JP7390412B2 - Rust-preventing paint, rust-preventing method, and coating film - Google Patents

Description

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

BACKGROUND ART Conventionally, steel members such as girders and beams constituting bridges have been coated with rust-proofing to prevent corrosion. If the paint film or base material of painted steel members deteriorates over time, they are repainted or repaired depending on the degree of deterioration. Repainting is carried out when the paint film or base material has deteriorated over a relatively wide area, and large-scale scaffolding is erected to form a new paint film on the entire surface of the steel parts.

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

Conventionally, for rust prevention of steel members, an epoxy resin paint made by mixing an epoxy resin base agent and an amine hardening agent has been used (for example, Patent Document 1). When this type of epoxy resin paint is used for painting repair, it is mixed with a base agent and a hardening agent, and then applied by spraying onto deteriorated areas of steel members. The applied epoxy resin paint is cured to form a coating film that covers the deteriorated area, thereby making it possible to prevent the deteriorated area from rusting. This epoxy resin paint contains an aromatic hydrocarbon solvent such as ethylbenzene, xylene, toluene, etc. in addition to a base agent and a curing agent.

Japanese Patent Application Publication No. 2-311514

Some steel members of bridges, such as box girders, form closed spaces inside, and the closed spaces of steel members are susceptible to corrosion due to accumulation of rainwater. If you use the above-mentioned conventional epoxy resin paints when repairing the paint inside the closed space of such a bridge, the aromatic hydrocarbon solvent contained in the epoxy resin paint will volatilize and fill the closed space. .

It has been pointed out that aromatic hydrocarbon solvents such as ethylbenzene, xylene, and toluene have adverse effects on the human body, such as inducing neurological disorders and cancer. For this reason, when handling substances containing aromatic hydrocarbon solvents such as ethylbenzene, according to the Ordinance on Prevention of Hazards from Specified Chemical Substances and the Ordinance on Prevention of Organic Solvent Poisoning, it is necessary to install exhaust equipment, use a gas mask for organic gases or a ventilation mask, etc. The use of respiratory protection is mandatory.

However, since many bridges are located at high places, it is difficult to install exhaust equipment in closed spaces. In addition, since constituent members of the bridge are located close to each other in the closed space of the bridge and the route leading to the closed space, it is difficult to work or move when wearing a respiratory protector. Therefore, the above conventional epoxy resin paint has a problem in that it is virtually impossible to use it in the closed space of a bridge.

Therefore, the object of the present invention is to provide a rust-preventing paint, a method of use, and a coating film that can be used even in places where ventilation is difficult or where it is difficult to work while wearing a respiratory protector, and which also has a sufficient rust-preventing effect. Our goal is to provide the following.

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

The anticorrosion paint of one embodiment further contains zinc oxide.

The anticorrosive 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 of the anticorrosion paint, the scale-like stainless steel foil has a 50% particle diameter 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 above-mentioned 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 is located in a closed space.

Moreover, the coating film of the present invention is obtained from the above-mentioned anticorrosive paint.

The anticorrosive paint of the present invention does not contain ethylbenzene, xylene, toluene, etc., which are known to be carcinogenic, so it can be used in closed spaces without any problems.

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

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

<Aqueous acrylic resin emulsion>
In the anticorrosive paint of the present embodiment, a commercially available aqueous acrylic resin emulsion can be used as the aqueous acrylic resin emulsion used as the vehicle, and a synthetic resin emulsion containing at least a (meth)acrylic acid derivative can be used. Examples of aqueous 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, and styrene/(meth)acrylic acid derivative emulsion. Acrylic acid derivative copolymer emulsion, vinyl acetate/(meth)acrylic acid derivative emulsion, etc. can be used. (Meth)acrylic acid derivative means acid derivatives such as acrylic acid and/or methacrylic acid, and esters thereof, and contains at least one type of these components.

Specific examples of the above (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, -hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide and the like.

By using a water-based acrylic resin emulsion as the anti-rust paint, workers can safely apply the anti-rust paint, and the film formed with this anti-rust paint has good adhesion to the substrate and high weather resistance. As a result, excellent rust prevention function can be obtained over a long period of time.

The glass transition temperature (Tg) of the synthetic resin component contained in the aqueous acrylic resin emulsion is preferably 0°C or more and 50°C or less, particularly preferably 10°C or more and 40°C or less. As a result, the coating film formed with the anticorrosive paint of this embodiment can have an excellent waterproof function.

Further, the minimum film forming temperature (MFT) of the synthetic resin component contained in the aqueous acrylic resin emulsion is preferably -20°C or more and 50°C or less, particularly preferably 0°C or more and 30°C or less. Thereby, the anticorrosive paint of this embodiment can obtain good film-forming properties. Note that the minimum film forming temperature can be determined by a temperature gradient plate method based on ISO2115.

The aqueous acrylic resin emulsion can be obtained by a known production method. For example, in the presence of an emulsifier, a polymerizable monomer, which is a raw material for a synthetic resin, is produced by using a polymerization initiator in water or a water-containing solvent. It can be produced by emulsion polymerization or the like.

As the emulsifier, known emulsifiers can be used, including anionic, nonionic, cationic, or amphoteric surfactants, protective colloids such as polyvinyl alcohol, and the like.

The non-volatile content of the synthetic resin contained in the aqueous acrylic resin emulsion is not particularly limited, but from the standpoint of stability and handling properties of the aqueous acrylic resin emulsion, the non-volatile content is 30% by mass or more and 70% by mass or less. is preferable, and particularly preferably 40% by mass or more and 60% by mass or less. Here, the non-volatile content can be measured in accordance with "Synthetic emulsions - Part 1: How to determine 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 aqueous 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 anticorrosive paint is applied by spraying, a pressure of 2,000 mpa·s or more and 6,000 mpa·s or less is particularly preferable because there is little dripping and the amount of application can be easily adjusted. Here, the viscosity is a value obtained by measuring the viscosity at 23° C. and a rotational speed of 10 rpm using a BH type viscometer.

The pH of the aqueous acrylic resin emulsion is preferably 7.0 to 10.0 in order to ensure stable coating liquid properties.

<Scaly stainless steel foil>
The scale-like stainless steel foil used in the anticorrosive paint of this embodiment is laminated in the thickness direction inside the paint film to form a labyrinth structure. The labyrinth structure formed by this scale-like stainless steel foil can effectively cut off the supply of water, oxygen, various ions, etc. that cause deterioration to the substrate, and reduce corrosion of the substrate. In the present invention, the scaly shape is not limited to the scaly shape, but may also be an elongated linear shape that draws a straight line or a curve, and broadly corresponds to the shape of a flake. In particular, it is preferred that linear stainless steel foils are present together with other shapes of stainless steel foils, such as scale shapes. In this case, the linear stainless steel foil can fill the gaps between the stainless steel foils of other shapes, thereby further improving the anticorrosion performance.

The type of stainless steel that is the material for this scale-like stainless steel foil is not particularly limited, and any known stainless steel can be used. Known stainless steels include ferritic stainless steel, austenitic stainless steel, martensitic stainless steel, and two-phase stainless steel. In particular, it is preferable to use ferritic stainless steel or austenitic stainless steel because they have high corrosion resistance and high workability. Among ferritic stainless steels, SUS430 is preferred, and among austenitic stainless steels, SUS304, SUS316, and SUS316L are preferred. Note that stainless steel may contain unavoidable impurities, and its composition is not particularly limited as long as it exhibits the effects of the present invention, but from the viewpoint of corrosion resistance and workability, the inclusion of unavoidable impurities in scale-like stainless steel foil is The proportion is preferably 1% by mass or less.

This scale-like stainless steel foil preferably has a 50% particle diameter (hereinafter referred to as Dp50), which is a particle diameter that accounts for 50% in the cumulative distribution, of 10 μm or more and 300 μm or less, particularly 20 μm or more and 50 μm or less. preferable. Further, the thickness of the scale-like stainless steel foil is preferably 0.1 μm or more and 5.0 μm or less, particularly preferably 0.2 μm or more and 1.0 μm or less. Further, the aspect ratio of the scale-like stainless steel foil is preferably 1 or more and 20 or less, particularly preferably 2 or more and 15 or less. By using such a 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. Further, by using stainless steel foil, high impact resistance, abrasion resistance, thermal stability, and chemical resistance can be ensured.

<Zinc oxide>
The rust-preventing paint of this embodiment contains zinc oxide as a rust-preventing pigment in order to add rust-preventing action to the base material through sacrificial corrosion protection in addition to the rust-preventing action on the base material due to the laminated structure of scale-like stainless steel foil. is preferred. The physical properties of zinc oxide are not particularly limited, but the average particle size is preferably in the range of 0.1 μm or more and 5.0 μm or less, particularly preferably in the range of 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 the rust-preventing effect of the substrate by sacrificial corrosion protection without causing formation defects in the laminated structure of the scale-like stainless steel foil.

In the rust-preventing paint of this embodiment, the content of the water-based acrylic resin emulsion is determined from the viewpoints of adhesion of the formed coating film to the base material and the effect of blocking deterioration factors by the acrylic resin. 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, based on the total amount of the composition.

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

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

The method for forming a coating film of this embodiment is to form a wet coating film (uncured coating film) by coating the anticorrosive paint of the above embodiment onto a base material, and then harden this wet coating film. A coating film can be formed. The rust-preventing paint of the above embodiment does not contain ethylbenzene, xylene, toluene, etc. as components that volatilize during the curing process of the wet paint film, so there is an inconvenience that carcinogenic substances may be spread in and around the location where the rust-preventive 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 anticorrosion paint without using exhaust equipment or respiratory protective equipment such as an organic gas gas mask or an air supply mask. Particularly when a closed space is formed inside, such as a box girder on a bridge, and it is difficult to install exhaust equipment, or when it is difficult to perform work while wearing an organic gas gas mask or air supply mask. Since no exhaust equipment or respiratory protection equipment is required, the rust-proofing paint can be applied quickly and easily.

The anticorrosive paint of this embodiment can be applied to the base material by, for example, air spray, airless spray, rotary atomizer, dip coating, applicator, brush, roller, in-mold coating, etc. In particular, application by spraying such as air spray or airless spray is preferred from the viewpoint of speed, adhesion of the coating film, and workability.

The thickness of the coating film formed with the anticorrosive paint of this embodiment is preferably 5 μm or more and 100 μm or less in terms of cured film thickness, particularly preferably 20 μm or more and 70 μm or less.

The material of the base material to which the anti-corrosive paint of this embodiment is applied is preferably steel from the viewpoint of the adhesion between the formed coating film and the base material, the anti-rust effect of the anti-rust paint, etc. . That is, the base material is preferably a steel member. As such steel members, those used for civil engineering structures such as bridges, buildings, ships, tanks, etc. are preferable. Examples of the materials of these steel members include rolled steel for general structures specified by JIS G3101 (for example, SS400, etc.), rolled steel for welded structures specified by JIS G3106 (for example, SM400, etc.), and JIS Examples include rolled steel materials for architectural structures specified by G3136 (for example, SN400, etc.).

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note 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. Further, the film thickness of the coating film is based on the cured coating film.

[Aqueous acrylic resin emulsion]
The water-based acrylic resin emulsion used as a vehicle in the Examples was commercially available AP-6750 (manufactured by Showa Denko K.K.). 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℃
Nonvolatile content: 45 (44-47)%
Viscosity: 3000 (2000-6000) mPa・s
pH: 8 (7-9)
Here, the values in parentheses are standard values.

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

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

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

This anti-rust paint was applied to a test piece by air spray, and a rust-proof test and a weather resistance test were conducted. In addition, commercially available Aqua Shield Spray manufactured by Nissin Industry Co., Ltd. was used as Comparative Example 1, Zinc Plus S Spray manufactured by Nissin Industry Co., Ltd. was used as Comparative Example 2, and commercially available Aqua Shield Spray manufactured by Nissin Industry Co., Ltd. was used as Comparative Example 2. Modified Epospray next was used as Comparative Example 3, and the same test as in the example was conducted. In addition, as Comparative Example 4, the same water-based acrylic resin emulsion, scaly stainless steel foil, and zinc oxide as in the example were used, and the content of the scaly stainless steel foil was set to be greater than 30% by mass. Furthermore, as Comparative Example 5, the same water-based acrylic resin emulsion, scale-like stainless steel foil, and zinc oxide as in the example were used, and the content of the scale-like stainless steel foil was set to be smaller than 5% by mass. The components and blending ratios of the comparative example are as shown in Table 1. In Table 1, the dispersant used as an additive is one that disperses the pigment and metal foil, and DISPERBYK-2015 (manufactured by BYK-Chemie) was used. In addition to the above-mentioned dispersant, an antifoaming agent (BYK-1610, manufactured by BYK-Chemie) was used as an additive at a rate of 1% or less.

[Rust prevention test]
A test piece was prepared by coating a steel plate with the anticorrosion paints of Examples and Comparative Examples so that the dry film thickness was 65 μm, and drying it at 23° C. for 7 days. In accordance with JIS K5600-7-1 neutral salt spray resistance, the degree of rust and blistering that occurred on the scratches and painted surface of the test piece after 60 days of exposure to salt spray was evaluated according to the following criteria. The evaluation was based on The evaluation results are shown in Table 2.
〇: Rust width in the scratch area is 0 to 1 mm, there is no or slight rust or blistering on the painted surface ×: Rust width in the scratch area exceeds 1 mm, rust or blistering occurs on the painted surface [Weather test]
A test piece similar to the rust prevention test was irradiated with ultraviolet light 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. A 360-hour test was conducted with one cycle of 4 hours of darkness (black panel temperature: 63° C. and humidity: 90%) and 4 hours of dew condensation (black panel temperature: 30° C. and humidity: 95%). The state of the painted surface of the test piece after this was evaluated based on the following criteria, and the evaluation results are as shown in Table 2.
〇: There is no whitening area ×: There is a whitening area

As can be seen from Table 2, the anti-rust paints of Examples 1 to 4 have the same anti-rust effect as the anti-rust paints of Comparative Examples 1 to 3, and the same weather resistance as Comparative Examples 2, 4, and 5. have Furthermore, since the anti-corrosion paints of Examples 1 to 4 do not use solvents such as ethylbenzene, they do not cause neurological disorders or cancer caused by volatile substances, and there is no 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, application can be carried out by spraying without wearing a respiratory protector or providing ventilation.

The present invention is not limited to the embodiments described above, and many modifications can be made within the technical idea of the present invention by those skilled in the art.

Claims (4)

Contains 60 to 85 mass % of an aqueous acrylic resin emulsion with a nonvolatile content of 30 mass % to 70 mass %, 5 to 30 mass % of scaly stainless steel foil, and 0.1 to 3 mass % of zinc oxide (however, (The total amount does not exceed 100% by mass.) A rust prevention method comprising spraying the rust prevention paint according to claim 1 onto a steel member to form a coating film. 3. The rust prevention method according to claim 2 , wherein the steel member is present in a closed space. A coating film obtained from the anticorrosive paint according to claim 1 .