JP2023110746A - Rustproof coating, rustproof coating method and coated film - Google Patents

Abstract

To provide a rustproof coating and a rustproof method which are usable even in a place where ventilation is difficult, and a place where it is difficult to work while wearing a protective tool for respiratory, and can further obtain sufficient rustproof effect.SOLUTION: A rustproof coating contains aqueous acrylic resin emulsion, and a scaly stainless steel foil, especially, 60-85 mass% of an aqueous acrylic resin emulsion, 5-30 mass% of a scaly stainless steel foil, and 0.1-3 mass% of a zinc oxide, provided that a total amount does not exceed 100 mass%. A rustproof method coats the rustproof material onto a steel member with a spray, and forms a coated film.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a rust-preventing paint, a rust-preventing method, and a coating film suitable for rust-prevention of steel members such as bridges.

2. Description of the Related Art Conventionally, steel members such as girders and beams that constitute a bridge are rust-proofed by painting in order to prevent corrosion. Painted steel members need to be repainted or repaired depending on the degree of deterioration when the paint film or substrate deteriorates over time. Repainting is performed when the paint film or substrate has deteriorated over a relatively wide area.

On the other hand, when the range of deterioration of the paint film or base is relatively narrow, paint repair is performed by locally forming a paint film on the portion where the deterioration has occurred. Painting repairs are often performed as an emergency measure during periodic inspections that are performed at relatively short intervals.

BACKGROUND ART Conventionally, an epoxy resin-based paint obtained by mixing an epoxy resin-based main agent and an amine-based curing agent has been used for rust prevention of steel members (for example, Patent Document 1). When this type of epoxy resin-based paint is used for coating repair, the main agent and curing agent are mixed and then sprayed onto the deteriorated portion of the steel member to apply the mixture. The applied epoxy resin-based paint cures to form a coating film covering the deteriorated portion, thereby preventing rust on the deteriorated portion. This epoxy resin-based paint contains an aromatic hydrocarbon-based solvent such as ethylbenzene, xylene, or toluene in addition to a main agent and a curing agent.

JP-A-2-311514

Some of the steel members of bridges, such as box girders, form a closed space inside, and the closed space of the steel member tends to accumulate rainwater and corrode. When the paint is repaired in the closed space of such a bridge, if the conventional epoxy resin-based paint is used, the aromatic hydrocarbon-based solvent contained in the epoxy resin-based paint volatilizes and fills the closed space. .

Ethylbenzene, xylene, toluene, and the like, which are aromatic hydrocarbon solvents, are pointed out to have adverse effects on the human body, such as induction of neuropathy and cancer. For this reason, when handling substances containing aromatic hydrocarbon solvents such as ethylbenzene, installation of exhaust equipment, gas masks for organic gases, air supply masks, etc. are required in accordance with the Ordinance on Prevention of Hazards from Specified Chemical Substances and the Ordinance on Prevention of Organic Solvent Poisoning. use of respiratory protection is compulsory.

However, many of the bridges are located at high altitudes, making it difficult to install exhaust equipment in closed spaces. In addition, in the closed space of the bridge and on the route leading to the closed space, there are components of the bridge in close proximity. Therefore, the above conventional epoxy resin-based paint has the problem that it is practically impossible to use it in the closed space of the bridge.

Therefore, an object of the present invention is to provide a rust-preventive paint that can be used in places where ventilation is difficult or where it is difficult to work while wearing a respiratory protective device, and which provides a sufficient rust-preventive effect, a method of use, and a coating film. is to provide

In order to solve the above problems, the antirust paint of the present invention is characterized by containing a water-based acrylic resin emulsion and scale-like stainless steel foil.

The antirust paint of one embodiment further contains zinc oxide.

The antirust paint of one embodiment contains 60 to 85% by mass of water-based acrylic resin emulsion, 5 to 30% by mass of scale-like stainless steel foil, and 0.1 to 3% by mass of zinc oxide (however, the total amount is does not exceed 100% by mass).

In one embodiment, the scale-like stainless steel foil has a 50% particle size of 10 μm or more and 300 μm or less, a thickness of 0.1 μm or more and 5.0 μm or less, and an aspect ratio of 1 or more and 20 or less.

Further, in the rust prevention method of the present invention, the rust prevention paint is applied to a steel member by spraying to form a coating film.

In one embodiment of the rust prevention method, the steel member exists in a closed space.

Moreover, the coating film of the present invention is obtained from the antirust paint.

Since the anticorrosion paint of the present invention does not contain ethylbenzene, xylene, toluene, etc., which have been pointed out to be carcinogenic, it can be used in closed spaces without problems.

Hereinafter, embodiments of the antirust paint, antirust method, and coating film of the present invention will be described. The antirust paint of the present embodiment is suitably used for anticorrosion of steel. In particular, it is a rust-preventive paint that is suitable for local spray application to deteriorated portions of steel members used in structures such as existing bridges.

The antirust paint of this embodiment is formed by containing a water-based acrylic resin emulsion and scale-like stainless steel foil.

<Water-based acrylic resin emulsion>
In the rust-preventive paint of the present embodiment, a commercially available aqueous acrylic resin emulsion can be used as a vehicle for the antirust paint, and a synthetic resin emulsion or the like containing at least a (meth)acrylic acid derivative can be used. Examples of water-based acrylic resin emulsions include ethylene/vinyl acetate/(meth)acrylic acid derivative copolymer emulsion, ethylene/(meth)acrylic acid derivative copolymer emulsion, poly(meth)acrylic acid derivative emulsion, styrene/(meth) Acrylic acid derivative copolymer emulsions, vinyl acetate/(meth)acrylic acid derivative emulsions, and the like can be used. A (meth)acrylic acid derivative means an acid derivative such as acrylic acid and/or methacrylic acid, or an ester thereof, and contains at least one or more of these components.

Specific examples of the (meth)acrylic acid derivatives include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2 -hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide and the like.

By using a water-based acrylic resin emulsion for the rust-preventive paint, workers can safely apply the rust-preventive paint, and the coating film formed by this rust-preventive paint has good adhesion to the substrate and high weather resistance. Therefore, an excellent anticorrosion function can be obtained over a long period of time.

The glass transition temperature (Tg) of the synthetic resin component contained in the water-based acrylic resin emulsion is preferably 0° C. or higher and 50° C. or lower, and particularly preferably 10° C. or higher and 40° C. or lower. As a result, the coating film formed with the anticorrosive paint of the present embodiment has an excellent waterproof function.

The minimum film-forming temperature (MFT) of the synthetic resin component contained in the water-based acrylic resin emulsion is preferably -20°C or higher and 50°C or lower, particularly preferably 0°C or higher and 30°C or lower. As a result, the antirust paint of the present embodiment can obtain good film-forming properties. The minimum film-forming temperature can be obtained by a temperature gradient plate method conforming to ISO2115.

As the water-based acrylic resin emulsion, one obtained by a known production method can be used. For example, in the presence of an emulsifier, using a polymerization initiator, in water or a water-containing solvent, a polymerizable monomer that becomes a raw material for a synthetic resin can be produced by a method such as emulsion polymerization.

Known emulsifiers can be used, and anionic, nonionic, cationic or amphoteric surfactants and protective colloids such as polyvinyl alcohol can be used.

The non-volatile content of the synthetic resin contained in the aqueous acrylic resin emulsion is not particularly limited, but the non-volatile content is 30% by mass or more and 70% by mass or less from the viewpoint of the stability and handling properties of the aqueous acrylic resin emulsion. is preferable, and 40% by mass or more and 60% by mass or less is particularly preferable. Here, the non-volatile content can be measured in accordance with "Synthetic emulsion-Part 1: Determination of non-volatile content" specified in JIS K6828-1, and the drying conditions are a heating temperature of 105 ° C. and a drying time of 1. It's time.

The water-based acrylic resin emulsion preferably has a viscosity of 500 mpa·s or more and 100,000 mpa·s or less in order to ensure adhesion to the substrate. When the antirust paint is applied by spraying, it is particularly preferable to set the pressure to 2,000 mpa·s or more and 6,000 mpa·s or less in terms of less dripping and easy adjustment of the coating amount. Here, the viscosity is a value obtained by measuring the viscosity at 23° C. and a rotation speed of 10 rpm using a BH type viscometer.

The water-based acrylic resin emulsion preferably has a pH of 7.0 to 10.0 in order to ensure stable coating liquid properties.

<Scale-like stainless steel foil>
The scale-like stainless steel foils used in the antirust paint of this embodiment are laminated in the thickness direction inside the coating film to form a labyrinth structure. The labyrinth structure formed by this scaly stainless steel foil can effectively cut off the supply of water, oxygen, various ions, etc. that cause deterioration to the substrate, and can reduce the corrosion of the substrate. In the present invention, the scaly shape is not limited to a scaly shape, but may be an elongated linear shape that draws a straight line or a curved line, and the shape of a thin plate widely applies. In particular, linear-shaped stainless steel foils are preferably present together with other-shaped stainless steel foils, such as scale-shaped. In this case, the linear stainless steel foil can fill the gaps between other shaped stainless steel foils to further enhance the anti-corrosion performance.

The type of stainless steel that is the material of the scale-like stainless steel foil is not particularly limited, and known stainless steel can be used. Known stainless steels include ferritic stainless steel, austenitic stainless steel, martensitic stainless steel, duplex stainless steel, and the like. In particular, it is preferable to use ferritic stainless steel or austenitic stainless steel in terms of having high corrosion resistance and high workability. Among ferritic stainless steels, SUS430 is preferred, and among austenitic stainless steels, SUS304, SUS316, and SUS316L are preferred. In addition, stainless steel may contain inevitable impurities, and its composition is not particularly limited as long as the effect of the present invention is exhibited. The proportion is preferably 1% by mass or less.

In the scaly stainless steel foil, the 50% particle diameter (hereinafter referred to as Dp50), which is the particle diameter at 50% in the cumulative distribution, is preferably 10 μm or more and 300 μm or less, particularly 20 μm or more and 50 μm or less. preferable. Further, the scale-like stainless steel foil preferably has a thickness of 0.1 μm or more and 5.0 μm or less, and particularly preferably 0.2 μm or more and 1.0 μm or less. The scale-like stainless steel foil preferably has an aspect ratio of 1 or more and 20 or less, more preferably 2 or more and 15 or less. By using such scale-like stainless steel foil, a labyrinth structure can be stably formed in the coating film, and a coating film having excellent antirust performance can be obtained. Also, by using a stainless steel foil, high impact resistance, abrasion resistance, thermal stability, and chemical resistance can be ensured.

<Zinc oxide>
The rust-preventive paint of the present embodiment contains zinc oxide as a rust-preventive pigment in order to add rust-preventing action to the base material by sacrificial corrosion protection in addition to the rust-preventing action to the base material by the layered structure of the scale-like stainless steel foils. is preferred. The physical properties of zinc oxide are not particularly limited, but the average particle size is preferably 0.1 μm or more and 5.0 μm or less, and particularly preferably 0.2 μm or more and 1.0 μm or less. By using zinc oxide having such a particle size, it is possible to exhibit a rust-preventing effect on the substrate by means of sacrificial corrosion protection without causing defective formation of the layered structure of the scale-like stainless steel foil.

In the antirust paint of the present embodiment, the content of the water-based acrylic resin emulsion is determined from the viewpoint of the adhesion of the formed coating film to the base material and the effect of blocking deterioration factors by the acrylic resin. Based on the total amount of the composition, it is preferably within the range of 60% by mass or more and 85% by mass or less, and particularly preferably within the range of 65% by mass or more and 80% by mass or less.

In addition, in the antirust paint of the present embodiment, the content of the scale-like stainless steel foil is adjusted to the composition of the antirust paint from the viewpoint of forming a laminate in the coating film and thereby forming a labyrinth structure. Based on the total amount, it is preferably within the range of 5% by mass or more and 30% by mass or less, and particularly preferably within the range of 10% by mass or more and 30% by mass or less. If the content of the scale-like stainless steel foil is less than 5% by mass relative to the antirust paint, the formation of the labyrinth structure will be insufficient, making it difficult to obtain the antirust effect. On the other hand, if the content of the scale-like stainless steel foil is more than 30% by mass with respect to the antirust paint, the orientation of the scale-like stainless steel foil is disturbed, resulting in an insufficient antirust effect.

In addition, in the rust preventive paint of the present embodiment, the content of the zinc oxide is the content of the rust preventive paint composition, from the viewpoint of not hindering the exhibition of the anticorrosion effect by sacrificial corrosion prevention and the formation of the labyrinth structure by the scale-like stainless steel foil. It is preferably in the range of 0.1% by mass or more and 3% by mass or less based on the total amount.

The method of forming a coating film of the present embodiment comprises forming a wet coating film (uncured coating film) by applying the antirust coating of the above embodiment onto a substrate, and then curing the wet coating film. A coating film can be formed by The antirust paint of the above embodiment does not contain ethylbenzene, xylene, toluene, or the like as a component that volatilizes during the curing process of the wet paint film, so there is the inconvenience of diffusing carcinogenic substances to and around the position where the antirust paint is used. There is no Therefore, even in a place where ventilation is difficult or in a closed space, it is possible to apply the anticorrosive paint without using an exhaust system or respiratory protective equipment such as a gas mask for organic gas or an air-supplied mask. In particular, when closed space is formed inside and installation of exhaust equipment is difficult, such as a box girder of a bridge, or when it is difficult to work while wearing a gas mask for organic gas or an air supply mask. , since no exhaust equipment or respiratory protective equipment is required, the antirust coating can be applied quickly and easily.

The method of applying the anticorrosive paint of the present embodiment to the base material can be, for example, air spray, airless spray, rotary atomization coating machine, dip coating, applicator, brush, roller, in-mold coating, or the like. In particular, application by a spray such as an air spray or an airless spray is preferable from the viewpoint of quickness, adhesion of the coating film, and workability.

The thickness of the coating film formed by the antirust paint of the present embodiment is preferably 5 μm or more and 100 μm or less, more preferably 20 μm or more and 70 μm or less, in terms of cured film thickness.

The material of the base material to which the antirust paint of the present embodiment is applied is preferably steel from the viewpoints of the adhesion between the formed coating film and the base material and the antirust effect of the antirust paint. . That is, the base material is preferably a member made of steel. As such a steel member, those used for civil engineering structures such as bridges, buildings, ships, tanks and the like are preferable. Examples of materials for these steel members include general structural rolled steel specified by JIS G3101 (e.g., SS400, etc.), welded structure rolled steel specified by JIS G3106 (e.g., SM400, etc.), and JIS Examples thereof include rolled steel materials for building structures (for example, SN400, etc.) specified by G3136.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. It should be noted that the following examples are merely illustrative and do not limit the scope of the present invention. In the examples, "%" is based on mass unless otherwise specified. Moreover, the film thickness of the coating film is based on the cured coating film.

[Water-based acrylic resin emulsion]
Commercially available AP-6750 (manufactured by Showa Denko KK) was used as a water-based acrylic resin emulsion used as a vehicle in the examples. The physical properties of this aqueous acrylic resin emulsion are as follows.
Composition: Styrene-acrylic copolymer emulsion Glass transition temperature (Tg): 36°C
Minimum film-forming temperature (MFT): 0°C
Non-volatile content: 45 (44-47)%
Viscosity: 3000 (2000-6000) mPa s
pH: 8 (7-9)
Here, values in parentheses are standard values.

[Scale-like stainless steel foil]
Commercially available RFA4500 (manufactured by Toyo Aluminum Co., Ltd.) was used as the scale-like stainless steel foil used as the metal foil in the examples. The physical properties of this scale-like stainless steel foil are as follows.
Material: SUS316L
50% particle size: 28 μm
Thickness: 0.3 μm
Aspect ratio: 2.1

[Zinc oxide]
As the zinc oxide used as an antirust pigment in the examples, a commercially available zinc oxide JIS standard 2 equivalent (manufactured by Hakusui Tech Co., Ltd.) was used. The physical properties of this zinc oxide are as follows.
Average particle size: 0.3 μm

The water-based acrylic resin emulsion, scale-like stainless steel foil, zinc oxide, etc. were mixed at the mixing ratios shown in Table 1, and thoroughly stirred to produce the rust preventive paints of Examples 1, 2, 3 and 4. In Examples 2 and 4, titanium oxide was added as a pigment. The titanium oxide used as the pigment has a composition of titanium dioxide, a density of 4.1 and an average particle size of 0.25 μm, and is commercially available TITANIX JR-600A (manufactured by Tayca Corporation). In addition, in the antirust paint of the embodiment, the average particle size of titanium oxide may be 0.01 μm or more and 5.0 μm or less, and the mixing ratio of titanium oxide to the antirust paint can be set to 5% or more and 50% or less. By containing titanium oxide as a pigment, the effect of reinforcing the coating film can be obtained, and the strength of the coating film can be improved.

This rust-preventive paint was applied to a specimen by an air spray, and a rust-preventive test and a weather resistance test were conducted. In addition, commercially available Nisshin Industry Co., Ltd. Aquashield Spray was used as Comparative Example 1, Nisshin Industry Co., Ltd. Zinc Plus S Spray was used as Comparative Example 2, and Nisshin Industry Co., Ltd. Using Modified Epos Spray next as Comparative Example 3, the same test as in Examples was performed. As Comparative Example 4, the same water-based acrylic resin emulsion, scaly stainless steel foil and zinc oxide as in Examples were used, and the content of the scaly stainless steel foil was set to be greater than 30% by mass. As Comparative Example 5, the same water-based acrylic resin emulsion, scaly stainless steel foil and zinc oxide as in Examples were used, and the content of the scaly stainless steel foil was set to be less than 5% by mass. The components and blending ratios of Comparative Examples are as shown in Table 1. In Table 1, DISPERBYK-2015 (manufactured by BYK-Chemie) was used as a dispersant as an additive for dispersing the pigment and the metal foil. As additives, in addition to the dispersant, an antifoaming agent (BYK-1610, manufactured by BYK-Chemie) was used at a rate of 1% or less.

[Rust prevention test]
A steel plate was coated with the antirust paints of Examples and Comparative Examples so that the dry film thickness was 65 μm, and dried at 23° C. for 7 days to prepare test pieces. In accordance with JIS K5600-7-1 neutral salt spray resistance, the degree of rust and blistering generated on the scratched part and painted surface of the test piece after exposure to salt spray for 60 days was measured according to the following criteria. evaluated based on Evaluation results are as shown in Table 2.
○: Rust width of 0 to 1 mm on the scratched area, no or slightly rusted or blistered on the painted surface ×: Exceeding 1 mm of rusted width on the scratched area, rust or blistering on the painted surface [weather resistance test]
A test piece similar to the rust prevention test was irradiated with ultraviolet rays for 4 hours (irradiation intensity 90 mW, black panel temperature 63 ° C. humidity 70%) using an accelerated weathering tester Super UV Tester (SUV) manufactured by Iwasaki Electric Co., Ltd. A cycle of 4 hours of darkness (black panel temperature of 63° C. and humidity of 90%) and 4 hours of condensation (black panel temperature of 30° C. and humidity of 95%) was defined as one cycle, and the test was conducted for 360 hours. The state of the coated surface of the test piece after this was evaluated based on the following criteria. Table 2 shows the evaluation results.
〇: No whitening part ×: There is a whitening part

As can be seen from Table 2, the antirust paints of Examples 1 to 4 have the same antirust action as the antirust paints of Comparative Examples 1 to 3, and the weather resistance equivalent to that of Comparative Examples 2, 4, and 5. have. In addition, since the antirust paints of Examples 1 to 4 do not use solvents such as ethylbenzene, they do not induce neuropathy or cancer caused by volatile substances, nor do they cause toxicity caused by zinc powder as in Comparative Example 2. . Therefore, even in a closed space such as the inside of a box girder of a bridge, the application work can be carried out by spraying without wearing respiratory protective equipment or ventilation.

The present invention is not limited to the embodiments described above, and many modifications are possible within the technical concept of the present invention by those skilled in the art.

Claims (6)

An anticorrosive paint characterized by containing a water-based acrylic resin emulsion and scale-like stainless steel foil. 2. The antirust paint according to claim 1, further comprising zinc oxide. Contains 60 to 85% by mass of aqueous acrylic resin emulsion, 5 to 30% by mass of scale-like stainless steel foil, and 0.1 to 3% by mass of zinc oxide (however, the total amount does not exceed 100% by mass). The antirust paint according to claim 2, characterized by: 4. A rust prevention method comprising applying the rust prevention paint according to any one of claims 1 to 3 to a steel member by spraying to form a coating film. 5. A rust prevention method according to claim 4, wherein said steel member is present in a closed space. A coating film obtained from the antirust paint according to any one of claims 1 to 3.