Composition for self-forming optical waveguide, self-forming optical waveguide, and method for manufacturing self-forming optical waveguide

Abstract

The present invention addresses the problem of providing a composition for a self-forming optical waveguide capable of forming a self-forming optical waveguide having high connection efficiency. The present invention also addresses the problem of providing a self-forming optical waveguide having high connection efficiency, and a method for manufacturing a self-forming optical waveguide.　This composition for a self-forming optical waveguide includes a compound having a thio (meth)acrylate group.

Description

Composition for self-forming optical waveguide, self-forming optical waveguide, method for producing self-forming optical waveguide

[0001] The present invention relates to a composition for a self-written optical waveguide, a self-written optical waveguide, and a method for producing an optical waveguide.

[0002] In fields such as optical communications, optical information processing, electronic devices, and optical equipment that utilize optical technology, development of optical waveguides used to connect various optical devices is progressing. Optically connecting various optical devices using optical waveguides requires extremely high-precision alignment of optical axes. Conventionally, such alignment work has been performed manually or using high-precision equipment, but it has been problematic in terms of labor and time required. From this perspective, self-written optical waveguide technology, in which an optical waveguide is manufactured by self-forming the core of the optical waveguide from a photocurable resin, has been studied. A self-written optical waveguide can be formed at the end of an optical fiber or the like by, for example, immersing the end of an optical fiber or the like in the photocurable resin and irradiating light from the optical fiber or the like into the photocurable resin to gradually harden the photocurable resin.

[0003] For example, Patent Document 1 describes a core-forming composition for a self-forming optical waveguide, in which a composition containing a (meth)acrylate having a COOH group and a photopolymerization initiator is used as a material for photo-curing the core of the self-forming optical waveguide, and also describes a self-forming optical waveguide in which the core is a cured product obtained by photo-curing the core-forming composition (see Claims 1, 15, etc.).

[0004] JP 2011-034054 A

[0005] The present inventors attempted to form a self-written optical waveguide using the composition for a self-written optical waveguide described in Patent Document 1, and found that the connection efficiency of the formed self-written optical waveguide was insufficient and there was room for improvement.

[0006] An object of the present invention is to provide a composition for a self-written optical waveguide that can form a self-written optical waveguide with high connection efficiency. Another object of the present invention is to provide a self-written optical waveguide with high connection efficiency and a method for manufacturing a self-written optical waveguide with high connection efficiency.

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that the above-mentioned problems can be solved by the following configurations. [1] A self-forming optical waveguide composition containing a compound having a thio(meth)acrylate group. [2] The self-forming optical waveguide composition according to [1], in which the compound has two or more thio(meth)acrylate groups in one molecule. [3] The self-forming optical waveguide composition according to [1] or [2], further containing a polymerizable compound different from the compound. [4] The self-forming optical waveguide composition according to [3], in which the refractive index of the polymerizable compound is lower than the refractive index of the compound having a thio(meth)acrylate group. [5] The self-forming optical waveguide composition according to any one of [1] to [4], in which the viscosity of the self-forming optical waveguide composition at 25°C is 500 to 100,000 mPa·s. [6] A self-forming optical waveguide produced using the self-forming optical waveguide composition according to any one of [1] to [5]. [7] A method for producing a self-forming optical waveguide using the self-forming optical waveguide composition according to [3] or [4], the method comprising the steps of preparing a first optical element, a second optical element, and the self-forming optical waveguide composition disposed between the first optical element and the second optical element, irradiating light from at least one of the first optical element and the second optical element to cure the self-forming optical waveguide composition and form a core portion, and exposing uncured components in the self-forming optical waveguide composition to form a clad portion, thereby forming a self-forming optical waveguide including the core portion and the clad portion.

[0008] According to the present invention, a composition for a self-written optical waveguide capable of forming a self-written optical waveguide with high connection efficiency can be provided. Furthermore, according to the present invention, a self-written optical waveguide with high connection efficiency and a method for manufacturing a self-written optical waveguide with high connection efficiency can be provided.

[0009] Fig. 1 is a schematic diagram showing an example of a method for producing a self-written optical waveguide. Fig. 2 is a schematic diagram showing an example of a method for producing a self-written optical waveguide. Fig. 3 is a schematic diagram showing an example of a method for producing a self-written optical waveguide. Fig. 4 is a schematic diagram showing another example of a method for producing a self-written optical waveguide. Fig. 5 is a schematic diagram showing another example of a method for producing a self-written optical waveguide. Fig. 6 is a schematic diagram showing another example of a method for producing a self-written optical waveguide.

[0010] The present invention will be described in detail below. The following description of the components may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In each drawing, the scale of the components may differ from the actual scale in order to make it easier to see and explain.

[0011] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the upper and lower limits. In the numerical ranges described in stages in this specification, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit described in a certain numerical range may be replaced with a value shown in the Examples. In this specification, each component may be a single substance corresponding to the component, or two or more substances may be used in combination. Here, when two or more substances are used in combination for each component, the content of that component refers to the total content of the substances used in combination, unless otherwise specified.

[0012] In this specification, "(meth)acrylate" is a notation representing "acrylate" or "methacrylate", "(meth)acrylic" is a notation representing "acrylic" or "methacrylic", and "(meth)acryloyl" is a notation representing "acryloyl" or "methacryloyl". In this specification, the number average molecular weight (Mn) and weight average molecular weight (Mw) are values ​​measured by size exclusion chromatography (gel permeation chromatography) using polystyrene as a standard substance.

[0013] As used herein, "orthogonal" or "perpendicular" refers to a range of 90°±5°, and "parallel" refers to a range of 0°±5°. Similarly, unless otherwise specified, angles refer to angles that are within a range of 5 degrees from the exact angle. The difference in the angle is preferably within 4 degrees, and more preferably within 3 degrees. As used herein, visible light refers to light with wavelengths visible to the human eye, in the wavelength range of 380 to 780 nm. Ultraviolet light (UV) refers to light with a wavelength range of 10 nm or more and less than 380 nm, and infrared light (IR) refers to light with a wavelength range exceeding 780 nm.

[0014] [Self-Writing Optical Waveguide Composition] The self-forming optical waveguide composition according to the present invention (hereinafter also referred to as "the composition") contains a compound having a thio(meth)acrylate group (hereinafter also referred to as "specific compound").

[0015] The present composition enables the formation of self-forming optical waveguides with high connection efficiency. When forming an optical waveguide by self-organization using a composition containing a reactive compound, it is desirable for the viscosity of the composition to be within a predetermined range from the viewpoint of ease of handling. While increasing the refractive index of an optical waveguide is one effective means of improving the connection efficiency of an optical waveguide, increasing the refractive index of the optical waveguide often increases the viscosity of the reactive compound used to self-form the optical waveguide, affecting its handleability. In response to this problem, the present inventors formed an optical waveguide by self-organization using a composition containing a compound having a thio(meth)acrylate group. They found that an optical waveguide with a high refractive index could be formed while maintaining a low viscosity of the composition, thereby enabling the formation of a self-forming optical waveguide with high connection efficiency, thereby completing the present invention. The composition of the present composition is described in more detail below.

[0016] <Specific Compound> The present composition contains a specific compound having a thio(meth)acrylate group. The thio(meth)acrylate group is represented by the following formula (1): CH ２ =CR-C(=O)-S-* (1) In formula (1), R represents a hydrogen atom or a methyl group, and * represents the bonding position.

[0017] The specific compound has at least one thio(meth)acrylate group in one molecule. The number of thio(meth)acrylate groups in the specific compound may be one or two or more. The specific compound is highly reactive and prone to phase separation when forming an optical waveguide (core portion) using the composition. The concentration of the highly reactive specific compound in the core portion facilitates further increasing the refractive index, making it easier to fabricate an all-solid-state self-forming optical waveguide. The upper limit of the number of thio(meth)acrylate groups in the specific compound is not particularly limited, and may be 12 or less, 6 or less, or 4 or less.

[0018] The specific compound may be, for example, a compound represented by the following formula (2): (CH ２ =CR-C(=O)-S) ｎ -L (2) In formula (2), each R independently represents a hydrogen atom or a methyl group. L represents an optionally substituted aliphatic group, an optionally substituted alicyclic group, an optionally substituted aromatic group, or an optionally substituted heterocyclic group. The aliphatic group and the alicyclic group represented by L may have at least one linking group selected from an ether group (-O-) and a sulfide group (-S-) between two carbon atoms. n represents an integer of 1 or greater.

[0019] In terms of increasing the refractive index of the optical waveguide, L in formula (2) is preferably an aliphatic group having at least one sulfide group between two carbon atoms, which may have a substituent, or an aromatic group, which may have a substituent. The preferred range of n is the same as the preferred range of the number of thio(meth)acrylate groups in one molecule described above.

[0020] The compound represented by formula (2) can be produced, for example, by a dehalogenation-dehydrogenation reaction between a thiol compound represented by formula (3) and a (meth)acrylic acid halide. ｎ -L (3) In formula (3), L and n are the same as L and n in formula (2), including preferred embodiments.

[0021] The thiol compound represented by formula (3) may further have a hydroxy group in addition to the mercapto group. Specific examples of the thiol compound represented by formula (3) are listed below. Specific examples of L in formula (2) include groups derived from the following compounds:

[0022] Among the thiol compounds represented by formula (3), specific examples of monothiol compounds having one thiol group include methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl mercaptan, amyl mercaptan, hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, undecyl mercaptan, dodecyl mercaptan, tridecyl mercaptan, tetradecyl mercaptan, cetyl mercaptan, octadecyl mercaptan, allyl mercaptan, 2-butene-1-thiol, 1-butene-4-thiol, methallyl mercaptan, 1-pentenyl mercaptan, 2-i-pentenyl mercaptan, oleyl mercaptan, cyclopentyl mercaptan, cyclohexyl mercaptan, cyclopent ... ethyl mercaptan, cycloheptyl mercaptan, 3-methylcyclopentyl methyl mercaptan, 2-methylcyclohexyl mercaptan, 3-methylcyclohexyl mercaptan, 4-methylcyclohexyl mercaptan, 3-methylcyclohexyl methyl mercaptan, 1-cyclopentyl mercaptan, 2-cyclohexenyl mercaptan, β-cyclohexylethyl mercaptan, 2,2,6,6-tetramethylcyclohexyl mercaptan, ε-cyclohexylamyl mercaptan, cholesteryl mercaptan, furfuryl mercaptan, methylfurfuryl mercaptan, 2-mercaptothiophene, 3-mercaptothiophene, 2-ethyl-3-mercaptothiophene, thiophenol, thiocresol, ethylthiophenol, 2,4-thioxyleneol, 2,5-thiooxirenol, propylthiophenol, allylthiophenol, 2-allyl-4-methylthiophenol, phenylthiophenol, chlorothiophenol, bromothiophenol, iodothiophenol, nitrothiophenol, trinitrothiophenol, dinitrothiophenol, nitrobromothiophenol, nitrochlorothiophenol, methylsulfonylthiophenol, benzenethiol, benzyl mercaptan, nitrobenzyl mercaptan, α-phenylethyl mercaptan, β-phenylethyl mercaptan, α-phenylpropyl mercaptan, γ-phenylpropyl mercaptan, β-phenylpropyl mercaptan, β-phenyl-i-propyl mercaptan, D-β-phenylbutyl mercaptan, ε-phenylamyl mercaptan, α,β-diphenylethyl mercaptan, methylbenzyl mercaptan, 2-nitro-p-tolyl mercaptan, α-(o-tolyl)benzyl mercaptan, α-(p-tolyl)benzyl mercaptan, chlorobenzyl mercaptan, dichlorobenzyl mercaptan, bromobenzyl mercaptan, α-phenyl-p-chlorobenzyl mercaptan, 3-hydroxy-5-methylbenzyl mercaptan, cinnamyl mercaptan, β-γ-diphenylallyl mercaptan, 4,4′-dichlorobenzhydryl mercaptan, triphenylmethyl mercaptan, Examples of such thionaphthol include α-thionaphthol, β-thionaphthol, 4-methylthio-α-thionaphthol, 5-methylthio-α-thionaphthol, 6-methylthio-α-thionaphthol, 5-methylthio-β-thionaphthol, 6-methylthio-β-thionaphthol, 7-methylthio-β-thionaphthol, 4-chloro-α-thionaphthol, 4-bromo-α-thionaphthol, 1-nitro-β-thionaphthol, and 4-nitro-α-thionaphthol.

[0023] Among the thiol compounds represented by formula (3), specific examples of polythiol compounds having two or more thiol groups include methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6-hexanedithiol, 1,2,3-propanetrithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2- Methylcyclohexane-2,3-dithiol, bicyclo[2,2,1]hepta-exo-cis-2,3-dithiol, 1,1-bis(mercaptomethyl)cyclohexane, thiomalic acid bis(2-mercaptoethyl ester), 2,3-dimercaptosuccinic acid (2-mercaptoethyl ester), 2,3-dimercapto-1-propanol (2-mercaptoacetate), 2,3-dimercapto-1-propanol (3-mercapto aliphatic polythiols such as 1,2-dimercaptopropyl methyl ether, 2,3-dimercaptopropyl methyl ether, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, bis(2-mercaptoethyl)ether, ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), trimethylolpropane bis(2-mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), and pentaerythritol tetrakis(3-mercaptopropionate), as well as halogen-substituted aliphatic polythiols such as chlorine-substituted and bromine-substituted derivatives thereof; 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, 1,2-bis(mercaptoethyl)benzene, 1,3-bis(mercaptoethyl)benzene, 1,4-bis(mercaptoethyl)benzene, 1,2-bis(mercaptomethyleneoxy)benzene, 1,3-bis(mercaptomethyleneoxy)benzene, 1,4-bis(mercaptomethyleneoxy)benzene, 1,2-bis(mercaptoethyleneoxy)benzene, 1,3-bis(mercaptoethyleneoxy)benzene, 1,4-bis(mercaptoethyleneoxy)benzene, 1,2,3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, 1,2,3-tris(mercaptomethyl)benzene, 1,2,4-tris(mercaptomethyl)benzene benzene, 1,3,5-tris(mercaptomethyl)benzene, 1,2,3-tris(mercaptoethyl)benzene, 1,2,4-tris(mercaptoethyl)benzene, 1,3,5-tris(mercaptoethyl)benzene, 1,2,3-tris(mercaptomethyleneoxy)benzene, 1,2,4-tris(mercaptomethyleneoxy)benzene, 1,3,5-tris(mercaptomethyleneoxy)benzene, 1,2,3-tris(mercaptoethyleneoxy)benzene, 1,2,4-tris(mercaptoethyleneoxy)benzene, 1,3,5-tris( (mercaptoethyleneoxy)benzene, 1,2,3,4-tetramercaptobenzene, 1,2,3,5-tetramercaptobenzene, 1,2,4,5-tetramercaptobenzene, 1,2,3,4-tetrakis(mercaptomethyl)benzene, 1,2,3,5-tetrakis(mercaptomethyl)benzene, 1,2,4,5-tetrakis(mercaptomethyl)benzene, 1,2,3,4-tetrakis(mercaptoethyl)benzene, 1,2,3,5-tetrakis(mercaptoethyl)benzene, 1,2,4,5-tetrakis(mercaptoethyl)benzene , 1,2,3,4-tetrakis(mercaptomethyleneoxy)benzene, 1,2,3,5-tetrakis(mercaptomethyleneoxy)benzene, 1,2,4,5-tetrakis(mercaptomethyleneoxy)benzene, 1,2,3,4-tetrakis(mercaptoethyleneoxy)benzene, 1,2,3,5-tetrakis(mercaptoethyleneoxy)benzene, 1,2,4,5-tetrakis(mercaptoethyleneoxy)benzene, 2,2'-dimercaptobiphenyl, 4,4'-thiobis-benzenethiol, 4,4'-dimercaptobiphenyl, 4,aromatic polythiols such as 4'-dimercaptobibenzyl, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,4-naphthalenedithiol, 1,5-naphthalenedithiol, 1,6-naphthalenedithiol, 2,6-naphthalenedithiol, 2,7-naphthalenedithiol, 2,4-dimethylbenzene-1,3-dithiol, 4,5-dimethylbenzene-1,3-dithiol, 9,10-anthracenedimethanethiol, 1,3-di(p-methoxyphenyl)propane-2,2-dithiol, 1,3-diphenylpropane-2,2-dithiol, phenylmethane-1,1-dithiol, 2,4-di(p-mercaptophenyl)pentane, and bis(4-mercaptophenyl)sulfide; Halogen-substituted aromatic polythiols (such as chlorine-substituted aromatic polythiols and bromine-substituted aromatic polythiols) such as 2,5-dichlorobenzene-1,3-dithiol, 1,3-di(p-chlorophenyl)propane-2,2-dithiol, 3,4,5-tribromo-1,2-dimercaptobenzene, and 2,3,4,6-tetrachloro-1,5-bis(mercaptomethyl)benzene; heterocycle-containing polythiols such as 2-methylamino-4,6-dithiol-sym-triazine, 2-ethylamino-4,6-dithiol-sym-triazine, 2-amino-4,6-dithiol-sym-triazine, 2-morpholino-4,6-dithiol-sym-triazine, 2-cyclohexylamino-4,6-dithiol-sym-triazine, 2-methoxy-4,6-dithiol-sym-triazine, 2-phenoxy-4,6-dithiol-sym-triazine, 2-thiobenzeneoxy-4,6-dithiol-sym-triazine, 2-thiobutyloxy-4,6-dithiol-sym-triazine, 3,4-thiophenedithiol, and bismuthiol; 1,2-bis(mercaptomethylthio)benzene, 1,3-bis(mercaptomethylthio)benzene, 1,4-bis(mercaptomethylthio)benzene, 1,2-bis(mercaptoethylthio)benzene, 1,3-bis(mercaptoethylthio)benzene, 1,4-bis(mercaptoethylthio)benzene, 1,2,3-tris(mercaptomethylthio)benzene, 1,2,4-tris(mercaptomethylthio)benzene, 1,3,Polythiols derived from nuclear alkylation products of aromatic compounds such as 5-tris(mercaptomethylthio)benzene, 1,2,3-tris(mercaptoethylthio)benzene, 1,2,4-tris(mercaptoethylthio)benzene, 1,3,5-tris(mercaptoethylthio)benzene, 1,2,3,4-tetrakis(mercaptomethylthio)benzene, 1,2,3,5-tetrakis(mercaptomethylthio)benzene, 1,2,4,5-tetrakis(mercaptomethylthio)benzene, 1,2,3,4-tetrakis(mercaptoethylthio)benzene, 1,2,3,5-tetrakis(mercaptoethylthio)benzene, and 1,2,4,5-tetrakis(mercaptoethylthio)benzene; Bis(mercaptomethyl) sulfide, bis(mercaptoethyl) sulfide, bis(mercaptopropyl) sulfide, bis(mercaptomethylthio)methane, bis(2-mercaptoethylthio)methane, bis(3-mercaptopropylthio)methane, 1,2-bis(mercaptomethylthio)ethane, 1,2-bis(2-mercaptoethylthio)ethane, 1,2-bis(3-mercaptopropyl)ethane, 1,3-bis(mercaptomethylthio)propane, 1,3-bis(2-mercaptoethylthio)propane propane, 1,3-bis(3-mercaptopropylthio)propane, 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, 1,2,3-tris(3-mercaptopropylthio)propane, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)methane, tetrakis(3-mercaptopropylthiomethyl)methane, bis(2,3-dimercaptopropyl)sulfide, 2,5-dimercapto-1,Aliphatic polythiols such as 4-dithiane, bis(mercaptomethyl)disulfide, bis(mercaptoethyl)disulfide, and bis(mercaptopropyl)disulfide, and their thioglycolic acid esters and mercaptopropionic acid esters; Hydroxymethyl sulfide bis(2-mercaptoacetate), hydroxymethyl sulfide bis(3-mercaptopropionate), hydroxyethyl sulfide bis(2-mercaptoacetate), hydroxyethyl sulfide bis(3-mercaptopropionate), hydroxypropyl sulfide bis(2-mercaptoacetate), hydroxypropyl sulfide bis(3-mercaptopropionate), hydroxymethyl disulfide bis(2-mercaptoacetate), hydroxymethyl disulfide bis(3-mercaptopropionate), hydroxyethyl disulfide bis(2-mercaptoacetate), hydroxyethyl disulfide bis(3-mercaptopropionate), hydroxypropyl disulfide bis(2-mercaptoacetate), hydroxypropyl disulfide bis(3-mercaptopropionate), 2-mercaptoethyl ether bis(2-mercaptoacetate), 2-mercapto ethyl ether bis(3-mercaptopropionate), 1,4-dithiane-2,5-diol bis(2-mercaptoacetate), 1,4-dithiane-2,5-diol bis(3-mercaptopropionate), thiodiglycolic acid bis(2-mercaptoethyl ester), thiodipropionic acid bis(2-mercaptoethyl ester), 4,4-thiodibutyric acid bis(2-mercaptoethyl ester), dithioglycolic acid bis(2-mercaptoethyl ester) ), dithiodipropionic acid bis(2-mercaptoethyl ester), 4,4-dithiodibutyric acid bis(2-mercaptoethyl ester), thiodiglycolic acid bis(2,3-dimercaptopropyl ester), thiodipropionic acid bis(2,3-dimercaptopropyl ester), dithioglycolic acid bis(2,3-dimercaptopropyl ester), and dithiodipropionic acid bis(2,3-dimercaptopropyl ester); esters of aliphatic polythiols such as 2-mercaptoethanol, 3-mercapto-1,2-Propanediol, glycerin di(mercaptoacetate), 1-hydroxy-4-mercaptocyclohexane, 2,4-dimercaptophenol, 2-mercaptohydroquinone, 4-mercaptophenol, 3,4-dimercapto-2-propanol, 1,3-dimercapto-2-propanol, 2,3-dimercapto-1-propanol, 1,2-dimercapto-1,3-butanediol, pentaerythritol tris(3-mercaptopropionate), pentaerythritol mono(3-mercaptopropionate), pentaerythritol bis(3-mercaptopropionate), pentaerythritol tris(thioglycolate), pentaerythritol pentakis(3-mercapto Polythiols such as 2,2'-((3-mercaptopropane-1,2-diyl)bis(sulfanediyl))bis(ethane-1-thiol), and 3,3'-thiobis(2-((2-mercaptoethyl)thio)propane-1-thiol); and 2,2'-((3-mercaptopropane-1,2-diyl)bis(sulfanediyl))bis(ethane-1-thiol). Further examples include halogen-substituted products such as chlorine-substituted products and bromine-substituted products of these.

[0024] In terms of improving the handleability of the present composition, the viscosity of the specific compound at 25° C. is preferably 500 to 100,000 mPa·s, and more preferably 1,000 to 20,000 mPa·s. In this specification, the viscosity of the compound, composition, etc. is the viscosity measured when the target object is measured at 25° C. using an E-type viscometer (for example, "RE-85" manufactured by Toki Sangyo Co., Ltd.).

[0025] The molecular weight of the specific compound is not particularly limited, but is preferably 100 to 30000. When the specific compound has a molecular weight distribution, it is preferable that the weight average molecular weight (Mw) of the specific compound is within the above range.

[0026] The refractive index of the specific compound is not particularly limited, but when the refractive index of the core portion (described later) of the optical waveguide is increased, the refractive index at the wavelength of light guided by the optical waveguide is preferably 1.45 or more, more preferably 1.55 or more. The upper limit of the refractive index is not particularly limited and may be, for example, 1.9 or less. Hereinafter, the refractive index of compounds, members, etc. means the refractive index at the wavelength of light guided by the optical waveguide formed using this composition, unless otherwise specified.

[0027] The content of the specific compound may be, for example, 0.1 to 99.9% by mass, and preferably 5 to 95% by mass, based on the total mass of the composition.

[0028] <Other Components> The present composition may contain components other than the specific compound. Examples of other components include a polymerizable compound other than the specific compound, a polymerization initiator, and various additives that are added as needed.

[0029] (Polymerizable Compound) The present composition may contain a polymerizable compound (hereinafter also simply referred to as a "polymerizable compound") different from the specific compound, and preferably contains a polymerizable compound. In this specification, the polymerizable compound is a compound that has a polymerizable group and does not have a thio(meth)acrylate group.

[0030] The number of polymerizable groups possessed by the polymerizable compound is not particularly limited. The polymerizable compound may be a monofunctional polymerizable compound having one polymerizable group or a polyfunctional polymerizable compound having two or more polymerizable groups. The polymerizable group possessed by the polymerizable compound may be a radically polymerizable group or a cationically polymerizable group, as long as it is a group involved in a polymerization reaction. That is, the polymerizable compound may be a radically polymerizable compound or a cationically polymerizable compound. Examples of radically polymerizable compounds include polymerizable compounds (ethylenically unsaturated compounds) having at least one ethylenically unsaturated group such as a vinyl group, a (meth)acryloyl group, a styryl group, and a maleimide group. Examples of cationically polymerizable compounds include polymerizable compounds having a cationically polymerizable group such as an epoxy group and an oxetane group. When the present composition contains a cationically polymerizable compound, it preferably contains a curing agent (e.g., a polyol, an acid anhydride, a polyamine, etc.) that polymerizes with the cationically polymerizable compound to form a cured product such as an epoxy resin or a urethane resin. The polymerizable compound can be appropriately selected in consideration of the characteristics of the self-written optical waveguide to be formed, the viscosity of the polymerizable compound, the compatibility with the specific compound, and the reactivity of the polymerizable compound and the specific compound.

[0031] In particular, by selecting the polymerizable compound and the specific compound so that the refractive index of the cured product of the polymerizable compound is smaller than the refractive index of the cured product of the specific compound, it is possible to produce a self-forming optical waveguide using this composition, which consists of a core part with a high refractive index and a solid clad part with a low refractive index that is disposed around the core part. This production method is advantageous in that it can produce an all-solid self-forming optical waveguide in which the core part and the clad part are both solid, without removing the uncured part around the core part after the core part is formed.

[0032] From the above viewpoints, when the present composition is used for producing an all-solid-state self-forming optical waveguide, the refractive index of the polymerizable compound is preferably smaller than that of the specific compound. In particular, the difference between the refractive index of the specific compound and that of the polymerizable compound is more preferably 0.05 or more, and even more preferably 0.1 or more. The upper limit of the refractive index difference is not particularly limited and may be, for example, 0.5 or less. The refractive indexes of the specific compound and the polymerizable compound are measured using an Abbe refractometer. Since the refractive index of the polymerizable compound and its cured product tends to be smaller, it is preferable that the polymerizable compound does not contain sulfur atoms or halogen atoms. Furthermore, since the self-formation of the core portion is more promoted, it is preferable that the polymerizable compound has lower reactivity (photosensitivity, polymerization reaction rate) than the specific compound.

[0033] High compatibility between the polymerizable compound and the specific compound is preferable because it is less likely to produce a fine phase separation structure, which is one of the causes of scattering (light loss) when light is guided in a self-written optical waveguide. The Hansen solubility parameter distance (ΔHSP) between the polymerizable compound and the specific compound is 7 MPa. ０．５ Preferably, 4 MPa or less ０．５ The lower limit is not particularly limited, and 0 MPa or less is more preferable. ０．５ The Hansen solubility parameters (HSP) are calculated by dividing the solubility of a substance into three components (dispersion term δD, polar term δP, and hydrogen bond term δH) and expressing them in a three-dimensional space. The ΔHSP between a polymerizable compound and a special compound is calculated using the following formula: ΔHSP = (4 x (dDa - dDb) ２ +(dPa-dPb) ２ +(dHa-dHb) ２ ) ０．５In the above formula, dDa, dPa, and dHa are the dispersion term, polarization term, and hydrogen bond term of the polymerizable compound, respectively, and dDb, dPb, and dHb are the dispersion term, polarization term, and hydrogen bond term of a specific compound, respectively. The definition and calculation method of the Hansen solubility parameter of each compound are described in Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007). Furthermore, by using the computer software Hansen Solubility Parameters in Practice (HSPiP), the Hansen solubility parameter can be easily estimated from the chemical structure of a compound for which literature values ​​are unknown. In this specification, the Hansen solubility parameters are calculated using the Y-MB method using HSPiP (ver. 5).

[0034] The polymerizable compound may be any of a polymer, an oligomer, and a monomer. The molecular weight of the polymerizable compound is not particularly limited, but is preferably 100 to 50,000. When the polymerizable compound has a molecular weight distribution, it is preferable that the weight average molecular weight (Mw) of the polymerizable compound is within the above range. In terms of improving the handleability of the composition, the viscosity of the polymerizable compound at 25°C is preferably 500 to 100,000 mPa·s, and more preferably 1,000 to 20,000 mPa·s.

[0035] The polymerizable compound may be used alone or in combination of two or more types. When the composition contains a polymerizable compound, the contents of the polymerizable compound and the specific compound are appropriately selected depending on the structure of the self-forming optical waveguide to be formed. The content of the polymerizable compound may be, for example, 1 to 99% by mass, preferably 5 to 95% by mass, based on the total mass of the composition. When the composition contains a polymerizable compound, the content of the specific compound may be, for example, 1 to 99% by mass, preferably 5 to 95% by mass, based on the total mass of the composition. Furthermore, the content of the polymerizable compound relative to the total content of the polymerizable compound and the specific compound may be, for example, 1 to 99% by mass, preferably 5 to 95% by mass.

[0036] (Polymerization initiator) The present composition preferably contains a polymerization initiator. The polymerization initiator contained in the present composition is preferably a photopolymerization initiator, and more preferably a photopolymerization initiator that generates radicals or acids upon irradiation with ultraviolet or visible light. Various photosensitive compounds can be used as the photopolymerization initiator. The type of photopolymerization initiator is appropriately selected depending on the types of specific compound and polymerizable compound contained in the present composition, the wavelength of light irradiated when forming the optical waveguide, etc.

[0037] Examples of the photopolymerization initiator include acylphosphine oxide initiators, oxyphenylacetic acid ester initiators, benzoylformic acid initiators, and hydroxyphenyl ketone initiators. More specific examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propanone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-1-propanone, 2,2-dimethoxy-2-phenylacetophenone, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, methyl benzoylformate, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), and 2,4,6-trimethylbenzoyldiphenylphosphinic acid ester.

[0038] The polymerization initiator may be used alone or in combination of two or more. When the composition contains a polymerization initiator, the content of the polymerization initiator is preferably 0.1 to 10 mass% and more preferably 0.2 to 5 mass% relative to the total mass of the composition. When the content of the polymerization initiator is equal to or greater than the above-mentioned lower limit, the reactivity during self-formation of the optical waveguide is improved, and when the content of the polymerization initiator is equal to or less than the above-mentioned upper limit, coloration of the optical waveguide is further suppressed.

[0039] The viscosity of the present composition at 25°C is preferably 500 to 100,000 mPa·s, and more preferably 1,000 to 20,000 mPa·s, in terms of better handleability. The viscosity of the present composition can be adjusted by selecting the types of the specific compound and the polymerizable compound.

[0040] The method for preparing the composition is not particularly limited, and the composition can be prepared, for example, by mixing the specific compound, the polymerizable compound, the polymerization initiator, and various additives that are added as needed.

[0041] As described above, the present composition is a composition used for producing a self-written optical waveguide, and by using the present composition, a self-written optical waveguide with high connection efficiency can be formed.

[0042] [Method for manufacturing a self-written optical waveguide] A self-written optical waveguide can be formed, for example, by preparing an optical element and the present composition placed close to the optical element, and then curing the present composition by irradiating light from the optical element. The formed self-written optical waveguide contains a cured product of a specific compound, and therefore is an optical waveguide with a high refractive index and high connection efficiency. Specific embodiments of the method for manufacturing a self-written optical waveguide are described below.

[0043] First Embodiment A method for manufacturing a self-forming optical waveguide according to a first embodiment includes the following steps: a preparation step of preparing an optical element and a self-forming optical waveguide composition disposed in proximity to the optical element, a core portion formation step of irradiating light from the optical element to cure the self-forming optical waveguide composition to form a core portion, and a cladding portion formation step of exposing uncured components in the self-forming optical waveguide composition to form a cladding portion, thereby forming a self-forming optical waveguide including a core portion and a cladding portion. Here, in this embodiment, a self-forming optical waveguide composition containing a specific compound, a polymerizable compound, and a photopolymerization initiator is used.

[0044] This embodiment will be described in more detail below with reference to the drawings. Figures 1A to 1C are schematic diagrams illustrating a method for manufacturing a self-written optical waveguide according to this embodiment. The self-written optical waveguide manufacturing apparatus 100 shown in Figures 1A to 1C includes a transparent container 10, an optical fiber 20 (optical element), and a lamp 30 (only Figure 1C). A self-written optical waveguide composition (composition 1) is held in the transparent container 10.

[0045] 1A , in the preparation step, one end 20A of the optical fiber 20 is brought into contact with the composition 1. In the preparation step, the composition 1 may be filled into the transparent container 10, and then the optical fiber 20 may be placed so that the end 20A is in contact with the composition 1, or the optical fiber 20 may be placed so that the end 20A is located within the transparent container 10, and then the composition 1 may be filled into the transparent container 10.

[0046] In the core portion formation process, irradiation light L (e.g., UV light) transmitted from a light source (not shown) through an optical fiber 20 and emitted from an end portion 20A is irradiated onto the composition 1, selectively polymerizing (curing) the specific compound contained in the composition 1. As a result, as shown in FIG. 1B , an optical waveguide (core portion 2) is gradually formed inside the composition 1 from end portion 20A along the optical axis of the irradiation light L at end portion 20A. At this time, because the refractive index of the formed core portion 2 is higher than the refractive index of the uncured polymerizable compound, the light irradiated from the optical fiber 20 is concentrated on the tip of the core portion 2, and as a result, the core portion 2 gradually extends linearly from end portion 20A. Meanwhile, as the polymerization of the specific compound and the formation of the core portion 2 progress, the uncured polymerizable compound having fluidity is expelled from the core portion 2. Eventually, a core portion 2 is formed inside the composition 1 so as to penetrate from end portion 20A to the end face on the opposite side, and the formed core portion 2 is surrounded by the uncured composition 1.

[0047] 1C , in the cladding formation step, a lamp 30 (e.g., an ultraviolet lamp) is used to irradiate the composition 1 from around it with light (e.g., ultraviolet light) that polymerizes (cures) the composition 1, thereby exposing the composition 1 and polymerizing (curing) the uncured polymerizable compound. As a result, a cladding 3 is formed around the core 2, and an all-solid-state self-written optical waveguide 4 consisting of the core 2 and the cladding 3 is formed.

[0048] Second Embodiment A second embodiment of a method for manufacturing a self-forming optical waveguide will be described with reference to the drawings. Regarding the second embodiment, a description of configurations and operations common to the first embodiment will be omitted. The method for manufacturing a self-forming optical waveguide according to the second embodiment includes a preparation step of preparing a first optical element, a second optical element, and a self-forming optical waveguide composition disposed between the first and second optical elements; a core portion formation step of irradiating light from at least one of the first and second optical elements to cure the self-forming optical waveguide composition to form a core portion; and a clad portion formation step of exposing uncured components in the self-forming optical waveguide composition to form a clad portion, thereby forming a self-forming optical waveguide including a core portion and a clad portion. This embodiment also uses a self-forming optical waveguide composition containing a specific compound, a polymerizable compound, and a photopolymerization initiator.

[0049] 2A to 2D are schematic diagrams illustrating a method for manufacturing a self-written optical waveguide according to this embodiment. The self-written optical waveguide manufacturing apparatus 110 shown in Figures 2A to 2D includes a transparent container 10, a first optical fiber 21, a second optical fiber 22, and a lamp 30.

[0050] 2A , in the preparation step, one end 21A of the first optical fiber 21 and one end 22A of the second optical fiber 22 are brought into contact with the composition 1. In the preparation step, the composition 1 may be filled into the transparent container 10, and then the first optical fiber 21 and the second optical fiber 22 may be placed so that the end 21A and the end 22A are in contact with the composition 1, or the first optical fiber 21 and the second optical fiber 22 may be placed so that the end 20A is located within the transparent container 10, and then the composition 1 may be filled into the transparent container 10.

[0051] In the core portion forming step of this embodiment, the composition 1 is irradiated with irradiation light from at least one of the first optical fiber 21 and the second optical fiber 22 to selectively polymerize (cure) a specific compound contained in the composition 1, thereby forming an optical waveguide (core portion 2) inside the composition 1. That is, the irradiation light for forming the core portion 2 may be emitted from only one of the first optical fiber 21 and the second optical fiber 22, or may be emitted from both the first optical fiber 21 and the second optical fiber 22.

[0052] FIG. 2B shows an example in which the composition 1 is irradiated with irradiation light L1 only from the first optical fiber 21 to form a core portion 2. In this example, irradiation light L1 transmitted from a light source (not shown) through the first optical fiber 21 is irradiated onto the composition 1 from the end 21A, selectively polymerizing (curing) a specific compound contained in the composition 1. As a result, the core portion 2 is formed along the optical axis of the irradiation light L1 at the end 21A. Eventually, the core portion 2 is formed within the composition 1, penetrating from the end 21A to the end 22A located on the opposite side, and the first optical fiber 21 and the second optical fiber 22 are optically connected by the core portion 2. In addition, the formed core portion 2 is surrounded by uncured composition 1. Next, as in the first embodiment, an exposure process is performed on the composition 1 using a lamp 30 (e.g., an ultraviolet lamp) to polymerize (cure) the uncured polymerizable compound, thereby performing a cladding portion formation process (see FIG. 1C ). As a result, a cladding portion 3 is formed around the core portion 2, and an all-solid-state self-written optical waveguide 4 consisting of the core portion 2 and the cladding portion 3 is formed.

[0053] 2C and 2D show an example in which the composition 1 is irradiated with irradiation light L from both the first optical fiber 21 and the second optical fiber 22 to form a core portion 2. In this example, as shown in the figures, the composition 1 is irradiated with irradiation light L1 from the end 21A of the first optical fiber 21, and with irradiation light L2 from the end 22A of the second optical fiber 22. As a result, a core portion 2 is formed from both the end 21A and the end 22A along the optical axes of the irradiation light L1 and L2. At this time, as shown in FIG. 2C , the extending directions of the two core portions 2 may be misaligned. Even in this case, as the tips of the two core portions 2 approach each other, the irradiation light L1 and L2 from the respective tips overlap, creating a region where the light intensity is increased, and the composition 1 is preferentially cured in that region. As a result, the two core portions 2 are connected to form a single core portion 2 that optically connects the end 21A of the first optical fiber 21 and the end 22A of the second optical fiber 22. Next, as in the first embodiment, the composition 1 is exposed to light using a lamp 30 (e.g., an ultraviolet lamp) to polymerize (cure) the uncured polymerizable compound in a cladding formation step, whereby the cladding 3 is formed around the core 2, and an all-solid-state self-written optical waveguide 4 consisting of the core 2 and the cladding 3 is formed.

[0054] The method for manufacturing a self-forming optical waveguide using the present composition is not limited to the above embodiment. In the above embodiment, an all-solid-state self-forming optical waveguide including a core portion and a clad portion is manufactured, but an optical waveguide including only a core portion may be formed using the present composition containing at least a specific compound and a photopolymerization initiator. For example, by performing the preparation step and the core portion formation step of the above embodiment using a composition containing at least a specific compound and a photopolymerization initiator, and then removing the uncured composition, an optical waveguide having a path containing a cured product of the specific compound and in which the surrounding atmosphere functions as a low-refractive layer is obtained.

[0055] The wavelength of the light irradiated to the composition in the core portion-forming step is not particularly limited and is appropriately selected depending on the composition of the composition including the specific compound and the photopolymerization initiator. Examples of the wavelength of the light irradiated in the core portion-forming step include UV light, visible light, and IR light. The wavelength of the light irradiated to the uncured components of the composition in the cladding portion-forming step is not particularly limited and is appropriately selected depending on the composition of the composition including the polymerizable compound and the photopolymerization initiator. Examples of the wavelength of the light irradiated in the cladding portion-forming step include UV light, visible light, and IR light. Furthermore, the wavelength of the light irradiated in the core portion-forming step and the wavelength of the light irradiated in the cladding portion-forming step may be the same or different.

[0056] In the method for producing a self-written optical waveguide, the optical element used to irradiate the composition with light can be any optical component that can be placed in proximity to the composition and that can emit light. Examples of such optical elements include the above-mentioned optical fiber, as well as optical waveguides, semiconductor lasers, light-emitting diodes, photodiodes, and lenses.

[0057] Furthermore, the self-written optical waveguide produced using the present composition may have a branched structure. For example, during or after the core formation step, the present composition may be irradiated with light from a direction intersecting the direction in which the cores extend, thereby connecting the cores to each other near the positions where the irradiated light intersects, thereby forming a core having a branched structure.

[0058] [Self-Writing Optical Waveguide] The self-writing optical waveguide according to the present invention is a self-writing optical waveguide manufactured using the present composition. By using the present composition, a self-writing optical waveguide with high connection efficiency can be obtained. The self-writing optical waveguide is preferably an all-solid self-writing optical waveguide including a core portion containing a larger amount of the cured product of a specific compound and a clad portion containing a larger amount of the cured product of a polymerizable compound. The method for manufacturing a self-writing optical waveguide has already been described, but the self-writing optical waveguide according to the present invention may be manufactured by a manufacturing method other than the above-described method as long as it is manufactured using the present composition.

[0059] In the self-written optical waveguide including the core and clad portions, the difference in refractive index between the core and clad portions is preferably 0.005 or more, more preferably 0.01 or more, and even more preferably 0.02 or more. The upper limit is not particularly limited, and may be 0.5 or less.

[0060] The optical waveguide according to the present invention is formed by self-forming (self-organization) and has high connection efficiency, and is therefore useful as an optical waveguide for various optical devices, and is particularly useful as an optical coupler for connecting multiple optical elements.

[0061] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment details, and treatment procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0062] Synthesis Example 1 A monomer mixture I containing the compound (B-4), the compound (B-5) and the compound (C-2) was synthesized by the following method.

[0063]

[0064] <Synthesis of a mixture containing compound (B-4A), compound (B-5A), compound (C-1), and 1,6-naphthalenedithiol> 18.6 g (96.9 mmol) of 1,6-naphthalenedithiol, 13.7 g (96.9 mmol) of methyl iodide, and 240 mL of N,N-dimethylacetamide (DMAc) were mixed, and the mixture was cooled so that the internal temperature (liquid temperature) was 0°C. 13.2 g (101.8 mmol) of N,N-diisopropylethylamine (DIPEA) was added dropwise to the mixture so that the liquid temperature did not exceed 7°C, and then the mixture was heated so that the internal temperature (liquid temperature) was 25°C. After stirring for 1 hour, 800 mL of ethyl acetate and 800 mL of 1N hydrochloric acid were added, followed by washing and separation. Next, 800 mL of water was added, and the mixture was stirred, followed by washing and separation. The resulting mixture was dehydrated with magnesium sulfate, filtered, and concentrated to give 19.5 g of an oily composition containing the compound (B-4A), the compound (B-5A), the compound (C-1), and 1,6-naphthalenedithiol. The yield was 98%.

[0065] <Synthesis of Compound (B-4), Compound (B-5), and Compound (C-2)> 5.0 g (24.2 mmol) of a mixture of Compound (B-4A), Compound (B-5A), Compound (C-1), and 1,6-naphthalenedithiol, and 12 mL of N,N-dimethylacetamide (DMAc) were mixed, and the mixture was cooled to an internal temperature (liquid temperature) of 0°C. 3.38 g (26.7 mmol) of 3-chloropropionyl chloride (3CPC) was added dropwise to the mixture so that the liquid temperature did not exceed 7°C, and the mixture was then heated to an internal temperature (liquid temperature) of 25°C. After stirring for 1 hour, the mixture was cooled to 0°C, and 5.89 g (58.1 mmol) of triethylamine (TEA) was added dropwise to the mixture so that the liquid temperature did not exceed 7°C, and the mixture was then heated to an internal temperature (liquid temperature) of 25°C. After stirring for 1 hour, 40 mL of ethyl acetate and 40 mL of 1N hydrochloric acid were added, and the insoluble matter was filtered, followed by washing and separation. Next, 40 mL of a 5% aqueous solution of sodium bicarbonate was added, and the mixture was stirred, followed by washing and separation. An oily composition was obtained by dehydration using magnesium sulfate, filtration, and concentration, and then purified by column chromatography to remove compound (C-1). A monomer mixture I containing compound (B-4), compound (B-5), and compound (C-2) was isolated (yield 63%). The concentration of each compound alone was calculated from the area at a wavelength of 254 nm of compound (B-4), compound (B-5), and compound (C-2) obtained by high-performance liquid chromatography (HPLC) analysis. The composition ratio of monomer mixture I determined from these results was compound (B-4): compound (B-5): compound (C-2) = 28% by mass: 34% by mass: 38% by mass.

[0066] Synthesis Example 2 The following Monomer II (2,2'-thiodiethanethiol diacrylate) was synthesized according to the method described in Example 2 of JP-B 07-091262.

[0067]

[0068] In addition to Monomer Mixture I and Monomer II, the following compounds were used to prepare the self-written optical waveguide composition. "A-LEN-10": Ethoxylated o-phenylphenol acrylate manufactured by Shin-Nakamura Chemical Co., Ltd. "OGSOL (registered trademark) EA-F5710": Fluorene-based acrylate manufactured by Osaka Gas Chemicals Co., Ltd. "AD-TMP": Ditrimethylolpropane tetraacrylate manufactured by Shin-Nakamura Chemical Co., Ltd. "A-200": Polyethylene glycol #200 diacrylate manufactured by Shin-Nakamura Chemical Co., Ltd. "OGSOL EA-0300": Fluorene-based acrylate manufactured by Osaka Gas Chemicals Co., Ltd. "OGSOL GA-2800": Fluorene-based acrylate manufactured by Osaka Gas Chemicals Co., Ltd.

[0069] Example 1 Preparation of Self-Written Optical Waveguide Composition The monomer mixture I (a mixture of compound (B-4), compound (B-5), and compound (C-2)) obtained in the above Synthesis Example, OGSOL EA-F5710, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide as a photopolymerization initiator were mixed in a mass ratio of 50:50:1 to obtain composition X-1.

[0070] Examples 2 to 6, Comparative Example 1 Compositions X-2 to X-7 were prepared according to the procedure described in Example 1, except that the compound described in the Monomer A column of Table 1 was used instead of Monomer Mixture I, and the compound described in the Monomer B column of Table 1 was used instead of OGSOL EA-F5710.

[0071]

[0072] [Measurement of Viscosity] The viscosity at 25°C of Compositions X-1 to X-7 and the components other than the photopolymerization initiator used in the preparation of Compositions X-1 to X-7 in each example was measured using an E-type viscometer ("RE-85" manufactured by Toki Sangyo Co., Ltd.) The measurement results are shown in Table 1 above.

[0073] [Measurement of Refractive Index] The refractive index nd25 of each material was measured using an Abbe refractometer.

[0074] [Self-Written Optical Waveguide Fabrication Test] According to the following test method, an attempt was made to fabricate a self-written optical waveguide using each of compositions X-1 to X-7. The test method using composition X-1 as a representative example will be described. A glass tube with an inner diameter of 2.8 mm was filled with composition X-1 in an amount that would result in a length of 2 mm. An optical fiber with a core diameter of 50 μm was inserted into the tube, and the optical fiber was positioned so that the exit port at one end was in contact with composition X-1. UV light was irradiated for 30 seconds through the optical fiber from a light source (xenon UV lamp) located at the other end of the optical fiber. The illuminance of the UV light at the exit port of the optical fiber was 10 μW / cm ２ Thereafter, UV light (light source: metal halide lamp) was irradiated from the side of the cylinder with 200 mW / cm 2 onto the composition X-1 filled in the cylinder. ２ The sample was irradiated with 1000 kJ / min for 1 minute.

[0075] [Evaluation] [Formation of self-written optical waveguide] In the above-mentioned production test, after irradiation with UV light through the optical fiber was completed, each composition was observed with an optical microscope to confirm the presence or absence of an optical waveguide. Based on the observation results, examples in which the presence of an optical waveguide was confirmed were evaluated as "A", and examples in which the presence of an optical waveguide was not confirmed were evaluated as "B". Note that, as a result of the observation, if the composition was found to be flowing and no clear optical waveguide structure was observed, it was evaluated as "B".

[0076] [Evaluation of Fully Solidified Self-Written Optical Waveguides] In the above fabrication test, the optical waveguides formed by irradiation with UV light through the optical fiber were observed using an optical microscope during and after the UV light irradiation from the side of the tube to confirm whether the structure of the optical waveguide was maintained. Based on the observation results, examples in which the structure of the optical waveguide was maintained even after the UV light irradiation from the side of the tube was completed were evaluated as "A," and examples in which the structure of the optical waveguide was lost and not maintained due to flow of the composition or other factors before the UV light irradiation from the side of the tube was completed were evaluated as "B." In examples rated as A, it can be evaluated that a solid cladding portion was formed around the optical waveguide (core portion), and an all-solid self-written optical waveguide was produced that maintained the structure of the optical waveguide.

[0077] [Evaluation of optical waveguide performance] After the above-mentioned fabrication test was completed, red laser light emitted from the laser light source was output from the light irradiation port through the optical fiber and guided inside the composition filled in the tube. The end face of the composition opposite the light irradiation port was observed with an optical microscope, and the performance of each composition as an optical waveguide was evaluated based on the observation results and the following criteria: 3: Strong color development of the guided laser light was observed at the end face on the opposite side. 2: Weak color development of the guided laser light was observed at the end face on the opposite side. 1: No color development of the guided laser light was observed at the end face on the opposite side.

[0078] The evaluation results of the self-written optical waveguide fabrication test carried out using the compositions of each example are shown in Table 2. In the table, the notation "-" in the "Fully solidified" column for Comparative Example 1 means that a self-written optical waveguide was not formed in Comparative Example 1, and evaluation of the full solidification could not be carried out.

[0079]

[0080] From the results shown in Table 2, it was confirmed that by using the self-written optical waveguide composition of the present invention, a self-written optical waveguide with high connection efficiency could be formed (Examples 1 to 6).

[0081] REFERENCE SIGNS LIST 1 composition 2 core portion 3 cladding portion 4 self-written optical waveguide 10 transparent container 20 optical fiber 20A, 21A, 22A end portion 21 first optical fiber 22 second optical fiber 30 lamp 100, 110 manufacturing device L, L1, L2 irradiation light

Claims

1. A composition for a self-forming optical waveguide, comprising a compound having a thio(meth)acrylate group.

2. The self-forming optical waveguide composition according to claim 1, wherein the compound has two or more thio(meth)acrylate groups in one molecule.

3. The self-written optical waveguide composition according to claim 1 or 2, further comprising a polymerizable compound different from the compound.

4. The self-writing optical waveguide composition according to claim 3, wherein the refractive index of the polymerizable compound is smaller than the refractive index of the compound having a thio(meth)acrylate group.

5. A self-writing optical waveguide composition according to claim 1 or 2, wherein the viscosity of the self-writing optical waveguide composition at 25°C is 500 to 100,000 mPa·s.

6. A self-written optical waveguide manufactured using the composition for a self-written optical waveguide according to claim 1 or 2.

7. A method for manufacturing a self-forming optical waveguide using the self-forming optical waveguide composition according to claim 3, comprising the steps of: preparing a first optical element, a second optical element, and the self-forming optical waveguide composition disposed between the first optical element and the second optical element; irradiating light from at least one of the first optical element and the second optical element to cure the self-forming optical waveguide composition and form a core portion; and exposing the uncured components in the self-forming optical waveguide composition to form a cladding portion, thereby forming a self-forming optical waveguide comprising the core portion and the cladding portion.

Images