JP2011016341A - Acrylic resin precoated metal sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic resin precoated metal sheet excellent in stainproofness and drawing processability.SOLUTION: A chemical conversion film is formed on a metal plate and a resin film is formed thereon to constitute the precoated metal sheet. The precoated metal sheet has, at least at its outer surface side, a silica-containing acrylic resin film 1 which has an acrylic resin as a base material and further contains colloidal silica 2 and a wax 3. Content of the wax 3 is 0.5 to 10% and in a resin film cross-section having an optional straight line of 1,000 μm as a side, the number of arched wax particles having a diameter d of 1 to 15 μm and depth of d/4 to d/2 is 1 to 30 and a gel fraction is 90% or more.

Description

  The present invention relates to an acrylic resin precoated metal plate having excellent antifouling properties and drawing workability.

Metal materials are often used for building materials and civil engineering structures. In these applications, durability that can withstand long-term use is particularly demanded, and it has been devised that surface treatment is performed to enhance the corrosion resistance and weather resistance of the metal material to maintain the aesthetic appearance.
In recent years, dirt due to automobile exhaust gas or the like has become particularly noticeable in civil engineering structures. Therefore, it is desired to develop a material having antifouling properties, that is, a material that is not easily soiled and that easily removes soiling. As such a material, a highly durable low-contamination paint, a photocatalyst paint, and the like have been developed and put into practical use by a post-coating method.
Compared with the post-coating method in which the metal material is coated after being processed, the pre-coating method in which the coating is performed before the processing can reduce the total cost by shortening the process. For this reason, pre-coated metal plates are used in applications such as building materials and civil engineering structures, and pre-coated metal plates having antifouling properties are attracting attention. As such a precoat metal plate, Patent Document 1 discloses a silica-containing acrylic resin precoat metal plate. Since the resin film is hard, the dirt substance does not easily enter, and since the resin film surface has hydrophilicity, the dirt substance can be easily washed.
In the pre-coated metal plate, it is necessary that the deformation of the resin film can follow the plastic deformation of the metal plate, and workability is important. As a pre-coated metal sheet that can be applied to processing conditions such as pressing, embossing, roll forming, etc. in a ceiling panel or exterior building material for bathrooms having a siding structure, and having a narrow interval between irregularities, Patent Document 2 Discloses an antifouling pre-coated aluminum plate.

Japanese Patent Laid-Open No. 2004-082516 JP 2007-196403 A

  The pre-coated metal plate having antifouling properties is increasingly desired to improve workability and may be required to withstand drawing. In such a case, it is conceivable that the surface roughness of the resin film is increased, the lubricating oil is easily accumulated in the recesses, and the lubricity during processing is ensured. However, in such a case, there remains a problem that dirt substances easily accumulate in the recesses and the antifouling property is poor.

  The present invention provides a precoated metal plate in which a chemical conversion film is formed on a metal plate and a resin film is formed thereon, and at least the outer surface side is based on an acrylic resin and colloidal silica. , A silica-containing acrylic resin film containing wax, the wax content is 0.5 to 10%, and the diameter d is 1 μm or more and 15 μm in the resin film cross section having one straight line of 1000 μm as one side. An acrylic resin precoat comprising 1 to 30 bow-shaped wax particles having a depth f of d / 4 or more and d / 2 or less and a gel fraction of 90% or more It is a metal plate.

  The silica-containing acrylic resin film of the present invention has excellent antifouling properties and drawability because wax particles having a specific shape are in a specific distribution state. In the silica-containing acrylic resin film of the present invention, as shown in FIG. 1, arcuate wax particles are present. If the wax particles exceed a certain size, contaminants diffuse in the depth direction and cannot be removed. In the present invention, since the bow-shaped wax particles have a specific size, the contaminants are difficult to diffuse in the depth direction and are easy to remove, so that the antifouling property is excellent. Further, since the number of the bow-shaped wax particles is in a specific range, the drawing property is excellent because the lubricity is improved while maintaining the excellent antifouling property. Further, since the silica-containing acrylic resin film of the present invention has a specific gel fraction, the silica-containing acrylic resin film has a dense cross-linking structure, and contaminants hardly enter the resin film surface. Therefore, even if the Ra on the surface of the resin film exceeds 0.15 μm and contaminants are likely to accumulate in the recesses on the surface of the resin film, the contaminants are not easily penetrated into the resin film surface, so the contaminants can be easily removed. can do.

FIG. 1 is an image showing the state of bow-shaped wax particles in a cross section of a silica-containing acrylic resin film of an acrylic resin precoated metal plate of the present invention.

A. Metal plate The metal plate used in the present invention is not particularly limited as long as it has sufficient strength to form building materials and the like and has sufficient workability. For example, 1000 series, 3000 series or 5000 series aluminum alloy, hot dip galvanized steel, hot dip galvanized aluminum alloy steel, electrogalvanized steel, galvanized aluminum steel, and stainless steel are mentioned.

B. Chemical conversion film The chemical conversion film is not particularly limited as long as it is interposed between the surface of the metal plate and the resin film to enhance the adhesion between them. For example, for aluminum alloys, a chemical conversion film formed with a phosphoric acid chromate treatment solution that is inexpensive and easy to manage bath solution, or a chemical conversion coating formed by a coating-type zirconium treatment that does not require changes in the treatment liquid components and does not require washing with water. Can be used. Such a chemical conversion treatment is performed by spraying a predetermined chemical conversion treatment liquid on the aluminum alloy plate or immersing the alloy plate in the treatment liquid at a predetermined temperature for a predetermined time. For hot-dip galvanized steel and hot-dip zinc-aluminum alloy steel, a conversion coating formed with a phosphating solution can be used in addition to chromate treatment. Before the chemical conversion treatment, in order to remove dirt on the surface of the metal plate or to adjust the surface properties, the metal plate is subjected to acid treatment (washing) with sulfuric acid, nitric acid, phosphoric acid, or the like, or caustic soda, It is desirable to perform alkali treatment (washing) with sodium phosphate, sodium silicate, or the like. Surface treatment by such cleaning is also performed by spraying a predetermined surface treatment liquid on the metal plate or immersing the metal plate in the treatment liquid at a predetermined temperature for a predetermined time.

C. Resin film A resin film is formed on the chemical conversion film.
C-1. At least the outer surface side is a silica-containing acrylic resin film having an acrylic resin as a base material and containing colloidal silica and wax.
In the resin film of the present invention, at least the outer surface side is a silica-containing acrylic resin film containing an acrylic resin as a base material and containing colloidal silica and wax.
Acrylic resins are particularly excellent in weather resistance, and the coating film performance is generally good. In addition, since it is relatively inexpensive, it is often used in paints. Furthermore, the gloss of the coating film surface can be made relatively high, and a relatively hard coating film can be formed. The acrylic resin is a copolymer of acrylic acid, methacrylic acid and the like and esters thereof. Even if a small amount of an epoxy resin, a melamine resin, a fluororesin, a urethane resin or the like is blended with such an acrylic resin, there is no problem.
By adding colloidal silica to the paint, it is evenly dispersed in the resin film immediately after coating, but is concentrated on the surface of the resin film during baking and drying. When this resin film is exposed to the atmosphere, it reacts with moisture and rainwater in the air, and a highly hydrophilic silanol group is generated on the surface, so that the water contact angle on the surface of the resin film can be lowered. As a result, rainwater or the like on the surface of the resin film can be easily spread and the attached dirt can be easily removed. In addition, colloidal silica is an inorganic substance and is harder than an organic resin. Therefore, the surface of the resin film becomes hard, and the dirt substance hardly penetrates into the resin film. The average particle size of the colloidal silica used in the present invention is preferably 0.01 μm or more and 0.3 μm or less. More preferably, it is 0.02 μm or more and 0.10 μm or less. . This is because when the particle size of the colloidal silica is 0.3 μm or less, silanol groups are finely present on the surface of the resin film, so that water wetting can be improved. Moreover, when the average particle diameter of colloidal silica exceeds 0.3 μm, the resin film becomes discontinuous at that portion, and therefore, it becomes a starting point for cracking of the resin film during drawing. If the average particle size of the colloidal silica is less than 0.01 μm, the improvement of water wettability is not recognized, and the cost increases. The content of colloidal silica is preferably in the range of 1 to 10%. If it is less than 1%, the hydrophilic effect cannot be sufficiently obtained, and the attached rainwater or the like tends to accumulate, and it is difficult for the contaminants to flow away. If it exceeds 10%, the resin film becomes hard, the starting point of the resin film cracks increases, and cracks are likely to occur during drawing.
Wax is added to the silica-containing acrylic resin film used in the present invention. The wax used in the present invention may be either a natural wax or a synthetic wax. Examples of natural waxes include beeswax, montan wax, carnauba wax, paraffin wax, and microcrystalline wax. On the other hand, examples of the synthetic wax include polyethylene wax, Fischer-Tropsch wax, castor oil and the like. In particular, it is preferable to use microcrystalline wax or polyethylene wax. Microcrystalline wax is a petroleum wax and is a white, pale yellow solid. Polyethylene wax is a synthetic hydrocarbon and is a white solid. The melting point of the added wax is preferably in the range of 50 to 150 ° C.
The average particle size of the added wax is preferably 5 to 20 μm. When the average particle size of the wax is less than 5 μm, the lubricity is insufficient and the drawability is inferior. On the other hand, when the average particle size exceeds 20 μm, the antifouling property is poor.

C-2. The wax content is 0.5 to 10%, and the diameter d is 1 μm or more and 15 μm or less and the depth f is d / 4 or more d in an arbitrary 1000 μm straight line on one side. 1 or more and 30 or less arcuate wax particles of / 2 or less.
The content of the wax is preferably 0.5 to 10.0% of the dry coating film weight. If it is less than 0.5%, the drawability is inferior. When it exceeds 10.0%, the antifouling property is inferior.
Solid wax particles dispersed in the paint at room temperature become liquid at a temperature at which the baking temperature exceeds the melting point of the wax particles. At the same time, the volatilization of the solvent progresses, so the viscosity increases and the shape of the wax particles is limited to some extent, and it is considered that the colloidal silica covers the wax particles. Due to convection, the wax particles that reach the surface layer have less surface energy than the base resin, so that they spread on the surface. However, in the surface layer, colloidal silica is distributed in the part without wax particles, so it is considered that arcuate particles are formed instead of being linear.
The wax particles added to the paint have a particle size. In the process of baking and hardening the paint, when the temperature above the melting point is reached, the wax melts. As mentioned above, the colloidal silica contained in the paint covers the wax particles and becomes arcuate particles. Therefore, the diameter d of the bow-shaped wax particles is affected by the particle size of the wax particles, the type of resin, the particle size of colloidal silica, and the amount added. After that, the shape is fixed as the curing of the resin proceeds from the temperature higher than the melting point of wax. The longer the temperature at which the resin is cured to some extent from the temperature higher than the melting point, the more slowly the shape is fixed, so the diameter d becomes smaller. On the other hand, the shorter it is, the faster it is fixed, and the diameter d becomes larger. The diameter d of the bow-shaped wax can be adjusted by appropriately controlling the particle size of the wax particles, the type of resin, the particle size of the colloidal silica, the addition amount, and the baking conditions. In the cross section of the resin film having an arbitrary 1000 μm straight line as one side, the diameter d of the bow-shaped wax particles is 1 μm or more and 15 μm or less. When the diameter d is less than 1 μm, the drawability is inferior, and when the diameter d exceeds 15 μm, the antifouling property is inferior.
The depth f of the arcuate wax particles increases as the diameter d increases. In the baking and curing process, the wax once melts, but its shape is fixed as the resin cures from a temperature higher than the melting point of the wax. The longer the temperature at which the resin hardens to some extent from the temperature above the melting point, the more slowly the shape is fixed, so the depth becomes smaller. On the other hand, as the length is shorter, the depth f becomes larger because it is fixed more rapidly. In the cross section of the resin film having an arbitrary 1000 μm straight line as one side, the depth f of the arcuate wax particles is d / 4 or more and d / 2 or less. If the depth f is less than d / 4, the drawability is inferior. When the depth f exceeds d / 2, the antifouling property is poor.
In the silica-containing acrylic resin film used in the present invention, the number of arcuate wax particles in the cross section of the resin film having one straight line of 100 μm as one side is 1 or more and 30 or less. If the number of bow-shaped wax particles is less than 1, the drawability is inferior. When the number of arcuate wax particles exceeds 30, antifouling properties and drawability are poor.
The state of the bow-shaped wax particles in the cross section of the resin film is that the metal of the pre-coated metal plate is dissolved and only the resin layer is collected, the collected resin layer is dyed with ruthenic acid, embedded in the embedding resin, and exposed with an ultramicrotome. Observe with FE-SEM, and measure diameter d, depth f, and number of bow-shaped wax particles.

C-3. The gel fraction is 90% or more.
The gel fraction of the silica-containing acrylic resin film is 90% or more. Preferably it is 95% or more. As the reaction progresses, the gel fraction increases. Therefore, as the gel fraction increases, the entanglement of the resin tends to become dense, and the contaminant does not easily penetrate into the resin film surface. However, if the gel fraction is less than 90%, the entanglement of the resin is not sufficient, so that the contaminant easily penetrates in the depth direction and the antifouling property is poor.
The gel fraction is calculated according to the following equation by immersing the precoated metal plate in boiled 2-butanone.
Gel fraction (%) = (weight after immersion−weight after film removal) * 100 / (initial weight−weight after film removal)
As will be described later, the gel fraction of the silica-containing acrylic resin film is adjusted by the final temperature of the metal plate and the baking time.
In addition, it is preferable that the thickness of the silica containing acrylic resin film used by this invention exists in the range of 2-20 micrometers. If the thickness is less than 2 μm, the corrosion resistance is inferior, and if it exceeds 20 μm, the resin film cannot follow the deformation of the metal plate during processing, and the drawability is inferior.

C-4. Additives The paints used in the present invention include pigments, pigment dispersants, fluidity regulators, leveling agents, anti-waxing agents used in ordinary paints to ensure paintability and general performance as precoat materials. Further, preservatives, stabilizers and the like may be added as appropriate. For example, titanium oxide or carbon black is preferable as the pigment, and phthalocyanine blue or the like may be used as the dye. Moreover, in order to improve the hydrophilicity immediately after coating, a silicone compound containing an alkoxy group may be added. Further, a matting agent may be added to adjust the gloss.

C-5. A method for producing an acrylic resin pre-coated metal plate A chemical conversion film is formed on a metal plate, and a coating material containing an acrylic resin as a base material and colloidal silica and further containing a specific amount of wax is rolled. It is applied by a coater and baked and dried by the method shown below.
Since the paint used in the present invention is lower than the melting point of the wax during storage at room temperature, the wax is dispersed in the paint in a solid state. Since the wax is dissolved in an appropriately adjusted solvent, the wax is uniformly dispersed in the paint without agglomerating and settling. In the process of baking and drying the paint, the temperature of the paint rises. When the melting point of the wax is exceeded, the wax in the paint becomes liquid, and is agitated by the convection of the paint, and moves to the paint surface because it has a lower surface energy than the acrylic resin and spreads on the surface. At that time, the coating material used in the present invention contains colloidal silica, and as described above, these concentrate on the coating surface. As a result, colloidal silica is present around the wax, so that wetting and spreading of the wax is suppressed, and when the resin film after drying is observed from a cross section, an arc shape is formed in the vicinity of the surface.
Therefore, in order to obtain the wax distribution of the present invention, it is preferable that the time from the temperature 6 ° C. higher than the melting point of the wax to the temperature 90 ° C. lower than the final temperature is 3 seconds or more. In this temperature range, the wax melts but the acrylic resin does not cure. In less than 3 seconds, many wax particles move to the paint surface, and arcuate particles are observed near the resin film surface after drying. When the temperature is lower than 6 ° C. from the melting point of the wax, the wax does not melt sufficiently. The time required to reach a temperature 6 ° C. higher than the melting point of the wax is preferably within 10 seconds. If it exceeds 10 seconds, the solvent in the paint evaporates to increase the viscosity of the paint, and the wax may not move to the surface even if it is kept at a temperature at which the acrylic resin is not cured.
In order to obtain the gel fraction of the present invention, it is preferable that the final reached temperature of the metal plate is 210 to 250 ° C. and the baking time is in the range of 30 to 80 seconds. If it is less than 210 degreeC, a gel fraction will be less than 90% and antifouling property will be inferior. When it exceeds 250 ° C., overbaking occurs, the silica-containing acrylic resin film deteriorates, and the drawing processability is inferior. If it is less than 30 seconds, the gel fraction is less than 90% and the antifouling property is poor. If it exceeds 80 seconds, the productivity is inferior and the cost increases.
As the solvent used for the paint, xylene, ethyl acetate, butyl acetate, isophorone, cyclohexanone and the like are used. In addition, it may replace with a roll coater and may apply | coat a coating material with an air spray, a bar coater, etc.

D. Undercoat layer In order to improve the workability of the precoated metal sheet used in the present invention, it is preferable to form an undercoat layer between the chemical conversion film and the silica-containing acrylic resin film. The thickness of the undercoat layer is preferably in the range of 2 to 50 μm. If it is less than 2 μm, the corrosion resistance is inferior, and if it exceeds 50 μm, the undercoat layer easily breaks following the cracking of the antifouling resin film by drawing.
As the base resin for the undercoat layer, a polyester resin or an epoxy resin is preferably used. This is because polyester resins have good workability during coating and good workability. This is because the epoxy resin has good adhesion to the chemical conversion film and excellent corrosion resistance.
As the polyester resin, alkyd resin, unsaturated polyester resin, modified alkyd resin and the like are used. The alkyd resin has a skeleton of a condensate of a polybasic acid such as phthalic anhydride and a polyhydric alcohol such as glycerin, which is modified with fatty acid fats and oils. Depending on the type and content of the fats and oils used, the oils are classified into short oil alkyd resins, medium oil alkyd resins, long oil alkyd resins and super long oil alkyd resins. An unsaturated polyester resin is synthesized by esterifying an unsaturated polybasic acid or a saturated polybasic acid and a glycol. As the polybasic acid, phthalic anhydride, isophthalic acid, terephthalic acid and adipic acid are used, and as the glycols, propylene glycol is often used. As the modified alkyd resin, those modified with a polymerizable monomer such as natural resin, phenol resin or styrene are used.
Epoxy resins include baking-curing type epoxy resins that are baked using the reaction of hydroxyl groups in the molecule, and curing by addition reaction between primary amines or secondary amines added as curing agents and epoxy groups. The two-component curable epoxy resin is often used. Bake curable epoxy resins include amine resin curable epoxy resins, phenol resin curable epoxy resins, isocyanate curable epoxy resins, and the like. The two-component curable epoxy resin includes an amine curable resin, an amine adduct curable resin, a polyamide resin curable resin, and the like.
In addition to baking curable epoxy resins and two-component curable epoxy resins, epoxy ester resins using ester compounds obtained by reacting an epoxy resin with a dry oil fatty acid, and methyl methacrylate bonded to the end of the epoxy resin. Vinyl esters copolymerized with styrene or the like can also be used.
A coating material in which a base resin is an essential component and these are dissolved or dispersed in an appropriate solvent is applied onto the chemical conversion film by a roll coater, treated in an oven at a predetermined temperature for a predetermined time, and baked and dried. As the solvent, cyclohexane, isophorone, isobutyl alcohol, xylene, ethylbenzene, methyl ethyl ketone, diacetone alcohol, ethylene glycol monobutyl ether, or the like is used. In addition, it may replace with a roll coater and may apply | coat a coating material with an air spray, a bar coater, etc.

  Hereinafter, the present invention will be described in detail with reference to examples. In addition, this invention is not limited to a following example, unless the range of a claim is exceeded.

Numbers 1 to 7 (invention example)
Both surfaces of the metal plate were degreased with a commercially available alkaline degreasing solution and subjected to chemical conversion treatment with a commercially available phosphoric acid chromate treating solution. A polyester resin coating was applied on one side so that the coating thickness after drying was 5 μm. The baking temperature was 216 ° C. as the final temperature of the metal plate, and the baking time was 40 seconds. Furthermore, the coating material A shown in Table 1 was applied.

Numbers 8 to 10 (Invention example)
Both surfaces of the metal plate were degreased with a commercially available alkaline degreasing solution, pickled with dilute sulfuric acid, and then subjected to chemical conversion treatment with a commercially available zirconium treatment solution. An epoxy resin coating was applied on one side so that the coating thickness after drying was 5 μm. The baking temperature was 210 ° C. at the final reached temperature of the metal plate, and the baking time was 50 seconds. Furthermore, the coating material A shown in Table 1 was applied.

Numbers 11-12 (Invention Example)
Both surfaces of the metal plate were subjected to chemical conversion treatment with a commercially available chromate treatment solution. A polyester resin coating was applied on one side so that the coating thickness after drying was 5 μm. The baking temperature was 210 ° C. at the final reached temperature of the metal plate, and the baking time was 50 seconds. Furthermore, the coating material A shown in Table 1 was applied.

Numbers 13 to 19 (comparative examples)
It painted like No. 1-7.

As a result of measuring the film amount of the chemical conversion film obtained by the above-described method using a fluorescent X-ray analyzer, the chromium content was 30 mg / m ² and the zirconium content was 10 mg / m ² .

About the obtained precoat metal plate, the gel fraction and the distribution state of the bow-shaped particles were measured.
(1) Gel fraction A pre-coated metal plate was immersed in boiled 2-butanone and calculated according to the following formula.
Gel fraction (%) = (weight after immersion−weight after film removal) * 100 / (initial weight−weight after film removal)
(2) Distribution state of arcuate particles Dissolve the metal of the pre-coated metal plate, collect only the resin layer, dye the collected resin layer with ruthenic acid, embed it in the embedding resin, surface it with an ultramicrotome, and FE -SEM was observed at five locations. From the observed image, the diameter d, depth f, and number of the bow-shaped particles were measured, and the average value thereof was calculated.

The obtained precoated metal plate was used to evaluate antifouling properties and drawing workability. In the evaluation, ○, ○ △, and Δ were accepted, and x was rejected.
(1) Antifouling property (a) An aqueous solution in which 5% by weight of carbon black was suspended was spray-coated on the surface of the carbon-fouling-resistant coating film, and then dried in a thermostatic bath at 60 ° C. for 1 hour. Next, the ΔL value after the carbon black adhering to the coating surface in running water was wiped with gauze and dried was measured.
○: ΔL ≧ −7
×: ΔL <−7
(B) Resistance to red magic ink removal The surface of the coating film after a 3 cm * 5 cm line was drawn with a commercially available Sakuraname (registered trademark) red magic ink, left for 24 hours, and then rubbed with Kimwipe soaked in ethanol 20 times. The remaining red magic was visually evaluated.
○: Almost removed.
○ △: Some traces remained.
Δ: A weak mark remained.
X: A considerable amount of marks remained.
(2) Drawing workability Drawing was carried out so that the resin film surface of the precoated metal sheet was outside the cylindrical molded product. As a result, the appearance of the side wall portion of the obtained cylindrical molded product was visually evaluated. The punch diameter was 32 mm, the die diameter was 33.68 mm, and the blank diameter was 68.5 mm.
○: No cracking of the resin film was observed.
◯: Some cracking of the resin film was observed.
Δ: The resin film was weakly cracked.
X: Remarkable cracking of the resin film was observed.

The results are shown in Table 2.

Nos. 1 to 12 are pre-coated metal plates in which a chemical conversion film is formed on a metal plate and a resin film is formed thereon. At least the outer surface side is based on an acrylic resin and contains colloidal silica and wax. It is a silica-containing acrylic resin film, the content of wax is 0.5 to 10%, and in a resin film cross section having one straight line of 1000 μm as one side, the diameter d is 1 μm or more and 15 μm or less, The number of arcuate wax particles having a depth f of d / 4 or more and d / 2 or less is 1 or more and 30 or less, and the gel fraction is 90% or more. Therefore, antifouling property and drawability were good.
On the other hand, No. 13 was inferior in drawing workability because the diameter d of the bow-shaped wax particles was less than 1 μm in the cross section of the resin film having an arbitrary straight line of 1000 μm as one side.
No. 14 was inferior in antifouling property because the diameter d of the bow-shaped wax particles exceeded 15 μm in the cross section of the resin film having an arbitrary straight line of 1000 μm as one side.
No. 15 was inferior in drawing workability because the depth f of the bow-shaped wax particles was less than d / 4 in the cross section of the resin film having an arbitrary 1000 μm straight line as one side.
No. 16 was inferior in the antifouling property because the depth f of the bow-shaped wax particles exceeded d / 2 in the cross section of the resin film having an arbitrary 1000 μm straight line as one side.
No. 17 was inferior in drawing workability because the number of arcuate wax particles was less than 1 in the cross section of the resin film having an arbitrary 1000 μm straight line as one side.
No. 18 was inferior in antifouling property and drawing workability because the number of the bow-shaped wax particles exceeded 30 in the cross section of the resin film having an arbitrary 1000 μm straight line as one side.
No. 19 was inferior in antifouling property because the gel fraction was less than 90%.

1 Silica-containing acrylic resin film 2 Colloidal silica 3 Bow-shaped wax particles 4 Diameter d
5 depth f

Claims (1)

  In a pre-coated metal plate in which a chemical film is formed on a metal plate and a resin film is formed thereon, at least the outer surface side is based on an acrylic resin, and a silica-containing acrylic resin film containing colloidal silica and wax The wax content is 0.5 to 10%, and in a resin film cross section having one straight line of an arbitrary 1000 μm, the diameter d is 1 μm or more and 15 μm or less, and the depth f is d / Acrylic resin pre-coated metal sheet characterized in that it has 1 or more and 30 or less arcuate wax particles of 4 or more and d / 2 or less and a gel fraction of 90% or more.

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