JP2003202438A - Radiation-curable composition for forming optical waveguide, optical waveguide and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide excellent in transmission properties and long-term stability of the properties and to provide a method for manufacturing the optical waveguide. <P>SOLUTION: In the optical waveguide comprising a lower clad layer, a core portion and an upper clad layer, at least one selected from the lower clad layer, the core portion and the upper clad layer is a cured body of a radiation- curable composition comprising (A) a copolymer (having alkali solubility) comprising (a) (5-50 wt.% component comprising) a radical polymerizable compound having a carboxy group, (b) (15-60 wt.% component comprising) a radial polymerizable compound having no carboxy group and (c) (5-80 wt.% component comprising) another radical polymerizable compound, (B) a compound having two or more polymerizable reactive groups per molecule and (C) a radiation polymerization initiator. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation-curable composition for forming an optical waveguide, which can form an optical waveguide having a waveguide shape suitable for a target shape and excellent transmission characteristics, and an optical waveguide formed using the composition. The present invention relates to a waveguide and a method for manufacturing an optical waveguide.

[0002]

2. Description of the Related Art With the advent of the multimedia era, optical waveguides have been attracting attention as optical transmission media due to the demand for large capacity and high speed of information processing in optical communication systems and computers. A silica-based waveguide is typical as such an optical waveguide, and is generally manufactured by the following steps. A lower clad layer made of a glass film is formed on a silicon substrate by a method such as a flame deposition method (FHD) or a CVD method. An inorganic thin film having a refractive index different from that of the lower clad layer is formed on the lower clad layer, and the thin film is patterned by reactive ion etching (RIE) to form a core portion. Further, the upper clad layer is formed by the flame deposition method. However, such a method of manufacturing a silica-based waveguide has problems that a special manufacturing apparatus is required and that manufacturing time is long.

Therefore, the inventors of the present invention irradiate a composition containing a radiation-polymerizable component with a predetermined amount of light,
It proposes a method of manufacturing an optical waveguide having excellent transmission characteristics by forming a core portion and the like by developing a non-exposed portion while radiation curing at a predetermined place. According to the method for producing an optical waveguide using such a radiation-curable composition, as compared with the conventional method for producing a silica-based waveguide, only by developing after irradiating a predetermined amount of light, a short time, Further, it is possible to obtain an advantage that the optical waveguide can be manufactured at low cost. However, it is difficult to form an optical waveguide having a fine width even if the above-mentioned method for producing an optical waveguide is performed using a radiation-curable composition that has been reported in the past, or excellent transmission characteristics are obtained. In some cases, it was not possible to form the existing optical waveguide.

[0004]

SUMMARY OF THE INVENTION The present invention has been made under the circumstances as described above, and has an excellent waveguide shape and an optical waveguide having excellent transmission characteristics, and such an optical waveguide. It is an object of the present invention to provide a method capable of efficiently producing

[0005]

The present invention provides (A) (a)
A structural unit derived from a radical polymerizable compound having a carboxyl group, (b) a structural unit derived from a radical polymerizable compound having a cyclic alkyl group and not having a carboxyl group, and (c) the above (a) and ( Copolymers having structural units derived from radically polymerizable compounds other than b) (hereinafter also referred to as "copolymer (A)"), (B) compounds having two or more polymerizable reactive groups in the molecule And (C) radiation polymerization initiator, at least the radiation curable composition for forming an optical waveguide (hereinafter, also referred to as “radiation curable composition”), the clad layer and the core portion. The present invention provides an optical waveguide, one of which is formed from the composition, and a method for producing the same.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A radiation-curable compound copolymer (A) for forming an optical waveguide has (a) a radically polymerizable compound having a carboxyl group, (b) a cyclic alkyl group and a carboxyl group. It can be obtained by radical-copolymerizing a radical-polymerizable compound that does not exist, (c) a radical-polymerizable compound other than (a) and (b) above in a solvent.

Examples of the radically polymerizable compound (a) having a carboxyl group include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; maleic acid,
Dicarboxylic acids such as fumaric acid, citraconic acid, mesaconic acid, and itaconic acid; 2-succinoloylethyl (meth) acrylate, 2-maleinoroylethyl (meth) acrylate, 2-hexahydrophthaloylethyl (meth) acrylate, etc. A methacrylic acid derivative having a carboxyl group and an ester bond can be used. These compounds can be used alone or in combination of two or more kinds. Among these, acrylic acid, methacrylic acid, 2-
Hexahydrophthaloylethyl (meth) acrylate is preferable, and acrylic acid and methacrylic acid are more preferable.

The proportion of the structural unit derived from the radically polymerizable compound having a carbonyl group in the copolymer (A) is 5 to 50% by weight, preferably 10 to 40% by weight.
Is. When the proportion of this structural unit is less than 5% by weight,
When this composition is cured by light irradiation and subjected to alkali development treatment, it becomes difficult to dissolve, and when used as the core part of an optical waveguide, the core shape as designed cannot be obtained and sufficient transmission characteristics cannot be obtained. . On the other hand, even if it exceeds 50% by weight, the shape as designed cannot be obtained.

Examples of the radically polymerizable compound (b) having a cyclic alkyl group and not a carbonyl group include cyclohexyl (meth) acrylate, 2-methylcyclohexyl (meth) acrylate and dicyclopentanyloxyethyl (meth). ) Acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate and the like. These compounds can be used alone or in combination of two or more kinds.
Among these, dicyclopentanyl (meth) acrylate is preferable.

The proportion of structural units derived from the radically polymerizable compound having a cyclic alkyl group and not having a carbonyl group in the copolymer (A) is 15 to 60% by weight,
It is preferably 20 to 50% by weight. If this ratio is less than 15% by weight, the molecular weight of the obtained copolymer does not sufficiently increase, and it becomes difficult to form a cured film of the present composition having a thickness of 20 μm or more, and a desired waveguide shape cannot be produced. On the other hand, when it exceeds 60% by weight, the solubility of the obtained copolymer in a solvent is lowered, and a problem occurs when the copolymer is prepared.

The other radically polymerizable compound (c) is
Mainly used for the purpose of appropriately controlling the mechanical properties and refractive index of the copolymer (A). Such other radically polymerizable compound (c) is preferably (meth)
Acrylic acid alkyl esters, (meth) acrylic acid aryl esters, dicarboxylic acid diesters, aromatic vinyls, conjugated diolefins, nitrile group-containing polymerizable compounds, chlorine-containing polymerizable compounds, amide bond-containing polymerizable compounds, Examples thereof include fatty acid vinyls. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate and the like (meth ) Acrylic acid alkyl ester; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate and benzyl (meth) acrylate; dicarboxylic acid diester such as diethyl maleate, diethyl fumarate, and itaconic acid diethyl ester; styrene, α-methylstyrene , M-methylstyrene, p-methylstyrene,
Aromatic vinyls such as vinyltoluene and p-methoxystyrene; conjugated diolefins such as 1,3-butadiene, isoprene and 1,4-dimethylbutadiene; nitrile group-containing polymerizable compounds such as acrylonitrile and methacrylonitrile; A chlorine-containing polymerizable compound such as vinyl or vinylidene chloride; an amide bond-containing polymerizable compound such as acrylamide or methacrylamide; a fatty acid vinyl such as vinyl acetate can be used. These compounds can be used alone or in combination of two or more, and among these, methyl (meth) acrylate, n-
Butyl (meth) acrylate, styrene, α-methylstyrene and the like are particularly preferable. The proportion of structural units derived from radically polymerizable compounds other than (a) and (b) in the copolymer (A) is 5 to 80% by weight, preferably 20 to 70% by weight.

Examples of the polymerization solvent used when synthesizing the copolymer (A) include alcohols such as methanol, ethanol, ethylene glycol, diethylene glycol and propylene glycol; tetrahydrofuran,
Cyclic ethers such as dioxane; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol Alkyl ethers of polyhydric alcohols such as monomethyl ether and propylene glycol monoethyl ether; Alkyl ethers of polyhydric alcohols such as ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate and propylene glycol ethyl ether acetate Le acetates; toluene, aromatic hydrocarbons such as xylene; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4
-Hydroxy-4-methyl-2-pentanone, ketones such as diacetone alcohol; ethyl acetate, butyl acetate, ethyl lactate, ethyl 2-hydroxypropionate,
Ethyl 2-hydroxy-2-methylpropionate, 2-
Ethyl hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-
Esters such as methyl 3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate and methyl 3-ethoxypropionate can be mentioned. Of these, cyclic ethers, polyhydric alcohol alkyl ethers, polyhydric alcohol alkyl ether acetates, ketones, and esters are preferable.

As the polymerization catalyst in the radical copolymerization, a usual radical polymerization initiator can be used, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethyl). Valeronitrile), 2,
Azo compounds such as 2'-azobis- (4-methoxy-2'-dimethylvaleronitrile); benzoyl peroxide, lauroyl peroxide, t-butylperoxypivalate, 1,1'-bis- (t-butylperoxy).
Examples thereof include organic peroxides such as cyclohexane, hydrogen peroxide and the like. When a peroxide is used as the radical polymerization initiator, a redox type initiator may be used in combination with a reducing agent. The average molecular weight of the obtained copolymer (A) is preferably 3,000 to 100,000. This molecular weight is defined in terms of polystyrene determined by gel permeation chromatography (GPC). When the molecular weight is less than 3,000, it becomes difficult to coat the composition with a predetermined film thickness on the substrate. On the other hand, if the molecular weight exceeds 100,000, the desired waveguide shape may not be obtained when the optical waveguide is formed from the composition.

The compound (B) having two or more polymerizable reactive groups in the molecule constituting the composition of the present invention is a compound capable of thermal polymerization and / or photopolymerization, and is a compound as shown below. Can be illustrated. Compounds having two or more ethylenically unsaturated groups in the molecule
Compounds: Compounds containing two or more (meth) acryloyl groups or vinyl groups in the molecule can be used. Examples of such a compound include ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4-butanediol di (meth).
Acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, bis (hydroxymethyl) tricyclodecane di (meth) ) Acrylate, di (meth) acrylate of diol which is an adduct of ethylene oxide or propylene oxide of bisphenol A, di (meth) acrylate of diol which is an adduct of hydrogenated bisphenol A ethylene oxide or propylene oxide, of bisphenol A Examples thereof include epoxy (meth) acrylate obtained by adding (meth) acrylate to diglycidyl ether, and diacrylate of polyoxyalkylenated bisphenol A. Furthermore, as the (meth) acrylate containing 3 or more (meth) acryloyl groups in the molecule, a compound in which 3 mol or more of (meth) acrylic acid is ester-bonded to a polyhydric alcohol having 3 or more hydroxyl groups, for example, Trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate Etc. Further, polyether acryl oligomer having polyester, polyester, polyurethane skeleton in the main chain, polyester acryl oligomer, polyurethane acryl oligomer, or polyepoxy acryl oligomer can also be used.

These commercially available products include Uupimer UV
SA1002, SA2007 (above, manufactured by Mitsubishi Chemical), Viscoat # 195, # 230, # 215, # 260, #
295, # 300, # 335HP, # 360, # 40
0, # 540, # 700, 3PA, GPT (above, manufactured by Osaka Organic Chemical Industry), light acrylate 4EG-A, 9
EG-A, NP-A, DCP-A, BP-4EA, BP
-4PA, PE-3A, PE-4A, DPE-6A (above, Kyoeisha Chemical Co., Ltd.), KAYARAD MANDA, H
X-220, HX-620, R-551, R-712,
R-604, R-684, PET-30, GPO-30
3, TMPTA, DPHA, D-310, D-330,
DPCA-20, -30, -60, -120 (all manufactured by Nippon Kayaku), Aronix M208, M210, M21
5, M220, M240, M305, M309, M31
0, M315, M325, M400, M1200, M6
100, M6200, M6250, M7100, M80
30, M8060, M8100, M8530, M856
0, M9050 (above, manufactured by Toagosei), Lipoxy VR-
77, VR-60, VR-90 (above, Showa High Polymer), Ebecryl 81, 83, 600, 629, 6
45, 745, 754, 767, 701, 755, 70
5, 770, 800, 805, 810, 830, 45
0, 1830, 1870 (above, made by Daicel UCB),
Beam sets 575, 551B, 502H, 102 (above, manufactured by Arakawa Chemical Co., Ltd.) and the like can be mentioned.

Having two or more cyclic ethers in the molecule
Compounds; among oxirane compounds, oxetane compounds, oxolane compounds and the like, compounds having two or more cyclic ethers in the molecule can be used. For example, 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-) as oxirane compounds
5,5-spiro-3,4-epoxy) cyclohexane-
Meta-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6)
-Methylcyclohexylmethyl) adipate, 3,4-
Epoxy-6-methylcyclohexyl-3 ', 4'-epoxy-6'-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexyl) Methyl) ether, ethylenebis (3,4-epoxycyclohexanecarboxylate), epoxidized tetrabenzyl alcohol, lactone-modified 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, lactone-modified epoxidized tetrahydrobenzyl Alcohol, cyclohexene oxide, bisphenol A diglycidyl ether, bisphenol F
Diglycidyl ether, bisphenol S diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol AD diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, Brominated bisphenol S
Diglycidyl ether, epoxy novolac resin, 1,
4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers; ethylene glycol, propylene glycol,
1 or 2 for aliphatic polyhydric alcohols such as glycerin
Polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides; Diglycidyl esters of aliphatic long-chain dibasic acids;
Monoglycidyl ethers of higher aliphatic alcohols; monoglycidyl ethers of polyether alcohols obtained by adding phenol, cresol, butylphenol or alkylene oxides to these; glycidyl esters of higher fatty acids; epoxidized soybean oil, epoxystearic acid Butyl, epoxy octyl stearate,
Examples include epoxidized linseed oil. As an oxetane compound, 3,7-bis (3-oxetanyl)
-5-oxa-nonane, 3,3 '-(1,3- (2-methylenyl) propanediylbis (oxymethylene)) bis- (3-ethyloxetane), 1,4-bis [(3-
Ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, 1,3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane , Ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyl bis (3-ethyl-3-oxetanylmethyl) ether, triethylene glycol bis (3-ethyl-3-oxetanylmethyl)
Ether, tetraethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tricyclodecanediyldimethylene (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris (3-
Ethyl-3-oxetanylmethyl) ether, 1,4-
Bis (3-ethyl-3-oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis (3 -Ethyl-3-oxetanylmethyl) ether and the like can be exemplified, and these can be used alone or in combination of two or more.

These commercially available products include Epolite 40
E, 100E, 70P, 1500NP, 100MF, 4
000, 3002 (above, Kyoeisha Chemical Co., Ltd.), Celoxide 2021, 2081, GT301, GT401, Epolide CDM, PB3600, Epofriend A100.
5, A1010, A1020 (all manufactured by Daicel Chemical Industries), Denacol 611, 612, 512, 521, 4
11, 421, 313, 321 (above, manufactured by Nagase Kasei)
Etc.

Further, it may be a compound containing at least one ethylenically unsaturated group and at least one cyclic ether reactive group in the molecule. For example,
Glycidyl (meth) acrylate, vinyl cyclohexene oxide, 4-vinyl epoxy cyclohexane,
3,4-epoxycyclohexylmethyl (meth) acrylate and the like can be mentioned. These compounds (B) may be used alone or in combination of two or more, and it is particularly preferable to use a compound containing two or more ethylenically unsaturated groups in the molecule. With respect to 100 parts by weight of the copolymer (A),
Preferably 30-150 parts by weight, more preferably 50-
It is 130 parts by weight. If it is less than 30 parts by weight, the desired waveguide shape may not be obtained when forming the optical waveguide, and if it exceeds 150 parts by weight, the compatibility with the copolymer (A) becomes poor and the composition is cured. Roughness may occur on the surface of the object.

The radiation polymerization initiator (C) constituting the composition of the present invention is an initiator capable of generating an active species capable of polymerizing the compound (B) by irradiation. Here, radiation means, for example, infrared rays, visible rays, ultraviolet rays and X-rays,
It means ionizing radiation such as electron rays, α rays, β rays and γ rays. Therefore, the radiation polymerization initiator which is the component (C) is required, and if necessary, a photosensitizer is further added. Radiation polymerization initiators can be broadly classified into those that decompose by light irradiation to generate radicals (radiation radical polymerization initiators) and those that generate cations (radiation cationic polymerization initiators).

Examples of the radiation radical polymerization initiator include acetophenone, acetophenone benzyl ketal,
1-hydroxycyclohexyl phenyl ketone, 2,2
-Dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3
-Methylacetophenone, 4-chlorobenzophenone,
4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1- (4-isopropylphenyl)-
2-hydroxy-2-methylpropan-1-one, 2-
Hydroxy-2-methyl-1-phenylpropane-1-
On, thioxanthone, diethylthioxanthone, 2-
Isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl]
-2-morpholino-propan-1-one, 2,4,6-
Trimethylbenzoyldiphenylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,
4,4-trimethylpentylphosphine oxide and the like can be mentioned.

Commercially available radiation radical polymerization initiators include, for example, Irgacure 184, 369, 651,
500, 819, 907, 784, 2959, CGI1
700, CGI1750, CGI11850, CG24
-61, Darocurl 116, 1173 (above, manufactured by Ciba Specialty Chemicals), Lucirin
Examples thereof include TPO, TPO-L (above, manufactured by BASF), and Yubecryl P36 (manufactured by UCB).

The radiation cationic polymerization initiator is as follows:
Examples of onium salts having a structure represented by the general formula (1)
You can This onium salt receives light
A compound that releases more Lewis acid.           [R¹² _a R¹³ _b R¹⁴ _c R¹⁵ _d W]^{+ m}[MX_{n + m}]^-m      (1) [In the formula, the cation is an onium ion, and W is S, S
e, Te, P, As, Sb, Bi, O, I, Br, Cl
Or N≡N and R¹², R¹³, R¹⁴And R ¹⁵Is the same
One or a different organic group, where a, b, c and d are
Each is an integer of 0 to 3, and (a + b + c + d) is W
Is equal to the valence of. M is a halide complex [MX_{n + m}]
Is a metal or metalloid that constitutes the central atom of
For example, B, P, As, Sb, Fe, Sn, Bi, Al, C
a, In, Ti, Zn, Sc, V, Cr, Mn, Co, etc.
How is it? X is a halogen atom such as F, Cl or Br
And m is the net charge of the halide complex ion
Where n is the valence of M. ] As a specific example of the onium ion in the general formula (1),
Is diphenyliodonium, 4-methoxydiphenyl
Iodonium, bis (4-methylphenyl) iodonium
Bis (4-tert-butylphenyl) iodonium,
Bis (dodecylphenyl) iodonium, triphenyl
Sulfonium, diphenyl-4-thiophenoxypheni
Rusulfonium, bis [4- (diphenylsulfonyl)
E) -phenyl] sulfide, bis [4- (di (4-
(2-hydroxyethyl) phenyl) sulfonio) -fu
[Phenyl] sulfide, η^Five-2,4- (cyclopentadi
Phenyl) [1,2,3,4,5,6- [eta])-(methyl ether
Chill) -benzene] -iron (1+) and the like.

In the general formula (1), the anion (M
Specific examples of X _{n + m} ) include tetrafluoroborate (BF ₄ ⁻ ), hexafluorophosphate (PF ₆ ⁻ ),
Hexafluoroantimonate (SbF ₆ ⁻ ), hexafluoroarsenate (AsF ₆ ⁻ ), hexachloroantimonate (SbCl ₆ ⁻ ), and the like can be mentioned. As an onium salt that can be used as a radiation cationic polymerization initiator, in the general formula (27), instead of [MX _{n + m} ], a general formula: [MX _n (OH) ⁻ ] (where M, X And n are as defined in relation to the general formula (1)), anion represented by general formula (1), perchlorate ion (ClO ₄ ⁻ ), trifluoromethanesulfonate ion (CF ₃ SO ^{3 −} ), fluorosulfonate ion (FS
O ₃ ^-), toluenesulfonic acid ion, trinitrobenzene sulfonic acid ion, and other onium salts having an anion such as trinitrotoluene sulfonate ion.

Commercially available radiation cationic polymerization initiators include, for example, UVI-6950, UVI-6970 and UV.
I-6974, UVI-6990 (above, Union Carbide Corporation), ADEKA OPTOMER SP-150, SP-1
51, SP-170, SP-171 (above Asahi Denka Kogyo KK), Irgacure 261 (above Ciba Geigy), CI-2481, CI-2624, CI-2
639, CI-2064 (above, Nippon Soda Co., Ltd.), C
D-1010, CD-1011, CD-1012 (above, Sartomer), DTS-102, DTS-10
3, NAT-103, NDS-103, TPS-10
2, TPS-103, MDS-103, MPI-10
3, BBI-101, BBI-102, BBI-103
(Midori Kagaku Co., Ltd.), Degacure K1
26 (manufactured by Degussa) and the like. The radiation polymerization initiators may be used alone or in combination of two or more to form the component (C).

The content ratio of the component (C) in the radiation curable composition of the present invention is usually 0.1 to 20 parts by weight when the total amount of the components (A) and (B) is 100 parts by weight. It is preferably 0.2 to 10 parts by weight, and particularly preferably 0.2 to 10 parts by weight. If the content ratio of the component (C) is less than 0.1 part by weight, curing may not proceed sufficiently and a problem may occur in the transmission characteristics of the optical waveguide. On the other hand, if it exceeds 20 parts by weight, the initiator may adversely affect long-term transmission characteristics.

In the radiation curable composition, it is also preferable to add a photosensitizer in combination with the above-mentioned radiation polymerization initiator. The reason for this is that the energy ray such as light can be more effectively absorbed by using the photosensitizer together. Such photosensitizers include thioxanthone, diethylthioxanthone and thioxanthone derivatives; anthraquinone, bromanthraquinone and anthraquinone derivatives; anthracene, bromanthracene and anthracene derivatives; perylene and perylene derivatives; xanthone, thioxanthone and thioxanthone derivatives; Examples include coumarin and ketocoumarin. For these photosensitizers, it is necessary to select a suitable sensitizer depending on the type of the initiator.

The radiation-curable composition of the present invention contains, in addition to the above-mentioned components, one polymerizable reaction in the molecule, for example, within the range that does not impair the characteristics of the radiation-curable composition of the present invention, if necessary. A compound or a polymer resin containing a group, for example, an epoxy resin, an acrylic resin, a polyamide resin, a polyamideimide resin, a polyurethane resin, a polybutadiene resin,
A polychloroprene resin, a polyether resin, a polyester resin, a styrene-butadiene block copolymer, a petroleum resin, a xylene resin, a ketone resin, a cellulose resin, a fluorine-based polymer, and a silicone-based polymer can be blended.

In addition to the above-mentioned components, various additives such as an antioxidant, an ultraviolet absorber, and
Light stabilizers, silane coupling agents, coating surface improvers, thermal polymerization inhibitors, leveling agents, surfactants, colorants, storage stabilizers, plasticizers, lubricants, fillers, fine particles, antiaging agents, wettability improvers Further, an antistatic agent or the like can be added if necessary. Here, as the antioxidant, for example, Irg
anox1010, 1035, 1076, 1222 (above, manufactured by Ciba Specialty Chemicals), Anti
gene P, 3C, FR, Sumilizer (manufactured by Sumitomo Chemical Co., Ltd.) and the like. Examples of the ultraviolet absorber include T
inuvin P, 234, 320, 326, 327,
328, 329, 213 (above, manufactured by Ciba Specialty Chemicals), Seesorb 102, 103, 1
10, 501, 202, 712, 704 (above, manufactured by Cipro Kasei) and the like, and examples of the light stabilizer include Ti.
Nuvin 292, 144, 622LD (above, Ciba Specialty Chemicals), Sanor LS77
0 (manufactured by Sankyo), Sumisorb TM-061 (manufactured by Sumitomo Chemical Co., Ltd.), and the like. Examples of the silane coupling agent include γ-aminopropyltriethoxysilane,
γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, as commercially available products SH6062, 6030 (above, manufactured by Toray Dow Corning Silicone), KBE903, 603, 403.
(Above, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like, examples of the coating surface improver include silicone additives such as dimethylsiloxane polyether, and commercially available products include DC-5.
7, DC-190 (above, manufactured by Dow Corning), SH-28PA, SH-29PA, SH-30PA, SH-1
90 (above, Toray Dow Corning Silicone),
KF351, KF352, KF353, KF354 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), L-700, L-7002, L
-7500, FK-024-90 (above, Nippon Unicar make) etc. are mentioned.

The radiation-curable composition of the present invention preferably further contains an organic solvent as the component (D). By adding the organic solvent, the storage stability of the radiation curable composition is improved and an appropriate viscosity can be obtained, so that an optical waveguide having a uniform thickness can be formed.

The types of organic solvents are as follows:
Although it can be selected within a range that does not impair the effect, it is usually an organic compound having a boiling point under atmospheric pressure in the range of 50 to 200 ° C., which is an organic compound that uniformly dissolves each constituent component. It is preferable. Specifically, the organic solvent used when preparing the copolymer of the component (A) can be used. Preferred organic solvents include alcohols, esters, and ketones, and more preferred organic solvents include propylene glycol monomethyl ether, ethyl lactate, methyl isobutyl ketone, methyl amyl ketone, toluene, xylene, and methanol. At least one solvent selected from the group is included.

The content of the organic solvent is 10 to 20 when the total weight of the components (A) to (C) is 100 parts by weight.
A value within the range of 0 parts by weight is preferable. This is because if the amount of the organic solvent added is less than 10 parts by weight, it may be difficult to adjust the viscosity of the radiation curable composition. On the other hand, if the amount of the organic solvent added is more than 200 parts by weight, it is sufficient. This is because it may be difficult to form an optical waveguide or the like having a thickness.

The radiation-curable composition of the present invention contains the above-mentioned components (A) and (B) in order to obtain the required refractive index for the part to be used, that is, the clad layer or the core part.
The compounding amount and the like are appropriately selected. When preparing the radiation curable composition of the present invention, its viscosity is adjusted to 1 to 10,000 cps.
A value within the range of (25 ° C.) is preferable, and 5 to
A value within the range of 8,000 cps (25 ° C.) is more preferable, and a value within the range of 10 to 5,000 cps (25 ° C.) is further preferable.

Optical Waveguide FIG. 1 is a sectional view showing the basic structure of an optical waveguide formed by applying the radiation curable composition of the present invention. This Figure 1
As shown in FIG. 2, the optical waveguide includes a substrate 12 extending in a direction perpendicular to the plane of the drawing (depth direction), a lower clad layer 13 formed on the surface of the substrate 12, and a lower clad layer 13
It is configured to include a core portion 15 formed on the lower cladding layer 13 having a specific width, and an upper cladding layer 17 laminated on the lower cladding layer 13 including the core portion 15. The core portion 15 is covered with the lower clad layer 13 and the upper clad layer 17 including the side portions thereof so that the waveguide loss is reduced, and is in a state of being buried as a whole.

In the optical waveguide having the above structure, the thicknesses of the lower clad layer, the upper clad layer, and the core part are not particularly limited. For example, the thickness of the lower clad layer is 1 to 200 μm. , The core portion has a thickness of 3 to 200 μm, and the upper clad layer has a thickness of 1 to 200
A value within the range of μm is preferable. Further, the width of the core portion is not particularly limited, but is preferably set to a value within the range of 1 to 200 μm, for example.

Further, it is necessary to make the refractive index of the core portion larger than that of both the lower and upper cladding layers. Therefore, wavelength 400 to 1,600 nm
, The refractive index of the core part is 1.420 to 1.6.
50, and the refractive indices of the lower clad layer and the upper clad layer are 1.40 to 1.
A value within the range of 648 is preferable. Further, it is preferable that the refractive index difference between the core portion and the clad layer is separated by 0.1% or more, and particularly, the refractive index of the core portion is set to a value that is at least 0.1% larger than the refractive index of the clad layer. preferable. In the optical waveguide of the present invention, at least one of the clad layer and the core portion is composed of a cured product of the radiation curable composition of the present invention. The clad layer and core portion which are not formed by the cured product of the radiation curable composition of the present invention can be formed by polyimide, polyacrylate, polycarbonate, polysiloxane or the like.

The optical waveguide is formed through the steps shown in FIG. That is, all of the lower clad layer 13, the core portion 15 and the upper clad layer (not shown) are formed by applying a radiation curable composition for forming these layers and then radiation curing. Preferably. In the following formation examples, the lower clad layer, the core portion and the upper clad layer, a lower layer composition which is a radiation-curable composition to obtain a cured product having a different refractive index after curing, a core composition, Also, description will be given assuming that it is formed from the composition for the upper layer. Then, using two or three types of radiation curable composition such that the difference in refractive index has an appropriate size, the radiation curable composition that gives a cured film having the highest refractive index as a core composition,
Other radiation curable compositions are preferably used as the lower layer composition and the upper layer composition. However, the lower layer composition and the upper layer composition may be the same radiation-curable composition, and it is usually the same composition, which is economically advantageous and facilitates production control. Therefore, it is more preferable.

Preparation of Substrate First, as shown in FIG. 2A, a substrate 12 having a flat surface is prepared. The type of the substrate 12 is not particularly limited, but for example, a silicon substrate or a glass substrate can be used.

Step of forming lower clad layer This is a step of forming the lower clad layer 13 on the surface of the prepared substrate 12. Specifically, as shown in FIG. 2B, the lower layer composition is applied to the surface of the substrate 12 and dried or prebaked to form a lower layer thin film. And
The lower clad layer 13 can be formed by curing the lower layer thin film by irradiating it with radiation. In the step of forming the lower clad layer 13, it is preferable to irradiate the entire surface of the thin film with radiation to cure the entire surface.

Here, as a method for applying the lower layer composition, a spin coating method, a dipping method, a spraying method, a bar coating method, a roll coating method, a curtain coating method, a gravure printing method, a silk screen method, an ink jet method or the like. The method of can be used. Among these, the spin coating method is more preferable because a lower layer thin film having a particularly uniform thickness can be obtained. Further, in order to appropriately correspond the rheological properties of the composition for the lower layer to the coating method, it is preferable to add various leveling agents, thixotropic agents, fillers, organic solvents, surfactants and the like as necessary. . In addition, the lower layer thin film made of the lower layer composition has a thickness of 50 to 20 for the purpose of removing an organic solvent after coating.
Prebaking at a temperature of 0 ° C. is preferred. The coating method in the formation process of the lower clad layer, the improvement of the rheological properties, and the like are also applicable to the formation process of the core portion and the formation process of the upper clad layer described later.

The irradiation dose of the radiation for forming the lower clad layer is not particularly limited either, but the wavelength is 200 to 390 nm and the illuminance is 0.1 to 500 mW.
Radiation dose of 10 / 5,000 mJ /
It is preferable to irradiate and expose so as to be cm 2. Visible light, ultraviolet rays, infrared rays, X-rays, α-rays, β-rays, γ-rays and the like can be used as the type of radiation to be applied, and ultraviolet rays are particularly preferable. As a radiation (ultraviolet) irradiation device, for example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, an excimer lamp, or the like is preferably used. Further, after the exposure, it is preferable to further perform a heat treatment (hereinafter referred to as “post bake”) so that the entire surface of the coating film is sufficiently cured. This heating condition varies depending on the composition of the radiation curable composition, the type of additives, etc., but is usually 30 to 40.
0 ° C., preferably 50 to 300 ° C., for example 5 minutes to 7
The heating condition may be 2 hours. The radiation dose, type, radiation (ultraviolet) irradiating device, and the like in the lower clad layer forming step are also applicable to the core portion forming step and the upper clad layer forming step, which will be described later.

Formation of Core Portion Next, as shown in FIG. 2C, a core composition is applied onto the lower clad layer 13 and dried or further prebaked to form a core thin film 14. After that, Figure 2
As shown in (d), with respect to the upper surface of the core thin film 14,
It is preferable to irradiate the radiation 16 according to a predetermined pattern, for example, through a photomask 19 having a predetermined line pattern. As a result, only the portion irradiated with the radiation is cured, and thus the uncured portion other than that is removed by development, so that the patterned curing on the lower cladding layer 13 is performed as shown in FIG. The core portion 15 made of a film can be formed.

Further, the irradiation of the radiation 16 to the core thin film 14 for forming the core portion 15 is performed according to the photomask 19 having a predetermined pattern, and then the unexposed portion is developed with a developing solution. The uncured unnecessary portion is removed, whereby the core portion 15 is formed. As described above, the method of irradiating the radiation according to the predetermined pattern is not limited to the method of using the photomask composed of the radiation transmitting portion and the non-transmissive portion.
The following methods a to c are included. a. A method utilizing electro-optically forming means for forming a mask image consisting of a radiation transmitting region and a radiation opaque region according to a predetermined pattern, using the same principle as that of a liquid crystal display device. b. Using a light guide member that bundles many optical fibers,
A method of irradiating radiation through an optical fiber corresponding to a predetermined pattern in the light guide member. c. A method of irradiating a radiation curable composition while scanning laser light or converging radiation obtained by a condensing optical system such as a lens and a mirror. After the exposure, it is preferable to perform heat treatment (hereinafter referred to as “PEB”) in order to accelerate the curing of the exposed portion. The heating conditions vary depending on the composition of the radiation curable composition, the type of additives, etc., but are usually 30 to 20.
The temperature is 0 ° C, preferably 50 to 150 ° C.

In this way, the thin film which is pattern-exposed according to a predetermined pattern and selectively cured can be developed by utilizing the difference in solubility between the cured portion and the uncured portion. . Therefore, after pattern exposure,
By removing the uncured portion and leaving the cured portion, as a result, the core portion can be formed.

Here, as a developing solution, an organic solvent or sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propyl is used. Amine, triethylamine, methyldiethylamine, N-methylpyrrolidone, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, choline, pyrrole, piperidine, 1,
8-diazabicyclo [5.4.0] -7-undecene,
It is possible to use an alkaline aqueous solution containing an alkali such as 1,5-diazabicyclo [4.3.0] -5-nonane. When an alkali water-soluble substance is used, its concentration is usually 0.05 to 25% by weight, preferably 0.1.
It is preferable to set the value within the range of to 3.0% by weight. It is also preferable to add a suitable amount of a water-soluble organic solvent such as methanol or ethanol or a surfactant to such an alkaline aqueous solution and use it as a developing solution.

The developing time is usually 30 to 600 seconds, and a known method such as a puddle method, a dipping method and a shower developing method can be adopted as the developing method. When an organic solvent is used as a developing solution, it is air-dried as it is. When an alkaline aqueous solution is used, washing with running water is performed for, for example, 30 to 90 seconds, and air-dried with compressed air, compressed nitrogen, or the like. The patterned film is formed by removing the water content. Then, in order to further harden the patterning portion, for example, with a heating device such as a hot plate or an oven, 30
Post-baking is performed at a temperature of ~ 400 ° C for 5 to 600 minutes to form a hardened core portion.

Formation of Upper Cladding Layer Next, the lower cladding layer 13 on which the core portion 15 is formed is formed.
The composition for the upper layer is applied to the surface of, and dried or prebaked to form a thin film for the upper layer. By irradiating the upper layer thin film with radiation to cure it, the upper clad layer 17 can be formed as shown in FIG. The upper clad layer obtained by irradiation with radiation is preferably post-baked as described above, if necessary. By post-baking, the upper clad layer having excellent hardness and heat resistance can be obtained.

[0047]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples.

[Preparation of Radiation Curable Composition] Preparation Example of Copolymer (A) for Core Part 1 A flask equipped with a dry ice / methanol reflux was replaced with nitrogen, and then 2,2′-as a polymerization initiator. 1.3 g of azobisisobutyronitrile and 53.8 g of ethyl lactate as an organic solvent were charged and stirred until the polymerization initiator was dissolved. Subsequently, 6.7 g of methacrylic acid, 15.7 g of dicyclopentanyl methacrylate and 9.0 of styrene.
After charging g and 13.5 g of n-butyl acrylate, gentle stirring was started. After that, increase the temperature of the solution to 8
The temperature was raised to 0 ° C., and polymerization was carried out at this temperature for 4 hours. Then, the reaction product was dropped into a large amount of hexane to solidify the reaction product. Further, the coagulated product was redissolved in tetrahydrofuran of the same weight and coagulated again with a large amount of hexane. This redissolution-coagulation operation was performed three times in total, and the obtained coagulated product was vacuum dried at 40 ° C. for 48 hours to obtain the target copolymer A-1.

Preparation Example 2 of Copolymer (A) for Clad Layer
The flask equipped with a dry ice / methanol reflux was replaced with nitrogen, and then 2,2′-azobisdimethylvaleronitrile was added to 0.5 as a polymerization initiator.
g, 54.3 g of ethyl lactate was charged as an organic solvent,
The mixture was stirred until the polymerization initiator was dissolved. Subsequently, 4.5 g of methacrylic acid, 9.0 g of dicyclopentanyl methacrylate, 20.4 g of methyl methacrylate, and n
After charging 11.3 g of -butyl acrylate, gentle stirring was started. Then, the temperature of the solution was raised to 80 ° C., and polymerization was carried out at this temperature for 4 hours. Then, the reaction product was dropped into a large amount of hexane to solidify the reaction product. Further, the coagulated product was redissolved in tetrahydrofuran of the same weight and coagulated again with a large amount of hexane. This redissolution-coagulation operation was carried out three times in total, and then the coagulated product obtained was
Vacuum-dried at 0 ° C. for 48 hours to obtain the target copolymer A-2
Got

Preparation Example 3 of Copolymer (A) for Core Part After replacing a flask equipped with a dry ice / methanol reflux with nitrogen, 1,2'-azobisisobutyronitrile was added as a polymerization initiator to 1. 3 g and 53.8 g of ethyl lactate as an organic solvent were charged and stirred until the polymerization initiator was dissolved. Subsequently, after charging 6.7 g of methacrylic acid, 15.7 g of isobornyl methacrylate, 9.0 g of styrene, and 13.5 g of n-butyl acrylate,
The stirring was started gently. Then, the temperature of the solution was raised to 80 ° C., and polymerization was carried out at this temperature for 4 hours. Then, the reaction product was dropped into a large amount of hexane to solidify the reaction product. Further, the coagulated product was redissolved in tetrahydrofuran of the same weight and coagulated again with a large amount of hexane. This re-dissolution-coagulation operation was performed three times in total, and the obtained coagulated product was vacuum dried at 40 ° C. for 48 hours to obtain the target copolymer A.
-3 was obtained.

Preparation Example 4 of Copolymer (A) for Core Part (Comparative
Comparative Example) A flask equipped with a dry ice / methanol reflux was purged with nitrogen, and then charged with 1.3 g of 2,2′-azobisisobutyronitrile as a polymerization initiator and 53.8 g of ethyl lactate as an organic solvent. The mixture was stirred until the polymerization initiator was dissolved. Subsequently, after charging 17.9 g of dicyclopentanyl methacrylate, 9.1 g of styrene, and 17.9 g of n-butyl acrylate, gentle stirring was started. Then, the temperature of the solution was raised to 80 ° C., and polymerization was carried out at this temperature for 4 hours. Then, the reaction product was dropped into a large amount of hexane to solidify the reaction product. further,
Redissolved in tetrahydrofuran of the same weight as this coagulated product,
It was solidified again with a large amount of hexane. This redissolution-coagulation operation was performed three times in total, and the obtained coagulated product was vacuum dried at 40 ° C. for 48 hours to obtain the target copolymer A-4.

Preparation Example 5 of Clad Layer Copolymer (A)
(Comparative Example) A flask equipped with a dry ice / methanol reflux was purged with nitrogen, and then charged with 0.5 g of 2,2'-azobisdimethylvaleronitrile as a polymerization initiator and 54.3 g of ethyl lactate as an organic solvent. The mixture was stirred until the polymerization initiator was dissolved. Subsequently, 4.5 g of methacrylic acid, 24.9 g of methyl methacrylate, and 15.8 g of n-butyl acrylate were charged, and then gentle stirring was started. Then, the temperature of the solution was raised to 80 ° C., and polymerization was carried out at this temperature for 4 hours. Then, the reaction product was dropped into a large amount of hexane to solidify the reaction product. Further, the coagulated product was redissolved in tetrahydrofuran of the same weight and coagulated again with a large amount of hexane. This redissolution-coagulation operation was performed three times in total, and the obtained coagulated product was vacuum dried at 40 ° C. for 48 hours to obtain the target copolymer A-5.

Preparation of Radiation Curable Composition J-1 Polyester polyfunctional acrylate (M8100 manufactured by Toagosei Co., Ltd.), which is a polymerization reactive composition, was added to 32.0 parts by weight of the above-mentioned copolymer A-1. 0 parts by weight, 6.5 parts by weight of trimethylolpropane triacrylate, and Irgcure. 369
(Ciba Specialty Chemicals) 3.0 parts by weight and ethyl lactate 48.5 parts by weight were added and uniformly mixed to obtain a radiation curable composition J-1.

Preparation of Radiation-Curable Composition J-2 16. To 27.7 parts by weight of the above-mentioned copolymer A-2, a polyester polyfunctional acrylate (M8100 manufactured by Toagosei Co., Ltd.), which is a polymerization-reactive composition, was used. 6 parts by weight, 11.1 parts by weight of trimethylolpropane triacrylate,
A radiation radical polymerization initiator, Irgcure. 36
3.0 (manufactured by Ciba Specialty Chemicals) and 41.6 parts by weight of ethyl lactate were added and uniformly mixed to obtain a radiation curable composition J-2.

Preparation of Radiation Curable Composition J-3 13.5 parts by weight of a polymerization-reactive composition, pentaerythritol triacrylate, was added to 35.0 parts by weight of the above-described copolymer A-3, and radiation radical polymerization was performed. The initiator Irgcure. A radiation curable composition J-3 was obtained by adding 3.0 parts by weight of 819 (manufactured by Ciba Specialty Chemicals) and 48.5 parts by weight of ethyl lactate and mixing them uniformly.

Preparation of Radiation-Curable Composition J-4 To 32.0 parts by weight of the above-mentioned copolymer A-1 was added a polyfunctional oxirane compound (Eporide GT301 manufactured by Daicel Chemical Industries) as a polymerization-reactive composition. By adding 16.5 parts by weight, 3.0 parts by weight of a radiation cationic polymerization initiator SP170 (manufactured by Asahi Denka Co., Ltd.) and 48.5 parts by weight of ethyl lactate, and uniformly mixing, a radiation curable composition J -4 was obtained.

Preparation of Radiation Curable Composition J-5 Dipentaerythritol hexaacrylate (DPHA manufactured by Nippon Kayaku), which is a polymerization-reactive composition, was added to 35.0 parts by weight of the above-mentioned copolymer A-1. 13.5 parts by weight,
A radiation radical polymerization initiator, Irgcure. 36
3.0 (manufactured by Ciba Specialty Chemicals) and 48.5 parts by weight of ethyl lactate were added and uniformly mixed to obtain a radiation curable composition J-5.

Preparation of Radiation Curable Composition J-6 (Comparison
Example) With respect to 32.0 parts by weight of the above-mentioned copolymer A-4, 10.0 parts by weight of polyester polyfunctional acrylate (M8100 manufactured by Toagosei Co., Ltd.), which is a polymerization-reactive composition, and 6 parts of trimethylolpropane triacrylate were used. .5 parts by weight, Irgcure. 369
A radiation curable composition J-6 was obtained by adding 3.0 parts by weight of Ciba Specialty Chemicals and 48.5 parts by weight of ethyl lactate and mixing them uniformly.

Preparation of Radiation Curable Composition J-7 (Comparison
Example) To 27.7 parts by weight of the above-mentioned copolymer A-5, 16.6 parts by weight of a polyester polyfunctional acrylate (M8100 manufactured by Toagosei Co., Ltd.), which is a polymerization-reactive composition, and 11 parts of trimethylolpropane triacrylate were used. .1 part by weight,
A radiation radical polymerization initiator, Irgcure. 36
3.0 (manufactured by Ciba Specialty Chemicals) and 41.6 parts by weight of ethyl lactate were added and uniformly mixed to obtain a radiation curable composition J-7.

Example 1 (1) Formation of Optical Waveguide Formation of Lower Clad Layer The radiation curable composition J-2 was applied on the surface of a silicon substrate.
Apply with a spin coater and use a hot plate for 120
Prebaking was performed under the conditions of 10 ° C. and 10 minutes. Then, a coating film composed of the radiation curable composition J-2 was coated with a wavelength of 365 nm,
Ultraviolet rays having an illuminance of 20 mW / cm @ 2 were irradiated for 30 seconds to cure the radiation. Then, this cured film is post-baked under the condition of 200 ° C. for 1 hour to obtain a thickness of 50 μm.
m of the lower clad layer.

Formation of Core Part Next, the radiation curable composition J-1 was coated on the lower clad layer by a spin coater and prebaked at 120 ° C. for 10 minutes using a hot plate. afterwards,
A 50 μm-thick coating film made of the radiation-curable composition J-1 is irradiated with ultraviolet rays having a wavelength of 365 nm and an illuminance of 20 mW / cm 2 for 30 seconds through a photomask having a line-shaped pattern having a width of 50 μm to form a coating film. Was radiation cured.
Next, PEB was performed on the irradiated coating film at 100 ° C. for 1 minute. Next, the radiation-cured substrate having the coating film was dipped in a developer containing a 1.8% aqueous solution of tetramethylammonium hydroxide (TMAH) to dissolve the unexposed portion of the coating film. Then, post-baking was performed under the condition of 200 ° C. for 1 hour to form a core portion having a linear pattern with a width of 10 μm.

Formation of Upper Clad Layer Next, the radiation curable composition J-2 was applied on the upper surface of the lower clad layer having a core portion by a spin coater and prebaked at 120 ° C. for 10 minutes using a hot plate. . Then, the coating film made of the radiation curable composition J-2 was irradiated with ultraviolet rays having a wavelength of 365 nm and an illuminance of 20 mW / cm 2 for 30 seconds to form an upper clad layer having a thickness of 50 μm. After that, this upper clad layer
Post-baking was performed at 200 ° C. for 6 hours.

Examples 2 to 4 and Comparative Examples 1 to 3 Except that the composition shown in Table 2 was used instead of the composition described in Example 1 for the lower clad layer, the core portion and the upper clad layer. An optical waveguide was formed by the same method as all the methods described above.

(2) Accuracy of optical waveguide shape Core shape designed by the above-mentioned method (height 50 μm ×
With respect to the line width of 50 μm), the case where the core height and the core width are both 50 ± 5 μm is defined as “◯”, and the case where the shape is more than or equal to the following is defined as “x”. The results are shown in Table 2.

(3) Evaluation of Transmission Loss of Optical Waveguide With respect to the optical waveguide including the lower clad layer, the core portion and the upper clad layer thus obtained, the wavelength 82
Light of 4 nm was made incident from one end. Then, by measuring the amount of light emitted from the other end, the waveguide loss per unit length was obtained by the cutback method. The results are shown in Table 2.

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

By using the radiation-curable composition of the present invention, it becomes possible to mold an optical waveguide extremely easily, in a short time and with high precision. Further, the optical waveguide formed of the radiation curable composition of the present invention was able to obtain low transmission loss. As described above, according to the method for manufacturing an optical waveguide of the present invention, the optical waveguide can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an optical waveguide of the present invention.

2A to 2E are partial process diagrams of a method for manufacturing an optical waveguide.

[Explanation of symbols]

10 Optical waveguide 12 substrates 13 Lower clad layer 14 core thin film 15 core part 16 Radiation 17 Upper clad layer 18 Ridge 19 Photomask

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuichi Eriyama             2-11-21 Tsukiji, Chuo-ku, Tokyo J             Within SRL Co., Ltd. F-term (reference) 2H047 PA01 PA02 PA22 PA24 PA28                       QA05 TA43

Claims (6)

[Claims] 1. A structural unit derived from (A) (a) a radically polymerizable compound having a carboxyl group, and (b) a structural unit derived from a radically polymerizable compound having a cyclic alkyl group and having no carboxyl group. And (c) a copolymer having a structural unit derived from a radically polymerizable compound other than the above (a) and (b), (B) a compound having two or more polymerizable reactive groups in the molecule, and (C ) A radiation curable composition for forming an optical waveguide, which comprises a radiation polymerization initiator. 2. The radiation curable composition for forming an optical waveguide according to claim 1, wherein the polymerizable reactive group of the component (B) is an ethylenically unsaturated group. 3. The radiation-curable composition for forming an optical waveguide according to claim 1, which further contains an organic solvent as the component (D). 4. An optical waveguide, wherein at least one of the clad layer and the core portion is composed of a cured product of a radiation curable composition containing the following components (A) to (C). (A) (a) a structural unit derived from a radically polymerizable compound having a carboxyl group, (b) a structural unit derived from a radically polymerizable compound having a cyclic alkyl group and having no carboxyl group, and (c) Copolymer (B) having a structural unit derived from a radically polymerizable compound other than (a) and (b) (C) Radiation polymerization initiator having two or more polymerizable reactive groups in the molecule 5. The refractive index difference between the clad layer and the core portion is 0.
It is 1% or more, The optical waveguide of Claim 4 characterized by the above-mentioned. 6. A step of forming a lower clad layer, a step of forming a core portion, and a step of forming an upper clad layer, wherein at least one of these steps is
A method of manufacturing an optical waveguide, comprising a step of radiation-curing the radiation-curable composition according to claim 1.