JPS5811070A - Continuous painting method - Google Patents

Abstract

PURPOSE:To obtain a beautifully painted plate having roving patterns free from flow marks by transferring paint onto a painting roll via a receiving roll on which the paint is flowed down from a chamber, then coating the paint continuously on the surface of a base plate from the painting roll. CONSTITUTION:Paint R is flowed down from a chamber 12 provided above a receiving roll 1 onto the surface of the roll 11 in the state of avoiding the generation of flow marks, and is further transferred onto the surface of a painting roll 14 under natural revolution with respect to the roll 11 via a meniscus part 15, then the paint is naturally applied on the surface of a base plate P from the roll 14. Since it is necessary to generate beautiful roving patterns, the paint of high thixotropic properties and low fluidity as compared to paint for general roll coating purposes is preferable as the paint to be used. For example, the paint of low fluidity such as PVC plastisol paint is more preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous coating method for obtaining a painted board having a beautiful roving pattern without running patterns.

In recent years, painted boards with a beautiful appearance have been eagerly sought after as interior and exterior materials for buildings, home appliances, passenger cars, furniture, and the like.

The present invention aims to obtain a painted board having a beautiful roving pattern that meets such demands. Conventionally, in a two-roll type natural roll coater as shown in FIG. The paint R is drawn up by the pickup roll 3 and transferred to the pickup roll 3 and the naturally rotating coating roll 4 via the meniscus portion 5, and then supported by the backup roll 6 and transferred to the coating roll 4. There is a method of applying natural coating onto the substrate P that is moving in the same direction as the rotation direction.

In this case, as the paint, for example, a high viscosity paint,
When paints such as metallic paints or paints mixed with large particle diameter pigments are used, a so-called roving pattern (an uneven pattern on the painted surface) on the substrate surface, and a running pattern (the width of the substrate) on the painted surface. This was undesirable because there was a problem that a striped pattern (color unevenness in the direction) occurred and the beauty of the surface was impaired.

Here, the state in which the flow pattern occurs will be explained with reference to the schematic diagram of FIG. 2. FIG. 2 is a plan view showing a state in which the pickup roll 3 is partially immersed in the paint pan l. 7
is the central axis of the pickup roll 3, which rotates as shown by the arrow. In this case, the paint R in the paint pan l moves as shown by the arrow 8 as the pickup roll 3 rotates,
The pattern as shown in 9 is formed on the surface of the paint on the pickup roll 3, and this pattern is transferred onto the substrate P via the paint roll 4. In the case of FIG. 2, the flow pattern tends to appear at both ends of the pickup roll 3, but in the meniscus portion of FIG. 3, which will be described later, the flow pattern appears over the entire surface in the axial direction, although to a small extent. If a flowing pattern occurs, a roving pattern with a stable and uniform color tone will not be produced, resulting in a loss of beauty.

The object of the present invention is to obtain a beautiful painted board having a roving pattern without running patterns, in accordance with the preferences of consumers.

That is, the coating method of the present invention involves natural rotation of a substrate and a coating roll to produce a coated board with a roving pattern on the surface. The paint is allowed to flow down continuously onto the surface, and the catch is natural to the roll, or the surface of the paint roll is rotated in perspective.
It is characterized in that a part or almost all of the paint is transferred, and then the paint is continuously applied as a natural coating onto the surface of the substrate from a coating roll.

In this specification, natural rotation refers to rotation in which two rolls move in the same direction near the contact area, and reverse rotation refers to rotation in which two rolls move in opposite directions to each other near the contact area. Refers to rotation as if moving in a direction, and both are terms used in the field of painting.

The present invention will be explained below based on the drawings.

FIG. 3 shows one example of the present invention, and is a side view for explaining the state of continuous coating, in which the roll and the coating roll are rotating naturally.

In FIG. 3, instead of using a paint pan that causes a flow pattern, the paint R overflows from a chamber 12 provided above the roll 11, and the paint R is transferred to the roll through a flange 13. In the 11-axis direction, it is layered with a constant thickness,
The receiver is allowed to flow down onto the surface of the roll 11 under less turbulent flow conditions.

The paint R is supplied to the chamber 12 from a tank (not shown). The chamber 12 may have a structure having an integrated flange 13 as shown in FIGS. 3 and 5, or may have a structure that can be separated as shown in FIG. 6. Alternatively, it may be of a mechanism in which it is dropped from the lower slit 17 of the chamber 12, as shown in FIG. 7, without using a flange. In short,
It is necessary for the paint to flow down continuously onto the roll surface without creating a running pattern. Paints usually consist of resins, solvents, pigments, etc., and need to be fluid, such as solvent-type or emulsion-type. In particular, in the present invention, it is necessary to generate a beautiful rope pattern, so the paint used in the present invention has high thixotropic properties and fluidity compared to general roll coating paints. A paint with a low temperature is desirable. Specifically, the thixotropic index (T
I value) is preferably 1.5 or more. For example, paints that have low fluidity such as vinyl chloride-based plastisol paints and acrylic water-dispersed paints, low-gloss paints that contain large amounts of inorganic pigments such as calcium carbonate,
A low-gloss paint containing a large amount of organic pigment such as urethane beads with a particle size of 20μ or more, an average particle size of 0.05~ in the paint.
2. There are metallic paints mixed with Qim's aluminum aggregate (Special Publication No. 55-46227).

When the paint is to form a coating film with a substantially constant thickness on the substrate, the overflow portion of the chamber 12 is held substantially horizontally,
It is desirable that the bearing flows down with a substantially constant thickness in the roll axis direction. Furthermore, the paint flows down in a flow state with little turbulence and no flow pattern, and the flow state with little turbulence is most preferably a laminar flow state. Some disturbance is allowed within a range that does not impede the purpose of the present invention. For example, in FIG. 3, since the paint R is transferred to the coating roll 14 via the meniscus 15, turbulence is allowed to the extent that the flow pattern does not increase at the meniscus.

However, in FIG. 4, which will be described later, the turbulence in the flow state is directly transferred to the coating roll 14' and a flow pattern is likely to occur. It is important that it remains in a state where it does not occur.

The distance between the 7 langes 13 and the receivers and the surface of the roll 11, that is, the curtain film distance, is approximately O# 200 turns.

0 means that the tip of the seventh flange 13 is in contact with the surface of the roll 11, and in this case, the paint R that has flowed down along the seventh flange 13 is directly connected to the rotating base of the roll 11. It spreads evenly over the surface. If the tip of the flange 13 and the receiver do not contact the surface of the roll 11, the paint R that has flowed down the flange 13 separates from the tip and forms a curtain-like film, and the receiver transfers onto the surface of the roll 11.

However, in the case of a large gap of more than 200 mm, if the amount of flowing water is small, a stable curtain film may not be formed, and the curtain may be dispersed in particles below the curtain film, or part of the curtain may crack. Therefore, the coating film on the surface of the roll 11 may become uneven, so especially when applying a small amount of coating, it is preferable to reduce the interval to stabilize the curtain film. In addition, in the case of a mechanism in which the paint falls from a slit at the bottom of the chamber, the above curtain film interval is
The distance between the lower slit and the receiver is the distance between the lower slit and the roll surface.

Part or all of the paint R flowing down onto the receiver roll 11 is transferred onto the surface of the coating roll 14 which is naturally rotating with respect to the receiver roll 11. Note that the receiver has a meniscus portion 15 between the roll 11 and the coating roll 14.
If the meniscus portion 15 is not provided, there is a risk that the coating film will break and transfer to the substrate P will not be performed sufficiently. For this reason, the flow rate is reduced to the meniscus portion 15.
Adjust so that it always exists.

(9) Next, from the coating roll 14, the backup roll 16
The paint is continuously and natural coated on the surface of the substrate P supported by.

Here, the substrate typically includes metal plates such as steel plates and aluminum plates, flat plates such as gypsum board and wood plywood, paperboard, and plastic plates.

These substrates may be subjected to a suitable pretreatment by a conventional method to improve the adhesion of the paint, and may also be coated with a suitable undercoat for the purpose of imparting anticorrosion properties and adhesion. After applying the paint of the present invention, drying and heating are performed in a manner appropriate to the type of paint. A coated board is thus obtained.

In order to maintain a flow state with little turbulence, it is desirable that the surfaces of the roll 11 and the coating roll 14 of the first receiver be finished smoothly. Further, it is preferable that the roll 11 of the receiver is made of metal, and that the coating roll 14 be coated with a coating material that is more elastic than metal, such as synthetic rubber. The amount of paint R transferred from the roll 11 to the coating roll 14 can be adjusted (10) by adjusting the roll interval. There is a paint receiver 18 at the bottom of each roll,
This is so that falling paint can be collected.

The amount of paint R applied to the substrate P is mainly determined by the amount of paint R applied to the substrate P.
The amount of flow from and the amount of gap between the roll 11 and the coating roll 14 and the amount of the gap between the roll 11 and the coating roll 14 are determined by adjusting the rotational speeds of the roll 11 and the coating roll 14.

In this way, compared to the conventional method, a painted plate having a beautiful roving pattern with fewer flow patterns can be continuously obtained, but even in this case, slight flow patterns may still occur. As a result of various studies regarding this point, the inventors of the present invention have found that a slight flow pattern occurs in the meniscus portion 15, and this is transferred onto the substrate P, resulting in a flow pattern on the painted object. Although the cause of the occurrence of flow patterns in the meniscus portion 15 has not been fully elucidated, one of the main reasons seems to be subtle differences in the roughness of the roll surface.

Figure 4 shows an example of the invention of wooden tablet 2, in which the receiver is rotating the roll and the coating roll in reverse;
FIG. 3 is a side view for explaining a case of continuous coating.

The difference from Fig. 3 is that the receiver is the roll 11' and the coating roller /l/
14' are reversely rotated with respect to each other, the others are 3rd
This is the same as the case shown in the figure.

Since the invention of wooden tablet 2 does not have a paint pan or a meniscus portion, it is possible to obtain a painted object decorated with a beautiful roving pattern without producing a running pattern. Furthermore, the invention of Mokkan 2 eliminates the need for delicate adjustment of the roll gap between the roll 11' and the coating roll 14' when adjusting the amount of coating onto the substrate, and the appropriate coating can be achieved by simply controlling the amount of water flowing down from the chamber 12'. This has the advantage that workability is significantly improved because of the large amount of material that can be obtained.

In addition, in FIGS. 3 and 4, the doctor knife 17
．． A receiver 17' is installed on the roll 11.11', and the receiver has the function of removing excess paint remaining on the surface of the roll 11.11'. By installing the trimmer knife 17, 17', the receiver removes the remaining paint on the surface of the roll 11, 11' where the paint flows down, thereby making it easier to control the coating amount and stabilizing the workability.

Examples of the present invention will be described below.

Example 1 An epoxy resin paint containing about 6 to 10 parts by weight of strontium chromate anti-corrosion pigment per 100 parts by weight of solid resin was applied to a galvanized steel coil with a thickness of 0.4mm and a width of 914 stripes. The coating was applied and baked so that the dry coating thickness was 5μ. Using this substrate as a substrate P, continuous coating was performed by the method shown in FIG. 3 using the chamber shown in FIG. 5.

The paint R is a thermosetting acrylic resin paint with a particle size of 0.2.
TI value 3, containing approximately 50 parts by weight of flat aluminum particles of ~l, Q mm based on 100 parts by weight of resin solid content.
．． 5 to 4.0, the amount of paint flowing down is 3 kg/min against the board width, and the amount of paint applied is 50 g/min when wet.
It was set as R.

Also, the distance between the flange and the receiver is 5Q1 nm.

The board passing speed is 60 rllpm, and the roll circumferential speed ratio is board passing speed: coating roll: receiving roll -1:1:(
13) 1.1. The baking conditions were an ambient temperature of 300°C and a time of 40 seconds.

The obtained painted board had a beautiful roving pattern and no running pattern at all.

As described in detail above, the present invention allows the paint to flow down from the chamber in a flow state with little turbulence, instead of pumping up the paint from the paint pan using a pickup roll, and by naturally applying the paint from the paint roll onto the substrate, The painted surface has a beautiful roving pattern without running patterns, and the resulting painted board can be used as a decorative steel plate for the interior and exterior of buildings, etc. The value is extremely great.

[Brief explanation of the drawing]

Figures 1 and 2 are a side view and a top view of the prior art, respectively. Figure 3 is a side view of the invention of wooden tablet 1, Figure 4
The figure is a side view of the invention of wooden tablet 2. 5 to 7 are perspective views showing the structure of the chamber according to the present invention. R...paint, P...substrate, 1...paint pan-3.
... (14) Pick-up roll, 4... Paint roll, 5... Meniscus portion, 6... Backup roll, 7...
Roll axis, 8... Paint flow, 9... Flow pattern, 1
1, ll',...The receiver is a roll, 12.12' chamber, 13.13', own flange, 14.14', 1 painting roll, 15...meniscus part, 16.16'...
・Backup roll, 17.17′...Doctor knife, 18.18′・1 paint receiver, 19.19′,・
slit. Applicant Taiyo Steel Co., Ltd. Representative Patent Attorney Masao Inoue Figure 1 Figure 2

Claims (1)

[Claims] 1. When manufacturing a painted board with a roving pattern generated on the surface by natural rotation of a paint roll relative to the substrate, the receiver receives the paint from a chamber provided above the roll. A continuous coating method characterized by flowing down onto the surface of a roll, further transferring the paint via a meniscus portion to the surface of a paint roll which is rotating naturally relative to the roll, and then naturally painting from the paint roll onto the surface of a substrate. 2. The continuous coating method according to claim 1, wherein the paint is caused to flow down onto the surface of the roll from a chamber provided above the roll in a flow state with little turbulence. 3. The continuous coating method according to claim 2, wherein the paint is caused to flow down onto the surface of the roll from a chamber provided above the roll in a laminar flow state. 4. The continuous coating method according to claim 1 or 2, wherein the chamber has a structure in which seven lunges are integrated. 5. The continuous coating method according to claim 1 or 2, wherein the chamber has a flange having a structure that allows it to be separated. 6. The continuous coating method according to claim 1 or 2, wherein the chamber has a structure having a slit at the bottom. 7. When manufacturing a painted board with a roving pattern on the surface by natural rotation of the paint roll relative to the substrate, the paint is caused to flow down onto the roll surface from a chamber installed above the roll. This continuous coating method is characterized in that the receiver is transferred onto the surface of a paint roll that is rotating in reverse relative to the roll, and then natural coating is applied from the paint roll to the surface of the substrate.