinylpyrrolidone): 10.0wt%
Water: 72.5wt%
pH: 0.5

<Method and evaluation>
A 400 g / m ² coating film peeling agent having the above composition was applied onto the old coating film using a roller, and wrapping curing was performed for 2 days in order to prevent penetration and drying. Thereafter, the old coating film was peeled off with a water jet (500 kg / cm ² ), and the film removing agent was applied with 300 g / m ² using a roller. After 8 hours, it was washed with a water jet (500 kg / cm ² ). After drying, evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1.

Claims (14)

In the substrate preparation method for removing the old coating film of the oxide film and organic coating or inorganic coating on the metal substrate,
Applying a coating-penetrating softener on the old coating;
A step of peeling and removing the old coating film together with the coating film softening agent,
Applying a black skin remover on the metal substrate from which the old coating film has been removed,
Removing the oxide film together with the black skin remover;
A substrate adjustment method characterized by not requiring a blasting treatment.   The substrate adjustment method according to claim 1, wherein the coating film softening agent contains aromatic alcohols, glycols, alcohols, silica, and water.   The substrate preparation method according to claim 1 or 2, wherein the black skin removing agent contains an inorganic acid, an organic acid, a surfactant, a thickener, and water.   The substrate preparation method according to claim 3, wherein the inorganic acid includes at least one of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and hydrofluoric acid.   4. The substrate preparation method according to claim 3, wherein the organic acid includes at least one of citric acid, malic acid, lactic acid, valeric acid, acetic acid, formic acid, pyroglutamic acid, propionic acid, and butyric acid.   The substrate preparation method according to claim 3, wherein the surfactant includes at least one of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.   Examples of the anionic surfactant include alkylbenzene sulfonate, higher alcohol sulfate, polyoxyethylene alkyl ether sulfate, α-sulfo fatty acid ester, α-olefin sulfonate, monoalkyl phosphate, alkane sulfone. The substrate preparation method according to claim 6, comprising at least one of the acid salts.   The substrate preparation method according to claim 6, comprising at least one of an alkyltrimethylammonium salt and an alkyldimethylbenzylammonium salt / amine salt as the cationic surfactant.   The substrate preparation method according to claim 6, comprising at least one of an alkylamino fatty acid salt, an alkylbetaine, and an alkylamine oxide as the amphoteric surfactant.   As the nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, alkyl glucoside, polyoxyethylene fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkanolamide The substrate adjustment method according to claim 6, comprising at least one. The step of peeling and removing the old coating film together with the coating-penetrating softener is a step of peeling and removing by high-pressure water washing at 200 to 1500 Kg / cm ² , and further collecting the removed coating and washing water. The substrate preparation method according to any one of claims 1 to 10, further comprising a step of:   The substrate preparation method according to any one of claims 1 to 11, wherein the metal substrate is one of an iron-based metal substrate, an aluminum-based metal substrate, and an aluminum alloy substrate.   The organic coating of the old coating is a chlorinated rubber coating, an alkyd resin coating, an unsaturated polyester resin coating, an epoxy resin coating, an acrylic resin coating, a urethane resin coating, or a fluororesin coating. The substrate preparation method according to any one of claims 1 to 12, which is any one of coating films.   The substrate preparation method according to any one of claims 1 to 12, wherein the inorganic coating of the old coating is one of a silicone resin coating and an acrylic silicone resin coating.