JPH04371258A - Method and device for coating with resin solution - Google Patents

Abstract

PURPOSE:To fill a resin soln. storage tank with the saturated vapor of the solvent at all times, to keep the solute concn. in the soln. constant, to prevent the formation of a surface film and to obtain a uniform coating by providing a lid, a solvent supply hole and an adsorbing member to be impregnated with the solvent to the tank. CONSTITUTION:A sheet 4 is coated with a resin soln. 2 through a sheet conveying roller 3 and a doctor blade 5. In this case, a resin soln. storage tank 1 is filled with the vapor of the solvent for the soln. 2 during the coating. Accordingly, a lid 6, a solvent supply hole 7 and an adsorbing member 8 to be impregnated with the solvent are provided to the tank 1. As a result, since the tank 1 is always filled with the saturated vapor of the solvent, the solute concn. in the soln. is kept constant, and a uniform coating is obtained without the formation of the surface film. Furthermore, the selection range of the solvent is widened, and the workability is improved.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method and apparatus for coating an object with a resin solution.

[
0002

[Prior Art/Problems to be Solved by the Invention] When coating an object with a synthetic resin in a relatively volatile organic solvent, especially as a highly concentrated and highly viscous solution that is almost saturated, it is necessary to As the solvent evaporates, the concentration and viscosity change, resin components precipitate on the surface, and a film-like substance forms.
Occurrence of uneven wrinkles and bumps on the surface of the object to be coated,
It is known that film-like particles may be mixed in and cause coating defects and quality deterioration, especially when coating a thin layer. Specific examples of this include, for example, magnetic tape, photographic film, and coatings for EL lamps. The case of an EL lamp will be described below as one example.

[0003] EL elements have a light-emitting layer made of a phosphor with an active substance dispersed in plastic.
This is an electroluminescent device sandwiched between electrodes, and EL lamps using this device have been put into practical use as backlights for various instruments, backlight sources for liquid crystal displays, panel displays for personal computers, and wall lighting. The general structure of an EL lamp is protected by upper and lower moisture-proof films, and a back lead electrode, a back electrode layer, an insulating voltage layer, a light emitting layer, a front lead electrode, and a transparent electrode layer are stacked one after another on the back moisture-proof film. It is. The lamination of the light-emitting layer and the dielectric strength layer, which are the main components, is
Generally, phosphor particles such as zinc sulfide are suspended in a resin solution in which a plastic material is dissolved.The bottom surface of a resin solution storage chamber is placed on an electrode layer such as aluminum foil that is conveyed by a roller or the like, and barium titanate is added as a resin component. It is manufactured by coating the resin solution on a sheet in which dispersed dielectric strength layers are laminated.

[0004] At this time, the resin solution in which fine particles such as phosphors are dispersed is prepared by using resin components with high dielectricity, such as modified cyanoethyl cellulose, cyanoethyl pullulan, fluororesin, etc., as a solvent to improve boiling point, solubility, stability, drying property, etc.
Due to various conditions such as adhesion to the base material, those dissolved in dimethylformamide or ethyl cellosolve are mainly used. However, this resin solution has a high concentration (generally 20-50%) that is as close to saturation as possible, and the solvent evaporates during stirring and coating, resulting in a viscosity (generally 1000-50%).
100,000 cP), the concentration is easy to change, and as a result, the resin tends to precipitate on the surface and a film-like substance is easily formed, causing unevenness and bumps on the smooth surface of the light emitting layer that forms a thin layer, causing the coating to deteriorate. This may cause defects.

Furthermore, if a solvent with a low boiling point is used as a resin solvent, the above-mentioned film-like substance is likely to be formed, and if a solvent with a high boiling point is used, the drying temperature after coating becomes high and the drying time becomes longer, resulting in problems with quality and manufacturing work. There was a problem that it was difficult to control. This kind of phenomenon is EL
This problem is not limited to lamps. An object of the present invention is to provide a method of coating a highly concentrated resin solution and an apparatus therefor that are free from the above-mentioned drawbacks.

[0006]

[Means for Solving the Problems] The present invention was completed with the aim of solving these problems.
The gist of the invention is as follows. (2) A method for coating a resin solution, which comprises coating an article with a resin solution in a state where the resin solution exists in an atmosphere of solvent vapor used as a solvent for the solution. (2) A resin coating apparatus having a resin solution reservoir that is sufficiently sealed to maintain the resin solution in the solvent vapor atmosphere used as a solvent for the solution. (2) A resin coating device having a resin solution storage tank including at least a lid and an adsorption member for solvent impregnation provided in a position not immersed in the resin solution. (2) A resin coating device having a resin solution storage tank including at least a lid, an adsorption member for impregnation with a solvent provided in a position not immersed in the resin solution, and a hole for impregnating the adsorption member with a solvent.

The resin solution used in the present invention is generally a solution in which a synthetic resin component is dissolved in a volatile organic solvent having a relatively low boiling point to a high concentration close to saturation. This resin solution may further have a suitable solute dissolved therein or insoluble fine particles dispersed or suspended therein. In the coating method of the present invention, the solvent vapor atmosphere refers to an atmosphere in which the solvent vapor is usually 60% or more, preferably 80% or more, particularly preferably 90% or more, and may be in a supersaturated state. .

The resin solution of the present invention is supplied from the reservoir to the coating surface of the workpiece, and the reservoir is maintained in an atmosphere of solvent vapor used as a solvent for the resin solution. It is necessary that the storage tank be sufficiently sealed, and in order to maintain this condition, it is preferable that the storage tank is provided with a lid. In addition, in order to create an atmosphere with a higher concentration of solvent vapor, an adsorption member for solvent impregnation should be provided in a position within the storage tank that is not immersed in the resin solution, and the adsorption member should be impregnated with the solvent. is preferred. Furthermore, it is preferable to have a reservoir provided with holes for supplying and impregnating the adsorption member with a solvent. Therefore, an appropriate amount of solvent is supplied at any time through this small hole for solvent replenishment, so that the adsorption member near the hole is constantly impregnated with the replenishment solvent, and the space in the storage tank is maintained under saturated vapor of the solvent.

The small hole for replenishing the solvent and the adsorption member for impregnating the solvent may be attached to the side wall of the upper space of the storage tank or to the lid. The lid can be opened/closed and removed freely. The hole only needs to be able to inject the solvent, and its diameter is usually 1 m.
m to 50 mmφ, and the solvent supplied through the hole is guided to the adsorption member. The adsorption member may be made of any material that can impregnate and adsorb the solvent, such as absorbent cotton,
Examples include gauze, cotton fabric, nonwoven fabric, rubber, and plastic sponges such as polyurethane. These may be of appropriate size and capacity and may be attached near the holes by appropriate means to prevent them from falling.

[0010] In the coating method of the present invention, the resin solution is coated on the object to be coated in a solvent vapor atmosphere, and in the coating apparatus of the present invention, the structure of the resin solution reservoir is There are certain characteristics, and conventionally known methods can be used as appropriate for other objects to be coated and coating treatment means.

For example, EL lamps require particularly accurate, homogeneous, and thin coatings, and are one example of where the present invention may be advantageously used, but are not limited thereto. A technical field that aims to solve the problem of film formation on the surface of the resin solution and non-uniformity of the coating surface that occurs when coating the object to be coated with a resin solution that tends to precipitate components to a certain thickness. can also be applied.

0012

[Example] As a specific example of the present invention, for example, E.
The coating of the L element will be described in detail below. FIG. 1 schematically shows a side sectional view of the coating apparatus. In the figure, 1 is a resin solution storage tank, 2 is a resin solution, 3 is a sheet conveyance roller, and 4 is a sheet to be coated with an electrode layer such as aluminum foil (thickness: 50 to 300 μm).
), on which an insulating layer (thickness 10 to 50 μm) made of a resin component containing barium titanate is laminated, 5 is a doctor blade, 6 is an adsorption member with a small hole 7 formed in the lower part thereof and impregnated with a resin solvent. The sealing lid with 8 attached is shown. Note that the structure other than the sealing lid is a known structure. In the figure, a sealing lid is provided at the top of the resin solution storage tank, a small hole is provided in the lid for injecting and replenishing the resin solvent, and an adsorption member impregnated with the solvent is attached to the bottom of the lid. Therefore, the resin solution storage tank is kept in a nearly hermetically sealed state by the lid, and the storage tank is kept free of solvent at all times by replenishing the solvent through the small hole in the lid and by the adsorption member attached to the inner surface of the lid that impregnates the solvent. It is maintained in a saturated steam atmosphere.

A coating sheet for an EL lamp was prepared using the apparatus of the present invention shown in FIG. 1 under the following conditions. A homogeneous resin solution was prepared by adding 25 parts of modified cyanoethyl cellulose and 50 parts of dimethylformamide to 100 parts of phosphor particles made of zinc sulfide, and the mixture was placed in a storage tank. Attach a flat adsorption member and replenish dimethylformamide from the small hole as appropriate to keep the absorbent cotton impregnated at all times. An insulating layer (20 to 30 μm thick) containing barium titanate on aluminum foil (100 μm thick) is placed on the bottom of the resin solution storage tank.
) was conveyed by a roller at a speed of 3 m/min, coated with the resin solution by a doctor blade, and dried for 5 minutes at a drying temperature of 120°C to form an EL element coated with a luminescent layer (thickness: 50 mμ). Obtained.

Test Example 1 As a comparative example, an EL device coated with a light-emitting layer was produced by performing the same treatment under the open conditions without a lid. When we investigated the occurrence rate of defective products between this and the EL elements produced by the method of the present invention, the occurrence rate of defective products was 0% in the present invention, whereas it was 5 to 15% in the comparative example.
We looked at the occurrence of defective products at a rate of . Note that defective products here refer to those that have uneven wrinkles, bumps, and inclusion of film-like particles due to film-like substances generated on the surface of the resin solution 2, and the incidence of defective products is as follows: As shown in FIG. 2, in a coated article obtained by coating a long object, it refers to the ratio of the length (La) of the defective coating part to the total length (L) of the coated article. In addition, in this test, the total length of the coated object was 50 m.

[0015]

As explained above, the present invention provides a method for coating an object with a resin solution in a state where the inside of the storage tank is under a solvent vapor atmosphere of the resin solution, and a method for coating the object with the resin solution, and a method for coating the object with the resin solution. Since the resin solution storage tank is equipped with an adsorption member and a solvent supply hole, the resin solution storage tank is always maintained under a saturated vapor atmosphere of the solvent, so the solute concentration of the resin solution is constant and the formation of a surface film is prevented. This eliminates coating defects and provides coatings of uniform quality. Furthermore, since the degree of freedom in selecting a solvent is increased, a solvent suitable for drying conditions and solute dissolution can be selected, and workability is improved.

[0016]

[Brief explanation of drawings]

FIG. 1 is a schematic side sectional view of an embodiment of a device used in the method of the present invention.

FIG. 2 is a diagram showing the occurrence of the length of a defective coating portion in a coated long object.

[0017]

[Explanation of symbols]

1 Resin solution storage tank 2 Resin solution 3 Sheet conveyance roller 4 Sheet 5 made of aluminum foil coated with an insulating layer
Doctor blade 6 Sealing lid 7 Small hole 8 Adsorption member L Total length of coated object La Length of defective coating part

Claims (4)

[Claims] 1. A method for coating a resin solution, which comprises coating an article with a resin solution in a state where the resin solution exists in an atmosphere of solvent vapor used as a solvent for the solution. 2. A resin coating apparatus having a resin solution reservoir sufficiently sealed to maintain the resin solution in an atmosphere of solvent vapor used as a solvent for the solution. 3. A resin coating apparatus having a resin solution storage tank including at least a lid and an adsorption member for solvent impregnation provided at a position not immersed in the resin solution. 4. A resin solution reservoir having at least a lid, an adsorption member for impregnation with a solvent provided in a position not immersed in the resin solution, and a hole for impregnating the adsorption member with a solvent. Coating equipment.