JP2772664B2 - Transmission screen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Technical Field) The present invention relates to an improvement of a transmission screen applied in the fields of optics and electricity.

(Conventional technology and problems) Transmission screens provided with lenticular lenses or Fresnel lenses are widely used in combination with small CRTs and LCDs.

However, for example, a methacrylic resin is used for a transmission screen substrate for a projection television in terms of light resistance and abrasion resistance. There is a drawback of impairing.

In order to prevent the warpage due to the moisture absorption of the substrate and the warpage due to the temperature difference between the outside air and the inside of the apparatus, a device has been devised in which the screen is formed in a convex or concave shape in advance, but this step is complicated. There was a problem.

Means for Solving the Problems The present inventors have made intensive studies particularly on the material of the substrate of the transmission screen, and if at least one substrate of the components of the transmission screen is made of a specific material, a convex or concave shape is obtained. The present invention was found to be a transmissive screen in which the optical performance was not degraded due to warpage when actually used without molding. Thus, the present invention was completed.

That is, the present invention provides: In a transmission screen having at least one surface provided with a lenticular lens or a Fresnel lens, at least one substrate of a constituent member is a methacrylic resin containing 2 to 30 mol% of a tert-butylcyclohexyl methacrylate unit. The present invention relates to a transmissive screen, which is a feature of the present invention.

In the present invention, tert-butylcyclohexyl methacrylate units constituting the methacrylic resin of the transmission screen substrate must be 2 to 30 mol%. 2 mol%
If it is less than 10%, a drastic change in the humidity of the atmosphere will cause the transmission screen to be warped, and 30 mol%
Exceeding the mechanical properties lowers the mechanical properties and causes cracks and the like during screen production.

The main component other than the tert-butylcyclohexyl methacrylate unit constituting the methacrylic resin of the transmission screen substrate is methyl methacrylate, but the ethylenically unsaturated compound unit represented by the formula (1) and a light diffusing agent And a colorant, and may be appropriately selected and blended depending on the configuration or manufacturing method of the transmission screen.

CH ₂ ＣC—R ₁ R ₂ (1) [where R _{1 is a} hydrogen atom or a methyl group, and R _{2 is a} phenyl group, a methyl-substituted phenyl group, or CO ₂ Z (Z:
An unsubstituted or fluorine-substituted alkyl group having 1 to 8 carbon atoms). The unit of the ethylenically unsaturated compound represented by the formula (1) is
It is effective in improving the thermal stability and fluidity during production, but when the compounding ratio exceeds 30 mol%, the heat resistance decreases, so when mixing, it must be 30 mol% or less. . The type of the ethylenically unsaturated compound unit is not particularly limited, but alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate; Fluorinated alkyl acrylates such as trifluoromethyl acrylate and 1,1,1-trifluoroethyl acrylate; styrene, α-
There are aromatic vinyl compounds such as methylstyrene and p-methylstyrene.

The method for producing the methacrylic resin for the substrate of the transmission screen of the present invention is not particularly limited, and ordinary cast polymerization, bulk polymerization, suspension polymerization, emulsion polymerization and the like are used.

When a light diffusing agent or a coloring agent is blended, the mixture may be heated and kneaded after the polymerization. To form a lenticular lens or a Fresnel lens, the above polymerization may be performed simultaneously, or after the polymerization, a usual injection molding method, compression molding method, extrusion molding method, or the like may be used.

When the transmissive screen is composed of one member, the substrate must be a methacrylic resin specified in the present invention, but when composed of a plurality of members, a part of the substrate of the member is used. The methacrylic resin specified in the present invention may be used, or all may be the methacrylic resin specified in the present invention. For example, in the case of a transmission type screen composed of separate members of a lenticular lens and a Fresnel lens, both may be made of a methacrylic resin defined in the present invention, or only one of the substrates may be made of the present invention. And the other substrate may be another transparent resin.

In the present invention, a light diffusing agent can be added to the methacrylic resin of the substrate of the transmission screen according to the purpose. There are no particular restrictions on the type and proportion of the light diffusing agent to be compounded, and it is selected according to the required light diffusing performance. For example, as inorganic materials, calcium carbonate, barium sulfate,
Titanium oxide, silicon dioxide, calcium fluoride, talc,
There are glass beads and the like, and as an organic type, there are a styrene resin, a crosslinked polymer mainly composed of methyl methacrylate / acrylate / aromatic vinyl monomer, etc., and any of them can be used alone or in combination of two or more. Among these, preferred are a crosslinked polymer containing methyl methacrylate / acrylate / aromatic vinyl monomer as a main component having an average particle size of 30 to 300 μm, calcium carbonate, quartz powder, barium sulfate, glass beads and the like.

In the transmission screen of the present invention, it is desirable to provide an external light absorbing layer on the observation surface in order to improve image contrast. The material and method of forming the external light absorbing layer are not particularly limited as long as they have a performance of absorbing external light. For example, in a lenticular lens having a total reflection surface on the observation surface, when an external light absorbing layer is formed on the total reflection surface, as a device for raising the total reflection efficiency, for example, Japanese Patent Application No. 63-223464.
As shown in the above item, a method of providing an air layer between the substrate and a coating material in which black dyes / pigments and specific spherical particles are blended, or using a transparent material smaller than the refractive index of the substrate as the main component There is a method using a compound containing a black dye or pigment, or a method of forming a layer mainly composed of a transparent substance having a smaller refractive index than the substrate between the external light absorbing layer and the substrate, Available.

(Examples and Comparative Examples) Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

I. Production of a transmission screen; (1) Production of a polymer for a substrate: A monomer obtained by adding 0.15 part by weight of azobisisobutyronitrile and 0.2 part by weight of n-octylmercaptan to a monomer having the composition shown in Table 1. The phases are water, potassium polyacrylate,
It was added to an aqueous phase composed of sodium hydrogen phosphate, stirred and suspended, and further stirred at a temperature of 75 ° C. for 2 hours to carry out polymerization. Thereafter, the temperature was raised to 95 ° C., maintained for 1 hour, cooled, and the content was filtered, washed with water, and dried to obtain a beaded polymer.

(2) Production of light diffusing agent (organic crosslinked polymer particles): The following compound was charged into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen gas inlet, and the like.

Methyl methacrylate 42 parts by weight Butyl methacrylate 33 parts by weight Styrene 25 parts by weight Allyl methacrylate 1.5 parts by weight t-dodecylmercaptan 0.3 parts by weight Azobisisobutyronitrile 0.5 parts by weight Polyvinyl alcohol 3.0 parts by weight Water 200 parts by weight After sufficient replacement with nitrogen gas, the mixture of the above compounds was heated to 70 ° C. with sufficient stirring, and the polymerization was advanced in nitrogen gas. After 4 hours, the temperature was raised to 90 ° C. and maintained at 90 ° C. for 1 hour to complete the polymerization. After completion of the polymerization, dehydration, washing with water, and drying were performed to obtain granular beads. The obtained peas were sieved to obtain organic crosslinked polymer particles having an average particle size of 35 µm.

(3) Production of substrate: 3% by weight of the light diffusing agent obtained in (2) is added to the bead-like polymer for substrate obtained in (1), and the mixture is heated and kneaded with an extruder (resin temperature 250 ° C.). Then, the molten resin discharged from the die was passed between rolls and cooled to obtain a milky white substrate of 850 × 650 × 3 mm.

(4) Molding of lenticular lens and Fresnel lens: The substrate manufactured in (3) is placed between a lenticular lens mold and a Fresnel lens mold, and is heated at a molding temperature of 160 ° C., a molding time of 10 minutes, and a molding pressure. After molding under the conditions of 30 kg / cm ² , the molded article was obtained by water cooling for 10 minutes. The used Fresnel lens mold has a pitch of 0.25mm and a focal length of 1,000mm
It is. The dimensions of the effective surface of the completed transmission screen were 813 × 610 mm.

The cross-sectional shape of the lenticular lens is an arc having a pitch of 0.5 mm and a central angle of 85 ° C.

II. Evaluation test Attach a transmission screen for testing that was left for one week in an atmosphere of 23 ° C and 50% humidity to a projection television, and put it in a constant temperature and humidity chamber of 50 ° C and 80% humidity for 2 hours.
The displacement at the center of the transmission screen was measured with a three-dimensional measuring machine. When the displacement at the central portion was 10 mm or less, it was judged that there was no problem in practical use, and was accepted.

In addition, cracks during molding of the lenticular lens and the Fresnel lens were observed.

III. Results: Examples 1 to 4 had small displacement due to moisture absorption and had good moldability.

On the other hand, in Comparative Example 1, the displacement due to moisture absorption was large, and in Comparative Example 2, cracks occurred during molding, making it impossible.

(Effect of the Invention) In the present invention, since the substrate constituting member of the transmission screen is a methacrylic resin containing a tert-butylcyclohexyl methacrylate unit, it is possible to absorb moisture without forming it in a convex or concave shape in advance. It is possible to sufficiently prevent return due to properties, temperature differences, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C08F 220/18 C08F 220/18 C08L 33/10 C08L 33/10

Claims (1)

(57) [Claims] 1. A transmission screen having at least one surface provided with a lenticular lens or a Fresnel lens, wherein at least one substrate of a component member is made of methacrylic acid te.
A transmission screen characterized by being a methacrylic resin containing 2 to 30 mol% of rt-butylcyclohexyl units.