JP5621458B2 - Optical device - Google Patents

Description

The present invention relates to an optical device in which a fine structure is formed on a substrate surface by transfer molding such as nanoimprint.

In recent years, nanoimprints capable of forming submicron order periodic structures have attracted attention as next-generation lithography technologies. Examples of the optical device produced by transfer molding such as nanoimprint include an antireflection film having a moth-eye structure, a brightness enhancement film having a prism array, a microlens array, and a spectroscopic element having a lattice pattern. . Many of these utilize the refraction and diffraction of light, and the shape of the microstructure and the refractive index of the material forming it are important factors affecting the performance.

However, there is a limit to the fine structure that can be formed by nanoimprinting. For example, a structure with a large aspect ratio is difficult to release from the mold, and is difficult to manufacture. Therefore, if there is a material having a high refractive index, the degree of freedom of optical design is increased more than before, and a higher performance device can be manufactured. For example, Patent Document 1 proposes a prism sheet made of a material having a high refractive index, and describes that front luminance increases when this prism sheet is used as a luminance enhancement film for a liquid crystal display. However, although the effect of increasing the refractive index is clear, the refractive index is at most 1.63, and a material having a higher refractive index has been desired.

  In addition, a nanoimprint containing a resin having a radical reactive group and an acid group in the side chain (Patent Document 2), a laminated optical member using a specific urethane oligomer and a specific monomer (Patent Document 3), a specific radical There have been proposed an optical component (Patent Document 4) having a surface with a fine concavo-convex shape using a polymerizable reaction product, an optical sheet (Patent Document 5) having a light diffusion structure formed by fine foaming, and the like. However, a material having a high refractive index has not been obtained.

The inventor has found a photocurable composition containing an episulfide compound and a photobase generator (Patent Document 6). The refractive index of this cured product is around 1.70, which is much higher than that of a conventional photocurable composition. Further, the cured product has high transparency and is suitable as an optical material. Furthermore, when considering its performance as a material for transfer molding such as nanoimprinting, the photocurable composition has a low viscosity of several tens of mPa · s, so it is easy to get into the details of the mold structure. Can be accurately transferred. In addition, since the episulfide compound is difficult to adhere to a material such as metal or quartz, the releasability from the mold is good.

Japanese Patent Application Laid-Open No. 07-174910 JP 2008-238416 A JP 2009-048184 A JP 2010-024447 A JP 2010-145428 A International Publication WO2005 / 014696 Pamphlet

An object of the present invention is to provide an optical device having a fine structure with a high refractive index on a substrate surface by transfer molding such as nanoimprint.

As a result of intensive studies, the present inventors have found that an optical device having a high refractive index can be obtained by using a photocurable composition containing the above episulfide compound and a photobase generator, leading to the present invention. It was.

That is, the present invention relates to an optical device having a microstructure formed on a substrate surface, wherein the photocurable composition containing an episulfide compound and a photobase generator is used. In addition, the photocurable composition is obtained by sandwiching a substrate and a mold having a fine structure, polymerizing by irradiation with light, and then peeling the substrate having the fine structure transferred from the mold. The present invention relates to a method for manufacturing an optical device.

According to the present invention, an optical device having a fine structure with a high refractive index on a substrate surface can be provided by transfer molding such as nanoimprint.

The episulfide compound used in the present invention is represented by the following general formula (1).

（式中、ｍは０から６の整数、ｎは０から４の整数であり、Ｒ^１，Ｒ^２はそれぞれ独立に、水素原子またはＣ１〜Ｃ１０の炭化水素であり、Ｒ^３，Ｒ^４はそれぞれ独立にＣ１〜Ｃ１０の炭化水素である。）

(In the formula, m is an integer of 0 to 6, n is an integer of 0 to 4, R ¹ and R ² are each independently a hydrogen atom or a C1-C10 hydrocarbon, and R ³ and R ⁴ are Each is independently a C1-C10 hydrocarbon.)

Specific examples of this episulfide compound include bis (2,3-epithiopropyl) sulfide, bis (2,3-epithiopropylthio) ethane, bis (2,3-epithiopropylthio) propane, bis (2 , 3-epithiopropylthio) butane, bis (5,6-epithio-3-thiohexane) sulfide, bis (2,3-epithiopropyl) disulfide, bis (3,4-epithiobutyl) disulfide, bis (4 5-epithiopentyl) disulfide, bis (5,6-epithiohexyl) disulfide and the like. These may be used alone or in combination of two or more. Among them, bis (2,3-epithiopropyl) sulfide (in the general formula (1), n is 0, R ¹ and R ² are hydrogen atoms, R ³ and R ⁴ are methylene) has a particularly high refractive index, Moreover, since the viscosity is low, it is preferable as a material for transfer molding.

The photobase generator used in the present invention is a compound that generates a base by photolysis with ultraviolet light or visible light. In particular, since the polymerization of episulfide compounds is promoted by amidine such as DBN (diazabicyclononene) and DBU (diazabicycloundecene), photobase generators that generate these bases are preferred. Specifically, the amidinium ketone (the left side of the following formula (2)) forming the tetraarylborate salt described in JP-T-2001-513765 and JP-T-2005-511536 is described. 1,3-diamine (the left side of the following formula (3)) substituted with an arylalkyl group that has been used. These may be used alone or in admixture of two or more. The addition amount of the photobase generator is in the range of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 100 parts by weight of the total amount of the episulfide compound and the thiol compound described later. Is 0.5 to 2 parts by weight.

Further, a photosensitizer may be added to the photobase generator. By adding the photosensitizer, the photodecomposition of the photobase generator is accelerated, and the curing time of the photocurable composition can be shortened. Specific examples of the photosensitizer include benzophenones, thioxanthones, anthraquinones, camphorquinones, benzyls, Michler ketones, and anthracenes. These may be used alone or in combination of two or more. The addition amount of the photosensitizer is in the range of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 100 parts by weight of the total amount of the episulfide compound and the thiol compound described later. Is 0.5 to 2 parts by weight.

The photocurable composition used in the present invention preferably contains a thiol compound in addition to the episulfide compound and the photobase generator. By blending the thiol compound, a transparent cured product with less coloring can be obtained.

Preferred examples of the thiol compound include methanedithiol, methanetrithiol, 1,2-dimercaptoethane, bis (2-mercaptoethyl) sulfide, bis (2,3-dimercaptopropyl) sulfide, 1,2,3. -Trimercaptopropane, 2-mercaptomethyl-1,3-dimercaptopropane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 2,4-bis (mercaptomethyl) -1,5-dimercapto -3-thiapentane, 4,8-bis (mercaptomethyl) -1,11-dimercapto-3,6,9-trithiaundecane, 4,7-bis (mercaptomethyl) -1,11-dimercapto-3,6 , 9-trithiaundecane, 5,7-bis (mercaptomethyl) -1,11-dimercapto-3, , 9-trithiaundecane, 1,2,7-trimercapto-4,6-dithiaheptane, 1,2,9-trimercapto-4,6,8-trithianonane, 1,2,8,9-tetramercapto- 4,6-dithianonane, 1,2,10,11-tetramercapto-4,6,8-trithiaundecane, 1,2,12,13-tetramercapto-4,6,8,10-tetrathiatridecane , Tetrakis (mercaptomethyl) methane, tetrakis (4-mercapto-2-thiabutyl) methane, tetrakis (7-mercapto-2,5-dithiaheptyl) methane, trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris ( 3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate) , Pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), 2,5-bis (mercaptomethyl) -1,4-dithiane, 1,3-bis (mercaptomethyl) benzene 1,4-bis (mercaptomethyl) benzene, bis (4-mercaptophenyl) sulfide, bis (4-mercaptomethylphenyl) methane, 2,2-bis (4-mercaptomethylphenyl) propane, bis (4-mercapto Methylphenyl) ether, bis (4-mercaptomethylphenyl) sulfide and the like. These may be used alone or in combination of two or more. As the thiol compound content increases, a colorless and transparent cured product can be obtained. On the other hand, the refractive index of the cured product tends to decrease, and the cured product tends to be soft. Therefore, the content of the thiol compound is in the range of 1 to 50 parts by weight, preferably 5 to 30 parts by weight, more preferably 10 to 25 parts per 100 parts by weight of the total amount of the episulfide compound and the thiol compound. Parts by weight.

As necessary, the photo-curable composition includes an antioxidant, a light stabilizer (HALS), an ultraviolet absorber, a silane coupling agent, a release agent, an inorganic filler, a pigment, a dye, a reactive or non-reactive material. It is possible to add a diluent.

The photocurable composition can be obtained by uniformly mixing an episulfide compound, a photobase generator, and other components at room temperature of about 25 ° C. or under heating according to a conventional method. The composition after mixing may be filtered or defoamed as necessary.

The optical device of the present invention is one in which a fine structure having a high refractive index is formed on a substrate surface by a photocurable composition. Specifically, a condensing film on which a microlens is formed, a front luminance improving film on which a prism pattern is formed, an antireflection film on which a moth-eye shape is formed, a spectroscopic element on which a lattice pattern is formed, and the like. Among these, the moth-eye shape is a surface shape having a regular protrusion arrangement, and the refractive index continuously changes in the thickness direction, so that reflection of light can be suppressed. The size of these fine structures is not particularly limited, and is preferably a periodic structure of several nm to several hundred μm.

The substrate used in manufacturing the optical device of the present invention is not particularly limited, but organic materials include thermoplastic resins such as polyester, polycarbonate, polymethyl methacrylate, polycycloolefin, and inorganic materials include glass, quartz, and silicon. Etc. Since it is used as an optical device, the substrate is preferably transparent. These substrates are preferably subjected to surface treatment such as plasma treatment, corona treatment, primer treatment, and silane coupling agent treatment for the purpose of enhancing adhesion.

The shape and size of the mold on which the microstructure used for manufacturing the optical device of the present invention is not particularly limited, but specifically, prism array pattern, dot pattern, hole pattern, cone pattern, pyramid pattern , A lattice pattern, a moth-eye structure, a microlens array, and the like, and a periodic structure of several nm to several hundred μm is preferable. Examples of the mold material include silicon, quartz, nickel, PDMS (polydimethylsiloxane), fluororesin, glassy carbon, and silicon carbide. These molds are preferably subjected to a surface treatment with a release agent such as a fluorine-based agent for the purpose of enhancing the releasability.

The optical device of the present invention is produced by sandwiching a photocurable composition between a substrate and a mold, irradiating light to polymerize the substrate, and then peeling the substrate onto which the fine structure has been transferred from the mold. Therefore, at least one of the substrate and the mold must be made of a material that transmits light.

The wavelength of the irradiated light is preferably 200 nm or more, and more preferably 300 nm or more. The light source is not particularly limited as long as it emits light of these wavelengths, and specific examples include a mercury lamp, a metal halide lamp, a xenon lamp, an electrodeless discharge lamp, and an LED lamp.

After the photocurable composition is polymerized by irradiating light, heating may be performed to further proceed the polymerization. The heating temperature is preferably in the range of 30 ° C. to 150 ° C., and the heating time is preferably in the range of 1 minute to 24 hours.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The mold used in the examples was subjected to mold release treatment using OPTOOL HD-2100TH (manufactured by Daikin Industries).

Example 1
Bis (2,3-epithiopropyl) sulfide (85 parts by weight), pentaerythritol tetrakis (3-mercaptopropionate) (15 parts by weight), and a photobase generator represented by the following formula (4) (2 parts by weight) Part) were mixed and stirred at room temperature until uniform to prepare a photocurable composition (1). The viscosity of the photocurable composition (1) was 20 mPa · s (25 ° C.).

A nickel mold in which a photocurable composition (1) is hung on a PET film (Cosmo Shine A4100, thickness 100 μm, manufactured by Toyobo Co., Ltd.) and a prism row (vertical angle 90 °, pitch 50 μm) is formed thereon. And was irradiated with light from the PET film side. As the exposure conditions, a metal halide lamp (120 W / cm) was used as a light source, and irradiation was performed for 60 seconds at an exposure distance of 30 cm. After the light irradiation, the PET film on which the structure was transferred was peeled from the mold. As a result, the cured product did not remain in the mold and the mold release property was good. By the above procedure, an optical film to which the prism row was transferred was produced. When the surface structure was observed with an SEM (scanning electron microscope), the prism structure of the mold was accurately transferred, and the transferability was good.

In addition, the photocurable composition (1) was sandwiched between two flat glass plates, irradiated with light, and then the cured product was peeled from the glass plate to produce a film having a thickness of about 100 μm. As the exposure conditions, a metal halide lamp (120 W / cm) was used as a light source, and irradiation was performed for 60 seconds at an exposure distance of 30 cm. It was 1.69 (D line, 25 degreeC) when the refractive index of the obtained film was measured using the Abbe refractometer.

Example 2
Bis (2,3-epithiopropyl) sulfide (90 parts by weight), bis (2-mercaptoethyl) sulfide (10 parts by weight), photobase generator represented by the following formula (5) (0.5 parts by weight) , And 4-benzoyl-4′-methyldiphenyl sulfide (1 part by weight) as a photosensitizer was mixed and stirred at room temperature until uniform to prepare photocurable composition (2). Example 1 was repeated except that the photocurable composition (1) was changed to the photocurable composition (2).

The viscosity of the photocurable composition (2) was 12 mPa · s (25 ° C.), and the refractive index of the cured product was 1.71 (D line, 25 ° C.). Further, the mold release property and transferability were good.

Example 3
Example 2 was repeated except that a silicon mold on which a lattice pattern (line width: space = 1: 1, pitch 300 nm, pattern depth 100 nm) was used was used. The releasability from the mold and transferability were good.

Comparative Example 1
Example 3 was repeated except that the photocurable composition was changed to PAK-02 (manufactured by Toyo Gosei Co., Ltd.), which is a commercially available resin for nanoimprinting. The viscosity of the resin was 9 mPa · s (25 ° C.), and the refractive index of the cured product was 1.51 (D line, 25 ° C.). Moreover, the release property from the mold and the transferability were good.

Comparative Example 2
Example 3 was repeated except that the photocurable composition was changed to NICT-83ND (manufactured by Daicel Chemical Industries), which is a commercially available resin for nanoimprinting. The viscosity of the resin was 800 mPa · s (25 ° C.), and the refractive index of the cured product was 1.54 (D line, 25 ° C.). Moreover, the release property from the mold and the transferability were good.

Claims (5)

An optical device having a fine structure formed on a substrate surface, wherein a photocurable composition containing an episulfide compound represented by the general formula (1) and a photobase generator is used.

(In the formula, m is an integer of 0 to 6, n is an integer of 0 to 4, R ¹ and R ² are each independently a hydrogen atom or a C1-C10 hydrocarbon, and R ³ and R ⁴ are Each is independently a C1-C10 hydrocarbon.) The optical device according to claim 1, wherein the photocurable composition further contains a thiol compound. The optical device according to claim 1 or 2, compounds represented by the general formula (1) is bis (2,3-epithiopropyl) sulfide. A photocurable composition containing an episulfide compound represented by the general formula (1) and a photobase generator is sandwiched between a substrate and a mold in which a fine structure is formed, and polymerized by irradiation with light. A method for producing an optical device, which is obtained by peeling a transferred substrate from a mold.

(In the formula, m is an integer of 0 to 6, n is an integer of 0 to 4, R ¹ and R ² are each independently a hydrogen atom or a C1-C10 hydrocarbon, and R ³ and R ⁴ are Each is independently a C1-C10 hydrocarbon.) The method for producing an optical device according to claim 4, wherein the photocurable composition further contains a thiol compound.