JP2012063620A - Method for manufacturing curable composition and optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a curable composition enabling time and energy saving when forming a clad or core, improving work environment and preventing occurrence of crease at a substrate (plastic film) when forming the clad on a surface of the substrate, and a method for manufacturing an optical waveguide using the curable composition.SOLUTION: A curable composition is provided for forming a clad 20 or a core 10 of an optical waveguide 1. The curable composition contains: a fluorine-containing polyarylene prepolymer (A) having a crosslinkable functional group; and a compound (B) expressed by [X]Y (n: an integer number from 1 to 5, X: crosslinkable functional group, Y: n-valent aliphatic or alicyclic organic group) and having no fluorine atom, and substantially contains no solvent.

Description

  The present invention relates to a curable composition for forming a clad or core of an optical waveguide and a method for producing an optical waveguide using the curable composition.

In the field of communication equipment, with the miniaturization of equipment and the speeding up of communication, the use of resin-made optical waveguides for signal transmission has attracted attention. The resin used for the core and clad of the optical waveguide is required to have high transparency and heat resistance.
A fluorine-containing polyarylene prepolymer is known as a resin having high transparency and heat resistance (Patent Document 1), and a curable composition using the fluorine-containing polyarylene prepolymer has also been proposed (patent). Reference 2).

However, since the fluorine-containing polyarylene prepolymer is in a powder form, it is necessary to use a solvent when mixing this with other components (crosslinking agent, photosensitizer, etc.) to obtain a curable composition. When a solvent is used, the following problems occur.
When applying a curable composition to form a clad or a core, it takes time to evaporate the solvent, and energy for heating is required.
・ In order to maintain a good working environment, equipment for ventilating and treating the evaporated solvent is required.
・ When forming a clad by the roll-to-roll method, it is necessary to use a plastic film as the base material. However, when the curable composition is applied to the plastic film and dried, the film shrinks to the film. Wrinkles may occur.

International Publication No. 2006/137327 Pamphlet International Publication No. 2007/119384 Pamphlet

  The present invention saves time and energy when forming a clad or core, improves the working environment, and does not cause wrinkles on the base material when forming the clad on the surface of the base material (plastic film). A composition and a method for producing an optical waveguide using the curable composition are provided.

The curable composition of the present invention is a curable composition for forming a clad or core of an optical waveguide, and includes a fluorine-containing polyarylene prepolymer (A) having a crosslinkable functional group, and the following formula (I): It is characterized by including the compound (B) which does not have a fluorine atom, and does not contain a solvent substantially.
[X] _n Y (I).
However, n is an integer of 1-5, X is a crosslinkable functional group, Y is an n-valent aliphatic or alicyclic organic group which may have an etheric oxygen atom. is there.

The viscosity of the compound (B) at 25 ° C. is preferably 3000 mPa · s or less.
The ratio of the fluorine-containing polyarylene prepolymer (A) is 1 to 97% by mass in the total (100% by mass) of the fluorine-containing polyarylene prepolymer (A) and the compound (B). preferable.
N in the formula (I) is preferably an integer of 2 to 3.
X in the formula (I) is at least one selected from the group consisting of vinyl group, allyl group, ethynyl group, vinyloxy group, allyloxy group, acryloyl group, acryloyloxy group, methacryloyl group and methacryloyloxy group. preferable.

  The method of manufacturing an optical waveguide according to the present invention includes forming an underclad layer on a surface of a base material, forming a core on the surface of the underclad layer, and covering the underclad layer and the surface of the core. A method for producing an optical waveguide, wherein the curable composition of the present invention is used for forming at least the under cladding layer and / or the over cladding layer.

According to the curable composition of the present invention, it is possible to save time and energy when forming a clad or core, improve the working environment, and to form a clad on the surface of a base material (plastic film). It is hard to generate wrinkles.
According to the method for manufacturing an optical waveguide of the present invention, the time and energy when forming the clad or core can be saved, the working environment can be improved, and the base material can be formed when forming the clad on the surface of the base material (plastic film). It is hard to generate wrinkles.

It is sectional drawing which shows an example of an optical waveguide. It is a figure which shows an example of the manufacturing method of the optical waveguide of this invention.

In this specification, a compound represented by the formula (B-1) will be referred to as a compound (B-1). The same applies to compounds represented by other formulas.
Moreover, in this specification, a methacryloyl (oxy) group means a methacryloyl group or a methacryloyloxy group. The same applies to the acryloyl (oxy) group.

<Optical waveguide>
FIG. 1 is a cross-sectional view perpendicular to the length direction of the core, showing an example of the optical waveguide of the present invention. The optical waveguide 1 is in the form of a long film having a plurality of cores 10 provided in parallel with each other and spaced apart from each other, and a clad 20 surrounding the core 10.

(core)
The refractive index of the core 10 is higher than the refractive index of the clad 20.
The cross-sectional shape of the core 10 is rectangular in the illustrated example, but is not limited thereto. For example, it may be a trapezoid, a circle, an ellipse, or a pentagon or more polygon. When the cross-sectional shape of the core 10 is a polygon, the corners may be rounded.
What is necessary is just to design the cross-sectional shape and magnitude | size of the core 10 suitably considering the coupling efficiency with a light source or a light receiving element. The coupling efficiency depends on the core diameter and the numerical aperture (NA).

  The width a and height b of the core 10 are each preferably about 1 to 100 μm. When the width a and the height b of the core 10 are 1 μm or more, a decrease in the coupling efficiency with the light source or the light receiving element can be suppressed. When the width a and the height b of the core 10 are 100 μm or less, even when the bending radius (R) is about 1 mm, bending loss can be reduced. In addition, since the size (width and height) of the light receiving portion of the photodiode (PD) used as the light receiving element is usually 100 μm or less, the width a and height b of the core 10 is 100 μm or less from this point. Preferably there is.

(Clad)
The clad 20 includes an under clad layer 22 and an over clad layer 24.
The material of the under cladding layer 22 and the material of the over cladding layer 24 may be the same as long as the refractive index of the under cladding layer 22 and the refractive index of the over cladding layer 24 are lower than the refractive index of the core 10. Well, it can be different.

  The thickness c of the under-cladding layer 22 and the thickness d of the over-cladding layer 24 are designed so as to reduce the light loss according to the numerical aperture (NA) value. Even if the core 10 is in contact with the air layer without one or both of the under-cladding layer 22 and the over-cladding layer 24, light transmission is possible, but the under-cladding layer 22 and the over-cladding layer 24 are provided. Preferably it is.

The thickness c of the under cladding layer 22 is preferably 5 to 50 μm from the viewpoint of protecting the core 10.
The thickness d of the over clad layer 24 is thicker than the height b of the core 10 and is preferably 15 to 150 μm from the viewpoint of protecting the core 10.
The thickness (c + d) of the clad 10 is preferably 20 to 200 μm.

<Curable composition>
The curable composition of the present invention is a curable composition for forming the clad 20 or the core 10 of the optical waveguide 1 and is also referred to as a fluorine-containing polyarylene prepolymer (A) (hereinafter also referred to as prepolymer (A)). And a compound (B), and substantially free of a solvent.

  The refractive index of the cured product of the curable composition for forming the clad 20 (hereinafter also referred to as a curable composition for forming a clad) is the curable composition for forming the core 10 (hereinafter, for core formation). It is also necessary to be lower than the refractive index of the cured product. The refractive index of the cured product of the curable composition can be adjusted by the type of the compound (B), the mixing ratio of the prepolymer (A) and the compound (B), and the like.

  Since the curable composition of the present invention contains the compound (B) having a relatively low viscosity, it tends to be a uniform composition, and the surface tends to be flat when cured. Moreover, since the prepolymer (A) having an aromatic ring is included and the prepolymer (A) and the compound (B) are crosslinked or chain-extended, the heat resistance is good.

  The proportion of the prepolymer (A) is preferably 1 to 97 mass%, more preferably 1 to 70 mass%, of the total (100 mass%) of the prepolymer (A) and the compound (B), and 5 to 50 % By mass is more preferable, and 8 to 35% by mass is particularly preferable. The higher the proportion of prepolymer (A), the higher the heat resistance. The greater the proportion of compound (B), the better the surface flatness of the cured product.

(Prepolymer (A))
The core 10 is usually composed of a cured product of only the prepolymer (A), but may be composed of a cured product of the curable composition of the present invention containing the prepolymer (A) and the compound (B). .
The clad 20 is normally comprised from the hardened | cured material of the curable composition of this invention containing a prepolymer (A) and a compound (B).
The prepolymer (A) used for forming the core 10 and the prepolymer (A) used for forming the clad 20 may be the same or different. From the viewpoint of adhesiveness, adhesion, crack suppression, and reduction in expansion coefficient difference, the same is preferable.

The prepolymer (A) has a polyarylene structure in which a plurality of aromatic rings are bonded via a single bond or a linking group, a fluorine atom, and a crosslinkable functional group.
Examples of the linking group in the polyarylene structure include an ether bond (—O—), a sulfide bond (—S—), a carbonyl group (—CO—), and a divalent group obtained by removing a hydroxyl group from a sulfonic acid group (—SO ₂ —). Etc.

Of the prepolymer (A), one having a structure in which a plurality of aromatic rings are bonded via a linking group containing an ether bond (—O—) is referred to as a fluorinated polyarylene ether prepolymer (A1).
Examples of the linking group containing an ether bond include an ether bond (—O—) consisting only of an etheric oxygen atom, and an alkylene group containing an etheric oxygen atom in the carbon chain.
Since the fluorine-containing polyarylene ether prepolymer (A1) has an etheric oxygen atom, the molecular structure has flexibility and the flexibility of the cured product is improved.

Since the prepolymer (A) has an aromatic ring, the heat resistance is good.
The crosslinkable functional group of the prepolymer (A) does not substantially react during the production of the prepolymer, reacts by applying external energy, and causes a high molecular weight by crosslinking or chain extension between prepolymer molecules. It is a group.

  Crosslinkable functional groups include vinyl, allyl, allyloxy, methacryloyl (oxy), acryloyl (oxy), vinyloxy, trifluorovinyl, trifluorovinyloxy, ethynyl, 1-oxocyclopenta Examples include -2,5-dien-3-yl group, cyano group, alkoxysilyl group, diarylhydroxymethyl group, hydroxyfluorenyl group, cyclobutalene ring, and oxirane ring. A vinyl group, a methacryloyl (oxy) group, an acryloyl (oxy) group, a trifluorovinyloxy group, an ethynyl group, a cyclobutalene ring, and an oxirane ring are preferable because of high reactivity and high crosslink density. A vinyl group and an ethynyl group are particularly preferable from the viewpoint of good heat resistance.

Examples of external energy include heat, light, and electron beam. A plurality of external energies may be used in combination.
When heat is used as external energy, the prepolymer (A) preferably has a reactive functional group that reacts at a reaction temperature of 40 to 500 ° C. as a crosslinkable functional group. If the reaction temperature is too low, the stability of the prepolymer (A) or the curable composition containing the prepolymer (A) during storage cannot be ensured. If the reaction temperature is too high, thermal decomposition of the prepolymer itself will occur during the reaction. The reaction temperature is more preferably from 60 to 300 ° C, further preferably from 70 to 200 ° C, particularly preferably from 120 to 250 ° C.

  When light (actinic radiation) is used as external energy, it is preferable to perform exposure in a state where the prepolymer (A) and the photosensitive agent coexist. Specifically, it is preferable to prepare a curable composition (or coating solution) containing the prepolymer (A) and to contain a photosensitizer. By selectively irradiating only a desired part with actinic radiation in the exposure step, only the exposed part can be made to have a high molecular weight, and the unexposed part can be dissolved in a developing solution and removed. Further, if necessary, external energy such as actinic radiation and heat may be applied after the exposure and development to further increase the molecular weight.

The prepolymer (A) has a fluorine atom. That is, since the prepolymer (A) has a C—F bond in which a hydrogen atom of a C—H bond is substituted with a fluorine atom, the presence ratio of the C—H bond is reduced. Since the C—H bond has absorption in the optical communication wavelength band (1250 to 1650 nm), the prepolymer (A) having few C—H bonds is suppressed to absorb light in the optical communication wavelength band. Moreover, since it has a fluorine atom, its water absorption rate or moisture absorption rate is low, it has excellent resistance to high temperature and high humidity, and it is chemically stable. Therefore, in the optical waveguide using the prepolymer (A), the characteristics are stable because the refractive index variation due to changes in the external environment, particularly humidity, is small, and the transparency in the optical communication wavelength band is high. high.
Moreover, since the cured product of the prepolymer (A) has high transparency in the vicinity of a wavelength of 1310 nm, an optical waveguide having good compatibility with existing optical elements can be obtained. That is, in an optical transmission device using a normal silica-based optical fiber, 1310 nm is often used as a wavelength, so that many optical elements such as light receiving elements suitable for the wavelength used are manufactured, and reliability is also high. high.

Preferred prepolymers (A) include fluorine-containing aromatic compounds (perfluoro (1,3,5-triphenylbenzene), perfluorobiphenyl, etc.) and phenolic compounds (1,3,5-trihydroxybenzene, 1, 1,1-tris (4-hydroxyphenyl) ethane) and a crosslinkable compound (pentafluorostyrene, acetoxystyrene, chloromethylstyrene, etc.) in the presence of a dehydrohalogenating agent (potassium carbonate, etc.) The polymer obtained by making it include.
A prepolymer (A) may be used individually by 1 type, and may use 2 or more types together.

(Compound (B))
The compound (B) is represented by the following formula (I), has a viscosity at 25 ° C. of 3000 mPa · s or less, and has no fluorine atom, aromatic ring or heterocyclic ring.
[X] _n Y (I).

  n is an integer of 1-5. When n is 1 or more, chain extension (further crosslinking when n is 2 or more) causes high molecular weight, and the cured product has good heat resistance. n is preferably 2 or more from the viewpoint that it can cross-link between molecules, can improve heat resistance in a cured product, and can satisfactorily suppress a decrease in film thickness due to heating in the cured product. If n is 5 or less, the viscosity of the compound (B) can be kept low, and the solubility of the prepolymer (A) in the compound (B) becomes good. n is preferably 4 or less and more preferably 3 or less from the viewpoint of the solubility of the prepolymer (A) in the compound (B).

X is a crosslinkable functional group. X does not have a fluorine atom.
X reacts with each other to cause crosslinking or chain extension. X is preferably one that reacts with the crosslinkable functional group of the prepolymer (A) to cause crosslinking or chain extension.
X is preferably a carbon atom-carbon atom double bond or triple bond. However, aromatic double bonds and triple bonds are not included. The double bond or triple bond may be present in the molecular chain or at the terminal, but is preferably present at the terminal because of high reactivity. The double bond may be an internal olefin or a terminal olefin, but a terminal olefin is preferred. Being inside a molecular chain includes being present in a part of an aliphatic ring such as cycloolefins.
X is preferably one or more selected from the group consisting of a vinyl group, an allyl group, an ethynyl group, a vinyloxy group, an allyloxy group, an acryloyl group, an acryloyloxy group, a methacryloyl group, and a methacryloyloxy group. An acryloyl group and an acryloyloxy group are preferable from the viewpoint of causing a reaction by light irradiation even in the absence of a photosensitizer.

Y is an n-valent aliphatic or alicyclic organic group which may have an etheric oxygen atom. Y does not have a fluorine atom.
Examples of the aliphatic organic group include a linear or branched aliphatic hydrocarbon group (an alkyl group, an alkylene group, etc.), a (poly) oxyalkylene group, a group combining these, and the like.
Examples of the alicyclic organic group include alicyclic hydrocarbon groups (cycloalkyl groups, cycloalkylene groups, etc.).
Y is preferably a linear one from the viewpoint of the solubility of the prepolymer (A) in the compound (B). Moreover, as Y, what has a (poly) oxyalkylene group from the solubility point to the compound (B) of a prepolymer (A) is preferable.

  The viscosity at 25 ° C. of the compound (B) is preferably more than 0 mPa · s and 3000 mPa · s, more preferably 5 to 2000 mPa · s, and further preferably 10 to 1100 mPa · s. If the viscosity of a compound (B) is 3000 mPa * s or less, the solubility to the compound (B) of a prepolymer (A) will become favorable. Moreover, the curable composition of the present invention tends to be a uniform composition, and the surface tends to be flat when cured. When the viscosity of the compound (B) is 10 mPa · s or more, good heat resistance is obtained, and decomposition and volatilization are hardly caused by heating.

Compound (B) does not have a fluorine atom. Since there are no fluorine atoms in the molecule, good embedding flatness is easily obtained. If the embedded flatness is good, the surface of the over clad layer 24 tends to be flat. Further, the cost is likely to be lower than that of the fluorine-containing compound.
Compound (B) does not have an aromatic ring or a heterocyclic ring. When the molecule has an aromatic ring and a heterocyclic ring, the solubility of the prepolymer (A) in the compound (B) tends to be lowered even if the compound (B) has a low viscosity.

As preferred compound (B), compound (B-1), compound (B-2), compound (B-3), compound (B-4), compound (B-5), compound (B-6) described later are used. ), Compound (B-7), compound (B-8), compound (B-15) and the like.
A compound (B) may be used individually by 1 type, and may use 2 or more types together.

  Among the compounds (B), those in which the refractive index of the cured product obtained by curing the compound (B) alone is lower than the refractive index of the cured product obtained by curing the prepolymer (A) alone are the same. By mix | blending with A), a refractive index can be lowered | hung rather than the hardened | cured material which hardened the prepolymer (A) independently. When the compound (B) that increases the refractive index is used, the refractive index of the clad 20 can be made lower than the refractive index of the core 10 by combining with the compound (B) that decreases the refractive index.

(solvent)
The curable composition of the present invention contains substantially no solvent. “Substantially free of solvent” means that the solvent is not contained at all or the solvent contained as an impurity in the raw materials (prepolymer (A), compound (B), etc.) does not impair the effects of the present invention. It means that it may be inevitably mixed. The solvent means a compound other than the compound (B) and capable of dissolving the prepolymer (A).

(Thermosetting accelerator)
When thermosetting the curable composition of the present invention, a thermosetting accelerator may be included in the curable composition of the present invention. Examples of the thermosetting accelerator include azobisisobutyronitrile, benzoyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, and dicumyl peroxide.

(Photosensitive agent)
When the curable composition of the present invention is photocured, a photosensitive agent may be included in the curable composition of the present invention. IRGACURE 907 (α-aminoalkylphenone series), IRGACURE 369 (α-aminoalkylphenone series), DAROCUR TPO (acylphosphine oxide series), IRGACURE OXE01 (oxime ester derivative), IRGACURE OXE02 (oxime ester derivative) ) (Both manufactured by Ciba Specialty Chemicals). Of these, DAROCUR TPO, IRGACURE OXE01, and IRGACURE OXE02 are particularly preferable.

(Adhesion improver)
The curable composition of the present invention may contain an adhesion improver such as a silane coupling agent. By including an adhesion improver, it is possible to improve the adhesion between a layer made of a cured product of the curable composition and a layer adjacent thereto.

<Optical waveguide manufacturing method>
The method for producing an optical waveguide of the present invention is a method having the following steps (a) to (c), and the curable composition of the present invention is used for forming at least an under cladding layer and / or an over cladding layer. Is the method.
(A) The process of forming an under clad layer on the surface of a base material.
(B) A step of forming a core on the surface of the under cladding layer.
(C) A step of forming an over clad layer so as to cover the surface of the under clad layer and the core.

  Hereinafter, the method for producing an optical waveguide of the present invention will be described in detail by taking as an example a method in which an undercladding layer and an overcladding layer are formed by applying the curable composition of the present invention and a core is formed by a photolithography method. In addition, the manufacturing method of the optical waveguide of this invention is not limited to the following specific examples.

(Process (a))
As shown in FIG. 2, the curable composition of this invention is apply | coated to the surface of the base material 30, and it heats and / or light-irradiates and hardens | cures, and the underclad layer 22 is formed. Before applying the curable composition of the present invention to the surface of the substrate 30, an adhesion improver may be applied to the surface of the substrate 30. Also, an adhesion improver may be applied between the under cladding layer 22, the core 10, and the over cladding layer 24.

Examples of the base material 30 include a plastic film and silicon. Examples of the plastic film material include polyimide and polyethylene terephthalate.
When the optical waveguide is used in a state where the clad 20 and the base material 30 are integrated, it is preferable to include an adhesion improver in the curable composition of the present invention.

(Process (b))
As shown in FIG. 2, the coating liquid of the prepolymer (A) or the curable composition of the present invention is applied to the surface of the underclad layer 22 and prebaked to form the semi-cured core precursor layer 12. (Step (b-1)).
Next, as shown in FIG. 2, the core precursor layer 12 is processed by a photolithographic method to form the core 10. That is, the core precursor layer 12 is irradiated with light (exposure) through a photomask, and then developed to form the core 10 (step (b-2)).
Subsequently, post-baking is performed to completely cure the core 10.

The coating solution can be prepared by dissolving the prepolymer (A) in a solvent.
Solvents include propylene glycol monomethyl ether acetate (hereinafter also referred to as PGMEA), ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, pentyl acetate, isopentyl acetate, isobutyl isobutyrate, methyl-3-methoxypropionate, di- Examples include propylene glycol methyl ether acetate, cyclopentanone, methyl ethyl ketone, methyl isobutyl ketone, and dibutyl ketone.
The coating solution may contain the above-described photosensitive agent, adhesion improver, and the like.
The coating liquid may contain the compound (B).

  When the core-forming coating liquid or the core-forming curable composition contains the compound (B), the refractive index of the cured product of the core-forming coating liquid or the core-forming curable composition, that is, the refractive index of the core 10 is It is necessary to include the refractive index of the cured product of the curable composition for forming a clad, that is, in a range higher than the refractive index of the clad 20. The refractive index difference between the core 10 and the clad 20 is preferably within a range where a preferable numerical aperture (NA) can be obtained.

(Process (c))
As shown in FIG. 2, the curable composition of the present invention is applied to the surfaces of the underclad layer 22 and the core 10, and is cured by heating and / or light irradiation in the same manner as the underclad layer 22. By forming the clad layer 24, the optical waveguide 1 is obtained. If necessary, the substrate 30 may be peeled off and removed.

(Function and effect)
In the curable composition and the method for producing an optical waveguide of the present invention described above, since the curable composition does not contain a solvent, the following effects are exhibited.
-It is not necessary to evaporate the solvent when a curable composition is applied to form a clad or core. As a result, it takes no time to form the clad and the core, and energy for solvent evaporation becomes unnecessary.
・ Further, the equipment for ventilating and treating the evaporated solvent is not necessary, and the working environment can be kept good.
・ In addition, when forming a clad by the roll-to-roll method, it is necessary to use a plastic film as a base material. However, when a curable composition is applied to the plastic film and dried, the coating film shrinks. The film is less likely to wrinkle.

  Moreover, in the manufacturing method of the optical waveguide of this invention demonstrated above, a core is comprised with the hardened | cured material of a prepolymer (A), and a clad is the curable composition of this invention containing a prepolymer (A). By comprising the cured product, good adhesion can be obtained at the interface between the core and the clad. Therefore, even if the obtained optical waveguide is subjected to heating, bending, temperature change or the like, peeling or cracking is unlikely to occur at the interface between the core and the clad. Moreover, since the hardened | cured material of the prepolymer (A) and the hardened | cured material of the curable composition of this invention containing a prepolymer (A) are excellent in heat resistance, the optical waveguide excellent in heat resistance is obtained.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these examples.
Examples 1 to 11 and 13 are examples, and example 12 is a comparative example.

(Solubility)
4 g of the prepolymer (A1-1) described later is added to 16 g of the compound (B), mixed for 3 days at room temperature using a mix rotor (manufactured by ASONE, MR-5), and dissolved according to the following criteria. Judging sex.
○: The prepolymer (A1-1) was completely dissolved in the compound (B).
(Triangle | delta): The undissolved residue of the prepolymer (A1-1) was confirmed in the compound (B).
X: It did not melt at all.

(Prepolymer (A))
In N, N-dimethylacetamide (hereinafter referred to as DMAc), perfluorobiphenyl and 1,3,5-trihydroxybenzene were reacted in the presence of potassium carbonate, and then 4-acetoxystyrene was added to water. A prepolymer was synthesized by reaction in the presence of potassium oxide. The obtained DMAc solution of the prepolymer was poured into an aqueous hydrochloric acid solution for purification by reprecipitation, followed by vacuum drying to obtain a powdery prepolymer (A1-1).

(Coating solution)
5.0 g of prepolymer (A1-1), 0.3 g of IRGACURE OXE01 (manufactured by Ciba Specialty Chemicals) as a photosensitizer and 5.0 g of PGMEA as a solvent are placed in a sample bottle at room temperature using a mix rotor. By mixing for 48 hours, a coating solution for core formation was obtained.

(Compound (B))
As the compound (B), those shown in Table 1 and Table 2 were prepared.

(Thermosetting accelerator)
As the thermosetting accelerator, benzoyl peroxide (manufactured by NOF Corporation) was prepared.

(Base material)
A silicon wafer was prepared as the substrate.

[Example 1]
20 parts by mass of the powdered prepolymer (A1-1), 80 parts by mass of the compound (B-4), and 1 part by mass of a thermosetting accelerator are placed in a sample bottle and mixed at room temperature for 3 days using a mix rotor. Thus, a curable composition for forming a clad was obtained. The curable composition for clad formation was filtered using a filtration device (Millipore Corporation, filter pore size: 5 μm).

(Process (a))
The surface of the base material is spin-coated with a curable composition for forming a clad, placed in an inert oven (KOYO THERMO SYSTEMS) under a nitrogen gas atmosphere, and heated to a predetermined heating temperature (150 ° C., 160 ° C. or 190 ° C.). And an under cladding layer having a thickness of 15 μm was formed. Table 3 shows the time until the clad forming curable composition is cured (curing time).

(Process (b))
A core-forming coating solution was applied to the surface of the undercladding layer and heated at 190 ° C. for 2 hours to form a core precursor layer having a thickness of 50 μm. The core precursor layer was exposed in a state where the core precursor layer was shielded from light by the metal foil except for the portion to be the core. For the exposure, an ultrahigh pressure mercury lamp (manufactured by Quintel, UL-7000) was used, and the irradiation energy was 2520 mJ / cm ² . Then, it developed using the liquid mixture of PGMEA and ethyl lactate as a developing solution, after removing the unexposed part of a core precursor layer, it was made to dry. Furthermore, it heated at 190 degreeC for 2 hours, and formed the core of width 50micrometer and height 50micrometer.

(Process (c))
A curable composition for clad formation was spin-coated on the surfaces of the core and the under clad layer, and heated under the same conditions as in step (a) to form an over clad layer having a thickness of 60 μm. The interface between the substrate and the underclad layer was peeled off to obtain a film-like optical waveguide.

[Examples 2 to 11]
An optical waveguide was obtained in the same manner as in Example 1 except that the composition of the curable composition for forming a clad was changed as shown in Table 3.
Table 3 shows the time (curing time) until the clad forming curable composition in the step (a) is cured.

[Example 12]
20 parts by mass of the powdered prepolymer (A1-1), 80 parts by mass of the compound (B-4), 1 part by mass of a thermosetting accelerator and 20 parts by mass of PGMEA as a solvent are placed in a sample bottle. Was mixed at room temperature for 3 days to obtain a coating solution for forming a clad. The coating liquid for clad formation was filtered using a filtering device.

  A clad-forming coating solution was spin-coated on the surface of the base material, placed in an inert oven in a nitrogen gas atmosphere, and heated at 190 ° C. to form an under-cladding layer having a thickness of 15 μm. The time until the clad forming coating solution was dried and cured was 2 hours.

  The curable composition for forming a clad of Examples 1 to 11 containing no solvent is cured in a shorter time than the coating solution for forming a clad of Example 12 containing a solvent, and without taking time to form the clad, In addition, energy for forming the cladding can be saved. Moreover, the equipment which ventilates and processes the evaporated solvent becomes unnecessary, and the working environment can be kept good.

[Example 13]
The surface of a polyimide film having a thickness of 50 μm was spin-coated with the curable composition for forming a clad of Example 1, placed in an inert oven in a nitrogen gas atmosphere, heated at 190 ° C. for 5 minutes, and an under cladding layer having a thickness of 15 μm. Formed. No wrinkles occurred on the polyimide film.

  The optical waveguide obtained by the production method of the present invention is useful as a resin-made optical waveguide used for signal transmission in communication equipment and the like.

DESCRIPTION OF SYMBOLS 1 Optical waveguide 10 Core 12 Core precursor layer 20 Cladding 22 Under cladding layer 24 Over cladding layer 30 Base material

Claims (6)

A curable composition for forming a cladding or core of an optical waveguide comprising:
A fluorine-containing polyarylene prepolymer (A) having a crosslinkable functional group;
The compound represented by the following formula (I) and having no fluorine atom (B),
A curable composition substantially free of solvent.
[X] _n Y (I).
However, n is an integer of 1-5, X is a crosslinkable functional group, Y is an n-valent aliphatic or alicyclic organic group which may have an etheric oxygen atom. is there.   The curable composition of Claim 1 whose viscosity in 25 degreeC of the said compound (B) is 3000 mPa * s or less.   The ratio of the fluorine-containing polyarylene prepolymer (A) is 1 to 97% by mass in the total (100% by mass) of the fluorine-containing polyarylene prepolymer (A) and the compound (B). Item 3. The curable composition according to item 1 or 2.   The curable composition according to any one of claims 1 to 3, wherein n in the formula (I) is an integer of 2 to 3.   X in the formula (I) is at least one selected from the group consisting of vinyl group, allyl group, ethynyl group, vinyloxy group, allyloxy group, acryloyl group, acryloyloxy group, methacryloyl group and methacryloyloxy group. Item 5. The curable composition according to any one of Items 1 to 4. Forming an undercladding layer on the surface of the substrate,
Forming a core on the surface of the under cladding layer;
An over-cladding layer is formed so as to cover the surface of the under-cladding layer and the core.
The manufacturing method of an optical waveguide which uses the curable composition as described in any one of Claims 1-5 for formation of the said under clad layer and / or the said over clad layer at least.

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