JPH0411969A - Method for forming metallic coating on sheet-like material - Google Patents

Abstract

PURPOSE:To prevent coating unevennesses from being caused by utilizing a die which is equipped with both the flow path of coating for an upper layer and a flow path of coating for a lower layer and joins the coating allowed to flow out through these flow pathes in a laminar state. CONSTITUTION:While the sheet-like material 17 is traveled, metallic coating is supplied from a coating supply port 8 by a quantitative pump and nonmetallic coating is supplied from a coating supply port 7 by the quantitative pump. Coating is introduced into the holding parts 6, 5 and regulated to the pressure equal in the width direction of the die and flows through the slots 10, 9 and is joined in a laminar shape by a slot 11 and discharged. While the coating discharged as two layers maintains a laminated state, it is uniformly stuck on the sheet-like material 17 directly from the die or indirectly via a coating roll 18 and a coated film having prescribed thickness is formed. Thereby metallic coating is efficiently performed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for applying metallic coating to a sheet-like object, particularly a thin metal plate, by die coating.

<Prior art and its problems> Several methods are known for continuously applying coating to a sheet-like object. Most of these methods use coating rolls.

However, when metallic coating is applied to a sheet-like object using this method, orientation occurs in the metallic pigment in the coating material, which tends to cause streak-like coating unevenness.

Another known method for continuously applying coating to a sheet-like object is to use a die. This die coating method is used to apply magnetic paint when manufacturing magnetic recording media,
It is used for coating photosensitizers in the production of photosensitive materials. However, when metallic paint is applied using the die coating method, streak-like coating unevenness tends to occur as in the case of the roll coating method.

Therefore, although metallic coating is mainly performed by spray coating, a more economical and efficient metallic coating method is desired.

Means for Solving the Problems According to the present invention, a multi-layer die capable of simultaneously coating a plurality of paints is used to coat a sheet directly from the die or indirectly through a coating roll. By simultaneously applying a plurality of paints in layers on the surface of a sheet-like object, such as a metallic paint in the lower layer and a non-metallic paint in the upper layer, it is possible to continuously apply a high-quality metallic coating to the sheet-like object.

According to the method of the present invention, die coating method or die coating method is used.
The reason why streak-like uneven coating is difficult to occur despite the roll coating method is not clear. However, since the metallic paint does not directly contact the lip of the die, but indirectly contacts the lip through the non-metallic paint that overlaps the metallic paint, the metallic pigment is subjected to shearing force and becomes oriented. This is thought to be due to the fact that the tendency for this phenomenon to occur is small. Furthermore, even if orientation occurs, the orientation of the pigment may change between the time it leaves the lip and the time the paint hardens, while both are still in a wet state, that is, in a state where the pigment can flow within the paint. It is thought that the phenomenon of deformation and part of the pigment penetrating into the upper non-metallic paint layer also occurs.

This relaxation of the orientation of the metallic pigment is thought to be due to the non-metallic paint covering the metallic paint layer, which prevents the surface of the metallic paint layer from rapidly drying (=hardening). .

To further explain the invention, the invention can be practiced using any die that is capable of applying multiple layers of paint in a superimposed manner.

Such dies are available in various styles.

FIG. 1 is a conceptual diagram of one typical such die. In the figure, (1) is a die, which is composed of three overlapping blades: an upper blade (2), a middle blade (3), and a lower blade (4), and side plates (not shown) on both sides. ing. The upper blade and the lower blade are respectively provided with paint holding parts (5), (6) and paint supply ports (7), (8) for supplying paint thereto. The gap between the lower surface of the upper blade and the upper surface of the middle blade and the gap between the upper surface of the lower blade and the lower surface of the middle blade are slots (9) and (10), respectively.

The thickness of the paint flowing through the slots, ie the spacing between the top and bottom of the slots, is usually 100-500v.

The intersection angle (α) between slots (9) and (10) is such that the non-metallic paint flowing through slot (9) and slot (1o)
It is preferable to make an acute angle, usually 30 degrees or less, so that the flowing metallic paint can smoothly merge to form an overlapping paint layer. Note that the tip of the middle blade may be a knife edge, but from the viewpoint of workmanship and handling, it is preferable to make it slightly rounded.

Further, as shown in the figure, it is preferable that the slots (9) and (10) be merged inside the die to form a single slot (11), but it is preferable that the slots (9) and (10) be made to open independently to the outside. It's okay. In addition, in FIG. 1, the die (
The mechanism that supports 1) and adjusts the positional relationship between the coating roll or the sheet material to be coated and the lips (12) and (13) of the die, and the mechanism that supplies a fixed amount of paint to the die are omitted. has been done.

In the present invention, the paint flowing out from the die may be applied directly to the sheet-like object to be coated, or the paint flowing out from the die may be once applied to a coating roll, and then applied from the coating roll to the sheet-like object. You may also do so.

One typical example of the positional relationship between the die (1) and the sheet-like object to be coated when coating the sheet-like object directly from the die is as shown in Figure 2. This is a method in which a sheet-like material (17) is supported and the slits (11) are arranged perpendicularly to the sheet-like material, that is, toward the center of the roll. According to this method, since the sheet-like material is fixedly supported, the distance between the lip of the die (1) and the sheet-like material is kept constant. Another typical example, as shown in FIG.
) to face each other. In this method, the distance between the lip of the die (1) and the sheet material changes depending on the pressure at which the paint is discharged from the die. Fig. 4 shows a variation of the method shown in Fig. 3, in which the sheet material is placed at a position slightly away from the roll in the non-coating state, usually the bottom surface of the sheet material is 50 degrees from the roll.
The die is opposed to the sheet material at a distance of 0 to 500 pm. When using this method, local variations in the thickness of the coating film can be made smaller than in the case of FIG.

The position of the die coating roll and the sheet-like object when the paint flowing out from the die is once received on the coating roll and then applied from the coating roll to the sheet-like object to be coated while maintaining the layered state of the paint. One representative example of the relationship is the fifth
As shown in the figure. In this case, the peripheral speed of the coating roll may be the same as in the case of a general one-type roll coater. By interposing the coating roll in the middle in this way, it is possible to avoid defects in the coating film even if there are foreign objects on the sheet-like material or there are protrusions on the edges of the sheet-like material. Furthermore, even if defects cannot be avoided, defects in the coating film can be limited to only local defects.

In the present invention, various commercially available products can be used as they are as metallic paints and non-metallic paints.

That is, commonly used metallic pigments such as aluminum powder and brass powder can be used. Further, pigments obtained by coating these pigments with ultrafine particles of metal oxides, pearl mica pigments whose mica surface is coated with titanium dioxide, etc. can also be used. As the resin component of the vehicle, commonly used acrylic resins, alkyd resins, amino-alkyd resins, etc. are used in air-dried or baked-on types.

Although the coating thickness of the metallic paint is arbitrary, it is preferable that the coating thickness of the non-metallic paint overlaid thereon, that is, the thickness in an undried state, is 10 μm or more.

If this thickness is too thin, there is a risk that the expected effects of the non-metallic paint layer will not be exhibited. The preferred coating thickness of the non-metallic paint layer is 15-40 pm.

In the method of the present invention, the coating itself can be carried out according to a conventional method.

That is, while running the sheet material (17) in the direction of the arrow in FIGS. 2 to 5, metallic paint is applied to the die in FIG. 1 from the paint supply port (8), and non-metallic paint is applied to the die shown in FIG. Each is supplied using a metering pump. The paint flows into the paint holding parts (6) and (5), becomes under equal pressure in the width direction of the die, flows through the slots (1o) and (9),
Thrower) (11) merges in a layered manner and is discharged. The paint discharged in two layers uniformly adheres to the sheet material (17) directly from the die or indirectly via the coating roll (18) while maintaining its layered state, and forms a predetermined layer. Form a coating film with a thickness of . Note that if the flow speeds of the respective paints flowing through the slots differ greatly at the confluence point, it will be difficult to form a stable coating film, so it is preferable that the flow speeds of the non-metallic paint and the metallic paint match. Even if they are different, it is preferable that the difference between the two be as small as possible within ±50% based on the metallic paint.

The coated sheet material is introduced into a drying oven or other post-processing device in a conventional manner to harden the coating layer.

<Examples> The present invention will be explained in more detail by examples below.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

In addition, the die used in the following examples has a slot length of 57.5 mm and a vertical spacing (clearance) of 2801.1 m for both the upper layer paint and the lower layer paint.

Furthermore, the upper and lower slots merge at an angle of 15 degrees inside the die, and the merge slot has a length of 400 pm and a clearance of 5601 m. The height of the die lip is 2 for both the top and bottom.
．． It is 5 mm.

Example 1 Aluminum sheet (1100-HI3 material, diameter 1250
2 mm, thickness 0.5 mm) was run for 20 m in 1 minute, dies were arranged in the positional relationship shown in Fig. 2, and a metallic paint was applied to the lower layer and a clear paint was applied to the upper layer at the same time.

The width of the die is 124 mm considering the horizontal spread of the paint.
It was set to 2 mm. Lumiflon (Asahi Glass Co., Ltd. product) was used as the paint.

Clear paint resin: Fluororesin solids content = 51% by weight Solvent: Organic solvent Viscosity = 120 seconds (Ford Cup, 20°C) Metallic paint resin: Fluororesin solids content = 52% by weight Pigment Ni-Aluminum Paste (pigment size 501m or less) Solvent: Organic solvent Viscosity = 125 seconds (Ford cup, 20'C) The supply pressure of paint to the die was 2.5 kg/cm2,
The coating amount was 14 pm for both the metallic paint layer and the clear paint layer after drying.

The coated aluminum sheet was dried through a drying oven with a length of about 20 m. The inside of the drying oven is equally divided into three zones from the inlet side to the outlet side, and the temperature of the aluminum sheet at the outlet of each zone is 100°C.
Hot air was blown at temperatures of 0°C and 220°C.

The distance between the die lip and the aluminum sheet is 95-12
When coating was performed with the thickness changed to 5 μm, a smooth coating film with a good appearance was obtained.

Example 2 Aluminum sheet (1100-H18 material, diameter 1025
mm, thickness 0.15 mm) was run for 20 m in 1 minute,
The die was arranged in the positional relationship shown in FIG. 4, and a metallic paint was applied to the lower layer and a clear paint was applied to the upper layer at the same time. The distance between the lip of the die and the roll was set to 370 pm,
The width of the die is 1019 mm considering the horizontal spread of the paint.
mm. As for the paint, Kansai Paint■ KP-15.
90 was used.

Clear paint resin: Polyester resin solid content: 52% by weight Solvent: Organic solvent Viscosity: 120 seconds (Ford cup, 20°C) Metallic paint resin: Polyester resin solid content = 49% by weight Pigment Ni-aluminum Paste (pigment size 301m or less) Solvent: Organic solvent Viscosity = 120 seconds (Ford cup, 20°C) The pressure for supplying the paint to the die was 1.5 kg/am2, and the amount of paint applied was the same as the metallic paint after drying. Both the layer and the clear paint layer were 11 νm.

The aluminum sheet coated with the paint was treated in a drying oven in exactly the same manner as in Example 1, and a smooth coating film with a good appearance was obtained.

Example 3 An aluminum sheet (1100 material, width 1250 mm, thickness 0.5 mm) was run at 20 m/min, and a die and coating roll were placed on it in the positional relationship shown in Fig. 5 to coat the lower layer with metallic paint, Clear paint was applied to the upper layer at the same time. The distance between the die lip and the coating roll is approximately 100 μm,
The coating roll was rotated at a circumferential speed of 23 m/min in a direction opposite to the running direction of the aluminum sheet. The width of the die is 12
It was set to 50 mm. Lumiflon (Asahi Glass Co., Ltd. product) was used as the paint.

Clear paint resin: Fluororesin solid content: 51% by weight Solvent: Organic solvent Viscosity near 0 seconds (Ford Cup, 20°C) Metallic paint resin: Fluororesin solid content: 52% by weight Pigment Ni-Aluminum Paste (pigment size 50 μm or less) Solvent: Organic solvent Viscosity: 0 seconds (Ford cup, 20°C) The pressure for supplying the paint to the die was 2 kg/cm2, and the amount of coating was determined by the metallic paint layer after drying, Clear paint layer 13
It was set as pm. The coated aluminum sheet was dried through a drying oven with a length of about 20 m. The inside of the drying oven is equally divided into three zones from the inlet side to the 8-mouth side.
The temperature of the aluminum sheet at the exit of each zone is 1
Hot air was blown at temperatures of 00°C, 1160°C, and 220°C.

The resulting coating film was smooth and had a good appearance.

Effects> According to the present invention, metallic coating, which has conventionally been carried out exclusively by a spray method, can be carried out by an efficient die coating method.

[Brief explanation of the drawing]

FIG. 1 shows an example of a die suitable for implementing the present invention. FIGS. 2 to 5 are diagrams showing the relationship between a die and a sheet-like material when carrying out the present invention. 1: Die, 2: Upper blade of die, 3: Middle blade of die, 4: Lower blade of die, 5, 6: Paint holding part, 7.8: Paint supply part, 9
．． 10.11 Ni slot, 12.13: Lip of die, 14, 15.16: Support roll for sheet material, 17: Sheet material 18: Coating roll Gate B

Claims (4)

[Claims] (1) A method for applying metallic coating to a sheet-like object, which includes an upper layer paint flow path consisting of an upper layer paint supply port, a paint holding section following this, a slot leading from this paint holding section to a lip, and a lower layer paint. At least two paint flow paths are provided, including a supply port, a paint holding portion following the feed port, and a lower paint flow path consisting of a slot leading from the paint holding portion to the lip, and these flow paths have an equal velocity from each slot. A die is positioned so that when the paint flows out, the paint merges into a layer near the lip, and the lip of this die is placed close to a continuously moving sheet-like object.
A method characterized in that metallic paint is supplied from a lower layer paint supply port, non-metallic paint is supplied from an upper layer paint supply port, and the paint flowing out from each slot is layered and applied to a sheet-like object. . (2) A method for applying metallic coating to a sheet-like object, which includes an upper layer paint flow path consisting of an upper layer paint supply port, a paint holding section following this, a slot leading from this paint holding section to a lip, and a lower layer paint. At least two paint flow paths are provided, including a supply port, a paint holding portion following the feed port, and a lower paint flow path consisting of a slot leading from the paint holding portion to the lip, and these flow paths have an equal velocity from each slot. Using a die and a rotating application roll, which are positioned so that when the paint flows out, the paint merges in a layer near the lip, the metallic paint is supplied from the lower layer paint supply port of the die, and the upper layer paint is applied to the upper layer. Supply non-metallic paint from the supply port,
The paint flowing out from each slot is layered and placed on a coating roll, and then the paint on the coating roll is applied to a sheet-like object that is continuously moving in contact with the coating roll while maintaining a layered state. A method characterized by: (3) A die according to claim (1) or (2), characterized in that a die is used in which a slot for the lower layer paint and a slot for the upper layer paint merge inside the die to form one slot. Method. (4) The method according to any one of claims (1) to (3), wherein the coating thickness of the upper layer paint in an undried state is 10 μm or more.