JP4964630B2 - Coating apparatus and coating method - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus and a coating method, and in particular, a backup roller disposed in the vicinity of a coating machine in coating that requires coating liquid to be applied to a traveling belt-like support (hereinafter referred to as a web) with high accuracy. The present invention relates to improved technology.

  The coating apparatus that applies the coating liquid to the surface of the web to be transported is a coating apparatus that opposes the coating head or places and arranges backup rollers that support the conveyance of the web on the upstream side and the downstream side of the coating head. There is. Examples of the coating machine include a bar coating device (also referred to as a rod coating device), a reverse roll coating device, a gravure roll coating device, a slot die coating device (for example, an extrusion coating device). These coating devices are used in the manufacture of optical films (optical compensation films, antireflection films, etc.) and magnetic recording media, and require high-precision precision coating with good surface quality that is thin and free of coating unevenness. Has been.

  In these coating apparatuses having a backup roller, when the web is passed between the coating head and the backup roller, or at the start or end of coating, a detaching operation for moving the backup roller back and forth between the coating position and the retracted position is performed. Do.

  By the way, when the vibration of the coating head is transmitted to the coating surface of the web in the coating operation, it appears as coating unevenness, which degrades the coating quality. It has also been proposed to prevent vibrations.

Although it is not a coating head, for example, in the exposure apparatus and device apparatus disclosed in Patent Document 1, a natural vibration of the air damper is provided by providing a pair of air dampers arranged so that their driving directions face each other in the vertical direction and a means for controlling the internal pressure of the air damper. A vibration isolator that adjusts the number is disclosed. Patent Document 2 discloses that the natural frequency is adjusted by changing the rigidity of the photosensitive drum.
Japanese Patent Laid-Open No. 11-315883 JP-A-10-2222011

  However, when thin film coating is required and high-precision precision coating with minimal coating unevenness is required, such as coating in the manufacture of optical films and magnetic recording media, horizontal step-like unevenness is caused by vibration of the backup roller during coating. There is a problem that may occur. As means for reducing the vibration of the backup roller during application, it is necessary to increase the rigidity of the raising / lowering portion of the backup roller and at the same time reduce the backlash of the raising / lowering mechanism. In general, desorption by bar coating uses a guide (for example, LM guide) in order to move the backup roller vertically. For this reason, the backlash of the guide causes the backlash of the entire backup roller lifting unit.

  The present invention has been made in view of such circumstances, and even if it is a precision coating that requires very high precision coating such as an optical film or a magnetic recording medium, coating unevenness (particularly horizontal stepwise unevenness) is caused. It is an object of the present invention to provide a coating apparatus and a coating method capable of obtaining an excellent surface-shaped coating film.

In order to achieve the above object, the first aspect of the present invention applies the coating liquid from the coating head to the surface of the belt-like support that continuously runs while being supported by the backup roller, and retracts the backup roller from the coating position. In a coating apparatus having an advancing / retreating mechanism that moves forward / backward between positions, the advancing / retreating mechanism includes a roller unit that rotatably supports rotation shafts at both ends of the backup roller by a bridging frame, and the backup roller. Swinging means for swinging the roller unit so as to advance and retreat between the application position and the retracted position, and the roller unit is positioned at an upstream side and a downstream side across the application head. A pair of the backup rollers is provided, and the center of one rotation axis of the pair of backup rollers and the center of the swinging shaft of the swinging means are Is one, the rotation center and the pivot shaft center and the same backup roller of the pair of backup rollers, wherein the a backup roller in the running direction downstream side of the planar support member.

  According to the first aspect of the present invention, the roller unit formed by rotatably supporting the rotation shafts at both ends of the backup roller with the bridging frame is provided in the advance / retreat mechanism, so that the rigidity can be increased, so that the vibration is increased to a high frequency. The absolute value of the amplitude can be suppressed. Further, since the advancing / retreating movement mechanism is provided with the swinging means for swinging the roller unit so that the backup roller advances and retracts between the application position and the retracted position, the vibration of the roller during application can be suppressed. Thus, since it apply | coated in the state which suppressed the vibration by a backup roller, generation | occurrence | production of a coating nonuniformity can be suppressed effectively. Therefore, even when coating a coating film that requires very high precision coating such as an optical film or a magnetic recording medium, a good planar coating film can be obtained.

Then, according to claim 1, the roller unit, by comprising providing a pair of backup rollers in the position of the upstream side across the coating head and the downstream side, suitably it is possible to suppress the web, the coating unevenness Generation | occurrence | production can be suppressed more effectively. Further, since the roller unit is provided with a pair of backup rollers, uneven application can be further prevented.

Further, according to claim 1, one and the axis of rotation of the backup roller, by matching the rocking axis center of the swinging means, it is possible to further suppress the vibration of the roller unit, the backup roller Vibration can be further suppressed.

Further, according to claim 1, the rotation shaft center and the rocking axis center and the same backup roller of the pair of backup rollers, by a backup roller in the running direction downstream side of the belt-like support, coating irregularity It is possible to obtain a good planar coating film having no surface.

Claim 2 according to claim 1, wherein the coating head is characterized in that a head of the bar coating.

According to the second aspect , when the coating head is a bar coating head, it is possible to preferably obtain a good planar coating film without coating unevenness.

A third aspect of the present invention is characterized in that, in the first or second aspect , the coating liquid is a coating liquid for manufacturing an optical film or a magnetic recording medium.

According to the third aspect , when the coating solution is a coating solution for manufacturing an optical film or a magnetic recording medium, extremely high-precision coating is required, so that the present invention is effective.

According to a fourth aspect of the present invention, there is provided a coating method in which the coating apparatus performs the coating / removing operation with the coating apparatus according to any one of the first to third aspects, and the rotation shafts at both ends of the backup roller are rotatably supported by a bridging frame. The detaching operation is performed by swinging the entire roller unit.

  Here, “application / removal operation” means that the belt-like support is passed between the application head and the backup roller, at the start or end of application, or as necessary, with the backup roller attached to the application head. It refers to an operation of moving forward and backward to bring the coating liquid into a state where it is applied to the belt-like support (attached state) or not applied (detached state).

According to the fourth aspect of the present invention, it is easy to increase the rigidity of the mechanism for moving the backup roller forward and backward by swinging together the bridge-shaped frames that rotatably support the rotation shafts at both ends of the backup roller. In addition, it is possible to reduce backlash when moving forward and backward. Thereby, since the vibration of the backup roller during application can be reduced, uneven application of the coating film surface can be effectively prevented.

  According to the present invention, it is possible to obtain a good planar coating film with no coating unevenness even for coatings that require extremely high precision coating such as optical films and magnetic recording media.

  Hereinafter, preferred embodiments of the coating method and apparatus of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an example in which a coating apparatus according to the present invention is shown as a bar coating apparatus, and a bar coating apparatus 10 is an example of a coating / metering integrated type.

  As shown in FIG. 1, a coating and metering integrated bar coating apparatus 10 mainly includes a bar coating head 50 for coating a desired amount of coating liquid, and an upstream side of the bar coating head along a web W conveyance line. And backup rollers 20, 20 provided in a pair on the downstream side.

  The bar coating head 50 is mainly composed of a bar 28, a bar support 30 that rotatably supports the bar 28, coater blocks 52 and 54, and side blocks (not shown) on both sides (front and rear in the drawing). The Pockets 56 and 58 and slits 60 and 62 are formed between the bar support 30 and the coater blocks 52 and 54, and the coating liquid is supplied to the pockets 56 and 58.

  The coating liquid supplied to the pockets 56 and 58 is uniformly pushed out in the width direction of the web W through slits 60 and 62 that are parallel to the width direction of the web W and narrow in the web conveyance direction. As a result, the primary coating bead 64 is formed on the upstream side (hereinafter referred to as “primary side”) of the web 28 in the conveyance direction of the web W, and is formed on the downstream side (hereinafter referred to as “secondary side”). Then, the secondary side application bead 66 is formed. Accordingly, the bar 28 transfers and coats a predetermined amount of the coating liquid onto the web W traveling through these coating beads 64 and 66.

  The coating liquid supplied excessively from the pockets 56 and 58 overflows from between the coater blocks 52 and 54 and the web W, and is collected through the side grooves 65 and 67 (partially shown). The supply of the coating liquid to the pockets 56 and 58 may be performed from the center part of the pockets 56 and 58 or from the end part.

  The bar 28 is rotationally driven in the same direction as the web W or in the opposite direction by a rotational drive system (not shown). Thereby, the excess of the coating liquid 14 that has been excessively applied to the web W by the pre-coating device 16 is scraped off by the bar 28 and is measured to a desired amount of the coating liquid. Further, by rotating the bar 28, foreign matter is prevented from being trapped between the web W and the bar 28, and occurrence of coating failure due to the foreign matter is prevented.

  As the bar 28, a flat bar having a flat bar surface, a wire bar in which a wire is tightly wound around the bar, a grooved bar having a groove on the surface of the bar, or the like can be used.

  The bar coating apparatus 10 performs the detachment operation when the web is passed between the bar coating head and the backup roller, when the coating is started, or when necessary, by moving the backup roller back and forth with respect to the bar coating head.

  2 and 3 are examples of the advancing / retreating mechanism of the backup rollers 20 and 20 according to the present invention. Here, in FIG. 2, FIG. 2 (A) shows the case where the backup roller is moved to the retracted position, and FIG. 2 (B) shows the case where the backup roller is moved to the application position, and FIG. FIG. 3 is a side view showing a case where the web W is passed through in FIG. FIG. 3 is a front view of a roller unit 25 that is a mechanism for moving the backup rollers 20 forward and backward.

  Here, in the roller unit 25, as shown in FIGS. 2 and 3, the rotating shafts 20A and 20A at both ends of the backup rollers 20 and 20 are supported by the bridge-like frame 21 via bearings 21A and 21A. . Incidentally, bearings (not shown) are incorporated in the bearings 21A and 21A, respectively, so that the backup roller rotates as the web W is conveyed. The frame 21 has a cylinder 23 attached to an end on the upstream side or the downstream side, and swings so as to draw an arc. Further, the roller unit 25 that moves up and down by the bar coating device 10 and the cylinder 23 is fixed to the support base 21B.

  Thus, the backup roller 20 is made rigid by configuring the roller unit 25 in which the rotation shafts at both ends of the backup roller are rotatably supported by the bridging frame 21. This makes it difficult for the backup roller 20 to vibrate during application. Further, even if the backup roller 20 vibrates, the rigidity becomes high, so that the vibration frequency shifts to the high frequency side, so that the absolute value of the amplitude becomes small and it becomes difficult to cause horizontal unevenness.

  Further, the conventional mechanism in which both ends of the backup roller 20 are supported by a pair of LM guides and moved forward and backward with respect to the coating head 50 has two fulcrums for the backup roller 20 to move forward and backward. It is necessary to give some support to the fulcrum in order to harmonize the two fulcrums. The play caused by the play causes the back-up roller to play, and the vibration is likely to occur during application. On the other hand, the mechanism that moves forward and backward by swinging the roller unit 25 as in the present invention does not require play because the fulcrum has only one swing shaft and no play is required. The vibration inside can be suppressed. Further, by making the backup roller 20 rigid with the frame 21, a swinging mechanism is possible.

  Thus, since it apply | coated in the state which suppressed the vibration by a backup roller, generation | occurrence | production of a coating nonuniformity can be suppressed effectively. Therefore, even when a coating film that requires highly precise precision coating, such as an optical film or a magnetic recording medium, is applied, a good planar coating film can be obtained.

  As shown in FIG. 2, it is preferable that a pair of backup rollers 20, 20 provided on the upstream side and the downstream side of the bar coating head 50 are unitized in the same frame (frame 21). Since the pair of backup rollers are unitized in the same frame, coating unevenness can be further prevented.

  In addition, as shown in FIG. 2, it is preferable that the center of one rotation axis of the pair of backup rollers 20 and 20 is the same as the center of the swing axis. By causing one rotation center axis of the backup roller to coincide with the center of the swing axis, the vibration of the roller unit can be further suppressed, so that the vibration of the backup roller can be further suppressed.

  Further, the backup roller having the same rotation axis center and swing axis center in the pair of backup rollers 20 and 20 is preferably a backup roller on the downstream side in the running direction of the web W. Of the pair of backup rollers, the backup roller having the same rotation axis center and swing axis center is a backup roller on the downstream side in the running direction of the web, thereby obtaining a good surface coating film without coating unevenness. be able to.

  The bar coating apparatus 10 ′ in FIG. 4 is an example of a separate coating / metering type. In addition, the same code | symbol is attached | subjected and demonstrated to the same member as the application | coating and measurement integrated type demonstrated in FIG.

  Mainly, an extrusion-type pre-coating device 16 that applies the coating liquid 14 to the web W in excess of a desired amount of coating liquid, and a scraping bar that scrapes off the excess of the coating liquid 14 that has been excessively applied to the web W. The apparatus 18 includes a plurality of pass rollers 20 and 20 provided along the web W conveyance line.

  The extrusion type pre-coating device 16 includes a slit 24 (also referred to as “slot”) that communicates the coating liquid 14 pumped into the pocket 22 (or also referred to as “manifold”) with the pocket 22. From the outlet 24A, the head end face 26 is pressed against the web W that is mounted on the pass roller 20 and travels at a constant speed in the direction of the arrow.

  Thereby, an excessive coating liquid is applied to the lower surface of the web W immediately before the scraping bar device 18. The precoating device 16 is not limited to the extrusion type, and any coating device that applies a coating solution to the web W can be used.

  The scraping bar device 18 is configured by supporting a columnar bar 28 disposed in parallel with the width direction of the web W in a support groove 30A of the bar support base 30, and the web W traveling by the pass roller 20 is The coating bar 28 is configured to come into contact with a predetermined wrap angle (winding angle).

  As the shape of the support groove 30A for supporting the bar 28, a V-shaped groove shown in FIG. 5 or a U-shaped groove (not shown) is generally used. The straightness in the longitudinal direction (same as the web width direction) of the wall surface 30B forming the support groove 30A is processed to be equal to or greater than the straightness in the longitudinal direction of the bar 28 (same as the web width direction). Is done.

  Also in the scraping bar device 18, by using the roller unit 25 shown in FIGS. 2 and 3, similarly to the bar coating device 10 shown in FIG. 1, vibration of the roller during coating can be suppressed.

  As described above, the scraping bar device 18 can also be applied in a state in which the vibration due to the backup roller is suppressed, and the occurrence of uneven coating can be effectively suppressed. Therefore, even when coating a coating film that requires very high precision coating such as an optical film or a magnetic recording medium, a good planar coating film can be obtained.

  Here, the swing operation angle of the roller unit 25 that swings while drawing an arc is preferably 90 ° or less. The bearing (not shown) is preferably a single row deep groove ball shaft, and the radial clearance of the bearing is preferably 40 μm or less. The effects of the present invention can also be obtained when the number of backup rollers attached to the roller unit 25 is one.

  In any of the coating / measuring integrated type and the separate coating / measuring type bar coating apparatuses 10, 10 ', the diameter Φ of the bar 28 is preferably in the range of 3 to 15 mm, and the wire diameter when the bar 28 is a wire bar. Φ is preferably in the range of 0.05 to 0.20 mm. Further, the coating tension (tension in the conveying direction) of the web W is preferably in the range of 50 to 1500 N / m, and the coating speed is preferably in the range of 5 to 150 m / min. Further, the different peripheral speed ratio (bar peripheral speed / web speed) of the bar 28 is preferably in the range of 0.1 to 1.5. Further, the speed unevenness of one rotation period of the pass roller 20 is preferably within 1.5%, and more preferably within 1.0%.

  As described above, in the present embodiment, the bar coating apparatus has been described. However, the present invention can be applied to any coating apparatus having a backup roller. For example, the extrusion type coating apparatus 10 '' shown in FIG. Good. 6 includes an extrusion-type coating head 70 that coats a desired amount of coating solution, and a backup roller 20 that is provided to face the coating head 70 with a web W interposed therebetween. The A manifold 72 and a slot 74 are formed inside the coating head 70, and the coating solution 14 supplied to the manifold 72 of the coating head 70 is applied to the web W through the slot 74.

  The web W used in the present invention is generally polyethylene terephthalate (PET) having a width of 300 to 3000 mm, a length of 45 to 10000 m, and a thickness of 2 to 200 μm, polyethylene-2,6-naphthalate, cellulose diacetate. , Cellulose triacetate, cellulose acetate propionate, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyimide, polyamide and other plastic films, paper, polyethylene, polypropylene, ethylene butene copolymer, etc. Examples include a flexible strip made of paper or the like coated or laminated with polyolefins, or a strip having a processed layer formed on the surface of the strip as a base material.

As a coating amount of the coating liquid onto the web W, a range of ^{2 to} 15 mL / m ² can be preferably employed. Moreover, as a coating width of the coating liquid to the web W, the range of 500-3000 mm can be employ | adopted preferably.

The coating solution is not limited to a non-Newtonian fluid such as a coating solution for an optical film or a magnetic tape, but may be a Newtonian fluid using a gelatin solution having a relatively low viscosity of the photographic photosensitive layer as a binder. As the viscosity of the coating solution, a range of 0.8 to 10 cp (0.8 to 10 × 10 ⁻³ Pa · s) can be preferably employed.

[Example 1]
Next, an embodiment in which a coating solution for an optical compensation film is coated using the separate coating / metering type bar coating apparatus 10 ′ shown in FIG. 4 will be described.

  The vibration speed (overall value of 0 to 200 Hz) of the backup roller 20 was tested. The evaluation of the test was performed on the upstream backup roller 20 closest to the bar 28 of the scraping bar device 18.

  In the test, as shown in Table 1, a backup roller 20 having a roller length (surface length) of 1600 mm and a roller shaft distance (axis length) of 1800 mm was used.

(Preparation of coating solution for optical compensation film)
Ethylene oxide-modified trimethylolpropane triacrylate (V # 360, Osaka Organic Science Co., Ltd.) with respect to a mixture of the discotic compound TE-8 shown below in a weight ratio of R (1) and R (2) of 4: 1. 10% by weight, cellulose acetate petitate (CAB531-1, Eastman Chemical Co., Ltd.) 0.6% by weight, photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy Japan, Inc.) 3% by weight 1% by weight of a sensitizer (Kayacure DET-X, manufactured by Nippon Kayaku Co., Ltd.) was added, and finally a 32% by weight methyl ethyl ketone solution of the mixture was obtained. To the liquid containing the liquid crystal compound, 0.3% by weight of a fluorine-based interfacial binder (fluoroaliphatic group-containing copolymer, Megafac F780, manufactured by Dainippon Ink Co., Ltd.) was further added. did.

(Application conditions)
・ Pre-coating equipment: Extrusion-type slot die ・ Scraping bar equipment: Wire bar with 0.07 mm wire tightly wound around a cylindrical core with a diameter of 8 mm ・ Application speed: 20 m / min ・ Application tension ... 200 N / m
(Backup roller condition)
・ Roller body diameter: 95mm
・ Roller shaft diameter: 32 mm
・ Roundness of pass roller… 0.01mm
-Cylindrical degree of pass roller ... 0.01mm
・ Distance from the bar of the scraping bar device to the pass roller… 100mm
(Elevating method)
A comparison was made between a vertical lift in which the backup roller was moved vertically by a guide and a swing arm in which the backup roller swings in an arc by the roller unit according to the present invention.

  For the vertical lift type, THK HSR20A2SSM + 520LHMII was used as the LM guide, and Yuken F-CJT70-FB50B320B was used as the operating cylinder.

For swing arms, CJT70CB50C-350B-BAD-EK and CJT70CB50C-350B-DAB-EK made by Yuken Kogyo were used as the operating cylinders (there is no guide because the arm draws an arc). SB30 made by THK was used for the arm bearing (spherical bearing).
(Evaluation item)
When the roller peripheral speed is 24 m / min and 28 m / min (the peripheral speed is measured with a rotary encoder (RD-5000 manufactured by Sendai Nikon)), FFT (CF5220 manufactured by Ono Sokki Co., Ltd.) is used as the vibration speed. And measured.

(Test results)
As can be seen from Table 1, the vibration speed when applying with the swing arm of the present invention is higher than the vibration speed when applying the vertical back-and-forth movement with the conventional backup roller operated vertically by the guide. From 1/6 to 1/7, it can be seen that the vibration of the roller during application can be suppressed. Therefore, according to the present invention, the occurrence of coating unevenness can be effectively suppressed.

  In addition, although the example by the application | coating and measurement integrated type is not shown in a figure, it was the same result as the above.

Side surface sectional view showing an example of a coating and metering integrated type, which is a bar coating device according to the present invention. The side view explaining the roller unit concerning the present invention Front view illustrating a roller unit according to the present invention Side surface sectional view showing an example of a separate coating / metering type, which is a bar coating apparatus according to the present invention. Side surface sectional view of the bar device for scraping in FIG. Side sectional view showing an example of an extrusion-type coating apparatus

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Application | coating and measurement integrated type bar application apparatus, 10 '... Application | coating and measurement separate type | mold bar application apparatus, 11 ... Roller main-body part, 13 ... Roller shaft, 14 ... Application liquid, 16 ... Precoat apparatus, 18 ... Scraping Bar device, 20 ... backup roller, 21 ... frame, 21A ... bearing, 21B ... support base, 23 ... cylinder, 25 ... roller unit, 28 ... bar, 30 ... bar support base, 50 ... bar coating head

Claims (4)

A coating apparatus having an advancing / retreating mechanism for applying a coating liquid from a coating head to the surface of a belt-like support that continuously runs while being supported by a backup roller, and for moving the backup roller back and forth between a coating position and a retracted position. In
The advance / retreat mechanism is:
A roller unit configured to rotatably support the rotation shafts at both ends of the backup roller with a bridged frame;
Rocking means for rocking the roller unit so that the backup roller moves back and forth between the application position and the retracted position ;
The roller unit is
A pair of the backup rollers are provided at positions on the upstream side and the downstream side across the coating head,
The center of one rotation axis of the pair of backup rollers and the center of the swinging shaft of the swinging means are the same,
The coating apparatus, wherein the backup roller of the pair of backup rollers having the same rotation axis center and the same swing axis center is a backup roller on the downstream side in the running direction of the belt-like support . The coating apparatus according to claim 1, wherein the coating head is a bar coating head. The coating solution, coating apparatus according to claim 1 or 2, characterized in that a coating solution for producing an optical film or magnetic recording medium. In the application | coating method which performs desorption operation of application | coating with the coating device of any one of Claim 1 to 3 ,
The coating method characterized in that the attaching / detaching operation is performed by swinging together a roller unit formed by rotatably supporting rotating shafts at both ends of the backup roller with a bridging frame.

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