JP2009078221A - Die head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die head which does not allow a coating solution discharged from the slit to wet and spread on both sides and enables stable coating by forming a coating applied to a support with a specified coating width. <P>SOLUTION: The die head has a flat tip surface and a tip side surface of a lip which is sandwiched with side plates on both sides and contains a slit formed by at least two blocks and discharging a coating solution. Surface-treated layers water- and oil-repelling to the coating solution are formed on the upper surface of the tip of the side plate connected with the tip surface of the lip and the side surface of the tip of the lip. After an electroless nickel plating containing a fluorine resin having water-oil repellency is applied to the die head, the load due to the heat treatment is eliminated to stabilize coating, and the die head is then subjected to mirror surface grinding to stabilize the coating. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a die head used in a die coater for applying a coating solution onto a continuously running belt-like support such as an optical film.

  Conventionally, gravure coaters, knife coaters, bar coaters, air doctors, curtain coaters, slide coaters, and die coaters have been used as coating methods for coating a coating solution on a continuous belt-like support (hereinafter referred to as a web). And so on. Among these coating methods, die coaters that are hermetically sealed and have excellent film thickness uniformity and smoothness in the width direction are often used. In such a die coater, the coating liquid is extruded from the slit of the die head and applied while forming beads on a continuously running web. In general, this die head is formed by combining two or more blocks sandwiched from both sides by a side plate to form a slit, and a supply port for supplying the coating liquid and the supplied coating liquid are once retained and stored. This is a coating method having a manifold portion for spreading in the width direction and flowing uniformly in the longitudinal direction, and a slit for causing the coating liquid to flow uniformly from the manifold in the width direction and discharging from the lip.

  However, it is necessary for the bead formation that the lip tip surface of the die head has good wettability with respect to the coating liquid, but the side surface of the lip tip and the side plate tip part, which are usually made of the same material, also have good wettability with respect to the coating solution. The coating liquid wets and spreads on the upper surface of the tip of the side plate at both ends of the lip, and the coating width with respect to the web is wider than the slit width, which causes a problem that cannot be stably regulated. Further, the coating liquid may also spread on the side surfaces of the lip tip and the side plate tip, making the bead unstable or solidifying without transferring to the web. This causes a problem of causing coating defects such as streaks and unevenness in the flow direction.

  For example, in a coating solution containing particles used for an AG (Anti-Glare) film used on the surface of a liquid crystal display panel, particularly a coating solution containing particles having a high sedimentation speed, the distance from the inside of the die head, particularly the supply port, is increased. On the other hand, particles on the opposite side are liable to settle, and the deposition amount becomes unstable due to accumulation over time, and coating defects such as shading unevenness and streaks are likely to occur. In this case, in most cases, the problem cannot be solved unless the die head is disassembled and cleaned.

Therefore, in order to prevent the coating liquid from spreading from the lip tip, applying a water / oil repellent treatment to the lip tip, or applying an electroless nickel plating process or a DLC (diamond-like carbon) process, It corresponds.
JP 2004-50025 A

  However, when a water / oil repellent treatment agent is applied to the lip tip, the coating solution always comes into contact, or wiping the tip of the lip during cleaning deteriorates the water / oil repellency, resulting in durability. The problem remains. In addition, there is no problem in durability in the electroless nickel plating process or the DLC (diamond-like carbon) process, but since the heat treatment at 100 to 300 ° C. is required for performing the above process, there is a concern about deformation of the die head. In particular, in the thin film coating of an optical film or the like, since the uniformity of the film thickness distribution in the width direction becomes important, careful attention must be paid to the deformation of the die head. Further, in the above processing, it is necessary to reduce the contact angle with respect to the coating liquid on the upper surface of the lip tip, and the coating width discharged by the coating liquid discharged from the slit spreads laterally only by the surface treatment of the side surface of the lip tip in the coating direction. It spreads and the edge of the coated surface becomes thick. An object of the present invention is to provide a die head in which a coating liquid discharged from a slit does not wet and spread on both sides, is applied to a support with a prescribed coating width, and enables stable coating.

  The invention according to claim 1 of the present invention is a die head for applying a coating liquid to a continuously running support, and is formed by at least two blocks sandwiched from both sides by a side plate. In a die head having a flat lip tip surface of a lip including a slit for discharging a coating liquid and a lip tip side surface, an upper surface of a side plate tip connected to the lip tip surface and a side connected to the lip tip side surface The die head is characterized in that a water-repellent and oil-repellent surface treatment layer is formed on the side surface of the plate tip with respect to the coating solution.

  The invention according to claim 2 of the present invention is the die head according to claim 1, wherein a water-repellent and oil-repellent surface treatment layer for the coating liquid is formed on the manifold. .

  According to a third aspect of the present invention, in the die head according to the first or second aspect, a surface treatment layer having water repellency and oil repellency to the coating solution is formed on the side surface of the lip. It is a die head.

  The invention according to claim 4 of the present invention is the die head according to any one of claims 1 to 3, wherein the surface treatment layer is a fluorine resin-containing electroless nickel plating in which a fluorine resin is uniformly dispersed and co-deposited. A die head characterized in that a layer is formed to provide water repellency and oil repellency with a contact angle of 60 ° or more with respect to the coating solution.

  According to a fifth aspect of the present invention, in the die head according to the fourth aspect, after the formation of the fluororesin-containing electroless nickel plating layer, a mirror grinding process is performed to increase the accuracy of the die head. It is a die head.

  In the present invention, in order to prevent the coating liquid from spreading to both ends of the die head lip and climbing up to the top surface of the side plate tip, the surface of the top surface of the side plate and the side surface of the side plate tip are water-repellent and oil-repellent to the coating solution. A treatment layer is formed. Preferably, the side surface of the lip tip is similarly subjected to electroless nickel plating containing a fluororesin having water and oil repellency. For example, in a TAC (Tri Acetyl Cellulose) film frequently used as a base material for an optical film such as a protective film for a polarizing plate, both sides of the film are knurled and thickened to prevent blocking. The stability of is particularly important. Variations in the coating width and the thickness of the edge portion are not limited to partial defects, but affect the stability of the entire take-up roll coated with the coating liquid, often leading to optical distortion and defects.

  Next, in order to eliminate the influence of the deformation of the die head due to the surface treatment, the top surface of the lip tip, the inner surface of the side plate and the top surface of the tip are mirror ground after the surface treatment. Thereby, the influence of the thermal deformation by this surface treatment can be improved, and processing accuracy can be obtained. Through the above processing, the coating liquid discharged from the slit does not wet and spread on both sides, and is applied to the support with a prescribed coating width, thereby enabling stable coating. For example, in thin film coating of optical films such as anti-reflection films used on the surface of car navigation devices and mobile display devices, it is important that the lip tip drains and the film thickness distribution is uniform in the width direction. Therefore, in order to improve the processing accuracy that affects them, the tip of the lip is made of a cemented carbide alloy, electroless nickel plating treatment containing fluorine resin is applied, and after being bonded to the die head, mirror grinding is performed. By doing so, it is possible to cope with the problem of machining accuracy.

  Furthermore, by subjecting the manifold to an electroless nickel plating treatment that contains water- and oil-repellent fluororesin, the deposits in the manifold can be easily removed, and the remaining coating solution can be easily removed and washed. Moreover, even if a problem due to sediment occurs during application, it can be removed by increasing the flow rate in the manifold. A guideline for the flow velocity at this time is to set the flow velocity so as to be a turbulent flow region having a Reynolds number of 4000 or more.

  In the present invention, by providing water repellency and oil repellency functions to the tip of the side plate and the manifold constituting the die plate, it is possible to stably apply the end in the width direction to the continuously running web, Moreover, efficient cleaning becomes possible. By using the die head of the present invention, it is possible to prevent the coating liquid from spreading to both ends of the lip and to prevent coating defects due to riding on the top end of the side plate, and to improve the influence of heat treatment and deformation of the die head. In addition, the cleaning effect can be improved even when the inside of the manifold is cleaned, particularly when a coating solution that easily settles is used.

  Hereinafter, the present invention will be described in detail based on an embodiment.

  FIG. 1 is a schematic view illustrating a coating section of a coating apparatus using a die head according to the present invention in cross section. As an application method, either an on-roll method applied to a web backed up by a roll as shown in FIG. 1A or an off-roll method (not shown) may be used. Further, the die head 1 may be disposed on the side or the lower side of the backup roll 11 and applied without any limitation. The coating liquid 8 supplied from the pump 23 passes through the manifold 3 and the slit 4, and then forms a bead portion 9 and is applied to the web 10.

  Further, a fluorine resin-containing electroless nickel plating layer 3A is provided on the manifold 3, a fluorine resin-containing electroless nickel plating layer 6A on the side surface of the upstream lip 5A, and a fluorine resin-containing electroless nickel plating layer 6B on the side surface of the downstream lip 5B. Although not shown, a fluororesin-containing electroless nickel plating layer is formed on the upper surface of the side plate tip and the side surface of the side plate tip on both sides. A bead is formed at the edge portions 7A and 7B at the tip of the lip, and the coating liquid 8 is held.

  FIG. 2A is a schematic diagram of the upstream block 2 </ b> A of the die head 1. A fluororesin-containing electroless nickel plating 6A is applied to the side surface of the upstream lip tip 5A of the upstream block 2A. Further, the surface of the manifold 3 is subjected to fluorine resin-containing electroless nickel plating 3A. The upstream slit 4A is not subjected to surface treatment. FIG. 2B is a schematic diagram of the downstream block 2 </ b> B of the die head 1. A fluororesin-containing electroless nickel plating 6B is applied to the side surface of the downstream lip tip 5B of the downstream block 2B. The downstream slit 4B is not subjected to surface treatment.

FIG. 3 is a schematic view of the die head 1. The die head 1 includes at least an upstream block 2A, a downstream block 2B, and side plates 12A and 12B. The side plate is integrated as a die head by sandwiching the upstream block and the downstream block from both sides. The side plates 12 </ b> A and 12 </ b> B are provided with a supply port 13 for supplying the coating liquid 8 into the manifold 3. Further, a fluorine resin-containing electroless nickel plating layer 6A is formed on the side surface of the upstream lip tip 5A, and a fluorine resin-containing electroless nickel plating layer 6B is also formed on the side surface of the downstream lip tip 5B. In addition, an electroless nickel plating containing fluororesin is applied to the upper surface of the tip of the side plate that is connected to the lip tip surface and the side surface of the side plate that is connected to the side surface of the lip tip. That is, the fluororesin-containing electroless nickel plating layers 14A and 14B are applied to the top surfaces of the tips of the side plates 12A and 12B, and the fluororesin-containing electroless nickel plating layers 15A and 15B are applied to the side surfaces of the tips. The inner surface that is in contact with the slit is not subjected to surface treatment except for the mandrel portion.

  FIG. 4 is a schematic diagram of the upstream block 16A and the downstream block 16B of the die head 1 when the material of the lip tip is changed. FIG. 4A shows a structure in which the lip tip 17A can be changed in the upstream block 16A, and the fluororesin-containing electroless nickel plating layer 6A is formed on the upstream side surface. Further, the fluororesin-containing electroless nickel plating layer 3A is similarly formed on the manifold 3. FIG. 4B shows a structure in which the lip tip 17B can be changed in the downstream block 16B, and a fluororesin-containing electroless nickel plating layer 6B is formed on the downstream side surface. The above is a die head having a structure in which the lip tips 17A and 17B can be changed. The die head may be made of a material different from the base material, for example, a cemented carbide, or may be applied when only the tip shape is changed with the same material as the base material. It is preferable to form a fluororesin-containing electroless nickel plating layer on the side surface of the tip. Even in this case, it is important that the fluorine resin-containing electroless nickel plating layers 14A and 14B are provided on the top surface of the tip of the side plate, and the fluorine resin-containing electroless nickel plating layers 15A and 15B are provided on the side surface of the tip.

  In the application with the die head, the lip portion needs to have a low contact angle with respect to the coating solution and good wettability in order to form a stable bead. In order to prevent the coating liquid from reaching the side surface of the lip tip, the difference in contact angle between the lip portion and the side surface of the lip tip should be 5 degrees or more. In order to obtain stability at the coating end surface, which is the maximum purpose, the bead of the coating solution present on the lip tip surface that is connected in the same plane does not spread on the top surface of the side plate tip. Strong water repellency or oil repellency is required, and the contact angle with respect to the coating liquid at this time is preferably 60 ° or more. In the case of less than this, when the coating speed is increased and the discharge amount of the coating liquid is increased, there arises a problem that the stability of the coating end face is lowered.

  First, in order to form the fluororesin-containing electroless nickel plating layer on the die head blocks 2A, 2B and the side plates 12A, 12B, the blocks 2A, 2B, In the process of immersing the side plates 12A and 12B and depositing the plating metal by the chemical reduction action, the metal nickel film containing the fluororesin fine particles is formed on the object to be plated by repeatedly adsorbing the fluororesin fine particles together with the plating. Go.

  The surface on which the fluororesin-containing electroless nickel plating layer is formed includes the inside of the manifold 3 of the upstream block 2A and the side surface of the lip tip 5A, the side surface of the lip tip 5B of the downstream block 2B, and the top surfaces of the side plates 12A and 12B. 14A, 14B and tip side surfaces 15A, 15B, which are essential. The reason why the side plates 12A and 12B and the upper surfaces 14A and 14B are formed is that, as described above, when the coating liquid is discharged from the slit 4, it does not spread to both sides, and the coating is stabilized with a prescribed coating width. It is. In order not to make the coating unstable due to the water / oil repellency, the fluororesin-containing electroless nickel plating layer on the upper surfaces of the slit surfaces 4A and 4B and the lip tips 5A and 5B needs to be removed by polishing. In addition, when the method which does not form a fluororesin containing electroless nickel plating layer is employ | adopted for the said surface, the removal method is not restricted only to grinding | polishing. Further, the surface other than the above is not limited to the presence or absence of formation.

  Since heat treatment is applied in forming the fluororesin-containing electroless nickel plating layer, the die head 1 and the side plates 12A and 12B are deformed. In order to maintain the processing accuracy, mirror grinding is performed on the slits 4A and 4B and the lip tips 5A and 5B. Further, when a material different from the base material is used for the lip tip, each of the members 16A, 16B, 17A and 17B is subjected to a surface treatment in the same manner as described above.

  Further, as a method for efficiently removing deposits generated when using a coating solution containing particles, particularly a coating solution having a high sedimentation rate, the manifold 3 is provided with a fluororesin-containing electroless nickel plating layer 3A, and By making the Reynolds number in the manifold 3 a turbulent flow region of 4000 or more, deposits can be efficiently removed.

  As described above in detail, the present invention prevents the spreading and spreading of the coating liquid to the width direction and the side surface of the tip of the die head lip, and prevents the top surface and side surfaces of the side plate and the tip of the lip to stabilize the coating. The side surface of this is subjected to a fluorine resin-containing electroless nickel plating treatment having water and oil repellency. In addition, in order to eliminate the influence of the deformation of the die head due to the treatment, the accuracy of the die head can be improved by performing the mirror grinding of the lip tip surface and the slit portion after the fluororesin-containing electroless nickel plating treatment. As a result, the coating liquid discharged from the slit does not spread on both sides, and stable coating with a prescribed coating width becomes possible. In addition, by applying the same treatment to the manifold, it is possible to cope with cleaning performance, particularly removal of deposits by a coating solution having a high sedimentation rate.

Schematic explaining the application | coating part of the coating device using the die head which concerns on this invention in a cross section. (A) is a schematic diagram of an on-roll type die coater. (B) is the expansion schematic of an application part. The schematic of the block which comprises the die head which concerns on this invention, and forms a slit. (A) is the schematic of an upstream block. (B) is the schematic of a downstream block. 1 is a schematic view of a die head according to the present invention. Schematic of the other block which comprises the die head which concerns on this invention, and forms a slit. (A) is the schematic of the upstream block which can change a lip. (B) is the schematic of the downstream block which can change a lip.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Die head 2A ... Upstream side block 2B ... Downstream side block 3 ... Manifold 3A ...... Fluorine resin containing electroless nickel plating 4 ... Slit 4A ... Upstream side Slit 4B ... Downstream slit 5A ... Upstream lip 5B ... Downstream lip 6A ... Upstream fluororesin-containing electroless nickel plating layer 6B ... Downstream fluororesin-containing electroless nickel plating layer 7A: Upstream lip edge portion 7B: Downstream lip edge portion 8 ... Coating liquid 9 ... Bead portion 10 ... Support (web)
DESCRIPTION OF SYMBOLS 11 ... Backup roll 12A, B ... Side plate 13 ... Supply port 14A, B ... Side plate front end upper surface fluororesin containing electroless nickel plating layer 15A, B ... Side plate front end side fluororesin Contained electroless nickel plating layer 16A ... upstream block 16B ... downstream block 17A ... upstream lip tip member 17B ... downstream lip tip member 21 ... pipe 22 ... tank 23 ··pump

Claims (5)

  A die head for applying a coating liquid to a continuously running support, the plane of a lip including a slit for discharging the coating liquid formed by at least two blocks sandwiched from both sides by a side plate In a die head having a lip tip surface and a lip tip side surface, an upper surface of the side plate tip continuous with the lip tip surface and a side surface of the side plate tip continuous with the lip tip side surface are applied to the coating liquid. A die head, wherein a water-repellent and oil-repellent surface treatment layer is formed.   2. The die head according to claim 1, wherein a surface treatment layer having water repellency and oil repellency for the coating liquid is formed on the manifold.   3. The die head according to claim 1, wherein a water-repellent and oil-repellent surface treatment layer is formed on the side surface of the lip tip with respect to the coating solution. 4.   The die head according to any one of claims 1 to 3, wherein a fluororesin-containing electroless nickel plating layer in which a fluororesin is uniformly dispersed and co-deposited is formed as a surface treatment layer and contacted with a coating solution. A die head characterized by having water repellency and oil repellency of 60 ° or more.   5. The die head according to claim 4, wherein after the formation of the fluororesin-containing electroless nickel plating layer, mirror grinding is performed to increase the accuracy of the die head.

Images