JP5256442B2 - Anticorrosion method - Google Patents

Description

  The present invention relates to a metal surface anticorrosion method capable of suppressing the generation of rust and rusted juice and shortening the coating process.

  Steel structures installed outdoors are subjected to an undercoat to prevent the occurrence of rust and then an overcoat. In general, since the top coat is applied a plurality of times, undercoating the steel structure requires a base coat and two or more top coats, and a total of three coating steps must be performed. Furthermore, in order to further improve rust prevention, an intermediate coating may be applied between the undercoating and the top coating (for example, Patent Document 1). In such a case, it is necessary to repeat the coating process.

Thus, the conventional painting of outdoor steel structures that require anti-rust properties requires time and labor to finish the painting, and therefore, the painting process is required to be shortened.
JP-A-11-616

  The present invention has been made in order to solve the above-described conventional problems, and an object of the present invention is to provide a method for preventing corrosion of a metal surface that can suppress the generation of rust and rust juice and can shorten the coating process. There is.

  The metal surface anticorrosion method of the present invention comprises a step of coating a metal surface with a two-component anticorrosive coating comprising a main agent and a curing agent, and a step of drying the coated film, wherein the main agent comprises a polyol resin and Acetylacetone is included, the curing agent includes a polyisocyanate compound, and the content of the acetylacetone is 0.25 to 2% by weight based on the total amount of the coating material in which the main agent and the curing agent are mixed.

  In a preferred embodiment, the curing agent further contains a silane coupling agent, and the content of the silane coupling agent is 0.5 to 1.5% by weight based on the total amount of the paint in which the main agent and the curing agent are mixed. %.

  In preferable embodiment, the said coating process and the said drying process are implemented in multiple times.

  In a preferred embodiment, a corrosion product is generated on the metal surface.

  According to the present invention, by using a two-component anticorrosive paint comprising a main component and a curing agent containing a specific amount of a specific component, the generation of rust and rust juice is suppressed, and an anticorrosion method that eliminates the need for an undercoat step, that is, It is possible to provide a metal surface anticorrosion method that is excellent in the durability of a coating film and can significantly shorten the coating process.

A. Coating process In the metal surface anticorrosion method of the present invention, first, a two-component anticorrosive paint comprising a main agent and a curing agent is applied to the metal surface.

  The main agent contains a polyol resin and acetylacetone.

  The content of the polyol resin contained in the main agent is preferably 10 to 90% by weight, more preferably 20 to 80% by weight, particularly preferably based on the total amount of the paint in which the main agent and the curing agent are mixed. 30 to 70% by weight.

  The content of acetylacetone contained in the main agent is 0.25 to 2% by weight, preferably 0.5 to 2% by weight, more preferably, based on the total amount of the paint in which the main agent and the curing agent are mixed. 1.5 to 2% by weight. If the acetylacetone content is in such a range, the generation of rust and rust juice can be significantly suppressed. When the content of acetylacetone is less than 0.25% by weight, the effect of containing acetylacetone cannot be sufficiently obtained, and rust and rusted juice may not be effectively suppressed. When the content of acetylacetone exceeds 2% by weight, the water resistance of the resulting coating film is lowered, and also in this case, rust and rust juice may not be effectively suppressed.

  The polyol resin is preferably an acrylic polyol resin, a polyester polyol resin, a polyurethane polyol resin, a fluorine polyol resin, an epoxy polyol resin, a polyether polyol resin, or the like, and particularly preferably an acrylic polyol resin. If it is acrylic polyol resin, the coating film which is excellent in various physical properties, such as an external appearance, a weather resistance, and chemical resistance, can be obtained.

  The number average molecular weight by GPC of the polyol resin is preferably 3000 or more, more preferably 4000 to 20000, and particularly preferably 6000 to 16000. When the molecular weight of the polyol resin is in such a range, a coating film having excellent coating film properties after curing can be obtained.

  The hydroxyl value of the polyol resin is preferably 10 to 100 mgKOH / g, more preferably 20 to 80 mgKOH / g, and particularly preferably 25 to 50 mgKOH / g.

  The polyol resin can be obtained by polymerizing a hydroxyl group-containing monomer and, if necessary, other monomers by a conventional method. For example, it can be obtained by the polymerization method described in JP-A-7-48518.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3- Hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, di-2-hydroxyethyl fumarate, mono-2-hydroxyethyl-monobutyl fumarate, Hydroxyalkyl esters of α, β-ethylenically unsaturated carboxylic acids such as polyethylene glycol- or polypropylene-glycol mono (meth) acrylates and adducts thereof with ε-caprolactone; (meth) acrylic acid, croton Various unsaturated mono- or dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid or citraconic acid; α, β-ethylenically unsaturated carboxylic acids such as monoesters of the above dicarboxylic acids with monohydric alcohols; Examples include adducts of the above α, β-ethylenically unsaturated carboxylic acids and ε-caprolactone, and hydroxyl group-containing monomers disclosed in JP-A-7-48518.

  Examples of the other monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, and i-butyl (meth) acrylate. , Tert-butyl (meth) acrylate, sec-butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 4-tert-butylcyclohexyl ( Alkyl (meth) acrylates such as meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate; methoxyethyl Alkoxyalkyl (meth) acrylates such as meth) acrylate; diesters of dicarboxylic acids such as maleic acid, fumaric acid or itaconic acid and monohydric alcohols; vinyl esters such as vinyl acetate and vinyl benzoate; The other monomer disclosed by 7-48518 gazette is mentioned.

  A commercial product may be used as the polyol resin. Specific examples of commercially available polyol resin products include trade names “ACRYDIC A-837”, “ACRYDIC A-871”, “ACRYDIC A-1370” manufactured by DIC Corporation, and trade names “Hariacron D” manufactured by Harima Kasei Co., Ltd. -1703 "," Hariacron N-2043-60MEX "and the like.

  The curing agent includes a polyisocyanate compound.

  The content of the polyisocyanate compound contained in the curing agent is preferably 2 to 10% by weight, more preferably 4 to 8% by weight, based on the total amount of the coating material in which the main agent and the curing agent are mixed.

  Any appropriate polyisocyanate compound may be employed as long as it is compatible with the polyol resin used as the main agent. Preferably, it is a polyisocyanate compound which is generally used for paint applications. Specific examples of the polyisocyanate compound include hexamethylene diisocyanate isocyanurate, hexamethylene diisocyanate biuret, and the like.

  The number average molecular weight by GPC of the polyisocyanate compound is preferably 100 to 2500, more preferably 200 to 2000, and particularly preferably 300 to 1500.

  Commercial products may be used as the isocyanate compound. Specific examples of commercially available isocyanate compounds include trade names “Durato TSA100” and “Durato TPA10” manufactured by Asahi Kasei Corporation, “Burnock DN-990” and “Burnock DN-992” manufactured by DIC Corporation. It is done.

  The curing agent preferably further contains a silane coupling agent. The silane coupling agent preferably contains an epoxy group. Specific examples of the silane coupling agent containing an epoxy group include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane and the like can be mentioned.

  The content of the silane coupling agent is preferably 0.5 to 1.5% by weight, more preferably 0.7 to 1.3% by weight, based on the total amount of the paint in which the main agent and the curing agent are mixed. And particularly preferably 0.8 to 1.2% by weight. If content of a silane coupling agent is such a range, the coating film which is excellent in the adhesiveness with respect to a coating surface can be obtained. When content of a silane coupling agent is less than 0.5 weight%, there exists a possibility that the effect of containing a silane coupling agent may not fully be acquired. When the content of the silane coupling agent is more than 1.5% by weight, the coating film may be dulled or whitened (brushed).

  The main agent or curing agent may further contain any appropriate solvent, pigment, additive and the like as necessary.

  The solvent is preferably a solvent containing 50% by weight or more of an aliphatic hydrocarbon solvent based on the total amount of the solvent, and more preferably 50% by weight or more of the aliphatic hydrocarbon solvent and 20% by weight based on the total amount of the solvent. It is a solvent (commonly called mineral spirit) containing -40% by weight of an aromatic hydrocarbon solvent. A commercial product may be used as the solvent. Specific examples of the solvent containing 50% by weight or more of the aliphatic hydrocarbon solvent with respect to the total amount of the solvent include the trade name “Swazol 310” manufactured by Maruzen Petroleum Co., Ltd. and the product name “Exxon naphtha No. manufactured by Exxon. .5 "and the like. Specific examples of the solvent containing 50% by weight or more of the aliphatic hydrocarbon solvent and 20 to 40% by weight of the aromatic hydrocarbon solvent with respect to the total amount of the solvent include trade name “LAWS” manufactured by Shell, Nippon Oil The product name “Akirashi Solvent” manufactured by Co., Ltd. can be mentioned.

  Examples of the pigment include coloring pigments such as titanium oxide, yellow iron oxide, red iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, azo red, quinacridone red, and benzimidazolone yellow; calcium carbonate, barium sulfate, kaolin, clay And extender pigments such as talc.

  Examples of the additive include an antifoaming agent, an anti-sagging agent, a dispersing agent, a viscosity adjusting agent, a curing catalyst, a surface adjusting agent, a plasticizer, a film forming aid, an ultraviolet absorber, and an antioxidant.

  The two-component anticorrosive paint can be used in a method of coating the mixture on the metal surface after mixing the main agent and the curing agent before painting. Any appropriate mixing method (such as a disper) can be adopted as the mixing method.

  The mixing ratio of the main agent and the curing agent (OH group / NCO group ratio) is preferably OH group / NCO group = 1 / 0.5 to 1 / 1.5, more preferably OH group / NCO group = 1. /0.7 to 1 / 1.3, particularly preferably OH group / NCO group = 1 / 1.0 to 1 / 1.2.

  The metal surface is preferably a surface of iron, galvanized steel plate, aluminum, aluminum alloy, tin steel plate, tin steel plate, bonde steel plate, galvalume steel plate, black leather plate, zinc aluminum steel plate, zinc alloy and stainless steel, especially An iron surface is preferred. If it is such a metal surface, generation | occurrence | production of rust and rust juice may be more effectively suppressed by the said 2 liquid type anticorrosion coating material.

  The metal surface may be a metal surface on which corrosion products (such as rust) are generated. That is, the anticorrosion method of the present invention does not require any special metal surface preparation (for example, steel road bridge coating) even on metal surfaces on which corrosion products that are more likely to generate rust juice are generated. A coating film can be formed (by treatment of 4 types of keren or less determined in the handbook), and generation of rust and rusted juice can be suppressed. This is because according to the anticorrosion method of the present invention, not only the effect of suppressing the generation of new rust but also the excellent effect of suppressing the rust juice caused by the remaining rust can be obtained. Therefore, the anticorrosion method of the present invention is very useful in workability, economical efficiency, maintenance of a good appearance, etc. even during repainting.

  Examples of the coating method of the two-component anticorrosive paint include brush coating, air spray, airless spray, roller coating, and the like.

The application amount of the two-component anticorrosion paint can be set to any appropriate application amount depending on the application. Generally, it is preferable that it is 100-150 g / m < ² >.

B. Drying Process The anticorrosion method for a metal surface according to the present invention includes a process of drying the coated film after coating the two-part anticorrosive paint on the metal surface.

  Arbitrary appropriate drying methods may be employ | adopted for the drying method in the said drying process. Typically, it is natural drying. The drying time is preferably 3 hours or longer, more preferably 24 hours or longer.

  The coating process and the drying process may be performed a plurality of times. If the coating process and the drying process are carried out a plurality of times, a coating film having an excellent appearance can be obtained. The painting process and the drying process can be performed any appropriate number of times depending on the application. Typically twice. In addition, when the coating process and the drying process are performed a plurality of times, the second and subsequent coating processes are preferably performed after the drying process.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on weight.

[Reference Example 1] Production of Rust Plate A polished steel plate SPCC-SB was exposed outdoors for three months in the summer (June to August) to obtain a steel plate (rust plate) with rust on the surface.

[Reference Example 2] Preparation of main agents A to I Acrylic polyol resin (trade name “ACRYDIC A-871” manufactured by DIC Corporation (molecular weight 8,000, hydroxyl value 29 ± 3%), acetylacetone, titanium pigment (product manufactured by Ishihara Sangyo Co., Ltd.) Name "titanium CR-95"), antifoaming agent (trade name "BYK063" manufactured by BYK), sag stopper (trade name "Dispalon 6810-20X" manufactured by Enomoto Kasei Co., Ltd.), dispersing agent (trade name "BYK" BYK162 ") and mineral spirit as a solvent were mixed in the blending amounts shown in Table 1 below to obtain main agents A to I.

Reference Example 3 Preparation of Curing Agent J Isocyanate resin (trade name “Durato TSA100” (molecular weight 700 ± 300), NCO content 21%, manufactured by Asahi Kasei Co., Ltd.) 6.2 parts, and mineral spirit 3.8 parts as a solvent. Mixing was performed to obtain a curing agent J.

Reference Example 4 Preparation of Curing Agent K Isocyanate resin (trade name “Durato TSA100” manufactured by Asahi Kasei Co., Ltd. 6.2 parts, epoxy silane coupling agent (trade name “KBE-403” manufactured by Shin-Etsu Chemical Co., Ltd.) 1.0 part and As a solvent, 2.8 parts of mineral spirit was mixed to obtain a curing agent K.

[Example 1]
After the rust plate obtained in Reference Example 1 was wiped, the main agent A and the curing agent J were added to the rust plate in a weight ratio of main agent A: curing agent J = 9: 1 (that is, OH group / NCO group = 1). The two-part anticorrosive paint obtained by mixing in 1) was applied by brush coating to obtain a test piece. The number of coatings was 2 times, the coating amount per time was 130 g / m ² , and the repeated drying time was 3 hours.

[Example 2]
A test piece was obtained in the same manner as in Example 1 except that the main agent B was used in place of the main agent A.

[Example 3]
A test piece was obtained in the same manner as in Example 1 except that the main agent C was used in place of the main agent A.

[Example 4]
A test piece was obtained in the same manner as in Example 1 except that the main agent D was used instead of the main agent A.

[Example 5]
A test piece was obtained in the same manner as in Example 1 except that the main agent E was used in place of the main agent A.

[Example 6]
A test piece was obtained in the same manner as in Example 1 except that the main agent F was used instead of the main agent A.

[Comparative Example 1]
A test piece was obtained in the same manner as in Example 1 except that the main agent G was used instead of the main agent A.

[Comparative Example 2]
A test piece was obtained in the same manner as in Example 1 except that the main agent H was used instead of the main agent A.

[Comparative Example 3]
A test piece was obtained in the same manner as in Example 1 except that the main agent I was used in place of the main agent A.

[Example 7]
A test piece was obtained in the same manner as in Example 1 except that the curing agent K was used in place of the curing agent J.

[Example 8]
A test piece was obtained in the same manner as in Example 1 except that the main agent B was used instead of the main agent A, and the hardener K was used instead of the hardener J.

[Example 9]
A test piece was obtained in the same manner as in Example 1 except that the main agent C was used instead of the main agent A, and the hardener K was used instead of the hardener J.

[Example 10]
A test piece was obtained in the same manner as in Example 1 except that the main agent D was used instead of the main agent A, and the curing agent K was used instead of the curing agent J.

[Example 11]
A test piece was obtained in the same manner as in Example 1 except that the main agent E was used instead of the main agent A, and the hardener K was used instead of the hardener J.

[Example 12]
A test piece was obtained in the same manner as in Example 1 except that the main agent F was used instead of the main agent A, and the curing agent K was used instead of the curing agent J.

[Comparative Example 4]
A test piece was obtained in the same manner as in Example 1 except that the main agent G was used instead of the main agent A, and the curing agent K was used instead of the curing agent J.

[Comparative Example 5]
A test piece was obtained in the same manner as in Example 1 except that the main agent H was used instead of the main agent A, and the hardener K was used instead of the hardener J.

[Comparative Example 6]
A test piece was obtained in the same manner as in Example 1 except that the main agent I was used instead of the main agent A, and the hardener K was used instead of the hardener J.

[Comparative Example 7]
After rusting the rust plate obtained in Reference Example 1, a weak solvent 1-pack epoxy resin rust preventive paint (trade name “Hypon Fine Decro” manufactured by Nippon Paint Co., Ltd.) was applied at 130 g / m ² , Thereafter, it was dried for 16 hours to form an undercoat layer. Furthermore, fine urethane 100 (manufactured by Nippon Paint Co., Ltd.) was applied as an overcoat layer to obtain a coating film comprising an undercoat layer and an overcoat layer. The top coat was applied twice, the coating amount per application was 130 g / m ² , and the coating and drying time was 3 hours.

<Evaluation>
The test pieces obtained in Examples 1 to 12 and Comparative Examples 1 to 7 were dried at 23 ° C. × 50% RH for 7 days, and then evaluated by the following methods. The results are shown in Table 2 and Table 3. In addition, the addition amount of acetylacetone and the addition amount of the silane coupling agent in Table 2 and Table 3 are the content ratio (%) with respect to the total amount of the paint in which the main agent and the curing agent are mixed.
(1) Rust juice evaluation A test was conducted in accordance with the test method of JIS K5674 6.11.2, and the rust juice was evaluated visually. FIG. 1 shows the determination criteria.
(2) Fluff width and rust width A test was conducted according to the test method of JIS K5674 6.11.2, and the blister width and rust width were measured. However, the combined cycle test was 120 cycles, and the coatings within 2 mm on each side of the scratches on the coatings were also evaluated.

  As apparent from Tables 2 and 3, according to the metal surface anticorrosion method of the present invention, rusting is caused by using a main agent containing a specific amount of acetylacetone and a polyol resin and a curing agent containing polyisocyanate. And rust juice can be significantly suppressed.

  Further, for example, as apparent from the fact that the blister width of Example 7 is smaller than that of Example 1, very high adhesion to the metal surface by adding a specific amount of silane coupling agent to the curing agent. A coating film exhibiting properties can be obtained.

  Furthermore, as is clear from Examples 1 to 12, according to the corrosion prevention method for metal surfaces of the present invention, rust and rust juice are suppressed more than the conventional corrosion prevention method (Comparative Example 7) without applying the undercoat. A coating film excellent in effect can be obtained.

  And according to the anticorrosion method of this invention, the above outstanding effects can be acquired with respect to the metal surface by which only the simple base adjustment of the extent which wipes a rusty board was carried out.

  The metal surface anticorrosion method of the present invention can be suitably used for building exteriors, bridges, ships, vehicles, industrial machinery, construction machinery, and the like.

It is a figure which shows the criterion of rusted juice evaluation.

Claims (4)

Coating a metal surface with a two-component anticorrosion paint consisting of a main agent and a curing agent;
Including a step of drying the coated film after painting,
The main agent contains a polyol resin and acetylacetone,
The curing agent comprises a polyisocyanate compound;
The content of the acetylacetone is 0.25 to 2% by weight with respect to the total amount of the paint mixed with the main agent and the curing agent.
Anticorrosion method for metal surfaces. The curing agent further comprises a silane coupling agent;
The method for preventing corrosion of a metal surface according to claim 1, wherein the content of the silane coupling agent is 0.5 to 1.5% by weight with respect to the total amount of the paint mixed with the main agent and the curing agent.   The metal surface anticorrosion method according to claim 1 or 2, wherein the coating step and the drying step are performed a plurality of times. The anticorrosion method according to any one of claims 1 to 3, wherein a corrosion product is generated on the metal surface.