JP2000102933A - Photosetting resin composition for lens sheet, lens sheet and production of lens sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photosetting resin compsn. suitable for producing a lens sheet of a Flesnel lens, a renticular lens or a condensing Flesnel lens. SOLUTION: A compsn. consists of at least one kind of a polythiol compd. (A) having at least two or more mercapto groups in one molecule, at least one kind of an acrylic compd. (B) having at least two or more aryl groups in one molecule and at least one photopolymerization initiator (C) and a ratio of the total number of thiol groups in the polythiol compd. (A) and that of aryl groups in the aryl compd. (B) is 5:1-1:5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable resin suitable for producing a lens sheet such as a Fresnel lens, a lenticular lens or a condensing Fresnel lens used for a transmission screen such as a video projector and a projection television. The present invention relates to a composition, a lens sheet as a cured product thereof, and a method for producing the same.

[0002]

2. Description of the Related Art Heretofore, lens sheets such as Fresnel lenses have been formed by a method such as a pressing method or a casting method. The former press method has a drawback that productivity is poor because it is manufactured by a cycle of heating, pressurizing and cooling, and metal erosion is remarkable due to heating and pressurizing. On the other hand, in the latter casting method, a monomer is poured into a mold and polymerization is performed, so that it takes a long time to produce the mold, and a large number of molds are required.

In order to solve such a problem, various proposals have been made for using an ultraviolet-curable resin composition (JP-A-61-177215, JP-A-61-248707, and JP-A-61-248707). 61-248708
JP-A-63-16330, JP-A-63-16330
167301, JP-A-63-199302, JP-A-64-6935, etc.). For example, as a typical production method, a method of interposing an ultraviolet-curable resin liquid between a lens mold and a transparent substrate and irradiating ultraviolet rays to cure the resin, as described in JP-A-61-177215. Is taken.

[0004] A method for producing a lens sheet by using these ultraviolet curable resin compositions has been somewhat successful. However, the cured product of the conventional photocurable resin composition has insufficient adhesion to a transparent substrate (eg, sheet-like plastics such as polycarbonate, polymethacrylate or polyester) which is the base of the lens sheet. Therefore, the surface of the transparent substrate is often subjected to a primer treatment, which complicates the operation process and has a problem.

[0005] By the way, usually, a pair of transmissive screens are often used one by one so as to form a Fresnel lens on the light source side and a lenticular lens on the observer side. At that time, the Fresnel lens is placed so that the corrugated lens surface formed by the ultraviolet curable resin composition faces the lenticular lens, and the two lenses are brought into contact with each other, but the gap is not filled with resin or the like. It is commercialized by fixing around the screen. For this reason, especially when subjected to shock or vibration during transportation, the tip of the corrugated surface of the Fresnel lens strikes the lenticular lens, deforming or damaging the tip, or causing minute abrasions on the opposing lenticular lens surface, causing a decrease in image quality. Had become.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lens sheet having good adhesion to a transparent substrate so that no primer treatment or the like is required at the time of producing a lens sheet by photocuring with ultraviolet light or the like. It is an object of the present invention to provide a photocurable resin composition for a lens sheet which is less likely to cause deformation, breakage, abrasion, etc., when the transmission type screen is constituted by a lens sheet such as a lenticular lens.

[0007]

The present invention relates to (A) at least one kind of polythiol compound having at least two mercapto groups in one molecule, and (B) at least two or more allyl groups in one molecule. A composition comprising at least one allyl compound and (C) at least one photopolymerization initiator, wherein the number of all thiol groups in the polythiol compound (A) and the number of all allyl groups in the allyl compound (B) are The present invention relates to a photocurable resin composition for a lens sheet, wherein a ratio of numbers is 5: 1 to 1: 5.

The polythiol compound (A) used in the present invention may have a molecular weight of 150 to 1,000,
It may have up to 6, preferably 2 to 4, more preferably 3 to 4 mercapto groups.

The polythiol compound (A) is

Embedded image

Embedded image Wherein R ¹ represents CH ₃ or CH ₃ CH ₂ , and R ² is CH
₂ or CH ₂ CH ₂ . ]

Embedded image [Wherein, R ³ represents H or CH ₃ , R ⁴ represents CH ₂ or CH ₂ CH ₂ , m and n are integers satisfying m + n = 6, and n represents 2 or more. ]

Embedded image [In the formula, R ⁵ represents an alkylene group having 1 to 6 carbon atoms. ].

The polythiol compound (A) includes, for example, trimethylolpropane tristhioglycolate,
Trimethylolpropane tristhiopropionate, pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, 1,
2,4-tris (mercaptomethyl) benzene, 1,
3,5-tris (mercaptomethyl) benzene, 2,
4,6-tris (mercaptomethyl) mesitylene, 1,
2,4,5-tetrakis (mercaptomethyl) benzene, tris (2-mercaptoethyl) isocyanurate
G, tris (3-mercaptopropyl) isocyanurate
And these can be used alone or as a mixture. Pentaerythritol tetrakisthioglycolate is preferred.

The allyl compound (B) may have a molecular weight of from 150 to 1,000, and has two allyl groups in one molecule.
-5, preferably 2-4, more preferably 2-3.

The specific allyl compound (B) used in the present invention includes cyanuric acid or isocyanuric acid,
Alternatively, all hydrogen atoms present in a compound selected from compounds obtained by substituting all oxygen atoms present therein with sulfur atoms are represented by the general formula (5):

Embedded image Wherein a is an integer of 0 to 2, b is 0 or 1, c is 0 or 1, d is 0 or 1, R is an unsaturated functional group, and at least two Rs are allyl groups . At least one acid derivative (B-
1) or a diallyl phthalate monomer (B-2).

The allyl compound (B) is an acid derivative (B-
1) 40 to 97% by weight (for example, 60 to 80% by weight) and diallyl phthalate monomer (B-2) 3 to 60%
% (E.g., 20-40% by weight).

In the acid derivative (B-1), the unsaturated functional group R may be an allyl group, a methallyl group, an acryloyl group or a methacryloyl group. In the acid derivative (B-1), all the unsaturated functional groups R are preferably allyl groups. Examples of the acid derivative (B-1) include triallyl cyanurate and triallyl isocyanurate.
These may be used alone or as a mixture. Triallyl isocyanurate is preferred for improving the toughness of the cured product.

Diallyl phthalate monomer (B-2)
May be a polybasic ester of an allyl alcohol having an aromatic ring. Diallyl phthalate monomer (B-
Examples of 2) include diallyl phthalate, diallyl isophthalate, and diallyl terephthalate. Diallyl terephthalate imparts elasticity to the cured product and is preferred for improving the refractive index.

In addition to the acid derivative (B-1) and the diallyl phthalate monomer (B-2), an allyl compound (B)
Is diallyl chlorendate, diethylene glycol bisallyl carbonate, tri (allyloxyphenyl)
It may be isocyanurate, tetraallyloxyethane, trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, or the like.

As for the mixing ratio of the specific polythiol (A) and the specific allyl compound (B) used in the present invention, the ratio of the thiol group in the polythiol used to the allyl group of the allyl compound used is determined by the thiol group. 5: 1 to 1: 5 is preferable with respect to an allyl group, and 3: 1 to 1: 3 is more preferable. If the blending ratio is out of this ratio and the amount of one of the polythiol or allyl compound is too large, it takes a long time to cure even when irradiated with light, thereby reducing productivity or not curing. Moreover,
If the amount of the polythiol is too large, a specific mercaptan smell becomes too strong even when cured, which is not suitable for the present invention.

The photopolymerization initiator (C) used in the present invention may be a known photopolymerization initiator. Specific examples include benzoin alkyl ethers such as benzoin ethyl ether, benzoin isobutyl ether and benzoin isopropyl ether; acetophenones such as 2,2-diethoxyacetophenone and 4'-phenoxy-2,2-dichloroacetophenone; -2
-Methylpropiophenone, 4'-isopropyl-2-
Propiophenones such as hydrosil-2-methylpropiophenone, 4'-dodecyl-2-hydroxy-2-methylpropiophenone, benzophenone, 3,3'-dimethyl-4-methoxybenzophenone, p, p'- Benzophenones such as tetramethyldiaminobenzophenone, benzylmethyl ketal, 1-hydroxycyclohexylphenyl ketone, acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2-ethylanthraquinone;
-Anthraquinone-based photopolymerization initiators such as chloranthraquinone, and thioxanthone-based photopolymerization initiators. These photopolymerization initiators may be used alone or in combination of two or more kinds at an arbitrary ratio. Benzophenone and benzoin ethyl ether are preferred.

The amount of the photopolymerization initiator used in the photocurable resin of the present invention varies depending on the type thereof, but is preferably an amount necessary and sufficient for the polymerization of the polymerizable composition, and 100 parts by weight of the curable resin composition. May be 0.1 to 10 parts by weight, for example, 1 to 6 parts by weight. Photoinitiators such as triethanolamine, methyldiethanolamine, triisopropanolamine, and ethyl 4-dimethylaminobenzoate may be added to the above photopolymerization initiator.

The photocurable resin of the present invention can be added with an allyl compound other than those described above, or an acrylic compound or a methacrylic compound to adjust the properties of the blend and the cured product. For example, the viscosity of the blended liquid can be increased by adding a small amount of diallyl phthalate prepolymer.

Further, the photocurable resin of the present invention comprises a polymerization inhibitor, a chain transfer agent, an antioxidant, a release agent, a light stabilizer, an antistatic agent, an ultraviolet absorber, an antifoaming agent, a shrinkage inhibitor and the like. Various additives can also be added.

In addition, the photocurable resin of the present invention may contain various metal oxides having an average particle diameter of 50 nm or less. At this time, if a high refractive index, for example, titanium oxide or zircon oxide having an average particle diameter of 30 nm is added, the refractive index of the system can be increased without substantially lowering the visible light transmittance.

The resin composition of the present invention can be obtained by mixing and dissolving each component. A cured product of the resin composition of the present invention can be obtained by irradiating the resin composition with light according to a conventional method. Specifically, for example, the resin composition of the present invention is applied on a stamper (mold) having a Fresnel lens shape, a layer of the resin composition is provided, and a hard transparent substrate (for example, , Polyvinyl chloride, polystyrene, polycarbonate, poly (meth) acrylate, polyester, or a transparent substrate made of a blend of these polymers, etc.), and then, in that state, a high-pressure mercury lamp or metal halide lamp from the hard transparent substrate side. After curing the resin composition by irradiating the resin composition with light, the cured product layer is peeled off from the stamper. In this way, a soft Fresnel lens having a normal refractive index (25 ° C.) of 1.56 or more can be obtained. The thickness of the resin composition layer is
0.02-0.8 mm, substrate thickness is 0.5-10 m
m.

As the light used in the present invention, a wide range of ultraviolet light, visible light and infrared light can be used in relation to a photoinitiator. It is preferable to use Curing is also possible depending on the conditions by electron beam, radiation, or the like.

The photocurable resin composition for a lens sheet of the present invention can form not only a layer on a substrate but also an entire lens sheet.

[0026]

Next, the present invention will be described more specifically with reference to examples. The evaluation in the examples was performed by the following method. In addition,
Parts are parts by weight.

(1) Releasability: The difficulty in releasing the cured resin from the mold was confirmed. ○ ・ ・ ・ Good releasability from the mold △ ・ ・ ・ Slightly difficult to release × ・ ・ ・ ・ Difficult to release or there is mold residue

(2) Mold reproducibility: The surface shape of the cured resin layer and the surface shape of the mold were observed. ○ ・ ・ ・ ・ Good reproducibility × ・ ・ ・ ・ Poor reproducibility

(3) Restorability: A metal round bar having a diameter of 10 mm was strongly pressed against a Fresnel lens manufactured using the resin composition (a load of 1.5 kgf was applied for 30 seconds), and then a round bar attached to the lens was used. The time until the traces disappeared completely was measured. ◎ ・ ・ ・ ・ It disappeared instantly ○ ・ ・ ・ ・ It disappeared within 60 seconds △ ・ ・ ・ ・ It disappeared between 60 seconds and 60 minutes × ・ ・ ・ ・ It did not disappear

(4) Scratch resistance: An acrylic plate (width 15 mm, length 1) was applied to a Fresnel lens produced using the resin composition.
(00 mm, thickness 2 mm) 15 mm x 2 mm surface is pressed firmly vertically (pressure on acrylic plate: 2 kgf / cm)
² ) While reciprocating 10 times at a speed of 1 second for 1 reciprocation at intervals of 100 mm while observing scratches on the lens surface. ◎ ・ ・ ・ ・ ・ ・ Scratch is not observed at all ○ ・ ・ ・ ・ Several streak-like scratches are observed △ ・ ・ ・ ・ Some band-like scratches are observed × ・ ・ ・ ・ Full band-like scratches Is recognized

(5) Adhesion: A resin composition is coated on a hard transparent substrate (width 20 mm, length 150 mm, film thickness 30).
0 μm) and then a metal halide lamp (1.5 kW, distance 10 cm from the lamp) for 5 seconds to cure. Next, it was evaluated by a cross cut test using an adhesive tape in accordance with JIS K5400. ○ ・ ・ ・ ・ No peeling ×× ・ Peeled off

(6) Flexibility: A spray type silicon-containing fluorine-based release agent (Daifree A-741, Daikin Industries, Ltd.) is applied as an external release agent on a glass substrate, and then coated with a resin composition ( Width 20 mm, length 150 mm, film thickness 300 μm), and then a metal halide lamp (1.5 k
(W, distance from the lamp: 10 cm) for 5 seconds to cure. After that, the cured film is stripped off and the half length 75
It is folded in half at the point of mm, a 5 kg lead weight is placed on the fold, a load is applied for 30 seconds, and then the fold is taken out and the fold is observed. ○ ・ ・ ・ ・ No abnormality is recognized △ ・ ・ ・ ・ Break remains × ・ ・ ・ ・ Break

(7) Refractive index (25 ° C.): The refractive index (25 ° C.) of the cured product of the resin composition was measured.

Examples 1 to 5 and Comparative Examples 1 to 4 Resin compositions having the compositions shown in Tables 1 and 2 (the numerical values indicate parts by weight) were prepared, and the resin compositions were mixed with a Fresnel lens mold and a thickness. 2.5mm polymethacrylic resin plate (untreated)
(Manufactured by Sumitomo Chemical Co., Ltd., extruded with methyl methacrylic resin “Sumiflex-B, HT013E” at a mold temperature of 165 ° C.), and a metal halide lamp (1.5 kW, 10 cm from the lamp). ) To irradiate ultraviolet rays for 5 seconds to cure, thereby obtaining a Fresnel lens (maximum thickness of the cured layer: 0.2 mm).

[0035]

[Table 1]

[0036]

[Table 2]

As is clear from Tables 1 and 2, the cured product of the resin composition of the present invention has excellent resilience, abrasion resistance, adhesion, flexibility and the like, and a refractive index (25 ° C.) of 1. It was 56 or more.

[0038]

The photocurable resin composition of the present invention has good adhesion to a transparent substrate when it is cured, and the cured lens sheet has excellent releasability and flexibility, and can reproduce the mold. sex,
Good resilience. In addition, when it is used for a transmission screen, the abrasion resistance between the lenses is excellent.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G02B 3/08 G02B 3/08 // C09D 181/02 C09D 181/02 B29K 101: 10 B29L 11: 00F Term (reference) 4F204 AA34E AA44 AB04 AG01 AH74 EA03 EB02 EF01 EF02 4J030 BA03 BA44 BA48 BA49 BA51 BB06 BB07 BC37 BC43 BD01 BE04 BF09 BF14 BF19 BG25 BG30 4J038 FA011 JB36 JC02 KA04 PA17 PB08

Claims (7)

[Claims] (A) at least one polythiol compound having at least two or more mercapto groups in one molecule, (B) at least one allyl compound having at least two or more allyl groups in one molecule, and (C)
A composition comprising at least one photopolymerization initiator, wherein the ratio of the number of all thiol groups in the polythiol compound (A) to the number of all allyl groups in the allyl compound (B) is 5: 1 to 1: 5. A photocurable resin composition for a lens sheet, characterized in that: 2. The photocurable resin composition for a lens sheet according to claim 1, wherein the number of mercapto groups in the polythiol compound (A) is 2 to 6. 3. The polythiol compound (A) has the general formula (1), (2), (3) or (4): Embedded image Wherein R ¹ represents CH ₃ or CH ₃ CH ₂ , and R ² is CH
₂ or CH ₂ CH ₂ . ] [Wherein, R ³ represents H or CH ₃ , R ⁴ represents CH ₂ or CH ₂ CH ₂ , m and n are integers satisfying m + n = 6, and n represents 2 or more. ] [In the formula, R ⁵ represents an alkylene group having 1 to 6 carbon atoms. 3. The photocurable resin composition for a lens sheet according to claim 2, which is at least one member selected from the group consisting of: 4. The method according to claim 1, wherein the allyl compound (B) is obtained by converting all hydrogen atoms present in a compound selected from cyanuric acid or isocyanuric acid or a compound in which all oxygen atoms present therein are replaced with sulfur atoms to a general formula (5): Wherein a is an integer of 0 to 2, b is 0 or 1, c is 0 or 1, d is 0 or 1, R is an unsaturated functional group, and at least two Rs are allyl groups . At least one acid derivative (B-1) substituted with an organic group
The photocurable resin composition for a lens sheet according to any one of claims 1 to 3, which is a diallyl phthalate monomer (B-2). 5. The lens according to claim 4, wherein the allyl compound (B) comprises 40 to 97% by weight of the acid derivative (B-1) and 3 to 60% by weight of the diallyl phthalate monomer (B-2). Photocurable resin composition for sheet. 6. A lens sheet comprising a resin layer formed by polymerizing the photocurable resin composition for a lens sheet according to claim 1 on a substrate. 7. A method for producing a lens sheet, comprising: providing a layer of the photocurable resin composition for a lens sheet according to claim 1 on a substrate, and curing the composition.