JPH07256174A - Coating application method to corrugated sheet made of synthetic resin and device therefor - Google Patents

Abstract

PURPOSE:To uniformly apply a coating material liquid on a corrugated sheet by horizontally transporting this corrugated sheet in a direction perpendicular to the corrugation direction of this sheet and supplying the corrugated sheet and the coating material liquid between coating rolls on both upper and lower sides formed with the ruggedness corresponding to the corrugations of the corrugated sheet and a press roll, thereby applying the coating material thereon. CONSTITUTION:The main parts of this coating applicator 1 are composed of a line 2 for transporting the corrugated sheet N made of a synthetic resin nearly horizontally A in the direction perpendicular to the corrugation direction of this sheet and a roll coater 3 for applying the coating material liquid T to the corrugated sheet N. The main part of this roll coater 3 are composed of the upper coating roll 4 and the lower press roll 5. Further, the roll axis of the coating roll 4 is arranged in the corrugation direction of the corrugated sheet N and the ruggedness corresponding to the waveforms of the surface to be coated of the corrugated sheet N is formed on the roll. The rotating direction of this roll is set at the direction reverse from the transporting direction of the corrugated sheet N. On the other hand, the press roll 5 is formed with the ruggedness corresponding to the waveforms on the rear surface of the corrugated sheet N and its rotating direction is set at the direction forward to the transporting direction of the corrugated sheet N.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for applying a synthetic resin corrugated sheet, and more particularly to a synthetic resin corrugated sheet for applying a coating liquid to a synthetic resin corrugated sheet by a coating roll (application roll). And a coating device for a synthetic resin corrugated plate for carrying out this coating method.

[0002]

2. Description of the Related Art Synthetic resin corrugated sheets, which are generally used as building materials and roofing materials for houses, have antifogging properties, surface hardening properties, antistatic properties, weather resistance, and scratch resistance. Functionality is often given, but most of the methods are carried out by laminating functional films or kneading functional raw materials, and applying them to corrugated sheets of functional paint (or coating liquid). Is generally not applied very often. It is considered that this is because the functional coating material often has a low viscosity, so that it may be a flat plate, but in the corrugated plate, the film thickness at the peaks, valleys, and slopes tends to be uneven.

Of course, as a means for applying a coating material to a synthetic resin corrugated sheet, for example, Japanese Patent Application Laid-Open No. 54-102342 discloses a method by curtain flow coating. The plate feeding speed is restricted, and it is difficult to apply the corrugated plate at a normal forming speed, and there is a drawback that it cannot be in-line. Next, Japanese Patent Application Laid-Open No. 60-143862 discloses a coating method by spraying. In this method, when spraying is carried out by moving a spray gun in the direction of the streaks of the corrugated sheet (the direction perpendicular to the wave direction). Good, but when the gun moves perpendicular to the muscle direction (for example, when the coating device is installed inline on the corrugated sheet extrusion line), there may be differences in the coating thickness at the peaks, valleys, and slopes of the paint. There is a nature.

In addition, spray coating and Japanese Patent Publication Sho 58-
In the coating method using the brush roll disclosed in No. 21547, in addition to the problem that the film thickness at the peaks, valleys, and slopes is likely to be non-uniform, when the paint contains a surfactant, the paint takes in bubbles. However, it is difficult to obtain a smooth surface even after drying. In particular, when the paint is a low-viscosity paint liquid (rare paint liquid), it was difficult to apply it uniformly to the corrugated sheet.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a coating method and a coating apparatus capable of uniformly coating a synthetic resin corrugated sheet even with a low-viscosity coating liquid. That is, according to the present invention, a synthetic resin corrugated sheet is conveyed substantially horizontally in a direction perpendicular to the wave direction, and the corrugated sheet and the coating liquid have an uneven surface in advance corresponding to the corrugated shape of the corrugated sheet. A method for applying a synthetic resin corrugated sheet characterized by supplying and applying between a pair of upper coating roll and lower pressure roll, and a synthetic resin corrugated sheet being substantially horizontal in a direction perpendicular to the wave direction. A conveying line for conveying, a pair of upper coating rolls / lower pressure rolls having a roll axis in the wave direction of the corrugated plate and having a corrugated surface corresponding to the corrugation, and a coating liquid provided in contact with the upper coating rolls. Supplying doctor roll, the above-mentioned transport line, upper coating roll
It is an object of the present invention to provide a coating device for a synthetic resin corrugated plate, which is composed of driving means for driving a lower pressure roll and a doctor roll.

That is, according to the present invention, the roll surfaces of the upper coating roll and the lower pressure roll are formed in advance so as to have an uneven shape corresponding to (corresponding to) the corrugated shape of the corrugated plate at a specific position. The upper coating roll and the lower pressure roll are rotated and pressed substantially evenly along the waves of the corrugated sheet supplied between the two rolls, whereby the viscosity of the coating liquid (or coating) is not restricted (low Even viscosity)
The coating liquid can be applied to the corrugated plate substantially uniformly.

The synthetic resin corrugated sheet usable in the present invention is made of synthetic resin such as polycarbonate resin, acrylic resin and vinyl chloride resin, and is used as a simple building material such as a constituent wall material for a house, a roof material and a partition wall material. The integrally extruded transparent / semi-transparent / opaque corrugated sheet used may be used. These synthetic resin corrugated sheets have an average sheet thickness of 0.4 to 1.
5 mm, wave pitch: 32-130 mm, valley depth: 9-36
Normally set to mm. In order to apply the coating liquid, these corrugated plates are conveyed substantially horizontally in a direction (muscle direction) perpendicular to the wave direction. The conveying speed is preferably 2 to 20 m / min. Usually, the corrugated sheet is extruded in the direction perpendicular to the wave direction like the above-mentioned conveying direction, so if a coating line for coating the coating liquid is provided on the extension of the extrusion molding line, the conveying equipment / space Is preferable, and the conveying speed in this case is 2 to 20 m / min.

In the pair of upper coating roll and lower pressure roll used in the present invention, the roll surface is located at a position where the roll axis crosses in the corrugation direction of the corrugated sheet, and the roll surface is uneven corresponding to the corrugated shape of the corrugated sheet as described above. It is preformed so as to have a shape (the diameter changes in the roll axis direction). As the specific upper coating roll, a rubber roll or a soft synthetic resin roll can be used, and in particular, a rubber roll is preferable because it can absorb variations in the corrugated shape of the corrugated sheet, and more preferably, the Shore hardness of the rubber is set to 10 to 40 °. To be done.

In the present invention, the corrugated plate and the coating liquid which are conveyed as described above are supplied between the pair of upper coating roll and lower pressure roll, and the upper coating roll and the lower pressure roll are used to feed the corrugated plate. The coating liquid is applied to the corrugated plate while being pressed substantially uniformly along the wave. It is preferable to supply the coating liquid through the doctor roll that is in contact with the upper coating roll and has the unevenness corresponding to the unevenness of the upper coating roll, because the coating liquid is uniformly supplied.

Here, the rotation of the upper coating roll and the lower pressure roll is performed in the direction opposite to or in the forward direction of the corrugated sheet conveying direction, and the upper coating roll is in the reverse direction with respect to the corrugated sheet conveying direction. It is effective to rotate each in the forward direction. In particular, such a rotation of the roll is preferable because it entraps less bubbles during coating. The rotation speed of the upper coating roll is the maximum outer diameter of the roll: 250 to 400 mm and the minimum outer diameter: 1
In the case of 50 to 380 mm, 10 to 100 rpm is preferable, and the pressing force to the corrugated plate on the roll surface is 1 to 10 kgf / cm ^{2 even} with a low viscosity (for example, 1 cps) coating liquid diluted with water and / or an organic solvent. It is preferable because it can be applied with a uniform film thickness (for example, 1 to 10 μm when wet).

The lower pressure roll has a maximum roll outer diameter:
250 to 400 mm, and minimum roll outer diameter: 150 to 3
In the case of 80 mm, the rotation speed: 2 to 30 rpm (a peripheral speed approximately equal to the conveying speed of the corrugated plate is obtained), the pressing force on the corrugated plate on the roll surface: the same as the upper coating roll, 1 to 1
A pressure of 0 kgf / cm ² is preferable because a more reliable pressing force can be obtained.

On the other hand, as the doctor roll for supplying the coating liquid, a metal roll is preferable for supplying the coating liquid to the corrugated plate with a uniform film thickness via the rubber upper coating roll, and further, the rotating direction of the upper coating roll. It is more preferable to set the pressing force to the upper coating roll to 1 to 7 kgf / cm ² while rotating in the forward direction corresponding to the above.

In the present invention, the coating liquid may be the present coating liquid alone, but may be applied to a primer coating liquid. When using this coating liquid and primer coating liquid,
It is preferable that a pair of upper coating roll and lower pressure roll be arranged on the upstream and downstream sides of the conveying line, and that the corrugated plate is first coated with the primer coating liquid and then the main coating liquid.

The coating liquid that can be used in the present invention includes anti-fogging property, surface hardening property, antistatic property, weather resistance, and corrugated plate.
Examples thereof include various water and / or organic solvent-based diluted low-viscosity coating liquids capable of imparting functions such as scratch resistance. In particular, as a material imparting antifogging property, a coating solution in which a silicic acid sol and / or silicon dioxide modified with a metal oxide insoluble in water or an organic solvent is dispersed in water or an organic solvent is preferable.

Examples of the metal oxide include colorless metal oxides derived from zinc, titanium, zirconium or titanium. Of these, aluminum oxide is preferable.
The solubility of the oxide itself or its hydrated form in water at 20 ° C. is preferably below 200 ppm. The metal oxides can be colloidal in water as a suspending medium, but colloids in polar liquids such as dimethylformamide or isopropanol or in aqueous solvents such as acetone, methanol or a mixture of ethanol and water. Can also be used. Colloidal particles below 200 nm, especially 1
It is desirable to have sizes below 20 nm, especially 5 to 100 nm.

As the silicic acid sol, that is, colloidal silicic acid, commercially available ones can be used, but anionic type containing a cation such as an alkali ion or an ammonium ion is particularly suitable for stabilization. If necessary (for example, to form a closed layer), a surfactant may be added to these coating liquids, and specifically, 2 to 20% by weight, especially 3 to 3% by weight of the oxide content may be added. 5% by weight of non-anionic surfactant is preferred.

The metal oxide for imparting the surface hardening property to the corrugated sheet is a silane-based paint, a polyurethane-based paint or the like, an antistatic one is a silica-based paint or the like, and a weathering-resistant one is a metal oxide. Zinc oxide-based paints and the like are preferable examples. When these coating liquids are applied to the corrugated plate, it is preferable to apply the above-mentioned primer coating liquid before that since the adhesion to the corrugated plate is enhanced, but the primer coating liquid is polarizable dispersible in water or an organic solvent. It is preferable that the polymer is composed of a polymer having an average molecule of at least 1000 or more, preferably 10000 or more, and has the polar group in an amount of 0.4 to 100 milliequivalent with respect to 100 g of the polymer.

As the polar group, especially a hydroxyl group,
Carboxyl group, sulfonyl group, carboxylic acid amide group,
Examples include nitrile groups and silanol groups. Of these, a hydroxyl group, a carboxyl group, a carboxylic acid amide group and a silanol group are preferable. A suitable class of polymers comprises the polymerization or copolymerization of vinyl monomers, polyesters, polyethers, polycarbonates, polyurethanes or epoxy resins. At least some of the monomer units that make up the polymer must have polar groups of the type described above. The polar group may be derived from the underlying monomer or may be subsequently introduced into the polymer by reaction. Some of the monomers contain non-polar groups such as alkyl, alkylene, aryl or arylene groups.

In the present invention, the driving means includes a conveying line for conveying the synthetic resin corrugated sheet, an upper coating roll,
The combination of the lower pressure roll and the doctor roll, specifically, the deceleration motor that drives the transport line and each roll, or the combination of the motor as the power source and the reduction gear and the power transmission device, which are added if necessary, is increased. To be

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to examples of corrugated plate coating apparatus and examples shown in the drawings. The present invention is not limited to this. First, in FIGS. 1 to 3, a corrugated plate applicator (1) conveys a synthetic resin corrugated plate (N) substantially horizontally (A) in a direction perpendicular to the wave direction of the corrugated plate (N). It mainly comprises a line (2) and a roll coater (3) for applying the present coating liquid (T) to the corrugated plate (N).

This roll coater (3) comprises a coating roll (4) as an upper coating roll and a pressure roll (or a pressure roll) (5) as a lower pressure roll.
And a doctor roll (6), the coating roll (4) has its roll axis arranged in the wave direction of the corrugated plate (N), and the corrugated shape of the coated surface of the corrugated plate (N) is as shown in FIG. The corrugated plate (N) has a corrugated surface, is in contact with the surface to be coated of the corrugated plate (N), and the rotation direction is opposite to the conveying direction of the corrugated plate (N).

The pressure roll (5) faces the coating roll (4) as shown in FIG. 3 and has irregularities corresponding to the corrugated shape of the back surface of the corrugated plate (N). Is pressed, and the rotation direction is the forward direction with respect to the conveyance direction of the corrugated plate (N). The doctor roll (6) has irregularities corresponding to the irregularities of the coating roll (4) and comes into contact with the coating roll (4), and as shown in FIG. 1, it is pumped from the second tank (7) as a paint tank. The coating liquid (T) supplied via 8) is supplied to the coating roll (4). The direction of rotation is forward with respect to the coating roll (4).

Next, a roll coater (13) for applying the primer coating liquid (P) is installed on the upstream side of the transfer line of the corrugated plate (N) with respect to the roll coater (3) having the above structure. There is. The front roll coater (13) has almost the same structure as that of the roll coater (3), and as shown in FIG. 1, the front doctor roll (16) is fed from the first tank (17) as a primer paint tank via the pump (18). ) Is applied to the surface of the corrugated plate (N) by the pre-coating roll (14) before the application of the main coating liquid.
The front coating roll (14) rotates in the direction opposite to the conveying direction of the corrugated plate (N), and the pressure roll (15) rotates in the forward direction of the conveying direction of the corrugated plate (N). (16) rotates so as to contact the front coating roll (14) in the forward direction.

The corrugated sheet (N) thus integrally extruded
Is coated with the primer coating liquid (P) in advance by the front roll coater (13) on the conveying line (2) which is an extension of the molding line (S), and then the main coating liquid (T) is rolled by the roll coater (3). ) Is applied. The corrugated plate (N) to which the primer coating liquid and then the main coating liquid (T) have been applied in this way is dried through a far-infrared heating and drying section (furnace) (9) as shown in FIG. Here, (10) in FIG. 1 is a conveyance roller, (20) in the molding line (S) in FIG. 2 is a synthetic resin integrated extrusion molding machine,
(21) is a die-cutting machine, (22) is a corrugating machine, and (23) is a take-up roll.

As described above, the coating liquid (3) is provided with the coating roll (3) having the corrugations corresponding to the corrugated shape of the corrugated plate (N) and rotating in the direction opposite to the conveying direction of the corrugated plate (N). Since T) is applied to the corrugated plate (N), the coating liquid (T) can be applied in a thin film, so that the entire surface to be coated can be applied regardless of the wave shape of the corrugated plate (N) and the low viscosity of the paint. The paint can be applied uniformly. Further, by combining the coating roll (4) and the doctor roll (6), the coating liquid can be circulated and the loss of the coating can be reduced.

Since the pre-coating roll (14) having the same structure is used also in the application of the primer coating liquid (P), the entire surface to be coated is evenly applied, resulting in loss of the primer coating liquid. Also less. Further, since the transport line (2) is formed on the extension of the integral extrusion molding line (S) of the corrugated plate (N), the equipment can be simplified.

A far-infrared heating / drying unit may be installed between the front roll coater (13) and the roll coater (3). The obtained coated corrugated sheet (N) can be coated with the coating liquid not only on one side but on both sides by using a corrugated sheet coating device (not shown) separately provided with the same configuration. Example 1 Aqueous colloidal weak ionic silicic acid (commercially available, Bayer silica sol 300, which is an extruded polycarbonate resin transparent corrugated board, whose surface is modified with aluminum oxide as an antifogging agent.
Aluminum oxide (30% by weight) added with 0.1% by weight of anionic surfactant (viscosity 1 cps) was applied to the above-mentioned equipment by corrugation, and the coating roll was rotated in the reverse direction (EPDM hardness 30 °). Application is performed using a roll coater that uses a corrugated forward rotation pressure roll (EPDM hardness 70 °) and a doctor roll (aluminum), and then heat drying by far infrared radiation at 80 ° C for 5 minutes. It was As a result, a coating film having a uniform wet film thickness of 10 μm could be obtained. At this time, the occurrence of pinholes, uneven coating,
Almost no deterioration in transparency was observed, and a good performance was obtained.

Specific dimensional specifications of the above apparatus (see FIGS. 1 to 3) will be given below. Maximum outer diameter of coating roll (4): 300mm Minimum outer diameter: 280mm Rotation speed (reverse): 80r.pm Maximum outer diameter of pressure roll (5): 300mm Minimum outer diameter: 280mm Rotation speed: 10r.pm Doctor roll ( 6) Maximum outer diameter: 300mm Minimum outer diameter: 280mm Rotational speed: 80r.pm Pressing force by coating roll (4): 3kgf / cm ² Corrugated plate conveying speed (extrusion molding speed): 10m / min Corrugated plate (N ) Average plate thickness: 0.7 mm Wave pitch: 32 mm Valley depth: 9 mm Example 2 To the above corrugated plate with PMMA (polymethylmethacrylate) as toluene as a weather-resistant coating liquid and benzotriazole as an ultraviolet absorber. Paint solution (viscosity 3 cp)
The coating of s) was performed with the above apparatus. At this time, pinholes, uneven coating, orange peel, and deterioration of transparency were hardly seen.

Example 3 The above corrugated plate was coated with a cationic surfactant as an antistatic agent using the above apparatus, and as a result, foaming at the time of coating,
It was possible to obtain a uniform film thickness without introducing air bubbles into the coating film. Comparative Example 1 The polycarbonate resin transparent corrugated board of Example 1 was sprayed with the antifogging agent of Example 1 by a spray gun with a nozzle diameter of 1.0 mm to give an injection amount of 10c.
Coating was performed at c / m ² and immediately thereafter, drying was performed at 80 ° C. for 5 minutes.
As a result, numerous pinholes were generated on the surface of the coating film due to air bubbles, the smoothness of the coating film surface was lost, and the persistence of the antifogging effect was significantly reduced.

Comparative Example 2 The weather-resistant coating liquid of Example 2 was applied to the corrugated plate using the spray gun of Comparative Example 1. As a result, the corrugated plate temperature is 50 ° C.
Due to the high temperature, the spray adhered to the corrugated plate was dried before leveling on the coated surface, which became white after drying and significantly reduced the light transmittance.

Comparative Example 3 The corrugated plate was coated with the antistatic agent of Example 3 using a roll coater composed of a flat roll (urethane resin hardness 10 °) and a doctor roll (aluminum) not corrugated. I went. In this method, a flexible roll is used to transform the roll shape into a corrugated plate shape for application.

As a result, since the roll is deformed and the coating is performed while increasing the touch pressure between the roll and the corrugated plate, pressure is particularly applied to the crests of the corrugated plate, the coating film thickness is thin at the crests, and the troughs are more It's thickened. Only a thin film having a variation in film thickness was obtained (max wet 2 to 3 μm), and streaks due to bubbles were generated in the valleys of the corrugated plate, and traces remained after drying. These defects also affect the surface performance and appear as variations in the charge amount. Table 1 shows data specifically showing the above results.

[0033]

[Table 1]

[0034]

According to the present invention, the corrugated sheet is formed while the coating roll is rotated by preliminarily forming the roll surface of the coating roll to have an uneven shape corresponding to the corrugated shape of the corrugated sheet at a specific position. The coating liquid can be applied to the corrugated plate substantially uniformly without being restricted by the viscosity property of the coating liquid.

Further, the primer coating liquid is pre-applied by the pre-coating roll in the same manner as in the case of coating the above-mentioned coating liquid (main coating liquid), whereby the adhesion of the coating liquid (main coating liquid) is further improved. To be enhanced.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of a coating device for a synthetic resin corrugated plate according to the present invention.

FIG. 2 is an explanatory view of the structure around an integral extrusion molding line of a corrugated sheet that is guided to a transport line of an example.

FIG. 3 is a perspective view of a roll coater of the embodiment.

[Explanation of symbols]

1 Synthetic resin corrugated sheet coating device 2 Conveyor line 3 Roll coater 4,14 Coating roll (upper coating roll) 5,15 Pressure roll (lower pressure roll) 6,16 Doctor roll 13 Front roll coater N Synthetic resin corrugated plate S Integral extrusion molding line for corrugated sheet T Main coating liquid P Primer coating liquid

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B05D 7/00 K 7717-4D 7/04 7717-4D

Claims (9)

[Claims] 1. A pair of corrugated plates made of synthetic resin is conveyed substantially horizontally in a direction perpendicular to the wave direction thereof, and the corrugated plate and the coating liquid have an uneven surface in advance corresponding to the corrugated shape of the corrugated plates. A method for applying a synthetic resin corrugated sheet, which comprises supplying between an upper coating roll and a lower pressure roll to apply. 2. The coating method according to claim 1, wherein in the pair of coating rolls, the upper coating roll is rotated in the direction opposite to the corrugated plate transport direction, and the lower pressure roll is rotated in the forward direction and the corrugated plate transport direction. . 3. The coating method according to claim 1, wherein the coating liquid is a low viscosity liquid diluted with water and / or an organic solvent. 4. The coating method according to claim 3, wherein the coating liquid contains a surfactant. 5. The coating method according to claim 1, wherein the coating liquid comprises a primer coating liquid and a main coating liquid, and the coating is performed in two steps. 6. A conveyor line for conveying a synthetic resin corrugated sheet substantially horizontally in a direction perpendicular to the wave direction thereof, and a roll axis in the wave direction of the corrugated sheet, and having a corrugated surface corresponding to the corrugated shape. A pair of upper coating roll and lower pressure roll having,
A coating device for a synthetic resin corrugated sheet, comprising a doctor roll for supplying a coating liquid provided in contact with the upper coating roll, and a drive means for driving the transport line, the upper coating roll, the lower pressure roll, and the doctor roll. 7. The coating apparatus according to claim 6, wherein the transport line is provided on an extension of the integral extrusion molding line for the synthetic resin corrugated sheet. 8. The method according to claim 6, wherein the upper coating roll is rotated in the direction opposite to the conveying direction of the synthetic resin corrugated sheet, and the lower pressure roll is rotated in the forward direction relative to the conveying direction of the synthetic resin corrugated sheet. 7. The coating device according to 7. 9. An upper surface of the pair of upper coating rolls and lower pressure rolls according to claim 6, which has a roll shaft in the wave direction of the corrugated plate made of synthetic resin and has an uneven surface corresponding to the wave shape. 7. A pair of upper coating rolls / lower pressure rolls are provided, and further, a doctor roll for supplying a coating liquid for primer is provided in contact with the upper coating roll of the other pair of upper coating rolls / lower pressure rolls. This coating liquid supply doctor roll is a coating roll for synthetic resin corrugated sheet coating equipment.