JPH0679801A - Manufacture of resin coated metal sheet - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for producing a double-sided thermoplastic resin-coated metal sheet having excellent adhesion, workability, corrosion resistance, and appearance. [Composition] A pressure roll is pressed against a preheated metal plate wound around a winding roll, and a molten thermoplastic resin is flowed down from a T-die through an extruder into a gap between the pressure roll and the metal plate so that metal A resin is temporarily adhesively coated on one side of the plate, and then the other side is similarly temporarily adhesively coated with a resin by the T-die extrusion method, and then reheated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin-coated metal sheet having excellent adhesion, workability, corrosion resistance and appearance.

[0002]

2. Description of the Related Art Conventionally, as a surface-treated metal plate coated with a synthetic resin, a color steel plate obtained by applying a thermosetting acrylic resin paint or a polyester resin paint, or a laminated steel plate laminated with a resin film is known. .

Due to their beautiful color, appearance and corrosion resistance, they are widely used in construction, interior materials for buses and passenger cars, materials for household electric appliances, furniture furniture and the like.

However, the resin used in the paint is
Due to the need for coating workability, relatively low molecular weight ones are used, and even after baking and baking, the high molecular weight is not sufficient, and the flow on the metal substrate is not sufficient. there were.

On the other hand, a laminated steel sheet laminated with a resin film uses an extruded film made of a resin such as vinyl chloride resin, acrylic resin or fluororesin which has a consistently high molecular weight at a petrochemical plant. However, the molecular weight is also much higher than that of the resin for paints, and therefore the durability of the coating film on the substrate is significantly longer, for example, about 10 to 20 years, compared to 3 to 5 years in the case of applying the paint. Is.

However, in this case as well, there are various problems as follows. (1) When the thickness of the film is reduced, it becomes difficult to uniformly laminate the film on the substrate, and a phenomenon such as wrinkling occurs on the surface. Therefore, the thickness is usually limited to about 50 μm.

(2) Since the substrate has microscopic unevenness, a space is likely to be formed between the solidified film and the substrate, and the adhesion of the film is insufficient.

(3) Since it is once formed as a film, there are restrictions on the resin used in terms of film forming ability.

On the other hand, the metal substrate is 50 on the heating roll.
Preheated to a temperature in the range of ~ 170 ° C, then progresses through the gap between the heating roll and the cooling roll, and the molten resin is extruded into the gap between the metal substrate and the cooling roll preheated by the heating roll, and the molten resin is laid on the metal substrate. It has been reported that a surface-treated metal plate having a beautiful appearance and excellent adhesion and corrosion resistance as compared with the conventional color steel plate or laminated steel plate can be obtained by pressure-bonding to the plate (Japanese Patent Application Laid-Open No. 2000-242242). 57-203545).

This metal plate has markedly superior adhesion to the substrate and corrosion resistance as compared with the conventional metal plate. further,
Since the coating is performed in a molten state directly from the T-die without forming a film, the film thickness is 50 μm or less, which is difficult with the conventional film coating, and 35 μm or less.
It became possible to coat up to about μ thickness.

Since the durability of the surface-treated metal plate is greatly influenced by the type of thermoplastic resin and the film thickness, it is desirable that the film thickness can be controlled according to the required degree of durability and the price. However, the present invention enables coating with a thin film.

Further, for example, a hard resin or the like can be formed into a film, but it is easily broken, and it is difficult to form a film and then press-bond it to a metal plate. Since it is coated in the state of having properties, even such a hard resin can be used.

Besides, since the film forming step is omitted, there is an advantage that the cost is reduced.

Further, a method for producing a laminate by co-extruding a thermoplastic resin on both sides of a substrate is also disclosed in JP-A-55-10145.
No. 1 is disclosed.

[0015]

DISCLOSURE OF THE INVENTION According to the present invention, one side of a preheated metal plate is laminated with a thermoplastic resin extruded from a T die, and the other side of a resin-coated metal plate is further extruded from another T die. When a method of laminating a resin to obtain a double-sided resin-coated metal plate was examined, when the metal plate was preheated, the temperature of the resin and the metal plate of the obtained single-sided resin-coated metal plate was high and the resin was softened.

Then, when the resin coated with the first T-die comes into contact with the pressure-bonding roll of the second T-die, a flaw of the roll is transferred to the surface of the resin, resulting in a problem that the appearance is deteriorated.

The cause of this flaw may be dirt on the surface of the metal plate or slipping between the roll and the metal plate when starting the line or passing the metal plate.

The present inventor has found that if the preheating temperature of the metal plate is lowered in order to solve this problem, no flaws are formed, but conversely the adhesion is lowered.

Therefore, by lowering the preheating temperature and reheating the double-sided resin-coated metal plate obtained by coating the resin with the second T-die, no flaws are formed and the adhesion is good. Heading, completes the present invention.

The present invention provides a method for producing a thermoplastic resin metal plate having excellent adhesion, workability, corrosion resistance and appearance.

[0021]

According to the present invention, (1) a pressure roll is pressed against a preheated metal plate wound around a winding roll, and an extruder is installed in the gap between the pressure roll and the metal plate. After T
The molten thermoplastic resin is flowed down from the die to temporarily bond and coat the metal plate with the thermoplastic resin, and then this resin-coated metal plate is wound on another winding roll so that the resin-coated surface is in contact with the winding roll side. Then, press the other pressure roll from the side of the metal plate and press it through the extruder into the gap between the other pressure roll and the metal plate.
The molten thermoplastic resin is flowed down from the die, the other side of the metal plate is temporarily adhered and coated with the thermoplastic resin, and a double-sided resin-coated metal plate is obtained. A method for producing a double-sided resin-coated metal plate, which comprises reheating,

(2) The pressure-bonding roll is pressed against the preheated metal plate wound around the winding roll, and the thermoplastic resin melted from the T-die through the extruder is inserted into the gap between the pressure-bonding roll and the metal plate. The metal plate is allowed to flow down and the thermoplastic resin is temporarily adhered and coated, then the resin-coated metal plate is passed through while being wound on a pressure bonding roll, and the resin-coated surface is reversed so that the resin-coated surface is on the winding roll side. It is wound around another winding roll so that it is in contact with it, another pressure bonding roll is pressure-contacted from the metal plate side, and the molten thermoplastic resin is flowed down from the T die through the extruder into the gap between the other pressure bonding roll and the metal plate. The other side of the metal plate is temporarily adhered with a thermoplastic resin to obtain a double-sided resin-coated metal plate, and then the double-sided resin-coated metal plate is reheated by a downstream heating device. A method for producing a coated metal plate,

(3) Reheating at a temperature not higher than the temperature of the melt extruded resin and higher than the preheating temperature (1),
(2) The method described

(4) The thermoplastic resin is polyethylene terephthalate, the preheating temperature is 90 ° C. or higher, and the temperature of the metal plate when one side of the metal plate coated with the resin on the other side is 90 ° C. to 130 ° C. The method according to (1) or (2), wherein the reheating temperature is 140 ° C. or higher and the melt extruded resin temperature is lower than or equal to 140 ° C.

(5) The thermoplastic resin is polypropylene, the preheating temperature is 50 ° C. or higher, and the temperature of the metal plate when one side of the metal plate coated with the resin is 50 ° C.
The method according to (1) or (2), wherein the reheating temperature is 100 ° C or higher and the temperature of the melt-extruded resin is lower than or equal to 90 ° C.

The present invention will be described in detail below with reference to the drawings.

In the present invention, first, as the metal substrate, the roof,
Used for building materials such as walls and partitions, materials for automobiles, materials for household appliances, furniture, cans, etc., thick steel plates, zinc plated steel plates, zinc alloy plated steel plates, tin plated steel plates, tin alloys, depending on the application. A plated steel plate, an aluminum plated steel plate, an aluminum alloy plated steel plate, a stainless steel plate, or the like is used.

Further, a layer having a chemical conversion treatment layer of about 0.1 to 5 μm is also included.

The chemical conversion treatment is carried out as a surface treatment of the metal plate in order to improve the corrosion resistance, oxidation resistance and adhesion of the metal substrate. For example, zinc phosphate treatment, iron phosphate treatment or electrolytic chromate treatment is carried out. Done by

Further, it also includes those having an adhesive layer thereon without chemical conversion treatment or after chemical conversion treatment.

The adhesive layer is a layer coated with an adhesive of at least several μ in order to improve the adhesion between the metal substrate and the thermoplastic resin.

As the adhesive, an adhesive thermoplastic resin having a functional group such as a modified polyethylene resin, a modified epoxy resin, a modified vinyl resin is suitable.

These have good adhesion to both the metal and the thermoplastic resin used for coating. For example, in the case of a polyolefin-coated steel sheet, ethylene-vinyl acetate copolymer resin or ethylene-acrylic acid copolymer resin is used. Modified polyolefins are preferred.

The thermoplastic resin used for coating in the present invention is, for example, polyethylene terephthalate resin, polyolefin resin, acrylic resin, polyester resin, polyamide resin, vinyl chloride resin, fluororesin, polycarbonate resin, polystyrene resin, ABS resin, chlorine. Polyolefin resins, urethane resins, etc. are typical, and polyolefin resins include polymers or copolymers of ethylene, propylene, 1-butene, 1-pentene, etc., and acrylic resins such as acrylic acid and meta There are polymers or copolymers of acrylic acid, acrylic acid ester, methacrylic acid ester, acrylamide, etc., polyester resins include polyethylene terephthalate, oil-free polyester, etc., and polyamide resins include so-called nylon 66, nylon. Down 6, nylon 610, nylon 1
1 and the like. Vinyl chloride resins include homopolymers and copolymers with ethylene and vinyl acetate, and the like. Fluorocarbon resins include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylene resin. Fluorinated ethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, etc.

Two or more resins may be mixed and used. Further, it may contain additives usually used in the production of a film, for example, a deterioration inhibitor, a modifier, a pigment and the like. Further, when coating in a molten state, a crosslinking agent such as an amino resin or an epoxy resin may be added within the range where the fluidity is not lost.

These thermoplastic resins are required to have weather resistance, cold weather suitability, heat resistance, scratch resistance, stain resistance, chemical resistance, deep drawing workability, etc., depending on the use of the surface-treated metal sheet. It is selected as appropriate. For example, polyolefin has excellent cold resistance, polyamide has excellent abrasion resistance,
Acrylic resin has excellent stain resistance and chemical resistance, and fluororesin has excellent weather resistance.

Polyethylene terephthalate resins are particularly useful in acid resistant applications.

The resin may be a single layer coating or a multilayer coating of the same or different resins. In the case of multi-layer coating, for example, a multi-layer T die may be used and an adhesive layer may be provided between the layers.

For example, on a steel sheet coated with an adhesive and preheated, a molten thermoplastic resin is used as a lower layer, an adhesive resin is used as an intermediate layer, a thermoplastic resin is used as an upper layer, and a three-layer T die is used. , Can be extruded in a film form, to obtain a surface-treated steel sheet directly and continuously coated in multiple layers, or an adhesive resin in a molten state on a preheated steel sheet as a first lower layer,
Surface treatment with thermoplastic resin as the second intermediate layer, adhesive resin as the third intermediate layer, thermoplastic resin as the fourth uppermost layer, extruded into a film shape with a 4-layer T-die, and directly and continuously in multilayer coating A steel plate can be obtained.

Next, the manufacturing process will be described with reference to the drawings.

The metal substrate needs to be preheated before being coated with the molten resin.

Preheating increases the fluidity of the resin and improves the adhesion.

When preheating is not carried out or when the preheating temperature is low, particularly when a cooling roll is used, the adhesion of the resin is insufficient and the corrosion resistance is poor.

The higher the preheating temperature is, the better the fluidity of the resin is, which is preferable. However, if the preheating temperature is too high, the resin and the adhesive are decomposed, which is not preferable. It is also not preferable from the viewpoint of energy saving.

Moreover, as described above, when the preheating temperature is increased, the flaws of the roll are transferred to the resin surface during the second coating and the external appearance is impaired. Therefore, the preheating temperature is such that the resin is temporarily bonded by the first T-die. It is possible.

This temperature varies depending on the resin, and for example, temporary adhesion is possible at 90 ° C. or higher for double-sided polyethylene terephthalate and at 50 ° C. or higher for double-sided polypropylene.

FIGS. 1 and 2 are explanatory views showing the steps of the present invention, in which a pressure-bonding roll 5 is pressed against the surface of a metal substrate 1 which is wound around a winding roll 4 and preheated to a temperature T1. At the interface between the substrate surface and the pressure-bonding roll 5, the molten thermoplastic resin 3 is made to flow down from the T die 2 through the extruder, and the metal substrate 1
Cover with thermoplastic resin.

Then, the obtained single-sided resin-coated metal plate 6 is wound around the next winding roll 7 at the temperature T2, and the pressure bonding roll 8 is pressed against the metal plate 6, and the interface between the metal plate 6 and the pressure bonding roll 8 is wound. Then, the molten thermoplastic resin 10 is flown down from the second T die 9 through the extruder, and the resin not coated on the metal plate 6 is coated with the flow-down resin to obtain a double-sided resin-coated metal plate 11.

In FIG. 2, the single-sided resin-coated metal plate 6 is passed through the pressure-bonding roll 5 while being wound, and the resin-coated face is reversed by the guide roll 13 so that the resin-coated face is wound by the roll 7.
It is wound so as to be in contact with the side, the pressure-bonding roll 8 is pressed against the metal plate 6, and the interface between the metal plate 6 and the pressure-bonding roll 8 is passed through an extruder,
The molten thermoplastic resin 10 is flowed down from the second T die,
The resin-uncoated surface of the metal plate is coated with the falling resin to obtain the double-sided resin-coated metal plate 11.

In the present invention, the metal plate 11 is attached to the heating device 1.
Reheat at temperature T3 at 2. This reheating improves the adhesion.

The metal plate 11 coming out of the heating device is cooled and wound.

Cooling may be carried out, for example, by air cooling followed by water spraying, passing through a water cooling tank, or passing through a cooling roll.

Here, the temperature T2 of the metal plate 6 before the coating with the second T-die is the same as that when the resin coated with the first T-die comes into contact with the pressure roll at the second T-die. To
High temperature is not preferable in order to prevent the damage of the roll from being transferred to the resin surface and impairing the appearance. It is sufficient if the temperature is such that the resin can be temporarily bonded with the second T-die, and the heating and cooling required for this temperature. And adjust in advance.

This temperature T2 also differs depending on the resin coated with the first T-die, and is preferably 90 to 130 ° C. when the resin is polyethylene terephthalate. When the resin is polypropylene, the temperature is preferably 50 to 90 ° C.

Next, the reheating temperature T3 after the second coating is preferably high in order to improve the adhesiveness of the resin, and is preferably 140 ° C. or higher when the resin is polyethylene terephthalate.

When the resin is polypropylene, the temperature is preferably 100 ° C. or higher.

However, if the reheating temperature T3 is higher than the melt extruded resin temperature, the coating resin is decomposed and deteriorated, which is not preferable.

A specific description will be given below with reference to examples.

[0059]

【Example】

[0060]

Example 1 Using a laminated metal plate manufacturing apparatus using a pair of rolls having an outer diameter of 300 mm shown in FIGS. 1 and 2, an electrolytic chromic acid treated steel plate having a thickness of 0.2 mm was used as a metal plate. After preheating the steel plate, polyethylene terephthalate (PET) was melt extruded from the T die through the extruder at the interface between the steel plate and the roll on which the steel plate was not wound.

Further, polyethylene terephthalate was melt-extruded from the T die to the other surface of the metal plate by using a laminated metal plate manufacturing apparatus using a pair of rolls having an outer diameter of 300 mm further downstream.

Melt extruded resin temperature is 280 ° C., coating thickness is 50 μm, line speed is 50 mpm. The reheated steel sheet was cooled with water spray to room temperature, dried and wound.

In the case of PP (polypropylene), PP
And extruded with two layers of modified PP, the melt extruded resin temperature is 280
C., film thickness 70 .mu., Line speed 50 mpm.

The results are shown in Tables 1 and 2.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

Industrial Applicability According to the present invention, a double-sided resin-coated laminated metal sheet excellent in adhesion, workability, corrosion resistance and appearance can be manufactured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a method of the present invention.

FIG. 2 is an explanatory diagram of a method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 metal plate 2 T die 3 thermoplastic resin 4 winding roll 5 pressure bonding roll 6 single-sided resin coating metal plate 7 second winding roll 8 second pressure bonding roll 9 second T die 10 thermoplastic resin 11 double-sided resin coating Metal plate 12 Heating device 13 Guide roll

Claims (5)

[Claims] 1. A thermoplastic resin melted from a T-die is passed through an extruder through a extruder by pressing a pressure roll onto a preheated metal plate wound around a winding roll and pressing the pressure roll into the gap between the pressure roll and the metal plate. Then, temporarily coat the metal plate with a thermoplastic resin, then wind this resin-coated metal plate around another winding roll so that the resin-coated surface is in contact with the winding roll side. The thermoplastic resin melted from the T die through the extruder is flowed into the gap between the other pressure bonding roll and the metal plate, and the other side of the metal plate is temporarily adhered with the thermoplastic resin to form a double-sided resin. A method for producing a double-sided resin-coated metal plate, which comprises re-heating the double-sided resin-coated metal plate with a downstream heating device after obtaining the coated metal plate. 2. A preheated metal plate wound around a winding roll is pressed against a pressure bonding roll, and a thermoplastic resin melted from a T-die flows through a gap between the pressure bonding roll and the metal plate through an extruder. Then, the metal plate is temporarily adhered and coated with a thermoplastic resin, and then the resin-coated metal plate is passed through while being wound around a pressure bonding roll, and the resin-coated surface is reversed so that the resin-coated surface contacts the winding roll side. As described above, the other winding roll is wound around, the other pressure-bonding roll is pressure-contacted from the metal plate side, and the molten thermoplastic resin is flowed down from the T die through the extruder into the gap between the other pressure-bonding roll and the metal plate. Thermoplastic resin is temporarily adhered to the other side of the metal plate to obtain a double-sided resin-coated metal plate, and then the double-sided resin-coated metal plate is reheated by a downstream heating device. Manufacturing method of metal plate. 3. Reheating is carried out at a temperature not higher than the temperature of the melt-extruded resin and higher than the preheating temperature.
The method described. 4. The thermoplastic resin is polyethylene terephthalate, the preheating temperature is 90 ° C. or higher, and the temperature of the metal plate at the time of coating the other side of the metal plate coated on one side with the resin is 90 ° C. to 130 ° C. And the reheating temperature is 140 ° C. or higher and the melt extruded resin temperature or lower.
Or the method described in 2. 5. The thermoplastic resin is polypropylene,
The preheating temperature is 50 ° C. or higher, and the temperature of the metal plate when the other side of the metal plate whose one side is coated with the resin is 50 ° C. to 9 ° C.
3. The method according to claim 1, wherein the reheating temperature is 0 ° C. and the reheating temperature is 100 ° C. or higher and the melt extruded resin temperature is lower than or equal to 3.