JPH0136775B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention is a light control sheet used for optically anisotropic (light can only be seen from one direction) display cover, etc., which forms parts through which light passes and parts that do not. It concerns the manufacturing method. Conventional technology An optically anisotropic light control sheet has conventionally been produced by alternately forming a transparent resin film that transmits light and a resin film that blocks light by an appropriate method such as heat-fusion lamination, dry lamination, etc. A method of stacking layers and slicing them to a predetermined thickness.
Alternatively, there was a method of exposing and fixing using a photosensitive resin so as to form a light transmitting portion. Problems to be Solved by the Invention However, the former method requires a large number of laminating steps and has the disadvantage that it is difficult to slice to a desired thickness. Moreover, the latter can only be applied to thin films, and it is difficult to obtain the desired sheet thickness. This is caused by light diffraction. Therefore, the present invention was made as a result of intensive research in order to solve the drawbacks of the conventional light control sheet, such as high manufacturing cost and inability to obtain a desired sheet thickness. Means for Solving the Problems The present invention utilizes the coextrusion method, which has become popular in recent years, as a means to solve all the shortcomings of the prior art. A light control sheet can be manufactured by alternately fusing a light-blocking resin layer and a light-transmitting resin in a mold. That is, a step of extruding a resin that blocks light and a resin that transmits light into mutually independent resin channels, and a comb-shaped channel in which each resin is branched from each resin channel and has a comb-shaped cross section. In the process leading to this, the comb-shaped channel through which the light-blocking resin flows and the comb-shaped channel through which the light-transmitting resin flows, the comb-teeth portions mesh with each other, and the comb-shaped channel is extruded in a layered form from the meshed end surfaces. It is characterized by going through a step of converging and integrating the resin. Function The present invention utilizes the property of high viscosity laminar flow of resin, and adjusts the thickness of the resin extruded in a layered manner from the end surface where the comb tooth portions of each comb-shaped flow path are engaged, and the subsequent Depending on the degree of convergence, a light control sheet in which light transmitting portions and light blocking portions are formed with appropriate uniform widths is continuously manufactured. EXAMPLE An example of a coextrusion mold for achieving the present invention will be explained with reference to the drawings. FIG. 1 shows a mold 3 forming comb-shaped channels 4, 4'.
FIG. The resin flowing through the resin flow path 1 and the resin flowing through the resin flow path 2 bypass the surface of the mold 3 and finally branch to form narrow comb-shaped flow paths 4 and 4'. FIG. 2 is a left side view of FIG. 1 (viewed from the direction of arrow A in FIG. 1), and shows how the resin flow path 1 is detoured. FIG. 3 is a front view of the mold 5 in which the slit 6 has been formed, and surface E in this figure and surface B in FIG. 1 are in contact with each other. In FIG. 3, the width W and thickness T are determined according to the final sheet size. FIG. 4 is a CD sectional view of FIG. 3, and FIG. 5 is a right side view of FIG. 4, and consists of two left and right molds separated by the FG line. The flow path of the slit 6 in Fig. 3 is such that the flow path is narrowed down to the desired sheet size as shown in Fig. 4.
1 and W1 are determined. FIG. 6 is a perspective view of an apparatus for manufacturing the light control sheet of the present invention. The resin extruded by the extruder 7 and the extruder 7' passes through the connecting pipes 10 and 10' and enters the mold 3, where it branches into the comb-shaped channels 4 and 4' shown in FIG. 1, respectively, and then at the end. After the thickness of each layer is adjusted by the slits in the mold 5, the light control sheet 9 can be manufactured by converging the layers. FIG. 7 is a perspective view of the light control sheet 9 of the present invention, and shows a transparent resin 10 that transmits light.
A resin 11 that blocks light is laminated thereon.
In FIG. 7, sheet width W2 and sheet thickness T2
is determined by W1 in FIG. 5 and T1 in FIG. The above-mentioned mold used in the present invention can be processed by general machining,
It can be manufactured by electrical discharge machining. Further, resins that can be used in the present invention include polycarbonate, polysulfane, polystyrene,
Transparent resins such as polyvinyl chloride, thermoplastic polyester, acrylic resins such as polymethyl methacrylate, and polypropylene containing a nucleating agent. As the light-blocking resin, a resin obtained by mixing and kneading additives such as pigments, dyes, and inorganic fillers with the above resin can be used. The width P of the transparent resin 10 and the width Q of the light blocking resin 11 of the light control sheet of the present invention are as follows:
The size (gap) of the slit 6 and the fourth
This is possible by adjusting W1 of the narrowing down result of the diagram. That is, the final sheet thickness T2 and sheet width W2 are determined by adjusting T and W in FIG. 3 and T1 and W1 in FIG. 4. Of course, we cannot ignore netting due to sheet withdrawals. The size of each part is T≧T1≧T2 and W≧W1
≧W2. Example 1 In Figure 3, W = 500m/m, T = 3m/
m, slit thickness 0.5m/m, number of slits 501,
In Figure 5, T1 = 2.2m/m, W1 = 110m/m
A mold was made, and polyethylene terephthalate (transparent resin) and carbon black were mixed at 3% by weight.
Contains polyethylene terephthalate (light blocking resin)
T2 is 2.0m/m as shown in Figure 7 using
A light control sheet with a W2 of 100 m/m was produced by coextrusion. Table 1 shows the thicknesses of the transparent resin layer and light-blocking resin layer formed on this sheet. Comparative example 1 Polyethylene terephthalate transparent film (thickness 200 μm) and carbon black at a weight ratio of 3
Light blocking films (thickness: 200 μm) made of polyethylene terephthalate containing 1.5% were laminated alternately and a block with a thickness of 50 mm was produced using a hot press, and this was cut in the lamination direction to produce a light control sheet with a thickness of 2 mm. Table 1 shows the thickness of the transparent part and the light-blocking part of the finished sheet. Example 2 In Figure 3, W = 500m/m, T = 2.2m/
m, slit thickness 0.2m/m, number of slits 501,
In Figure 5, T1 = 1.7m/m, W1 = 90m/m
A mold was made, and polymethyl methacrylate (transparent resin) and carbon black were mixed at 2.5% by weight.
T2 = 1.5m/m, W2 = 80m/m using polymethyl methacrylate (light blocking resin) containing
A light control sheet was created. Table 1 shows the thickness of the transparent portion and the light blocking portion formed on this sheet.

[Table] Effects of the Invention The present invention has the following effects compared to conventional methods. (1) The thickness of the transparent resin layer, the light-blocking resin layer, and the sheet size (thickness, width) can be easily changed, and the accuracy of the layer thickness is high. (2) Man-hours for manufacturing can be reduced to 30 to 50% of conventional methods. (3) Can be manufactured continuously.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a mold member used in the present invention;
Fig. 2 is a left side view of Fig. 1, Fig. 3 is a front view of a mold member to be combined with the mold member of Fig. 1, Fig. 4 is a sectional view taken along line CD in Fig. 3, and Fig. 5 The figure is a right side view of FIG. 4, FIG. 6 is a perspective view of a main part showing a state in which a light control sheet is manufactured according to the present invention, and FIG. 7 is a perspective view of a main part of a light control sheet according to the present invention. 1 and 2 are resin channels, 4 and 4' are comb-shaped channels, 6 is a slit, 9 is a light control sheet, and 10
11 is a transparent resin, and 11 is a resin that blocks light.

Claims (1)

[Claims] 1. A step of extruding a light-blocking resin and a light-transmitting resin into mutually independent resin flow channels, and forming a comb-shaped flow channel in which each resin is branched from each resin flow channel and has a comb-shaped cross section. In the process leading to this, the comb-shaped channel through which the light-blocking resin flows and the comb-shaped channel through which the light-transmitting resin flows, the comb-teeth portions mesh with each other, and the comb-shaped channel is extruded in a layered form from the meshed end surfaces. A method for manufacturing a light control sheet, which is characterized by passing through a process of converging and integrating resin.