Metal surface treatment composition and metal plate using the same

The present invention relates to a metal surface treatment composition capable of obtaining a film having excellent processability, corrosion resistance, lubricity, topcoat coating property, etc. without a conventional chrome treatment step, and the surface treatment composition. The present invention relates to a surface-treated metal plate obtained by using the above, which is particularly useful in the fields of home appliances, automobiles, and the like.

In recent years, steel sheets having excellent lubricity, which can omit press oil coating, have been developed and used in fields such as automobiles, home appliances, and building materials. These lubricating steel sheets are required to have excellent corrosion resistance, and usually a film having lubricity is formed on the chromate-treated steel sheet (see, for example, Patent Document 1 and the like).

However, in recent years, the toxicity of chromium has become a social problem. Surface treatment methods that use chromate include problems with scattering of chromate fumes in the treatment process, high costs for wastewater treatment equipment, and problems due to elution of chromic acid from the chemical conversion coating. There is. Hexavalent chromium compounds are extremely harmful substances, which are designated as carcinogens for the human body by many public institutions including the IARC (International Agency for Research on Cancer Review).

In addition, it has been pointed out that it would be too costly to apply a treatment agent for forming a lubricating film after chromate treatment, and it does not contain harmful chromium and has both corrosion resistance and lubricity1. There is an increasing demand for surface-treated steel sheets consisting of layer coatings.

In order to meet such demands, a composition capable of forming a lubricating film containing a water-soluble resin and / or a water-dispersible resin, a lubricating function imparting agent, silica particles and a vanadium compound has been developed and disclosed ( See Patent Document 2.).

However, in the above system, it is difficult to adapt to a part where severe performance is required in terms of corrosion resistance and the like.

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 9-99517</text></patcit>

<patcit num="2"><text>Japanese Unexamined Patent Publication No. 2003-183587</text></patcit>

<p> An object of the present invention is to provide a metal surface treatment composition which does not contain harmful chromium and can form a surface treatment metal plate having excellent corrosion resistance and lubricity with a single layer coating.</p>

<p> As a result of diligent studies to solve the above problems, the present inventors have used a polyurethane resin as a water-soluble or water-dispersible organic resin, and used it as a silica particle, a silane coupling agent, a vanadic acid compound, or a specific one. We have found that a metal surface treatment composition capable of forming a film having lubricity and corrosion resistance comparable to chromate treatment can be obtained by combining a fluoride compound and a lubricating function imparting agent, and the present invention has been made. It came to be completed.</p><p> Thus, the present invention relates to (A) 10 to 40 parts by weight of silica particles and 0.3 to 25 parts by weight of a silane coupling agent with respect to 100 parts by weight of the solid content of the water-soluble or water-dispersible polyurethane resin. (D) 0.3 to 30 parts by weight of vanadic acid compound, (E) 1 to 20 parts by weight of at least one hydrofluoric acid compound selected from metal hydrofluoric acid and metal hydrofluoric acid salt, and (F) imparting lubrication function. The present invention relates to a metal surface treatment composition comprising 0.5 to 30 parts by weight of an agent.</p><p> The present invention also relates to a metal plate having excellent lubricity, which is formed by applying the above metal surface treatment composition to a steel sheet to form a film.</p>

<p> In the metal surface treatment composition of the present invention, the flexibility of the coating is ensured by using a urethane resin as the organic resin for forming the continuous layer of the coating obtained from the composition, and the urethane resin, the silica particles and the silane coupling agent are used. By combining it, it is possible to obtain strong adhesion to the material metal, and by combining it with a vanadic acid compound and a specific fluoride compound, corrosion resistance can be significantly improved, and further lubrication. By combining the function-imparting agents, excellent lubricity and corrosion resistance comparable to chromate treatment have been obtained, which is particularly useful in the fields of home appliances, automobiles and the like.</p>

The metal surface treatment composition of the present invention comprises a water-soluble or water-dispersible polyurethane resin (A), silica particles (B), a silane coupling agent (C), a vanadic acid compound (D), a metal hydrofluoric acid and a metal. It contains at least one hydrofluoric acid compound (E) selected from hydrofluoric acid salts and a lubricating function imparting agent (F).

<u style="single">Water-soluble or water-dispersible polyurethane resin (A)</u> The water-soluble or water-dispersible polyurethane resin which is the component (A) of the metal surface treatment composition of the present invention is a polyurethane composed of a polyol such as a polyester polyol or a polyether polyol and a diisocyanate, and if necessary, a diol, a diamine or the like. The chain is extended in the presence of a chain extender, which is a low molecular weight compound having two or more active hydrogens, and is stably dispersed or dissolved in water, and known compounds can be widely used.

As a method for stably dispersing or dissolving the polyurethane resin in water, for example, the following method can be used. (1) A method of imparting hydrophilicity by introducing an ionic group such as a hydroxyl group, an amino group, or a carboquil group into the side chain or terminal of a polyurethane polymer, and dispersing or dissolving it in water by self-emulsification; (2) Reaction A method in which a complete polymer or terminal isocyanate group is forcibly dispersed in water using a blocking agent such as oxime, alcohol, phenol, mercaptan, amine, sodium bisulfite, etc. using an emulsifier and mechanical shearing force; (3) A method in which a urethane prepolymer having a terminal isocyanate group is mixed with water, an emulsifier and an extender to simultaneously disperse and polymerize using a mechanical shearing force; (4) As a polyol as a main raw material for polyurethane. A method in which a water-soluble polyol such as polyethylene glycol is used and dispersed or dissolved in water as a water-soluble polyurethane.

Commercially available products of the above polyurethane resin include, for example, Hydran HW-330, HW-340, HW-350 (all manufactured by Dainippon Ink and Chemicals), Superflex 100, 110, 150, and F-8438D. , 420 (all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Adeka Bontider HUX-232, 260, 320, 350 (all manufactured by Asahi Denka Co., Ltd.).

The water-soluble or water-dispersible polyurethane resin (A) may include other water-soluble or water-dispersible organic resins as required, such as water-soluble or water-dispersible acrylic resins, ethylene and polymerizable unsaturated carboxylics. A copolymer with an acid, and an emulsion polymerization resin, an epoxy resin, an epoxy ester resin, a phenol resin, or the like using this polymer can also be used in combination.

When a water-soluble or water-dispersible organic resin other than the polyurethane resin is used in combination, the other water-soluble or water-dispersible organic resin is a solid of the water-soluble or water-dispersible polyurethane resin (A). The solid content of 100 parts by weight or less, particularly about 5 to 50 parts by weight, is preferable from the viewpoint of workability of the coating film with respect to 100 parts by weight.

<u style="single">Silica particles (B)</u> The silica particles which are the component (B) in the metal surface treatment composition of the present invention contribute to the improvement of adhesion and corrosion resistance, and have an average particle size of 1 to 100 nm, particularly 2 to 30 nm, and further particularly 3 to 10 nm. The silica particles of the above are preferable, and any silica particles such as vapor phase silica, pulverized silica, and water-dispersible colloidal silica may be used. Examples of commercially available products of water-dispersible colloidal silica include Snowtex N, Snowtex C, and Snowtex O (all manufactured by Nissan Chemical Industries, Ltd.), and commercially available products of other silica particles include. For example, AEROSIL200V, R-811 (manufactured by Nippon Aerosil Co., Ltd.) and the like can be mentioned. Further, silica particles having an average particle size of 1 to 100 nm may be used in combination with silica particles having a particle size of more than 100 nm, particularly a large particle size of more than 200 nm.

The amount of the silica particles (B) added is 10 to 40 parts by weight, preferably 15 to 35 parts by weight, based on 100 parts by weight of the solid content of the water-soluble or water-dispersible polyurethane resin (A). It is suitable in terms of film formation and storability.

<u style="single">Silane coupling agent (C)</u> The silane coupling agent which is the component (C) in the metal surface treatment composition of the present invention is blended in order to improve the adhesion between the steel plate and the coating film, and is, for example, γ- (2-aminoethyl) amino. Amino group-containing silane couplings such as propyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane Agents; glycidyl group-containing silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldimethoxysilane; mercapto group-containing silane coupling agents such as γ-mercaptopropyltrimethoxysilane. Be done.

The amount of the silane coupling agent (C) added is 0.3 to 25 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the solid content of the water-soluble or water-dispersible polyurethane resin (A). It is suitable in terms of effects.

<u style="single">Vanadate compound (D)</u> By blending the vanadate compound in the system of the polyurethane resin (A), vanadate ions can passivate the metal surface, suppress elution of the object to be coated, and improve corrosion resistance.

Examples of the vanadate compound include ammonium vanadate, sodium vanadate, potassium vanadate, vanadate anhydride and the like, and it is particularly preferable to use ammonium vanadate from the viewpoint of corrosion resistance.

Corrosion resistance is in the range of 0.3 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the solid content of the water-soluble or water-dispersible polyurethane resin (A). Suitable for.

<u style="single">Compound (E)</u> The compound (E) component in the metal surface treatment composition of the present invention is at least one compound selected from metal hydrofluoric acid and metal hydrofluoric acid salt.

As the above-mentioned preferable metal hydrofluoric acid, for example, zirconium hydrofluoric acid, titanium hydrofluoric acid and the like can be mentioned. Examples of those forming a salt of metal hydrofluoric acid include sodium, potassium, lithium, ammonium and the like. Among them, potassium, sodium and ammonium are preferable, and specific examples thereof include potassium zirconium fluoride and zirconium fluoride. Ammonium, potassium titanium fluoride and the like can be mentioned.

The compounding amount of the compound (E) is preferably in the range of 1 to 20 parts by weight, particularly preferably in the range of 3 to 15 parts by weight, based on 100 parts by weight of the solid content of the water-soluble or water-dispersible polyurethane resin (A).

<u style="single">Lubrication function imparting agent (F)</u> The lubricating function-imparting agent which is the component (F) in the composition of the present invention may be any as long as it imparts lubricity to the obtained film. Specifically, for example, fluororesin fine powder (for example, ethylene tetrafluoride resin, ethylene tetrafluoride-propylene hexafluoride copolymer resin, ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer resin, ethylene tetrafluoride- Fine powder of ethylene copolymer resin, ethylene trifluoride chloride resin, vinylidene fluoride resin, etc.), polyolefin wax (for example, polyethylene wax, polypropylene wax, etc.), polyolefin and fluororesin are mixed and contained in one particle. Examples thereof include fluoropolymers, graphite, boron nitride, carbon fluoride and the like.

The average particle size of the lubricating function imparting agent (F) is preferably in the range of 0.3 to 5.0 μm, more preferably 0.5 to 3.0 μm. When the average particle size of the wax becomes smaller, the effect of improving lubricity tends to decrease, and when the average particle size becomes too large, the number of protrusions from the wax film increases, and the wax peels off in continuous processing, resulting in gold. There is a problem that it easily adheres to the mold.

Further, in continuous high-speed machining accompanied by heat generation, the surface temperature rises due to frictional heat, so that the low melting point lubricating function imparting agent becomes liquid, and is not fixed to the lubricating film but adheres to and accumulates on the mold to form a metal surface. It is not preferable because it will hurt. For high-speed machining with heat generation, it is suitable to use polyolefin wax with a softening point of 100 ° C or higher, preferably 130 to 150 ° C. Even at high temperatures, the wax is uniformly fixed to the film and damages the surface of the galvanized steel sheet. It is possible to effectively exert the lubrication function. The lubricating function imparting agent (F) can be used by mixing two or more kinds of waxes from the viewpoints of coating workability, lubricity, etc. For example, the one in which the polyolefin wax and the fluororesin powder are used in combination is used. It is mentioned as a preferable one.

The amount of the lubricating function imparting agent (F) added should be in the range of 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the solid content of the water-soluble or water-dispersible polyurethane resin (A). Is suitable. If the amount added is too small, the effect of improving lubricity is small, and if it is too large, the gloss value and transparency of the film are lowered and the surface smoothness is lost, and the elongation rate and adhesive force of the film are sharply lowered. Not only is the film easily peeled off and the lubricity function cannot be sufficiently exhibited and the press workability is lowered, but also the adhesiveness of the topcoat coating film is lowered when the topcoat coating is applied on the coating film.

Further, if necessary, the metal surface treatment composition of the present invention, in addition to the above-mentioned components, for example, a thickener, an anti-repellent agent, an antifoaming agent, a surfactant, an oxidizing agent, an antibacterial agent, and an anticorrosive agent. It can contain agents (tannic acid, phytic acid, benzotriazole, etc.), coloring pigments, extender pigments, rust preventive pigments, conductive pigments, and the like.

Further, in the metal surface treatment composition of the present invention, if necessary, for example, a hydrophilic solvent such as metanol, ethanol, isopropyl alcohol, ethylene glycol-based, propylene glycol-based, etc. is used. It may be added.

<u style="single">Manufacture of metal plates with excellent lubricity</u> The metal surface treatment composition of the present invention can omit the conventional chromate treatment step and is directly applied to an untreated cold-rolled steel sheet or aluminum plate, or a plated steel sheet such as an untreated zinc-based plated steel sheet or aluminum-plated steel sheet. By drying, a metal plate having excellent corrosion resistance and lubricity can be obtained. Even if the composition of the present invention is coated on a chromate-treated steel sheet, there is no problem in performance, and a metal plate having more excellent corrosion resistance can be obtained, so that it can be used as needed.

Examples of the zinc-based plated steel sheet include an electrogalvanized steel sheet, a hot-dip galvanized steel sheet, a nickel-zinc alloy plated steel sheet, and a zinc-aluminum alloy plated steel sheet. Zinc-aluminum plated steel sheets include 5% Al-Zn series, 8% Al-Zn series, 15% Al-Zn series, etc. in the case of zinc base, and 55% Al-Zn series, 75 in the case of aluminum base. Although% Al-Zn type and the like are known, the composition of the present invention is applicable not only to these but also to composite plated steel sheets having aluminum and zinc as main components in the plating layer. For example, an Al-Zn alloy to which Mg, Mn, Si, Ti, Ni, Co, Pb, Sn, Cr and rare metals (La, Ce, Y, Nb, etc.) are added can also be applied.

The composition of the present invention is used by being applied to the steel sheet, and the amount of the composition applied is 0.3 to 6.0 g / m in terms of dry film weight.², More preferably 0.5 ~ 4.0 g / m²Degree is desirable. When the film becomes thin, the corrosion resistance, black discoloration resistance and lubricity decrease, and when the film becomes thick, the corrosion resistance improves but the press workability decreases, and the cost increases.

Further, when it is desired to impart welding suitability to the steel sheet coated with the composition of the present invention, the weight of the dry film is 1.5 g / m.²Below, especially 0.05 ~ 1.0g / m²It is desirable to make it a degree. If the amount of coating is large, dust is likely to be generated during spot welding, and the welding strength is insufficient, so that the appropriateness of continuous spot welding is lowered.

When the composition of the present invention is applied to a steel sheet to form a film, the viscosity of the composition is appropriately adjusted to about 5 to 30 cmpoise according to the coating amount with a diluent such as water, and then roll coater coating, spray coating, and depping are performed. After painting to a predetermined film weight by a generally known method such as painting, the mixture is dried at an atmospheric temperature of 150 to 250 ° C. for 10 to 40 seconds. The maximum temperature (PMT) of the steel sheet at this time is preferably in the range of 90 to 160 ° C. By coating and drying the film composition in this way, a steel sheet having excellent corrosion resistance, press workability, and the like is produced.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the following, "parts" and "%" are both based on weight.

<u style="single">Manufacture of metal surface treatment compositions</u> Examples 1 to 31 and Comparative Examples 1 to 11 Each metal surface treatment composition was produced according to the formulation shown in Table 1 below. The formulations in Table 1 are shown by solid content weight. Further, each metal surface treatment composition was adjusted to a solid content of 20% with deionized water.

<tables num="1"><img file="JP2005298837A_D0001.tif" /></tables>

<tables num="2"><img file="JP2005298837A_D0002.tif" /></tables>

The raw materials of (Note 1) to (Note 13) in Table 1 above are as follows. (Note 1) ADEKA Bontider HUX320: Product name, manufactured by Asahi Denka Kogyo Co., Ltd., aromatic polyester polyurethane emulsion, solid content 30%. (Note 2) Superflex 150: Product name, manufactured by Asahi Denka Kogyo Co., Ltd., polyurethane emulsion, solid content 30%. (Note 3) Aqua Brid 4635: Product name, manufactured by Daicel Chemical Industries, Ltd., anionic acrylic emulsion, Tg 60 ° C, solid content 35%. (Note 4) Chemipearl S-100: Product name, manufactured by Mitsui Chemicals, ethylene acrylic copolymer resin dispersion, pH 12, solid content 27%. (Note 5) Adelite AT-20S: Product name, manufactured by Asahi Denka Kogyo Co., Ltd., colloidal silica, average particle size 7 to 10 nm, SiO₂Content 20%. (Note 6) Snowtex C: Product name, manufactured by Nissan Chemical Industries, Ltd., colloidal silica, average particle size 10 to 20 nm, SiO₂Content 20%. (Note 7) Adelite AT-2045: Product name, manufactured by Asahi Denka Kogyo Co., Ltd., colloidal silica, average particle size of 5 nm or less, SiO₂Content 20%. (Note 8) AEROSIL 200V: Product name, manufactured by Nippon Aerosil Co., Ltd., fumed silica, average particle size 12 nm. (Note 9) KBM-603: Trade name, manufactured by Shin-Etsu Chemical Co., Ltd., N-β (aminoethyl) γ-aminopropyltrimethoxysilane. (Note 10) KBM-803: Trade name, manufactured by Shin-Etsu Chemical Co., Ltd., γ-mercaptopropyltrimethoxysilane. (Note 11) Chemipearl W-700: Brand name, manufactured by Mitsui Chemicals, Inc., high-density polyethylene wax, molecular weight 4,000, softening point 132 ° C, average particle size 1.1 μm. (Note 12) SLIP AID SL-92: Product name, manufactured by San Nopco, polyethylene wax, softening point 92 ° C, average particle size 2 μm. (Note 13) PTFE: Polytetrafluoroethylene resin powder, average particle size 2 to 5 μm.

<u style="single">Preparation of test coating plate and evaluation of coating film performance</u> Examples 28 to 58 and Comparative Examples 12 to 22 Using the metal surface treatment compositions of Examples 1 to 27 and Comparative Examples 1 to 11 obtained above as various materials using a bar coater, the dry film weight is 1.2 g / m²Each test coated plate was prepared by painting and drying at an ambient temperature of 240 ° C for 10 seconds (the maximum temperature reached by the steel sheet [PMT] was 110 ° C). The combination of each metal surface treatment composition and coating material was carried out according to Table 2 below.

Various performance tests were performed on each of the obtained test coated plates. The results obtained are shown in Table 2 below.

The material symbols and test methods in Table 2 are shown below.

<u style="single">Material symbol and content</u>A: Hot-dip galvanized steel sheet; plate thickness 0.6 mm, plating adhesion 100 g / m²B: Zinc-aluminum alloy plated steel plate; Zinc / aluminum = 95/5 (weight ratio), trade name Super Zinc, plate thickness 0.5 mm, plating adhesion 140 g / m²C: Zinc-aluminum alloy plated steel plate; Zinc / aluminum = 45/55 (weight ratio), trade name Galvalume, plate thickness 0.5 mm, plating adhesion amount 90 g / m²D: Electrogalvanized steel sheet; Brand name Gincoat, plate thickness 0.6mm, plating adhesion 20g / m²E: Ni-Zn plated steel plate; Zinc / nickel = 88/12 (weight ratio), plate thickness 0.6 mm Plating adhesion 20 g / m² As shown in Table 2, the test plates were prepared with and without chrome treatment, but for the test plates with chrome treatment, Cosmah 150 (manufactured by Kansai Paint Co., Ltd., coating type chromate) was converted to metal chrome. At 5 mg / m²The coated one was used, and the degreased material was used as it was for the test plate without chrome treatment.

<u style="single">Test method</u> Film appearance: For each test plate, the film appearance was visually evaluated according to the following criteria. : The film is transparent. : The film is slightly white and cloudy. Δ: The film is considerably cloudy or is considerably colored. ×: Does not form a clean continuous film.

Deep drawing workability: For each test plate, a deep drawing test was conducted under the following conditions using a metal thin plate deep drawing tester 142 type manufactured by Eriksen. Test temperature 20 ° C and 80 ° C Seat holder pressure 1500Kg Punch diameter 50mm Blank diameter 110mm Aperture ratio 2.2 Processing speed 10mm / sec The processed test plate was visually evaluated according to the following criteria. : There is no deposit on the die, and no scratches are found on the surface of the work piece. : There is a small amount of deposits on the die, and slight scratches are observed on the surface of the work piece. Δ: There are a few deposits on the die, and many scratches are observed on the surface of the work piece. X: There is a large amount of deposits on the die, and scratches are observed on the entire surface of the work piece.

Corrosion resistance: A salt spray test was conducted in accordance with JIS Z-2371. The test time was 360 hours for the flat plate before processing and 240 hours for the sample obtained in the deep drawing workability test, and the evaluation was made according to the following criteria based on the degree of occurrence of white rust or black rust. : No rust was observed. : Rust is observed in an area of less than 5%. Δ: Rust is observed in an area of 5% or more and less than 20%. ×: Rust is observed in an area of 20% or more.

Boiling water resistance: After immersing the test piece in boiling water for 1 hour, measure the color difference (ΔE) of the coated plate before and after the test using the color difference meter "SM Color Computer MODEL SM-5" (manufactured by Suga Test Instruments Co., Ltd.). It was evaluated according to the following criteria. : ΔE is less than 2. : ΔE is 2 or more and less than 5. Δ: ΔE is 5 or more and less than 10. ×: ΔE is 10 or more.

High temperature and humidity resistance: After leaving the test piece in an environment of temperature 80 ° C and humidity 95% for 48 hours, before and after the test using the color difference meter "SM Color Computer MODEL SM-5" (manufactured by Suga Test Instruments Co., Ltd.) The color difference (ΔE) of the coated plate was measured and evaluated according to the following criteria. : ΔE is less than 2. : ΔE is 2 or more and less than 5. Δ: ΔE is 5 or more and less than 10. ×: ΔE is 10 or more.

Alkali resistance: Immerse the test plate in a 5% aqueous sodium hydroxide solution for 2 minutes, wash it with water, dry it, and use the color difference meter "SM Color Computer MODEL SM-5" (manufactured by Suga Test Instruments Co., Ltd.) to remove the coated plate before and after the test. The color difference (ΔE) was measured and evaluated according to the following criteria. : ΔE is less than 2. : ΔE is 2 or more and less than 5. Δ: ΔE is 5 or more and less than 10. ×: ΔE is 10 or more.

Topcoat adhesion: Thermosetting alkyd paint Amylac # 1000 and thermosetting acrylic paint Magiclon # 1000 (both manufactured by Kansai Paint Co., Ltd., color is white) are applied on the test piece with a film thickness of 25 μm. Acrylic # 1000 is baked at 130 ° C for 20 minutes, and Magiclon # 1000 is baked at 150 ° C for 20 minutes to make two types of coating boards. , Make 100 1mm x 1mm goban eyes on the paint film with a sharp blade so that it reaches the substrate, attach adhesive cellophane tape to the surface, and peel off the paint film after abrupt peeling. Was calculated and evaluated according to the following criteria. : No peeling of coating film. : The coating film peels off slightly, but the peeled area is less than 1%. Δ: The coating film peels off, but the peeled area is 1% or more and less than 5%. X: The peeled area of the coating film is 5% or more.

<tables num="3"><img file="JP2005298837A_D0003.tif" /></tables>

<tables num="4"><img file="JP2005298837A_D0004.tif" /></tables>