JP2008247946A - Photo-setting composition and light-controlling membrane produced by curing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo-setting composition suitable as a raw material for a light-controlling membrane having a wide light-scattering angle range and to provide a light-controlling membrane having a wide light-scattering angle range and produced by curing the photo-setting composition. <P>SOLUTION: The photo-setting composition is produced by using a plurality of compounds having a polymerizable carbon-carbon double bond in the molecule as the polymerizable compounds and using a compound having a number-average molecular weight of 20,000-100,000 as at least one kind of the compounds. The light-controlling membrane is produced by curing a membrane of the photo-setting composition by light irradiation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photocurable composition suitable as a raw material for a light control film. The present invention also relates to a light control film obtained by curing the photocurable composition.

  The light control film (for example, see Patent Documents 1 to 8) is attached to a window glass or a touch panel of a cash dispenser, for example, in order to protect privacy by taking advantage of the unique property that the haze value has an angle dependency. It is used as a viewing angle control film, or attached to a flat panel display or the like and used as a viewing angle widening film. It has also been proposed to apply a light control film to a projection screen (see, for example, Patent Documents 9 to 15).

  The angle dependency of the haze value in the light control film is measured as follows. That is, as shown in FIG. 1, when the angle θ of the incident light to the test piece 1 of the light control film is changed between 0 to 180 ° and the haze value is measured for each angle, Incident light is scattered to exhibit a high haze value, and in other angle ranges, the incident light basically passes straight and exhibits a low haze value. And the angle range which shows this high fog value shall be called a light scattering angle area | region in this specification.

  The angle θ is a value in which the direction parallel to the surface of the test piece 1 is 0 ° and the normal direction of the test piece 1 is 90 °, and the rotation of the test piece 1 has an angle dependency of the haze value. Perform in the maximum direction. A and B in the figure are the left figure (when light enters the test piece 1 from the vertical direction: θ = 90 °) and the right figure (when light enters the test piece 1 from an oblique direction) Thus, the reference numerals are attached so that the corresponding portions of the test piece 1 can be seen.

  The haze value is a value obtained by the following equation by measuring the total light transmittance and diffuse transmittance of the light control film using an integrating sphere light transmittance measuring device.

  In order to obtain such a light control film, for example, Patent Documents 1 to 5 and 8 each have at least two kinds of polymerizable carbon-carbon double bonds in the molecule and different refractive indexes. It is disclosed that a photocurable composition containing a compound is used as a raw material, and a film of this composition is irradiated with light from a predetermined direction to be cured. Further, as the above compound, various oligomers or monomers are used, and specifically, those obtained by reaction of polyalkylene glycol having a molecular weight of several thousand, diisocyanate, and hydroxy group-containing acrylate are used. .

JP 63-309902 A (Japanese Patent Publication No. 7-58361) Japanese Patent Application Laid-Open No. 64-40905 (Japanese Patent No. 2547419) Japanese Patent Application Laid-Open No. 64-77001 (Japanese Patent No. 2691543) Japanese Patent Laid-Open No. 2-67501 (Japanese Patent No. 2702521) Japanese Laid-Open Patent Publication No. 2-54201 (Patent No. 2782200) Japanese Patent Laid-Open No. 3-107901 (Japanese Patent No. 2822065) Japanese Patent Laid-Open No. 3-107902 (Japanese Patent No. 2782250) Japanese Patent Laid-Open No. 6-11606 (Japanese Patent No. 3211381) JP-A-3-127039 Japanese Patent Laid-Open No. 3-127042 (Japanese Patent No. 2838295) Japanese Patent Laid-Open No. 3-200909 JP-A-4-77728 International Publication No. 2004/034145 Pamphlet JP 2005-316354 A JP 2005-331631 A

  In order to enhance the viewing angle control effect and the viewing angle expansion effect, a light control film is often required to have a wide light scattering angle range. There was a problem that it was difficult to obtain a film easily. Accordingly, an object of the present invention is to provide a photocurable composition suitable as a raw material for a light control film having a wide light scattering angle range. And it is providing the light control film | membrane with a wide light-scattering angle area | region by hardening | curing this photocurable composition.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by adding a higher molecular weight oligomer to the above-mentioned photocurable composition, and have completed the present invention. That is, the present invention contains a plurality of compounds having a polymerizable carbon-carbon double bond in the molecule, and at least one of the compounds is a compound having a number average molecular weight of 20,000 to 100,000. The photocurable composition characterized by the above is provided. Moreover, according to this invention, the light control film | membrane formed by irradiating light and hardening | curing to the film | membrane of this photocurable composition is also provided.

  By using the photocurable composition of the present invention, a light control film having a wide light scattering angle range can be easily obtained.

  The photocurable composition of the present invention contains a plurality of compounds having at least one polymerizable carbon-carbon double bond in the molecule (hereinafter sometimes simply referred to as a polymerizable compound). This polymerizable compound has a polymerizable carbon-carbon double bond in the molecule, for example, acryloyl group, methacryloyl group, vinyl group, allyl group, arylidene group, styryl group, acryloylamino group, crotonyl group, cinnamoyl group, It has a conjugated polyene structure such as a butadiene structure, a cycloolefin ring structure such as a cyclopentene ring structure, and preferably has an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, an arylidene group, and more preferably And an acryloyl group.

  In the present invention, a compound having a number average molecular weight of 20,000 to 100,000 is used as at least one polymerizable compound. Thus, the light control film | membrane with a wide light-scattering angle range can be obtained by mix | blending a predetermined high molecular weight polymeric compound with a photocurable composition. In addition, the haze value in the light scattering angle region can be increased.

  The above high molecular weight polymerizable compounds include various oligomers such as polyester acrylate, polyol polyacrylate, modified polyol polyacrylate, isocyanuric acid skeleton polyacrylate, melamine acrylate, hydantoin skeleton polyacrylate, polybutadiene acrylate, epoxy acrylate, urethane. It can be selected from acrylates and methacrylates corresponding to these polyfunctional acrylates.

  As the high molecular weight polymerizable compound, those having a plurality of polymerizable carbon-carbon double bonds in the molecule are preferably used. In addition, urethane (meth) acrylate is preferably used as the type of compound.

  Urethane (meth) acrylate is a polyol which is a compound having a plurality of hydroxy groups in the molecule, a polyisocyanate which is a compound having a plurality of isocyanato groups in the molecule, a hydroxy group and (meth) acryloyl in the molecule. It is preferable to be obtained by reacting a hydroxy group-containing (meth) acrylate which is a compound having an oxy group. In particular, urethane (meth) acrylate having a polyether skeleton obtained by using polyalkylene glycol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol as the polyol is preferable.

  In the present specification, (meth) acrylate means acrylate or methacrylate, and (meth) acryloyloxy group means acryloyloxy group or methacryloyloxy group.

  Examples of the polymerizable compound that can be used in combination with the above high molecular weight polymerizable compound include various monomers such as tetrahydrofurfuryl acrylate, ethyl carbitol acrylate, dicyclopentenyloxyethyl acrylate, phenyl carbitol acrylate, and nonylphenoxyethyl. Acrylate, 2-hydroxy-3-phenoxypropyl acrylate, ω-hydroxyhexanoyloxyethyl acrylate, acryloyloxyethyl succinate, acryloyloxyethyl phthalate, isobornyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, 2,4,6 -Tribromophenyl acrylate, 2,4,6-tribromophenoxyethyl acrylate, 2,2,3,3-tetrafluoropropylene Acrylates or methacrylates corresponding to these monofunctional acrylates, furthermore, N- vinylpyrrolidone, triallyl isocyanurate, diethylene glycol diallyl carbonate, such as di-arylidene pentaerythritol.

  In the photocurable composition of the present invention, as described above, a plurality of polymerizable compounds are used, and at least one of them is a compound having a number average molecular weight of 20,000 to 100,000. Those with different refractive indices are selected. In this way, a film of a composition containing at least two types of polymerizable compounds having different refractive indexes is cured by irradiating light from a predetermined direction to form a light scattering region, that is, a light scattering angle region. Is done. This composition expresses the angle dependency of the haze value due to the solubility and refractive index difference between a plurality of composing compounds, and has a large refractive index difference in a combination with poor compatibility. When the reaction rates are different, the degree of light scattering, that is, the haze value increases. This refractive index difference is preferably 0.01 or more, and more preferably 0.02 or more. Moreover, the usage-amount of each compound is 10-900 weight part of compounds other than this normally on the basis of 100 weight part of arbitrary 1 types of compounds. In addition, when using 3 or more types of polymeric compounds, the refractive index of all the compounds does not necessarily need to mutually differ, and the refractive index of any two compounds should just differ from each other.

  The photocurable composition of the present invention may contain a photopolymerization initiator, and those used in ordinary photopolymerization, such as benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone, benzoin ethyl ether , Diethoxyacetophenone, benzyldimethyl ketal, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one Etc. can be used.

  When the photopolymerization initiator is used, the amount of the photopolymerization initiator used is usually 0.01 to 10 parts by weight, preferably 0.02 to 5 parts by weight, more preferably 100 parts by weight of the total amount of the polymerizable compound. Is 0.05 to 3 parts by weight. The greater the amount used, the wider the light scattering angle range of the resulting light control film, and the curing of the photocurable composition tends to be accelerated. , Resistance to physical impact, organic solvent, etc. tends to be low. Two or more photopolymerization initiators can be used as necessary.

  Further, in the photocurable composition of the present invention, if necessary, components other than the polymerizable compound and the photopolymerization initiator, for example, polystyrene, polymethyl methacrylate, polyethylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, nylon Polymers such as toluene, n-hexane, cyclohexane, methyl alcohol, ethyl alcohol, acetone, methyl ethyl ketone, tetrahydrofuran, ethyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dimethylformamide, dimethylacetamide, acetonitrile and other organic solvents, Additives such as organohalogen compounds, organosilicon compounds, plasticizers, and stabilizers may be included.

  The film of the photocurable composition of the present invention described above is cured by irradiating light from a predetermined direction. Specifically, the composition is applied on a substrate or encapsulated in a cell. In this way, a light-scattering film that scatters incident light in a wide angle range and basically passes straight in other angle ranges, that is, a light control film, is cured by irradiating light from a rod-shaped light source. can get. The light used for curing may have any wavelength as long as it cures the composition, and for example, visible light, ultraviolet light, and the like are often used. Ultraviolet rays are emitted from mercury lamps, metal halide lamps, etc. When a rod-shaped lamp is used, the generated photocured film can be adjusted with respect to the major axis and minor axis direction of the light source by adjusting the irradiation conditions. Anisotropy is exhibited, and light of a specific angle is scattered only when the light source is rotated about the major axis direction of the light source.

  At the time of photocuring, a light scattering angle region is developed around the light irradiation direction. For example, if light is irradiated almost perpendicularly to the film surface formed from the photocurable composition, a light scattering angle region appears around the normal direction, that is, the normal direction, and the normal direction is When light is irradiated from an oblique direction inclined by a predetermined angle, a light scattering angle region is developed around the inclined direction.

  An example in the case of irradiating light from the perpendicular direction to the photocurable composition film will be described based on FIG. (A) of FIG. 2 is a side view schematically showing an example of an apparatus that can be used when light is irradiated from the vertical direction to the photocurable composition film, and (B) shows the apparatus. FIG. This apparatus includes a conveyor 2 that moves in the direction of a hollow arrow, a light shielding plate 3 that is disposed above the conveyor 2 and has slits 4 formed in the width direction of the conveyor, and a bar-like shape that is further spaced apart by a predetermined distance. It comprises a light source lamp 5. The slit 4 is formed so as to coincide with the length direction of the light source lamp 5. Then, the substrate 6 on which the photocurable composition film is formed is placed on the conveyor 2, and the light from the light source lamp 5 is passed through the slit 4 of the light shielding plate 3 while moving at a constant speed. When the material film is irradiated, light in the vertical direction is centered on the composition film, and therefore phases having different refractive indexes are alternately formed in the vertical direction (normal direction), and light is centered on that direction. A scattering angle region is developed. By controlling the width of the slit 4, the distance from the rod-shaped light source lamp 5 to the photocurable composition film, the thickness of the photocurable composition film, the amount of irradiation light, the wavelength of irradiation light, etc., the haze value increases. The angle range, that is, the light scattering angle region can be further widened.

  Next, the example in the case of irradiating light with respect to a photocurable composition film | membrane from an oblique direction is demonstrated based on FIG. FIG. 3A is a side view schematically showing an example of an apparatus that can be used when light is applied to the photocurable composition film from an oblique direction, and FIG. FIG. This apparatus is composed of a conveyor 2 that moves in the direction of a white arrow, a light-shielding plate 3 that covers a predetermined position above it, and a bar-like light source lamp 5 that is arranged above that by a predetermined distance. The light-shielding plate 3 in this example slightly protrudes from the position immediately below the light source lamp 5 toward the traveling direction side of the conveyor 2. Then, if the substrate 6 on which the photocurable composition film is formed is placed on the conveyor 2 and is moved at a constant speed, the light from the light source lamp 5 is irradiated toward the light shielding plate 3 side. Since the light having the angle α is centered on the photocurable composition film, phases having different refractive indexes are alternately formed in the light incident direction, and a light scattering angle region is developed around the direction. become. By changing the light irradiation angle α, the center value of the light scattering angle region can be changed, and the distance from the light source lamp 5 to the photocurable composition film, the thickness of the photocurable composition film, By controlling the irradiation light amount, the wavelength of the irradiation light, etc., the angle range where the haze value increases, that is, the light scattering angle region can be further widened.

  In the light control film of the present invention thus obtained, the width of the light scattering angle region exhibiting a haze value of 60% or more is preferably 30 ° or more, more preferably 35 ° or more. However, if the width of the light scattering angle region is too large, it is difficult to use as a viewing angle control film, a viewing angle widening film, a projection screen, or a member thereof.

  The light control film of the present invention has a wide light scattering angle range and itself has excellent light diffusion performance, but in order to further widen the light scattering angle range or to improve the uniformity of light scattering. Two or more sheets can be laminated and used. The light control film can be laminated by, for example, cutting the light control film into an appropriate size and pasting the sheets with a single sheet, or simultaneously bonding two or more individually prepared light control films. You may carry out by supplying to an apparatus and bonding continuously. At that time, in order to make the bonding between the light control films stronger, it is also possible to insert a medium such as an adhesive between the films.

  The light control film of the present invention can be used by being attached to the surface of a transparent base material such as transparent glass or transparent plastic, or being inserted between a plurality of base materials. In particular, when applied to a projection screen, a light control film is laminated on a polished glass or a light diffusing plate with a relatively small amount of filler added and reduced light diffusibility to increase total light transmittance. You can also. The substrate used when forming the light control film can be used as the above-described transparent or light diffusing substrate as it is.

  Further, the light control film of the present invention may be used as a flat plate, or the outermost layer may be formed into a lens shape such as a lenticular lens. As a method of forming a curved lens surface, there is a method of forming a light control film having a lens curved surface in addition to a method of laminating a light control film on a substrate having a curved lens surface. When the latter method is employed, for example, a mold having a curved lens surface may be used, and a photocurable composition may be applied thereto and further irradiated with light so that the cured film has a curved lens surface.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited by these examples. In the examples, the part representing the content or amount used is based on weight.

As urethane acrylate, the following were used.
Urethane acrylate (1): Polyether urethane acrylate obtained by reaction of polypropylene glycol having an average molecular weight of about 10,000 with 2 mol of isophorone diisocyanate and 2 mol of 2-hydroxyethyl acrylate per mol of the polypropylene glycol ( Number average molecular weight 22,000).
Urethane acrylate (2): Polyether urethane acrylate obtained by reaction of polypropylene glycol having an average molecular weight of about 15,000 with 2 mol of isophorone diisocyanate and 2 mol of 2-hydroxyethyl acrylate per mol of the polypropylene glycol ( Number average molecular weight 27,400).
Urethane acrylate (3): polypropylene glycol having an average molecular weight of about 3,000, 0.3 mol of toluene diisocyanate, 2.7 mol of hexamethylene diisocyanate and 2 mol of 2-hydroxyethyl acrylate per 2 mol of the polypropylene glycol Polyether urethane acrylate obtained by the reaction of (Number average molecular weight 12,100).

The above number average molecular weight is a value obtained by gel permeation chromatography under the following conditions.
Column: One TSKgel SuperH3000 (6.0mmφ × 150mm) from Tosoh Corporation, two TSKgel SuperH2000 (6.0mmφ × 150mm), and one TSKgel SuperH1000 (6.0mmφ × 150mm) in series, 4 in series .
Temperature: 40 ° C.
Carrier: tetrahydrofuran (flow rate 0.5 mL / min).
Sample: 10 mg of urethane acrylate was dissolved in 10 mL of tetrahydrofuran, and 50 μL was injected.
Detection: RI.
Standard product: polystyrene.

Example 1
40 parts of urethane acrylate (1), 60 parts of 2-hydroxy-3-phenoxypropyl acrylate, 1.5 parts of 2-hydroxy-2-methylpropiophenone [Darocur 1173 of Ciba Specialty Chemicals Co., Ltd.] , And 2- (3-tert-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzotriazole [Sumisorb 300 of Sumitomo Chemical Co., Ltd.] 0.015 parts added and mixed. The film was coated on a transparent polyethylene terephthalate substrate (hereinafter referred to as a PET substrate) with a thickness of about 230 μm. An 80 W / cm rod-shaped high-pressure mercury lamp is fixed at a position 80 cm above the coating film, and is passed at a speed of 1.0 m / min through a light-shielding plate with a slit so that the light hits the entire coating film vertically. The PET substrate with a coating was irradiated with light while moving in the lateral direction (see FIG. 2) to obtain a light control film. About this light control film, using an integrating sphere type light transmittance measuring device (Hardguard Plus 4725 of Gardner), the angle of incident light was changed between 0 to 180 °, and the haze at each angle was measured. As a result, the light scattering angle region showing a haze value of 60% or more was in the range of 77 to 110 ° (width 33 °). The maximum haze value in this light scattering angle region was 94.5%.

Example 2
Except for using urethane acrylate (2) instead of urethane acrylate (1), the same operation as in Example 1 was performed, and the resulting light control film was measured for haze as in Example 1, The light scattering angle region showing a haze value of 60% or more was in the range of 70 to 105 ° (width 35 °). The maximum haze value in this light scattering angle region was 95.5%.

Comparative Example 1
Except for using urethane acrylate (3) instead of urethane acrylate (1), the same operation as in Example 1 was performed, and the resulting light control film was measured for the haze value in the same manner as in Example 1, The light scattering angle region showing a haze value of 60% or more was in the range of 81 to 109 ° (width 28 °). The maximum haze value in this light scattering angle region was 89.3%.

  The light control film of the present invention can be used, for example, as a viewing angle control film by sticking to a window glass or a touch panel of a cash dispenser. It can also be used as a viewing angle widening film by sticking to a flat panel display or the like. Further, it can be applied to a projection screen.

  Further, by using the photocurable composition of the present invention, for example, as disclosed in JP-A No. 64-40906, it is possible to obtain a light scattering film having no angle dependency on the haze value.

It is a figure for demonstrating the measuring method of the angle dependence of a haze. It is the side view (A) and perspective view (B) which show the example of the apparatus in the case of irradiating light from a perpendicular direction with respect to a photocurable composition coating film. It is the side view (A) and perspective view (B) which show the example of the apparatus in the case of irradiating light from the diagonal direction with respect to a photocurable composition coating film.

Explanation of symbols

1 ... Test piece for measuring haze value
2 ... conveyor,
3 …… Shading plate,
4 ... Slits provided on the light shielding plate,
5 ... Stick-shaped light source lamp,
6: A substrate on which a photocurable composition film is formed.

Claims (4)

  Photocuring characterized in that it contains a plurality of compounds having a polymerizable carbon-carbon double bond in the molecule, and at least one of the compounds is a compound having a number average molecular weight of 20,000 to 100,000. Sex composition.   The photocurable composition according to claim 1, wherein at least one of the compounds having a number average molecular weight of 20,000 to 100,000 is a compound having a plurality of polymerizable carbon-carbon double bonds in the molecule.   The photocurable composition according to claim 1 or 2, wherein at least one of the compounds having a number average molecular weight of 20,000 to 100,000 is urethane (meth) acrylate.   The light control film | membrane formed by irradiating light and hardening | curing the film | membrane of the photocurable composition in any one of Claims 1-3.

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