JP2007284600A - Coating composition containing high corrosion-proof zinc powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zinc powder-containing coating exhibiting high corrosion-proof property and having good adhesiveness. <P>SOLUTION: The coating composition containing highly corrosion-proof zinc powder comprises (A) 100 pts.mass (based on solid content) binder resin, (B) 200-800 pts.mass zinc powder, (C) 1-95 pts.mass corrosive ion-fixing agent and (D) 200-1,000 pts.mass solvent for dispersing the above component. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a zinc dust-containing coating composition. More particularly, the present invention relates to a highly anticorrosive coating composition that is useful as a primary rust-preventive paint or undercoat paint for large steel structures and detoxifies corrosive ions as a function not found in conventional zinc dust-containing paints.

  Zinc dust-containing paints in which a relatively large amount of zinc dust is blended into a binder resin are widely used for the purpose of anticorrosion of ships, bridges, tanks, plants, marine structures and the like. Zinc powder-containing paints are roughly classified into organic zinc powder-containing paints and inorganic zinc powder-containing paints depending on the type of binder resin used.

  Organic zinc powder-containing paints are generally made by adding a large amount of zinc powder to a binder resin such as epoxy resin, urethane resin, acrylic resin, etc. It has the characteristic that the applicability to is good.

  On the other hand, since the anticorrosion function and the cohesive force of the coating film are somewhat insufficient, it is not often used when long-term anticorrosion is important. In contrast, inorganic zinc dust-containing paints generally use alkyl silicate resins as binders and have excellent anti-corrosion function and durability of the coating film, especially for long-term anti-corrosion purposes for large steel structures. Although it is suitable, it cannot be said that the substrate adjustment work and the painting workability are easy, and therefore it is necessary to carefully perform substrate adjustment such as polishing and blasting of the substrate. In general, blasting is basically used. Furthermore, the adhesion of the coating film is insufficient.

  In paints containing a large amount of zinc powder, attempts have been made to further improve the high corrosion resistance and adhesion. However, in any zinc powder-containing paint, a method for improving the anticorrosion properties by adding other components is mainly not effective. For example, a method for improving the anticorrosion property by blending a metal powder other than zinc powder in a zinc powder paint is disclosed. (For example, refer to Patent Document 1). Although the anticorrosion properties are slightly improved by the metal powder other than the zinc powder, the coating stability is insufficient such that precipitation is likely to occur, and it is difficult to form a good coating film. In addition, a rust preventive coating composition containing needle-like or long columnar calcium metasilicate to prevent cracking or peeling of the coating (for example, see Patent Document 2), commercially available products such as magnesium phosphate and aluminum phosphomolybdate. A rust preventive paint composition to which a rust preventive pigment is added (for example, see Patent Document 3) is disclosed. However, these needle-like or fibrous materials have poor permeability when meshed for use in filtration, so the yield when adjusting the powder component in the pre-process of paint production is poor, resulting in blend blurring, There was a problem that the spray of the coating machine was clogged during painting. Further, commercially available rust preventive pigments form coatings with good anticorrosion properties due to moisture that has permeated, but these coatings tend to be formed on the surface of the zinc powder and inhibit the sacrificial anticorrosive action of zinc powder.

  In addition, when it is time to repaint existing steel structures, many red rusts are usually generated on the surface of steel materials. Can not protect from rust for a period. One reason for this is that corrosive ions contained in the rust layer remain.

Therefore, conventionally, after rusting the surface of the steel material by blasting etc. before painting, a method of painting the paint, or after removing floating rust etc. on the steel surface before painting, tannic acid, etc. A rust conversion agent containing a rust was applied, and the brittle hydrated oxide, which is the main component of red rust, was converted to hard Fe ₃ O ₄ , which is the main component of black rust, and a paint was applied.

However, the former method has a problem that not only the working environment is deteriorated but also the working efficiency is very bad at the time of rust removal. Furthermore, in general repainting, 2 or 3 types of keren are applied to the steel surface, but the rust of the steel structure is difficult to remove, and the rust layer and iron base at that location are difficult to remove. the interfacial, Cl ^- and, sO ₄ ^2-like corrosive ionic materials are likely to remain, the water also present, be painted repaint Therefore, corrosion resistance at that point is substantially reduced There was a problem to do.

  In the latter method, although the rust layer is strengthened, it is impossible to remove the corrosive ionic substance in the recessed portion and the narrow portion, and tannic acid is soluble in water. The formed anticorrosion coating film is easy to blister over time, and as a result, peeling easily occurs, and there is a problem that the long-term anticorrosion property at that portion is poor.

JP-A-52-54724 JP-A-62-181370 Japanese Patent Publication No. 2002-348686

In view of such circumstances, the object of the present invention is to efficiently collect and fix corrosive ionic substances such as Cl ⁻ and SO ₄ ²⁻ that adhere to the steel surface by using a corrosive ion fixing agent or the like. It is an object of the present invention to provide a highly anticorrosive zinc powder-containing coating material that controls elution of zinc powder and exhibits higher corrosion resistance and adhesion than conventional zinc powder-containing coating materials.

  On the other hand, corrosive ion immobilizing agents generally have a very large amount of water solubility and often cause blistering and peeling when mixed in paints, and are difficult to use as rust inhibitors. The object of the present invention is to eliminate such inconveniences and to exhibit the original functions by optimizing the blending amount and blending method. In particular, it is an object of the present invention to provide a highly anticorrosive zinc dust coating that does not exist in conventional zinc dust-containing paints, when a two or three types of kelen are applied in repainting, whereby a corrosive ion fixing agent acts effectively.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-described problems can be achieved by the following configurations, and have reached the present invention.
The present invention is as follows.

  (1) (A) Binder resin 100 parts by mass (solid content weight), (B) Zinc powder 200 to 800 parts by mass, (C) Corrosive ion fixing agent 1 to 95 parts by mass, (D) Solvent 200 to 200 A highly anticorrosive zinc dust-containing coating composition containing 1000 parts by mass.

  (2) The highly anticorrosive zinc dust-containing coating composition according to the above (1), wherein the component (A) is an inorganic resin or an organic resin.

(3) Inorganic resin of component (A) is a partially hydrolyzed condensate of alkyl silicate or general formula R ₂ O · nSiO ₂ (wherein R is an alkali metal atom, n is a positive number of 1.0 to 4.5) The highly anticorrosive zinc dust-containing coating composition according to the above (2), which is an aqueous dispersion of a water-soluble silicate and colloidal silica.

  (4) The highly anticorrosive zinc dust-containing coating composition as described in (2) above, wherein the organic resin as the component (A) is selected from an epoxy resin, an acrylic resin, and a urethane resin.

  (5) The highly anticorrosive zinc dust-containing coating composition according to any one of (1) to (4), wherein the component (C) is hydrocalumite or hydrotalcite.

  (6) The highly anticorrosive zinc dust-containing coating composition according to any one of (1) to (5), further comprising (E) a coupling agent.

  According to the present invention, the amount of water dissolved is very large, and when using a corrosive ion immobilizing agent that causes blistering or peeling when blended in a paint, it is prevented and high corrosion resistance and adhesion are achieved. The zinc dust-containing paint shown can be provided.

The present invention will be described in detail below.
The (A) binder resin used in the present invention may be organic or inorganic, and may be aqueous or solvent-based.

  The organic binder resin may be any commercially available resin such as an epoxy resin, a modified epoxy resin, an acrylic resin, or a urethane resin. Particularly preferred are epoxy resins, acrylic resins and urethane resins which have good anticorrosion properties and adhesion to the substrate.

Further, the aqueous organic binder resin is obtained by introducing a hydrophilic functional group such as —OH, —NH ₂ , or —COOH into the above resin or the like to make it water-dispersed or water-soluble.

  Examples of the inorganic binder resin used in the present invention include a partially hydrolyzed condensate of alkyl silicate or a modified product thereof. For example, tetramethylorthosilicate, tetraethylorthosilicate, tetrapropylorthosilicate, tetrabutylorthosilicate, tetrapentylorthosilicate, tetrahexylorthosilicate, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane , Ethyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, amyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, etc. The rate is preferably 50 to 98%. These hydrolysates may be derivatives obtained by reacting with other organic polymer compounds. You may use these individually or in combination of 2 or more types.

  Specifically, for example, ethyl silicate 40 (manufactured by Colcoat Co., Ltd.), ethyl silicate 40 (manufactured by Tama Chemical Co., Ltd.), Silver 40 (manufactured by Stauffer Chemical Co.), Ethyl Silicate 40 (manufactured by Union Carbide Co.), etc. There is.

In addition, as the water-based inorganic binder resin, a general formula R ₂ O · nSiO ₂ (I)
(Wherein R represents an alkali metal atom, and n represents a positive number of 1.0 to 4.5). At least one selected from the group consisting of an aqueous dispersion of a water-soluble silicate and colloidal silica. It is a seed binder. In the above general formula (I), examples of the alkali metal atom represented by R include lithium, sodium, and potassium.

  A conventionally well-known thing can be widely used for the water-soluble silicate represented by general formula (I).

  Moreover, in this invention, said organic type or inorganic type binder resin can be used individually by 1 type or in mixture of 2 or more types. A mixture of organic and inorganic binder resins can be used, and a reaction product of organic and inorganic binder resins can also be used.

  As the (B) zinc powder used in the present invention, conventionally known zinc powder can be used as long as zinc is eluted and has a sacrificial anodic action.

  Moreover, the particle size of zinc powder is usually in the range of 1 to 100 μm, and the preferred particle size is in the range of 3 to 7 μm. When zinc powder particles having the above particle size range, particularly the above preferable particle size range, are used, it is possible to obtain a coating film having better workability during coating and having a more uniform appearance.

  The amount of zinc powder to be blended in the paint of the present invention is 200 to 800 parts by mass with respect to 100 parts by mass of the solid content of the binder resin. Preferably, it is 250-700 mass parts. If it is less than 200 parts by mass, the anticorrosion properties are insufficient, and if it is 800 parts by mass or more, the physical properties and the appearance of the coating film are poor. In addition, the binder resin cannot be sufficiently bonded to the substrate surface, and the adhesion of the coating film is poor.

Next, (C) the corrosive ion fixing agent will be described.
Component (C) collects corrosive ionic substances such as Cl ^- and SO ₄ ^2- present at the interface between the rust layer and the iron base and reacts chemically to form a water-insoluble double salt. It is a corrosive ion immobilizing agent for immobilizing and deactivating reactive ions. Even if a corrosive ionic substance remains on the surface of the steel material, the fixing agent is inactivated, so that it is possible to prevent the corrosion resistance from being lowered.

  Typical examples of such corrosive ion fixing agents include hydrocalumite and hydrotalcite.

Hydrocalumite has the formula
3CaO ・ Al ₂ O ₃・ CaX _{2 / m}・ nH ₂ O
(In the formula, X represents a monovalent or divalent anion, m represents the valence of the anion, and n represents 20 or less.)
A water-containing crystalline powder having a layered structure represented by Representative examples of the anion (X) include NO ₃ ⁻ , NO ₂ ⁻ , OH ⁻ , CH ₃ COO ⁻ , CO ₃ ^{2− and the} like. These anions, and chlorine ions when contacted with sulfuric acid ion, etc., anion exchange, NO ₃ is X ^-, NO ₂ ^- with liberating the like, fixing the corrosive ionic material in hydrocalumite (supported) And inactivate. In addition, the liberated anion has an effect of forming a passive film on the surface of the steel material and further improving the corrosion resistance.

Hydrotalcite is typically a formula,
Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ · nH ₂ O
(In the formula, n is 4 or less, preferably 3.5.)
It is a hydrous crystalline powder with a layered structure shown in Fig. 1. When it comes into contact with corrosive ionic substances like hydrocalumite, it exchanges anions, immobilizes corrosive ions in hydrotalcite, and does not desorb from the crystal structure. It has the ability.

The amount of the corrosive ion fixing agent to be blended in the coating material of the present invention is 1 to 95 parts by mass with respect to 100 parts by mass of the solid content of the binder resin. Preferably it is 5-50 mass parts. If it is less than 1 part by mass, it cannot collect all of the corrosive ionic substances such as Cl ^- and SO ₄ ^2- existing at the interface between the rust layer and the iron base, so that the corrosion resistance is insufficient, and 95 parts by mass Exceeding will cause blistering and peeling, resulting in poor corrosion resistance.

  The (D) solvent used in the present invention may be either an organic solvent or water as long as it can dissolve or disperse the above components (A) to (C).

  Examples of organic solvents include aromatic solvents such as toluene and xylene, alcohol solvents such as ethanol, methanol, and butanol, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and ether solvents such as propylene glycol monomethyl ether and ethylene glycol monomethyl ether. Solvents and ester solvents such as butyl acetate and ethyl acetate are used.

  When the paint form is aqueous, water is applied as the solvent. In that case, a water-soluble organic solvent may be further added. Examples of the water-soluble organic solvent include methanol, ethanol, 1-propanol, 2-propanol, t-butyl alcohol, ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, glycerin, acetone, and methyl. Examples thereof include cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, propyl carbitol, butyl carbitol, diacetone alcohol and the like.

  (D) The compounding quantity of a solvent is 200-1000 mass parts with respect to 100 mass parts (solid content) of binder resin, Preferably it is 200-600 mass parts. When the amount is less than 100 parts by mass, the viscosity of the coating is increased, and the coating stability and the coating workability are inferior. On the other hand, when the amount is more than 1000 parts by mass, the viscosity of the coating becomes too low to provide a prescribed film thickness (50 μm or more).

  Moreover, the said coupling agent (E) is a coupling agent for improving the wettability and impregnation property to the rust layer of steel materials, and improving the adhesiveness with the coating material coated on it. Examples of the coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltriethoxysilane, Silane coupling agents such as γ-methacryloxytrimethoxysilane and γ-mercaptopropyltrimethoxysilane; isopropyl triisostearoyl titanate, tetraoctylbis (didodecyl) phosphite titanate, isopropyltrioctanoyl titanate, isopropyltridodecylbenzene Typical examples include titanium-based coupling agents such as sulfonyl titanates; aluminum-based coupling agents, zirconium-based coupling agents, and the like.

  Component (E) is added to improve wettability and impregnation to the rust layer, and to improve adhesion to the paint to be coated on, but 0 to 10 parts by mass is added. Preferably, 0.5-5 mass parts is mix | blended. If the amount is more than the above range, the improvement of the effect is not recognized, which is disadvantageous economically.

  The blending ratio of each component constituting the zinc powder-containing paint of the present invention is as follows: (A) 100 parts by mass of binder resin (solid content weight), (B) 200 to 800 parts by mass of zinc powder, (C) corrosive ion immobilization. 1 to 95 parts by weight of the agent, preferably 5 to 50 parts by weight, (D) 200 to 1000 parts by weight of the solvent, and (E) the coupling agent is 0 to 10 parts by weight, preferably 0.5. -5 parts by mass.

  In the coating composition of the present invention, a dispersant may be used for uniformly dispersing the zinc powder and the corrosive ion fixing agent. Dispersing agents include cationic systems such as quaternary ammonium salts, anionic systems such as carboxylates, sulfonates, sulfate esters, phosphate esters, ether types, ether ester types, ester types, nitrogen-containing types, etc. Nonionic system of

  In addition, an anti-sagging agent, a pigment or the like can be blended as an additive used. Anti-sagging agents are usually blended in paints to develop structural viscosity and impart thixotropy to the paints. For example, amorphous silica, colloidal calcium carbonate, organic bentonite, hydrogenated castor oil, aliphatic amides. Higher fatty acids, microgel particles, and the like. These are used singly or in combination of two or more. Particularly, an organic bentonite-based sagging inhibitor is preferable because it exhibits a large structural viscosity with a small amount of addition.

  Moreover, as a pigment, the extender pigment, rust preventive pigment, and coloring pigment which are used for a normal rust preventive paint can be used. Specific examples include talc, mica, barium sulfate, clay, calcium carbonate, zinc oxide, titanium dioxide, bengara, zinc phosphate, aluminum phosphate, barium metaborate, aluminum molybdate, iron phosphate, etc. It is used alone or in combination of two or more.

  The paint can be adjusted in accordance with a conventional method, and a method of mixing both paints immediately before use is common. For the dispersion of the liquid component and the powder component, a roll mill, a sand grind mill, a media mill such as a ball, which is usually used for dispersion of a paint, a disper disperser, or the like can be used.

  The zinc powder-containing paint thus formed is applied to a steel structure or the like by means of air spray, airless spray, roll coater, brush, etc., but is generally applied by spray.

  The coated paint is dried at room temperature for 18 to 48 hours, or forcedly dried at a temperature of about 80 ° C. for 30 minutes or more, whereby the solvent is volatilized and a coating film is formed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited at all by these Examples. In the following description, “parts” and “%” represent “parts by mass” and “mass%” unless otherwise specified.

Example 1
400 parts by mass of ethyl silicate solution A (produced by Colcoat, ethyl silicate 40, solid content 25%) using xylene as a solvent, 500 parts by mass of zinc dust A (manufactured by Honjo Chemical Co., Ltd., average particle size 5 μm), corrosive ion fixing agent 40 parts by mass (manufactured by Toho Pigment Co., Ltd., nitrous acid type hydrocalumite) was stirred in a container, 20 parts by mass of xylene was further added, and the mixture was stirred until uniform to prepare a paint.

Next, the above-mentioned paint was applied to a sandblasted steel plate of 3.0 × 70 × 150 (mm) that had been dried by spraying with salt water by spraying so that the salt content after drying was 0.2 g / m ^2, and 48 hours had elapsed at room temperature. Air spray coating was performed so that the subsequent dry film thickness was 70 μm.
Using the produced test piece, performance evaluation was performed as follows, and the results are shown in Table 2.

Examples 2 to 6 and Comparative Examples 1 to 2
As in Example 1, the paints of Examples 2 to 6 and Comparative Examples 1 to 2 were prepared with the formulations shown in Table 1, and test pieces for evaluation were prepared in the same manner as in Example 1. .

Furthermore, performance evaluation was performed as follows, and Table 2 shows the results.
<Performance evaluation>
The corrosion resistance and adhesion of the coating film were evaluated as follows.

Salt water spray test Using the test piece prepared as described above, the appearance of the cross-cut coating film after spraying with salt water for 3500 hours in accordance with JIS K 5400, 9.1 salt water resistance test method is as follows. Visual judgment was made on the basis of

(Evaluation)
◎: No abnormality on the coating surface ○: Some red rust is generated in the crosscut part △: Red rust with a diameter of 1 mm or more and less than 2 mm is generated around the crosscut part ×: A diameter of 2 mm or more is generated around the crosscut part Red rust occurs

Salt water immersion test Using the test piece prepared as described above, in accordance with JIS K 5400, 8.23 salt water resistance test method, the appearance of the coating film after immersion in salt water at room temperature for 5000 hours is as follows. Visual judgment was made.

(Evaluation)
◎: There is no abnormality on the coating film surface. ○: About 1 to 2 points of red rust is generated on the coating film surface. △: About 5% of red rust is generated on the coating film surface. More than 20% red rust occurs

Natural potential After the specimen prepared as described above was immersed in 3% saline for 18000 hours, it was a fully automatic polarization measuring device HZ-3000 manufactured by Hokuto Denko Co., Ltd., and the reference electrode was Ag / AgCl. The potential was measured and judged according to the following criteria.

(Evaluation)
◎; -900 mV or less ○; -899 to -750 mV
Δ: −749 to −650 mV
×: −649 mV or more

<Performance evaluation>
The corrosion resistance and adhesion of the coating film were evaluated as follows.

Adhesion test Using the test piece prepared as described above, in accordance with JIS K 5600 adhesion test method, 500 hours of 100 mm 2 mm grids were prepared using a cutter knife after 500 hours of immersion in deionized water. (Registered trademark) After the tape peeling test, visual judgment was made according to the following criteria.

(Evaluation)
◎: There is no abnormality on the coating surface. ○: There is a slight peeling of the coating along the straight line. Δ: The remaining coating is 95/100 or more. X: The remaining coating is 94/100 or less.

1) Ethyl silicate: “Ethyl silicate 40” manufactured by Colcoat Co. (solid content: 25%)
2) Epoxy resin solution B: “ Epicoat 1001 ” (solid content: 70%) manufactured by Japan Epoxy Resin Co., Ltd.
3) Lithium silicate aqueous solution C: “Lithium silicate aqueous solution” manufactured by Nippon Chemical Industry Co., Ltd. (solid content: 40%)
4) Urethane resin aqueous dispersion D: “Adekabon titer 290H” manufactured by Asahi Denka Co., Ltd. (solid content: 40%)
5) Polysilicon aqueous solution E: “KBM403” manufactured by Shin-Etsu Chemical Co., Ltd. (solid content 80%)
6) Zinc Powder A: “Zinc Powder F-1000” (average particle size 5 μm) manufactured by Honjo Chemical Co., Ltd.
7) Zinc Powder B: "Zinc Powder # 3-13L" (average particle size 4 μm) manufactured by Sakai Chemical Co., Ltd.
8) Corrosion ion fixing agent A: “Solucut C” manufactured by Toho Pigment Co., Ltd .: Nitrite type hydrocalumite 9) Corrosion ion fixing agent B: “DHT-4A” manufactured by Kyowa Chemical Industry Co., Ltd .: Hydrotalcite 10) Silane Coupling agent A: “KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.
11) Silane coupling agent B: “BYK354” manufactured by BYK Chemie
12) Polyamidoamine solution A: “Tomide TXK-659A” manufactured by Fuji Kasei Co., Ltd. (solid content 60%, amine value 120)

  As is clear from the results in Table 2, the paint containing a zinc ion-containing paint and a corrosive ion immobilizing agent is extremely different from the comparative paint in both the salt-containing sandblasted steel sheet and the steel sheet from which rust has been removed with a power tool. Good anticorrosion. On the other hand, Comparative Example 1 in which a silane coupling agent is blended without blending a corrosive ion fixing agent is insufficient in corrosion resistance. Further, Comparative Example 2 and Comparative Example 3 in which no corrosive ion fixing agent and silane coupling agent were blended had insufficient corrosion resistance and poor adhesion.

  As described above, according to the present invention, it is possible to provide a zinc dust-containing paint that exhibits high anticorrosion and adhesion in both a salt-containing sandblasted steel plate and a steel plate from which rust has been removed with a power tool. .

Claims (6)

  (A) Binder resin 100 parts by mass (solid content weight), (B) Zinc powder 200-800 parts by mass, (C) Corrosive ion fixing agent 1-95 parts by mass, (D) Solvent 200-1000 parts by mass Highly anticorrosive zinc powder-containing coating composition containing   The highly anticorrosive zinc dust-containing coating composition according to claim 1, wherein the component (A) is an inorganic resin or an organic resin. (A) Inorganic resin of component is alkyl silicate partial hydrolyzate or general formula R ₂ O.nSiO ₂ (wherein R represents an alkali metal atom, and n represents a positive number of 1.0 to 4.5.) The highly anticorrosive zinc dust-containing coating composition according to claim 2, which is an aqueous dispersion of a water-soluble silicate and colloidal silica represented by the formula:   The highly anticorrosive zinc dust-containing coating composition according to claim 2, wherein the organic resin (A) is selected from an epoxy resin, an acrylic resin, and a urethane resin.   The highly anticorrosive zinc dust-containing coating composition according to any one of claims 1 to 4, wherein the component (C) is hydrocalumite or hydrotalcite.   The highly anticorrosive zinc dust-containing coating composition according to claim 1, further comprising (E) a coupling agent.