JPH091727A - Painted metal plate - Google Patents

Abstract

PURPOSE: To provide a painted metal plate, whose environmental pollution resistance is enhanced with high durability being maintained. CONSTITUTION: A chemical-conversion treated film is formed on at least one surface of a metal plate. A prime coated film of 2μm or more is formed as the upper layer for the film. Furthermore, a painted film containing 5-100 pts.wt. molecular sheave having the small-hole diameter of 0.1-2.0nm with respect to 100 pts.wt. resin solid component is formed as the upper layer for the primer coated film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention selectively absorbs and permeates water and oil adhering to the surface of a coating film to keep the surface always dry and to prevent dust and soot which cause environmental pollution. TECHNICAL FIELD The present invention relates to a coated metal plate that is less likely to adhere to a coating film and has improved environmental pollution resistance, and particularly to a coated metal plate suitable for use on the road side or near a factory.

[0002]

2. Description of the Related Art Since roads and the vicinity of factories are environments where a large amount of environmental pollutants such as dust and soot are scattered, the painted metal plates installed on buildings and structures existing there are Since the contaminants are likely to be adsorbed on the coating film, stains are likely to be accumulated on the surface and the appearance is easily damaged.

On the other hand, recently, maintenance-free coating metal sheets are required, and not only the durability of the coating metal sheet is improved, but also the stain resistance of the coating film surface is required.

Fluorocarbon resin coatings were expected to be maintenance-free due to their excellent durability, but on the other hand, when used outdoors, pollutants tend to adhere and are difficult to remove, so they may be inferior in elbow environmental pollution. It has been pointed out.

In order to improve the resistance to environmental pollution, a method has been proposed in which the surface hardness of the coating film is made extremely hard by an electron beam curing method or an ultraviolet curing method to make it difficult for dirt to adhere (for example, Japanese Patent Publication No. 2). Japanese Patent No. 1242863, Japanese Patent Publication No. 31261
551). When the surface hardness of the coating film is increased in this way, stains do not penetrate into the coating film, so even if stains adhere, they will fall off if washed.

[0006] In addition, a method of imparting inorganic stain resistance by compounding an inorganic polymer in the coating film (for example,
Japanese Patent Publication No. 6-65527, Japanese Patent Publication No. 6-145453
Japanese Patent Publication No. 6-248233) has been proposed, and this method makes it difficult for contaminants to adhere due to the high water and oil repellency of the inorganic polymer.

The mechanism of pollution is as follows: rainwater, dew condensation on the surface of the coating film, water or oil contained in exhausted automobile exhaust gas, etc. adheres to the surface of the coating film, soot or dust It is considered that when the environmental pollutants are adsorbed and the water and oil evaporate and volatilize, the pollutants remain and become dirt.

However, even if the surface hardness of the coating film is increased as described above, the adhesion of water and oil cannot be prevented, and since it becomes a ball on the coating film and remains adhered forever,
Environmental pollutants are incorporated into the balls and become dirty. Although these stains are removed by washing, they cannot satisfy the maintenance-free requirement.

Further, even if the water repellency and oil repellency of a coating film are improved by an inorganic polymer, a coating film surface having a surface energy low enough to prevent both water and oil from adhering has not been obtained. Adsorbs pollutants after deposits. In addition, if the water repellency and oil repellency are enhanced, water or oil that has adhered to form beads can be easily collected, and stains can be partially concentrated to form streak-like stains, which makes the appearance conspicuous.

Recently, on the contrary, a hydrophilic polymer has been added to make the surface of the coating film hydrophilic. However, water is still attached to the coating film, and dirt is also attached thereto. On the other hand, in order to improve the water permeability and the hygroscopicity of the coating film, it has been studied to make the coating film water-absorbing (for example, Japanese Patent Publication No. 62-197469 and Japanese Patent Publication No. 62-26536).
No. 4). However, in the case of a coated metal plate, water absorption is not preferable because it causes deterioration of the coating film, a decrease in adhesion at the coating film-metal plate interface, and corrosion of the metal plate material.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is to maintain high durability while maintaining high durability.
It is an object of the present invention to provide a coated metal plate having improved resistance to environmental pollution.

[0012]

Means and Actions for Solving the Problems The present inventors have proposed that if water or oil adhering to the surface of a coating film can be removed from the coating surface by absorbing water or oil into the coating film or accelerating evaporation, it will cause contamination. I thought it would improve the sex. Then, as a result of an examination based on such a consideration result, by selectively absorbing and permeating moisture and oil into the coating film from the moisture and oil containing the contaminants attached to the coating film surface, It has been found that it becomes difficult to adhere. It was also found that the absorbed contaminants are appropriately diffused during drying so that they are not saturated in the coating film, so that the contamination prevention effect continues for a long period of time.

It is possible to selectively absorb and permeate water and oil into the coating film by adding a molecular sieve such as zeolite to the coating film. According to the results of studies by the present inventors, it has been found that there is an optimum blending ratio for maximizing the selectivity and the absorption capacity of the absorbing substance. Furthermore, it has been found that there is an optimum coating composition for obtaining high durability.

The present invention has been completed based on these findings, and has a chemical conversion coating film on at least one surface of a metal plate, and an undercoating film of 2 μm or more on the upper layer, and further A molecular sieve having a pore size of 0.1 to 2.0 nm is added to the upper layer in an amount of 5 to 100 parts by weight of the resin solid content.
Provided is a coated metal plate having a coating film containing 100 parts by weight.

Hereinafter, the present invention will be described in detail. The coated metal plate according to the present invention has a chemical conversion treatment film on at least one surface of the metal plate, an undercoat coating film on its upper layer, and a coating film containing a molecular sieve on its upper layer.

The top coating film used in the present invention has a pore size of 0.
1 to 2.0 nm molecular sieve was added to the resin solid content 10
It is 5 to 100 parts by weight with respect to 0 parts by weight. The medium which adheres to the surface of the coating film and causes the adsorption of contaminants is water or n-, iso-paraffin, or n-, i-paraffin.
It is a hydrocarbon compound such as so-olefin. And
Soot and dust are substances having a large particle size that are adsorbed to the medium and, after the medium evaporates, adhere to the surface of the coating film and cause stains in appearance.

Soot and dust do not strongly adhere even if they adhere to a coating film that is not wet with water or oil, and immediately fall due to wind or vibration. In order for these contaminants to strongly adhere to the coating surface, (1) adhesion of a medium such as water or oil to the coating surface → (2) adsorption to a medium such as soot or dust → (3) It is considered that the process of evaporating the medium and adhering contaminants to the surface of the coating film is performed. Therefore, as a method of preventing the adherence of contaminants to the coating surface, a method of preventing the adherence of contaminant media, or even if they adhere, immediately evaporate or absorb them, so that the time for adsorbing contaminants is not given Can be adopted.

In the present invention, a mechanism for preventing the adsorption of contaminants by keeping the coating film surface always dry by absorbing the moisture or oil of the contamination medium adhering to the coating film surface into the coating film has an appropriate pore size. It was realized by adding the content of the molecular sieve. Also, water and oil absorbed in the coating film are gradually released outside the coating film as the external environment dries, and they are inserted and inserted, so that they do not accumulate in the coating film and the absorption mechanism is maintained for a long time. Can be held.

Regarding the pore size and the amount of addition of the molecular sieve, water or oil as a polluting medium is about 0.1.
Since it has an effective diameter of 2.0 nm, and soot and dust, which are pollutants, are much larger than the diameter, an appropriate pore size is 0.1 to 2 that can selectively absorb water or oil. It needs to be at 0.0 nm.

The amount of the molecular sieve added to the top coating film is 5 to 100 parts by weight based on the resin solid content. If the amount added is less than 5 parts by weight with respect to 100 parts by weight of the resin solid content, the effect of absorption is insufficient, while if it exceeds 100 parts by weight, the cohesive force of the coating film decreases and corrosion resistance, chemical resistance, etc. Durability decreases.

The molecular sieve is preferably an inorganic material having a uniform pore size and a high molecular adsorption ability. For example, various zeolites of alumino-silicate metal salt crystals are most suitable. Further, in order to improve the dispersibility of the molecular sieve in the coating material for forming this coating film or to enhance the adsorption efficiency of water or oil, these molecular sieves are subjected to a surface treatment such as a coupling agent treatment. Is more preferable.

As the coating resin for holding such a molecular sieve, a coating resin generally used for a coated steel sheet for outdoor building materials can be used, and each resin such as polyester, fluorine, vinyl chloride, acrylic, silicone or the like can be used. Also, a composite of two or more of these can be used. Further, it is also possible to use a mixture of them with an amino resin such as a melamine resin or an isocyanate compound as a curing agent.

The addition of the molecular sieve into these resins can be carried out by mixing and stirring the molecular sieve with the resin, pigment, additive, etc. at the time of mixing the resin, pigment and additives. It is preferable to stir.

This topcoat film has the above-mentioned components and
It can be formed by applying a paint having the composition to a metal plate described later. The paint can be applied by using a coating line such as a roll coater method or a curtain flow coater method, spray coating, powder coating, or brush coating. The baking treatment may be room temperature drying or baking drying, and in the case of baking drying, a hot air heating method, a high frequency heating method or the like can be applied.

The dry coating film thickness of the top coating film is preferably 3 μm or more. This is because if the coating film thickness is less than 3 μm, the absorption layer becomes thin and sufficient stain resistance cannot be obtained. Next, the metal plate for forming the above-mentioned top coating film will be described.

As the metal plate to be coated used in the coated metal plate of the present invention, in addition to cold rolled steel plate, stainless steel plate, aluminum plate and copper plate, zinc, zinc alloy, aluminum, chromium, nickel or alloys thereof are plated. Various metal plates such as a plated steel plate can be used.

A chemical conversion treatment film is formed on the surface of the above-mentioned metal plate in order to secure adhesion with the coating film. The chemical conversion coating may be formed by a pre-coating treatment suitable for each metal plate, and may be performed by applying or spraying chromate, phosphate, or silane coupling agent, or by using an acid or alkali such as phosphoric acid, nitric acid, or hydrofluoric acid. In addition to those formed by an activation process or the like, those formed by an electrolytic process may be used.

An undercoat coating film is formed on the upper layer of the above chemical conversion treatment film, and the above-mentioned top coating film is further formed on the upper layer thereof. The topcoat contains water in the coating to absorb water, etc.If it is directly coated on the metal plate, water accumulates at the interface between the coating and the metal plate, which causes a problem between the metal plate and the topcoat. An undercoating film is applied between the metal plate and the topcoating film because it causes the decrease in the adhesiveness of.

As the undercoat coating film, a generally used undercoat paint can be used, but preferably, an epoxy resin-based paint or a polyester resin-based paint having high water-resistant adhesion and a composite resin-based paint thereof are used.

Further, when high corrosion resistance and coating adhesion are required, it is preferable to add a chromate compound as a rust preventive pigment in the undercoat paint. As the chromate compound, zinc chromate, strontium chromate, calcium chromate, barium chromate, etc. are suitable, and the content thereof is appropriately in the range of 1 to 60% by weight of the solid content in the undercoat coating film. is there.

The formation of the undercoating film is also carried out by applying such a paint as in the case of the topcoating film and baking it. The dry coating film thickness of the undercoat film needs to be 2 μm or more in order to obtain the above-mentioned effects. Below that, sufficient corrosion resistance cannot be obtained. Further, in order to improve durability, two or more primer layers may be applied to increase the undercoat film thickness.

If necessary, a plasticizer, a desiccant, a dispersant, a curing catalyst, a pigment, etc. may be added to the above-mentioned top coat film and undercoat coat film. It is effective to add an inhibitor. Also,
As the pigment, an extender pigment and a rust preventive pigment can be added in addition to various color pigments.

[0033]

EXAMPLES First, a top coating composition was produced as follows. According to the blending ratio shown in Table 1, titanium dioxide was added to a part of each resin-based clear paint and uniformly mixed, then dispersed with an attritor to a particle size of 10 μm or less, and the remaining clear while stirring. The coating composition, the acid catalyst, and the molecular sieve were added and mixed to obtain coating compositions T-1 to T-8 shown in Table 1. In addition, in Table 1,
T-1 to T-4 are coating compositions of the present invention examples, and T-5
-T-8 are coating compositions of comparative examples.

Next, a stainless steel plate or a hot-dip galvanized steel plate (each having a plate thickness of 0.5 mm) was subjected to a coating-type chromate treatment or a phosphate treatment, and then an epoxy resin-based paint shown in Table 2 as an undercoat paint or Polyester resin-based paint is applied and baked to form an undercoat coating film, and then the above coating composition is applied as an overcoat paint,
A baking treatment was performed to form a top coating film, and the obtained coated metal plate was subjected to various tests described below. Table 2 shows the manufacturing conditions of each coated metal plate and the results of various tests.

(Test / Evaluation Method) (1) Environmental Pollution Side wall of the road near the entrance of the Ogishima submarine tunnel in the NKK Keihin Works (distance from the road is 0.5 m, height from the ground is 2.3).
The sample was attached to m) so that it was perpendicular to the ground, and an exposure test was conducted for 6 months. The color tone before and after the exposure was measured, and the change in the L value (ΔL) calculated by the Hunter value was investigated. The color tone is spectrophotometer MSC-IS manufactured by Suga Test Instruments Co., Ltd.
-2B. In this test, ΔL is 10
The following were passed and those exceeding 10 were rejected.

(2) Corrosion resistance According to the method of JIS-Z2371, in a salt spray test,
Abnormalities such as rust, blistering, peeling and discoloration of the flat surface of the coating film after 2000 hours were investigated. Visually observe the changes in the coating surface,
Evaluation was made according to the following criteria. ◯: No change on coating surface (pass) ×: Rust, blistering, peeling, or discoloration on coating surface (fail) (3) Chemical resistance According to JIS-A5707, 5% nitric acid aqueous solution ,
1 ml of 5% sulfuric acid aqueous solution and 5% hydrochloric acid aqueous solution on the coating film
The solution was dropped, and allowed to stand in a constant temperature and humidity room at 20 ° C. and 50 RH% for 24 hours, then washed with water and dried, and changes in the coating film surface were visually observed and evaluated according to the following criteria. ◯: No change on coating film surface (pass) X: Discoloration or blistering on coating film surface (fail)

[0037]

[Table 1]

Table 1 Note 1) Polyester-melamine type paint (clear) (weight ratio: polyester resin / melamine resin / Solvesso # 10)
0 = 70/30/60, nonvolatile content 63%) Polyester resin finger: Byron 29XS (trade name of Toyobo Co., Ltd.) Melamine resin: Cymel 212 (Mitsui Cyanamid Co., Ltd.)
Trade name) 2) Fluorocarbon resin-based paint: Uniflon K Clear (Nippon Paint Co., Ltd., trade name, 50% non-volatile content) 3) Acrylic-silicone resin-based paint: Perhard 1000 Clear (Nippon Yushi Co., Ltd. trade name, non-volatile content) 50%) 4) Acrylic-isocyanate paint (clear) (weight ratio: acrylic resin / isocyanate compound / Solvesso # 100 = 70/30/60, non-volatile content 63%) Acrylyl resin finger: Byron 29XS (Toyobo Co., Ltd.) Trade name) Isocyanate compound: Desmodur BL3175 (Sumitomo Bayer Urethane Co., Ltd. trade name) 5) Taipek CR93 (Ishihara Sangyo Co., Ltd. trade name) 6) p-toluenesulfonic acid, 20 wt% solution 7) Molecular sieve type A : Zeolite 3A (particle size 10 μm or less) (pore size 0.3 nm)
(Trade name of Union Showa Co., Ltd.) B: Zeolite 13X (particle size 10 μm or less) (pore size 1.3 nm
) (Trade name of Union Showa Co., Ltd.) C: Silica gel 60 (particle size 15 to 40 μm) (average pore size 5.0 n
m) (Kanto Chemical Co., Ltd. product name)

[0039]

[Table 2]

Table 2 Note 1) Kind of metal plate SUS: SUS304 stainless steel plate GI: Hot dip galvanized steel plate (coating adhesion amount; Z-25) 2) Kind of chemical conversion treatment Cr: Coating type chromate treatment P: Phosphate treatment 3) Types of undercoating film P-1: Epoxy resin-based primer "Precolor WP-3" (trade name of NOF CORPORATION) P-2: Polyester resin-based primer "Precolor FX-2" (NOF ( Co., Ltd.) 4) Reachable plate temperature (× 60 seconds) As is clear from the results shown in Table 2, the coated metal plates of Comparative Examples 1 to 6, which are out of the conditions of the present invention, have environmental pollution resistance, corrosion resistance, It was confirmed that all of the coated metal plates of Examples 1 to 4 of the present invention were excellent in all properties, while they were unacceptable in terms of chemical resistance.

[0041]

As described above, according to the present invention, by selectively absorbing and permeating oil and water adhering to the surface of the coating film, dust or soot, which causes environmental pollution, is applied to the coating film. It is possible to obtain a coated metal plate that is excellent in environmental pollution resistance as well as in durability such as corrosion resistance and chemical resistance because it is difficult to adhere. Therefore, the coated metal plate of the present invention exhibits extremely excellent performance as an exterior plate used on the road side or near a factory.

Claims (1)

[Claims] 1. A metal plate having a chemical conversion coating on at least one surface thereof, an undercoating film having a thickness of 2 μm or more as an upper layer, and a molecular weight having a pore diameter of 0.1 to 2.0 nm as an upper layer. 5 to 100 parts by weight of resin solids
A coated metal plate having a coating film containing 100 parts by weight.