JP2006218688A - Painted metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated metal plate excellent in both scratch resistance and raindrop resistance.
The coated metal sheet of the present invention has a coating film having a film containing 1 to 40% by mass of plant fiber as the uppermost layer on at least one side of the base metal sheet, and the diameter of the plant fiber is a film. The length of the plant fiber is 100 times or less of the thickness of the film. The plant fiber is preferably at least one selected from the group consisting of bast fiber, vein fiber, fruit fiber and seed hair fiber.
[Selection figure] None

Description

  The present invention relates to a coated metal plate excellent in both scratch resistance and raindrop contamination suitable for the field of outdoor building materials such as roofs and walls.

  A coated metal plate obtained by coating a metal plate and imparting functions such as design and corrosion resistance is widely used in the field of building materials such as roofs and walls.

  Since these coated metal plates have been processed and formed into roofing materials and wall materials, so-called scratch resistance was required so that the surface of the coating film was not damaged during processing and forming. On the other hand, when it is actually used as a roof or a wall, it has been required to have so-called rainproof stain resistance, in which the surface of the paint film does not have rain lines.

  Techniques for improving the scratch resistance are mainly a method of increasing the hardness of the coating film by increasing the hardness of the resin itself constituting the coating film, and a coating film hardness by adding a high hardness substance to the coating film. Have been used. For example, Patent Document 1 discloses a paint for a precoated steel sheet to which flaky glass is added. This technology improves scratch resistance by increasing the hardness of the coating film by adding flaky glass with high hardness to the coating film. Certainly, this technique improved the scratch resistance of the coating film, but did not improve the stain resistance.

  On the other hand, as a technique for improving the stain resistance, for example, Patent Document 2 discloses a technique of adding an organic silicate compound such as methyl silicate or ethyl silicate to a paint. This technology utilizes the fact that a hydrophilic silanol group is formed on the surface by concentrating the organic silicate compound on the surface during painting and then causing hydrolysis. Oily soil that causes raindrop contamination cannot be firmly bonded to the surface of the hydrophilic coating film, and the rainwater flows along the surface of the hydrophilic coating film. The so-called soil release effect that is washed away improves the resistance to raindrops. Certainly, although this technique improved the raindrop contamination of the paint film, it did not solve the problem of scratches on the paint film surface during severe roll forming. In addition, although the raindrop stain resistance is maintained as long as silanol groups on the surface of the coating film exist, if the coating film deteriorates and the surface silanol group layer is lost as a result of long-term outdoor use, it is no longer resistant. There was also a problem that it did not show raindrop pollution.

  As described above, there is a problem that there is no coated metal sheet that satisfies both scratch resistance and raindrop resistance.

Japanese Patent Publication No.51-8128 Japanese Patent Laid-Open No. 10-324845

  Accordingly, the present invention has been made in view of such problems, and an object of the present invention is to provide a new and improved painted metal plate that is excellent in scratch resistance and raindrop resistance.

  In general, it has been conventionally known that a highly rigid substance should be added to the coating film to improve the scratch resistance of the coating film. On the other hand, to improve the raindrop contamination, the surface is made hydrophilic. Conventionally, it has been known that a hydrophilic surface should be maintained for a long period in an outdoor environment.

  As a result of intensive studies to solve the above problems, the present inventors have found that plant-based fibers are optimal as a substance that satisfies both the scratch resistance improvement and raindrop pollution resistance improvement. Based on this, the present invention has been completed.

  Specifically, the present inventors have found that the plant-based fiber has an appropriate rigidity so that the scratch resistance of the coating film can be improved, and moreover than the conventionally used flaky glass. It has been found that the specific gravity is light and exists on the surface of the coating film so that it can be efficiently scratched.

  On the other hand, the present inventors have a lot of hydrophilic hydroxyl groups that exert a soil release effect because the molecules constituting the plant fiber are mainly composed of cellulose in terms of raindrop contamination, and It has been found that it has a characteristic that it exists efficiently on the surface of the coating film because of its low specific gravity, and can provide excellent raindrop resistance. Furthermore, the present inventors have found that since the plant fibers are distributed to the inside rather than the conventional method of forming a hydrophilic silanol group on the outermost layer, the coating layer deteriorates and the outermost layer disappears. However, it was found that the raindrop-stain resistance was maintained by the plant-based fibers present inside.

  That is, according to the present invention, the plant fiber has an appropriate rigidity, its basic structure is cellulose and has many hydrophilic hydroxyl groups, and its specific gravity is light and easily exists in a state of floating on the surface of the coating film. It uses features.

The gist of the present invention having such characteristics is as follows.
(1) Having a coating containing 1 to 40% by mass of plant fiber as the uppermost layer on at least one side of the base metal plate, the thickness of the uppermost layer is A, and the diameter of the plant fiber A coated metal plate characterized by satisfying the conditions of the following mathematical formulas 1 and 2 when S and the length of the plant fiber are L:
S ≦ 0.8A (Formula 1)
L ≦ 100A (Formula 2)
(2) The coated metal sheet according to (1), wherein a thickness A of the uppermost layer is 5 μm or more and 5 mm or less.
(3) The coating according to (1) or (2), wherein the plant fiber is at least one selected from the group consisting of bast fiber, vein fiber, fruit fiber and seed hair fiber. Metal plate.
(4) The painted metal sheet according to (3), wherein the bast fiber is at least one selected from the group consisting of jute fibers and kenaf fibers.
(5) The coated metal sheet according to any one of (1) to (4), wherein the surface of the uppermost layer has a hydroxyl group.
(6) The coated metal plate according to any one of (1) to (5), wherein the uppermost layer film contains a biodegradable organic substance.
(7) The coated metal plate according to any one of (1) to (6), wherein the base metal plate is a plated steel plate.

  According to the present invention, it is possible to provide a coated metal plate that is excellent in both scratch resistance and raindrop resistance. Therefore, the painted metal plate according to the present invention can be particularly suitably used as a painted metal plate for building materials such as roofs and walls.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  The coated metal plate according to one embodiment of the present invention has a coating film having a coating containing 1 to 40% by mass of plant-based fibers as the uppermost layer on at least one surface of the base metal plate, and the thickness of the coating on the uppermost layer. Is A, the diameter of the plant fiber is S, and the length of the plant fiber is L, the conditions of the following formulas 1 and 2 are satisfied.

S ≦ 0.8A (Formula 1)
L ≦ 100A (Formula 2)

  The reason why the content of the plant fiber in the film is limited to 1 to 40% by mass is that if it is less than 1% by mass, the effect of adding the plant fiber is not seen, and both the scratch resistance and the raindrop stain resistance are obtained. It is insufficient. On the other hand, if it exceeds 40% by mass, the proportion of the plant fiber in the film becomes too large, and the resin component is relatively small. The range of the more preferable addition amount of the plant fiber in a film | membrane is 5-30 mass%.

  The reason why the diameter (S) of the plant fiber is set to 80% or less of the thickness (A) of the film is that if it exceeds 80%, the coating film cracks during severe processing and molding. Similarly, the reason why the length (L) of the plant fiber is set to 100 times or less of the thickness (A) of the film is that when it exceeds 100 times, the coating film cracks during severe processing and molding. More preferably, the diameter of the plant fiber is 40% or less of the thickness of the film, and the more preferable length of the plant fiber is 10 times or less of the thickness of the film.

  The lower limit of the diameter and length of the plant fiber is not particularly defined, but since the plant fiber is derived from natural products, it is difficult to obtain a fiber that is too small. The diameter is about 5 μm and the length is about 20 μm. Is the lower limit.

  The thickness (A) of the uppermost layer containing plant fiber is not particularly limited, but is preferably 5 μm or more and 5 mm or less. If it is less than 5 μm, the appearance of the coating film becomes slightly inferior depending on the shape of the plant fiber, and if it exceeds 5 mm, the effects of scratch resistance and stain resistance are saturated, which is not economical.

  The plant fiber of the present embodiment is not particularly limited, and plant fibers derived from natural products and processed products thereof can be used. For example, jute fiber, kenaf fiber, Fuji fiber, flax fiber, ramie fiber, bast fiber such as cannabis fiber, Manila hemp fiber, sisal hemp fiber, leaf vein fiber such as New Zealand hemp fiber, palm fruit Examples thereof include fruit fibers such as fiber fibers, seed hair fibers such as cotton fibers, and kapok fibers. Among them, bast fibers are preferable, and kenaf fibers and jute fibers are particularly preferable. In particular, kenaf has the highest carbon dioxide absorption capacity as a plant, and in recent years, it has been cultivated in various countries around the world as a countermeasure against global warming. There was no usage yet. Therefore, the present invention is meaningful as a method for effectively using kenaf.

  By allowing a hydroxyl group to be present on the surface of the uppermost layer containing the plant fiber of the present embodiment, it is possible to more effectively impart raindrop resistance. This is due to a synergistic effect of the hydroxyl group and the hydrophilicity of the plant fiber. Further, a coated metal plate having a hydroxyl group formed on the surface thereof has been conventionally known, and the scratch resistance of this known painted metal plate can be improved by the added plant fiber.

  The method of making a hydroxyl group exist is not specifically limited, A well-known method is applicable. For example, a method using a paint containing an organosilicon compound such as ethyl silicate or methyl silicate can be mentioned. When these coating materials are used, alkoxide groups such as methoxy groups and ethoxy groups are oriented on the surface, and further hydrolyzed to form silanol groups in which hydroxyl groups are bonded to silicon.

  The amount of hydroxyl groups present on the surface of the uppermost layer is not particularly limited, but in the case of silanol groups, the condition is that the content of the organosilicon compound is 1 to 30% by mass with respect to the total solid content in the paint. Is preferred. If it is less than 1% by mass, the effect of forming hydroxyl groups (silanol groups) on the surface is not seen. On the other hand, if it exceeds 30% by mass, the viscosity of the paint becomes high, making it difficult to paint, It is not preferable because it causes a decrease. Similar to the organosilicon compound, an organotitanium compound or an organozirconium compound can also be applied.

  Further, by forming the uppermost layer film containing the plant fiber of the present embodiment using a biodegradable organic material, it is possible to more efficiently impart rainproof stain resistance. This is due to the synergistic effect of the hydrophilicity of the biodegradable organic matter and the hydrophilicity of the plant fiber. In addition, the addition of plant fiber provides better scratch resistance than biodegradable organic substances alone.

  In addition, since biodegradable organic materials have the characteristic of decomposing in the natural environment, this coated metal sheet containing a biodegradable bioorganic substance can be coated with a film like a known painted metal sheet even when illegally dumped. The organic resin is not semi-permanently left, but the film is decomposed and the additive is also plant fiber.

  The biodegradable organic substance is not particularly limited, and known ones can be applied. For example, microbial production biodegradable organic substances represented by polyhydroxybutyrate, chemically synthesized biodegradable organic substances represented by aliphatic polyester and polylactic acid, succinates represented by polybutylene succinate adipate And natural product-based biodegradable organic substances represented by cellulose acetate. The abundance of biodegradable organic matter in the uppermost layer is not particularly limited, but when biodegradable organic matter is included, it is expected that biodegradable organic matter should be used against non-biodegradable organic matter. The composition ratio is preferably equal to or more than the same amount.

  In addition to the above-described biodegradable organic matter, the resin of the paint used for the coated metal plate of the present embodiment is not particularly limited, and those usually used as paint resins can be applied. For example, resin components such as high molecular polyester resin, polyester resin, acrylic resin, epoxy resin, urethane resin, fluorine resin, or modified resins thereof, butylated melamine, methylated melamine, butylmethyl mixed melamine , Urea resins, isocyanates, or those cross-linked with a cross-linking component of a mixed system thereof may be used. Further, an electron beam curable type, an ultraviolet curable type, a thermosetting type or a thermoplastic type may be used.

  It is also possible to produce a film containing the plant fiber of this embodiment and laminate the metal plate in the film state. Examples of resins suitable for laminating include fluororesins, acrylic resins, polyvinyl chloride resins, polyethylene terephthalate resins, and the like, and commonly used adhesives and corona discharge treatments may be used in combination.

  The coated metal plate of the present embodiment may be colored using a colorant such as a color pigment or dye that is used in ordinary paints. The colorant is not particularly limited. As the colorant, known ones can be used regardless of inorganic, organic, or a combination of both. For example, cyanine pigments such as titanium white, zinc yellow, alumina white, cyanine blue, pyrazolone orange, Examples include azo pigments, bitumen, condensed polycyclic pigments, metallic pigments / powder, pearl pigments, mica pigments and other bright pigments, indigoid dyes, sulfur dyes, phthalocyanine dyes, diphenylmethane dyes, nitro dyes, acridine dyes, and the like. The concentration of the colorant is not particularly limited, and may be determined according to the necessary color and hiding power.

  In addition to the colorant, any additives that are usually added to paints can be added without any problem. For example, extender pigments such as calcium carbonate, talc, gypsum, and clay, and other organic cross-linked fine particles and / or inorganic fine particles may be added. If necessary, a surface smoothing agent, an ultraviolet absorber, a hindered amine light stabilizer, a viscosity adjusting agent, a curing catalyst, a pigment dispersant, a pigment settling inhibitor, a color separation inhibitor, and the like can be used.

  For the purpose of improving the corrosion resistance of the coated metal plate of this embodiment, a rust preventive pigment may be added to the coating film of this embodiment. As the rust preventive pigment, known ones can be applied, for example, phosphate phosphate rust preventive pigments such as zinc phosphate, iron phosphate, aluminum phosphate, zinc phosphite, calcium molybdate, aluminum molybdate, molybdic acid. Molybdate anticorrosion pigments such as barium, vanadium anticorrosion pigments such as vanadium oxide, silicate pigments such as calcium silicate, strontium chromate, zinc chromate, calcium chromate, potassium chromate, chromate anticorrosion pigment such as barium chromate, Fine silica such as water-dispersed silica and fumed silica, ferroalloy such as ferrosilicon, and the like can be used. These may be used alone or in combination.

  Nickel filler or the like may be added to the painted metal plate of this embodiment to impart conductivity.

  The coated metal plate of this embodiment can be painted by any method. Examples of the coating method include bar coater, spray coating, brush coating, roll coater, overflow curtain coater, slit curtain coater, roller curtain coater, T-die, and multilayer curtain coater.

  The method of drying (curing) the coated metal plate of this embodiment is arbitrary, and is suitable for the paint used, such as heat drying such as hot air heating and high-frequency induction heating, natural drying, curing by electron beam, and ultraviolet irradiation. Should be selected.

  Although the base metal plate of this embodiment is not specifically limited, A stainless steel plate, a plated steel plate, and an aluminum alloy plate are suitable. Examples of the stainless steel plate include a ferritic stainless steel plate, a martensitic stainless steel plate, and an austenitic stainless steel plate. Examples of aluminum alloy plates include JIS 1000 series (pure Al series), JIS 2000 series (Al-Cu series), JIS 3000 series (Al-Mn series), JIS 4000 series (Al-Si series), and JIS 5000 series. (Al-Mg system), JIS 6000 system (Al-Mg-Si system), JIS 7000 system (Al-Zn system), and the like.

  A particularly suitable base metal plate is a plated steel plate having a good balance between cost and performance (corrosion resistance, workability, paintability, etc.). Examples of the plated steel sheet include galvanized steel sheet, zinc-iron alloy plated steel sheet, zinc-nickel alloy plated steel sheet, zinc-chromium alloy plated steel sheet, zinc-aluminum alloy plated steel sheet, aluminum-plated steel sheet, zinc-aluminum-magnesium alloy plating. Examples include steel plates, zinc-aluminum-magnesium-silicon alloy plated steel plates, aluminum-silicon alloy plated steel plates, galvanized stainless steel plates, and aluminum plated stainless steel plates.

  Examples of the pretreatment for coating the base metal plate include washing with water, washing with water, pickling, alkali degreasing, grinding, polishing, and the like, and these can be performed alone or in combination as necessary. The pretreatment conditions may be selected as appropriate.

  Chemical conversion treatment may be performed on the base metal plate as necessary. The chemical conversion treatment is performed for the purpose of strengthening the adhesion between the coating and the base metal plate and improving the corrosion resistance. As the chemical conversion treatment, known techniques can be used, for example, zinc phosphate treatment, chromate treatment, silane coupling treatment, composite oxide film treatment, non-chromate treatment, tannic acid treatment, titania treatment, zirconia treatment, etc. And the like.

  The coated metal plate of this embodiment is coated with a film containing plant fiber on at least the uppermost layer on one side. Moreover, you may give the undercoat which contains a rust preventive pigment between the membrane | film | coat and metal plate of this embodiment. Undercoat paints can be used as they are for normal undercoat. As the resin, generally known resins can be applied depending on the application. That is, for example, polymer polyester resin, polyester resin, acrylic resin, epoxy resin, urethane resin, fluorine resin, silicon polyester resin, vinyl chloride resin, polyolefin resin, butyral resin, polycarbonate resin Resin, phenolic resin, or resin components such as these modified resins are cross-linked with butylated melamine, methylated melamine, butylmethyl mixed melamine, urea resin, isocyanate, or a crosslinker component of these mixed systems. it can.

  As the rust preventive pigment for the undercoat layer, known rust preventive pigments can be applied. For example, phosphate phosphate rust preventive pigments such as zinc phosphate, iron phosphate, aluminum phosphate, zinc phosphite, calcium molybdate, molybdenum Molybdate anticorrosive pigments such as aluminum oxide and barium molybdate, vanadium antirust pigments such as vanadium oxide, silicate pigments such as calcium silicate, strontium chromate, zinc chromate, calcium chromate, potassium chromate, chromate such as barium chromate Anti-corrosive pigments, fine silica such as water-dispersed silica and fumed silica, ferroalloys such as ferrosilicon, and the like can be used. These may be used alone or in combination.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these at all.

As the base metal plate, a hot-dip galvanized steel plate having a thickness of 0.27 mm (single-sided plating adhesion amount 90 g / m ² ) was used. The hot dip galvanized steel sheet was first subjected to alkali degreasing and chromate treatment. Further, a polyester resin paint (NSC200HQ, clear, manufactured by Nippon Fine Coatings Co., Ltd.) is used as a basic paint composition, and various plant fibers are added to the basic paint composition, whereby various paints according to the examples of the present invention are used. A composition and a coating composition according to a comparative example were prepared.

  As plant fibers, jute fibers and kenaf fibers as bast fibers, manila hemp fibers as leaf fibers, palm fruit fibers as fruit fibers, and cotton yarn fibers as seed hair fibers were used. In addition, a coated metal plate to which equal amounts of jute fiber and kenaf fiber were added was also prepared. The thickness of the film was set at two levels of 15 μm and 100 μm.

  As an example of a multi-layer structure, 5 μm of an undercoating paint (Nippon Fine Coatings Co., Ltd., P655) containing a rust preventive pigment is applied on a base metal plate, and kenaf fibers are added to the above basic coating composition. The performance of the coated paint added under the conditions of film thicknesses of 15 μm and 100 μm was also evaluated.

  A coating for investigating the influence of the silanol groups on the surface was also prepared by adding 5 mass% of ethyl silicate (manufactured by Colcoat, ES-40) to the basic coating composition. Kenaf fiber was added as plant fiber, and the thickness of the film was 15 μm and 100 μm. It is known that when a paint containing this ethyl silicate is applied, ethyl silicate is concentrated on the surface and further hydrolyzed to form silanol groups.

  Instead of the basic paint composition, a paint using polylactic acid was also prepared as a biodegradable paint composition. Kenaf fiber was added as plant fiber, and the thickness of the film was 15 μm and 100 μm.

  In addition, the diameter and length of various plant fiber measured the diameter and length of 30 fibers with the optical microscope, and made it the average value. The thickness of the coating film was determined by observing the cross section of the coated metal plate with an optical microscope.

  The various coated metal plates produced were evaluated for scratch resistance, raindrop resistance, and workability according to the following criteria.

1. Evaluation method of scratch resistance The evaluation of scratch resistance was based on the pencil hardness test of JIS K 5400. Compared with the conditions in which the basic paint composition was applied, a product whose hardness was increased by one rank or more was regarded as acceptable.

2. Evaluation method of raindrop contamination After the initial deterioration of the paint film in the outdoor environment was conducted for 48 hours by conducting a sunshine carbon arc type accelerated weathering test (JIS K 5400) on the various coated metal plates produced. , A raindrop contamination test was conducted. For those with silanol groups formed on the surface, an accelerated weather resistance test was not performed, but an example of a rainproof stain resistance test was also performed.
The raindrop resistance test was carried out by processing the test piece into the shape shown in FIG. The degree of rain streaks on the evaluation surface (vertical surface) in FIG. 1 was visually observed and evaluated according to the following criteria, with 3 or more being accepted. The raindrop exposure test was conducted for three months in Futtsu City, Chiba Prefecture.

3. Evaluation method of workability Painted metal plate with 20μC condition, painted metal plate with 15μm thickness is 3T bent (180 ° bend with 3 sheets of same thickness), and coated metal plate with 100μm thickness Was subjected to 5T bending (bending 180 ° with 5 sheets of the same thickness sandwiched), cellotape (registered trademark) was applied to the bent portion, and then the cellotape was instantaneously peeled off. The film adhered to the cello tape was visually observed, and the workability was evaluated in five stages according to the following criteria.

  Tables 3 to 11 show the results of the performance evaluation test of the coated metal sheet. From these tables, it was found that the coated metal plate containing plant fiber according to the examples of the present invention has both excellent scratch resistance and raindrop resistance, and is suitable for outdoor building materials. In addition, when bast fibers such as kenaf fiber and jute fiber are used as plant fibers, the coated metal sheet has better raindrop resistance and workability than when other plant fibers are used. I found it. In addition, when the surface has hydroxyl groups such as silanol groups or biodegradable coating, it was found that the coated metal plate has particularly excellent raindrop resistance.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are of course within the technical scope of the present invention. Understood.

It is explanatory drawing which shows the shape of a raindrop contamination exposure test body.

Claims (7)

Having a coating film containing 1 to 40% by mass of plant fiber as the uppermost layer on at least one side of the base metal plate;
Painted metal characterized by satisfying the following formulas 1 and 2 where A is the thickness of the uppermost coating, S is the diameter of the plant fiber, and L is the length of the plant fiber: Board.
S ≦ 0.8A (Formula 1)
L ≦ 100A (Formula 2)   2. The coated metal plate according to claim 1, wherein a thickness A of the uppermost layer is 5 μm or more and 5 mm or less.   The coated metal sheet according to claim 1 or 2, wherein the plant fiber is at least one selected from the group consisting of bast fiber, vein fiber, fruit fiber and seed hair fiber.   The painted metal sheet according to claim 3, wherein the bast fiber is at least one selected from the group consisting of jute fibers and kenaf fibers.   The coated metal plate according to any one of claims 1 to 4, wherein the surface of the uppermost layer has a hydroxyl group.   The coated metal plate according to any one of claims 1 to 5, wherein the uppermost layer coating contains a biodegradable organic substance. The coated metal plate according to claim 1, wherein the base metal plate is a plated steel plate.

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