JPH07256200A - Coating applying method - Google Patents

Abstract

PURPOSE:To provide a coating applying method which adjusts a coating liquid to a specific coating quantity by metering scrapers after excessively supplying the coating liquid onto a shielded edge web and with which the effective width of the coating liquid is obtainable and there are no drying defects by the liquid pools at the edges of a resin. CONSTITUTION:After the coating liquid is excessively supplied to the continuously traveling web 5, the spread of the coating width of the coating liquid on the web 5 is prevented by the pressuring air ejected out of nozzles 1 installed on the coated surface side just before the metering bars 2. As a result, the edges of the web 5 are stably provided with the parts where the coating liquid is not substantially applied. The contamination of transporting rolls after a drier by the defective drying arising from the liquid pools and the blocking fault after taking up are thus prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hydrophobic polyolefin resin coated paper used for photographic printing paper, sublimation type thermal transfer paper, ink jet paper, special printing paper, etc.
Regarding the method of applying the coating liquid to the hydrophobic polyolefin resin coated paper (hereinafter referred to as "shield edge base") whose both edges are formed of only the front and back resin layers, refer to the edge of the shield edge base in detail. The present invention relates to a coating method in which a portion on which the coating liquid is not substantially coated is provided.

[0002]

2. Description of the Related Art Conventionally, a support coated with a hydrophobic polyolefin resin has been supplied to a subsequent coating step by melt-coating the base paper with the polyolefin resin and then slitting the base paper into a predetermined product width. However, in recent years, it has become necessary to manufacture a shield edge base in which the edges of the base paper are sealed with a polyolefin layer on the front and back sides for the purpose of countermeasures against paper dust contamination in the coating process, and the reduction and reuse of waste. It's coming.

A support coated with a hydrophobic polyolefin resin is usually provided with a back coat layer for improving curling performance and imparting antistatic property.
As an example of the method of applying the back coat layer, there is a method of applying to a continuously running strip-shaped flexible support (hereinafter abbreviated as "web") with a metalling bar such as a wire bar.

In this coating method, the width of the coating liquid after being measured on the web is wider than the width of the coating liquid supplied to the web due to the action of the measuring means by the metalling bar and the surface tension of the coating liquid. When the tension in the width direction of the web when measuring the coating liquid is not uniform and the tension of the edge is low,
The edges are partially thickened.

In the shield edge base, since the base paper is completely covered with resin, a portion (hereinafter, abbreviated as "resin ear") formed only by the polyolefin resin layer at the edge portion is
There is a problem that the thickness is thinner than the part containing the base paper, the rigidity is low, and the base paper is not stiff. Therefore, after measuring the coating liquid by the metering bar, excess coating liquid or liquid pool was generated, which resulted in poor drying of this portion, resulting in contamination of rolls after the dryer and blocking failure after winding. In the past, as a countermeasure against this, excessive drying conditions had to be set in the drying step after coating, leading to a reduction in energy efficiency.

As a method of removing the thick coating on the edge,
As described in U.S. Pat. No. 2,899,339, a diluting liquid or a jet stream of a solvent or a spray liquid is supplied from the outer peripheral portion of a double-structured L-tube, and suction removal is performed together with the coating liquid from the central portion. The method has been reported. In addition, JP-A-56
In Japanese Patent Publication No. 73579 and Japanese Utility Model Publication No. 60-49949, a method of suction-removing a thick coating portion is described in almost the same manner. However, in these methods, when the position of the suction nozzle is outside the position of the edge portion of the web, the coating liquid goes around the web and deteriorates the quality of the product. In addition, it was impossible to completely eliminate the liquid pool in the resin edge portion corresponding to the edge portion of the base paper by the conventional method.

[0007] As a method of eliminating the thick coating portion, the actual construction of Sho 63-
Japanese Patent No. 136765 discloses a processing device having a function of cleaning a backup roll. Further, Japanese Patent Application Laid-Open No. 5-59697 discloses a device for ejecting a coating liquid with pressurized air or humidified air toward both edges to remove the thick coating portion. However, when it is applied to the shield edge base, it is unavoidable that the cleaning liquid collects in the resin edge portion corresponding to the edge portion of the base paper, which leads to poor drying of the resin edge portion and reduces operating efficiency.

Further, in order to prevent the resin coating from being thickly coated without removing a part of the coating liquid on the web,
A method of regulating the width of the coating liquid supplied to the web is considered so that the width of the coating liquid obtained after being measured by the metering bar is equal to or less than the width of the web. However, in this method, the coating width varies depending on the amount of the coating liquid supplied to the web, and a stable predetermined coating width cannot be obtained, resulting in lack of operational stability.

[0009]

SUMMARY OF THE INVENTION The present invention is a coating method in which a coating liquid is excessively supplied onto a shield edge strip-shaped flexible web, and then a predetermined coating amount is adjusted by a metering bar. An object of the present invention is to provide a coating method capable of preventing the resin from spreading to the ears, leaving uncoated portions on the resin ears stably, and obtaining an effective coating width in a stable manner.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a continuously running strip-shaped flexible support having both surfaces coated with a hydrophobic polyolefin resin, both edges of which are formed only by the front and back polyolefin layers. In a coating method in which the coating liquid is excessively supplied to the shield edge base and then a predetermined coating amount is measured with a metalling bar, the position is located just before the metalling bar and on both edges of the support. This can be achieved by a coating method characterized in that pressurized air is jetted toward the center of the support from a nozzle provided. Further, in the present invention, the pressurized air of the solving means has a relative humidity of 40 to 90.
% Humidified pressurized air, the amount of pressurized air supplied is 1 to 20 liters per minute, and the clearance between the nozzle outlet and the metering bar is 0.5 to 2.0.
mm, and the effect is particularly remarkable when the clearance between the nozzle outlet and the web is 0.5 to 2.0 mm.

The details of the present invention will be described below.
FIG. 1 is a side view showing an example of a metalling unit according to the configuration of the present invention. The air blown out by the pressurized air blowing nozzle 1 installed at the upstream side of the metering bar 2 in the web running direction prevents the spread of the coating liquid on the edge of the web. A stable unpainted portion is formed on the web. The pressurized air blowing nozzle according to the present invention may have any shape. In order to suck and remove the coating liquid particularly efficiently, it is preferable to use a nozzle whose tip has a diameter of about 1.0 to 5.0 mm. If the diameter of the pressurized air blowing nozzle is smaller than 1 mm, the effect as an air blade becomes smaller,
It becomes difficult to make the unpainted part stably. Also,
When the nozzle diameter exceeds 5 mm, the wind velocity at the nozzle outlet becomes small, and the uncoated width becomes uneven. The nozzle outlet may have a slit shape or a circular shape.

The supply amount of the pressurized air can be arbitrarily set by the coating liquid, but in order to prevent uneven coloring and to stabilize the quality and the operation, it is preferably in the range of 1 to 20 liters per minute, particularly preferably 5 to 5. It is better to adjust the range to 15 liters.

As the pressurized air, normally clean air may be used. From the viewpoint of not drying the metering bar and the coating liquid, the relative humidity of the pressurized air is important for stable operation and high quality, and the relative humidity is 40 to 90%, particularly preferably 50 to 80. It is good to adjust to%.

The position of the nozzle may be adjusted so as not to come into contact with the surface of the web, depending on the coating conditions. It should be noted that the nozzle is installed from the web running surface in order to ensure quality and stable operation.
It is particularly preferable to set the position to about 5 to 2.0 mm. or,
The clearance between the tip of the nozzle and the metering bar is particularly preferably set at a position of about 0.5 to 2.0 mm from the metering bar from the viewpoint of stable operation for stable uncoating.

FIG. 2 is a front view showing the installation position of the suction nozzle in the present invention. The nozzle 1 is installed immediately in front of the metering bar 2 along the line traveling direction. The nozzle 1 may be installed at any position, but for quality and stable operation, the installation position of the nozzle is preferably 0 from the end of the paper base, with the edge of the paper base of the web as the base point.
It is preferable to set it in the range of 10 mm inside, particularly preferably in the range of 0 to 5 mm from the end of the paper substrate. As a result, a preferable unpainted width by securing an effective coating width and a preferable drying by preventing the occurrence of liquid pool in the resin ear can be achieved more stably.

In order to carry out the coating method of the present invention more effectively and with high production efficiency, the coating liquid excessively supplied to the web is kept to a coating width narrower than the width of the web by a certain width. It is preferable to minimize the adhesion of the coating liquid to the resin ears by post-metalling. The coating width is determined by the coating conditions, but the width is 1000 mm.
When using the above web, it is 1 from the coating width after metalling.
It is preferable to narrow it by about 40 to 40 mm.

In the present invention, as a method of supplying the coating liquid to the web, an existing coating liquid supply device such as a gravure roll system, a roll coating system, a dipping system, a die system or the like can be used. As the metalling system, a system in which tension is applied to the metalling bar as shown in FIG. 1 or a rod coater system in which a coating rod is pressed against a web supported by a backup roll can be adopted. Further, as the metalling bar, either a plain coating rod or a wire bar wound with a wire can be used.

The polyolefin resin of the hydrophobic polyolefin resin-coated paper in the present invention includes low density polyethylene, high density polyethylene, linear low density polyethylene, homopolymers such as polypropylene, polybutene and polypentene, or ethylene-propylene copolymer. Copolymers composed of two or more kinds of olefins such as, and mixtures thereof can be used.

The coating solution used in the present invention is gelatin, polyvinylpyrrolidone, polyvinyl alcohol, sodium polystyrene sulfonate, styrene-maleic anhydride copolymer, styrene-acrylic acid ester-methacrylic acid copolymer, sulfate ester compound of polysaccharide. Aqueous solution of hydrophilic polymer compound such as, cellulose ester, polyvinyl acetal, polyvinyl chloride, polyvinylidene chloride, polystyrene, acrylic resin, an organic solvent solution of a phenol resin as a binder solution, if necessary, a surfactant, a pigment, Additives such as dyes and curing agents can be included.

The coating amount of the coating liquid in the present invention is usually
1 to 200 g / m ² when fed to the web, and 0.
It is about 1 to 80 g / m ² .

[0021]

As a method of applying a back coat to the web, a wire bar-based metering method has been applied. However, when the coating liquid is excessively supplied to the continuously running shield edge strip-shaped flexible web and metalling is performed, the resin ear portion of the web is thinner than the paper substrate, has low rigidity, and is not stiff. The ring bar alone could not remove the excess coating liquid. As a result, a liquid pool is liable to occur between the resin edge portion and the end portion of the paper substrate, and the transport roll is contaminated after the dryer due to poor drying of this portion, and blocking failure after winding occurs. Therefore, for the purpose of preventing the occurrence of liquid pool, the nozzle provided on the coating surface side and immediately before the metering bar prevents the spreading of the coating liquid and stabilizes the portion where the coating liquid is not substantially coated on the edge of the web. By this provision, it is possible to achieve the object of the present invention to prevent the contamination of the transport roll after the dryer due to poor drying and the blocking failure after winding.

[0022]

The present invention will be described in detail below with reference to specific examples, but the present invention is not limited to these examples. First, the evaluation method will be described. [Resin ear fluid pool] The following criteria were used to evaluate whether the coating fluid pooled in the resin edge portion of the edged seal base to cause defective drying. ◯: Good, no liquid pool was formed in the resin edge of the support. Δ: A slightly small liquid pool is formed, but it is within the usage limit. Poor: Unusable level due to large liquid pool and poor drying in the dryer. [Contact between nozzle tip and plain bar, edged seal base] Visually check that the tip of the nozzle does not come into contact with the plane bar or edged seal base, and that there are no quality defects such as scratches on the product. The following criteria were evaluated. ◯: Good without contact. ×: Unusable level due to failure points such as scratches on the surface of the product. [Drying of the plain bar] The state of the plain bar during the operation was visually observed and evaluated according to the following criteria. ◯: The plane bar does not dry and the coating solution can be applied stably. Δ: It is slightly dried and coating unevenness occurs slightly, but it is within the use limit. ×: The plane bar was greatly dried and uneven coating occurred,
Unusable level. [Condensation in the air pipe] The influence of jet air was evaluated according to the following criteria according to the condition of the condensation in the air pipe. ◯: Good, no problem. Δ: Condensation occurs, but jet air rarely affects the coated surface and is within the usage limit. ×: Moisture condensed in the pipe becomes water droplets and is ejected together with the air, causing a failure on the coating surface, which is unusable level. [Part not coated with coating liquid] After supplying the coating liquid, measure the state with a meta bar from the resin edge to see the edge shield base edge after coating the liquid, and check the following criteria. It was evaluated by. ◯: A part where the coating solution is not stably applied can be formed on the support. Δ: There is blur in the uncoated portion, but it is within the usage limit. X: The uncoated portion has a narrow coating width and is not practical, or is unstable and has a large width variation and is unusable.

(Examples 1 to 4 and Comparative Example 1) In a method of measuring a coating amount with a wire bar using a gravure system as a coating liquid supplying device for a web, resin ears each including 2 mm at both end portions, Shielded edge polyethylene coated paper with a width of 1000 mm using gelatin as a binder, solid content 10%, viscosity 10 cps, surface tension 30
Dyne / cm coating solution, coating speed 150m / min
With a gravure roll, the coating width shown in Table 1 is 10 g /
m ^{2 was} supplied, and coating was performed with a plain bar so that the coating amount was 2 g / m ² . At that time, as illustrated in FIGS. 1 and 2, a blowing nozzle was provided at a position shown in Table 1 inside from the end of the resin ear and immediately before the plenbar to perform coating. The results are shown in Table 1.

(Comparative Examples 2 to 4) Under the same conditions as in the above-mentioned examples, as shown in FIG. 3, a suction nozzle was provided immediately after the plane bar and coating was performed. The results are also shown in Table 1.

(Comparative Example 5) Under the same conditions as in Examples 1 to 4, as shown in FIG. 5, pressurized air from a blowing nozzle was jetted toward the outer side of the web for coating. The results are also shown in Table 1.

(Examples 5 to 10 and Comparative Examples 6 and 7) Under the same conditions as in Examples 1 to 4, the relative humidity of the pressurized air was changed to
The values were set to the values shown in Table 1, the amount of pressurized air supplied was 10 liters per minute, the coating liquid supply width was 900 mm, and the position of the blowing nozzle was 10 mm from the ear. The results are shown in Table 1.

(Examples 11 to 15, Comparative Examples 8 and 9) Under the same conditions as in Examples 1 to 4, the amount of pressurized air supplied was changed to
The coating amount was set so as to be the amount described in Table 1, the relative humidity of the pressurized air was 80%, the coating liquid supply width was 900 mm, and the position of the blowing nozzle was 10 mm from the ear. The results are shown in Table 1.

(Examples 16 to 20, Comparative Examples 10 to 13)
Under the same conditions as in Examples 1 to 4, the clearance between the nozzle and the edge shield base or the plane bar was set at the interval shown in Table 1, the relative humidity of the pressurized air was 80%, and the supply rate was 10 per minute. Liter, coating liquid supply width 900
mm, the position from the ear of the blowing nozzle was 10 mm, and the coating was performed. The results are shown in Table 1.

[0029]

[Table 1]

By applying under predetermined conditions as in Examples 1 to 20 of the present invention, it is possible to stably form a portion on the edge of the shield edge base where the coating liquid is not substantially applied. it can. As a result, after measuring the coating liquid,
The product can be manufactured without causing the contamination of the paper roll after the dryer and the blocking trouble after the winding due to the excess of the coating liquid or the occurrence of the liquid pool.

In Comparative Example 1, when a suction nozzle is installed on the opposite side of the coating surface as shown in FIG. 3, a liquid pool is generated in the resin ear portion and poor drying occurs after the dryer, and the paper roll is contaminated. Or blocking occurred during product winding. In addition, the uncoated part is not stable. Further, in Comparative Example 2, when the pressurized air from the blowing nozzle was ejected toward the outer side of the web to apply the liquid as shown in FIG. 5, a liquid pool was generated as in Comparative Example 1, and the same result was obtained. become.

The relative humidity of the pressurized air in Comparative Example 3 was
When the relative humidity is less than 40%, the plane bar is dried, and as a result, streak-like quality failure occurs on the coated surface. Further, in Comparative Example 4, when the relative humidity exceeds 90%, dew condensation water droplets generated in the air pipe are ejected onto the application surface, resulting in quality failure on the application surface. Further, when the supply amount of the pressurized air is less than 1 liter per minute as in Comparative Example 5, a liquid pool occurs, and when it exceeds 20 liters per minute as in Comparative Example 6, the coating width fluctuates. ,
It is not possible to form a portion where the coating liquid is not stably applied.

Further, when the clearance between the nozzle and the edge shield base is set to less than 0.5 mm as in Comparative Example 7, contact occurs and a quality defect such as a streak occurs on the product surface. Conversely, Comparative Example 8 As described above, when it exceeds 2.0 mm, the effect of jetting is reduced, and a liquid pool occurs in the resin ear portion.
Further, when the clearance between the nozzle and the plane bar is less than 0.5 mm as in Comparative Example 9, the plane bar is dried due to contact and coating unevenness occurs, and when it is more than 2.0 mm as in Comparative Example 10, The effect of jetting is reduced, and a liquid pool occurs in the resin ear.

[0034]

According to the present invention, an effective coating liquid width can be obtained in a coating method in which a coating liquid is excessively supplied onto a shield edge web and then a predetermined coating amount is adjusted with a bar, and It is possible to provide a coating method that does not cause thick coating on the resin ear portion.

[0035]

[Brief description of drawings]

FIG. 1 is a side view of a metalling portion showing an example of an embodiment of the present invention.

FIG. 2 is a front view schematically showing an installation position of a blowing nozzle in the present invention.

FIG. 3 is a side view of a metalling portion showing an example of a comparative example, in which a nozzle is provided on the opposite side of the metabar.

FIG. 4 is a front view showing an installation position in a width direction of a web of a suction nozzle, which is an example of a comparative example, and the nozzle is right above a resin ear.

FIG. 5 is a front view showing an example of a comparative example in which pressurized air from a blowing nozzle is ejected to the outside of the web.

[Explanation of symbols]

1 Pressurized Air Blow Nozzle 2 Metalling Bar 3 Metalling Bar Support 4 Pressurized Air Supply Pipe 5 Web 6 Coating Liquid 7 Shield Edge Polyolefin Resin Coated Paper Resin Ear Part 8 Shield Edge Polyolefin Resin Coated Paper Base Part 9 Pressurized air outlet 10 Suction nozzle 11 Coating liquid suction pipe 12 Coating liquid suction port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B05C 11/06

Claims (4)

[Claims] 1. A coating solution is applied to a continuously running strip-shaped flexible support whose both surfaces are coated with a hydrophobic polyolefin resin, the both edges of which are formed only by the front and back polyolefin layers. In a coating method of excessively supplying and metering to a predetermined coating amount with a metering bar, pressurized air is supplied from a nozzle installed at the position of both edges of the support immediately before the metering bar. The coating method is characterized in that it is ejected toward the center of the. 2. The coating method according to claim 1, wherein the pressurized air is humidified air having a relative humidity of 40 to 90%. 3. The coating method according to claim 1, wherein the amount of pressurized air supplied is 1 to 20 liters per minute. 4. The clearance between the nozzle outlet and the metering bar is 0.5 to 2.0 mm, and the clearance between the nozzle outlet and the support is 0.5 to 2.0 mm.
The coating method according to any one of claims 1 to 3, wherein