JP5848050B2 - Rust prevention coating method on metal surface - Google Patents

Description

  The present invention relates to a method for painting a metal surface, and particularly to a method for painting a rusted metal surface.

Various guard rails, bridges, road sign poles, and the like are formed of a metal material (hereinafter referred to as a “metal base material”), and these surfaces rust over time. A mechanism for generating rust will be briefly described. FIG. 6 is a diagram showing a mechanism of rust formation on the metal surface. For example, when moisture adheres to the surface of iron, iron having a large ionization tendency becomes ions Fe ²⁺ and dissolves in the moisture. An anodic reaction occurs near the surface of the iron, and a cathodic reaction occurs near the other part. The anodic reaction is Fe → Fe ²⁺ + 2e ⁻ . The cathode reaction is H ₂ O + 1 / 2O ₂ + 2e ⁻ → 2OH ⁻ . The overall chemical reaction is Fe ²⁺ + 2OH ⁻ → Fe (OH) ₂ . Here, with the passage of time, water and oxygen further react to generate a chemical reaction 2Fe (OH) ₂ + 1 / 2O ₂ → Fe ₂ O ₃ .H ₂ O, and rust is generated (FIG. 6). . Rust not only deteriorates the appearance of the metal surface but also weakens the strength of the metal base material. Therefore, it is necessary to prevent the rust from being applied to the metal surface at the beginning, periodically or as needed.

JP 2011-20006 A

  Briefly explain the normal method of painting on rusted metal surfaces. FIG. 7A is a cross-sectional view of a metal base material whose surface is rusted. FIG. 7B is a cross-sectional view of the metal base material after applying one kind of keren to the rusted metal surface. FIG. 7C is a cross-sectional view of the metal base material after applying two types of kelen to the rusted metal surface. FIG. 8 is a cross-sectional view of a metal base material in the case where an epoxy resin paint is applied after applying two types of kelen to a rusted metal surface.

  In a normal painting method for a rusted metal surface, first, the rust 72 on the surface of the metal base material 71 is dropped, the old coating film and the fragile portion of the metal surface are removed, and the metal surface is exposed (Kellen). After this, a coating film is formed by applying an epoxy resin coating to protect the metal surface from rusting.

 Keren improves the adhesion of the paint to the metal surface, changing the durability of the coating and the surface finish. For this reason, it is desirable to perform the coating process by applying one type of kelen (FIG. 7B) that completely removes rust, old paint film and fragile parts by blasting.

 However, one kind of keren requires labor, and it is necessary to sufficiently cure the dust, which increases the cost. In addition, with one kind of keren, it is necessary to collect a lot of removed rust and metal surface fragments, and it is necessary to prepare a working environment at the construction site. For this reason, in a normal painting method for a rusted metal surface, two types of kelen (Fig. 7C) or three or four types of kelen, which is simpler and less expensive than one type of kelen, are applied, and then an epoxy resin coating is applied. Painted.

  In the case of 2-4 type keren, a certain amount of metal surface is exposed, but the coating film which has not deteriorated remains, and as much as 1 type keren (FIG. 7B), the metal surface is not smoothed. For this reason, the unevenness | corrugation of a metal surface is still large, and the rust 72 of a recessed part also remains (FIG. 7C). In a normal coating method for a rusted metal surface, an epoxy resin coating is applied on such a metal surface to form a coating 73 (FIG. 8).

However, the epoxy resin coating is a coating having an oxygen permeability coefficient of 8.94 × 10 ⁻¹⁰ mol / m ² · s · Pa or more. Thus, the particles of the epoxy resin paint are not sufficiently small, and the surface tension against the metal surface is still large.

  For this reason, the epoxy resin paint tends to harden without penetrating into the recess formed by the metal surface and the residual rust 72. Therefore, the space | gap 81 exists between the coating film 73, the metal surface, and the residual rust 72, the contact area of the coating film 73 and a metal surface is not enough, and durability of the coating film 73 is low.

  Part of the epoxy resin paint comes into contact with the remaining rust 72a (on the right end of the metal base material 71 in FIG. 8). As described above, since the epoxy resin has a sufficiently small particle and a large surface tension, the epoxy resin hardly penetrates into the gap in the residual rust 72a. Therefore, the epoxy resin coating cannot fix the residual rust 72a to the metal base material 71 and peels off together with the residual rust 72a after being cured.

  When oxygen and moisture remain in the void 81, rust is generated again in the void 81. When this rust grows to some extent in the void 81, the coating film 73 is destroyed, and the coating film 73 peels from the metal surface.

As described above, since the epoxy resin paint has an oxygen permeability coefficient of 8.94 × 10 ⁻¹⁰ mol / m ² · s · Pa or more, the oxygen shielding performance of the coating film 73 is not sufficient, and the time There is a risk that oxygen will permeate into the gap 81 as the time passes. Thereby, when the water | moisture content remains in the space | gap 81, generation | occurrence | production of the rust in the space | gap 81 still cannot be suppressed.

  On the other hand, in order not to form the gap 81, it is necessary to apply another paint (such as a base film treatment liquid) before applying the epoxy resin paint. This takes time and effort.

The present invention has been made in view of such technical problems, the metal penetrates between recess and the remaining rust on the metal surface, applying a coating of an acrylic resin of a high oxygen blocking fine particle surface An object of the present invention is to provide a rust preventive coating method .

According to an aspect of the present invention, a step of applying an acrylic resin paint consisting only of a coating film component that forms a coating film after curing to the metal surface, and a step of curing the acrylic resin paint on the metal surface A rust preventive coating method for a metal surface on which rust is generated is provided.

  In the above aspect of the present invention, an acrylic resin paint is applied to the metal surface instead of the conventional epoxy resin paint. The oxygen permeability coefficient of this acrylic resin is lower than the oxygen permeability coefficient of the epoxy resin, and has finer particles than the epoxy resin particles.

  Since the acrylic resin having these fine particles (hereinafter referred to as “fine particle acrylic resin”) easily penetrates into the gap of the residual rust on the metal surface, the residual rust adheres to the metal surface by curing. Further, since the surface tension of the fine particle acrylic resin is smaller than the surface tension of the epoxy resin, the paint penetrates into the concave portion of the metal surface and adheres to the metal surface without forming the conventional void 81.

  Therefore, even if irregularities and residual rust exist on the metal surface, the residual rust can be fixed to the metal surface without forming voids, and a durable coating film can be formed.

FIG. 1 is a flowchart showing the steps of the coating construction method. FIG. 2 is a cross-sectional view of a metal base material whose surface is rusted. FIG. 3 is a cross-sectional view of the metal base material after applying keren to the rusted surface. FIG. 4 is a cross-sectional view of the metal base material after a fine particle acrylic resin coating is applied on the metal surface. FIG. 5 is an enlarged view of a portion indicated by a circle A in FIG. FIG. 6 shows the mechanism of rust formation on the metal surface. FIG. 7A is a cross-sectional view of a metal base material whose surface is rusted. FIG. 7B is a cross-sectional view of the metal base material after applying one kind of keren to the rusted metal surface. FIG. 7C is a cross-sectional view of the metal base material after applying two types of kelen to the rusted metal surface. FIG. 8 is a cross-sectional view of the metal base material after applying two types of kelen to the rusted metal surface and then applying and curing an epoxy resin paint.

  Hereinafter, an embodiment of the present invention of a method for painting a metal surface will be described in detail.

(First embodiment)
First, the process of the painting method will be described with reference to FIGS.

  FIG. 1 is a flowchart showing the steps of the coating construction method. FIG. 2 is a cross-sectional view of a metal base material whose surface is rusted. FIG. 3 is a cross-sectional view of the metal base material after applying keren to the rusted surface. FIG. 4 is a cross-sectional view of the metal base material after a fine particle acrylic resin coating is applied on the metal surface.

  First, keren is applied to the rusted metal surface (S1 in FIG. 1). As the target rusted metal surface 23 (FIG. 2), for example, metal surfaces such as guardrails, bridges, road signs, iron doors, steel towers and the like formed of metal materials, and rust is generated over time. A metal surface is mentioned. The metal surface may have a partially degraded coating. Moreover, other rusted metal surfaces, such as a structure comprised using a metal material and a steel material, a structural component, and various machines, may be sufficient.

  Kelene applied in the present invention may be about 2 to 4 kinds of kelen (FIG. 3), and is kelene that completely removes rust, coating film and fragile part on the metal surface 23, like 1 kind of kelen. There is no need. Keren in the present invention removes rust on the way from the metal surface 23, a deteriorated coating film, some fragile parts and deposits on the metal surface 23. The metal surface 23 is exposed to some extent by the keren, but a part of the rust 22 in the concave portion of the metal surface 23 remains (FIG. 3).

  The keren can be applied using a brush. However, other tools may be used, or other hand tools such as a broom or a paper file or a power tool may be used.

  The paint of the fine particle acrylic resin of the present invention is applied to the metal surface 23 after the above-mentioned keren is applied (S2 in FIG. 1). Details of the fine particle acrylic resin coating will be described later.

The fine particle acrylic resin is applied by a normal application method such as a brush, a roller, a trowel, or a spraying machine. The coating amount of the fine particle acrylic resin coating is 200 g / m ² . What is necessary is just to set the frequency | count of application | coating suitably, and it performs by application | coating 1-2 times normally. As a guideline, the time required for coating (pot life) is 30-40 minutes.

  After coating, the paint of the fine particle acrylic resin is cured to form the coating film 41 on the metal surface 23 and the residual rust 22 (S3 in FIG. 1, FIG. 4).

  The curing time of the fine-particle acrylic resin coating is usually 20 minutes-2 hours after application, and varies depending on the temperature and the temperature of the coating. A curing time of 20-30 minutes is required when the temperature is high such as summer, and a curing time of 1-2 hours is required when the temperature is low such as winter.

  Details of the fine particle acrylic resin paint used in the present invention will be described below.

  Table 1 shows the main composition of the fine particle acrylic resin paint. The paint of the fine particle acrylic resin is obtained by adding an additive (additive for producing viscosity and an additive as a curing agent) to the fine particle acrylic resin.

  The main components of the fine particle acrylic resin are dicyclopentenyloxyethylene and methacrylate, methoxypolyethylene glycol # 900 and methacrylate as a softening agent, and chloroprene as a softening agent.

  Among the above additives, additives for producing viscosity are aerosil and aluminum powder. Thereby, the adhesiveness of the coating material to the metal surface 23 is improved, and the dripping of the coating material on the inclined metal surface 23 is prevented.

  Among the above additives, the additive as a curing agent is a peroxide. This peroxide is added to the fine particle acrylic resin immediately before it is applied to the metal surface 23.

  In addition to the above additives, retarders and accelerators may be mixed in a certain ratio. Examples of the retarder include alkylphenol. Accelerators include cobalt naphthenate.

The oxygen permeability coefficient of the fine particle acrylic resin is 1.54 × 10 ⁻¹⁴ mol / m ² · s · Pa. This oxygen permeability coefficient is obtained according to the test method JISK7126. This oxygen permeability coefficient is smaller than the oxygen permeability coefficient (8.94 × 10 ⁻¹⁰ mol / m ² · s · Pa) of a normal epoxy resin. Thus, the fine particle acrylic resin particles are smaller than the normal epoxy resin particles.

The moisture permeability of the fine particle acrylic resin is 14 g / m ² · 24 h. This moisture permeability is obtained according to the test method JISK5400.

  The water permeability of the fine particle acrylic resin is 0.06 g. This water permeability is obtained in accordance with the test method JISK6203.

  When the metal base material 21 is iron, the adhesiveness of the fine particle acrylic resin to the metal surface 23 is 7.8 MPa. When the metal base material 21 is stainless steel or aluminum, the adhesion of the fine particle acrylic resin to the metal surface 23 is 7.8 MPa and 8.8 MPa. These adhesive properties are obtained by an autograph tensile test. In this test, two pieces of the above-mentioned metal base material are bonded with a fine particle acrylic resin, and each is pulled with an autograph tensile tester from the opposite direction.

  The viscosity of the fine particle acrylic resin paint is 80-100 mPa · s, and the specific gravity is 1.2.

(Action / Effect)
FIG. 5 is an enlarged view of a portion indicated by a circle A in FIG. Oxygen permeability coefficient of the paint used in the present invention, as described above, was ^{1.54 × 10 -14 mol / m 2} · s · Pa, the oxygen permeability coefficient of the conventional epoxy resin (8.94 × 10 ^{- 10} mol / m ² · s · Pa). Thus, the paint particles used in the present invention are smaller than the epoxy resin paint particles.

  Thereby, since the coating material of the fine particle acrylic resin penetrates into the gap of the residual rust 22 on the metal surface 23 and cures (FIG. 5), the residual rust 22 can be fixed to the metal surface 23.

  Further, the fine particle acrylic resin paint has a lower surface tension than the epoxy resin paint, and therefore penetrates into the recesses on the metal surface 23. Therefore, the coating film 41 does not form the conventional void 81 (FIGS. 4, 5, and 8), and can secure a contact area with the metal surface 23 and improve durability.

The oxygen permeability coefficient of the fine particle acrylic resin is 1.54 × 10 ⁻¹⁴ mol / m ² · s · Pa, which is lower than the oxygen permeability coefficient of the epoxy resin. The water permeability of the fine particle acrylic resin is 0.06 g, which is less than the water permeability of the epoxy resin (usually 0.15-0.25 g). Therefore, rust is prevented from being regenerated between the coating film 41 and the metal surface 23, and the durability of the coating film 41 is improved.

  As described above, the fine particle acrylic resin paint penetrates into the recesses of the metal surface 23 and penetrates into the gaps of the remaining rust. For this reason, the other coating material which fills the space | gap of the conventional space | gap 81 and the residual rust 22 is unnecessary, and the coating film 41 can be formed saving time and an effort.

  Since the coating material of the fine particle acrylic resin has air anaerobic property, the surface in contact with air (oxygen) is finally cured. For this reason, when the paint of the fine particle acrylic resin is applied, it hardens while expelling air in the recesses on the metal surface 23 and in the gaps of the remaining rust. Therefore, the coating film 41 adheres firmly to the metal surface 23 and the durability of the coating film 41 is improved.

  The viscosity of the fine particle acrylic resin coating is as low as 80-100 mPa · s. For this reason, it is easy to apply repeatedly, and the thickness of the coating film 41 can be changed according to the unevenness of the metal surface 23.

  The fine particle acrylic resin is excellent in weather resistance as compared with the epoxy resin coating. Therefore, it is possible to form the coating film 41 that is more durable than the conventional coating film 73.

(Second Embodiment)
The fine particle acrylic resin paint used in the second embodiment will be described. In this embodiment, a heat insulating material is mixed in the paint of the fine particle acrylic resin of the first embodiment to make a paint.

  A commercially available heat insulating agent may be used as the heat insulating agent, and examples thereof include polyether ether ketone (PEEK) and liquid crystal polyester (LCP).

  By applying the coating material, a coating film 41 for rust prevention and heat insulation can be formed on the metal surface 23. Therefore, the construction for rust prevention and the construction for heat insulation can be performed simultaneously.

(Third embodiment)
The fine particle acrylic resin paint used in the third embodiment will be described. In this embodiment, a colorant is mixed in the fine particle acrylic resin paint of the first embodiment.

  Table 2 shows the formulation of the fine particle acrylic resin paint.

  As shown in Table 2, a colored paint can be generated by adding an aggregate to the fine particle acrylic resin. By selecting another color as the aggregate, a paint of a desired color can be obtained.

  Although several embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the invention described in each of the claims. For example, in the summer, that is, when the outside air is at a high temperature, the amount of the curing agent mixed with the fine particle acrylic resin can be reduced. Further, in the winter season, that is, when the outside air is at a low temperature, the curing becomes slow, so that the amount of the curing agent can be increased. You may apply | coat the coating material of the said fine particle acrylic resin to the metal surface which is a metal surface (unused metal surface) which is not rusting, and is uneven. Even in this case, the paint penetrates into the unevenness of the metal surface, and the same effect as described above can be obtained.

21, 71 Metal matrix 22, 72 Rust 23 Metal surface 41 Paint film 51 Fine particle acrylic resin particle 73 Epoxy resin film 81 Void

Claims (7)

A rust preventive coating method for a metal surface that targets a rusted metal surface ,
Applying an acrylic resin paint consisting only of a coating film component that forms a coating film after curing to the metal surface;
Curing the acrylic resin paint on the metal surface,
An antirust coating method for metal surfaces characterized by the above. Before the step of applying, further includes a step of cleansing the metal surface where rust has occurred,
The rust preventive coating method for a metal surface according to claim 1. The keren is four kinds of keren,
The rust preventive coating method for metal surfaces according to claim 2. The acrylic resin paint is obtained by adding an additive to the main component of the acrylic resin,
The main agent consists of sidiclopentenyl oxyethylene, methacrylate, methoxypolyethylene glycol 900 # and chloroprene.
The rust preventive coating method for a metal surface according to any one of claims 1 to 3. The additive includes a retarder and an accelerator,
The retarder is an alkylphenol;
The accelerator is cobalt naphthenate,
The rust preventive coating method for metal surfaces according to claim 4. Further comprising mixing a colorant into the acrylic resin paint,
Coloring the coating,
The rust preventive coating method for a metal surface according to any one of claims 1 to 5. The metal surface is a metal surface of a guardrail, a bridge, a road sign, an iron door, or a steel tower formed of a metal material, and is a metal surface on which rust has occurred over time,
The rust preventive coating method for a metal surface according to any one of claims 1 to 6.

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