JP3258456B2 - Painting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a continuously running steel strip ( hereinafter referred to as a steel strip).
"Web" coating method of forming a continuous coating on the coated surface of the called), in particular slit-shaped opening is shaped in the width direction of the web
The present invention relates to a coating method for forming a coating film on a steel strip coating surface by using a coating liquid discharged from a formed slit nozzle.

[0002]

BACKGROUND ART In scan <br/> slit-like Nozurukota forming a coating film on conventional web coating surface, web coating which is an object to be painting material
Air coming entrained to the surface it is, in order to bring the bubble-like defects on the coating film is caught under the coating film, JP 62-18696
6 and JP-A-48-32923 have taken measures. That is, for example,
In Japanese Patent Application Laid-Open No. 2-186966, as shown in FIG. 7, a gas such as CO ₂ gas, which is easily absorbed by a solvent of a coating liquid for forming a coating film, is sprayed onto a web coating surface immediately before coating.
Replaced with soaking air. That is, in FIG.
The web which is an object to be painting was 102 bar click up roll, 103 is a slit nozzle, 104 paint supply pump, 105 Coating Solution, 106 Namanurimaku blown out from the slit nozzle 103, 107 is coated on the web 101 A later coating film, 108 is a decompression chamber, 109 is a gas nozzle for supplying air replacement gas such as CO ₂ gas, and 110 is a decompression pump.

[0003] In Figure, the vacuum chamber 108 an air layer coming entrained to the web 101 coated surface, to some extent the web
After the coating film 101 is peeled off from the painted surface, a gas such as CO ₂ gas which is easily absorbed by the raw coating film 106 is blown out from the gas nozzle 109, and the contact portion 111 of the raw coating film 106 to the web 101
Then, the air layer is replaced with the supply gas such as the CO ₂ gas.

[0004]

The above conventional web coating method has the following problems to be solved.

Namely, in the method of JP 62-186966, in order to prevent the entrainment phenomenon of the coating film of air entrained in the web coming traveling as described above, the absorption solvent of the paint Although the entrained air is replaced by a gas (e.g., CO ₂ gas) which is easily removed, this replacement gas is also caught under the coating by about 10 μm in gas phase layer thickness. the, not be absorbed in a solvent of paint liquid and partly there is a problem that results in a bubble defect remained.

[0006] Further, in the method of JP-A-48-32923, by blowing a mixed gas of steam and air in water or solvent to the web of the painting surface, condensed water or solvent of the coated surface, By improving the wettability with the coating liquid ,
Air bubbles are less likely to occur due to entrainment of air, but the entrained air is replaced with a mixed gas of water or solvent vapor and air. And there is a risk of causing defects due to entrainment of air bubbles in the coating.

[0007] Also, Oite the method shown in this publication, in order to adjust the liquid film thickness to condense on the web coated surface, the temperature of the web coated surface, each of the temperature of the liquid temperature and the suction air for evaporation However, since three types of temperatures have to be adjusted, there is a problem that the operation becomes complicated.

[0008] Since the present invention is to solve the above problems, weather
After almost complete removal of the air of the probe painted surface, the web coated surface
An object of the present invention is to provide a coating method for performing coating of a coating.

[0009]

The object of the present invention is to provide a coating method described in the following (1) and (2) as means for solving the above-mentioned problems.

(1) Slip the painted surface of the steel strip running continuously.
The door nozzle placed opposite, strip coating a paint solution in the width direction of the steel strip Ru discharged from the nozzle of the <br/> slit nozzle is open mouth
In the coating method of coating an arbitrary thickness instrumentation surface, said Sri
The heating means from the installed nozzle on the upstream side of Tsu bets nozzle
Heated and gaseous temperature-vapor pressure characteristics differ
Spraying a mixed vapor of multiple organic solvents onto the steel strip painted surface
After contacting and condensing, paint from the slit nozzle
A coating method characterized by discharging and applying a liquid to a steel strip coating surface .

(2) In the coating method according to claim 1,
A suction means is provided further upstream from the installation position of the nozzle.
Only, painting wherein the cause Aspirate the air layer entrained to the steel strip coated surface which runs by the suction means.

[0012]

The present invention is configured as described above and has the following effects.

[0013] (1) In the configuration (1), the installation position of the slit bets nozzle for applying to discharge the paint liquid to the steel strip <br/>
Painted surfaces of the steel strip to more traveling on upstream side, as the heating means
Is heated by a heater which is in gaseous contact with mixed vapor of an organic solvent, after condensed, coating from the slit nozzle
The coating liquid is discharged to form a coating film .
So-called temperature-steam pressure characteristics where the steam pressure differs with temperature
Of the coated surface of the steel strip with a mixed gas (vapor) in different organic solvents, in advance an organic solvent is condensed, the liquid film is formed, the coating
Postal liquid and wettability between the steel strip coated surface is increased, as well as expel the air, since not remain as a gas from itself, air bubbles are not mixed into the coating film.

(2) In the configuration of the above (2), in addition to the configuration of the above (1), the mixed gas of the organic solvent is discharged to the steel strip coating surface , and is sucked further upstream from a portion where the mixed gas is contacted and condensed.
The means provided to the intake pull the air layer to accompany the steel strip coated surface
Therefore, in addition to the effect of the above (1), the chance of air bubbles entering the coating film is further reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First and second embodiments of the method of the present invention will be described with reference to FIGS. In addition, the same reference numerals are given to the same devices and members as those used in the conventional example or the previous embodiment, and the description will be omitted unless necessary. Further, the description of the same method as that of the previous embodiment will be omitted unless necessary.

(First Embodiment) FIGS. 1 to 3 show a first embodiment according to the coating method of the present invention.
This will be described below.

FIG. 1 is a schematic side sectional view of a coating apparatus for coating a web coating surface used in the method of the present embodiment, and FIG.
FIG. 3 is an enlarged view of the vicinity of the slit nozzle 3 and the organic solvent gas supply chamber 7, and FIG. 3 shows the temperature of each organic solvent used in the coating apparatus of the present embodiment.
Degree - is a graph showing the vapor pressure properties.

[0018] In FIGS. 1 and 2, the web (steel strip) 1 is the painting product, 2 need web 1 is flattened at painting
Therefore , a backup roll for securing the flatness, 3 is a slit nozzle for applying the coating liquid 4 to the coating surface of the web 1, 4 is a coating liquid for coating containing an organic solvent or the like, and 5 is a slit nozzle 3 6 is a coated film obtained by solidifying the raw film 5 after coating on the web 1, 7 is an organic solvent gas for bringing the mixed gas of the mixed organic solvents 12 and 13 into contact with the web 1 A supply chamber, 7a is a wall of the organic solvent gas supply chamber 7, 8 is a nozzle for supplying an organic solvent mixed gas to the organic solvent gas supply chamber 7, 9 is a pipe, and 10 and 11 are for storing the organic solvents 12 and 13, respectively. Tank, 1
2 and 13 are supplied to the organic solvent gas supply chamber 7 and the web 1
The organic solvents 14 and 15 condensing upon contact with the organic solvents 12 and 1 stored in the tanks 10 and 11 respectively.
A heater for heating 3 to gaseous vapor ; 16 a pipe; 17 a gas mixer for mixing the gases of the respective organic solvents 12 and 13;
Heater for preventing condensation of the 2, 13 gas, 27 is a thin film of an organic solvent 12.

Next, a description will be given of a coating method according to the first embodiment when coating is performed using the coating apparatus having the above-described configuration.

The web 1 of the painting material is attached backup roll 2 wound while entrained air layer on the coated surface, into the organic solvent gas supply chamber 7. The organic solvent gas supply chamber 7, as the temperature of the above - mixed gas consisting of vapor pressure characteristics of two different types of organic solvent 12, 13 are supplied from a nozzle 8 for gas supply, painted surfaces of the web 1 And the organic solvent 12, 13
There condenses to form a thin film 27 of the organic solvent 12, 13 shown in FIG. 2 the web 1 coated surface. By forming the thin films 27 of the organic solvents 12 and 13, the raw coating film 5 supplied from the slit nozzle 3 can maintain good wettability with the web 1, so that the coating film 6 can be formed without involving air. One web coating
It can be formed on the mounting surface.

[0021] Incidentally, the thickness of the thin film 27 of the organic solvent 12 and 13 before painting Ru is formed into web 1 coated surface on critical, 0.1 to 10 [mu] m is appropriate. That is, when the film thickness is 10
When the thickness is more than μm, the loss of the solvent increases, and the load on a drying furnace (not shown) increases. Conversely, it has been experimentally found that when the film thickness is 0.1 μm or less, there is a portion where the thin film 27 does not adhere to the web 1 locally.

Therefore, 0.1 to 10 μm of organic solvent 1
In order to stably obtain the condensed thin film 27 of 2, 13, the coating surface temperature of the web 1 is measured in advance, and heating by the heaters 14, 15 is performed so as to match the coating surface temperature of the web 1. System
It becomes possible only by controlling the composition of the mixed gas of the organic solvents 12 and 13 by controlling the composition.

For example, when acetone and toluene are used as the two kinds of organic solvents 12 and 13,
Is stored in the tank 10 and the tank 11 as the organic solvent 13, respectively, and the heating of the heater 14 and the heater 15 are respectively adjusted to adjust the composition of the mixed gas composed of the organic solvents 12 and 13. Change.

[0024] That is, as shown in FIG. 3, acetone and Torr
It has a different temperature-vapor pressure characteristic from E
Since acetone has a high vapor pressure and toluene has a low vapor pressure, if the coating surface temperature of the web 1 is higher than the standard,
The input to the heater 14 of FIG.
By increasing the input to the mixture, the toluene component in the mixed gas is increased, and the same condensed film thickness as at the reference temperature can be obtained. Conversely, when the coating surface temperature of the web 1 is lower than the reference, the input to the heater 14 is increased, and the input to the heater 15 is reduced, so that the acetone component in the mixed gas is increased. The same condensed film thickness as in the case of the reference temperature can be obtained.

The mixed gas of the organic solvents 12 and 13 is prevented from condensing on the surfaces of the pipes 9 and 16, the nozzle 8 for supplying the mixed gas and the wall 7 a constituting the organic solvent gas supply chamber 7 and the slit nozzle 3. , They need to be heated above about 100 ° C. The heater 25 is used for that purpose.

The above-mentioned example is a case where acetone and toluene are used as a mixed vapor of an organic solvent. However, three kinds of temperature such as acetone, toluene and xylene are used as a mixed vapor.
The same operation and effect can be obtained by using a mixed vapor composed of organic solvents having different degree-vapor pressure characteristics .

(Second Embodiment) FIGS. 4 to 6 show a second embodiment of the coating method according to the second aspect of the present invention.
This will be described below.

FIG. 4 is a schematic side sectional view of a coating apparatus used in the method of this embodiment, and FIG. 5 is an organic solvent gas supply chamber 7 of FIG.
The air suction chamber 18 enlarged view of the vicinity, FIG. 6 is a temperature of the organic solvent used in this embodiment - a vapor pressure characteristic diagram.

4 and 5, reference numeral 18 denotes an air suction chamber which is provided upstream of the organic solvent gas supply chamber 7 when viewed from the running direction of the web 1 and whose lower portion is close to the coating surface of the web 1. , 19 are air suction ports for communicating with a decompression pump 20 to suck air from the air suction chamber 18, and 20 is a negative pressure applied to the air suction chamber 18, and its painted surface accompanied by the web 1. A decompression pump for sucking and removing an air layer, a tank 21 for dissolving an organic solvent 22, an organic solvent 22 for forming a mixed gas with other organic solvents 12 and 13, 23
Is a heater attached to the bottom of the tank 21 for warming the organic solvent 22 and appropriately promoting the vaporization thereof. 26 is a schematic diagram showing the laminar air flow on the painted surface of the web 1,
8 is an organic solvent mixed gas flow schematically shown. Other configurations are the same as those in FIGS. 1 and 2 according to the first embodiment.

That is, the second embodiment differs from the first embodiment in that an air suction chamber 18 is provided on the upstream side of the organic solvent gas supply chamber 7 and that three types of organic solvents for mixed vapor are used. .

Next, a description will be given of a coating method according to a second embodiment in the case where the coating is performed using the coating apparatus having the above configuration.

[0032] By web 1 of the painting material is passed through the air suction chamber 18 under lateral <br/>, most of the air layer that is associated to the coated surface is sucked in the direction of the following air layer flow 26 Is painted
It peeled off from the surface.

Next, the web 1 is placed under the organic solvent gas supply chamber 7.
In this way , the entrained air remaining on the painted surface in a small amount is completely replaced by the mixed gas of the organic solvents 12, 13 and 22. This substitution mechanism is performed by an organic solvent mixed gas stream 28 flowing at high speed from the organic solvent gas supply chamber 7 to the air suction chamber 18 via the wall 7a .
The residual air layer is completely separated from the painted surface ,
Next, the web 1 enters the organic solvent gas supply chamber 7 consisting entirely of the mixed gas of the organic solvents 12, 13, 22.
Only the mixed gas of the organic solvents 12, 13 and 22 exists on the painted surface of.

The mixed gas of the organic solvents 12, 13, 22 constituting the gas phase of the organic solvent gas supply chamber 7 is produced as follows. That is, for example, three kinds of organic solvents 1 of acetone, benzene and toluene are used as the organic solvents 12, 13, and 22.
When preparing a mixed gas consisting of 2, 13, 22
Temperature of the organic solvents 12,13,22 - vapor pressure characteristics
Since the diagram is as shown in FIG . 6, each organic solvent 1
If the liquids 2, 13, and 22 are heated to 50 ° C., the pressure of these three types of mixed steam will be 760 Torr or more (about 930 Torr). Therefore, acetone was selected as the organic solvent 12, benzene was selected as 13, and toluene was selected as 22, and each of the heaters 14, 15, and 23 was heated to 50 ° C.
If heated, the inside of the pipe 16 is
After the gases 13 and 22 pass and are completely mixed in the gas mixer 17, they are blown into the organic solvent gas supply chamber 7 from the nozzle 8 through the pipe 9 at a pressure of about 900 Torr.

If the outer surface of the wall 7a of the organic solvent gas supply chamber 7 and the coating surface of the web 1 are kept at about 50 ° C., the mixed gas of the organic solvents 12, 13 and 22 does not condense on the web. Although the raw coating film 5 adheres to the lower surface of the raw coating film 5 while adhering to the coating surface, the mixed gas adhering to the coating surface of the web 1 is easily condensed into a liquid phase by the collision pressure when the raw coating film 5 collides with the web 1. However, it is assimilated with the organic solvent in the coating film 6 and does not remain as a gas at all.

In the second embodiment, 12,1 is used as the organic solvent.
Although three types of 3, 22 were used, the number is not limited to three, but may be two, or four or more. Further, the organic solvent used is not limited to acetone, benzene or toluene.

As described above, according to the first embodiment, the web 1
An organic solvent gas supply chamber 7 is provided on the upstream side of the slit nozzle 3 for blowing the coating liquid 4, and the mixed vapor of the organic solvents 12 and 13 is brought into contact with the coated surface of the web 1 and condensed. 4 as raw coating film 5 for web 1
Since it is discharged toward the painted surface and adhered to form the coating film 6, there is no opportunity for air to enter the coating film 6, and the mixed vapor (gas) of the organic solvent is different from that of the conventional CO ₂ gas or the like. On the contrary, since it becomes condensed and liquid at room temperature and has an affinity for the organic solvent of the paint, it does not immediately melt and generate air bubbles, so that there is no problem that air bubbles and gas bubbles are entrained in the coating film 6. There is.

Further, according to the second embodiment, an air suction chamber 18 is provided further upstream of the organic solvent gas supply chamber 7 so that the air layer accompanying the painted surface of the web 1 is sucked and removed. Since it is exposed to the mixed gas atmosphere in the organic solvent gas supply chamber 7 on the downstream side, in addition to the advantages of the first embodiment, air bubbles are generated in the coating film 6.
This has the advantage of further reducing the chances of being caught in

[0039]

The present invention has the following effects because it is configured as described above.

(1) In the invention of claim 1 , a steel strip coating
Moving above flow side of the site for discharging a coating solution to Somen
Since a mixed vapor composed of a plurality of organic solvents is brought into contact with and condensed on the coated surface of the steel strip, the wettability between the coating liquid and the strip is improved, and the entrapment of air bubbles is prevented. Therefore, the coating of steel strip
A high quality painted surface without bubbles is formed on the mounting surface.

[0041] (2) In the invention of claim 2, it said (1) contacting the mixed vapor of the organic solvent, the condensation makes the steel strip
Further upstream side of the coated surface site is associated painted surfaces of the steel strip
Re that is provided with means for sucking the air layer, so to suck the air layer, even fewer opportunities to be caught with an air painted surfaces,
It is possible to form a better painted surface without bubbles.
I can .

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view of a coating apparatus used in a method according to a first embodiment of the present invention;

FIG. 2 is an enlarged view of the vicinity of an organic solvent gas supply chamber 7 in FIG.

FIG. 3 shows the temperature of each organic solvent used in the method of the first embodiment.
Vapor pressure characteristic diagram,

FIG. 4 is a schematic side sectional view of a coating apparatus used in the method according to the second embodiment of the present invention;

5 is an organic solvent gas supply chamber 7 and an air suction chamber 1 shown in FIG.
Enlarged view near 8

FIG. 6 shows the temperature of each organic solvent used in the method of the second embodiment.
Vapor pressure characteristic diagram,

FIG. 7 is a schematic side sectional view of a coating apparatus used for a conventional coating method.

[Description of Signs] 1 Web (band) 2 Backup roll 3 Slit nozzle 4 Paint liquid 5 Raw coating 6 Coating 7 Organic solvent gas supply chamber 7a Wall 8 Nozzle 9 Piping 10, 11 Tank 12, 13 Organic solvent 14, Reference Signs List 15 heater 16 pipe 17 gas mixer 18 air suction chamber 19 air suction port 20 decompression pump 21 tank 22 organic solvent 23, 25 heater 26 accompanying air laminar flow 27 thin film 28 organic solvent mixed gas flow

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Etsuro Hirai 4-2-2 Kannon Shinmachi, Nishi-ku, Hiroshima Sanritsu Heavy Industries, Ltd. Hiroshima Laboratory (72) Inventor Masahiro Sugihara 4--22 Kannon Shinmachi, Nishi-ku, Hiroshima City No. 7 Hiroshi Heavy Industries, Ltd.Hiroshima Laboratory (72) Inventor Yasuyoshi Takeoka 6-22, Kannon Shinmachi, Nishi-ku, Hiroshima City Inside Hiroshima Research Lab., Mitsubishi Heavy Industries, Ltd. (72) Ryoichi Nomi 4-5 Kitahama, Chuo-ku, Osaka City No. 33 Sumitomo Metal Industries Co., Ltd. (72) Inventor Yukihiko Noguchi 4-5-33 Kitahama, Chuo-ku, Osaka City Sumitomo Metal Industries Co., Ltd. (56) References JP-A-62-95173 (JP, A) JP-A-3-181368 (JP, A) JP-A-62-289264 (JP, A) JP-B-48-39802 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 1 / 26 B05C 5/02 B05D 3/00

Claims (2)

(57) [Claims] 1. A slit Roh <br/> nozzle disposed opposite to the coated surface of the steel strip traveling continuously, paint solution the slit <br/> Ru discharged from bets nozzle is open mouth steel strip width direction In a coating method of applying an arbitrary thickness to the steel strip coating surface, heated by a heating means from a nozzle installed on the upstream side of the slit nozzle ,
A gaseous temperature-vapor pressure mixed vapor of a plurality of organic solvents having different vapor pressure characteristics is sprayed onto the steel strip coating surface to contact and condense, and then the coating liquid is passed from the slit nozzle to the steel strip.
A coating method characterized by discharging and applying to a painted surface . 2. The coating method according to claim 1, wherein
Suction means is provided further upstream from the installation position of the nozzle,
The air layer entrained to the steel strip coated surface which runs by the suction means
Coating wherein the cause Aspirate.