JP2000272048A - Thermoplastic resin-coated metal plate having mat surface and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mat appearance in a surface without adding a matting agent by forming the mat surface within a specific range of Ra of surface roughness of a thermoplastic resin layer. SOLUTION: A film thickness of a thermoplastic resin is set to 9 to 11 μm, and a surface roughness or an appearance is evaluated. A thermoplastic resin surface obtains a mat appearance, and a crack of a processed portion after a bending test is not recognized. The roughness of the thermoplastic resin film is all in a range of 0.2 to 5 μm. In the case of using a pressing roll having R of the roughness of 0.162 μm, a resin surface of a manufactured thermoplastic resin-coated metal plate has a gloss and cannot obtain a mat appearance. In the case of using a pressing roll having Ra of 7.33 μm, it is impossible in either case to manufacture a thermoplastic resin-coated metal plate attached to the roll. When the Ra of the roll is deviated from a fine protrusion and recess shape of 0.2 to 5 μm, a thermoplastic resin-coated metal plate having a good mat surface is scarcely obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated metal plate which is used after being processed into a building material, an electric component exterior material, a container material, and the like in which appearance quality is important, and more particularly, to a resin-coated surface. Relates to a metal plate coated with a thermoplastic resin having a matte surface.

[0002]

2. Description of the Related Art Metal materials such as steel and aluminum have excellent formability and high mechanical properties as compared with ceramic materials and polymer materials, and are therefore used in building materials, transportation equipment, electric parts materials, container materials, etc. , Is used as a structural material in a wide range of fields. In use, in order to protect the metal material from its weak point of corrosion and maintain its initial performance over a long period of time, and to impart surface quality such as various colors and glossiness, the surface of the metal material is usually used. A resin coating is often applied.

A method of forming a resin film on a metal plate includes a pre-coat method in which a resin film is formed in advance on a metal plate before processing, and an after-coat method in which a resin film is formed on each part after processing. However, the latter has many disadvantages in terms of productivity, so it is limited to cases involving complicated shape processing and cases where the working environment of the processing degree is particularly severe, and the ratio of the highly productive precoat method is increasing. is there.

[0004] As a typical example of a precoating method for a metal plate, a roll coating method in which a paint is applied by a roll is known. In the roll coating method, epoxy resin,
Dissolve polyester resin, urethane resin, etc. in organic solvent,
Alternatively, a dispersed organic solvent type paint or an aqueous paint obtained by modifying the surface of an epoxy resin or the like with an acrylic resin having a high hydrophilicity and dispersing it in water is used. All of these paints are liquid at room temperature, are supplied to a coater pan by a pump, and are then transferred to a metal plate by two or three painting rolls. The paint transferred to the surface of the metal plate is cured while passing through the baking furnace to form a resin film.

[0005] In order to secure stable paintability by the above-mentioned roll coating method, the viscosity range of the paint is usually 0.1 to
A paint of 10 poise is required, but when such a low-viscosity paint is used, the paint transferred to the metal plate by the coating roll flows and spreads until it is baked and hardened, and the surface is smoothed. Therefore, the appearance of the resin film obtained by the roll coating method generally tends to be a glossy surface.

Therefore, as a method of obtaining a matte appearance by a roll coating method, a method of adding a matting agent to paint has been adopted. As the matting agent, inorganic fine particles and organic fine particles are generally used, and examples of the inorganic fine particles include silica fine particles, alumina fine particles, calcium carbonate fine particles, and the like.
As organic fine particles, polyethylene resin, epoxy resin,
Beads such as polyester resin and polyurethane resin are often used. For example, Japanese Patent Publication No. 6-900 discloses an organic fine particle having an average particle size of 15 to 80 μm and an inorganic coating surface modifier having an average particle size of 1/3 or less of the average particle size of the organic fine particle in the coating film. The technology used by blending is disclosed in
Japanese Patent Application Laid-Open No. 9-24339 discloses a technique in which precipitated silica having a particle size of 1 to 7 μm is added to a coating film. Are respectively disclosed.

[0007]

However, when roll coating is performed using a paint to which a matting agent is added,
There are the following problems. That is, the viscosity of the organic solvent-based paint or water-based paint used in the roll coating method is generally
It is as low as 0.1 to 10 poise. When a matting agent is added to such a paint, if the specific gravity of the matting agent is greater than the specific gravity of the paint, the matting agent will precipitate, and if the specific gravity of the matting agent is small, the matting agent will float on the paint surface. In either case, it is difficult to uniformly disperse the matting agent in the coating film.

There is also a problem that the addition of a matting agent increases the viscosity of the coating material itself, thereby deteriorating the coatability by the roll coating method. Further, in order to make full use of such a coating material, it is necessary to reduce the coating speed, so that there is a problem that productivity is greatly impaired.

Further, as described above, when the amount of the matting agent added is high, the elongation of the coating film itself becomes small. Therefore, when the completed metal plate is used after being bent or drawn, the coating of the processed portion is not performed. Problems such as cracking and peeling of the coating film easily occur in the film.

The present invention has been made in view of the above-mentioned problems, and has as its object to reduce the workability and adhesion of a resin film formed on the surface of a metal plate, as well as the paintability and productivity. An object of the present invention is to provide a metal plate coated with a resin film having a matte appearance without adding a matting agent which causes the problem, and a method for producing the same.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the extruder has been manufactured without adding an additive for matting to the resin layer. A thermoplastic resin having a matte surface by extruding a thermoplastic resin having a limited melt viscosity onto the surface of a metal plate using a pressure-sensitive adhesive roll formed with fine irregularities and cooling and solidifying the resin. The present invention has been achieved by focusing on obtaining a coated metal plate. That is, the gist configuration of the present invention is as follows.

According to a first aspect of the present invention, in a metal plate coated with a thermoplastic resin, the surface roughness of the thermoplastic resin layer is reduced.
A thermoplastic resin-coated metal sheet having a matte surface, which is formed on a matte surface of 0.2 to 5 μm with Ra.

The invention of claim 2 is characterized in that the thermoplastic resin layer contains no matting additive having an average particle size of 0.2 μm or more, or contains no additive having an average particle size of 0.2 μm or more. A thermoplastic resin-coated metal sheet having a matte surface according to claim 1.

According to a third aspect of the present invention, there is provided a step of preheating a metal plate, a step of extruding a thermoplastic resin which is heated and melted on the surface of the metal plate, and a step of forming a fine irregular shape on the surface and cooling it. A method for producing a thermoplastic resin-coated metal plate having a matte surface, comprising a step of cooling and solidifying while pressing a thermoplastic resin extruded by a roll onto a metal plate.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a metal sheet coated with a thermoplastic resin having a matte surface according to the third aspect, wherein the surface roughness of the pressure roll is 0.2 to 5 μm. Method.

According to a fifth aspect of the present invention, the thermoplastic resin extruded in the extrusion step has a melt viscosity of 100 to 100,000 poise. Method.

[0017] The invention of claim 6 aims at matting the thermoplastic resin extruded in the extrusion step to have a melt viscosity of 100 to 100,000 poise and an average particle size of 0.2 µm or more in the thermoplastic resin. The method for producing a thermoplastic resin-coated metal sheet having a matte surface according to claim 3 or 4, wherein the method does not include an additive.

According to a seventh aspect of the present invention, the thermoplastic resin extruded in the extrusion step has a melt viscosity of 100 to 100,000 poise and contains no additive having an average particle size of 0.2 μm or more. The method for producing a thermoplastic resin-coated metal sheet having a matte surface according to claim 3 or 4. Hereinafter, the configuration and operation of the present invention will be described in detail.

For the resin coating of the resin-coated metal plate having a matte surface provided by the present invention, a thermoplastic resin is used instead of the paint used in the roll coating method.
The metal plate covered with the resin film is formed by a melt extrusion lamination method as shown in FIG. The outline of the molding procedure of the thermoplastic resin-coated metal plate (hereinafter, also referred to as a resin-coated metal plate) will be described with reference to FIG. First, a thermoplastic resin pellet 1 is extruded from a hopper 2 into an extruder 3.
After being melted, kneaded and pressurized in the extruder 3 and extruded as a thermoplastic resin sheet 5 from the extrusion die 4, the metal plate 6 is heated through a preheater 7, and then the extruded thermoplastic resin is heated. The resin sheet 5 and the heated metal plate 6 are laminated, passed through a cooled pressure roll 8, and cooled and solidified while pressing the thermoplastic resin sheet 5 against the metal plate 6 by the pressure roll 8 to form a resin-coated metal plate 9. It is to be molded. By forming fine irregularities on the surface of the pressing roll 8A on the side of the thermoplastic resin sheet 5 in the pressing roll 8, the resin-coated metal plate 9 having a matte surface provided by the present invention can be formed. It is obtained. Although not shown, the pressure roller 8 is supplied and drained through a shaft and is internally water-cooled.

The surface of the resin coating of the thermoplastic resin-coated metal plate 9 obtained above is matted by transferring and forming the fine irregularities of the surface of the pressing roll 8A, and the mat is formed in the resin coating layer. A sufficient matte state can be obtained without adding an additive aimed at. Therefore, an additive for matting as used in the roll coating method is not necessarily required, but bending or drawing of a resin-coated metal plate caused by adding an additive for matting is performed. Defects in coating performance such as cracking and peeling of resin coating during processing, appearance defects due to poor dispersion of additives in paint, and paintability and productivity due to increased viscosity of paint Addition within a range that does not cause a problem such as a decrease does not matter at all, and a coloring agent, ultraviolet absorption, which has been added so far to satisfy the characteristics required according to the use of the resin-coated metal plate, etc. As for auxiliary materials such as an agent, an antioxidant, a lubricant, a stabilizer, a flame retardant, and an antistatic agent, there is no problem in adding them in a range that does not cause the above-mentioned problems.

As described above, in the thermoplastic resin-coated metal sheet according to the present invention, the thermoplastic resin layer does not contain any matting additive having an average particle diameter of 0.2 μm or more. Desirably, more preferably the average particle size
It is desirable not to contain any additive of 0.2 μm or more.
That is, when an additive having an average particle size of 0.2 μm or more is contained in the thermoplastic resin layer, there is a concern that the above-described problems may occur. This is because, when silica particles or the like are added, cracks are observed in the bending process of the resin-coated metal plate as described in Examples below.

The type of metal plate used in the present invention is not particularly limited, but a steel plate, an iron plate, a stainless plate, an aluminum plate, an aluminum alloy plate, a copper plate and the like can be suitably used. The thickness, temper and the like of these metal plates are not particularly limited, and they can be suitably used from a foil having a thickness of about 10 μm to a thick plate having a thickness of about 3 mm. The surface treatment of the metal plate is not particularly limited, either.
As for the steel sheet, a plated steel sheet or a chromate-treated steel sheet is preferably used, and as the aluminum plate and the aluminum alloy sheet, a surface-treated plate which has been subjected to a phosphoric acid chromate treatment, a coating type chromate treatment, an alumite (anodized film) treatment, etc. is preferably used. You.

The melt viscosity of the thermoplastic resin used in the production of the thermoplastic resin-coated metal sheet according to the present invention is desirably 100 to 100,000 poise. This melt viscosity is extremely high as compared with the viscosity of the paint used in the roll coating method of 0.1 to 10 poise. To achieve such a high viscosity, when the thermoplastic resin in a molten state is pressed against a metal plate using a cooled roll having fine irregularities on the surface,
A metal plate with a matte appearance resin coating in which the fine irregularities formed on the roll surface are transferred to the resin coating surface, and the transferred fine irregularities hardly flow and become smooth like paint. Is obtained.

The thermoplastic resin used in the present invention is not particularly limited as long as it has a melt viscosity of 100 to 100,000 poise, but is not limited to polyethylene, polypropylene, polystyrene, AS resin, ABS resin.
Resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, nylon 6, nylon 66,
Nylon MXD6, polyimide, polycarbonate, polyacetal, polyphenylene sulfide, polyphenylene oxide, fluorine resin and the like are preferably used.
In addition, copolymers, polymer blends, and polymer alloys of these resins can be used without any particular limitation.

In the production of the thermoplastic resin-coated metal sheet according to the present invention, the surface roughness of a pressure roll for pressing the thermoplastic resin, which has been heated and melted to a melting point or higher, onto the metal sheet, and the thermoplastic resin layer coated on the metal sheet, Surface roughness 0.2 to 5μm in Ra
However, if the surface roughness of the pressure roll is less than 0.2 μm in Ra, the surface roughness of the thermoplastic resin layer of the finished metal plate will be less than 0.2 μm in Ra. The reason for this is that the surface is too glossy and cannot be called a matte surface. Also, when the surface roughness of the pressure-bonding roll exceeds 5 μm in Ra, a part of the molten thermoplastic resin adheres to the fine irregularities of the pressure-bonding roll. Since it is not possible to manufacture a matte surface with a surface roughness exceeding 5 μm in Ra, the upper limit of the surface roughness of the pressure roll and the surface roughness of the thermoplastic resin layer is limited.
Ra is set to 5 μm or less.

Further, in the production method of the present invention, the melt viscosity of the thermoplastic resin is set to 100 to 100,000 poise in order to obtain the effect of paragraph number [0023].
If the melt viscosity is less than 100 poise, the extruded resin is no longer liquid and cannot be formed into a uniform film.If the melt viscosity exceeds 100,000 poise, the viscosity is too high and the fine irregularities of the pressure roll may be reduced. This is because transfer to the resin film becomes difficult.

[0027]

EXAMPLES Examples of the present invention will be described below, including comparative examples. (Example 1) Using an apparatus having the structure shown in FIG. 1, various thermoplastic resins (polyethylene (PE), nylon 6, polyethylene terephthalate (PET)) containing no additives were heated and melted to the melting point or higher, and then the surface roughness was increased. 0.223μm in Ra
A thermoplastic resin-coated metal plate was prepared by pressing a JIS 5052-H18 aluminum plate having a thickness of 0.2 mm using a pressure roll of 1.35 μm, 4.89 μm and a temperature adjusted to 20 ° C. The coating thickness of the thermoplastic resin was set to 9 to 11 μm. The prepared plate was evaluated for surface roughness and appearance, and cracks in the resin film after the 1T-180 degree bending test were observed. Table 1 summarizes the results.

[0028]

[Table 1]

As is evident from Table 1 above, in any of the examples, the surface of the thermoplastic resin had a matte appearance,
No cracks were found in the processed part after the bending test. The surface roughness of the thermoplastic resin coating is 0.2 to 5 μm.
Was in the range.

(Example 2) In the same manner as in Example 1 above, a PET resin to which an additive not intended for matting of 0.2 μm or less was added was heated and melted to a melting point or higher (265 ° C.), and then the surface was heated. Roughness is 0.223μm, 1.35μm, 4.89μm in Ra
0.2mm thick using a pressure roll adjusted to 20 ℃
JIS5052-H18 was pressed against an aluminum plate to produce a PET resin-coated metal plate. The thickness of the PET resin film was set to 9 to 11 μm. The prepared plate was evaluated for surface roughness and appearance, and 1T-18
Cracking of the resin film after the 0 degree bending test was observed. Table 2 summarizes the results.

[0031]

[Table 2]

As is clear from Table 2 above, in any of the examples, the surface of the thermoplastic resin has a matte appearance,
No cracks were found in the processed part after the bending test. The surface roughness of the thermoplastic resin coating is 0.2 to 5 μm.
Was in the range. That is, even if the additive is contained in the thermoplastic resin, if the particle size is 0.2 μm or less, a thermoplastic resin-coated metal plate having a good matte surface can be obtained.

(Comparative Example 1) In the same manner as in Examples 1 and 2, a PET resin to which 5% of silica fine particles of 5 μm was added as a matting agent was heated and melted to a temperature equal to or higher than the melting point (265 ° C.). Roughness 0.223μm, 1.35μm, 4.89μm in Ra
0.2mm thick using a pressure roll adjusted to 20 ℃
JIS5052-H18 was pressed against an aluminum plate to produce a PET resin-coated metal plate. The thickness of the PET resin film was set to 9 to 11 μm. The prepared plate was evaluated for surface roughness and appearance, and 1T-18
Cracking of the resin film after the 0 degree bending test was observed. Table 3 summarizes the results.

[0034]

[Table 3]

As is clear from Table 3 above, in each of the comparative examples, the surface of the thermoplastic resin had a matte appearance,
The surface roughness of the thermoplastic resin coating is 0.2 to 5μ.
m, but cracks were observed in the processed part after the bending test. That is, the particle size is 0.5 μm in the thermoplastic resin.
When an additive intended for matting is included, even if a matte surface is obtained, cracking may be caused by bending or drawing.

(Comparative Example 2) In the same manner as in Example 1 described above, after heating and melting various thermoplastic resins containing no additives to the melting point or higher, the surface roughness was 0.162 μm in Ra and 7.33 in Ra.
thickness using a pressure roll with a temperature of 20 μm.
A thermoplastic resin-coated metal plate was prepared by pressing against a 0.2 mm JIS5052-H18 aluminum plate. The coating thickness of the thermoplastic resin was set to 9 to 11 μm. Along with evaluating the surface roughness and appearance of the prepared plate,
Cracking of the resin film after the 1T-180 degree bending test was observed.
Table 4 summarizes the results.

[0037]

[Table 4]

As is apparent from Table 4, the surface roughness is
In each of the comparative examples using a pressure roll of 0.162 μm in Ra, the resin surface of the produced thermoplastic resin-coated metal plate was glossy and a matte appearance could not be obtained. Further, in the comparative examples using the pressure-bonding roll having a surface roughness of Ra of 7.33 μm, the resin adhered to the pressure-bonding roll, and a thermoplastic resin-coated metal plate could not be produced.
That is, the surface roughness of the pressure roll is 0.2 to 5 μm in Ra
It can be seen that when the shape deviates from the fine irregularities, it becomes difficult to obtain a thermoplastic resin-coated metal plate having a good matte surface.

(Comparative Example 3) Using an apparatus having the structure shown in FIG. 1, a PET resin was used and heated and melted under a condition that the melt viscosity was less than 100 poise or more than 100,000 poise. In this practice, in the case of a commercially available PET resin, it is difficult to reduce the melt viscosity to less than 100 poise under ordinary use conditions. However, even under such conditions, the viscosity was too low, so that the extruded resin was no longer liquid and could not be formed into a uniform film. In addition, it is difficult to increase the melt viscosity of the PET resin to more than 100,000 poise under normal use conditions. . The molten resin having a melt viscosity of 120,000 poise has a surface roughness of 0.223 μm, 1.35 μm, and 4.89 μm in Ra.
0.2m thick using a pressure roll adjusted to 20 ℃
A JIS5052-H18 aluminum plate was pressed to prepare a PET resin-coated metal plate. The thickness of the PET resin film was set to 9 to 11 μm. The surface roughness and appearance of the prepared plate were evaluated, and 1T-18
Cracking of the resin film after the 0 degree bending test was observed. Table 5 summarizes the results.

[0040]

[Table 5]

As is evident from Table 5, when the melt viscosity of the resin is as low as less than 100 poise, it is difficult to form a resin sheet by an extruder, and it is impossible to produce a thermoplastic resin-coated metal plate itself. On the other hand, when the melt viscosity of the resin is 10
In the case of higher than 0000 poise, in any case of Table 5, the rough surface of the pressure bonding roll was not sufficiently transferred to give a glossy appearance, and the thermoplastic resin film was cracked in the 1T-180 degree bending test. Occurred.

(Comparative Example 4) Urethane-based paint, epoxy-based paint, polyester-based paint, acrylic-modified epoxy paint containing no matting agent, urethane-based paint containing 20% of 5 μm silica fine particles as matting agent and polyester System paint and prepare these paints with a surface roughness Ra of 0.128.
Using a roll coater having applicator rolls of μm and 3.24 μm, a JIS5052-H18 aluminum plate having a thickness of 0.2 mm was reverse-coated to prepare a resin-coated metal plate. The coating thickness was adjusted to 9 to 11 μm. The prepared plate was evaluated for surface roughness and appearance, and cracks in the resin film after the 1T-180 degree bending test were observed. Table 6 summarizes the results.

[0043]

[Table 6]

As is clear from Table 6, the paint containing no matting agent had a glossy appearance irrespective of the surface roughness of the pressure roll. On the other hand, the paint to which the matting agent was added all had a matte appearance irrespective of the surface roughness of the pressure bonding roll, but cracked in the bending test. That is, when roll coating is performed using a paint to which a matting agent has been added, although a resin-coated metal plate having a matte surface can be produced, the viscosity of the paint is higher than that of a paint containing no matting agent. As a result, coating by the roll coating method becomes difficult and the coating speed becomes slow, and in addition, there is a concern that cracking may occur during bending or drawing.

[0045]

As described above, with the thermoplastic resin-coated metal sheet having a matte surface according to the present invention, the properties of the metal sheet itself, such as bending workability and drawing workability, can be improved. In addition to this, it is possible to solve problems in production technology such as a problem of dispersion of the matting agent when a conventional paint is used.

Further, according to the method for producing a thermoplastic resin-coated metal sheet having a matte surface according to the present invention, the matte surface can be formed even if an additive for matting is not contained in the thermoplastic resin. It can produce a new thermoplastic resin-coated metal sheet, and can be applied to a wide range of materials such as iron, aluminum, and copper. , Can contribute to a wide range of industries.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a manufacturing apparatus used for manufacturing a thermoplastic resin-coated metal sheet having a matte surface according to the present invention.

[Explanation of symbols]

1: thermoplastic resin pellets
2: Hopper 3: Extruder 4: Extrusion die
5: thermoplastic resin sheet 6: metal plate 7: preheater
8: Crimping roll 8a: Crimping roll with fine irregularities formed on the surface 9: Thermoplastic resin-coated metal plate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 31/30 B32B 31/30 // B29L 9:00 31:10 (72) Inventor Shun-ichiro Maezono Moka, Tochigi 15 Kinuigaoka Ichika Kobe Steel Co., Ltd. Moka Works F-term (reference) 4F100 AB01B AB10 AK01A AK04 AK42 AK48 BA02 CA23A DD07A DE01A DE01H EH232 EJ402 EJ421 EJ502 GB07 GB16 GB48 HB22A JA06A JB16A JY01A26F AG03 AH42 AH47 AH55 AH56 AR12 AR13 AR17 KA01 KA17 KB13 KB22 KK65 KK88 KL84 KM16

Claims (7)

[Claims] In a metal plate coated with a thermoplastic resin, the thermoplastic resin layer has a surface roughness Ra of 0.2 to 5 μm.
m. A thermoplastic resin-coated metal plate having a matte surface formed on the matte surface of m. 2. An average particle size of 0.2 μm in a thermoplastic resin layer.
The thermoplastic resin-coated metal plate having a matte surface according to claim 1, which does not contain the above additive for matting or does not contain any additive having an average particle size of 0.2 µm or more. 3. A step of preheating a metal plate, a step of extruding a thermoplastic resin heated and melted on a surface of the metal plate,
A thermoplastic resin-coated metal having a matte surface, characterized by comprising a step of cooling and solidifying while pressing a thermoplastic resin extruded by a cooled pressure roll onto a metal plate, the surface having fine irregularities formed thereon. Plate manufacturing method. 4. The pressing roll has a surface roughness of 0.2 to 5 in Ra.
4. The method for producing a thermoplastic resin-coated metal sheet having a matte surface according to claim 3, wherein the metal sheet is formed in a fine irregular shape of μm. 5. The method for producing a thermoplastic resin-coated metal sheet having a matte surface according to claim 3, wherein the melt viscosity of the thermoplastic resin extruded in the extrusion step is 100 to 100,000 poise. 6. The thermoplastic resin extruded in the extrusion step has a melt viscosity of 100 to 100,000 poise, and contains an additive for matting having an average particle size of 0.2 μm or more in the thermoplastic resin. The method for producing a thermoplastic resin-coated metal sheet having a matte surface according to claim 3 or 4. 7. The thermoplastic resin extruded in the extrusion step has a melt viscosity of 100 to 100,000 poise, and contains no additive having an average particle size of 0.2 μm or more in the thermoplastic resin. 5. The method for producing a thermoplastic resin-coated metal sheet having a matte surface according to 4.