JP2010188254A - Coating apparatus and coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating apparatus and a coating method, for obtaining a coating film with high film thickness accuracy and a smooth surface without coating irregularities. <P>SOLUTION: The coating apparatus 10 includes: a base 12; a pair of frames 14 provided at a prescribed interval on the base 12; a bearing 16 provided on the frames 14; a backup roller 18 supported by the bearing 16 so as to be freely rotated and for supporting a continuously running web on the outer peripheral surface; a coating head 28 disposed facing the backup roller 18 and for supplying coating liquid to the web; and a moving base 26 installed on the base 12 and for supporting the coating head 28. The height (H1) from the base 12 to the axis of the backup roller 18 is ≤800 mm, and the frames 14 have a natural frequency ≥150 Hz. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coating apparatus and a coating method, and more particularly, to a coating apparatus and a coating method for forming a coating film surface having a uniform thickness by coating a coating liquid on a continuously running web.

  In the fields of photographic photosensitive materials and magnetic recording media, a coating process is employed in which a predetermined coating solution is applied to a continuously running belt-like flexible support (hereinafter referred to as “web”) to form a coating film. ing. In recent years, in these fields, there has been a demand for a coating technique capable of obtaining a coating film having high coating film thickness accuracy, a smooth surface and no coating unevenness.

  Similarly, in the coating process applied to the production of an optical film having various functions such as an optical compensation film, an antireflection film, and an antiglare film, the above coating technique is required.

  For example, roll coater type, gravure coat type, roll coat plus doctor type, reverse roll coater type, extrusion type, slide coat type, etc., can be used depending on the application. This is the current situation.

  In any of these coating apparatuses, there is a demand for a coating film having high coating film thickness accuracy, a smooth surface, and no coating unevenness.

  Patent Document 1 discloses a coating apparatus that enables high-precision thin film coating. This coating apparatus uses granite as a backup roller, uses a hydrostatic bearing as a bearing, and uses a linear motor and an air slide as a moving mechanism of the die cradle. By improving the roundness of the backup roll alone, the rotation accuracy when the backup roll is assembled, the unit positioning accuracy, and the level of the die cradle, high-precision thin film coating is possible.

JP 2003-062506 A

  By the way, a variation in the clearance between the backup roller and the coating head is known as a factor that causes coating unevenness on the coating surface. This variation occurs due to vibrations of members constituting the coating apparatus. Even if such a vibration uses granite as a backup roller, uses a hydrostatic bearing as a bearing, and uses a linear motor and an air slide as a moving mechanism of a die cradle, as shown in Patent Document 1. It was difficult to suppress, and it was difficult to sufficiently suppress fluctuations in clearance.

  The present invention has been made in view of such circumstances, and provides a coating apparatus and a coating method capable of obtaining a coating film having a high film thickness accuracy, a smooth surface and no coating unevenness. Objective.

  In order to achieve the above object, a coating apparatus of the present invention includes a base, a pair of frames provided on the base at a predetermined interval, a bearing provided on the frame, and a bearing rotatably supported by the bearing. A backup roller that supports the continuously running web on its outer peripheral surface, an application head that is disposed opposite to the backup roller and that supplies an application liquid to the web, and a movable base that is installed on the base and supports the application head The height (H1) from the base to the axis of the backup roller is 800 mm or less, and the natural frequency of the frame is 150 Hz or more.

  The inventor carefully observed coating unevenness due to the vibration of the coating apparatus, and as a result, the height (H1) from the base to the axis of the backup roller is 800 mm or less, and the natural frequency of the frame is 150 Hz or more. Thus, it has been found that even if application unevenness or application stripes due to the clearance between the backup roller and the application head occur, they are not recognized as application unevenness or application stripes by visual observation. That is, the present inventors have found that coating unevenness and coating stripes can be visually observed by controlling the natural frequency within the above range, instead of completely removing the natural frequency of the frame.

  In the coating apparatus according to the present invention, the height (H1) from the base to the axis of the backup roller and the height (H2) from the base to the coating liquid discharge port of the coating head are as follows. It is preferable to satisfy the formula.

(1) H1 / H2 ≦ 1.1
Further, the present inventor carefully observed the clearance fluctuation between the backup roller and the coating head when coating unevenness occurs, and found that the height (H1) up to the axis of the backup roller relative to the base and coating of the coating head. It has been found that when the height (H2) to the liquid discharge port satisfies the relationship of H1 / H2 ≦ 1.1, the amount of displacement is 0.42 μm or less. The displacement between the backup roller and the coating head appears as a difference between the peaks and valleys of the coating surface. However, it was found that when the difference is 0.42 μm or less, it can be further prevented from being visually observed.

  In the coating apparatus of the present invention, in the above invention, the moving mechanism of the moving table is preferably composed of a ball screw and a guide rail. Thereby, the clearance between the coating head and the backup roller can be easily adjusted.

  In order to achieve the above object, the coating method of the present invention is characterized in that a coating solution is supplied onto a continuously running web using the coating apparatus.

  According to the present invention, the height (H1) from the base to the axis of the backup roller is 800 mm or less, and the natural frequency of the frame is 150 Hz or more, so that the film thickness accuracy is high and the surface is A coating apparatus and a coating method that can obtain a coating film that is smooth and free from coating unevenness can be obtained.

Explanatory drawing explaining the manufacturing line of the optical compensation sheet | seat with which the coating device which concerns on this invention is applied. The side view and front view of a coating device. A graph showing the relationship between the height from the base to the axis of the backup roller and the natural frequency. The figure which shows the positional relationship of the height (H2) from a base to the discharge outlet of a coating head, and the height (H1) from a base to the axial center of a backup roller. The graph which shows the relationship of the displacement amount of the height (H2) from the base to the discharge port of a coating head, the height (H1) from the base to the axial center of a backup roller, and clearance (L).

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention will be described with reference to the following preferred embodiments, but can be modified in many ways without departing from the scope of the present invention, and other embodiments than the present embodiment can be used. be able to. Accordingly, all modifications within the scope of the present invention are included in the claims.

  FIG. 1 is an explanatory view for explaining a production line of an optical compensation sheet, which is a preferred example to which a coating apparatus according to the present invention is applied.

  As shown in FIG. 1, the optical compensation sheet production line is configured such that a web 60, which is a transparent support on which a polymer layer for forming an alignment film is formed in advance, is sent out from a feeder 66. The web 60 is guided by a guide roller 68 and fed into a rubbing processing device 70. The rubbing roller 72 is provided for performing a rubbing process on the polymer layer. A dust remover 74 is provided downstream of the rubbing treatment device 70, and dust attached to the surface of the web 60 can be removed.

  A coating device 10 is disposed downstream of the rubbing processing device 70. The coating apparatus 10 applies, for example, a coating liquid containing disconematic liquid crystal to the web 60. Further, a drying zone 76 and a heating zone 78 are sequentially provided on the downstream side. A liquid crystal layer is formed on the web 60 through the drying zone 76 and the heating zone 78. Further, an ultraviolet lamp 80 is provided downstream of this, and the liquid crystal is cross-linked by ultraviolet irradiation to form a desired polymer. And the web 60 in which the polymer was formed is wound up by the winder 82 provided downstream.

  In the optical compensation sheet production line of FIG. 1, while feeding the web 60 from the delivery device 66, the flow rate of a pump (not shown) so that the average flow rate of the coating liquid of the coating head of the coating apparatus 10 is 100 to 500 mm / second. In addition, the coating is performed by controlling the conveyance speed of the web 60 so that the thickness of the coating film immediately after coating becomes a predetermined thickness.

  In drying after coating, the drying zone 76, the heating zone 78, the ultraviolet lamp 80, etc. are set so that a coating film having a high thickness accuracy and a smooth surface can be obtained. The web 60 after coating and drying is wound up by a winder 82.

  It is preferable that the above-described series of steps is performed in an environment of good dust-freeness and optimum temperature and humidity. Therefore, it is preferably performed in a clean room, and in particular, the coating apparatus 10 is preferably installed in an environment of class 100 or less.

  FIG. 2 shows a side view and a plan view of the coating apparatus. The coating apparatus 10 includes a base 12, a pair of frames 14 provided on the base 12 at a predetermined distance, a bearing 16 provided on the frame 14, and a backup roller rotatably supported via the bearing 16. 18 is provided.

  Further, a pair of guide rails 22 is provided on the base 12, and a ball screw 24 is provided between the pair of guide rails 22. On the pair of guide rails 22, a movable table 26 that can move along the guide rails 22 is installed. The coating head 28 is fixed on the moving table 26 via the mounting table 30 and is disposed to face the backup roller 18.

  The distance between the backup roller 18 and the coating head 28 can be adjusted so that the type of coating solution applied to the web and the thickness of the coating solution can be adjusted optimally. The distance is adjusted by rotating the ball screw 24 by a driving means (not shown), so that the rotational motion is transmitted to the movable table 26 as a straight motion. The moving table 26 moves forward / backward along the guide rail 22, and thereby the distance between the coating head 28 on the moving table 26 and the backup roller 18 is adjusted.

  In the coating apparatus 10 having the above-described configuration, the present inventors diligently studied the cause of coating unevenness, and found that the vibration of the constituent members of the coating apparatus 10 is related to the occurrence of coating unevenness. In particular, when the vibrations of the bearing 16 and the frame 14 of the coating apparatus 10 resonate, the clearance variation between the backup roller 18 and the coating head 28 occurs and appears as coating unevenness. In order to avoid resonance, the natural frequency of the frame 14 is adjusted to 150 Hz or more by adjusting the height of the frame 14 so that the height (H1) from the base 12 to the axis of the backup roller 18 is 800 mm or less. It was. At this time, by setting the natural frequency of the frame 14 to 150 Hz or more, even if the clearance between the backup roller 18 and the application head 28 fluctuates and application unevenness or application stripes occur, I found that it was not recognized. That is, the present inventors have found that coating unevenness and coating stripes can be visually observed by controlling the natural frequency within the above range, instead of completely removing the natural frequency of the frame.

  FIG. 3 is a graph showing the relationship between the height from the base to the axis of the backup roller and the natural frequency. As shown in FIG. 3, when the height (H1) from the base to the axis of the backup roller is increased, the natural frequency of the frame is decreased. On the other hand, when H1 is decreased, the natural frequency of the frame is increased. Become. As is apparent from FIG. 3, it can be understood that the natural frequency of the frame can be 150 Hz or more by setting the height of H1 to 800 mm or less. By setting the natural frequency of the frame to 150 Hz or more, it can be prevented from being recognized as coating unevenness or coating stripes in visual observation.

  FIG. 4 shows the positional relationship between the height (H2) from the base 12 to the discharge port of the coating head 28 and the height (H1) from the base 12 to the axis of the backup roller 18. In order to facilitate understanding of the positional relationship between the discharge port of the coating head 28 and the backup roller 18, the bearings on the frame 14 are omitted.

  As a result of intensive studies on the amount of displacement of the clearance (L) between the backup roller 18 and the coating head 28 and the occurrence of coating unevenness, the present inventor has determined that the amount of displacement of the clearance (L) between the backup roller 18 and the coating head 28 is zero. In addition to setting the natural frequency of the frame to 150 Hz or more, it has been found that the film is not visually observed. That is, if the displacement amount is 0.42 μm or less, even if the clearance (L) fluctuates and application unevenness or application streaks occur on the surface of the application film, it can be prevented from being recognized by visual observation.

  Furthermore, as a result of studying the conditions under which the clearance (L) displacement amount is 0.42 μm or less, the present inventor has found that the height (H2) from the base 12 to the discharge port of the coating head 28 and the backup roller 18 from the base 12. It has been found that the amount of displacement of the clearance (L) becomes 0.42 μm or less by making the height (H1) to the axis of the distance constant.

  FIG. 5 is a graph showing the relationship between H1 / H2 and the displacement amount of the clearance (L). From the graph of FIG. 5, it can be understood that the displacement amount of the clearance (L) decreases as H1 / H2 decreases. In particular, when the relationship of H1 / H2 ≦ 1.1 is satisfied, it can be understood that the displacement amount of the clearance (L) is 0.42 μm or less.

  The formation of a coating film using the coating apparatus 10 will be described. As the coating solution, for example, a coating solution having a viscosity of 10 mPa · s or less and containing an organic solvent can be used. However, the thing of viscosity other than this and the thing which does not contain an organic solvent can also be used.

  As the web 60, in general, polyethylene terephthalate (PET), polyethylene-2,6-naphthalate having a predetermined width, a predetermined length, and a thickness of about 2 to 200 μm, cellulose diacetate, cellulose triacetate, cellulose acetate propionate, Paper coated with α-polyolefins having 2 to 10 carbon atoms, such as polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyimide, polyamide, etc., paper, polyethylene, polypropylene, ethylene butene copolymer, etc., metal A flexible strip made of a plate or the like or a strip having a processed layer formed on the surface of the strip can be used.

  As mentioned above, although embodiment of the coating device which concerns on this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  Further, the application of the coating apparatus 10 can be applied not only to an optical film such as an optical compensation film but also to various coatings.

DESCRIPTION OF SYMBOLS 10 ... Application | coating apparatus, 12 ... Base, 14 ... Frame, 16 ... Bearing, 18 ... Backup roller, 22 ... Guide rail, 24 ... Ball screw, 26 ... Moving base, 28 ... Coating head, 30 ... Mounting base, 60 ... Web, DESCRIPTION OF SYMBOLS 66 ... Sending machine, 68 ... Guide roller, 70 ... Rubbing processing apparatus, 72 ... Rubbing roller, 74 ... Dust remover, 76 ... Drying zone, 78 ... Heating zone, 80 ... Ultraviolet lamp, 82 ... Winder

Claims (4)

Base and
A pair of frames provided on the base at a predetermined interval;
A bearing provided on the frame;
A backup roller rotatably supported by the bearing, and supporting a continuously running web on the outer peripheral surface;
An application head disposed opposite to the backup roller and supplying an application liquid to the web;
A coating device installed on the base and supporting the coating head;
A coating apparatus, wherein a height (H1) from the base to the axis of the backup roller is 800 mm or less, and a natural frequency of the frame is 150 Hz or more. 2. The coating apparatus according to claim 1, wherein a height (H1) from the base to an axis of the backup roller and a height (H2) from the base to a coating liquid discharge port of the coating head are as follows. Coating device that satisfies the formula.
(1) H1 / H2 ≦ 1.1   3. The coating apparatus according to claim 1, wherein the moving mechanism of the moving table is configured by a ball screw and a guide rail.   The coating method which supplies a coating liquid on the web which runs continuously using the coating device of any one of Claims 1-3.

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