WO2021002139A1

WO2021002139A1 - Heat-resistant coating composition, heat-resistant coating film, heat-resistant coating film-attached substrate, and method for preparing same

Info

Publication number: WO2021002139A1
Application number: PCT/JP2020/021999
Authority: WO
Inventors: 高橋　英樹; 康人引地; 浩章村田
Original assignee: 中国塗料株式会社
Priority date: 2019-07-03
Filing date: 2020-06-03
Publication date: 2021-01-07
Also published as: KR20220019109A; JPWO2021002139A1; KR102752754B1; CN113993638B; JP7329599B2; CN113993638A

Abstract

An embodiment of the present invention relates to a heat-resistant coating composition, a heat-resistant coating film, a heat-resistant coating film-attached substrate, or a method for preparing same, said heat-resistant coating composition including a siloxane-based binder (A), an aluminum powder (B), and an anti-corrosive pigment containing a magnesium phosphate-based compound.

Description

Heat-resistant paint composition, heat-resistant coating film, base material with heat-resistant coating film and its manufacturing method

One embodiment of the present invention relates to a heat-resistant coating composition, a heat-resistant coating film, a base material with a heat-resistant coating film, or a method for producing the same.

In pipes of plant structures, etc., heat insulating materials are often installed around the pipes (steel pipes) in order to prevent heat dissipation to the outside air and heat absorption from the outside air, and to suppress energy loss. However, rainwater that has entered the gap between the heat insulating material and the steel (eg, carbon steel, low alloy steel) pipe and water that has aggregated at that location form a water film on the surface of the steel pipe and corrode under the heat insulating material (CUI). : Corrosion Under Insulation) may occur. The CUI means that local corrosion erosion occurs by forming a corrosive battery on the surface of a steel pipe due to the water film. Its corrosion rate is faster than the total corrosion that occurs in the outdoor atmosphere, which poses a major problem in the maintenance of plant structures.

Further, in the CUI, since the corroded erosion portion is under the heat insulating material (surrounded by the heat insulating material), the moisture once invaded easily stays, and the wet state is maintained for a long period of time, depending on the operating conditions of the plant. Since the pipes may be exposed to high temperatures, the progress of corrosion, which is an oxidation reaction, is promoted, and plant structures are often installed in beach areas rich in sea salt particles that can be corrosion factors. Therefore, there is also a problem that the corrosion erosion is likely to become serious due to the fact that the sea salt particles promote the progress of corrosion.

Therefore, for the purpose of preventing the corrosion and the like, the piping used for the plant structure and the like is provided with an anticorrosion coating film (heat resistant coating film) on the outer surface thereof. This anticorrosive coating film is provided not only under the heat insulating material but also on the outer surface of the pipe where the heat insulating material is not applied for the purpose of preventing the same corrosion as described above. As the anticorrosion coating film provided on the outer surface of the pipe, particularly the portion not provided with the heat insulating material, a silver-colored anticorrosion coating film (metallic coating film) is preferably used from the viewpoint of its design and the like. ..

Further, since the piping used for a plant structure or the like is exposed to various temperature environments depending on the operating conditions of the plant or the like, the heat resistant temperature and resistance required for the anticorrosion coating film (heat resistant coating film) used for the piping. The heating and cooling cycle conditions are also wide-ranging, and for example, resistance in a wide temperature range from −198 ° C. to 500 ° C. or higher may be required.

Patent Document 1 discloses a coating composition containing polysiloxane, alkyl titanate, talc, and aluminum pieces as a composition capable of forming a metallic coating film having heat resistance and corrosion resistance.

Special Table 2009-522388

Aluminum pigments are usually used for the coating composition for forming the metallic coating film, but as a result of diligent studies by the present inventor, the anticorrosion coating film formed from the conventional coating composition containing the aluminum pigment has anticorrosion properties. It turns out that it may not be enough. When forming a coating film (metallic coating film) on a pipe, it may not be sufficiently heat-cured depending on the type and application of the pipe, but in such a case, the corrosion resistance is not sufficient. It turned out.

When forming a heat-resistant coating film on each member such as a steel pipe, it may be possible to heat-dry (bake), but the manufacturing cost is increased due to the increase in the number of processes and energy for heating. Will increase. Therefore, there is a demand for a coating composition capable of forming a heat-resistant coating film having sufficient coating film performance such as corrosion resistance required even if the coating film is formed by drying at room temperature (5 to 40 ° C.).

Further, when the heat-resistant coating film formed on the outer surface of a pipe such as a plant structure that can be exposed to an ultra-high temperature of 500 ° C. or higher is a thick film having a film thickness of 100 μm or more, the heat-resistant coating film is used in a high temperature environment. Swelling and cracks are likely to occur due to repeated temperature changes. More specifically, when the heat-resistant coating film is exposed to a high temperature, the residual solvent in the coating film volatilizes, and the silicone resin component constituting the coating film swells due to gas generated by the reaction / decomposition. In addition, cracks may occur due to an increase in the internal stress of the coating film due to the reaction / decomposition of the silicone resin component. Since these coating film defects are particularly likely to occur when a thick film is coated, the film thickness of the heat-resistant coating film obtained from the conventional silicone resin-based heat-resistant paint is usually less than 80 μm, and is 100 μm. It was difficult to achieve the above thick film coating specifications.
However, CUI has become a major maintenance problem in piping of plant structures, etc., and it is difficult to maintain long-term corrosion resistance with a thin film of less than 80 μm as described above against the severe corrosive environment. Do you get it.

One embodiment of the present invention exhibits excellent corrosion resistance without heating when forming a coating film, and has sufficient heat resistance, corrosion resistance, and adhesion to a substrate even under a wide range of temperatures including high temperatures. Provided is a heat resistant coating composition capable of forming a heat resistant coating film (metallic coating film) capable of maintaining the above.

We have found that the above problems can be solved according to the following configuration examples, and have completed the present invention.
A configuration example of the present invention is as follows.

<1> A heat-resistant coating composition containing a siloxane-based binder (A), aluminum powder (B), and a rust-preventive pigment (C) containing a magnesium phosphate-based compound.
<2> The heat-resistant coating composition according to <1>, wherein the rust preventive pigment (C) further contains a zinc phosphate-based compound.

<3> The heat-resistant coating composition according to <1> or <2>, which further contains a curing accelerator (D).

<4> The heat-resistant coating composition according to any one of <1> to <3>, wherein the pigment volume concentration (PVC) is 25 to 55%.

<5> A heat-resistant coating film formed from the heat-resistant coating composition according to any one of <1> to <4>.
A base material with a heat-resistant coating film containing the base material and the heat-resistant coating film according to <5>.
<7> A method for producing a base material with a heat-resistant coating film, which comprises the following steps [1] and [2].
[1] Step of coating the base material with the heat-resistant coating composition according to any one of <1> to <4> [2] Step of drying the coated heat-resistant coating composition to form a heat-resistant coating film.

According to one embodiment of the present invention, it exhibits excellent anticorrosion properties without heating when forming a coating film, and has sufficient heat resistance even under a wide range of temperatures including high temperatures (eg, 500 ° C. or higher). It is possible to provide a heat-resistant coating composition capable of forming a heat-resistant coating film (metallic coating film) capable of maintaining corrosion resistance and adhesion to a substrate.

FIG. 1 is a schematic plan view of a test piece containing a scribe used for evaluation of corrosion resistance in Examples.

≪Heat-resistant paint composition≫
The heat-resistant coating composition according to one embodiment of the present invention (hereinafter, also simply referred to as “the present composition”) contains a siloxane-based binder (A), aluminum powder (B), and a magnesium phosphate-based compound. Contains rust pigment (C).
Since this composition contains the above (A) and (C) together with the above (B), even though it is a metallic paint composition containing aluminum powder, it has sufficient corrosion resistance even if a coating film is formed by drying at room temperature. A heat-resistant coating film can be obtained, and according to this composition, a thick film having a dry film thickness of 100 μm or more and having anticorrosion properties and a base even after being exposed to a high temperature environment of more than 500 ° C. A heat-resistant coating film capable of maintaining adhesion to the material can be obtained.

Further, according to this composition, stainless steel (eg, SUS304, which is applied when it is expected to be exposed to a high temperature environment of 400 ° C. or higher, which has a larger coefficient of linear expansion than carbon steel, is particularly applicable. A heat-resistant coating film having good adhesion to SUS316L or the like can be formed.
For this reason, this composition is preferably used for the outer surface of pipes for plant structures, etc., where operation under various temperature conditions is expected and heat insulating materials are installed, and heat resistance suitable for suppressing CUI. / It is suitably used as a paint capable of forming an anticorrosion coating film.

The composition is not particularly limited as long as it contains the above (A) to (C), and if desired, other additives other than the above (A) to (C), as long as the effects of the present invention are not impaired. For example, a curing accelerator (D), a pigment other than the above (B) and (C), a dispersant, a defoaming agent, a sagging / sedimentation inhibitor, a dehydrating agent, and an organic solvent may be contained.

The present composition may be a one-component type composition or a two-component type or more composition.
The present composition preferably contains a curing accelerator (D) from the viewpoint that a heat-resistant coating film having excellent corrosion resistance can be easily obtained even when dried at room temperature. In this case, the above (A) to (C) It is preferable to prepare a two-component composition composed of a main component containing the above and a component containing the curing accelerator (D).
When the present composition is a composition of two or more components, each component used in the composition is usually stored, stored, transported, etc. in separate containers, and mixed and used immediately before use.

<Siloxane binder (A)>
The siloxane-based binder (A) is not particularly limited as long as it is a compound having a siloxane bond. The siloxane-based binder (A) is also a siloxane-based binder.
Since the siloxane-based binder (A) is used as the binder in this composition, a heat-resistant coating film having particularly excellent heat resistance can be obtained.
The siloxane-based binder (A) contained in the present composition may be one kind or two or more kinds.

The siloxane-based binder (A) has, for example, a reactive group in the molecule via a siloxane bond, and the reactive groups react with each other to form a high molecular weight or three-dimensional crosslinked structure and cure. Examples of the compound.
Examples of the reaction include a condensation reaction and an addition reaction, and examples of the condensation reaction include a dehydration reaction and a dealcoholization reaction.

The siloxane-based binder (A) is preferably a compound represented by the following formula (I), and may contain the following silicone resin (A1), silicone oligomer (A2) and / or ethyl silicate (A3). preferable.
In particular, the present composition preferably contains a silicone resin (A1) as the siloxane binder (A) from the viewpoint that a heat-resistant coating film having excellent heat resistance and corrosion resistance can be obtained, and the coating properties and coating properties are preferable. It is more preferable to use it in combination with a silicone oligomer (A2) and an ethyl silicate (A3) having a lower weight average molecular weight for the purpose of adjusting the film performance.
The siloxane-based binder (A) may be linear or branched.

(In the formula (I), R ¹ independently represents an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 8 carbon atoms or −OR (R is a hydrocarbon group having 1 to 8 carbon atoms). R ² independently represents an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 8 carbon atoms or a hydrogen atom, and n represents a repeating number, and the weight average molecular weight of the siloxane-based binder is 200 to 300. Selected to be in the range of 000.)

Examples of the alkyl group having 1 to 8 carbon atoms in R ¹ and R ² include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group.
The aryl group having 6 to 8 carbon atoms in R ¹ and R ² may be a group having a substituent such as an alkyl group on the aromatic ring, and examples thereof include a phenyl group, a methylphenyl group and a dimethylphenyl group. Be done.
Examples of the -OR in R ¹ include a methoxy group, an ethoxy group, a propoxy group, and a phenoxy group.

The weight average molecular weight (hereinafter simply referred to as “Mw”) of the siloxane-based binder (A) in terms of standard polystyrene measured by the GPC (gel permeation chromatography) method is preferably 200 or more, more preferably 400 or more. Yes, preferably 300,000 or less, more preferably 200,000 or less.
Specifically, the Mw can be measured by the method described in the following Examples.

The content of the siloxane-based binder (A) is preferably 20% by mass or more with respect to 100% by mass of the solid content of the present composition from the viewpoint that a heat-resistant coating film having better corrosion resistance and heat resistance can be obtained. It is more preferably 25% by mass or more, particularly preferably 35% by mass or more, preferably 60% by mass or less, more preferably 55% by mass or less, and particularly preferably 50% by mass or less.

<Silicone resin (A1)>
The silicone resin (A1) is not particularly limited as long as it is a compound other than the ethyl silicate (A3) described later, but is preferably a compound represented by the formula (I), and R ¹ in the formula (I) is A compound having a methyl group, an ethyl group, a propyl group or a phenyl group is more preferable, and a compound in which R ² in the formula (I) is a methyl group, an ethyl group, a phenyl group or a hydrogen atom is more preferable.
When the present composition contains a silicone resin (A1), the silicone resin (A1) may be one kind or two or more kinds.

The silicone resin (A1) is preferably a resin having heat resistance such as methyl silicone resin and methylphenyl silicone resin, and is described below as a dimethylsiloxane unit (a1), a diphenylsiloxane unit (a2), and a monomethylsiloxane unit (a3). , It is more preferable to contain one or more constituent units selected from the group consisting of the monopropylsiloxane unit (a4) and the monophenylsiloxane unit (a5).

(In the formulas (a1) to (a5), "-" in Si-O- that is bonded to O and not bonded to Si indicates a bond, and Si-O- is not necessarily Si-O-CH. Does not indicate _3. )

The Mw of the silicone resin (A1) is 15,000 or more, preferably 18,000 or more, and 300,000 or less from the viewpoint that a heat-resistant coating film having excellent heat resistance and corrosion resistance can be obtained. Yes, preferably 200,000 or less.
Since the silicone resin (A1) having Mw larger than the above range has a high viscosity, it is diluted with an organic solvent or the like in order to reduce the viscosity of the present composition containing such a silicone resin (A1) in consideration of handleability. Is often required. As a result, the solvent content in the composition increases, and it may not be possible to reduce VOCs (Volatile Organic Compounds) in the composition.

The silicone resin (A1) may be obtained by synthesizing it by a conventionally known synthetic method, or may be a commercially available product. Examples of the commercially available product include "SILRES REN60", "SILRES REN80" (all manufactured by Asahi Kasei Wacker Silicone Co., Ltd.), and "SILIKOPHEN P80 / X" (manufactured by Evonik Industries).

When the present composition contains a silicone resin (A1), the content of the silicone resin (A1) is a solid of the present composition from the viewpoint that a heat-resistant coating film having better corrosion resistance and heat resistance can be obtained. With respect to 100% by mass per minute, it is preferably 10% by mass or more, more preferably 15% by mass or more, particularly preferably 25% by mass or more, preferably 50% by mass or less, more preferably 45% by mass or less, and particularly preferably. It is 42% by mass or less.

<Silicone oligomer (A2)>
The silicone oligomer (A2) is not particularly limited as long as it is a compound other than the ethyl silicate (A3) described later, but it is preferably a compound having a structure similar to the structure described in the column of the silicone resin (A1). ..
The Mw of the silicone oligomer (A2) is less than 15,000, preferably 400 or more, and preferably 12,000 or less.
When the present composition contains a silicone oligomer (A2), the silicone oligomer (A2) may be one kind or two or more kinds.

The silicone oligomer (A2) may be obtained by synthesizing it by a conventionally known synthetic method, or may be a commercially available product. Examples of the commercially available product include "SILRES MSE100" (manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) and "KR-401N" (manufactured by Shin-Etsu Chemical Co., Ltd.).

When the present composition contains a silicone oligomer (A2), the content of the silicone oligomer (A2) is such that a heat-resistant coating film having better corrosion resistance and heat resistance can be obtained, and thus the solid of the present composition. With respect to 100% by mass per minute, it is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, particularly preferably 0.5% by mass or more, preferably 20% by mass or less, and more preferably 15% by mass. % Or less, particularly preferably 10% by mass or less.

<Ethyl silicate (A3)>
The ethyl silicate (A3) is a compound composed of a siloxane having an ethoxy group and is represented by the following formula (II).
When the present composition contains ethyl silicate (A3), the ethyl silicate (A3) may be one kind or two or more kinds.

(In formula (II), n is 1 to 10.)

Ethyl silicate (A3) may be obtained by synthesizing by a conventionally known synthetic method, or may be a commercially available product. Examples of the commercially available products include "Ethylsilicate 40" (manufactured by Corcote Co., Ltd.) and "Wacker Silicate TES 40WN" (manufactured by Asahi Kasei Wacker Silicone Co., Ltd.), which are oligomers having a molecular weight distribution centered on a pentamer. Can be mentioned.

When the present composition contains ethyl silicate (A3), the content of the ethyl silicate (A3) makes it possible to obtain a coating composition excellent in coating workability, cost reduction, and dehydration effect during storage. From the point of view, it is preferably 1% by mass or more, more preferably 2% by mass or more, preferably 20% by mass or less, and more preferably 15% by mass or less with respect to 100% by mass of the solid content of the present composition.

When the composition contains the above (A1) and / or (A2) and (A3), the total content of the silicone resin (A1) and the silicone oligomer (A2) in the composition and the ethyl silicate ( The ratio (A1 + A2: A3) to the content of A3) is preferably 95: 5 to 60:40 from the viewpoint that a heat-resistant coating film having better heat resistance and corrosion resistance can be obtained.

When the composition contains the above (A1) and (A2) and / or (A3), the content of the silicone resin (A1) in the composition and the silicone oligomer (A2) and ethyl silicate. The ratio (A1: A2 + A3) to the total content of (A3) is preferably 90:10 to 30:70 from the viewpoint that a heat-resistant coating film having better heat resistance and corrosion resistance can be obtained. It is preferably 90:10 to 40:60.

<Aluminum powder (B)>
The aluminum powder (B) is not particularly limited, and may be scaly aluminum powder or non-scaly aluminum powder other than scaly, but a more metallic heat-resistant coating film can be easily obtained. The reptile aluminum powder is preferable from the viewpoint of being able to be used. Further, by using the reptile aluminum powder, it is possible to form an anticorrosion coating film having excellent salt water resistance, moisture resistance and the like.
Further, as a raw material for preparing the present composition, not only powdered aluminum but also pasty aluminum may be used.
The aluminum powder (B) contained in the present composition may be one kind or two or more kinds.

The "reptile" refers to a scale-like shape, and although there is no specified range, the aspect ratio is usually preferably 5 or more, more preferably 10 or more. It is more preferably 20 or more, preferably 150 or less, and more preferably 120 or less.
Further, the "non-scaly" refers to a shape having a shape other than the scaly shape such as a sphere, a teardrop shape, a spindle shape, etc., and there is no particularly specified range, but usually the aspect ratio thereof. The ratio is preferably less than 5, more preferably 1 or more, and more preferably 3 or less.

The aspect ratio can be measured using an electron microscope. Observe the aluminum powder using a scanning electron microscope (SEM), for example, "XL-30" (trade name; manufactured by Philips), and observe the thickness of tens to hundreds of powder particles and the maximum length (or length) on the main surface. , The length of the major axis and the length of the minor axis), and calculate the average value of these ratios (maximum length / thickness on the main surface or length of the major axis / length of the minor axis). Can be calculated with.
The thickness of the aluminum powder can be measured by observing from the horizontal direction with respect to the main surface (the surface having the largest area) of the powder, and the maximum length of the aluminum powder on the main surface is For example, if the main surface is square, it means the length of the diagonal line, if the main surface is circular, it means the diameter, and if the main surface is elliptical, it means the length of the major axis. Specifically, the length of the major axis of the aluminum powder is the longest length in the cross-sectional view near the center of the powder, and the length of the minor axis of the aluminum powder is the cross section in the cross-sectional view. It is the length of a line orthogonal to the long axis at the center of the figure.

The median diameter (D50) of the scaly aluminum powder is preferably 100 μm or less, more preferably 5 μm or more, and more preferably 70 μm or less from the viewpoint that a coating film having more excellent corrosion resistance can be obtained. , Especially preferably 50 μm or less.
The median diameter (D50) of the non-scaly aluminum powder is preferably 50 μm or less, more preferably 5 μm or more, from the viewpoint that a composition having excellent coating workability can be obtained with a low VOC amount. It is more preferably 30 μm or less, and particularly preferably 15 μm or less.
The D50 is an average value measured three times using a laser scattering diffraction type particle size distribution measuring device, for example, "SALD 2200" (manufactured by Shimadzu Corporation).

The reptile aluminum powder may be a leafing type or a non-leafing type, but it is preferable to use the leafing type from the viewpoint of suppressing deterioration of the coating film and deterioration of adhesion to the base material. Further, when the reptile aluminum powder is used, a leaving type and a non-leaving type may be used in combination.

The non-scaly aluminum powder is preferably an aluminum powder produced by an atomizing method (spray method).

The content of the aluminum powder (B) in the present composition is 100% by mass of the solid content of the present composition from the viewpoint that a metallic coating film having excellent anticorrosion properties and adhesion to the base material can be obtained. On the other hand, it is preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 15% by mass or more, preferably 35% by mass or less, and more preferably 30% by mass or less.

<Rust preventive pigment (C)>
The rust preventive pigment (C) is not particularly limited as long as it contains a magnesium phosphate-based compound.
As a result of diligent studies by the present inventor, among rust preventive pigments, even when a coating film is formed by drying at room temperature for the first time when a magnesium phosphate compound is used, the metallic paint containing aluminum powder has excellent anticorrosive properties. We have found that a heat-resistant coating can be formed.
The rust preventive pigment (C) contained in the present composition may be one kind or two or more kinds. That is, the present composition may contain two or more kinds of magnesium phosphate compounds.

Examples of the magnesium phosphate-based compound include magnesium phosphate, magnesium ammonium phosphate, magnesium monohydrogen phosphate, magnesium dihydrogen phosphate, magnesium / calcium phosphate, magnesium / cobalt phosphate, and magnesium / nickel phosphate. , Magnesium phosphate / Zinc, Magnesium phosphate / Aluminum, Silica-modified magnesium phosphate, Magnesium phosphite, Magnesium phosphite / Aluminum, Magnesium phosphite / Calcium, Magnesium hypophosphite, Magnesium polyphosphate, Tripolyphosphoric acid Examples thereof include magnesium, magnesium metaphosphate, and magnesium pyrophosphate.

The rust preventive pigment (C) is a zinc phosphate compound (magnesium phosphate compound) together with the magnesium phosphate compound from the viewpoint that a heat-resistant coating film having excellent adhesion to the substrate can be easily obtained. Compounds other than) are preferably contained.
Examples of the zinc phosphate-based compound include zinc phosphate, zinc phosphite, zinc hypophosphite, zinc polyphosphate, zinc tripolyphosphate, zinc metaphosphate, zinc orthophosphate, zinc pyrophosphate, and zinc phosphate. , Zinc Phosphate, Zinc Aluminum Phosphate, Zinc Calcium Phosphate.

As the rust preventive pigment (C), other rust preventive pigments other than the magnesium phosphate compound and the zinc phosphate compound may be used, and the other rust preventive pigments include, for example, zinc powder and zinc. Alloy powder, calcium phosphate compound, aluminum phosphate compound, calcium phosphite compound, aluminum phosphite compound, strontium phosphite compound, aluminum tripolyphosphate compound, zinc molybdenate compound, aluminum molybdenate compound, Examples thereof include cyanamide zinc-based compounds, borate compounds, nitro compounds, and composite oxides.

D50 of the rust preventive pigment (C) measured using a laser diffraction type particle size distribution measuring device (SALD-2200, manufactured by Shimadzu Corporation) can obtain a heat-resistant coating film having better corrosion resistance. From the point of view, it is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 20 μm or less, and more preferably 15 μm or less.

The rust preventive pigment (C) may be a commercially available product, and examples of the commercially available product containing a magnesium phosphate compound include Pigmentan E (manufactured by Banner Chemicals Group UK), LF Bowsei MPZ-500, and LF Bowsei PMG (above, above, Examples thereof include Kikuchi Color Co., Ltd., NP-1802, and NP-1902 (all manufactured by Toho Pigment Industry Co., Ltd.), and examples of commercially available products containing zinc phosphate compounds include LF Bowsei ZP-N (manufactured by Toho Pigment Industry Co., Ltd.). Kikuchi Color Co., Ltd.).

The content of the rust preventive pigment (C) in the present composition is preferably 0.1 with respect to 100% by mass of the solid content of the present composition from the viewpoint that a heat-resistant coating film having better corrosion resistance can be obtained. It is mass% or more, more preferably 0.5 mass% or more, particularly preferably 1 mass% or more, preferably 20 mass% or less, more preferably 15 mass% or less, and particularly preferably 10 mass% or less.

The content of the magnesium phosphate compound in the present composition is preferably 0 with respect to 100% by mass of the solid content of the present composition from the viewpoint that a heat-resistant coating film having excellent corrosion resistance can be easily formed even when dried at room temperature. 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, preferably 15% by mass or less, more preferably 10% by mass or less, particularly preferably 5% by mass or less. Is.

When the present composition contains both a magnesium phosphate compound and a zinc phosphate compound, the magnesium phosphate compound and phosphorus can be easily obtained because of the excellent adhesion to the substrate. The total content of the zinc phosphate compound is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 20% by mass or less, based on 100% by mass of the solid content of the present composition. More preferably, it is 15% by mass or less.
Further, the content of the magnesium phosphate compound is preferably 20 with respect to 100 parts by mass of the zinc phosphate compound from the viewpoint that an excellent heat-resistant coating film can be easily obtained due to the adhesion to the substrate. It is more than parts by mass, more preferably 30 parts by mass or more, preferably 80 parts by mass or less, and more preferably 70 parts by mass or less.

The content of the aluminum powder (B) in the present composition is such that a metallic coating film having an excellent balance of corrosion resistance, adhesion to the substrate, coating film strength, etc. can be easily obtained. With respect to the total content of the aluminum powder (B) and the rust preventive pigment (C) of 100% by mass, it is preferably 50% by mass or more, more preferably 60% by mass or more, particularly preferably 70% by mass or more, and preferably 70% by mass or more. It is 99% by mass or less, more preferably 90% by mass or less, and particularly preferably 80% by mass or less.

The content of the magnesium phosphate-based compound in the present composition is that the aluminum powder (B) and the magnesium phosphate-based compound are different from each other in that a metallic heat-resistant coating film having excellent corrosion resistance can be easily formed even when dried at room temperature. With respect to the total content of 100% by mass, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, preferably 30% by mass or less, more preferably 20. It is mass% or less, particularly preferably 15 mass% or less.

When the present composition contains a zinc phosphate-based compound, the content of the zinc phosphate-based compound in the present composition makes it easy to obtain a metallic heat-resistant coating film having excellent adhesion to the substrate. From the above points, the total content of the aluminum powder (B) and the zinc phosphate compound is 100% by mass, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 1. It is 0% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, and particularly preferably 25% by mass or less.

<Curing accelerator (D)>
The curing accelerator (D) is not particularly limited, but is preferably a material having an effect of accelerating the cross-linking reaction of the siloxane binder (A). For example, aminosilane; titanium alkoxide, titanium chelate and the like are titanium-based curing. Catalyst; Aluminum-based curing catalyst such as aluminum metal soap; Zinc-based curing catalyst such as zinc metal soap; Phosphoric acid-based curing catalyst such as phosphoric acid and phosphoric acid ester; Tin-based curing catalyst such as dibutyltin dilaurate and dibutyltin diacetate A bismuth-based curing catalyst such as bismuth 2-ethylhexanoate and bismuth naphthenate; a lithium-based curing catalyst such as lithium decanoate can be mentioned. Among these, aminosilane is preferable from the viewpoint that when the present composition is dried at room temperature, a heat-resistant coating film having more excellent corrosion resistance can be easily obtained. It is also preferable that it is a mixture of aminosilane and alcohol.

As the aminosilane, an amino group-containing silane coupling agent is preferable. The silane coupling agent is not particularly limited, and conventionally known compounds can be used, but the compounds have at least two functional groups in the same molecule and can contribute to the improvement of adhesion to the substrate. are preferred, for example, the formula: _{"X-SiMe _n} Y _3-n" [n is 0 or 1, X comprises a reaction capable amino groups of the organic group (e.g., amino groups, a portion of the hydrocarbon group Is a group substituted with an amino group, or a group in which a part of the hydrocarbon group is substituted with an ether bond or the like is partially substituted with an amino group.), Me is a methyl group, and Y is a methyl group. Shows a hydrolyzable group (eg, an alkoxy group such as a methoxy group or an ethoxy group). ] Is more preferable.

The curing accelerator (D) may be a commercially available product, and examples of the commercially available product include phosphoric acid-based curing catalysts "D-220" and "X-40-2309A", and titanium-based curing catalysts "D". -25 "," D-20 "," DX-175 ", aluminum-based curing catalyst" DX-9740 "," CAT-AC ", aminosilane" KP-390 "(n of amino group-containing alkoxysilane) -Butanol solution), zinc-based curing catalysts "D-15" and "D-31" (all manufactured by Shin-Etsu Chemical Industry Co., Ltd.).

When the present composition contains a curing accelerator (D), the content of the curing accelerator (D) is such that a heat-resistant coating film having excellent corrosion resistance can be easily formed even when dried at room temperature. With respect to 100% by mass of the solid content of, it is preferably 0.01% by mass or more, more preferably 0.5% by mass or more, preferably 5% by mass or less, and more preferably 3% by mass or less.

<Other additives>
The composition is not particularly limited as long as it contains the above (A) to (C), and if desired, other pigments other than the above (B) and (C), for example, as long as the effects of the present invention are not impaired. It may contain other additives such as (eg, extender pigments, color pigments), dispersants, defoamers, anti-sagging / sedimentation agents, dehydrating agents, organic solvents and the like.
These other additives may be one kind or two or more kinds, respectively.

<Other pigments>
The extender pigment is not particularly limited, but is preferably an extender pigment having heat resistance, and examples thereof include talc, silica, potassium orthoclase, barium sulfate, zinc oxide, calcium carbonate, kaolin, and aluminum oxide.
When the present composition contains an extender pigment, the content of the extender pigment is based on 100% by mass of the solid content of the present composition from the viewpoint that a heat-resistant coating film having more excellent corrosion resistance can be easily formed. It is preferably 10% by mass or more, more preferably 15% by mass or more, preferably 40% by mass or less, and more preferably 35% by mass or less.

The coloring pigment is not particularly limited, but is preferably a coloring pigment having heat resistance, and examples thereof include Pigment Black 28 (Copper chromate black spinel), stainless flakes, titanium white, carbon black, and a valve handle.

The other pigments are preferably used in an amount such that the pigment volume concentration (PVC: Pigment Volume Concentration) in the present composition is within the following range.
The PVC in the present composition is preferably 25% or more, more preferably 30% or more, preferably 30% or more, from the viewpoints of being able to obtain a heat-resistant coating film having excellent corrosion resistance and adhesion to a substrate. It is 55% or less, more preferably 50% or less, still more preferably 45% or less, even more preferably 43% or less, and particularly preferably 40% or less.
When PVC is below the above range, the corrosion resistance of the heat-resistant coating film to be formed tends to decrease, and the adhesion of the formed coating film to the substrate also tends to decrease. Further, when PVC exceeds the above range, the corrosion resistance of the heat-resistant coating film formed tends to decrease.

The PVC refers to the total volume concentration of all pigments including the above-mentioned (B), (C) and other pigments with respect to the volume of solid content (nonvolatile content) in the present composition. It can be calculated from the following formula.
PVC [%] = total volume of all pigments in the composition x 100 / volume of solids in the composition

In addition, in this specification, the solid content of this composition means the heating residue obtained according to JIS K 5601-1-2 (heating temperature: 125 ° C., heating time: 60 minutes). Further, the solid content of the present composition can also be calculated as an amount excluding the solvent in the raw material used and the organic solvent.

The volume of the solid content in the present composition can be calculated from the mass and the true density of the solid content of the present composition. The mass and true density of the solid content may be measured values or values calculated from the raw materials used.
The volume of the pigment can be calculated from the mass and true density of the pigment used. The mass and true density of the pigment may be measured values or values calculated from the raw materials used. For example, it can be calculated by separating the pigment and other components from the solid content of the present composition and measuring the mass and true density of the separated pigment.

<Dispersant>
The dispersant is not particularly limited, but is preferably a dispersant capable of uniformly dispersing the (B), (C) and other pigments to prepare a stable dispersion.
The dispersant may be a commercially available product, and examples of the commercially available product include "Disperbyk-180" and "Disperbyk-2022" (both manufactured by Big Chemie Japan Co., Ltd.).

<Defoamer>
The antifoaming agent is not particularly limited, but is a material capable of suppressing the generation of bubbles during the production or painting of the present composition, or a material capable of breaking the bubbles generated in the present composition. Is preferable.
The defoaming agent may be a commercially available product, and examples of the commercially available product include "BYK-320", "BYK-066N", and "BYK-1790" (all manufactured by Big Chemie Japan Co., Ltd.). ..

<Sauce prevention / sedimentation prevention agent>
The sagging preventive / sedimentation inhibitor is not particularly limited, but is a material capable of suppressing the sedimentation of the pigments (B), (C) and other pigments and improving the storage stability thereof, or during or after painting. It is preferable that the material can improve the sagging property of the coating composition.

Examples of the anti-sagging / sedimentation inhibitor include organic rocking agents such as amide-based rocking agents, hydrogenated castor oil-based rocking agents, polyethylene oxide-based rocking agents, clay minerals such as bentonite, and synthetic fine powder silica. Among these, clay minerals such as amide-based rocking agents, polyethylene oxide-based rocking agents, synthetic fine powder silica, and bentonite are preferable.

In particular, by containing an amide-based rocking agent, it is excellent in rocking denaturation, and according to the composition containing the amide-based rocking agent, a thick film having a dry film thickness of 100 μm or more can be easily formed by one coating. Even if the base material to be coated is stainless steel such as SUS304 or SUS316L, it has excellent adhesion to the base material and is excellent even after being exposed to a high temperature environment of 400 ° C. or higher. A heat-resistant coating film that maintains good adhesion can be easily obtained.
Examples of the amide-based shaker include a shaker synthesized from vegetable oil fatty acids and amines.

The anti-sagging / sedimentation inhibitor may be a commercially available product, and the commercially available products include, for example, "Disparon A630-20X" and "Disparon 6650" (both manufactured by Kusumoto Kasei Co., Ltd.), which are amide-based rocking agents. ), "ASA T-250F" (manufactured by Ito Oil Co., Ltd.), "Flownon RCM-300TL" (manufactured by Kyoeisha Chemical Co., Ltd.), organically modified bentonite viscosity modifier (hectorite / 4th grade) Amine) "Bentone 38" (manufactured by Denaturis Specialties Inc.), silicon dioxide-based rocking agent "Aerosil R972" (manufactured by Nippon Aerozil Co., Ltd.), polyethylene oxide-based rocking agent "AS-" "AD-120" (manufactured by Ito Oil Co., Ltd.) can be mentioned.

When the present composition contains a sagging / sedimentation inhibitor, the content of the sagging / sedimentation inhibitor is preferably 0.1 to 10% by mass with respect to 100% by mass of the solid content of the composition. is there.

<Organic solvent>
When this composition is applied to a plant structure that is in a high temperature state during plant operation, especially a base material such as the outer surface of a pipe, the organic solvent component is easily volatilized by the heat of the base material surface, and a good coating film is formed. Is likely to be difficult. Therefore, the organic solvent preferably contains an organic solvent having a relatively high boiling point. Examples of such a high boiling point organic solvent include mineral spirit (turpen) and isopropyl alcohol. In addition, solvents usually used for paints can also be applied. Examples of such an organic solvent include xylene, toluene, and n-butanol.

≪Heat-resistant coating film and base material with heat-resistant coating film≫
The heat-resistant coating film according to one embodiment of the present invention (hereinafter, also referred to as “the present heat-resistant coating film”) is formed from the above-mentioned composition, and the base material with the heat-resistant coating film according to one embodiment of the present invention is: It is a laminate containing the present heat-resistant coating film and a base material.

The base material is not particularly limited, and for example, a metal base material made of steel (iron, steel, alloy iron, carbon steel, alloy steel, etc.), non-ferrous metal (aluminum, etc.), stainless steel, and a shop primer or the like on the surface. Examples include coated metal substrates. Further, examples of the base material include a plant structure, a land structure, an offshore structure, a ship, and the like, but from the viewpoint of more exerting the effects of the present invention, the plant structure is preferable. Among the structures, plant piping is more preferable. As the base material, carbon steel used for plant piping, ships, and marine structures, or stainless steel such as SUS304 and SUS316L, which is preferably used for parts requiring cold resistance and heat resistance, is more preferable.

The film thickness of the heat-resistant coating film is not particularly limited as long as it is thick enough to prevent corrosion of the substrate, but is preferably 30 μm or more, more preferably 50 μm or more, still more preferably 100 μm or more, and particularly preferably 150 μm or more. It is preferably 400 μm or less, more preferably 280 μm or less.
Since this composition is used, even if a coating film having such a film thickness is formed on the base material, swelling and cracks are unlikely to occur in the coating film, and in particular, the coating film is subject to a high temperature of 500 ° C. or higher and a sudden temperature change. Even when exposed, swelling and cracks are unlikely to occur, so that the substrate can be protected from corrosion for a long period of time.
A thicker film is desirable in consideration of corrosion resistance, but in the case of an excessively thick film, the residual solvent and the like contained in the coating film volatilize due to heating, causing swelling of the coating film or a siloxane-based film. The internal stress of the coating film caused by the structural change due to the reaction or decomposition of the binder (A) and the components derived from the binder tends to increase, and cracks and peeling due to the increase tend to occur easily.

The heat-resistant coating film is formed from the above-mentioned composition, and can be specifically produced by undergoing a step including the following steps [1] and [2].
[1] Step of applying the present composition to the base material [2] Step of drying the heat-resistant coating composition coated on the base material to form a heat-resistant coating film

Furthermore, this method can form a heat-resistant coating film having better corrosion resistance and heat resistance by including the following step [3].
[3] A step of heating the heat-resistant coating film obtained in the step [2].

<Step [1]>
The method for coating the composition on the substrate is not particularly limited, and conventionally known methods can be used without limitation, and commonly used airless spray coating, air spray coating, brush coating, roller coating and the like are preferable. Spray coating is preferable because it is excellent in workability and productivity, can be easily coated on a large-area substrate, and can further exert the effects of the present invention.
When the present composition is a two-component composition containing a curing accelerator, it is preferable to mix the main component and the component containing the curing accelerator immediately before painting and perform spray painting or the like.

The conditions for spray coating may be appropriately adjusted according to the thickness of the heat-resistant coating film to be formed. For example, in the case of airless spray, the primary (air) pressure: about 0.4 to 0.8 MPa, secondary ( The coating conditions may be set to (paint) pressure: about 10 to 26 MPa and gun moving speed: about 50 to 120 cm / sec.
The viscosity of the composition used at this time may be adjusted with thinner or the like, and the viscosity at that time is 23 when measured with a B-type viscometer (“TVB-10M, manufactured by Toki Sangyo Co., Ltd.)”. It is preferably about 1.8 to 2.5 Pa · s at ° C. The thinner is preferably an organic solvent capable of dissolving or dispersing the components in the composition, and for example, aromatic carbonization such as toluene and xylene. Examples thereof include a hydrogen solvent, an aliphatic hydrocarbon solvent such as mineral spirit and cyclohexane, and an alcohol solvent such as n-butanol and isopropanol. The thinner used may be one type or two or more types.

When this composition is applied to plant piping, etc., it is possible to apply it to relatively high temperature piping, etc. without stopping the operation of the plant. In this case, the spray-painted paint is uniform on the surface of the substrate. It solidifies before it becomes a smooth coating, and it becomes easy to be coated in the form of dust. A high boiling point organic solvent can be used as the thinner for the purpose of suppressing this.

When the present composition is applied onto a base material, in order to remove rust, oil, moisture, dust, salt, etc. on the base material, and to improve the adhesion of the obtained heat-resistant coating film to the base material. If necessary, it is preferable to treat the surface of the base material (for example, blast treatment (ISO8501-1 Sa2 1/2), treatment for removing oil and dust by degreasing) and the like. Further, the base material may be coated with a shop primer or the like for the purpose of primary rust prevention.

As a method for forming a heat-resistant coating film having the above-mentioned film thickness, a coating film having a desired film thickness may be formed by one coating, or a desired film thickness may be formed by two or more coatings (two or more coatings). A coating film may be formed. From the viewpoint of film thickness control and the residual solvent in the coating film, it is preferable to form a coating film having a desired film thickness by two or more coatings.
The two coatings (two coatings) are the steps [1] and [2], and if necessary, the steps [3], and then the steps [1] and [2] are applied on the obtained coating film. , Refers to a method of performing step [3] as necessary, and coating three or more times further refers to a method of repeating a series of steps.

When forming a coating film by coating two or more times, for example, it is preferable that the hue of the paint / coating film to be coated first and the hue of the paint / coating film to be coated next are different. This is a measure for facilitating the judgment of forgetting to apply or insufficient film thickness in the painting work. In addition, a top coat may be applied to finish the final hue of the outer surface to a specified hue.

<Step [2]>
The present composition can be dried and cured at room temperature, and thus a heat-resistant coating film having excellent heat resistance and corrosion resistance can be obtained even when dried and cured at room temperature. If desired, it may be dried under heating in order to shorten the drying time.
The drying conditions are not particularly limited, and may be appropriately set according to the composition, the base material, the coating place, and the like. The drying temperature is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, preferably 40 ° C. or lower, and more preferably 30 ° C. or lower. The drying time is preferably 18 hours or more, more preferably 24 hours or more, preferably 14 days or less, and more preferably 7 days or less.

<Step [3]>
By performing the above step [3], a heat-resistant coating film that is physically and chemically more resistant can be formed. That is, it is possible to form a heat-resistant coating film having higher coating film hardness or more excellent corrosion resistance.
The heating conditions in the step [3] are not particularly limited, but the heating temperature is preferably 150 to 250 ° C., and the heating time is preferably 10 minutes or longer, more preferably 30 minutes or longer, preferably 3 It is less than an hour, more preferably less than one hour.

Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited thereto.

[Examples 1 to 9 and Comparative Examples 1 to 2]
Each of the raw materials listed in the column of the main agent in Table 1 was added to the container in the amount (parts by mass) shown in Table 1, stirred with a high-speed disperser, and uniformly dispersed to prepare the main agent component.
The details of each component shown in Table 1 are as shown in Table 2. The solid content (mass%) of each component in Table 2 is a value in the manufacturer's catalog.

<Adhesion evaluation>
A coating composition was obtained by mixing 100 parts by mass of the prepared main ingredient and 1.5 parts by mass of the curing accelerator KP-390, and the obtained coating composition was subjected to SS400 sandblasting (ISO8501-ISO8501-). 1 Sa2 1/2) The steel sheet was coated with a film applicator having a gap of 700 μm so that the dry film thickness was 250 μm.
A test piece (base material with a coating film) was prepared by drying the coating composition coated on the steel sheet at 23 ° C. for 7 days. Further, in order to eliminate the influence of the unpainted portion of the coating composition, a test piece in which the back surface and the edge portion of the test piece are coated with an epoxy-based anticorrosive paint is used, and each test piece is neutralized according to JIS Z 2371. After performing a salt spray test (35 ° C) for 3 weeks, the test piece was washed with water and then dried for 1 day in an environment of a temperature of 23 ° C and a humidity of 55%, and a grid tape peeling test (5 mm × 5 mm, 9 squares) was performed.

Specifically, the grid tape peeling test was performed as follows.
Using a cutter guide, the coating film of the test piece after drying was cut into 4 vertical × 4 horizontal cuts at a depth reaching the steel plate to prepare a 9-square grid. The interval between cuts was 5 mm. Next, cellophane tape (registered trademark) was strongly pressure-bonded to the grid portion of the coating film, and the end of the cellophane tape was peeled off at a stretch at an angle of 90 ° with respect to the coating film surface. Then, the residual area ratio (%), which is the area of the coating film remaining on the steel sheet, was calculated with respect to the area of the 9 squares, and the adhesion was evaluated by the value of the residual area ratio (%).
When the remaining area ratio (%) was less than 50%, it was regarded as defective (x), and when the remaining area ratio (%) was 50% or more, the adhesion was good (◯).

<Evaluation of corrosion resistance>
Test pieces were prepared as described in (1) to (3) below, and the salt spray test of (4) below was performed using each test piece for evaluation.

(1) An unheated test piece By mixing 100 parts by mass of the prepared main ingredient and 1.5 parts by mass of KP-390, which is a curing accelerator, a coating composition was obtained, and the obtained coating material was further obtained. The composition was adjusted with xylene so that the viscosity at 23 ° C. measured with the B-type viscometer was 2 Pa · s.
The viscosity-adjusted coating composition was coated on an SS400 sandblasted (corresponding to ISO8501-1 Sa2 1/2) steel sheet using a film applicator with a gap of 700 μm so that the dry film thickness was 250 μm.
Then, the coating composition coated on the steel sheet was dried at 23 ° C. for 7 days to prepare an unheated test piece (base material with a coating film).

(2) Heat cycle test piece (300 ° C heating + quenching)
The test piece obtained in the same manner as the (1) unheated test piece was placed in an electric oven, heated at 300 ° C. for 1.5 hours, taken out of the oven, and immediately immersed in ice water for 10 seconds for rapid cooling. Then, the test piece was taken out from ice water and left at room temperature for 30 minutes. A heat cycle test piece was prepared by carrying out this heating and quenching as one cycle and carrying out three cycles.

(3) Heat resistance test piece (heated at 550 ° C)
A heat resistance test piece was prepared by putting the test piece obtained in the same manner as in the above (1) unheated test into a muffle furnace, heating at 550 ° C. for 4 hours, and then allowing to cool.

(4) Salt spray test In each of the test pieces prepared in (1) to (3) above, a scratch (creep) having a depth to the extent that a part of the steel plate is exposed is made in the portion shown in FIG. In order to eliminate the influence of the unpainted part of the coating composition, a test piece in which the back surface and the edge portion of the test piece are coated with an epoxy-based anticorrosion paint is used, and each test piece is sprayed with neutral salt water according to JIS Z 2371. The test (35 ° C.) was carried out for 3 weeks, and the creep width (the length between the part farthest from the scribing part and the scribing part among the parts where the coating film and the steel plate were peeled off) was measured. , Evaluated according to the following evaluation criteria. Here, the “evaluation target portion” refers to a portion excluding the range of 1 cm from the end portion of the test piece in consideration of the influence of the epoxy-based anticorrosive paint.

-Evaluation criteria ◎: Creep width in the evaluation target part is less than 5 mm ○: Creep width in the evaluation target part is 5 mm or more and less than 10 mm Δ: Creep width in the evaluation target part is 10 mm or more and less than 20 mm ×: Creep in the evaluation target part Width is 20 mm or more

Claims

A heat-resistant coating composition containing a siloxane-based binder (A), aluminum powder (B), and a rust-preventive pigment (C) containing a magnesium phosphate-based compound.
The heat-resistant coating composition according to claim 1, wherein the rust preventive pigment (C) further contains a zinc phosphate-based compound.
The heat-resistant coating composition according to claim 1 or 2, further comprising a curing accelerator (D).
The heat-resistant coating composition according to any one of claims 1 to 3, wherein the pigment volume concentration is 25 to 55%.
A heat-resistant coating film formed from the heat-resistant coating composition according to any one of claims 1 to 4.
A base material with a heat-resistant coating film containing the base material and the heat-resistant coating film according to claim 5.
A method for producing a base material with a heat-resistant coating film, which comprises the following steps [1] and [2].
[1] Step of coating the base material with the heat-resistant coating composition according to any one of claims 1 to 4 [2] Step of drying the coated heat-resistant coating composition to form a heat-resistant coating film.