JP7329599B2 - Heat-resistant paint composition, heat-resistant coating film, substrate with heat-resistant coating film, and method for producing the same - Google Patents

Description

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

2. Description of the Related Art Heat insulating materials are often installed around pipes (steel pipes) in plant structures and the like 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 enters the gap between the insulation material and the steel (e.g. carbon steel, low alloy steel) pipe, and moisture that condenses at that location forms a water film on the surface of the steel pipe, causing corrosion under insulation (CUI). : Corrosion Under Insulation) may occur. The CUI means that local corrosion erosion occurs due to the formation of corrosion cells on the steel pipe surface due to the water film. Since its corrosion rate is faster than that of general corrosion that occurs in the open air, it poses a serious problem in the maintenance of plant structures.

Furthermore, since the CUI is located under the heat insulating material (surrounded by the heat insulating material), the water that has once entered the CUI is likely to remain, and the wet state can be maintained for a long period of time. , because the pipes are sometimes exposed to high temperatures, the progress of corrosion, which is an oxidation reaction, is promoted Therefore, it is also a problem that the sea salt particles accelerate the progress of corrosion, and the corrosion erosion tends to become serious.

Therefore, for the purpose of preventing the corrosion and the like, pipes used in plant structures and the like are provided with an anticorrosive coating (heat-resistant coating) on the outer surface thereof. This anti-corrosion coating film is provided not only under the heat insulating material but also on portions of the outer surface of the pipe where the heat insulating material is not applied for the purpose of preventing corrosion and the like similar to those described above. As the anti-corrosion coating film provided on the outer surface of such pipes, especially on the part where the heat insulating material is not applied, a silver-colored anti-corrosion coating film (metallic coating film) is preferably used from the viewpoint of its design and the like. .

In addition, pipes used in plant structures, etc. are exposed to various temperature environments depending on the operating conditions of the plant. 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.

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

Japanese Patent Publication No. 2009-522388

Aluminum pigments are usually used in coating compositions that form metallic coating films, but as a result of extensive studies by the present inventors, anticorrosion coating films formed from conventional coating compositions containing aluminum pigments have anticorrosion properties. It turns out that sometimes it's not enough. When forming a coating film (metallic coating film) on a pipe, it may not be possible to heat and harden it sufficiently depending on the type and application of the pipe. I found out.

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

In addition, when the heat-resistant coating film formed on the outer surface of piping of plant structures and the like that can be exposed to ultrahigh temperatures of 500 ° C. or higher is a thick film with a thickness of 100 μm or more, the heat-resistant coating film is used in a high temperature environment, Blisters and cracks are likely to occur due to repeated temperature changes. More specifically, when the heat-resistant coating film is exposed to high temperatures, volatilization of the residual solvent in the coating film and swelling due to gas generated by reaction and decomposition of the silicone resin component constituting the coating film, In addition, cracks may occur due to increased internal stress in the coating film due to reaction, decomposition, etc. of the silicone resin component. These coating film defects are particularly likely to occur when a thick film is applied. It was difficult to achieve coating specifications for such a thick film.
However, CUI has become a major problem in maintenance management for piping in plant structures, and it is known that a thin film of less than 80 μm as described above cannot maintain long-term corrosion resistance in a severely 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 substrates even under a wide range of temperatures including high temperatures. To provide a heat-resistant paint composition capable of forming a heat-resistant paint film (metallic paint film) capable of maintaining

The inventors have found that the above problems can be solved by 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 comprising a siloxane-based binder (A), aluminum powder (B), and an antirust 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 compound.

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

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

<5> A heat-resistant coating film formed from the heat-resistant coating composition according to any one of <1> to <4>.
<6> A substrate with a heat-resistant coating, comprising the substrate and the heat-resistant coating according to <5>.
<7> A method for producing a substrate with a heat-resistant coating, comprising the following steps [1] and [2].
[1] A step of applying the heat-resistant coating composition according to any one of <1> to <4> to a substrate [2] A step of drying the applied 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 scribed test piece used for corrosion resistance evaluation in Examples.

≪Heat resistant paint composition≫
A heat-resistant coating composition according to one embodiment of the present invention (hereinafter also simply referred to as "this composition") is a siloxane-based binder (A), an aluminum powder (B), and a magnesium phosphate-based compound. Contains rust pigment (C).
Since the present composition contains the above (A) and (C) together with the above (B), it is a metallic coating composition containing aluminum powder, and even when a coating film is formed by drying at room temperature, it has sufficient anticorrosion properties. In addition, according to the present composition, the dry film thickness is a thick film of 100 μm or more, and even after exposure to a high temperature environment exceeding 500 ° C., corrosion resistance and base It is possible to obtain a heat-resistant coating film that can maintain adhesion to the material.

In addition, according to the present composition, stainless steel (e.g., SUS304, SUS316L, etc.) can form a heat-resistant coating film with good adhesion.
For this reason, the present composition is suitable for use on the outer surface of piping for plant structures, etc., where operation under various temperature conditions is assumed, and where heat insulating materials are installed. / Suitably used as a coating capable of forming an anticorrosive coating.

The present 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) within a range that does not impair the effects of the present invention, For example, it may contain a curing accelerator (D), pigments other than the above (B) and (C), a dispersant, an antifoaming agent, an anti-sagging/anti-settling agent, a dehydrating agent, and an organic solvent.

The composition may be a one component composition or a two or more component 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) and a component containing the curing accelerator (D), preferably a two-component composition.
When the present composition is a composition of two or more components, the components used in the composition are usually stored, stored, transported, etc. in separate containers and mixed just before use.

<Siloxane-based 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 the present 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 of one type or two or more types.

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

The siloxane-based binder (A) is, for example, 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) in view of the ability to obtain a heat-resistant coating film with excellent heat resistance and corrosion resistance. For the purpose of adjusting membrane performance, it is more preferable to use in combination with silicone oligomer (A2) and ethyl silicate (A3) having a lower weight average molecular weight.
The siloxane-based binder (A) may be linear or branched.

（式（Ｉ）中、Ｒ¹はそれぞれ独立に、炭素数１～８のアルキル基、炭素数６～８のアリール基または－ＯＲ（Ｒは炭素数１～８の炭化水素基）を示し、Ｒ²はそれぞれ独立に、炭素数１～８のアルキル基、炭素数６～８のアリール基または水素原子を示す。また、ｎは繰り返し数を示し、シロキサン系バインダーの重量平均分子量が２００～３００，０００の範囲となるように選択される。）

(in formula (I), each 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); Each 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, n represents the number of repetitions, and the weight average molecular weight of the siloxane-based binder is 200 to 300. , 000.)

Examples of the alkyl group having 1 to 8 carbon atoms in R ¹ and R ² include methyl group, ethyl group, propyl group, butyl group and 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 —OR in R ¹ include a methoxy group, an ethoxy group, a propoxy group and a phenoxy group.

The weight average molecular weight of the siloxane-based binder (A) measured by GPC (gel permeation chromatography) in terms of standard polystyrene (hereinafter also simply referred to as "Mw") 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 Examples below.

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 excellent corrosion resistance and heat resistance can be obtained. 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 it is preferably a compound represented by the formula (I), and R ¹ in the formula (I) is Compounds in which R 2 in formula (I) is methyl, ethyl, propyl or phenyl are more preferred, and compounds in which R ² in formula (I) is methyl, ethyl, phenyl or hydrogen are more preferred.
When the present composition contains a silicone resin (A1), the silicone resin (A1) may be of one type or two or more types.

The silicone resin (A1) is preferably a resin having heat resistance such as methyl silicone resin, methylphenyl silicone resin, etc., and the following dimethylsiloxane unit (a1), diphenylsiloxane unit (a2), monomethylsiloxane unit (a3) , monopropylsiloxane units (a4) and monophenylsiloxane units (a5).

（式（ａ１）～（ａ５）中、Ｓｉ－Ｏ－における、Ｏに結合し、Ｓｉに結合していない「－」は、結合手を示し、Ｓｉ－Ｏ－は、必ずしもＳｉ－Ｏ－ＣＨ₃を示すわけではない。）

(In the formulas (a1) to (a5), the "-" 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 It 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 an Mw larger than the above range has a high viscosity, in consideration of handleability, in order to reduce the viscosity of the present composition containing such a silicone resin (A1), dilution with an organic solvent or the like is necessary. is often required. As a result, the solvent content in the present composition increases, and VOC (Volatile Organic Compounds) in the present composition may not be reduced.

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

When the present composition contains a silicone resin (A1), the content of the silicone resin (A1) is the solid content of the present composition, from the viewpoint that a heat-resistant coating film having excellent corrosion resistance and heat resistance can be obtained. 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, 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 the same structure as the structure listed in the silicone resin (A1) section. .
Mw of the silicone oligomer (A2) is less than 15,000, preferably 400 or more, preferably 12,000 or less.
When the present composition contains the silicone oligomer (A2), the silicone oligomer (A2) may be of one type or two or more types.

The silicone oligomer (A2) may be synthesized by a conventionally known synthetic method, or may be a commercially available product. Examples of such commercially available products 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 the silicone oligomer (A2), the content of the silicone oligomer (A2) is the solid content of the present composition from the viewpoint that a heat-resistant coating film having excellent corrosion resistance and heat resistance can be obtained. 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, more preferably 15% by mass, based on 100% by mass. % or less, particularly preferably 10 mass % or less.

<Ethyl silicate (A3)>
The ethyl silicate (A3) is a compound composed of 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 of one type or two or more types.

（式（ＩＩ）中、ｎは１～１０である。）

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

Ethyl silicate (A3) may be synthesized by a conventionally known synthetic method, or may be a commercially available product. Examples of the commercially available products include "Ethyl Silicate 40" (manufactured by Colcoat 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 pentamers. is mentioned.

When the present composition contains ethyl silicate (A3), the content of the ethyl silicate (A3) is such that a coating composition that is excellent in coating workability, cost reduction, and dehydration effect during storage can be obtained. 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, more preferably 15% by mass or less, relative to 100% by mass of the solid content of the present composition.

When the composition contains (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 excellent heat resistance and corrosion resistance can be obtained.

Further, when the composition contains (A1) and (A2) and/or (A3), the content of the silicone resin (A1), the silicone oligomer (A2) and the ethyl silicate in the composition The ratio (A1: A2 + A3) to the total content of (A3) is preferably 90: 10 to 30: 70 from the viewpoint of obtaining a heat resistant coating film with excellent heat resistance and corrosion resistance, and more It is preferably 90:10 to 40:60.

<Aluminum powder (B)>
The aluminum powder (B) is not particularly limited, and may be a scale-like aluminum powder or a non-scale-like aluminum powder other than the scale-like aluminum powder. A scale-like aluminum powder is preferred because it can Also, by using the scale-like aluminum powder, it is possible to form an anti-corrosion coating film which is more excellent in resistance to salt water and humidity.
As a raw material for preparing the present composition, not only powdered aluminum but also paste aluminum may be used.
The aluminum powder (B) contained in the present composition may be of one type or two or more types.

The above-mentioned "scaly" refers to those having the shape of a scale, and although there is no particularly defined 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.
In addition, the above-mentioned "non-scaly" refers to those having a shape other than a scaly shape such as a spherical shape, a teardrop shape, a spindle shape, etc., and there is no particularly defined range, but usually the aspect The ratio is preferably less than 5, more preferably 1 or more, more preferably 3 or less.

The aspect ratio can be measured using an electron microscope. Observing the aluminum powder using a scanning electron microscope (SEM), for example, "XL-30" (trade name; manufactured by Philips), the thickness of several tens to several hundred powder particles and the maximum length on the main surface (or , the length of the major axis and the length of the minor axis), and 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 by
The thickness of the aluminum powder can be measured by observing from the horizontal direction with respect to the main surface (the surface with the largest area) of the powder, and the maximum length of the main surface of the aluminum powder is For example, if the main surface is square, it means the length of the diagonal, 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 section near the center of the powder, and the length of the minor axis of the aluminum powder is the length of the cross section in the cross section. It is the length of the line perpendicular to the major axis at the center of the figure.

The median diameter (D50) of the scale-like aluminum powder is preferably 100 μm or less, more preferably 5 μm or more, and more preferably 70 μm or less, in order to obtain a coating film having more excellent anticorrosion properties. , particularly preferably 50 μm or less.
The median diameter (D50) of the non-scale-like aluminum powder is preferably 50 μm or less, more preferably 5 μm or more, from the viewpoint of obtaining a composition having a low VOC content and excellent coating workability. It is more preferably 30 μm or less, particularly preferably 15 μm or less.
The D50 is an average value measured three times using a laser scattering diffraction particle size distribution analyzer such as "SALD 2200" (manufactured by Shimadzu Corporation).

The scaly aluminum powder may be leafing type or non-leafing type, but it is preferable to use leafing type from the viewpoint of suppressing deterioration of the coating film and deterioration of adhesion to the substrate. Moreover, when using the scale-like aluminum powder, a leafing type and a non-leafing type may be used in combination.

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

The content of the aluminum powder (B) in the present composition is 100% by mass of the solid content of the present composition, because it is possible to obtain a metallic coating film with excellent corrosion resistance and adhesion to the substrate. is preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 15% by mass or more, and preferably 35% by mass or less, more preferably 30% by mass or less.

<Antirust pigment (C)>
The rust preventive pigment (C) is not particularly limited as long as it contains a magnesium phosphate compound.
As a result of intensive studies by the present inventors, among rust-preventive pigments, for the first time when a magnesium phosphate-based compound is used, even when a coating film is formed by drying at room temperature, the metallic paint containing aluminum powder has excellent anti-corrosion properties. It was found that a heat-resistant coating film can be formed.
The rust preventive pigment (C) contained in the present composition may be of one type or two or more types. That is, the present composition may contain two or more 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/zinc phosphate, magnesium/aluminum phosphate, silica-modified magnesium phosphate, magnesium phosphite, magnesium/aluminum phosphite, magnesium/calcium phosphite, magnesium hypophosphite, magnesium polyphosphate, tripolyphosphate Magnesium, magnesium metaphosphate, and magnesium pyrophosphate.

From the viewpoint of easily obtaining a heat-resistant coating film having excellent adhesion to a substrate, the anticorrosive pigment (C) is used together with the magnesium phosphate-based compound as a zinc phosphate-based compound (magnesium phosphate-based compound It is preferable to contain a compound other than
Examples of the zinc phosphate compound include zinc phosphate, zinc phosphite, zinc hypophosphite, zinc polyphosphate, zinc tripolyphosphate, zinc metaphosphate, zinc orthophosphate, zinc pyrophosphate, and zinc phosphomolybdate. , phosphorus-zinc silicate, aluminum zinc phosphate, and calcium zinc phosphate.

As the rust preventive pigment (C), a rust preventive pigment other than the magnesium phosphate-based compound and the zinc phosphate-based compound may be used. Examples of the other rust preventive pigment include zinc powder, zinc alloy powder, calcium phosphate-based compound, aluminum phosphate-based compound, calcium phosphite-based compound, aluminum phosphite-based compound, strontium phosphite-based compound, aluminum tripolyphosphate-based compound, zinc molybdate-based compound, aluminum molybdate-based compound, Examples include cyanamide-zinc compounds, borate compounds, nitro compounds, and composite oxides.

D50 of the rust preventive pigment (C) measured using a laser diffraction particle size distribution analyzer (manufactured by Shimadzu Corporation, SALD-2200) is such that a heat-resistant coating film with excellent corrosion resistance can be obtained. From the point of view, it is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 20 μm or less, more preferably 15 μm or less.

The rust preventive pigment (C) may be a commercial product, and commercial products containing a magnesium phosphate compound include, for example, Pigmentan E (manufactured by Banner Chemicals Group UK), LF Bosei MPZ-500, LF Bosei PMG (above, Kikuchicolor Co., Ltd.), NP-1802, and NP-1902 (manufactured by Toho Pigment Industry Co., Ltd.), and commercial products containing zinc phosphate compounds include, for example, LF Bosei ZP-N ( (manufactured by Kikuchi Color Co., Ltd.).

The content of the rust preventive pigment (C) in the present composition is preferably 0.1 based on 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 obtained. % by mass or more, more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less.

The content of the magnesium phosphate-based 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, and particularly preferably 5% by mass or less is.

When the present composition contains both a magnesium phosphate compound and a zinc phosphate compound, a heat-resistant coating film having excellent adhesion to a substrate can be easily obtained. The total content of zinc acid compounds is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 20% by mass or less, relative to 100% by mass of the solid content of the present composition. More preferably, it is 15% by mass or less.
In addition, from the viewpoint of easily obtaining a heat-resistant coating film with excellent adhesion to the substrate, the content of the magnesium phosphate compound with respect to 100 parts by mass of the zinc phosphate compound is preferably 20 parts by mass. It is at least 30 parts by mass, preferably at most 80 parts by mass, and more preferably at most 70 parts by mass.

The content of the aluminum powder (B) in the present composition is such that it is possible to easily obtain a metallic-tone coating film that is excellent in well-balanced corrosion resistance, adhesion to the substrate, coating film strength, etc. It is preferably 50% by mass or more, more preferably 60% by mass or more, particularly preferably 70% by mass or more, and preferably 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 such that even when dried at room temperature, it is possible to easily form a metallic heat-resistant coating film with excellent corrosion resistance, so that the aluminum powder (B) and the magnesium phosphate-based compound 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% by mass % by mass or less, particularly preferably 15% by 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 possible to easily obtain a metallic heat-resistant coating film with excellent adhesion to the substrate. etc., relative to the total content of 100% by mass of the aluminum powder (B) and the zinc phosphate compound, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 1 % 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)>
Although the curing accelerator (D) is not particularly limited, it is preferably a material having an effect of promoting the cross-linking reaction of the siloxane binder (A). Catalysts; Aluminum curing catalysts such as aluminum metal soap; Zinc curing catalysts such as zinc metal soap; Phosphoric acid curing catalysts such as phosphoric acid and phosphoric acid esters; Tin curing catalysts such as dibutyltin dilaurate and dibutyltin diacetate bismuth-based curing catalysts such as bismuth 2-ethylhexanoate and bismuth naphthenate; and lithium-based curing catalysts such as lithium decanoate. Among these, aminosilane is preferable because, when the present composition is dried at room temperature, a heat-resistant coating film having more excellent corrosion resistance can be easily obtained. A mixture of aminosilane and alcohol is also preferred.

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. However, the compound must have at least two functional groups in the same molecule and can contribute to the improvement of adhesion to the substrate. is preferred, for example, the formula: "X- _SiMen Y _3-n " [n is 0 or 1, X is a group containing an amino group capable of reacting with an organic substance (eg, an amino group, part of a hydrocarbon group is a group substituted with an amino group, or a group in which a part of a hydrocarbon group is substituted with an ether bond or the like and a part of the group is substituted with an amino group), Me is a methyl group, and Y is 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 commercial product, and examples of such commercial products include phosphoric acid-based curing catalysts “D-220” and “X-40-2309A”, and titanium-based curing catalysts “D -25”, “D-20”, “DX-175”, aluminum curing catalysts “DX-9740” and “CAT-AC”, aminosilane “KP-390” (n of amino group-containing alkoxysilane -butanol solution), zinc-based curing catalysts "D-15" and "D-31" (both manufactured by Shin-Etsu Chemical Co., Ltd.).

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

<Other additives>
The present composition is not particularly limited as long as it contains the above (A) to (C), and if desired, within a range that does not impair the effects of the present invention, for example, other pigments other than the above (B) and (C) Other additives such as (eg, extender pigments, color pigments), dispersants, antifoaming agents, anti-sagging/anti-settling agents, dehydrating agents, and organic solvents may be included.
Each of these other additives may be used alone or in combination of two or more.

<Other Pigments>
Although the extender pigment is not particularly limited, it is preferably a heat-resistant extender pigment, and examples thereof include talc, silica, potassium feldspar, 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 the solid content of 100% by mass of the composition, from the viewpoint that it is possible to easily form a heat-resistant coating film with more excellent anticorrosion properties. It is preferably 10% by mass or more, more preferably 15% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less.

Although the coloring pigment is not particularly limited, it is preferably a coloring pigment having heat resistance.

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.
PVC in the present composition is preferably 25% or more, more preferably 30% or more, and preferably 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.
If the PVC is below the above range, the anticorrosiveness of the heat-resistant coating film formed tends to be reduced, and the adhesion of the formed coating film to the substrate tends to be reduced. On the other hand, when PVC exceeds the above range, the corrosion resistance of the formed heat-resistant coating tends to deteriorate.

The PVC refers to the total volume concentration of all pigments, including the above (B), (C) and other pigments, etc., relative to the volume of the solid content (non-volatile content) in the composition. Specifically, it can be obtained from the following formula.
PVC [%] = total volume of all pigments in this composition x 100/volume of solids in this composition

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

The volume of solids in the composition can be calculated from the mass of solids and the true density of the composition. The mass and true density of the solid content may be measured values or values calculated from 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 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>
Although the dispersant is not particularly limited, it is preferably a dispersant capable of uniformly dispersing the pigments (B), (C), and other pigments to prepare a stable dispersion.
The dispersant may be a commercial product, and examples of the commercial product include "Disperbyk-180" and "Disperbyk-2022" (both manufactured by BYK-Chemie Japan).

<Antifoaming agent>
The antifoaming agent is not particularly limited, but is a material capable of suppressing the generation of foam during production or coating of the present composition, or a material capable of breaking foam generated in the present composition. is preferred.
The antifoaming agent may be a commercial product, and examples of the commercial product include "BYK-320", "BYK-066N", and "BYK-1790" (all manufactured by BYK-Chemie Japan Co., Ltd.). .

〈Anti-sagging and anti-settling agent〉
The anti-sagging/anti-settling agent is not particularly limited, but is a material that can suppress the settling of the pigments (B) and (C) and other pigments and improve their storage stability, or during or after painting. It is preferably a material capable of improving the anti-sagging property of the coating composition.

Anti-sagging and anti-settling agents include, for example, organic thixotropic agents such as amide-based thixotropic agents, hydrogenated castor oil-based thixotropic agents, polyethylene oxide-based thixotropic agents, clay minerals such as bentonite, and synthetic finely divided silica. Among these, amide-based thixotropic agents, polyethylene oxide-based thixotropic agents, synthetic finely divided silica, and clay minerals such as bentonite are preferred.

In particular, by containing an amide-based thixotropic agent, the thixotropy is excellent, and a composition containing the amide-based thixotropic agent can easily form a thick film having a dry film thickness of 100 μm or more in one coating. In addition, even if the base material to be coated is stainless steel such as SUS304, SUS316L, etc., it has excellent adhesion to the base material, and is excellent even after exposure to a high temperature environment of 400 ° C. or higher. It is possible to easily obtain a heat-resistant coating film that maintains good adhesion.
The amide-based thixotropic agents include, for example, thixotropic agents synthesized from vegetable oil fatty acids and amines.

The anti-sagging/anti-settling agent may be a commercial product, and examples of such commercial products include amide-based thixotropic agents "Disparlon A630-20X" and "Disparlon 6650" (both manufactured by Kusumoto Kasei Co., Ltd.). ), “ASA T-250F” (manufactured by Ito Oil Oil Co., Ltd.), “Flowonon RCM-300TL” (manufactured by Kyoeisha Chemical Co., Ltd.), organically modified bentonite viscosity modifier (hectorite / 4th grade amine) "Bentone 38" (manufactured by Elementis Specialties Inc.), silicon dioxide-based thixotropic agent "Aerosil R972" (manufactured by Nippon Aerosil Co., Ltd.), polyethylene oxide-based thixotropic agent "AS- AD-120” (manufactured by Ito Oil Co., Ltd.).

When the composition contains an anti-sagging/anti-settling agent, the content of the anti-sagging/anti-settling agent is preferably 0.1 to 10% by mass relative to 100% by mass of the solid content of the composition. be.

<Organic solvent>
When this composition is applied to a plant structure that is in a high temperature state during plant operation, especially to a base material such as the outer surface of a pipe, the organic solvent content 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 high-boiling organic solvents include mineral spirits (turpentine) and isopropyl alcohol. In addition, solvents commonly used in paints can also be applied. Examples of such organic solvents include xylene, toluene, and n-butanol.

<<Heat-resistant coating and substrate with heat-resistant coating>>
A heat-resistant coating film according to one embodiment of the present invention (hereinafter also referred to as "this heat-resistant coating film") is formed from the composition described above, and a substrate with a heat-resistant coating film according to one embodiment of the present invention is A laminate comprising the present heat-resistant coating and a substrate.

The substrate is not particularly limited, and examples thereof include iron and steel (iron, steel, ferroalloy, carbon steel, alloy steel, etc.), non-ferrous metals (aluminum, etc.), metal substrates made of stainless steel, and a surface of which is coated with a shop primer or the like. Included are coated metal substrates. Further, examples of the base material include plant structures, land structures, offshore structures, ships, and the like. Plant piping is more preferable among structures. Carbon steel used for plant piping, ships, and offshore structures, or stainless steel such as SUS304 and SUS316L, which are suitably used for parts requiring cold resistance and heat resistance, are particularly preferable as the base material.

The film thickness of the present heat-resistant coating film is not particularly limited as long as it is thick enough to prevent corrosion of the base material, 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. , preferably 400 μm or less, more preferably 280 μm or less.
Since the present composition is used, even if a coating film having such a thickness is formed on a substrate, the coating film is less likely to blister or crack. Even when exposed, the base material can be protected from corrosion for a long period of time because swelling and cracking are less likely to occur.
Considering corrosion resistance, a thicker film is desirable, but in the case of an excessively thick film, the residual solvent contained in the coating film evaporates due to heating, causing swelling in the coating film or siloxane-based Structural changes due to reaction and decomposition of the binder (A) and components derived from the binder increase the internal stress of the coating film, and cracks and peeling tend to occur accordingly.

The present heat-resistant coating film is formed from the above-described present composition, and specifically, can be produced through steps including the following steps [1] and [2].
[1] A step of coating the present composition on a substrate [2] A step of drying the heat-resistant coating composition coated on the substrate to form a heat-resistant coating film

Furthermore, the present method can form a heat-resistant coating film that is more excellent in 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 of 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, etc. are preferred. Spray coating is preferable because it is excellent in workability, productivity, etc., can be easily coated on a large-area base material, and can exhibit the effects of the present invention more.
In addition, 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 coating and perform spray coating or the like.

The conditions for the spray coating may be appropriately adjusted according to the thickness of the heat-resistant coating film to be formed. Paint) Pressure: about 10 to 26 MPa, 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 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 present composition, for example, aromatic carbonized solvents such as toluene and xylene. Hydrogen-based solvents, mineral spirits, aliphatic hydrocarbon-based solvents such as cyclohexane, and alcohol-based solvents such as n-butanol, isopropanol, etc. The thinner used may be of one type or two or more types.

When the composition is applied to plant pipes, etc., it is possible to apply the composition to relatively hot pipes, etc. without stopping the operation of the plant. It will solidify before it becomes a smooth coating film, and it will be easy to paint like dust. For the purpose of suppressing this, a high boiling point organic solvent can be used as the thinner.

To remove rust, oil, moisture, dust, salt content, etc. on the substrate when the composition is applied onto the substrate, and to improve the adhesion of the obtained heat-resistant coating film to the substrate. If necessary, it is preferable to subject the substrate surface to treatment (for example, blast treatment (ISO8501-1 Sa2 1/2), treatment to remove oil and dust by degreasing), and the like. Further, the substrate 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 thickness, a coating film having a desired thickness may be formed by one coating, or a coating film having a desired thickness may be formed by coating two or more times (two or more coatings). A coating film may be formed. From the viewpoint of film thickness control and considering the residual solvent in the coating film, it is preferable to form a coating film having a desired thickness by coating two or more times.
In addition, two coatings (two coatings) refer to steps [1] and [2], and after performing step [3] if necessary, on the resulting coating film, steps [1] and [2] , It refers to a method in which step [3] is performed if necessary, and three or more coatings refers to a method in which a series of steps are repeated.

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

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

<Step [3]>
By performing the step [3], a heat-resistant coating film having higher physical and chemical resistance can be formed. That is, it becomes possible to form a heat-resistant coating film having higher coating film hardness or more excellent anti-corrosion properties.
The heating conditions in the step [3] are not particularly limited, but the heating temperature is preferably 150 to 250° C., the heating time is preferably 10 minutes or longer, more preferably 30 minutes or longer, and preferably 3 hours or less, more preferably 1 hour or less.

The present invention will be further described with reference to examples below, but the present invention is not limited to these.

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

<Adhesion evaluation>
By mixing 100 parts by mass of the prepared main component and 1.5 parts by mass of KP-390, which is a curing accelerator, a coating composition is obtained, and the obtained coating composition is subjected to SS400 sandblasting (ISO8501- 1 Sa2 1/2) was coated on a steel plate using a film applicator with a gap of 700 µm so that the dry film thickness was 250 µm.
A test piece (substrate with coating film) was prepared by drying the coating composition coated on the steel plate at 23°C for 7 days. Furthermore, in order to eliminate the influence of the parts not coated with the coating composition, the back surface and the edge part of the test piece were coated with an epoxy anticorrosion paint, and according to JIS Z 2371, neutrality was applied to each test piece. After performing a salt spray test (35 ° C.) for 3 weeks, it was washed with water and then dried for one day in an environment of 23 ° C. and 55% humidity. 9 squares) was performed.

Specifically, the cross-cut tape peeling test was performed as follows.
Using a cutter guide, the coated film of the dried test piece was cut with 4 vertical×4 horizontal cuts to a depth reaching the steel plate to form a grid of 9 squares. The interval between the cuts was 5 mm. Next, Cellotape (registered trademark) was strongly pressed against the grid portion of the coating film, and the end of the Cellotape was quickly peeled off at an angle of 90° to the coating film surface. After that, the remaining area ratio (%), which is the area of the coating film remaining on the steel plate, was calculated with respect to the area of the 9 squares, and the adhesion was evaluated based on the value of the remaining area ratio (%).
A case where the residual area ratio (%) was less than 50% was evaluated as poor (X), and a case where the residual area ratio (%) was 50% or more was evaluated as good adhesion (○).

<Corrosion resistance evaluation>
Test pieces were prepared as described in (1) to (3) below, and each test piece was subjected to the following salt spray test (4) for evaluation.

(1) Unheated test piece 100 parts by mass of the prepared base component and 1.5 parts by mass of the curing accelerator KP-390 are mixed to obtain a coating composition, and the obtained coating The composition was adjusted using xylene so that the viscosity at 23° C. measured using the Brookfield viscometer was 2 Pa·s.
The viscosity-adjusted coating composition was applied onto a SS400 sandblasted (equivalent to ISO8501-1 Sa2 1/2) steel plate using a film applicator with a gap of 700 µm so that the dry film thickness was 250 µm.
Thereafter, the coating composition coated on the steel plate was dried at 23° C. for 7 days to prepare an unheated test piece (substrate with coating film).

(2) Heat cycle test piece (300°C heating + rapid cooling)
A test piece obtained in the same manner as the unheated test piece (1) was placed in an electric oven and heated at 300° C. for 1.5 hours, then removed from the oven and immediately immersed in ice water for 10 seconds to rapidly cool. The specimen was then removed from the ice water and left at room temperature for 30 minutes. A heat cycle test piece was prepared by performing 3 cycles of heating and quenching as one cycle.

(3) Heat resistance test piece (heated at 550°C)
A test piece obtained in the same manner as in the (1) unheated test was placed in a muffle furnace, heated at 550° C. for 4 hours, and then allowed to cool, thereby preparing a heat resistance test piece.

(4) Salt spray test In each of the test pieces prepared in (1) to (3) above, in the locations shown in FIG. In order to eliminate the influence of the parts not coated with the coating composition, the back surface and edge of the test piece were coated with an epoxy anticorrosion paint, and each test piece was sprayed with neutral salt water according to JIS Z 2371. The test (35°C) was conducted for 3 weeks, and the creep width of the part to be evaluated (the length between the farthest point from the scribed part and the scribed part in the part where the paint film and the steel plate were separated) was measured. , was evaluated according to the following evaluation criteria. Here, the "part to be evaluated" refers to the part excluding the range of 1 cm from the edge 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 △: Creep width in the evaluation target part is 10 mm or more and less than 20 mm ×: Creep in the evaluation target part 20 mm or more in width

Claims (6)

A heat-resistant paint composition,
The heat-resistant paint composition contains a siloxane-based binder (A), aluminum powder (B), and an antirust pigment (C) containing a magnesium phosphate-based compound,
The siloxane-based binder (A) contains a silicone resin (A1), a silicone oligomer (A2) and an ethyl silicate (A3),
The silicone resin (A1) is a compound other than the ethyl silicate (A3) and has a weight average molecular weight of 15,000 or more,
The silicone oligomer (A2) is a compound other than the ethyl silicate (A3) and has a weight average molecular weight of less than 15,000,
The content of the aluminum powder (B) is 10% by mass or more with respect to 100% by mass of the solid content of the heat-resistant coating composition,
The rust preventive pigment (C) further contains a zinc phosphate compound,
Heat-resistant paint composition. The heat-resistant coating composition according to claim 1 , further comprising a curing accelerator (D). 3. The heat-resistant paint composition according to claim 1 , wherein the pigment volume concentration is 25-55%. A heat-resistant coating film formed from the heat-resistant coating composition according to any one of claims 1 to 3 . A substrate with a heat-resistant coating comprising a substrate and the heat-resistant coating according to claim 4 . A method for producing a substrate with a heat-resistant coating, comprising the following steps [1] and [2].
[1] A step of coating a substrate with the heat-resistant coating composition according to any one of claims 1 to 3. [2] A step of drying the coated heat-resistant coating composition to form a heat-resistant coating film.

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