JPS5942291B2 - Method of manufacturing screen members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a screen member made of a crystalline polymer.

Conventionally, so-called painted screens have been used as transmission screens, which are made by coating a transparent or semi-transparent substrate with pigments having light diffusing ability, ganas, beads, etc. dispersed in a vehicle. However, there are also screens that have completely different advantages and forms, such as screens that apply the light diffusion effect of crystal particles generated in crystalline polymer materials. -14236 Publication or Special Publication No. 1977-192
This is already known from the description in Publication No. 57.

Generally, polymeric materials are considered to be non-crystalline, but some of them exhibit crystallinity when their molecular repeating constituent units are regular and symmetrical.

Specifically, for example, polyolefins such as polyethylene and polypropylene, 6-nylon, 6.6-nylon,
6.10-Polyamides such as nylon; polyoxymethylene, polyethylene terephthalate, isotactic polystyrene, polyethylene sebacate, polytetrafluoroethylene, etc. belong to this category. However, even though these crystalline polymers are generally available, their light diffusivity is very poor, and they cannot be used as transmission screens. Therefore, in order to improve its crystallinity and obtain excellent light diffusivity, heat treatment for crystal growth is required. The crystallinity (two-light diffusivity) of a crystalline polymer depends not only on the ease with which the molecular chain itself crystallizes, but also on the thermal history during crystallization from a molten state.

For example, when a crystalline polymer is gradually cooled from a molten state, its crystallinity (double-light diffusivity) is very large, but when it is rapidly cooled from a molten state, even though it is a crystalline polymer, its crystallinity is very large. Does not exhibit crystallinity (dipodiffusivity). In this way, the thermal history between [melting = crystal solidification] is an important process for the crystallinity (two-light diffusivity) of crystalline polymers, and heat treatment that controls this process can achieve arbitrary crystallinity (two-light diffusivity). The heat treatment conditions include the treatment temperature and its time change, and these conditions are determined based on the required performance of the screen.The transmission type screen is shown in Figure 1. The structure is such that an image or information is projected from behind the screen 1 by a projector 2, and an observer 3 can observe the image or information at a position opposite to the projector 2.

As is well known, transmission screens are used for a variety of purposes, and the characteristics required of the screen differ depending on the purpose of use and the environment in which it is used.

For example, when used in audiovisual education equipment for groups, excellent light diffusion is required so that a bright image can be seen at a wide angle of view, whereas in individual learning equipment and micro readers, brightness is required rather than light diffusion. is required. Therefore, the heat treatment conditions should be changed each time depending on the required performance. Furthermore, using a crystalline polymer material to form a screen has an important advantage not only in that the above-mentioned screen characteristics can be obtained, but also in that it satisfies mass production of the screen.

In other words, similar to the conventional production of plastic sheets and films, extrusion molding using an extruder and T-die allows for continuous molding, and is much more efficient than the calender roll method or casting method, making it inexpensive. You can get a sheet. Furthermore, since extrusion molding is relatively simple in operation and work, it is easy to mechanize and automate the process, which has many advantages in terms of product quality control and other aspects.

The sheet thus formed using an extrumeter or T-die is subsequently subjected to heat treatment to promote crystallization, resulting in a sheet with excellent light diffusing properties, which is used as a screen.

As for the specific method of this crystallization heat treatment, it can be carried out very effectively by the method described in Japanese Patent Application No. 127981/1982 or Japanese Patent Application No. 10411/1989 filed by the applicant. is possible.

However, when using a light diffusion sheet made of the crystalline polymer material alone, it has insufficient mechanical strength for practical use because it needs to be a thin film from the point of view of light transmittance. When making a large screen, a reinforcing frame is required, or a transparent support is required to be tightly bonded using an adhesive or the like.

The thickness of the light diffusion layer of the conventional screen is 0.6
If it exceeds ~1.0 mm, the resolution and sharpness of the image will drop drastically, resulting in a very unsightly star screen. Therefore, when using it alone without using a support, use a screen with a small screen size, such as 8 mm film. It is used for editing machines and monitor stareens for 8mm, 11mm, and 16mm video machines, and for large screens, the machine is In other words, when a support is required, a light diffusing layer 7 is provided on a transparent support 5 via a bonding layer 6 as shown in FIG. Generally, the transparent support 5 is provided on the viewer 3 side.

In the case of a configuration in which the transparent support 5 is provided on the viewer 3 side, essentially it is sufficient that the transparent support 5 has the function of supporting the light diffusion layer 7, but it is necessary to make the projected image easier to see. Various efforts have been made to achieve this goal. One example is a method of applying a so-called NOnglare treatment in which fine irregularities are formed on the front surface of the transparent support 5 to prevent the reflected image around the screen 4 from overlapping with a predetermined projected image, resulting in poor visibility. . Alternatively, the transparent support 5 may be appropriately colored to prevent surface reflection from the surface of the light diffusion layer 7 (back scattering due to ambient light).
) is also available to improve the contrast of the projected image. Furthermore, if there is air between the transparent support 5 and the light diffusion layer 7, reflection will occur there and cause a reduction in the contrast of the image, so the two should be closely bonded (optically bonded) to prevent air from entering. ), and various efforts have been made for this purpose. Further, it is desirable that the material of the bonding layer 6 provided has optically similar performance to that of the transparent support 6 and the light diffusion layer 7, and in this sense, limitations on the material are unavoidable. Furthermore, it has been proposed that the bonding layer 6 not only has the effect of eliminating air intrusion, but also that the contrast of the projected image is further improved by coloring the bonding layer 6 to maintain its light absorption ability. A screen with such a structure consisting of a light diffusing layer, a bonding layer, and a transparent support certainly provides an excellent projected image and is perfect as a screen, but in manufacturing it, the light diffusing layer 7 and the transparent support are Considering the process of joining 5 and 5 while preventing air from entering, it is still not completely satisfactory in terms of production costs and the like.

In view of these points, the present invention integrates a light diffusion layer, a bonding layer, and a support, thereby improving not only its screen properties, but also
It is an object of the present invention to provide an extremely excellent method of manufacturing a screen member that is fully satisfactory in terms of productivity.

The method for manufacturing a screen member of the present invention is to unevenly distribute light diffusion regions on one surface side in a layer, and the third
As shown in the figure, by providing a thin light diffusion region 10 in a part of a screen 9 having a thickness necessary for self-reliance, the screen can produce images with excellent resolution and sharpness.

At the same time, the surface of the screen 9 may be subjected to a glare treatment to improve the visibility of the image as described above, or may be colored to improve contrast. The method for producing a screen member of the present invention involves extruding a member made of a molten crystalline polymer into a sheet by extrusion molding at a temperature below the temperature at which the member melts and at a temperature at which the member crystallizes. By exposing one side of the member to a roller having a temperature below the temperature at which the member melts and above the temperature at which the member crystallizes, the member is exposed to a temperature atmosphere maintained at a temperature below. By forming a temperature difference in the thickness direction of the member such that the side that crystallizes is above the crystallization temperature and the side that prevents crystallization is below the crystallization temperature, heat-treated, and then (gradually) cooled. A light diffusion region is formed by locally crystallizing one side of the member.

Specifically, in the present invention, for example, polyolefins such as polyethylene and polypropylene, 6-nylon, 6-nylon,
．． Polyamides such as 6-nylon, 6.10-nylon; polyoxymethylene, polyethylene terephthalate,
Crystalline polymeric materials such as isotactic polystyrene, polyethylene sebacate, polytetrafluoroethylene, etc. are used.

The manufacturing method of the screen member of the present invention is an extremely simple manufacturing method with integral molding that does not require the provision of a support and a bonding layer, and the resulting screen member itself is self-supporting. By doing so, it is possible to solve the problem of reflection at the interface between the light diffusion layer and the bonding layer, and the bonding layer and the support, and there is no need to closely bond the support through the bonding layer. Therefore, the production process can be shortened and simplified, mass productivity can be further improved, and production costs can be reduced, which has excellent effects in many fields.

The method for manufacturing the screen member of the present invention will be described below.

The present invention utilizes extrusion molding using an extruder and a T-die to manufacture a screen member in a series of steps with good mass productivity.

Specifically, in the process of manufacturing a screen member, a screen member formed using a crystalline polymer material by extrusion molding is heated to a temperature below the temperature at which the member melts while the screen member is in a molten state. With one side (back side) of a screen member formed on a roller that is controlled at a temperature that is controlled to be at a temperature higher than the crystallization temperature, the surface is exposed to infrared rays, etc., at a temperature lower than the crystallization temperature of the screen member. In the thickness direction of the screen member by heating it to a certain temperature,
Effect of subsequent crystallization heat treatment by creating a temperature difference such that the back side of the member is at a temperature higher than the temperature at which the member crystallizes, and the front side of the member is at a temperature lower than the temperature at which the member crystallizes. After creating a difference in the temperature, the light diffusing region is formed on the back surface side by cooling. That is, when the raw resin serving as the screen member is fed into the extruder 1, it is sent to the T-die by the rotation of the screw 1. A heater is installed on the outside of the extruder's first barrel, and the heating gradually softens the raw material resin until it becomes molten.The feed pressure generated by one revolution of the screw causes the sheet to pass through the narrow slit of the T-die. It is formed into a shape. Next, heat treatment is performed to promote crystallization for the purpose of imparting light diffusivity, but in the present invention, the crystallization atmosphere of this heat treatment is concentrated in a part of the screen member, and the crystallization is locally caused. This is to promote light diffusion and create a light diffusion area.

The light diffusing sheet thus obtained may then be embossed using a matte-treated roller, if necessary, or subjected to plastic processing to create fine irregularities on at least one side of the sheet.
So-called nano-glare processing is applied. It does not essentially matter whether this nanoglare treatment is carried out after the sheet is formed and before the heat treatment for promoting crystallization, but it is carried out in the order convenient for the heat treatment method. For example, when heat treatment to promote crystallization is performed in a bath solution after forming the sheet, the roller that takes the molten sheet from the T-die is given a matte finish, and then the nanoglare treatment is applied by embossing, and then the bath is heated. Heat treatment is performed in the liquid. In this case, if there is only one matte roller, only one side can be glared, and if there are two, both sides can be glared, but either is fine. Furthermore, if a coloring agent is mixed in the raw material resin as a screen material in advance, when it is melted in the extruder, the coloring agent and raw resin will be uniformly kneaded by the rotation of the screw, so that it will be molded. The sheets can be obtained in colored form. Alternatively, the light diffusing sheet may be subjected to crystallization heat treatment and then colored in a dyeing tank.

At this time, the order of the Nanglare treatment and the coloring treatment may be either performed first. The present invention will be further explained in detail below with reference to Examples.

Example 1 High density polyethylene (ρ=0.970
, M1=6.5), and the width is 50±5? using an extruder and T-die. , thickness 4.8m77! form the plate.

This plate is subsequently subjected to crystallization heat treatment, but at this time, the formed plate remains in a molten state as it comes out of the T-die.
The plate is taken through an atmosphere (tunnel oven) maintained at 15±1° C. with one side in contact with a drum kept at 123±1° C., and a temperature difference is formed in the thickness direction of the plate.

After this contact time was 20±3 minutes in a tunnel oven, the sample was allowed to cool slowly to room temperature. In addition, as comparison samples at this time, 5 painted screens used in conventional microreaders and 5 plates with a thickness of 4 mm were immediately heated in a heat treatment tank with polyethylene glycol as a heating medium at 126°C + 2°C for hours in a molten state. Crystallization heat treated for 10 to 20 minutes 6 Same method as above to a thickness of 0.3 mm
Prototype screen 3 was made by molding a sheet, melting the entire surface, and applying the same heat treatment to the diffusion sheet, bonding it with an adhesive (Acrytac, manufactured by Sony Chemical) using a 2 mm thick cast acrylic plate as a support. I used seeds. The screens were colored the same blue hue, and their densities were also adjusted to the same extent. The measurement method for each evaluation item is that the diffusivity of 1 is the angle that shows 0.5 when the horizontal angular dependence of the diffusely transmitted light when the light incident on the Screly is diffused is normalized with the optical axis component being 1. , that is, expressed as an angle that gives a half value of the optical axis component.

The brightness in 2 is expressed as the total diffuse transmittance at a measurement wavelength of 550 mμ, and the resolving power in 3 is the limit of 1 mm that can be discerned using a 5x magnifying glass on a screen using a 5x magnifying glass. The evaluation was based on the number of pieces per item.

Contrast 4 has a large subjective element, so it will be sensually evaluated as a panel test by five people.

The evaluation was carried out using Fissure Reader 200 (manufactured by Canon), and the results were: ◎: 4 points, ○: 3 points, △: 2 points, ×
; Expressed as the average of 5 people who scored 0 points. All of the screens according to the present invention provide excellent contrast, but in terms of resolution, the screen with a thickness of 8 m1L has 8.5 lines/screen.
M77! It shows a slightly lower value.

However, according to what is physiologically estimated from the resolving power of the eye, a value of about 8 lines/Mm is sufficient, so the value of 8.5 lines/Mm for this 8 mm lens is sufficiently satisfactory. or,
In the case of a 4 mTL type having a diffusion layer on one side and the entire surface, the resolving power is extremely low at 603 lines/M7n, compared to 9.7 lines/Mm on one side. This is due to the difference in the thickness of the diffusion layer, and the heat treatment according to the present invention crystallizes only a small portion of the thickness of the screen, creating a thin diffusion layer, which provides excellent resolution. Example 2 Using polypropylene as the crystalline polymer, Example 1
The effects of the present invention will be explained by molding plates with thicknesses of 4 mm and 8 mm using the same method as described above, and subjecting them to crystallization heat treatment.

The heat treatment and evaluation methods and comparative samples were the same as in Example 1, but the conditions for the crystallization heat treatment were as follows.

Temperature of tunnel oven: 147 ± 1°C Temperature of drum: 157 ± 1°C Time of contact with drum: 20 ± 3 minutes Temperature of crystallization heat treatment tank (heat medium Nipolyethylene glycol) for comparative sample 5: 160°C Time 10-20 minutes

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the use of a transmission screen, FIG. 2 is a conventional diagram, and FIG. 3 is a diagram illustrating the configuration of a transmission screen according to the present invention. 1... Transmissive screen, 2... Projector, 3... Observer, 4... Conventional transmissive screen, 5...・Transparent support, 6...
...Joining layer, T ...Light diffusion layer, 8...
. . . Projection light, 9 . . . Transmissive screen of the present invention, 10 . . . Light diffusion region.

Claims (1)

[Claims] 1. A member made of a molten crystalline polymer extruded into a sheet by extrusion molding is irradiated with infrared rays at a temperature below the melting temperature of the member and below a temperature at which the member crystallizes. By exposing one side of the member to a roller having a temperature below the temperature at which the member melts and above the temperature at which the member crystallizes in an atmosphere of The temperature difference is created such that the side that causes crystallization is above the crystallization temperature and the side that prevents crystallization is below the crystallization temperature, and then heat treatment is performed and then cooled to locally form one side of the member. A method for manufacturing a screen member, characterized by forming a light diffusion region by crystallizing the screen member.