JP2006218448A - Method for manufacturing coated metal plate and coated metal plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a coated metal plate capable of making coarseness of a coating film large without processing machining work to the metal plate which is a base material containing aggregate of a large particle size and to the coating film after forming a film and capable of forming the coating film with high design properties having an appearance of unglazed pottery. <P>SOLUTION: After a first paint is applied on a surface of a metal plate and a second paint is applied before forming a film of the first paint, the first and second paint are heated and films are formed. At least the second paint out of 2 paints is a wrinkle finish coating material and it is preferable that the first paint is also a wrinkle finish coating material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a painted metal plate that can be used for building materials such as exterior materials, and a painted metal plate.

  A coated metal plate in which the surface of a metal plate such as a plated steel plate has been previously coated (pre-coated) is widely used as a building material such as an exterior material in the building field.

  Conventionally, by adding a curing catalyst blocked with an amine to a polyester / melamine-based paint as a pre-coat paint, the difference in cure speed between the surface layer and the lower layer in the curing process of the coating film is increased, and a fine shrinkage pattern is formed on the surface. A formed painted metal sheet is provided.

  In the coated metal plate as described above, it is possible to change the size of the shrinkage and the size (roughness) of the unevenness by finely controlling the difference in the curing rate in the coating film.

As described above, the coated metal plate whose design property is improved by using the shrunk paint has been widely used in recent years, but the user has been required to further improve the design property. In particular, as an exterior material, in recent years, it has been demanded that the surface roughness of the coating film be increased to have an unglazed appearance and touch, and thus the coated metal plate has such a large roughness. There is an increasing demand to form a coating film.
JP-A-11-104558

  However, there is a limit to the roughness of the coating film by shrinkage paint, and it has been difficult to form a coating film having a large roughness. If the roughness of the coating film is simply increased, it is conceivable that aggregates having a large particle size are included in the coating film, but the coated steel sheet is often processed and transported in a coil shape, and therefore in the coil shape. When winding, there is a possibility that aggregates may fall off or the coating film may crack. In addition, in order to increase the roughness of the coating film, it may be possible to form unevenness in advance on the metal plate that is the base material, or to apply surface treatment after forming the coating film to form unevenness. Increases the manufacturing cost, and it is also difficult to form a rough surface having a natural texture.

  The present invention has been made in view of the above points, and can be applied without adding aggregates having a large particle size or mechanical processing to a metal plate as a base material or a coating film after film formation. An object of the present invention is to provide a method for producing a coated metal plate and a coated metal plate capable of increasing the roughness of the film and forming a highly designable coating film having an unglazed appearance. .

  In the method for producing a coated metal plate according to the present invention, the first paint is applied to the surface of the metal plate, the second paint is further applied before the first paint is formed, and then the first and first coatings are applied. Including a step of heating and forming a second paint, wherein at least a second paint of the paints is a shrink paint.

  At this time, the first paint is also preferably a shrink paint.

  Further, as the shrinkage paint, a polyester / melamine paint obtained by adding a curing catalyst blocked with amines can be suitably used.

  The coated metal plate according to the present invention is manufactured by the method as described above, and the ten-point average roughness Rzjis82 of the surface of the coating film obtained by heating and forming the first paint and the second paint. Is 55 μm or more.

  According to the present invention, it is possible to increase the ten-point average roughness (Rzjis82) of a coating film formed on a metal plate without incorporating an aggregate having a large particle size into the paint or performing mechanical processing. It is possible to obtain a coated metal plate having a high design and having an unglazed appearance and touch.

  Hereinafter, the present invention will be described based on the best mode for carrying out the invention.

  Although it does not restrict | limit especially as the metal plate 1 used by this invention, For example, an aluminum plating steel plate, a galvanization steel plate, an aluminum galvanization steel plate, a stainless steel plate etc. can be mentioned. Moreover, as such a metal plate 1, a long thing can be used.

  The galvanized steel sheet is formed by immersing a steel sheet such as a mild steel sheet in a hot dip galvanizing bath to form a galvanized layer on the surface of the steel sheet. In this hot dip galvanizing bath, other materials that do not impair the properties of the hot dip galvanized steel sheet such as corrosion resistance, adhesion to the coating film, etc., such as hot dip galvanizing baths conventionally used for hot dip galvanizing are allowed. Impurities and other conscious additives may be present, such as trace impurities such as lead, iron, copper, cadmium, tin, etc. contained in each raw material component, production such as iron, copper, lead, etc. Impurities inevitably mixed in the process, components such as additives such as manganese, tin, nickel, molybdenum, tungsten, cobalt, chromium, titanium, cadmium, antimony, lanthanum, and selenium may be included.

  The aluminum-zinc alloy-plated steel sheet is obtained by forming an alloy plating layer containing aluminum, zinc, and other metal components added as necessary on the surface of a steel sheet such as a mild steel sheet. The composition of the alloy plating layer is not particularly limited. For example, so-called low aluminum-zinc alloy plating in which 4 to 10% by weight of aluminum is applied, and the remainder of the alloy plating is a combination of zinc and Ce-La. The steel plate and the surface of the steel plate contain 25 to 75% by weight of aluminum and 0.5% by weight or more of silicon with respect to the aluminum content, and the remainder forms an alloy plating layer consisting essentially of zinc. A so-called high aluminum-zinc alloy plated steel sheet can be used.

  In applying the above plating to the steel sheet, a known method such as immersing the steel sheet as a base material in a molten metal bath containing zinc, aluminum, silicon, etc. at the same blending ratio as the composition of the desired plating layer. Means can be used. Although the formation conditions of the plating layer at this time are not particularly limited, for example, the steel sheet is immersed in a molten metal bath at 550 to 650 ° C. for 1 to 10 seconds, and then cooled at a cooling rate of 20 to 40 ° C./second to obtain aluminum. -A zinc alloy plated steel sheet can be obtained.

  Moreover, as a stainless steel plate, the thing made from SUS304 can be used, for example.

  The first paint and the second paint are sequentially applied to such a metal plate. Prior to this, a chemical conversion treatment such as a chromate treatment or a zinc phosphate treatment, or a metal plate, if necessary. It is possible to perform pretreatment such as removal of dirt such as oil and fat on the surface of 1 and application of an undercoat paint.

  As the first paint and the second paint, at least a shrink paint (crepe paint) is used as the second paint. Any suitable shrinkage paint can be used. For example, a shrinkage paint obtained by adding a curing catalyst blocked with an amine to a polyester / melamine paint, that is, a polyester resin and a melamine resin such as a low-nuclear methylated melamine resin. And a reaction mixture obtained by reacting a curing catalyst such as sulfonic acid with an amine in an appropriate solvent can be used. If necessary, an appropriate pigment or dye for coloring, organic powder or glass fiber for adjusting the physical properties and shrinkage of the coating film, and the like can also be contained. At this time, when the content of the polyester resin is 100 parts by mass, the content of the melamine resin is preferably 10 to 50 parts by mass, and the content of the curing catalyst blocked with amine is preferably 1 to 10 parts by mass. When the organic powder is contained, the content is preferably 5 parts by mass or less when the content of the polyester resin is 100 parts by mass, and when the glass fiber is contained, the content is The amount is preferably 35 parts by mass or less.

  Moreover, it does not restrict | limit especially as a 1st coating material, Appropriate thermosetting coating materials, such as a polyester-type coating material, are used. In particular, if a shrinkage paint similar to the second paint is used as the first paint, the surface roughness of the coating film can be further increased.

  In applying the first paint and the second paint, after the first paint is applied, the second paint is applied in a wet state without heating and curing the coating film. A film is formed, and then the first paint and the second paint are heated and cured to form a film. Thereby, the roughness of the formed coating film is compared with the case where the coating film is formed with a single paint or when the second coating film is applied after the first coating film is formed. Can be made larger.

  The reason why the roughness of the coating film becomes large is not always clear, but the presence of the first paint in a wet state on the lower layer side during heating film formation causes the second paint to shrink during the film formation process. This facilitates the flow of the second paint when the surface of the coating film becomes rough, and this is considered to increase the roughness of the surface of the coating film. In particular, when both the first paint and the second paint are shrink paints, it is considered that the first paint also contributes to an increase in shrinkage, and the surface roughness of the coating film is further increased.

  Here, the roughness of the coating film means a ten-point average roughness (Rzjis82; JIS B 0601: 2001, Annex 1, JIS B 0601: 1982). This is because it is optimal to evaluate the appearance and roughness of the rough surface of the unglazed tone with Rzjis82. When the coating film is formed as described above, it is possible to make the Rzjis82 of the coating film 55 μm or more. Such a coated steel sheet has an unglazed appearance and is very designable. Is expensive.

  In addition, as the coating film thickness increases, the coating film roughness increases, and as the coating film thickness decreases, the coating film roughness tends to decrease. It becomes large when both the two paints are shrunk paints. For this reason, the film thickness of the coating film is appropriately adjusted according to the composition of the coating material so that a coating film having a desired roughness can be formed. The range of ˜30 μm, the thickness of the coating film made of the second paint is preferably in the range of 1 to 10 μm, and the total thickness is preferably in the range of 8 to 40 μm.

  In addition, the viscosity of the first paint and the second paint is appropriately adjusted according to the application method, etc. In order to form the coating film so as to have a sufficiently large roughness, Paint Ford Cup No. The viscosity according to No. 4 is preferably 50 seconds or more. The viscosity according to 4 is preferably in the range of 15 to 40 seconds.

  An outline of the process of performing the coating process on the metal plate 1 in this way is shown in FIG. In this process, the payoff reel 12, the pretreatment unit 13, the undercoat coating unit 14, the baking furnace 15, the cooling device 16, the coating application device 17 for coating the first coating material, and the secondary coating are performed from the start side to the end side. A paint spraying device 21, a baking furnace 18, a cooling device 19, and a take-up roll 22 are sequentially disposed.

  A long metal plate 1 is wound around the payoff reel 12 in a roll shape, and the long metal plate 1 is unwound from the payoff reel 12 and fed out in the longitudinal direction toward the end of the process. It is designed to be transported.

  The long metal plate 1 fed out from the payoff reel 12 is introduced into the pretreatment unit 13 and is subjected to chemical conversion treatment such as chromate treatment and zinc phosphate treatment, and dirt such as oil and fat on the surface of the metal plate 1. After being subjected to preprocessing such as removal of the image, it is derived from the preprocessing unit 13.

  The metal plate 1 is introduced into the undercoating part 14 after pretreatment, the undercoating paint is applied to the surface to form the undercoating film 5, and further introduced into a baking furnace 15 such as a hot air oven or a dielectric heating device. The coating film 5 is heated and baked and cured. The heated metal plate 1 passes through the cooling device 16 and is cooled.

  At this time, as an undercoat paint, for example, extender pigments such as titanium oxide, fine powder clay, calcium carbonate, and antirust pigments are dispersed in thermosetting resin varnishes such as epoxy resin varnish, epoxy urethane resin varnish, and polyester resin varnish. It is possible to use a resin-based paint. As the rust preventive pigment, for example, pigments mainly composed of chromates such as strontium chromate and calcium chromate can be used. In the undercoat coating portion 14, an undercoat paint having such a composition is applied to one surface of the metal plate 1, and in some cases, the undercoat paint is also applied to the other surface of the metal plate 1. Further, a back coating material having a composition different from that of the undercoat paint may be applied to the other surface of the metal plate 1. In the example shown in the drawing, the undercoat paint and the back coat paint are applied by bringing the application rolls 14a and 14b supplied with the paint into contact with the upper and lower surfaces of the metal plate 1, respectively. A normal coating apparatus composed of coating, roll coater, air knife, electrostatic coating or the like can be provided.

  The thickness of the undercoat coating film 5 is not particularly limited and is appropriately set, but is preferably in the range of 3 to 25 μm.

  The metal plate 1 on which the undercoat film 5 is formed then sequentially passes through a paint coating device 17 for coating the first paint and a paint spraying device 21 for secondary coating, and the first paint and the first coating on the surface. The two coating materials are sequentially applied in a wet state, and further introduced into a baking furnace 18 such as a hot air furnace or a dielectric heating device, whereby the top coat film 4 is heated and baked and cured.

  In the coating material application device 17 for applying the first coating material, the first coating material is applied to the entire surface of one surface of the metal plate 1. In some cases, the first coating material is also applied to the other surface of the metal plate 1. Apply. Further, a back coating material having a composition different from that of the first coating material may be applied to the other surface of the metal plate 1 instead of the first coating material.

In the example shown in the figure, a roll coat is adopted as a coating method at the time of applying the first paint. In other words, the coating material application device 17 is composed of a coating roll 17a for back coating and a coating roll 17b for coating the first coating, and the application of the first coating or the back coating is performed in the illustrated example. The coating rolls 17a and 17b supplied with the paint are brought into contact with the upper and lower surfaces of the metal plate 1, respectively. The configuration of the paint coating device 17 is not limited to this, and a coating device using an appropriate method such as dipping, spraying, brushing, roll coater, air knife, electrostatic coating, or the like can be used. This first coating is applied over the entire surface of the metal plate 1 on which the undercoat coating 5 has been formed, whereby a coating with the first coating is formed.

  Thus, after the coating film by a 1st coating material is formed, the 2nd coating material 10 is apply | coated in the wet state, without heating and hardening this coating film, and a coating film is formed. There is no particular limitation on how long it takes to apply the second paint 10 after the coating film is formed with the first paint, but it is preferably within 90 seconds.

  The coating material application device 20 for applying the second coating material 10 is disposed on the downstream side of the coating material application device 17 for the first coating material including application rolls 17a and 17b.

  In the illustrated example, the coating material application device 20 is provided with a coating material spraying device 21 above the metal plate 1. The coating material spraying device 21 applies the coating material spraying device 21 to the metal plate 1 coated with the first coating material. On the surface on the one surface side of the metal plate 1, the second paint 10 is sprayed and applied onto the uncured first paint film before being baked and cured.

  The configuration of the coating material application device 20 is not limited to that by spray spraying, and a device by curtain coating or the like can be adopted. However, in order to apply the coating material to the upper surface of the uncured first coating material, It is preferable to employ a non-contact coating method in which the second coating material 10 is applied in a state in which the nozzle of the first coating material is separated from the upper surface of the coating film by the first coating material. It is preferable not to employ a coating method.

  In particular, when the second paint 10 is applied by spraying as described above, the roughness of the formed coating film is further increased. This is because the volatilization amount of the solvent in the second paint 10 after the spraying of the second paint 10 and before reaching the upper surface of the coating film of the first paint increases. The second coating material 10 applied to the upper surface of the film is presumed to be because the shrinkage of the coating film in the second coating film 10 is increased due to the increase in the resin concentration.

Thus, although the spraying pressure in the case of spray-coating the second coating material 10 is appropriately adjusted, it is in the range of 4.9 × 10 ^{4 to} 3.9 × 10 ⁵ Pa (0.5 to 4.0 kgf / cm ² ). It is preferable that

  And after the 2nd coating material is apply | coated, the top coat film 4 is baked and hardened | cured by introducing the metal plate 1 into baking ovens 18, such as a hot air oven and a dielectric heating apparatus. The coating film made of one paint and the coating film made of the second paint are simultaneously heated and baked and cured. There is no particular limitation as to how long it takes to bake and harden after the formation of the coating film by the second paint 10, but it is preferably within 90 seconds. Moreover, the heating conditions for bake hardening are appropriately adjusted according to the composition of the first paint or the second paint 10, the thickness of the coating film, and the like. The heated metal plate 1 passes through the cooling device 19 and is cooled.

  The metal plate 1 on which the coating film is formed in this manner is wound around a winding roll 22 disposed on the terminal side of the process. Further, at the end of this step, the metal plate 1 can be cut and stacked along the width direction.

  Hereinafter, the present invention will be described in detail by way of examples.

(Examples 1-10, Comparative Examples 1-6)
As the metal plate 1, a long hot-dip galvanized steel sheet having a width of 1250 mm is used. While this coated galvanized steel sheet is continuously conveyed at a conveyance speed of 50 m / min in the longitudinal direction, pre-coating treatment, undercoating and overcoating are performed. By applying sequentially, a coated metal plate was obtained.

At this time, as a pre-coating treatment, a coating type chromate treatment (Cr adhesion amount 18.6 mg / m ² ) was performed.

  In addition, as the undercoat paint to be applied in the undercoat paint section 14, a polyester undercoat paint (manufactured by NOF BASF Coatings Co., Ltd., product number “FX-39P”) is used, and the thickness of the undercoat paint film 5 is 5 μm on the upper surface side. The lower surface side was 3 μm. The baking conditions for the undercoat film 5 in the baking furnace 16 were a heating temperature of 210 ° C. and a heating time of 50 seconds.

  Further, as the first paint and the second paint, a polyester / melamine paint (ordinary paint) shown in Table 1 below, or a shrink paint obtained by adding a curing catalyst blocked with an amine to a polyester / isocyanate paint, is used. The viscosity of each paint was adjusted by adding a solvent. And about each Example and the comparative example, formation of the coating film was performed on the conditions shown in Table 2,3. At this time, the interval between the application of the first paint and the application of the second paint was 5 seconds, and the interval between the application of the paint and the start of baking hardening was 5 seconds.

(Surface roughness measurement)
About the coating film in the coated aluminum-zinc alloy plated steel sheet of each Example and a comparative example, ten-point average roughness Rzjis82 was measured using the roughness measuring apparatus "Handy Surf E-35A" by Tokyo Seimitsu Kogyo Co., Ltd.

(Workability test)
The coated aluminum-zinc alloy-plated steel sheet of each Example and Comparative Example was placed in a room at 20 ° C. or 5 ° C. for 1 hour, then bent 180 degrees with the coated surface outside, and an adhesive tape was attached to the bent portion. The T number at which peeling of the coating film does not occur when peeled off later was measured. The T number is 0T when 180 ° bending is performed without sandwiching anything inside the bent portion, and 1T when 2 sheets are bent with the same thickness as the coated aluminum-zinc alloy plated steel sheet. The case where 2 sheets, 3 sheets, and 4 sheets are sandwiched is represented as 2T, 3T, and 4T, respectively.

(Impact measurement)
About the coated aluminum-zinc alloy plated steel plate of each Example and a comparative example, the impact strength was measured by the DuPont-type impact test based on JISK5400.55.3: 1990. At this time, the height at which the weight was dropped was changed in the range of 0 to 50 cm, and the presence or absence of peeling of the coating film after the weight was dropped was confirmed. In the following evaluation, the denominator has a weight

The change range of the height is 50 (cm), and the molecule indicates the maximum height (cm) of the weight when no peeling of the coating film occurs after the weight is dropped.

(Pencil hardness measurement)
About each Example and the comparative example, the hardness of the coating film was calculated | required based on JISK5400: 1990.

  These results are shown together in Tables 2 and 3.

It is a schematic process drawing which shows an example of embodiment of this invention.

Explanation of symbols

1 Metal plate 10 Second paint

Claims (4)

  Applying a first paint on the surface of the metal plate, and further applying a second paint before forming the first paint, and then heating and forming the first and second paints, A method for producing a coated metal plate, wherein at least a second paint of the paint is a shrink paint.   The method for producing a coated metal plate according to claim 1, wherein the first paint is a shrink paint.   The method for producing a coated metal sheet according to claim 1 or 2, wherein the shrink paint is a polyester / melamine paint added with a curing catalyst blocked with amines.   The ten-point average roughness Rzjis82 of the surface of the coating film produced by heating and forming the first coating material and the second coating material by the method according to claim 1 to 55 is 55 μm or more. Characteristic painted metal plate.

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