JP2005212446A - Manufacturing process for metal resin composite board having photocatalytic function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient manufacturing process for a metal resin composite board having photocatalytic function excellent in stainproof property, durability and surface design. <P>SOLUTION: The manufacturing process for the metal resin composite board having photocatalytic function comprises transferring a transfer film in which a photocatalyst layer and a protective layer are consecutively laminated on the surface of a releasable film onto (1) a metal plate having an organic coating film on the surface and bonding a metal plate on the back side of the metal plate via a resin sheet or (2) the coated surface of the metal resin composite board constituted of metal/resin/metal layers with an organic coating film on the surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a metal resin composite plate having a photocatalytic function. In particular, the present invention relates to a method for producing a metal resin composite plate having a photocatalytic function that allows a thin film of a photocatalyst to be uniformly laminated on a metal resin composite plate having a large area.

A photocatalyst such as titanium oxide decomposes an organic substance and develops a hydrophilic function when irradiated with ultraviolet rays. By laminating a photocatalyst on the surface of a substrate, it is being used for various applications such as antifouling, antifogging, deodorizing, and air purification.
On the other hand, the metal resin composite plate constructed by bonding both sides of the resin layer with a metal plate is superior in mechanical strength and has advantages such as lightness, surface smoothness, and large area. Widely used in the field of building materials and civil engineering. It is extremely useful to provide an antifouling function in the metal resin composite slope used for these applications, and in recent years, application of the above-mentioned photocatalyst has been studied as one of the promising methods.

  Patent Document 1 discloses a metal resin composite in which a metal layer is formed on the surface of a synthetic resin base material, and a photocatalyst layer made of titanium oxide is formed on the metal layer via a protective layer such as an organic paint. A board has been proposed. However, Patent Document 1 only exemplifies methods such as a thermal spraying method and a spraying method as a method for forming a photocatalyst layer. In these methods, a metal resin composite plate having a photocatalyst layer with good quality is disclosed. Cannot be produced efficiently and continuously.

  Patent Document 2 describes a method in which a photocatalyst layer and an adhesive layer are applied to a release film and then transferred to a base material such as a synthetic resin. According to this method, it is considered possible to efficiently produce a metal resin composite plate having a photocatalyst layer. However, Patent Document 2 considers the problem that, in this method, the adhesive layer is selected mainly from the adhesiveness to the synthetic resin base material, and the photocatalyst decomposes the organic layer of the base resin or the adhesive. It has not been.

JP-A-9-174744 JP 2002-316380 A

  An object of the present invention is to solve the above-mentioned problems and to provide a method for producing a metal resin laminated plate on which a photocatalyst is laminated, which can be painted in a factory and has excellent productivity.

  As a result of diligent research to solve the above problems, the present inventor has reached the present invention. That is, the present invention transfers a transfer film in which a photocatalyst layer and a protective layer are sequentially laminated on the surface of a peelable film to 1) a transfer onto a metal plate having an organic coating on the surface, and a resin on the back side of the metal plate. It is characterized by sticking a metal plate through a sheet, or 2) transferring to a coating surface of a metal resin composite plate having a metal / resin / metal layer structure having an organic coating film on the surface. The present invention resides in a method for producing a metal resin composite plate having a photocatalytic function.

  According to the method of the present invention, a metal resin composite plate having a photocatalytic function excellent in antifouling property, durability, and surface design can be produced. This method is a transfer method and is excellent in mass productivity.

Hereinafter, the present invention will be described in detail. In addition, the following description is an example (representative example) of the embodiment of this invention, and is not specified by these content.
The basic layer structure of the metal resin composite plate produced in the present invention is “photocatalyst layer / protective layer / organic coating / metal plate / resin layer / metal layer”. As the metal plate here, for example, a plate (sheet) made of a metal such as aluminum, stainless steel, iron, copper, titanium, tin, nickel or various alloys is used. However, workability, heat transfer, rigidity, etc. In general, an aluminum plate is particularly preferable. In addition, the metal surface may be previously subjected to polishing treatment, degreasing treatment, plating treatment, etching treatment, or the like as necessary for the purpose of improving the adhesion with other layers.

  Examples of the raw material for the resin layer include polyolefin resin, polystyrene resin, vinyl chloride resin, phenol resin, urethane resin, and the like, and polyolefin resin is preferable. In general, in order to impart flame retardancy, an inorganic filler such as magnesium, calcium, barium or aluminum oxide, hydroxide, silicate, carbonate or sulfate is usually contained in an amount of 10 to 80% by weight. Can be made.

Further, the resin layer is not limited to a single layer, and a three-layer structure in which a thin resin film layer having adhesiveness is laminated on both surfaces of a thick core resin sheet that forms the center is usually used. As the adhesive film, a thermoplastic resin film having affinity for both the core resin sheet and the metal plate is used. Specific examples of thermoplastic resins include ethylene / acrylic acid copolymers, ethylene / vinyl acetate copolymers, ethylene / glycidyl acrylate copolymers, ethylene / maleic anhydride copolymers, and polyethylene acrylic acid graft copolymers. And a maleic anhydride graft copolymer of polyethylene.
Furthermore, the core resin sheet portion may also be composed of a laminated sheet made of about 2 to 5 kinds of resins.

  In a general metal resin composite plate, a coating film made of an organic paint is often formed on the surface of at least one metal plate of the composite plate from the standpoint of maintaining and improving design properties and corrosion resistance. Examples of the organic paint here include fluorine resins, acrylic resins, polyester resins, polyurethane resins, and the like, and fluorine resins are particularly preferable.

  The thickness of the metal resin composite plate is usually about 0.5 to 6.0 mm, preferably about 0.7 to 5.0 mm, and the resin layer usually occupies 60 to 90% of the thickness. Generally speaking, by increasing the thickness of the core resin sheet in the composite plate, the rigidity can be increased without sacrificing the lightness. The thicknesses of the back and front metal plates are each 0.1 to 2 mm, preferably 0.2 to 1 mm, and the thickness ratio on the front and back is preferably in the range of 0.8 to 1.2, Usually the same thickness is most preferred.

The metal resin composite plate produced in the present invention has a structure in which a thin photocatalyst layer is laminated on the metal resin composite plate having the above-described general configuration, and the production method thereof includes a photocatalyst layer on the surface of the peelable film, A transfer film in which protective layers are sequentially laminated is used.
As this transfer film, a synthetic resin film made of polyester, polyolefin, polyimide, or the like and a release agent such as a silicon-based resin or a melamine-based resin is preferably used. The thickness of the peelable film is usually about 20 to 100 μm, and if it is too thin, the transfer strength at the time of transfer is not sufficient, and if it is too thick, there is a problem that it tends to wrinkle at the time of transfer. Further, in order to improve transferability to an organic coating film and releasability, it is also effective to add an inorganic fine particle to the release agent to make it matte.

  On the above peelable film, a photocatalyst layer is usually formed by applying and drying a liquid containing photocatalyst fine particles. As the photocatalyst, there are metal oxides such as titanium dioxide, zinc oxide, and tin oxide, and therefore, titanium dioxide that is chemically stable and relatively inexpensive is preferable. The particle size of the photocatalyst fine particles is usually about 0.001 to 0.1 μm. Photocatalyst coating liquids can be broadly classified into two types: paint types and sol-gel types. In order not to impair the surface design of the metal-resin composite plate, the sol-gel method that can form a transparent film is particularly preferable. desirable.

  That is, the paint-type photocatalyst is a combination of photocatalyst fine particles and silicone as a binder component, and can maintain hydrophilicity by utilizing the water retention property of the binder component and can be made thicker. There is a problem that it is easily opaque. On the other hand, a sol-gel type photocatalyst is, for example, a metal produced by a sol-gel method in which titanium compound such as titanium alkoxide is hydrolyzed under the catalyst as a raw material, and is further calcined and crystallized titanium oxide. An oxide catalyst is used. In the sol-gel type, since a binder component is usually unnecessary, there is a tendency that the organic substance decomposition performance as a function of the photocatalyst is high and the transparency of the film is high. The film thickness is usually about 0.05 to 1 μm. If the thickness is too thin, the function is difficult to be exhibited, and if it is too thick, cracks are likely to occur in the film, and interference fringes called irises are generated, which may impair the appearance.

  A protective layer is further provided on the photocatalyst layer. The protective layer has a function of blocking the photocatalyst layer and the organic coating film in order to prevent decomposition of the organic coating film due to the photocatalytic action, and has a function of adhering both through the protective layer. is there. The type of the protective layer is not particularly limited as long as it has such a function, but inorganic fine particles having a particle size of usually about 0.001 to 0.1 μm are preferably used. Examples of the inorganic fine particles include zirconia, silica, and amorphous titanium oxide (can be used as a protective layer in a normal environment because it is transferred to anatase-type titanium oxide that exhibits a photocatalytic function at 300 ° C. or higher). . Further, as the protective layer, in addition to the above inorganic fine particles, an organic-inorganic hybrid gradient material (an organic layer is formed on the organic coating layer side and an inorganic layer is formed on the photocatalyst layer side) is also used. be able to.

  Examples of the coating method of the photocatalyst layer and the protective layer include a method using a roll coater, a gravure coater, and a die coater. The coating solution for the photocatalyst layer and the protective adhesive layer is in a state in which fine particles are dispersed in water or an organic solvent, and the solid content concentration is usually only about several percent from the storage stability, so the viscosity of the coating solution is also several centipoise. It is low. Moreover, the coating film formed from this coating liquid as mentioned above needs to make film thickness into 0.05-1 micrometer normally, and the method by a gravure coater is especially suitable as a coating method.

  The transfer film in which the photocatalyst layer and the protective layer are sequentially laminated on the surface of the above-described peelable film is suitable as a method for continuously laminating the photocatalytic thin film on the metal resin composite plate having a large area. ) Transferring the transfer film to a metal plate having an organic coating film on the surface, and then bonding the metal plate to the back surface of the metal plate via a resin sheet, or 2) Applying the transfer film to the surface with an organic coating And a method of transferring to a coating film surface of a metal / resin composite plate having a metal / resin / metal layer structure.

  In the first aspect, as the transfer step, for example, an organic coating film is applied to a coiled metal plate, and after drying and curing, the protective surface of the transfer film and the coating surface of the metal plate are heated and pressurized. After the rolls are continuously bonded, the peelable sheet is peeled off. Next, the metal plate to which the photocatalyst has been transferred is used with the same heating / pressurizing roll as the equipment for producing the metal resin composite plate having the usual structure of “(organic coating film) / metal / resin / metal”. Thus, a resin-metal composite plate having a photocatalytic function, which is the final product, is obtained by continuously bonding the resin and the metal plate together.

  In the second aspect, as the transfer step, for example, an organic coating film is applied to a coiled metal plate, and after drying and curing, the protective surface of the transfer film and the already manufactured “organic coating film / metal” After the heating / pressurizing roll is continuously bonded to the coating surface of the metal resin composite plate having the structure of “/ resin / metal”, the release sheet is peeled off. Next, the metal plate to which the photocatalyst has been transferred is used with the same heating / pressurizing roll as the equipment for producing the metal resin composite plate having the usual structure of “(organic coating film) / metal / resin / metal”. Thus, a resin-metal composite plate having a photocatalytic function, which is the final product, is obtained by continuously bonding the resin and the metal plate together.

In the above, the optimum conditions for transferring the protective layer and the photocatalyst layer to the organic coating film with a heating / pressurizing roll depend on the type of the organic coating film, but usually the temperature is 60 to 180 ° C. and the pressure is ² to 20 kg / cm ² . If the temperature is too low, the transfer is insufficient. On the other hand, if the temperature is too high, the base resin of the transfer film is thermally deteriorated, and there is a possibility of causing a problem of tearing at the time of peeling. If the pressure is too low, the transfer is insufficient. On the other hand, if the pressure is too high, the equipment capacity is excessive, which is unnecessary.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to the following description examples, unless the meaning is exceeded.
1. Materials used Metal coil: An aluminum coil having a thickness of 0.5 mm was used.
Resin and inorganic filler: Low density polyethylene LF542M (Mitsubishi Chemical Corporation) was mixed with aluminum hydroxide (Alcoa Chemical Co., Ltd.) at a weight ratio of 65% and used.
Adhesive film: An ethylene acrylic acid copolymer film having a thickness of 40 μm was used.
Fluororesin paint: Solvent-soluble fluororesin paint Lumiflon (Asahi Glass Coat and Resin Co., Ltd.) was used.
Peeling film: A 50-μm thick polyester film coated with a melamine release agent to which silica fine particles were added as a release agent was used.
Coating solution for protective layer: A coating solution (solid content concentration 2%, viscosity 3 centipoise) in which zirconium fine particles (average primary particle size: about 8 nm) produced by the sol-gel method were dispersed in isopropanol was used.
Photocatalyst layer coating solution: A coating solution (solid content concentration 2%, viscosity 3 centipoise) obtained by dispersing anatase-type titanium oxide fine particles produced by a sol-gel method in isopropanol was used.

2. Manufacture of Coiled Metal Plate After washing the aluminum coil with water, the oil adhering during rolling was removed by immersion in a degreasing solution, further washed with hot water, and then dried. The surface to be bonded to the resin sheet was surface-treated with a coating type chromium chromate solution, and then the adhesive film was thermally welded at 200 ° C. with a hot roll.
A fluororesin paint was applied to the surface of the aluminum coil opposite to the above with a die coater so as to have a coating thickness of 20 μm, and then heated at 230 ° C. for 1 minute.

3. Production of Transfer Film A release film was coated with a gravure coater in the order of a photocatalyst layer coating solution and a protective layer coating solution in the order of 0.1 μm, and then heated at 80 ° C. for 1 minute.
4). Transfer to the fluororesin coating film Apply the fluororesin coating on the coated coiled metal plate prepared in the above item ² using the thermal transfer roll at the temperature of 150 ° C. and the pressure of 5 kg / cm ² using the thermal transfer roll. The protective layer and the photocatalyst layer were transferred to the film.

5). Manufacture of metal resin composite plate Using a raw material supply feeder, low density polyethylene and aluminum hydroxide are supplied to the biaxial kneader in the above-described proportions, melt kneaded with an extruder, and extruded into a sheet having a thickness of 3.0 mm. did. Next, on both sides of the obtained sheet, an aluminum coil having a thickness of 0.5 mm, in which an adhesive film is heat-sealed on one side, a fluororesin paint is applied on the opposite side, and the adhesive layer and the photocatalyst layer are transferred. And a metal-resin composite plate having a total thickness of 4.0 mm was manufactured using a pressure bonding roll having a surface temperature set to 180 ° C.
Moreover, the metal resin composite board manufactured by the method similar to an Example was prepared as a comparative example except not having performed transfer of the protective adhesive layer and the photocatalyst layer.

6). Evaluation Table 1 below shows the results of the transfer rate, the contact angle with water, and the outdoor exposure test (one year) for the metal resin composite plate produced above. From Table 1, in the metal resin composite board manufactured in the Example, it was confirmed that the photocatalyst was completely transferred and that the antifouling property, durability, and surface design were excellent. When the contact angle of water on the surface is small, the hydrophilicity is high, indicating that dirt adhering to the surface can be efficiently removed with rainwater.
In addition, since it is difficult to measure the film thickness of the protective layer and the photocatalyst layer as a measurement of the transfer rate, the intensity of trace amounts of Zr and Ti elements on the transfer film and the surface of the coated coil after transfer is determined by fluorescent X-ray analysis. The transfer rate was determined from the following calculation formula.
Transfer rate (%) = [(Fluorescent X-ray intensity (Kcps) on coated coil surface after transfer) / (Fluorescent X-ray intensity (Kcps)) on transfer film surface]] × 100

(Notes on Table 1)
1) Gloss retention rate 60 ° specular reflectance retention rate after outdoor exposure 2) Color difference Color difference before and after outdoor exposure JIS Z8730
3) Appearance (rain stains) Visual

Claims (4)

A transfer film in which a photocatalyst layer and a protective layer are sequentially laminated on the surface of the peelable film is transferred to a metal plate having an organic coating film on the surface, and further, a metal plate is placed on the back surface of the metal plate via a resin sheet. Or 2) a metal having a photocatalytic function, characterized in that it is transferred to the coating surface of a metal resin composite plate having a metal / resin / metal layer structure and having an organic coating film on the surface Manufacturing method of resin composite board. 2. The method for producing a metal resin composite plate according to claim 1, wherein the protective layer comprises inorganic fine particles. The method for producing a metal resin composite plate according to claim 1 or 2, wherein the photocatalyst is made of titanium oxide obtained by a sol-gel method. The metal having a photocatalytic function according to any one of claims 1 to 3, wherein a transfer film is transferred to a coating surface of a metal plate having an organic coating film under conditions of a temperature of 60 to 180 ° C and a pressure of ^{2 to 20} kg / cm2. Manufacturing method of resin composite board.