JP2008137187A - Transfer film, light emitting device, and coating for forming functional layer of transfer film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer film which can form a fluorescence emitting layer and a reflection layer uniform in thickness by pressurization alone when the fluorescence emitting layer and reflection layer of the surface light source device of a liquid crystal display, a cathode-ray tube, and a plasma display panel, a light emitting device, and a coating for forming the functional layer of the transfer film. <P>SOLUTION: The transfer film 1 comprises a film 2 in which a peeling layer 3 is formed on the upper surface 2a, a functional layer 4, and a film 5 for protecting the functional layer 4 in which a peeling layer 6 is formed on the upper layer 5a. The functional layer 4 contains an adhesive organic polymer 11 and functional particles 12 made of particles containing metal oxide particles reflecting ultraviolet rays and/or visible light or a phosphor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transfer film, a light-emitting device, and a coating material for forming a functional layer of the transfer film, and more specifically, a transfer film capable of easily and inexpensively forming a functional layer having a uniform thickness, and a functional layer of the transfer film TECHNICAL FIELD The present invention relates to a light emitting device in which a functional layer containing a sticky organic polymer and functional fine particles can be easily and inexpensively formed on a film. .

2. Description of the Related Art Conventionally, a display device using a non-light emitting element such as a liquid crystal as a display unit requires a separate light source for supplying light to the non-light emitting element.
The light source includes a method in which light from a fluorescent lamp provided at an edge of the liquid crystal display unit is reflected by the light guide plate to irradiate the entire liquid crystal display unit, and on the reflection plate on the back side of the liquid crystal display unit. There is a method of arranging a plurality of fluorescent lamps and irradiating light from these fluorescent lamps to the entire liquid crystal display unit through a diffusion plate on the front side, and the latter method is currently mainstream.

In recent years, surface light source devices that emit planar fluorescent light, which is advantageous for increasing the brightness from the point of light utilization, have attracted attention, and attempts to apply this surface light source device to a light source of a non-light emitting element are in progress. (Patent Document 1).
In this surface light source device, a fluorescent layer is formed on the inner wall of a meandering sealed space formed between a pair of opposing glass substrates, a discharge gas is injected into the sealed space, and the discharge gas is generated by plasma discharge. By irradiating the fluorescent light emitting layer with ultraviolet rays, visible light is generated from the excited fluorescent light emitting layer.
In this surface light source device, in order to efficiently use the ultraviolet rays generated to excite the phosphors contained in the fluorescent light emitting layer and the visible light generated by the excited phosphors, the surface light source device has a characteristic of reflecting these lights. A reflective layer made of fine metal oxide particles such as alumina is formed at the bottom of the sealed space.

On the other hand, in a display using a phosphor as a display medium such as a cathode ray tube (CRT), a plasma display panel (PDP), etc., phosphor fine particles are contained by using a coating method such as a spray coating method or a flow coating method. Since the fluorescent light-emitting layer is formed by applying a paint, it is difficult to control the thickness of the fluorescent light-emitting layer, and thus the in-plane luminance of the obtained display device becomes uneven. It was.
Further, the spray coating method and the flow coating method have a problem that the paint cannot be applied efficiently.
Therefore, in order to solve this problem, a transfer film is proposed in which a cushion layer mainly composed of a thermoplastic polymer and a fluorescent light-emitting layer containing a phosphor are laminated on a release film (Patent Document 2). ).
JP 2005-268111 A JP 2001-202884 A

By the way, in the conventional surface light source device, the fluorescent light emitting layer is formed on the inner wall of the sealed space, and the reflective layer is formed on the bottom of the sealed space by using a coating method such as a spray coating method or a flow coating method. It is difficult to control the thicknesses of the light emitting layer and the reflective layer, and therefore there is a problem that the in-plane luminance of the obtained surface light source device becomes non-uniform.
In addition, the spray coating method and the flow coating method have a problem that a coating containing phosphor fine particles or a coating containing reflective metal oxide fine particles cannot be efficiently applied.

On the other hand, with the conventional transfer film, it is necessary to heat and press the transfer film to soften the thermoplastic polymer when transferring the transfer film to the display surface of the display. Since the thickness of the glass substrate used for the surface is also becoming thinner, there is a problem that the thin glass substrate may break due to thermal shock during heating and pressurization.
This is because the temperature difference between the temperature of the overheated transfer roll used for heating and pressurization and the ambient temperature including the glass substrate becomes large. Therefore, as a countermeasure, a step of heating the glass substrate in advance is necessary.

  The present invention has been made to solve the above-described problems, and transfers a surface light source device of a liquid crystal display (LCD), a fluorescent light emitting layer or a reflective layer of a cathode ray tube (CRT) or a plasma display panel (PDP). Provided a transfer film and a light emitting device capable of forming a fluorescent light emitting layer and a reflective layer having a uniform thickness only by applying pressure without heating when forming with a film, and a coating material for forming a functional layer of the transfer film The purpose is to do.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that on the film, there are functionalities such as an organic polymer having adhesiveness, phosphor fine particles and reflective metal oxide fine particles. If a functional layer containing fine particles is formed, a fluorescent light emitting layer and a reflective layer can be formed only by pressing without heating, and the thickness of the obtained fluorescent light emitting layer and reflective layer is uniform and in-plane uniform. As a result, the present invention has been completed.

  That is, the transfer film of the present invention is characterized in that a functional layer containing an adhesive organic polymer and functional fine particles is formed on the film.

The functional fine particles are preferably metal oxide fine particles that reflect one or more of ultraviolet light and visible light, and the functional layer is preferably a reflective layer.
The functional fine particles are preferably fine particles containing a phosphor, and the functional layer is preferably a fluorescent light emitting layer.
It is preferable that a release layer for peeling the functional layer is formed on the film.

  The light emitting device of the present invention is characterized in that the functional layer of the transfer film of the present invention is transferred to the light emitting surface.

  The transfer layer-forming coating material of the transfer film of the present invention is a coating material for forming a functional layer containing an adhesive organic polymer and functional fine particles on the film. And functional fine particles are dispersed in a solvent.

The functional fine particles are preferably metal oxide fine particles that reflect at least one of ultraviolet light and visible light.
The functional fine particles are preferably phosphor fine particles.

  According to the transfer film of the present invention, since the functional layer containing the adhesive organic polymer and the functional fine particles is formed on the film, the transfer film is used as a light emitting surface of a surface light source device or a cathode ray tube (CRT). The functional layer can be easily transferred to the transferred object such as the light emitting surface and the display surface by a simple process of attaching to the transferred object such as the display surface of the plasma display panel (PDP) and applying pressure and peeling the film. can do. Further, since there is no need to heat at the time of transfer, there is no possibility of damaging the transfer target due to heating.

According to the light emitting device of the present invention, since the functional layer of the transfer film of the present invention is transferred to the light emitting surface, this transfer film is applied to the light emitting surface of the light emitting device, pressed, and peeled off. As a result, the functional layer can be easily transferred to the light emitting surface, and the process for forming the functional layer can be shortened and the manufacturing cost can be reduced.
Further, since there is no need to heat at the time of transfer, there is no possibility of damaging the glass substrate on the light emitting surface due to the heating.

  According to the coating material for forming a functional layer of the transfer film of the present invention, since the organic polymer having adhesiveness and the functional fine particles are dispersed in a solvent, a roll coating method, a die coating method, etc. capable of controlling the thickness, etc. By using this coating method, it is possible to easily and inexpensively form a functional layer containing an organic polymer having a uniform adhesiveness and functional fine particles on the film.

The best mode for carrying out the transfer film and the light emitting device of the present invention and the coating material for forming a functional layer of the transfer film will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

"Transfer film"
FIG. 1 is a cross-sectional view showing a transfer film according to an embodiment of the present invention, in which 1 is a transfer film, a film 2 having a release layer 3 formed on an upper surface (surface) 2a, and a functional layer 4 And a film 5 for protecting the functional layer 4 with the release layer 6 formed on the upper surface (surface) 5a.

The film 2 only needs to have a function as a support for supporting the functional layer 4. For example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC ) And the like are preferably used, and a polyethylene terephthalate (PET) film is particularly preferable in terms of excellent mechanical strength and thermal stability.
The thickness of the film 2 should just be sufficient thickness to exhibit the function as a support body which supports the functional layer 4, 10 micrometers-200 micrometers are preferable, More preferably, they are 20 micrometers-50 micrometers.

  The release layer 3 is preferably one that adheres onto the film 2 and adheres to the functional layer 4 by an adhesive force and easily peels off from the functional layer 4 while being adhered to the film 2 during transfer. Resins, urethane resins, melamine resins, copolymers thereof, or mixtures thereof are preferably used.

The functional layer 4 includes an organic polymer 11 having adhesive properties and functional fine particles 12.
As the organic polymer 11 having adhesiveness, the transfer film is applied to a transfer object such as a light emitting surface of a surface light source device or a display surface of a cathode ray tube (CRT) or a plasma display panel (PDP) and pressed. In addition, any material can be used as long as it cannot be easily peeled off by being attached to a transfer object. For example, acrylic resin, acrylic ester resin, vinyl acetate resin, acrylic acid-vinyl acetate copolymer, acrylic ester-vinyl acetate Examples thereof include a polymer, an ethylene-vinyl acetate copolymer, and a styrene-acrylic acid ester copolymer.

The functional fine particles 12 are for imparting a reflection function, a fluorescence emission function, and the like to the functional layer 4 and are composed of a single type or a plurality of types of functional fine particles. In FIG. 1, for convenience, a case in which two types of functional fine particles 12 a and 12 b are used is shown.
When the functional layer 4 is a reflective layer, the functional fine particles 12 are preferably metal oxide fine particles that reflect one or more of ultraviolet rays and visible rays. For example, aluminum oxide, titanium oxide, yttrium oxide, zinc oxide And zirconium oxide.
These metal oxide fine particles may be either a single type or a plurality of types, and the average particle diameter thereof may be not only one type, but also a plurality of types may be combined.

  When the functional layer 4 is a fluorescent light emitting layer, fine particles containing a phosphor are preferable. The fine particles containing the phosphor are preferably fine particles containing a phosphor made of one or more of red, green, and blue phosphor materials. The fine particles containing the phosphor preferably have an average particle size of 0.5 μm to 20 μm, preferably 2 μm to 6 μm.

Here, as the red phosphor material, for example, Y ₂ O ₃ : Eu, Y (PV) O ₄ : Eu, YVO ₄ : Eu, Y ₂ O ₂ S: Eu, (Y, Gd) BO ₃ : Eu etc. are mentioned.
Examples of the green phosphor material include (Ba, Eu) (Mg, Mn) Al ₁₀ O ₁₇ , LaPO ₄ : Ce, Tb, Zn ₂ SiO ₄ : Mn, ZnS: Cu, Al, CeMgAi ₁₁ O. ₁₉ : Tb, GdMgB ₅ O ₁₀ : Ce, Tb, and the like.
Examples of the blue phosphor material include (Sr, Ca, Ba, Mg) ₅ (PO ₄ ) ₃ Cl: Eu, (Ba, Sr, Eu) (Mg, Mn) Al ₁₀ O ₇ , Sr _10. (PO ₄ ) ₆ Cl ₂ : Eu, ZnS: Ag, Al, BaMgAl ₁₀ O ₁₇ : Eu, and the like.
The content of each of the red phosphor material, the green phosphor material, and the blue phosphor material may be appropriately set in accordance with the light emission characteristics of the target fluorescent lamp.

The fine particles containing the phosphor are preferably surface-treated with a surface treatment substance in order to reduce damage caused by ultraviolet rays.
This surface treatment material needs to absorb or reflect ultraviolet rays moderately, thereby reducing phosphor damage caused by the ultraviolet rays and not significantly affecting the emission of the phosphor. Inorganic compounds containing one or more selected from the group of yttrium, aluminum, zirconium, titanium, cerium, zinc, hafnium, niobium, silicon, and vanadium, or phosphor fine particles are preferable.

Examples of the inorganic compound include yttrium oxide, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, zinc oxide, hafnium oxide, niobium oxide, silicon dioxide, vanadium oxide, and the like.
Examples of the phosphor fine particles include calcium halophosphate.
Among these surface treatment substances, aluminum oxide, yttrium oxide, zinc oxide, cerium oxide and the like are particularly excellent in that the phosphor is less damaged by ultraviolet rays and does not significantly affect the light emission of the phosphor.

The film 5 may be any film as long as it has sufficient mechanical strength to protect the functional layer 4 and is preferably the same as the film 2 described above. In particular, a polyethylene terephthalate (PET) film is preferable because it is excellent in mechanical strength and thermal stability.
The release layer 6 is preferably in close contact with the functional layer 4 while being in close contact with the film 5, and is easily peeled off from the functional layer 4 while being in close contact with the film 5 during transfer. The same as 3 is preferred.

The thickness of the film 5 should just be sufficient thickness to have the mechanical strength for protecting the functional layer 4, and 10 micrometers-200 micrometers are preferable, More preferably, they are 20 micrometers-50 micrometers.
In addition, when the convenience at the time of sticking the functional layer 4 is considered, it is preferable that the film 2 with the peeling layer 3 and the film 5 with the peeling layer 6 are the same.

Next, the manufacturing method of the transfer film of this embodiment is demonstrated based on FIG.
First, as shown in FIG. 2A, a release layer 3 made of a silicon resin, a urethane resin, a melamine resin, a copolymer thereof, or a mixture thereof is formed on the upper surface 2a of the film 2.

Separately from this, an organic polymer having adhesive properties and functional fine particles are dispersed in a solvent to produce a functional layer forming coating material for forming the functional layer 4.
Examples of the adhesive organic polymer include acrylic resin, acrylic ester resin, vinyl acetate resin, acrylic acid-vinyl acetate copolymer, acrylic ester-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, Examples thereof include styrene-acrylic acid ester copolymers, and precursors thereof.
The functional fine particles may be appropriately selected from the above-described metal oxide fine particles and fine particles containing a phosphor depending on the purpose of the functional layer 4.

The solvent used in the functional layer-forming coating material is basically an organic solvent, but other organic polymers such as polymer monomers and oligomers alone or a mixture thereof are also preferably used.
In addition to the above, the coating material may contain an organic polymer such as a resin, a low-melting glass such as zinc borosilicate glass, a dispersant, and the like, depending on applications and specifications.

  Examples of the organic solvent include methanol, ethanol, 2-propanol, butanol, diacetone alcohol, furfuryl alcohol, alcohols such as ethylene glycol and hexylene glycol, methyl acetate, ethyl acetate, and n-butyl acetate. Esters, diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, acetone, methyl ethyl ketone , One or more of ketones such as acetylacetone and acetoacetate, aromatic hydrocarbons such as toluene and xylene Can be used, in particular, 2-propanol acetate -n- butyl, toluene, methyl ethyl ketone are preferred.

Next, as shown in FIG. 2 (b), this functional layer forming coating is applied onto the release layer 3 to form a coating film 21.
As a coating method, a method capable of forming a coating film having a uniform thickness is preferable, and a roll coating method, a die coating method, a bar coating method, or the like can be used. In particular, when the in-plane uniformity of the thickness is required as in the light emitting surface of the surface light emitting device, a roll coating method, a die coating method, or the like is preferable.
In application, it is preferable to set the application amount so that the film thickness of the formed application film is 1 μm to 100 μm, preferably 10 μm to 60 μm.

Next, the coating film 21 is dried in the atmosphere.
The drying temperature may be a temperature at which the adhesive organic polymer 11 contained in the paint does not change in quality and the temperature at which the solvent is sufficiently dissipated, for example, normal temperature (25 ° C.) to 100 ° C.
In this drying step, the coating film may be sufficiently dried, and air may be blown. Specifically, warm air may be blown by air blow at normal temperature.

Next, the coating film 21 is dried in the atmosphere to form the functional layer 4 including the organic polymer 11 having adhesive properties and the functional fine particles 12.
As shown in FIG. 2 (c), the release layer 6 of the film 5 is overlaid on the functional layer 4 thus obtained, and pressed with a predetermined pressure P from the outside of the film 5 to release the film 5. The layer 6 is adhered to the functional layer 4.
By the above, the transfer film of this embodiment can be produced.

FIG. 3 is a cross-sectional view showing a light emitting surface of a flat panel surface light emitting device applied to a liquid crystal display (LCD) according to an embodiment of the present invention. A reflective layer 32 is formed on the light emitting surface 31 a of the glass substrate 31. Has been. FIG. 3 shows a case where the reflective layer 32 is composed of two types of functional fine particles 12a and 12b.
In order to form this reflective layer 32, as shown in FIG. 4, using the transfer film 1 in which the functional fine particles 12 of the functional layer 4 are metal oxide fine particles that reflect one or more of ultraviolet rays and visible rays. The surface of the functional layer 4 exposed by peeling off the film 5 of the transfer film 1 is superimposed on the light emitting surface 31a of the glass substrate 31 and pressed with a predetermined pressure P from the outside of the film 2 to The light emitting surface 31a is closely attached.
Next, the film 2 is peeled, and the exposed functional layer 4 is baked at a temperature equal to or higher than the temperature at which the adhesive organic polymer 11 is thermally decomposed to dissipate the adhesive organic polymer 11. . Thereby, in the functional layer 4, the organic polymer 11 having adhesiveness is dissipated, and only the functional fine particles 12 composed of the metal oxide fine particles remain, and the reflective layer 32 shown in FIG. 3 is formed.

If the light emitting surface 31a is a display surface of a cathode ray tube (CRT) or a plasma display panel (PDP), one of ultraviolet light and visible light is displayed on the display surface of the cathode ray tube (CRT) or plasma display panel (PDP). A reflective layer that reflects more than seeds can be formed.
Further, if the functional fine particles 12 a and 12 b of the functional layer 4 are fine particles containing a phosphor, a fluorescent light emitting layer can be formed on the surface of the glass substrate 31 by the same method as that of the reflective layer 32.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.
"Example"
(Preparation of reflective layer coating)
Nitrocellulose is used as a dispersant, an acrylic ester adhesive is used as an adhesive organic polymer, and alumina fine particles having a reflective function are used as functional fine particles. The alumina fine particles are used in a solvent using nitrocellulose. The resulting alumina fine particle dispersion and the acrylic ester pressure-sensitive adhesive were mixed so that the solid content volume ratio was alumina fine particles: acrylic acid ester = 1: 2, to prepare a coating material for forming a reflective layer. .

(Formation of reflective layer)
Next, this reflective layer-forming coating material was applied onto a film on which a release layer had been previously formed to form a reflective layer made of an organic polymer and alumina fine particles.
Next, this reflective layer was transferred onto a glass substrate by pressurization and the film was peeled off, and then baked for 30 minutes at 500 ° C., which is a temperature equal to or higher than the thermal decomposition temperature of nitrocellulose and an acrylic ester adhesive. A reflective layer made of alumina fine particles was formed on the substrate.

"Comparative example"
(Preparation of reflective layer coating)
Nitrocellulose was used as a dispersant, and alumina fine particles having a reflection function as functional fine particles. The alumina fine particles were dispersed in a solvent using nitrocellulose to prepare a coating material for forming a reflective layer.

  Next, the coating material for forming the reflective layer is sprayed onto the glass substrate by a spray coating method and baked for 30 minutes at 500 ° C., which is equal to or higher than the thermal decomposition temperature of nitrocellulose. Formed.

"Evaluation of in-plane uniformity of thickness of reflective layer"
The film thicknesses of the reflective layers of the examples and comparative examples were measured at 9 points in a lattice shape, and the film thickness at each point was quantified based on the film thickness at the center point with the film thickness at the center point being 100.
Table 1 shows the film thickness distribution of the reflective layer of the example, and Table 2 shows the film thickness distribution of the reflective layer of the comparative example.

  From Table 1, the standard deviation (σ) of the film thickness distribution of the reflective layer of the example was found to be 3. On the other hand, when the standard deviation (σ) of the film thickness distribution of the reflective layer of the comparative example was obtained from Table 2, it was 12. Therefore, it turned out that the reflective layer of an Example is excellent in the in-plane uniformity of film thickness compared with the reflective layer of a comparative example.

It is sectional drawing which shows the transfer film of one Embodiment of this invention. It is process drawing which shows the manufacturing method of the transfer film of one Embodiment of this invention. It is sectional drawing which shows the light emission surface of the flat panel-shaped surface light-emitting device of one Embodiment of this invention. It is explanatory drawing for demonstrating the fluorescence light emitting layer formation process of the flat panel-shaped surface emitting device of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transfer film 2 Film 2a Upper surface 3 Release layer 4 Functional layer 5 Film 5a Upper surface 6 Release layer 11 Adhesive organic polymer 12, 12a, 12b Functional fine particle 21 Coating layer 31 Glass substrate 31a Light emitting surface 32 Reflective layer

Claims (8)

  A transfer film comprising a functional layer containing an adhesive organic polymer and functional fine particles on a film.   The transfer film according to claim 1, wherein the functional fine particles are metal oxide fine particles that reflect one or more of ultraviolet rays and visible rays, and the functional layer is a reflective layer.   The transfer film according to claim 1, wherein the functional fine particles are fine particles containing a phosphor, and the functional layer is a fluorescent light emitting layer.   The transfer film according to claim 1, wherein a release layer for peeling the functional layer is formed on the film.   A light-emitting device, wherein the functional layer of the transfer film according to claim 1 is transferred to a light-emitting surface. A paint for forming a functional layer containing an adhesive organic polymer and functional fine particles on a film,
A coating material for forming a functional layer of a transfer film, comprising an organic polymer having adhesive properties and functional fine particles dispersed in a solvent.   The coating material for forming a functional layer of a transfer film according to claim 6, wherein the functional fine particles are metal oxide fine particles that reflect one or more of ultraviolet rays and visible rays.   The coating material for forming a functional layer of a transfer film according to claim 6, wherein the functional fine particles are phosphor fine particles.

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