JP2008192527A - Light guide body and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide body using a wave guide of a type of taking out light to a front side from a side directly and reconciling improvement of efficiency of utilizing light and productivity by integration or reduction of members, by realizing thinning by forming a curvature by making a large difference between refractive indices of a core and a clad, and to provide a method for manufacturing the same. <P>SOLUTION: The light guide body guides light by a light wave guide formed with core portions formed from a polymer material and a clad portion formed from a material having a lower refractive index than that of the core portions, and the clad portion consists of foam including fine closed pores having an average pore diameter of 5 to 200 nm and a volume porosity of the foam portion is 1 to 95%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a light guide that is used in an illumination device, a display device, and the like and guides incident light from a light source in one direction as emitted light by changing the light in another direction.
In particular, the present invention provides a light guide excellent in conversion efficiency of light from a light source, and a method for manufacturing the same.

The light guide is made of a translucent molded article, and a light output pattern that causes a change in refractive index is provided on the surface or inside thereof. As a method for obtaining the light emission pattern, (1) a method of printing white dots on the surface, (2) a method of forming grooves and dots on the surface, and (3) a method of dispersing light scatterers inside are used. It has been.
The light-scattering light guide using the method (3) is a light guide of a type in which incident light is scattered by an inherent light scatterer and guided to the light exit surface. Since there is no pattern processing on the surface of the light guide, a light diffusing sheet becomes unnecessary compared with a printed light guide using the method (1) and a molded light guide using the method (2). There is merit that can be made. In addition, there is an advantage that the light guide can be reduced in weight by using a light scatterer having a small specific gravity. Examples of the light scatterer include light scattering particles such as styrene fine particles described in Patent Document 1, silicon beads described in Patent Document 2, methacrylic fine particles described in Patent Document 3, and hollow beads described in Patent Document 4. For example, bubbles made of carbon dioxide described in Patent Document 5 are used.
In order to further increase the efficiency, a light guide that applies the principle of an optical waveguide has also been proposed. An illumination device described in Patent Document 6 that condenses light passing through an optical fiber or an optical waveguide by a microlens array, a display element described in Patent Document 7 that uses a waveguide as a means for condensing light from a backlight, There are a planar light-emitting device described in Patent Document 8 that extracts light entering through a waveguide by scattering in the middle, a backlight described in Patent Document 9 that extracts light that has passed through the waveguide by an outcoupling member, and the like.
Japanese Patent Laid-Open No. 06-324215 JP-A-10-183532 JP-A-11-19928 JP 9-17221 A JP 11-291374 A Japanese Patent Laid-Open No. 06-222326 JP 2002-333619 A JP 2006-134720 A JP-T-2006-520076

The light guide is mainly built in an edge light type surface emitting device. This edge light type surface light emitting device is used in general lighting equipment and display devices.
For example, in a liquid crystal display device, since the liquid crystal itself of the display element does not emit light, a display function is exhibited in combination with a surface light emitting device called an edge light type backlight or a front light. With the diversification of applications such as liquid crystal display devices, the quality items required for the light guide are becoming stricter.
In particular, space-saving and portability of display devices are emphasized, and LEDs used as light sources are downsized, so that light guides are strongly reduced in thickness and weight. Since the light guide occupies more than half of the thickness of the surface light emitting device, it contributes greatly to thinning. In addition, in order to improve display quality and save power, it is also required to improve light utilization efficiency.
However, in the case of a light guide in which light scatterers are simply uniformly dispersed, the entire light guide needs to be formed into a wedge shape as described above. Specifically, it will be molded by injection molding, but the thinner the mold, the worse the filling rate and transfer accuracy to the mold (due to the limit of resin fluidity). It was difficult.
In addition, in the backlight using the conventional optical waveguide, the type in which light is partially extracted from the waveguide is low in efficiency, and the type in which the optical path is bent from the efficient direct side to the front is the core and cladding. Since there is no difference in refractive index between the two, it is difficult to bend abruptly, and there is a drawback in that the backlight becomes thick due to the necessity of taking a large curvature.
In view of the above circumstances, the present invention provides a light guide that applies a waveguide that directly takes out light from the side to the front, and reduces the curvature by increasing the difference in refractive index between the core and the cladding. It is an object of the present invention to provide a light guide body that realizes a reduction in thickness and achieves both improvement in light utilization efficiency and productivity improvement through integration and member saving, and a manufacturing method thereof.

In order to solve the above problems, the present invention employs the following configurations (1) to (6).
(1) A light guide that is formed of a polymer material and guides light through an optical waveguide formed by a core portion and a cladding portion made of a material having a refractive index lower than that of the core portion. A light guide comprising a foam containing fine closed cells having a bubble diameter of 5 to 200 nm, and having a volume porosity of 1 to 95%.
(2) Contains an acid generator that generates an acid by the action of active energy rays or a base generator that generates a base, and further decomposes and desorbs one or more low-boiling volatile substances by reacting with the acid or base. A foamable composition containing a compound having a decomposable foamable functional group is obtained by irradiating an active energy ray at a position where a clad portion is to be formed and foaming the conductive composition. Light body.
(3) A sheet-like or plate-like light guide in which two or more sheets are laminated, and the optical waveguide is formed across two or more sheets by connecting the core portions of adjacent layers. The light guide according to (1) or (2), wherein
(4) The method for producing a light guide according to (2) or (3), wherein the foam part forms the fine closed cells by irradiating an active energy ray and performing a heat treatment.
(5) The method for producing a light guide according to (4), characterized in that, in the formation process of the foam part, the process includes foaming by controlling the pressure in a temperature region where the low boiling point volatile substance decomposes and desorbs. .
(6) The process of forming the foam part includes a step of cooling while controlling the pressure after the step of foaming by controlling the pressure in a temperature range where the low boiling point volatile substance decomposes and desorbs (4) Or the manufacturing method of the light guide as described in (5).

As described above, in the present invention, a substance that generates an acid and a base by active energy rays is formed on a part of a low refractive index material that includes an optical waveguide in a light guide and forms a cladding portion of the optical waveguide. Using a foam having closed cells containing a compound that decomposes and desorbs low-boiling volatiles by reacting with an acid or base, the average cell diameter is 5 to 200 nm, and the porosity of the foamed part is 1 to 95%. is there. The curvature radius of the optical waveguide can be dramatically reduced by generating fine bubbles by irradiating the foamed part with electron beam irradiation or ultraviolet rays and then heating.
According to this method, a complicated waveguide pattern can be formed inside the light guide plate, and the light guide plate can be thinned. Further, since it can be manufactured by a simple method of exposing and heating a waveguide pattern with an electron beam or ultraviolet rays, it is advantageous in terms of cost as compared with the conventional manufacturing method.

The configuration of the present invention will be described in detail below.
The planar light emitting device according to the present invention can be a material used when manufacturing a planar image display device used in a system using light, such as a liquid crystal display, or a component of an optical component. It refers to a planar light emitting device as a basic part. The optical waveguide included in the light guide constituting the obtained planar light emitting device has a refractive index higher than that of the peripheral portion of the core portion, and the light that performs various functions on the light guide. It can also be used for parts (eg, sign panels, general lighting devices). Therefore, the planar light emitting device according to the present invention includes one that can be used alone as an optical component. Such a light guide can be used alone, but it may be used as a part of an optical component and is not particularly limited.

  The optical waveguide inherent in the light guide is a line itself for confining and transmitting light within a certain region, or processing a portion having a high refractive index into a linear shape on a light-transmitting substrate having a low refractive index. The above-mentioned optical line is formed on a substrate, and refers to an element that changes the direction of light propagating.

  Below, the foamable composition used as the raw material of the foam used for the light guide which comprises this invention first is demonstrated. The foamable composition is a composition that develops foamability when irradiated with active energy rays and subjected to heat treatment. The foamable composition is desirably a composition in which at least the following two components coexist. One is an acid generator that generates an acid by the action of active energy rays, or a base generator that generates a base, and the other is one or more types that react with the generated acid or base. It is a decomposition foamable compound that decomposes and desorbs a low boiling point volatile compound.

<Acid generator and base generator>
Examples of the acid generator or base generator used in the foamable composition used in the present invention include a chemically amplified photoresist and a photoacid generator or a photobase generator generally used for photocationic polymerization. What is called can be used.
As a photoacid generator suitable for the present invention,
(1) Diazonium salt compounds (2) Ammonium salt compounds (3) Iodonium salt compounds (4) Sulfonium salt compounds (5) Oxonium salt compounds (6) Phosphonium salt compounds Mention may be made of PF _6- , AsF _6- , SbF ₆ -and CF ₃ SO ₃ -salts of aliphatic onium compounds. Although the specific example is enumerated below, it is not limited to what was illustrated.

Bis (phenylsulfonyl) diazomethane,
Bis (cyclohexylsulfonyl) diazomethane,
Bis (tert-butylsulfonyl) diazomethane,
Bis (p-methylphenylsulfonyl) diazomethane,
Bis (4-chlorophenylsulfonyl) diazomethane,
Bis (p-tolylsulfonyl) diazomethane,
Bis (4-tert-butylphenylsulfonyl) diazomethane,
Bis (2,4-xylylsulfonyl) diazomethane,
Bis (cyclohexylsulfonyl) diazomethane,
Benzoylphenylsulfonyldiazomethane,
Trifluoromethanesulfonate,
Trimethylsulfonium trifluoromethanesulfonate,
Triphenylsulfonium trifluoromethanesulfonate,
Triphenylsulfonium hexafluoroantimonate,
2,4,6-trimethylphenyldiphenylsulfonium trifluoromethanesulfonate, p-tolyldiphenylsulfonium trifluoromethanesulfonate,
4-phenylthiophenyldiphenylsulfonium hexafluorophosphate,
4-phenylthiophenyldiphenylsulfonium hexafluoroantimonate,
1- (2-naphthoylmethyl) thiolanium hexafluoroantimonate,
1- (2-naphthoylmethyl) thiolanium trifluoromethanesulfonate,
4-hydroxy-1-naphthyldimethylsulfonium hexafluoroantimonate,
4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate,
(2-oxo-1-cyclohexyl) (cyclohexyl) methylsulfonium trifluoromethanesulfonate,
(2-oxo-1-cyclohexyl) (2-norbornyl) methylsulfonium trifluoromethanesulfonate,
Diphenyl-4-methylphenylsulfonium perfluoromethanesulfonate,
Diphenyl-4-tert-butylphenylsulfonium perfluorooctanesulfonate,
Diphenyl-4-methoxyphenylsulfonium perfluorobutanesulfonate,
Diphenyl-4-methylphenylsulfonium tosylate,
Diphenyl-4-methoxyphenylsulfonium tosylate,
Diphenyl-4-isopropylphenylsulfonium tosylate diphenyliodonium,
Diphenyliodonium tosylate,
Diphenyliodonium chloride,
Diphenyliodonium hexafluoroarsenate,
Diphenyliodonium hexafluorophosphate,
Diphenyliodonium nitrate,
Diphenyliodonium perchlorate,
Diphenyliodonium trifluoromethanesulfonate,
Bis (methylphenyl) iodonium trifluoromethanesulfonate,
Bis (methylphenyl) iodonium tetrafluoroborate,
Bis (methylphenyl) iodonium hexafluorophosphate,
Bis (methylphenyl) iodonium hexafluoroantimonate,
Bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate,
Bis (4-tert-butylphenyl) iodonium hexafluorophosphate,
Bis (4-tert-butylphenyl) iodonium hexafluoroantimonate,
Bis (4-tert-butylphenyl) iodonium perfluorobutanesulfonate,
2-methyl-4,6-bis (trichloromethyl) -1,3,5-triazine,
2,4,6-tri (trichloromethyl) -1,3,5-triazine,
2-phenyl-4,6-ditrichloromethyl-1,3,5-triazine,
2- (p-methoxyphenyl) -4,6-ditrichloromethyl-1,3,5-triazine,
2-naphthyl-4,6-ditrichloromethyl-1,3,5-triazine,
2-biphenyl-4,6-ditrichloromethyl-1,3,5-triazine,
2- (4′-hydroxy-4-biphenyl) -4,6-ditrichloromethyl-1,3,5-triazine,
2- (4′-methyl-4-biphenyl) -4,6-ditrichloromethyl-1,3,5-triazine,
2- (p-methoxyphenylvinyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-chlorophenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-methoxyphenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-methoxy-1-naphthyl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (benzo [d] [1,3] dioxolan-5-yl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-methoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (3,4,5-trimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (3,4-dimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (2,4-dimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (2-methoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-butoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2- (4-pentyloxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine,
2,6-di-tert-butyl-4-methylpyrylium trifluoromethanesulfonate,
Trimethyloxynium tetrafluoroborate,
Triethyloxynium tetrafluoroborate,
N-hydroxyphthalimide trifluoromethanesulfonate,
N-hydroxynaphthalimide trifluoromethanesulfonate,
(Α-benzoylbenzyl) p-toluenesulfonate,
(Β-benzoyl-β-hydroxyphenethyl) p-toluenesulfonate,
1,2,3-benzenetriyltrismethanesulfonate,
(2,6-dinitrobenzyl) p-toluenesulfonate,
(2-nitrobenzyl) p-toluenesulfonate,
(4-nitrobenzyl) p-toluenesulfonate,
Etc. Of these, iodonium salt compounds and sulfonium salt compounds are preferred.
In addition to the onium compounds, sulfonates that generate sulfonic acid upon irradiation with active energy rays, such as 2-phenylsulfonylacetophenone, halides that generate hydrogen halide upon irradiation with active energy rays, such as phenyltribromo. Methylsulfone and 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane, and ferrocenium compounds that generate phosphoric acid upon irradiation with active energy rays, such as bis (cyclopentadienyl) ferrocenium hexa Fluorophosphate, bis (benzyl) ferrocenium hexafluorophosphate, and the like can be used.
Furthermore, the following imide compound derivatives having acid generating ability can also be used.
N- (phenylsulfonyloxy) succinimide,
N- (trifluoromethylsulfonyloxy) succinimide,
N- (10-camphorsulfonyloxy) succinimide,
N- (trifluoromethylsulfonyloxy) phthalimide,
N- (trifluoromethylsulfonyloxy) -5-norbornene-2,3-dicarboximide,
N- (trifluoromethylsulfonyloxy) naphthalimide,
N- (10-camphorsulfonyloxy) naphthalimide.

As a photobase generator suitable for the present invention,
(1) Oxime ester compounds (2) Ammonium compounds (3) Benzoin compounds (4) Dimethoxybenzylurethane compounds (5) Orthonitrobenzylurethane compounds As an amine. In addition, a base generator that generates ammonia or hydroxy ions by the action of light may be used. These include, for example, N- (2-nitropentyloxycarbonyl) piperidine, 1,3-bis [N- (2-nitrobenzyloxycarbonyl) -4-piperidyl] propane, N, N′-bis (2-nitrobenzyl). It can be selected from oxycarbonyl) dihexylamine, O-benzylcarbonyl-N- (1-phenylethylidene) hydroxylamine, and the like. Further, a compound that generates a base by heating may be used in combination with the photobase generator.
In addition, a photosensitizer may be used in combination as appropriate in order to shift or expand the wavelength region of the active energy ray of the photoacid generator or photobase generator. For example, examples of photosensitizers for onium salt compounds include acridine yellow, benzoflavin, and acridine orange.

  As a method of minimizing the amount of acid generator or base generator added and the light irradiation energy while generating the necessary acid or base, an acid proliferator or base proliferator is used together with the acid generator or base generator. be able to. The acid proliferator is thermodynamically stable at around room temperature, but decomposes with acid and generates a strong acid by itself to greatly accelerate the acid-catalyzed reaction. By utilizing this reaction, it is possible to improve the generation efficiency of acid or base, and to control the foam generation rate and the foam structure.

<Decomposable foamable compound>
A decomposable foamable compound (hereinafter abbreviated as a decomposable compound) used in the foamable composition used in the present invention reacts with an acid or a base to produce one or more low-boiling volatile substances (low-boiling volatile compounds). Decomposes and desorbs. That is, this decomposable compound must be previously introduced with a degradable functional group capable of generating a low boiling point volatile substance. The low boiling point is the upper limit of the temperature at which gasification occurs during foaming. Usually, it is preferably 100 ° C. or lower and room temperature or lower. Examples of the low boiling point volatile substance include isobutene (boiling point: −7 ° C.), carbon dioxide (boiling point: −79 ° C.), nitrogen (boiling point: −196 ° C.), and the like. Examples of the decomposable functional group include tert-butyl group, tert-butyloxycarbonyl group, keto acid and keto ester group as those that react with acid, and urethane group and carbonate group as those that react with base. Can be mentioned. Reacting with acid includes tert-butyl group, tert-butyloxycarbonyl group, and acid, tert-butyl group is isobutene gas, tert-butyloxycarbonyl group is isobutene gas and carbon dioxide, keto Acid sites generate carbon dioxide and ketoesters such as the tert-butyl keto acid group generate carbon dioxide and isobutene. As those that react with the base, urethane groups and carbonate groups generate carbon dioxide gas. In this way, each gas is released from the decomposable compound.

The form of an acid-decomposable compound that decomposes by reacting with an acid or a base-decomposable compound that decomposes by reacting with a base can be used as a monomer, oligomer, polymer compound (polymer), etc. It can be classified into such compound groups.
(1) Non-curing low molecular weight decomposable compound group (2) Curing monomer based degradable compound group (3) Polymerizable degradable compound group Examples represented by curable monomer based degradable compounds In the case of an active energy ray-curable compound containing a vinyl group that causes a polymerization reaction when irradiated with active energy rays, it is easy to form uniform fine bubbles, and a foam having excellent strength is obtained. It is possible to obtain. Although the specific example of a decomposable compound is enumerated below, it is not limited to what was illustrated.

(1) -a, non-curing low molecular weight decomposable compound group <acid decomposable compound>
1-tert-butoxy-2-ethoxyethane,
2- (tert-butoxycarbonyloxy) naphthalene,
N- (tert-butoxycarbonyloxy) phthalimide,
2,2-bis [p- (tert-butoxycarbonyloxy) phenyl] propane, etc.

(1) -b, non-curing low molecular weight decomposable compound group <base decomposable compound>
N- (9-fluorenylmethoxycarbonyl) piperidine and the like (2) -a, a curable monomer-based decomposable compound group <acid-decomposable compound>
tert-butyl acrylate,
tert-butyl methacrylate,
tert-butoxycarbonylmethyl acrylate,
2- (tert-butoxycarbonyl) ethyl acrylate,
p- (tert-butoxycarbonyl) phenyl acrylate,
p- (tert-butoxycarbonylethyl) phenyl acrylate,
1- (tert-butoxycarbonylmethyl) cyclohexyl acrylate,
4-tert-butoxycarbonyl-8-vinylcarbonyloxy-tricyclo [5.2.1.02,6] decane,
2- (tert-butoxycarbonyloxy) ethyl acrylate,
p- (tert-butoxycarbonyloxy) phenyl acrylate,
p- (tert-butoxycarbonyloxy) benzyl acrylate,
2- (tert-butoxycarbonylamino) ethyl acrylate,
6- (tert-butoxycarbonylamino) hexyl acrylate,
p- (tert-butoxycarbonylamino) phenyl acrylate,
p- (tert-butoxycarbonylamino) benzyl acrylate,
p- (tert-butoxycarbonylaminomethyl) benzyl acrylate,
(2-tert-butoxyethyl) acrylate,
(3-tert-butoxypropyl) acrylate,
(1-tert-butyldioxy-1-methyl) ethyl acrylate,
3,3-bis (tert-butyloxycarbonyl) propyl acrylate,
4,4-bis (tert-butyloxycarbonyl) butyl acrylate,
p- (tert-butoxy) styrene,
m- (tert-butoxy) styrene,
p- (tert-butoxycarbonyloxy) styrene,
m- (tert-butoxycarbonyloxy) styrene,
Acryloyl acetate, methacryloyl acetate tert-butyl acryloyl acetate,
N- (tert-butoxycarbonyloxy) maleimide such as tert-butylmethacloyl acetate

(2) -b, curable monomer group decomposable compound group <base decomposable compound>
4-[(1,1-dimethyl-2-cyano) ethoxycarbonyloxy] styrene,
4-[(1,1-dimethyl-2-phenylsulfonyl) ethoxycarbonyloxy] styrene,
4-[(1,1-dimethyl-2-methoxycarbonyl) ethoxycarbonyloxy] styrene,
4- (2-cyanoethoxycarbonyloxy) styrene,
(1,1-dimethyl-2-phenylsulfonyl) ethyl methacrylate,
(1,1-dimethyl-2-cyano) ethyl methacrylate, etc.

(3) -a, decomposable compound group of polymer system <acid-decomposable compound>
Poly (tert-butyl acrylate),
Poly (tert-butyl methacrylate),
Poly (tert-butoxycarbonylmethyl acrylate),
Poly [2- (tert-butoxycarbonyl) ethyl acrylate],
Poly [p- (tert-butoxycarbonyl) phenyl acrylate],
Poly [p- (tert-butoxycarbonylethyl) phenyl acrylate],
Poly [1- (tert-butoxycarbonylmethyl) cyclohexyl acrylate],
Poly {4-tert-butoxycarbonyl-8-vinylcarbonyloxy-tricyclo [5.2.1.02,6] decane},
Poly [2- (tert-butoxycarbonyloxy) ethyl acrylate],
Poly [p- (tert-butoxycarbonyloxy) phenyl acrylate],
Poly [p- (tert-butoxycarbonyloxy) benzyl acrylate],
Poly [2- (tert-butoxycarbonylamino) ethyl acrylate],
Poly [6- (tert-butoxycarbonylamino) hexyl acrylate],
Poly [p- (tert-butoxycarbonylamino) phenyl acrylate],
Poly [p- (tert-butoxycarbonylamino) benzyl acrylate],
Poly [p- (tert-butoxycarbonylaminomethyl) benzyl acrylate],
Poly (2-tert-butoxyethyl acrylate),
Poly (3-tert-butoxypropyl acrylate),
Poly [(1-tert-butyldioxy-1-methyl) ethyl acrylate],
Poly [3,3-bis (tert-butyloxycarbonyl) propyl acrylate],
Poly [4,4-bis (tert-butyloxycarbonyl) butyl acrylate],
Poly [p- (tert-butoxy) styrene],
Poly [m- (tert-butoxy) styrene],
Poly [p- (tert-butoxycarbonyloxy) styrene],
Poly [m- (tert-butoxycarbonyloxy) styrene],
Polyacryloyl acetic acid, polymethacryloyl acetic acid,
Poly [tert-butyl acroyl acetate],
Poly [tert-butyl methacryloyl acetate]
N- (tert-butoxycarbonyloxy) maleimide / styrene copolymer and the like (3) -b, decomposable compound group of polymer system <base decomposable compound>
Poly {p-[(1,1-dimethyl-2-cyano) ethoxycarbonyloxy] styrene},
Poly {p-[(1,1-dimethyl-2-phenylsulfonyl) ethoxycarbonyloxy] styrene},
Poly {p-[(1,1-dimethyl-2-methoxycarbonyl) ethoxycarbonyloxy] styrene},
Poly [p- (2-cyanoethoxycarbonyloxy) styrene],
Poly [(1,1-dimethyl-2-phenylsulfonyl) ethyl methacrylate],
Poly [(1,1-dimethyl-2-cyano) ethyl methacrylate],
And so on.

  Organic polymer compounds such as polyethers, polyamides, polyesters, polyimides, polyvinyl alcohols and dendrimers into which degradable functional groups are introduced can be used as acid-decomposable or base-decomposable polymer compounds. Furthermore, an acid-decomposable or base-decomposable polymer compound in which a decomposable functional group is introduced into an inorganic compound such as silica is also included. Especially, it is preferable that a decomposable functional group is introduce | transduced into the compound group which has a functional group chosen from the group which consists of a carboxylic acid group or a hydroxyl group, and an amine group.

  Among these polymer compounds into which a degradable functional group is introduced, polymer compounds having excellent optical characteristics and heat resistance are particularly suitable for optical waveguide applications. Preferable examples include polyimide, polycarbonate, fluorine-based resin (particularly a fluorine-containing aliphatic ring structure-containing polymer), epoxy resin, silicone resin, polysilane, and cyanate ester resin. Among the polymer materials having excellent optical properties, polyimide is particularly preferable from the viewpoint of heat resistance.

  The decomposable compound group may be used alone or in combination of two or more different types. Moreover, the decomposable compound can be used by mixing with other resins. When mixed, the decomposable compound and the other resin may be either compatible or incompatible. Other resins include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, unsaturated polyester resins, polycarbonate resins, polyolefin resins such as polyethylene and polypropylene, polyolefin composite resins, polystyrene resins, polybutadiene resins, (meth) acrylic resins, Acryloyl resin, ABS resin, fluororesin, polyimide resin, polyacetal resin, polysulfone resin, vinyl chloride resin, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, starch, polyvinyl alcohol, polyamide resin, phenol resin, melamine resin, urea resin, urethane resin, It can be appropriately selected from commonly used resins such as epoxy resins and silicone resins. Moreover, a gas barrier resin can also be used for the purpose of allowing a low-boiling volatile substance that decomposes and gasifies from a decomposable compound to be contained in the molded body. The gas barrier resin may be mixed, coated or laminated, and in order to allow the low boiling point volatile substance to be contained in the molded body, it is preferable to coat or laminate the molded body surface.

  Among the decomposable foaming compounds, the curable monomer-based decomposable compound group and the polymer-based decomposable compound group may be used singly or in combination with the generally used resins. On the other hand, since the non-curable low molecular weight decomposable compound group cannot be molded alone, it is necessary to use it by mixing with the generally used resin.

In order to increase the water resistance of the foam of the present invention, a compound obtained by introducing a decomposable foamable functional group into a compound containing at least one or more types of hydrophobic functional groups can also be used as the foamable composition. The hydrophobic functional group used in the present invention is preferably selected from the group consisting mainly of an aliphatic group, an alicyclic group, an aromatic group, a halogen group, and a nitrile group. The decomposable and foamable functional group is easily introduced into a hydrophilic functional group selected from the group consisting mainly of a carboxylic acid group, a hydroxyl group and an amine group. Therefore, the decomposable compound of the present invention is preferably a composite compound comprising a decomposable unit in which a decomposable and foamable functional group is introduced into the hydrophilic functional group and a hydrophobic unit containing a hydrophobic functional group. In the more preferable composite compound, the decomposable unit and the hydrophobic unit are vinyl polymers. Hydrophobic units include aliphatic (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate, aromatic vinyl compounds such as styrene, methylstyrene and vinylnaphthalene, (meth) acrylonitrile compounds, vinyl acetate A compound group, a vinyl chloride compound group, etc. are mentioned. As a representative example of the decomposable compound, the decomposable unit is tert-butyl acrylate in which a tert-butyl group which is a decomposable functional group is introduced into acrylic acid having a carboxylic acid group of a hydrophilic functional group, and Examples thereof include vinyl copolymers comprising a combination in which the hydrophobic unit is methyl acrylate having a hydrophobic functional group methyl group. Specific examples of the decomposable compound comprising a combination of degradable unit / hydrophobic unit are shown below.
tert-butyl acrylate / methyl methacrylate copolymer tert-butyl methacrylate / methyl acrylate copolymer tert-butyl methacrylate / methyl methacrylate copolymer tert-butyl acrylate / ethyl acrylate copolymer tert-butyl acrylate / ethyl methacrylate copolymer Tert-butyl methacrylate / ethyl acrylate copolymer tert-butyl methacrylate / ethyl methacrylate copolymer tert-butyl acrylate / styrene copolymer tert-butyl acrylate / vinyl chloride copolymer tert-butyl acrylate / acrylonitrile copolymer p -(Tert-Butoxycarbonyloxy) styrene / styrene copolymer In addition, a degradable unit in the decomposable compound and The hydrophobic unit can be used alone or in combination of two or more. The form of copolymerization can be performed arbitrarily such as random copolymerization, block copolymerization, and graft copolymerization. In addition, the copolymerization ratio of the hydrophobic unit is preferably 1 to 95% by mass with respect to the total amount of the decomposable compound, and considering the decomposable foamability of the decomposable compound and the environmental preservation of the foamed structure, 5 to 80 The mass% is more preferable.
The decomposable compounds may be used alone or in combination of two or more different types. The decomposable compound is a compound containing at least one or more kinds of hydrophobic functional groups after the decomposable and foamable functional groups are decomposed and released to generate a bubble forming gas.

In order to increase the water resistance of the foam of the present invention, the foamable composition has a low moisture content of less than 10% as measured by the JIS K-7209D method in an environmental atmosphere at a temperature of 30 ° C. and a relative humidity of 60%. A compound in which a decomposable and foaming functional group is introduced into a functional compound can also be used. Examples of the low hygroscopic compound having a structure in which a decomposable and foamable functional group can be easily introduced include p-hydroxystyrene and m-hydroxystyrene. Accordingly, examples of the decomposable compound include p- (tert-butoxy) styrene, m- (tert-butoxy) styrene, p- (tert-butoxycarbonyloxy) styrene, and m- (tert-butoxycarbonyloxy) styrene. These may be a curable monomer or a polymer in which one or more kinds are mixed.
Further, a decomposable and foamable functional group may be introduced into a composite compound comprising a combination of a highly hygroscopic compound having a water absorption rate of 10% or more and a low hygroscopic compound having a water absorption rate of less than 10%. However, the composite compound preferably has a water absorption of less than 10% by an appropriate combination. For example, a copolymer (composite compound) of acrylic acid, which is a highly hygroscopic compound, and p-hydroxystyrene, which is a low hygroscopic compound, has a copolymerization ratio of acrylic acid / p-hydroxystyrene = 90 / 10-0 / 100 is preferred. Specific examples of degradable compounds include
tert-butyl acrylate / p- (tert-butoxy) styrene copolymer tert-butyl acrylate / m- (tert-butoxy) styrene copolymer tert-butyl acrylate / p- (tert-butoxycarbonyloxy) styrene copolymer tert-butyl acrylate / m- (tert-butoxycarbonyloxy) styrene copolymer tert-butyl methacrylate / p- (tert-butoxycarbonyloxy) styrene copolymer Further polyester, polyimide, polyvinyl acetate, polyvinyl chloride Further, a decomposable and foamable functional group may be introduced into a low-hygroscopic polymer material selected from the group consisting of polyacrylonitrile, phenol resin, and dendrimer.
The decomposable compounds may be used alone or in combination of two or more different types. The decomposable compound becomes a low hygroscopic compound after the decomposable and foaming functional group is decomposed and eliminated to generate a bubble forming gas.

<Foaming composition>
In the foamable composition used in the present invention, in addition to the acid generator or base generator and the decomposition foamable compound, other active energy ray-curable unsaturated organic compounds may be used in combination. Examples of combination compounds include
(1) Aliphatic, alicyclic, aromatic 1-6 valent alcohols and polyalkylene glycol (meth) acrylates (2) Aliphatic, alicyclic, aromatic 1-6 valent alcohols with alkylene (Meth) acrylates of compounds obtained by adding oxide (3) Poly (meth) acryloylalkyl phosphate esters (4) Reaction products of polybasic acid, polyol and (meth) acrylic acid (5) Reaction product of isocyanate, polyol, (meth) acrylic acid (6) Reaction product of epoxy compound and (meth) acrylic acid (7) Reaction product of epoxy compound, polyol, (meth) acrylic acid (8) Melamine and A reaction product of (meth) acrylic acid can be mentioned.

Among the compounds that can be used in combination, curable monomers and resins can be expected to improve physical properties such as foam strength and heat resistance, and control foamability. Moreover, if a curable monomer is used for the decomposable compound and the combination compound, solvent-free molding can be performed, and a production method with less environmental load can be provided. Examples include the following materials.
Specific examples of the combined compound include methyl acrylate, ethyl acrylate, lauryl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, caprolactone-modified tetrahydrofurfuryl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, dicyclohexyl acrylate, isobornyl acrylate, isobornyl methacrylate, benzyl acrylate , Benzylmeta Relate, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxy polyethylene glycol acrylate, phenoxy polypropylene glycol acrylate, ethylene oxide modified phenoxy acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, 2-ethylhexyl carbitol acrylate, ω-carboxypolycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, acrylic acid dimer, 2-hydroxy-3-phenoxypropyl acrylate, acrylic acid-9,10-epoxidized oleyl, ethylene maleate Glycol monoacrylate, dicyclo Pentenyloxyethylene acrylate, acrylate of caprolactone adduct of 4,4-dimethyl-1,3-dioxolane, acrylate of caprolactone adduct of 3-methyl-5,5-dimethyl-1,3-dioxolane, polybutadiene acrylate, ethylene oxide modified Phenoxylated phosphate acrylate, ethanediol diacrylate, ethanediol dimethacrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol di Methacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, di Tylene glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, neopentyl glycol diacrylate, 2-butyl-2-ethylpropanediol diacrylate, ethylene oxide modified bisphenol A diacrylate, Polyethylene oxide modified bisphenol A diacrylate, polyethylene oxide modified hydrogenated bisphenol A diacrylate, propylene oxide modified bisphenol A diacrylate, polypropylene oxide modified bisphenol A diacrylate, ethylene oxide modified isocyanuric acid diacrylate, pentaerythritol diacrylate monostearate 1,6-hexanediol diglycidyl ether acrylic acid adduct, polyoxyethylene epichlorohydrin modified bisphenol A diacrylate, trimethylolpropane triacrylate, ethylene oxide modified trimethylolpropane triacrylate, polyethylene oxide modified trimethylolpropane triacrylate, Propylene oxide modified trimethylolpropane triacrylate, polypropylene oxide modified trimethylolpropane triacrylate, pentaerythritol triacrylate, ethylene oxide modified isocyanuric acid triacrylate, ethylene oxide modified glycerol triacrylate, polyethylene oxide modified glycerol triacrylate, propylene oxide modified glycerol triacrylate Polypropylene oxide modified glycerol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, caprolactone modified dipentaerythritol hexaacrylate, polycaprolactone modified Although dipentaerythritol hexaacrylate etc. can be mentioned, it is not restricted to these.
Further, as part or all of the combined active energy ray-curable unsaturated organic compound, an active energy ray-curable resin having a (meth) acryloyl group at the molecular chain terminal and having a molecular weight of about 400 to 5000 can be combined. . As such a curable resin, for example, polyurethane poly (meth) acrylate polymers such as polyurethane-modified polyether poly (meth) acrylate and polyurethane-modified polyester poly (meth) acrylate are preferably used.

  The foamable composition used for this invention can contain additives other than a decomposable compound as needed. Additives include inorganic or organic compound fillers, dispersants such as various surfactants, reactive compounds and antioxidants such as polyvalent isocyanate compounds, epoxy compounds and organometallic compounds, silicone oils and processing aids. Contains one or more types of agents, UV absorbers, optical brighteners, anti-slip agents, antistatic agents, anti-blocking agents, anti-fogging agents, light stabilizers, lubricants, softeners, colored dyes, and other stabilizers. You may not. By using an additive, improvement in moldability, foamability and the like can be expected.

  Specific examples of inorganic compound fillers include titanium oxide, magnesium oxide, aluminum oxide, silicon oxide, calcium carbonate, barium sulfate, magnesium carbonate, calcium silicate, aluminum hydroxide, clay, talc, silica and other pigments, stearic acid Metal soap such as zinc, as well as dispersants such as various surfactants, calcium sulfate, magnesium sulfate, kaolin, silicate clay, diatomaceous earth, zinc oxide, silicon oxide, magnesium hydroxide, calcium oxide, magnesium oxide, alumina, mica, Asbestos powder, glass powder, shirasu balloon, zeolite, etc. are achieved. Examples of the organic compound filler include cellulose powders such as wood powder and pulp powder.

Examples of the organic compound filler include cellulose powder such as wood powder and pulp powder, and polymer beads. As the polymer beads, for example, those produced from acrylic resin, styrene resin or cellulose derivative, polyvinyl resin, polyvinyl chloride, polyester, polyurethane and polycarbonate, monomers for crosslinking, and the like can be used.
These fillers may be a mixture of two or more. When these fillers are added, it is preferable to add those finely divided to a size of 100 nm or less so as not to deteriorate the properties of the light guide.

Specific examples of the ultraviolet absorber are selected from salicylic acid-based, benzophenone-based, or benzotriazole-based ultraviolet absorbers. Examples of salicylic acid-based ultraviolet absorbers include phenyl salicylate, pt-butylphenyl salicylate, p-octylphenyl salicylate, and the like. Examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone. Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-5′-t-butylphenyl) benzotriazole and the like.
Specific examples of the antioxidant include monophenol-based, bisphenol-based, polymer-type phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.
A typical example of the light stabilizer is a hindered amine compound.

The softening agent can be used for the purpose of improving moldability or processability of the molded body. Specifically, ester compounds, amide compounds, hydrocarbon polymers having side chains, mineral oils, liquid paraffins, Examples thereof include waxes.
The ester compound is not particularly limited as long as it is a mono- or polyester having a structure comprising an alcohol and a carboxylic acid, and may be a compound in which the hydroxyl group and carbonyl group ends are left in the molecule, or a compound blocked in the form of an ester group. . Specifically, stearyl stearate, sorbitan tristearate, epoxy soybean oil, refined castor oil, hydrogenated castor oil, dehydrated castor oil, epoxy soybean oil, extremely hardened oil, trioctyl trimellitic acid, ethylene glycol dioctanoate, pentaerythritol tetra Examples include octanoate.
The amide compound is not particularly limited as long as it is a mono- or polyamide compound having a structure composed of an amine and a carboxylic acid, and may be a compound in which the amino group and carbonyl group ends are left in the molecule, or a compound blocked in the form of an amide group. Good. Specifically, stearic acid amide, behenic acid amide, hexamethylene bis stearic acid amide, trimethylene bisoctylic acid amide, hexamethylene bishydroxy stearic acid amide, triocta trimellitic acid amide, distearyl urea, butylene bis stearic acid Amides, xylylene bis stearic acid amides, distearyl adipic acid amides, distearyl phthalic acid amides, distearyl octadecadioic acid amides, epsilon caprolactam, and derivatives thereof.
The hydrocarbon polymer having a side chain is preferably a poly α-olefin and classified into a normal oligomer having a side chain having 4 or more carbon atoms. Specifically, ethylene-propylene copolymer and its maleic acid derivative, isobutylene polymer, butadiene, isoprene oligomer and hydrogenated product thereof, 1-hexene polymer, polystyrene polymer and the like are derived from these. Derivatives thereof, hydroxypolybutadiene and hydrogenated products thereof, and terminal hydroxypolybutadiene hydrogenated products.
The foamable composition used in the present invention can be prepared using a general kneader. For example, two rolls, three rolls, cowless resolver, homomixer, sand grinder, planetary mixer, ball mill, kneader, high speed mixer, homogenizer, and the like. An ultrasonic disperser or the like can also be used.
Further, the optical loss of the optical waveguide formed from the foamable composition used in the present invention is preferably 3 dB / cm or less for light having a wavelength in the range of 600 nm to 1600 nm. If it is greater than 3 dB / cm, the resulting light guide may have a large optical loss and may not be practical. The lower limit of optical loss is not particularly limited, and the lower the optical loss, the better.

<Light guide manufacturing process>
The light guide manufacturing process of the present invention includes a step of irradiating the foamable composition with active energy rays, and a step of foaming by controlling the pressure in a temperature region where the low boiling point volatile substance is decomposed and desorbed from the foamable composition. Including. By controlling the pressure when the low boiling point volatile substance decomposes and desorbs and foams, it becomes possible to easily control the foam structure and shape of the clad.
In order to stably obtain a fine cell foam having a desired thickness, shape and foam structure, the production method of the present invention can include a molding step. The molding process can be classified into a preforming process and a foam molding process. A preforming process is a process of shape | molding the foamable composition which is resin before foaming by the formation process provided before and after the process of irradiating an active energy ray, and the process shape | molded during irradiation. The foam molding step is a step of molding while foaming by controlling pressure as necessary in a temperature range where the low boiling point volatile substance decomposes and desorbs, and a step of molding the foam after the foaming step.

First, the process of irradiating an active energy ray to a foamable composition is demonstrated. Examples of active energy rays used in the present invention include ionizing radiation such as electron beams, ultraviolet rays, visible rays, and γ rays. In these, it is preferable to use an electron beam and an ultraviolet-ray.
When electron beam irradiation is used, the acceleration voltage may be adjusted to 20 to 100 kV according to the thickness of the foamable composition, and more preferably a curtain type electron beam irradiation apparatus or electron beam drawing under the condition of 30 to 300 kV. It is preferable to use an apparatus. If the accelerating voltage is lower than the above range, the transmission power of the electron beam becomes insufficient, and the inside of the molded body cannot be sufficiently transmitted. If it is larger than this range, the energy efficiency is not only deteriorated. In some cases, the strength of the obtained molded article becomes insufficient, the resin and additives contained therein are decomposed, and the quality of the obtained foam is unsatisfactory. When the oxygen concentration in the irradiation atmosphere is high during electron beam irradiation, generation of acid or base and / or curing of the curable decomposable compound may be hindered. Substitution with an inert gas such as carbon is preferred. The oxygen concentration in the irradiation atmosphere is preferably 1000 ppm or less, and more preferably 500 ppm or less in order to obtain more stable electron beam energy.

In the case of ultraviolet irradiation, an ultraviolet lamp generally used in the semiconductor / photoresist field or the ultraviolet curing field can be used. Typical UV lamps include, for example, halogen lamps, halogen heater lamps, xenon short arc lamps, xenon flash lamps, ultra high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, medium pressure mercury lamps, deep UV lamps, metal halide lamps. There are noble gas fluorescent lamps, krypton arc lamps, excimer lamps, etc., and in recent years, there are also Y-ray lamps that emit an extremely short wavelength (peak at 214 nm). Some of these lamps are ozone-less types that generate less ozone. These ultraviolet rays may be scattered light or parallel light with high straightness. In order to form partial foaming accurately, parallel light is preferable. For ultraviolet irradiation, various lasers such as ArF excimer laser, KrF excimer laser, YAG laser via a harmonic unit including a nonlinear optical crystal, and ultraviolet light emitting diodes may be used. The emission wavelength of the ultraviolet lamp, laser, or ultraviolet light emitting diode is not limited as long as it does not interfere with the foaming property of the foamable composition. Preferably, the photoacid generator or the photobase generator is efficient in acid or base efficiency. The emission wavelength that is often generated is good. That is, an emission wavelength that overlaps with the photosensitive wavelength region of the photoacid generator or photobase generator to be used is preferable. Furthermore, the light emission wavelength which overlaps the maximum absorption wavelength or the maximum absorption wavelength in the photosensitive wavelength region of these generators is more preferable, and the generation efficiency tends to increase. The energy irradiation intensity of ultraviolet rays is appropriately determined depending on the foamable composition. When using UV lamps with high irradiation intensity, such as various mercury lamps and metal halide lamps, productivity can be improved, and the irradiation intensity (lamp output) is 30 W / cm or more for long arc lamps. Is preferred. The integrated irradiation light quantity (J / cm ² ) of ultraviolet rays is obtained by adding the irradiation time to the energy irradiation intensity, and is appropriately determined depending on the foamable composition and the desired bubble distribution. It may be set according to the extinction coefficient of the acid generator or base generator. For stable and continuous production, a range of 1.0 mJ / cm ^{2 to 20} J / cm ² is preferable. When using an ultraviolet lamp, the irradiation time can be shortened because the irradiation intensity is high. When an excimer lamp or excimer laser is used, the irradiation intensity is weak, but it is close to a single light, so if the emission wavelength is optimized for the photosensitive wavelength of the generator, higher generation efficiency and foamability Is possible. When the amount of irradiation light is increased, heat generation may interfere with foaming properties depending on the ultraviolet lamp. At that time, a cooling treatment such as a cold mirror can be performed.

  In the light guide manufacturing method of the present invention, in order to obtain a patterned clad portion in the form of a foam, irradiation with active energy rays is performed using a photomask so that an intensity distribution of active energy is generated in the irradiation process. can do. When a photomask including a drawing pattern is used, an intensity distribution of active energy rays to which the drawing pattern is transferred can be obtained. As a photomask drawing pattern, the core part of the optical waveguide part is shielded with a mask, a pattern is created so that the active energy ray hits the clad part, and the energy transmission is adjusted as a means of adjusting the expansion ratio of the clad part. Various things such as the ones that are tones can be designed as appropriate according to the application. The core part is an unfoamed part and serves as a light path of the optical waveguide.

  Photomasks include chrome masks, metal masks, silver salt glass masks, silver salt films, screen masks, glass ion-etched masks, and masks with electron beam-drawing interference fringes on planar lenses that have a condensing function. it can. A mask obtained by printing a drawing pattern on a photomask substrate with a printer using an ink jet printer or an ultraviolet curable ink can also be used as a mask. Printing may be performed on one side or both sides of the substrate. In order to increase the printing accuracy of the drawing pattern, it is preferable to modify the surface of the substrate to be printed. As a specific example of the modification treatment, a functional layer that enhances the absorbability of the ink to be printed is provided on the surface of the substrate by a coating method or an adhesion method. However, this functional layer must not significantly impair the basic optical performance of the photomask.

  Further, the ink to be used is preferably a material that absorbs, scatters, or reflects active energy rays, while the photomask base material is preferably a material that transmits active energy rays. When irradiating ultraviolet rays with a wavelength of 300 nm or less, it is preferable to use quartz glass as the base material of the photomask. You may utilize the foam which has the bubble distribution obtained by this invention as a photomask. As an irradiation method using a photomask, methods such as contact irradiation and projection irradiation can be adopted. In order to transfer the pattern of the photomask with high accuracy, it is preferable that the irradiated light is uniform parallel light. Examples of the exposure system for irradiating parallel light include an optical system using an integrator and a parabolic mirror, an optical system using a Fresnel lens, and an optical system using a honeycomb board and a diffusion plate. In order to obtain high uniformity, an optical system using an integrator and a parabolic mirror is generally preferable, and a short arc lamp is preferable as a light source used in this optical system. Examples of the short arc lamp include a metal halide lamp, an ultra-high pressure mercury lamp, a mercury xenon lamp, a sodium lamp, and a Y-ray lamp. Further, a method of irradiating radiation that generates interference fringes is also possible.

  Next, in the foaming step, the higher the temperature applied to the foamable composition, the higher the reaction rate at which the low-boiling volatile substances decompose and desorb, so the bubbles are more likely to be refined. However, when the glass transition temperature of the foam resin after foaming is low, when the pressure is released in a high temperature state after the foaming step, the bubbles grow and coalesce and the bubble diameter increases at a stretch and the fine bubbles cannot be maintained. Since the deformation ratio due to foaming becomes large, a foam having a desired shape may not be obtained. In such a case, it is more preferable to include a step of cooling while controlling the pressure after the pressure control foaming step. Examples of the cooling method include a method in which a structure capable of flowing cooling water is formed in the pressurization heating part and the mold of the press machine and the method is cooled by water cooling and the method of electrically forced cooling using a Peltier element.

  The steps in the method of manufacturing the light guide according to the present invention are not limited to these, and various steps other than these can be added at appropriate desired portions. For example, processes such as a stretching process, a cleaning process, a drying process, and a relaxation process may be appropriately introduced. The production method of the present invention comprises a combination of these steps, and the steps can be combined discontinuously or continuously, or at least two steps can be simultaneous steps. Either the batch method or the continuous method may be used. Further, in the light guide manufacturing method of the present invention, since the active energy intensity distribution, the thermal energy intensity distribution, the concentration distribution of the foamable composition, and the like can be attached, the bubble diameter of the foamed part formed in the clad portion and Control of the bubble distribution related to the bubble density is arbitrarily variable, and a light guide having a bubble distribution can also be obtained. Although the specific example of each process is demonstrated below, this invention is not limited.

First, the step of foaming by controlling the pressure in a temperature range where the low boiling point volatile substance is decomposed and desorbed from the foamable composition will be described. Examples of pressure control methods include a partly facing surface pressure control method in which pressure is controlled by applying pressure only from the facing surfaces using two plates as shown in FIG. 1, and from the entire surface using a mold as shown in FIG. For example, an overall pressure control method in which pressure is controlled by pressurization. Further, there are a type in which the pressure can be varied according to the pushing force without having a gap control function as shown in FIGS. 1 and 2, and a type having a gap control function as in FIGS. In the case of the entire surface pressure control method, pressure control is performed by injecting a fluid such as gas, liquid, or melt into a closed mold, and pressure control is performed by the foam self-expanding force by foaming of the foamable composition and the generated gas pressure. And a method of controlling the pressure by the thermal expansion force of the mold and the mold contents.
In order to obtain a temperature region in which the low boiling point volatile substance is decomposed and desorbed, it is possible to use a heater or to use the remaining heat when heat is applied in the previous step. The temperature range where the low boiling point volatile substance decomposes and desorbs from the foamable composition is higher than the minimum temperature at which the low boiling point volatile substance decomposes and desorbs. That is, it refers to a temperature range in a range lower than the temperature at which various physical properties such as the decomposition temperature or strength of the foam resin are not impaired. This temperature range varies depending on the type of foamable composition. For example, in the case of an acrylic foamable composition, the minimum decomposition and desorption temperature is about 75 to 85 ° C, and the decomposition temperature of the foam resin is about 180 to 200 ° C. The minimum temperature is about 65 to 80 ° C, and the decomposition temperature of the foam resin is about 160 to 180 ° C. The higher the temperature during foaming, the higher the decomposition and desorption rate of the low boiling point volatile substances, and the higher the degree of supersaturation. However, the higher the temperature, the lower the resin viscosity, and bubbles tend to grow and coalesce and become larger. Therefore, there exists a temperature range suitable for foaming. The region varies depending on the type of the foamable composition, but is 65 to 200 ° C, preferably 90 to 180 ° C, and more preferably 100 to 160 ° C.

  Although there is no restriction | limiting in particular as a heater, What can be heated by induction heating, resistance heating, dielectric heating (and microwave heating), infrared heating, etc. can be illustrated. Examples include an electric or gas infrared dryer using radiant heat, a roll heater using electromagnetic induction, an oil heater using an oil medium, an electric heater, and a hot air dryer using these hot airs. In the case of dielectric heating and infrared heating, the internal heating method directly heats the inside of the material, so it can be heated more uniformly and instantaneously than external heating methods such as hot air dryers, but the material of the plate or mold used for pressure control can be changed. It is necessary to select appropriately. In the case of dielectric heating, high frequency energy with a frequency of 1 MHz to 300 MHz (wavelength 30 m to 1 m) is used. A frequency of 6 MHz to 40 MHz is often used. Among dielectric heating, especially microwave heating uses microwaves with a frequency of 300 MHz to 300 GHz (wavelength 1 m to 1 mm), but 2450 MHz and 915 MHz (same as microwave ovens) are often used. In the case of infrared heating, an electromagnetic wave having a wavelength in the infrared region of 0.76 to 1000 μm is used. Although the optimum band of the wavelength selected varies depending on the situation from the heater surface temperature and the infrared absorption spectrum of the material to be heated, a wavelength band of preferably 1.5 to 25 μm, more preferably 2 to 15 μm can be used.

  In the production method of the present invention, in order to obtain a foam part in which the bubble distribution is arbitrarily changed, heat treatment can be performed so as to produce a thermal energy intensity distribution. The intensity distribution of thermal energy is preferably adjusted by the heating temperature. As a method of creating a thermal energy intensity distribution, a method of providing a temperature difference on the opposite surface, a method of applying a heating method used in a general thermal recording printer, that is, a print head used in a thermal printer. The heating part is controlled by a heating element in which a large number of fine heating elements that generate heat when such current is passed, and the heating part is controlled by laser irradiation such as a laser heating head used in a laser printer. It is done.

  The molding process (preliminary molding process, foam molding process) included in the method of manufacturing the light guide according to the present invention will be described. As a molding method used in the molding process, coating molding, extrusion molding, injection molding, cast molding, press molding, or the like can be selected according to the shape to be molded. The resin shape obtained in the molding step is not particularly limited, and can be appropriately determined depending on the purpose of use of the foam. Examples include sheet-like materials (including film-like materials), fiber-like materials, rod-like materials, and materials having other desired shapes. The sheet-like material may be a single sheet-like material or a sheet layer in close contact with the support, or may be a laminated structure of a plurality of resins.

  As an example of coating molding, after applying a foamable composition to a support using a coating head, if the foamable composition is diluted with a solvent, remove the solvent with a dryer. And a method of obtaining a sheet layer made of a foamable composition on a support. At this time, the sheet | seat layer which consists of a foamable composition can also be obtained by peeling a sheet | seat layer from a support body. Coating methods include bar coating, air doctor coating, blade coating, squeeze coating, air knife coating, roll coating, gravure coating, transfer coating, comma coating, smoothing coating, and micro gravure. Examples include coating method, reverse roll coating method, multi-roll coating method, dip coating method, rod coating method, kiss coating method, gate roll coating method, falling curtain coating method, slide coating method, fountain coating method, and slit die coating method. . Examples of the support include paper, synthetic paper, plastic resin sheet, metal sheet, metal vapor deposition sheet, and the like, and these may be used alone or may be laminated with each other. The plastic resin sheet is, for example, a general-purpose plastic sheet such as a polystyrene resin sheet, a polyolefin resin sheet such as polyethylene or polypropylene, and a polyester resin sheet such as polyethylene terephthalate, an engineering resin such as a polyimide resin sheet, an ABS resin sheet, or a polycarbonate resin sheet. A plastic sheet etc. are mentioned, Moreover, aluminum, copper, etc. are mentioned as a metal which comprises a metal sheet. Examples of the metal deposition sheet include an aluminum deposition sheet, a gold deposition sheet, and a silver deposition sheet.

Examples of the extrusion molding method include a general extrusion molding method using a screw-like extrusion shaft, and a ram extrusion molding method using a piston-like extrusion shaft.
Examples of injection molding methods include, in addition to the normal injection molding method, vacuum filling molding method, injection compression molding method, high-speed vacuum filling molding method, gas absorption melt molding method, mold thermal cooling / heating cycle molding method, low-pressure low-speed filling molding method. Method, injection press molding method, stack mold molding method and the like. The methods for thin-wall molding and high-transfer rate molding of fine shapes, which are the latest trends, are the heat-insulating mold molding method, the ultra-high-speed injection molding method with an injection speed of 1000 to 2000 mm / sec. Examples include an injection molding method using a supercritical fluid in which an active gas is dissolved in a molten resin in a supercritical state and molded without foaming.
As an example of cast molding, a liquid foamable composition containing an active energy ray-curable monomer is cast into a prism sheet-shaped mold, cured by irradiating with active energy rays, and demolded to form a prism sheet shape The method of obtaining a thing etc. are mentioned. By appropriately selecting the irradiation conditions such as the light source and wavelength of the active energy ray, it is possible to simultaneously cause resin curing and acid and base generation from the acid and base generator.

  In the production of the light guide of the present invention, a method of directly forming the foamable composition as a raw material into the final shape of the planar light emitting device (light guide) before lamination or a shape close thereto is used in the preforming step. It is also possible to use a method of forming in a multi-stage from a temporary shape into a relatively simple shape such as a sheet shape, a rod shape, a pellet shape, and a powder shape, and then forming the final shape of the foam or a shape close thereto. . In either method, the molding method described above can be used as appropriate.

Next, regarding the foam molding process, “a sheet-shaped or plate-shaped light guide in which two or more sheets are laminated, and the core portions of adjacent layers are connected to each other, so that the optical waveguide has two or more layers. A case where it is formed over “is formed” will be described as an example.
In this case, the foaming process of the light guide is as follows: (1) A layer irradiated with an active energy ray in accordance with a pattern and foamed by controlling the pressure in a temperature range where the low-boiling volatile substances decompose and desorb. And a step of forming the light guide by laminating after the foaming step of the clad part.
In either case, the core part of one layer (unfoamed part) and the core part of the adjacent layer are connected, the core part is formed across two or more layers, and the light passes through it. It is necessary to keep. The lowermost layer is a layer that reflects light, and the uppermost layer constitutes a core that allows light to travel outward. There may be a substrate layer under the lowermost layer, and a transparent layer or a light diffusion layer may be formed on the uppermost layer.
Here, the polymer substances in each layer may be the same or different, but it is preferable that the layers forming the waveguide are made of the same material from the viewpoint of bonding properties and production efficiency.

<Structure of light guide>
The cross-sectional shape of the light incident portion of the waveguide including the core portion and the cladding portion inherent in the light guide manufactured according to the present invention is the length of the waveguide in the vertical direction and the length of the waveguide in the direction perpendicular thereto. When the height is the horizontal length, the aspect ratio is (horizontal length) ÷ (vertical length). The aspect ratio is 0.1-10. When the aspect ratio is out of this range, the light incident loss from the light source to the light guide increases, and the efficiency decreases. Further, the longitudinal length, which is the length in the thickness direction of the core portion of the optical waveguide, and the lateral length in the direction perpendicular thereto are each 1 μm or more and 100 μm or less. The minimum radius of curvature of the core portion varies depending on the bubble content, but can be reduced to about 80 μm when the volume porosity of the cladding portion is 33%.

The substrate may be a plate having little flexibility, a film having flexibility, or an intermediate one, and is particularly limited. is not. The material used is not particularly limited, and specific examples include a silicon wafer, a metal substrate, a ceramic substrate, and a polymer substrate.
The material of the polymer substrate is not particularly limited. For example, polyimide resin, polyamideimide resin, polyetherimide resin, polyamide resin, polyester resin, polycarbonate resin, polyketone resin, polysulfone resin, polyphenylene ether resin , Polyolefin resin, polystyrene resin, polyphenylene sulfide resin, fluororesin, polyarylate resin, liquid crystal polymer resin, epoxy resin, cyanate resin and the like.

  The method for laminating two or more sheets constituting the light guide is not particularly limited, and a conventionally known method can be used. Specifically, it is possible to perform lamination by pressure bonding or thermocompression bonding without using an adhesive, and it is also possible to perform lamination by using an adhesive. In the method using an adhesive, it is preferable to use thermoplastic polyimide as the adhesive. Thereby, heat resistance and adhesiveness can be made more excellent.

<Use of light guide>
The light guide of the present invention is applied as a planar light emitting device. The planar light-emitting device includes a light source disposed in proximity to or in contact with the incident surface side of the light guide. As the light source, a linear light source such as a cold cathode tube or a point light source such as a light emitting diode (LED) can be appropriately employed.
The light guide of the present invention can be used for various display devices in the same manner as conventional light guides. For example, it can be used as a backlight or a front light of a liquid crystal display device used for a display of a television, a mobile phone, a personal computer, an automobile or the like. Further, it can also be used as internal illumination of a display device used for a guide sign board, a signboard, a traffic sign or the like in a station or public facility. It can also be used for general lighting used in offices and homes.

  The present invention will be described in detail by the following examples, but the present invention is not limited to these examples. Unless otherwise specified, “parts” and “%” in the examples represent “parts by mass” and “mass%”, respectively.

<Example 1>
(1) Foamable composition As a decomposable compound, an iodonium salt system is used for 100 parts of a copolymer of tert-butyl acrylate (20%), tert-butyl methacrylate (40%) and methyl methacrylate (40%). As an acid generator, a foamable composition A in which 3 parts of bis (4-tert-butylphenyl) iodonium perfluorobutanesulfonate (trade name: BBI-109, manufactured by Midori Chemical) was mixed was used.

(2) Preliminary molding step A 25% solution of the foamable composition having the above-mentioned mixing ratio was prepared with a diluent of MEK / ethyl acetate = 65/35 (mass ratio), and this was used as a coating solution. Using this applicator (FIG. 1a), an applicator having a clearance of 300 μm on a silicone-treated surface of a support made of 75 μm thick silicone PET (FIG. 1b) (trade name: MR-75: manufactured by Mitsubishi Polyester). Coated and left in a constant temperature dryer at 110 ° C. for 10 minutes to evaporate and remove the diluted solution. After removing the sample from the constant temperature dryer, the coating layer was peeled off from the silicone PET to obtain a foamable composition film having a thickness of 45 μm.

(3) Ultraviolet irradiation A quartz plate (FIG. 5c) in which a mask made of chromium plating is applied to the foamable composition film in the step (2) so that ultraviolet light hits a portion that becomes a low refractive index cladding portion of the optical waveguide. Sheets 1-10 (FIG. 5d), which were stacked on a film and irradiated with ultraviolet rays at an irradiation dose of 2000 mJ / cm ^{2 using} a metal halide lamp (trade name: multi-metal lamp for ultraviolet curing M03-L31, manufactured by Eyegraphic Co., Ltd.) as a light source. A sheet 11 (FIG. 5e) is obtained by irradiating the entire surface of the sheet with ultraviolet rays at an irradiation dose of 2000 mJ / cm ² without applying a mask.

(4) Foaming step The sheets 1 to 10 and the sheet 11 obtained by the step (3) are cut out at 5 cm × 6 cm, respectively, and the sheets 2 are laminated on the upper and lower sides of the sheet 1, respectively, 10 cm × 10 cm, thickness 1 mm The laminate sample was press-molded at 150 ° C. for 3 minutes under a pressure of 6 MPa using a hand press machine (trade name: Mini TEST PRESS-10 manufactured by TOYOSEIKI). After the press was released, the sample was taken out from the press machine while being sandwiched between the SUS plates, naturally air-cooled, and the light guide molded product was removed from the SUS plate.

(5) Light guide structure evaluation A cross-sectional observation was performed to confirm the structure of the obtained light guide. The sample was frozen and cut in liquid nitrogen, and the size of the core (FIG. 6f) was measured with an optical microscope. The size of the core part was 10 μm × 10 μm.
Furthermore, gold vapor deposition treatment was performed on the foam cross section, and the cross-sectional structure of this gold vapor deposition surface was observed using a scanning electron microscope (trade name: S-510, manufactured by Hitachi, Ltd.). The average bubble diameter of the foamed portion of the clad portion (FIG. 6g) was selected as an average of 100 diameters by randomly selecting 100 bubbles from the cross-sectional observation image (magnification: 20000 times). The expansion ratio was calculated from the number of bubbles per unit area (Nf) and the bubble diameter (D) using the following formula: Expansion ratio = 1 / (1-πD ³ Nf / 6). The average cell diameter of the clad part was 100 nm, and the expansion ratio was 1.5 times.

(6) Refractive index calculation The refractive index measurement of each of the core part and the clad part of the sheets 1 to 10 applies a beam profile reflectance measurement method, and a high-precision film thickness meter Opti-Probe 2000 (manufactured by Therma Wave Co., Ltd.) as a measuring device. ), And the measurement wavelength was 675 nm and the beam spot diameter was 1 μm. As a result of the measurement, the core part was 1.57 and the clad part was 1.38.

(7) Surface light emitting device and light emission evaluation Four white chip LEDs (manufactured by Nichia, external dimensions: 1.2 mm long, 1.5 mm wide, 0.6 mm high) on the side surface of the light guide obtained in the above process. Evenly arranged. The incident direction at this time was adjusted to the direction facing the light introduction part on the side surface of the light guide. A surface light-emitting device was obtained by incorporating these into a white housing.
When the uniform light emitting property of the obtained planar light emitting device was visually evaluated, it showed uniform light emission without overlapping the light diffusing sheet, and it was difficult to achieve with conventional technology. Even if there was no diffusion sheet, it was possible to easily obtain a planar light emitting device that uniformly and efficiently emitted light without uneven brightness.

<Example 2>
(4) A light guide was formed and evaluated in the same manner as in Example 1 except that the pressure applied to the laminated sample in the foaming step was 2 MPa.

<Example 3>
The steps from (1) to (3) are the same as in Example 1.
(4) Foam molding step The laminated sheets were set in a rectangular parallelepiped molding die having a bottom surface of 5 cm × 6 cm, and foamed while being press-molded at 130 ° C. for 2 minutes under a pressure of 4 MPa. After releasing the press, the mold was removed from the hand press machine and allowed to cool naturally, and when the mold temperature reached about 40 ° C., the light guide was removed from the rectangular parallelepiped mold. Thereafter, evaluation was performed in the same manner as in Example 1.

<Example 4>
(1) Foamable composition An iodonium salt acid generator for 100 parts of a copolymer of tert-butyl acrylate (60%), methyl methacrylate (30%) and methacrylic acid (10%) as a decomposable compound. As the foaming composition B, 3 parts of bis (4-tert-butylphenyl) iodonium perfluorobutanesulfonate was used.
Thereafter, a light guide was formed and evaluated in the same manner as in Example 1.

<Comparative Example 1>
A light guide was prepared and evaluated in the same manner as in Example 1 except that the foaming temperature was set to 150 ° C. under the condition that pressure was not applied to the sample in (4) foaming step of Example 1.
As a result, the bubble diameter of the clad portion became too large and clouded, and the refractive index could not be evaluated.

  As described above, in the present invention, a part of the low refractive index material forming the cladding portion of the optical waveguide inherent in the light guide constituting the planar light emitting device has an average bubble diameter of 5 to 200 nm and the voids in the foamed portion. A compound comprising a foam part having a rate of 1 to 95%, wherein the foam part reacts with an acid or base to generate acid and base by active energy rays and decomposes and desorbs low-boiling volatiles. A thin planar light emitting device with high luminous efficiency can be produced by forming fine bubbles by heating the foamable composition containing the above after irradiation with an electron beam or ultraviolet rays. Therefore, the present invention greatly contributes to the miniaturization of the planar light emitting device, and can be used not only for the resin industry and the material industry for processing a polymer material into a light guide, but also for producing a specific optical component. The present invention can be widely applied to industries related to optical equipment and optoelectronic equipment related to display equipment.

Pressure control method using a plate (no gap control function) Pressure control method using mold (no gap control function) Pressure control method using a plate (with gap control function) Pressure control method using a mold (with gap control function) It is a schematic diagram which shows the manufacturing method of the multiple sheet laminated light guide concerning this invention. It is a schematic diagram which shows the cross section (the light-incident part cross section from a light source, and an internal cross section) of the multi-sheet lamination | stacking light guide concerning this invention.

Explanation of symbols

1 to 4. 1. Foamable composition (plate-like); 2. Pressure control plate (no gap adjustment function); 3. Upper die of pressure control mold 4. Lower die for pressure control (no gap adjustment function) 5. Pressure control plate (with gap adjustment function), 6. Lower die for pressure control (with gap adjustment function) Functional part for gap adjustment About FIGS. 5 to 6 a Foamable composition b Base material (film, etc.)
c UV shielding mask d Sheets 1 to 10 (irradiation with ultraviolet rays other than the core)
e Sheet 11 (entire UV irradiation)
f Core part (unfoamed)
g Cladding part (material with lower refractive index than foamed or core part)

Claims (6)

  A light guide that is made of a polymer material and guides light through an optical waveguide formed by a core part and a clad part made of a material having a refractive index lower than that of the core part. The clad part has an average bubble diameter. A light guide comprising a foam containing fine closed cells of 5 to 200 nm, and having a volume porosity of 1 to 95%.   Decomposing foam that contains an acid generator that generates an acid by the action of active energy rays or a base generator that generates a base, and further decomposes and desorbs one or more low-boiling volatile substances by reacting with the acid or base. 2. The light guide according to claim 1, wherein the foamed composition containing a compound having a functional functional group is obtained by irradiating an active energy ray at a position where a clad portion is formed and foaming.   It is a sheet-like or plate-like light guide in which two or more sheets are laminated, and the optical waveguide is formed across two or more sheets by connecting the core portions of adjacent layers. The light guide according to claim 1 or 2.   The method for manufacturing a light guide according to claim 2 or 3, wherein the foam part irradiates active energy rays and heat-treats to form the fine closed cells.   5. The method of manufacturing a light guide according to claim 4, further comprising a step of foaming by controlling the pressure in a temperature range where the low boiling point volatile substance is decomposed and desorbed in the process of forming the foam part.   The process of forming the foam part includes a step of cooling while controlling pressure after the step of foaming by controlling the pressure in a temperature range where the low boiling point volatile substance decomposes and desorbs. The manufacturing method of the light guide as described.

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