JPS6124180B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coated metal plate in which the metal plate is coated with a polyethylene terephthalate biaxially stretched film provided with a metal thin film layer. BACKGROUND OF THE INVENTION Conventionally, metal plates with smooth surfaces have been molded and used for construction materials, fixtures, ornaments, and other members with good surface smoothness. However, there is a drawback that the metal surface is easily scratched during molding. Therefore, various measures have been taken to prevent scratches. Of these, the most economically advantageous method is to use commonly used inexpensive metal plates such as chromium-treated steel plates, galvanized steel plates, and aluminum plates, instead of using expensive smooth-finished metal plates. This is a method of attaching a polyester film with a thin metal layer using an adhesive. In this method, the adhesive is a solvent type,
Emulsion type adhesives, polyolefin hot melt adhesives, etc. are used.
It has not yet achieved satisfactory performance and has the following drawbacks. (1) The bending and drawing properties are poor, and the coating layer on the processed parts peels off and floats off the metal plate. (2) The coating layer to be punched out stretches and protrudes from the punched part of the metal plate, making the punching process difficult. (3) Moisture resistance is poor, and the metal thin film layer disappears from the end surface of the coated metal plate. (4) Due to the smoothness of the metal plate, fine irregularities occur in the thin metal film layer, causing the mirror image to appear distorted when projected. Therefore, as a result of studying to improve the shortcomings of these conventional products, we found that all of these shortcomings could be overcome for the first time by a combination of providing a metal thin film layer on a specific polyester film and thermally bonding it to a metal plate via a specific high molecular weight thermoplastic resin. It was discovered that a coated metal plate with improved gloss and high gloss could be produced, and the present invention was achieved. That is, the coated metal plate of the present invention has a thickness of 25 to 250 mm.
A thin metal film layer is provided on one side of a polyethylene terephthalate biaxially stretched film (hereinafter abbreviated as PET-BO film) with a haze of 10% or less, and this metal thin film layer surface and the metal plate are exposed to high molecular weight heat with a melting point of 100 to 230°C. This is a coated metal plate that is thermally bonded via an adhesive layer with a thickness of 5 to 50 μm, the main component of which is one or more selected from plastic polyester and high molecular weight thermoplastic polyester ether with a melting point of 115 to 210°C. The PET-BO film used in the present invention has a thickness of 25
~250μ, preferably 30-100μ, and the haze is
It is essential that it be 10% or less, preferably 5% or less. PET-BO film containing various quality improvers such as colorants and UV absorbers can also be used. PET-BO film with a light hay line treatment can also be used as long as the haze is 10% or less. If the thickness of the PET-BO film is less than 25μ, the mirror image will be distorted, and if it exceeds 250μ, the bending workability and drawing workability will be poor. Haze again
If it exceeds 10%, the gloss will be lost. The metal forming the metal thin film layer is a metal capable of forming a mirror surface, such as aluminum, copper, zinc, gold, silver, platinum, chromium, nickel, tin, or cobalt. Among these, aluminum is preferred from the viewpoint of economy and brightness of the mirror surface. The thickness of the metal thin film layer is 200-2000 Å, preferably 400-1000 Å. The metal thin film layer is made by a known vacuum thin film forming method such as a vapor deposition method, an ion plating method, or a sputtering method. Among these, the vapor deposition method is preferred because it can greatly improve the moisture resistance of the coated metal plate. The thermoplastic polyester used in the present invention is
A high molecular weight substance with a molecular weight of 10,000 or more, preferably 15,000 or more, and a melting point of 100 to 230℃, preferably 105 to 220℃.
℃. Among such thermoplastic polyesters, thermoplastic polyesters in which 50 mol% or more of the diol component is ethylene glycol or butanediol and 50 mol% or more of the dicarboxylic acid component are terephthalic acid are particularly preferred. The thermoplastic polyester ether used in the present invention has a molecular weight of 10,000 or more, preferably 15,000 or more, and has a melting point of 115 to 210°C, preferably 125°C.
~190℃. Among thermoplastic polyester ethers,
Polybutylene terephthalate/isophthalate/
It is preferable to use polytetramethylene glycol copolymer (abbreviated as PBT/I-PTMG) or polybutylene terephthalate/polytetramethylene glycol copolymer (abbreviated as PBT-PTMG), and from the viewpoint of moisture resistance of the coated metal plate. PBT/I
-PTMG is particularly preferred. The adhesive layer in the present invention is a layer whose main component is one or more selected from the above thermoplastic polyesters and thermoplastic polyester ethers. Additionally, additives such as inorganic fine particles, adhesion promoters, and heat resistant agents can be added to the adhesive layer. When the molecular weight of these adhesive layer resins is less than 10,000, the molding processability such as bending, drawing, and punching and moisture resistance are slightly inferior. If the melting point of the adhesive layer resin is lower than a predetermined temperature, the distortion of the mirror image gradually increases. Moreover, if the temperature is too high than a predetermined temperature, the moisture resistance will not be sufficient. In the present invention, thermal bonding via an adhesive layer is essential. If the thermal adhesion method is not used, that is, if the adhesive layer resin is dissolved in an organic solvent and then applied and bonded, the moisture resistance is poor and the image is likely to be distorted. The thermal bonding temperature in the present invention is 130 to 240°C, preferably 140 to 230°C. Further, the metal plate used in the present invention includes aluminum,
It is a plate-shaped material made of commonly known metals such as iron, copper, and various alloys. The surfaces of these metal plates are preferably subjected to various surface treatments such as rust prevention treatment, hardening treatment, adhesion promotion treatment, polishing, etc. in advance. The thickness of the metal plate used is 0.1 to 5 mm, preferably 0.2 to 2 mm.
It is. The coated metal plate of the present invention can be produced by the following methods, but is not limited to these methods. (1) Create a composite film by melt-extruding and laminating adhesive layer resin on the metal thin film layer of PET-BO film. A method in which this composite film and a preheated metal plate are bonded under pressure and heat using a press roll, passed through a heating oven as necessary, and then cooled with water. (2) A method in which a film is made by forming adhesive layer resin in advance, and the film is sandwiched between the metal thin film layer surface of the PET-BO film and a metal plate, and the film is bonded under pressure with a press roll. (3) A method in which the adhesive layer resin is directly melted and extruded between the metal thin film layer surface of the PET-BO film and the metal plate to integrate it, and if necessary, it is passed through a heating oven and then cooled. (4) After melting and extruding the adhesive layer resin onto the metal plate to create a composite of the metal plate adhesive layer, the adhesive layer surface is overlapped with the metal thin film layer surface of the PET-BO film, and heat bonding is performed using a press roll. How to integrate. In the present invention, method (1) is preferred from the viewpoint of productivity. In addition, 5 to 30 wt%, preferably 5 to 30 wt% of a polyethylene copolymer having a polar group is added to the adhesive layer resin of the present invention.
By dispersing and blending 10 to 25 wt%, a coated metal plate with even better moisture resistance and drawing workability can be produced. Polyethylene copolymers having such polar groups include ionomers, ethylene/vinyl acetate copolymers, ethylene/acrylic acid copolymers, ethylene/methyl acrylate copolymers, and polyethylene with unsaturated dicarboxylic acids such as maleic anhydride. Alternatively, copolymers obtained by graft polymerization of derivatives thereof can be mentioned. In addition, by providing a surface hardening layer, an antistatic layer, a colored layer, a printed layer such as a pattern on the surface of the PET-BO film of the coated metal plate of the present invention by a method such as coating, scratch resistance and dust It is possible to further improve adhesion prevention, design, etc. The present invention relates to a specific PET-BO having a metal thin film layer.
Since it is a coated metal plate made by thermally bonding a film and a metal plate via a special adhesive layer, it has the following excellent effects. (1) It has excellent forming processability in punching, bending, drawing, etc., and the coating layer does not peel or tear during these processes, and processes with a large degree of deformation can be performed. (2) It has excellent moisture resistance, and the metal thin film layer will not gradually disappear due to moisture. (3) High surface gloss and an excellent mirror surface that allows a clear image to be obtained when projected. Since the coated metal plate of the present invention has the above-mentioned effects, it can be used for exterior members of fixtures, decorative parts, and building materials such as wall materials and ceiling materials with design properties. The present invention will be specifically described below with reference to Examples. The physical properties were measured by the following methods. (1) Melting point The melting peak temperature measured using a differential calorimeter (DSC) on a 10 mg sample in a nitrogen atmosphere at a heating rate of 40°C/mm. If the DSC melting point was unclear, it was measured with a penetrometer. In this case, the sample is heated to 80℃ for 15 minutes.
After time heat treatment, 0.5mm diameter pin (load 5g)
The melting point is the temperature at which 250μ penetrates. (2) Haze Measured on one film according to JIS K-6714. (3) Distortion of mirror image A straight white round bar is projected onto a coated metal plate, and the image of the round bar appears to be ○ if it appears straight, △ if the image appears to be slightly distorted, and △ if the image appears to be distorted. ×, those that appear extremely distorted are marked as XX. (4) Punching workability A disk with a diameter of 12 cm is punched out from the coated metal plate, the punched surface is observed, and the punching workability is evaluated using the following criteria. ○: Has a clean punched surface. ×: The film peeled off or stretched and protruded from the punched surface. (5) Bending processability The coated metal plate is folded in close contact with the PET-BO film layer side facing outward. A cut reaching the surface of the metal plate is made in the bent part with a knife, the degree of adhesion of the metal coating layer is observed, and the decrease in adhesion due to the bending process is evaluated using the following criteria. 〇: No decrease in adhesion. △: Adhesion is slightly decreased. ×: Adhesion deteriorates and peels off. (6) Drawing workability A disk of coated metal plate punched out for punching workability evaluation was drawn with a die and a punch to a diameter of 6.7cm and a depth of 2.3cm.
A cup with a flange is made and its drawability is evaluated using the following criteria. ○: No defects such as peeling of the film are observed. △: Slight peeling is observed on the film at the flange and bottom corners. ×: The film peels off at the flange and bottom corners. (7) Moisture resistance A cross cut with a side length of 10 cm is placed on a 15 cm square coated metal plate and left in boiling water for 1 hour to perform an acceleration test. Observe the disappearance width of the metal thin film layer on the cross-cut surface. 〇: Disappearance width is less than 0.5mm. △: Disappearance width is 0.5 to 1.0 mm. ×: Disappearance width exceeds 1.0 mm. (8) Glossiness 60 degree specular glossiness was measured according to JIS Z8741. A material with a gloss level of 500 or higher is excellent as a mirror surface. Example 1 (1) Aluminum vapor-deposited PET-BO film Aluminum was vapor-deposited to a thickness of about 500 Å on PET-BO films having different thicknesses as shown in Table 1 by vapor deposition. (2) Melt extrusion laminate of adhesive layer resin The following two types of thermoplastic polyesters were prepared as adhesive layer resins. Polyester No. 1: Polybutylene terephthalate/isophthalate copolymer [copolymerization molar ratio: terephthalic acid/isophthalic acid 65/35, melting point 160°C,
Molecular weight 20,000 (terminal group method)]. Polyester No. 2: Terephthalic acid/isophthalic acid/adipic acid (copolymerization molar ratio: 70/10/20) as dicarboxylic acid components, butanediol/ethylene glycol (copolymerization molar ratio: 60/40) as diol components [ A polyester with a melting point of 140℃ and a molecular weight of 25,000 (vapor pressure method). This polyester No. 1 and No. 2 are mixed at a ratio of 30:70wt%, and a 40mm
Supplied to milli-extrusion laminator, extrusion temperature 250℃
It was extruded from the nozzle and laminated on the aluminum-deposited surface of the aluminum-deposited PET-BO film of (1) above using a nip roll. The thickness of the adhesive layer was 20μ. (3) Preparation of coated metal plate The chromium-treated steel plate with a thickness of 0.3 mm and the adhesive layer side of the composite film of (2) above were stacked and pressed with a press roll.
Pressure and heat bonding was carried out at 180°C and a linear pressure of 7 kg/cm. Next, this was completely thermally bonded in a heating oven at 200°C, and then cooled with water to produce a coated metal plate. (4) Performance evaluation

[Table] As shown in Table 1, samples Nos. 1 and 2 of the present invention had no image distortion and had good moisture resistance. On the other hand, No. 3
Since the PET-BO film was thin, the image was highly distorted and its moisture resistance was poor. Example 2 (1) Aluminum vapor-deposited PET-BO film Aluminum was vapor-deposited to a thickness of about 700 Å on a PET-BO film with a thickness of 38 and 50 μm shown in Table 2 by vapor deposition. (2) Melt extrusion laminate of adhesive layer resin Terephthalic acid/isophthalic acid (copolymerization molar ratio: 56/44) as the dicarboxylic acid component, and butanediol/ethylene glycol (copolymerization molar ratio: 68/32) as the diol component. 80wt% thermoplastic polyester [Polyester No. 3, melting point 114℃, molecular weight 23000 (vapor pressure method)] and ethylene.
Vinyl acetate copolymer (vinyl acetate content 14wt%,
Melt index 3.5g/10 minutes) was mixed with 20wt%, extruded in the same manner as in Example 1 at an extrusion temperature of 170°C, and laminated on the aluminum-deposited surface of an aluminum-deposited PET-BO film. The cast temperature was 40°C. (3) Preparation of coated metal plate A coated metal plate was prepared in the same manner as in Example 1 by stacking the adhesive layer surfaces of the various composite films prepared in (2) above on an aluminum plate having a thickness of 0.6 mm. (4) Performance evaluation As shown in Table 2 below, Experiment Nos. 4, 5,
6, there was no image distortion. Furthermore, since an ethylene/vinyl acetate copolymer was used in combination as the adhesive layer resin, it exhibited better punching workability, bending workability, drawing workability, and moisture resistance than polyester alone. On the other hand, No. 7, which had a thick adhesive layer, had large image distortion and poor punching, bending, and drawing properties.

[Table] Example 3 (1) Aluminum evaporated PET-BO film As shown in Table 3, the haze was changed to wide width.
A vapor-deposited film was made by depositing approximately 800 Å of aluminum onto a PET-BO film using the vapor deposition method. (2) Melt extrusion laminate of adhesive layer resin Thermoplastic polyester ether PBT/I-PTMG [terephthalic acid/isophthalic acid (copolymerization molar ratio: 70/30), copolymerization amount of polytetramethylene glycol 50wt% as adhesive layer resin , melting point 155℃,
Molecular weight approximately 25,000 (GPC method)] and ethylene/acrylic acid copolymer (acrylic acid content 8wt%, melt/
index 2g/10 minutes) and 90wt%
(former):10 wt% (latter), extruded in the same manner as in Example 1 at an extrusion temperature of 220°C, and laminated on the aluminum-deposited surface of an aluminum-deposited PET-BO film. The thickness of the adhesive layer was 20μ. (3) Preparation of coated metal plate A coated metal plate was prepared in the same manner as in Example 1 by stacking the adhesive layer surfaces of the various composite films prepared in (2) above on an aluminum plate having a thickness of 0.4 mm. (4) Performance evaluation As shown in Table 3, Nos. 8 and 9 of the present invention had no image distortion, high gloss, and good punching workability and drawing workability. On the other hand, the haze value is large
No. 10, which used PET-BO film, had a cloudy mirror surface, was unable to obtain a clear image, and had low gloss.

[Table] Comparative Example 1 The following low molecular weight thermoplastic polyester was prepared as the adhesive layer resin. Terephthalic acid/isophthalic acid (copolymerization molar ratio: 50/
50) and ethylene glycol/neopentyl glycol (copolymerization molar ratio:
55/45) [melting point 115℃,
Molecular weight 3000 (vapor pressure method)]. This polyester was dissolved in ethyl acetate and coated on the vapor deposited layer surface of the aluminum vapor deposited PET-BO film used in No. 6 of Example 2, and the solvent was evaporated at 60° C. to leave it half-dried. The 0.6 mm thick galvanized steel plate used in Example 2 was coated with the above adhesive and left to dry, then the coated surfaces of both were brought together using a press roll and laminated with a linear pressure of 5 kg/cm to form a coated metal plate. (experiment
No. 11) was created. The adhesive layer thickness of this product was 4μ. As a result of evaluating this coated metal plate in the same manner as in Example 2, the overall evaluation was × for mirror image distortion ×, punching workability ×, bending workability ×, drawing workability ×, and moisture resistance △ to ×. . Thus, it was found that using low molecular weight polyester and using conventional solvent-based adhesive methods, it was not possible to obtain a coated metal plate that would be of practical use. Example 4 (1) Aluminum vapor-deposited PET-BO film One side of a PET-BO film with a thickness of 38 μm and a haze of 0.3% was subjected to a light hair line treatment with vertical streaks to produce a film with a haze of 2.5%. Next, aluminum was deposited to a thickness of about 700 Å on the surface without the hair line processing using a vapor deposition method. (2) Melt-extrusion laminate of adhesive layer resin The adhesive layer resin of Example 2 was laminated to a thickness of 20 μm on an aluminum vapor-deposited surface in the same manner. (3) Preparation of coated metal plate Example 1 using a galvanized steel plate with a thickness of 0.5 mm
A coated metal plate (No. 10) was made in the same manner as above. (4) Performance evaluation The product of the present invention has good punching workability, bending workability, drawing workability, and moisture resistance (all ○), and the surface has a light hairline finish, so it is better than a polished aluminum plate. It gave a natural feel, had an excellent gloss level of 600, and was rich in design.

Claims (1)

[Claims] 1. A thin metal film layer is provided on one side of a polyethylene terephthalate biaxially stretched film with a thickness of 25 to 250 μm and a haze of 10% or less, and the metal thin film layer surface and the metal plate are made of high molecular weight thermoplastic polyester with a melting point of 100 to 230°C,
A coated metal plate formed by thermally adhering via an adhesive layer with a thickness of 5 to 50 μm, the main component of which is one or more selected from high molecular weight thermoplastic polyester ethers with a melting point of 115 to 210°C.