JP7203569B2 - Antirust paint composition and its use - Google Patents

Description

TECHNICAL FIELD The present invention relates to an anticorrosive paint composition used in steel material working processes and the like, and uses thereof. More specifically, a rust-preventive coating composition capable of forming a rust-preventive coating film having excellent corrosion resistance and weldability, and a substrate with a rust-preventive coating film formed using this rust-preventive coating composition, etc. Regarding.

BACKGROUND ART Conventionally, antirust paints have been applied to substrate surfaces for the purpose of preventing rust formation during the construction of large steel structures such as ships, offshore structures, plants, bridges, and land tanks. Known antirust paints include organic antirust paints such as wash primers, non-zinc epoxy primers and epoxy zinc-rich primers, and inorganic zinc antirust paints containing siloxane-based binders and zinc dust. Among these antirust paints, inorganic zinc antirust paints with excellent weldability are most widely used.

In recent years, welding has become more automated and faster, and with the improvement of welding speed, conventional inorganic zinc rust preventive paints have increased the occurrence of welding defects such as pits and blowholes. is becoming a barrier. For this reason, there is a demand for an inorganic zinc antirust paint with further improved weldability.

In addition, structures exposed to the outdoor environment are required to have high outdoor exposure resistance, and structures built in coastal areas such as ships and offshore structures are required to have high corrosion resistance against seawater. , there is a demand for improved salt spray resistance.

Patent Document 1 discloses a coating composition containing a binder resin, Zn-based metal powder, and condensed aluminum phosphate containing Mg. It is described that a coating film exhibiting good corrosion resistance can be formed.

Patent Document 2 discloses a coated steel sheet having a coating containing a binder resin, zinc-based metal powder, and condensed aluminum phosphate containing Mg on at least one side of the steel sheet. It is described that it has excellent long-term corrosion resistance, is environmentally friendly, and is inexpensive.

Patent Document 3 discloses an antirust coating composition containing at least one of silicon-based inorganic compound, zinc powder, phosphate-based pigment and feldspar, and this coating composition is generated during welding. It is described that the occurrence of welding defects such as pits and blowholes can be greatly reduced and the welding speed can be improved.

Patent Document 4 discloses a rust-preventive paint composition comprising a silicon-based inorganic compound as a binder and zinc dust and a cyclic aluminum metaphosphate free of water of crystallization as rust-preventive pigments. It is stated that the composition can form a coating film with excellent rust prevention properties that does not cause white rust or welding defects due to zinc vapor even in the process of working steel materials under high heat. It is

JP 2017-122186 A JP 2017-121778 A JP-A-6-200188 JP-A-11-116856

However, coating films and coated steel sheets formed from the coating compositions disclosed in the above patent documents require further improvement in weldability, or have insufficient outdoor exposure resistance or salt spray resistance.

The present invention aims to solve the above-mentioned problems, and provides a rust-preventive coating composition capable of forming a rust-preventive coating film with high corrosion resistance, particularly salt spray resistance, outdoor exposure resistance, and weldability, and its use.

The present inventors have made intensive studies to solve the above problems, and as a result, have found that the above problems can be solved by using a rust preventive coating composition having a specific composition, and have completed the present invention.
A configuration example of the present invention is as follows.

<1> Containing an alkylsilicate condensate (A), zinc powder (B), and aluminum phosphate (C),
A rust-preventive paint composition in which the mass ratio ((B)/(C)) of zinc dust (B) and aluminum phosphate (C) is 5.0 to 11.0,
An antirust paint composition, wherein the content of the zinc dust (B) in the non-volatile matter contained in the composition is 50 to 70% by mass.
<2> The antirust coating composition according to <1>, wherein the aluminum phosphate (C) is aluminum dihydrogen tripolyphosphate.
<3> The antirust coating composition according to <1> or <2>, wherein the PVC (pigment volume concentration) of the antirust coating composition is 60 to 70%.
<4> An antirust coating film formed from the antirust coating composition according to any one of <1> to <3>.
<5> A primary anticorrosive coating film comprising the anticorrosive coating film according to <4> and having an average dry film thickness of 10 μm or less.
<6> A substrate with an anticorrosive coating film comprising the anticorrosive coating film according to <4> or the primary anticorrosive coating film according to <5> and a substrate.
<7> A method for producing a substrate with an antirust coating, comprising the following steps [1] and [2].
[1] A step of applying the antirust paint composition according to any one of <1> to <3> to a substrate [2] Drying the antirust paint composition applied to the substrate, The process of forming a coating film on the material

The antirust coating composition of the present invention can form an antirust coating film having high anticorrosion properties, particularly high resistance to salt spray and outdoor exposure, and high weldability.

FIG. 1 is a diagram showing an outline of a welding test.

The antirust coating composition (hereinafter also referred to as "the present composition"), the antirust coating film, the substrate with the antirust coating film, and the method for producing the same of the present invention will be described in detail below, including preferred embodiments. do.
≪Antirust paint composition≫
The composition contains an alkylsilicate condensate (A), zinc dust (B), and aluminum phosphate (C), and the mass ratio of the zinc dust (B) to the aluminum phosphate (C) is ((B)/(C)) is from 5.0 to 11.0, and the content of zinc dust (B) in the non-volatile matter contained in the composition is from 50 to 70% by mass.

The present composition comprises the components (A) to (C), the mass ratio of the component (B) and the component (C) is within a specific range, and the content ratio of the component (B) is a specific Since it is in the range, it is possible to form a rust-preventive coating film with high salt spray resistance and high weldability.

If desired, the present composition may contain a conductive pigment, an extender pigment, a coloring pigment, the zinc dust (B), the aluminum phosphate (C), and an anticorrosive pigment, excluding the conductive pigment, within a range that does not impair the effects of the present invention. Pigments; binders other than the condensate (A) of alkyl silicate; other pigments; additives, organic solvents, and the like.

The present composition is usually a two-component composition comprising a base component containing an alkylsilicate condensate (A) and a paste component containing zinc powder (B) and aluminum phosphate (C). . Moreover, if necessary, the present composition may be a multicomponent composition consisting of three or more components. These main ingredient component and paste component are usually stored, stored, transported, etc. in separate containers, and mixed just before use.
<Condensate of Alkyl Silicate (A)>
The condensate (A) of alkylsilicate preferably has a weight average molecular weight (Mw) of 1,500 to 8,000, more preferably 1,500 to 7,000. Mw is a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method, and the details are as described in Examples.

When the Mw is in the above range, the paint can be cured at normal temperature, for example, 5 to 35 ° C. in a short time when dried, and the corrosion resistance of the coating film and the adhesion strength to the substrate are improved, and welding The effect of suppressing the occurrence of blowholes (inner bubbles) at time increases. On the other hand, if Mw is less than the above lower limit, the curing reaction of the alkylsilicate condensate (A) is slow, and when curing in a short time is required, the coating film is dried at a high temperature, for example, by heating at 200 to 400 ° C. Hardening is required. When Mw exceeds the above upper limit, the pot life tends to be shortened.

Examples of alkyl silicates used in the alkyl silicate condensate (A) include tetramethyl orthosilicate, tetraethyl orthosilicate, tetra-n-propyl orthosilicate, tetra-i-propyl orthosilicate, and tetra-n-butyl orthosilicate. , tetra-sec-butyl orthosilicate, methyl polysilicate, ethyl polysilicate, and the like.

The alkylsilicate condensate (A) can be produced by a conventionally known method. For example, an alkylsilicate condensate (A) can be produced by adding hydrochloric acid or the like to a mixed solution of an alkylsilicate and an organic solvent and stirring the mixture to produce a partially hydrolyzed condensate.

Such alkylsilicate condensates (A) may be used singly or in combination of two or more.
The content of the alkylsilicate condensate (A) is usually 10 to 30% by mass, preferably 15 to 25% by mass, more preferably 16 to 23% by mass, based on 100% by mass of the nonvolatile content of the present composition. %. When the content of the alkylsilicate condensate (A) is within the above range, a continuous and homogeneous coating film can be obtained, and as a result, rusting of steel materials can be more effectively prevented.
The non-volatile matter means the heating residue of the present composition under the following conditions. The heating residue of the coating composition can be measured according to JIS K 5601 1-2 (heating temperature: 125° C., heating time: 60 minutes).

<Zinc dust (B)>
The zinc dust (B) is not particularly limited as long as it is metallic zinc powder or zinc-based alloy powder. For example, an alloy of zinc and at least one selected from aluminum, magnesium and tin and preferably zinc-aluminum alloys and zinc-tin alloys. Moreover, the shape of such zinc dust (B) is not particularly limited, and may be, for example, scale-like or spherical. Such zinc powder (B) may be used singly or in combination of two or more.

In the present composition, the mass ratio ((B)/(C)) between the zinc dust (B) and the aluminum phosphate (C) described later is 5.0 to 11.0, preferably 5.0. ~10.0, more preferably 5.0 to 9.0, particularly preferably 5.0 to 8.0. When the mass ratio ((B)/(C)) is within the above range, the coating film formed from the present composition has good corrosion resistance, especially salt water resistance, outdoor exposure resistance, and weldability. When the mass ratio ((B)/(C)) exceeds the upper limit of the above range, the amount of aluminum phosphate is relatively decreased, and weldability tends to deteriorate. On the other hand, when the mass ratio ((B)/(C)) is below the lower limit of the above range, the amount of aluminum phosphate is relatively increased, and although weldability is improved, outdoor exposure resistance tends to be deteriorated. be. This is probably because aluminum phosphate, which is present in a large amount, inhibits the sacrificial anticorrosion action of zinc.

The content of zinc dust (B) in the nonvolatile matter contained in the present composition is 50 to 70% by mass, preferably 50 to 65% by mass. When the content of zinc dust (B) is within the above range, the corrosion resistance of the coating film formed from the present composition, particularly salt water resistance, outdoor exposure resistance, and weldability are well balanced. If the content of zinc dust (B) exceeds the upper limit of the above range, the amount of zinc fume generated during welding increases, which may adversely affect the health of welders and tends to deteriorate weldability. It is in. On the other hand, when the content of zinc dust (B) is below the lower limit of the above range, various anticorrosion properties tend to deteriorate due to the small amount of zinc dust.

In the present composition, as the zinc dust (B), it is preferable to adopt an embodiment in which scale-like zinc dust and spherical zinc dust are used in combination, or an embodiment in which only spherical zinc dust is contained. When only spherical zinc dust is contained, since spherical zinc dust is less expensive than flake zinc dust, it is economically superior and can form a coating film having necessary and sufficient anti-corrosion properties. On the other hand, since flake zinc has a large specific surface area, contact between zinc particles in the antirust coating film tends to be dense. Therefore, even if the content of zinc dust (B) in the anticorrosive coating film to be formed is relatively small, the composition containing flaky zinc dust is a coating film with excellent anticorrosion properties after long-term exposure. can be formed.

In addition, when the antirust coating film formed from the present composition is heated at a high temperature of 800 ° C. or higher during welding, etc., the scale-like zinc dust is easily oxidized due to its large specific surface area, and the corrosion resistance after heating may decrease. On the other hand, when flake zinc dust and spherical zinc dust are used in combination, metallic zinc tends to remain inside the spherical zinc dust even when the antirust coating film is heated at the above-mentioned high temperature. tend to be maintained.

In addition, the scale-like zinc dust has a metallic luster color, and when forming a coating film, the main surface of the zinc dust particles tends to be oriented parallel to the surface of the coating film, so other coloring pigments were introduced. Even in such a case, the hue tends to be tinged with a metallic luster color. Therefore, when using scale-like zinc powder, there are sometimes restrictions on hue design. On the other hand, by using both flaky zinc dust and spherical zinc dust, the content of flaky zinc dust can be relatively reduced, so that this tendency is alleviated, and the hue can be freely designed.

Commercially available zinc dust (B) includes, for example, flake-like metallic zinc dust STANDART Zinc flake GTT, STANDART Zinc flake G, STANDART Zinc flake AT (manufactured by ECKART GmbH), and flake-like zinc alloy powder. STAPA 4ZNAL7 (alloy of zinc and aluminum; manufactured by ECKART GmbH), STAPA 4 ZNSN30 (alloy of zinc and tin; manufactured by ECKART GmbH), spherical zinc powder F-2000 (manufactured by Honjo Chemical Co., Ltd.). .

<Aluminum phosphate (C)>
By containing aluminum phosphate (C), the present composition exhibits corrosion resistance such as excellent salt spray resistance and outdoor exposure resistance, and also exhibits excellent weldability.

The aluminum phosphate (C) has generally been used as a rust-preventive pigment, and by using it in a specific proportion with respect to zinc dust, the effect of significantly improving the corrosion resistance and weldability can be obtained. is a novel finding that has not been known until now and cannot be predicted even by those skilled in the art. Although the mechanism of action that produces the above effect is not clear, the anticorrosion property can be improved by adjusting the mass ratio of zinc dust (B) and aluminum phosphate (C) to a specific range. is controlled and contributes to the development of long-term corrosion resistance. With regard to weldability, when arc welding a steel material coated with a coating film formed from this composition, P and Al ions constituting aluminum phosphate (C) are presumed to contribute to the stabilization of the arc.

Examples of aluminum phosphate (C) include trialuminum phosphate, aluminum dihydrogen orthophosphate, aluminum pyrophosphate, aluminum dihydrogen tripolyphosphate, aluminum metaphosphate, and aluminum phosphite. From the viewpoint of imparting corrosion resistance and weldability, condensed aluminum phosphate represented by aluminum dihydrogen tripolyphosphate is preferable. Commercially available products of aluminum phosphate (C) include, for example, aluminum dihydrogen tripolyphosphate such as K-WHITE#84 and K-WHITE#105 (manufactured by Tayca Corporation).
The mass ratio ((B)/(C)) of zinc dust (B) and aluminum phosphate (C) in the present composition is as described above.

<Other ingredients>
Other components of the present composition include a binder other than the alkylsilicate condensate (A), a conductive pigment, an extender pigment, a coloring pigment, an antirust pigment, other pigments, an anti-settling agent, a desiccant, and fluidity. Additives such as modifiers, antifoaming agents, dispersants, anti-color separation agents, anti-skinning agents, plasticizers, UV absorbers, organic solvents, etc. You may
These may be used individually by 1 type, and may use 2 or more types together.

<Binder other than the alkylsilicate (A)>
The present composition may contain, for example, a polyvinyl butyral resin or the like as a binder other than the condensate (A) of alkylsilicate. Examples of commercial products of the polyvinyl butyral resin include S-LEC B BM-2 (manufactured by Sekisui Chemical Co., Ltd.).
A binder other than the alkylsilicate condensate (A) is preferably contained in the main component when the present composition is a two-component composition.

<Conductive pigment>
The present composition preferably contains a conductive pigment from the viewpoint of improving the anti-corrosion properties of the anti-rust coating film to be formed. In particular, when only spherical zinc dust is contained as the zinc dust (B), it is preferable to use the above together from the viewpoint of enhancing the sacrificial anti-corrosion effect of the anti-corrosion coating film.

Specifically, in order for the antirust coating film made of the present composition to exhibit excellent anticorrosion properties, electrons generated when the zinc dust (B) is ionized must be efficiently transferred to a substrate such as steel. supply is important. Normally, the contact between the zinc dust particles (B) in the rust-preventive coating film makes it possible to obtain an energizing effect. be. On the other hand, the antirust coating film containing only spherical zinc dust as the zinc dust (B) further contains a conductive pigment, so that the conductive pigment plays a role of connecting the zinc dust, and effective sacrificial corrosion prevention. effect can be obtained, and good anti-corrosion properties can be exhibited.

Examples of the conductive pigment include zinc powder (B) and metal powders other than molybdenum, which will be described later, zinc oxide, carbon powder, and the like. Among these, zinc oxide is preferable because it is inexpensive and has high conductivity.

Examples of commercially available zinc oxide include Type 1 zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.) and Type 3 zinc oxide (manufactured by Hakusui Tech Co., Ltd.).
Examples of the metal powder include Fe--Si powder, Fe--Mn powder, Fe--Cr powder, magnetic iron powder, and iron phosphide. Examples of commercially available metal powders include ferrosilicon (manufactured by Kinseimatec Co., Ltd.), ferromanganese (manufactured by Kinseimatec Co., Ltd.), ferrochromium (manufactured by Kinseimatec Co., Ltd.), and Ferrophos 2132 (manufactured by Occidental Chemical Corporation). made) and the like.

Carbon black etc. are mentioned as said carbon powder. Examples of commercial products of the carbon powder include Mitsubishi Carbon Black MA-100 (manufactured by Mitsubishi Chemical Corporation).

The conductive pigments may be used singly or in combination of two or more.
When the conductive pigment is used, the content of the conductive pigment is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the zinc powder (B). When the content of the conductive pigment is within the above range, it is preferable from the viewpoint of enhancing the sacrificial anti-corrosion effect of the coating film and improving the anti-corrosion property.

Moreover, the content of the conductive pigment is preferably more than 0% by mass and 10% by mass or less, more preferably 5% by mass or less, relative to 100% by mass of the non-volatile matter of the present composition. When the content of the conductive pigment is within the above range, it is preferable in that the content of the zinc dust (B) can be kept low while the anticorrosion property can be maintained.

<Extender pigment>
The extender pigment is not particularly limited as long as it is an inorganic pigment used in general paints, but is preferably a heat-resistant inorganic pigment, such as potassium feldspar, soda feldspar, kaolin, mica, silica, and talc. , barium sulfate, aluminum oxide, zirconium silicate, wollastonite, diatomaceous earth, and the like. Also, inorganic pigments such as calcium fluoride, calcium carbonate, magnesium carbonate, and strontium carbonate that generate thermal decomposition gas may be used. Potassium feldspar and mica are preferable as such extender pigments.

Commercially available products of the extender pigment include, for example, potassium feldspar UNISPAR PG-K10 (manufactured by Sibelco Malaysia Sdn. Bhd), mica powder 100 mesh (manufactured by Fukuoka Talc Kogyosho Co., Ltd.), kaolin ASP-200 (BASF Japan Co., Ltd.), zirconium silicate A-PAX45M (manufactured by Kinseimatec Co., Ltd.), FC-1 talc (manufactured by Fukuoka Talc Kogyo Co., Ltd.), silica QZ-SW (manufactured by Goto Mining Co., Ltd.), sedimentation and diatomaceous barium sulfate 100 (manufactured by Sakai Chemical Co., Ltd.), Radiolite (Showa Chemical Industry Co., Ltd.), and the like.

The pyrolysis gas generating inorganic pigment generates gases such as CO ₂ and F ₂ by thermal decomposition, eg, thermal decomposition at 500 to 1500°C. When welding a steel material coated with a paint film containing such a pigment, in the molten pool during welding, the alkylsilicate condensate (A) and the composition other than the condensate (A) described later It has the effect of removing bubbles generated by the derived gas from the molten pool together with the gas derived from the inorganic pigment. Examples of commercially available pigments include fluorite 400 mesh (manufactured by Kinseimatec Co., Ltd.), NS#400 (manufactured by Nitto Funka Kogyo Co., Ltd.), magnesium carbonate (manufactured by Tomita Pharmaceutical Co., Ltd.), and strontium carbonate. A (manufactured by Honjo Chemical Co., Ltd.).

The said extender may be used individually by 1 type, and may use 2 or more types together.
When using such an inorganic pigment that generates thermal decomposition gas, the content thereof is preferably 0.1 to 8% by mass, more preferably 0.2 to 8% by mass, based on 100% by mass of the nonvolatile matter of the composition. 4% by mass.
When an extender pigment other than an inorganic pigment that generates thermal decomposition gas is used, the content thereof is preferably 0.1 to 25% by mass with respect to 100% by mass of the non-volatile matter of the present composition.

<Coloring pigment>
The color pigments include inorganic color pigments and organic color pigments. The inorganic coloring pigment is not particularly limited as long as it is an inorganic coloring pigment other than the conductive pigment, and examples thereof include titanium oxide, red iron oxide, and a composite oxide of copper, chromium, and manganese. Examples of organic coloring pigments include organic coloring pigments such as phthalocyanine green and phthalocyanine blue. Examples of commercially available organic color pigments include TITONE R-5N (manufactured by Sakai Chemical Industry Co., Ltd.), Bengara No. 404 (manufactured by Morishita Bengara Kogyo Co., Ltd.), Dipyroxide Black #9510 (manufactured by Dainichiseika Kogyo Co., Ltd.), Heliogen Green L8690 (manufactured by BASF Japan Co., Ltd.), and FASTOGEN Blue 5485 (manufactured by DIC Corporation). made) and the like.

The said coloring pigment may be used individually by 1 type, and may use 2 or more types together.
When inorganic color pigments are used, the content thereof is preferably 0.1 to 25% by mass with respect to 100% by mass of nonvolatile matter in the present composition.
When an organic color pigment is used, the content thereof is preferably 0.15 to 2.0% by mass with respect to 100% by mass of non-volatile matter in the present composition.

<Antirust pigment>
The rust-preventive pigment is a rust-preventive pigment other than the zinc dust (B), aluminum phosphate (C), and conductive pigment, and is used for the purpose of further improving the corrosion resistance of the coating film. Examples of the antirust pigment include zinc phosphate compounds, calcium phosphate compounds, magnesium phosphate compounds, zinc phosphite compounds, calcium phosphite compounds, strontium phosphite compounds, zinc cyanamide compounds, boron acid salt compounds, zinc chloride, zinc sulfide, zinc sulfate, nitro compounds and the like.

Examples of commercially available antirust pigments include LF Bosei CP-Z (manufactured by Kikuchi Color Co., Ltd.), which is a calcium zinc phosphate compound, and PROTEX YM-70 (Taihei Kagaku Co., Ltd.), which is a zinc phosphite (calcium) compound. Sangyo Co., Ltd.), Protex YM-92NS, a zinc phosphite (strontium) compound (manufactured by Taihei Kagaku Sangyo Co., Ltd.), LF Bosei ZK-32, a zinc cyanamide compound (manufactured by Kikuchi Color Co., Ltd.) ), zinc sulfide Sachtorich HD (manufactured by Sachleben Chemie GmbH), zinc chloride (manufactured by Nagai Pharmaceutical Co., Ltd.), and the like.

The rust preventive pigments may be used singly or in combination of two or more.
When a rust preventive pigment is used, its content is preferably 0.1 to 25% by mass with respect to 100% by mass of non-volatile matter in the present composition.

<Other pigments>
The present composition may contain pigments other than the zinc dust (B), aluminum phosphate (C), conductive pigments, extender pigments, coloring pigments and antirust pigments. Such pigments include alkali glass powder, molybdenum and molybdenum compounds, and the like.
Alkali glass powder, molybdenum and molybdenum compounds are exemplified in WO2014/014063 and the like.

<Additive>
The composition may contain additives such as anti-settling agents, desiccants, fluidity modifiers, anti-foaming agents, dispersants, anti-color separation agents, anti-skinning agents, plasticizers and UV absorbers. good.
Examples of the anti-settling agent include organic bentonite-based, polyethylene oxide-based, fumed silica-based, and amide-based anti-settling agents. Commercially available anti-settling agents include, for example, TIXOGEL MPZ (manufactured by BYK Additives GmbH), Disparlon 4200-20 (manufactured by Kusumoto Kasei Co., Ltd.), Disparlon A630-20X (manufactured by Kusumoto Kasei Co., Ltd.), AEROSIL 200 (manufactured by Kusumoto Kasei Co., Ltd.). manufactured by Nippon Aerosil Co., Ltd.).

When the present composition contains an anti-settling agent, its content is usually 0.5 to 5.0% per 100% by mass of the nonvolatile matter of the paste component when the present composition is a two-component composition. 0 mass %, preferably 0.5 to 3.0 mass %. When the content of the anti-settling agent is within the above range, the pigment is less likely to precipitate, which is preferable in terms of workability when mixing the paste component and the main component.

<Organic solvent>
This composition contains an organic solvent because it improves the dispersibility of zinc dust (B), has good compatibility with steel materials in the coating process, and provides a coating film with excellent adhesion to steel materials. preferably.

Examples of the organic solvent include alcohol solvents, ester solvents, ketone solvents, aromatic solvents, glycol solvents, and other organic solvents commonly used in the field of coatings.

Examples of the alcohol solvent include methanol, ethanol, propanol, and butanol. Examples of the ester solvent include ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and the like. Examples of the ketone-based solvent include methyl isobutyl ketone and cyclohexanone. Examples of the aromatic solvent include benzene, xylene, and toluene. Examples of the glycol-based solvent include propylene glycol monomethyl ether.

When the present composition contains an organic solvent, the content is usually 25-50% by mass, preferably 35-45% by mass, more preferably 38-42% by mass. The coating composition of the present invention is preferably such an organic solvent-based composition.

In addition, when forming a primary antirust coating film with an average dry film thickness of 10 μm or less, this composition is measured using an Iwata viscosity cup (model: NK-2, manufactured by Anest Iwata Co., Ltd.) at a temperature of 23 ° C. The resulting viscosity is preferably 9 to 13 seconds, more preferably 9 to 11 seconds. In order to adjust the viscosity of the present composition within the above range, the present composition may contain the aforementioned organic solvent as appropriate.

<Pigment Volume Concentration (PVC)>
The composition preferably has a pigment volume concentration (PVC) of 60-70%, more preferably 61-68%, even more preferably 62-67%. In the present invention, the pigment volume concentration (PVC) means the pigment component in the nonvolatile matter of the present composition, and the solid in the additive that is insoluble in an organic solvent obtained by mixing ethanol and toluene at a ratio of 1:1 at 23 ° C. "Particles" refers to the concentration expressed as a percentage of the non-volatile content of the present composition (based on volume). Pigment volume concentration (PVC) is calculated by the following formula

Examples of the "pigment component" include zinc dust (B), aluminum phosphate (C), conductive pigments, extender pigments, coloring pigments, antirust pigments and other pigments. Examples of "additives" include anti-settling agents, desiccants, fluidity modifiers, anti-foaming agents, dispersants, anti-color separation agents, anti-skinning agents, plasticizers, and UV absorbers.

In calculating PVC, the volume of each component is calculated from the mass and density of each component. The volume of the alkylsilicate condensate (A) is calculated from the mass of the alkylsilicate condensate (A) in terms of SiO ₂ and its density.

The total volume of nonvolatile matter in the present composition can be calculated from the mass and true density of the solid content of the present composition. The mass and true density of the solid content of the present composition may be measured values or, as described above, values calculated in advance from the raw materials used.

The sum of the total volume of the pigment component and the total volume of the solid particles in the additive can be calculated from the mass and true density of the solid particles in the pigment and additive used. The mass and true density of the solid particles in the pigment and additive may be measured values or values calculated from raw materials used. For example, the sum of the total volume of the pigment components and the total volume of the solid particles in the additive can be obtained by using an organic solvent obtained by mixing the ethanol and toluene at a ratio of 1:1 from the non-volatile content of the composition. It can be calculated by separating the solid particles and other components in the pigment and additive and measuring the mass and true density of the separated pigment and solid particles.

By adjusting the PVC of the present composition to the above range, the pigments in the coating film can be made dense, making it possible to easily form a primary antirust coating film with an average dry film thickness of 10 μm or less. . On the other hand, when the PVC of the present composition exceeds the upper limit of the above range, the ratio of the alkylsilicate condensate (A) and the binder other than the condensate (A) in the coating film to be formed becomes low, and the pigment It becomes difficult to form a primary antirust coating film having an average dry film thickness of 10 µm or less because voids are likely to form between them. In addition, when the PVC of the present composition is below the lower limit of the above range, the ratio of the condensate (A) and the binder other than the condensate (A) in the coating film formed increases, and zinc dust ( B) Since it becomes difficult to obtain an electric current effect between them, the corrosion resistance of the coating film may be lowered. In addition, since the organic content derived from the condensate (A) in the coating film increases, the weldability may deteriorate.
The present composition can also obtain the following benefits (1) to (3) by adjusting the PVC within the above range.

(1) The primary antirust coating can reduce the amount of paint used per coated area, and the amount of VOC generated per coated area is usually 40 g/m ² or less, so the environmental load tends to be reduced. In addition, since the content of zinc dust (B) per coating area is usually 30 g/m ² or less, it is also excellent from the viewpoint of resource conservation. (2) Even if the primary anticorrosion coating film has an average dry film thickness of 10 μm or less, the coating film has excellent anticorrosion properties after long-term exposure. (3) Since a thin primary antirust coating film can be formed, the welding speed in the steel material welding process can be increased, and productivity can be improved.

<Uses of antirust paint composition>
The antirust coating composition of the present invention is preferably a primary antirust coating composition.
In general, anticorrosive coatings applied to steel materials for large structures such as ships, offshore structures, plants, bridges, land tanks, etc., do not interfere with fusing, welding, etc. in the construction process of large structures. In addition to suppressing the rusting of the steel material during the period, excellent adhesion with the top coat applied on the antirust coating is required. Therefore, the antirust coating film formed from the present composition having excellent properties can be suitably used for the above applications.

<Antirust coating and substrate with antirust coating>
The rust-preventive coating film of the present invention (hereinafter also referred to as "the present rust-preventive coating film") is formed from the above-described rust-preventive coating composition, and the substrate with the rust-preventive coating film of the present invention is made of steel or the like. It has a substrate and an antirust coating film formed on the surface of the substrate and made of the antirust coating composition described above.

Examples of the material of the substrate include steel such as iron, steel, ferroalloy, carbon steel, mild steel, and alloy steel. In addition, it is preferable that the base material is blasted under conditions corresponding to a degree of rust removal Sa2 1/2 or more according to ISO 8501-1, if necessary.

The average dry film thickness of the antirust coating film measured with an electromagnetic film thickness meter is usually 30 μm or less, preferably 5 to 20 μm. Further, when the rust preventive coating film is a primary rust preventive coating film, the average dry film thickness is preferably 10 μm or less, more preferably 5 to 9 μm.

In the primary antirust coating film, the content of zinc dust (B) per unit area is usually 5 to 30 g/ m ² , preferably 5 to 20 g/m ² . The content of zinc dust (B) per unit area is determined from the content of zinc dust (B) in the coating composition and the average dry film thickness obtained by measurement, per unit area in the coating film. The content of zinc dust (B) may be calculated, or it may be obtained by analyzing the content of zinc dust (B) contained in the coating film per unit area.

<Method for producing base material with antirust coating>
The present rust preventive coating film is formed from the present composition described above, and specifically, it can be produced through steps including the following steps [1] and [2].
[1] A step of applying the present antirust coating composition to a substrate [2] A step of drying the antirust coating composition applied on the substrate to form a coating film on the substrate

<Step [1]>
The method of applying the present composition onto a substrate is not particularly limited, and conventionally known methods such as air spray coating, airless spray coating, brush coating, and roller coating can be used. In general, when the present composition is applied in shipyards, ironworks and the like, line coating machines are mainly used. Coating conditions such as the line speed of the line coating machine, the coating pressure of the air spray installed inside the coating machine, airless spray, etc., and the size (caliber) of the spray tip are adjusted appropriately according to the thickness of the antirust coating film to be formed. can be changed. For example, the line coating machine may be set at a line speed of 4.5 m/min, a chip size (GRACO) of 617-929 coating, and a secondary (paint) pressure of about 3.8-8.9 MPa.

<Step [2]>
The composition can be dried and cured at room temperature, but may be dried with heat or hot air depending on the line speed of the line coating machine. In the case of heating/hot air drying, the drying temperature is usually 5 to 40° C., preferably 10 to 30° C., and the drying time is usually 3 to 15 minutes, preferably 5 to 10 minutes. By using the alkylsilicate condensate (A) having an Mw within the above range, the present composition can cure the coating film in a short period of time even at such room temperature. Therefore, the coating composition of the present invention is suitable for use in the pretreatment of steel sheets in the steel sheet processing process for ships, offshore structures, plants, bridges, land tanks and the like.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. In the following descriptions of Examples and the like, "parts" means "parts by mass" unless otherwise specified.

<Method for Preparing Alkyl Silicate Condensate (A)>
[Preparation Example 1]
41.8 parts of ethyl silicate 40 (manufactured by Colcoat Co., Ltd.), 9.5 parts of industrial ethanol, 5 parts of deionized water, and 0.1 part of 35% by mass hydrochloric acid were placed in a container and stirred at 65° C. for 5 hours. After that, 43.6 parts of isopropyl alcohol was added to prepare a solution A of an alkylsilicate condensate.

The alkylsilicate condensate solution A thus obtained was used as the main component of the present composition. Therefore, in the following description, the solution A of the condensate of alkyl silicate is also referred to as the main ingredient component A.

The weight average molecular weight (Mw) of the alkylsilicate condensate contained in the resulting alkylsilicate condensate solution A was measured by gel permeation chromatography (GPC) under the following measurement conditions. was 3,000. A small amount of the solution was weighed, diluted with tetrahydrofuran, and filtered through a membrane filter to obtain a GPC measurement sample.
・ Apparatus: "Alliance 2695" (manufactured by Waters)
・ Column: One "TSKgel Super H4000" and "TSKgel Supe
r H2000” are connected (both manufactured by Tosoh Corporation, inner diameter 6 mm × length 15 cm)
Eluent: Tetrahydrofuran 99% (Stabilized with BHT)
・Flow rate: 0.6 ml/min
・ Detector: “RI-104” (manufactured by Shodex)
・Column bath temperature: 40°C
・Standard material: polystyrene

<Method for preparing paste component>
[Preparation Example 2]
0.6 parts of TIXOGEL MPZ (manufactured by BYK Additives GmbH) as anti-settling agent and 4.3 parts of xylene, 5.9 parts of isobutyl alcohol and 4.0 parts of butyl acetate, aluminum phosphate (C ), 4.7 parts of K-WHITE #105, which is aluminum dihydrogen tripolyphosphate, and 1.6 parts of UNISPAR PG-K10 (manufactured by Sibelco Malaysia Sdn. Bhd), which is an extender pigment, are each charged in a polyethylene container and glass. Beads were added and shaken on a paint shaker for 3 hours. Next, 30.7 parts of spherical zinc powder F-2000 (manufactured by Honjo Chemical Co., Ltd.) was added as zinc powder (B), and the mixture was shaken for an additional 5 minutes to disperse the pigment component. Thereafter, the glass beads were removed using an 80-mesh screen to prepare paste component B-1.

[Preparation Examples 3 to 14]
Paste components B-2 to B-13 were prepared in the same manner as in Preparation Example 2 except that each raw material shown in Table 1 below was used in the amount shown in Table 1. Numerical values in Table 1 indicate parts by mass.

なお、表１に記載の各成分の詳細は、表２に示すとおりである。

Details of each component described in Table 1 are as shown in Table 2.

<Method for preparing antirust coating composition>
[Example 1]
The main ingredient component A and the paste component B-1 were mixed according to the amounts (numerical values) shown in Table 3 immediately before coating to prepare an antirust coating composition of Example 1. Table 3 shows the mass ratio of zinc dust (B) to aluminum phosphate (C) ((B)/(C)) and zinc dust content (% by weight) in the antirust coating composition obtained. .

[Examples 2 to 7 and Comparative Examples 1 to 6]
In the same manner as in Example 1, the main agent component and each paste component listed in Table 1 were mixed according to the amounts (numerical values) listed in Table 3 immediately before coating, and each of Examples 2 to 7 and Comparative Examples 1 to 6 was prepared. A rust coating composition was prepared. Table 3 shows the mass ratio of zinc dust (B) to aluminum phosphate (C) ((B)/(C)) and zinc dust content (% by weight) in the antirust coating composition obtained.

[Painting conditions]
Air spray coating was performed using a line coating machine (device name: conveyor coating machine for SP, manufactured by Takeuchi Kosakusho Co., Ltd.) so that the dry film thickness was about 12 μm.
(1) Corrosion resistance Each antirust paint composition was applied to the blasted surface of a sandblasted plate (JIS G3101, SS400, dimensions: 150 mm x 70 mm x 2.3 mm) under the above coating conditions. Next, according to the standard of JIS K5600-1-6, the coated composition is dried in a constant temperature room at a temperature of 23 ° C. and a relative humidity of 50% for 1 week, and each obtained anticorrosive coating film and the treated plate. A test plate was created.

According to the standard of JIS K5600-7-1, the prepared test plate was subjected to a salt spray test for 350 hours using a 5% concentration salt solution, and the ratio (%) of the rusted area to the total area of the test plate was obtained. The state of rust was evaluated.

According to the standard of JIS K5600-7-6, it was exposed to the outdoors at 0° (horizontal) for 5 months, and the ratio (%) of the rusted area to the total area of the test plate was obtained to evaluate the state of rusting.
The evaluation criteria for the salt spray test and outdoor exposure test are as follows. Based on the evaluation criteria (ASTM D610) for the state of rusting, evaluation was made on a scale of 10 according to the following criteria. Furthermore, as an anticorrosion evaluation, compositions that scored 10, 9 or 8 on the basis of the following criteria were evaluated as "good", and compositions that scored 7 or less were evaluated as "poor". Table 5 below shows the corrosion resistance evaluation results of each coating composition.
10: No rusting, or the rusted area is 0.01% or less of the total area of the test plate.
9: The rusted area is more than 0.01% and 0.03% or less of the total area of the test plate.
8: The rusted area is more than 0.03% and 0.1% or less of the total area of the test plate.
7: The rusted area is more than 0.1% and 0.3% or less of the total area of the test plate.
6: The rusted area is more than 0.3% and 1% or less of the total area of the test plate.
5: The rusted area is more than 1% and 3% or less of the total area of the test plate.
4: The rusted area exceeds 3% and is 10% or less of the total area of the test plate.
3: The rusted area exceeds 10% and is 16% or less of the total area of the test plate.
2: The rusted area exceeds 16% and is 33% or less of the total area of the test plate.
1: The rusted area exceeds 33% and is 50% or less of the total area of the test plate.
0: The rusted area is more than 50% and 100% or less of the total area of the test plate.

(2) Weldability On the blasted surfaces of two sandblasted plates (JIS G3101, SS400, lower plate dimensions: 600 mm × 100 mm × 12 mm, upper plate dimensions: 600 mm × 50 mm × 12 mm), each protective layer was applied under the above coating conditions. A rust paint composition was applied. Next, according to the standard of JIS K5600-1-6, the coated composition was dried in a constant temperature room at a temperature of 23 ° C. and a relative humidity of 50% for 1 week, and shown in FIGS. 1 (a-1), (b-1) and An upper plate 20 and a lower plate 10 having a rectangular planar shape were produced as shown in (c-1). As shown in FIGS. 1(a-2), (b-2) and (c-2), the upper plate 20 is joined to the lower plate 10 so that the upper plate 20 is perpendicular to the lower plate 10. bottom. In FIGS. 1(a-1), (b-1), (a-2) and (b-2), the densely shaded areas of the sandblasted plates (upper plate 20 and lower plate 10) indicate the painted areas. show.

Next, while maintaining a predetermined torch angle and torch shift, as shown in FIGS. The lower plate 10 was welded so that the first weld line side and the second weld line side were welded at the same time. The welding conditions at this time are shown in Table 4 below.

Weldability was then evaluated as follows.
First, the number of pits (pieces) and gas groove length (mm )It was confirmed. Furthermore, based on the welding conditions described in Table 5, a laser notch (V-shaped cut) was made on the weld line on the first weld line side, and the weld on the second weld line side was pressed along the weld line. After breaking, divide the total area of blowholes (width x length x number of blowholes) generated on the fractured surface by the evaluation area to calculate the rate of occurrence of blowholes (%), and evaluate weldability in the following three stages. evaluated. Weldability evaluation results for each coating composition are shown in Table 5 below.
◯: Blowhole occurrence rate is less than 8%.
Δ: Blowhole generation rate is 8% or more and less than 10%.
x: Blowhole generation rate is 10% or more.

10: Sandblasting plate (lower plate)
20: Sandblasting plate (upper plate)

Claims (8)

Containing an alkylsilicate condensate (A), zinc dust (B), and aluminum phosphate (C) (excluding cyclic aluminum metaphosphate having no water of crystallization) ,
A rust-preventive paint composition in which the mass ratio ((B)/(C)) of zinc dust (B) and aluminum phosphate (C) is 5.0 to 11.0,
An antirust paint composition, wherein the content of the zinc dust (B) in the non-volatile matter contained in the composition is 50 to 70% by mass. Containing an alkylsilicate condensate (A), zinc dust (B), and aluminum phosphate (C),
A rust preventive paint composition in which the mass ratio ((B)/(C)) of zinc dust (B) and aluminum phosphate (C) is 5.0 to 11.0,
The aluminum phosphate (C) is aluminum tertiary phosphate, aluminum dihydrogen orthophosphate, aluminum pyrophosphate, aluminum dihydrogen tripolyphosphate, or aluminum phosphite,
An antirust paint composition, wherein the content of the zinc dust (B) in the non-volatile matter contained in the composition is 50 to 70% by mass. 3. The antirust coating composition according to claim 1, wherein said aluminum phosphate (C) is aluminum dihydrogen tripolyphosphate. The antirust paint composition according to any one of claims 1 to 3, wherein the PVC (pigment volume concentration) of the antirust paint composition is 60 to 70%. An antirust coating film formed from the antirust coating composition according to any one of claims 1 to 4 . A primary rust preventive coating comprising the rust preventive coating according to claim 5 and having an average dry film thickness of 10 µm or less. A substrate with an antirust coating film comprising the antirust coating film according to claim 5 or the primary antirust coating film according to claim 6 and a substrate. A method for producing a substrate with an antirust coating, comprising the following steps [1] and [2].
[1] A step of coating a substrate with the anticorrosive coating composition according to any one of Claims 1 to 4 [2] Drying the anticorrosive coating composition coated on the substrate, The process of forming a coating film on the material

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