CN113993638A

CN113993638A - Heat-resistant coating composition, heat-resistant coating film, substrate with heat-resistant coating film, and method for producing same

Info

Publication number: CN113993638A
Application number: CN202080042269.XA
Authority: CN
Inventors: 高桥英树; 引地康人; 村田浩章
Original assignee: Chugoku Marine Paints Ltd
Current assignee: Chugoku Marine Paints Ltd
Priority date: 2019-07-03
Filing date: 2020-06-03
Publication date: 2022-01-28
Anticipated expiration: 2040-06-03
Also published as: WO2021002139A1; JP7329599B2; JPWO2021002139A1; KR20220019109A; CN113993638B

Abstract

One embodiment of the present invention relates to a heat-resistant coating composition comprising a siloxane-based binder (a), aluminum powder (B), and a rust-preventive pigment (C) containing a magnesium phosphate-based compound, a heat-resistant coating film, a substrate with a heat-resistant coating film, or a method for producing the same.

Description

Heat-resistant coating composition, heat-resistant coating film, substrate with heat-resistant coating film, and method for producing same

Technical Field

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

Background

In many cases, a heat insulating material is provided around a pipe (steel pipe) in order to prevent heat dissipation to the outside air or heat absorption from the outside air and suppress energy consumption in the pipe of a plant structure or the like. However, rainwater entering the gap between the heat insulating material and the steel (for example, carbon steel or low alloy steel) pipe or water condensed at the position may form a water film on the surface of the steel pipe, and cause Corrosion Under the heat insulating material (CUI). The CUI means that corrosion cells are formed on the surface of the steel pipe by the water film, and local corrosion attack occurs. Since the corrosion rate is faster than general corrosion occurring in the outdoor atmosphere, it is a major problem in maintenance and management of a plant structure.

Further, in the CUI, since the corrosion-etched portion is under the heat insulating material (surrounded by the heat insulating material), moisture once intruded may easily remain and the wet state may be maintained for a long period of time, and the pipe is exposed to a high temperature depending on the operation condition of the plant, so that the progress of corrosion as an oxidation reaction may be promoted, and further, since the plant structure is often installed in a seashore region where sea salt particles which may form a corrosion factor are abundant, the progress of corrosion may be promoted by the sea salt particles, and the corrosion etching may be easily aggravated, which is also problematic.

Therefore, pipes used in plant structures and the like are provided with an anticorrosive coating (heat-resistant coating) on their outer surfaces for the purpose of preventing the above corrosion and the like. The anticorrosive coating film is provided not only on the heat insulating material but also on the portion of the outer surface of the pipe where the heat insulating material is not provided for the purpose of preventing corrosion and the like as described above. Such an anticorrosive coating film provided on the outer surface of the pipe, particularly on the portion where the heat insulating material is not provided, is preferably a silver-colored anticorrosive coating film (metal coating film) in view of its design property and the like.

Further, since pipes used in plant structures and the like are exposed to various temperature environments depending on the operating conditions of the plants and the like, heat-resistant temperature or heating-resistant cooling cycle conditions required for an anticorrosive coating (heat-resistant coating) used for the pipes are also in a wide range, and for example, resistance to a wide temperature range of-198 ℃ to 500 ℃ or higher is sometimes required.

As a composition capable of forming a metal coating film having heat resistance and corrosion resistance, patent document 1 discloses a coating composition containing polysiloxane, alkyl titanate, talc, and aluminum sheet.

Documents of the prior art

Patent document

Patent document 1: japanese Kokai publication 2009-522388

Disclosure of Invention

Technical problem to be solved by the invention

The inventors of the present invention have made extensive studies and as a result, found that an anticorrosive coating film formed from a conventional coating composition containing an aluminum pigment may have insufficient anticorrosive properties. It is known that, depending on the type and use of the pipe, when a coating film (metal coating film) is formed on the pipe, sufficient heat curing may not be performed, and in such a case, particularly, corrosion resistance is insufficient.

In addition, when a heat-resistant coating film is formed on each material such as a steel pipe, heat drying (baking) may be performed, but the production cost increases due to an increase in the number of steps, energy for heating, and the like. Therefore, there is a need for a coating composition which can form a heat-resistant coating film having sufficient coating film properties such as corrosion resistance required even when the coating film is formed by drying at room temperature (5 to 40 ℃).

In addition, when the heat-resistant coating film formed on the outer surface of the pipe of the plant structure or the like that can be exposed to an ultra high temperature of 500 ℃ or higher is a thick film having a thickness of 100 μm or more, the heat-resistant coating film is likely to expand and crack due to the high-temperature environment and repetition of temperature changes. More specifically, when the heat-resistant coating film is exposed to a high temperature, expansion due to gas generated by volatilization of a residual solvent in the coating film, reaction and decomposition of a silicone resin component constituting the coating film, and the like may occur, and cracks may also occur due to increase in internal stress of the coating film due to reaction and decomposition of the silicone resin component. These coating defects are likely to occur particularly when the coating is applied as a thick film, and therefore, the thickness of the heat-resistant coating film obtained from the conventional silicone resin heat-resistant coating material is usually less than 80 μm, and it is difficult to achieve a coating specification of a thick film of 100 μm or more.

However, it is known that CUI is a major problem in maintenance and management in pipes of a plant structure or the like, and a thin film of less than 80 μm as described above cannot maintain corrosion resistance for a long period of time in a severe corrosive environment.

One embodiment of the present invention provides a heat-resistant coating composition which exhibits excellent corrosion resistance without heating when forming a coating film, and which can form a heat-resistant coating film (metal coating film) capable of maintaining sufficient heat resistance, corrosion resistance, and adhesion to a substrate even at a wide range of temperatures including high temperatures.

Technical solution for solving technical problem

The present invention has been accomplished by finding that the above-described technical problems can be solved by the following configuration examples.

The constitution of the present invention is as follows.

< 1 > a heat-resistant coating composition comprising a siloxane-based binder (A), an aluminum powder (B) and an anticorrosive 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.

A heat-resistant coating composition as described in < 3 > such as < 1 > or < 2 > which further comprises a curing accelerator (D).

The heat-resistant coating composition of any one of < 4 > to < 1 > -3 > wherein the Pigment Volume Concentration (PVC) is 25 to 55%.

< 5 > a heat-resistant coating film formed from the heat-resistant coating composition described in any one of < 1 > to < 4 >.

< 6 > a substrate having a heat-resistant coating film attached thereto, comprising a substrate and < 5 > said heat-resistant coating film.

< 7 > A method for producing a substrate having a heat-resistant coating film, which comprises the following steps [1] and [2 ].

[1] Applying the heat-resistant coating composition described in any one of (1) to (4) to a substrate;

[2] and drying the coated heat-resistant coating composition to form a heat-resistant coating film.

Effects of the invention

According to one embodiment of the present invention, a heat-resistant coating composition can be provided which exhibits excellent corrosion resistance without heating when forming a coating film, and can form a heat-resistant coating film (metal coating film) that can maintain sufficient heat resistance, corrosion resistance, and adhesion to a substrate even at a wide range of temperatures including high temperatures (e.g., 500 ℃ or higher).

Drawings

Fig. 1 is a schematic plan view of a test piece with a scribe line used for evaluating the corrosion resistance of the examples.

Detailed Description

Heat-resistant coating composition

A heat-resistant coating composition according to an 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 rust-preventive pigment (C) containing a magnesium phosphate-based compound.

The present composition contains the above (a) and (C) together with the above (B), and is a metallic coating composition containing an aluminum powder, and can give a heat-resistant coating film having sufficient corrosion resistance even when a coating film is formed by drying at room temperature, and further, the present composition can give a heat-resistant coating film having: the dry film thickness is 100 μm or more, and the corrosion resistance and the adhesion to the substrate can be maintained even after the film is exposed to a high temperature environment exceeding 500 ℃.

In addition, the composition can form a heat-resistant coating film having excellent adhesion particularly to stainless steel (for example, SUS304, SUS316L, etc.) which has a larger linear expansion coefficient than carbon steel and is suitable for use in a case where the composition is supposed to be exposed to a high-temperature environment of 400 ℃ or higher.

Therefore, the composition is suitable for use on the outer surface of pipes for plant structures and the like provided with a heat insulating material, which are supposed to operate under various temperature conditions, and is suitable for use as a coating material capable of forming a heat-resistant/anticorrosive coating film suitable for suppressing CUI.

The present composition is not particularly limited as long as it contains the above-mentioned components (a) to (C), and if necessary, other additives other than the above-mentioned components (a) to (C), for example, a curing accelerator (D), pigments other than the above-mentioned components (B) and (C), a dispersing agent, an antifoaming agent, an anti-sagging agent, an anti-settling agent, a dehydrating agent, and an organic solvent may be contained within a range not to impair the effects of the present invention.

The present composition may be a one-component type composition or a two-component type or more composition.

In view of easily obtaining a heat-resistant coating film excellent in corrosion resistance even when dried at room temperature, the present composition preferably contains a curing accelerator (D), and in this case, a two-component type composition comprising the main component (a) to (C) and a component containing the curing accelerator (D) is preferred.

When the composition is a two-component type or more composition, the components used in the composition are usually stored, transported, and the like in separate containers, and are mixed before use.

< Silicone-based adhesive (A) >

The silicone adhesive (a) is not particularly limited as long as it is a compound having a siloxane bond. The silicone adhesive (A) is also a silicone adhesive.

In the present composition, the siloxane-based binder (a) is used as the binder, and therefore a heat-resistant coating film particularly excellent in heat resistance can be obtained.

The silicone adhesive (a) contained in the present composition may be 1 type, or 2 or more types.

Examples of the silicone adhesive (a) include compounds having reactive groups in the molecule via siloxane bonds, and curing the reactive groups by reacting with each other to form a high molecular weight or three-dimensional crosslinked structure.

The above reaction includes, for example, a condensation reaction and an addition reaction, and the condensation reaction includes, for example, a dehydration reaction and a dealcoholization reaction.

The silicone adhesive (a) is preferably a compound represented by the following formula (I), and preferably contains the following silicone resin (a1), silicone oligomer (a2), and/or ethyl silicate (A3).

In particular, the present composition preferably contains a silicone resin (a1) as the silicone binder (a) in order to obtain a heat-resistant coating film having more excellent heat resistance and corrosion resistance, and is more preferably used in combination with a silicone oligomer (a2) having a low weight average molecular weight and ethyl silicate (A3) for the purpose of adjusting the properties of the coating material and the coating film performance.

The silicone adhesive (a) may be linear or branched.

(in the formula (I), R¹Each 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), R²Each 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 a repetition number, and the weight average molecular weight of the siloxane adhesive is in a range of 200 to 300,000And (4) selecting. )

As the above-mentioned R¹And R²Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group and a pentyl group.

R is as defined above¹And R²The aryl group having 6 to 8 carbon atoms may have 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.

As the above-mentioned R¹Examples of the-OR of (2) include methoxy, ethoxy, propoxy and phenoxy.

The weight average molecular weight (hereinafter also simply referred to as "Mw") of the silicone adhesive (a) in terms of standard polystyrene, as measured by GPC (gel permeation chromatography), is preferably 200 or more, more preferably 400 or more, preferably 300,000 or less, and more preferably 200,000 or less.

Specifically, the Mw can be measured by the method described in the following examples.

The content of the silicone binder (a) is preferably 20% by mass or more, 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, based on 100% by mass of the solid content of the present composition, from the viewpoint of obtaining a heat-resistant coating film having more excellent corrosion resistance and heat resistance.

< Silicone resin (A1) >)

The silicone resin (a1) is not particularly limited as long as it is a compound other than ethyl silicate (A3) described later, but is preferably a compound represented by the formula (I), more preferably R in the formula (I)¹A compound which is a methyl group, an ethyl group, a propyl group or a phenyl group, and further, R in the formula (I) is more preferable²A methyl group, an ethyl group, a phenyl group or a hydrogen atom.

When the present composition contains the silicone resin (a1), the silicone resin (a1) may be 1 kind, or 2 or more kinds.

The silicone resin (a1) is preferably a heat-resistant resin such as a methyl silicone resin or a methylphenyl silicone resin, and more preferably contains 1 or more structural units selected from the following dimethylsiloxane unit (a1), diphenylsiloxane unit (a2), monomethylsiloxane unit (a3), monopropylsiloxane unit (a4), and monophenylsiloxane unit (a 5).

(in the formulae (a1) to (a5), "-" bonded to O but not bonded to Si in Si-O-represents a bond, and Si-O-does not necessarily mean Si-O-CH₃。)

The Mw of the silicone resin (a1) is 15,000 or more, preferably 18,000 or more, 300,000 or less, preferably 200,000 or less, from the viewpoint of obtaining a heat-resistant coating film having more excellent heat resistance and corrosion resistance.

Since the silicone resin (a1) having Mw greater than the above range has high viscosity, it is often necessary to dilute the silicone resin (a1) with an organic solvent or the like in order to reduce the viscosity of the present composition containing such a silicone resin in view of workability. As a result, the solvent content in the composition may increase, and the VOC (Volatile Organic compound) in the composition may not be reduced.

The silicone resin (a1) can be synthesized by a conventionally known synthesis method, or can be a commercially available product. Examples of the commercially available products include "SILRES REN 60", "SILRES REN 80" (both manufactured by Wacker Asahi Kasei Chemicals Co., Ltd.) and "SILIKOPHEN P80/X" (manufactured by Evonik Co., Ltd.).

When the present composition contains the silicone resin (a1), the content of the silicone resin (a1) 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 42% by mass or less, relative to 100% by mass of the solid content of the present composition, from the viewpoint of obtaining a heat-resistant coating film having more excellent corrosion resistance and heat resistance.

< Silicone oligomer (A2) >)

The silicone oligomer (a2) is not particularly limited as long as it is a compound other than ethyl silicate (A3) described below, and is preferably a compound having the same structure as the structure listed in the column of the silicone resin (a 1).

The 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 number of the silicone oligomer (a2) may be 1, or 2 or more.

The silicone oligomer (a2) can be synthesized by a conventionally known synthesis method or can be a commercially available product. Examples of the commercially available products include "SILRES MSE 100" (manufactured by Wacker Asahi Kasei Silicone Co., Ltd.) and "KR-401N" (manufactured by shin-Etsu chemical industry Co., Ltd.).

When the present composition contains the silicone oligomer (a2), the content of the silicone oligomer (a2) 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 or less, and particularly preferably 10% by mass or less, relative to 100% by mass of the solid content of the present composition, from the viewpoint of obtaining a heat-resistant coating film having more excellent corrosion resistance and heat resistance.

< 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 composition contains ethyl silicate (A3), the number of ethyl silicate (A3) may be 1 or 2 or more.

(in the formula (II), n is 1 to 10.)

Ethyl silicate (a3) can be synthesized by a conventionally known synthesis method, or can be a commercially available product. Examples of the commercially available products include "Ethyl Silicate 40" (manufactured by collet corporation) and "Wacker Silicate TES 40 WN" (manufactured by Wacker Kasei Cork) which are oligomers having a molecular weight distribution centered on a pentamer.

When the present composition contains ethyl silicate (A3), the content of ethyl silicate (A3) is preferably 1 mass% or more, more preferably 2 mass% or more, preferably 20 mass% or less, and even more preferably 15 mass% or less, based on 100 mass% of the solid content of the present composition, from the viewpoint of obtaining a coating composition excellent in coating workability, cost reduction, and dehydration effect during storage.

When the present composition contains the above (a1) and/or (a2) and (A3), the ratio (a1+ a 2: A3) of the total content of the silicone resin (a1) and the silicone oligomer (a2) to the content of ethyl silicate (A3) in the present composition is preferably 95: 5 to 60: 40, from the viewpoint that a heat-resistant coating film having more excellent heat resistance and corrosion resistance can be obtained.

When the present composition contains the above (a1) and (a2) and/or (A3), the ratio of the content of the silicone resin (a1) to the total content of the silicone oligomer (a2) and the ethyl silicate (A3) (a 1: a2+ A3) in the present composition is preferably 90: 10 to 30: 70, and more preferably 90: 10 to 40: 60, from the viewpoint that a heat-resistant coating film having excellent heat resistance and corrosion resistance can be obtained.

< aluminum powder (B) >

The powdery aluminum (B) is not particularly limited, and may be a scaly powdery aluminum or a non-scaly powdery aluminum other than scaly aluminum, and is preferably a scaly powdery aluminum in view of more easily obtaining a heat-resistant coating film having a metallic feeling. Further, by using the flaky aluminum powder, an anticorrosive coating film having more excellent salt water resistance, moisture resistance, and the like can be formed.

In addition, as a raw material for preparing the composition, not only powder but also paste-like aluminum may be used.

The powdery aluminum (B) contained in the present composition may be 1 kind or 2 or more kinds.

The "scaly" refers to a shape having a scale shape, and does not have a specific range, and the aspect ratio is usually preferably 5 or more, more preferably 10 or more, further preferably 20 or more, preferably 150 or less, and more preferably 120 or less.

The "non-scaly" is a shape having a shape other than a scaly shape such as a sphere, a teardrop, a spindle, or the like, and there is no particular limitation, and the aspect ratio is usually preferably less than 5, more preferably 1 or more, and more preferably 3 or less.

The aspect ratio can be measured by an electron microscope. The average value of the ratio (maximum length/thickness of the main surface or length of the major axis/length of the minor axis) of the thicknesses of the powder particles and the maximum length of the main surface (or length of the major axis and length of the minor axis) of the powder particles of 10 to 100 numbers can be calculated by observing the aluminum powder using a Scanning Electron Microscope (SEM) such as "XL-30" (trade name; manufactured by Philips).

The thickness of the powdery aluminum can be measured by observing the main surface (the surface having the largest area) of the powdery aluminum from the horizontal direction, and the maximum length of the main surface of the powdery aluminum means the length of the diagonal line when the main surface is square, the diameter when the main surface is circular, and the length of the major axis when the main surface is elliptical, for example. Specifically, the length of the major axis of the powdery aluminum is the longest length in a cross-sectional view near the center of the powder, and the length of the minor axis of the powdery aluminum is the length of a line orthogonal to the major axis at the center of the cross-sectional view in the cross-sectional view.

The median particle diameter (D50) of the above-mentioned flaky aluminum powder is preferably 100 μm or less, more preferably 5 μm or more, still more preferably 70 μm or less, and particularly preferably 50 μm or less, from the viewpoint of obtaining a coating film having more excellent corrosion resistance.

The median particle diameter (D50) of the non-flaky powdery aluminum is preferably 50 μm or less, more preferably 5 μm or more, more preferably 30 μm or less, and particularly preferably 15 μm or less, from the viewpoint of obtaining a composition excellent in coating workability with a low VOC content.

The D50 is an average value obtained by 3 measurements using a laser scattering diffraction particle size distribution measuring apparatus, for example, "SALD 2200" (manufactured by Shimadzu corporation).

The above-mentioned powdery aluminum flakes may be leafing (leafing) type or non-leafing type, and the leafing type is preferably used from the viewpoint of suppressing the deterioration of the coating film and the deterioration of the adhesion to the substrate. When the above-mentioned flaky aluminum powder is used, a leafing type and a non-leafing type can be used in combination.

The non-flaky aluminum powder is preferably an aluminum powder produced by an atomization method (spray method).

The content of the powdery aluminum (B) in the present composition is preferably 5 mass% or more, more preferably 10 mass% or more, particularly preferably 15 mass% or more, preferably 35 mass% or less, and more preferably 30 mass% or less with respect to 100 mass% of the solid content of the present composition, from the viewpoint of obtaining a coating film having a metallic feel and more excellent in corrosion resistance and adhesion to a substrate.

< anti-rust pigment (C) >

The rust preventive pigment (C) is not particularly limited as long as it contains a magnesium phosphate compound.

The inventors of the present invention have made extensive studies and found that a heat-resistant coating film having excellent corrosion resistance can be formed from a metallic paint containing aluminum powder only when a coating film is formed by drying at room temperature using a magnesium phosphate compound as a rust preventive pigment.

The number of the rust preventive pigments (C) contained in the present composition may be 1 or 2 or more. That is, the composition may contain 2 or more magnesium phosphate compounds.

Examples of the magnesium phosphate-based compound include magnesium phosphate, magnesium ammonium phosphate, magnesium monohydrogen phosphate, magnesium dihydrogen phosphate, calcium magnesium phosphate, cobalt magnesium phosphate, nickel magnesium phosphate, zinc magnesium phosphate, aluminum magnesium phosphate, silica-modified magnesium phosphate, magnesium phosphite, aluminum magnesium phosphite, calcium magnesium phosphite, magnesium hypophosphite, magnesium polyphosphate, magnesium tripolyphosphate, magnesium metaphosphate, and magnesium pyrophosphate.

The rust-preventive pigment (C) preferably contains a zinc phosphate compound (a compound other than the magnesium phosphate compound) together with the magnesium phosphate compound, in view of easily obtaining a heat-resistant coating film having more excellent adhesion to the substrate.

Examples of the zinc phosphate compound include zinc phosphate, zinc phosphite, zinc hypophosphite, zinc polyphosphate, zinc tripolyphosphate, zinc metaphosphate, zinc orthophosphate, zinc pyrophosphate, zinc phosphomolybdate, zinc silicophosphate, zinc aluminum phosphate, and calcium zinc phosphate.

As the rust preventive pigment (C), other rust preventive pigments other than the magnesium phosphate-based compound and the zinc phosphate-based compound can be used, and examples of the other rust preventive pigments 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, zinc cyanamide-based compound, borate compound, nitro compound, and composite oxide.

In view of obtaining a heat-resistant coating film having more excellent corrosion resistance, D50 of the rust preventive pigment (C) measured by a laser diffraction particle size distribution measuring apparatus (SALD-2200, manufactured by Shimadzu corporation) is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 20 μm or less, and still more preferably 15 μm or less.

The rust-preventive pigment (C) may be a commercially available product, and examples of commercially available products containing magnesium phosphate compounds include Pigmentan E (manufactured by Banner Chemicals Group UK), LF BOWSEI MPZ-500, LF BOWSEI PMG (manufactured by KIKUCHI COLOR, Inc.), NP-1802, and NP-1902 (manufactured by Toho pigment industries, Inc.), and examples of commercially available products containing zinc phosphate compounds include LF BOWSEI ZP-N (manufactured by KIKUCHI COLOR, Inc.).

The content of the rust preventive pigment (C) in the present composition is preferably 0.1% 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, relative to 100% by mass of the solid content of the present composition, from the viewpoint of obtaining a heat-resistant coating film having more excellent corrosion resistance.

The content of the magnesium phosphate-based compound in the present composition is preferably 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, relative to 100% by mass of the solid content of the present composition, from the viewpoint of easily forming a heat-resistant coating film excellent in corrosion resistance even when dried at room temperature, and the like.

When the magnesium phosphate compound and the zinc phosphate compound are used in combination in the present composition, the total content of the magnesium phosphate compound and the zinc phosphate compound is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, preferably 20% by mass or less, and more preferably 15% by mass or less, based on 100% by mass of the solid content of the present composition, from the viewpoint of easily obtaining a heat-resistant coating film having more excellent adhesion to a substrate.

In addition, the content of the magnesium phosphate compound is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, preferably 80 parts by mass or less, and more preferably 70 parts by mass or less, relative to 100 parts by mass of the zinc phosphate compound, from the viewpoint of easily obtaining a heat-resistant coating film having more excellent adhesion to a substrate.

The content of the powdery aluminum (B) in the present composition is preferably 50 mass% or more, more preferably 60 mass% or more, particularly preferably 70 mass% or more, preferably 99 mass% or less, more preferably 90 mass% or less, and particularly preferably 80 mass% or less, with respect to 100 mass% of the total content of the powdery aluminum (B) and the rust preventive pigment (C), from the viewpoint of easily obtaining a coating film having a metallic feel with an excellent balance among corrosion resistance, adhesion to a substrate, coating film strength, and the like.

The content of the magnesium phosphate compound in the present composition is 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 or less, and particularly preferably 15% by mass or less, relative to 100% by mass of the total content of the powdery aluminum (B) and the magnesium phosphate compound, from the viewpoint of easily forming a heat-resistant coating film having a metallic feeling excellent in corrosion resistance even when dried at room temperature.

When the present composition contains a zinc phosphate-based compound, the content of the zinc phosphate-based compound in the present composition is 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, relative to 100% by mass of the total content of the powdery aluminum (B) and the zinc phosphate-based compound, from the viewpoint of easily obtaining a heat-resistant coating film having a metallic feel and further excellent adhesion to a substrate.

< curing Accelerator (D) >)

The curing accelerator (D) is not particularly limited, but is preferably a material having an effect of accelerating the crosslinking reaction of the silicone adhesive (a), and examples thereof include: an aminosilane; titanium curing catalysts such as titanium alkoxides and titanium chelates; an aluminum-based catalyst for curing such as a metallic soap of aluminum; zinc-based curing catalysts such as metal soaps of zinc; phosphoric acid-based curing catalysts such as phosphoric acid and phosphoric acid esters; tin-based curing catalysts such as dibutyltin dilaurate and dibutyltin diacetate; bismuth-based curing catalysts such as bismuth 2-ethylhexanoate and bismuth naphthenate; lithium-based curing catalysts such as lithium decanoate. Among these, aminosilane is preferable because a heat-resistant coating film having more excellent corrosion resistance can be easily obtained when the present composition is dried at room temperature. In addition, a mixture of an aminosilane and an alcohol is also preferred.

The aminosilane is preferably a silane coupling agent containing an amino group. The silane coupling agent is not particularly limited, and a conventionally known compound, preferably a compound having at least 2 functional groups in the same molecule and contributing to improvement of adhesion to a substrate, can be used, and for example, more preferably a compound represented by the formula: "X-SiMe_nY_3-n"[ n represents 0 or 1, X represents an amino group-containing group capable of reacting with an organic substance (for example, an amino group, a group in which a part of a hydrocarbon group is 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 amino group is substituted with an amino group),", Me represents a methyl group, and Y represents a hydrolyzable group (for example, an alkoxy group such as a methoxy group or an ethoxy group).]The compounds shown.

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

When the present composition contains the curing accelerator (D), the content of the curing accelerator (D) is preferably 0.01% by mass or more, more preferably 0.5% by mass or more, preferably 5% by mass or less, and still more preferably 3% by mass or less, based on 100% by mass of the solid content of the present composition, from the viewpoint of easily forming a heat-resistant coating film excellent in corrosion resistance even when dried at room temperature.

< other additives >

The present composition is not particularly limited as long as it contains the above-mentioned components (A) to (C), and if necessary, may contain other additives such as other pigments (e.g., extender pigments, coloring pigments), dispersing agents, defoaming agents, sagging preventing agents, sedimentation preventing agents, dehydrating agents, organic solvents, etc., other than the above-mentioned components (B) and (C), within a range not impairing the effects of the present invention.

These other additives may be 1 kind or 2 or more kinds, respectively.

< other pigments >

The extender pigment is not particularly limited, but is preferably a heat-resistant extender pigment, and examples thereof include talc, silica, potash feldspar, barium sulfate, zinc oxide, calcium carbonate, kaolin, and alumina.

When the present composition contains an extender pigment, the content of the extender pigment 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, relative to 100% by mass of the solid content of the present composition, from the viewpoint of easily forming a heat-resistant coating film having more excellent corrosion resistance.

The above-mentioned coloring Pigment is not particularly limited, and preferable coloring pigments having heat resistance include, for example, Pigment Black 28 (Copper chromium Black), stainless steel flake, titanium white, carbon Black, and iron red.

The other Pigment is preferably used in an amount such that the Pigment Volume Concentration (PVC) in the present composition falls within the following range.

The PVC in the present composition is preferably 25% or more, more preferably 30% or more, preferably 55% or less, more preferably 50% or less, further preferably 45% or less, further preferably 43% or less, and particularly preferably 40% or less, from the viewpoint of obtaining a heat-resistant coating film having more excellent corrosion resistance and more excellent adhesion to a substrate.

When PVC is less than the above range, the corrosion resistance of the formed heat-resistant coating film tends to decrease, and the adhesion of the formed coating film to the substrate also tends to decrease. When PVC is higher than the above range, the corrosion resistance of the heat-resistant coating film formed tends to be lowered.

The PVC is the volume concentration of the total of all pigments including the (B) and (C) and other pigments, based on the volume of the solid content (nonvolatile content) in the present composition, and can be specifically determined by the following formula.

PVC [% ] -the sum of the volumes of all pigments in the composition multiplied by 100/volume of the solid content in the composition

Here, in the present specification, the solid content of the present composition means a heating residue obtained in accordance with JIS K5601-1-2 (heating temperature: 125 ℃ C., heating time: 60 minutes). The solid content of the present composition can also be calculated as the amount of the solvent and the organic solvent excluding the raw materials used.

The volume of the solid content in the present composition can be calculated from the mass and the true density of the solid content in the present composition. The mass and true density of the solid matter 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, the mass and true density of the separated pigment 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, and is preferably a dispersant capable of uniformly dispersing the above (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" (manufactured by BYKChemi Japan, Inc.).

< antifoam agent >

The defoaming agent is not particularly limited, and is preferably a material capable of suppressing the generation of bubbles during the production of the present composition or during the coating, or a material capable of breaking bubbles generated in the present composition.

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 BYKChemi Japan, Inc.).

< anti-sagging, anti-settling agent >

The anti-sagging/anti-settling agent is not particularly limited, but is preferably a material capable of inhibiting the sedimentation of the pigments (B) and (C) and other pigments to improve the storage stability thereof, or a material capable of improving the anti-sagging property of the coating composition at the time of coating or after coating.

Examples of the anti-sagging/anti-settling agent include organic thixotropic agents such as amide thixotropic agents, hydrogenated castor oil thixotropic agents, and polyethylene oxide thixotropic agents, clay minerals such as bentonite, and inorganic thixotropic agents such as synthetic fine powder silica, and among these, amide thixotropic agents, polyethylene oxide thixotropic agents, synthetic fine powder silica, and clay minerals such as bentonite are preferable.

In particular, the amide thixotropic agent is excellent in thixotropy, and a composition containing the amide thixotropic agent can easily form a thick film having a dry film thickness of 100 μm or more by 1-time coating, and can easily obtain the following heat-resistant coating film: even if the substrate to be coated is stainless steel such as SUS304 or SUS316L, the coating composition has excellent adhesion to the substrate and maintains excellent adhesion even after exposure to a high-temperature environment of 400 ℃.

Examples of the amide thixotropic agent include thixotropic agents synthesized from vegetable oil fatty acids and amines.

The anti-sagging/anti-settling agent may be a commercially available product, and examples of the commercially available product include "disparon a 630-20X", "disparon 6650" (both manufactured by miao chemical corporation), "a-S-A T-250F" (manufactured by imitations oil (ltd), "FLOWNON RCM-300 TL" (manufactured by coohno chemical corporation), "Bentone 38" (manufactured by Elementis Specialties inc., ltd.) as an organic modified bentonite viscosity modifier (hectorite/quaternary amine), "Aerosil R972" (manufactured by japan Aerosil (ltd.), and "a-S-A D-120" (manufactured by imitations oil (ltd.)) as an amide thixotropic agent.

When the composition contains the sagging/settling preventing agent, the content of the sagging/settling preventing agent is preferably 0.1 to 10% by mass based on 100% by mass of the solid content of the composition.

< organic solvent >

When the composition is applied to a plant structure in a high-temperature state during plant operation, particularly to a substrate such as the outer surface of a pipe, the organic solvent is partially volatilized by the heat of the substrate surface, and it is difficult to form a good coating film. 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 may also be used. Examples of such an organic solvent include xylene, toluene, and n-butanol.

Heat-resistant coating film and substrate with heat-resistant coating film

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

The substrate is not particularly limited, and examples thereof include a metal substrate made of steel (iron, steel, alloyed iron, carbon steel, alloy steel, etc.), nonferrous metal (aluminum, etc.), stainless steel, and a metal substrate whose surface is covered with a primer for precoating. The base material may be a plant structure, a land structure, an offshore structure, a ship, or the like, and from the viewpoint of further exhibiting the effects and the like of the present invention, a plant structure is preferable, and plant piping is more preferable in a plant structure. As the base material, in particular, carbon steel used for plant pipes, ships, and marine structures, or stainless steel such as SUS304 and SUS316L suitable for use in parts requiring cold resistance and heat resistance is more preferable.

The thickness of the heat-resistant coating film is not particularly limited as long as it is a thickness enough to prevent corrosion of the substrate, and is preferably 30 μm or more, more preferably 50 μm or more, still more preferably 100 μm or more, particularly preferably 150 μm or more, preferably 400 μm or less, and more preferably 280 μm or less.

By using the present composition, even if a coating film having such a thickness is formed on a substrate, the coating film is less likely to expand and crack, and particularly, is less likely to expand and crack even when exposed to a high temperature of 500 ℃ or higher and a rapid temperature change, and therefore, corrosion of the substrate can be prevented for a long period of time.

In addition, in the case of an excessively thick film, the film tends to be easily cracked or peeled off when the internal stress of the film increases due to a structural change caused by a reaction or decomposition between the silicone-based binder (a) and a component derived from the binder, or due to a swelling of the film caused by volatilization of a residual solvent or the like contained in the film caused by heating.

The heat-resistant coating film is formed from the present composition described above, and specifically can be produced through a process including the following steps [1] and [2 ].

[1] Coating the composition on a substrate;

[2] and drying the heat-resistant coating composition applied to the substrate to form a heat-resistant coating film.

Further, the method can form a heat-resistant coating film having more excellent corrosion resistance and heat resistance by including the following step [3 ].

[3] And (3) heating the heat-resistant coating film obtained in the step [2 ].

< Process [1] >

The method for applying the present composition to a substrate is not particularly limited, and conventionally known methods can be used without limitation, and conventional airless spraying, air spraying, brush coating, roll coating, and the like are preferred. The spray coating is preferable in that it is excellent in workability, productivity, and the like, can easily coat a large-area substrate, and can further exhibit the effects of the present invention.

In the case where the present composition is a two-component type composition containing a curing accelerator, it is preferable to mix the main component and the curing accelerator-containing component immediately before coating and perform spraying or the like.

The conditions for the spray coating may be appropriately adjusted depending on the thickness of the heat-resistant coating film to be formed, and for example, in the case of airless spraying, the coating conditions may be set to 1-time (air) pressure: about 0.4-0.8 MPa, 2 times (coating) pressure: about 10-26 MPa, spray gun moving speed: about 50-120 cm/sec.

In this case, the viscosity of the present composition to be used can be adjusted by a diluent, and is preferably about 1.8 to 2.5 pas at 23 ℃ as measured by a B-type viscometer ("TVB-10M", manufactured by Toyobo industries, Ltd.). The diluent is preferably an organic solvent capable of dissolving or dispersing the components in the present composition, and examples thereof include aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as mineral spirits and cyclohexane, and alcohol solvents such as n-butanol and isopropanol. The number of the diluent used may be 1 or 2 or more.

When the composition is applied to piping of a plant, it can be applied to piping of a relatively high temperature without stopping the operation of the plant, but in this case, the coating material to be spray-coated is cured before a uniform and smooth coating film is formed on the surface of the substrate, and is easily applied in the form of dust. In order to suppress such a situation, a high boiling point solvent can be used as the diluent.

When the present composition is applied to a substrate, it is preferable to perform, as necessary, a treatment (for example, a sand blast treatment (ISO 8501-1 Sa21/2), a treatment for removing oil and dust by degreasing) on the surface of the substrate in order to remove rust, grease, moisture, dust, salt, and the like on the substrate and to improve the adhesion between the obtained heat-resistant coating film and the substrate. In addition, for 1 time rust prevention, a primer or the like may be applied to the base material.

As a method for forming the heat-resistant coating film having a desired film thickness, a coating film having a desired film thickness may be formed by 1-time coating, or a coating film having a desired film thickness may be formed by 2 or more times of coating (2 or more times of coating). In view of the control of the film thickness and the residual solvent in the coating film, it is preferable to form a coating film having a desired film thickness by coating 2 or more times.

Here, the 2-time coating (2-time coating) refers to a method in which the steps [1] and [2], and if necessary the step [3] are performed on the obtained coating film after the steps [1] and [2], and if necessary the step [3] are performed, and the 3-time or more coating refers to a method in which a series of steps are further repeated.

When the coating film is formed by 2 or more times of coating, for example, the color tone of the coating material and the color tone of the coating film to be coated at the first time are preferably different from those of the coating material and the color tone of the coating film to be coated subsequently. This is a measure for easily judging the forgetfulness of coating, the insufficient film thickness, and the like in the coating operation. In addition, finish coating may be performed in order to process the color tone of the final outer surface to a predetermined color tone.

< Process [2] >

The composition can be dried and cured at normal temperature, and thus, even if dried and cured at normal temperature, a heat-resistant coating film excellent in heat resistance and corrosion resistance can be obtained. If necessary, the drying may be carried out 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, the substrate, the coating place, and the like. The drying temperature is preferably 5 ℃ or higher, more preferably 10 ℃ or higher, preferably 40 ℃ or lower, and more preferably 30 ℃ 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.

< Process [3] >

By performing the step [3], a heat-resistant coating film having further physical and chemical resistance can be formed. That is, a heat-resistant coating film having a higher coating film hardness and more excellent corrosion resistance can be formed.

The heating conditions in the step [3] are not particularly limited, but the heating temperature is preferably 150 to 250 ℃ and the heating time is preferably 10 minutes or more, more preferably 30 minutes or more, preferably 3 hours or less, more preferably 1 hour or less.

Examples

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

Examples 1 to 9 and comparative examples 1 to 2

The main agent component was prepared by adding the raw materials described in the main agent column of table 1 to a vessel in the amounts (parts by mass) described in table 1, and uniformly dispersing them by stirring with a high-speed disperser.

The details of each component shown in table 1 are shown in table 2. In addition, the solid content (% by mass) of each component in table 2 is a manufacturer catalog value.

[ Table 1]

[ Table 2]

< evaluation of adhesion >

100 parts by mass of the prepared main component and 1.5 parts by mass of KP-390 as a curing accelerator were mixed to obtain a coating composition, and the obtained coating composition was coated on a SS400 sandblasted (corresponding to ISO 8501-1 Sa21/2) steel plate using a film coater having a clearance of 700. mu.m, so that the dry film thickness became 250. mu.m.

The coating composition applied to the steel plate was dried at 23 ℃ for 7 days to prepare a test piece (substrate with a coating film). In order to eliminate the influence of the portion not coated with the coating composition, the test piece was subjected to neutral salt water spray test (35 ℃) for 3 weeks, then washed with water, and then subjected to checkerboard tape peeling test (5mm × 5mm, 9 squares) in an environment of 23 ℃ and 55% humidity after drying for 1 day, using a test piece in which the back surface and the edge portion of the test piece were coated with an epoxy-based anticorrosive coating, in accordance with JIS Z2371.

The checkerboard tape peel test was specifically performed as follows.

On the coating film of the test piece after drying, 4 vertical by 4 horizontal cuts reaching the depth of the steel plate were made using a cutter guide to produce a 9-grid checkerboard. Wherein the interval of the cutting marks is 5 mm. Subsequently, CELLOTAPE (registered trademark) was strongly pressure-bonded to the checkered portions of the coating film, and one end of the CELLOTAPE was continuously peeled off at an angle of 90 ° to the surface of the coating film. Then, a residual area ratio (%) of the area of the coating film remaining on the steel sheet to the area of the 9 cells was calculated, and the adhesion was evaluated using the value of the residual area ratio (%).

When the residual area ratio (%) is less than 50%, the case was regarded as poor (x), and when the residual area ratio (%) is 50% or more, the case was regarded as good adhesion (o).

< evaluation of Corrosion resistance >

Test pieces were prepared as in the following (1) to (3), and the salt spray test of the following (4) was performed using each test piece to evaluate.

(1) Unheated test piece

100 parts by mass of the prepared main component and 1.5 parts by mass of KP-390 as a curing accelerator were mixed to obtain a coating composition, and the obtained coating composition was adjusted with xylene so that the viscosity at 23 ℃ measured with the type B viscometer became 2 pas.

The coating composition having the adjusted viscosity was applied to an SS400 sandblasted (corresponding to ISO 8501-1 Sa21/2) steel plate with a film coater having a clearance of 700 μm so that the dry film thickness became 250 μm.

Thereafter, the coating composition coated on the steel plate was dried at 23 ℃ for 7 days to prepare an unheated test piece (substrate with a coating film).

(2) Thermal cycle test piece (300 ℃ heating and quenching)

The test piece obtained in the same manner as in the above (1) test piece without heating was put into an electric oven, heated at 300 ℃ for 1.5 hours, taken out of the oven, and immediately immersed in ice water for 10 seconds to be quenched. Thereafter, the test piece was taken out from the ice water and left at room temperature for 30 minutes. The heating and quenching were performed for 3 cycles as 1 cycle, thereby producing a thermal cycle test piece.

(3) Heat resistance test piece (550 ℃ C. heating)

The test piece obtained in the same manner as in the non-heating test (1) was put into a muffle furnace, heated at 550 ℃ for 4 hours, and then left to cool, thereby producing a heat-resistant test piece.

(4) Salt spray test

In order to eliminate the influence of the portion not coated with the coating composition, the test piece was subjected to a neutral salt water spray test (35 ℃) for 3 weeks using a test piece in which the back surface and the edge portion of the test piece were coated with an epoxy-based anticorrosive coating, and the creep width of the evaluation target portion (the length between the portion farthest from the drawn line portion and the drawn line portion in the portion where the coating film and the steel sheet were peeled off) was measured according to the following evaluation criteria (35 ℃). The "evaluation target portion" referred to herein means a portion removed from the edge of the test piece in a range of 1cm in consideration of the influence of the epoxy-based anticorrosive paint.

Evaluation criteria

Very good: the creep amplitude of the evaluation object part is less than 5 mm;

o: the creep width of the evaluation target part is more than 5mm and less than 10 mm;

and (delta): the creep width of the evaluation target part is more than 10mm and less than 20 mm;

x: the creep width of the evaluation target portion is 20mm or more.

[ Table 3]

Claims

1. A heat resistant coating composition characterized by:

comprising a siloxane-based binder (A), an aluminum powder (B) and a rust preventive pigment (C) containing a magnesium phosphate-based compound.

2. The heat resistant coating composition of claim 1, wherein:

the rust preventive pigment (C) further contains a zinc phosphate compound.

3. A heat-resistant coating composition according to claim 1 or 2, characterized in that:

further comprises a curing accelerator (D).

4. A heat-resistant coating composition according to any one of claims 1 to 3, characterized in that:

the pigment volume concentration is 25-55%.

5. A heat-resistant coating film characterized by:

a heat-resistant coating composition according to any one of claims 1 to 4.

6. A substrate with a heat-resistant coating film attached thereto, characterized in that:

comprising a substrate and the heat-resistant coating film according to claim 5.

7. A method for producing a substrate with a heat-resistant coating film, comprising:

comprising the following steps [1] and [2 ]:

[1] coating a substrate with the heat-resistant coating composition according to any one of claims 1 to 4; and