JP3020330B2 - UV curable resin composition for Fresnel lens and transmission screen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet curable resin composition and a transmission screen for producing a Fresnel lens sheet, and more particularly to a transmission screen having a short focus type Fresnel lens.

[0002]

2. Description of the Related Art Conventionally, as a transmission type screen used in a projection television or the like, for example, a circular Fresnel lens for converting diffused light from a light source such as a CRT into parallel light and sending it to an observer side, There is known a configuration in which a lenticular lens that functions to distribute light only to a range seen by an observer is used in order to effectively use light. In recent years, projection TVs have been increasing in size. In particular, in order to reduce the thickness of the TV itself, it is necessary to reduce the distance between the light source and the screen, and the light emitted from the light source is reflected at a large angle and the reflection loss is reduced. As described above, a short focal length lens sheet made of a material having a large refractive index is used for a Fresnel lens sheet in order to project light on a screen.

Conventionally, in order to form a high-refractive-index short-focal lens for the above-mentioned transmission screen, it is necessary to use polymethyl methacrylate (refractive index n = 1.49) having good transparency and polystyrene (refractive index) having a high refractive index. n = 1.59) and the like (acrylic-styrene copolymer (refractive index n = 1.56-
The resin sheet of 1.57) was used to form a Fresnel lens sheet by molding the surface into a Fresnel lens shape by means such as hot press molding. However, the above-mentioned conventional hot press molding method requires a strict temperature condition for heating in order to reproduce a complicated shape of the surface when forming a large-area Fresnel lens sheet, and the molding process is troublesome. In addition, there is a problem that it takes time for pressurization and cooling, and the productivity is very low. Therefore, as a molding method instead of the conventional heating press, a Fresnel lens is formed on a substrate using an ultraviolet-curable resin, and a Fresnel lens sheet is efficiently formed in a short time only by irradiation of ionizing radiation such as ultraviolet rays. A method has been proposed.

[0004]

Incidentally, a transmission screen has a structure in which a plurality of lens sheets are combined, such as a Fresnel lens sheet and a lenticular lens sheet, and is applied during vibration and warping during transportation. There is a problem that the Fresnel lens surface rubs against another lens sheet surface due to stress etc., and it is damaged. To solve this problem, insert a buffer sheet etc. between the lens sheets, or use a lubricant such as silicone oil. And apply
It has been practiced to prevent damage due to surface rubbing. However, if the buffer sheet is sandwiched between the lens sheets, it is necessary to remove the sheet before use after transportation, and if silicone oil or the like is used, the sharpness and durability of the image are reduced. Therefore, it is desired to impart physical properties of the Fresnel lens surface having excellent scratch resistance to the lens sheet itself.

[0005] However, in the conventional ultraviolet curable resin composition for Fresnel lens, when the refractive index of the cured product is increased, the cured resin becomes hard and the abrasion resistance is reduced, and the surface has an increased abrasion resistance. If the composition is too flexible, the refractive index decreases, and there is no such composition that satisfies both the scratch resistance and the refractive index of the surface. The present invention is to solve the above-mentioned drawbacks of the prior art, and provides an ultraviolet-curable resin composition for a Fresnel lens for forming a Fresnel lens sheet having a high refractive index and excellent scratch resistance. And to provide a transmission type screen lens using the composition.

[0006]

According to the present invention, as a result of various studies for solving the above-mentioned problems, in order to impart flexibility and a high refractive index, tolylene diisocyanate is used as a prepolymer. Urethane acrylate is used as the main component, difunctional bisphenol A diacrylate is used as the reactive diluent, and bromo acrylate is used to increase the refractive index. By adding caprolactone-modified hydroxypivalic acid ester neopentyl diacrylate for the latter two components in a specific amount range, a cured product of the composition maintains a high refractive index and has excellent scratch resistance. It was found that a Fresnel lens was obtained, and the present invention was completed.

That is, the ultraviolet-curable resin composition for a Fresnel lens of the present invention is an ultraviolet-curable resin composition containing a urethane acrylate prepolymer based on tolylene diisocyanate as a main component, and 100% by weight of the urethane acrylate prepolymer. Parts by weight, at least 30 to 60 parts by weight of bromoacrylate and 10 to 40 parts by weight of caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate, and the cured product has a refractive index of 1.5 or more. It has.

The caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate used in the present invention is a bifunctional acrylate obtained by esterifying hydroxypivalic acid ester neopentyl glycol with caprolactone diol to lengthen the straight chain of the skeleton and acrylate it. The flexibility is increased by lowering the functional group density. If the content of the diacrylate is less than 10 parts by weight, sufficient flexibility cannot be obtained, and if it exceeds 40 parts by weight, the refractive index will decrease. As this diacrylate, for example, HX-220 or the like under the trade name of Nippon Kayaku can be used.

The urethane acrylate prepolymer used in the composition of the present invention is tolylene diisocyanate (TD).
A prepolymer of terminal acrylate obtained by reacting I) with a polyol component such as polyether polyol or polyester polyol is used.

Bromine acrylate is used to increase the refractive index of a cured product. The higher the amount of bromoacrylate, the higher the refractive index of a Fresnel lens. However, it is usually solid at room temperature and the amount of soluble in a composition is limited. Therefore, the content is at most 60 parts by weight based on 100 parts by weight of urethane acrylate, and if it is less than 30 parts by weight, it becomes difficult to obtain a sufficient refractive index. As the bromoacrylate used in the present invention, specifically, for example, 1-methylacrylate-
Examples include methacrylate of tribromophenol such as 2,4,6-tribromophenol and acrylate of ethylene oxide adduct of tetrabromobisphenol A.

The ultraviolet-curable resin composition for a Fresnel lens of the present invention is prepared by adding bisphenol A diacrylate as a reactive diluent to the urethane prepolymer 10 as a reactive diluent.
It is preferable to contain 30 to 60 parts by weight with respect to 0 parts by weight. Bisphenol A diacrylate has a higher refractive index due to having a benzene ring in its structure than monofunctional epoxy acrylate, and the physical properties of the cured product are softer.
It has the advantage that it does not easily adhere to the mold, and can be used as a reactive diluent having a high refractive index and good releasability.
The above-mentioned bisphenol A diacrylate is a diacrylate obtained by adding acrylic acid to a terminal hydroxyl group such as an ethylene oxide (EO) or propylene oxide (PO) adduct of bisphenol A, and adding EO or PO. The number of moles affects the flexibility and refractive index of the cured product. EO and PO contained in the main chain of the polymer
A long chain improves the flexibility of the cured product, but decreases the number of benzene rings contained in the cured product and lowers the refractive index. Therefore, in the present invention, a good balance between flexibility and high refractive index can be maintained by using a combination of bisphenol A diacrylate having a small number of added EOs and a compound having a large number of added EOs. For this purpose, the content of the former is desirably 15 to 30 parts by weight, and the content of the latter is desirably 15 to 30 parts by weight. As the bisphenol A diacrylate used in the present invention, for example, FM-300 (trade name) manufactured by Nippon Kayaku Co., Ltd. for those with a small number of added EOs, and Nippon Kayaku ( BR-800 (trade name) manufactured by KK Corporation. If the content of bisphenol A diacrylate is less than 30 parts by weight, the dilutability is not sufficient, and if it exceeds 60 parts by weight, the moldability deteriorates due to the excessive fluidity of the resin at the time of molding the cured product due to the decrease in viscosity. I do.

In the present invention, as a reactive diluent,
A monofunctional urethane acrylate monomer containing a hydroxyl group and a benzene ring can be contained in an amount of 10 to 40 parts by weight. Such a monofunctional acrylate improves the flexibility of the cured product and contributes to a higher refractive index. Examples of the monofunctional urethane acrylate monomer that can be used in the present invention include OPP-2 (trade name) manufactured by Nippon Kayaku.

Further, the ultraviolet-curable resin composition for a Fresnel lens of the present invention preferably contains 2 to 10 parts by weight of a pentaerythritol tetrafunctional monomer in the above composition. The pentaerythritol-based tetrafunctional monomer contributes to crosslinking during curing and improves the elasticity of the cured product. If the content of the pentaerythritol tetrafunctional monomer is less than 2 parts by weight, sufficient elasticity cannot be obtained, and
If the amount exceeds the weight part, the cured product becomes hard due to excessive crosslinking. Pentaerythritol type 4 used in the present invention
As the functional monomer, for example, RP-1040 manufactured by Nippon Kayaku
(Product name) and the like.

[0014] As the reactive diluent, a substance other than bisphenol A diacrylate may be added to the above composition as long as other physical properties are not impaired. As another reactive diluent, for example, a phenoxyethyl acrylate monomer or the like can be used.

The ultraviolet-curable resin composition for a Fresnel lens of the present invention contains a urethane acrylate based on tolylene diisocyanate as a main component, so that the polymer as a cured product contains many benzene rings, Oxidation of the benzene ring causes yellowing of the cured product. Therefore, in the present invention, the amine-based additive
It is preferable to add up to 5 parts by weight. The amine-based additive can stabilize the double bond in the benzene ring by its reduction curing, and can improve the weather resistance. The amine-based additive used in the present invention is, for example, IM-82 manufactured by Nippon Kayaku.
0 (product name) and the like.

The above compositions are mixed so that the refractive index obtained by curing becomes 1.5 or more. When the refractive index of the cured product is lower than 1.5, when a Fresnel lens sheet is used, a sufficient short focus lens cannot be obtained, and satisfactory performance cannot be exhibited. The composition of the present invention has the above-mentioned TD
With a composition comprising a specific blending amount of an I-based urethane acrylate prepolymer and a specific amount of bromoacrylate and caprolactone-modified hydroxypivalate neopentyl glycol diacrylate, the cured product has a sufficiently high refractive index and has flexible physical properties. Therefore, there is no fear that the surface will be scratched when rubbed by contact with another lens sheet or the like during transportation or post-processing.

The ultraviolet-curable resin composition for a Fresnel lens of the present invention can be cured by irradiation with ionizing radiation such as ultraviolet light or an electron beam. Add initiator. As the photopolymerization initiator, known acetophenones, benzophenones, thioxanthones, amines and the like are used.
The composition of the present invention may further contain other additives such as a light diffusion controller, an antistatic agent, a flame retardant, a colorant, and a surfactant.

FIG. 1 is a sectional view showing an example of the transmission screen of the present invention. As shown in FIG. 1, a transmission type screen lens 1 of the present invention has a Fresnel lens 5 obtained by curing the above-described ultraviolet curable resin composition for a Fresnel lens, and a lenticular lens having a light absorbing layer 4. It is arranged in combination with the seat 3. In the Fresnel lens sheet 2, it is preferable that after the primer layer 7 is provided on the surface of the base material 6, the Fresnel lens 5 is formed on the primer layer 7 with the above resin. The adhesion between layers 5 is improved. In addition, as the base material, a transparent synthetic resin sheet such as polymethyl methacrylate, polystyrene, or polycarbonate, a film, or the like is used.
There is no particular limitation as long as it has good adhesiveness to both the base material and the ultraviolet-curable resin composition for a Fresnel lens of the present invention. As such a primer, for example, a vinyl chloride-vinyl acetate copolymer, a butyral primer, a urethane primer, a phenoxy primer and the like can be used. The transmission screen 1 of the present invention
Need only have a Fresnel lens sheet 2 provided with a Fresnel lens 5 formed from the above-mentioned ultraviolet-curable resin composition. In addition to the combination with the lenticular lens sheet 3 shown in FIG. It can be formed in any combination with a lens sheet.

In order to manufacture the Fresnel lens sheet 2 using the ultraviolet-curable resin composition for a Fresnel lens of the present invention, first, a mold having a Fresnel lens surface is prepared, and the mold is coated with the resin composition. Work. Next, after the primer layer 7 is provided on the base material 6 in advance, the primer layer 7 is brought into contact with the resin filled in the mold so as to prevent air bubbles from entering, laminated by pressing, and ultraviolet rays or the like are applied from the base material 6 side. The resin is cured by irradiating the resin with ionizing radiation, and the mold is released. Examples of the ionizing radiation include ultraviolet rays generated from a light source such as a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a low-pressure mercury lamp, a carbon arc, a black light lamp, and a metal halide lamp, and electron beams generated from various electron beam accelerators.

[0020]

The present invention will be described below in more detail with reference to specific examples. Example 1 A UV curable resin composition for a Fresnel lens mainly composed of a urethane acrylate prepolymer shown below is applied to a Fresnel lens mold previously plated with chromium using a dispenser, and the surface is previously coated on the surface. A 3 mm-thick acrylic plate (Sumitomo Chemical: SUMIPEX HT) provided with a primer [vinyl chloride-vinyl acetate copolymer (UCC: VAGH)] layer was blown over the resin filled in the mold with air. The layers were pressed under pressure so as not to enter, and ultraviolet rays were irradiated using a high-pressure mercury lamp for 30 seconds to cure the ultraviolet-curable resin, and then the mold was peeled off to obtain a Fresnel lens sheet. In addition, the following UV-curable resin composition for Fresnel lens was applied with a strength of 50.
The refractive index of the cured product itself obtained by irradiating mw / cm ² with ultraviolet rays (sodium D line) for 30 seconds was 1.55.

[Ultraviolet curable resin composition for Fresnel lens] Ingredient name (manufacturer: trade name) parts by weight ・ urethane acrylate prepolymer based on tolylene diisocyanate (Nippon Kayaku: TU03) 100.0 ・ monofunctional urethane acrylate Monomer (Nippon Kayaku: OPP-2) 25.0 Bisphenol A diacrylate (Nippon Kayaku: FM-300) 25.0 (Nippon Kayaku: BR-800) 25.0 ・ Brom acrylate (Nippon Kayaku: BR-100) 50.0-Pentaerythritol-based tetrafunctional monomer (Nippon Kayaku: RP-1040) 5.0-Caprolactone modified hydroxypivalate ester neopentyl glycol diacrylate (Nippon Kayaku: HX-220) 25.0 -1-hydroxycyclohexyl phenyl ketone ( Bagaigi: Irgacure 184) 2.5 amine-based additive (Nippon Kayaku: IM-820) 2.5 - Fluorine-based surfactant (Sumitomo 3M: Fluorad FC-430) 0.8

[0022]

As described above, the ultraviolet-curable resin composition for a Fresnel lens of the present invention has the above-mentioned constitution, so that a cured product of the composition has flexibility and excellent scratch resistance. In order to have a refractive index, by a simple operation of coating the composition on a substrate and irradiating with ionizing radiation,
A short-focus Fresnel lens sheet is obtained, and the Fresnel lens sheet has flexibility and the surface has excellent scratch resistance. Since the transmission screen of the present invention has a Fresnel lens sheet obtained by curing the ultraviolet curable resin for a Fresnel lens, the transmission screen has a Fresnel lens sheet surface having excellent scratch resistance on the surface, and during transmission of the transmission screen. Contact with other lens sheets when performing post-processing or
There is no danger of being damaged by rubbing due to vibration or stress, and there is no need to sandwich a buffer sheet between lens sheets or use silicone oil or the like as in the related art. The transmissive screen of the present invention can form a short focal point Fresnel lens to shorten the distance between the transmissive screen and the light source. Therefore, in particular, a large projection television can be made thinner and smaller, and the projection TV can be enlarged. To contribute.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a transmission screen of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmissive screen 2 Fresnel lens sheet 6 Substrate

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI // B29C 39/02 B29C 39/02 C08J 7/00 304 C08J 7/00 304 B29L 11:00 (56) References JP JP-A-4-288314 (JP, A) JP-A-4-88265 (JP, A) JP-A-5-65318 (JP, A) JP-A-5-134101 (JP, A) JP-A-3-255118 (JP, A A) JP-A-3-255117 (JP, A) JP-A-3-239711 (JP, A) JP-A-5-78507 (JP, A) JP-A-4-216814 (JP, A) JP-A-3 -281511 (JP, A) JP-A-3-296513 (JP, A) JP-A-3-215512 (JP, A) JP-A-3-157412 (JP, A) (58) Fields investigated (Int. . ^7, DB name) C08F 290/00 - 290/14 C08F 2/46 - 2/50 G02B 1/04 G02B 3/08 G03B 21/62

Claims (4)

(57) [Claims] An ultraviolet-curable resin composition containing a urethane acrylate prepolymer based on tolylene diisocyanate as a main component, wherein at least bromoacrylate is contained in an amount of 30 to 60 parts by weight based on 100 parts by weight of the urethane acrylate prepolymer. Containing 10 to 40 parts by weight of caprolactone modified hydroxypivalic acid ester neopentyl glycol diacrylate,
An ultraviolet-curable resin composition for a Fresnel lens, wherein the cured product has a refractive index of 1.5 or more. 2. Bisphenol A diacrylate is used in an amount of 30 to
The ultraviolet-curable resin composition for a Fresnel lens according to claim 1, which contains 60 parts by weight. 3. The ultraviolet-curable resin composition for a Fresnel lens according to claim 1, comprising 2 to 10 parts by weight of a pentaerythritol-based tetrafunctional monomer. 4. A transmission type screen comprising a Fresnel lens sheet provided with a Fresnel lens made of the ultraviolet-curable resin composition for a Fresnel lens according to claim 1, on a base material.