JP6700148B2 - How to paint metal - Google Patents

Description

  The present invention relates to a method for coating a metal such as a guardrail.

  Various metals are used in many buildings, pipes, roads and the like. These metals corrode when they come into contact with water, seawater, moisture in the air, moisture in the soil, and the like. It is explained that many of these corrosion phenomena of metals in the external environment are electrochemical reactions (battery action) accompanied by ion elution and electron transfer that occur in the presence of two electrodes having different potentials. It is said that this corrosion includes micro cell corrosion and macro cell corrosion. Macrocell corrosion includes air flow difference type macrocells, dissimilar metal contact type macrocells, dissimilar soil contact type macrocells, and concrete soil type macrocells depending on the environment in which metal is present.

  As measures against these metal corrosions, means such as substitution of materials other than metal, coating with corrosion resistant coating, cathodic protection, and non-formation of batteries are adopted. However, metal materials are still widely used because of their excellent strength, workability, and low cost. Therefore, the means for performing corrosion resistant coating on metals is important.

  Although various coating means have been adopted as the corrosion resistant coating, for example, an aqueous primer composition in which a thermosetting, self-emulsifying epoxy resin and a thermosetting non-self-emulsifying resin composition are used in combination (Patent Document 1) ), a method for coating a coil in which a primer coating composition and a top coat film are cured together (Patent Document 2).

Japanese Patent Publication No. 2010-539314 Special table 2011-522689 gazette

However, although the conventional coating means can suppress the corrosion of the portion that is in contact with water or seawater by coating the metal surface, the above-mentioned macrocell corrosion can hardly be suppressed.
Therefore, the present invention is to provide a new coating method capable of suppressing macrocell corrosion of metal.

  Therefore, the present inventor has conducted a study to find out a coating means capable of effectively suppressing the macrocell corrosion of metal. For example, the inventors have found that it is possible to suppress corrosion of metals such as guard rails and reinforcing bars in bridge piers that cause macro cell corrosion, and have completed the present invention.

  That is, the present invention provides the following [1] to [5].

[1] With respect to the metal part, (1) highly alkaline aqueous primer treatment, and then (2) (A) water-dispersed polyester resin and (B) acrylic resin emulsion in mass ratio (A:B) 1:4 to 4: A coating method for a metal part, which comprises performing a sealing treatment with a treating agent contained in the range of 1.
[2] The coating method according to [1], wherein after (2) the sealing treatment, (3) a top coat treatment with a resin-based paint is further performed.
[3] The coating method according to [1] or [2], wherein the metal part is a metal part selected from guardrails, bridge piers, reinforcing bars, pipes, walls, steel frames and mechanical equipment.
[4] The coating method according to any one of [1] to [3], wherein the highly alkaline aqueous primer treatment is a primer treatment with an inorganic salt.
[5] (3) The topcoat treatment with resin-based paint is selected from water-soluble polyurethane resin paint, water-soluble acrylic resin paint, polyurethane-silicone resin paint, acrylic-silicone resin paint, and asphalt resin paint The coating method according to any one of [2] to [4], which is a topcoat treatment with a resin-based paint.

  According to the coating method of the present invention, macrocell corrosion is remarkable in guardrails, bridge piers, reinforcing bars, pipes, walls, steel frames, mechanical equipment, etc. simply by performing primer treatment and sealing treatment, or primer treatment, sealing treatment and topcoat treatment. Can be suppressed to.

  In the coating method of the present invention, the metal part is treated with (1) highly alkaline aqueous primer, and then (2) (A) water-dispersed polyester resin and (B) acrylic resin emulsion in a mass ratio (A:B) of 1: It is characterized by performing a sealing treatment with a treating agent contained in a range of 4 to 4:1.

  The object of coating of the present invention is a metal part. The metal is not limited as long as it is a metal that causes corrosion, and includes iron, steel, zinc, aluminum, chromium, nickel, tin, etc., but since iron and steel are widely used, iron and steel are used. It is preferably targeted.

  Examples of metal parts using these metals include guardrails, bridge piers, reinforcing bars, pipes, walls, steel frames, and mechanical equipment. Of these, corrosion is a major problem for guardrails, piping, and mechanical equipment, and it is preferable to target these metal parts.

  The target metal part may remove the corrosive dust on the surface of the target metal part using a cloth, a brush or the like impregnated with the primer of (1) before the primer treatment.

  (1) The highly alkaline aqueous primer treatment is intended to raise the pH of the surface of the target metal part and make it an alkaline environment atmosphere to suppress re-deterioration of the oxidation-degraded part of the target metal part surface. The primer treatment agent is preferably a treatment with a highly alkaline inorganic salt aqueous solution. Here, the inorganic salt aqueous solution is preferably a highly alkaline aqueous solution such as a lithium silicate aqueous solution, a lithium nitrite aqueous solution, and a sodium hydroxide aqueous solution. Among these, the lithium silicate aqueous solution is preferable, and the pH of the aqueous solution is preferably 9 to 13, and more preferably 10 to 12.

(1) In the highly alkaline aqueous primer treatment, the amount of the active ingredient of the primer is preferably 50 to 150 g per 1 m ^{2 of} metal, and varies depending on the target metal surface condition. Examples of the coating means include brush coating, roller coating and spray coating.

  After the primer layer is dried, (2) (A) a water-dispersed polyester resin and (B) an acrylic resin emulsion are contained in a mass ratio (A:B) in the range of 1:4 to 4:1. Perform processing. Macrocell corrosion of metal can be significantly suppressed by the sealing treatment.

  The (A) water-dispersed polyester resin used in the sealant is a water-dispersible polyester resin obtained from a diol and a dicarboxylic acid. Examples of the diol include one or more selected from bisphenol A, a diol obtained by adding ethylene oxide, propylene oxide and the like to bisphenol A, and an aliphatic diol. Examples of the dicarboxylic acid include fumaric acid, isophthalic acid, maleic acid and the like.

  A more preferable water-dispersed polyester is a polymer obtained by polymerizing fumaric acid or isophthalic acid in an alcohol monomer obtained by adding ethylene oxide or propylene oxide to bisphenol A, and dissolving it in a ketone solvent, adding a neutralizing agent, A self-dispersion type water-based polyester resin composition in which a carboxyl group is ionized, water is added thereto, and then a ketone solvent is distilled off to invert the phase into an aqueous system is mentioned.

  The average molecular weight of the water-dispersed polyester resin is preferably 2500 to 70000, and the particle size is preferably 0.001 to 10 μm, more preferably 0.001 to 1.0 μm. The flexibility of the polyester coating film can be increased by adding a plasticizer to the water-dispersed polyester.

  As the water-dispersed polyester, commercially available products such as "New Track 2010" and "New Track 2011" with Kao Plasticizer added, and "New Track 2040" with no plasticizer added can be used. Can be used.

  The (B) acrylic resin emulsion used for the sealant is a copolymer of styrene and one or more (meth)acrylic acid-based monomers selected from (meth)acrylic acid and (meth)acrylic acid ester. Combined emulsions are preferred. More preferably, a styrene-(meth)acrylic acid alkyl ester copolymer emulsion and a styrene-(meth)acrylic acid alkyl ester-(meth)acrylic acid copolymer emulsion are mentioned. As the acrylic acid alkyl ester, 2-ethylhexyl (meth)acrylate or n-butyl (meth)acrylate is preferably used to prevent hydrolysis by alkali.

  The nonvolatile content of the acrylic resin emulsion is preferably 30 to 60%, and more preferably 45 to 55% from the viewpoint of film forming property. The glass transition point (Tg) is preferably -20°C to 30°C, and more preferably -20°C to 10°C from the viewpoint of adhesion.

  As the acrylic resin emulsion, those generally commercially available such as acrylic emulsion manufactured by E-Tech Co., Ltd., styrene-butyl acrylate (meth)acrylic acid ammonium salt manufactured by High Pressure Gas Industry Co., Ltd. can be used.

  In the sealing agent, it is important that the content mass ratio (A:B) of the component (A) and the component (B) is 1:4 to 4:1 from the viewpoint of anticorrosion, and 3:7 to. 7:3 is more preferable, and 2:3 to 3:2 is particularly preferable.

  In addition to the components (A) and (B) described above, a defoaming agent, a stabilizer, a pigment and the like can be added to the sealant. When the components (A) and (B) are mixed and used, (A) 20 to 80% by mass and (B) 80 to 20% by mass may be mixed, and (A) 30 to 70% by mass ( It is preferable to mix 70 to 30% by mass of B), more preferably 40 to 60% by mass of (A) and 60 to 40% by mass of (B).

  There is no particular limitation on the mixing method of the component (A) and the component (B), and they can be mixed at an arbitrary ratio with a normal stirring device such as a homomixer.

In the sealing agent treatment, 50 to 150 g is preferable and 70 to 120 g is more preferable as the amount of the active ingredient of the sealing agent per 1 m ^{2 of} metal. Examples of the coating means include brush coating, roller coating and spray coating.

  In the coating method of the present invention, the above-mentioned (1) primer treatment and (2) sealing treatment may be carried out, and further, (3) resin-based topcoat treatment is carried out for corrosion resistance, physical impact resistance and water resistance. It is preferable in terms of heat resistance, heat resistance and aesthetics. The topcoat treatment is preferably performed after the seal treatment layer has dried.

  (3) Examples of the resin-based paint for the top coat treatment agent include water-soluble polyurethane resin paints, water-soluble acrylic resin paints, polyurethane-silicone resin paints, acrylic-silicone resin paints, and asphalt resin paints. Among these, a water-soluble polyurethane resin coating material is preferable from the viewpoint of adhesive properties with the seal treatment agent. 7-8 are preferable and, as for pH of a topcoat processing agent, 7 is more preferable.

Further, an antifoaming agent, a stabilizer, a pigment and the like can be added to the top coat treating agent.
The topcoat treatment preferably has a topcoat coating thickness of 50 μm to 350 μm, more preferably 100 μm to 300 μm. Examples of the coating means include brush coating, roller coating and spray coating.

  By carrying out the coating according to the present invention, various kinds of corrosion on metal parts, particularly macrocell corrosion, can be remarkably suppressed. Therefore, deterioration of metal parts in various structures, guard rails, bridge piers, reinforcing bars, pipes, walls, steel frames, mechanical equipment, etc. can be suppressed, and the durability of these metal parts is improved.

  Next, the present invention will be described in detail with reference to examples.

Example 1
(1) Primer treatment agent A highly alkaline aqueous primer "AMC primer" manufactured by Wada Shoten Co., Ltd. was used as a primer treatment agent.
(2) Sealing agent E-Tech acrylic emulsion "C-420-A1" (B1) and Kao "New Track 2040" (A1), Toagosei Co., Ltd. water-penetrating water-absorption inhibitor "Aquaproof" ( A2), Asahi Kasei Geotech Co., Ltd. silane/siloxane high performance penetrating waterproofing material "Magical Repeller" (A3) or Sumitomo Seika Silane Emulsion "Aquaseal 50E" (A4) in a mass ratio of 50:50 or 30. : 70 was used as the sealing treatment agent.
(3) Topcoat treating agent A water-soluble polyurethane resin paint "Aqueous Compourethane" manufactured by SK Kaken Co., Ltd. was used as a topcoat treating agent.

(4) 80 g per 1 m ^{2 of} iron guardrail was applied with a brush and dried. Next, 100 g of a seal treatment agent (A:B=50:50) was applied with a brush per 1 m ^{2 of} the guard rail. Further, the topcoat treatment agent was applied by brush with a coating thickness of 150 μ (applied twice).

(5) After 4 years, the treated guardrail had no corrosion. On the other hand, the untreated guardrail existing in the same place was corroded. Even when the top coat was not applied, there was a sufficient corrosion inhibiting effect.

Example 2
(1) Primer treatment agent A highly alkaline aqueous primer "AMC primer" manufactured by Wada Shoten Co., Ltd. was used as a primer treatment agent.
(2) Sealing agent E-Tech acrylic emulsion "C-420-A1" (B1) and Kao "New Track 2040" (A1), Toagosei Co., Ltd. water-penetrating water-absorption inhibitor "Aquaproof" ( A2), a silane/siloxane-based high-performance penetrating waterproofing material “Magical Repeller” (A3) manufactured by Asahi Kasei Geotech, or a silane emulsion “Aquaseal 50E” (A4) manufactured by Sumitomo Seika Co., Ltd. in a mass ratio of 50:50 or 30. : 70 was used as the sealing treatment agent.

(3) 80 g per 1 m ^{2 of} primer treatment agent was brushed onto the deteriorated reinforcing bar portion of the concrete silo where the surface layer concrete portion was peeled off due to expansion of the reinforcing bar deteriorated portion due to salt damage, and then dried. Next, 100 g of a sealing treatment agent (A:B=50:50) was applied with a brush per 1 m ^{2 of} the deteriorated reinforcing bar portion. Further, the topcoat treatment agent was applied with a brush at a coating thickness of 150 μ (double coating meter).
(4) After 2 years, the deteriorated reinforcing bar portion of the treated concrete silo was not corroded. On the other hand, the deteriorated rebar existing in the same concrete silo was corroded.

Claims (5)

A mass ratio of (1) highly alkaline aqueous primer treatment, and then (2) (A) water-dispersed polyester resin and (B) acrylic resin emulsion having a nonvolatile content of 30 to 60% to a metal portion selected from iron and steel ( A:B) Coating of a metal part, which is contained in a range of 1:4 to 4:1 and is subjected to a sealing treatment with a treating agent containing neither the crosslinking agent of A and B nor the zirconium compound or the titanium compound. Method.   The coating method according to claim 1, further comprising: (2) after the sealing treatment, and (3) a top coat treatment with a resin-based paint.   The coating method according to claim 1 or 2, wherein the metal portion is a metal portion selected from guardrails, bridge piers, reinforcing bars, pipes, walls, steel frames and mechanical equipment.   (1) The coating method according to any one of claims 1 to 3, wherein the highly alkaline aqueous primer treatment is a primer treatment with an inorganic salt.   (3) The resin-based top coating is selected from water-soluble polyurethane resin coatings, water-soluble acrylic resin coatings, polyurethane-silicone resin coatings, acrylic-silicone resin coatings, and asphalt resin coatings. The coating method according to any one of claims 2 to 4, which is a top coat treatment according to.