JP2002273301A - Device and method for coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a thin film coating material without a stripe, by preventing the coating material from drying in the vicinity of a die extruding the coating material. SOLUTION: A catch pan 23 for storing a solvent 24 is installed on the upstream side in the carrying direction of the die 20 that extrudes the coating material 2 toward a carried long support 1. The solvent 24 is evaporated from the catch pan 23, and the concentration of a solvent vapor in the vicinity of the coating material 2 that is extruded from the die 20 is increased, thereby the coating material 2 can be prevented from drying. As a result, even when the coating material 2 is thinly applied to the support 1, a stripe-like defect does not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus for manufacturing a heat-sensitive recording material by coating a long support with a coating material.

[0002]

2. Description of the Related Art Conventionally, a method for applying a coating material to a long support is known as an extrusion method in which a coating material adjusted to an appropriate viscosity with a solvent is extruded from an extrusion die, and the coating material is applied to the surface of the transferred support material. There is a die method. In this method, it is possible to continuously apply the coating material to the support regardless of the length of the support. However, after a lapse of time from the start of the application of the paint, the dried paint adheres to the lip portion at the tip of the die and may remain and grow. When the dried paint adheres to the lip and grows,
A streak-like scar is generated on the applied paint (hereinafter, referred to as "streak scar defect"). In addition, drying caused on the liquid surface of the paint extrusion port causes the paint to gel, and a defect (hereinafter, referred to as “gel-like streak defect”) that causes streaks to remain due to the gelled paint occurs. Even if there are streak scar defects and gel-like streak defects, there is no particular problem as a product when the paint is an adhesive or the like. When application is required, the portion having a streak defect or a gel-like streak defect does not become a product. Therefore, not only the yield is poor, but also the number of sorting steps for removing the portion increases.

As a technique for solving the above problems, there is a technique disclosed in Japanese Patent Application Laid-Open No. Hei 10-118560. In the coating apparatus disclosed in Japanese Patent Application Laid-Open No. H10-118560, drying of the tip of the extrusion die is prevented by reducing the pressure on the upstream side of the support in the transport direction as viewed from the die and simultaneously applying pressure from the downstream side in the transport direction. are doing.

[0004]

However, even in the case of using a coating apparatus that reduces the pressure on the upstream side in the transport direction of the support as viewed from the die and pressurizes the downstream side in the transport direction, there are the following problems. When thinly applying a heat-sensitive material or the like to a long support, the paint is dissolved in an organic solvent and extruded from a die. By reducing the pressure on the upstream side in the transport direction, the evaporation of the organic solvent is promoted, and the paint dries and easily adheres to the lip at the tip of the die, which may cause the above-mentioned streak scar or gel streak defect. Was high. In addition, it is difficult to design a decompression chamber for providing a reduced-pressure atmosphere on the upstream side in the transport direction of the support and a pressurizing chamber for providing a pressurized atmosphere on the downstream side in the transport direction. Under such circumstances, the support may vibrate during the pressurization and depressurization, and the thickness of the paint fluctuates with the vibration, so that there is a problem that the paint cannot be applied to a uniform thickness.

The present invention has been made in view of the above situation, and has as its object to prevent the occurrence of defects due to drying of a paint and to stabilize the application of the paint to a support.

[0006]

In order to achieve the above object, a coating apparatus according to a first aspect of the present invention comprises a support for transporting a support having a coating surface from an upstream side in a transport direction to a downstream side in a transport direction. A body conveying mechanism, a coating die having a tip directed to the coating surface and a coating outlet opening at the tip, and extruding a coating material dissolved in a solvent from the coating outlet to apply the coating to the coating surface; and the coating die. And a solvent tank that is disposed on the upstream side in the transport direction and stores the solvent and volatilizes the solvent toward the support. By adopting such a configuration, the solvent stored in the solvent tank is volatilized, and the vicinity of the upstream side in the transport direction of the coating die is wrapped with the vaporized solvent, and the solvent vapor concentration increases, and the coating material flows from the tip of the coating die. The extruded solvent is less likely to volatilize, thereby preventing sticking of the paint and gelling of the paint.

The solvent tank may be provided with a volatilization-promoting member that is partially exposed from the liquid level of the stored solvent and that promotes the volatilization of the solvent. Further, the volatilization promoting member may be formed of a fiber upper member. Further, the volatilization promoting member may be formed of a porous member. Further, a heating mechanism for heating the solvent stored in the solvent tank to promote the volatilization of the solvent may be further provided. Further, the apparatus may further include a shielding plate extending from the end of the solvent tank toward the support and reducing air flowing from the upstream side in the transport direction to the application port side with the transport of the support. . Further, it is preferable that the angle between the shielding plate and the support on the upstream side in the transport direction is 90 ° or less. Further, the distance between the support-side end of the shielding plate and the support may be 5 mm or more. Further, a support transport mechanism for transporting the support having the coating surface from the upstream side in the transport direction to the downstream side in the transport direction, and a tip is directed to the coating surface and a paint extrusion opening is opened at the tip, and the solvent is dissolved by the solvent. A coating die for extruding paint from the paint extrusion port to apply the coating surface, and increasing the vapor concentration of the solvent in an atmosphere on the upstream side in the transport direction of the paint extrusion port, and extruding the paint with the coating die from the coating die. Drying suppression means for preventing the solvent from volatilizing.

In order to achieve the above object, a second aspect of the present invention is provided.
The coating method according to the aspect of the present invention, a support having a coating surface is transported from a transport direction upstream side to a transport direction downstream side, from a coating die having a tip directed toward the coating surface and a paint extrusion opening at the tip. In a coating method in which a paint dissolved in a solvent is extruded and applied to the application surface, the vapor concentration of the solvent in an atmosphere on the upstream side in the transport direction of the paint extrusion port is increased, and the paint is extruded from the coating die together with the paint. It is characterized by preventing volatilization of the solvent. By adopting such a method, on the upstream side in the transport direction, the vapor concentration of the solvent in the vicinity of the paint extrusion port of the coating die increases, thereby reducing the volatilization amount of the solvent extruded with the paint from the coating die, Prevents paint from drying.

[0009]

FIG. 1 is a structural view of a coating apparatus according to a first embodiment of the present invention, and FIG. 2 is an enlarged view showing the vicinity of a die 20 in FIG. This coating apparatus is for applying a coating material 2 to an application surface 1a of a long plastic support 1 such as a polyester tape, and a supply stand 10 on which the support 1 wound in a roll is set.
A die 20 for extruding the coating material 2 having a viscosity adjusted by being dissolved in a solvent; a drying unit 30; a take-up device 40 serving as a support transport mechanism for transporting the support 1 by pulling the support 1; And

An arbitrary number of guide rolls 11 are provided between the supply stand 10 and the die 20 for guiding the support 1 drawn out of the supply stand 10 to the die 20. Immediately above the die 20, there is provided a back roll 12 that directs the coating surface 1 a of the support 1 toward the die 20 and approaches the tip of the die 20. The support 1 is
The support 1 passes between the back roll 12 and the die 20, passes through the drying unit 30, is guided by the guide roll 13, and enters the take-up machine 40.
The supply stand 10 is provided with a brake (not shown) for applying a constant tension to the support 1 to be fed, and the guide rolls 11 and 13 and the back roll 12 are rotated so that unnecessary tension is not applied to the support 1. It is free to move. The drying unit 30 is for drying the paint 2, and has a structure in which warm air is applied to the application surface 1 a of the support 1.

The take-up machine 40 is provided with a capstan roll 41 which is driven by a drive system (not shown) to rotate and take up the support 1 passing through the drying unit 30.
Guide rolls 42 and 43 for increasing the contact area of the support 1 with the capstan roll 41 are provided before and after the capstan roll 41. The winding machine 50 includes the take-up machine 4
This is a device for winding the support 1 taken up in a roll shape at a constant tension.

As shown in FIG. 2, at the tip of the die 20,
A paint extrusion port 21 for extruding the paint 2 is opened. A portion surrounding the paint extrusion port 21 is a lip portion 22 where the paint 2 is easily adhered in the related art. The gap between the lip 22 and the support 1 is set by the back roll 12. The side of the die 20 on the supply stand 10 side, that is,
A catch pan 23 is attached to the side surface on the upstream side in the support transport direction. The catch pan 23, together with the side surface of the die 20, constitutes a solvent tank for storing the solvent 24. The upper part of the solvent tank formed by the catch pan 23 and the side surface of the die 20 is opened so that the stored solvent 24 volatilizes toward the support 1. The solvent 24 is stored. The solvent 24 is the same kind of solvent as the one in which the paint 2 is dissolved in order to adjust the viscosity of the paint 2.

In the coating apparatus having the above-described configuration, when the take-up machine 40 starts taking the support 1, the support 1 is continuously fed out of the supply stand 10 and is conveyed downstream in the conveying direction. The transported support 1 is guided by the guide roll 11 and passes between the backup roll 12 and the die 20. At this time, the die 20 is extruding the coating material 2 whose viscosity is adjusted by being dissolved by the solvent. The material of paint 2 is
The thermosensitive recording material is preferably a leuco dye, a developer that causes the leuco dye to develop a color by heating, and a binder resin as a binder. Among them, a heat-sensitive recording material of a medical thermal film is particularly preferable, and a satisfactory coating layer can be obtained even in a case where quality accuracy is particularly required as in the case of a medical thermal film.

The viscosity of the coating material 2 is preferably 400 mPa · s or less, and particularly preferably 50 to 400 mPa · s. When the viscosity exceeds 400 mPa · s, the leveling performance of the coating film is impaired, and coating unevenness such as orange peel and uneven shading tends to occur in the drying process. When the viscosity is lower than 50 mPa · s, the coating material 2 tends to flow, and therefore, when the coating material 2 comes into contact with the support 1, uneven flow tends to occur. The paint 2 extruded from the paint extrusion port 21 of the die 20 is in contact with the application surface 1 a of the support 1, and the support 1 is taken off by the take-off machine 40 as it is. Therefore, the paint 2 having a thickness determined by the amount of extrusion of the paint 2 and the take-up speed is applied to the application surface 1a of the support 1. The same solvent 24 as the solvent contained in the paint 2 is selected and the catch pan 2
3, the solvent 24 evaporates from the catch pan 23 at a speed corresponding to the ambient temperature, and proceeds toward the support 1. As a result, the concentration of the solvent vapor in the atmosphere on the upstream side of the die 20 in the support conveyance direction increases. As the solvent vapor concentration in the atmosphere increases, the solvent extruded from the paint extrusion port 21 of the die 20 together with the paint 2 decreases, and the drying of the paint 2 is suppressed. As a result, the dried paint 2 does not adhere to the lip portion 22, and
The paint 2 does not become a gel.

The thickness of the coating material 2 applied to the support 1 is 70
１００100 μm is preferred. When the film thickness is less than 70 μm, it is difficult to adjust the gap between the support 1 and the die 20, and the left and right difference of the coating film tends to occur. And paint 2
An application failure such as breakage of the coating occurs. If the film pressure of the paint 2 exceeds 100 μm, the lip 22 of the die 20
In this case, paint dripping occurs and a uniform film thickness cannot be obtained. The paint 2 applied to the support 1 evaporates and dries when the solvent evaporates at the stage of passing through the drying unit 30. The support 1 from which the coating material 2 has dried passes through a take-up machine 40 and is wound into a roll by a take-up machine 50.

Hereinafter, the present invention will be described in more detail with reference to Examples 1 to 4, but the present invention is not limited to the Examples.

(Example 1) From a die 20, 10 parts of octadecylphosphonic acid, 2 parts of 3-diethylamino-6-methyl-7-anilinofluoran and 9 parts of polyvinyl acetoacetal as paint 2 were obtained. 60 parts of methyl ethyl ketone as an organic solvent and 15 parts of toluene are kneaded together, the viscosity of the coating material 2 is adjusted to 150 mPa · s / 22 ° C. and extruded, and the coating material 2 is applied to the support 1 by the apparatus shown in FIG. went. Here, methyl ethyl ketone as a solvent 24 was stored in the catch pan 23 and volatilized at room temperature. The take-up speed (transport speed) of the support 1 is 12 m / min,
The gap between the front end of No. 0 and the support 1 was 155 μm, and the amount of paint extruded was 900 g / min. By continuously applying the coating material 2 to the support 1, the coating film 2 was applied to the coating surface 1 a of the support 1 with a wet film thickness of 85 μm. Even if the coating material 2 is continuously applied for 6 hours, the methyl ethyl ketone stored in the catch pan 23 volatilizes, and the coating material is prevented from drying, and no streaks or gel streaks are generated. A good coating state was obtained. Further, the take-off speed is 18 m / min,
The coating amount was changed to 1300 g / min, and the coating material 2 was continuously applied for 6 hours. In this case, no streaks or gel streaks were generated. The condition was obtained.

(Embodiment 2) FIG. 3 is a structural view showing a catch pan used in Embodiment 2, and the same reference numerals are given to the elements common to the elements in FIG. At the front end of the support side 1 of the catch pan 23, a shielding plate 25 for preventing entry of air entering with the transport of the support 1 from the upstream side in the transport direction of the support as viewed from the die 20 is extended. The angle θ between the shielding plate 25 and the support 1 can be set in the range of 0 to 90 degrees, but is preferably set in the range of 10 to 70 degrees. In particular, it is more preferable to provide at 10 to 30 degrees. The angle θ between the shielding plate 25 and the support 1 is 90
If it is larger than the degree, the air carried by the support 1 enters into the catch pan 25 without being shielded, and the concentration of the solvent vapor is reduced, so that the possibility of application unevenness increases.

The distance L between the tip of the shielding plate 25 and the support 1 is preferably 5 mm to 30 mm, and more preferably 10 mm to 20 mm. When the tip of the shielding plate 25 is closer than 5 mm, the possibility that the support 1 comes into contact with the support 1 or the support 1 is torn due to loosening or bouncing of the support 1 increases. If the distance L between the tip of the shielding plate 25 and the support 1 exceeds 30 mm, the amount of air transported by the support 1 increases, and the possibility of application unevenness increases. Further, the concentration of the solvent vapor in the catch pan 23 also becomes thin, and a gel-like streak defect tends to occur. In this way, the coating material 2 was applied under the same conditions as in Example 1 using the coating device in which the catch pan 23 with the shielding plate 25 extended was mounted on the upstream side of the die 20 in the support transport direction.
As a result of the application, even if the coating material 2 was applied to the application surface 1a of the support 1 continuously for at least 8 hours or more, a good coating film having no gel streak defect was obtained.

(Embodiment 3) FIG. 4 is a view showing a volatilization promoting member used in Embodiment 3, and elements common to those in FIG. 3 are denoted by common reference numerals. In order to promote the volatilization of the solvent 24, a volatilization promoting member 27 made of fibrous felt is placed on the catch pan 23 as shown in FIG. 3, and the upper part thereof is exposed from the liquid surface of the solvent 24. With the volatilization promoting member 27 placed in this way, the coating material 2 was applied under the same conditions as in Examples 1 and 2. As a result of application of the coating material 2, a good coating film free of streak-like scars and gel-like streak defects was obtained even after continuous application for 11 hours.

Example 4 The solvent 24 stored in the catch pan 23 of FIG. 2 was toluene having a boiling point lower than that of methyl ethyl ketone, and the coating material 2 was applied to the support 1 under the conditions shown in Example 1. Even when the coating was performed, a favorable coating film state free of streak-like scars and gel-like streak defects was obtained.

(Comparative Example) The support 1 was used under the conditions shown in Example 1 without storing the solvent 24 in the catch pan 23 shown in FIG.
When the coating material 2 was applied to the lip portion 22, when the coating material was continuously applied for two hours, the lip portion 22 had gelled due to the streak-like scratches due to the adhesion of the dried coating material and the drying of the coating liquid surface near the coating extrusion port 21. And a gel-like streak defect caused by the above. Of course, when the take-up speed is 18 m / min, these defects occur in a much faster time.

As described above, the coating apparatus of the present embodiment
As is clear from Examples 1 to 4 and Comparative Example, the following operation and effect can be obtained. (1) Since the catch pan 23 for storing the solvent 24 is attached to the die 20 for extruding the paint 2, the catch pan 23
As a result, the solvent 24 evaporates, and the solvent vapor concentration in the vicinity of the lip portion 22 and the liquid surface of the paint 2 at the tip of the die 20 can be increased. As a result, the solvent is prevented from evaporating from the paint 2 and drying, and even if the paint 2 is applied to the support 1 for a long time, the streak scar and the gel streak defect do not occur. That is, the coating can be performed for a long time. (2) Attaching the shielding plate 25 to the catch pan 23 prevents air from flowing into the liquid surface of the paint 2 at the tip of the die 20 and the vicinity of the lip portion 22 with the transport of the support 1. 2 can maintain a high solvent vapor concentration in the liquid surface and in the atmosphere near the lip 22.

(3) Since the volatilization of the solvent 24 is promoted by placing the volatilization promoting member 27 on the catch pan 23, the solvent vapor concentration at the tip of the die 20 and in the vicinity of the liquid surface of the coating material 2 can be increased. It can be higher and the probability of streak and gel streak defects is lower.

Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications.

(I) In FIG. 1, the supply stand 10
Is shown, but two rolls are prepared, and rolls on which the support 1 is wound are set on these rolls. When the application of one roll to the support 1 is completed, the other roll is mounted on the support 1. If the support 1 is connected, the paint 2 can be continuously applied to the support 1 wound around a plurality of rolls.
Also, without disposing the supply stand 10, the die 20,
The take-up machine 40 and the winder 50 may be arranged in an extruder for manufacturing the support 1 or a stretching device for stretching the support 1 so as to be in tandem.

(Ii) In FIG. 1, the paint 2 is forcibly dried by the drying unit 30. However, the drying unit 30 may be omitted and the drying may be performed naturally. (Iii) In order to increase the volatility of the solvent 24, the volatilization promoting member 27 is placed on the catch pan 23. However, if the paint 2 at the tip of the die 20 is not affected, the solvent 24
Can also promote volatilization. Therefore, for example, a heating unit that performs hot water heating or ultrasonic heating without using a fire may be provided. For example, by attaching a hot water heating device or an ultrasonic heating device to the catch pan 23 and heating the solvent 24 to about the boiling point, the volatilization rate of the solvent 24 increases, and the solvent vapor concentration near the extrusion port 21 of the die 20 decreases. Ascends and approaches saturation. Thereby, the effect of preventing the paint 2 from drying can be further enhanced, and it is expected that the same operation and effect as the above embodiment can be obtained.

(Iv) The volatilization promoting member 27 may be any material that can promote the volatilization of the solvent 24 without being dissolved in the solvent 24, and a fibrous or porous material is preferable because it can increase the surface area. Specifically, felt, cotton, nonwoven fabric, cloth and the like can be considered. Further, even if a capillary flaw is formed on the inner wall surface of the catch pan 23 on the upstream side in the support transport direction, the same effect as in the above embodiment can be expected. (V) In Examples 1 to 3, methyl ethyl ketone is stored in the catch pan 23, and in Comparative Example 2, toluene is stored in the catch pan 23. However, a mixed solvent of methyl ethyl ketone and toluene may be stored in the catch pan 23. . (Vi) In the third embodiment, the volatilization promoting member 27 is placed on the catch pan 23 with the shielding plate 25 extended. However, as in the first embodiment, the volatilization promoting member 27 is placed on the catch pan 23 without the shielding plate 25. It is also possible to mount the member 27.

[0029]

As described above, in the coating apparatus according to the present invention, the solvent tank for storing the solvent is disposed upstream of the coating die for extruding the coating material in the transport direction of the support. The solvent vapor concentration in the atmosphere at the tip increases, which prevents the paint from drying at the tip of the die. Therefore, even if the support is long, stable and defect-free coating becomes possible, and the product yield can be improved, and the production efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a coating apparatus showing an embodiment of the present invention.

FIG. 2 is a partially enlarged view showing the vicinity of a die 20 in FIG.

FIG. 3 is a diagram illustrating a catch pan used in a second embodiment.

FIG. 4 is a view showing a volatilization promoting member used in Example 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support body 1a Coating surface 2 Paint 10 Supply stand 20 Die 21 Paint extrusion port 22 Lip part 23 Catch pan 24 Solvent 25 Shielding plate 27 Volatilization promoting member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D075 AC05 AC72 AC80 AC93 BB57Y BB69Y CA48 DA04 DB48 DC27 EA07 EC30 4F041 AA12 BA32 BA47 BA53 CA03 CA12 CA25 4F042 AA22 CA08 CB04 DA09 DF23 DH10

Claims (11)

[Claims] 1. A support transport mechanism for transporting a support having a coating surface from an upstream side in a transport direction to a downstream side in a transport direction; a tip directed to the coating surface; A coating die for extruding the melted coating from the coating extrusion port and applying it to the coating surface; and a solvent tank disposed upstream of the coating die in the transport direction, for storing the solvent and volatilizing the solvent toward the support. And a coating device. 2. In the case where the paint is dissolved in a plurality of types of mixed solvents, a solvent selected from solvents excluding the solvent having the highest boiling point in the mixed solvent is stored in the solvent tank. The coating device according to claim 1, wherein 3. A volatilization-promoting member, which is partially exposed from the liquid surface of the stored solvent and promotes volatilization of the solvent, is placed in the solvent tank. 3. The coating device according to claim 1. 4. The coating apparatus according to claim 3, wherein said volatilization promoting member is formed of a fibrous member. 5. The coating apparatus according to claim 3, wherein said volatilization promoting member is formed of a porous member. 6. The coating apparatus according to claim 1, further comprising a heating mechanism for heating the solvent stored in the solvent tank to promote the evaporation of the solvent. 7. A shielding plate extending from an end portion of the solvent tank toward the support and reducing air flowing from the upstream side in the transport direction to the coating port side as the support is transported. 7. The method according to claim 1, wherein:
The coating device according to Item. 8. The coating apparatus according to claim 7, wherein the angle between the shielding plate and the support on the upstream side in the transport direction is 90 ° or less. 9. The coating apparatus according to claim 7, wherein a distance between the support-side tip of the shielding plate and the support is at least 5 mm. 10. A support transport mechanism for transporting a support having a coating surface from an upstream side in a transport direction to a downstream side in a transport direction, a tip directed to the coating surface, a paint extruding port opened at the tip, and a solvent. A coating die for extruding the melted coating from the coating extrusion port to apply the coating surface, and increasing the vapor concentration of the solvent in the atmosphere on the upstream side in the transport direction of the coating extrusion port, and from the coating die together with the coating. A drying suppressing means for preventing volatilization of the extruded solvent. 11. A support having a coating surface is transported from the upstream side in the transport direction to the downstream side in the transport direction, and the support is melted by a solvent from a coating die having a tip directed toward the coating surface and having a paint extrusion port opened at the tip. In the coating method of extruding the applied paint on the application surface, increasing the vapor concentration of the solvent in the atmosphere on the upstream side in the transport direction of the paint extrusion port, the solvent extruded from the application die together with the paint A coating method characterized by preventing volatilization.