JP2789195B2 - Manufacturing method of plastic sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses a UV or EB curable resin among plastic sheets having a specific concavo-convex pattern on the surface, such as a Fresnel lens, and heats the molded sheet after molding. The present invention relates to a method for manufacturing a plastic sheet to be processed.

[Conventional technology]

In a conventional Fresnel lens using a UV or EB curable resin, a primer layer is provided to increase the adhesive strength between the substrate and the UV or EB curable resin layer, and a sensitizer or the like is further mixed into the primer. Those manufactured by the method are known.

[Problems to be solved by the invention]

In the above-mentioned conventional Fresnel lens, the adhesive force of the primer itself could be improved, but the decrease in the adhesive force due to the strain generated when the UV or EB curable resin was cured was not improved, In particular, in the case of a large size used for a projection television, there is a problem that the UV or EB curable resin layer is peeled off.

Therefore, the present invention provides UV or EB
It is an object of the present invention to provide a method of manufacturing a plastic sheet that can be used as a Fresnel lens having sufficient strength without causing peeling of a curable resin layer.

[Means for solving the problem]

In order to achieve the above object, a first method for producing a plastic sheet of the present invention is a method for producing a plastic sheet having a Fresnel lens-shaped surface layer on a substrate with a primer layer interposed therebetween. On top, after applying a primer layer, provide a UV or EB curable resin surface layer,
A method for producing a plastic sheet, which comprises subjecting a plastic sheet to molding by irradiating UV or EB, curing, and then peeling from a mold, followed by heat processing.

In order to achieve the above object, a second aspect of the method for producing a plastic sheet of the present invention is the method for producing a plastic sheet according to the first aspect of the present invention, wherein the substrate is polymethyl methacrylate, and the primer layer is vinyl chloride vinyl acetate. A copolymer, wherein the surface layer is a polyurethane-based acrylate.

In order to achieve the above object, a third method of manufacturing a plastic sheet of the present invention is characterized in that, in the first and second methods of manufacturing a plastic sheet of the present invention, the thermal processing temperature is used for a substrate or a surface layer. The temperature is higher than the lower temperature of the glass transition point of the resin, and is lower than the lower temperature of the decomposition temperature of the resin used for the substrate or the surface layer.

A third method of the present invention for producing a plastic sheet for achieving the above object is the first and second methods of the present invention.
And a third method for producing a plastic sheet,
The heat processing is performed on a table having at least one direction convexly or concavely curved.

As the material constituting each layer of the plastic sheet obtained by the production method of the present invention, the following materials are preferable for the reason that the effect of improving the adhesiveness is large and for the reasons described above. As a substrate, polymethyl methacrylate is preferred because it is colorless and has high transmittance of visible light. As the primer layer, a vinyl chloride-vinyl acetate copolymer is preferred because of good adhesion between the surface layer described below and the substrate. For the surface layer that forms the shape of the Fresnel lens, an oligomer or monomer of a polyurethane acrylate was used because UV yellowing after curing was extremely small among UV and EB curable resins.

The thermal processing in the method for producing a plastic sheet of the present invention is at least a temperature higher than the lower temperature of the glass transition point of the resin used for the substrate or the surface layer, and the decomposition temperature of the resin used for the substrate or the surface layer. Is effected by performing at a temperature lower than the lower temperature of
No special equipment is required for the thermal processing equipment as long as the temperature can be kept constant, but it is generally preferable to use a constant temperature chamber. Further, by selecting a polyurethane acrylate having an appropriate glass transition point, it is possible to select conditions that are easy to implement.

When the plastic sheet obtained by the production method of the present invention is used as a projection television screen, it is used in combination with a sheet having a light diffusion effect, for example, a sheet having a lenticular lens as a shape. Alternatively, it is preferable to use a plastic sheet that is convexly or concavely curved in at least one direction out of the lateral direction, because adhesion to other sheets is improved. As a method of bending the plastic sheet, there is a method of performing thermal processing on a table that is convexly or concavely curved in at least one direction, in the longitudinal direction or the lateral direction of the plastic sheet, and according to the manufacturing method of the present invention, The improvement of the adhesive strength of the surface layer made of UV or EB curable resin and the bending of the plastic sheet can be simultaneously and effectively performed by the thermal processing means.

[Action]

Although the stress acting on the surface perpendicular to the film thickness direction of the surface layer caused by the strain due to shrinkage causes the separation of the primer layer and the surface layer, according to the method for producing a plastic sheet of the present invention, the thermal processing means In addition, since the internal strain due to the shrinkage of the resin generated when the surface layer is cured gradually decreases, the adhesive strength between the surface layer and the primer layer is maintained.

〔Example〕

Embodiments will be described with reference to the drawings. FIG. 1 (A) is a cross-sectional view of a plastic sheet showing a first embodiment of the present invention, and FIG. 1 (B) is a process drawing showing a method for manufacturing a plastic sheet.

The substrate 1 is an extruded plate of polymethyl methacrylate to which no UV absorber is added so as to transmit UV, and has a thickness of
3 mm, length 810 mm × width 540 mm was used. The primer layer 2 is a copolymer of vinyl chloride and vinyl acetate, and was formed by thermal transfer to the substrate 1 in advance.

The means for forming the surface layer 3b having the Fresnel lens shape will be described. An urethane-based acrylate oligomer or monomer as a UV or EB curable resin is applied to the mold 4 to form an uncured resin layer (surface layer 3a). Next, an uncured surface layer 3a is formed by placing a sheet in which the primer layer 2 is formed on the substrate 1 in advance on the resin layer. Thereafter, the resin layer (surface layer 3a) is cured by irradiating UV rays so as to transmit through the substrate 1 and the primer layer 2, thereby forming a surface layer 3b (FIG. 1 (B)). After peeling this from the mold to form a plastic sheet, the glass transition point of the acrylic substrate is 110 ° C and the glass transition point of urethane acrylate is 60 ° C. Left for 36 hours.

As a result, the adhesive strength without heat processing was about
250 g / cm compared to about 8
The value was as high as 00 g / cm.

2 and 3 show a second embodiment of the present invention.
FIG. 2 shows a plastic sheet which has the same structure as that of the first embodiment and is curved in the longitudinal direction of the sheet. FIG. 3 shows a method of thermal processing of the plastic sheet. After the plastic sheet was peeled off from the mold, it was placed on a curved thermal processing table 5 at a thermal processing temperature of 70 ° C. and left for 36 hours. Even in the case of a curved shape, the adhesive strength was about 800 g / cm.

〔The invention's effect〕

In the plastic sheet obtained by the manufacturing method of the present invention, since the distortion of the material constituting the plastic sheet is reduced, the adhesive strength of the surface layer can be increased, and the plastic having a stable mechanical shape with high mechanical strength can be obtained. This has the effect of obtaining a sheet.

According to the method for manufacturing a plastic sheet of the present invention, a plastic sheet having high adhesive strength can be easily manufactured.

[Brief description of the drawings]

1 (A) is a cross-sectional view of a plastic sheet showing a first embodiment, FIG. 1 (B) is a process diagram showing a method for manufacturing a plastic sheet, FIGS. 2 and 3 are FIGS. FIG. 2 is a perspective view of a curved plastic sheet, and FIG. 3 is a process chart showing a thermal processing method. 1 ... substrate, 2 ... primer layer, 3 ... surface layer, 4 ... mold, 5 ... curved thermal processing table

Claims (4)

(57) [Claims] 1. A method for producing a plastic sheet having a Fresnel lens-shaped surface layer on a substrate via a primer layer, comprising: applying a primer layer on the substrate; A method for producing a plastic sheet, comprising: providing a surface layer, curing by irradiating UV or EB, and peeling from a mold to form a plastic sheet, followed by thermal processing. 2. The method for producing a plastic sheet according to claim 1, wherein the substrate is polymethyl methacrylate, the primer layer is a vinyl chloride-vinyl acetate copolymer, and the surface layer is a polyurethane acrylate. Of manufacturing plastic sheets. 3. The method for producing a plastic sheet according to claim 1, wherein the thermal processing temperature is higher than the lower temperature of the glass transition point of the resin used for the substrate or the surface layer; And a method for producing a plastic sheet, wherein the temperature is lower than the lower temperature of the decomposition temperature of the resin used for the substrate or the surface layer. 4. The method for producing a plastic sheet according to claim 1, wherein the thermal processing is performed on a table having at least one direction curved in a convex or concave manner. Of manufacturing plastic sheets.