JP2017187653A - Optical waveguide cladding material, optical waveguide cladding layer-forming resin film, and optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an optical waveguide that can be industrially manufactured easily and exhibits small optical transmission loss; an optical waveguide cladding material that can be used to produce such an optical waveguide; and an optical waveguide cladding layer-forming resin film using the optical waveguide cladding material.SOLUTION: An optical waveguide cladding material contains (A) a polymer having an acidic substituent, (B) a polymerizable compound having two or more ethylenically unsaturated groups, and (C) a polymerization initiator. The (B) polymerizable compound having two or more ethylenically unsaturated groups contains (B1) a polyalkylene glycol di(meth)acrylate having a structural unit derived from polyethylene glycol.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical waveguide clad material, an optical waveguide clad layer forming resin film using the optical waveguide clad material, and an optical waveguide using the optical waveguide clad layer forming resin film.

In recent years, in high-speed and high-density signal transmission between electronic elements and between wiring boards, signal interference and attenuation become barriers in conventional transmission using electric wiring, and the limits of high-speed and high-density have begun to appear. In order to overcome this problem, a technique for connecting electronic elements and wiring boards with light, so-called optical interconnection, has been studied. As an optical transmission line, polymer optical waveguides are attracting attention from the viewpoints of easy processing, low cost, high degree of freedom in wiring, and high density.
As a form of the polymer optical waveguide, a type produced on a glass epoxy resin substrate assuming application to an opto-electric hybrid board, and a flexible type not including a hard support substrate assuming connection between boards are considered suitable.

Polymer optical waveguides are required to have high heat resistance as well as transparency (low light propagation loss) from the viewpoint of the environment in which the equipment is used and component mounting. In addition, a material that can freely form a pattern required by exposure and development is desired in accordance with demands such as improvement in the degree of freedom of optical wiring design, enhancement of device functionality, and simplification of processes. As a developing method, a solvent developing type and an alkali developing type are assumed, but an alkali developing type is desired from the viewpoint of environmental load and safety.
As an optical waveguide material corresponding to such a demand, one using a (meth) acrylic polymer (for example, see Patent Document 1) is known. The resin composition for an optical waveguide using the (meth) acrylic polymer described in Patent Document 1 is alkali-developable and has a light propagation loss of 0.3 dB / cm at a wavelength of 850 nm. And in high density signal transmission, this number is not always sufficient.

Therefore, the present inventors have developed an optical waveguide having the following cladding layer and core pattern (see Patent Document 2).
That is, the first cladding layer,
A core pattern laminated on the first cladding layer that forms an optical path of an optical signal, and
The core pattern has a core peripheral surface extending in the direction of the optical path and a core body formed inside the core peripheral surface,
The core peripheral surface has a contact core peripheral surface in contact with the first cladding layer and a non-contact core peripheral surface other than the contact core peripheral surface,
The core body has a core region near the non-contact surface within a predetermined range from the peripheral surface of the non-contact core in the core body, and a core central region other than the core region near the non-contact surface in the core body. ,
The refractive index of the core region near the non-contact surface is an optical waveguide that is smaller than the refractive index of the core central region.
With the optical waveguide of Patent Document 2, further reduction of light propagation loss was achieved.

Japanese Patent No. 4241874 Japanese Patent Laying-Open No. 2015-215468

However, the actual situation is that the influence of the core pattern structure on the optical propagation loss cannot be grasped, and further development of an optical waveguide having a core pattern that can further reduce the optical propagation loss is desired.
Accordingly, an object of the present invention is to provide an optical waveguide that is easy to manufacture industrially and has a small light propagation loss, and an optical waveguide cladding material that can manufacture the optical waveguide, and the optical waveguide cladding material. The object is to provide a resin film for forming an optical waveguide clad layer used.

  As a result of intensive studies, the present inventors have (A) a polymer having an acidic substituent, (B) a polymerizable compound having two or more ethylenically unsaturated groups, (C) a polymerization initiator, And a resin film for forming an optical waveguide clad layer using the optical waveguide clad material, wherein the component (B) contains a polyalkylene glycol di (meth) acrylate having a specific structural unit If it exists, it discovered that the said subject could be solved and came to this invention.

That is, the present invention relates to the following [1] to [17].
[1] containing (A) a polymer having an acidic substituent, (B) a polymerizable compound having two or more ethylenically unsaturated groups, and (C) a polymerization initiator,
(B) An optical waveguide cladding material in which the polymerizable compound having two or more ethylenically unsaturated groups contains (B1) polyalkylene glycol di (meth) acrylate having a structural unit derived from polyethylene glycol.
[2] The light beam according to [1], wherein the component (B1) is at least one selected from the group consisting of polyethylene glycol di (meth) acrylate and poly (ethylenepropylene) glycol di (meth) acrylate. Waveguide clad material.
[3] The optical waveguide cladding material according to the above [1] or [2], wherein the component (B1) has a weight average molecular weight of 170 to 4,000.
[4] The above-mentioned [1] to [B], wherein the component (B) further contains (B2) a polymerizable compound having two or more ethylenically unsaturated groups (excluding the component (B1)). 3] The optical waveguide cladding material according to any one of [3].
[5] Any of [1] to [4] above, wherein the content of the component (B) is 20 to 70 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B). An optical waveguide cladding material according to any one of the above.
[6] Any of [1] to [5] above, wherein the content of the component (B1) in the component (B) is 30 to 100 parts by mass with respect to 100 parts by mass of the total amount of the component (B). An optical waveguide cladding material according to any one of the above.
[7] The optical waveguide cladding material according to any one of [1] to [6], wherein (C) the polymerization initiator is a photo radical polymerization initiator.
[8] The optical waveguide cladding material according to any one of [1] to [7], further comprising (D) a thermosetting resin.
[9] (D) The thermosetting resin is at least one selected from the group consisting of a compound having two or more epoxy groups in the molecule and a compound having an epoxy group and an ethylenically unsaturated group in the molecule. The optical waveguide cladding material according to [8] above.
[10] A resin film for forming an optical waveguide cladding layer, comprising the optical waveguide cladding material according to any one of [1] to [9].
[11] The optical waveguide cladding layer according to [10], including a base film, a resin layer containing the optical waveguide cladding material according to any one of [1] to [9], and a protective film. Forming resin film.
[12] An optical waveguide having a core and a clad layer formed using the optical waveguide clad layer-forming resin film according to [10] or [11].
[13] The optical waveguide according to [12], wherein the core portion has a portion formed by mixing a core material forming the core portion with a cladding material forming the cladding layer.
[14] The optical waveguide according to [13], wherein the core portion includes 10 to 90% by volume of a portion formed by mixing the cladding material with the core material.
[15] The optical waveguide according to [13] or [14], wherein in the core portion, a portion formed by mixing the clad material with the core material occupies 40 to 90% by volume.
[16] The optical device according to any one of [12] to [15], wherein the clad layer has a portion formed by mixing a core material forming a core portion with a clad material forming the clad layer. Waveguide.
[17] The optical waveguide according to any one of [12] to [16], wherein the light propagation loss at a wavelength of 850 nm is 0.25 dB / cm or less.

  ADVANTAGE OF THE INVENTION According to this invention, industrial manufacture is easy and provides an optical waveguide with small optical propagation loss, and the optical waveguide clad material which can manufacture this optical waveguide, and this optical waveguide clad material were used. A resin film for forming an optical waveguide cladding layer can be provided.

It is sectional drawing which shows the example of the optical waveguide produced using the optical waveguide clad material of this invention. It is sectional drawing which shows the structural example of the optical waveguide of this invention. It is sectional drawing which shows the manufacturing method of the optical waveguide which forms the resin film for optical waveguide clad layer formation using a lower clad layer, a core part, and an upper clad layer.

In the resin composition for forming an optical waveguide used for alkali development, the present inventors have previously left an alkali cation remaining on the surface layer of the core part when the core part (also referred to as a core pattern) is formed by an alkali development process. Therefore, the phenomenon in which the total light transmittance decreases or yellows due to this, and the light loss deteriorates as a result is captured. Then, the cause is analyzed, and an approximate expression of the Lorentz-Lorenz equation relating to the refractive index of the polymer. Refractive index n ≈ constant a × polarization (α) × material density (V) + b
In this equation, attention was paid to the material density (V) of the above equation. If the material density (V) of the surface layer affected by alkali development is reduced, the refractive index of the surface layer of the core portion is reduced, and a large amount of light propagates through the core having a high refractive index, thereby improving the light propagation loss. Assuming that it is, it examined from the characteristic of the whole material, and the component side of the material (refer patent document 2).
The inventors of the present invention have considered that an optical waveguide with a small optical propagation loss can be provided by further grading the refractive index change between the outer peripheral portion and the central portion of the core pattern through further examination. . Therefore, a method of infiltrating the raw material of the cladding layer of the optical waveguide, that is, the optical waveguide cladding material (hereinafter sometimes simply referred to as cladding material) into the core portion was examined. Specifically, the cross-linking reaction is not performed when the core portion is formed or the degree of the cross-linking reaction is suppressed, and a specific clad material (optical waveguide clad layer forming resin film) is added when the clad layer is formed. By using it, the clad material could penetrate into the core part while forming the clad layer. As a result, a core portion having a larger refractive index distribution can be formed even inside the core portion, and an optical waveguide having a smaller optical propagation loss has been successfully manufactured.
Hereinafter, one embodiment of the present invention will be described in detail.

  In the present invention, at least a part of the refractive index around the periphery of the core pattern is smaller than the refractive index at the center of the core pattern. More specifically, from the center of the core pattern toward the outer periphery (upper clad layer side to be described later), there is a portion where the refractive index is gradually reduced, between the high refractive index region and the low region, Since the change in refractive index is continuous, this belongs to the so-called GI (graded index type) refractive index distribution. As a result, the light propagating through the core pattern is further propagated closer to the center of the core pattern, so that it is less susceptible to the roughness of the side wall of the core pattern, and a further reduction in light propagation loss is possible. Further, by having a lower cladding layer and / or an upper cladding layer having a lower refractive index on the outside of the core portion, it is possible to further reduce the light propagation loss.

An example of an optical waveguide produced using the clad material of the present invention based on the above principle is shown in FIG. In FIG. 1, (a) is a diagram schematically showing a cross-sectional view of an optical waveguide, and (b) is an enlarged view of one of the cross-sections of the core portion formed in the optical waveguide (portion surrounded by a dotted line). It is a photograph taken.
FIG. 1 shows an optical waveguide 1 having a core pattern 2 showing approximate positions of a core pattern central portion 3 and a core pattern outer peripheral portion 4. The clad material forming the upper clad layer 5 penetrates into the core pattern 2, and the lower clad layer 6 having a lower refractive index and the upper clad on the lower clad layer 6 outside the outer peripheral portion 4 of the core pattern. By arranging the layer 5, light that propagates through the core pattern 2 and leaks to the outside of the core pattern outer peripheral portion 4 can be very efficiently retained in the core pattern 2. it can. With such an optical waveguide, for example, light propagating through the linear core pattern 2 easily propagates through the core pattern central portion 3, resulting in a low optical propagation loss. The light that is about to leak into the core pattern 2 is totally reflected between the lower clad layer 6 or the upper clad layer 5 and the core pattern 2 having a larger refractive index difference, so that light propagation loss is less likely to occur.

[Optical waveguide cladding material]
The clad material of the present invention for realizing the above-described embodiments includes (A) a polymer having an acidic substituent, (B) a polymerizable compound having two or more ethylenically unsaturated groups, and (C) a polymerization initiator. And (B) a polymerizable compound having two or more ethylenically unsaturated groups contains (B1) polyalkylene glycol di (meth) acrylate having a polyethylene glycol structural unit. Here, the optical waveguide clad material or clad material refers to a mixture of raw materials for the clad layer.
By using such a clad material, the clad material efficiently penetrates into the core part when the clad layer is formed, so that the core part exhibits the above-described characteristics. Propagation mainly occurs near the target center, and low optical propagation loss can be achieved.
Hereinafter, each component of the clad material of the present invention will be described in detail.

((A) component: polymer having an acidic substituent)
(A) As an acidic substituent of the polymer which has an acidic substituent of a component, a carboxyl group, a sulfonic acid group, a phenolic hydroxyl group, an alcoholic hydroxyl group, an amino group etc. are mentioned, for example, A hydroxyl group and a carboxyl group are preferable.
The component (A) is preferably a (meth) acrylic polymer having an acidic substituent, more preferably a (meth) acrylic polymer having at least one selected from the group consisting of a hydroxyl group and a carboxyl group, and having a hydroxyl group (meta Acrylic polymers are more preferred. In addition, (meth) acryl means acryl and / or methacryl.
Examples of the (meth) acrylic polymer having an acidic substituent include (meth) acrylic acid, various (meth) acrylic acid esters [(meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyalkyl ester, etc.], (meta ) Homopolymer or copolymer of (meth) acrylic monomer such as acrylamide; (meth) acrylic monomer and other polymerizable unsaturated group-containing monomer (for example, styrene, α-methylstyrene, maleic anhydride, etc.), etc. And a copolymer thereof.
(A) A component may be used individually by 1 type and may use 2 or more types together.
More specifically, the component (A) is preferably a polymer having a structural unit derived from the polymerizable compound (A-1) having a carboxyl group. The component (A) is a component other than the structural unit derived from the polymerizable compound (A-2) having a hydroxyl group and the component (A-1) and the component (A-2) together with the component (A-1). It may be a copolymer having at least one structural unit selected from the group consisting of structural units derived from the polymerizable compound (A-3). The structural unit derived from the component (A-1) and the (A -3) A copolymer having a structural unit derived from the component is preferable.

(A-1) component;
Examples of the polymerizable compound (A-1) having a carboxyl group include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, and itaconic acid; (Meth) acrylic acid derivatives having a carboxyl group and an ester bond, such as 2-succinoloylethyl (meth) acrylate, 2-malenoylethyl (meth) acrylate, 2-hexahydrophthaloylethyl (meth) acrylate, etc. Is mentioned. Among these, acrylic acid, methacrylic acid, and 2-hexahydrophthaloylethyl (meth) acrylate are preferable, acrylic acid and methacrylic acid are more preferable, and methacrylic acid is more preferable.
(A-1) A component may be used individually by 1 type and may use 2 or more types together.

(A-2) About component;
Examples of the polymerizable compound (A-2) having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and 2-hydroxy. Hydroxyl-containing aliphatic (meth) acrylates such as butyl (meth) acrylate; 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3- (o-phenylphenoxy) propyl (meth) acrylate, 2-hydroxy Examples include hydroxyl group-containing aromatic (meth) acrylates such as -3- (1-naphthoxy) propyl (meth) acrylate and 2-hydroxy-3- (2-naphthoxy) propyl (meth) acrylate.
However, in the case of a polymerizable compound having both a carboxyl group and a hydroxyl group, the compound having a carboxyl group is preferentially classified as the component (A-1).
Among these, from the viewpoint of low light propagation loss, aliphatic (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate; 2-hydroxy Aromatic (meth) acrylates such as -3-phenoxypropyl (meth) acrylate and 2-hydroxy-3- (o-phenylphenoxy) propyl (meth) acrylate are preferred, aliphatic (meth) acrylates are more preferred, and 2- More preferred is hydroxyethyl (meth) acrylate.
(A-2) A component may be used individually by 1 type and may use 2 or more types together.

(A-3) component;
The polymerizable compound (A-3) other than the component (A-1) and the component (A-2) is mainly composed of mechanical properties, transparency, and refractive index of the polymer having an acidic substituent as the component (A). Can be controlled.
As such a polymerizable compound, (meth) acrylic acid ester is preferable, and (meth) acrylic acid alkyl ester is more preferable. Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, and butoxyethyl (meth). Acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl heptyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) ) Acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, Teariru (meth) acrylate, behenyl (meth) acrylate. Among these, from the viewpoint of low light propagation loss, methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate are preferable, and methyl (meth) acrylate and butyl (meth) acrylate are more preferable.
(A-3) A component may be used individually by 1 type and may use 2 or more types together. (A-3) As a component, it is preferable to use 2 or more types together, and it is more preferable to use methyl (meth) acrylate and butyl (meth) acrylate together.

  In the component (A), the content of the structural unit derived from the polymerizable compound (A-1) having a carboxyl group is preferably 3 to 60 mol%. If it is 3 mol% or more, the film tends to have low tack, and the handleability of the film is improved. If it is 60 mol% or less, when the clad material is laminated on the base material described later, it tends to have a high adhesion to the base material. From the above viewpoint, the content is more preferably 5 to 50 mol%, further preferably 10 to 40 mol%, and particularly preferably 20 to 40 mol%.

  In the component (A), the content of the structural unit derived from the polymerizable compound (A-2) having a hydroxyl group is preferably 0 to 50 mol%. If it is 50 mol% or less, the film tack tends to be small and the adhesion to the substrate tends to be good. From the above viewpoint, it is more preferably 0 to 35 mol%, further preferably 0 to 15 mol%, and particularly preferably 0 to 5 mol%.

In the component (A), the content of the structural unit derived from the polymerizable compound (A-3) other than the component (A-1) and the component (A-2) is derived from the component (A-1). The total of the structural unit, the structural unit derived from the component (A-2), and the structural unit derived from the component (A-3) is 100 mol%.
From the viewpoint of controlling the mechanical properties, transparency and refractive index of the component (A), the content of the structural unit derived from the component (A-3) is preferably 30 to 97 mol%. If it is 30 mol% or more, low light propagation loss tends to be sufficient, and if it is 97 mol% or less, the film tends to have low tack, and the handleability of the film is improved. From the above viewpoint, it is more preferably 30 to 90 mol%, further preferably 50 to 90 mol%, and particularly preferably 60 to 80 mol%.
In addition, in (A) component, the content rate of the structural unit derived from said (A-1)-(A-3) component is set so that a sum total may be 100 mass% from the content rate of each said structural unit. Each is selected.
In particular, when the component (A) is a copolymer having a structural unit derived from the component (A-1) and a structural unit derived from the component (A-3), the component (A-1) is derived from the component (A-1). Although there is no restriction | limiting in particular in content ratio [(A-1) :( A-3)] of a structural unit and the structural unit derived from the said (A-3) component, Preferably it is 10: 90-50 by molar ratio. : 50, more preferably 20:80 to 50:50.

  Although there is no restriction | limiting in particular in the manufacturing method of (A) component, For example, the said (A-1)-(A-3) component is superposed | polymerized or co-polymerized using a suitable polymerization initiator (preferably radical polymerization initiator). (A) component can be obtained by superposing | polymerizing. At this time, an organic solvent can also be used as needed.

  The polymerization initiator is not particularly limited, and examples thereof include ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, and methylcyclohexanone peroxide; 1,1-bis (t-butylperoxy) cyclohexane, 1 , 1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) ) Peroxyketals such as cyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane; hydroperoxides such as p-menthane hydroperoxide; α, α′-bis (t -Butylperoxy) diisopropylbenzene, dicumyl peroxide, t-butyl Dialkyl peroxides such as tilcumyl peroxide and di-t-butyl peroxide; diacyl peroxides such as octanoyl peroxide, lauroyl peroxide, stearyl peroxide and benzoyl peroxide; bis (4-t-butylcyclohexyl) peroxide Peroxycarbonates such as oxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-3-methoxybutyl peroxycarbonate; t-butyl peroxypivalate, t- Hexyl peroxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t -Hexylperoxy 2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxyisopropylmonocarbonate, t-butylperoxy-3,5,5- Trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-butyl peroxybenzoate, t-hexyl peroxybenzoate, 2, Peroxyesters such as 5-dimethyl-2,5-bis (benzoylperoxy) hexane and t-butylperoxyacetate; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4 -Dimethylvaleronitrile), 2,2'-azobis (4 Such as methoxy-2'-dimethylvaleronitrile) and the like azo compounds and the like.

The organic solvent is not particularly limited as long as it can dissolve the component (A) obtained by the polymerization reaction. For example, aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene and p-cymene; cyclic ethers such as tetrahydrofuran and 1,4-dioxane; alcohols such as methanol, ethanol, isopropanol, butanol, ethylene glycol and propylene glycol; acetone , Ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate and γ-butyrolactone; ethylene carbonate, propylene Carbonates such as carbonates; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether Polyethylene such as tellurium, ethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether Alcohol alkyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate And polyhydric alcohol alkyl ether acetates such as diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone.
An organic solvent may be used individually by 1 type, and may use 2 or more types together.

  Furthermore, (A) component may contain the ethylenically unsaturated group in the side chain as needed. The composition and synthesis method are not particularly limited, but for example, a polymer having an acidic substituent as the component (A), for example, a (meth) acrylic polymer having an acidic substituent, at least one ethylenically unsaturated group, An ethylenically unsaturated group can be introduced into the side chain by addition reaction of a compound having at least one functional group selected from the group consisting of a group, an oxetanyl group, an isocyanate group, a hydroxyl group and a carboxyl group.

The compound having at least one ethylenically unsaturated group and at least one functional group selected from the group consisting of epoxy group, oxetanyl group, isocyanate group, hydroxyl group and carboxyl group is not particularly limited. Are, for example, glycidyl (meth) acrylate, α-ethylglycidyl (meth) acrylate, α-propylglycidyl (meth) acrylate, α-butylglycidyl (meth) acrylate, 2-methylglycidyl (meth) acrylate, 2-ethylglycidyl (Meth) acrylate, 2-propylglycidyl (meth) acrylate, 3,4-epoxybutyl (meth) acrylate, 3,4-epoxyheptyl (meth) acrylate, α-ethyl-6,7-epoxyheptyl (meth) acrylate 3, 4 Compounds having an ethylenically unsaturated group and an epoxy group, such as epoxycyclohexylmethyl (meth) acrylate, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether; (2-ethyl-2- Oxetanyl) methyl (meth) acrylate, (2-methyl-2-oxetanyl) methyl (meth) acrylate, 2- (2-ethyl-2-oxetanyl) ethyl (meth) acrylate, 2- (2-methyl-2-oxetanyl) ) Ethylenically unsaturated groups and oxetanyl such as ethyl (meth) acrylate, 3- (2-ethyl-2-oxetanyl) propyl (meth) acrylate, 3- (2-methyl-2-oxetanyl) propyl (meth) acrylate Compound having a group; 2- (meth) acryl Compounds having an ethylenically unsaturated group and an isocyanate group, such as royloxyethyl isocyanate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, Compounds having an ethylenically unsaturated group and a hydroxyl group, such as 2-hydroxybutyl (meth) acrylate; (meth) acrylic acid, crotonic acid, cinnamic acid, succinic acid (2- (meth) acryloyloxyethyl), 2-phthaloylethyl (meth) acrylate, 2-tetrahydrophthaloylethyl (meth) acrylate, 2-hexahydrophthaloylethyl (meth) acrylate, ω-carboxy-polycaprolactone mono (meth) acrylate, 3-vinylbenzoic acid 4-vinylbenzoic acid Of, such compound having an ethylenically unsaturated group and a carboxyl group.
Among these, from the viewpoint of transparency and reactivity, glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 2- (meth) acryloyloxyethyl isocyanate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth) acrylic acid, crotonic acid, and 2-hexahydrophthaloylethyl (meth) acrylate are preferred. These compounds may be used individually by 1 type, and may use 2 or more types together.

  The weight average molecular weight (Mw) of the component (A) is preferably 1,000 to 3,000,000. If the molecular weight is 1,000 or more, the cured product tends to have sufficient strength due to its large molecular weight. If it is 3,000,000 or less, solubility in organic solvents and component (B) There is a tendency that the compatibility with is good. From the above viewpoint, 3,000 to 2,000,000 is more preferable, 5,000 to 1,000,000 is more preferable, 5,000 to 200,000 is particularly preferable, and 5,000 to 100,000 is preferable. Most preferred. The weight average molecular weight in the present invention is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene, and the detailed measurement method is as described in the examples.

((B) component: polymerizable compound having two or more ethylenically unsaturated groups)
One of the characteristics of the present invention is that the component (B) contains a polyalkylene glycol di (meth) acrylate having a structural unit derived from (B1) polyethylene glycol. The content of the component (B1) in the component (B) is not particularly limited, but from the viewpoint of low light propagation loss, the content of the component (B) is preferably 30 to 100 parts by mass. 100 mass parts, More preferably, it is 40-100 mass parts, More preferably, it is 40-95 mass parts, Especially preferably, it is 60-95 mass parts, Most preferably, it is 85-95 mass parts.
The content ratio of “structural units derived from polyethylene glycol” in the polyalkylene glycol di (meth) acrylate that is the component (B1) is, from the viewpoint of easy penetration into the core of the clad material, On the other hand, it is preferably 5 to 100 mol%, more preferably 20 to 100 mol%, further preferably 40 to 100 mol%, particularly preferably 50 to 100 mol%, most preferably 80 to 100 mol%, It is also preferable that it is 100 mol%.
The component (B1) is preferably at least one selected from the group consisting of polyethylene glycol di (meth) acrylate and poly (ethylenepropylene) glycol di (meth) acrylate from the viewpoint of low light propagation loss. At least one selected from the group consisting of acrylate and poly (ethylenepropylene) glycol diacrylate is more preferable, polyethylene glycol di (meth) acrylate is more preferable, and polyethylene glycol diacrylate is particularly preferable.
The weight average molecular weight of the component (B1) is preferably 170 to 4,000, more preferably 300 to 4,000, still more preferably 300 to 3,000, particularly preferably 300 to 2, from the viewpoint of light propagation characteristics. 000, most preferably 300 to 900, and a range of 450 to 1,300 is also preferred.

In addition to the component (B1), the component (B) further contains (B2) a polymerizable compound having two or more ethylenically unsaturated groups (excluding the component (B1)). May be.
Examples of the ethylenically unsaturated group contained in the component (B2) include a (meth) acryloyl group, a vinyl group, and an allyl group. Among these, a (meth) acryloyl group and a vinyl group are preferable, and (meth) An acryloyl group is more preferred.
As the component (B2), from the viewpoint of transparency, heat resistance and low light propagation loss, (B2-1) di (meth) acrylate and (B2-2) trifunctional or higher poly (meth) acrylate are preferable. B2-2) A tri- or higher functional poly (meth) acrylate is more preferable.

  Examples of (B2-1) di (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (Meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-propanediol di (meth) acrylate, 2-methyl-1,3-propanediol di (meth) acrylate, 2-butyl-2-ethyl-1 , 3-propanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 1, 6-hex Di (meth) acrylates such as diol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, glycerin di (meth) acrylate; (Meth) acrylate, ethoxylated product, propoxylated product, ethoxylated propoxylated product or caprolactone modified product; ethylene glycol type epoxy di (meth) acrylate, diethylene glycol type epoxy di (meth) acrylate, polyethylene glycol type epoxy di (meth) acrylate, Propylene glycol type epoxy di (meth) acrylate, dipropylene glycol type epoxy di (meth) acrylate, polypropylene glycol type epoxy di (meth) acrylate, 1,3-propanediol Epoxy di (meth) acrylate, 2-methyl-1,3-propanediol type epoxy di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol type epoxy di (meth) acrylate, 1,4-butanediol Type epoxy di (meth) acrylate, neopentyl glycol type epoxy di (meth) acrylate, 3-methyl-1,5-pentanediol type epoxy di (meth) acrylate, 1,6-hexanediol type epoxy di (meth) acrylate, 1,9 -Nonanediol type epoxy di (meth) acrylate, 1,10-decanediol type epoxy di (meth) acrylate and other aliphatic epoxy di (meth) acrylates; cyclohexanedimethanol di (meth) acrylate, tricyclodecane dimethanol di (meth) Alicyclic di (meth) acrylates such as acrylate, hydrogenated bisphenol A di (meth) acrylate, hydrogenated bisphenol F di (meth) acrylate; ethoxylated and propoxylated alicyclic di (meth) acrylates , Ethoxylated propoxylated product or caprolactone modified product; cyclohexanedimethanol type epoxy di (meth) acrylate, tricyclodecane dimethanol type epoxy di (meth) acrylate, hydrogenated bisphenol A type epoxy di (meth) acrylate, hydrogenated bisphenol F type epoxy di Cycloaliphatic epoxy di (meth) acrylates such as (meth) acrylate; hydroquinone di (meth) acrylate, resorcinol di (meth) acrylate, catechol di (meth) acrylate, bisphenol A di (meth) acrylate Aromatic di (meth) acrylates such as bisphenol F di (meth) acrylate, bisphenol AF di (meth) acrylate, biphenol di (meth) acrylate, fluorene bisphenol di (meth) acrylate; Ethoxylated, propoxylated, ethoxylated propoxylated or caprolactone modified; hydroquinone type epoxy di (meth) acrylate, resorcinol type epoxy di (meth) acrylate, catechol type epoxy di (meth) acrylate, bisphenol A type epoxy di (meth) acrylate , Bisphenol F type epoxy di (meth) acrylate, bisphenol AF type epoxy di (meth) acrylate, biphenol type epoxy di (meth) acrylate, fluorene bis Aromatic epoxy di (meth) acrylates such as enol-type epoxy di (meth) acrylates; heterocyclic di (meth) acrylates such as isocyanuric acid di (meth) acrylates; ethoxylated isomers of the heterocyclic di (meth) acrylates; Examples thereof include propoxylated products, ethoxylated propoxylated products, or caprolactone-modified products; heterocyclic di (meth) acrylates such as isocyanuric acid monoallyl type epoxy di (meth) acrylates, and the like.

Here, “ethoxylated product, propoxylated product, ethoxylated propoxylated product” means alcohol or phenol as a raw material [for example, mono (meth) acrylate; CH ₂ = C (R ¹ ) -COO-R ² In the case of (wherein R ¹ is a hydrogen atom or a methyl group, R ² is a monovalent organic group), one or more ethylene oxides are respectively added to the alcohol or phenol instead of the one represented by HO—R ^2. (Meth) acrylate obtained by using, as a raw material, an alcohol having a structure having an added structure, an alcohol having a structure in which one or more propylene oxides are added, or an alcohol having a structure having one or more ethylene oxide and propylene oxide added [for example, ethoxy In the case of a compound, CH ₂ ═C (R ¹ ) —COO— (CH ₂ CH ₂ O) q—R ² (q is an integer of 1 or more, R ¹ and R ² are the same as described above. The same applies hereinafter. For example, an ethoxylated phenoxyethyl (meth) acrylate means a (meth) acrylate obtained by reacting an alcohol obtained by adding ethylene oxide to phenoxyethyl alcohol and acrylic acid or methacrylic acid. The caprolactone-modified product refers to a (meth) acrylate using a modified alcohol obtained by modifying an alcohol used as a raw material for (meth) acrylate with caprolactone [for example, in the case of an ε-caprolactone-modified product of mono (meth) acrylate , CH ₂ ═C (R ¹ ) —COO — ((CH ₂ ) ₅ COO) q—R ² (where q, R ¹ and R ² are the same as above). The same applies hereinafter.

Among these, from the viewpoints of transparency, heat resistance and low light propagation loss, alicyclic di (meth) acrylate; ethoxylated, propoxylated, ethoxylated propoxy of the alicyclic di (meth) acrylate. Modified, caprolactone modified; alicyclic epoxy di (meth) acrylate; bisphenol A di (meth) acrylate, bisphenol F di (meth) acrylate, bisphenol AF di (meth) acrylate, biphenol di (meth) acrylate, fluorene bisphenol di Aromatic di (meth) acrylate such as (meth) acrylate; ethoxylated product, propoxylated product, ethoxylated propoxylated product, caprolactone modified product of the above aromatic di (meth) acrylate; bisphenol A type epoxy di (meth) acrylate Bisphenol F type epoxy Aromatic epoxy di (meth) acrylates such as sidi (meth) acrylate, bisphenol AF type epoxy di (meth) acrylate, biphenol type epoxy di (meth) acrylate, and fluorene bisphenol type epoxy di (meth) acrylate; heterocyclic di (meth) acrylate; The heterocyclic di (meth) acrylate is preferably an ethoxylated product, a propoxylated product, an ethoxylated propoxylated product, or a caprolactone-modified product.
As the component (B2-1), one type may be used alone, or two or more types may be used in combination.

(B2-2) Trifunctional or higher poly (meth) acrylates include, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) ) Aliphatic poly (meth) acrylates such as acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate; ethoxylated, propoxylated, ethoxylated of the above aliphatic poly (meth) acrylate Propoxylated product or caprolactone modified product; aromatic epoxy poly (meth) acrylate such as phenol novolac type epoxy poly (meth) acrylate and cresol novolac type epoxy poly (meth) acrylate; Heterocyclic poly (meth) acrylates such as tricyanuric acid tri (meth) acrylate; ethoxylated, propoxylated, ethoxylated propoxylated or caprolactone modified products of the above-mentioned heterocyclic poly (meth) acrylate; isocyanuric acid type epoxy Examples include heterocyclic epoxy poly (meth) acrylates such as tri (meth) acrylate.
In the above, as poly (meth) acrylate, all are preferably tri (meth) acrylate, tetra (meth) acrylate, and penta (meth) acrylate, more preferably tri (meth) acrylate, and still more preferably triacrylate.
Among these, from the viewpoint of transparency, heat resistance and low light propagation loss, aliphatic poly (meth) acrylate; aromatic epoxy poly (meth) acrylate; heterocyclic poly (meth) acrylate; isocyanuric acid type epoxy poly ( (Meth) acrylates are preferred, aliphatic poly (meth) acrylates are more preferred, aliphatic tri (meth) acrylates are more preferred, pentaerythritol tri (meth) acrylates are particularly preferred, and pentaerythritol triacrylate is most preferred.
As the component (B2-2), one type may be used alone, or two or more types may be used in combination.

  It is preferable that content of the said (B) component is 20-70 mass parts with respect to 100 mass parts of total amounts of (A) component and (B) component from a viewpoint of low optical propagation loss. From the same viewpoint, the lower limit value of the amount of component (B) is more preferably 25 parts by mass, and even more preferably 35 parts by mass. Moreover, as for an upper limit, it is more preferable that it is 70 mass parts, and it is further more preferable that it is 65 mass parts.

((C) component: polymerization initiator)
The polymerization initiator is not particularly limited as long as it initiates polymerization by heating or irradiation with ultraviolet rays or the like, and examples thereof include a thermal radical polymerization initiator and a photo radical polymerization initiator. Since it can be cured, a radical photopolymerization initiator is preferred.

  Examples of the photo radical polymerization initiator include benzoinketals such as 2,2-dimethoxy-1,2-diphenylethane-1-one; 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane Α-hydroxy ketones such as -1-one and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one; 2-benzyl-2-dimethylamino- Α-amino ketones such as 1- (4-morpholinophenyl) -butan-1-one and 1,2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one; Oxime esters such as [(4-phenylthio) phenyl] -1,2-octadion-2- (benzoyl) oxime; bis (2,4,6-tri Phosphine oxides such as methylbenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide; 2- (o-chlorophenyl) ) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer 2,4,5-triaryl such as 2-mer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer Imidazole dimer; benzophenone, N, N′-tetramethyl-4,4′-dia Benzophenone compounds such as nobenzophenone, N, N′-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone; 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethyl Anthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenant Quinone compounds such as laquinone, 2-methyl-1,4-naphthoquinone and 2,3-dimethylanthraquinone; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether and benzoin phenyl ether Ter; benzoin compounds such as benzoin, methylbenzoin and ethylbenzoin; benzyl compounds such as benzyldimethyl ketal; acridine compounds such as 9-phenylacridine and 1,7-bis (9,9′-acridinylheptane): N— Examples include phenylglycine and coumarin.

  In the 2,4,5-triarylimidazole dimer, the substituents of the aryl groups at the two triarylimidazole sites may give the same and symmetric compounds, but give differently asymmetric compounds. May be. Moreover, you may combine a thioxanthone compound and a tertiary amine like the combination of diethyl thioxanthone and dimethylaminobenzoic acid.

Among these, from the viewpoints of curability, transparency, and heat resistance, α-hydroxyketone and phosphine oxide are preferable, and phosphine oxide is more preferable.
A radical photopolymerization initiator may be used individually by 1 type, and may use 2 or more types together. Furthermore, it can also be used in combination with an appropriate sensitizer.

Examples of the thermal radical polymerization initiator include ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, and methylcyclohexanone peroxide; 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t- Butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1- Peroxyketals such as bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane; hydroperoxides such as p-menthane hydroperoxide; α, α′-bis (t-butylperoxy) diisopropylbenzene , Dicumyl peroxide, t-butylcumylperoxy Dialkyl peroxides such as di-t-butyl peroxide; diacyl peroxides such as octanoyl peroxide, lauroyl peroxide, stearyl peroxide, benzoyl peroxide; bis (4-t-butylcyclohexyl) peroxydicarbonate, Peroxycarbonates such as di-2-ethoxyethyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-3-methoxybutyl peroxycarbonate; t-butyl peroxypivalate, t-hexyl peroxypi Valate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t-hexylperoxy 2-ethylhexanoe Tate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate , T-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-butylperoxybenzoate, t-hexylperoxybenzoate, 2,5-dimethyl- Peroxyesters such as 2,5-bis (benzoylperoxy) hexane and t-butylperoxyacetate; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile) ), 2,2′-azobis (4-methoxy-2′-dimethylva And azo compounds such as (relonitrile).
Among these, diacyl peroxide, peroxy ester, and azo compound are preferable from the viewpoints of curability, transparency, and heat resistance.
A thermal radical polymerization initiator may be used individually by 1 type, and may use 2 or more types together. Moreover, it can also be set as the clad material which has photocurability and thermosetting by using combining a radical photopolymerization initiator and a thermal radical polymerization initiator.

  It is preferable that content of the polymerization initiator of (C) component is 0.3-10 mass parts with respect to 100 mass parts of total amounts of (A) component and (B) component. When it is 0.3 parts by mass or more, curing is sufficient, and it is easy to suppress precipitation of unreacted materials due to insufficient curing, and when it is 10 parts by mass or less, sufficient light transmittance tends to be obtained. is there. From the above viewpoint, it is more preferably 0.35 to 7 parts by mass, further preferably 0.40 to 5 parts by mass, and particularly preferably 0.45 to 3 parts by mass.

((D) component: thermosetting resin)
The clad material of the present invention may contain a thermosetting resin as the component (D).
As the thermosetting resin, for example, at least one selected from the group consisting of a compound having two or more epoxy groups in the molecule and a compound having an epoxy group and an ethylenically unsaturated group in the molecule is preferable.
Examples of the compound having two or more epoxy groups in the molecule include bisphenol A type epoxy resin, tetrabromobisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, bisphenol AD type epoxy resin, and biphenyl. Type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, etc. bifunctional phenol glycidyl ether; hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, hydrogenated 2,2′-biphenol type epoxy resin, water Hydrogenated bifunctional phenol glycidyl ether such as 4,4′-biphenol type epoxy resin; phenol novolac type epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene-phenol type epoxy resin Polyfunctional phenol glycidyl ethers such as tetraphenylolethane type epoxy resins; bifunctional aliphatic alcohols such as polyethylene glycol type epoxy resins, polypropylene glycol type epoxy resins, neopentyl glycol type epoxy resins, 1,6-hexanediol type epoxy resins Glycidyl ether; bifunctional alicyclic alcohol glycidyl ether such as cyclohexanedimethanol type epoxy resin, tricyclodecane dimethanol type epoxy resin; polyfunctional fat such as trimethylolpropane type epoxy resin, sorbitol type epoxy resin, glycerin type epoxy resin Alcohol glycidyl ether; bifunctional aromatic glycidyl ester such as diglycidyl phthalate; tetrahydrophthalic acid diglycidyl ester, hexahydrophthal Bifunctional alicyclic glycidyl esters such as diglycidyl oxalate; bifunctional aromatic glycidyl amines such as N, N-diglycidyl aniline and N, N-diglycidyl trifluoromethylaniline; N, N, N ′, N Polyfunctional aromatic glycidylamines such as' -tetraglycidyl-4,4-diaminodiphenylmethane, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, O-triglycidyl-p-aminophenol; Bifunctional alicyclic epoxy resins such as alicyclic diepoxy acetal, alicyclic diepoxy adipate, alicyclic diepoxycarboxylate, vinylcyclohexene dioxide; 2,2-bis (hydroxymethyl) -1-butanol 1,2-epoxy-4- (2-oxiranyl) cyclohex Polyfunctional heterocyclic epoxy resins such as triglycidyl isocyanurate; polyfunctional cycloaliphatic epoxy resins emissions adduct such bifunctional or polyfunctional silicon-containing epoxy resins such as organopolysiloxane type epoxy resins. The epoxy equivalent of the epoxy resin is preferably 50 to 3,000 g / eq, more preferably 80 to 2,000 g / eq, and still more preferably 100 to 1,000 g / eq. Here, the epoxy equivalent is the mass (g / eq) of the resin per equivalent of epoxy groups, and can be measured according to the method defined in JIS K 7236.
Examples of the compound having an epoxy group and an ethylenically unsaturated group in the molecule include glycidyl (meth) acrylate, α-ethylglycidyl (meth) acrylate, α-propylglycidyl (meth) acrylate, and α-butylglycidyl (meth). Acrylate, 2-methylglycidyl (meth) acrylate, 2-ethylglycidyl (meth) acrylate, 2-propylglycidyl (meth) acrylate, 3,4-epoxybutyl (meth) acrylate, 3,4-epoxyheptyl (meth) acrylate , Α-ethyl-6,7-epoxyheptyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, o-vinylbenzyl glycidyl ether, 4-hydroxybutyl acrylate glycidyl ether, m-vinyl benzil Glycidyl ethers, such as p- vinylbenzyl glycidyl ether.
When a clad material contains (D) component, it is preferable that the content is 1-40 mass parts with respect to 100 mass parts of total amounts of (A)-(C) component. When the amount is 1 part by mass or more, a sufficient cross-linked structure is formed with the component (A), so the heat resistance tends to be good. When the amount is 40 parts by mass or less, the light propagation characteristics tend to be good. . From the same viewpoint, the content of the component (D) is more preferably 3 to 30 parts by mass, and further preferably 5 to 20 parts by mass.

((E) Mono (meth) acrylate)
The clad material of the present invention may contain mono (meth) acrylate as the component (E). There is no restriction | limiting in particular as mono (meth) acrylate, For example, the (meth) acrylate as described in Paragraph [0033] of Unexamined-Japanese-Patent No. 2015-215467 is mentioned.
When the clad material contains the component (E), the content is preferably 10 parts by mass or less, and preferably 5 parts by mass or less with respect to 100 parts by mass of the total amount of the components (A) to (C). It is more preferable.

(Additive)
In addition, the clad material of the present invention can be added with an antioxidant, an anti-yellowing agent, an ultraviolet absorber, a visible light absorber, a colorant, a plasticizer, a stabilizer, a filler, etc., if necessary. You may contain the agent in the ratio which does not have a bad influence on the effect of this invention.
When the clad material contains an additive, the content thereof is preferably 20 parts by mass or less, and preferably 10 parts by mass or less, with respect to 100 parts by mass of the total amount of the components (A) to (C). More preferably, it is 5 parts by mass or less.

[Optical waveguide core material]
The raw material of the core portion of the optical waveguide, that is, the optical waveguide core material (hereinafter sometimes simply referred to as the core material) is composed of (A ′) a polymer having an acidic substituent and (B ′) two or more ethylenic non-polymers. It contains a polymerizable compound having a saturated group and (C ′) a polymerization initiator. Here, the optical waveguide core material or the core material refers to a mixture of raw materials for the core portion.
By using such a core material, the clad material efficiently penetrates into the core portion when forming the core portion (core pattern). As described above, the light propagating through the core pattern is relatively near the center of the core pattern. The light tends to be propagated, and the light propagation loss tends to be reduced.
Hereinafter, each component of the core material will be described in detail.

((A ′) component: polymer having an acidic substituent)
(A ') As a polymer which has an acidic substituent of a component, what is necessary is just a polymer which can melt | dissolve with respect to aqueous alkali solution. Examples of the acidic substituent include a carboxyl group, a sulfonic acid group, a phenolic hydroxyl group, an alcoholic hydroxyl group, and an amino group, and a hydroxyl group and a carboxyl group are preferable.
The component (A ′) is preferably a (meth) acrylic polymer having an acidic substituent, more preferably a (meth) acrylic polymer having at least one selected from the group consisting of a hydroxyl group and a carboxyl group, and having a hydroxyl group ( More preferred are (meth) acrylic polymers. In addition, (meth) acryl means acryl and / or methacryl.
The (meth) acrylic polymer having an acidic substituent is not particularly limited as long as it dissolves in a developing solution composed of an alkaline aqueous solution and has a solubility to the extent that the intended development processing is performed. For example, (meth) acrylic acid, various (meth) acrylic acid esters [(meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyalkyl ester, etc.], homopolymers of (meth) acrylic monomers such as (meth) acrylamide Or a copolymer; a copolymer of the (meth) acrylic monomer and another polymerizable unsaturated group-containing monomer (for example, styrene, α-methylstyrene, maleic anhydride, etc.) is preferably exemplified.
As the component (A ′), one type may be used alone, or two or more types may be used in combination.
More specifically, the component (A ′) is preferably a polymer having a structural unit derived from the polymerizable compound (A′-1) having a carboxyl group. The component (A ′) is a structural unit derived from the polymerizable compound (A′-2) having a hydroxyl group, together with the component (A′-1), (A′-3) an aliphatic ring or an aromatic ring. Selected from the group consisting of a structural unit derived from a polymerizable compound having a structure and a structural unit derived from a polymerizable compound (A′-4) other than the components (A′-1) to (A′-3). It may be a copolymer having at least one structural unit, the structural unit derived from the component (A′-1), the structural unit derived from the component (A′-2), and the component (A′-3). It is preferable that the copolymer has all the structural units derived from the above and the structural units derived from the component (A′-4).

About the component (A′-1);
Examples of the polymerizable compound (A′-1) having a carboxyl group include the same compounds as the component (A-1). Among these, acrylic acid, methacrylic acid, and 2-hexahydrophthaloylethyl (meth) acrylate are preferable, acrylic acid and methacrylic acid are more preferable, and methacrylic acid is more preferable.
As the component (A′-1), one type may be used alone, or two or more types may be used in combination.

About the component (A′-2);
Examples of the polymerizable compound (A′-2) having a hydroxyl group include the same compounds as the component (A-2). Among them, from the viewpoint of transparency, aliphatic (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate; 2-hydroxy-3 Aromatic (meth) acrylates such as phenoxypropyl (meth) acrylate and 2-hydroxy-3- (o-phenylphenoxy) propyl (meth) acrylate are preferred, aliphatic (meth) acrylates are more preferred, and 2-hydroxyethyl More preferred is (meth) acrylate.
As the component (A′-2), one type may be used alone, or two or more types may be used in combination.

(A'-3) component;
Examples of the polymerizable compound (A′-3) having an aliphatic ring or an aromatic ring include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyl (meth). Alicyclic (meth) acrylates such as acrylate, isobornyl (meth) acrylate, mono (2- (meth) acryloyloxyethyl) tetrahydrophthalate, mono (2- (meth) acryloyloxyethyl) hexahydrophthalate; benzyl ( (Meth) acrylate, phenyl (meth) acrylate, o-biphenyl (meth) acrylate, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, p-cumylphenoxyethyl (meth) Acrylate, o-phenylphenoxyethyl (meth) acrylate, 1-naphthoxyethyl (meth) acrylate, 2-naphthoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, phenoxypolypropylene glycol (meth) acrylate 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3- (o-phenylphenoxy) propyl (meth) acrylate, 2-hydroxy-3- (1-naphthoxy) propyl (meth) acrylate, 2 Aromatic (meth) acrylates such as hydroxy-3- (2-naphthoxy) propyl (meth) acrylate; 2-tetrahydrofurfuryl (meth) acrylate, N- (meth) Methacryloyloxyethyl hexahydrophthalimide, 2- (meth) acryloyloxy heterocyclic such as carboxyethyl -N- carbazole (meth) acrylate, etc. These caprolactone modified products thereof.
Among these, from the viewpoint of transparency and refractive index, alicyclic (meth) acrylates and aromatic (meth) acrylates are preferred, and cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. , Dicyclopentenyl (meth) acrylate benzyl (meth) acrylate, phenyl (meth) acrylate, and o-biphenyl (meth) acrylate are more preferable, aromatic (meth) acrylate is more preferable, and phenyl (meth) acrylate is particularly preferable.
(A'-3) A component may be used individually by 1 type and may use 2 or more types together.
In the case of a polymerizable compound having both a hydroxyl group and an aliphatic ring or an aromatic ring, such as 2-hydroxy-3-phenoxypropyl (meth) acrylate contained in the component (A′-2). The polymerizable compound is classified as a polymerizable compound having a hydroxyl group as the component (A′-2), giving priority to the one having a hydroxyl group. Similarly, in the case of a polymerizable compound having both a carboxyl group and an aliphatic ring, such as 2-hexahydrophthaloylethyl (meth) acrylate contained in the component (A′-1), or In the case of a polymerizable compound having a hydroxyl group and an aliphatic ring or an aromatic ring, the compound having a carboxyl group is preferentially classified as the component (A′-1).

Regarding the component (A′-4);
The polymerizable compound (A′-4) other than the components (A′-1) to (A′-3) mainly has mechanical properties and transparency of the polymer having an acidic substituent as the component (A ′). And the refractive index can be controlled.
As such a polymerizable compound, (meth) acrylic acid ester is preferable, and (meth) acrylic acid alkyl ester is more preferable. As this (meth) acrylic-acid alkylester, the same thing as the illustration in the said (A-3) component is mentioned. Among them, from the viewpoint of transparency, methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate are preferable, methyl (meth) acrylate and butyl (meth) acrylate are more preferable, and methyl (meth) acrylate Is more preferable.
(A'-4) A component may be used individually by 1 type and may use 2 or more types together.

  In the component (A ′), the content of the structural unit derived from the polymerizable compound (A′-1) having a carboxyl group is preferably 5 to 60 mol%. If it is 5 mol% or more, it tends to dissolve in a developer composed of an alkaline aqueous solution or the like. If it is 60 mol% or less, the pattern of the photosensitive resin composition layer is selectively removed by development described later. In the developing step to be formed, the developer resistance (property that the portion that becomes a pattern without being removed by development is not attacked by the developer) tends to be good. From the above viewpoint, the content is more preferably 8 to 50 mol%, further preferably 10 to 45 mol%, and particularly preferably 15 to 40 mol%.

  In the component (A ′), the content of the structural unit derived from the polymerizable compound (A′-2) having a hydroxyl group is preferably 5 to 50 mol%. If it is 50 mol% or less, the developer resistance tends to be improved in the development step of selectively removing the layer of the photosensitive resin composition by development described later to form a pattern. From the above viewpoint, it is more preferably 5 to 35 mol%, and further preferably 5 to 20 mol%.

  In the component (A ′), the content of the structural unit derived from the polymerizable compound (A′-3) having an aliphatic ring or an aromatic ring is preferably 5 to 70 mol%. If it is 5 mol% or more, it is sufficient to increase the refractive index, and if it is 70 mol% or less, the refractive index becomes higher, and the pattern formation by development is easy without lowering the solubility in the developer. Become. From the above viewpoint, it is more preferable that it is 10-60 mol%, and it is especially preferable that it is 15-40 mol%.

In the component (A ′), the content of the structural unit derived from the polymerizable compound (A′-4) other than the components (A′-1) to (A′-3) is the component (A′-1). The total of the structural unit derived from (A′-2), the structural unit derived from the component (A′-2), the structural unit derived from the component (A′-3) and the structural unit derived from the component (A′-4) is 100 mol%. This is the amount.
From the viewpoint of controlling the mechanical properties, transparency and refractive index of the component (A ′), the content of the structural unit derived from the component (A′-4) is preferably 10 to 80 mol%. If it is 10 mol% or more, the transparency tends to be sufficient, and if it is 80 mol% or less, it becomes more transparent and tends to facilitate pattern formation by development without lowering the solubility in a developer. It is in. From the above viewpoint, the content is more preferably 20 to 70 mol%, further preferably 30 to 60 mol%, and particularly preferably 35 to 50 mol%.
In addition, in (A ') component, the content rate of the structural unit derived from said (A'-1)-(A'-4) component is 100 mass% in total from the content rate of said each structural unit. Each is selected to be.

  Although there is no restriction | limiting in particular in the manufacturing method of (A ') component, For example, the said (A'-1)-(A'-4) component is used using an appropriate polymerization initiator (preferably radical polymerization initiator). (A ') component can be obtained by making it superpose | polymerize or copolymerize. At this time, an organic solvent can also be used as needed.

About a polymerization initiator and an organic solvent, it demonstrates similarly to the description in the said (A) component.
Furthermore, (A ') component may contain the ethylenically unsaturated group in the side chain as needed. This is also explained in the same manner as the explanation for the component (A).

  The weight average molecular weight (Mw) of the component (A ′) is preferably 1,000 to 3,000,000. If the molecular weight is 1,000 or more, the cured product tends to have sufficient strength due to a large molecular weight. If it is 3,000,000 or less, the solubility in a developer composed of an alkaline aqueous solution and The compatibility with the component (B ′) tends to be good. From the above viewpoint, 3,000 to 2,000,000 is more preferable, 5,000 to 1,000,000 is more preferable, 5,000 to 200,000 is particularly preferable, and 5,000 to 100,000 is preferable. Most preferred.

The component (A ′) has an acid value so that it can be developed with various known developing solutions in the step of selectively removing a layer of the photosensitive resin composition by development described later to form a pattern. Can do. For example, when developing using an alkaline aqueous solution such as sodium carbonate, potassium carbonate, tetramethylammonium hydroxide, triethanolamine, etc., the acid value of the component (A ′) is preferably 20 to 300 mgKOH / g. When it is 20 mgKOH / g or more, development tends to be easy, and when it is 300 mgKOH / g or less, developer resistance tends not to be lowered. From the above viewpoint, when developing using the alkaline aqueous solution, the acid value of the component (A ′) is more preferably 30 to 250 mgKOH / g, and further preferably 40 to 200 mgKOH / g.
Moreover, when developing using the alkaline aqueous solution which consists of water or alkaline aqueous solution and 1 or more types of surfactant, it is preferable that the acid value of (A ') component is 10-260 mgKOH / g. When the acid value is 10 mgKOH / g or more, development tends to be easy, and when it is 260 mgKOH / g or less, the developer resistance tends not to decrease. From the above viewpoint, when developing using an alkaline aqueous solution containing one or more surfactants, the acid value of the component (A ′) is more preferably 20 to 250 mgKOH / g, and 30 to 200 mgKOH. More preferably, it is / g.

((B ′) component: polymerizable compound having two or more ethylenically unsaturated groups)
Examples of the ethylenically unsaturated group contained in the component (B ′) include a (meth) acryloyl group, a vinyl group, and an allyl group. Among these, a (meth) acryloyl group and a vinyl group are preferable, ) An acryloyl group is more preferred.
As the component (B ′), from the viewpoint of transparency, heat resistance and low light propagation loss, (B′-1) di (meth) acrylate and (B′-2) trifunctional or higher poly (meth) acrylate are included. Preferably, (B′-1) di (meth) acrylate is more preferable.

(B′-1) di (meth) acrylate is described in the same manner as the di (meth) acrylate of the component (B2-1) in the clad material. In particular, the aromatic di (meth) acrylate represented by the following general formula (1) and the aromatic di (meth) acrylate represented by the following general formula (2) are more preferable, and represented by the following general formula (1). More preferred is an aromatic di (meth) acrylate.

In formula (1), R < ¹⁰ > shows a hydrogen atom or a methyl group each independently, and may be same or different. R ¹¹ independently represents a hydrogen atom, a fluorine atom, or a monovalent organic group having 1 to 20 carbon atoms, and may be the same or different.
Examples of the monovalent organic group having 1 to 20 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an acyl group, an ester group (—CO—O—R or —O—CO—R). Where R is a hydrocarbon group), and monovalent organic groups such as a carbamoyl group, and further include a hydroxyl group, a halogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and a carbonyl group. Group, formyl group, ester group, amide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, amino group, silyl group, silyloxy group and the like. Among these, an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group are preferable from the viewpoint of transparency and heat resistance.
In formula (1), Z ² represents a single bond, an oxygen atom, a sulfur atom, —CH ₂ —, —C (CH ₃ ) ₂ —, —CF ₂ —, —C (CF ₃ ) ₂ —, —SO ₂ —. And any divalent group represented by the following formula:

R ¹² represents any one of a hydrogen atom, a fluorine atom, and a monovalent organic group having 1 to 20 carbon atoms, and may be the same or different. F represents an integer of 2 to 10. As the monovalent organic group having 1 to 20 carbon atoms, mention may be made of suitably the same as what was described as the monovalent organic group having 1 to 20 carbon atoms in R ¹¹ described above, preferred The same is true.

In the general formula (1), ^{Y 2} represents an oxygen atom, a sulfur _{atom, -OCH 2 -, - SCH 2} -, - O (CH 2 CH 2 O) g -, - O [CH (CH 3) CH 2 O] _h −, —O [CH ₂ CH (CH ₃ ) O] _i —, and —O [(CH ₂ ) ₅ CO ₂ ] _j — are included and may be the same or different. . G to j each independently represent an integer of 1 to 10.

In formula (2), k represents an integer of 1 to 10.
In the formula (2), R ¹³ represents a hydrogen atom or a methyl group, and may be the same or different. R ¹⁴ represents any one of a hydrogen atom, a fluorine atom, and a monovalent organic group having 1 to 20 carbon atoms, and may be the same or different.
As the monovalent organic group having 1 to 20 carbon atoms, the same as those described as the monovalent organic group having 1 to 20 carbon atoms in R ¹¹ described above can be suitably exemplified, and preferred ones are also included. The same.
In formula (2), Z ³ represents a single bond, an oxygen atom, a sulfur atom, —CH ₂ —, —C (CH ₃ ) ₂ —, —CF ₂ —, —C (CF ₃ ) ₂ —, —SO ₂ —. And any divalent group represented by the following formula:

R ¹⁵ represents any one of a hydrogen atom, a fluorine atom, and a monovalent organic group having 1 to 20 carbon atoms, and may be the same or different. L represents an integer of 2 to 10.
The monovalent organic group having 1 to 20 carbon atoms include the same said ^{R 14.} Among these, an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group are preferable from the viewpoints of transparency and heat resistance.

In General Formula (2), Y ³ represents an oxygen atom, a sulfur atom, —O (CH ₂ CH ₂ O) _m —, —O [CH (CH ₃ ) CH ₂ O] _n —, —O [CH ₂ CH ( The divalent group includes any of CH ₃ ) O] _o — and —O [(CH ₂ ) ₅ CO ₂ ] _p —, which may be the same or different. M to p each independently represents an integer of 1 to 10.

  (B′-2) The tri- or higher functional poly (meth) acrylate is described in the same manner as the (B2-2) component of the clad material.

  The content of the component (B ′) is preferably 20 to 70 parts by mass with respect to 100 parts by mass as a total of the components (A ′) and (B ′). When it is 20 parts by mass or more, low light propagation loss is improved, and since the component (A ′) is sufficiently entangled and cured at the time of photocuring, the developer resistance tends to be good, and 70 masses. If it is at most part, the solubility in an alkali developer tends to be good. From the above viewpoint, the lower limit of the blending amount of the component (B ′) is more preferably 25 parts by mass, and further preferably 35 parts by mass. Moreover, as for an upper limit, it is more preferable that it is 70 mass parts, and it is further more preferable that it is 65 mass parts.

((C ′) component: polymerization initiator)
The polymerization initiator is not particularly limited as long as it initiates polymerization by heating or irradiation with ultraviolet rays or the like, and examples thereof include a thermal radical polymerization initiator and a photo radical polymerization initiator. Since it can be cured, a radical photopolymerization initiator is preferred.
The thermal radical polymerization initiator and the photo radical polymerization initiator are explained in the same manner as the component (C) of the clad material.
It is preferable that content of the polymerization initiator of (C ') component is 0.3-10 mass parts with respect to 100 mass parts of total amounts of (A') component and (B ') component. When it is 0.3 parts by mass or more, curing is sufficient, and it is easy to suppress precipitation of unreacted materials due to insufficient curing, and when it is 10 parts by mass or less, sufficient light transmittance tends to be obtained. is there. From the above viewpoint, it is more preferably 0.35 to 7 parts by mass, further preferably 0.40 to 5 parts by mass, and particularly preferably 0.45 to 3 parts by mass.

((D ′) component: thermosetting resin)
The core material may contain a thermosetting resin as a component (D ′).
The thermosetting resin is preferably at least one selected from the group consisting of a compound having two or more epoxy groups in the molecule and a compound having an epoxy group and an ethylenically unsaturated group in the molecule.
Examples of the compound having two or more epoxy groups in the molecule and the compound having an epoxy group and an ethylenically unsaturated group in the molecule include the same as the thermosetting resin of the component (D).
When a core material contains (D ') component, it is preferable that the content is 1-40 mass parts with respect to 100 mass parts of total amounts of (A')-(C ') component. When it is 1 part by mass or more, it forms a sufficient cross-linked structure with the component (A), so the heat resistance tends to be good, and when it is 40 parts by mass or less, the solubility in an alkali developer is good. Tend to be. From the same viewpoint, the content of the component (D ′) is more preferably 3 to 35 parts by mass, and further preferably 5 to 30 parts by mass.

((E ') mono (meth) acrylate)
The core material of the present invention may contain mono (meth) acrylate as the component (E ′). There is no restriction | limiting in particular as mono (meth) acrylate, For example, the (meth) acrylate as described in Paragraph [0033] of Unexamined-Japanese-Patent No. 2015-215467 is mentioned.
When the (E ′) component is contained in the core material, the content is preferably 10 parts by mass or less with respect to 100 parts by mass of the total amount of the components (A ′) to (C ′), and 5 parts by mass. The following is more preferable.

(Additive)
In addition to this, the core material of the present invention may be added with an antioxidant, an anti-yellowing agent, an ultraviolet absorber, a visible light absorber, a colorant, a plasticizer, a stabilizer, a filler, etc., if necessary. You may contain the agent in the ratio which does not have a bad influence on the effect of this invention.
When the core material contains an additive, the content thereof is preferably 20 parts by mass or less, and preferably 10 parts by mass or less with respect to 100 parts by mass of the total amount of the components (A ′) to (C ′). More preferred is 5 parts by mass or less.

[Resin varnish]
(Organic solvent)
Each of the clad material and the core material may be a so-called resin varnish diluted with a suitable organic solvent. The organic solvent is not particularly limited as long as it can dissolve the clad material and the core material. For example, aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene and p-cymene; cyclic ethers such as tetrahydrofuran and 1,4-dioxane; alcohols such as methanol, ethanol, isopropanol, butanol, ethylene glycol and propylene glycol; acetone , Ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate and γ-butyrolactone; ethylene carbonate, propylene Carbonates such as carbonates; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether Polyethylene such as tellurium, ethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether Alcohol alkyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate And polyhydric alcohol alkyl ether acetates such as diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone.

Among these, from the viewpoint of solubility and boiling point, aromatic hydrocarbons, alcohols, ketones, esters, polyhydric alcohol alkyl ether acetates, and amides are preferable, and toluene, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, Cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol It should be monomethyl ether acetate, N, N-dimethylacetamide Preferred.
Moreover, the clad material and the core material may contain the organic solvent used in the production of the component (A) and the component (A ′) as they are.
An organic solvent may be used individually by 1 type, and may use 2 or more types together.
The solid concentration in the resin varnish is usually preferably 20 to 80% by mass from the viewpoint of ease of application.

When making a clad material and a core material into a resin varnish, it is preferable to mix by stirring. Although there is no restriction | limiting in particular in the stirring method, From the viewpoint of stirring efficiency, stirring using a propeller is preferable. Although there is no restriction | limiting in particular in the rotational speed of the propeller at the time of stirring, It is preferable that it is 10-1,000 rpm (min < ^-1 >).

Although not particularly limited, the resin varnish is preferably filtered using a filter having a pore size of 50 μm or less. When the pore diameter is 50 μm or less, large foreign matters or the like are removed, and no repelling or the like occurs during varnish application, and scattering of light propagating through the core portion tends to be suppressed. From the above viewpoint, it is more preferable to filter using a filter having a pore diameter of 30 μm or less, and it is more preferable to filter using a filter having a pore diameter of 10 μm or less.
Further, although not particularly limited, it is preferable to use a resin varnish defoamed under reduced pressure. There is no restriction | limiting in particular in the defoaming method, As a specific example, the method of using a vacuum pump, a bell jar, and a defoaming apparatus with a vacuum apparatus is mentioned. Although there is no restriction | limiting in particular in the pressure at the time of pressure reduction, The pressure which the organic solvent contained in a resin varnish does not boil is preferable. Although there is no restriction | limiting in particular in vacuum degassing time, It is preferable that it is 3 to 60 minutes. If it is 3 minutes or longer, bubbles dissolved in the resin varnish tend to be removed. If it is 60 minutes or less, the organic solvent contained in the resin varnish tends to be less volatile.

  The refractive index of the cured film formed from the clad material or core material of the present invention in the wavelength range of 830 to 850 nm at a temperature of 25 ° C. is preferably 1.400 to 1.700. If the refractive index is 1.400 to 1.700, the refractive index is not significantly different from that of a normal optical resin, and therefore the versatility as an optical material tends to be hardly impaired. From the above viewpoint, the refractive index is more preferably 1.425 to 1.675, and further preferably 1.450 to 1.650.

  The transmittance at a wavelength of 400 nm of a cured film having a thickness of 50 μm formed from the clad material or core material of the present invention is preferably 80% or more. If it is 80% or more, it can be said that the amount of transmitted light is sufficient. From the same viewpoint, the transmittance is more preferably 85% or more. In addition, there is no restriction | limiting in particular about the upper limit of the transmittance | permeability.

[Resin film for forming optical waveguide cladding layer and resin film for forming optical waveguide core]
From the clad material and the core material, an optical waveguide clad layer forming resin film containing the clad material and an optical waveguide core part forming resin film containing the core material can be formed. Hereinafter, the resin film for forming an optical waveguide clad layer and the resin film for forming an optical waveguide core part of the present invention (hereinafter may be collectively referred to as an optical waveguide forming resin film) will be described.

  The resin film for forming an optical waveguide can be easily produced by applying the clad material or core material to a base material (base film) in the state of a resin varnish, and then removing the organic solvent. Moreover, you may manufacture a film by apply | coating the clad material or core material which does not contain an organic solvent directly to a base material (base film).

There is no restriction | limiting in particular as said base film, For example, Polyester, such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; Polyolefin, such as polyethylene and a polypropylene; Polycarbonate, polyamide, polyimide, polyamideimide, polyetherimide, polyether Examples thereof include sulfide, polyethersulfone, polyetherketone, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone, and liquid crystal polymer.
Among these, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polycarbonate, polyamide, polyimide, polyamideimide, polyphenylene ether, polyphenylene sulfide, polyarylate, and polysulfone are preferable from the viewpoints of flexibility and toughness.

  The thickness of the base film can be appropriately selected depending on the intended flexibility, but it is usually preferably 3 to 250 μm. If it is 3 μm or more, the film strength tends to be sufficient, and if it is 250 μm or less, sufficient flexibility tends to be obtained. From the above viewpoint, the thickness of the base film is more preferably 5 to 200 μm, and further preferably 7 to 150 μm. In addition, from the viewpoint of improving releasability from the clad material or the core material, a film that has been subjected to a release treatment with a silicone compound, a fluorine-containing compound, or the like may be used.

The resin film for forming an optical waveguide obtained as described above is applied with a protective film on a resin layer (a layer formed from a clad material or a core material, hereinafter the same), if necessary. It is good also as a 3 layer structure laminated | stacked in order of the base film, the resin layer, and the protective film. Thereby, this invention also provides the resin film for optical waveguide clad layer formation which has a base film, the resin layer containing an optical waveguide clad material, and a protective film.
The protective film is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene. Among these, from the viewpoints of flexibility and toughness, polyesters such as polyethylene terephthalate; polyolefins such as polyethylene and polypropylene are preferable. In addition, from the viewpoint of improving the peelability from the resin layer, a film that has been subjected to a release treatment with a silicone compound, a fluorine-containing compound, or the like may be used as necessary. The thickness of the protective film may be appropriately changed depending on the intended flexibility, but is preferably 10 to 250 μm. When it is 10 μm or more, the film strength is sufficient, and when it is 250 μm or less, sufficient flexibility is obtained. From the above viewpoint, the thickness is more preferably 15 to 200 μm, and further preferably 20 to 150 μm.

  The thickness of the resin layer of the resin film for forming an optical waveguide clad layer and the resin film for forming an optical waveguide core part is not particularly limited, but both are preferably 5 to 500 μm after drying. If the thickness is 5 μm or more, the thickness is sufficient, so that the strength of the resin film or the cured product of the film tends to be sufficient. If the thickness is 500 μm or less, the drying can be sufficiently performed, so the amount of residual solvent in the resin film Without increasing, it tends to suppress foaming when the cured product of the film is heated.

  The resin film for forming an optical waveguide thus obtained can be easily stored, for example, by winding it into a roll. Alternatively, a roll-shaped film can be cut into a suitable size and stored in a sheet shape.

[Optical waveguide]
Hereinafter, the optical waveguide of the present invention will be described with reference to the drawings.
FIG. 2 is a cross-sectional view showing a configuration example of the optical waveguide of the present invention.
As shown in FIG. 2A, the optical waveguide 1 is formed on a base material 7 and is formed of a core portion 2 formed of a core material having a high refractive index and a clad material having a low refractive index. A lower clad layer 6 and an upper clad layer 5.
The resin film for forming an optical waveguide clad layer of the present invention is preferably used for forming at least one of the lower clad layer 6 and the upper clad layer 5 of the optical waveguide 1 and is preferably used for both. The resin film for forming an optical waveguide core part is preferably used for forming the core part 2. Thus, this invention provides the optical waveguide which has a core part and the clad layer formed using the said resin film for optical waveguide clad layer formation.

  By using the optical waveguide forming resin film for the formation of each clad layer and core part, interlayer adhesion between the clad layer and core part, and pattern formability (correspondence between fine lines or narrow lines) at the time of core pattern formation can be achieved. It is possible to further improve, and it is possible to form a fine pattern with a small line width and line. In addition, it is possible to provide a process with excellent productivity in which a large-area optical waveguide can be manufactured at a time.

  In the optical waveguide 1, a hard substrate such as a silicon substrate, a glass substrate, or a glass epoxy resin substrate such as FR-4 can be used as the base material 7. The optical waveguide 1 may be a flexible optical waveguide using the base film having flexibility and toughness instead of the substrate.

Further, a base film having flexibility and toughness may be functioned as the cover film 8 of the optical waveguide 1. By disposing the cover film 8, the flexibility and toughness of the cover film 8 can be imparted to the optical waveguide 1. Further, since the optical waveguide 1 is not damaged or scratched, the ease of handling is improved.
From the above viewpoint, the cover film 8 is disposed outside the upper clad layer 5 as shown in FIG. 2B, or the lower clad layer 6 and the upper clad layer 5 as shown in FIG. The cover film 8 may be arrange | positioned on both the outer sides.
If the optical waveguide 1 has sufficient flexibility and toughness, the cover film 8 may not be disposed as shown in FIG.

Although there is no restriction | limiting in particular in the thickness of the lower clad layer 6, It is preferable that it is 2-200 micrometers. If the thickness is 2 μm or more, propagating light tends to be easily confined inside the core, and if it is 200 μm or less, the thickness of the entire optical waveguide 1 tends to be improved without being too large. The thickness of the lower cladding layer 6 refers to the average value of the shortest distance from the boundary between the core portion 2 and the lower cladding layer 6 to the lower surface of the lower cladding layer 6.
There is no restriction | limiting in particular about the thickness of the resin film for lower clad layer formation, and thickness is adjusted so that the thickness of the lower clad layer 6 after hardening may become said range.

  The height of the core part 2 is not particularly limited, but is preferably 10 to 100 μm. If the height of the core is 10 μm or more, the alignment tolerance tends not to be reduced in the coupling with the light emitting / receiving element or the optical fiber after the optical waveguide is formed. In coupling with an element or an optical fiber, coupling efficiency tends not to decrease. From the above viewpoint, the height of the core part is more preferably 15 to 80 μm, and further preferably 20 to 70 μm. In addition, there is no restriction | limiting in particular about the thickness of the resin film for optical waveguide core part formation, Thickness is adjusted so that the height of the core part after hardening may become said range.

  The thickness of the upper clad layer 5 is not particularly limited as long as the core portion 2 can be embedded, but the thickness after drying is preferably 12 to 500 μm. The thickness of the upper clad layer 5 may be the same as or different from the thickness of the lower clad layer 6 formed first, but is thicker than the thickness of the lower clad layer 6 from the viewpoint of embedding the core portion 2. It is preferable to do. The thickness of the upper clad layer 5 refers to the average value of the shortest distance from the boundary between the core portion 2 and the lower clad layer 6 to the upper surface of the upper clad layer 5.

The waveguide of the present invention manufactured as described above has a portion formed by mixing the core material forming the core portion with the clad material forming the cladding layer in the core portion. In the core portion, the portion formed by mixing the clad material with the core material preferably occupies 10 to 90% by volume, more preferably 20 to 90% by volume, and 30 to 90% by volume. More preferably, it occupies 40 to 90% by volume, more preferably 50 to 90% by volume, 60 to 90% by volume, and 60 to 80% by volume.
Further, the clad layer may have a portion formed by mixing the clad material forming the clad layer with the core material forming the core part.
The optical waveguide of the present invention can realize a light propagation loss of 0.25 dB / cm or less, further 0.15 dB / cm or less as a light propagation loss at a wavelength of 850 nm. It is.

Hereinafter, a method for manufacturing the optical waveguide 1 using the resin film for forming an optical waveguide will be described.
As described above, the method of manufacturing the optical waveguide 1 of the present invention is preferably a method of manufacturing the optical waveguide forming resin film by a lamination method.

Hereinafter, a method of manufacturing the optical waveguide 1 using the optical waveguide forming resin film for the lower clad layer, the core portion, and the upper clad layer will be described with reference to FIG.
First, as shown in FIG. 3A, as a first step, a resin film for forming an optical waveguide cladding layer is laminated on a substrate 7 to form a lower cladding layer 6. As a laminating method in the first step, there is a method of laminating by pressing with a roll laminator or a flat plate laminator while heating, but from the viewpoint of adhesion and followability, a flat laminator is used. It is preferable to laminate the resin film for lower clad layer formation under reduced pressure. In the present invention, the flat plate type laminator refers to a laminator in which a laminated material is sandwiched between a pair of flat plates and pressed by pressing the flat plate. For example, a vacuum pressurizing laminator can be suitably used. The heating temperature here is preferably 40 to 130 ° C., and the pressing pressure is preferably 0.1 to 1 MPa, but these conditions are not particularly limited. When a protective film is present in the optical waveguide clad layer forming resin film, the protective film is removed and then laminated.
In addition, you may temporarily stick the resin film for optical waveguide clad layer forming on the base material 7 beforehand using a roll laminator before lamination | stacking by a vacuum pressurization type laminator. Here, from the viewpoint of improving adhesion and followability, it is preferable to perform temporary bonding while pressing, and when pressing, a laminator having a heat roll may be used while heating. The laminating temperature is preferably 20 to 130 ° C. When the temperature is 20 ° C. or higher, the adhesion between the resin film for forming the lower clad layer 6 and the base material 7 tends to be improved. When the temperature is 130 ° C. or lower, the resin layer flows too much during roll lamination. The required film thickness tends to be easily obtained. From the above viewpoint, the laminating temperature is more preferably 40 to 100 ° C. The pressure is preferably 0.2 to 0.9 MPa and the laminating speed is preferably 0.1 to 3 m / min, but these conditions are not particularly limited.

Subsequently, the optical waveguide clad layer forming resin film laminated on the base material 7 is cured by light and / or heating, the base film of the optical waveguide clad layer forming resin film is removed, and the lower clad layer 6 is removed. Form.
The irradiation amount of actinic rays when forming the lower cladding layer 6 is preferably 0.1 to 5 J / cm ² and the heating temperature is preferably 50 to 200 ° C. There is no limit.

  Next, as shown in FIG. 3B, as the second step, the optical waveguide core portion-forming resin film 9 is laminated in the same manner as in the first step. Here, the resin film 9 for forming the optical waveguide core part is designed to have a higher refractive index than the resin film for forming the lower clad layer 6 and can form a core pattern with actinic rays. Preferably it consists of.

Next, as shown in FIG. 3C, the core portion is exposed as a third step to form a core pattern (core portion 2) of the optical waveguide. Specifically, actinic rays are irradiated in an image form through a photomask 10 having a negative or positive mask pattern called an artwork. Alternatively, the active light beam may be directly irradiated on the image without passing through the photomask 10 by using laser direct drawing. Examples of the active light source include known light sources that effectively emit ultraviolet rays, such as carbon arc lamps, mercury vapor arc lamps, ultrahigh pressure mercury lamps, high pressure mercury lamps, and xenon lamps. In addition, there are those that effectively radiate visible light such as a photographic flood bulb and a solar lamp.
The actinic ray irradiation amount here is preferably 0.01 to 10 J / cm ² . If it is 0.01 J / cm ² or more, the curing reaction sufficiently proceeds, there is a tendency that the core portion 2 is less likely to flow out by a developing step described later, if it is 10J / cm ² or less, the core by exposure excessive The portion 2 does not become fat and tends to form a fine pattern. From the viewpoints described above, more preferably 0.05~5J / cm ^2, further preferably 0.1~3J / cm ^2.
In addition, you may heat after exposure from a viewpoint of the resolution of the core part 2, and adhesive improvement. The time from ultraviolet irradiation to heating after exposure is preferably within 10 minutes. If it is within 10 minutes, active species generated by ultraviolet irradiation tend to be hardly deactivated. The post-exposure heating temperature is preferably 40 to 160 ° C., and the time is preferably 30 seconds to 10 minutes.

  After the exposure, as shown in FIG. 3 (d), the base film of the optical waveguide core portion forming resin film 9 is removed to correspond to the composition of the core portion forming resin film such as an alkaline aqueous solution or an aqueous developer. Using the developed developer, development is performed by a known method such as spraying, rocking dipping, brushing, scraping, dipping or paddle. Moreover, you may use together 2 or more types of image development methods as needed.

  The base of the alkaline aqueous solution is not particularly limited. For example, an alkali hydroxide such as lithium, sodium or potassium hydroxide; an alkali carbonate such as lithium, sodium, potassium or ammonium carbonate or bicarbonate; Alkali metal phosphates such as potassium phosphate and sodium phosphate; Alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate; Sodium salts such as borax and sodium metasilicate; Tetramethylammonium hydroxide, Triethanolamine And organic bases such as ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl-1,3-propanediol and 1,3-diaminopropanol-2-morpholine. The pH of the alkaline aqueous solution used for development is preferably 9 to 11, and the temperature is adjusted according to the developability of the resin film for forming an optical waveguide core part. Further, in the alkaline aqueous solution, a surfactant, an antifoaming agent, a small amount of an organic solvent for accelerating development, and the like may be mixed.

The aqueous developer is not particularly limited as long as it is composed of water or an alkaline aqueous solution and one or more organic solvents. The pH of the aqueous developer is preferably as low as possible within the range where the development of the resin film for forming a core part can be sufficiently performed, preferably pH 8-12, and particularly preferably pH 9-10.
Examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, butanol, ethylene glycol and propylene glycol; ketones such as acetone and 4-hydroxy-4-methyl-2-pentanone; ethylene glycol monomethyl ether and ethylene glycol mono Examples thereof include polyhydric alcohol alkyl ethers such as ethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether.
These may be used individually by 1 type and may use 2 or more types together.
In general, the concentration of the organic solvent is preferably 2 to 90% by mass, and the temperature is adjusted in accordance with the developability of the resin film for forming an optical waveguide core part. Further, a small amount of a surfactant, an antifoaming agent or the like may be mixed in the aqueous developer.

  As a treatment after development, a washing treatment may be performed using a washing solution such as an acidic aqueous solution. The cleaning method is not particularly limited, and examples thereof include a spray method, a dipping method, a paddle method, a spin method, a brushing method, and a scraping method. Moreover, you may use these washing | cleaning methods together as needed.

  The acid of the acidic aqueous solution is not particularly limited, and examples thereof include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid; carboxylic acids such as formic acid, acetic acid, malonic acid, and succinic acid; lactic acid, salicylic acid, malic acid, tartaric acid, Examples include hydroxy acids such as citric acid. An acid may be used individually by 1 type and may use 2 or more types together. Among these, sulfuric acid is preferable from the viewpoint of high acidity, low volatility, and low oxidizing power.

  The pH of the acidic aqueous solution used for washing is preferably more than 0 and 5 or less. If it exceeds 0, the acidity and corrosivity are not too strong, and if it is 5 or less, the unstable monovalent salt remaining in the core pattern is effectively used as the original acidic functional group. Can be converted. From the above viewpoint, the pH of the acidic aqueous solution is more preferably from 0.1 to 4, and further preferably from 0.3 to 3. The temperature of the acidic aqueous solution is adjusted according to the pH. Further, an organic solvent, a surfactant, an antifoaming agent, or the like may be mixed in the acidic aqueous solution.

  In addition, as a treatment after development, the core portion 2 of the optical waveguide may be washed with a washing liquid composed of water and the organic solvent as necessary. The organic solvent may be used alone or in combination of two or more. In general, the concentration of the organic solvent is preferably 2 to 90% by mass, and the temperature is adjusted according to the developability of the resin film for forming an optical waveguide core part.

As processing after development or after washing, the core portion 2 may be further cured by heating at about 60 to 250 ° C. or exposure at about 0.1 to 1,000 mJ / cm ^2. In the present invention, it is preferable to form the following upper clad layer 5 without carrying out the treatment and without proceeding with the hardening of the core. As a result, the clad material tends to efficiently penetrate into the core portion.

Subsequently, as shown in FIG. 3E, as the fourth step, the upper clad layer 5 is formed by laminating the resin film for forming the optical waveguide clad layer in the same manner as in the first and second steps. To do. Here, the optical waveguide clad layer forming resin film has a lower refractive index than the optical waveguide core portion forming resin film. Further, the thickness of the upper clad layer 5 is preferably larger than the height of the core portion 2.
Next, the resin film for forming an optical waveguide cladding layer is cured by light and / or heat in the same manner as in the first step, and the upper cladding layer 5 is formed.
When the base film of the resin film for forming a clad layer is polyethylene terephthalate (PET), the active light irradiation amount is preferably 0.1 to 5 J / cm ² . On the other hand, when the base film is polyethylene naphthalate, polyamide, polyimide, polyamideimide, polyetherimide, polyphenylene ether, polyether sulfide, polyethersulfone, or polysulfone, actinic rays having a short wavelength such as ultraviolet rays are used compared to PET. Since it is difficult to pass through, the irradiation amount of actinic rays is preferably 0.5 to 30 J / cm ² . When it is 0.5 J / cm ² or more, the curing reaction tends to proceed sufficiently, and when it is 30 J / cm ² or less, the light irradiation time tends to be reduced. From the viewpoints described above, more preferably 3~27J / cm ^2, further preferably 5~25J / cm ^2.
In addition, in order to make it harden | cure, the double-sided exposure machine which can irradiate actinic light simultaneously from both surfaces can be used. Moreover, you may irradiate actinic light, heating. The heating temperature during and / or after irradiation with actinic rays is preferably 50 to 200 ° C., but these conditions are not particularly limited.
After forming the upper cladding layer 5, the base film can be removed if necessary to produce the optical waveguide 1.

  Since the optical waveguide of the present invention is excellent in transparency and light propagation properties, it may be used as an optical transmission line of an optical module. Examples of the optical module include an optical waveguide with an optical fiber in which an optical fiber is connected to both ends of the optical waveguide, an optical waveguide with a connector in which a connector is connected to both ends of the optical waveguide, and a light in which the optical waveguide and the printed wiring board are combined. Examples thereof include an electrical composite substrate, an optical / electrical conversion module that combines an optical waveguide and an optical / electrical conversion element that mutually converts an optical signal and an electrical signal, and a wavelength multiplexer / demultiplexer that combines an optical waveguide and a wavelength division filter. In the photoelectric composite substrate, the printed wiring board to be combined is not particularly limited, and either a rigid substrate such as a glass epoxy substrate or a flexible substrate such as a polyimide substrate may be used.

  Next, the present invention will be described in more detail with reference to the following examples, but these examples are not intended to limit the present invention in any way.

Synthesis example 1
[(A) Polymer for forming clad layer; production of (meth) acrylic polymer (A-1)]
100 parts by mass of methyl ethyl ketone was put into a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel, and a thermometer, and stirred while introducing nitrogen gas. The liquid temperature was raised to 65 ° C., and 30 parts by mass of methacrylic acid, 35 parts by mass of methyl methacrylate, 35 parts by mass of n-butyl methacrylate [methacrylic acid: methyl methacrylate: n-butyl methacrylate (mol) Ratio) = 0.35: 0.35: 0.25], a mixture of 3 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) and 85 parts by mass of methyl ethyl ketone was added dropwise over 3 hours, The mixture was stirred at 65 ° C. for 3 hours, and further stirred at 95 ° C. for 1 hour to obtain a (meth) acrylic polymer (A-1) solution (solid content concentration: 35 mass%).

[Measurement of weight average molecular weight]
The weight average molecular weight (in terms of standard polystyrene) of the (meth) acrylic polymer (A-1) is determined by GPC (component device: online degasser “SD-8022” manufactured by Tosoh Corporation, dual pump “DP-8020”, and differential refractive index detection. It was 80,000 as a result of measuring using a device "RI-8020"). As the column, “Gelpack GL-A150-S” and “Gelpack GL-A160-S” manufactured by Hitachi Chemical Co., Ltd. were used. Tetrahydrofuran was used as the eluent, the sample concentration was 0.5 mg / ml, and the elution rate was 1 ml / min.

Synthesis example 2
[(A ′) Core Part Forming Polymer; Production of (Meth) acrylic Polymer (A′-1)]
In a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel, and a thermometer, 47 parts by mass of propylene glycol monomethyl ether acetate and 24 parts by mass of methyl lactate were weighed and stirred while introducing nitrogen gas. . The liquid temperature was raised to 65 ° C., 34 parts by weight of methyl methacrylate, 34 parts by weight of benzyl methacrylate, 14 parts by weight of 2-hydroxyethyl methacrylate, 18 parts by weight of methacrylic acid [methyl methacrylate: benzyl methacrylate: 2-hydroxyethyl methacrylate: methacrylic acid (Molar ratio) = 0.34: 0.19: 0.11: 0.21], 2.5 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile), 43 masses of propylene glycol monomethyl ether acetate And a mixture of 24 parts by mass of methyl lactate were added dropwise over 3 hours, followed by stirring at 65 ° C. for 3 hours, and further stirring at 95 ° C. for 1 hour, Solid content concentration: 43 mass%) was obtained.
It was 34,000 as a result of measuring the weight average molecular weight of the (meth) acrylic polymer (A'-1) by the method similar to the synthesis example 1. Moreover, the acid value measured according to the following method was 120 mgKOH / g.
[Measurement of acid value]
The acid value was calculated from the amount of 0.1 mol / L potassium hydroxide aqueous solution required to neutralize the (meth) acrylic polymer (A′-1) solution. At this time, the point at which the phenolphthalein added as an indicator changed color from colorless to pink was defined as the neutralization point.

Example 1
[Preparation of optical waveguide cladding material 1]
As the component (A), 143 parts by mass (50 parts by mass in terms of solid content) of the (meth) acrylic polymer (A-1) solution obtained in Synthesis Example 1, and as the component (B), polyethylene glycol diacrylate (Shin Nakamura Chemical) "A-400" manufactured by Kogyo Co., Ltd., corresponding to component (B1).) 45 parts by mass and pentaerythritol triacrylate (corresponding to "PE-3A" manufactured by Kyoeisha Chemical Co., Ltd., (B2-2) component) As a component (C), 5 parts by mass, 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.) is weighed into a wide-mouthed plastic bottle, and a stirrer is used. Then, the mixture was stirred for 6 hours under the conditions of a temperature of 25 ° C. and a rotational speed of 400 rpm to obtain a resin varnish-like optical waveguide clad material 1.
The optical waveguide clad material 1 is made by using a polyflon filter having a pore diameter of 2 μm (“PF020” manufactured by Advantech Toyo Co., Ltd.) and a membrane filter having a pore diameter of 0.5 μm (“J050A” manufactured by Advantech Toyo Co., Ltd.) at a temperature of 25 ° C. The obtained resin varnish was filtered under pressure at a pressure of 0.4 MPa, and subsequently degassed under reduced pressure for 15 minutes using a vacuum pump and a bell jar at a reduced pressure of 50 mmHg. Used for.

[Preparation of resin film 1 for forming optical waveguide cladding layer]
The optical waveguide clad material 1 obtained above was coated on a non-treated surface of a PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd., thickness 50 μm) (“Multicoater TM-MC” manufactured by Hirano Techseed Co., Ltd.). ) Was applied. After drying at 100 ° C. for 20 minutes, a surface release treatment PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) was applied as a protective film to obtain a resin film 1 for forming an optical waveguide cladding layer. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine. In this embodiment, the thickness of the lower clad layer used is described in the embodiment. Moreover, the film thickness after hardening of a lower clad layer and the film thickness after coating were the same. The film thickness of the upper clad layer forming resin film used in this example is also described in the examples. The film thickness of the upper clad layer forming resin film described in the examples is the film thickness after coating.

Examples 2-5
[Preparation of optical waveguide cladding materials 2 to 5]
In Example 1, instead of polyethylene glycol diacrylate (“A-400” manufactured by Shin-Nakamura Chemical Co., Ltd.) as component (B), polyethylene glycol diacrylate (“A-600” manufactured by Shin-Nakamura Chemical Co., Ltd.) was used. ), Polyethylene glycol diacrylate (“A-1000” manufactured by Shin-Nakamura Chemical Co., Ltd.), polyethylene propylene glycol diacrylate (“A-1000PER” manufactured by Shin-Nakamura Chemical Co., Ltd.), or polyethylene propylene glycol diacrylate (new) Optical waveguide cladding materials 2 to 5 were obtained in the same manner except that “A-3000PER” manufactured by Nakamura Chemical Co., Ltd. was used.
[Production of resin films 2 to 5 for forming optical waveguide cladding layer]
In Example 1, resin films 2 to 5 for forming an optical waveguide cladding layer were produced in the same manner except that the optical waveguide cladding materials 2 to 5 were used instead of the optical waveguide cladding material 1.

Example 6
[Preparation of optical waveguide cladding material 6 (containing thermosetting resin of component (D)]]
As the component (A), 143 parts by mass (50 parts by mass in terms of solid content) of the (meth) acrylic polymer (A-1) solution obtained in Synthesis Example 1, and as the component (B), polyethylene glycol diacrylate (Shin Nakamura Chemical) “A-400” manufactured by Kogyo Co., Ltd. (corresponding to component (B1).) 40 parts by mass and pentaerythritol triacrylate (corresponding to “PE-3A” manufactured by Kyoeisha Chemical Co., Ltd., (B2-2) component) 5 parts by weight, 1 part by weight of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.) as component (C), and hydrogenated bisphenol A di-component as component (D) 5 parts by mass of glycidyl ether (“Epolite 4000” manufactured by Kyoeisha Chemical Co., Ltd.) is weighed in a wide-mouthed plastic bottle, and a temperature of 25 is measured using a stirrer. , By stirring 6 hours at a rotation speed 400rpm conditions, to obtain a resin varnish-shaped optical waveguide cladding material 6.
Then, in Example 1, an optical waveguide clad layer forming resin film 6 was produced in the same manner except that the optical waveguide clad material 6 was used instead of the optical waveguide clad material 1.

Reference example 1
[Preparation of optical waveguide core material 1]
As component (A ′), 140 parts by mass (60 parts by mass in terms of solid content) of the (meth) acrylic polymer (A′-1) solution obtained in Synthesis Example 2, and as component (B ′), the following ethoxylated bisphenol 40 parts by mass of A diacrylate (“Fancryl FA-324A” manufactured by Hitachi Chemical Co., Ltd.)

Furthermore, as a component (C ′), 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.) is weighed into a wide-mouthed plastic bottle, and a stirrer is used. The resin varnish-like optical waveguide core material 1 was prepared by stirring for 6 hours under the conditions of a temperature of 25 ° C. and a rotational speed of 400 rpm.
The optical waveguide core material 1 has a temperature of 25 ° C. using a polyflon filter having a pore diameter of 2 μm (“PF020” manufactured by Advantech Toyo Co., Ltd.) and a membrane filter having a pore diameter of 0.5 μm (“J050A” manufactured by Advantech Toyo Co., Ltd.) The solution was filtered under pressure at a pressure of 0.4 MPa, then degassed under reduced pressure for 15 minutes using a vacuum pump and a bell jar under conditions of a reduced pressure of 50 mmHg, and then used for production of a resin film described later.

[Preparation of resin film 1 for forming optical waveguide core]
The optical waveguide core material 1 obtained above was coated on a non-treated surface of a PET film (“Cosmo Shine A1517” manufactured by Toyobo Co., Ltd., thickness 16 μm) (“Multicoater TM-MC” manufactured by Hirano Techseed Co., Ltd.). It applied using. After drying at 100 ° C. for 20 minutes, a release PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness: 25 μm) was attached as a protective film to obtain a resin film 1 for forming an optical waveguide core part. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine, but in this example, the thickness after curing was adjusted to 50 μm.

(Measurement of light transmittance at a wavelength of 850 nm)
The resin film 1 for forming an optical waveguide core part from which the protective film (Purex A31) has been removed is placed on a slide glass (size: 76 mm × 26 mm, thickness: 1 mm) using the vacuum laminator, a pressure of 0.4 MPa, Lamination was performed under conditions of a temperature of 50 ° C. and a pressurization time of 30 seconds. Next, ultraviolet rays (wavelength 365 nm) were irradiated at 1,000 mJ / cm ² with the ultraviolet exposure machine, and further heated at 160 ° C. for 1 hour to prepare a sample for measuring light transmittance. When the light transmittance of this sample at a wavelength of 850 nm was measured using a spectrophotometer (manufactured by Hitachi High-Technologies Corporation, “U-3310”), it was 99.8%.

(Measurement of total light transmittance, YI value, and haze)
Using the sample for measuring light transmittance, total light transmittance, YI (Yellowness Index) value, and haze were measured. A chromaticity meter (“COH-300A” manufactured by Nippon Denka Kogyo Co., Ltd.) was used for the measurement. The YI value is preferably 0.15 or less, and more preferably 0.1 or less.
The total light transmittance was 99.6%, the YI value was 0.09, and the haze was 0.1%.

Example 7
[Manufacture of optical waveguides]
Obtained in Example 1 in which a protective film was removed using a vacuum pressure laminator (“MVLP-500 / 600” manufactured by Meiki Seisakusho Co., Ltd.) under conditions of a pressure of 0.4 MPa, a temperature of 80 ° C., and a pressurization time of 30 seconds. The optical waveguide clad layer forming resin film 1 (cladding layer resin thickness: 15 μm) was etched with a glass epoxy resin substrate (“MCL-E-679FB” manufactured by Hitachi Chemical Co., Ltd., plate thickness 0.6 mm, copper foil was etched) Removal) was laminated on top.
Next, the substrate film (Cosmo Shine A4100) is removed after irradiating the ultraviolet ray (wavelength 365 nm) with 4,000 mJ / cm ² using an ultraviolet exposure machine (Dainippon Screen Co., Ltd. “MAP-1200-L”). The lower clad layer 6 was formed.

Subsequently, the resin film 1 for forming an optical waveguide core part obtained in Reference Example 1 from which the protective film was removed using a roll laminator (“HLM-1500” manufactured by Hitachi Chemical Technoplant Co., Ltd.) is formed on the lower clad layer 6. And a pressure of 0.5 MPa, a temperature of 50 ° C., and a speed of 0.2 m / min.
Subsequently, the core part 2 was exposed by irradiating 1,800 mJ / cm < ² > of ultraviolet rays (wavelength 365 nm) with the said ultraviolet exposure machine through the negative photomask which has an optical waveguide formation pattern of width 35 micrometers. After removing the base film (Cosmo Shine A1517), using a spray-type developing device (“RX-40D” manufactured by Yamazaki Kikai Co., Ltd.), a 1 mass% sodium carbonate aqueous solution at a temperature of 30 ° C., a spray pressure of 0.15 MPa Development was performed under conditions of a development time of 90 seconds. Subsequently, the substrate was washed with a 0.3% by mass sulfuric acid aqueous solution (pH 1), and further washed with pure water to form a core pattern.

Next, the resin film 1 for forming an optical waveguide clad layer (cladding layer resin thickness: 70 μm) obtained in Example 1 from which the protective film was removed using the vacuum pressure laminator was used for the core portion 2 and the lower clad layer 6. On top of this, lamination was performed under conditions of a pressure of 0.4 MPa, a temperature of 80 ° C., and a pressing time of 30 seconds. Ultraviolet rays (wavelength 365 nm) were irradiated at 4,000 mJ / cm ² , the base film (Cosmo Shine A4100) was removed, and the upper cladding layer 5 was formed to obtain the optical waveguide 1 shown in FIG. Thereafter, a rigid optical waveguide having a length of 10 cm was cut out using a dicing saw (“DAD-341” manufactured by DISCO Corporation). According to the following measurement method, the optical propagation loss of the obtained optical waveguide was measured. The results are shown in Table 1.

[Measurement of optical propagation loss]
The optical propagation loss of the optical waveguide is a VCSEL (“FLS-300-01-VCL” manufactured by EXFO) having a wavelength of 850 nm as a light source, a light receiving sensor (“Q82214” manufactured by Advantest Co.), and an incident fiber (SI−). 10/125 single mode fiber, NA = 0.14), and output fiber (SI-114 / 125, NA = 0.22). The optical propagation loss was calculated by dividing the optical loss measurement value (dB) by the optical waveguide length (10 cm), and evaluated based on the following criteria.
A: 0.15 dB / cm or less B: Greater than 0.15 dB / cm and 0.20 dB / cm or less C: Greater than 0.20 dB / cm

Examples 8-11
In Example 7, instead of the optical waveguide clad layer forming resin film 1, the optical waveguide clad layer forming resin films 2 to 5 (cladding layer resin thickness: 70 μm) obtained in Examples 2 to 5 were used. An optical waveguide was manufactured in the same manner except that, and the optical propagation loss was measured. The results are shown in Table 1.

Example 12
In Example 7, instead of the optical waveguide clad layer forming resin film 1, the optical waveguide clad layer forming resin film 6 (clad layer resin thickness: 70 μm) obtained in Example 6 was used, and the lower part An optical waveguide was manufactured in the same manner except that the heat curing treatment was performed at 170 ° C. for 1 hour after the formation of the clad layer 6 and the upper clad layer 5, and the optical propagation loss was measured. The results are shown in Table 1.

Example 13
In order to confirm the refractive index distribution inside the core part in the optical waveguide produced as described above, the following samples were prepared, the refractive index was measured, and the refractive index distribution was evaluated.
(Measurement of refractive index change inside the core)
(1) Formation of core pattern On a polyimide substrate (“Kapton 200EN” manufactured by Toray DuPont Co., Ltd., size: 60 × 20 mm, thickness: 50 μm), a roll laminator (“HLM-” manufactured by Hitachi Chemical Technoplant Co., Ltd.) 1500 ”), the optical waveguide core portion-forming resin film 1 (thickness: 5 μm) from which the protective film was removed was laminated under the conditions of a pressure of 0.5 MPa, a temperature of 50 ° C., and a speed of 0.2 m / min.
Next, ultraviolet light (wavelength 365 nm) was irradiated with 1,000 mJ / cm ² with an ultraviolet exposure machine to expose the optical waveguide core portion forming resin film 1. Then, after removing the base film (Cosmo Shine A1517), using a spray type developing device (“RX-40D” manufactured by Yamazaki Kikai Co., Ltd.), a 1% by weight aqueous sodium carbonate solution at a temperature of 30 ° C. and a spray pressure of 0. Development was performed under conditions of 15 MPa and a development time of 90 seconds. Subsequently, the substrate was washed with a 0.3% by mass sulfuric acid aqueous solution (pH 1), and further washed with pure water.
(2) Formation of upper clad layer Subsequently, an optical waveguide clad layer forming resin film 1 (thickness: 70 μm) is laminated on the core film, and ultraviolet rays (wavelength 365 nm) are irradiated with 4,000 mJ / cm ² with an ultraviolet exposure machine. did.
(3) Measurement of refractive index Next, the resin layer (that is, the core material derived from the resin film 1 for forming an optical waveguide core part and the clad material derived from the resin film 1 for forming an optical waveguide cladding layer) is peeled off from the polyimide substrate. Sample B was designated.
The refractive index of the surface of sample B that was in contact with the polyimide substrate (optical waveguide core 1 film side) was measured using a prism-coupled refractometer (“Model 2020” manufactured by Metricon), and the refractive index B was obtained.

(Preparation of samples A, C, and D and measurement of refractive index)
Sample A: For the optical waveguide clad layer forming resin film 1 (thickness: 70 μm) used in “(2) Formation of upper clad layer” in the preparation of sample B, ultraviolet rays (wavelength 365 nm) were applied with an ultraviolet exposure machine. Sample A was irradiated with 000 mJ / cm ² . About the obtained sample A, the refractive index was measured on the same conditions as the sample B, and it was set as the refractive index A (refractive index of the clad material 1).
Samples C and D: Optical waveguide core portion forming resin films 2 and 3 in which the thickness of the optical waveguide core portion forming resin film 1 was changed to 10 μm and 15 μm were prepared. Next, in the preparation of Sample B, Samples C and D were prepared in the same manner as Sample B, except that the optical waveguide core portion forming resin film 1 was changed to the optical waveguide core portion forming resin films 2 and 3, respectively. Produced. About the obtained samples C and D, the refractive index was measured on the same conditions as the sample B, and it was set as the refractive indexes C and D.

Examples 14-18
In Example 13, instead of using the resin film 1 for forming an optical waveguide cladding layer, the resin films 2 to 6 for forming an optical waveguide cladding layer obtained in Examples 2 to 6 (all thicknesses are 70 μm) were used. Similarly, Samples A to D were prepared, and refractive indexes A to D were measured. The results are shown in Table 2.

  From the results of Table 2, the refractive index of the core portion (core pattern) of the optical waveguides produced in Examples 7 to 12 using the clad material of the present invention is as the distance from the upper clad layer becomes 0 μm to 15 μm. It can be seen that the refractive index changes gradually (slowly). That is, the optical waveguide obtained by the present invention has a gradual distribution of refractive index change from the core pattern outer periphery 4 to the core pattern center. Therefore, it is presumed that the optical propagation loss can be further reduced as compared with the conventional optical waveguide.

  Since the optical waveguide cladding material of the present invention can reduce the light propagation loss, it is useful as a material for the cladding layer of the optical waveguide.

DESCRIPTION OF SYMBOLS 1 Optical waveguide 2 Core part 3 Core pattern center part 4 Core pattern outer periphery periphery part 5 Upper clad layer 6 Lower clad layer 7 Base material

Claims (17)

(A) a polymer having an acidic substituent, (B) a polymerizable compound having two or more ethylenically unsaturated groups, and (C) a polymerization initiator,
(B) An optical waveguide cladding material in which the polymerizable compound having two or more ethylenically unsaturated groups contains (B1) polyalkylene glycol di (meth) acrylate having a structural unit derived from polyethylene glycol.   The optical waveguide clad material according to claim 1, wherein the component (B1) is at least one selected from the group consisting of polyethylene glycol di (meth) acrylate and poly (ethylenepropylene) glycol di (meth) acrylate.   The optical waveguide clad material according to claim 1 or 2, wherein the component (B1) has a weight average molecular weight of 170 to 4,000.   The component (B) further contains (B2) a polymerizable compound having two or more ethylenically unsaturated groups (excluding the component (B1)). The optical waveguide cladding material according to Item.   The content of the (B) component is 20 to 70 parts by mass with respect to 100 parts by mass of the total amount of the (A) component and the (B) component, according to any one of claims 1 to 4. Optical waveguide cladding material.   The content of the (B1) component in the (B) component is 30 to 100 parts by mass with respect to 100 parts by mass of the total amount of the (B) component, according to any one of claims 1 to 5. Optical waveguide cladding material.   (C) The optical waveguide clad material according to any one of claims 1 to 6, wherein the polymerization initiator is a radical photopolymerization initiator.   Furthermore, the optical waveguide clad material of any one of Claims 1-7 containing (D) thermosetting resin.   (D) The thermosetting resin is at least one selected from the group consisting of a compound having two or more epoxy groups in the molecule and a compound having an epoxy group and an ethylenically unsaturated group in the molecule. Item 9. The optical waveguide cladding material according to Item 8.   The resin film for optical waveguide clad layer formation containing the optical waveguide clad material of any one of Claims 1-9.   The resin film for optical waveguide clad layer formation of Claim 10 which has a base film, the resin layer containing the optical waveguide clad material of any one of Claims 1-9, and a protective film.   The optical waveguide which has a core part and the clad layer formed using the resin film for optical waveguide clad layer formation of Claim 10 or 11.   The optical waveguide according to claim 12, wherein the core portion includes a portion formed by mixing a clad material forming a clad layer with a core material forming the core portion.   The optical waveguide according to claim 13, wherein in the core portion, a portion formed by mixing the clad material with the core material occupies 10 to 90% by volume.   The optical waveguide according to claim 13 or 14, wherein a portion of the core portion formed by mixing the clad material with the core material occupies 40 to 90% by volume.   The optical waveguide according to any one of claims 12 to 15, wherein the clad layer has a portion formed by mixing a clad material forming the clad layer with a core material forming the core portion.   The optical waveguide according to any one of claims 12 to 16, wherein an optical propagation loss at a wavelength of 850 nm is 0.25 dB / cm or less.