JP2009116292A - Resin composition for forming clad layer, resin film for forming clad layer using it, light guide using them, and optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for forming a clad layer superior in curvature resistance and torsion resistance, and also to provide a resin film for forming the clad layer, a light guide manufactured by using them, and an optical module. <P>SOLUTION: The resin composition for forming the clad layer of the light guide containing (A) (meta)acryl polymer having a reactive functional group and weight average molecular weight of 100,000 or more, (B) an epoxy resin, (C) a phenol-based epoxy resin curing agent, (D) a light reactive monomer, and (E) a photobase generator is provided. The resin film for forming the clad layer, the light guide manufactured by using them, and an optical module are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin composition for forming a cladding layer, a resin film for forming a cladding layer, and an optical waveguide and an optical module using the same.

In high-speed and high-density signal transmission between electronic devices and between wiring boards, signal transmission interference and attenuation become barriers in conventional transmission using electric wiring, and the limits of high-speed and high-density are beginning to appear. In order to overcome this problem, a technique for optically connecting electronic elements and wiring boards, so-called optical interconnection, has been studied.
In order to transmit an optical signal over a short distance such as inside or between devices, a flexible film optical waveguide is desired. In particular, when an optical waveguide is wired inside a small portable device, the component film is often wired so that the surface of the component faces in order to save space. The polymer film optical waveguide can be bent with a small curvature radius. Is required.
In order to improve the flexibility of the flexible optical waveguide or the followability at the interface when the shape is restored, an optical waveguide using a low elastic modulus material has been developed. For example, Patent Documents 1 and 2 propose a film optical waveguide with high bending resistance and high twist resistance in which the bending elastic modulus of the optical waveguide is 1000 MPa or less and the film thickness is 150 μm or less. However, since the optical waveguide is manufactured using a stamper, there is a disadvantage that the degree of freedom in design is low and it is difficult to change the design.

Japanese Patent No. 3870976 Japanese Patent No. 3906870

  In view of the above-described problems of the prior art, the present invention provides a clad layer-forming resin composition excellent in bending resistance and twist resistance, a clad layer-forming resin film, an optical waveguide and an optical module produced using them. The purpose is to provide.

As a result of intensive studies, the present inventors have found that the above-described problem can be solved by the following method. That is, the present invention relates to the following (1) to (17).
1. (A) a (meth) acrylic polymer having a reactive functional group and a weight average molecular weight of 100,000 or more, (B) an epoxy resin, (C) a phenolic epoxy resin curing agent, (D) a photoreactive monomer And (E) a resin composition for forming a cladding layer of an optical waveguide containing a photobase generator.
2. (D) The resin composition for forming a clad layer according to 1 above, wherein the photoreactive monomer is (meth) acrylate.
3. (A) An epoxy group-containing (meth) acryl having a reactive functional group and having a weight average molecular weight of 100,000 or more and containing 0.5 to 6% by mass of an epoxy group-containing repeating unit. 3. The resin composition for forming a cladding layer according to the above 1 or 2, which is a polymer.
4). (B) The resin composition for clad layer formation in any one of said 1-3 in which an epoxy resin contains a bisphenol type epoxy resin and / or a phenol novolak type epoxy resin.
5). (C) The resin composition for forming a clad layer according to any one of the above 1 to 4, wherein the phenolic epoxy resin curing agent includes at least one of a phenol novolak resin, a bisphenol A novolak resin, and an o-cresol novolak type epoxy resin. object.
6). (B) 5 to 250 parts by mass of epoxy resin and (D) light with respect to 100 parts by mass of (A) reactive functional group and 100 parts by mass of (meth) acrylic polymer having a weight average molecular weight of 100,000 or more. 5-100 parts by mass of reactive monomer and 0.1-20 parts by mass of (E) photobase generator, (C) phenolic epoxy resin curing agent, phenolic per epoxy group of epoxy resin The resin composition for forming a clad layer according to any one of the above 1 to 5, which is contained so that an equivalent ratio of hydroxyl groups is in a range of 0.5 to 1.5.
7). The resin composition for forming a clad layer according to any one of the above 1 to 6, wherein a cured film obtained by curing the resin composition for forming a clad layer has a tensile elastic modulus at 25 ° C of 1 to 2000 MPa.
8). The resin composition for forming a clad layer according to any one of 1 to 7 above, wherein a cured film obtained by curing the resin composition for forming a clad layer has a tensile elongation at break at 10C of 10 to 600%.
9. The resin composition for forming a clad layer according to any one of the above 1 to 8, wherein the cured film formed by curing the resin composition for forming a clad layer is subjected to a bending durability test with a bending radius of 2 mm for 100,000 times and is not broken. object.
10. 10. The resin composition for forming a clad layer according to any one of the above 1 to 9, wherein the cured film formed by curing the resin composition for forming a clad layer is subjected to a twisting durability test 100,000 times and has no breakage.
11. A resin film for forming a clad layer using the resin composition for forming a clad layer according to any one of 1 to 10 above.
12 An optical waveguide in which at least one of a lower clad layer and an upper clad layer is formed from the clad layer forming resin composition according to any one of 1 to 10 above.
13. 12. An optical waveguide in which at least one of a lower clad layer and an upper clad layer is formed by the clad layer forming resin film described in 11 above.
14 Between the lower clad layer and the upper clad layer of the optical waveguide, a core part is formed of a photosensitive resin composition having a higher refractive index than both clad layers, and the relative refractive index difference between the core part and the clad layer is 1 to 14. The optical waveguide according to the above 12 or 13, which is 10%.
15. 15. The optical waveguide according to the above 13 or 14, wherein at least one of the clad layer forming resin films is composed of a clad layer forming resin and a support film, and the support film is disposed outside the clad layer with respect to the core layer.
16. 16. The optical waveguide as described in 15 above, wherein the clad layer forming resin film is formed by depositing a clad layer forming resin composition on a support film subjected to an adhesion treatment.
17. The optical module using the optical waveguide in any one of said 12-16.

  ADVANTAGE OF THE INVENTION According to this invention, the resin hardening for clad layer formation which is excellent in bending resistance and twist resistance, and an optical waveguide using the same can be provided.

  The resin composition for forming a cladding layer of the present invention includes (A) a (meth) acrylic polymer having a reactive functional group and a weight average molecular weight of 100,000 or more, (B) an epoxy resin, and (C) phenol. Type epoxy resin curing agent, (D) a photoreactive monomer, and (E) a photobase generator. Hereinafter, in the present invention, the component (A) may be abbreviated as (A) (meth) acrylic polymer.

The reason why the above-described resin composition for forming a clad can solve the above-described problems is presumed as follows. (1) In addition to bending resistance and torsion resistance, (A) a reactive functional group and a (meth) acrylic polymer having a weight average molecular weight of 100,000 or more and (B) an epoxy resin are used. (2) (C) phenolic epoxy resin curing agent and (D) photoreactive monomer obtained by ultraviolet irradiation, heat resistance, Excellent reflow resistance,

(3) Since the (E) photobase generator is used in the presence of the component (C) and the component (D), the epoxy resin and the photoreactive monomer hardly react in the absence of light, and storage stability In addition to being superior to the above, photoreaction is promoted by irradiating light, and an epoxy resin curing accelerator is generated. Therefore, the epoxy resin cures smoothly when heated, achieving both reactivity and storage stability. It is possible to obtain a film.
Hereinafter, each component will be described more specifically.

The (meth) acrylic polymer in the component (A) of the present invention refers to a polymer obtained by polymerizing acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, and derivatives thereof as monomers. The (meth) acrylic polymer may be a homopolymer of the above monomer, or may be a copolymer obtained by polymerizing two or more of these monomers. Furthermore, the copolymer containing said monomer and monomers other than the above may be used in the range which does not inhibit the effect of this invention. Further, it may be a mixture of a plurality of (meth) acrylic polymers.
(A) As a (meth) acrylic polymer having a reactive functional group and a weight average molecular weight of 100,000 or more, a functional group such as an epoxy group, an acryloyl group, a methacryloyl group, a carboxyl group, a hydroxyl group, and an episulfide group What is contained is preferable, and an epoxy group is particularly preferable in terms of crosslinkability. Specifically, an epoxy group-containing (meth) acrylic polymer containing an ethylenically unsaturated epoxide as a raw material monomer and having a weight average molecular weight of 100,000 or more can be mentioned.

As such (meth) acrylic polymer, for example, (meth) acrylic ester copolymer, acrylic rubber, and the like can be used, and acrylic rubber is more preferable. Acrylic rubber is a rubber mainly composed of an acrylate ester and mainly composed of a copolymer such as butyl acrylate and acrylonitrile, a copolymer such as ethyl acrylate and acrylonitrile, or the like.
Examples of the copolymer monomer include butyl (meth) acrylate, ethyl acrylate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile and the like.

When an epoxy group is selected as the reactive functional group, it is preferable to use an ethylenically unsaturated epoxide as the copolymer monomer component.
The ethylenically unsaturated epoxide is not particularly limited, and examples thereof include glycidyl (meth) acrylate, α-ethyl glycidyl (meth) acrylate, α-propyl glycidyl (meth) acrylate, α-butyl glycidyl (meth) acrylate, 2- Methyl glycidyl (meth) acrylate, 2-ethyl glycidyl (meth) acrylate, 2-propyl glycidyl (meth) acrylate, 3,4-epoxybutyl (meth) acrylate, 3,4-epoxyheptyl (meth) acrylate, α-ethyl -6,7-epoxyheptyl (meth) acrylate, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, 3,4-epoxycyclohexylmethyl (meth) acrylate, , 4-epoxycyclohexyl ethyl (meth) acrylate, 3,4-epoxycyclohexyl methyl (meth) acrylate, 3,4-epoxycyclohexyl-butyl (meth) acrylate. Among these, from the viewpoint of transparency and heat resistance, glycidyl (meth) acrylate, 3,4-epoxybutyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl ( (Meth) acrylate is preferred.
Such an epoxy group-containing (meth) acrylic polymer having a weight average molecular weight of 100,000 or more can be produced by appropriately selecting a monomer from the above monomers, or a commercially available product (for example, HTR- manufactured by Nagase ChemteX Corporation). 860P-3, HTR-860P-5, etc.).

  (A) In a (meth) acrylic polymer having a reactive functional group and a weight average molecular weight of 100,000 or more, the number of reactive functional groups is important because it affects the crosslink density, and also varies depending on the resin used. However, when the (meth) acrylic polymer is obtained as a copolymer of a plurality of monomers, the amount of the reactive functional group-containing monomer used as a raw material is about 0.5 to 6.0% by mass of the copolymer. It is preferably included.

  When the epoxy group-containing (meth) acrylic polymer is used as the component (A), the amount of the ethylenically unsaturated epoxide used as a raw material is preferably 0.5 to 6.0% by mass of the copolymer, 0.5 -5.0 mass% is more preferable, and 0.8-5.0 mass% is especially preferable. When the amount of the epoxy group-containing repeating unit is within this range, the epoxy group is gradually crosslinked, so that a cured film having an appropriate elastic modulus that can withstand a bending test, a torsion test and the like can be obtained.

  Other functional groups may be incorporated into the ethylenically unsaturated epoxide to form a monomer. The mixing ratio in that case is determined in consideration of the glass transition temperature (hereinafter referred to as “Tg”) of the epoxy group-containing (meth) acrylic polymer, and Tg is preferably −10 ° C. or higher. This is because when the Tg is −10 ° C. or higher, the tackiness of the resin film for forming a clad layer is appropriate, and there is no problem in handleability.

  (A) In the case of using an epoxy group-containing (meth) acrylic polymer by polymerizing the above monomer as a (meth) acrylic polymer having a reactive functional group and a weight average molecular weight of 100,000 or more, the polymerization There is no restriction | limiting in particular as a method, For example, methods, such as pearl polymerization and solution polymerization, can be used.

  (A) The weight average molecular weight of the (meth) acrylic polymer is 100,000 or more, preferably 100,000 to 3,000,000, more preferably 300,000 to 3,000,000, and 500,000 to 2,000,000. It is particularly preferred. If the weight average molecular weight is 100,000 or more, the strength and flexibility in sheet form and film form are sufficient and tackiness does not increase. On the other hand, if it is 3 million or less, the compatibility with the epoxy resin and the phenolic epoxy resin curing agent is good, the flow property is sufficient, and the core embedding property does not deteriorate. In the present invention, the weight average molecular weight is a value measured by gel permeation chromatography and converted using a standard polystyrene calibration curve.

The (B) epoxy resin used for this invention is not specifically limited, For example, the epoxy resin described in the epoxy resin handbook (Shinho Masaki edition, Nikkan Kogyo Shimbun) etc. can be used widely. Specifically, for example, hydroquinone type epoxy resin, resorcinol type epoxy resin, catechol type epoxy resin, 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, biphenyl type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, etc. bifunctional phenol glycidyl ether type epoxy resin; hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, hydrogenated 2,2 Hydrogenated bifunctional phenol glycidyl ether type epoxy resin such as' -biphenol type epoxy resin, hydrogenated 4,4'-biphenol type epoxy resin; phenol novolac type epoxy resin, Crezo Polyfunctional glycol glycidyl ether type epoxy resin having 3 or more functional groups such as luminolac type epoxy resin, dicyclopentadiene-phenol type epoxy resin, dicyclopentadiene-cresol type epoxy resin, tetraphenylolethane type epoxy resin, etc .; polyethylene glycol type epoxy resin , Polypropylene glycol type epoxy resin, neopentyl glycol type epoxy resin, 1,6-hexanediol type epoxy resin, etc. bifunctional aliphatic alcohol glycidyl ether type epoxy resin; cyclohexanediol type epoxy resin, cyclohexanedimethanol type epoxy resin, tri Bifunctional alicyclic alcohol glycidyl ether type epoxy resin such as cyclodecanedimethanol type epoxy resin; Trimethylolpropane type epoxy resin Polyfunctional aliphatic alcohol glycidyl ether type epoxy resin such as sorbitol type epoxy resin and glycerin type epoxy resin; bifunctional aromatic glycidyl ester such as diglycidyl phthalate; tetrahydrophthalic acid diglycidyl ester, hexahydro Bifunctional alicyclic glycidyl esters such as diglycidyl phthalate; bifunctional aromatic glycidyl amines such as N, N-diglycidylaniline and N, N-diglycidyltrifluoromethylaniline; N, N, N ′, N Trifunctional or more polyfunctional fragrances such as' -tetraglycidyl-4,4-diaminodiphenylmethane, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, o-triglycidyl-p-aminophenol Glycidylamine; Alicycline Bifunctional cycloaliphatic epoxy resins such as kudiepoxy acetal, alicyclic diepoxy adipate, alicyclic diepoxycarboxylate, vinylcyclohexene dioxide; 1,2-bis (hydroxymethyl) -1-butanol 1,2 -Trifunctional or higher polyfunctional alicyclic epoxy resin such as epoxy-4- (2-oxiranyl) cyclohexane adduct; Trifunctional or higher polyfunctional heterocyclic epoxy resin such as triglycidyl isocyanurate; Organopolysiloxane type epoxy Silicon-containing bifunctional or trifunctional or higher polyfunctional epoxy resins such as resins are exemplified.
Among these, from the viewpoint of transparency and compatibility with (meth) acrylic polymer, hydroquinone type epoxy resin, resorcinol type epoxy resin, catechol type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type Bifunctional phenol glycidyl ether type liquid epoxy resin such as epoxy resin and bisphenol AD type epoxy resin; the above bifunctional alicyclic liquid epoxy resin is preferable.
These compounds can be used alone or in combination of two or more.

  In this invention, the usage-amount of (B) epoxy resin has preferable 5-250 mass parts with respect to 100 mass parts of (A) (meth) acrylic polymer. When it is within this range, it is possible to ensure the elastic modulus and flowability during molding, and to obtain sufficient handleability at high temperatures. (B) As for the usage-amount of an epoxy resin, 10-100 mass parts is more preferable, and 20-50 mass parts is especially preferable.

  The (C) phenolic epoxy resin curing agent used in the present invention is effective because it is excellent in impact resistance under high temperature and high pressure when combined with an epoxy resin.

(C) The phenolic epoxy resin curing agent is not particularly limited, and examples thereof include hydroquinone, resorcinol, catechol, bisphenol A, tetrabromobisphenol A, bisphenol F, bisphenol AF, bisphenol AD, biphenol, dihydroxynaphthalene, binaphthol, and fluorene. Bifunctional phenols such as type bisphenol; phenol novolak resin, cresol novolak resin, triazine ring-containing phenol novolak resin, triazine ring-containing cresol novolak resin, bisphenol A novolak resin, tetrabromobisphenol A novolak resin, bisphenol AF novolak resin, bisphenol AD novolak Resin, biphenol novolac resin, fluorene type bisphenol novolac tree , Dicyclopentadiene - phenol novolak resin, dicyclopentadiene - novolak resins such as cresol novolak resins; phenolic resole resins, such as resole resins and cresol resol resin.
Among these, from the viewpoint of transparency and compatibility with (meth) acrylic polymers, bifunctional phenols such as hydroquinone, resorcinol, catechol, bisphenol A, bisphenol F; phenol novolac resin, cresol novolac resin, bisphenol A novolac resin, etc. The novolac resin is preferable.
These compounds can be used alone or in combination of two or more.

  In this invention, it is preferable that the usage-amount of (C) component is the range whose equivalent ratio of phenolic hydroxyl group per epoxy group of an epoxy resin is 0.5-1.5, 0.8-1.2 It is more preferable that If it is this range, hardening (crosslinking) of resin will become enough, a glass transition temperature will go up, and the moisture resistance of a hardening | curing agent can be improved.

The (D) photoreactive monomer used in the present invention is not particularly limited, and examples thereof include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and pentaerythritol. Aliphatic (meth) acrylates such as tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate; heterocyclic (meth) acrylates such as isocyanuric acid tri (meth) acrylate; these Ethoxylated products thereof; propoxylated products thereof; ethoxylated propoxylated products thereof; modified products of these caprolactones; phenol novolac type epoxy (meth) acrylates, cresol novolac type epoxy ( Aromatic epoxy (meth) acrylates such as data) acrylate.
Among these, from the viewpoint of transparency and compatibility with (meth) acrylic polymer, the above aliphatic (meth) acrylate; the above heterocyclic (meth) acrylate; the ethoxylated product thereof; the propoxylated product thereof; An ethoxylated propoxy compound of the above; preferably a caprolactone modified product thereof.
The above compounds can be used alone or in combination of two or more, and can also be used in combination with other (meth) acrylic monomers.

  (D) It is preferable that Tg of hardened | cured material is 100 degreeC or more from a heat resistant viewpoint as for a photoreactive monomer. As a method for measuring Tg of component (D), a photoinitiator is added to component (D), and a cured product irradiated with ultraviolet rays is molded to a size of about 5 × 5 mm to prepare a sample. Tg was determined by measuring the produced sample in a compression mode using EXSTRA6000 manufactured by Seiko Instruments Inc. Heat resistance is favorable in Tg being 100 degreeC or more. In this respect, Tg is more preferably 150 ° C. or higher, further preferably 200 ° C. or higher, and particularly preferably 250 ° C. or higher.

  In addition, when using several (D) component, the Tg is Tg when the mixture is measured by the said measuring method, and it is not required that Tg of each monomer is 100 degreeC or more.

  As for the usage-amount of the (D) photoreactive monomer of this invention, 5-100 mass parts is preferable with respect to 100 mass parts of (A) (meth) acrylic polymer. If the blending amount is 5 parts by mass or more, the polymerization reaction of the photoreactive monomer is likely to occur, so that the peelability from the support substrate tends to be improved. If it is 100 parts by mass or less, the low elasticity of the (meth) acrylic polymer functions, and the flex resistance is improved without the film becoming brittle. Therefore, 10-70 mass parts is more preferable, and 20-50 mass parts is especially preferable.

  The (E) photobase generator in the present invention is generally called an α-aminoketone compound. Such compounds are described, for example, in J. Org. Photopolym. Sci. Technol, Vol. 13, No. 20001, etc., and reacts as shown in the following formula when irradiated with ultraviolet rays.

  Since the α-aminoketone compound does not have radicals before being irradiated with ultraviolet rays, the polymerization reaction of the photoreactive monomer does not occur. In addition, curing of the thermosetting resin is not accelerated due to steric hindrance. However, the α-aminoketone compound is dissociated by ultraviolet irradiation, and a polymerization reaction of the photoreactive monomer occurs with the generation of radicals. In addition, dissociation of the α-aminoketone compound causes steric hindrance to be reduced and activated amines to be present. For this reason, it is presumed that the amine has a curing accelerating action of the thermosetting resin, and the heating accelerating action is subsequently exerted by heating. By such an action, there is no radical or activated amine before the ultraviolet irradiation, so that it is possible to provide a resin composition for forming a cladding layer that is very excellent in storage stability at room temperature. Moreover, since the cure rate of a photoreactive monomer or an epoxy resin changes with the structure of the radical and amine produced by ultraviolet irradiation, the (E) photobase generator can be determined by the (B) to (D) components used. .

The (E) photobase generator is not particularly limited as long as it is a compound that generates radicals and activated amines upon irradiation with ultraviolet rays. For example, 2-benzyl-2-dimethylamino-1- (4- Morpholin-4-ylphenyl) -butan-1-one, 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholin-4-ylphenyl) -butan-1-one, , 2-Methyl-1- [4- (methylthio) phenyl]-(4-morpholin) -2-ylpropan-1-one and the like α-amino ketones; bis (2,4,6-trimethylbenzoyl) phenylphosphine Oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine Phosphine oxides such as xoxide; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o -Fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer 2,4,5-triarylimidazole dimer such as a monomer.
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.
Among these, from the viewpoint of curability and transparency, the α-aminoketone is preferable.
The above photobase generators can be used alone or in combination of two or more. Furthermore, it can also be used in combination with other thermal radical polymerization initiators, photo radical polymerization initiators, and appropriate sensitizers.

  In addition to the base generator, a method of generating a base by optical Fries rearrangement, optical Claisen rearrangement, Curtius rearrangement, or Stevens rearrangement can be used.

  The base generator may be a low molecular compound having a molecular weight of 500 or less, or a compound introduced into the main chain and side chain of a polymer. The molecular weight in this case is preferably a weight average molecular weight of 1,000 to 100,000, more preferably 5,000 to 30,000 from the viewpoint of fluidity.

  In the resin composition for forming a clad layer of the present invention, the amount of the (E) photobase generator used is 0.1 to 20 parts by mass with respect to 100 parts by mass of the (A) (meth) acrylic polymer. If it is 0.1 part by mass or more, the reactivity can be improved and the residual monomer can be reduced, and if it is 20 parts by mass or less, the molecular weight increase due to the polymerization reaction can be functioned well and the low molecular weight component can be reduced. The reflow resistance can be improved. Therefore, it is preferably 0.5 to 15 parts by mass, and more preferably 1 to 5 parts by mass.

  Next, in addition to the above components (A) to (E), components that can be contained in the cladding layer forming resin composition will be described. For the purpose of improving flexibility and reflow resistance, (F) a high molecular weight resin can be added to the resin composition for forming the clad layer forming resin film of the present invention. Examples thereof include phenoxy resin, high molecular weight epoxy resin, and ultra high molecular weight epoxy resin. These can be used alone or in combination of two or more.

  (F) It is preferable that the usage-amount of high molecular weight resin shall be 40 mass parts or less with respect to 100 mass parts in total of an epoxy resin and a phenol type epoxy resin hardening | curing agent. Within this range, the Tg of the epoxy resin layer can be secured.

  Moreover, an inorganic filler can also be added to the resin composition for forming the resin film for forming a clad layer of the present invention for the purpose of improving the handleability and adjusting the melt viscosity. The inorganic filler is not particularly limited. For example, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisker, Examples thereof include boron nitride, crystalline silica, amorphous silica, and the like, and the shape of the filler is not particularly limited. These fillers can be used alone or in combination of two or more.

  Above all, for the adjustment of handleability and melt viscosity, aluminum oxide, aluminum nitride, boron nitride, crystalline silica, amorphous silica, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate Magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, crystalline silica, amorphous silica and the like are preferable. Moreover, it is more preferable to use a nanofiller for improving the hot fluidity of the film.

  As for the usage-amount of an inorganic filler, 1-40 mass parts is preferable with respect to 100 mass parts of resin compositions. If it is 1 part by mass or more, the effect of addition is obtained, and if it is 40 parts by mass or less, the storage elastic modulus of the resin composition does not increase excessively, which is preferable.

  In addition, various coupling agents can be added to the resin composition for forming a cladding layer of the present invention in order to improve interfacial bonding between different materials. Examples of the coupling agent include silane, titanium, and aluminum.

  The silane coupling agent is not particularly limited. For example, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-ureidopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane and the like can be used, and these can be used alone or in combination of two or more. Specifically, there are A-189 and A-1160 manufactured by Nippon Unicar Company.

  The amount of the coupling agent used is 100 mass parts of (meth) acrylic polymer having (A) a reactive functional group and a weight average molecular weight of 100,000 or more from the viewpoint of its effect, heat resistance and cost. On the other hand, it is preferable to set it as 0.01-10 mass parts.

  The amount of the ion scavenger used is 100 masses of (meth) acrylic polymer having (A) a reactive functional group and a weight average molecular weight of 100,000 or more from the viewpoint of the effect of addition, heat resistance, cost, and the like. 0.1-10 mass parts is preferable with respect to a part.

The resin composition for forming a cladding layer of the present invention is obtained by dissolving the components (A) to (E) in a solvent.
The solvent used here is not particularly limited as long as it can dissolve the resin composition. For example, aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, p-cymene; diethyl ether, tert-butyl Chain ethers such as methyl ether, cyclopentyl methyl ether and dibutyl ether; cyclic ethers such as tetrahydrofuran and 1,4-dioxane; alcohols such as methanol, ethanol, isopropanol, butanol, ethylene glycol and propylene glycol; acetone, methyl ethyl ketone and methyl isobutyl Ketones such as 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; Carbonates such as tylene carbonate and propylene carbonate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol dimethyl ether, Polyhydric alcohol alkyl ethers such as propylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether; ethylene glycol monomethyl ether Polyhydric alcohol alkyl ether acetates such as ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate; N, N -Amides such as dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, etc., or a mixed solvent thereof can be used. The resin concentration in the resin solution is usually preferably 30 to 80% by mass.

  The resin composition for forming a clad layer of the present invention is preferably used for at least one of a lower clad and an upper clad of an optical waveguide.

Below, the preparation method of the resin film for clad layer formation of this invention and the preparation method of an optical waveguide using the same are demonstrated.
The resin film for forming a clad layer of the present invention can be obtained by dissolving or dispersing the resin composition for forming a clad layer in a solvent to form a varnish, applying the solution on a support film, heating and removing the solvent.

That is, on a protective film (also referred to as a release sheet), a resin composition comprising the above components dissolved in an organic solvent or the like to be varnished is a knife coating method, roll coating method, spray coating method, gravure coating method. The clad layer is formed by coating and drying according to generally known methods such as bar coating and curtain coating. Then, the support base material is laminated | stacked and the resin film for clad layer formation which consists of a release sheet (protective film), a clad layer, and a support base material can be obtained.
Alternatively, the clad layer resin composition can be directly coated on the supporting substrate by the same method and dried to obtain a clad layer forming resin film. In this case, you may laminate | stack a protective film as needed.

  Examples of the protective film or supporting substrate used for the resin film for forming a clad layer of the present invention include plastic films such as polytetrafluoroethylene film, polyethylene film, polypropylene film, polymethylpentene film, polyester such as polyethylene terephthalate, and the like. Can be mentioned.

The solvent for forming the varnish is not particularly limited as long as it can dissolve the clad layer-forming resin composition of the present invention, and the same solvents as those described above can be used.
These organic solvents can be used alone or in combination of two or more. Moreover, it is preferable that the solid content density | concentration in a resin varnish is 10-80 mass% normally.

  For the production of the varnish when the inorganic filler is added, it is preferable to use a raking machine, a three-roll, a ball mill, a bead mill or the like in consideration of the dispersibility of the inorganic filler, or a combination thereof. You can also. Moreover, after mixing an inorganic filler and a low molecular weight raw material beforehand, the mixing time can also be shortened by mix | blending a high molecular weight raw material. Further, after the varnish is formed, the bubbles in the varnish can be removed by vacuum degassing or the like.

Regarding the thickness of the cladding layer, the thickness after drying is preferably in the range of 5 to 500 μm. When the thickness is 5 μm or more, a clad thickness necessary for light confinement can be secured, and when the thickness is 500 μm or less, it is easy to control the film thickness uniformly. From the above viewpoint, the thickness of the cladding layer is preferably in the range of 10 μm to 100 μm.
The thickness of the clad layer may be the same or different between the lower clad layer formed first and the upper clad layer for embedding the core pattern. The thickness of the layer is preferably larger than the thickness of the core layer.

  In addition, when manufacturing a resin film for forming a clad layer, the resin film for forming a clad layer is protected as necessary for the purpose of protecting the resin film for forming the clad layer or improving the winding property when manufacturing it into a roll. A film may be attached.

  Although there is no restriction | limiting in particular in the thickness of a support base material, 5-250 micrometers is preferable. If the thickness is less than 5 μm, the workability deteriorates, and if it is more than 250 μm, it is not economical, which is not preferable. From the above viewpoint, the thickness of the supporting base material is preferably 10 to 200 μm, and more preferably 15 to 150 μm.

  Next, the resin composition for forming a core part used in the present invention can be a resin composition that is designed such that the core layer has a higher refractive index than the clad layer and can form a core pattern with actinic rays. A photosensitive resin composition is preferred.

It does not specifically limit about the thickness of the resin film for core part formation, The thickness of the core layer after drying is normally adjusted so that it may be 10-100 micrometers.
When the thickness of the core layer is 10 μm or more, there is an advantage that the alignment tolerance can be increased in the coupling with the light emitting / receiving element or the optical fiber after the optical waveguide is formed, and when the thickness is 100 μm or less, the light receiving / emitting after the optical waveguide is formed. In coupling with an element or an optical fiber, there is an advantage that coupling efficiency is improved.
From the above viewpoint, the thickness of the film is preferably in the range of 30 to 70 μm.

The base material used in the manufacturing process of the core portion forming resin film is a support that supports the optical waveguide forming film, and the material thereof is not particularly limited, but the core portion forming resin film may be peeled later. From the viewpoint of being easy and having heat resistance and solvent resistance, polyesters such as polyethylene terephthalate, polypropylene, polyethylene and the like are preferable.
The thickness of the substrate is preferably 5 to 50 μm. When it is 5 μm or more, there is an advantage that the strength as a support is easily obtained, and when it is 50 μm or less, there is an advantage that a gap with the mask at the time of pattern formation becomes small and a finer pattern can be formed.
From the above viewpoint, the thickness of the base material is more preferably in the range of 10 to 40 μm, and particularly preferably 15 to 30 μm.

Moreover, it is preferable to use a highly transparent flexible base material in order to improve the transmittance of exposure light and reduce the side wall roughness of the core pattern.
The haze value of the highly transparent base material is preferably 5% or less, more preferably 3% or less, and particularly preferably 2% or less.
In addition, a haze value is measured based on JISK7105, for example, can be measured with commercially available turbidimeters, such as NDH-1001DP (made by Nippon Denshoku Industries Co., Ltd.).
Such a base material is available from Toyobo Co., Ltd. under the trade names “Cosmo Shine A1517” and “Cosmo Shine A4100”.
In addition, in order to make peeling of the resin film for core part formation easy later, the said base material may perform the mold release process, the antistatic process, etc.

In addition, when manufacturing the core part forming resin film, the core part forming resin film is protected as necessary for the purpose of protecting the core part forming resin film and improving the winding property when manufacturing in a roll shape. A film may be attached.
As the protective film, those similar to those exemplified as the support film for the clad layer-forming resin film can be used, and may be subjected to mold release treatment or antistatic treatment as necessary.

Hereinafter, a cured film obtained by curing the resin composition for forming a cladding layer of the present invention will be described.
The tensile elastic modulus at 25 ° C. of the cured film obtained by curing the resin composition for forming a cladding layer of the present invention is preferably 1 to 2000 MPa, more preferably 10 to 1500 MPa, and further preferably 20 to 1000 MPa. When the elastic modulus of the cured film is 2000 MPa or less, when the film is bent in the thickness direction, it can be bent with a small radius of curvature. On the other hand, when the pressure is 1 MPa or more, the cured film returns to its original shape without being stretched when a bending test or a twist test is performed, which is preferable. If this resin composition for forming a cladding layer is used in an optical waveguide, the film is absorbed by the upper and lower cladding layers even when a mechanical tensile force is applied, so the core deformation can be reduced and the transmission characteristics of the optical waveguide can be reduced. Can be prevented.

The tensile elongation at break in a tensile test at 25 ° C. of a cured film obtained by curing the resin composition for forming a cladding layer of the present invention is preferably 10 to 600%, more preferably 15 to 400%, and more preferably 20 -200% is more preferable. When the tensile break is 10% or more, it becomes brittle and does not break when bent. If it is 600% or less, the cured film does not easily stretch by the bending test and does not return to the original shape, which is preferable. The tensile elongation at break means the elongation at the time when the film is broken in the film tensile test.
If this cured resin film for forming a clad layer is used in an optical waveguide, even if a mechanical tensile force is applied, it is absorbed by the upper and lower clad layers, so that the deformation of the core can be reduced, and the transmission characteristics of the film optical waveguide Can be prevented.

  In a repeated bending test of a cured film obtained by curing the resin composition for forming a cladding layer of the present invention, after performing a bending test 100,000 times with a curvature radius of 1 to 5 mm, for example, 2 mm, It is preferable that no mechanical breakage occurs. More preferably, no mechanical breakage occurs after the bending test is performed 1 million times. If no mechanical breakage occurs in the cured film, the optical waveguide using this film as the cladding layer can perform stable optical transmission for a long period of time, and it should be applied to parts that are always movable, such as the hinge part of mobile phones. Can do. In order to reduce the size of the device, it is required that the optical waveguide does not break even at a smaller radius of curvature. From this viewpoint, it is more preferable that no mechanical breakage occurs when the radius of curvature is 0.5 mm. Mechanical breakage can be confirmed by magnifying glass, under a microscope, or by visual observation.

  In the repeated twist test of the cured film obtained by curing the resin composition for forming a clad layer of the present invention, it is preferable that no mechanical breakage occurs in the cured resin film for forming a clad layer after the 100,000 times twist test. More preferably, no mechanical breakage occurs after the 1,000,000 times twist test. If no mechanical breakage occurs in the cured film, the optical waveguide using this film as the cladding layer can perform stable light transmission for a long period of time. For example, it should be applied to a mobile part such as a hinge part of a mobile phone. Can do. Mechanical breakage can be confirmed by magnifying glass, under a microscope, or by visual observation.

  The total light transmittance of a cured film having a thickness of 110 μm obtained by curing the resin composition for forming a cladding layer of the present invention is preferably 50% or more. If the transmittance is 50% or more, the visibility of the core portion in the optical waveguide is good. For example, when the optical waveguide is processed by a dicing saw, the processing can be easily positioned. From the above viewpoint, the transmittance is more preferably 60% or more, and particularly preferably 70% or more. The upper limit of the total light transmittance is not particularly limited.

  It is preferable that the cured film having a thickness of 110 μm obtained by curing the resin composition for forming a cladding layer of the present invention has a haze (haze value) of 50% or less. If the haze is 50% or less, the visibility of the core portion in the optical waveguide is good. For example, when the outer shape of the optical waveguide is processed by a dicing saw, the processing is easily positioned. From the above viewpoint, the haze is more preferably 40% or less, and particularly preferably 30% or less.

  The cured film formed by curing the resin composition for forming a cladding layer of the present invention preferably has a refractive index change of ± 0.005 or less after three reflow tests at a maximum temperature of 265 ° C. are performed. If it exists in this range, since optical stability can be ensured, a lead free reflow process can be applied and the application range of a resin composition can be expanded. From the above viewpoint, the refractive index change is more preferably within ± 0.003, and further preferably within ± 0.001. Note that the reflow test at the maximum temperature of 265 ° C. means a lead-free solder reflow test performed under conditions in accordance with IPC / JEDEC J-STD-020B.

Hereinafter, a method for producing an optical waveguide using the clad-forming resin composition of the present invention will be described.
As the method, for example, the resin composition is applied onto a substrate using a method such as a spin coating method, a dipping method, a spray method, a curtain coating method, a silk screen method, or a roll coating method, and is heated or dried under reduced pressure. After the solvent is removed by drying, etc., the resin is cured by irradiation with actinic rays or heating. This resin layer constitutes the cladding layer.
Next, a resin composition having a higher refractive index than that of the previously formed optical waveguide layer is applied by the same application method, and this is used as the core layer.
Subsequently, actinic rays are irradiated through a negative or positive mask pattern, and after exposure, unexposed portions are removed by wet development, dry development, etc., and a core pattern is manufactured.
Here, if necessary, the optical waveguide pattern may be further cured by heating at about 60 to 250 ° C. or exposure at about 0.1 to 1000 mJ / cm ² .
Thereafter, the clad layer forming resin composition is applied and formed in the same manner to produce an optical waveguide.

Hereinafter, the manufacturing method for forming an optical waveguide using the resin film for clad layer formation of this invention is explained in full detail.
As the method, for example, in the case where a protective film is present, a method of laminating the lower clad film on the substrate by thermocompression after the protective film is peeled off can be mentioned.
Here, it is preferable to laminate | stack under reduced pressure from the viewpoint of adhesiveness and followable | trackability.
The heating temperature of the film is preferably 20 to 130 ° C., and the pressing pressure is preferably 0.1 to 1.0 MPa (about 1 to 10 kgf / cm ² ), but these conditions are particularly limited. There is no.
Next, the lower clad film is cured by light or heating, and a core film having a refractive index higher than that of the lower clad film is laminated by the same method.
After laminating in this way, actinic rays are irradiated in an image form through a negative or positive mask pattern.
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, those that effectively emit visible light, such as a photographic flood bulb and a solar lamp, can be used.

Next, the unexposed portion is removed and developed by wet development or the like to form a waveguide pattern.
In the case of wet development, development is performed by a known method such as spraying, rocking immersion, brushing, and scraping using a developer such as an organic solvent suitable for the composition of the film.
Examples of the organic solvent developer include N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, γ-butyrolactone, methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl Examples include ether.
These organic solvents preferably add water in the range of 1 to 20 parts by mass in order to prevent ignition.
Moreover, you may use together 2 or more types of image development methods as needed.
Examples of the development method include a dip method, a battle method, a spray method such as a high-pressure spray method, brushing, and scraping. The high-pressure spray method is most suitable for improving the resolution.
As processing after development, the optical waveguide pattern may be further cured and used by heating at about 60 to 250 ° C. or exposure at about 0.1 to 1000 mJ / cm ² as necessary.
Thereafter, the clad layer forming resin film is laminated by the same method to produce an optical waveguide.

Hereinafter, the manufacturing method for forming a flexible optical waveguide using the resin film for clad layer formation of this invention is explained in full detail.
First, as a first step, the clad layer forming resin of the first clad layer forming resin film composed of the clad layer forming resin and the support film is cured to form the lower clad layer 2 (FIG. 1A )reference).
When a protective film is provided on the opposite side of the support film of the resin film for forming the clad layer, the protective film is not peeled off, and after the resin film for forming the clad layer is cured by light or heating, the protective film is peeled off. Then, the cladding layer 1 is formed.
At this time, the clad layer forming resin is preferably formed on a support film that has been subjected to an adhesion treatment.
On the other hand, the protective film is preferably not subjected to adhesion treatment in order to facilitate peeling from the clad layer-forming resin film, and may be subjected to mold release treatment as necessary.

Next, as a second step, a core part-forming resin film is laminated on the clad layer, and the core layer is laminated (see FIG. 1B).
In the second step, a core layer having a higher refractive index than that of the cladding layer is laminated on the above-described cladding layer by bonding the resin film for forming a core part at room temperature or by thermocompression bonding. Here, it is preferable to laminate | stack under reduced pressure from the viewpoint of adhesiveness and followable | trackability. The heating temperature here is preferably 20 to 130 ° C., and the pressure is preferably about 0.1 to 1.0 MPa (1 to 10 kgf / cm ² ), but these conditions are particularly limited. There is no.
In addition, when the protective film is provided in the other side of the base material of the resin film for core part formation, after peeling this protective film, the resin film for core part formation is laminated.
At this time, it is preferable that the protective film and the base material are not subjected to an adhesive treatment in order to facilitate the peeling from the core portion forming resin film, and may be subjected to a mold release treatment as necessary.

Next, as a third step, the core layer is exposed and developed to form a core pattern of the optical waveguide (see FIG. 1C).
Specifically, actinic rays are irradiated in an image form through a negative mask pattern.
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, those that effectively emit visible light, such as a photographic flood bulb and a solar lamp, can be used.

Next, when the base material of the core part forming resin film remains, the base material is peeled off, and the unexposed part is removed and developed by wet development or the like to form a waveguide pattern (FIG. 1D )reference).
In the case of wet development, development is performed by a known method such as spraying, rocking dipping, brushing, scraping, or the like, using an organic solvent developer suitable for the composition of the film.
Examples of the organic solvent developer include N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, γ-butyrolactone, methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl Examples include ether and propylene glycol monomethyl ether acetate.
These organic solvents preferably add water in the range of 1 to 20 parts by mass in order to prevent ignition.
Moreover, you may use together 2 or more types of image development methods as needed.
Examples of the development method include a dip method, a battle method, a spray method such as a high-pressure spray method, brushing, and scraping. The high-pressure spray method is most suitable for improving the resolution.
As the treatment after development, the optical waveguide pattern may be further cured and used by performing heating at about 60 to 250 ° C. or exposure at about 0.1 to 1000 mJ / cm ² as necessary.

Thereafter, a fourth step of embedding the core pattern by laminating the second clad layer forming resin film, and curing the clad layer forming resin of the second clad layer forming resin film to form an upper clad layer. A fifth step is performed (see FIG. 1 (e)).
When the clad layer forming resin film is composed of a clad layer forming resin and a support film, the laminating is performed with the clad layer forming resin on the core pattern side.
At this time, the thickness of the clad layer is preferably larger than the thickness of the core layer as described above. Curing is performed by light or heat in the same manner as described above.
When a protective film is provided on the opposite side of the support film of the clad layer forming resin film, the protective film is peeled off, and then the clad layer forming resin film is cured by light or heating to form a clad layer. .
At this time, the clad layer forming resin is preferably formed on a support film that has been subjected to an adhesion treatment.
On the other hand, the protective film is preferably not subjected to adhesion treatment in order to facilitate peeling from the clad layer-forming resin film, and may be subjected to mold release treatment as necessary.
According to the manufacturing method using the above-described film, a thin film can be formed, and the manufacturing time of a multimode optical waveguide having a large core size, which has been a conventional problem, can be greatly shortened.
In the repeated bending test of the flexible optical waveguide of the present invention, it is preferable that no mechanical breakage occurs in the flexible optical waveguide after the bending test is performed 100,000 times with a curvature radius of 1 to 5 mm, for example, 2 mm. More preferably, no mechanical breakage occurs after the bending test is performed 1 million times. If mechanical breakage does not occur in the optical waveguide, stable optical transmission can be performed for a long period of time. For example, the optical waveguide can be applied to a part that is always movable, such as a hinge part of a mobile phone. In order to reduce the size of the device, it is required that the optical waveguide does not break even at a smaller radius of curvature. From this viewpoint, it is more preferable that no mechanical breakage occurs when the radius of curvature is 0.5 mm. Mechanical breakage can be confirmed by magnifying glass, under a microscope, or by visual observation.

The film optical waveguide of the present invention preferably has a cladding layer having a small tensile modulus of elasticity of 1 to 2000 MPa, so that the followability at the interface when the film optical waveguide bends or recovers its shape is improved. Can do.
In the repeated twist test of the flexible optical waveguide of the present invention, it is preferable that no mechanical breakage occurs in the flexible optical waveguide after the 100,000-time twist test. More preferably, no mechanical breakage occurs after the 1,000,000 times twist test. If mechanical breakage does not occur in the optical waveguide, stable optical transmission can be performed for a long period of time. For example, the optical waveguide can be applied to a part that is always movable, such as a hinge part of a mobile phone. Mechanical breakage can be confirmed by magnifying glass, under a microscope, or by visual observation.

In the optical waveguide of the present invention, the relative refractive index difference between the core portion and the cladding layer is preferably 1 to 10%. When it is 1% or more, the light propagating through the core portion at the time of bending does not leak into the cladding layer. If it is 10% or less, the propagation light does not spread too much at the connection portion such as the optical waveguide and the optical fiber, and the coupling loss does not increase. From the above viewpoint, it is more preferably 1.5 to 7.5%, and particularly preferably 2 to 5%. The relative refractive index difference was determined by the following formula.
Specific refractive index difference (%) = [(refractive index of core part) ² − (refractive index of clad layer) ² ] / [2 × (refractive index of core part) ² ] × 100

  In the optical waveguide of the present invention, the light propagation loss is preferably 0.3 dB / cm or less. If it is 0.3 dB / cm or less, the loss of light becomes small and the intensity of the transmission signal is sufficient. From the above viewpoint, it is more preferably 0.2 dB / cm or less.

The optical waveguide of the present invention is excellent in bending resistance, twist resistance, transparency, reliability, and heat resistance, and can also be used as an optical transmission line of an optical module. As the form of the optical module, for example, an optical waveguide with an optical fiber in which optical fibers are connected to both ends of the optical waveguide, an optical waveguide with a connector in which connectors are connected to both ends of the optical waveguide, and an optical waveguide and a printed wiring board are combined. Examples include an opto-electric composite substrate, an opto-electric conversion module that combines an optical waveguide, an optical / electric conversion element that 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 examples thereof include a rigid substrate such as a glass epoxy substrate and a ceramic substrate, a flexible substrate such as a polyimide substrate and a polyethylene terephthalate substrate.

The following examples of the present invention will be described more specifically, but the present invention is not limited to these examples.
Example 1
[Preparation of Clad Layer Forming Resin Varnish CLV-1]
(A) As a (meth) acrylic polymer, cyclohexanone solution of epoxy group-containing acrylic rubber (HTR-860P-3 manufactured by Nagase ChemteX Corporation, molecular weight 800,000, solid content 12% by mass) 833 parts by mass (solid content 100 parts by mass) ), (B) As an epoxy resin, bisphenol F type epoxy resin (YDF-8170C, Toto Kasei Co., Ltd., epoxy equivalent 158 g / eq) 16 parts by mass, o-cresol novolac type epoxy resin (YDCN-703, Toto Kasei Co., Ltd.) , Epoxy equivalent 209 g / eq) 5 parts by mass, (C) as a phenolic epoxy resin curing agent, a methyl ethyl ketone solution of bisphenol A novolak resin (LF-4871, manufactured by Dainippon Ink & Chemicals, Ltd., hydroxyl equivalent 118 g / eq, solid content) 60 parts by mass) 26 parts by mass (solid content 1 (Parts by mass), (D) 30 parts by mass of dipentaerythritol hexaacrylate (A-DPH manufactured by Shin-Nakamura Chemical Co., Ltd.) as a photoreactive monomer, and (E) 2-benzyl-2-dimethyl as a photobase generator. 2 parts by mass of amino-1- (4-morpholinophenyl) -butan-1-one (Irgacure 369 manufactured by Ciba Specialty Chemicals Co., Ltd.), γ-mercaptopropyltrimethoxysilane (Nihon Unicar Co., Ltd.) as a silane coupling agent A-189) 0.1 parts by mass and 0.3 part by mass of γ-ureidopropyltriethoxysilane (A-1160, manufactured by Nihon Unicar Co., Ltd.) were stirred and mixed, and then degassed under reduced pressure to form a cladding layer. Resin varnish CLV-1 was obtained.

[Preparation of Cladding Layer Forming Resin Film CLF-1]
Clad layer-forming resin varnish CLV-1 is coated on a release treatment surface of a surface release treatment PET film (A53, Teijin DuPont Films Co., Ltd., thickness 25 μm) (Multicoater TM-MC, manufactured by Hirano Techseed Co., Ltd.). And then dried at 100 ° C. for 20 minutes, and then a surface release treatment PET film (A31 manufactured by Teijin DuPont Films Ltd., thickness 25 μm) is pasted as a protective film to obtain a resin film CLF-1 for forming a clad layer It was. 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 after curing is 30 μm for the resin film for forming the lower cladding layer, and the upper cladding layer. The resin film for forming was adjusted to 80 μm, and the cured film for refractive index measurement was adjusted to 50 μm.

[Preparation of cured film for tensile test, bending endurance test, twist endurance test, and total light transmittance and haze measurement]
Using a roll laminator (HLM-1500 manufactured by Hitachi Chemical Technoplant Co., Ltd.), the lower clad layer forming resin film CLF-1 from which the protective film (A31) has been removed is used for forming the upper clad layer from which the protective film (A31) has been removed. On the resin film CLF-1, it laminated | stacked on the conditions of pressure 0.4MPa, temperature 80 degreeC, and speed 0.4m / min. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 250 mJ / cm ² using an ultraviolet exposure machine (MAP-1200-L manufactured by Dainippon Screen Co., Ltd.). After curing at 160 ° C. for 1 hour, the support film (A53) was removed to obtain a cured film having a thickness of 110 μm.

[Tensile test]
The obtained cured film (width 10 mm, length 70 mm) was subjected to a tensile test (distance between grips 50 mm) using a tensile tester (RTM-100 manufactured by Orientec Co., Ltd.) at a temperature of 25 ° C. and a tensile speed of 50 mm / min, in accordance with JIS K 7127.
(1) Tensile modulus The tensile modulus was calculated by the following equation using the first linear portion of the tensile stress-strain curve.
Tensile stress difference (N) ÷ original average cross-sectional area of the cured film (mm ²⁾ ÷ difference (2) Tensile elongation at break of the strain between the same two points between two points of the tensile modulus (MPa) = a straight line The elongation at break was calculated according to the following formula.
Tensile elongation at break (%) = (distance between grips at break (mm) −initial distance between grips (mm)) ÷ initial distance between grips (mm) × 100

[Bending durability test]
A bending durability test of the obtained cured film (width 5 mm, length 10 mm) was performed using a bending durability tester (manufactured by Daisho Electronics Co., Ltd.), a bending angle of 0 to 180 °, a bending radius of 2 mm, and a bending speed of 2 times / second. The bending durability test was performed under the conditions described above, and the presence or absence of breakage of the cured film was observed.
○: Not broken after 100,000 times ×: Broken after less than 100,000 times

[Twist durability test]
A twist endurance test of the obtained cured film (width 2 mm, length 40 mm) was performed using a bending endurance tester (manufactured by Daisho Electronics Co., Ltd.) with a twist angle of ± 180 °, a distance between grippers of 20 mm, and a twist rate of 0. A twisting durability test was performed under the condition of 5 times / second, and the presence or absence of breakage of the cured film was observed.
○: Not broken after 100,000 times ×: Broken after less than 100,000 times

[Measurement of total light transmittance and haze]
The total light transmittance and haze of the obtained cured film were measured using a color separation / turbidity measuring device (COH 400 manufactured by Nippon Denko Kogyo Co., Ltd.). Evaluation was made according to the following criteria.
(1) Total light transmittance ○: 50% or more ×: Less than 50% (2) Haze ○: 50% or less ×: More than 50%

[Preparation of resin varnish COV-1 for core formation]
As binder polymer, propylene glycol monomethyl ether acetate solution of phenoxy resin (YP-70 manufactured by Toto Kasei Co., Ltd., solid content 40% by mass) 63 parts by mass (solid content 25 parts by mass), and as the polymerizable compound, ethoxylated fluorene type di Propylene glycol monomethyl ether acetate solution of acrylate (Shin Nakamura Chemical Co., Ltd. A-BPEF / PGMAC70, solid content 70% by mass) 54 parts by mass (solid content 38 parts by mass), bisphenol A type epoxy acrylate (Shin Nakamura Chemical Co., Ltd.) EA-1020) 38 parts by mass, as radical photopolymerization initiator, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (Ciba Specialty Chemicals) Irgacure 29 9) 1 part by mass and 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Irgacure 819 manufactured by Ciba Specialty Chemicals Co., Ltd.) were stirred and mixed, and then degassed under reduced pressure to form a core part. Resin varnish COV-1 was obtained.

[Preparation of Core Part Forming Resin Film COF-1]
The core part-forming resin varnish COV-1 is applied and dried on the non-treated surface of a PET film (Toyobo Co., Ltd., A1517, thickness 16 μm) in the same manner as the clad layer-forming resin film. A resin film COF-1 was obtained. 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.

[Production of cured film for refractive index measurement]
(1) Clad Layer Forming Resin Film The clad layer forming resin film CLF-1 was irradiated with ultraviolet rays (wavelength 365 nm) at 250 mJ / cm ² using the ultraviolet exposure machine. After curing at 160 ° C. for 1 hour, the support film (A53) and the protective film (A31) were removed to obtain a cured film having a thickness of 50 μm.
(2) Core part-forming resin film The core part-forming resin film COF-1 was irradiated with 2000 mJ / cm ^{2 of} ultraviolet rays (wavelength 365 nm) using the ultraviolet exposure machine. The protective film (A31) was removed, and after heat treatment at 160 ° C. for 1 hour, the support film (A1517) was removed to obtain a cured film having a thickness of 50 μm.

[Measurement of refractive index]
The refractive index at a wavelength of 830 nm at a temperature of 25 ° C. of the obtained cured film was measured using a prism coupler (manufactured by SAIRON TECHNOLOGY, SPA-4000).

[Calculation of relative refractive index]
The refractive index at a wavelength of 830 nm at a temperature of 25 ° C. of the obtained cured film was measured using a prism coupler (manufactured by SAIRON TECHNOLOGY, SPA-4000).
The relative refractive index difference was calculated by the following formula.
Relative Refractive Index Difference (%) = [(Refractive Index of Resin Cured Film for Forming Core Part) ² − (Refractive Index of Resin Cured Film for Forming Clad Layer) ² ] ÷ [2 × (of Resin Cured Film for Forming Core Part Refractive index) ² ] × 100

[Fabrication of optical waveguide]
Using the ultraviolet exposure machine, the lower clad layer forming resin film CLF-1 was irradiated with ultraviolet rays (wavelength 365 nm) at 250 mJ / cm ² . After removing the protective film (A31), it was cured at 160 ° C. for 1 hour to form a lower cladding layer.

Subsequently, using the roll laminator, the core part-forming resin film COF-1 from which the protective film (A31) has been removed is placed on the lower cladding layer at a pressure of 0.4 MPa, a temperature of 80 ° C., and a speed of 0.4 m / min. It laminated | stacked on conditions. Furthermore, using a vacuum pressurization type laminator (MVLP-500 / 600 manufactured by Meiki Seisakusho Co., Ltd.), pressure bonding was performed under the conditions of a pressure of 0.4 MPa, a temperature of 80 ° C., and a pressurization time of 30 seconds.
Next, the film was irradiated with ultraviolet rays (wavelength 365 nm) of 500 mJ / cm ² through the negative photomask having a width of 50 μm with the above-described ultraviolet exposure machine, and then heated after exposure at 80 ° C. for 5 minutes. The support film (A1517) was removed, and the core was developed using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 70/30 mass ratio), and then propylene glycol monomethyl ether and then isopropanol were used. Washed and dried by heating at 100 ° C. for 1 hour.

Next, the upper cladding layer-forming resin film CLF-1 from which the protective film (A31) has been removed using the vacuum pressurizing laminator is applied on the core and the lower cladding layer at a pressure of 0.4 MPa, a temperature of 80 ° C. Lamination was performed under a pressure time of 30 seconds. Ultraviolet light (wavelength 365 nm) was irradiated at 250 mJ / cm ² to remove the support film (A53) of the resin film CLF-1 for forming the lower cladding layer, and then cured at 160 ° C. for 1 hour to form an upper cladding layer. Subsequently, the support film (A53) of the upper clad layer-forming resin film CLF-1 was removed to obtain an optical waveguide. Thereafter, an optical waveguide having a waveguide length of 10 cm was cut out using a dicing saw (DAD-341 manufactured by DISCO Corporation).

Examples 2 to 6 and Comparative Example 1
Clad layer-forming resin varnishes CLV-2 to 7 were prepared according to the compounding ratios shown in Table 1, and clad layer-forming resin films CLF-2 to 7 were produced in the same manner as in Example 1. Table 1 shows the results of ultraviolet irradiation during film curing, as well as tensile test, bending durability test, and twisting durability test, and total light transmittance and haze measurement of the cured film.
Then, the optical waveguide was produced by the method similar to Example 1 using these resin films for optical waveguide formation. Table 2 shows the combination of the core portion forming resin film and the clad layer forming resin film used for the production of the optical waveguide, the results of measuring the refractive index of each cured film, and the relative refractive index difference.

* 1: Cyclohexanone solution of epoxy group-containing acrylic rubber (manufactured by Nagase ChemteX Corporation, weight average molecular weight 800,000)
* 2: Propylene glycol monomethyl ether acetate solution of phenoxy resin (manufactured by Toto Kasei Co., Ltd.)
* 3: Bisphenol F type epoxy resin (manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 158 g / eq)
* 4: Bisphenol A type epoxy resin (manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 172 g / eq)
* 5: o-cresol novolac type epoxy resin (manufactured by Toto Kasei Co., Ltd., epoxy equivalent 209 g / eq)
* 6: Methyl ethyl ketone solution of bisphenol A novolak resin (Dainippon Ink Chemical Co., Ltd., hydroxyl equivalent: 118 g / eq)
* 7: Dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)
* 8: Trimethylolpropane triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)
* 9: 2-Benzyl-2-dimethylamino-1- (4-morpholinylphenyl) -butan-1-one (manufactured by Ciba Specialty Chemicals)
* 10: 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholinylphenyl) -butan-1-one (manufactured by Ciba Specialty Chemicals)
* 11: 1,2-methyl-1- [4- (methylthio) phenyl] -2-morpholinylpropan-1-one (manufactured by Ciba Specialty Chemicals)
* 12: γ-Mercaptopropyltrimethoxysilane (manufactured by Nippon Unicar Co., Ltd.)
* 13: γ-Ureidopropyltriethoxysilane (Nihon Unicar Co., Ltd.)
* 14: ○… No break after 100,000 times, ×… Break after less than 100,000 times * 15: ○… No break after 100,000 times, ×… Break less than 100,000 times * 16: ○… 50 % Measured under the conditions of less than 50% and a film thickness of 110 μm * 17: ○ Measured under the condition of 50% or less, x ... greater than 50% and a film thickness of 110 μm

[Measurement of optical propagation loss]
The optical propagation loss of the optical waveguides (waveguide length 10 cm) obtained in Examples 1 to 6 and Comparative Example 1 is the VCSEL (FLS-300-01-VCL manufactured by EXFO) with the light source having a wavelength of 850 nm as the central wavelength. ), A light receiving sensor (Q82214 manufactured by Advantest Corporation), an incident fiber (GI-50 / 125 multimode fiber, NA = 0.20) and an outgoing fiber (SI-114 / 125, NA = 0.22), It was measured by the cutback method (measurement waveguide lengths 10, 5, 3, 2 cm).
○: 0.3 dB / cm or less ×: larger than 0.3 dB / cm

Further, the bending durability test and the twisting durability test of the obtained optical waveguide (width 5 mm, length 10 mm) were performed under the same conditions as described above.
○: No fracture after 100,000 times ×: Less than 100,000 times The results are shown in Table 3.

* 1: ○ ... 0.3 dB / cm or less, x ... greater than 0.3 dB / cm * 2: ○ ... no breakage after 100,000 times, x ... breakage less than 100,000 times

  From Table 1, the cured film of the resin composition for forming a clad layer of the present invention is excellent in bending resistance and twisting resistance, and an optical waveguide manufactured using these is also excellent in bending resistance and twisting resistance. I understand. On the other hand, it can be seen that a cured film of a resin composition for forming a cladding layer that does not belong to the present invention and an optical waveguide produced using the resin composition are inferior in bending resistance and twisting resistance.

  The cured resin film for forming a cladding layer of the present invention and an optical waveguide using the same have excellent bending resistance and twisting resistance due to the above configuration. Therefore, it can be applied to a wide range of fields such as optical interconnection.

Cross-sectional schematic diagram showing an example of optical waveguide manufacturing process

Explanation of symbols

1, 8; Support film (for clad layer)
2; lower clad layer 3; core layer 4; support film (for core portion formation)
5; Photomask 6; Core pattern 7; Upper cladding layer

Claims (17)

  (A) a (meth) acrylic polymer having a reactive functional group and a weight average molecular weight of 100,000 or more, (B) an epoxy resin, (C) a phenolic epoxy resin curing agent, (D) a photoreactive monomer And (E) a resin composition for forming a cladding layer of an optical waveguide containing a photobase generator.   (D) The resin composition for forming a clad layer according to claim 1, wherein the photoreactive monomer is (meth) acrylate.   (A) An epoxy group-containing (meth) acryl having a reactive functional group and having a weight average molecular weight of 100,000 or more and containing 0.5 to 6% by mass of an epoxy group-containing repeating unit. The resin composition for forming a clad layer according to claim 1, which is a polymer.   (B) The resin composition for clad layer formation in any one of Claims 1-3 in which an epoxy resin contains a bisphenol type epoxy resin and / or a phenol novolak type epoxy resin.   The resin for forming a clad layer according to any one of claims 1 to 4, wherein the (C) phenolic epoxy resin curing agent contains at least one of a phenol novolak resin, a bisphenol A novolak resin, and an o-cresol novolak type epoxy resin. Composition.   (B) 5 to 250 parts by mass of epoxy resin and (D) light with respect to 100 parts by mass of (A) reactive functional group and 100 parts by mass of (meth) acrylic polymer having a weight average molecular weight of 100,000 or more. 5-100 parts by mass of reactive monomer and 0.1-20 parts by mass of (E) photobase generator, (C) phenolic epoxy resin curing agent, phenolic per epoxy group of epoxy resin The resin composition for forming a clad layer according to any one of claims 1 to 5, which is contained so that an equivalent ratio of hydroxyl groups is in a range of 0.5 to 1.5.   The resin composition for forming a clad layer according to any one of claims 1 to 6, wherein a cured film obtained by curing the resin composition for forming a clad layer has a tensile elastic modulus at 25 ° C of 1 to 2000 MPa.   The resin composition for forming a clad layer according to any one of claims 1 to 7, wherein a cured film obtained by curing the resin composition for forming a clad layer has a tensile elongation at break at 10C of 10 to 600%. .   The resin for forming a clad layer according to any one of claims 1 to 8, wherein the cured film formed by curing the resin composition for forming a clad layer is not broken after performing a bending durability test with a bending radius of 2 mm 100,000 times. Composition.   The resin composition for forming a clad layer according to any one of claims 1 to 9, wherein the cured film formed by curing the resin composition for forming a clad layer has no break after performing a twisting durability test 100,000 times.   The resin film for clad layer formation using the resin composition for clad layer formation in any one of Claims 1-10.   An optical waveguide in which at least one of a lower clad layer and an upper clad layer is formed from the clad layer forming resin composition according to claim 1.   An optical waveguide in which at least one of a lower clad layer and an upper clad layer is formed by the clad layer forming resin film according to claim 11.   Between the lower clad layer and the upper clad layer of the optical waveguide, a core part is formed of a photosensitive resin composition having a higher refractive index than both clad layers, and the relative refractive index difference between the core part and the clad layer is 1 to The optical waveguide according to claim 12 or 13, which is 10%.   The optical waveguide according to claim 13 or 14, wherein at least one of the clad layer forming resin films comprises a clad layer forming resin and a support film, and the support film is disposed outside the clad layer with respect to the core layer.   The optical waveguide according to claim 15, wherein the resin film for forming a cladding layer is formed by forming a resin composition for forming a cladding layer on a support film subjected to an adhesion treatment.   An optical module using the optical waveguide according to claim 12.

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