JPH06335939A - Manufacture of face light source panel with optical diffusion layer - Google Patents

Abstract

PURPOSE:To efficiently obtain a face light source panel with an optical diffusion layer on the surface in a reduced processes by a method wherein injection or compression molding is performed in such a way that a molten thermoplastic resin layer is laminated on the optical diffusion layer side of a film and the base resin layer is peeled off from a molded item. CONSTITUTION:An optical diffusion film 1 is fed from a film roll and is placed in such a manner that a base resin layer is brought into contact with a cavity face of a fixed mold 12 and molds 5 and 12 are clamped. Then, the optical diffusion film 1 is pinched and fixed between a film holder 10 and a film fixing channel 14 and the optical diffusion film 1 is extended by feeding heated compressed air into a mold cavity 15 and the film 1 is brought into tight contact with a fixed insert 9 and a heated and molten, e.g. polymethyl methacrylate resin is injected and filled into the cavity 15. Thereafter, when the molten resin is solidified by cooling and the mold is opened, the optical diffusion layer being tightly adhered on the surface of the molded item is transferred with high accuracy and only the base resin layer is peeled off from the front face part of the molded item.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a surface light source panel having a light diffusion layer used in a surface light source device such as a liquid crystal backlight and a display plate.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a surface light source panel having a light diffusing layer, a base resin layer and a light diffusing layer are formed on the surface of a transparent thermoplastic resin panel which is molded in a predetermined shape in advance. A method is known in which a light diffusing film is overlaid and the light diffusing layer is transferred to the panel surface by a method such as a screen printing method or a hot stamping method. But,
These conventional techniques require a step of transferring the light diffusion layer to the surface of the panel as a step different from the step of molding the transparent thermoplastic resin into the shape of the panel in advance,
There is a problem in that the number of steps increases and the processing takes a long time. Moreover, when the light diffusion layer is formed by the screen printing method, defects such as crazing and cracks are likely to occur on the panel surface due to the solvent used during the printing process, and the hot stamping method newly uses a device such as a heater source or a pressure source. However, there is a problem in that, when the light diffusing layer is formed, heating and cracks are likely to occur and pinholes are generated due to dust adhering to the panel surface.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have solved the above problems and efficiently produced a pinhole due to crazing, cracks, dust, etc. on the panel surface without deteriorating the original property and in a small number of steps. As a result of earnest studies to manufacture a surface light source panel having a light diffusion layer without doing so, the present invention has been completed.

[0004]

[Means for Solving the Problems] That is, the present invention provides a light-diffusing film having a light-diffusing layer provided on a base resin layer and a molten transparent thermoplastic resin, the light-diffusing layer side of the film. Light diffusion characterized by being formed by injection molding or compression molding so that a layer made of a molten transparent thermoplastic resin is laminated on, and then peeling the base resin layer from the obtained molded product. A method for manufacturing a surface light source panel having a layer is provided.

The present invention will be described in detail below. The light-diffusing film used in the present invention has a light-diffusing layer provided on a base resin layer, and may be composed of only these two layers. A release layer may be provided to facilitate peeling, and an adhesive layer may be provided on the upper surface of the light diffusion layer to improve the adhesion between the light diffusion layer and the transparent thermoplastic resin during molding. .

The base resin layer of the light-diffusing film serves as a support base for the light-diffusing layer before molding, but is peeled off from the molded product after molding, and is usually a vinyl chloride film or a nylon-based film. Film, polypropylene film,
A polyester film or the like is used, but a polyester film, particularly a biaxially stretched polyester film is preferably used because of its good heat resistance and processability.
The release layer is provided to facilitate separation of the base resin layer from the molded body after molding as described above, and for example, coating the base resin layer with a silicone resin or the like. Can be formed by.

The light-diffusing layer is generally not affected by the high-temperature molten transparent thermoplastic resin supplied at the time of molding, for example, when it is refracted in an ink containing an epoxy resin or an acrylic resin as a vehicle. The composition can be formed by coating the composition containing microspheres such as spherical glass beads having different particle diameters of about 5 to 100 μm on the release layer by means such as coating. Of course, it is possible to form the light diffusion layer directly on the base resin layer without the release layer, but the bond between the base resin layer and the light diffusion layer is not so strong, and the base resin after molding is not so strong. It is necessary to appropriately select the type of the base resin layer, the vehicle component of the light diffusion layer, etc. so that the layer can be easily peeled from the light diffusion layer. The adhesive layer is for improving the adhesiveness between the light diffusion layer and the transparent thermoplastic resin serving as the substrate of the surface light source panel, and when the adhesiveness between the vehicle component and the transparent thermoplastic resin is good. There is no need to provide it.

The resin material of the surface light source panel is not particularly limited as long as it is a plastic material that is transparent and can be used in the surface light source device. For example, various acrylic resins represented by polymethylmethacrylate resin are used. Examples of the resin include polystyrene resin, polystyrene resin, polycarbonate resin, acrylonitrile-styrene resin, and methylmethacrylate-styrene resin. Among them, acrylic resin is preferable, and polymethylmethacrylate resin is particularly preferable because of its excellent optical characteristics.

In the present invention, conventionally known methods such as injection molding and compression molding can be applied to the integral molding of the light diffusing film and the transparent thermoplastic resin, and the specific molding conditions are particularly limited. Not something. For example, in the case of using an injection molding method, a light diffusing film is previously placed between a pair of molds forming a cavity of a predetermined shape, the molds are closed, and a molten transparent thermoplastic resin is injection-filled therein. In the case of integrally molding by a compression molding method, after placing a light diffusing film between a pair of molds forming a cavity of a predetermined shape, a molten transparent thermoplastic resin is supplied here. Then, the mold is closed, and pressure and compression are performed. The molten resin in these methods may be directly supplied into the cavity from a molten resin supply path provided in the mold, or in the case of compression molding, an appropriate resin supply device from the outside of the mold. It may be a method by external supply using. In any of these methods, it is necessary to supply the molten resin from the light diffusion layer side of the light diffusion film.

In these methods, the method for placing the light diffusing film between the molds is, for example, such that the base resin layer of the light diffusing film is in contact with the cavity surface of one mold. The method and the method of placing it in the middle of the cavity surface between both molds are mentioned. The light diffusing film is previously placed and fixed in the middle of the cavity surface between both molds, and the light diffusing layer side It is desirable to supply heated air from the above to soften the film, and to suction the film from the mold on the base resin layer side by vacuum suction to bring the film into close contact with the mold on the base resin layer side.

[0011]

According to the method of the present invention, a molded article in which the light diffusing film and the molten transparent thermoplastic resin are firmly integrated can be obtained in one step. By peeling off the resin layer, a surface light source panel having a light diffusion layer on the surface of the transparent thermoplastic resin layer can be efficiently obtained in a small number of steps. Moreover, the obtained surface light source panel has excellent properties such as neither crazing nor cracking, and no flaws or warpage.

[0012]

Embodiments of the present invention will be described below with reference to the drawings, but it goes without saying that the present invention is not limited to the embodiments.

Example 1 All of FIGS. 1 to 3 are sectional views of a molding die by an injection molding method. FIG. 1 is a state in which a light diffusing film is closely attached to a fixed die, FIG. Shows the state before the molten resin is supplied with the mold closed, and Fig. 3 shows the base resin layer of the light-diffusing film peeled from the molded product during the mold opening after the molten resin has been supplied and cooled. The state immediately before is shown.

First, each part of the apparatus will be described. In FIG. 1, reference numeral 1 is a light diffusing film, and a roll 2
The base resin layer is placed so as to be in contact with the cavity surface of the fixed mold via the guide roller 3a and the guide roller 3a. After the molding transfer, the base resin layer of the light diffusing film 1 is peeled off as the mold is opened, and the light diffusing film 1 is wound up via the guide roller 3b and collected by the roll 4. The mold clamping is performed by moving the movable mold 5 forward (leftward in the drawing), and the mold opening is performed by retracting the movable mold 5 (rightward in the drawing). The fixed die 12 is fixed to a fixed platen 13. The movable die 5 is connected to the movable plate 6,
It moves forward and backward together with the movable plate 6. The movable type 5 is
The structure has a runner and a gate as a supply path for supplying the molten resin into the mold cavity. When the molded product is taken out, the movable rod 7 is pushed out by the continuous rod 8, and the molded product is pushed out accordingly and taken out. When the mold is clamped,
As shown in FIG. 2, the movable insert piece 7 constitutes the cavity 15 together with the fixed insert piece 9. 10 is a film holder,
It has a structure capable of expanding and contracting by a spring 11 incorporated in the movable mold 5, and has a function of fixing the light diffusing film 1 by fitting the film fixing groove 14 and the film holder 10 together.

Next, a method of forming the surface light source panel will be described. In FIG. 1, the light-diffusing film 1 is supplied from the film roll 2 through the guide roller 3a, and the fixed mold 1
The base resin layer is placed in contact with the cavity surface of No. 2. The composition of the light diffusing film 1 used is a biaxially stretched polyester base film (trade name: Lumirror, manufactured by Toray) coated with a silicone resin as a release layer, and a polyester resin as a light diffusing agent layer thereon. White ink (Nagose Screen Printing Laboratory, trade name; Fujiron) containing spherical glass beads with different refractive index and particle size of 20-40 μm (Nagase Screen Printing Laboratory, trade name; beads) is coated. It has a three-layer structure. The movable platen 6 is moved forward to clamp the mold, and the second
As shown in the figure, the light diffusing film 1 was sandwiched and fixed between the film holder 10 and the film fixing groove 14. Heated compressed air of 150 ° C. and 4 kg / cm ² is supplied to the mold cavity portion from the supply path of the molten resin to extend the light diffusing film 1, and from the suction port provided on the fixed insertion piece 9 side. The film 1 by suction
Was closely attached to the fixed insert piece 9. After that, the polymethylmethacrylate resin heated and melted at 230 ° C. was injected and filled into the cavity from an injection machine through a gate and a runner (not shown).

When the molten resin is cooled and solidified, the movable plate 6
Was retracted and the mold was opened. As shown in FIG. 3, the molded product 16 is in close contact with the movable insert piece 7, while the light diffusing film 1 is fixed by the film holder 10 and the film fixing groove 14, The portion of the light diffusion layer that was in close contact with the surface of the molded product is transferred to the surface of the molded product with high accuracy, and only the base resin layer is peeled off from the front surface of the molded product. When the mold opening is completed,
By pushing out the movable insert piece 7, the molded product 16 was pushed out from the mold and taken out. The thus-obtained molded product 16 is an edge light type surface light source panel for liquid crystal backlight, the size of which is a flat plate having a length of 130 mm and a width of 240 mm, a wall thickness of 5 mm, and a performance of a conventional screen. The brightness was comparable to that produced by the printing method, and information such as characters could be displayed clearly. In addition, neither crazing nor cracks were observed on the panel surface, and no flaws or warpage were observed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a molding die, which is an explanatory view of a state in which the die is opened.

FIG. 2 is a cross-sectional view of a molding die, which is an explanatory view of a state in which the die is closed.

FIG. 3 is a cross-sectional view of a molding die, which is an explanatory view of a state immediately before peeling a base resin layer of a light diffusing film from a molded article during opening of the die.

[Explanation of symbols]

 1 ... Light-diffusing film 2, 4 ... Rolls 3a, 3b ... Guide rollers 5 ... Movable type 6 ... Movable plate 6 7 ... Movable insert 7 8 ... Continuous rod 9 ... Fixed insert piece 10 ... Film holder 11 ... Spring 12 ... Fixed type 13 ... Fixed plate 14 ... Film fixing groove 15 ... Cavity 16 ... Molded product

Claims (4)

[Claims] 1. A light-diffusing film having a light-diffusing layer provided on a base resin layer and a molten transparent thermoplastic resin, wherein the light-diffusing layer side of the film is made of a molten transparent thermoplastic resin. A method for producing a surface light source panel having a light diffusing layer, comprising molding by injection molding or compression molding so that the layers are laminated, and then peeling the base resin layer from the obtained molded product. 2. The light diffusing film is a film comprising a release layer provided between a base resin layer and a light diffusing layer.
A method for manufacturing a surface light source panel having the light diffusion layer as described above. 3. The method for manufacturing a surface light source panel having a light diffusion layer according to claim 1, wherein the thermoplastic resin is an acrylic resin. 4. The method for manufacturing a surface light source panel having a light diffusion layer according to claim 3, wherein the acrylic resin is polymethylmethacrylate resin.