JPH02266929A - Heavy anticorrosion coated steel material - Google Patents

Abstract

PURPOSE:To obtain excellent water-resistance tight adhesiveness and cathode release resistance by forming the primer used in the primer layer on the surface of a steel material from a metal painting composition prepared by mixing a specific compound and an inorg. powder. CONSTITUTION:The surface of a steel material is cleaned by blast treatment and subjected to chemical forming treatment of a chromic acid system and, subsequently, a primer layer and a coating layer composed of an org. resin are successively laminated to said treated surface. The primer used at this time is composed of a metal painting composition prepared by mixing a compound having two or more hydroxyl groups in its molecule with a compound having two or more isocyanate groups in its molecule and an inorg. powder. The compound having two or more hydroxyl groups in its molecule is obtained by reacting a compound having two or more epoxy groups in its molecule with a compound having one secondary amino group or phenolic hydroxyl group in its molecule. The inorg. powder is phosphate of a metal of the Group II and/or III of the Periodic Table and contained in an amount of 30-200 pts.wt. per 100 pts.wt. of the total amount of epoxy modified polyol and a compound having an isocyanate group.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention has been devised to reliably prevent corrosion and the accompanying destruction of piping, containers, structures, etc. even when used for long periods in underground ports, rivers, etc. This article relates to a new heavy-duty anti-corrosion coated steel material. (Prior art) Steel, the most common metal material, has the disadvantage of being easily corroded, so various anti-corrosion treatments are usually applied to the steel before or during use. Corrosion-proofing treatments for steel include:
For example, a method using anticorrosive coating or a method using a plastic coating material such as polyethylene is used. The method of using anti-corrosion coating is widely used because it can be applied relatively easily regardless of the form of the steel material. In particular, polyurethane heavy-duty anti-corrosion paints not only have good low-temperature curing properties and are excellent in winter paintability, they are also flexible and have excellent impact resistance, and are also long-term durable, so they can be maintained for a long time. Since it can be expected to have a free anti-corrosion effect, its demand is increasing significantly. Although polyurethane heavy-duty anticorrosive paints have the excellent characteristics described above, if a primer is not used, the water-resistant adhesion and cathode resistance may be slightly lower. [Problems to be Solved by the Invention] However, epoxy-based or polyurethane-based primers have conventionally been used to improve water-resistant adhesion and anode resistance. Certain epoxy primers have excellent water-resistant adhesion and shade-resistant IN female properties.For example, JP-A-57-159866, JP-A-58-9177.
No. 8, JP-A-58-217573, JP-A-Sho 5
9-71374, JP-A-59-222275, JP-A-59-232160, JP-A-60-2
No. 58277 and Japanese Unexamined Patent Publication No. 60-258278 describe adhesives for laminating polyolefin and metal which have excellent cathode @ layer resistance and water-resistant adhesion. However, in heavy polyurethane anti-corrosion coating, careful coating management is required to ensure the adhesion between the epoxy primer, which is a different material, and the polyurethane topcoat. On the other hand, polyurethane primers have good adhesion to polyurethane top coats, but have a problem in that they have somewhat poor cathodic peeling resistance. An object of the present invention is to eliminate the drawbacks of conventional heavy corrosion-resistant coated steel materials and to provide a heavy-duty corrosion-resistant coated steel material that has excellent water-resistant adhesion and cathodic peeling resistance. [Means for Solving the Problems] In order to achieve the above object, in the heavy-duty anti-corrosion coated preparation material of the present invention, the entire or part of the surface of the steel material is pretreated, and then a primer layer is applied. In a heavy anti-corrosion coated steel material in which coating layers made of organic resin are sequentially laminated, the primer is a mixture of a compound having two or more hydroxyl groups in the molecule, a compound having two or more isocyanate groups in the molecule, and an inorganic powder. A stone metal coating composition used for coating metals, wherein the compound having two or more hydroxyl groups in the molecule is a compound having two or more epoxy groups in the molecule and one secondary amino group in the molecule. or a compound obtained by reaction with a compound having a phenolic hydroxyl group, wherein the inorganic powder is a phosphate of a metal of Group N and/or Group II of the Periodic Table, and the epoxy-modified polyol and the The amount is 30 to 200 parts by weight based on 100 parts by weight of the total amount of the compound having two or more isocyanate groups in the molecule. As a pretreatment means, there is a means of cleaning the surface of the steel material to be coated by blasting or the like, and then subjecting it to chemical conversion treatment of chromic acid groups. Further, as the steel material, for example, a steel pipe, a steel pipe sheet pile, a steel sheet pile, an H-shaped steel, or a steel plate is used. Next, the heavy-duty anti-corrosion coating material used in the present invention will be explained. In the epoxy-modified polyol used in the present invention, the compounds having two or more epoxy groups include bisphenol A and bisphenol F. It is obtained by reacting a phenolic hydroxyl group such as novolak with epichlorohydrin in the presence of an alkali catalyst, and has a reactive epoxy group. Specifically, Ebiku) 812. Ebiku)
815. Epicoat 828゜Ebiku) 834. Epicu) 152 (all made of Yuka shell epoxy ■)
Adekal Resin BP-4100, Adekal Resin EP-4
200, Adeka Resin BP-4300 (all manufactured by Asahi Denka Kogyo ■) EPOMIK R-144, EPOMIK
R-130, EPOMIK R-140 (both manufactured by Mikata Petrochemical Epoxy ■), etc., and reacting these epoxy compounds with a compound having one secondary amino group or phenolic hydroxyl group in the molecule. This converts the epoxy group into an alcoholic hydroxyl group. Compounds having one secondary amino group in the molecule include compounds such as dimethylamine, diethylamine, and dibroviralamine. Alkanolamines other than those mentioned above, such as jetanolamine and diisopropanolamine, cannot be used because they contain hydroxyl groups, and if -class amines are used, gelation occurs due to polymerization of the epoxy compound, and Even when a compound having two or more secondary amines is used, gelation of the epoxy compound occurs, and neither can be used. The reaction between a compound having one secondary amine in the molecule and an epoxy compound is usually achieved in the absence of a catalyst, but the reaction may be carried out in the presence of a catalyst. Compounds having one phenolic hydroxyl group include phenol, ethylphenol, nonylphenol, and the like. The reaction between phenolic hydroxyl groups and epoxy groups is accomplished in the presence of an alkali catalyst and is converted to alcoholic hydroxyl groups.Normally, phenolic hydroxyl groups are more reactive with epoxy compounds than alcoholic hydroxyl groups. However, if a compound with an alcoholic hydroxyl group is used, the epoxy compound will be polymerized, so it cannot be used. For example, methyl alcohol,
When ethyl alcohol or the like is used, a polymer compound with three-dimensional crosslinking is created that is insoluble in solvents. The phenolic hydroxyl group and the epoxy group are usually reacted in an equivalent ratio of l=1. If there are too many phenolic hydroxyl groups, the resulting polyurethane resin coating film will have low heat resistance because the phenolic hydroxyl groups will remain. This is because the urethane bond formed by the reaction between the phenolic hydroxyl group and the isocyanate is likely to undergo thermal dissociation. On the other hand, when there are many epoxy groups, a polymerization reaction occurs and the material becomes insoluble in solvents. Therefore, it is preferable that the phenolic hydroxyl group and the epoxy group react in a ratio of 1+1. The alkali used as a reaction catalyst between a phenolic hydroxyl group and an epoxy group is preferably neutralized by a commonly known method. The hydroxyl groups of the epoxy-modified polyol thus obtained form urethane bonds through reaction with isocyanate groups, resulting in excellent heat resistance. Compounds having two or more isocyanate groups in the molecule (hereinafter referred to as polyisocyanate compounds) used in the present invention include tolylene diisocyanate (TDI),
diphenylmethane diisocyanate (MDI), polyphenylene polymethylene polyisocyanate (cr-MD
I) + hexamethylene diisocyanate) (HMD
l, isophorone diisocyanate) (IPDI),
Isocyanate-terminated urethane obtained by reacting a polyisocyanate such as xylylene diisocyanate (XDI), hydrogenated MDI, and a compound having two or more hydroxyl groups in the molecule with the polyisocyanate in an excess incyanate state. Prepolymers, etc. Among these polyisocyanates, MDI. Particularly preferred are cr-MDI and prepolymers thereof. The reaction between the epoxy-modified polyol and the polyisocyanate compound is preferably carried out by mixing them in such a proportion that the ratio of NCOloH is 0.7 to 2.0. If the N G Olo H ratio is less than O97, the hydroxyl groups will be too excessive, resulting in poor water resistance and cathodic peeling resistance when used as a primer. On the other hand, if the N G Olo H ratio is greater than 2.0, when applied thickly, it may react with moisture in the air and cause blistering, resulting in low adhesion strength. Phosphates of metals in Group N and/or Group II of the periodic table include phosphates of magnesium, calcium, zinc, aluminum, scandium, gallium, etc. Phosphates of metals from the fifth period onwards, such as strontium, cadmium, mercury, etc. Heavy metals are undesirable to use due to their toxicity, and salts of other inorganic acids, such as hydrochloric, sulfuric, and nitric acids, as well as organic acids such as carboxylic acids, are ineffective. Phosphates of these metals are The total amount of epoxy-modified polyol and polyisocyanate compound is 1
It should be added in an amount of 30 to 200 parts by weight per 00 parts by weight, and it is preferable to use particles with an average particle size of 0.1 to 20 nm.If the amount added is less than 30 parts by weight,
The cathode peeling resistance is reduced, and the object of the present invention cannot be achieved. If the amount added is more than 200 parts by weight, the strength of the primer coating will decrease and the initial adhesion and water-resistant adhesion will decrease.When adding powder other than phosphate for the purpose of coloring, etc. The total amount of powder added should not exceed 200 parts by weight. The primer used in the present invention may optionally include
Auxiliary agents such as a solvent, an n-material, a catalyst, and an antioxidant can be added. The film thickness of the primer used for the heavy corrosion protection coated steel material of the present invention is:
The dry film thickness is 5~! Although it is preferable to apply the coating to a thickness of 00 nm, there is no particular limitation. Further, as a painting method, methods such as brush, roller, air spray, and airless spray can be applied. The object of the present invention can be achieved by any method of coating. Next, examples of steel materials used in the present invention include steel pipes, steel pipe sheet piles, Il piles, H-shaped steel, and steel plates. Specifically, steel pipes used for underground piping, submarine piping, above-ground piping, steel plates used for fuel storage tanks, chemical plants, etc., H-shaped steel pipes, marine structures, 2 port and river revetment structures, bridges, etc. Examples include steel pipes for piles, steel pipe sheet piles, steel sheet piles, and H-shaped steel used in structures installed outdoors. Further, in order to improve the adhesion between the primer used in the present invention and the steel material, the surface of the steel material may be cleaned by blasting or the like, and then a chromium oxygen chemical conversion treatment may be performed. Here, as a chemical conversion treatment agent for chromic acid group,
An aqueous solution of a composite oxide of hexavalent chromium oxide and trivalent chromium oxide obtained by reducing a part of hexavalent chromium oxide, or a substance such as glycerin or polyvinyl alcohol to promote reduction, or a coating. An aqueous solution containing silica sol can be used to improve adhesion to the layer. Next, in order to obtain the heavy corrosion-resistant coated steel material of the present invention, first, the surface of the steel material is cleaned by blasting or the like, and then coated with the primer, or after applying a chromic acid-based chemical conversion treatment agent, the surface of the steel material is cleaned by blasting, etc. A primer is laminated and a coating layer consisting of an organic coating film is formed. In this case, if a polyurethane resin paint is used as the organic coating, water-resistant adhesion and cathodic peeling resistance will be greatly improved;
A polyester resin paint, a fluororesin paint, a vinyl resin paint, a chlorinated rubber resin paint, an epoxy resin paint, or a phenol resin paint may be used as the top coat.

[For use]

The heavy corrosion-resistant coated steel material according to the present invention has water-resistant adhesion. Since it has a coating layer made of a primer with excellent cathodic peeling resistance, it has excellent anticorrosion performance, especially in severe corrosive environments such as marine structures. In other words, the primer used in the present invention has an epoxy skeleton in its molecule with excellent water-resistant adhesion and cathode peeling resistance, and is modified into an epoxy polyol with excellent low-temperature curing properties, so it can be applied without careful painting control. According to the present invention, the water-resistant adhesion is 0 or more, which can ensure adhesion to the steel surface and the top coat. It is possible to provide a heavy anti-corrosion coated steel material with excellent cathodic peeling resistance and long-term anti-corrosion performance. (Example) Hereinafter, the present invention will be explained in more detail with reference to Examples. In addition, "part" and "%" in Examples and Comparative Examples are based on weight. Production Example 1 370 parts of Epikote 828 (epoxy equivalent 190,
molecular weight 380) and 258 parts of dibutylamine at 130°C.
The mixture was reacted for 3 hours, then cooled to 90° C., and 210 parts of methyl ethyl ketone was gradually added to obtain a solution with a solid content of 75%. The water ea value of this solution is 150 OH/
It was g. This is referred to as epoxy modified polyol 1. Production Example 2 1 part of sodium hydroxide was added to 370 parts of Epicote 828 and 180 parts of phenol, and the reaction was carried out at 130°C for 4 hours. After the temperature reached 90°C, 138 parts of methyl ethyl ketone was added while refluxing. The temperature of the contents was then cooled to 65°C, and then neutralized with acetic acid to adjust the pH.
was set at 7.0. The solid content of this solution is 80%, and the hydroxyl value is 182 KOH
/g. This is referred to as epoxy modified polyol 2. Comparative Production Example 1 370 parts of Epikote 828 and 270 parts of diisopropanolamine were reacted at 130°C for 3 hours to produce 0-90
The mixture was cooled to 70°C and diluted with gradual addition of 213 parts of methyl ethyl ketone. The solid content of this solution is 75%, and the hydroxyl value is 409■
It was OH/g. This is epoxy modified polyol 3
shall be. Examples and Comparative Examples The outer surface of a steel pipe with a wall thickness of 12 M, an outer diameter of 1600 M, and a length of 12 m, and the outer surface of a steel pipe sheet pile with a wall thickness of 15 m, an outer diameter of 16 m, and a length of 16 m, and FSPI! [After grid blasting (Ci-70) is applied to one side of the steel sheet pile of the mold to clean it, the main agent and hardening agent having the composition shown in Table 1 are thoroughly mixed and then spray painted. A film having a thickness of 30 μm after curing was formed. A polyurethane paint was coated on this film layer to form a coating layer having a film thickness of 2.5N after curing. A perspective view of the heavy corrosion-proof coated steel pipe thus obtained is shown in FIG. 1, a perspective view of the heavy-duty corrosion-proof coated steel pipe sheet pile is shown in FIG. 2, and a perspective view of the heavy corrosion-proof coated steel sheet pile is shown in FIG. In the figure, 1 is a steel pipe, 2 is a steel pipe sheet pile, 3 is a steel sheet pile, and 4
5 indicates a coating layer made of epoxy-modified polyol, and 5 indicates a coating layer made of polyurethane resin. These heavy-duty corrosion-resistant coated steel materials were cured for 7 days after coating to allow the coating layer to sufficiently harden, and then a test piece was cut out.
Various performance tests were conducted. The experimental results are shown in Table 1. [Effects of the Invention] As can be seen from the performance test results of heavy-duty corrosion-resistant coated steel materials shown in the above examples, the heavy-duty corrosion-resistant coated steel pipe according to the present invention has shade resistance of I! j＠Releasability has been significantly improved, and good adhesion can be maintained for a long period of time even in saline water. That is, it exhibits remarkable long-term durability in environments such as seawater and freshwater.

[Brief explanation of drawings]

Figure 1 shows Examples 1.2 and 3.4 of the present invention and Comparative Example 1.
□ A perspective view of the heavily anti-corrosion coated steel pipe of 2 and 3.4, Fig. 2 is a perspective view of the heavy anti-corrosion coated steel pipe sheet pile of Example 5 of the present invention, and Fig. 3 is a perspective view of the heavy anti-corrosion coated steel pipe of Example 6.7 of the present invention. It is a perspective view of a sheet pile. 1: steel pipe, 2: steel pipe sheet pile, 3: steel sheet pile, 4: epoxy polyol primer 5: coating layer made of polyurethane resin.

Claims (7)

[Claims] (1) In heavy-duty anti-corrosion coated steel where the entire or part of the surface of the steel is pre-treated and then a primer layer and a coating layer made of an organic resin are sequentially laminated, two primers are present in the molecule. A metal coating composition in which a compound having the above hydroxyl groups, a compound having two or more isocyanate groups in the molecule, and an inorganic powder are mixed and coated on metal, and the compound having two or more hydroxyl groups in the molecule. is a compound obtained by the reaction of a compound having two or more epoxy groups in the molecule with a compound having one secondary amino group or phenolic hydroxyl group in the molecule (hereinafter referred to as epoxy-modified polyol), and the inorganic compound The powder is a phosphate of a metal of Group II and/or Group III of the Periodic Table, and the total amount of the epoxy-modified polyol and the compound having two or more isocyanate groups in the molecule is 100 parts by weight. Heavy duty anti-corrosion coated steel material, characterized in that it contains 30 to 200 parts by weight. (2) The heavy-duty anti-corrosion coated steel material according to claim 1, wherein as a pretreatment, the surface of the steel material to be coated is cleaned by blasting or the like and then subjected to a chromic acid-based chemical conversion treatment. (3) The heavy corrosion-resistant coated steel material according to claim 1, wherein the steel material is a steel pipe. (4) Claim 1 characterized in that the steel material is a steel pipe sheet pile.
The heavy corrosion-resistant coated steel materials listed. (5) The heavy corrosion-resistant coated steel material according to claim 1, wherein the steel material is a steel sheet pile. (6) The heavy-duty anti-corrosion coated steel material according to claim 1, wherein the steel material is an H-beam steel. (7) The heavy corrosion-resistant coated steel material according to claim 1, wherein the steel material is a steel plate.