JP4561280B2 - Microlens array manufacturing method, photosensitive resin composition for microlens array, and photosensitive element for microlens array - Google Patents

Description

  The present invention relates to a method for producing a microlens array, a photosensitive resin composition for a microlens array, and a photosensitive element for a microlens array.

  A microlens array in which a large number of microlenses having a convex shape or a concave shape are arranged on a substrate can improve the light utilization rate. For example, a liquid crystal display device, a three-dimensional display, a lenticular lens, a CCD, etc. It is expected to be used in various fields, such as being used for optical parts.

  In the production of such a microlens array, since the size of the microlens is very small, a method different from polishing or molding used for ordinary lens production has been studied. For example, (1) a method of forming a lens in a round and hemispherical shape by heat flow using the thermal fluidity of the resin (see, for example, Patent Document 1), (2) pattern exposure and development of a photosensitive resin, and circular A method of forming a lens in a dome shape by using a surface tension at the time of melting the resin after forming the resin layer having a three-dimensional shape such as a columnar shape or a stripe shape (for example, Non-Patent Document 1) For example). In particular, the production method (2) using a photosensitive resin is an effective method when the size of the microlens is very small (particularly, when the lens diameter or the lens width is 100 μm or less). Has been.

JP 60-53073 A Meas. Sci. Technol. 1, no. 8, p. 759-766, (1990)

  However, in the conventional method for manufacturing a microlens array using a photosensitive resin, including the method described in Non-Patent Document 1, it is difficult to stably manufacture a microlens array having a lens with a desired curvature. there were. Therefore, there is room for further improvement in the method for manufacturing a microlens array using a photosensitive resin.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a microlens array that can manufacture a microlens array having a lens with a desired curvature with a high yield. Moreover, an object of this invention is to provide the photosensitive resin composition for microlens arrays and the photosensitive element for microlens arrays used for this manufacturing method.

  As a result of diligent studies to achieve the above object, the present inventors have focused on problems in conventional microlens array manufacturing methods including the method described in Non-Patent Document 1.

  FIG. 3 is a schematic cross-sectional view showing a process of forming a photocured portion on a substrate using a negative photoresist material as a photosensitive resin in a conventional method for manufacturing a microlens array. FIG. 3A shows a step of irradiating the photosensitive layer 102 made of a negative photoresist material provided on the substrate 101 with an actinic ray L through a predetermined photomask 103. By this step, the photocuring portion 104 is formed as shown in FIG. Next, by developing and removing the unexposed portion 105 of the photosensitive layer, the photocured portion 104 becomes apparent as shown in FIG.

  The light-irradiated surface S1 of this photocuring portion is usually substantially flat. That is, since the curing reaction of the photosensitive layer proceeds from the exposed surface side, a desired convex surface S2 is formed under the unexposed portion 105 of the photosensitive layer as shown in FIGS. It is difficult to form the photocuring part 106 having the photocuring part 107 having the desired concave surface S3. Therefore, in order to form the surface shape opposite to the substrate of the photosensitive layer only in the exposure and development steps into a convex shape or a concave shape having a desired curvature, a step of heating and melting the formed photocured portion is necessary thereafter. It becomes.

  However, in order to form a fully cured photocured portion into a convex or concave lens having a desired curvature by heating and melting, the photoresist materials that can be used are limited. Further, when the degree of deformation of the photocured portion by heat melting is large, the accuracy of lens molding is lowered. Accordingly, it has been found that it is difficult to stably produce a microlens array having a desired lens shape by a conventional microlens array production method using a negative photoresist material as a photosensitive resin.

  Here, it is conceivable to use a positive photoresist material capable of removing the exposed portion as the photosensitive resin. However, the positive photoresist material has a problem that the transparency required for use as an optical component is insufficient.

  As a result of various studies based on the above findings, the present inventors have devised the exposure method of the photosensitive layer, so that even if a negative photoresist material is used, a desired shape can be formed on the substrate. It has been found that a photocured part can be formed.

The method for producing a microlens array of the present invention comprises: (a) a binder polymer having an acid value of 16 to 260 mgKOH / g and a weight average molecular weight of 1000 to 300,000 on a support film; Each of the photosensitive resin compositions, which are negative photoresist materials, containing a photopolymerizable unsaturated compound having an ethylenically unsaturated group and (c) a photopolymerization initiator that generates free radicals by the active light. A photosensitive element for a microlens array, comprising: a photosensitive layer formed by applying a coating solution prepared by uniformly dissolving or dispersing components in a solvent to form a coating film, and drying and removing the solvent from the coating film. A microlens array photosensitive element on one side of a substrate transparent to a specific actinic ray, and the photosensitive layer of the photosensitive element is in contact with the substrate A photosensitive layer forming step of forming a photosensitive layer composed of a photosensitive resin composition by pressure bonding with a pressure roll, and actinic rays from a side opposite to the surface on which the photosensitive layer of the substrate is provided through a predetermined photomask. An exposure process for irradiating the photosensitive layer ; and a development process for forming a microlens array pattern by removing an unexposed portion of the photosensitive layer by development.

  Here, the “specific actinic ray” means a ray capable of photocuring the photosensitive resin.

  In the method for producing a microlens array of the present invention, the photosensitive layer is cured from the substrate side in the exposure step, and the unexposed portion of the photosensitive layer is removed from the opposite side of the substrate side in the development step. Thereby, the surface which has a desired curvature in a photocuring part can be formed. That is, a convex or concave photocured portion having a desired curvature as shown in FIG. 4 can be formed.

  The curvature of the side opposite to the substrate side of the photocuring part is controlled by adjusting, for example, the thickness of the substrate, the material of the substrate, the light diffusibility of the substrate, the distance between the photosensitive layer and the photomask, etc. Is possible.

  As described above, the microlens array manufacturing method of the present invention makes it difficult to use a conventional negative photoresist material, and the lens surface shape is convex or concave having a desired curvature only by exposure and development. Can be easily performed using a negative photoresist material having excellent transparency.

  In addition, even when the resist formed by exposure and development is further heated and melted to deform it into a desired convex or concave lens, the degree of deformation can be made smaller than in the conventional method, thus improving the accuracy of lens molding. To do. Furthermore, since the substrate side surface of the photosensitive layer can be sufficiently photocured, the photocured portion can also be prevented from peeling from the substrate.

  Therefore, a microlens array having a lens with a desired curvature can be manufactured with a high yield. Furthermore, since a negative photoresist material can be used, a microlens array having sufficiently excellent transparency can be obtained.

  In addition, the photosensitive resin composition includes (a) a binder polymer, (b) a photopolymerizable unsaturated compound having an ethylenically unsaturated group, and (c) photopolymerization initiation that generates free radicals by the active light. It is preferable to contain an agent.

  When such a photosensitive resin composition is used, it becomes easy to improve the resolution and adhesion of the photosensitive layer, so that a microlens array having a lens with a desired curvature can be manufactured with a higher yield.

  The photosensitive element for a microlens array of the present invention is used for providing a photosensitive layer in the method for producing a microlens array of the present invention, and is composed of the above-described photosensitive resin composition on a support film. A photosensitive layer is provided.

  Such a photosensitive element for a microlens array is excellent in workability (handleability) when providing a photosensitive layer, and can produce a microlens array having a lens with a desired curvature with a high yield. Furthermore, since a negative photoresist material can be used as the photosensitive resin composition, a microlens array having sufficiently excellent transparency can be obtained.

Here, the photosensitive resin composition has (a) a binder polymer having an acid value of 16 to 260 mgKOH / g and a weight average molecular weight of 1000 to 300,000, and (b) an ethylenically unsaturated group. It contains a photopolymerizable unsaturated compound and (c) a photopolymerization initiator that generates free radicals by the active light.

  When such a photosensitive resin composition is used, it is easy to improve the resolution and adhesion of the photosensitive layer, so that a microlens array having a lens with a desired curvature can be more reliably manufactured with a high yield.

  The photosensitive resin composition for a microlens array of the present invention is used in the method for producing the microlens array of the present invention, and (a) a binder polymer and (b) a photopolymerizable polymer having an ethylenically unsaturated group. It contains an unsaturated compound and (c) a photopolymerization initiator that generates free radicals by the active light.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the micro lens array which can manufacture the micro lens array which has a lens of a desired curvature with a sufficient yield can be provided. Moreover, this invention can provide the photosensitive resin composition for microlens arrays and the photosensitive element for microlens arrays used for this manufacturing method.

  Hereinafter, embodiments of the present invention will be described in detail.

  The method for producing a microlens array of the present invention includes (I) a photosensitive layer forming step in which a photosensitive layer made of a photosensitive resin composition is provided on one surface of a substrate transparent to a specific actinic ray; ) An exposure step of irradiating the photosensitive layer with an actinic ray through a predetermined photomask from the side opposite to the surface on which the photosensitive layer of the substrate is provided; and (III) development for removing unexposed portions of the photosensitive layer by development. Process.

  First, an embodiment of the photosensitive resin composition for a microlens array of the present invention used in the above method for producing a microlens array will be described.

  The photosensitive resin composition for a microlens array of the present embodiment includes (a) a binder polymer, (b) a photopolymerizable unsaturated compound having an ethylenically unsaturated group, and (c) free radicals by the active light. And a photopolymerization initiator to be produced.

  (A) As a binder polymer, a vinyl copolymer is mentioned, for example, Specifically, what was obtained by polymerizing the following vinyl monomer is mentioned. For example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, iso-propyl acrylate , Iso-propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, iso-butyl acrylate, iso-butyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, tert-butyl acrylate, Tert-butyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, acrylate Chill, octyl methacrylate, nonyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, Octadecyl methacrylate, eicosyl acrylate, eicosyl methacrylate, docosyl acrylate, docosyl methacrylate, cyclopentyl acrylate, cyclopentyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, cycloheptyl acrylate, cycloheptyl methacrylate, benzyl acrylate, Benzyl methacrylate, phenyl acrylate, phenyl methacrylate, methoxyethyl acrylate, methacrylate Methoxyethyl acid, methoxydiethylene glycol acrylate, methoxydiethylene glycol methacrylate, methoxydipropylene glycol acrylate, methoxydipropylene glycol methacrylate, methoxytriethylene glycol acrylate, methoxytriethylene glycol methacrylate, 2-hydroxyethyl acrylate, methacryl 2-hydroxyethyl acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, 2-chloroethyl acrylate, 2-methacrylic acid 2- Chloroethyl, 2-fluoroethyl acrylate, 2-fluoroethyl methacrylate, acrylic 2-cyanoethyl phosphate, 2-cyanoethyl methacrylate, styrene, α-methylstyrene, cyclohexylmaleimide, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, vinyl toluene, vinyl chloride, vinyl acetate, N-vinyl pyrrolidone, Examples include butadiene, isoprene, chloroprene, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile and the like. These may be polymerized singly or in combination of two or more.

  Furthermore, in the photosensitive resin composition for microlens array of this embodiment, (a) As a binder polymer, it has functional groups, such as a carboxyl group, a hydroxyl group, an amino group, an isocyanate group, an oxirane ring, an acid anhydride, for example. One functional group such as an oxirane ring, an isocyanate group, a hydroxyl group, and a carboxyl group that binds to the vinyl copolymer by reacting with the functional group of the vinyl copolymer, and at least one ethylenically unsaturated group It is also possible to use a radical polymerizable copolymer having an ethylenically unsaturated group in the side chain obtained by addition reaction of a compound having the following.

  Examples of the vinyl monomer used in the production of the vinyl copolymer having a functional group such as a carboxyl group, a hydroxyl group, an amino group, an oxirane ring, and an acid anhydride include acrylic acid, methacrylic acid, maleic acid, and fumaric acid. , Itaconic acid, cinnamic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, ethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, maleic anhydride and the like. These may be polymerized singly or in combination of two or more. Moreover, the said vinyl monomers other than the vinyl monomer which has functional groups, such as a carboxyl group, a hydroxyl group, an amino group, an oxirane ring, and an acid anhydride, can be copolymerized as needed.

  In addition, (a) the weight average molecular weight of the binder polymer (measured by gel permeation chromatography and converted to standard polystyrene) was heat resistance, heat meltability, coatability, and a microlens array photosensitive element described later. From the viewpoints of film properties (characteristics for maintaining a film-like form), solubility in a solvent, solubility in a developing solution in the development step, and the like, it is preferably 1000 to 300000, 5000 to 150,000. More preferably.

  Furthermore, it is preferable that (a) the binder polymer has an acid value so that it can be developed with various known developing solutions in the development step. For example, when the development is performed using an alkaline aqueous solution such as sodium carbonate, potassium carbonate, tetramethylammonium hydroxide, or triethanolamine, the acid value is preferably 50 to 260 mgKOH / g. When the acid value is less than 50 mgKOH / g, development tends to be difficult, and when it exceeds 260 mgKOH / g, the developer resistance (the portion that becomes a pattern without being removed by development is not affected by the developer). ) Tend to decrease. Moreover, when developing using the aqueous alkali solution which consists of water or aqueous alkali solution and 1 or more types of surfactant, it is preferable that an acid value shall be 16-260 mgKOH / g. When the acid value is less than 16 mgKOH / g, development tends to be difficult, and when it exceeds 260 mgKOH / g, the developer resistance tends to be lowered.

  (B) As a photopolymerizable unsaturated compound having an ethylenically unsaturated group, for example, a compound obtained by reacting a polyhydric alcohol and an α, β-unsaturated carboxylic acid, 2,2-bis (4- (Di (meth) acryloxypolyethoxy) phenyl) propane, a compound obtained by reacting a glycidyl group-containing compound with an α, β-unsaturated carboxylic acid, a urethane monomer, nonylphenyldioxylene (meth) acrylate, γ- Chloro-β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate, β-hydroxyethyl-β ′-(meth) acryloyloxyethyl-o-phthalate, β-hydroxypropyl-β ′-(meta ) Acryloyloxyethyl-o-phthalate, (meth) acrylic acid alkyl ester and the like.

  Examples of the compound obtained by reacting the polyhydric alcohol with an α, β-unsaturated carboxylic acid include, for example, polyethylene glycol di (meth) acrylate having 2 to 14 ethylene groups and 2 propylene groups. ~ 14 polypropylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane diethoxytri (meth) acrylate , Trimethylolpropane triethoxytri (meth) acrylate, trimethylolpropanetetraethoxytri (meth) acrylate, trimethylolpropane pentaethoxytri (meth) acrylate, tetramethylolmethanetri (meth) ) Acrylate (pentaerythritol tri (meth) acrylate), tetramethylolmethane tetra (meth) acrylate, polypropylene glycol di (meth) acrylate having 2 to 14 propylene groups, dipentaerythritol penta (meth) acrylate, di Examples include pentaerythritol hexa (meth) acrylate.

  Examples of the 2,2-bis (4- (di (meth) acryloxypolyethoxy) phenyl) propane include 2,2-bis (4- (di (meth) acryloxydiethoxy) phenyl) propane, 2 , 2-bis (4- (di (meth) acryloxytriethoxy) phenyl) propane, 2,2-bis (4- (di (meth) acryloxypentaethoxy) phenyl) propane, 2,2-bis (4 -(Di (meth) acryloxydecaethoxy) phenyl) and the like.

  Examples of the compound obtained by reacting the glycidyl group-containing compound with an α, β-unsaturated carboxylic acid include trimethylolpropane triglycidyl ether tri (meth) acrylate and 2,2-bis (4- (meth)). (Acryloxy-2-hydroxy-propyloxy) phenyl and the like.

  Examples of the urethane monomer include (meth) acrylic monomers having an OH group at the β-position and isocyanate compounds such as isophorone diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and 1,6-hexamethylene diisocyanate. Addition reaction product, tris ((meth) acryloxytetraethylene glycol isocyanate) hexamethylene isocyanurate, ethylene oxide modified urethane di (meth) acrylate, ethylene oxide, propylene oxide modified urethane di (meth) acrylate and the like.

  Examples of the (meth) acrylic acid alkyl ester include (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth) acrylic acid butyl ester, (meth) acrylic acid 2-ethylhexyl ester, and the like. .

  Said photopolymerizable unsaturated compound can be used individually by 1 type or in combination of 2 or more types.

  (C) Examples of photopolymerization initiators that generate free radicals with actinic rays include benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N′-tetraethyl-4, 4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one (“Irgacure-369”, Ciba Specialty) Chemicals Co., Ltd. trade name), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one ("Irgacure-907", Ciba Specialty Chemicals trade name), etc. Aromatic ketones; 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butyl Luanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9 , 10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, quinones such as 2,3-dimethylanthraquinone; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether; benzoin, methylbenzoin Benzoin compounds such as ethyl benzoin; benzyl derivatives such as benzyl dimethyl ketal; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl)- , 5-Di (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer 2,4,5-triarylimidazole dimers such as 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer; 9-phenylacridine, 1,7-bis (9,9′- Acridine derivatives such as (acridinyl) heptane; N-phenylglycine, N-phenylglycine derivatives, coumarin compounds and the like.

  In the 2,4,5-triarylimidazole dimer, the substituents substituted with two 2,4,5-triarylimidazoles may be the same or different. Moreover, you may combine a thioxanthone type compound and a tertiary amine compound like the combination of diethyl thioxanthone and dimethylaminobenzoic acid.

  In the photosensitive resin composition for a microlens array of the present embodiment, 2,4,5-triarylimidazole dimer is preferable from the viewpoints of adhesion to the substrate and sensitivity. Furthermore, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one is more preferable from the viewpoint of visible light transmittance when a microlens array is used as a liquid crystal spacer.

  Said photoinitiator can be used individually by 1 type or in combination of 2 or more types.

  In the photosensitive resin composition for a microlens array of the present embodiment, the blending ratio of the (a) binder polymer is 20 to 90 parts by mass with respect to 100 parts by mass of the total amount of the components (a) and (b). Is more preferable, 30 to 85 parts by mass is more preferable, 35 to 80 parts by mass is particularly preferable, and 40 to 75 parts by mass is extremely preferable. If the blending ratio is less than 20 parts by mass, the coating property, heat melting property, or film property in the case of a photosensitive element for a microlens array to be described later tends to be deteriorated. Or heat resistance tends to be lowered.

  In the photosensitive resin composition for a microlens array of this embodiment, the blending ratio of (b) the photopolymerizable unsaturated compound having an ethylenically unsaturated group is 100 mass of the total amount of the components (a) and (b). The amount is preferably 10 to 80 parts by mass, more preferably 15 to 70 parts by mass, particularly preferably 20 to 65 parts by mass, and particularly preferably 25 to 60 parts by mass. preferable. If the blending ratio is less than 10 parts by mass, the photocurability or heat resistance tends to decrease. If the blending ratio exceeds 80 parts by mass, the coating property, heat-melting property, or film for a microlens array photosensitive element is obtained. Tend to decrease.

  Moreover, in the photosensitive resin composition for a microlens array of the present embodiment, the blending ratio of the (c) photopolymerization initiator is 0.05 to 100 parts by mass with respect to 100 parts by mass of the total amount of the components (a) and (b). It is preferably 20 parts by mass, more preferably 0.1 to 15 parts by mass, and particularly preferably 0.15 to 10 parts by mass. If the blending ratio is less than 0.05 parts by mass, photocuring tends to be insufficient, and if it exceeds 20 parts by mass, absorption of actinic rays on the actinic ray-irradiated surface of the photosensitive layer increases in the exposure step. Therefore, the internal photocuring tends to be insufficient.

  In the photosensitive resin composition for the microlens array of the present embodiment, if necessary, an adhesion imparting agent such as a silane coupling agent, a leveling agent, a plasticizer, a filler, an antifoaming agent, a flame retardant, and a stabilizer. , Antioxidants, fragrances, thermal crosslinking agents, polymerization inhibitors and the like can be contained. These can be used individually by 1 type or in combination of 2 or more types. Moreover, these compounding ratios can be 0.01-20 mass parts with respect to 100 mass parts of total amounts of (a) and (b) component, respectively.

  Next, embodiments of the photosensitive element for microlens array of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of a photosensitive element for a microlens array of the present invention. A microlens array photosensitive element 100 of this embodiment shown in FIG. 1 includes a photosensitive layer 2 made of the above-described photosensitive resin composition for microlens array on a support film 1.

  Examples of the support film include films made of polyethylene terephthalate, polycarbonate, polyethylene, polypropylene, polyethersulfone, and the like. The thickness of the film is preferably about 5 to 100 μm.

  As a manufacturing method of the photosensitive element 100 for microlens array of this embodiment, the following method is mentioned, for example. First, a coating solution is prepared by uniformly dissolving or dispersing each component of the above-described photosensitive resin composition for a microlens array in a solvent. Next, this coating solution is applied onto the support film 1 to form a coating film. Next, the photosensitive element 100 for microlens array is obtained by drying and removing the solvent from the coating film to form a photosensitive layer.

  Solvents include aliphatic alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, n-pentanol, hexanol; allyl alcohol, benzyl alcohol, anisole, phenetole, n-hexane, cyclohexane, heptane , Hydrocarbons such as octane, nonane, decane; diacetone alcohol, 3-methoxy-1-butanol, 4-methoxy-1-butanol, 3-ethoxy-1-butanol, 3-methoxy-3-methyl-1- Butanol, 3-methoxy-3-ethyl-1-pentanol-4-ethoxy-1-pentanol, 5-methoxy-1-hexanol; acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl isobutyl ketone, methyl pentyl ketone , Me Ruhexyl ketone, ethyl butyl ketone, dibutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, γ-butyrolactone, 3-hydroxy-2-butanone, 4-hydroxy-2-butanone, 4-hydroxy-2-pentanone, 5-hydroxy -2-pentanone, 4-hydroxy-3-pentanone, 6-hydroxy-2-hexanone, 3-methyl-3-hydroxy-2-pentanone; ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, ethylene Glycol monoacetate, ethylene glycol diacetate, propylene glycol monoacetate, propylene glycol diacetate, methyl cellosolve, ethyl cellosolve, butyl cellosol , Phenyl cellosolve, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, methyl cellosolve acetate, ethyl cellosolve acetate and other ethylene glycol alkyl ethers and acetates thereof; diethylene glycol monomethyl ether, monoethyl ether, mono i-propyl ether Diethylene glycol monoalkyl ethers such as monobutyl ether and diethylene glycol monomethyl ether acetate and their acetates; diethylene glycol alkyl ethers such as dimethyl diethylene glycol, diethyl diethylene glycol and dibutyl diethylene glycol; monomethyl ether, monoethyl ether, dimethyl ether, diethyl ether And triethylene glycol alkyl ethers such as methyl ethyl ether; propylene glycol alkyl ethers such as monomethyl ether, monoethyl ether, n-propyl ether, monobutyl ether, dimethyl ether, diethyl ether, monomethyl ether acetate, monoethyl ether acetate, and the like; The acetate; dipropylene glycol alkyl ethers such as monomethyl ether, monoethyl ether, n-propyl ether, monobutyl ether, dimethyl ether, diethyl ether; ethyl formate, propyl formate, butyl formate, amyl formate, methyl acetate, ethyl acetate, acetic acid Carboxylic acid esters such as propyl, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate; Formamide, dimethyl sulfoxide, dioxane, tetrahydrofuran, methyl lactate, ethyl lactate, methyl benzoate, ethyl benzoate, propyl carbonate, and the like.

  As a method of applying the coating solution on the support film 1, a known coating method can be used. For example, a doctor blade coating method, a Meyer bar coating method, a roll coating method, a screen coating method, a spinner coating method, Examples include an inkjet coating method, a spray coating method, a dip coating method, a gravure coating method, a curtain coating method, and a die coating method.

  The thickness of the photosensitive layer 2 is not particularly limited as long as it exhibits performance as a microlens array after exposure and development, but is preferably 0.1 to 100 μm, and preferably 1.0 to 50 μm. Is more preferable, and 3.0 to 30 μm is particularly preferable. If the thickness of the photosensitive layer 2 is less than 0.1 μm, it tends to be difficult to show the performance as a microlens array. If the thickness exceeds 100 μm, the resolution is lowered and the microlens array has a good shape. Tends to be difficult to obtain.

  The viscosity of the photosensitive layer 2 is preferably 15 to 100 MPa · s, more preferably 20 to 90 MPa · s, and particularly preferably 25 to 80 MPa · s at 30 ° C. By setting it as this viscosity, when the photosensitive element for microlens arrays is wound and stored, for example, it can prevent that the photosensitive resin composition oozes out from the end surface of the photosensitive element for one month or more. In addition, when the photosensitive element is cut, it is possible to prevent the fragments of the photosensitive layer from adhering to the base material to cause exposure failure or development residue.

In addition, for the above viscosity, a circular photosensitive layer sample having a diameter of 7 mm and a thickness of 2 mm was prepared, and a load of 1.96 × 10 ⁻² N was applied in the thickness direction of this sample at 30 ° C. and 80 ° C. This is a value obtained by measuring the rate of change of thickness at the time and converting it to viscosity assuming a Newtonian fluid from this rate of change.

  In the microlens array photosensitive element 100 of this embodiment, a cover film may be further laminated on the photosensitive layer 2.

  Examples of the cover film include films made of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, and the like. The thickness of the cover film is preferably about 5 to 100 μm.

  The photosensitive element for a microlens array on which such a cover film is laminated can be stored in a roll shape or used in a roll shape.

  Next, the manufacturing method of the microlens array of this invention is demonstrated.

  FIG. 2 is a schematic cross-sectional view for explaining an embodiment of a method for producing a microlens array of the present invention. In the manufacturing method of the microlens array of this embodiment shown in FIG. 2, (I) Photosensitive layer formation which provides the photosensitive layer which consists of a photosensitive resin composition on one surface of a base material transparent with respect to a specific actinic ray. A step, (II) an exposure step of irradiating the photosensitive layer with an actinic ray through a predetermined photomask from the side opposite to the surface on which the photosensitive layer of the substrate is provided, and (III) unexposed of the photosensitive layer by development A developing step for removing the portion and (IV) a heating step for further heating the microlens array pattern formed through the above (I) to (III) are included.

  First, as shown in FIG. 2A, (I) a photosensitive layer forming step in which a photosensitive layer 20 made of a photosensitive resin composition is provided on one surface of a substrate 10 transparent to a specific actinic ray. Do.

  The substrate 10 is not particularly limited as long as it transmits an actinic ray capable of photocuring the photosensitive resin, such as a plastic plate, a glass plate, and a film of polyethylene terephthalate, polycarbonate, polyethersulfone, or the like. Can be mentioned.

  The photosensitive layer 20 can be formed using the photosensitive resin composition for a microlens array of the present embodiment or the photosensitive element for a microlens array of the present embodiment. Each method will be described below.

[(IA) Photosensitive layer forming step using photosensitive resin composition for microlens array]
A coating solution is prepared by uniformly dissolving or dispersing each component of the photosensitive resin composition for microarray of the present embodiment in a solvent. Next, this coating solution is applied onto the substrate 10 to form a coating film. Next, the photosensitive layer 20 is formed by drying and removing the solvent from the coating film.

  Solvents include aliphatic alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, n-pentanol, hexanol; allyl alcohol, benzyl alcohol, anisole, phenetole, n-hexane, cyclohexane, heptane , Hydrocarbons such as octane, nonane, decane; diacetone alcohol, 3-methoxy-1-butanol, 4-methoxy-1-butanol, 3-ethoxy-1-butanol, 3-methoxy-3-methyl-1- Butanol, 3-methoxy-3-ethyl-1-pentanol-4-ethoxy-1-pentanol, 5-methoxy-1-hexanol; acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl isobutyl ketone, methyl pentyl ketone , Me Ruhexyl ketone, ethyl butyl ketone, dibutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, γ-butyrolactone, 3-hydroxy-2-butanone, 4-hydroxy-2-butanone, 4-hydroxy-2-pentanone, 5-hydroxy -2-pentanone, 4-hydroxy-3-pentanone, 6-hydroxy-2-hexanone, 3-methyl-3-hydroxy-2-pentanone; ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, ethylene Glycol monoacetate, ethylene glycol diacetate, propylene glycol monoacetate, propylene glycol diacetate, methyl cellosolve, ethyl cellosolve, butyl cellosol , Phenyl cellosolve, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, methyl cellosolve acetate, ethyl cellosolve acetate and other ethylene glycol alkyl ethers and acetates thereof; diethylene glycol monomethyl ether, monoethyl ether, mono i-propyl ether Diethylene glycol monoalkyl ethers such as monobutyl ether and diethylene glycol monomethyl ether acetate and their acetates; diethylene glycol alkyl ethers such as dimethyl diethylene glycol, diethyl diethylene glycol and dibutyl diethylene glycol; monomethyl ether, monoethyl ether, dimethyl ether, diethyl ether And triethylene glycol alkyl ethers such as methyl ethyl ether; propylene glycol alkyl ethers such as monomethyl ether, monoethyl ether, n-propyl ether, monobutyl ether, dimethyl ether, diethyl ether, monomethyl ether acetate, and monoethyl ether acetate; The acetate; dipropylene glycol alkyl ethers such as monomethyl ether, monoethyl ether, n-propyl ether, monobutyl ether, dimethyl ether, diethyl ether; ethyl formate, propyl formate, butyl formate, amyl formate, methyl acetate, ethyl acetate, acetic acid Carboxylic acid esters such as propyl, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate; Formamide, dimethyl sulfoxide, dioxane, tetrahydrofuran, methyl lactate, ethyl lactate, methyl benzoate, ethyl benzoate, propyl carbonate, and the like.

  As a method of applying the coating solution onto the substrate 10, a known coating method can be used. For example, doctor blade coating method, Mayer bar coating method, roll coating method, screen coating method, spinner coating method, inkjet Examples thereof include a coating method, a spray coating method, a dip coating method, a gravure coating method, a curtain coating method, and a die coating method.

  The drying temperature for drying and removing the solvent from the coating film is preferably 60 to 130 ° C. The drying time is preferably 1 minute to 1 hour.

  Moreover, it is preferable to adjust the thickness of a coating film so that the thickness of the formed photosensitive layer may be 0.1-100 micrometers. Furthermore, the thickness of the photosensitive layer is more preferably 1.0 to 50 μm, and particularly preferably 3.0 to 30 μm. By setting the thickness of the photosensitive layer in the above range, the performance as a microlens array can be more reliably obtained after exposure and development. Adjustment of the thickness of a coating film can be performed by changing the application quantity of a coating liquid and the quantity of a solvent, for example.

[(IB) Photosensitive layer forming step using photosensitive element for microlens array]
First, the microlens array photosensitive element of the present embodiment is prepared. Next, when the photosensitive element is provided with a cover film, the cover film is removed, and the photosensitive element and the substrate are pressure-bonded with a pressure roll so that the photosensitive layer of the photosensitive element is in contact with the substrate 10. Laminate while.

  The pressure roll may be provided with a heating means so that it can be heat-pressure bonded. The heating temperature for thermocompression bonding is preferably 10 to 180 ° C, more preferably 20 to 160 ° C, and particularly preferably 30 to 150 ° C. When the heating temperature is less than 10 ° C., the adhesion between the photosensitive layer and the substrate tends to be lowered, and when it exceeds 180 ° C., the constituent components of the photosensitive layer tend to be thermally cured or thermally decomposed.

  If the photosensitive element for microlens array is heated as described above, it is not necessary to preheat the substrate, but it is possible to preheat the substrate in order to further improve the adhesion between the photosensitive layer and the substrate. preferable. The preheating temperature at this time is preferably 30 to 180 ° C.

Moreover, it is preferable to set it as 50N / m-1 * 10 < ⁵ > N / m in linear pressure at the time of thermocompression bonding, and it shall be 2.5 * 10 < ² > N / m-5 * 10 < ⁴ > N / m. Is more preferably 5 × 10 ² N / m to ⁴ × 10 ⁴ N / m. If this pressure is less than 50 N / m, the adhesion between the photosensitive layer and the substrate tends to be reduced, and if it exceeds 1 × 10 ⁵ N / m, the substrate tends to be destroyed.

  In this manner, the photosensitive layer of the microlens array photosensitive element of this embodiment can be laminated on the substrate, and the photosensitive layer 20 is laminated on the substrate 10.

  Next, an exposure process is performed after the photosensitive layer forming process. Hereinafter, this process will be described.

[(II) Exposure step]
In the exposure process in the present embodiment, as shown in FIG. 2B, the actinic ray L is applied to the photosensitive layer through a predetermined photomask 30 from the side opposite to the surface on which the photosensitive layer 20 of the substrate 10 is provided. 20 is irradiated.

  As the actinic ray used in the exposure step, a known actinic light source can be used, and examples thereof include a carbon arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, and the like, and those that effectively emit ultraviolet rays are preferable.

  As the photomask 30, a photomask 30 having a pattern in which the area through which actinic rays are transmitted is adjusted in accordance with a target microlens array shape (for example, a cylindrical shape, a stripe shape, or the like) may be used. In addition, in order to control the surface shape of a lens such as a convex lens or a concave lens, the thickness of the base material 10, the light diffusibility of the base material 10, the distance between the photosensitive layer 20 and the photomask 30, and the like are adjusted. do it. More specifically, when the substrate 10 is thickened, the light diffusibility is increased, or the distance between the photosensitive layer 20 and the photomask 30 is increased, there is a tendency to approach the convex lens. On the other hand, when the substrate 10 is thinned, the light diffusibility is decreased, or the distance between the photosensitive layer 20 and the photomask 30 is decreased, the lens tends to approach a concave lens.

[(III) Development step]
The development step in this embodiment is a step of removing the unexposed portion of the photosensitive layer 20 by development, and through this step, the photosensitive layer 20 is photocured on the substrate 10 as shown in FIG. The microlens array pattern 22 which is a part becomes obvious.

  As a developing method, development is performed by a known method such as spraying, showering, rocking dipping, brushing, scraping, etc. using a known developing solution such as an alkaline aqueous solution, an aqueous developer, an organic solvent, etc. The method of removing is mentioned, Among these, it is mentioned that it is preferable to use alkaline aqueous solution from a viewpoint of environment and safety.

  Examples of the base of the alkaline aqueous solution include alkali hydroxide (lithium, sodium or potassium hydroxide, etc.), alkali carbonate (lithium, sodium or potassium carbonate or bicarbonate, etc.), alkali metal phosphate (potassium phosphate, etc.) , Sodium phosphate, etc.), alkali metal pyrophosphates (sodium pyrophosphate, potassium pyrophosphate, etc.), tetramethylammonium hydroxide, triethanolamine, etc. Among them, tetramethylammonium hydroxide, etc. are preferred. It is done.

  The development temperature and time can be adjusted in accordance with the developability of the photosensitive layer comprising the photosensitive resin composition.

  Further, a surfactant, an antifoaming agent, a small amount of an organic solvent for accelerating development, and the like can be added to the alkaline aqueous solution.

  Further, the base of the alkaline aqueous solution remaining in the photosensitive layer after development and photocuring is converted into an acid by a known method such as spraying, rocking immersion, brushing or scraping using an organic acid, an inorganic acid or an aqueous acid solution thereof. It can be treated (neutralized).

  Furthermore, the water washing process can also be performed after an acid treatment (neutralization treatment).

  The substrate 10 on which the microlens array pattern 22 is formed functions sufficiently as a microlens array, but in the present embodiment, a heating process for further heating the microlens array pattern 22 is performed. Through this process, the microlens array pattern 22 is melted, and a microlens array 23 having a desired lens shape is formed as shown in FIG.

  Examples of the heating method include known methods such as hot air radiation and infrared irradiation heating, and are not particularly limited as long as the microlens array pattern formed on the substrate is effectively heated.

  The temperature during heating is preferably 140 to 300 ° C, more preferably 150 to 290 ° C, and particularly preferably 160 to 280 ° C. If the heating temperature is less than 140 ° C, the thermosetting effect tends to be insufficient, and if it exceeds 300 ° C, the constituent components of the photosensitive resin composition layer tend to thermally decompose.

  FIGS. 2C and 2D show a microlens array having a convex lens shape. As described above, the thickness of the base material 10, the light diffusibility of the base material 10, and the photosensitivity. A microlens array 23 having a concave lens shape as shown in FIG. 2E can also be formed on the substrate 10 by adjusting the distance between the layer 20 and the photomask 30.

  In the present embodiment, for the purpose of improving the adhesion of the microlens array pattern 22 to the substrate and improving the chemical resistance, actinic rays are applied to the microlens array pattern 22 after the (III) development step. An irradiation step can be performed.

  The method for irradiating the microlens array pattern 22 with actinic rays is not particularly limited as long as it is a method in which actinic rays are effectively radiated, and examples thereof include known actinic light sources that can be used in the above (II) exposure step. If it radiates | emits an ultraviolet-ray etc. effectively, it will not restrict | limit in particular.

The irradiation amount of active light is preferably 1 × 10 ² J / m ² to 1 × 10 ⁵ J / m ² . If the irradiation amount of actinic rays is less than 1 × 10 ² J / m ² , the effect of photocuring tends to be insufficient, and if it exceeds 1 × 10 ⁵ J / m ² , the microlens array pattern changes color. There is a tendency. Further, heating can be accompanied during irradiation.

  The microlens array obtained by the microlens array manufacturing method of the present embodiment can be used for optical components such as a liquid crystal display device, a three-dimensional display, a lenticular lens, and a CCD.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
[Preparation of binder polymer solution (a-1)]
Into a flask equipped with a stirrer, reflux condenser, inert gas inlet and thermometer, the component (1) shown in Table 1 was charged, heated to 80 ° C. in a nitrogen gas atmosphere, and the reaction temperature was set to 80 ° C. While maintaining the temperature at ± 2 ° C., the component (2) shown in Table 1 was uniformly added dropwise over 4 hours.
After dropwise addition of the component (2), stirring was continued at 80 ° C. ± 2 ° C. for 6 hours to obtain a binder polymer solution (solid content 35 mass%) (a-1) having a weight average molecular weight of about 30,000.

[Preparation of photosensitive resin composition solution for microlens array]
The materials shown in Table 2 were mixed for 15 minutes using a stirrer to prepare a photosensitive resin composition solution for a microlens array.

[Preparation of photosensitive element for microlens array]
A polyethylene terephthalate film having a thickness of 16 μm was used as the support film, and the photosensitive resin composition solution for microlens array obtained above was uniformly applied onto the support film using a comma coater, and hot air at 100 ° C. The solvent was removed by drying with a convection dryer for 3 minutes to form a photosensitive resin composition layer. The thickness of the obtained photosensitive resin composition layer was 30 μm.

  Next, a polyethylene film having a thickness of 25 μm was further laminated as a cover film on the obtained photosensitive resin composition layer to produce a photosensitive element for a microlens array.

[Production of microlens array]
Laminator (manufactured by Hitachi Chemical Co., Ltd., trade name) so that the photosensitive resin composition layer is in contact with a glass substrate having a thickness of 0.5 mm while peeling the polyethylene film of the obtained photosensitive element for microlens array. “HLM-1500 type”), a substrate having a roll temperature of 120 ° C., a substrate feed speed of 1 m / min, and a pressure (cylinder pressure) of 4 × 10 ⁵ Pa (thickness of 0.5 mm, length of 10 cm × width of 10 cm) Since it was used, the substrate was laminated under the condition that the linear pressure at this time was 9.8 × 10 ⁵ N / m) to prepare a substrate in which the photosensitive resin composition layer and the support film were laminated on the glass substrate. .

Next, after peeling off the support film, the surface of the resulting photosensitive resin composition layer provided with the photosensitive resin composition layer using a parallel light exposure machine (EXM1201 manufactured by Oak Manufacturing Co., Ltd.). The exposure amount is 1.5 × 10 ³ J / through a photomask having a stripe pattern of aperture width / light shielding width = 20 μm / 80 μm from the surface opposite to the surface on which the microlens array is formed. At m ² (measured value at i-line (wavelength 365 nm)), ultraviolet rays were irradiated imagewise.

  Next, using 0.5% by mass tetramethylammonium hydroxide aqueous solution containing 0.5% by mass surfactant, spray development is carried out at 30 ° C. for 200 seconds to selectively remove the photosensitive resin composition layer. Thus, a microlens array pattern was formed.

  When the pattern of the obtained microlens array was observed with a scanning electron microscope, a stripe-shaped concave microlens array having a concave shape with a cross-sectional shape and a depth of about 8 μm was well formed.

  Furthermore, it heated with the box-type dryer for 30 minutes at 230 degreeC. When the pattern of the microlens array after heating was observed with a scanning electron microscope, the depth of the concave lens was about 6 μm, and the shape was well maintained while the curvature was slightly smooth.

In addition, regarding the transparency of the formed microlens array, the transmittance with respect to light having a wavelength of 400 nm is 82%, and the transmittance with respect to light having a wavelength of 450 nm is 94%. Was confirmed.

It is a schematic cross section which shows suitable one Embodiment of the photosensitive element for microlens arrays of this invention. It is a schematic cross section explaining one embodiment of a manufacturing method of a micro lens array of the present invention. It is a schematic cross section for demonstrating the manufacturing method of the conventional microlens array. It is a schematic cross section which shows the example of the photocuring part which has a desired curvature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Support film, 2 ... Photosensitive layer, 10 ... Base material, 20 ... Photosensitive layer, 22 ... Microlens array pattern, 23 ... Microlens array, 30 ... Photomask, 50 ... Microlens array, 100 ... Microlens array Photosensitive element, L ... actinic ray.

Claims (2)

On the support film, (a) a binder polymer having an acid value of 16 to 260 mg KOH / g and a weight average molecular weight of 1000 to 300,000, and (b) a photopolymerizable polymer having an ethylenically unsaturated group. Each component of the photosensitive resin composition, which is a negative photoresist material containing a saturated compound and (c) a photopolymerization initiator that generates free radicals by actinic rays, is uniformly dissolved or dispersed in a solvent. A step of preparing a photosensitive element for microlens array, comprising a photosensitive layer formed by applying the prepared coating solution to form a coating film, and drying and removing the solvent from the coating film ;
On one surface of a substrate transparent to a specific actinic ray, the microlens array photosensitive element is pressure-bonded with a pressure-bonding roll so that the photosensitive layer of the photosensitive element is in contact with the substrate. A photosensitive layer forming step of providing a photosensitive layer comprising a photosensitive resin composition;
An exposure step of irradiating the photosensitive layer with the actinic ray through a predetermined photomask from the opposite side of the surface of the substrate on which the photosensitive layer is provided;
A development step of forming a microlens array pattern by removing an unexposed portion of the photosensitive layer by development; and
A method for manufacturing a microlens array.   The method for producing a microlens array according to claim 1, wherein the pressure bonding in the photosensitive layer forming step is a heat pressure bonding at 30 to 180 ° C.

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