JP6945030B1 - Paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition capable of forming a coating film having excellent environmental barrier property without impairing the appearance of a topcoat coating film. A coating composition containing a resin, a scaly pigment and a pigment dispersant, wherein the content of the scaly pigment in the non-volatile content of the coating composition is 10 to 50% by mass, and the coating composition. When the coating film is formed on the substrate, the average inclination angle of the scaly pigment in the coating film with respect to the substrate surface is 12.5 ° or less, and the scaly pigment is filled in the coating film. It is a coating composition characterized by having a ratio of 40 to 95 area% or more. [Selection diagram] None

Description

The present invention relates to a coating composition, and more particularly to a coating composition capable of forming a coating film having excellent environmental barrier properties without impairing the appearance of the topcoat coating film.

It is widely known that a scaly pigment is blended in a coating film for the purpose of improving the environmental barrier property of the coating film in order to suppress the invasion of deterioration factors of the base material from the outside. The scaly pigment can exert the effect of suppressing the invasion of corrosive factors of the metal such as water, oxygen, and chloride ions, and can suppress the generation of rust on the metal.

Japanese Patent Application Laid-Open No. 2000-129168 (Patent Document 1) aims to provide an anticorrosion coating composition capable of forming an anticorrosion coating film having excellent adhesion to a metal substrate, corrosion resistance and coating strength. , (A) Non-tar epoxy resin, (b) Hardener, (c) Epoxy group-containing alkoxysilane compound, (d) Weight average flake diameter of 20 μm or more, and weight average aspect ratio of 20 or more. Described is an anticorrosion coating composition comprising a flat pigment and (e) at least one extender pigment selected from the group consisting of talc, silica, barium sulfate and potash epoxies.

Japanese Unexamined Patent Publication No. 2018-53028 (Patent Document 2) is for a conventional undercoat paint which tends to be inferior in chemical resistance of the obtained undercoat coating film as compared with an organic solvent-based coating composition, although it is excellent in corrosion resistance. An undercoat coating material containing an epoxy resin and an amine resin, with the aim of solving the problems of the water-based coating composition and providing a two-component reaction-curable coating composition for an undercoat coating that provides an undercoat coating film having excellent chemical resistance. A two-component reaction-curable water-based coating composition for use, wherein the weight ratio of the epoxy resin having an epoxy equivalent of 400 to 1000 g / eq and the epoxy resin having an epoxy equivalent of 150 to 300 g / eq is 90: 10 to 60 in the epoxy resin. A coating composition of: 40 is described, wherein the scaly inorganic powder having an aspect ratio of 2 to 1000 is further contained, and the content of the scaly inorganic powder in the non-volatile content contained in the coating composition is 10. It is stated that a coating composition having an amount of about 40% by weight is preferable.

Further, Japanese Patent Application Laid-Open No. 2018-90830 (Patent Document 3) appropriately adjusts the ratio and shape of the pigment in the non-volatile component to set the coefficient of linear expansion at a temperature equal to or lower than the glass transition temperature of the non-volatile component in a specific range. It is described that a coating composition having excellent durability and capable of forming a coating film suitable for repair can be provided by reducing the temperature to the above, but it is described that a scaly pigment is preferable from the viewpoint of corrosion resistance. doing.

Japanese Unexamined Patent Publication No. 2000-129168 JP-A-2018-53028 JP-A-2018-90830

Since the scaly pigment can exert the effect of suppressing the invasion of corrosive factors, it is expected that the environmental barrier property is further improved by increasing the amount of the scaly pigment contained in the coating film. When the present inventor examined a coating composition having a high blending amount of a scaly pigment, an additional coating film (top coating film) was formed on the coating film (undercoat coating film) formed from the coating composition. In this case, it was found that there is a problem that the appearance of the topcoat coating film, particularly the gloss of the topcoat coating film, is deteriorated. Since a coating composition having excellent environmental barrier properties is often used as an undercoat when coating a metal surface, it is not desirable to deteriorate the appearance of the coating film applied on the coating composition.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a coating composition capable of forming a coating film having excellent environmental barrier properties without impairing the appearance of the topcoat coating film.

When the present inventor examined a coating composition having a high amount of scaly pigment, increasing the amount of scaly pigment causes significant thickening, which tends to cause a problem in the appearance of the topcoat film. It turned out to be in. In particular, the problem was remarkable when a scaly pigment having a high aspect ratio was used. Therefore, when the secondary electron image of the cross-sectional surface of the coating film was observed with a scanning electron microscope (SEM), the scaly pigment had a large inclination in the undercoat coating film that caused the appearance of the topcoat coating film to deteriorate, and the surface of the undercoat coating film had a large inclination. It was found that the smoothness was impaired and that many voids were formed inside the undercoat film.

As a result of further studies, the present inventor has specified the average inclination angle of the scaly pigment in the coating film formed from the coating composition even if the coating composition contains a large amount of the scaly pigment. The present invention has been found that a coating film having excellent environmental barrier properties can be formed without impairing the appearance of the topcoat coating film by reducing the amount to the above range and increasing the filling rate of the scaly pigment to a specific range. It came to be completed.

That is, the coating composition of the present invention is a coating composition containing a resin, a scaly pigment and a pigment dispersant, and the content of the scaly pigment in the non-volatile content of the coating composition is 10 to 50% by mass. When a coating film is formed on a substrate from the coating composition, the average inclination angle of the scaly pigment in the coating film with respect to the substrate surface is 12.5 ° or less, and the coating film has The filling rate of the scaly pigment in the above is 40 to 95 area%.

In a preferred example of the coating composition of the present invention, the scaly pigment has an aspect ratio of 30 to 100.

In another preferred example of the coating composition of the present invention, the scaly pigment has an average particle size of 10 to 100 μm.

In another preferred example of the coating composition of the present invention, the scaly pigment is mica, glass flakes or aluminum flakes.

In another preferred example of the coating composition of the present invention, the pigment dispersant has an acid value of 10 to 150 mgKOH / g.

According to the present invention, it is possible to provide a coating composition capable of forming a coating film having excellent environmental barrier properties without impairing the appearance of the topcoat coating film.

The coating composition of the present invention will be described in detail below. The coating composition of the present invention is a coating composition containing a resin, a scaly pigment and a pigment dispersant, and the content of the scaly pigment in the non-volatile content of the coating composition is 10 to 50% by mass. When a coating film is formed on a substrate from the coating composition, the average inclination angle of the scaly pigment in the coating film with respect to the substrate surface is 12.5 ° or less, and the scales in the coating film. It is characterized in that the filling rate of the state pigment is 40 to 95 area%.

In the coating composition of the present invention, the non-volatile component refers to a component excluding volatile components such as water and an organic solvent, and is a component that finally forms a coating film. The coating composition of the present invention has a high content of scaly pigment in the non-volatile content, which is 10 to 50% by mass.
In this specification, the components remaining when the coating composition is dried at 105 ° C. for 60 minutes are treated as non-volatile components.

The coating composition of the present invention is a coating composition having a high content of the scaly pigment in the non-volatile content as described above from the viewpoint of improving the environmental barrier property, but the inclination angle of the scaly pigment in the coating film By controlling the average and the filling rate of the scaly pigment in the coating film, it is possible to suppress a decrease in the appearance of the topcoat coating film, particularly the gloss of the coating film.
In the present specification, the environmental blocking property means that the metal is corroded by blocking components such as water, oxygen, and chloride ions that are present in the environment to which the structure is exposed and are corrosive to the metal. It means the function of suppressing.

Specifically, in the coating composition of the present invention, when a coating film is formed on a substrate from the coating composition, the average inclination angle of the scaly pigment in the coating film with respect to the substrate surface is 12.5. ° or less, preferably 12.0 ° or less, and even more preferably 11.0 ° or less. By lowering the average value of the inclination angles, the effect of suppressing the deterioration of the appearance of the topcoat coating film is improved, and the environmental barrier property can be further improved. The maximum value of the inclination angle is 90 °, and the minimum value is 0 °. It means that the scaly pigment having an inclination angle of 90 ° exists perpendicular to the surface of the substrate, and the scaly pigment having an inclination angle of 0 ° exists parallel to the surface of the substrate.

In the present specification, the "tilt angle of the scaly pigment in the coating film with respect to the surface of the substrate" can be obtained by acquiring a cross-sectional image of the coating film formed on the substrate. In the present specification, the inclination of the scaly pigment is represented by a straight line indicating the maximum distance in the cross-sectional image of the scaly pigment, and the angle of the straight line with respect to the substrate surface is defined as "the inclination of the scaly pigment in the coating film with respect to the substrate surface". Angle ". Further, in the present specification, the average of the inclination angles is obtained for all of the scaly pigments appearing in the cross-sectional image of the coating film acquired by the scanning electron microscope (SEM). A specific measurement method will be described below, but for example, the method described in Japanese Patent No. 4387165 can be used.

Further, in the coating composition of the present invention, when a coating film is formed on a substrate from the coating composition, the filling rate of the scaly pigment in the coating film is 40 to 95 area%, and 60 to 95. The area is preferably%, and more preferably 70 to 95 area%. When the filling rate of the scaly pigment is high, the scaly pigment is densely present in the coating film and the number of voids is reduced. Can be made to.

In the present specification, the "filling ratio of the scaly pigment in the coating film" is a scaly shape occupying the cross section of the coating film (however, if the coating film has voids, the cross section of the coating film and the voids combined). It refers to the proportion of pigment and can be obtained by acquiring a cross-sectional image of a coating film formed on a substrate.
Specifically, "filling ratio of scaly pigment in the coating film (area%)" = "area of the portion where the scaly pigment appears in the cross-sectional image of the coating film" ÷ "coating reflected in the cross-sectional image of the coating film" The "filling rate of the scaly pigment in the coating film" can be obtained from the relational expression of "area of the film cross section (including voids in the coating film)" x 100.
Further, as a method of measuring "the area of the portion where the scaly pigment appears in the cross-sectional image of the coating film", the scaly pigments appearing in the cross-sectional image of the coating film are manually painted one by one to obtain the total area. There are methods, but this method is not efficient. Therefore, in the present specification, first, an apparatus capable of element mapping analysis such as a scanning electron microscope / energy dispersive X-ray spectroscope (SEM / EDX) or an electron probe microanalyzer (EPMA) is used. The area where the elements characteristic of the scaly pigment (Al for mica, Mg for talc, etc.) exists in the cross section of the coating film is extracted and obtained, and from the image, "the scaly pigment shown in the cross section image of the coating film exists. Find the area of the part to be used.

In the present specification, specific measurement methods of "the average inclination angle of the scaly pigment in the coating film with respect to the surface of the substrate" and "the filling rate of the scaly pigment in the coating film" are as follows.
(1) Formation of coating film The substrate can be coated by a conventional method to form a coating film for measurement. In the present specification, each liquid of the poly (2) liquid type paint is stirred to make a uniform liquid, and then the paint viscosity is adjusted by using a diluent suitable for each paint. The adjusted paint is applied by spray coating (air spray coating), and the coating film after coating is sufficiently dried to prepare a coating film for measurement. The coating film thickness can be any film thickness suitable for each coating material.
(2) Acquisition of cross-sectional image of the coating film A cross-sectional image of the coating film can be acquired by using a secondary electron image obtained by a scanning electron microscope (SEM). In the present specification, as a pretreatment, the coating film is first embedded in an epoxy resin and fixed, and then the cross section of the coating film is exposed and smoothed using a polishing machine, and then a carbon vapor deposition treatment is performed. .. A cross-sectional image of the coating film is obtained by using a scanning electron microscope (SEM) on the sample subjected to this pretreatment (observation magnification x 1000, coating film width of about 150 μm).
* Carbon vapor deposition treatment: In the case of an insulator sample, a charge-up phenomenon occurs during SEM observation, which makes it impossible to observe clearly. To avoid this, before forming a thin carbon (conductive) film on the sample surface. Means processing.
* For SEM, SU-70 manufactured by Hitachi High-Technologies Corporation was used.
(3) Method for measuring the average inclination angle of the scaly pigment in the coating film with respect to the substrate surface All of the scaly pigments shown in the cross-sectional image of the coating film (observation magnification x1000, coating film width about 150 μm) acquired by SEM. , Measure the slope using image processing software and calculate the average value.
(4) Method for measuring the filling rate of scaly pigment in the coating film A cross-sectional image (secondary) of the coating film of the sample subjected to the pretreatment described in (2) above using an electron probe microanalyzer (EPMA). Acquire an electron image, an observation magnification x1000, and a coating film width of about 150 μm) and perform element mapping analysis. (For example, in the case of mica, Al can be selected, and in the case of talc, Mg can be selected as the element to be mapped. The element can be arbitrarily selected according to the sample.)
Next, using image processing software, the "area of the cross-sectional area of the coating film (including the voids in the coating film) reflected in the cross-sectional image of the coating film" is obtained from the secondary electron image. In addition, the "area of the portion where the scaly pigment appears in the cross-sectional image of the coating film" is obtained from the element mapping diagram. Then, "filling ratio of scaly pigment in the coating film (area%)" = "area of the portion where the scaly pigment appears in the cross-sectional image of the coating film" ÷ "the cross-sectional area of the coating film reflected in the cross-sectional image of the coating film". The "filling rate of the scaly pigment in the coating film" is obtained from the relational expression of "area (including voids in the coating film)" x 100.
* For EPMA, EPMA-1720 manufactured by Shimadzu Corporation was used.
* It is necessary that the image acquisition position and the element mapping analysis position of the cross section of the coating film are the same.
* The "area of the part where the scaly pigment appears in the cross-sectional image of the coating film" obtained from the element mapping diagram is the actual "area of the part where the scaly pigment appears in the cross-sectional image of the coating film". Must represent. Therefore, a device capable of element mapping analysis such as a scanning electron microscope / energy dispersive X-ray spectrometer (SEM / EDX) or an electron probe microanalyzer (EPMA) has spatial resolution (point of acquiring element information). Fineness) needs to be appropriately high, and measurement conditions (integration frequency) also need to be set appropriately.

In the coating composition of the present invention, the dispersibility of the scaly pigment is improved by appropriately selecting the pigment dispersant, and even if the coating composition has a high content of the scaly pigment, the scales in the coating film. It is possible to reduce the average inclination angle of the pigment with respect to the surface of the substrate and increase the filling rate of the scaly pigment in the coating film. In particular, it is preferable to use a pigment dispersant having an acidic adsorbent and an acid value of 10 to 150 mgKOH / g, and by blending the pigment dispersant, the orientation of the scaly pigment can be improved. can. In addition, it is also effective to reduce the tilt angle and increase the filling rate by appropriately selecting the surface treatment, shape, leafing / non-leafing of the scaly pigment, the ratio of the non-volatile component in the coating composition, the leveling agent, and the like. ..

The coating composition of the present invention contains a resin. Examples of the resin include resins usually used in the coating industry. Specifically, acrylic resin, silicone resin, acrylic silicone resin, styrene-acrylic copolymer resin, polyester resin, fluorine resin, rosin resin, and the like. Petroleum resin, kumaron resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic hydrocarbon resin, butyral resin, maleic acid resin, fumaric acid resin, vinyl resin, Examples include amine resin and ketimine resin. These resins may be used alone or in combination of two or more.

In the coating composition of the present invention, the content of the resin in the non-volatile content is preferably, for example, 15 to 50% by mass.

The resin used in the coating composition of the present invention preferably contains a modified resin. By using the modified resin, the dispersion stability of the pigment can be improved. Specific examples of the modified resin include alkyl modification, alkyl ether modification, alkylphenol novolac modification, acrylic modification, fatty acid modification, urethane modification, amino modification, isocyanate modification, silicone modification, and other modifications such as graft modification using an allyl group. Examples thereof include resins (preferably epoxy resins, resins containing hydroxyl groups, etc.). Here, examples of the resin containing a hydroxyl group include a hydroxyl group-containing acrylic resin, a hydroxyl group-containing acrylic silicone resin, and a hydroxyl group-containing fluorine resin.

In the coating composition of the present invention, the content of the modified resin in the non-volatile content is preferably, for example, 1 to 15% by mass.

The coating composition of the present invention may contain a curing agent. As the curing agent, a curing agent that is appropriately selected according to the type of resin to be used and is usually used in the coating industry can be used. These curing agents may be used alone or in combination of two or more. The content of the curing agent is appropriately adjusted according to the amount of reactive groups with the curing agent contained in the resin, but in the coating composition of the present invention, the content of the curing agent in the non-volatile content is For example, it is preferably 1 to 15% by mass.

For example, an isocyanate-based curing agent can be preferably used for a resin containing a hydroxyl group. Specific examples include toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), methylcyclohexanediisocyanate, bis (isocyanatemethyl) cyclohexane, isophorone diisocyanate, In addition to diisocyanate diisocyanate and lysine diisocyanate, modified products of these polyisocyanates can be mentioned. Specific examples of the modified product include a biuret modified product, an isocyanurate modified product, an adduct modified product (for example, a trimethylolpropane adduct), an allophanate modified product, and a uretdione modified product.
Further, for the epoxy resin, an amine-based curing agent can be preferably used. Specific examples include aliphatic groups such as ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, triaminopropane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, isophoronediamine, and 1,3-bisaminomethylcyclohexane. Polyamines; aromatic polyamines such as phenylenediamine, metaxylylene diamine, paraxylylene diamine, and diaminodiphenylmethane; other polyamines such as polyoxyethylenediamine, polyoxypropylenediamine, triethyleneglycoldiamine, and tripropyleneglycoldiamine. Examples thereof include compounds and modified polyamine compounds obtained by modifying the amino groups of these amine compounds. A known method can be used for the modification of the amine compound, and examples of the modification reaction include amidation of an amino group, a Mannich reaction of an amino group and a carbonyl compound, and an addition reaction of an amino group and an epoxy group. Be done. Here, a modified polyamine compound of the type in which an epoxy group or the like is added to an amino group is referred to as an adduct-type modified polyamine compound, and an epoxy adduct-type modified polyamine compound in which an epoxy group is added to an amino group is preferable.

The coating composition of the present invention contains a scaly pigment. The scaly pigment is a pigment having a thin and flat shape like a foil, and specific examples thereof include metal pigments such as zinc, nickel, chromium, tin, copper, silver, platinum, gold, and aluminum, and glass flakes. , Tarku, mica, kaolin clay, mica-like iron oxide and the like. The metal pigment also includes an alloy pigment such as stainless steel. Further, the scaly pigment, for example, talc or mica, may be surface-treated with a metal oxide such as titanium oxide. In particular, aluminum (aluminum flakes), glass flakes, and mica have a relatively high aspect ratio, and are therefore suitable as scaly pigments for the purpose of improving environmental barrier properties. Among them, mica is more suitable. It is preferable, and one kind may be used alone, or two or more kinds including other pigments may be used in combination.

The scaly pigment preferably has an aspect ratio of 30 to 100, and more preferably 50 to 100, from the viewpoint of improving the environmental barrier property.
In the present specification, the aspect ratio of the scaly pigment means the ratio (D / T) of the average particle size (D) and the average thickness (T) of the scaly pigment. Here, the average particle size refers to a 50% particle size (D ₅₀ ) of the volume-based particle size distribution, and is obtained from the particle size distribution measured using a laser diffraction / scattering type particle size distribution measuring device. The particle size of the scaly pigment is represented by a sphere-equivalent diameter obtained by a laser diffraction / scattering method. Further, in the present specification, the average thickness means the average value of 100 or more scaly pigments measured by using an SEM (scanning electron microscope).

The scaly pigment preferably has an average particle size of 10 to 100 μm, and more preferably 20 to 60 μm. If the average particle size of the scaly pigment is too large, the orientation in the coating film is lowered, so that the inclination of the scaly pigment is increased and the filling rate is lowered. Therefore, the average particle size of the scaly pigment is specified above. It is preferable that the range is as high as possible.
In the present specification, the average particle diameter of the scaly pigment, as described above, refers to the 50% particle diameter on a volume basis particle size distribution (D _50), is measured using a laser diffraction / scattering particle size distribution measuring apparatus Obtained from the particle size distribution. The particle size of the scaly pigment is represented by a sphere-equivalent diameter obtained by a laser diffraction / scattering method.

In the coating composition of the present invention, the content of the scaly pigment in the non-volatile content is preferably 10 to 50% by mass, more preferably 20 to 50% by mass, from the viewpoint of improving the environmental barrier property. preferable.

The coating composition of the present invention contains a pigment dispersant. In general, a pigment dispersant is adsorbed on the surface of a pigment to increase the wettability of the pigment and promote the dispersibility of the pigment.
The pigment dispersant used in the coating composition of the present invention is preferably a dispersant having an acidic adsorbing group such as a carboxy group.
The pigment dispersant used in the coating composition of the present invention preferably has a weight average molecular weight of 1,000 to 100,000. In the present specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC), polystyrene is used as a standard substance, and tetrahydrofuran is used as a mobile phase.

The acid value of the pigment dispersant is preferably 10 to 150 mgKOH / g, more preferably 30 to 150 mgKOH / g. When the acid value is 10 mgKOH / g or more, the dispersibility of the scaly pigment can be improved, and the decrease in gloss of the topcoat coating film formed on the coating film formed from the coating composition can be suppressed. In addition, the acid value can be measured by an acid-base titration method using a basic substance.

As the pigment dispersant, for example, a commercially available product can be used, and examples thereof include Big Chemie's product name: DISPERBYK and Kyoei's product name: Floren. These pigment dispersants may be used alone or in combination of two or more.

In the coating composition of the present invention, the content of the pigment dispersant in the non-volatile content is preferably, for example, 0.25 to 6.0% by mass, and further preferably 1.5 to 6.0% by mass. preferable.

In the coating composition of the present invention, the non-volatile content is preferably 50 to 90% by mass, more preferably 65 to 80% by mass.

The coating composition of the present invention may contain a solvent. As the solvent, an organic solvent, water or a mixed solvent thereof can be used. Here, the organic solvent is not particularly limited, and various organic solvents such as a hydrocarbon solvent, an alcohol solvent, a ketone solvent, an ester solvent, and an ether solvent can be used. The organic solvent may be used alone or in combination of two or more.

Examples of the hydrocarbon solvent include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and more specifically, toluene, xylene, solvent naphtha, mineral spirit, hexane, cyclohexane, and octane. , Solvent oil and the like can be exemplified. Examples of the alcohol solvent include methanol, ethanol, butanol and the like, examples of the ketone solvent include acetone, methyl ethyl ketone and methyl isobutyl ketone, and examples of the ester solvent include ethyl acetate. , Butyl acetate and the like, and examples of the ether solvent include ethylene glycol monoethyl ether and methyl carbitol. Solvents having both hydroxyl groups and ether bonds, such as ethylene glycol monoethyl ether and methyl carbitol, are classified as ether solvents as described above.

In the coating composition of the present invention, the content of the solvent is preferably 10 to 50% by mass, more preferably 20 to 35% by mass.

The coating composition of the present invention preferably contains a weak solvent as a solvent. In the coating composition of the present invention, as the weak solvent, a mixed aniline point specified in JIS K 2256 or a weak solvent having an aniline point in the range of 12 to 70 ° C. is preferable. Such a weak solvent is a solvent having a relatively small load on the environment and can be removed by drying at room temperature. The aniline point and the mixed aniline point are one of the indexes showing the dissolving power of the solvent, and the higher the aniline point or the mixed aniline point, the weaker the dissolving power. The aniline point is the lowest temperature at which an equal volume of solvent and aniline exist as a uniform solution, and the mixed aniline point is the lowest temperature at which one volume of solvent, one volume of heptane and two volumes of aniline exist as a uniform solution. ..

Examples of the weak solvent include hydrocarbon-based organic solvents such as aliphatic solvents, naphthen-based solvents, and aromatic naphtha. Among these, among these, a suitable weak solvent having less odor and less adverse effect on the environment is used. , Aliphatic hydrocarbon-based organic solvent can be mentioned. Specific examples of the above hydrocarbon-based organic solvent include methylcyclohexane (aniline point: 40 ° C.), ethylcyclohexane (aniline point: 44 ° C.), mineral spirit (aniline point: 56 ° C.), and turpentine oil (aniline point: 44 ° C.). Can be mentioned. In addition, some of the above-mentioned hydrocarbon-based organic solvents are commercially available as petroleum-based hydrocarbons, and for example, HAWS (manufactured by Shell Chemicals Japan, aniline point: 17 ° C.), LAWS (manufactured by Shell Chemicals Japan, aniline point). : 44 ° C), Pegazol 3040 (ExxonMobil, aniline point: 55 ° C), Pegazol AN45 (ExxonMobil, aniline point 42 ° C), A solvent (JX Nikko Nisseki Energy Co., Ltd., aniline point: 45 ° C) ), Clensol HS (manufactured by JX Nikko Nisseki Energy Co., Ltd., aniline point: 64 ° C), Mineral Spirit A (manufactured by JX Nikko Nisseki Energy Co., Ltd., aniline point: 43 ° C), Exxon D30 (manufactured by ExxonMobil, aniline point:) 64 ° C), Exxon D40 (ExxonMobil, aniline point: 69 ° C), Newsol DX High Soft (JX Nikko Nisseki Energy Co., Ltd., aniline point: 68 ° C), Solbesso 100 (ExxonMobil, mixed aniline point) : 14 ° C), Solbesso 150 (ExxonMobil, mixed aniline point: 18.3 ° C), Swazole 1000 (Maruzen Petrochemical, mixed aniline point: 12.7 ° C), Swazole 1500 (Maruzen Petrochemical) , Mixed aniline point: 16.5 ° C), Swazole 1800 (manufactured by Maruzen Petrochemical Co., Ltd., mixed aniline point: 15.7 ° C), Idemitsu Ipsol 100 (manufactured by Idemitsu Kosan Co., Ltd., mixed aniline point: 13.5 ° C), Idemitsu Ipsol 150 (manufactured by Idemitsu Kosan Co., Ltd., mixed aniline point: 15.2 ° C.) and the like can be mentioned. These weak solvents may be used alone or in combination of two or more.

In the coating composition of the present invention, the ratio of the weak solvent to the solvent is preferably 50% by mass or more, and the upper limit thereof is 100% by mass.

In the coating composition of the present invention, as other components, pigments other than scaly pigments, desiccants, antioxidants, reaction catalysts, antifoaming agents, dehydrating agents, leveling agents, antisettling agents, antiseptics, silanes Adhesion-imparting agents such as coupling agents, algae-proofing agents, fungicides, preservatives, ultraviolet absorbers, light stabilizers and the like may be appropriately added as necessary. Commercially available products can be preferably used as these components.

The pigments other than the scaly pigments are not particularly limited, and examples thereof include color pigments, rust preventive pigments, and extender pigments generally used in the paint industry. Specific examples of coloring pigments, rust preventive pigments, and extender pigments include titanium oxide, red iron oxide, yellow iron oxide, carbon black, aluminum tripolyphosphate, zinc phosphate, condensed aluminum phosphate, barium metaborate, calcium carbonate, and sulfuric acid. Inorganic pigments such as barium, kaolin, talc, clay, mica, alumina, myoban, white clay, magnesium hydroxide, and magnesium oxide, phthalocyanine blue, phthalocyanine green, naphthol red, quinacridone red, benzimidazolone yellow, Hansa yellow, benz Examples thereof include organic pigments such as imidazolone orange and dioxazine violet. The pigment may be used alone or in combination of two or more.

The coating composition of the present invention can be prepared by mixing various components appropriately selected as necessary. When the coating composition of the present invention is a two-component coating composition, a main agent and a curing agent are prepared in advance by mixing various components appropriately selected as necessary for coating. Sometimes used by mixing the main agent and the curing agent. The curing agent may be the curing agent as it is, or may be a mixture with other components.

The coating composition of the present invention has a shear rate of 0.1 s ^{-1 and} a viscosity of 0.1 to 10,000 Pa · s and a shear rate of 1,000 s when the non-volatile content is 70% by mass. ^{The viscosity of -1} is preferably 0.05 to 10 Pa · s. In the present specification, the viscosity is measured using a rheometer (such as a rheometer ARES manufactured by TA Instruments) after adjusting the liquid temperature to 25 ° C.

The coating composition of the present invention preferably has a thixotropic index (TI) value of 2.0 to 5.0 when the non-volatile content is 70% by mass. In the present specification, the TI value is a value of the viscosity at the shear rate of 1.0 s ^-1 and 25 ° C. with ^{respect to the viscosity at the shear rate of 0.1 s -1 and 25 ° C.}

In the coating composition of the present invention, the oxygen permeability of the coating film formed from the coating composition ^{is preferably 3,500 cc · μm / m 2} / day or less. In the present specification, the oxygen permeability is measured by the isobaric method (Mocon method) using an oxygen permeability measuring device (for example, 8001 manufactured by Illinois). Specifically, the coating film (single film) is fixed in the diffusion chamber in the apparatus, and the moving speed (OTR) of oxygen permeating the coating film is detected. A standard film with known transmittance is used to calibrate the detector.

The coating composition of the present invention is suitable as a coating composition for undercoating because it is a coating composition capable of forming a coating film having excellent environmental barrier properties without impairing the appearance of the topcoat coating film.

The coating means of the coating composition of the present invention is not particularly limited, and known coating means such as spray coating, roller coating, brush coating, iron coating, spatula coating and the like can be used. Further, the drying means of the coating composition of the present invention is not particularly limited, and may be either natural drying at an ambient temperature or forced drying using a dryer or the like.

In the coating composition of the present invention, the film thickness of the coating film formed from the coating composition is preferably 30 to 300 μm.

The base material that can be coated by the coating composition of the present invention is not particularly limited, but is limited to steel, zinc-plated steel (for example, totan plate), tin-plated steel (for example, tin plate), stainless steel, magnesium alloy, and aluminum. , A metal-based base material containing at least a part of a metal such as an aluminum alloy or an alloy can be preferably mentioned. Specific examples thereof are preferably steel materials such as steel plates, steel pipes and strips, and steel structures such as steel towers, bridge facilities and plants.
The surface of the base material may be subjected to a primer treatment such as anticorrosion treatment, or at least a part of the surface of the base material may already be on the base material when the old coating film (when coating with the coating composition of the present invention is applied). The coating film formed on the surface of the coating film) may be present.

When a topcoat coating is further formed on the coating film formed from the coating composition of the present invention, the topcoat coating usually contains a resin, and specific examples thereof include an acrylic resin, a silicone resin, and an acrylic silicone resin. , Styrene acrylic copolymer resin, polyester resin, fluorine resin, rosin resin, petroleum resin, kumaron resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic hydrocarbon Examples thereof include resins, butyral resins, maleic acid resins, fumaric acid resins, vinyl resins, amine resins, and ketimine resins. These resins may be used alone or in combination of two or more.

Various conventionally known paints such as an organic solvent-based paint using an organic solvent as a main solvent, a water-based paint using water as a main solvent, and an active energy ray-curable paint can be used for forming the top coat. Topcoat paints include solvents, hardeners, colorants, wetting agents, dispersants, desiccants, antioxidants, reaction catalysts, defoamers, dehydrating agents, leveling agents, anti-settling agents, and sagging agents as components other than resins. Adhesion-imparting agents such as stoppers and silane coupling agents, algae-proofing agents, antifungal agents, preservatives, ultraviolet absorbers, light stabilizers and the like may be blended as necessary. The topcoat paint can be prepared by mixing various components appropriately selected as necessary.

As a method for applying the top coat, known coating means such as brush coating, roller coating, iron coating, spatula coating, and spray coating can be used. The means for drying the topcoat paint is not particularly limited, and may be either natural drying at an ambient temperature or forced drying using a dryer or the like.

The film thickness of the topcoat coating film is preferably 10 to 100 μm.

The topcoat paint preferably has a mirror gloss (60 °) of 70 or more. In the present specification, the mirror glossiness (60 °) is a value measured according to JIS K5659.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

1. 1. Materials used The following materials were used to prepare the paint composition.
[Main agent]
(1) Resin / Modified Epoxy Resin (manufactured by DIC Corporation, EPICRON 5920-70MS, non-volatile content 70% by mass)
(2) Rust-preventive pigment / phosphoric acid compound (manufactured by Teika Co., Ltd., K-WHITE # 82, average particle size: 3.5 μm, aspect ratio: less than 30)
(3) Pigment / talc (manufactured by Fuji Tarku Kogyo Co., Ltd., talc PK-50, average particle size 14 μm, aspect ratio: less than 30)
-Titanium oxide (manufactured by Sakai Chemical Industry Co., Ltd., TITONE R-5N, average particle size 0.3 μm, aspect ratio: less than 30)
-Mica G (average particle size 30 μm, aspect ratio 25)
(4) Scale pigment, mica A (average particle size 15 μm, aspect ratio 70)
-Mica B (average particle size 23 μm, aspect ratio 70)
-Mica C (average particle size 75 μm, aspect ratio 70)
-Mica D (average particle size 30 μm, aspect ratio 32)
・ Mica E (average particle size 8 μm, aspect ratio 70)
-Mica F (average particle size 110 μm, aspect ratio 70)
-Glass flakes (average particle size 15 μm, aspect ratio 70)
-Aluminum flakes (average particle size 15 μm, aspect ratio 70)
(5) Additive / Pigment Dispersant A (manufactured by Kyoeisha Chemical Co., Ltd., Floren G-100SF, adsorbent group: unsaturated polycarboxylic acid group, acid value: 135 mgKOH / g)
-Pigment Dispersant B (manufactured by Big Chemie Japan Co., Ltd., DISPERBYK-118, adsorbent group: highly polar pigment affinity group, acid value: 36 mgKOH / g)
-Pigment Dispersant C (manufactured by Big Chemie Japan Co., Ltd., DISPERBYK-102, adsorbent group: phosphoric acid group, acid value: 101 mgKOH / g)
-Pigment dispersant D (manufactured by Kyoeisha Chemical Co., Ltd., Floren DOPA-15B, adsorbent group: cationic group, amine value: 10 mgKOH / g)
-Pigment Dispersant E (manufactured by Big Chemie Japan Co., Ltd., DISPERBYK-2155, adsorbent group: amine, amine value: 48 mgKOH / g)
・ Viscosity adjuster (manufactured by Kusumoto Kasei Co., Ltd., Disparon D6820-20M, non-volatile content 20% by mass)
・ Defoamer (manufactured by Kyoeisha Chemical Co., Ltd., Floren AC-901, non-volatile content 22% by mass)
(6) Solvent / Petroleum hydrocarbon solvent (manufactured by ExxonMobil, Solbesso 100, mixed aniline point: 14 ° C)
[Curing agent]
(1) Hardener / resin (manufactured by T & K TOKA Co., Ltd., tomide TXP-696, polyamide amine compound, non-volatile content 82% by mass)
(2) Solvent / Petroleum hydrocarbon solvent (manufactured by ExxonMobil, Solbesso 100, mixed aniline point: 14 ° C)
・ Alcohol-based solvent (isobutyl alcohol)

2. Measurement / Evaluation Method (1) Pigment Orientation in Coating Film / Filling Rate of Scaly Pigment in Coating Film It was determined according to the method described in the specification.
-Average of inclination angles of scaly pigments in the coating film with respect to the surface of the base material Obtained according to the method described in the specification.
The dry film thickness was 60 μm.
(2) Environmental barrier property Obtained according to the method described in the specification. The dry film thickness was 60 μm.
(3) Mirror gloss (60 °)
Measured according to JIS K5600-4-7. The coated plate obtained by the following coating plate manufacturing method was used for the measurement.
(4) Corrosion resistance Long-term durability of the coating film of JIS K5600-7-9: 2006, 120 cycles, 240 cycles, 360 cycles according to cycle D of the cycle corrosion test, and then around the cut applied to the test piece The degree of rust and swelling that occurred was evaluated based on the following criteria. The test plate obtained by the following coating plate manufacturing method was used for evaluation.
<Appearance of coating film>
⊚: There is no abnormality on the surface of the coating film, and the appearance of the coating film is excellent.
◯: Abnormalities such as rust and swelling are observed on a part of the coating film surface.
X: Abnormalities such as rust and swelling are observed on the entire surface of the coating film.
<Scratch deformation width>
⊚: There is no abnormality such as rust and swelling on the coated surface 2 mm or more from the cut portion.
◯: There is no abnormality such as rust and swelling on the coated surface 4 mm or more from the cut portion.
X: Abnormalities such as rust and swelling occurred on the coated surface 4 mm or more from the cut part.
(5) Method for preparing a coated plate A grit blast plate (3.2 × 70 × 150 mm) was spray-coated with a paint so that the dry film thickness was 60 μm, and dried to form an undercoat coating film. Then, as a topcoat paint, V-fluorocarbon # 100H topcoat (fluororesin topcoat paint manufactured by Dai Nippon Toryo Co., Ltd.) was spray-coated so that the dry film thickness was 25 μm.
The obtained two-layer coating film was dried at room temperature for one week to obtain a desired coating plate (test plate). The obtained coated plate was used for measuring the mirror glossiness. Further, the back surface of the obtained test plate was sealed with the same paint as the paint used as the undercoat paint, and subjected to the anticorrosion test.

3. 3. Examples and Comparative Examples The main agent and the curing agent were prepared according to the formulation shown in Table 1. Further, the obtained main agent and curing agent were mixed to prepare a coating composition, and the coating film performance was evaluated. The results are shown in Table 1. The unit of composition of the coating composition in Table 1 is "part by mass".

Claims (6)

A coating composition for forming a coating film having a film thickness of 30 to 300 μm, which comprises a resin, a scaly pigment, and a pigment dispersant.
The content of the scaly pigment in the non-volatile content of the coating composition is 10 to 50% by mass.
When a coating film is formed on a substrate from the coating composition, the average inclination angle of the scaly pigment in the coating film with respect to the substrate surface is 12.5 ° or less, and the scales in the coating film. A coating composition having a filling rate of 40 to 95 area% of a pigment. The coating composition according to claim 1, wherein the scaly pigment has an aspect ratio of 30 to 100. The coating composition according to claim 1 or 2, wherein the scaly pigment has an average particle size of 10 to 100 μm. The coating composition according to any one of claims 1 to 3, wherein the scaly pigment is mica, glass flakes or aluminum flakes. The coating composition according to any one of claims 1 to 4, wherein the pigment dispersant has an acid value of 10 to 150 mgKOH / g. The coating composition according to any one of claims 1 to 5, wherein the coating composition is a coating composition for being naturally dried at an ambient temperature.