JP2003240916A - Fresnel lens sheet and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for selectively forming a light shielding layer on the rise face of a Fresnel lens sheet so as to improve the contrast in an image on a projection TV. <P>SOLUTION: In the Fresnel lens sheet having a light shielding layer only on the rise face, the light shielding layer is formed on a layer made of a cured product of a photosetting composition (A). The photosetting composition (A) comprises 100 parts by mass of a photosetting resin composition (a) having ≥30 mN/m surface free energy and 0.01 to 10 parts by mass of a compound (b) having ≤25 mN/m surface free energy. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fresnel lens sheet necessary for a transmissive screen for a projection television and a manufacturing method thereof. In particular, the present invention relates to a method of forming a light-shielding layer on a Fresnel lens, which can dramatically improve contrast by reducing stray light.

[0002]

2. Description of the Related Art A transmissive screen used in a projection television generally comprises a combination of a Fresnel lens sheet and a lenticular lens sheet. The Fresnel lens sheet has a function of directing the image light emitted from a light engine such as a CRT or a liquid crystal display panel toward the lenticular lens sheet, and causing the image light to enter the lenticular lens sheet almost vertically. Further, the lenticular lens sheet has a function of enlarging the viewing angle of the image light vertically incident from the Fresnel lens sheet toward the observer.

[0003]

As shown in FIG. 1A, a general Fresnel lens sheet 1 is flat on the incident surface 2 side of image light and on the exit surface 3 side of a Fresnel lens surface 4 and a rise. It consists of surface 5. As shown in FIG. 1B, the image light 7 from the light engine 6 spreads and enters the Fresnel lens sheet 1. Therefore, most of the image light 7 can be emitted from the Fresnel lens surface 4 and incident on the lenticular lens sheet 1. However, as shown in FIG. 1C, a very small amount of the incident image light 7 reaches the rise surface 5 instead of the Fresnel lens surface 4. The image light reaching the rise surface 5 is directly emitted to the lenticular lens side, or
After being reflected by, the light exits from the Fresnel lens surface 4. These image lights are called stray lights because they do not enter the lenticular lens sheet vertically. The stray light mixes noise with the regular image light emitted from the lenticular lens sheet, and reduces the contrast of the projection television.

The present invention provides a Fresnel lens sheet with a light-shielding layer capable of dramatically improving the contrast of a projection television by reducing stray light emitted from the Fresnel lens sheet, and a simple manufacturing method thereof. Is an issue.

SUMMARY OF THE INVENTION The present invention for solving the above problems is a Fresnel lens composed of a Fresnel lens surface formed by dividing the lens surface of a convex lens into a large number of concentric circles and a rise surface forming a boundary between the Fresnel lens surfaces. In the lens sheet,
A light-shielding layer is formed on each of the rise surfaces, and the light-shielding layer is provided on a layer made of a cured product of the photocurable composition (A), and a cured product of the photocurable composition (A). The Fresnel lens sheet has a surface free energy of 25 mN / m or less on the Fresnel lens surface of the layer.

Further, according to the present invention, in a Fresnel lens sheet comprising a Fresnel lens surface formed by dividing the lens surface of a convex lens into a large number of concentric circles and a rise surface forming a boundary between the Fresnel lens surfaces, each rise surface is formed. A light-shielding layer is formed, and the light-shielding layer is provided on a layer made of a cured product of the photocurable composition (A).
However, 100 parts by mass of the photocurable resin composition (a) having a surface free energy of 30 mN / m or more and a surface free energy of 2
A Fresnel lens sheet, which is a composition comprising 0.01 to 10 parts by mass of a compound (b) having an amount of 5 mN / m or less.

Further, the present invention comprises a Fresnel lens surface formed by dividing the lens surface of a convex lens into a large number of concentric circles and a rise surface forming a boundary between the Fresnel lens surfaces, and a light shielding layer is formed on each rise surface. In the method for producing a Fresnel lens sheet, the rise surface and the lens surface have 100 parts by mass of the photocurable resin composition (a) having a surface free energy of 30 mN / m or more and a surface free energy of 25 mN / m or less. A step of applying a photocurable composition (A) consisting of 0.01 to 10 parts by mass of the compound (b) to form a layer consisting of the photocurable composition (A); the photocurable composition (A) The layer made of the photocurable composition (A) is irradiated with light in a state where the layer made of the compound (b) is in contact with a medium having a surface free energy lower than the surface free energy of the compound (b), and the Fresnel lens surface is exposed. Applied to Step of selectively curing only the photocurable composition (A); after the step, a color coating is applied on the layer made of the photocurable composition (A) to form a light-shielding layer on the rise surface. And a step of manufacturing the Fresnel lens sheet.

Further, according to the present invention, in the above-mentioned method for manufacturing a Fresnel lens sheet, the step of forming a light-shielding layer on the rise surface is a step of applying a coloring paint and the coloring paint applied to the Fresnel lens surface is repelled. A method for producing a Fresnel lens sheet, which comprises a step of drying the colored coating after a time for exposing the photocurable composition (A) layer on the Fresnel lens surface almost completely.

Further, in the present invention, in the above-mentioned method for manufacturing a Fresnel lens sheet, the step of forming a light-shielding layer on the rise surface includes a step of applying a colored paint, a step of drying the colored paint, and A method of manufacturing a Fresnel lens sheet, which includes a step of removing a coloring paint.

Further, in the present invention, in the above-mentioned method for producing a Fresnel lens sheet, the photocurable composition coated on the Fresnel lens surface by irradiating light from the surface opposite to the layer comprising the photocurable composition (A). Between the step of selectively curing only the composition (A) and the step of forming the light-shielding layer, the layer formed of the photocurable composition (A) is free from the surface of the photocurable resin composition (a). In the state of being in contact with a medium having a surface free energy higher than the energy, the photocurable composition (A) side is irradiated with light to cure the uncured portion of the layer made of the photocurable composition (A). It is a manufacturing method of a Fresnel lens sheet characterized by having a process.

The surface free energy value in the present invention is a value at a temperature of 20 ° C. and a relative humidity of 50% and is measured by the following method. There are various methods for measuring the surface free energy of a liquid, but in this specification, the value measured by the Wilhelmy method at a temperature of 20 ° C. and a relative humidity of 50% is used as the surface free energy. The measurement principle of the Wilhelmy method is as follows. As shown in FIG. 6, the plate 62 is hung on one side of the balance 61 so that one end of the plate 62 is immersed in the measurement liquid 63, and the other side is loaded with an appropriate load 64 to balance the balance 61. At this time, the plate 62 receives downward force from the measurement liquid 63 in addition to gravity and buoyancy, and in the equilibrium state, the following equation (1) is established.

[0011]

[Equation 1]   [Load 64] = [Gravity of plate 62]-[Buoyancy of plate 62] + [Force received from liquid surface] (1)

Since the force received from the liquid surface corresponds to the surface tension (= surface free energy of the liquid), the surface free energy of the liquid can be obtained by measuring the force received from the liquid surface. Although platinum, glass, or the like is used as the material of the plate 62, since the surface free energy is invariant, any material that is not corroded by the measurement liquid 63 may be used. In the measurement of the present specification, platinum is used as the plate 62. Is used.

The surface free energy of a solid cannot be measured directly, but can be determined using several kinds of liquids whose surface free energy is known. The droplet on the solid surface has a cross-sectional shape as shown in FIG. 7, and the contact angle in the figure is drawn to the liquid 72 at the intersection of the surface of the liquid 72 on the surface of the solid 71 and the surface of the solid 71. Tangent and solid 71
It is the angle between the surface and the side containing the liquid 72, and its value is θ
And At this time, the following equation (2) (Young's equation) is established due to the equilibrium condition at the intersection.

[0014]

(2) γ_S= γ_SL+ Γ_L・ Cos θ (2) Where γ_SIs the surface free energy of the solid, γ_LIs liquid
Surface free energy, γ _SLIs solid / liquid interface free energy
Represents Rugie.

The surface free energy γ is the dispersion force component γ^a,
Polar force component γ^bAnd hydrogen bond component γ ^cRepresented by the sum of
Body / liquid interface free energy γ_SLOf the following formula (3)
The assumption is said to hold.

[0016]

(3) γ _SL = γ _S + γ _L -2 (γ _S ^a γ _L ^a ) ^1/2 -2 (γ _S ^b γ _L ^b ) ^1/2 -2 (γ _S ^c γ _L ^c ) ^1/2 (3)

Therefore, the temperature of 20 ℃, relative humidity of 50%
3 types with different surface free energies
If the value θ of the contact angle of the above liquid on the solid surface is obtained,
Solving a ternary equation consisting of equations (2) and (3)
And γ_S ^a, Γ_S ^bAnd γ _S ^cCan be calculated and
Surface solid free energy γ_SIs required.

[0018]

FIG. 2 shows a schematic view of a Fresnel lens sheet 1 of the present invention. The Fresnel lens sheet 1 of the present invention is flat on the incident surface 2 side, and a Fresnel lens surface 4 and a rise surface 5 are formed on an exit surface 3 opposite to the incident surface 2. On the Fresnel lens surface 4 and the rise surface 5
A layer 8 made of a cured product of the photocurable composition (A) is provided on the upper side, and the photocurable composition (A) on the rise surface 5 is provided.
A light-shielding layer 9 is provided on the layer 8 made of the cured product. Further, the opening of the light shielding layer 9, that is, the Fresnel lens surface 4
The surface free energy of the layer 8 made of the cured product of the above photocurable composition (A) is 25 mN / m or less. The Fresnel lens sheet 1 can be easily molded by press molding of transparent thermoplastic resin or 2P molding method using photocurable resin.

In the present invention, as the photocurable composition (A), a composition comprising a photocurable resin composition (a) described later and a compound (b) having a low surface free energy described later is used. The surface free energy of the photocurable resin composition (a) used for solving the problems of the present application is 30 mN / m or more, preferably 40 mN / m or more. The surface free energy of the compound (b) is 25 mN / m or less, preferably 20 mN / m or less. Moreover, in order to solve the subject of this application, it is necessary to mix 0.01-10 mass parts of compounds (b) with respect to 100 mass parts of photocurable resin compositions (a), and compound (b) 0.1 It is preferable to mix 1 to 1 part by mass.

The present inventors cured the photocurable composition (A) comprising the above-mentioned photocurable resin composition (a) and compound (b) by irradiating it with light in a medium having a low surface free energy. By doing so, it was found that a surface having a low surface free energy can be obtained, and a surface having a high surface free energy can be obtained by curing by irradiating light in a medium having a high surface free energy. Also,
It was found that in the uncured state, the surface free energy of the photocurable composition (A) depends on the medium in contact with it. Examples of the light to be irradiated here include visible light and ultraviolet light, and ultraviolet light having high energy advantageous for curing the photocurable composition (A) is preferable.

The above surface modification phenomenon is presumed to be caused by the following mechanism. The interface between the composition comprising the photocurable resin composition (a) and the compound (b) and the medium is energetically stable when the difference between the surface free energies of the two becomes minimum. Since the compound (b) in the photosensitive composition (A) has a lower surface free energy than the photocurable resin composition (a), the compound (b) exists at the interface in the state of being in contact with a medium having a low surface free energy. By doing so, a stable state is achieved. On the other hand, when the photocurable resin composition (a) is present at the interface in the state of being in contact with a medium having a high surface free energy, the photocurable resin composition (a) is more energetically stable than the compound (b) is present at the interface. The compound (b) disappears from the interface. That is,
If the photocurable resin composition (a) is in an uncured state, phase transition will occur depending on the medium. Therefore,
Surfaces having different surface free energies can be obtained by irradiating the photocurable composition (A) with light in a medium having different surface free energies to fix the state at the interface.

Further, since the above phase transition is reversible when the photocurable composition (A) is in an uncured state, the photocurable composition (A) is divided into a region having a high surface free energy and a region having a low surface free energy. In the case of surface modification, it is possible to selectively modify the surface free energy to a high area and then the remaining surface to a low surface free energy. It is also possible to modify it to a region having a low surface energy and then modifying the rest to a region having a high surface free energy.

Since the main component of the photocurable composition (A) is the photocurable resin composition (a), it must be irradiated with a certain amount of light or more (hereinafter referred to as the critical exposure amount). The curing of the photocurable composition (A) does not proceed. Therefore,
When the photocurable composition (A) is irradiated with light of a critical exposure amount or less, the surface modification phenomenon does not occur.

Further, since the photocurable composition (A) can be treated as a paint, it is suitable for surface modification of an article having an uneven surface such as a Fresnel lens sheet.

As a medium having high surface free energy,
Water; examples include higher alcohols such as glycerin. Examples of the medium having a low surface free energy include the atmosphere; inert gases such as helium gas and argon gas; however, the medium is not limited to these. Particularly, in the present invention, it is possible to use water as a medium having a high surface free energy and atmospheric air as a medium having a low surface free energy. Therefore, the present invention is significant in terms of cost and environment.

The compound (b) having a surface free energy of 25 mN / m or less used in the present invention is a silicone oil such as polydimethylsiloxane, and the side chain or terminal of the silicone oil is modified with an amino group, an epoxy group or the like. Modified silicone oil, tetramethoxysilane, phenyltrimethoxysilane, and other alkoxysilanes and other silicon-containing (polymer) compounds; fluoroalkylsilanes, fluoroalkyl groups and other fluorine-containing polymer compounds, etc. Molecule) compound; a block copolymer, a graft copolymer, a random copolymer, etc. containing the above compound as a component can be mentioned, but the compound is not limited to the above compound.

The photocurable resin composition (a) used in the present invention comprises a polymerizable monomer and, if desired, other components such as a photopolymerization initiator (provided that the surface free energy is 25 mN / Compounds (b) that are less than or equal to m are included. The polymerizable monomer is a photopolymerizable compound, has a surface free energy of 30 mN / m or more, and at least in the molecule.
Although photopolymerizable ethylenically unsaturated compounds having one ethylenic double bond can generally be used,
If necessary, a photocationically polymerizable epoxy-based or oxetane-based compound or the like may be further added.

Examples of the photopolymerizable ethylenically unsaturated compound that can be used in the practice of the present invention include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl ( (Meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate and the like. Monofunctional (meth) acrylate-based monomer; N-vinylpyrrolidone, N-vinylimidazole, N-vinylcaprolactam, styrene, α-methylstyrene, vinyltoluene, allyl acetate, vinyl acetate, vinyl propionate,
Vinyl monomers such as vinyl benzoate, and 1,4
-Butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, etc. Bifunctional (meth) acrylate monomer; trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate. , Tri (meth) acryloyl cyanurate, tri (meth) acryloyl isocyanurate, triallyl cyanurate, triallyl isocyanurate, 1,3,5-tri (meth) acrylo Such as polyfunctional (meth) acrylate monomers such as Ruhekisahidoro -s- hydrazine and the like, one or more of these are used. In the names of the above compounds, "(meth) acrylic acid" is a generic term for "acrylic acid" and "methacrylic acid", "(meth) acrylate" is a generic term for "acrylate" and "methacrylate", and “(Meth) acryloyl” is a general term for “acryloyl” and “methacryloyl”.

If desired, a photopolymerization initiator may be added. Specific examples of the photopolymerization initiator include 2,2-dimethoxy-2-phenylacetone, acetophenone, benzophenone, xanthfluorenone, benzaldehyde, anthraquinone, 1- (4-isopropylphenyl).
2-hydroxy-2-methylpropan-1-one, 1
-Hydroxy-cyclohexyl-phenyl-ketone,
2,4-diethylthioxanthone, camphorquinone,
2-Methyl-1- [4- (methylthio) phenyl] -2-
Examples thereof include morpholinopropan-1-one.

In some cases, as a diluent for the photocurable composition (A), acetone, ethanol, methanol, isopropyl alcohol, hexane, ethyl acetate, chloroform, carbon tetrachloride, tetrahydrofuran, tetrahydrofuran,
An organic solvent such as diethyl ether, methyl ethyl ketone, toluene or benzene may be used.

The Fresnel lens sheet of the present invention has a structure as shown in FIG. 2 and is applied to a transmission screen or the like. The Fresnel lens sheet can be manufactured by the method described below. First, as shown in FIG. 3, the photocurable composition (A) described above is applied to the exit surface 3 of the Fresnel lens sheet 1 by spin coating, dip coating, or the like, and the surface free energy is higher than that of the compound (b). Light is emitted from the incident surface 2 side in a state of being in contact with a low medium (for example, the atmosphere). The light emitted at this time is preferably light emitted from a light source that can be regarded as the point light source 10. By doing so, it becomes possible to irradiate the Fresnel lens sheet with light that is substantially equivalent to the projection light of the image when used in a projection television. Therefore, most of the light is applied to the Fresnel lens surface 4, and only a very small amount of light is applied to the rise surface 5. Therefore, by adjusting the light irradiation amount, the Fresnel lens surface 4 is irradiated with the light. It is possible to easily make the amount to be the critical exposure amount or more and to make the irradiation amount of the light on the rise surface 5 less than the critical exposure amount. That is, only the photocurable composition (A) on the Fresnel lens surface 4 is selectively cured (shown by a dotted line in FIG. 3), and the photocurable composition (A) on the rise surface 5 is not yet cured. Hardened state.

Next, as shown in FIG. 4, the Fresnel lens sheet 1 obtained is brought into contact with a medium (for example, water) having a surface free energy higher than that of the photocurable resin composition (a), and the Fresnel lens sheet 1 is brought into contact therewith. By irradiating light from the exit surface 3 side of the sheet 1, the uncured photocurable composition (A)
Only cures (indicated by the gray line in Figure 4).

By the steps described above, the Fresnel lens surface 4 and the rise surface 5 on the exit surface 3 side of the Fresnel lens sheet 1 can be surface-modified into a region having a low surface free energy and a region having a high surface free energy, respectively. . At this time, the surface free energy of the rise surface 5 is transferred to the Fresnel lens surface 4
The surface free energy is preferably 5 mN / m or more from the viewpoint of the formability of the light shielding layer 9.

The wettability of various liquids is different on the surface having different surface free energy, and in the case of commonly used solvents and paints, the surface having high surface free energy is more easily wetted by the liquid than the surface having low surface free energy. . Therefore, the risen surface 5 of the surface-modified Fresnel lens sheet 1 is more easily wetted by various liquids than the Fresnel lens surface 4. By utilizing this property, the surface-modified Fresnel lens sheet 1 is coated with a coloring paint, whereby the light-shielding layer 9 to which the coloring paint is attached can be formed only on the rise surface 5.

The exit surface 3 of the Fresnel lens sheet 1
A medium in which the above-mentioned photocurable composition (A) is applied to the medium and the surface free energy of which is lower than that of the compound (b) from the incident surface 2 side.
After irradiating light in a state of contacting with (for example, the atmosphere) to selectively cure only the photocurable composition (A) on the Fresnel lens surface 4, a coloring paint is applied to form the light-shielding layer 9. Is also good.
It is also possible to cure the colored paint after applying the colored paint, and then irradiate light from the colored paint side to cure the uncured photocurable composition (A).

In the above case, the colored coating material applied on the layer 8 made of the photocurable composition (A) whose surface free energy of the Fresnel lens surface 4 is low (25 mN / m or less) is repelled. And a layer 8 comprising the photocurable composition (A)
After almost completely exposed, the light-shielding layer 9 can be formed by curing the colored paint. Here, the state in which the layer 8 made of the photocurable composition (A) is almost completely exposed is such that the objective of the Fresnel lens sheet 1 obtained is sufficiently achieved. ) Layer 8
This is the state in which the colored paint has been removed from above. Also,
The layer 8 made of the photocurable composition (A) in the uncured state, which is below the light shielding layer 9, is cured at the same time as or after the curing of the colored coating material.

When using a highly viscous colored paint,
Although the repelling of the colored paint on the Fresnel lens surface 4 may be used as described above, it takes time to completely repel the colored paint having a high viscosity because of its low fluidity. In this case, as shown in FIG. 5 (a), after applying the high-viscosity colored coating material 13 to the cured surface of the layer 8 made of the photocurable composition (A),
After adhering the base material 12 having good adhesion to the colored paint 13 to the colored paint, the colored paint 13 is cured to remove only the colored paint 13 on the Fresnel lens surface 4 as shown in FIG. 5 (b). The light shielding layer 9 can be formed by removing.
Alternatively, only the colored paint 13 on the Fresnel lens surface 4 may be removed by a physical method such as air flow, water flow, or blast. In these cases, the step of removing the colored paint 13 is not omitted, but the colored paint 13 on the Fresnel lens surface 4 is not omitted.
Due to its low adhesion strength, the colored paint 13
Can be easily removed and workability can be improved.

Examples of the colored coating material used in the present invention include gravure ink, flexographic ink, screen ink, offset ink and letterpress ink. From the viewpoint of improving the contrast, the colored paint is preferably a black paint. The colored paint is at least 1 selected from fats and oils components such as dry oils and non-drying oils; resin components such as synthetic resins and natural resins; solvent components such as hydrocarbons, ketones and alcohols.
Or a mixture of a photopolymerizable monomer and a photopolymerization initiator, and a colorant. The colorant may be a black dye such as aniline black; carbon black, acetylene black, lamp black, mineral black, or the like. Black pigments and the like are included.

[0039]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 A Fresnel lens sheet was obtained by a 2P molding method using a Fresnel lens molding die in which a reverse shape of a Fresnel lens having a pitch of 0.1 mm and a lens height of 0.1 mm was formed. At this time, a 0.25 mm thick polyethylene terephthalate film (Cosmo Shine A4300) manufactured by Toyobo Co., Ltd. was used as the base film, and an acrylate-based UV curable resin (Aronix) manufactured by Toagosei Co., Ltd. was used as the 2P molding resin.

100 parts by mass of pentaerythritol triacrylate (Aronix M-305) manufactured by Toagosei Co., Ltd., 1-hydroxy-cyclohexyl-phenyl-ketone (IRGACURE 18 manufactured by Ciba Specialty Chemicals Co., Ltd.)
4) Photocurable resin composition (a) mixed at a ratio of 3 parts by mass
Was prepared. The surface free energy of the photocurable resin composition (a) was measured by the Wilhelmy method.
It was 6.8 mN / m. Fluorine-based block copolymer (Modiper F200) manufactured by NOF CORPORATION whose surface free energy measured by the Wilhelmy method is 18.6 mN / m as the compound (b) having a low surface free energy in the photocurable resin composition (a). 1 part by weight of photocurable composition (A)
And Since the photocurable composition (A) has a high viscosity and is difficult to handle in view of coatability, it was diluted with methyl ethyl ketone so that the concentration of the photocurable composition (A) was 10 vol%. The curable mixture was applied to a PET film of 125 μm in thickness by Toyobo Co., Ltd. with a bar coater for 10 μm, and then methyl ethyl ketone was volatilized to uniformly coat the curable mixture with a thickness of 1 μm on the PET film. An engineered film could be obtained. The obtained film is cured by irradiating it with ultraviolet rays in the air and water,
When the contact angle with various solvents was measured with a contact angle meter manufactured by Kyowa Interface Science Co., Ltd. and the surface free energy was calculated, it was 20.3 mN / m for curing in air and 52.3 mN / m for curing in water. The solvents used were water, ethylene glycol, dipropylene glycol and toluene.

The photocurable composition (A) diluted with methyl ethyl ketone was applied to the exit surface of the Fresnel lens sheet by a spin coater to a thickness of 0.03 mm, and the temperature was set to 80 ° C.
The methyl ethyl ketone was volatilized by drying for 5 minutes, and the coating thickness of the photocurable composition (A) was adjusted to 0.003 mm. The Fresnel lens sheet was irradiated with ultraviolet light from the incident surface side in the atmosphere by a high pressure mercury lamp which can be regarded as a point light source.

A UV-curable ink for screen printing (UVPAL911) manufactured by Teikoku Ink Co., Ltd. was applied to the exit surface side of the obtained Fresnel lens sheet by a spin coater to a thickness of 0.01 mm.
Coated UV for screen printing on Fresnel lens surface
After the curable ink is repelled to expose the layer made of the photocurable composition (A) and the UV curable ink for screen printing adheres only to the rise surface, the screen printing When the UV curable ink was dried with a high pressure mercury lamp, a light shielding layer could be formed only on the rise surface. When the Fresnel lens sheet obtained was installed in a projection television, it was possible to observe a good image with little noise light.

(Example 2) Pitch 0.1 mm, lens height 0.1
A Fresnel lens sheet was obtained by a 2P molding method using a Fresnel lens molding die in which an inverse shape of a Fresnel lens having a size of mm was formed. At this time, a 0.25 mm thick polyethylene terephthalate film (Cosmo Shine A4300) manufactured by Toyobo Co., Ltd. was used as the base film, and an acrylate-based UV curable resin (Aronix) manufactured by Toagosei Co., Ltd. was used as the 2P molding resin.

50 parts by mass of dipentaerythritol hexaacrylate (KAYARAD DPHA) manufactured by Nippon Kayaku Co., Ltd., 50 parts by mass of isocyanuric acid ethylene oxide modified triacrylate (Aronix M-315) manufactured by Toagosei Co., Ltd., Nippon Kayaku Co., Ltd. 1 part by mass of 2,4-diethylthioxanthone manufactured by Ciba Specialty Chemicals Co., Ltd. 2-methyl-1- [4- (methylthio) phenyl] -2
-Morpholinopropan-1-one (Irgacure 907) 3
A photocurable resin composition (a) was prepared by mixing in a proportion of parts by mass. When the surface free energy of the photocurable resin composition (a) was measured by the Wilhelmy method, it was 42.6 mN.
It was / m. Amino-modified silicone oil (KF85 manufactured by Shin-Etsu Chemical Co., Ltd.) having a surface free energy measured by the Wilhelmy method of 20.7 mN / m as a compound (b) having a low surface free energy in the photocurable resin composition (a).
0.5 part by mass of 7) was added to obtain a photocurable composition (A). Since the photocurable composition (A) has a high viscosity and is difficult to handle in view of coatability, it was diluted with toluene so that the concentration of the photocurable composition (A) was 5 vol%. The surface free energies of the photocurable resin composition (A) when cured in the air and when cured in water were calculated in the same manner as in Example 1 to be 21.5 mN / m and 40.2 mN, respectively.
It was / m.

The photocurable composition (A) diluted with toluene was applied to the exit surface of the Fresnel lens sheet with a spin coater to a thickness of 0.02 mm, and the toluene was volatilized by drying at 120 ° C. for 5 minutes. The coating thickness of the photocurable composition (A) was set to 0.001 mm.

The Fresnel lens sheet was irradiated with ultraviolet light in a nitrogen atmosphere from the incident surface side by a high pressure mercury lamp which can be regarded as a point light source. Further, while the Fresnel lens sheet was immersed in water, ultraviolet light was irradiated from the emission surface side of the Fresnel lens sheet by a high pressure mercury lamp.

A UV curable ink for PS plate offset printing (FD Carton ink) manufactured by Toyo Ink Mfg. Co., Ltd. was applied to the emission surface side of the obtained Fresnel lens sheet with a spin coater to a thickness of 0.003 mm. The UV curable ink for screen printing is repelled on the Fresnel lens surface to expose the layer made of the photocurable composition (A), and the UV curable ink for screen printing is adhered only to the rise surface. After a lapse of time, the UV curable ink for screen printing was dried by a high pressure mercury lamp, and a light shielding layer could be formed only on the rise surface. When the Fresnel lens sheet obtained was installed in a projection television, it was possible to observe a good image with little noise light.

[0048]

According to the present invention, a light-shielding layer can be formed only on the rise surface of a Fresnel lens sheet used in a projection television, etc. By using the Fresnel lens sheet obtained, stray light can be reduced. It is possible to observe an image with improved contrast.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional Fresnel lens sheet and its function.

FIG. 2 is a diagram showing a Fresnel lens sheet of the present invention.

FIG. 3 is a diagram showing one of the embodiments of the present invention.

FIG. 4 is a diagram showing one of the embodiments of the present invention.

FIG. 5 is a diagram showing one of the embodiments of the present invention.

FIG. 6 is a diagram illustrating a Wilhelmy method.

FIG. 7 is a diagram illustrating a solid surface free energy measuring method.

[Explanation of symbols]

1. Fresnel lens sheet 2. Plane of incidence 3. Exit surface 4. Fresnel lens surface 5. Rise surface 6. Light engine 7. Image light 8. Layer composed of photocurable composition (A) 9. Shading layer 10. Ultraviolet light that can be regarded as a point light source 11. Ultraviolet light 12. Base film 13. Colored paint

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junichi Tanaka             41 Miyukigaoka, Tsukuba City, Ibaraki Prefecture Co., Ltd.             Kuraray (72) Inventor Tatsufumi Watanabe             41 Miyukigaoka, Tsukuba City, Ibaraki Prefecture Co., Ltd.             Kuraray F-term (reference) 2H021 BA22 BA26 BA32                 2H088 EA12 HA10 HA14 HA27 MA01                       MA02 MA03 MA04                 2H091 FA27X FA34X FB02 FC17                       FD06 LA03 LA16 LA17 MA07

Claims (10)

[Claims] 1. A Fresnel lens sheet comprising a Fresnel lens surface obtained by dividing a lens surface of a convex lens into a large number of concentric circles and a rise surface that forms a boundary between the Fresnel lens surfaces, and a light shielding layer is formed on each rise surface. The light-shielding layer is provided on a layer made of a cured product of the photocurable composition (A), and the surface of the layer made of the cured product of the photocurable composition (A) on the Fresnel lens surface. Free energy
Fresnel lens sheet characterized by being 25 mN / m or less. 2. A Fresnel lens sheet comprising a Fresnel lens surface formed by dividing a lens surface of a convex lens into a large number of concentric circles and a rise surface that forms a boundary between the Fresnel lens surfaces, and a light shielding layer is formed on each rise surface. The light-shielding layer is provided on a layer made of a cured product of the photocurable composition (A), and the photocurable composition (A) has a surface free energy of 30 mN / m or more. Photocurable resin composition (a)
A Fresnel lens sheet, which is a composition comprising 100 parts by mass and 0.01 to 10 parts by mass of a compound (b) having a surface free energy of 25 mN / m or less. 3. A Fresnel lens comprising a Fresnel lens surface formed by dividing the lens surface of a convex lens into a large number of concentric circles and a rise surface forming a boundary between the Fresnel lens surfaces, and a light-shielding layer formed on each rise surface. In the method for producing a sheet, the photocurable resin composition (a) 10 having surface free energy of 30 mN / m or more on the rise surface and the Fresnel lens surface.
A layer comprising the photocurable composition (A), which is obtained by applying the photocurable composition (A) consisting of 0 to 10 parts by mass and the compound (b) having a surface free energy of 25 mN / m or less to 0.01 to 10 parts by mass. A step of forming the photocurable composition (A) in a state where the layer comprising the photocurable composition (A) is in contact with a medium having a surface free energy lower than the surface free energy of the compound (b). Irradiating light from the opposite surface of the layer to selectively cure only the photocurable composition (A) applied to the Fresnel lens surface; from the photocurable composition (A) after the step A step of applying a colored coating material on the layer to form a light-shielding layer on the rise surface, the method for producing a Fresnel lens sheet. 4. The step of forming a light shielding layer on the rise surface,
The coloring is applied after the step of applying the coloring paint and the time for the photo-curable composition (A) layer on the Fresnel lens surface to be almost completely exposed by repelling the coloring paint applied to the Fresnel lens surface. The method for manufacturing a Fresnel lens sheet according to claim 3, further comprising a step of drying the paint. 5. The step of forming a light-shielding layer on the rise surface,
The method for producing a Fresnel lens sheet according to claim 3, which includes a step of applying a coloring paint, a step of drying the coloring paint, and a step of removing the coloring paint on the Fresnel lens surface. 6. A step of irradiating light from the side opposite to the layer comprising the photocurable composition (A) to selectively cure only the photocurable composition (A) applied to the Fresnel lens surface. During the step of forming the light-shielding layer, the layer made of the photocurable composition (A) is in contact with a medium having a surface free energy higher than that of the photocurable resin composition (a). 6. The method according to claim 3, further comprising the step of irradiating light from the photocurable composition (A) side to cure an uncured portion of a layer made of the photocurable composition (A).
Item 8. A method for manufacturing a Fresnel lens sheet according to item. 7. The method for producing a Fresnel lens sheet according to claim 3, wherein the medium having a surface free energy lower than that of the compound (b) is air. 8. The method for producing a Fresnel lens sheet according to claim 6, wherein the medium having a higher surface free energy than that of the photocurable resin composition (a) is water. 9. The method for producing a Fresnel lens sheet according to claim 3, wherein the light emitted from the surface opposite to the layer made of the photocurable composition (A) is a substantially point light source. 10. A Fresnel lens sheet is a Fresnel lens sheet for a transmissive screen used in an image display device for projecting and displaying an image from the back side, and the Fresnel lens sheet is provided from the side opposite to the layer comprising the photocurable composition (A). The method for manufacturing a Fresnel lens sheet according to claim 3, wherein the traveling direction of the irradiated light is substantially equivalent to the projected light of the image.