JP5080922B2 - Non-chromium resin coated metal plate with excellent end face corrosion resistance - Google Patents

Description

  The present invention relates to a resin-coated metal plate that is excellent in corrosion resistance, in particular, end surface corrosion resistance, even if it is not subjected to chromate treatment.

  The cut surface (end face) and collar of the resin-coated metal plate are exposed to the metal base of the metal plate and are difficult to exert the rust-preventing effect of galvanizing or resin film. When a rust pigment is added, Zn ions eluted from the galvanized surface and the metal in the rust preventive pigment form a passive film, thereby suppressing corrosion of zinc and ensuring a certain degree of corrosion resistance.

  For example, Patent Document 1 discloses a technique for improving the corrosion resistance of the end face by including a vanadium / phosphate anticorrosive pigment in a resin film in addition to a chromate anticorrosive pigment. In Patent Document 1, a function (deposition function) in which phosphate ions and dissolved zinc form a refractory film and a redox potential slightly higher than the corrosion potential of zinc due to the action of vanadate ions. According to the function (oxydizer function) and the like shown, it was shown that good corrosion resistance was exhibited in a 500 hour salt spray test.

  Patent Document 2 discloses a primer composition using a chromate rust preventive pigment and a phosphite rust preventive pigment in combination. It is described that a phosphate-based film improves end face corrosion resistance (750 hour salt spray test).

  These techniques described in Patent Documents 1 and 2 both use a chromate-based anticorrosive pigment, and are against the current trend of chromium-free. For this reason, the present applicant discloses, in Patent Document 3, a technique capable of providing a surface-treated galvanized steel sheet having excellent end face corrosion resistance without using a chromium compound. In the technique of Patent Document 3, alkaline earth metal (water) oxide such as magnesium oxide is present in the resin film, so that it is dissolved as alkali ions in a corrosive environment to suppress a decrease in pH. It is intended to exhibit a buffering action that controls elution, and is characterized by long-term endurance corrosion resistance even when the surrounding environment changes between acidic and neutral.

However, further improvement is required for the end surface corrosion resistance of the resin-coated metal plate. For example, at end faces and ridges in a wet environment that is always exposed to water, Zn ions and metal ions in the rust preventive pigment are washed away by water, so a passive film cannot be formed. Although red rust is generated in a short time, even in such a case, there is a demand for a resin-coated metal plate exhibiting good end face corrosion resistance. The above prior art cannot be said to be an end face corrosion resistance improvement technique assuming such a severe environment.
JP-A-6-9902 Japanese Patent Laid-Open No. 11-158417 JP 2006-28582 A

  Therefore, in the present invention, for example, it is an object to provide a non-chromium-based resin-coated metal plate capable of delaying the occurrence of red rust even in end surfaces and ridges in a wet environment that is always exposed to water. As listed.

The present invention, which has solved the above problems, is a non-chromium resin-coated metal plate in which an undercoating film and / or an overcoating film is formed on a non-chromic base treatment film, the undercoating film and / or overcoating. The coating film comprises 5 to 40 masses of sustained release rust preventive fine particles in which porous inorganic fine particles and metal compound rust preventive pigments are combined with respect to 100 parts by mass of coating film components other than the sustained release rust preventive fine particles. The metal ion elution rate from the rust preventive pigment is 0 when the resin coated metal plate is engraved with 100 squares of 1 mm × 1 mm and then immersed in a carbonate pH standard solution at 40 ° C. It is a non-chromium resin-coated metal plate having excellent end face corrosion resistance and having a characteristic of 0.001 to 1.0 mg / l · m ² · hr.

  When the average particle diameter of the sustained-release rust-preventing fine particles is 1 to 10 μm, the balance between corrosion resistance and workability is further improved.

  When the release rate of metal ions when the sustained-release rust-preventing fine particles are immersed in an aqueous sodium hydroxide solution having a pH of 10 at 40 ° C. is 0.005 to 0.5 mg / l · g · hr, the metal from the coating film This is preferable because the elution rate of ions can be easily set within a suitable range.

  The rust preventive pigment compounded with the sustained release rust preventive fine particles is selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium phosphate, magnesium carbonate, magnesium chloride, magnesium oxalate, magnesium sulfate and hydrates thereof. An excellent rust-preventing effect when it is at least one magnesium compound selected from the group consisting of aluminum tripolyphosphate, aluminum phosphate and aluminum phosphate dihydrate. It is preferable because it exhibits.

  It is preferable that the porous inorganic fine particles used for the sustained release rust preventive fine particles are porous silica fine particles because they can be easily combined with the rust preventive pigment. Further, the undercoat and / or the topcoat may further contain a rust preventive pigment, and the end surface corrosion resistance is further improved.

  In the present invention, since the resin coating film of the resin-coated metal plate contains sustained-release rust-preventing fine particles, even on the end face and the heel part in a wet environment that is always exposed to water, The rust-preventing components are gradually eluted into the water from the release rust-preventing fine particles, and the occurrence of red rust is suppressed for a long time. Therefore, the metal plate of the present invention is useful as a PCM (pre-coated metal plate) used in a relatively severe corrosive environment such as an outdoor unit of an air conditioner.

The present invention relates to a non-chromium resin-coated metal plate in which an undercoat film and / or a topcoat film is formed on a non-chromium base treatment film, and the undercoat film and / or the overcoat film are porous. 5-40 parts by mass of sustained-release rust-preventing fine particles in which fine inorganic fine particles and metal compound rust-preventive pigments are combined with respect to 100 parts by mass of coating film components other than the sustained-release rust-proof fine particles, When 100 squares of 1 mm × 1 mm are cut on a coated metal plate and then immersed in a carbonate pH standard solution at 40 ° C., the elution rate of metal ions eluted from the rust preventive pigment is 0.001 to 1. It is characterized by 0 mg / l · m ² · hr.

The resin-coated metal plate of the present invention is a non-chromium resin-coated metal plate. Non-chromium means that no chromate base treatment is applied. The type of the metal plate used in the present invention is not particularly limited, and includes a metal plate of a steel plate or a non-ferrous metal plate, a plated metal plate obtained by plating a single metal or various alloys on these, and the like. Specifically, for example, steel sheets such as hot-rolled steel sheets, cold-rolled steel sheets, and stainless steel sheets; plated steel sheets such as hot-dip galvanized steel sheets, alloyed hot-dip galvanized steel sheets, electrogalvanized steel sheets, and electric Zn-Ni alloy-plated steel sheets; Examples thereof include non-ferrous metal plates such as aluminum, titanium, and zinc, or plated non-ferrous metal plates obtained by plating them. The metal plate is subjected to non-chromium base treatment. The base treatment may be non-chromic, and examples thereof include phosphate treatment, pickling treatment, alkali treatment, electrolytic reduction treatment, silane coupling treatment, and inorganic silicate treatment. In the case of phosphating, it is preferable to set the adhesion amount to 0.05 to 3.0 g / m ² .

  The resin-coated metal plate of the present invention has an undercoat film and / or a topcoat film. That is, the composition of only the top coat film or the two-layer structure having the top coat film on the undercoat film may be used. Moreover, what laminated | stacked another coating film may be used.

  The main component of the undercoat film and the topcoat film is an organic resin. Examples of the resin include polyester resins, acrylic resins, urethane resins, polyolefin resins, fluorine resins, silicone resins, and mixtures or modified resins of these resins. Of these, organic solvent-soluble (amorphous) polyester resins are preferred. As the organic solvent-soluble polyester resin, “Byron (registered trademark)” series manufactured by Toyobo Co., Ltd. is preferable in that a wide variety of types can be obtained. The polyester resin may be crosslinked with a melamine resin or an epoxy resin. Examples of the melamine resin include “Sumimar (registered trademark)” series manufactured by Sumitomo Chemical Co., Ltd. and “Cymel (registered trademark)” series manufactured by Cytec. Examples of the epoxy resin include “jER (registered trademark)” series manufactured by Japan Epoxy Resin. The crosslinking agent is preferably blended in the dried resin film so that the crosslinking agent (after reaction) is 0.5 to 30% (more preferably 5 to 25%) by mass.

  In the resin-coated metal plate of the present invention, sustained-release rust-preventing fine particles in which porous inorganic fine particles and metal compound-based anti-rust pigments are combined are included in the undercoat and / or topcoat. “The composite of the porous inorganic fine particles and the metal compound rust preventive pigment” refers to a state in which the metal compound rust preventive pigment is adhered in the pores or on the surface of the porous inorganic fine particles. "Sustained release rust preventive fine particles" means the dissolution rate of metal compound rust preventive pigment from the sustained release rust preventive fine particles rather than the dissolution rate of metal compound rust preventive pigment itself into water by the above-mentioned compounding. Means that is getting smaller.

  The rust preventive pigment has a buffer action of pH change by elution of metal ions, which are rust preventive components, in a corrosive environment (pH 8.5 to 10.5), and is free from Zn ions eluted from the surface of the Zn plating. Forms a working film to suppress corrosion of zinc and develop corrosion resistance. The ratio of metal ions and Zn ions of the rust preventive component that forms the passive film is constant. Therefore, if the elution rate of metal ions, which are anticorrosive components, is high in a corrosive environment, metal ions that did not react with Zn ions will also be eluted and washed away, and there will be insufficient metal ions to form a new passive film. Therefore, corrosion progresses. However, if the sustained-release rust-preventing fine particles are contained in the coating film, elution and loss of metal ions derived from the rust-preventing pigment can be controlled to a low level even when the coating film is in contact with water. As a result, metal ions are eluted from the coating film, and the occurrence of red rust on the end face and the buttock can be suppressed (expression of end face corrosion resistance).

In order to maintain this end face corrosion resistance effectively over a long period of time, 100 squares of 1 mm × 1 mm are cut into a resin-coated metal plate and then immersed in a 40 ° C. carbonate pH standard solution (pH 10.01). Sometimes, the elution rate of metal ions eluted from the rust preventive pigment must be 0.001 to 1.0 mg / l · m ² · hr. When the elution rate is less than 0.001 mg / l · m ² · hr, the amount of metal ions in the corrosive environment is too small, and it is difficult to prevent red rust from occurring on the end face and the collar portion over a long period of time. However, if the elution rate of metal ions exceeds 1.0 mg / l · m ² · hr, endurance corrosion resistance cannot be obtained. The lower limit of the dissolution rate is more preferably 0.005 mg / l · m ² · hr, and the upper limit is 0.5 mg / l · m ² · hr. The conventional silica-based rust preventive agent (calcium ion exchanged silica) has an elution rate of 2.2 mg / l · m ² · hr in a corrosive environment, which is much lower than that of the sustained-release rust preventive fine particles of the present invention. Therefore, the endurance improvement effect of the end face corrosion resistance as in the present invention cannot be obtained. When measuring the elution rate, the grid is cut so as to reach the base metal plate. The carbonate pH standard solution is an aqueous solution having 0.21% by mass (0.02490 mol / l) of sodium bicarbonate and 0.26% by mass (0.02491 mol / l) of sodium bicarbonate, and is commercially available from, for example, Kanto Chemical Co., Inc. Has been.

  The elution rate is defined as the elution rate of metal ions from the resin-coated metal plate assuming an actual corrosive environment, but the sustained-release rust preventive fine particles themselves of the present invention are converted into an aqueous solution of sodium hydroxide having a pH of 10 at 40 ° C. The elution rate of metal ions when immersed is preferably 0.005 to 0.5 mg / l · g · hr. This is because, within this range, the elution rate of metal ions from the resin-coated metal plate can be easily set within the above preferred range.

  Sustained release rust preventive fine particles can be obtained by combining porous inorganic fine particles and metal compound rust preventive pigments. Porous inorganic fine particles include metal oxides such as silica, titanium oxide, iron oxide, cobalt oxide, zinc oxide, nickel oxide, manganese oxide, and alumina; iron hydroxide, nickel hydroxide, aluminum hydroxide, calcium hydroxide, Metal hydroxides such as chromium hydroxide; carbonates such as calcium carbonate and barium carbonate; silicates such as calcium silicate, barium silicate and magnesium silicate; calcium phosphate, barium phosphate, magnesium phosphate and zirconium phosphate And phosphates such as apatite; In particular, silica fine particles are preferable from the viewpoint of corrosion resistance.

  The average particle size of the porous inorganic fine particles is preferably 1 to 10 μm. If it is smaller than 1 μm, it is not preferable because it becomes difficult to produce porous inorganic fine particles and the corrosion resistance is lowered. If it exceeds 10 μm, the workability tends to decrease, which is not preferable. A more preferable average particle diameter is 1 to 3 μm. The average particle diameter of the porous inorganic fine particles and the average particle diameter of the sustained-release rust-preventing fine particles after the composite are hardly changed. Therefore, the preferable average particle diameter of the sustained release rust preventive fine particles is also 1 to 10 μm (more preferably 1 to 3 μm). The average particle diameter is obtained, for example, by calculating an average value of fine particles observed in the visual field using a scanning electron microscope (magnification 5000 times). Alternatively, “SA-P3” manufactured by Shimadzu Corporation can be used to calculate by the centrifugal sedimentation method.

The degree of porosity of the porous inorganic fine particles is preferably 100 to 800 m ² / g in terms of specific surface area. This is because an appropriate dissolution rate is obtained after compounding with the rust preventive pigment. As such porous inorganic fine particles, for example, “Godball (registered trademark)” series (manufactured by Suzuki Oil & Fats Industries Co., Ltd.) and porous silica fine particles (manufactured by Enex; SE MCB-FP / 2) are available. is there. The above “Godball (registered trademark)” includes non-hollow silica type E-2C (average particle size 0.9 to 1.4 μm, specific surface area 350 to 500 m ² / g), E-6C (average particle size 2). 0.0 to 2.5 μm, specific surface area 250 to 400 m ² / g), E-2C (average particle size 0.9 to 1.4 μm, specific surface area 350 to 500 m ² / g), E-16C (average particle size 4) 0.0-5.3 μm, specific surface area 300-550 m ² / g), D-11C (average particle size 3.0-4.0 μm, specific surface area 280-500 m ² / g); hollow silica type B-6C ( Average particle diameter 2.0-2.5 μm, specific surface area 250-400 m ² / g), B-25C (average particle diameter 8.0-10.0 μm, specific surface area 400-550 m ² / g); superporous silica Type AF-6C (average particle size 2.5-3.5 μm, specific surface Product 600-700 m ² / g), AF-16C (average particle size 4.0-5.3 μm, specific surface area 600-700 m ² / g), SF-16C (average particle size 4.0-5.3 μm, ratio) Surface area of 600 to 700 m ² / g).

  As the metal compound-based anticorrosive pigment, those having a low solubility in water and a low elution rate are preferable. End surface corrosion resistance can be exhibited over a long period of time. Specifically, magnesium compounds such as magnesium oxide, magnesium hydroxide, magnesium phosphate, magnesium carbonate, magnesium chloride, magnesium oxalate, magnesium sulfate and hydrates thereof; aluminum tripolyphosphate, aluminum phosphate, aluminum phosphate Aluminum compounds such as hydrates are preferred.

  The mass ratio of the porous inorganic fine particles and the metal compound-based anticorrosive pigment upon complexing is preferably 95: 5 to 50:50. If the rust preventive pigment is less than 5% by mass, it may be difficult to obtain sufficient end face corrosion resistance and its durability. In addition, due to the structure of the porous inorganic fine particles, it may be difficult to make the antirust pigment more than 50% by mass.

  The sustained-release rust preventive fine particles can be obtained by mechanically mixing a metal compound-based rust preventive pigment having a smaller diameter than that of the porous inorganic fine particles (if crushed if necessary) together with the porous inorganic fine particles. It is preferable to mix with a high shearing force. During this mixing, it is considered that the rust preventive pigment enters the pores of the porous inorganic fine particles, and both are combined. During mixing, heating and pressurization may be performed as appropriate. In the present invention, since a metal compound type anticorrosive pigment having a low solubility in water and a low elution rate is used, it is difficult to immerse the porous inorganic fine particles in an aqueous solution of the anticorrosive pigment to form a composite. If the rust preventive pigment is made into a solution by adjusting the pH or using another solvent, both can be combined by immersing the porous fine particles in this solution and then drying.

  When the sustained-release rust-preventing fine particles are contained in an amount of 5 to 40 parts by mass with respect to 100 parts by mass of the coating film component, good end face corrosion resistance and its sustainability can be obtained. That is, among the solid content of the coating film forming composition, 5 to 40 parts by mass of the sustained release rust preventive fine particles are added to 100 parts by mass of the solid content other than the sustained release rust preventive fine particles to form a coating film do it. The sustained-release rust-preventing fine particles may be contained in one or both of the undercoat film and the topcoat film. From the viewpoint of corrosion resistance, it is preferable to be contained in both coating films.

  In order to produce the resin-coated metal plate of the present invention, it is preferable to employ a method of preparing a coating film forming composition and applying and drying the composition to a metal plate. The coating film-forming composition is prepared by diluting a base organic resin, sustained-release rust-preventing fine particles, and a crosslinking agent added as necessary with an organic solvent or the like to a viscosity suitable for coating. The organic solvent is not particularly limited, but aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate; alicyclic hydrocarbons such as cyclohexane; aliphatic carbonization such as hexane and pentane. Hydrogen etc .; Ketones such as methyl ethyl ketone and cyclohexanone are listed. In consideration of coating suitability, the raw material composition has a viscosity of Ford Cup No. 4 is adjusted to be about 30 to 100 seconds, or it is recommended to adjust the solid content concentration to about 5 to 45% by mass.

  You may add a well-known antirust pigment to the said composition for coating-film formation further. Various known additives used in the field of resin-coated metal plates, such as matting agents, extender pigments, anti-settling agents, and waxes, may also be added.

  The method for applying the coating film forming composition to the metal plate is not particularly limited, and a bar coater method, a roll coater method, a spray method, a curtain flow coater method, and the like can be employed. Although drying is performed after coating, in a crosslinking agent addition system, it is preferable to perform drying by heating at a temperature at which the crosslinking agent can react. Specifically, heat drying is preferably performed at 100 to 250 ° C. for about 1 to 5 minutes.

  The thicknesses of the undercoat film and the topcoat film are not particularly limited, but both are preferably about 1 to 100 μm, and more preferably about 5 to 30 μm.

  The present invention will be described in more detail with reference to the following examples. However, the following examples are not intended to limit the present invention, and modifications within the scope of the present invention are included in the present invention. Unless otherwise specified, “%” indicates “mass%” and “part” indicates “part by mass”. The evaluation methods used in the examples are as follows.

[Cross-cut corrosion resistance]
Put a cross cut (60 °, 60 mm) with a cutter knife in the test material (50 mm x 120 mm), conduct a salt spray test in accordance with JIS Z2371, and determine the swollen width of the coating film from the cross cut part after 500 hours. It was measured. The evaluation criteria were as follows.
◎: Swelling width is 1 mm or less ○: Swelling width is more than 1 mm, 3 mm or less △: Swelling width is more than 3 mm, 5 mm or less ×: Swelling width is more than 5 mm

(End surface corrosion resistance)
A salt spray test was performed according to JIS Z2371, and the swollen width of the coating film from the end face portion after 500 hours was measured. The evaluation criteria were as follows.
◎: Swelling width is 1 mm or less ○: Swelling width is more than 1 mm, 3 mm or less △: Swelling width is more than 3 mm, 5 mm or less ×: Swelling width is more than 5 mm

(Artificial rainwater dripping test)
The test material was cut into 50 mm × 120 mm, and one end in the longitudinal direction was bent into a bowl shape so that the cross section was a semicircle as shown in FIG. Both ends of the buttocks were sealed. A circular (φ = 6 mm) cut was made in the center of the collar, and the end face of the periphery of this semicircle was exposed. Artificial rainwater was added dropwise from above the test material at 0.16 to 0.17 ml / min. The composition of artificial rainwater is as shown in Table 1, and the pH was adjusted to 4.7 with sulfuric acid. This is in accordance with the average ionic composition of domestic rainfall surveyed by the Environment Agency. The test atmosphere was 40 ° C. and 95% RH. A gauze was placed at the bottom of the test apparatus, and the red rust generation state at the semicircular cut and the red rust flow-down state on the gauze were visually confirmed every 24 hours. If red rust was generated at the time of this confirmation, the time was defined as the red rust generation time.

[Machinability A]
The test material was cut into 50 mm × 50 mm, bent with the surface to be evaluated outside, bent at 180 ° (0T bending) in a vise under a low temperature (0 ° C.) atmosphere, and then formed on the coating film at the bent portion. The state of occurrence of cracks was observed visually and with a magnifying glass (magnification 10 times). The evaluation criteria were as follows.
◎: No cracking (no cracks observed visually or with a loupe)
○: Little occurrence of cracks (not visually recognized, but a slight crack can be confirmed by observing with a magnifying glass)
Δ: Crack generation (small cracks are visually recognized)
X: Large crack (a large crack is visually recognized)

[Workability B]
The crack generation state of the bent portion was observed in the same manner as the workability A, except that it was performed in a normal temperature (20 ° C.) atmosphere instead of a low temperature (0 ° C.) atmosphere. The evaluation criteria are the same.

[Elution rate measurement test]
The test material was cut into a circular shape with a diameter of 50 mm, and 100 grids of 1 mm × 1 mm were cut with a cutter knife. It was immersed in 100 ml of a carbonate pH standard solution (pH = 10.01, sodium hydrogen carbonate + sodium carbonate aqueous solution) in an atmosphere of 40 ° C. and 95% RH. 10 ml of this aqueous solution was sampled every 24 hours, and the amount of ions eluted from the grid notch and the end face was quantitatively analyzed by ICP emission spectrometry to measure the elution rate of the rust preventive component.

[Manufacture of sustained-release antirust fine particles A]
Hollow porous silica fine particles (“Godball (registered trademark) B-6C”: manufactured by Suzuki Yushi Kogyo Co., Ltd .: average particle diameter of about 2.0 μm (2 to 2.5 μm)) and magnesium oxide (“Starmag L- 10 "high active product: manufactured by Kamishima Chemical Industry Co., Ltd .: average particle size 0.63 μm) was mixed with 50 parts to produce sustained-release rust preventive fine particles A. The magnesium oxide was previously pulverized and then mixed with the hollow porous silica fine particles. During mixing, the mixture was mixed with high shearing force while heating.

[Manufacture of sustained release antirust fine particles B]
Similar to the sustained-release rust preventive fine particles A, except that aluminum tripolyphosphate (“K-WAHITE # G105”: average particle size 2.3 μm: manufactured by Teica) was used instead of magnesium oxide. Rust-proof fine particles B were produced.

[Manufacture of sustained release rust preventive fine particles C]
Sustained release rust preventive fine particles C were produced in the same manner as the sustained release rust preventive fine particles A except that magnesium carbonate (industrial (light): manufactured by Kyowa Chemical Industry Co., Ltd.) was used instead of magnesium oxide.

[Manufacture of sustained release rust preventive fine particles D]
Controlled release rust preventive rust in the same manner as controlled release rust preventive fine particles A, except that magnesium hydroxide (“10A”: manufactured by Kamishima Chemical Industry Co., Ltd .: average particle size 3.5 μm) was used instead of magnesium oxide. Fine particles D were produced.

[Manufacture of sustained-release antirust fine particles E]
Sustained release rust preventive fine particles E were produced in the same manner as the sustained release rust preventive fine particles A except that magnesium phosphate (manufactured by Gokoku Dye Co., Ltd.) was used instead of magnesium oxide.

[Manufacture of sustained release antirust fine particles F]
Sustained release rust preventive fine particles F were produced in the same manner as the sustained release rust preventive fine particles A except that calcium vanadate (manufactured by Shinsei Chemical Industry Co., Ltd.) was used instead of magnesium oxide.

Experiment No. 1 (Elution rate of rust preventive component)
Each of the above-mentioned sustained-release rust-preventing fine particles A to F is added to a NaOH aqueous solution adjusted to 40 ° C. and pH 10 so as to be 2%, stirred, and an aqueous solution every 24 hours from 24 hours to 120 hours. The amount of ions dissolved therein was quantitatively analyzed by ICP emission spectrometry, and the elution rate of the anticorrosive component from the fine particles was measured. The results are shown in Table 2.

Experiment No. 2 (Effect of dissolution rate)
As the metal plate, a hot dip galvanized steel plate having a plate thickness of 0.8 mm and a plating adhesion amount of 45 g / m ^{2 on} one side was used. “CTE220” manufactured by Nihon Parkerizing Co., Ltd., which is a non-chromate base treatment agent, was applied to the front and back surfaces of this plated steel sheet so that the adhesion amount was 100 mg / m ² . The baking conditions were an ultimate plate temperature of 100 ° C., a heating time of 12 seconds, and a wind speed during baking of 5 m / second.

Base resin ("Byron (registered trademark) 300": 57 parts of organic solvent-soluble polyester resin manufactured by Toyobo Co., Ltd .: Tg 7 ° C .: molecular weight (Mn) 23 × 10 ³ ), and melamine resin (“Cymel ( (Registered trademark) 325 ": made by Cytec Co., Ltd.) 25 parts, epoxy resin (" jER (registered trademark) 1001 "(produced by Japan Epoxy Resin Co., Ltd.), 3 parts, titanium dioxide (" JR-603 ": Teika Corporation) Product: 14.5 parts of average particle size 0.28 μm) and 0.5 part of silica-based clay (“Clay No. 1” manufactured by Maruo Calcium Co., Ltd.) were mixed well. 20 parts of the sustained release rust preventive fine particles shown in Tables 3 and 4 were blended to prepare a resin composition for an undercoat coating film.

  The undercoat film resin composition was bar-coated on one side of the metal plate after the base treatment so that the thickness after drying was 10 μm. The baking conditions were an ultimate plate temperature of 210 ° C., a drying time of 50 seconds, and a baking wind speed of 5 m / second.

  15 parts of titanium dioxide ("JR-603": manufactured by Teika Co., Ltd .: average particle size 0.28 μm) per 100 parts (solid content) of polyester / melamine paint ("FLC5000": manufactured by Nihon Fine Coatings), silica 50 parts of clay (“Clay No. 1” manufactured by Maruo Calcium Co., Ltd.) and 20 parts of sustained-release rust preventive fine particles shown in Tables 3 and 4 were added to prepare a resin composition for a top coat film.

  Bar coating was performed on both surfaces of the plate after the formation of the undercoat coating film so that the thickness after drying of the resin composition for an overcoating film was 17 μm. The baking conditions were an ultimate plate temperature of 210 ° C., a drying time of 50 seconds, and a wind speed during baking of 5 m / second. Table 3 shows the evaluation results of the surface on which the undercoat film and the topcoat film were formed.

  In addition, the resin coating metal plate which apply | coated the resin composition for top coat films on both surfaces of the metal plate after base treatment without forming an undercoat coating film was also manufactured similarly to the above. The evaluation results are shown in Table 4.

Experiment No. 3 (Effect of average particle size of sustained-release antirust fine particles)
When the sustained-release rust-preventing fine particles A were produced, by changing the average particle size of the hollow porous silica fine particles, sustained-release rust-proof fine particles having an average particle size of 0.5 to 20 μm were produced. Each sustained-release rust-preventing fine particle was subjected to Experiment No. In the same manner as in No. 2, 20 parts of the resin composition for the undercoat film and the resin composition for the topcoat film were blended to produce a resin-coated metal plate on which the undercoat film and the topcoat film were formed. The evaluation results are shown in Table 5. In addition, the comparative example 3 changed to using 20 parts of sustained-release antirust fine particles, and magnesium oxide which is not compounded with the hollow porous silica fine particles ("Starmag L-10": manufactured by Kamishima Chemical Co., Ltd.) Is an example using 10 parts.

Experiment No. 4 (Effect of added amount of sustained-release antirust fine particles)
Except for changing the addition amount of the sustained-release rust-preventing fine particles A as shown in Tables 6 and 7, Experiment No. In the same manner as in Example 2, a resin-coated metal plate (Table 6) on which an undercoat film and a topcoat film were formed, and a resin-coated metal plate (Table 7) on which only a topcoat film was formed were produced. The evaluation results are shown in Tables 6 and 7.

Experiment No. 5 (Influence of the type of sustained-release anticorrosive fine particles)
Except for changing the kind of sustained-release rust-preventing fine particles as shown in Tables 8 and 9, the experiment No. In the same manner as in Example 2, a resin-coated metal plate (Table 8) on which an undercoat film and a topcoat film were formed, and a resin-coated metal plate (Table 9) on which only a topcoat film was formed were produced. The evaluation results are shown in Tables 8 and 9.

Experiment No. 6 (Influence of the type of sustained-release anticorrosive fine particles)
Except for changing the kind of sustained-release rust-preventing fine particles as shown in Tables 10 and 11, Experiment No. In the same manner as in No. 2, a resin-coated metal plate (Table 10) on which an undercoat film and a topcoat film were formed and a resin-coated metal plate (Table 11) on which only an upper coat film was formed were produced. The evaluation results are shown in Tables 10 and 11.

Experiment No. 7 (Influence of non-sustained-release antirust pigment)
Experiment No. In addition to the 100 parts of the resin composition for the undercoat coating film prepared in 2, an amount of magnesium oxide ("Starmag L-10" manufactured by Kamishima Chemical Industry Co., Ltd.) in the amount shown in Table 12 was additionally added as a rust preventive pigment. Except for Experiment No. In the same manner as in Example 2, a resin-coated metal plate on which an undercoat film and an overcoat film were formed was produced. Therefore, the elution amount of magnesium oxide additionally added is added to the elution ion amount in the measurement of the elution rate in Table 12. The evaluation results are shown in Table 12.

It is explanatory drawing of the measuring method of an artificial rainwater dropping test.

Claims (6)

A non-chromium resin-coated metal plate in which an undercoat film and / or a topcoat film is formed on a non-chromium base treatment film,
This undercoat and / or topcoat is formed from sustained release rust-preventing fine particles having an average particle size of 1 to 10 μm , which is a composite of porous inorganic fine particles and metal compound-based rust preventive pigments. Containing 5 to 40 parts by mass with respect to 100 parts by mass of coating film components other than rust fine particles,
When 100 squares of 1 mm × 1 mm are cut on a resin-coated metal plate and then immersed in a 40 ° C. carbonate pH standard solution, the elution rate of metal ions eluted from the rust preventive pigment is 0.001 to 1. A non-chromium resin-coated metal plate having excellent end surface corrosion resistance, characterized by 0.0 mg / l · m ² · hr. 2. The non-removal according to claim 1, wherein the elution rate of metal ions when the sustained-release rust-preventing fine particles are immersed in an aqueous sodium hydroxide solution having a pH of 10 at 40 ° C. is 0.005 to 0.5 mg / l · g · hr. Chrome resin coated metal plate. Rust preventive pigment compounded with sustained release rust preventive fine particles is selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium phosphate, magnesium carbonate, magnesium chloride, magnesium oxalate, magnesium sulfate and hydrates thereof chromium-resin coated metal sheet according to claim 1 or 2 is one or more magnesium compounds. 2. The rust preventive pigment compounded with sustained release rust preventive fine particles is one or more aluminum compounds selected from the group consisting of aluminum tripolyphosphate, aluminum phosphate and aluminum phosphate dihydrate. Or a non-chromium resin-coated metal plate according to 2; The non-chromium resin-coated metal plate according to any one of claims 1 to 4 , wherein the porous inorganic fine particles used for the sustained-release anticorrosive fine particles are porous silica fine particles. The non-chromium resin-coated metal sheet according to any one of claims 1 to 5 , wherein the undercoat film and / or the topcoat film further contains a rust preventive pigment.