JPH0147310B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a diffusion plate in which a transparent acrylic film is integrally adhered to an acrylic resin plate containing a diffusing agent. The purpose of this invention is to efficiently produce an acrylic resin diffusion plate that has good adhesion to an acrylic film and has excellent resolution and light diffusivity.

So-called screens that clearly view images projected from the rear are also used for screens such as large televisions, as well as for microfilm readers, reader printer screens, and camera focusing glasses. Diffusion plates used as screens or other lighting equipment are made by mixing a light diffusing agent such as titanium oxide or silica and a coloring agent with an appropriate binder, and applying this liquid to a transparent substrate such as acrylic resin. death,
It is generally manufactured by drying, solidifying, and forming a light-diffusing layer on one side. However, in screens manufactured using this method, the light diffusion layer is exposed on the outer surface, so there is a risk of staining or peeling off. Since it includes the step of applying a liquid material containing a diffusing agent, it requires complicated efforts such as adjusting the amount of application and adjusting the thickness of the coating film, and has the drawback of low production efficiency and high cost.

In order to improve this point, the applicant has already proposed a diffusion plate in which an acrylic film mixed with a light diffusing agent is integrated with an acrylic resin plate. The idea was to form the light diffusion layer from acrylic film and make this layer as thin as possible. However, when producing an acrylic film mixed with a light diffusing agent made of inorganic particles as described above, it is difficult to obtain a film with no spots in which the light diffusing agent is uniformly dispersed, and moreover, it is difficult to obtain a film with no spots in which the light diffusing agent is uniformly dispersed. There was also the risk of contaminating other materials, making it difficult to put it into practical use. Furthermore, in order to integrate the acrylic film and the acrylic resin board, since the film is partially swollen and/or dissolved by the acrylic monomer or its partial polymer before curing, it is difficult to integrate the acrylic film and the acrylic resin plate after curing. However, the thickness of the acrylic film tended to be large. Furthermore, the film mixed with a light diffusing agent is
Not only is it generally hard and inconvenient to handle,
Since its surface was rough, there was a risk of damaging the surface of the mold to which it was fixed during casting polymerization.

The present invention was developed in view of the above circumstances, and its gist is that after a transparent acrylic film is pasted on the inner surface of at least one of the molds, the mold and gasket are used to perform casting polymerization. An acrylic resin diffusion method characterized by forming a cell for use in the acrylic resin diffusion process, then injecting an acrylic resin monomer or a partial polymer thereof containing a light diffusing agent into the cell, and polymerizing and curing the monomer or a partial polymer thereof. It's in the manufacturing method of the board.

The present invention will be described below with reference to drawings of embodiments.

The present invention aims to produce a diffuser plate in which a transparent acrylic film is laminated on at least one side of an acrylic resin plate containing a light diffusing agent, and FIG. 1 shows the diffuser plate obtained by the present invention. This is a typical example. That is, a transparent acrylic film 2 is laminated on one side of an acrylic resin plate 1 containing a light diffusing agent. The diffusion plate obtained by the present invention is not one in which the acrylic film 2 is bonded with an adhesive or the like, but is made by using an acrylic monomer or a partial polymer thereof before polymerization and hardening of the acrylic resin plate 1 serving as the base material. Then, the transparent acrylic film 2 is partially swollen and/or dissolved, and when both are polymerized and hardened, they are tightly integrated. Figure 1 shows an example in which both surfaces are finished with a smooth mirror surface, but in the present invention, one of the surfaces is a matte surface, a hairline surface, a lenticular surface, or a Fresnel surface. A diffuser plate can also be obtained. FIG. 2 shows an example in which a transparent acrylic film 2 is formed with a lenticular surface A, and FIG. 3 is a manufactured example in which a Fresnel surface B is similarly formed. When the lenticular surface A and the Fresnel surface B are formed on the transparent acrylic film 2 in this way, since this film 2 does not contain a light diffusing agent, it will not affect the diffusion layer and its shape will be precise. It will be shaped into Note that FIG. 4 shows an example in which transparent acrylic films 2 are laminated on both sides. In either case, the transparent acrylic film 2 is partially swollen and/or dissolved by the acrylic monomer or its partial polymer before curing, so its thickness increases and it becomes relatively diffused. The layers can be made thinner, thus increasing the resolution of the diffuser plate and providing a diffuser plate with uniform diffusivity. Note that the transparent acrylic film 2 may be colorless and transparent, but in order to adjust the color tone of the diffuser plate and provide contrast when used as a screen, this film may be colored with an appropriate dye or the like. , preferably colored and transparent. Coloring in this way is advantageous because the reflectance on that surface can be reduced without significantly reducing the amount of transmitted light.

In the present invention, the acrylic resin monomer or partial polymer thereof that forms the acrylic resin plate 1 serving as the base material contains a light diffusing agent. , clay, alumina white, and calcium carbonate, each singly or as a mixture of two or more thereof, can be used. Among these, silica is most suitable in combination with acrylic resin due to its refractive index and other properties. The average particle size of these light diffusing agents is 0.5~
It is about 100 μ and the content is about 10 to 100 g/m ² .

The monomer or partial polymer forming the acrylic resin 1 of the present invention is a mixture of 90% by weight or more of methyl methacrylate and other copolymerizable monoethylenically unsaturated compounds and/or polyfunctional compounds, or a portion thereof. Polymers may be mentioned. Examples of the monoethylenically unsaturated compound include methacrylic esters, acrylic esters, and styrene. Examples of the polyfunctional compound include methacrylic acid esters such as glycol dimethacrylate and diallyl methacrylate, diallyl phthalate, diethylene glycol bisallyl carbonate, and mixtures thereof.

Further, as the transparent acrylic film 2, a film manufactured from a polymer whose main component is an alkyl methacrylate such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, or propyl methacrylate is used, and the thickness thereof should be approximately 100μ or more. Often, relatively thick materials, sometimes referred to as sheets, can also be used.

Next, regarding the manufacturing method of the present invention, an example in which a face plate is used as a mold will be described with reference to FIGS. 5 and 6. Figure 5 shows the state in which the cell S is assembled and polymerized and hardened. Reference numerals 3 and 3' are a pair of molds made of tempered glass face plates, etc., and the inner surface of one of the molds 3' is preliminarily coated with transparent acrylic. A series film 2 is attached. Note that 4 is a gasket and 5 is a tightening tool. Into the cell S assembled in this manner, a liquid material generally called syrup, which is made of an acrylic resin containing a light diffusing agent and is not yet cured, is injected. After injection, the cell S is polymerized and hardened by staying in a water bath or air bath in an atmosphere of several tens of degrees Celsius for several hours, and then in an atmosphere of 100 degrees Celsius or more for several tens of minutes. The acrylic resin diffusion plate taken out from the cell S has a cross section approximately as shown in FIG. 1, and is made up of an acrylic resin plate 1 and a transparent acrylic film 2 that are closely integrated. FIG. 6 shows a method of pasting a transparent acrylic film 2 onto a mold in advance, and the mold 3 is supported by a group of feed rolls 7 so as to be movable. First, a thin layer of adhesive is applied to the surface of the mold 3 using the adhesive application device 6. Next, this mold 3 is moved and a transparent acrylic film 2 supplied from a film joining device 8 is joined and pasted. The mold 3' to which the transparent acrylic film 2 is continuously attached is
The excess film is cut off, and a mold 3' as shown in FIG. 5 is prepared. The adhesive used in this method is usually the aforementioned acrylic resin syrup. When forming a lenticular surface, a Fresnel surface, a matte surface, or a hair line surface as shown in FIG. There is no problem in forming the diffuser plate by heat press processing or other post-processing, but if the inner surface of the mold to which the transparent acrylic film is attached is a lenticular surface, Fresnel surface, matte surface, or hairline surface. By using such an acrylic resin diffusion plate, it is possible to obtain an acrylic resin diffusion plate that is shaped in this manner simultaneously with casting polymerization. Shaping the surface of the transparent acrylic film 2 in this manner is particularly preferable since it does not affect the diffusion layer in any way as described above.

FIG. 7 shows another example of the manufacturing method of the present invention, and shows an embodiment using a mold made up of endless belts running opposite each other. In this manufacturing method, a continuous casting polymerization device 9 is used, and a transparent acrylic film 2 is attached to an upper belt 3', which is one of the molds. 9
2, and gaskets 4 are continuously supplied from both sides of the inlet, thereby forming a type of cell. In this device 9, an adhesive applicator 6 and a film bonding device 8 are provided on the upper belt 3'. This adhesive application device 6 is
As shown in FIG. 8, an adhesive 62 is stored in a storage tank 61, and a tongue piece 63 partially immersed in the storage tank 61 comes into contact with the upper belt 3'. Also, a film bonding device 8 as shown in FIG. 9 is installed almost adjacent to this coating device 6, and this device 8 has a main roller 81 that wraps a transparent acrylic film 2. The transparent acrylic film 2 is supplied to a pressure roller 83 via a group of rollers 81 on which an adhesive such as acrylic resin syrup is thinly applied by the coating device 6. It is designed to be connected continuously. The cell constituted by the upper belt 3' to which the transparent acrylic film 2 is attached as described above and the other lower belt 3 is filled with acrylic resin from the metering pump 91 via the injector 93. The syrup is continuously fed and passes through the first polymerization zone 95 and then through the second polymerization zone 96 to complete the polymerization. Subsequently, the resin passes through the first cooling zone 97 and the second cooling zone 98, and the upper and lower belts 3' and 3 are separated when the resin temperature has dropped to an appropriate level, and an acrylic resin diffusion plate having a cross section as shown in FIG. Manufactured continuously. The acrylic resin diffusion plate obtained by this method is also a good one, in which the transparent acrylic film 2 is closely integrated with the acrylic resin plate 1 containing the light diffusing agent, as in the case shown in Fig. 5. It was hot.

Specific examples will be described below.

Example 1 Methyl methacrylate monomer is prepolymerized to contain about 20% by weight of methyl methacrylate polymer.
A methyl methacrylate partial polymer (hereinafter referred to as syrup) having a viscosity of about 10 poise at 25°C was produced. This syrup contains 650 ppm of azobisdimethylvaleronitrile as a polymerization catalyst, 30 ppm of dioctyl sulfosuccinate as a release agent, and 2.5% by weight of silica particles with an average particle size of 4 μ as a light diffusing agent.
and mixed them. This amount of addition corresponds to about 65 g/m ² for the acrylic resin board.

On the other hand, the molds were made of tempered glass with a thickness of 100 mm, a width of 1.420 mm, and a length of 1.164 mm, with one side having a smooth mirror surface and the other side having a matte finish.
First, a transparent acrylic film was attached to the matte surface of tempered glass that had been matte treated, as shown in Figure 6. Acrylic film contains 64% by weight of methyl methacrylate and 36% by weight of butyl acrylate.
Using a 100μ thick copolymer with
When joining the films, the distance between the tempered glass molds was approximately 150 mm, and the moving speed was 0.5 m/min. When pasting, methyl methacrylate with a polymerization rate of 3% and a viscosity of 10 centipoise was used as a kind of adhesive and was applied in advance.

A pair of molds, one with the film attached and one without the film attached, are used as a pair, a hollow gasket made of vinyl chloride is clamped around them, and a cell is assembled as shown in Figure 5. The above syrup was injected into the mold, and the mold was adjusted and tightened so that the thickness of the mold was 2 mm. Then this cell
The mixture was heated at 60°C for 6 hours and then at 120°C for 2 hours to polymerize and harden. When the resin plates are peeled off from both molds after cooling, a good acrylic resin diffusion plate is obtained in which a matte surface is formed on one side, this surface is formed of a transparent acrylic film, and this film is tightly integrated. It was done.

Example 2 This example is an example of continuously manufacturing an acrylic resin diffusion plate using the polymerization apparatus shown in FIG.

The endless belt is made of mirror-polished stainless steel with a thickness of 1.5 mm and a width of 1500 mm, and is suspended under tension between two pairs of upper and lower pulleys, so that it runs at a speed of 3 meters per minute. It's summery. In such an apparatus, the syrup containing the light diffusing agent was the same as that used in Example 1, and was injected in fixed amounts from a syringe using a metering pump.

On the other hand, a transparent acrylic film having the same composition as in Example 1 and having a thickness of 250 μm and lightly colored with carbon black was prepared and set in a film sticking device as shown in FIG. 9. In addition, prior to pasting the film, the adhesive applicator shown in Figure 8 is
A syrup similar to that used in the coating device of Example 1 is stored in a storage tank, and is applied thinly to the surface of the upper belt in advance.

As described above, a transparent acrylic film was attached to the upper belt, and the upper and lower endless belts were adjusted to have a thickness of 2 mm, and polymerization was carried out while running the belts. Note that a hollow pipe made of polyvinyl chloride containing dibutyl phthalate was used as the gasket. Then, in the first polymerization zone, hot water at 84°C is sprayed as a shower, and the syrup is almost polymerized and hardened by this heating, but the transparent acrylic film is cured by the partial polymer or monomer in the syrup at this stage. It partially swells and/or dissolves and comes into close contact with the plate-shaped polymer in this polymerization zone. Then, it is sent to a second polymerization zone, where it is heated from both sides to about 130°C using an infrared heater, etc., to complete the polymerization. The endless belt was further air cooled to approximately 100°C in the first cooling zone and to approximately 80°C in the second cooling zone, and separated from the endless belt. The taken out acrylic resin diffusion plate has a thickness of 2 mm ± 0.2 mm, and as shown in the cross section of Figure 1, the transparent acrylic film and the acrylic resin plate containing the light diffusing agent are closely integrated. It was in good condition.

Since the present invention is constructed as described above, it is possible to efficiently produce a high-performance acrylic resin diffusion plate in which a transparent acrylic film is closely integrated with an acrylic resin plate containing a diffusing agent. It has the advantage of being able to absorb

[Brief explanation of drawings]

FIGS. 1 to 4 are cross-sectional views showing examples of acrylic resin diffusion plates manufactured according to the present invention, and FIG. 5 is a cross-sectional view showing an example of the manufacturing method according to the present invention using a mold made of a face plate. Cross-sectional view showing an example, No. 6
The figure is a side view showing an example of the method of attaching an acrylic film to the mold used in Figure 5, and Figure 7 is a side view showing an example of the method of attaching an acrylic film to the mold used in Figure 5. Figure 7 is a side view showing an example of the method of attaching an acrylic film to the mold used in Figure 5. FIG. 8 is an enlarged sectional view of the pasting syrup applicator shown in FIG. 7, and FIG. 9 is an enlarged side view of the film pasting apparatus shown in FIG. 7. 1...Acrylic resin plate containing a light diffusing agent,
2...Transparent acrylic film, 3,3'...
Mold (endless belt), 4... gasket.

Claims (1)

[Claims] 1. After pasting a transparent acrylic film on the inner surface of at least one of the molds, the mold and gasket form cells for cast polymerization,
A method for producing an acrylic resin diffuser plate, comprising: thereafter injecting an acrylic resin monomer or a partial polymer thereof containing a light diffusing agent into the cells, and polymerizing and curing the monomer. 2. The method for manufacturing an acrylic resin diffusion plate according to claim 1, wherein the mold is composed of a face plate. 3. The acrylic resin according to claim 1, wherein the inner surface of the mold to which the transparent acrylic film is attached has a matte surface, a hairline surface, a lenticular surface, or a Fresnel surface. Method of manufacturing a diffuser plate. 4. The method for manufacturing an acrylic resin diffusion plate according to claim 1, wherein the molds are composed of endless belts running oppositely to each other. 5. Claims 1, 2, and 3, characterized in that the light diffusing agent is composed of silica, talc, clay, alumina white, and calcium carbonate, each singly or in a mixture of two or more. The method for manufacturing an acrylic resin diffusion plate according to item 1 or 4.