JPH08266981A - Coating method and apparatus - Google Patents

Abstract

PURPOSE: To suppress the stripe trouble and thick or thin coating trouble generated in a coating start part and a splice part by supplying gas to a web so that the average collision speed to the web of the gas and the running speed of the web satisfy a specific condition. CONSTITUTION: A substitution chamber 12 is provided on the upstream side of the liquid contact part of coating solns S1 , S2 flowing down in a curtain like state and a web 1 and carbon dioxide is supplied as gas high in the solubility to the coating solns S1 , S2 from a gas supply source 13 and ejected to the web 1 from the slit 12a formed over the entire width region of the web to substitute the air accompanied by the web 1 with carbon dioxide. At this time, by adjusting the gap of the discharge slit 12a or the supply amt. of the soluble gas so that the average speed thereof satisfies formula, the accompanied air is perfectly substituted with the gas high in the solublility to the coating solns S1 , S2 . In the formula, V is the average collision speed to the web 1 of the gas and Cs is the running speed m/sec of the web 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to the continuous production of recording materials such as photographic light-sensitive materials such as photographic film and printing paper, photoengraving materials, pressure-sensitive recording papers, heat-sensitive recording papers and magnetic recording tapes. TECHNICAL FIELD The present invention relates to a coating method and a coating apparatus for coating various liquid substances on a strip-shaped support (hereinafter referred to as a web) that is running normally, and particularly thick coating / thin coating at a non-steady portion such as a coating start portion and a splice portion. The present invention relates to a technique for suppressing uneven defects similar to that, and further for partially causing streak defects, and achieving high-speed coating.

[0002]

2. Description of the Related Art Conventionally, as a technique for applying a liquid composition to a continuously running web, US Pat.
Slide coating disclosed in Japanese Patent Publication No. 33-8977, U.S. Pat. No. 3,508,947 (Japanese Patent Publication No. 49-2).
4133), curtain coating disclosed in Japanese Patent Publication No.
The extrusion coating method disclosed in Japanese Patent Laid-Open No. 12390/1993 is used.

In the above disclosed technique, an attempt has been made to increase the coating speed in the coating process, and one problem is a phenomenon called air entrainment. This is because the air on the running web surface is coated at the same speed. This is a phenomenon in which air flows into a point (hereinafter, referred to as a bead), so that air enters between the coating liquid and the web to generate bubbles. Due to this development, the performance of products such as photographic film and magnetic recording tape is significantly impaired.

As a method for suppressing the entrainment of air, a gas disclosed in Japanese Patent Publication No. 5-71307, which has a high solubility in a coating solution, such as carbon dioxide, is supplied to the entire width of the web and replaced with air. There is. On the other hand, when performing coating by the coating method as described above, as to thick coating portions and thin coating portions that occur at the coating start portion, (1) as disclosed in Japanese Patent Laid-Open No. 50-92328. A method of roughening the coating head portion, (2) JP-A-4-22586
A method of discharging the coating head portion as disclosed in Japanese Patent Laid-Open No. 4 (4), (3) a method of increasing the degree of pressure reduction at the coating head portion disclosed in Japanese Patent Laid-Open No. 1-258772.
(4) There are various measures such as a method of spraying a spray liquid onto a web immediately before coating, as in JP-A-52-31727.

In applying the coating, not only the continuous web 20 but also a plurality of webs may be applied continuously. In such a case, the two webs 20 are joined and conveyed continuously, but the joining part (splice part) is shown in FIG. 9 (a) showing the cross section of the splice part using the tape 21. To join. However, when coating is performed in this state, as shown in FIG. 9B, a gap such as the portion (a) where the coating liquid 22 is not coated may occur, and the bubbles generated in this portion may cause streak failure. It becomes a cause. As a countermeasure against such a streak failure or a coating failure such as thick coating or thin coating occurring on the downstream side of the joint, (5) the rear end of the joint as disclosed in JP-A-50-49338. Method for reducing or eliminating the step difference of (6)
A method for improving the wettability of a joint portion and its rear end portion as described in JP-A-5-142565, (7) JP-A-63-
A method for widening the bead gap as disclosed in Japanese Patent No. 80872 and a method for increasing the degree of reduced pressure as disclosed in (8) Japanese Patent Laid-Open No. 51-58437 have been proposed.

[0006]

However, the above-mentioned conventional techniques have the following problems. It is not easy to replace the air film (entrained air) with the gas. For example, with the disclosed gas supply amount, the coating speed (coating speed, that is, web transfer speed) is 150 (m).
/ Min), a thick coating portion, a thin coating portion, or a partial streak is generated particularly on the downstream side of the coating start portion and the web joining portion. Further, in the slide bead coating device having the decompression chamber, the disclosed device alone causes streak failure due to the inclusion of bubbles on both sides of the coating film as the decompression operation and the degree of decompression increase. Will occur.

Further, according to the method (1), there is a limit to speeding up, and at a high speed exceeding 150 (m / min), a thick film portion or a thin film portion is rather generated. According to the method (2), when the discharge treatment is partially performed, coating unevenness occurs,
According to the method of (3), it is effective for the occurrence of the pressure film portion and the thin film portion and the similar irregularity-like failure, but it is not effective for the muscle failure at the joint portion, and is rather the muscle failure due to the pressure reduction. Etc. will increase. Further, according to the method (4), dew condensation occurs and the coating property is greatly deteriorated. According to the method (5), a tape thickness of 100 μm or less cannot actually be used. The methods (6) to (8) are also effective for thick coating and thin coating failures, but are not particularly effective for muscle failures caused by bubbles trapped in the bead portion.

[0008] As described above, although the above-mentioned conventional solutions have some effects, they are not the fundamental solution to various problems associated with the speeding up of coating. The present inventors have found that the above-mentioned problems of the conventional technique can be solved by defining the following conditions.

1) The average impinging velocity of a gas having a high solubility on the web is defined in relation to the web traveling velocity, and the entrained air is separated and removed from the web surface. 2) For the decompression system, the inflow air determined by the pressure of the decompression system and the opening area formed by the gap between the decompression chamber and the backup roll forming the decompression system is completely converted into the gas. The supply flow rate required for replacement is regulated, and the gas supply device is arranged in the web width direction and at the pressure reducing system openings at both ends of the web.

3) The gas is supplied only to the coating head portion and the splice portion. 4) The direction of the air blown out of the gas is in the direction of web movement to prevent adverse effects on the bead and the curtain film, and to control the depressurization system when the gas is supplied or not. On the other hand, when the traveling direction of the web is 0 °, it is desirable that 90 ° <[gas jet wind direction] <180 °.

That is, the present invention clarifies a method and a device for replacing air entrained in a web with a gas having a high solubility, thereby achieving a high speed and at the same time, a streak failure and a thickness failure occurring in a coating start portion and a splice portion. The purpose is to solve problems such as coating or thin coating.

[0012]

Therefore, the present invention is to solve the above-mentioned problems of the prior art. The invention according to claim 1 relates to a continuously running web, immediately before coating the web. In the method of applying the coating liquid while replacing the entrained air with a gas having a high solubility in the coating liquid, the average collision speed of the gas with the web is V [m / sec], and the traveling speed of the web is C _S [ m / sec], V ≧ 3.5 ×
The gas is supplied to the web so as to satisfy the condition of C _S.

According to a second aspect of the present invention, in the method of applying the coating solution while maintaining the liquid bridge portion of the web and the coating solution under reduced pressure, a decompression chamber and a backup roll forming the decompression system. The opening area constituted by the gap is S [cm ² ] and the pressure of the pressure reducing system is P [mmA
q], and the supply flow rate of the gas is Q [l / min],

[0014]

[Equation 2]

It is configured to supply the supply amount Q defined by. Further, the invention according to claim 3 is configured such that the gas is supplied only to the application head portion or the splice portion. Further, the invention according to claim 4 is configured such that the gas is carbon dioxide.

According to a fifth aspect of the present invention, in a device for applying a coating liquid to a continuously running web, a supply device for supplying a gas having a higher solubility to the coating liquid than air to the web is used immediately before the coating. The structure is arranged at the full width direction position and both end positions of the web. In addition, claim 6
The described invention is configured such that the gas is carbon dioxide.

[0017]

According to the invention described in claim 1, when a highly soluble gas is supplied from the discharge opening provided on the upstream side in the running direction of the web and over the entire width direction of the web, the gas is supplied to the web. The average collision velocity and V [m / sec] are V ≧
By adjusting the opening width and the supply flow rate so as to satisfy 3.5 × Cs, a large dynamic pressure can be given to the web, and especially the coating speed is 150 [m / min].
The effect of replacing entrained air under the above high speed can be increased.

Here, Cs [m / sec] is the traveling speed of the web. According to the second aspect of the invention, with respect to the decompression system, the decompression chamber and the backup roll for supplying the gas to the entire region in the width direction of the web and both ends of the web to form the decompression system. Where S [cm ² ] is the opening area formed by the gap, P [mmAq] is the pressure of the depressurization system, and Q [1 / min] is the supply flow rate of the gas,

[0019]

(Equation 3)

By supplying a sufficient amount, the air flowing in from the side of the backup roll can be replaced with the gas, and the entrained air flowing into the bead portion is completely removed. It can be replaced with a gas having high solubility.
Therefore, the coating speed can be increased without causing defects such as streak failure, thick coating failure or thin coating failure. Claim 3
In the case where the supply of the gas is the coating start portion and the splice portion of the web as in the invention described above, it is possible to effectively replace the entrained air at the portion where various defects occur when the coating speed is increased. it can.

Further, from each of the discharge openings, the total supply amount Q defined by the above equation is supplied only to the discontinuous formation portion such as the coating start portion and the splice portion of the web, and the gas of the gas is supplied at other coating times. By stopping the supply or by supplying the gas with a supply amount smaller than the total supply amount Q, it is possible to reduce the use amount of the gas and increase the manufacturing cost of the product while increasing the coating speed. It can be reduced.

According to the invention of claim 4, since carbon dioxide is dissolved in the coating liquid by using carbon dioxide as the gas, bubbles are not generated in the beads, and further, it is the seam portion of the web. Since no bubbles are generated also in the splice portion, even when the web has many splice portions, it is difficult for a failure such as a streak to occur. Therefore, the productivity is improved and the cost can be reduced.

According to the fifth aspect of the invention, since the position for arranging the supply device for the gas having a higher solubility in the coating liquid than the air is defined, it is possible to reliably replace the entrained air. According to the invention of claim 6, in addition to the above-mentioned effect, since the gas replacing the entrained air is carbon dioxide, carbon dioxide is dissolved in the coating liquid, which may cause bubbles in the beads. Moreover, since bubbles are not generated in the splice portion which is the joint portion of the web, it is difficult for a failure such as a streak to occur. Therefore, the productivity is improved and the cost can be reduced.

[0024]

EXAMPLES The present invention will be described in detail below based on examples. FIG. 1 is a schematic cross-sectional view when the invention of claims 1 to 4 is applied to a two-layer curten coating device 3 (also referred to as a curten coater). Of course, this embodiment can also be applied to other extrusion coating apparatuses and slide bead coating apparatuses.

In the figure, the coating liquids S ₁ and S ₂ pass through the pockets 5 and the slits 6 that spread in the width direction to reach the slide surface 4, and the coating liquid flows down the slide surface 4 from the tip (lip) 10 of the coating machine. It is applied in the shape of a curl in the air onto the web 1. Here, the coating layer is two layers, but if it is three layers or more, it can be dealt with by adding a block.

A substitution chamber 12 is provided on the upstream side of the liquid contact part 11 between the coating liquid flowing down in the air in the shape of a curtain and the web 1, and carbon dioxide is used as a gas having a high solubility in the coating liquid from the gas supply source 13. A discharge slit 12a which is supplied to fill the replacement chamber 12 with the gas and is formed over the entire width of the web 1.
The air entrained in the web 1 is replaced with carbon dioxide by being ejected from.

At this time, the direction in which the gas is ejected from the discharge slit 12a is when the traveling direction of the web 1 is 0 ° with respect to the traveling direction of the web 1 in order to prevent the adverse effect on the curtain film. , 90 ° <[gas jet direction] <180 °. At this time, by adjusting the discharge slit gap or the supply amount of the soluble gas so that the average collision speed thereof satisfies V ≧ 3.5 × Cs −−−−−−−− (A), entrained air can be obtained. Is completely replaced with a gas having a high solubility in the coating liquid. As a result, the vicinity of the location where the web 1 is coated with the coating liquid is filled with a gas having a high solubility in the coating liquid. Therefore, even if a gas is caught between the web 1 and the coating solution at the coating location, it is immediately dissolved in the coating solution, so that the troubles seen in the coating start portion and the splice portion do not occur. .

2 and 3 are explanatory views when the inventions of claims 5 to 6 are applied to a slide bead coating device for three layers. Of course, the present invention is not limited to other extruders.
It can also be applied to a John coating device or a curtain coating device. 2 (a) and 3 are side sectional views of the coating device, FIG. 2 (b) is a top view thereof, and FIG.
FIG. 3 is a schematic perspective view of a main part.

In the same manner as the curtain coater in FIG. 1, the coating liquid flowing down the slide surface 4 reaches the lip 10 and is backed up through a coating bridge (liquid pool) called a bead here. -Applied on the web 1 which is run while being held by the reel 2. A decompression chamber 14 is provided near the bead portion and is set to a negative pressure from the outside air. Further, a substitution chamber 12 is provided on the upstream side of the web 1 adjacent to the decompression chamber, carbon dioxide is supplied from a gas supply source 13, and the substitution chamber 12 is filled with the gas.
A discharge slit 12 formed over the entire width of the web 1.
The air entrained in the web 1 is replaced with carbon dioxide by being ejected from a.

The direction in which the gas is ejected from the discharge slit 12a at this time is the same as in the case of the curtain coating method when the traveling direction of the web 1 is 0 ° with respect to the traveling direction of the web 1. 90 ° <[gas jet direction] <180 °. With this configuration, it is possible to suppress a decrease in the reduced pressure due to the inflow of the gas into the decompression chamber due to the dynamic pressure when the gas is ejected.

Further, not only the replacement chamber 12 but also the web 1
On the other hand, a pair of replacement chambers 15 are provided on both sides, and the gas is supplied from the gas supply source 13 and jetted from the discharge slit 15a to block the air flowing in from the gap with the backup roll 2. That is, even when the entrained air is replaced with the soluble gas in the replacement chamber 12, the air is fed from both sides due to the clearance between the backup roll 2 and the side of the decompression chamber 14 (arrow line in FIG. 2B). 2) flows in and the air entrainment phenomenon is prevented from occurring on both sides in the width direction of the web 1.

Here, it is effective if the discharge slit 15a is formed at least in the section from the discharge slit 12a to the bead forming position, and since it is not necessary to give dynamic pressure to this portion, the slit gap is It can be adjusted appropriately. However, it is necessary to supply a sufficient amount of air to shut off the inflowing air due to the pressure difference between the internal pressure of the decompression chamber 14 and the outside air, and the amount Q of the supply is related to the clearance between the backup roll 2 and the decompression chamber 14. When the total opening area determined is S (cm ² ) and the decompression degree of the decompression chamber 14 is P (mmAq)

[0033]

[Equation 4]

The total supply amount Q (l / mi
n) is required. That is, regarding the coating method having a reduced pressure system, it is necessary to adopt a method that satisfies the expressions (A) and (B). The shape of the device for discharging the soluble gas is not particularly limited, and, for example, a punch plate type can also be used.

Next, the results of comparison between the case of applying the embodiment and the prior art will be concretely described based on experimental examples. Experimental Example 1 (Coating liquid) Lower layer coating liquid: a silver halide emulsion containing a predetermined amount of coupler-dispersion, surfactant, sensitizing dye and the like. (Containing 5% by weight gelatin) Wet thickness: 50 μm Viscosity: 25 cp (35 ° C.) Upper layer coating solution: 5% by weight aqueous gelatin solution containing 0.2 g of anionic surfactant per liter of coating solution.

Wet thickness: 40 μm Viscosity: 30 cp (35 ° C.) (Coating conditions) Support: Gelatin subbed polyethylene terephthalate base (thickness 100 μm) Coating speed Cs: 200 m / min (Coating device) FIG. Curtain coating device shown (used in two-layer coating) (Gas supply device) Gas is supplied from the discharge slits provided at the positions along the width of the web shown in FIG.

Here, the collision velocity V of the gas jet flow was adjusted by changing the slit gap of the discharge slits provided at the positions in the full width direction of the web. (Gas Supply Amount) The collision speed V of the gas jet flow is also changed by changing the supply amount from the discharge slit in the full width direction.
Was adjusted. (Evaluation method of effect) The thickness of the coating starting portion was evaluated.

In the evaluation, the film thickness was calculated by the following formula, and the results are shown in Table 1 and FIG. Thickness (%) = {(maximum film thickness-normal film thickness) / normal film thickness}
× 100

[0039]

[Table 1]

It should be noted that, here, 20% or less is set as a pass value with a margin as an upper limit value that does not cause an undried portion. Experimental Example 2 (Coating liquid) Lower layer coating liquid: a silver halide emulsion containing a predetermined amount of coupler-dispersion, surfactant, sensitizing dye and the like. (Containing 4% by weight gelatin) wet thickness: 35 μm viscosity: 15 cp (35 ° C.) intermediate layer coating solution: 5% by weight gelatin aqueous solution.

Wet thickness: 35 μm Viscosity: 30 cp (35 ° C.) Upper layer coating liquid: 5% by weight gelatin aqueous solution containing 0.2 g of anionic surfactant per liter of coating liquid.

Wet thickness: 35 μm Viscosity: 30 cp (35 ° C.) (Coating conditions) Support: Gelatin subbed polyethylene terephthalate base (thickness 100 μm) Coating speed Cs: 200 m / min Decompression degree p: -30 mmAq ( gap area of the coating apparatus) used in Suraidobi ─ de application device (three-layer coating shown in FIG. 2) backplate ─ up side (FIG. 3L _B): 1.50c
Gap area on m ² side plate side (Fig. 3Ls): ~ 0.46
cm ² (× 2) (Gas supply device) Gas is supplied from the discharge slits 12a provided in the web widthwise position shown in FIG. 2 (c) and the discharge ports 15a provided on both sides of the web shown in FIG. 2 (c). To do.

Here, the collision velocity V of the gas jet flow was adjusted by changing the slit gap of the discharge slits provided at the position in the full width direction of the web. (Gas supply amount) The supply amount from the discharge port 15a is 10
The discharge slit 12a is 0 l / min in the entire width direction.
The amount of supply from was adjusted. (Evaluation of Effect) A seam was formed from a mat tape having a thickness of 50 μm, and the number of occurrence of muscle failure was evaluated when the seam was applied.

However, the average value of 10 seams applied was evaluated as a representative value. The results are shown in Table 2 and FIG.
Shown in

[0045]

[Table 2]

The gas supply amount here is the supply amount from the discharge slit in the full width direction. Experimental Example 3 (Coating liquid) Same as Experimental Example 2. (Coating conditions) Basically the same as in Experimental Example 2, coating speed Cs
Was increased to 300 m / min. (Coating device) The same as in Experimental Example 2. (Gas supply device) The same as in Experimental Example 2. (Gas supply amount) Same as in Experimental Example 2. (Evaluation method of effect) The same as in Experimental Example 2, Table 3 and FIG.
The results are shown in.

[0047]

[Table 3]

The gas supply amount here is the supply amount from the discharge slit in the full width direction. Experimental Example 4 (Coating liquid) Same as Experimental Example 2. (Coating Conditions) Basically the same as in Experimental Example 2, but the degree of vacuum P was adjusted. (Coating device) The same as in Experimental Example 2. (Gas Supply Device) Basically, the same as in Experimental Example 2, and the slit spacing of 300 μm therein was adopted. (Gas supply amount) The supply amount from the discharge port 15a is 50
1 / min, and the supply amount from the discharge slit 12a in the full width direction was 3.3 l / mi per unit length of Experimental Example 2.
It was n · cm. (Evaluation method of effect) The same as in Experimental Example 2, and the results are shown in Table 4 and FIG.

[0049]

[Table 4]

The space area of the back plate is 1.5.
interval area cm ² side plate portions: ~0.46cm ² (×
2). Experimental Example 5 (Coating liquid) Same as Experimental Example 2. (Coating conditions) The same as in Experimental Example 2. (P = -30mmAq) (coating apparatus) is basically the same as the Experimental Example 2, it was adjusted back plate spacing (Figure 3L _B) and the side plate spacing (Figure 3L _S). (Gas supply device) The same as in Experimental Example 4. (Gas supply amount) Same as Experimental Example 4. (Evaluation method of effect) The same as in Experimental Example 2, and the results are shown in Table 5 and FIGS. 6 (a) and 6 (b).

[0051]

[Table 5]

Experimental Example 6 (Coating liquid) Same as Experimental Example 2. (Coating Conditions) Basically the same as in Experimental Example 2, but the degree of pressure reduction was set to P = −50 mmAq. (Coating device) Basically the same as in Experimental Example 2, except that the back plate portion spacing area (FIG. 3L _B ) is 2.55 cm ² and the side plate portion spacing area (FIG. 3L _S ) is 1.11.
It was adjusted to be cm ² . (Gas supply device) The same as in Experimental Example 4. (Gas supply amount) The supply amount from the discharge port 15a and the supply amount from the discharge slit 12a in the full width direction were adjusted. (Evaluation method of effect) The same as in Experimental Example 2, and the results are shown in Table 6 and FIGS. 8 (a) and 8 (b).

[0053]

[Table 6]

Experimental Example 7 (Coating liquid) Same as Experimental Example 2. (Coating conditions) The same as in Experimental Example 2. It is the same as (coating apparatus) basically Example 2, but the interval area of the back plate side gap area of 1.05 m ² and the side plate side and 0.46 m ^2. (Gas supply device) The same as in Experimental Example 4. (Gas supply amount) The supply amount from the discharge port 15a is 50
The supply amount from the discharge slit 12a in the entire width direction was set to 3.3 l / min · cm per unit length.

Here, N ₂ gas was supplied for comparison in the sense of being compared with CO ₂ gas. (Evaluation method of effect) The thickness of the coating starting portion was evaluated. In the evaluation, the film thickness was calculated by the following formula and shown in Table 7.

Thickness (%) = {(maximum film thickness-normal film thickness)
/ Normal film thickness} × 100

[0057]

[Table 7]

[0058]

As described above, according to the first aspect of the present invention, when the highly soluble gas is supplied from the discharge opening provided on the upstream side in the running direction of the web and in the entire width direction of the web. , The average velocity V of the gas impinging on the web
A large dynamic pressure is applied to the web by adjusting the opening width and the supply flow rate so that [m / sec] satisfies V ≧ 3.5 × C _S (C _S is the traveling speed of the web). In particular, the effect of displacing the entrained air at a high coating speed of 150 [m / min] or more can be increased.

With this effect, it is possible to suppress coating failures such as thick coating and thin coating that occur particularly at the coating start portion and the downstream portion of the web joining portion, and further partially cause streak failure. According to the second aspect of the present invention, with respect to the decompression system, the decompression chamber and the backup roll which form the decompression system by supplying the gas to the entire area in the web width direction and both ends of the web are also provided. The opening area composed of intervals is S
[Cm ² ], the pressure of the pressure reducing system is P [mmAq]: When the supply flow rate of the gas is Q [l / min],

[0060]

(Equation 5)

By supplying a sufficient amount, the air flowing in from the side or the like can be replaced with the gas, and the entrained air flowing into the bead part is replaced with a gas having a high solubility. In addition, the coating speed can be increased. Further, in the invention as set forth in claim 3, in which the supply of the gas is performed by the coating start portion and the splice portion of the web, the entrained air of the entrained air can be effectively generated at a portion where various defects occur when the coating speed is increased. Replacement is possible, and if it is supplied only to the discontinuous formation part such as the coating start part and the splice part, the amount of the gas used is reduced while reducing the manufacturing cost of the product while increasing the coating speed. can do.

According to the fourth aspect of the invention, carbon dioxide is dissolved in the coating liquid, and even if there are many splice portions, streak formation can be prevented, productivity can be improved, and cost can be reduced. Further, according to the invention of claim 5, the supply device of the gas having a higher solubility in the coating liquid than the air is arranged at the predetermined position, so that the entrained air can be reliably replaced. In addition, claim 6
According to the invention described, carbon dioxide is dissolved in the coating liquid,
Even if there are many splice portions, it is possible to prevent streaks, improve productivity, and reduce costs.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a two-layer curtain coating device according to this embodiment.

FIG. 2 is an explanatory view of a slide bead coating device for three layers in the present embodiment.

FIG. 3 is an explanatory diagram of a slide bead coating device for three layers in the present embodiment.

FIG. 4 is a diagram showing experimental results in this example.

FIG. 5 is a diagram showing experimental results in this example.

FIG. 6 is a diagram showing experimental results in this example.

FIG. 7 is a diagram showing experimental results in this example.

FIG. 8 is a diagram showing experimental results in this example.

FIG. 9 is a diagram showing a coating state in a conventional example.

[Explanation of symbols]

1 Web 2 Backup Roll 4 Sliding Surface 5 Pocket 6 Slit 7 Bead 9 Coating Film 10 Lip 12 Displacement Chamber 12a Discharge Slit 13 Gas Supply Source 14 Decompression Chamber 15 Displacement Chamber 15a Discharge Slit L _B Back Plate Interval L _S Side Plate Interval S ₁ , S ₂ , S ₃ coating liquid

Claims (6)

[Claims] 1. A method for applying a coating solution to a continuously running web while replacing the entrained air of the web with a gas having a high solubility in the coating solution immediately before the application, wherein the gas is applied to the web. When the average collision speed is V [m / sec] and the traveling speed of the web is C _S [m / sec], the gas is supplied to the web so that the condition of V ≧ 3.5 × C _S is satisfied. A coating method characterized by: 2. A method of applying the coating solution while holding the liquid bridge between the web and the coating solution under reduced pressure, wherein an opening area formed by a gap between a depressurizing chamber forming the depressurizing system and a backup roll is provided. S [cm ² ], the pressure of the decompression system is P [mmAq], and the supply flow rate of the gas is Q [l /
min], then, The coating method according to claim 1, wherein a supply amount Q defined by is supplied. 3. The coating method according to claim 1 or 2, wherein the gas is supplied only to a coating head portion or a splice portion. 4. The coating method according to claim 1, wherein the gas is carbon dioxide. 5. A device for applying a coating liquid to a continuously running web, wherein a supply device for supplying a gas having a solubility to the coating liquid higher than that of air to the web is provided at a full width direction position of the web immediately before coating and both end positions of the web. A coating device characterized by being provided. 6. The coating apparatus according to claim 5, wherein the gas is carbon dioxide.