JP6606592B1 - Paint for rust surface, coating method for rust surface steel using the same, and painted steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating material and a coating method capable of preventing further generation of rust without requiring rust removal even on a rust surface of a steel material. A steel material rust surface paint according to the present invention is a composition containing a resin component and a pigment. When a coating film is formed from the composition, the coating film has a water vapor transmission rate of 1.5 g. / (M2 · 24h) or less. In addition, the method for coating a rusted surface steel material of the present invention includes a coating film step of forming a coating film on a steel material having a rust surface by using a paint containing a resin component and a pigment. The coating film is formed so that the permeation amount is 1.5 g / (m 2 · 24 h) or less, and the coating material of the present invention is used as the coating material, for example. [Selection] Figure 1

Description

  The present invention relates to a paint for steel having rust on the surface, a coating method using the same, and a coated steel.

  In various steel structures in which steel materials are used, rust is generated, so that the steel materials are repaired with a paint to prevent corrosion and prevent the rust from proceeding. In the repair of the steel structure, even if the surface of the steel structure is coated to form a coating film as it is on the surface where rust is generated, corrosion under the coating film proceeds, and in a short period of time The coating film swells and cracks, and the rust is further generated on the coating film forming surface of the steel structure. For this reason, in the field, before performing coating on the steel structure, after removing the rust in advance, repair is performed using a paint suitable for the steel material of the steel structure. .

  As a method for repairing the rust surface in this way, in Patent Document 1, for example, an undercoat paint is applied to the surface of a steel material, and further, an overcoat paint is applied as an outermost coating film covering the surface. How to do is described. The undercoat paint is an epoxy paint, and the top coat is at least one of a phthalic acid paint, a chlorinated rubber paint, and a polyurethane paint.

JP-A-3-278869

  In the rust surface repair method as described above, the undercoat paint is applied after sufficiently removing the rust on the surface of the steel material, and further, the overcoat paint is applied. On the other hand, depending on the shape of the steel structure, it is structurally difficult to remove rust, or due to restrictions on the construction period, it is not possible to spend a sufficient amount of time to remove rust. There are cases where repairs are forced to remain. In such a case, the method disclosed in Patent Document 1 is difficult to apply because it is premised on sufficient removal of rust.

  Therefore, for example, the present invention does not require the removal of rust in the formation of the coating film, even if the coating target is a rust surface of steel, and suppresses the progress of corrosion under the coating film. And the coating material and coating method which can suppress the swelling of the said coating film, a crack, the rusting in the coating surface of the said coating film in the said steel materials, etc. are provided.

In order to achieve the above object, the steel material rust surface paint of the present invention is a composition containing a resin component and a pigment, and when a coating film is formed from the composition, the water vapor transmission rate of the coating film Is 1.5 g / (m ² · 24 h) or less.

The coating method on the rust surface steel material of the present invention includes a coating film step of forming a coating film using a paint containing a resin component and a pigment on a steel material having a rust surface. Is characterized by forming the coating film so as to be 1.5 g / (m ² · 24 h) or less.

The coated steel material of the present invention includes a steel material and a coating film, and has the coating film on the rust surface of the steel material,
The coating film includes a resin component and a pigment, and has a water vapor transmission rate of 1.5 g / (m ² · 24 h) or less.

In the present invention, by setting the water vapor permeation amount of the coating film to 1.5 g / (m ² · 24 h) or less, for example, even if the formation target of the coating film is a rust surface of a steel material, Swelling, cracking, and rusting on the painted surface of the coating film on the steel material can be suppressed for a long period of time. For this reason, for example, even if it is a case where the rust which generate | occur | produced in the said steel materials cannot be removed, this invention is applicable to such a steel material.

FIG. 1 is a graph showing the relationship between the swelling area ratio and the acceleration test time. FIG. 2 is a graph showing the relationship between the slope of the linear approximation line (coating film deterioration rate) and the water vapor transmission rate. FIG. 3 is a graph showing the relationship between the slope of the linear approximation line (coating film deterioration rate) and the water vapor transmission rate.

  As a result of intensive studies, the present inventors have found the present invention for the following reasons. Note that these estimations do not limit the present invention.

When a coating film is formed as an anticorrosion coating on a steel material that does not generate rust, generally, the higher the barrier property of the coating film, the better the long-term adhesion of the coating film, It is known to become smaller. However, in order to increase the barrier property of the coating film, it is necessary to increase the curing density of the coating film to form a dense film, and as a result, the internal stress of the coating film increases, so long-term adhesion On the other hand, head for the direction of decline. That is, the barrier property of the coating film that determines the deterioration rate of the coating film and the long-term adhesion property of the coating film are in a contradictory relationship. For this reason, when anticorrosion coating is applied to a steel material that does not generate rust, the coating film deterioration rate of the coating film and the water vapor transmission amount representing the barrier property of the coating film conflict with each other over a long period of time. Since it is affected by sex, no correlation is shown. However, in the case of anticorrosion coating on steel material in which rust has occurred, the long-term adhesion is significantly inferior in comparison with anticorrosion coating on steel material in which rust has not occurred. For this reason, in the case of anticorrosive coating on steel material where rust has occurred, there is no need to consider the factor of long-term adhesion for the coating film, and for the coating film formed on the rust surface, the deterioration rate of the coating film is It was found that there was a correlation with the amount of water vapor transmission. And, as described above, the present inventors provide a coating film having a water vapor permeation amount of 1.5 g / (m ² · 24 h) or less with respect to the steel material from which the rust has been generated. The present invention has been found to prevent swelling, cracking, rusting and the like of the coating film.

In the rust surface coating of the present invention, for example, the resin component includes an epoxy resin and a curing agent,
The curing agent includes a polyamine compound, and the pigment includes a scaly pigment.

  In the rust surface coating material of the present invention, for example, the pigment contains at least one selected from the group consisting of talc, mica, glass flakes, and aluminum flakes.

  In the rust surface coating material of the present invention, for example, the content of the pigment in the nonvolatile content of the composition is 1 to 70% by mass.

  The coating method of the present invention uses, for example, the rust surface coating of the present invention as the coating.

  In the coating method of the present invention, for example, the rust thickness of the steel material is 0.1 to 400 μm, 0.1 to 300 μm, 0.1 to 200 μm, or 0.1 to 100 μm.

  In the coating method of the present invention, for example, on the rust surface of the steel material, the maximum thickness of rust is 0.1 to 3000 μm, 0.1 to 2000 μm, 0.1 to 1400 μm, or 0.1 to 700 μm.

  In the coating method of the present invention, for example, the film thickness of the coating film on the rust surface is 50 to 1000 μm.

  The coating method of this invention forms a coating film by apply | coating the said coating material to the said steel materials and hardening | curing in the said coating-film process, for example.

  In the coating method of the present invention, for example, the coating film is a laminated film, and in the coating film process, the coating material is applied to the steel material and dried repeatedly.

In the coated steel material of the present invention, for example, the resin component includes an epoxy resin and a curing agent,
The curing agent includes a polyamine compound, and the pigment includes a scaly pigment.

  In the coated steel material of the present invention, for example, the pigment includes at least one selected from the group consisting of talc, glass flakes, mica, and aluminum flakes.

  In the coated steel material of the present invention, for example, the pigment content in the coating film is 1 to 70% by mass.

  In the coated steel material of the present invention, for example, in the steel material, the surface in contact with the coating film has a rust surface, and the rust thickness of the rust surface is 0.1 to 400 μm, 0.1 to 300 μm, 0 .1 to 200 μm, or 0.1 to 100 μm.

  In the coated steel material of the present invention, for example, on the rust surface of the steel material, the maximum thickness of rust is 0.1 to 3000 μm, 0.1 to 2000 μm, 0.1 to 1400 μm, or 0.1 to 700 μm.

  In the coated steel material of the present invention, for example, the thickness of the coating film is 50 to 1000 μm.

  Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments.

<Coating for rust surface>
The rust surface coating material of the present invention (hereinafter also referred to as the coating material of the present invention) is a composition containing a resin component and a pigment as described above, and when the coating film is formed from the composition, the coating material is applied. The water vapor permeation amount of the membrane is 1.5 g / (m ² · 24 h) or less.

  The paint of the present invention is a paint for a rust surface, that is, a paint for a steel material in which rust has occurred. The paint of the present invention can be used, for example, on the surface of the steel material on which rust has not been generated as well as the rust surface on which rust has occurred. About the said steel materials, rust, etc., the description of the coating method of this invention mentioned later can be used.

The water vapor transmission amount of the coating film may be 1.5 g / (m ² · 24 h) or less. When the water vapor permeation amount exceeds 1.5 g / (m ² · 24 h), the corrosion prevention for the steel material becomes insufficient, and it becomes difficult to ensure the corrosion resistance particularly for a long time. The water vapor transmission amount of the coating film is preferably 1.2 g / (m ² · 24 h) or less, more preferably 0.8 g / (m ² · 24 h) or less, and further preferably 0.5 g / (m ² · ² h). 24h) or less. A method for measuring the water vapor transmission rate will be described later.

As described above, the coating material of the present invention satisfies that when the coating film is formed, the water vapor transmission rate of the coating film is 1.5 g / (m ² · 24 h) or less. What is necessary is just to include, and the composition etc. are not restrict | limited in particular. The paint of the present invention may be, for example, one kind of single paint or a paint kit containing two or more kinds of single paints. The resin component may include, for example, a resin as a binder component, and may further include a curing agent for the resin. As a specific example, the paint of the present invention includes a composition containing an epoxy resin as the resin of the resin component and a scaly pigment as the pigment (hereinafter also referred to as paint t) from the viewpoint of the water vapor transmission amount. preferable. Hereinafter, the paint t containing the epoxy resin and the scaly pigment will be described as an example of the paint of the present invention.

(1) Paint t
As described above, the paint t is a composition containing the epoxy resin and the scaly pigment.

  For example, as described above, the resin component contains an epoxy resin as the resin from the viewpoint of reducing the water vapor transmission amount. The epoxy resin may be, for example, a so-called pure epoxy resin or an epoxy resin having a chemically changed resin skeleton. In the composition, the epoxy resin may be used as a mixed system used in combination with a resin other than the epoxy resin, for example. The epoxy resin is a resin having an epoxy group, and the number of the epoxy groups is, for example, 2 or more per molecule, preferably 2 to 5 per molecule. The molecular weight of the epoxy resin is not particularly limited, and as a specific example, when represented by a number average molecular weight, it is, for example, 350 to 3,000, 400 to 1,500, and the epoxy equivalent is, for example, about 80 to 1, 000, 150-700.

  In the present invention, the number average molecular weight is measured under the same conditions by measuring the retention time (retention capacity) of a test resin (for example, the epoxy resin) using a gel permeation chromatograph (GPC). It is a value obtained by converting to the molecular weight of polystyrene by the retention time (retention capacity) of standard polystyrene having a known molecular weight. Specifically, the gel permeation chromatograph uses “HLC8120GPC” (trade name, manufactured by Tosoh Corporation), and the columns are “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”. And “TSKgel G-2000HXL” (trade name, all manufactured by Tosoh Corporation), and the mobile phase is maintained under the conditions of tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min, and detector RI. The time (retention capacity) can be measured to determine the number average molecular weight.

  Examples of the epoxy resin include epoxy resins obtained by reacting polyhydric alcohol or polyhydric phenol with excess epichlorohydrin or alkylene oxide. Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, propylene glycol, neopentyl glycol, butylene glycol, hexanediol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, diglycerol, sorbitol and the like. Examples of the polyhydric phenol include 2,2-bis (4-hydroxyphenyl) propane [also known as bisphenol A], halogenated bisphenol A, 4,4-dihydroxyphenylmethane [also known as bisphenol F], and tris (4-hydroxyphenyl). ) Propane, resorcin, tetrahydroxyphenylethane, novolac polyhydric phenol, cresol polyhydric phenol, and the like.

  The epoxy resin is not limited to these examples. For example, 1,2,3-tris (2,3-epoxypropoxy) propane, diglycidyl phthalate, glycidyl hexahydrophthalate, glycidyl tetrahydrophthalate Ester, dimer acid glycidyl ester, tetraglycidylaminodiphenylmethane, 3,4-epoxy-6-methylcyclohexylmethylcarboxylate, triglycidyl isocyanurate, 3,4-epoxycyclohexylmethylcarboxylate, polypropylene glycol glycidyl ether, etc. as synthetic materials Examples thereof include an epoxy resin obtained by using and reacting with epichlorohydrin or alkylene oxide.

  As described above, the resin component may include, for example, the epoxy resin and other resins as the resin. Examples of the resin other than the epoxy resin include xylene resin, toluene resin, ketone resin, coumarone resin, and petroleum resin, and these can be used as a combined resin for the epoxy resin. The combination resin may be, for example, any one kind or may contain two or more kinds of resins. For example, when the resin further contains the combination resin in addition to the epoxy resin, for example, the corrosion resistance against a rust surface can be further improved.

  In the paint t, the resin component may further contain a curing agent, for example, depending on the type of the resin. That is, for example, when the resin is cured by a reaction with the curing agent, or when the resin is cured more efficiently by a reaction with the curing agent, the resin component preferably further includes the curing agent. . The type of the curing agent is not particularly limited, and can be appropriately selected according to, for example, the type of the resin.

  Examples of the curing agent include polyamine compounds. When the resin includes the epoxy resin, the curing agent is preferably the polyamine compound, and the curing agent is also referred to as a crosslinking agent. When the resin is the epoxy resin, the polyamine compound preferably has a primary amino group, a secondary amino group, or both for a curing reaction with the epoxy resin, for example. Further, the active hydrogen equivalent of the polyamine compound is, for example, about 2,000 or less, and preferably in the range of about 30 to 1,000.

  Examples of the polyamine compound include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, and pentaethylenehexamine; aromatic polyamines such as metaxylenediamine, diaminodiphenylmethane, and phenylenediamine. Alicyclic polyamines such as isophorone diamine, cyclohexylpropyl diamine and norbornene diamine; modified polyamines such as epoxy adducts of these polyamines; polyamides having at least one primary amino group at the molecular end It is done. As said hardening | curing agent, the ketimine thing of these said polyamine compounds can also be used, for example. The ketiminate is obtained, for example, by blocking the polyamine compound with a carbonyl compound. Examples of the carbonyl compound include ketones such as acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone; aldehydes such as acetaldehyde and benzaldehyde.

  In the paint t, the content of the resin component is not particularly limited. Content of the said resin component in the non volatile matter of the said composition is 1-70 mass% and 10-40 mass%, for example.

  In the paint t, the content of the resin is not particularly limited, and the content of the resin in the nonvolatile content of the composition is, for example, 1 to 70% by mass and 10 to 40% by mass. Moreover, content of the said epoxy resin in the non volatile matter of the said composition is 1-70 mass% and 10-40 mass%, for example. Moreover, when the said resin contains the said epoxy resin and the said combined use resin, content of the said combined use resin is not restrict | limited in particular, For example, 1-100 mass parts on the basis of 100 mass parts of the said epoxy resin, 10 The range of -50 mass parts, the range of 10-350 mass parts, 30-300 mass parts, etc. can be illustrated.

  When the paint t further includes the curing agent as the resin component, the content of the curing agent is not particularly limited, and is appropriately determined according to, for example, the type of the resin, the content of the resin, and the like. it can. When the resin component includes the epoxy resin as the resin and includes the polyamine compound as the curing agent, the content of the curing agent is the polyamine with respect to 1 equivalent of the epoxy group in the epoxy resin. The active hydrogen equivalent in the compound is, for example, about 0.4 to 1.2 equivalent, and preferably about 0.4 to 1.0 equivalent from the viewpoint of the corrosion resistance of the steel material to be coated.

  The pigment is preferably a scaly pigment as described above, for example, from the viewpoint of reducing the water vapor transmission rate. Examples of the scaly pigment include talc, mica, glass flakes, and aluminum flakes. In the paint t, the scaly pigment may be, for example, one type or two or more types.

  In the paint t, the content of the pigment is not particularly limited. When the said pigment contains the said scale-like pigment, content of the said scale-like pigment in the non volatile matter of the said composition is the range of 1-70 mass%, for example.

  The paint t includes, for example, the scaly pigment from the viewpoint of the corrosion resistance of the steel material to be coated. The size of the scaly pigment is not particularly limited. For example, the average thickness is, for example, 0.1 to 15 μm, the average major axis is, for example, 0.01 to 2 mm, from the point that the anticorrosion performance can be further improved. What has a peak of a particle size distribution is 0.01-2 mm, for example. The scaly pigment is preferably talc, mica, glass flakes, aluminum flakes, and the like. For example, the paint t may include any one kind or two or more kinds as the scaly pigment. In the paint t, the content of the scaly pigment is not particularly limited. As a specific example, the content of the scaly pigment in the nonvolatile content of the paint t is, for example, 1 to 70% by mass. The scaly pigment is also referred to as flakes, for example. The character of the scaly pigment is not particularly limited.

  The size of the scaly pigment is not particularly limited, and the average particle size of the particles is, for example, 1 to 1500 μm. The average particle diameter can be calculated and defined as follows for each numerical range, for example. That is, an average particle size of 1 to 500 μm means that the particle size of the scaly pigment is measured using a laser diffraction / scattering particle size distribution measuring device, and the obtained 50% average particle size (accumulated on a volume basis). This means that the particle diameter (also referred to as 50% particle diameter or median diameter) is 1 to 500 μm, and is represented by a sphere equivalent diameter by a laser diffraction / scattering method. The average particle diameter is more than 500 μm and not more than 1500 μm by observing the scaly pigment with an optical microscope, measuring the major axis of 50 arbitrary particles, and calculating the average value of the 50 particle diameters. Means more than 500 μm and 1500 μm or less. In the scaly pigment, the “major axis” is the length in the longest direction of the particle in the plane direction when the particles that are the scaly pigment are placed on a horizontal plane and observed with an optical microscope. "Is the length in the shortest direction of the particles in the plane direction, and" thickness "is the length in the direction perpendicular to the plane direction.

  The aspect ratio of the scaly pigment is not particularly limited and is, for example, 1 to 750. The aspect ratio of the scaly pigment is represented by the ratio (D / T) of the average particle diameter (D) and the average thickness (T). The average particle diameter of the scaly pigment is as described above. The average thickness (T) of the scaly pigment is determined by measuring the thickness of the scaly pigment (the length in the direction perpendicular to the major axis and the minor axis) using an SEM (scanning electron microscope) or an optical microscope. It can be calculated as the average value of the thickness of the 50 particles.

  For example, the pigment may further contain a rust preventive pigment in addition to the scaly pigment from the viewpoint of the corrosion resistance of the steel material to be coated.

  Examples of the rust preventive pigment include zinc, zinc phosphate, phosphorous zinc silicate, aluminum phosphate, aluminum zinc phosphate, calcium zinc phosphate, calcium phosphate, aluminum pyrophosphate, calcium pyrophosphate, aluminum trihydrogen phosphate, aluminum metaphosphate , Calcium metaphosphate, zinc phosphomolybdate, aluminum phosphomolybdate, aluminum dihydrogen triphosphate, aluminum phosphomolybdate, zinc molybdate, barium metaborate, hydrocalumite and the like. For example, any one kind or two or more kinds of the antirust pigments may be included.

  In the paint t, the content of the rust preventive pigment is, for example, 1 to 50 parts by mass and 1 to 30 parts by mass with respect to 100 parts by mass of the resin component.

  In addition to the resin component and the pigment described above, the paint t may further include, for example, pigments such as color pigments and extender pigments, organic solvents, additives (for example, silane coupling agents, additives, and the like). Components such as a sticking agent, a plasticizer, an anti-sagging agent, and a pigment dispersant may be included. These components may be any one kind, for example, and may contain two or more kinds.

  Examples of the coloring pigment include coloring pigments such as titanium dioxide, iron oxide, and carbon black; extender pigments such as mica, silica, calcium carbonate, and barium sulfate; brightness such as nickel, chromium, tin, copper, silver, platinum, and gold And pigments. For example, the color pigment may be any one kind or two or more kinds.

  When the paint t contains the antirust pigment as described above in addition to the scale pigment, the total content of the various pigments is not particularly limited, and is based on 100 parts by mass of the resin component. For example, it is the range of 100-200 mass parts. In the paint t, the total content of the various pigments in the non-volatile content of the paint t is, for example, 1 to 80% by mass.

  The paint t may further contain a volatile component as a volatile component in addition to the resin component and the non-volatile component such as the pigment. Examples of the volatile component include the organic solvent. In the paint t, the volatile component is blended, for example, when each component such as the resin component contained in the paint t is manufactured, when the paint t is manufactured, and is included when the paint t is used. When applied to the object to be coated and formed as a coating film on the steel material as will be described later, it is a component that is not substantially contained due to volatilization. In the coating material t, the volatile component is preferably included because, for example, workability in manufacturing the component, manufacturing the coating material t, and painting the coating material t can be improved.

  The type of the organic solvent is not particularly limited, and can be appropriately selected depending on, for example, the type of other nonvolatile components in the coating material t, the content thereof, and the like. Examples of the organic solvent include aromatic hydrocarbon solvents such as toluene and xylene; mineral spirits; aliphatics such as n-hexane, n-heptane, n-octane, n-decane, n-dodecane, cyclopentane, and cyclohexane. Hydrocarbon solvents; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone; ester solvents such as ethyl acetate, n-butyl acetate and isobutyl acetate; alcohol solvents such as ethyl alcohol, propyl alcohol and butyl alcohol Glycol solvents such as ethylene glycol, diethylene glycol, propylene glycol and hexylene glycol; glycol ether solvents such as methyl ether, ethyl ether, propyl ether and butyl ether of these glycol solvents Come known solvents can be used.

  In the coating material t, the content of the volatile component is not particularly limited. For example, 100 parts by mass of the resin component from the viewpoint of workability at the time of manufacturing or coating as described above and the concentration adjustment of the nonvolatile component. For example, the range is 100 to 200 parts by mass. Moreover, in the said coating material t, the said non volatile matter is generally 50-100 mass% and 60-90 mass%, for example.

  For example, the paint t may have a one-pack type or a two-pack type depending on the type of the resin component, specifically, the type of the resin and the type of the curing agent. Also good. When the coating material t is the two-component type, for example, the coating material t may be prepared by mixing both immediately before use.

  The coating material of this invention can be used for the coating method to the rust surface steel material of this invention mentioned later, and can form the coating film in the coating steel material of this invention mentioned later.

  The coating film formed using the paint of the present invention may be, for example, a single layer or a laminate of two or more layers. In the latter case, the paint used for forming each single layer constituting the laminate may be, for example, the same paint or a different paint.

  When the coating film is a laminate, for example, one kind of the paint t may be used as the paint of the present invention, or two or more kinds of paints t having different compositions may be used. In the latter case, the paint of the present invention may be, for example, a kit containing two or more kinds of paints t.

  As described above, when the coating material of the present invention is a kit including two or more types of coating material t, for example, the coating material t that forms the first single layer with respect to the steel material is also referred to as an undercoat coating material t1.

  As described above, when the undercoat paint t1 includes the combination resin in addition to the epoxy resin as the resin, the combination resin includes, for example, a urethane-modified epoxy resin, a xylene resin, a toluene resin, a ketone resin, A coumarone resin, a petroleum resin, etc. are mention | raise | lifted, Any one kind may be sufficient and two or more types may be included. Examples of the urethane-modified epoxy resin include resins obtained by reacting an amine-added epoxy resin with a polyisocyanate compound or a monoisocyanate compound. The amine-added epoxy resin can be obtained, for example, by reacting an amine with the epoxy resin. The molecular weight of the urethane-modified epoxy resin is not particularly limited. As a specific example, the molecular weight is 1,000 to 65,000, 2,000 to 25,000, for example. In the undercoat paint t1, when the resin contains the epoxy resin and the combination resin, the content of the combination resin is not particularly limited, and is, for example, 10 to 350 on the basis of 100 parts by mass of the epoxy resin. The range of a mass part and 30-300 mass parts can be illustrated. The mass part of the epoxy resin can be represented, for example, by the mass of the nonvolatile content of the epoxy resin.

  The undercoat paint t1 may further include, for example, pigments such as color pigments, extender pigments, rust preventive pigments, organic solvents, additives (for example, silane coupling agents, thickeners, plasticizers, sauces, etc.). Ingredients such as a stopper, a pigment dispersant and the like may be included. These components may be any one kind, for example, and may contain two or more kinds.

  Moreover, when the said coating film is a laminated body, for example, after forming the coating film by the said coating material t (henceforth the coating film T), the coating film using the top coating material b mentioned later on the said coating film B may be formed. For this reason, the paint of the present invention may be, for example, a kit including the paint t and the top coat b. In this case, for example, as described above, the paint t may be one kind or two or more kinds. In the latter case, for example, the first layer undercoat paint t1 may be included. When the paint of the present invention is the kit, for example, each paint may be stored in a separate container.

(2) Undercoat paint a
When the paint of the present invention is a kit as described above, for example, an undercoat paint a may be included in addition to the paint t. Here, the undercoat paint a will be described as a paint different from the paint t (specifically, for example, the undercoat paint t1). The undercoat paint a is used, for example, from the viewpoint of corrosion protection of a steel material to be coated. The undercoat paint a includes, for example, a resin and a curing agent as resin components. The resin includes, for example, an epoxy resin and a combination resin for the epoxy resin.

  Examples of the epoxy resin include the resin exemplified for the paint t. Examples of the combined resin include urethane-modified epoxy resin, xylene resin, toluene resin, ketone resin, coumarone resin, and petroleum resin, and any one kind or two or more kinds may be included. Examples of the urethane-modified epoxy resin include resins obtained by reacting an amine-added epoxy resin with a polyisocyanate compound or a monoisocyanate compound. The amine-added epoxy resin can be obtained, for example, by reacting an amine with the epoxy resin. The molecular weight of the urethane-modified epoxy resin is not particularly limited. As a specific example, the molecular weight is 1,000 to 65,000, 2,000 to 25,000, for example. When the resin includes the epoxy resin and the combination resin, the content of the combination resin is not particularly limited, and is, for example, 10 to 300 parts by mass, 30 to 200 based on 100 parts by mass of the epoxy resin. The range of mass parts can be exemplified. The mass part of the epoxy resin can be represented, for example, by the mass of the nonvolatile content of the epoxy resin.

  Examples of the curing agent include polyamine compounds. Examples of the polyamine compound include the resins exemplified for the paint t.

  If necessary, the undercoat paint a may further include, for example, pigments such as coloring pigments, extender pigments, rust preventive pigments, organic solvents, additives (for example, silane coupling agents, thickeners, plasticizers, sauces). Ingredients such as a stopper, a pigment dispersant and the like may be included. These components may be any one kind, for example, and may contain two or more kinds.

  For example, the undercoat paint a may have a one-pack type or a two-pack type depending on the type of the resin component, specifically the type of the resin and the type of the curing agent. It is good. When the undercoat paint a is the two-pack type, for example, the undercoat paint a may be prepared by mixing both immediately before use.

  The kit of the present invention may be, for example, a kit including the paint t and the undercoat paint a, or a kit including the paint t, the undercoat paint a, and a top coat b described later. When the paint of the present invention is the kit, for example, each paint may be stored in a separate container.

(3) Top coating b
The top coat b is used, for example, from the viewpoint of durability of the steel material to be coated. The top coating material b includes, for example, a resin as a resin component. The resin includes, for example, an acrylic resin.

  Examples of the acrylic resin include resins having a (meth) acryloyl compound and, if necessary, another polymerizable unsaturated compound as a copolymerization component. Examples of the compound serving as the copolymer component include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, and iso- Butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) Acrylate (lauryl (meth) acrylate), tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate Rate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate or other alkyl or cycloalkyl (meth) acrylate; acrylic Carboxyl group-containing polymerizable unsaturated compounds such as acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and β-carboxyethyl acrylate; 2-acrylamido-2-methylpropanesulfonic acid, allylsulfonic acid, styrenesulfonic acid sodium salt Sulfonic acid group-containing polymerizable unsaturated compounds such as sulfoethyl methacrylate and sodium salts and ammonium salts thereof; 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxye Acid group-containing polymerizable unsaturated compounds such as phosphoric acid group-containing polymerizable unsaturated compounds such as tilacyl phosphate, 2-acryloyloxypropyl acid phosphate, and 2-methacryloyloxypropyl acid phosphate; 2-hydroxyethyl (meth) acrylate, C2-C8 hydroxyalkyl (meth) acrylates such as 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; N-methylolacrylamide; allyl alcohol; carbon number Ε-caprolactone-modified acrylic compound of 2-8 hydroxyalkyl (meth) acrylates; diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, polyethylene glycol Hydroxyl group content such as polyalkylene glycol (meth) acrylates such as polyol (meth) acrylate, dipropylene glycol (meth) acrylate, tripropylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, and polyethylene polypropylene glycol (meth) acrylate Polymerizable unsaturated compounds; aromatic ring-containing polymerizable unsaturated compounds such as benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene; N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide , Alkoxyalkyls such as methoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, ethoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, etc. ), Polyalkylene glycol monoalkoxy (meth) acrylate and other alkoxy group-containing polymerizable unsaturated compounds such as acrylate and polyethylene glycol monomethoxy (meth) acrylate; perfluorobutylethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate Perfluoroalkyl (meth) acrylates such as; polymerizable unsaturated compounds having a fluorinated alkyl group such as fluoroolefin; (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, Nitrogen-containing polymerizable unsaturated compounds such as N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, adducts of glycidyl (meth) acrylate and amines; Terminated polyoxyethylene chain having a (meth) acrylate is an alkoxy group; and the like. Any one kind of these polymerizable unsaturated compounds may be used, or two or more kinds thereof may be used in combination.

  For example, the acrylic resin preferably contains a hydroxyl group from the viewpoint of water vapor transmission. When the acrylic resin contains a hydroxyl group, the hydroxyl value of the acrylic resin is, for example, in the range of 10 to 200 mgKOH / g, 50 to 100 mgKOH / g.

  The resin component may further contain a curing agent in addition to the resin, for example. When the resin is an acrylic resin containing the hydroxyl group, the curing agent is preferably a polyisocyanate compound, for example.

  The polyisocyanate compound is not particularly limited, and for example, a compound containing two or more isocyanate groups in one molecule is preferable. Examples of the polyisocyanate compound include aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as 4,4′-methylenebis (cyclohexyl isocyanate) and isophorone diisocyanate; Examples thereof include aromatic diisocyanates such as tolylene diisocyanate, polytolylene polyisocyanate, diphenylmethane diisocyanate, polymethylene polyphenylene diisocyanate, polyphenylmethane diisocyanate, and naphthalene diisocyanate. Examples of the curing agent include, in addition to these polyisocyanate compounds, for example, isocyanurate-modified products of the polyisocyanate compounds, urethane polymers (for example, reaction products of polyols and excess polyisocyanates, And those having an isocyanate group at the molecular end) and similar compounds such as a burette body. Any one kind of the curing agent may be used, or two or more kinds may be used in combination.

  For example, the top coat b may have a one-pack type or a two-pack type depending on the type of the resin component, specifically, the type of the resin and the type of the curing agent. It is good. When the top coating material b is the two-pack type, for example, the top coating material b may be prepared by mixing both just before use. As the top coating material b, for example, a commercially available product can be used. As a specific example, a urethane-based top coating material containing a urethane polymer as a curing agent can be used.

  The kit of the present invention may be, for example, a kit including the paint t and the top coat b, or a kit including the paint t, the undercoat paint a, and the top coat b. When the paint of the present invention is the kit, for example, each paint may be stored in a separate container.

<Coating method>
The coating method on the rust surface steel material of the present invention includes a coating film step of forming a coating film using a paint containing a resin component and a pigment on the steel material having a rust surface as described above, and the coating film process In this case, the rust surface coating material of the present invention is used as the coating material, and the water vapor transmission rate of the coating film is 1.5 g / (m ² · 24 h) or less.

The present invention is characterized in that the coating film is formed on a steel material having a rust surface so that the water vapor transmission amount is 1.5 g / (m ² · 24 h) or less. There are no restrictions. According to the present invention, for example, even when rust is generated in a steel material, the above-described problem can be avoided by setting the water vapor transmission rate of the coating film to 1.5 g / (m ² · 24 h) or less. it can. That is, by forming a coating film under the above conditions, for example, progress of corrosion of the steel material under the coating film, swelling of the coating film, generation of cracks, generation of further rust on the coating film forming surface of the steel material Etc. can be suppressed.

The point of the present invention is that the coating film for a steel material having a rust surface has a water vapor transmission rate of 1.5 g / (m ² · 24 h) or less, but the water vapor transmission rate of the coating film is 1.5 g / (m ² · 24h) The method of adjusting to the following is not limited at all.

The water vapor transmission amount of the coating film may be 1.5 g / (m ² · 24 h) or less. When the water vapor permeation amount exceeds 1.5 g / (m ² · 24 h), the corrosion prevention for the steel material becomes insufficient, and it becomes difficult to ensure the corrosion resistance particularly for a long time. The water vapor transmission amount of the coating film is preferably 1.2 g / (m ² · 24 h) or less, more preferably 0.8 g / (m ² · 24 h) or less, and further preferably 0.5 g / (m ² · ² h). 24h) or less.

The method for measuring the water vapor transmission rate of the coating film can be carried out as follows according to “JIS Z 0208 Moisture permeability test method for moisture-proof packaging material (cup method)”. In the measurement of the water vapor transmission amount, the coating film formed on a substrate such as polypropylene was evaluated in the same manner as the coating film formation on the steel material having the rust surface, and the coating film peeled off from the substrate was evaluated. Use as a target.
(I) A sample bottle was prepared by polishing the upper surface of the opening to be flat, and 15 g of calcium chloride was placed in the sample bottle. Then, an epoxy-based elastic adhesive Cemedine (registered trademark) EP001K (product name, Cemedine) is applied to the upper surface of the mouth of the sample bottle, and the coating film to be evaluated is pasted so as to cover the mouth. wear. The inner diameter of the mouth of the sample bottle is 41 mm.
(II) The weight of the sample bottle containing calcium chloride and the coating film to be evaluated is measured. This weight is the initial weight of the coating film in the calcium chloride and the sample bottle.
(III) The sample bottle is stored in a desiccator containing silica gel. At the start of measurement, the sample bottle is transferred to a desiccator (humidity 99%) containing water, and the weight of the sample bottle is measured at a fixed time every day (that is, every 24 hours). And the weight of the calcium chloride and the coating film in the sample bottle (4-digit balance).
(IV) The initial weight change is ignored, and the water vapor transmission rate (g / (m ² · 24h)) is calculated from the stable weight increase portion.
(V) The weight is measured for one week or longer. Three tests are performed on the same coating film (x3 formula), and the average value is taken as measurement data.

  In the present invention, painting means surface treatment for covering the surface of an object with a coating film.

  In the present invention, the steel material to be coated is preferably a steel material having a rust surface as described above. According to this invention, even if it is a steel material which has a rust surface, it can coat, for example, without removing rust from the said rust surface. Further, according to the present invention, even when coating on the rust surface, for example, the progress of corrosion of the steel material under the coating film is suppressed, and the swelling and peeling of the coating film and the coating surface are performed. The generation of new rust can be prevented.

  The type of the steel material is not particularly limited, and examples thereof include steel materials that constitute a steel structure. The type of the steel material is not particularly limited, and for example, cold rolled steel material, hot rolled steel material, galvanized steel material, alloy galvanized steel material, zinc-iron alloy plated steel material, zinc-aluminum alloy plated steel material, zinc-aluminum-magnesium composite material. Gold-plated steel, aluminum-plated steel, chrome-plated steel, nickel-plated steel, zinc-nickel alloy steel, tin-plated steel, etc. Examples include metal sprayed steel materials such as sprayed steel materials, and weather resistant steel materials. The steel structure is not particularly limited, and examples thereof include steel structures constructed outdoors such as power transmission towers, plants, bridges, tanks, harbor facilities, and the like.

  In the coating method of the present invention, the steel material to be subjected to the coating film process may be, for example, a steel material in which rust has occurred, or a steel material in which a coating film (hereinafter also referred to as an old coating film) formed by a previous treatment remains. It may be. Thus, even when the previous coating film remains or rust is generated in the steel material, according to the present invention, by setting the water vapor transmission amount of the coating film as the above condition, for example, Even if the old coating film is peeled off (removed) or the coating film is formed without removing the rust, the effect as described above can be obtained by this coating film.

  In addition, the coating method of this invention does not exclude the form which removes the rust from the said steel materials, the removal of the said old coating film, etc., for example. That is, the coating method of the present invention may include, for example, a ground treatment process for performing a ground treatment on the steel material, for example, prior to the coating film process. Examples of the base treatment step include a step of removing rust from the steel material, a step of removing the old coating film from the steel material, and the like. Examples of the removal of rust from the steel material include blast treatment, treatment with a power tool, hand cleansing with a wire brush, and the like. When the old coating film has deteriorated, for example, the removal of the old coating film from the steel material can use the same method as the removal of the rust. Even when the old coating film is not deteriorated, for example, the same treatment can be performed. When the old coating film is not deteriorated, for example, it is preferable that the old coating film is subjected to a roughening treatment as the base treatment.

The thickness of the rust in the steel material is not particularly limited. According to the method of the present invention, for example, the present invention can be applied to a steel material having rust having the following thickness. The lower limit of the rust thickness in the steel material is not particularly limited, and is, for example, 0.1 μm, 50 μm, and 70 μm, and the upper limit is, for example, 400 μm, preferably 300 μm, more preferably 250 μm, 200 μm, 100 μm. The range of the thickness of the rust is, for example, 0.1 to 400 μm, preferably 0.1 to 300 μm, more preferably 0.1 to 250 μm, 0.1 to 200 μm, and 0.1 to 100 μm. . The thickness of the rust is an average thickness on the surface of the steel material unless otherwise specified. The average thickness can be calculated as an average value of 52 rust thicknesses at locations where rust is randomly measured with respect to an area of 150 cm ^{2 of the} steel material.

  The maximum thickness of rust in the steel material is not particularly limited. Rust generally causes local pitting. In the portion where rust is generated, for example, the pitting portion tends to have an extremely thick rust thickness as compared with other portions. Therefore, although depending on the rust generation environment, the average thickness of rust and the maximum thickness of rust are generally correlated with each other. Specifically, the maximum thickness of rust is, for example, the average thickness of rust. About 2 to 10 times, more specifically about 5 to 7 times. Examples of the upper limit of the maximum thickness include 3000 μm, 2000 μm, 1400 μm, and 700 μm. When the average thickness is 0.1 to 400 μm, the maximum thickness is, for example, 0.1 to 3000 μm. When the average thickness is 0.1 to 300 μm, the maximum thickness is, for example, 0.1 to 3000 μm. When the average thickness is 2000 μm and the average thickness is 0.1 to 200 μm, the maximum thickness is, for example, 0.1 to 1400 μm. When the average thickness is 0.1 to 100 μm, the maximum thickness is, for example, 0.1 to 700 μm.

In this invention, the measuring method of the thickness of rust can be calculated | required with a magneto-dielectric electromagnetic film thickness meter according to JISK5600-1-7, for example. Specifically, 52 points of rust thickness are randomly measured with respect to an area of 150 cm ^{2 in} the steel material, and the average value can be calculated as the rust thickness.

In the coating film process, the method of forming the coating film is not particularly limited, and as described above, the coating film is formed so that the water vapor transmission amount is 1.5 g / (m ² · 24 h) or less. That's fine. As the method for forming the coating film, for example, the coating material for rust surface of the present invention is used, and the coating material of the present invention is applied to the surface of the steel material, in particular, the surface having the rusted surface. The coating film can be formed.

  The method of applying the paint to the steel material is not limited at all, and examples thereof include a method of applying or spraying. For the application, for example, a method using a general tool such as a brush, a roller, or a spray gun can be employed.

  In the coating step, the paint applied to the steel material is preferably cured by drying to form a coating film, for example. The drying conditions are not particularly limited, and may be any conditions as long as the volatile components contained in the paint disappear (volatilize) after the paint is applied. The drying conditions are, for example, room temperature drying, and specific examples include a temperature of 20 to 30 ° C., a humidity of 0 to 70%, and a number of days of 1 to 7 days. In addition, the said drying conditions are illustrations, Comprising: This invention is not restrict | limited to this, Since the said drying is performed outdoors when the said steel materials are the steel structures installed outdoors, for example, outdoor The drying days may be adjusted according to the temperature and outdoor humidity.

  As described above, the coating film formed on the surface of the steel material may be, for example, a single layer film or a laminated film in which a plurality of single layer films are laminated. In the case where the coating film is the laminated film, it is preferable that the coating process repeats application and drying of the paint, for example.

  In the coating step, as described above, the paint of the present invention can be used as the paint, and specifically, the use of the paint t is preferable. When the coating film T formed by the coating material t is the laminated film, for example, only one type of coating material t may be used, or two or more types of coating material t may be used in combination. When the coating film T formed by the coating material t includes, for example, at least one of the undercoat and the topcoat film, the total film thickness is, for example, 50 to 1000 μm, 100 to 500 μm, and 100 to 400 μm.

  When the coating film is the laminated film, the thickness of each single layer film is not particularly limited, and is, for example, 50 to 1000 μm, 100 to 500 μm, 100 to 400 μm, and the number of laminated single layer films is, for example, 2-8 layers, 2-5 layers, 2-3 layers.

  The coating method of the present invention may further include, for example, an undercoat film forming step before the coating film step, and may further include an overcoat film forming step after the coating film step. The coating method of the present invention may include, for example, only one or both of the undercoat film forming step and the overcoat film forming step.

The undercoat film forming step is a step of forming the undercoat film A on the surface of the steel material using the undercoat paint a prior to the coating step. Specifically, the undercoat film forming step is, for example, a step of applying the undercoat paint a to the surface of the steel material to form an undercoat film A, and after this step, the coating film step is performed as described above. On the undercoat film A, the coating film T is formed using the coating material t. The undercoat paint a applied to the steel material is preferably, for example, dried after application to form the undercoat film A. The drying conditions are not particularly limited, and are the same as described above, for example. The thickness of the undercoat film A is not particularly limited, and is, for example, 10 to 200 μm or 30 to 100 μm. The undercoat film A may be, for example, a single layer film or a laminated film in which single layer films are laminated. The undercoat film A and the coating film T formed on the surface of the steel material preferably have a water vapor transmission rate of 1.5 g / (m ² · 24 h) or less as a whole.

The step of forming the top coat film is a step of forming the top coat film B on the surface of the coat T using the top coat paint b after the coat step. Specifically, the step of forming the top coat film is a step of forming the top coat film B by, for example, applying the top coat b on the surface of the coating film T. The top coating material b applied to the surface of the coating film T is preferably, for example, dried after application to form the top coating film B. The drying conditions are not particularly limited, and are the same as described above, for example. The thickness of the overcoat film B is not particularly limited, and is, for example, 20 to 100 μm, 25 to 50 μm. The overcoat film A may be, for example, a single layer film or a laminated film in which single layer films are laminated. The coating film T and the overcoat film B formed on the surface of the steel material preferably have a water vapor transmission rate of 1.5 g / (m ² · 24 h) or less as a whole.

When the film formed on the steel material is a laminated film of the undercoat film A and the coating film T, and when it is a laminated film of the coating film T and the overcoat film B, the undercoat film A and the coating film In the case of a laminated film of the film T and the overcoat film B, the total film thickness of each laminated film is, for example, 50 to 1000 μm, 100 to 500 μm. By setting the total film thickness of the laminated film to, for example, 50 μm or more, it becomes easier to adjust the water vapor transmission rate to 1.5 g / (m ² · 24 h) or less, and by setting it to 1000 μm or less. The peeling of the laminated film from the rust surface of the fragile steel material due to an increase in internal stress of the laminated film provided on the steel material can be sufficiently prevented.

<Coated steel>
As described above, the coated steel material of the present invention includes a steel material and a coating film, has the coating film on the rust surface of the steel material, the coating film includes a resin component and a pigment, and transmits water vapor. The amount is 1.5 g / (m ² · 24 h) or less.

  The coated steel material of the present invention can be obtained, for example, by subjecting the steel material to the coating method of the present invention. That is, the coated steel material of the present invention can also be referred to as a coated steel material manufactured by coating the steel material by the coating method of the present invention. Description of the coating material of the said this invention and the coating method of the said invention can be used for the steel material in which the said coating film is formed, the coating material which forms the said coating film, and the coating method, for example.

  In the coated steel material of the present invention, the coating film is, for example, a film formed by volatilization of a volatile component such as an organic solvent from the paint applied to the steel material. As described above, the coating film may be the single-layer film or the laminated film. When the coating film is the single-layer film, the single-layer film is preferably the coating film T, for example. When the coating film is the laminated film, for example, the coating film T may include one layer or two or more layers, and may further include at least one or both of the undercoat film A and the overcoat film B.

  A coating film was formed on the steel material, and various properties of the coating film were confirmed.

(1) Paint Four kinds of paints (Z, X, Y, Y ′) shown in Table 1 below were prepared. As paint F, a commercially available paint (manufactured by Kansai Paint Co., Ltd., urethane-based top coat “Product Name Retan 6000”) is used. Name Carboline 134K "). In Table 1 below, the unit of each component is “parts by mass”. Of the six types of paints (Z, X, Y, Y ′, F, and F ′), paints Z, X, Y, and Y ′ correspond to the paint t including the epoxy resin and the pigment, respectively. . The paint Y and the paint Y ′ are paints having the same properties including the same kind of epoxy resin and talc. The paints F and F ′ correspond to the above-described top coat paint b.

(2) Preparation of a rust steel sheet (rust steel material) having a rust surface Cold rolled steel sheet SPCC-SB (manufactured by Nippon Test Panel Co., Ltd.) 3.2 × 100 as defined in “JIS G 3101 General Structural Rolled Steel Material” A plurality of x300 mm were prepared. The steel sheet was exposed to the beach area for about 2 years, and rust was generated on the surface. The surface of the steel plate on which rust occurred was subjected to surface treatment with a power tool such as a disk sander, and the average rust thickness of 129 to 184 μm was designated as rust steel plate A. In addition, the average thickness of the rust was obtained as an average value by measuring 52 rust thicknesses at random with respect to an area of 150 cm ^{2 of the} steel plate as described above. In the rust steel plate A after the surface treatment, the maximum rust thickness was about 1400 μm in any of the rust steel plates A among 52 points at which the rust thickness was measured.

  Further, the steel sheet on which the rust was generated was subjected to a surface treatment over the rust steel sheet A, and the average rust thickness was 78 to 98 μm. Among the 52 points at which the rust thickness was measured in the rust steel plate B, the maximum rust thickness was about 1400 μm in any rust steel plate B.

(3) Coating treatment for rusted steel plate The rust surface of the rusted steel plate A and the rusted steel plate B is a single layer film as a coating film using various paints based on the coating treatment conditions shown in Table 2 below. A laminated film laminated from 2 layers to 8 layers was formed. Specifically, each of the coating materials was applied by brush painting, and after application, the coating material was dried for 1 day in an environment of 23 ° C. and 50% RH to form a single layer film. And after the said drying, the coating material of the next layer was further apply | coated on the said single layer film | membrane, and the single layer film | membrane was laminated | stacked sequentially by drying similarly. Finally, after the top coating F or F ′ was applied, curing was performed for 7 days in an environment of 23 ° C. and 50% RH. Thereby, the coated steel material in which the said coating film (the said laminated film) was formed in the rust surface of the said rust steel plate was obtained. In Table 2 below, the thickness of each single-layer film (from the first layer to the eighth layer) and the total film thickness of the laminated film all indicate the film thickness after drying. The test shown below was done about the said coated steel materials. In any of the coating films, the uppermost layer was a top coat film, and the following tests were evaluated as a laminated film including the top coat film.

The coating amounts of the various paints necessary for the dry film thickness shown in Table 2 were the theoretical coating amounts determined by the following formula. In the following formula, “specified coating thickness” is “dry film thickness” in Table 2.

(4) Various tests (4-1) Water vapor transmission test The water vapor transmission rate was measured for each coating film. The measurement of the amount of water vapor permeation of each of the coating films was carried out by using the same coating film (the laminated film) as an alternative to the coating film formed on the rust steel plate based on the coating treatment conditions shown in Table 2 below. Prepared by method. The painting method was air spray painting.

  First, a 2 mm (thickness) × 100 mm × 300 mm polypropylene plate is prepared, and each paint is applied to the surface of the polypropylene plate by air spray coating, and dried for one day in an environment of 23 ° C. and 50% RH. A single layer film was formed. And after the said drying, the following coating material was apply | coated further and the single layer film | membrane was laminated | stacked sequentially by drying similarly. Finally, after the top coating material F was applied, curing was performed for 7 days in an environment of 23 ° C. and 50% RH. After curing, the coating film (laminated film) formed on the polypropylene plate was peeled off and subjected to a water vapor transmission test.

About the coating film which is the prepared said laminated film, the water vapor transmission rate was measured as follows according to “JIS Z 0208 Moisture permeability test method of moisture-proof packaging material (cup method)”.
(I) A sample bottle was prepared by polishing the upper surface of the opening to be flat, and 15 g of calcium chloride was placed in the sample bottle. Then, an epoxy-based elastic adhesive Cemedine (registered trademark) EP001K (product name, Cemedine) is applied to the upper surface of the mouth of the sample bottle, and the coating film to be evaluated is pasted so as to cover the mouth. I attached. The inner diameter of the mouth of the sample bottle was 41 mm.
(II) The weight of the sample bottle containing calcium chloride and the coating film to be evaluated was measured. This weight was used as the initial weight of the coating film in the calcium chloride and the sample bottle.
(III) The sample bottle was stored in a desiccator containing silica gel. At the start of measurement, the sample bottle is transferred to a desiccator (humidity 99%) containing water, and the weight of the sample bottle is measured at a fixed time every day (that is, every 24 hours). The weight of the coating film contained in the calcium chloride and the sample bottle was taken as a 4-digit balance.
(IV) The initial weight change was ignored, and the water vapor transmission rate (g / (m ² · 24 h)) was calculated from the stable weight increase location.
(V) The weight was measured for one week or longer. Three tests were performed on the same coating film (x3 formula), and the average value was used as measurement data.

(4-2) Accelerated test The accelerated test was implemented based on the "JIS Z 2371 salt spray test method" about the said coating film formed on the said rust steel plate. The acceleration time was set to a predetermined time as will be described later. And about the said coating film formed on the said rust steel plate, after predetermined time progress, the swelling generation | occurrence | production area in all the areas was computed as a swelling generation | occurrence | production area ratio (%). And the deterioration of the said coating film was evaluated from the said blistering incidence.

(5) Results (5-1) Water vapor permeation amount, rust thickness, and swollen area ratio The coated steel material in which the coating film of Example 1 of Table 2 was formed on the rust steel plate A was obtained in Example 1A and the rust. The coated steel material in which the coating film of Example 2 in Table 2 was formed on the steel plate A was Example 2A, and the coated steel material in which the coating film of Comparative Example 1 in Table 2 was formed on the rusted steel sheet A was compared with Comparative Example 1A. did. With respect to the coated steel materials of Example 1A, Example 2A, and Comparative Example 1A, the swelling area ratio was evaluated after acceleration times of 1,000, 3,000, 6,900, and 8,500 hours, respectively. And as a result of these Examples and Comparative Examples, the amount of water vapor permeation, the thickness of rust, and the area ratio of swelling occurrence after 8500 hours of acceleration time are shown in Table 3 below.

  Moreover, about the coating steel materials of Example 1A and Comparative Example 1A, the swelling rate was evaluated after acceleration times of 1,500, 2,000, 3,900, and 5,500 hours, respectively. And as a result of these Examples and Comparative Examples, the amount of water vapor permeation, the thickness of rust, and the area ratio of blistering after 5500 hours of acceleration time are shown in Table 4 below.

As shown in Table 3, in the coated steel material of Comparative Example 1A, the water vapor transmission rate of the coating film exceeds 1.5 g / (m ² · 24 h), and the rate of occurrence of blistering which is an indicator of deterioration at an acceleration time of 8500 hours Was 16.47%. On the other hand, the coating steel materials of Example 1A and Example 2A both have a water vapor transmission amount of the coating film of 1.5 g / (m ² · 24 h) or less, and the occurrence rate of blistering, which is an indicator of deterioration, is It was 1/2 or less of Comparative Example 1A. From this, it was found that the deterioration of the coating film with respect to the rust steel material can be suppressed by setting the water vapor permeation amount of the coating film to 1.5 g / (m ² · 24 h) or less. Moreover, as shown in the said Table 4, also when it was set as acceleration time 5500 hours, the coated steel material of Example 1A showed suppression with the deterioration superior to the coated steel material of Comparative Example 1A. Furthermore, from the results of Example 1A and Example 2A in Table 3 above, it was also found that the rate of blistering, which is an indicator of deterioration, can be reduced as the water vapor transmission amount is relatively low.

(5-2) Deterioration rate of coating film and expected life For the coated steel materials of Example 1A, Example 2A, and Comparative Example 1A, the relationship between the swollen area ratio and the acceleration test time is shown in the graph of FIG. Shown in In FIG. 1, the vertical axis indicates the swelling occurrence area ratio (%), the horizontal axis indicates the acceleration test time (h), ● indicates the result of Example 1A, ■ indicates the result of Example 2A, and ▲ These show the results of Comparative Example 1A.

  About the result of each coated steel material of the said FIG. 1, the swelling generation | occurrence | production area ratio and the acceleration test time were linearly approximated, and the inclination was calculated | required as a coating-film deterioration rate. The expected life of the coating film was calculated as a relative value with reference to the coating film deterioration rate (slope) of Comparative Example 1A. These results are shown in Table 5 below.

As shown in Table 5, the coated steel materials of Example 1A and Example 2A having a coating film with a water vapor transmission rate of 1.5 g / (m ² · 24 h) or less are compared with each other in which the water vapor transmission rate does not satisfy the above value. It was found that the expected life value of the coating film was extremely excellent as compared with Example 1A. Further, from the results of Example 1A and Example 2A, it was also found that the expected life value can be improved as the water vapor transmission amount is relatively low.

(5-3) Relationship between coating film deterioration rate and water vapor transmission rate (rust steel plate A)
A coating film was formed on the rust steel sheet A as shown in Example 3-5 and Comparative Examples 2 and 3 shown in Table 2 in the same manner as in (3). And about the coating steel materials (Example 3A, 4A, 5A, Comparative Example 2A, 3A) by which the said coating film was formed in the rust surface of the said rust steel plate A, it is the same as said (4), and water vapor permeation | transmission amount and swelling The generation area ratio was measured. Then, in the same manner as in the above (5-2), the blister occurrence area rate and the acceleration test time are linearly approximated from the blister occurrence area rate and the acceleration test time, and the inclination is obtained as the coating film deterioration rate. It was. Then, the expected life of the coating film was calculated as a relative value with reference to the coating film deterioration rate (slope) of Comparative Example 1A in Table 5 described above. These results are shown in Table 6 below together with the results of Example 1A, Example 2A and Comparative Example 1A of (5-2).

As shown in Table 6, the coated steel materials of Example 1A to Example 5A had a water vapor permeation amount of 1.5 g / (m ² · 24 h) or less in all coating films, but were comparative examples. In each of 1A to 3A, the water vapor transmission rate exceeded 1.5 g / (m ² · 24 h). And the coated steel materials of all the examples having a coating film with a water vapor transmission rate of 1.5 g / (m ² · 24 h) or less are coated in comparison with Comparative Examples 1A to 3A in which the water vapor transmission rate does not satisfy the above value. It was found that the expected lifetime value of the film was extremely excellent. Further, from the results of Example 1A to Example 5A, it was also found that the expected life value can be improved as the water vapor transmission amount is relatively low.

Further, the graph of FIG. 2 shows the relationship between the water vapor transmission amount shown in Table 6 and the slope of the linear approximation line (coating film deterioration rate). In FIG. 2, the vertical axis represents the water vapor transmission rate [g / (m ² · 24h)], and the horizontal axis represents the slope (coating film deterioration rate). Each plot of the graph of FIG. 2 shows Example 1A (●), Example 2A (■), Example 3A (▲), Example 4A (◆), from a small value to a large value of water vapor transmission. Example 5A (×), Comparative Example 2A (□), Comparative Example 1A (◯), and Comparative Example 3A (Δ).

  As shown in FIG. 2, the slope of the linear approximation line (coating film deterioration rate) and the water vapor transmission amount show a positive correlation. From this result, as described above, in the case of rust surface coating, it is not necessary to consider the long-term adhesion factor for the coating film, and the deterioration rate of the coating film has a correlation with the amount of water vapor transmission. Was found to be obtained.

  In addition, the following is presumed. That is, in the coating treatment conditions shown in Table 2 above, Example 1, Example 2, Example 5, and Comparative Example 1 all had four layers of coatings applied to the same paint set (paint X, paint Z, The top coat paint F) is used, and in the paint set, a resin having a relatively high density (a bisphenol F-type epoxy resin having a relatively low molecular weight) that forms a relatively dense film is used. In these examples, the thickness of the single layer film (second layer and third layer) using the paint Z is made larger than that of Comparative Example 1, and the total thickness of the coating film (laminated film) is increased. By making it thicker than Comparative Example 1, the blocking property is improved as compared with Comparative Example 1. On the other hand, in the case of Example 3, Example 4, Comparative Example 2, and Comparative Example 3, these use different paint sets, and each paint set has a denseness that forms a relatively non-dense film. A low resin (bisphenol A type epoxy resin having a relatively large molecular weight) is used. And also in these Examples, the total film thickness of the whole coating film (laminated film) is improved rather than the comparative example 2 and the comparative example 3 by increasing the lamination | stacking number of a single layer film. In this way, the resin set containing a highly dense resin and the resin set containing a low dense resin each have a balance between the barrier property and adhesion of the coating film formed due to the difference in the denseness. It differs between the former and the latter. For this reason, when the former resin set or the latter resin set is coated on a steel material without rust, between the water vapor transmission amount and the slope of the linear approximation line (coating film degradation rate) as shown in FIG. A positive correlation cannot be obtained. However, in the present invention, since the object to be coated is a rust surface, as described above, the adhesion factor is not affected, and therefore the deterioration of the coating film depends only on the barrier property (that is, the water vapor transmission amount). As a result, it is estimated that a positive correlation was obtained.

(5-3) Relationship between coating film deterioration rate and water vapor transmission rate (rust steel plate B)
The rust steel plate B was subjected to a coating treatment (Example 1 to Example 5) in the same manner as the rust steel plate A to obtain a coated steel plate. And about the coating film formed in the said coated steel plate, the relationship between a coating-film degradation rate (inclination) and water vapor transmission amount was confirmed similarly to said (5-3). These results are shown in Table 7 below. Further, the graph of FIG. 3 shows the relationship between the water vapor transmission amount shown in Table 7 below and the slope of the linear approximation line (coating film deterioration rate). In FIG. 3, the vertical axis represents the water vapor transmission rate [g / (m ² · 24h)], and the horizontal axis represents the slope (coating film deterioration rate).

  As shown in FIG. 3, when the rust steel plate B having a rust thickness smaller than the rust steel plate A is coated, the slope of the linear approximation line (coating film deterioration rate) and water vapor permeation are the same as the above results. There was a positive correlation with the quantity. Further, from the comparison with FIG. 2, it was found that the rust steel plate B having a small rust thickness has a slower coating film deterioration rate than the rust steel plate A having a large rust thickness.

A part or all of the above embodiments can be described as in the following supplementary notes, but is not limited to the following.
(Appendix 1)
A composition comprising a resin component and a pigment;
When the coating film is formed from the composition, the water vapor permeation amount of the coating film is 1.5 g / (m ² · 24 h) or less.
(Appendix 2)
The resin component includes a resin and a curing agent, and the resin includes an epoxy resin,
The curing agent comprises a polyamine compound;
The rust surface coating material according to supplementary note 1, wherein the pigment includes a scaly pigment.
(Appendix 3)
The paint for rust surface according to appendix 1 or 2, wherein the pigment contains at least one selected from the group consisting of talc, mica, glass flakes, and aluminum flakes.
(Appendix 4)
The rust surface coating material according to any one of appendices 1 to 3, wherein a content of the pigment in a nonvolatile content of the composition is 1 to 70% by mass.
(Appendix 5)
Including a paint film process that forms a paint film using a paint containing a resin component and a pigment on a steel material having a rust surface,
In the coating film step, the coating film is formed so that the water vapor transmission amount is 1.5 g / (m ² · 24 h) or less.
(Appendix 6)
The coating method according to appendix 5, wherein the paint for rust according to any one of appendices 1 to 4 is used as the paint.
(Appendix 7)
The coating method according to appendix 5 or 6, wherein the rust thickness of the steel material is 0.1 to 400 µm.
(Appendix 8)
The coating method according to appendix 7, wherein the rust surface of the steel material has a rust thickness of 0.1 to 300 µm.
(Appendix 9)
The coating method according to appendix 7, wherein the rust surface of the steel material has a rust thickness of 0.1 to 200 µm.
(Appendix 10)
The coating method according to appendix 7, wherein the rust surface of the steel material has a rust thickness of 0.1 to 100 µm.
(Appendix 11)
The coating method according to any one of appendices 5 to 10, wherein the rust surface of the steel material has a maximum rust thickness of 0.1 to 3000 µm.
(Appendix 12)
The coating method according to appendix 11, wherein the maximum thickness of rust is 0.1 to 2000 µm on the rust surface of the steel material.
(Appendix 13)
The coating method according to appendix 11, wherein the rust surface of the steel material has a maximum rust thickness of 0.1 to 1400 µm.
(Appendix 14)
The coating method according to appendix 11, wherein the maximum thickness of rust is 0.1 to 700 µm on the rust surface of the steel material.
(Appendix 15)
The coating method according to any one of appendices 5 to 14, wherein the coating film on the rust surface has a thickness of 50 to 1000 µm.
(Appendix 16)
The coating method according to any one of appendices 5 to 15, wherein in the coating film step, the coating material is formed by applying the coating material to the steel material and curing the coating material.
(Appendix 17)
The coating film is a laminated film,
The coating method according to appendix 16, wherein in the coating step, the coating and drying of the paint on the steel material are repeated.
(Appendix 18)
Including steel and coating,
On the rust surface of the steel material, having the coating film,
The paint film includes a resin component and a pigment, and has a water vapor transmission rate of 1.5 g / (m ² · 24 h) or less.
(Appendix 19)
The resin component includes an epoxy resin and a curing agent,
The curing agent comprises a polyamine compound;
The coated steel material according to appendix 18, wherein the pigment includes a scaly pigment.
(Appendix 20)
The coated steel material according to appendix 18 or 19, wherein the pigment includes at least one selected from the group consisting of talc, mica, glass flakes, and aluminum flakes.
(Appendix 21)
The coated steel material according to any one of appendices 18 to 20, wherein the content of the pigment in the coating film is 1 to 70 mass%.
(Appendix 22)
In the steel material, the surface in contact with the coating film has a rust surface,
The coated steel material according to any one of appendices 18 to 21, wherein the rust surface has a rust thickness of 0.1 to 400 µm.
(Appendix 23)
The coated steel material according to appendix 22, wherein the rust surface of the steel material has a rust thickness of 0.1 to 300 µm.
(Appendix 24)
The coated steel material according to appendix 22, wherein the rust surface of the steel material has a rust thickness of 0.1 to 200 µm.
(Appendix 25)
The coated steel material according to appendix 22, wherein the rust surface of the steel material has a rust thickness of 0.1 to 100 µm.
(Appendix 26)
The coated steel material according to any one of appendices 18 to 25, wherein the maximum thickness of rust is 0.1 to 3000 µm on the rust surface of the steel material.
(Appendix 27)
27. The coated steel material according to appendix 26, wherein the rust surface of the steel material has a maximum rust thickness of 0.1 to 2000 μm.
(Appendix 28)
27. The coated steel material according to appendix 26, wherein the maximum thickness of rust is 0.1 to 1400 μm on the rust surface of the steel material.
(Appendix 29)
27. The coated steel material according to appendix 26, wherein the maximum thickness of rust is 0.1 to 700 μm on the rust surface of the steel material.
(Appendix 30)
30. The coated steel material according to any one of appendices 18 to 29, wherein the thickness of the coating film is 50 to 1000 μm.

  Although the present invention has been described with reference to the exemplary embodiments and examples, the present invention is not limited to the above exemplary embodiments and examples. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

According to the present invention, by setting the water vapor permeation amount of the coating film to 1.5 g / (m ² · 24 h) or less, for example, even if the formation target of the coating film is a rust surface of a steel material, Swelling and cracking of the film, and rusting on the coated surface of the coating film in the steel material can be suppressed for a long period of time. For this reason, for example, even if it is a case where the rust which generate | occur | produced in the said steel materials cannot be removed, this invention is applicable to such a steel material.

Claims (13)

For the steel having a rust surface rust occurs, includes a coating step of forming a coating film on the rust surface using a coating material containing a resin component and a pigment,
The thickness of the rust on the rust surface is 0.1 to 400 μm,
The said coating film process WHEREIN: The said coating film is formed so that water vapor permeation amount may be 0.5-1.5 g / (m < ² > * 24h ) , The coating method to the rust surface steel material characterized by the above-mentioned. Water vapor transmission rate is 0.8 to 1.5 g / (m ² The coating method according to claim 1, wherein the coating film is formed so as to be 24 h). The coating method of Claim 1 or 2 whose film thickness of the coating film on the said rust surface is 50-1000 micrometers. The coating method according to any one of claims 1 to 3 , wherein in the coating step, the coating is applied to the steel material and cured to form a coating. The coating film is a laminated film,
The coating method according to claim 4 , wherein in the coating step, the coating and drying of the paint on the steel material are repeated. The resin component includes a resin and a curing agent,
The resin includes an epoxy resin;
The curing agent comprises a polyamine compound;
The coating method according to any one of claims 1 to 5, wherein the pigment includes a scaly pigment. The coating method according to any one of claims 1 to 6, wherein the pigment includes at least one selected from the group consisting of talc, mica, glass flakes, and aluminum flakes. Including steel and coating,
On the rust surface where the rust of the steel material has occurred , the coating film is provided,
The thickness of the rust on the rust surface is 0.1 to 400 μm,
The coating film includes a resin component and a pigment, and has a water vapor transmission rate of 0.5 to 1.5 g / (m ² · 24h ) . Water vapor transmission rate is 0.8 to 1.5 g / (m ² The painted steel material according to claim 8, which is 24h). The resin component includes an epoxy resin and a curing agent,
The curing agent comprises a polyamine compound;
The coated steel material according to claim 8 or 9, wherein the pigment includes a scaly pigment. The coated steel material according to any one of claims 8 to 10, wherein the pigment includes at least one selected from the group consisting of talc, mica, glass flakes, and aluminum flakes. The coated steel material according to any one of claims 8 to 11 , wherein a content of the pigment in the coating film is 1 to 70 mass%. The coated steel material according to any one of claims 8 to 12 , wherein the coating film has a thickness of 50 to 1000 µm.

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