JP2007264343A - Light diffusion body, manufacturing method of light diffusion body, surface light emitting device, display device, and illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusion body not only making biased emitted light from a light source uniform but also enhancing light utilization efficiency and productivity by thinning, uniting and saving of members, to provide its manufacturing method, to provide a surface light emitting device using the light diffusion body, to provide a display device, and to provide an illumination device. <P>SOLUTION: The light diffusion body is provided with a light diffusion part made of a foaming body foamed by imparting radiation energy and heat energy and having a prescribed distribution pattern of foam density. The foam occupation area ratio of the foaming body is preferably distributed in ≤65% range and the light diffusion part preferably has a low foaming region having ≤0.5% foam occupation area ratio and a high foaming region having ≥1% foam occupation area ratio. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light diffuser, a display device using the same, a display device such as a liquid crystal display device, and an illumination device. More specifically, the present invention relates to a light diffuser made of a foam foamed by application of radiation energy and thermal energy, a method for manufacturing the same, and a surface light emitting device, a display device, and an illumination device using the same.

The light diffuser has a function of diffusing light from a light source, and is used as a light source surface or an optical member of a surface light emitting device. For example, the light diffuser coated on the surface of the LED light source unit described in Patent Document 1, the light diffuser mounted on the direct type backlight described in Patent Document 2 to Patent Document 6, and the edge described in Patent Document 7 Light diffuser mounted on the mold backlight. Emission lines that can be seen by eliminating the bright lines of the light source itself with direct type backlights, and the brightness unevenness (eye phenomenon) occurring near the light source in the case of edge type backlights and uneven brightness lines in the bright line dark line pattern in the light emission surface. The luminance is made uniform.
The structure of the diffuser is roughly divided into two groups: a type in which the diffusing agent is uniformly distributed and a type in which the diffusing agent is non-uniformly distributed. In the former group, a diffusing agent made of pigment or resin beads is internally added to a matrix resin, and light from a light source is diffused randomly. On the other hand, the latter group generally includes pattern printing with an ink containing a light diffusing agent and a pattern coating with a light concealing or light reflecting film, which makes the light from the light source more uniform than the former. It is possible.
Surface light emitting devices including these light diffusers are widely used in backlights for liquid crystal display devices and surface light emitting devices for illumination devices. In particular, applications in which liquid crystal display devices are installed have expanded dramatically in recent years, and include mobile phones, digital cameras, car navigation systems, personal computers, televisions, game machines, and the like.
JP 2006-18261 A JP 2004-271567 A Japanese Patent Laid-Open No. 11-212090 JP 2000-164411 A JP-A-5-477 JP 2006-30910 A JP 2002-22965 A

In a surface light-emitting device used for applications in which display quality is regarded as most important, such as a liquid crystal display device, particularly a backlight, if the luminance is uneven or uneven, the original quality is impaired. Therefore, it is very important to use a light diffuser for uniformly emitting light from the light source. In addition, liquid crystal display devices have a strong demand for lightness, shortness, and small size due to the increasing tendency to provide portable performance found in mobile phones and digital cameras. Therefore, the surface light source device, the light diffuser to be mounted, and the peripheral optical members thereof are strongly required to be thin and save members. Furthermore, it has always required physical properties for high brightness.
For example, in a direct backlight, a light diffuser is used in order to prevent the brightness from becoming bright near the light source. However, among them, the conventional light diffuser has the following problems. First, in the type in which a diffusing agent made of pigment or resin beads is internally added to the matrix resin, uniform light emission is not achieved unless the distance between the light diffuser and the light source is increased to some extent in order to achieve uniform diffusion. When the surface light source device itself is to be made thinner, it is better to shorten the distance, but there is a limit to shortening the distance in consideration of uniform light emission. That is, there was a limit to thinning. Further, even if the diffusion performance is improved by matching the diffusing agent and the matrix, the light transmittance tends to decrease and the light emission utilization efficiency tends to deteriorate.
As another type of light diffuser, the type that has been light-shielded or patterned with light-diffusing ink tends to increase the efficiency of light emission and reduce the distance to the light source compared to the light diffuser with the above-mentioned diffusing agent added. . However, due to the accuracy limit, the pattern processing is large, such as several hundreds of μm or more, and the pattern is easy to visually recognize as it is. Therefore, in order to make the pattern difficult to be visually recognized and to blur, the light diffuser added with the above diffusing agent must be used in combination, and the need for saving members cannot be satisfied. Furthermore, since printing methods such as screen printing are used for pattern processing, printing peeling, shielding ink deterioration due to ultraviolet rays, and display performance deterioration due to color temperature changes have occurred.
From the above, the conventional light diffuser has a limit to sufficiently satisfy the requirements for a surface light emitting device such as a liquid crystal display device.
In view of the above-described circumstances, the present invention not only makes uneven light emission having a nonuniform luminance distribution (or illuminance distribution) from a light source uniform, but also improves light utilization efficiency, thinning, integration, and saving. It is an object of the present invention to provide a light diffusing body that also has improved productivity by forming a member, a method for manufacturing the same, and a surface light emitting device, a display device, and a lighting device using the light diffusing body.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have formed a light diffuser containing microbubbles with a foam that is foamed by radiation energy and thermal energy. It has been found that a light diffusing body can be obtained that not only makes the light beam uniform, but also improves the light utilization efficiency, thinning, and improving productivity by integrating and reducing the number of parts. That is, the present invention employs the following configuration.

[1] A light diffusing body comprising a light diffusing portion which is made of a foam foamed by application of radiation energy and thermal energy and has a predetermined distribution pattern of bubble density.
[2] The light diffusing material according to [1], wherein a bubble occupation area ratio of the foam is distributed in a range of 65% or less.
[3] The [1] or [2], wherein the light diffusing portion has a low foaming area where the bubble occupation area ratio is 0.5% or less and a high foaming area where the bubble occupying area ratio is 1% or more. Light diffuser.
[4] Between the low foaming region and the high foaming region according to [3], bubbles are occupied from the side adjacent to the low foaming region toward the side adjacent to the high foaming region so as to connect both regions. A light diffuser comprising a middle foaming region having an area ratio that gradually increases.
[5] The light reflectance of the light diffusion part according to any one of [1] to [4] is distributed in a range of 0% to 99.5% along the bubble density distribution pattern. Characteristic light diffuser [6] A light diffuser characterized in that the light diffusion part according to any one of [1] to [5] is provided on the surface of a translucent support.
[7] The light reflection part made of the foam and having a bubble occupation area ratio of 15% or more is provided adjacent to a part of the surface of the light diffusion part, according to any one of [1] to [6] Light diffuser.
[8] The light diffuser according to any one of [1] to [7], wherein a light guide unit is provided adjacent to a part of the surface of the light diffusion unit.
[9] The light diffuser according to any one of [1] to [8], wherein a prism portion is provided adjacent to a part of the surface of the light diffusion portion.
[10] The foam reacts with an acid generator that generates an acid by the action of radiation energy or a base generator that generates a base, and decomposes or desorbs one or more low-boiling volatile substances. The light diffuser according to any one of [1] to [9], which is obtained by foaming a foamable composition containing a decomposable foamable functional group having a decomposable foamable functional group.
[11] A method for producing a light diffuser according to any one of [1] to [10], wherein an acid generator that generates an acid or a base generator that generates a base by the action of radiation energy, and an acid or A molding step using a foamable composition containing a decomposable foamable compound having a decomposable foamable functional group that reacts with a base to decompose and desorb one or more low-boiling volatile substances, and the molded body And a foaming process for imparting radiation energy and thermal energy to foam,
(A) Radiation energy applied to the molded body, (b) Thermal energy applied to the molded body, (c) Decomposable foamable functional group concentration in the molded body, (d) Acid generator in the molded body Alternatively, any one or more of the base generator concentrations have a predetermined non-uniform distribution.
[12] A surface light emitting device comprising: the light diffuser according to any one of [1] to [11]; and a light source disposed in proximity to or in contact with one surface of the light diffuser.
[13] A display device comprising the surface light-emitting device according to [12].
[14] An illumination device comprising the surface light-emitting device according to [13].

  According to the present invention, not only the uneven light emission having a non-uniform luminance distribution (or illuminance distribution) from the light source is made uniform, but also the light utilization efficiency is improved and produced by thinning, integration and member saving. It is possible to provide a light diffuser and a method for manufacturing the same, and a surface light-emitting device, a display device, and a lighting device using the light diffuser, both of which improve both the performance.

<Foaming composition>
(Type of foamable composition)
The foam constituting the light diffuser of the present invention is obtained by foaming a foamable composition by applying radiation energy and heat energy.
Specific examples of such foamable compositions include (A) a photofoamable compound that generates a gas upon irradiation with light, and (B) a combination of a photopolymerizable compound and a thermally foamable compound (Patent 3422384). No. 5, 477), (C) an acid generator that generates an acid by the action of radiation energy or a base generator that generates a base, and one or more low boiling point volatilizations by reacting with the acid or base. And a foamable composition containing a decomposable and foamable compound having a decomposable and foamable functional group for decomposing and desorbing active substances (see Japanese Patent Application Laid-Open No. 2004-2812).
In particular, the foamable composition (C) (hereinafter referred to as “composition (C)”) is preferable because the bubble diameter can be reduced to 10 μm or less and the bubble distribution pattern can be precisely controlled over a wide range.

The composition (C) is a composition that develops foamability by the action of radiation energy and thermal energy. The foamable composition contains at least the following two components.
One of them is an acid generator that generates an acid by the action of radiation energy or a base generator that generates a base. The other is a decomposable and foamable compound that reacts with the generated acid or base to decompose and desorb one or more low-boiling volatile compounds.

(Acid generator and base generator)
The acid generator or base generator used in the composition (C) is generally called a chemically amplified photoresist, a photoacid generator or a photobase generator that is used for photocationic polymerization, etc. Can be used.

As a suitable photoacid generator for the composition (C),
(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,
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 suitable photobase generator for the composition (C),
(1) Oxime ester compounds (2) Ammonium compounds (3) Benzoin compounds (4) Dimethoxybenzylurethane compounds (5) Orthonitrobenzylurethane compounds Generates 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 light energy activated by the photoacid generator or photobase generator. For example, examples of photosensitizers for onium salt compounds include acridine yellow, benzoflavin, and acridine orange.

  In order to minimize the amount of addition of the acid generator or base generator and the light energy while generating the necessary acid, an acid proliferator or base proliferator (K. Ichimura et al., Chemistry Letters, 551- 552 (1995), JP-A-8-248561 and JP-A-2000-3302700) can be used together with an acid generator or a base generator. 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)
The decomposition foamable compound (hereinafter abbreviated as a decomposable compound) used in the composition (C) reacts with an acid or a base to decompose and desorb one or more low boiling point volatile substances (low boiling point volatile compounds). It is a compound.
The low boiling point means having a boiling point at which gasification is possible at the time of foaming, that is, a boiling point lower than the temperature at the time of foaming. The boiling point of the low-boiling volatile substance is usually 100 ° C. or lower, preferably 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.

The decomposable compound must be previously introduced with a degradable functional group capable of generating a low boiling point volatile substance.
Among the decomposable functional groups, those that react with acid include tert-butyloxy group represented by the structural formula of -O-tBu, tert-butyloxycarbonyl group represented by the structural formula of -CO-O-tBu,- Examples thereof include a tert-butyl carbonate group represented by the structural formula of O-CO-O-tBu, a keto acid, and a keto acid ester group. At this time, -tBu represents a -C (CH _{3) 3.} By reacting with an acid, tert-butyloxy and tert-butyloxycarbonyl groups are isobutene gas, tert-butyl carbonate groups are isobutene gas and carbon dioxide, keto acid sites are carbon dioxide, keto acid esters such as tert-keto acid tert acid The butyloxy group generates carbon dioxide and isobutene gas.
Examples of those that react with the base include urethane groups and carbonate groups. Reacting with a base, the urethane group and carbonate group generate carbon dioxide gas.

The form of the decomposable compound may be any of a monomer, an oligomer, and a polymer compound (polymer). Degradable compounds can be classified into the following compound groups.
(1) Non-curable low molecular weight degradable compound group (2) Curable low molecular weight degradable compound group (3) High molecular weight degradable compound group

The non-curable low molecular weight decomposable compound group (1) is a low molecular weight degradable compound group that does not cause a polymerization reaction even when radiation energy is applied. The curable low molecular weight decomposable compound group (2) is a compound group that cures by causing a polymerization reaction by application of radiation energy, and includes a polymerizable group such as a vinyl group. The polymer-based decomposable compound group (3) is a polymer compound (polymer) that is already a polymer.
The decomposable compound group may be used alone or in combination of two or more different types. When the curable low molecular weight decomposable compound group (2) or the high molecular weight degradable compound group (3) is used, it is easy to form uniform microbubbles and has a superior strength. It is possible and preferable. Specific examples of the decomposable compound are listed below, but are not limited to those exemplified.

(1) -a, non-curing low molecular weight degradable compound group (acid decomposable)
1-tert-butoxy-2-ethoxyethane,
2- (tert-butoxycarbonyloxy) naphthalene,
N- (tert-butoxycarbonyloxy) phthalimide,
2,1-bis [p- (tert-butoxycarbonyloxy) phenyl] propane and the like (1) -b, non-curing low molecular weight degradable compounds (base degradability)
N- (9-fluorenylmethoxycarbonyl) piperidine, etc.

(2) -a, a curable low molecular weight degradable compound group (acid decomposable)
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 acroyl acetate,
N- (tert-butoxycarbonyloxy) maleimide such as tert-butylmethacloyl acetate

(2) -b, a curable low molecular weight degradable compound group (base degradability)
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, polymer-based degradable compound group (acid-decomposable)
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, etc.

(3) -b, polymeric degradable compound group (base degradability)
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],

  Organic polymer compounds such as polyethers, polyamides, polyesters, polyimides, polyvinyl alcohols and dendrimers into which degradable functional groups have been introduced can also be used as acid-decomposable or base-decomposable polymer compounds. Furthermore, an acid-decomposable or base-decomposable polymer compound in which a degradable functional group is introduced into an inorganic compound such as silica can also be used. 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.

In order to increase the water resistance of the foam, it is also possible to use a compound in which a decomposition foamable functional group is introduced into a compound containing at least one kind of hydrophobic functional group. The hydrophobic functional group 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.
However, since the decomposable 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, the decomposable compound is decomposed and foamed into a hydrophilic functional group. A composite compound comprising a degradable unit into which a functional group is introduced and a hydrophobic unit containing a hydrophobic functional group is preferred. In particular, a vinyl copolymer compound is preferable.
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, acetic acid A vinyl compound group, a vinyl chloride compound group, etc. are mentioned.

Specific examples of the decomposable compound comprising a composite compound of the decomposable unit and the hydrophobic unit are shown below.
tert-butyl acrylate / methyl acrylate copolymer,
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.

  Moreover, the decomposable unit and the hydrophobic unit in the decomposable compound can be used singly or in combination of two or more. The form of copolymerization can take any form such as random copolymerization, block copolymerization, and graft copolymerization. The copolymerization ratio of the hydrophobic unit is preferably 5 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, 20 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, the foamable composition is decomposed into a low-hygroscopic compound having an equilibrium water absorption of less than 10% measured by the JISK7209D method in an environmental atmosphere at a temperature of 30 ° C. and a relative humidity of 60%. A compound into which a group is introduced 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 composed of 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 to 0 / 100 is preferable.

Specific examples of the decomposable compound comprising a combination of a high hygroscopic compound and a low hygroscopic compound are shown below.
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.

  Furthermore, a decomposable and foamable functional group may be introduced into a low hygroscopic polymer material selected from the group consisting of polyester, polyimide, polyvinyl acetate, polyvinyl chloride, 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.

(Other resins)
In the composition (C), in addition to the acid generator or base generator and the decomposable foamable compound, it may be necessary to mix a general resin serving as a skeleton of the molded body. That is, in the case of using a non-curable low molecular weight decomposable compound group, it cannot be molded alone, so it is necessary to use it mixed with the following commonly used resins. A general resin may be either compatible or incompatible when mixed with a decomposable compound.
General 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. Of the decomposable foaming compounds, the curable low molecular weight decomposable compound group and the high molecular degradable compound group may be used singly or in combination with the generally used resins.

Whether or not the above general resin is used, other unsaturated organic compounds that are cured by radiation energy can 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. For example, such materials are used in JP-A-8-17257 and JP-A-9-102230.
Specific examples of the combination 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 Acrylate, 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, disic 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 Ethylene 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.

  Furthermore, as part or all of the combined active energy ray-curable unsaturated organic compound, an active energy ray-curable resin having a molecular weight of about 400 to 5000 having a (meth) acryloyl group at the molecular chain end 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.

(Additive)
The foamable composition used in the present invention can contain additives other than the acid generator or base generator and the decomposable compound, if necessary. 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 agents, UV absorbers, optical brighteners, anti-slip agents, antistatic agents, anti-blocking agents, anti-fogging agents, light stabilizers, lubricants, softeners, colored dyes, other stabilizers, etc. May be. By using additives, improvements in moldability, foamability, optical physical properties (especially in the case of white pigments), electrical and magnetic properties (especially in the case of conductive particles such as carbon) 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 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 can be used alone or in combination of two or more.

  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 used as the softening agent is not particularly limited as long as it is a mono- or polyester having a structure composed of an alcohol and a carboxylic acid, and even a compound having a hydroxyl group and a carbonyl group terminal in the molecule is blocked in the form of an ester group. It may be a compound. 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.

(Light scattering fine particles)
Light-scattering fine particles may be supplementarily added to the foamable composition such as the composition (C) in order to improve luminance and suppress luminance unevenness. Examples of the light scattering fine particles include acrylic, styrene-acrylic, and polyethylene organic crosslinked polymer beads, silicon beads, and hollow particles. Further, the light scattering fine particles may be phase-separated on a nanoscale, and in that case, the effect of miniaturizing the bubbles formed from the foamable composition and increasing the number density can be obtained.

  The foamable composition such as the composition (C) 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.

<Method for producing foam>
The foam constituting the light diffuser of the present invention is a foam obtained by imparting radiation energy and thermal energy to the foamable composition. The manufacturing method which manufactures a foam from a foamable composition is equipped with the shaping | molding process which makes a foamable composition a molded object, and the foaming process which provides a radiation energy and a thermal energy to the said molded object, and makes it foam.

(Molding process)
The molding step of the foamable composition is a step of molding the foamable composition into a molded body having a desired shape. As a shape of a molded object, a sheet-like thing (a film form is included) is preferable. The sheet-like material may be an independent sheet that does not use a support or a sheet layer that is in close contact with the support.
The molding step in the present invention is a step for determining the shape. The molded body at the stage of the molding process may be a fluid instead of a solid. For example, a liquid material poured into a specific mold is also included in the molded body in the present invention.

As a method for forming the sheet-like material, methods described in JP-A No. 2004-2812, JP-A Nos. 2005-54176, and 2005-55883 can be used. In general, melt extrusion molding, injection molding, coating molding, and press molding are preferable. In particular, coating molding is preferable because the light diffuser itself can be thinned and can be easily laminated on the surface of the translucent resin support.
Moreover, a batch type or a continuous type may be used. When the foamable composition is a solution, a solvent drying treatment may be added. It is also possible to laminate a plurality of molded bodies.

  In the case of coating molding, after applying the foamable composition to the support using a coating head, if the foamable composition is a solution diluted with a solvent or the like, the solvent content is removed with a dryer, A sheet layer made of a foamable composition is obtained on the 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. .

Specific 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, or an engineering 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. At this time, the support is preferably a translucent support, and more preferably a translucent resin sheet. The light-transmitting light transmission property is not limited as long as it is appropriately adjusted by use, but the light transmittance in the visible light region is preferably 90% or more.
In addition, if an optical functional sheet such as a light reflecting sheet, a light guide sheet (or a light guide plate), or a prism sheet is used as a support, it is easy to integrate the light diffusion portion made of a foam and these functional sheets. It can be carried out.

  In the case of extrusion molding, a general extrusion molding method using a screw-like extrusion shaft, a ram extrusion molding method using a piston-like extrusion shaft, and the like can be mentioned. For example, a foamable composition extruded from an extruder can be extruded from a die to obtain a sheet-like material via a roll or the like.

Depending on the composition, the foamable composition may be decomposed by heating at, for example, 150 ° C. or higher. Therefore, care must be taken not to lose the net foaming performance prior to the foaming step.
For example, in extrusion molding, when foaming performance is impaired when heated to the melt viscosity of the resin, a solution casting method in which a foamable composition solution is prepared using a solvent in the same manner as coating molding, and molding is performed at room temperature. You can also take the following method.

(Foaming process)
The foaming step is a step of imparting radiation energy and heat energy to the molded body to cause foaming. The foaming process includes a radiation irradiation process for irradiating the molded body with radiation and a heating process for heating the molded body. When only fine bubbles are formed, the heating process is preferably performed after the radiation irradiation process. A stable foam can be formed by sequentially performing the radiation irradiation step and the heating step. This is because the foaming mechanism of the composition (c) is a mechanism in which an acid or base is generated by radiation, and the decomposable and foamable compound is decomposed and foamed by the acid or base and heating. The composition (c) generates a large number of bubble nuclei at a relatively low temperature, and when the temperature is further increased to grow the bubbles, fine bubbles can be made uniform. However, if the temperature is raised from the beginning and radiation is applied to it, large bubbles are formed.
Each step may be performed continuously or discontinuously.

(Radiation irradiation process)
The radiation used in the radiation irradiation step is preferably ionizing radiation such as electron beam, ultraviolet ray, visible light, and γ-ray. In these, it is especially preferable to use an electron beam or an ultraviolet-ray.

  When irradiating with an electron beam, in order to obtain a sufficient transmission power, an electron beam accelerator having an acceleration voltage of 30 to 1000 kV, more preferably 30 to 300 kV is used, and the absorbed dose of one pass is controlled to 0.5 to 20 Mrad. It is preferable (1 rad = 0.01 Gy). When the acceleration voltage or the electron beam irradiation amount 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. On the other hand, if it is larger than this range, not only the energy efficiency is deteriorated, but also 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 low. It can be unsatisfactory.

  As the electron beam accelerator, for example, an electro curtain system, a scanning type, a double scanning type, or the like can be used. When the electron beam is irradiated, if the oxygen concentration in the irradiation atmosphere is high, generation of acid or base and / or curing of the curable decomposable compound may be hindered. For this reason, it is preferable to replace the air in the irradiation atmosphere with an inert gas such as nitrogen, helium or carbon dioxide. 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.

  When irradiating with ultraviolet rays, an ultraviolet lamp generally used in the semiconductor / photoresist field, the ultraviolet curing field, or the like 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 accurately control the position of the bubble distribution, it is preferable to use parallel light as the radiation. For the 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 can 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, a light emission wavelength that overlaps the maximum absorption wavelength or the maximum absorption wavelength in the photosensitive wavelength region of these generators is more preferable because the generation efficiency increases. The energy irradiation intensity of ultraviolet rays is appropriately determined depending on the foamable composition.

When an ultraviolet lamp having a high irradiation intensity typified by various mercury lamps and metal halide lamps is used, productivity can be improved, and the irradiation intensity (lamp output) is preferably 30 W / cm or more. 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 using an excimer lamp or excimer laser, 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.

(Heating process)
Although there is no restriction | limiting in particular in the heater which can be used at a heating process, What can be heated by contact heating, induction heating, resistance heating, dielectric heating (and microwave heating), infrared heating, etc. can be illustrated. Specific 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. It is done. In contact heating in which a heating body is brought into contact with the molded body and heated, a heating body such as a metal block, a metal plate, or a metal roll can be used. In contact heating, heating may be performed while applying pressure. In this case, a hot press machine used for press molding can be used.

In the case of dielectric heating and infrared heating, since the internal heating method directly heats the inside of the material, it is preferable to perform uniform heating instantaneously compared to an external heating method such as a hot air dryer. In the case of dielectric heating, high-frequency energy having 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 having a frequency of 300 MHz to 300 GHz (wavelength: 1 m to 1 mm), but 2450 MHz and 915 MHz (same as a microwave oven) are often used.
In the case of infrared heating, an electromagnetic wave having a wavelength of 0.76 to 1000 μm in the infrared region 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, it is preferable to use a wavelength band of 1.5 to 25 μm, more preferably 2 to 15 μm. it can.

  Furthermore, a heating method used in a general thermal recording printer can also be used. For example, a thermal head that generates heat when an electric current is passed and laser thermal transfer can be used, and a foam having the same pattern can be obtained by writing heat. When obtaining high definition or high resolution, laser thermal transfer is preferable to thermal heads.

<Non-uniform foaming>
The foam used in the present invention is a non-uniform foam whose bubble occupation area ratio varies depending on the position in order to provide a function as a light diffuser. Bubble occupying area ratio in the present invention and (%) is an index for evaluating the cell density, the foam from the cross section of the observation image by the image analysis, when the maximum bubble diameter of less than 1μm in the cross-section of 100 [mu] m ² When the maximum bubble diameter is 1 μm or more and 5 μm, it is the ratio of the area occupied by the bubble cross section in the cross section of 2500 μm ² and when the maximum bubble diameter is 5 μm or more, the cross section of 10000 μm ² .
The distribution of the desired bubble occupation area ratio (hereinafter sometimes referred to as “bubble distribution”) is (a) radiation energy applied to the molded body, (b) thermal energy applied to the molded body, (c) Any one or more of the concentration of the decomposable and foaming functional group in the molded body and (d) the concentration of the acid generator or base generator in the molded body is obtained by a predetermined non-uniform distribution.

(Non-uniform radiation energy)
A method of setting the radiation energy applied to the molded body to a predetermined nonuniform distribution will be described.
The distribution of radiation energy can be controlled by adjusting the irradiation energy intensity by using a photomask for electron beam or ultraviolet irradiation. Further, the irradiation energy distribution can be given by a drawing apparatus using an ultraviolet laser or an electron beam.
There are various types of photomask patterns, such as a gradient pattern in which the transmission of radiation energy changes continuously, a gradation pattern that changes stepwise at a certain interval, and a division pattern that is divided according to the presence or absence of transparency. These are designed and used suitable for the desired bubble distribution pattern.
As the material of the photomask, a chrome mask, a metal mask, a silver salt glass mask, a silver salt film, a screen mask, etc. can be used. A mask in which glass is ion-etched, a mask in which interference fringes of a planar lens having a condensing function are drawn with an electron beam, and the like can be used. 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.

When irradiation is performed using a photomask, methods such as contact irradiation and projection irradiation can be employed. 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 (http: / /www.kuranami.co.jp/toku_guide01.htm). 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 ultrahigh pressure mercury lamp, a mercury xenon lamp, a sodium lamp, and a Y-ray lamp. After a photomask is brought into close contact with a molded body made of a foamable composition, partial foaming having a line and space pattern with a width of several μm is obtained by irradiating parallel ultraviolet light and foaming by heating. The edge at that time can also be clearly transferred. Further, a method of irradiating radiation that generates interference fringes is also possible.

(Non-uniform thermal energy)
In order to obtain a predetermined non-uniform distribution of heat energy applied to the molded body, heat treatment is performed in the heating process so as to generate a heat energy intensity distribution. Specifically, it is preferable to control by the heating temperature. For example, there is a method of heating using a thermal recording printer so that the applied thermal energy has a continuous gradient.

(Non-uniform foaming composition)
The concentration of the decomposable foamable functional group in the molded body and / or the concentration distribution of the acid generator (or base generator) in the molded body is preferably adjusted by using a plurality of foamable compositions having different compositions. .
For example, the foaming composition from which the mixing ratio of a decomposable compound and a photo-acid generator differs can be mentioned by apply | coating and shape | molding on a support body in parallel.

(3D bubble distribution)
Each of the above-mentioned methods of non-uniformity of radiation energy, non-uniformity of thermal energy, and non-uniformity of the foamable composition as methods for non-uniform bubble distribution are independent of each other. The bubble distribution can be affected. Therefore, by combining two or more of these methods, the direction of the bubble distribution in the same foam can be controlled in three dimensions. Of course, it is also possible to control the direction of bubble distribution in three dimensions by utilizing only one of these methods. For example, a foam having a three-dimensionally patterned cell distribution can be obtained by heating and foaming a plurality of foamed composition molded bodies each irradiated with radiation in different patterns.

(Bubble diameter)
The bubble distribution can be controlled by the above method. In this case, the bubble diameter can be changed together with the bubble density evaluated by the bubble occupation area ratio. When the bubble density increases, the bubble diameter also increases, and when the bubble density decreases, the bubble diameter also tends to decrease.
However, it is also possible to change the cell density intensively by adjusting the composition of the foamable composition. For example, by increasing the glass transition point of the foamable composition, it is possible to mainly change the bubble density while keeping the bubble diameter relatively small. Further, by using a three-dimensional crosslinkable foamable composition, it is possible to mainly change the bubble density while keeping the bubble diameter relatively small. That is, the bubble diameter and the bubble number density can be controlled by adjusting the composition of the foamable composition.
The bubbles in the foam of the present invention are preferably constituted with a bubble diameter of 20 μm or less, and more preferably constituted with a bubble diameter of 10 μm or less. Furthermore, it is more preferably configured with a bubble diameter of 1 μm or less, which is close to the wavelength of a light source generally used for liquid crystal display devices and lighting devices. By setting the thickness to 20 μm or less, not only the optical function can be sufficiently exhibited, but also the light diffuser itself can be thinned.

<Light diffuser>
The light diffusing body of the present invention includes at least a light diffusing portion, and is formed by appropriately combining a light reflecting portion, a light guide portion, and a prism portion as necessary. In the light diffusing portion of the present invention, the bubble occupation area ratio has a predetermined distribution pattern. Preferably, it has a low foaming area of 0.5% or less and a high foaming area of 1% or more. A light diffuser in which the light reflectance or light transmittance is distributed along with the distribution pattern can be obtained. Specifically, the lower the bubble occupation area ratio, the lower the light reflectance (or higher light transmittance), and the higher the bubble occupation area ratio, the higher the light reflectance (or lower light transmittance). For example, in the case of a direct type backlight, it is desirable for luminance uniformity that the light reflectance of the light diffuser is the highest directly above the light source and gradually or gradually decreases as the distance from the light source increases. In order to provide such optical physical properties by foaming, the bubble occupation area ratio is the highest directly above the light source, and may be lowered stepwise or gradually as the distance from the light source increases.
The bubble occupation area ratio in the low foaming region may be 0%. If the area occupied by bubbles in the low foam area is lowered, the amount of change in the area occupied by bubbles in the entire light diffusing section can be increased, so the brightness distribution emitted from the light diffusing section can be controlled to make the brightness uniform. Becomes easy.
The area occupied by bubbles in the highly foamed region is more preferably 15% (equivalent to an expansion ratio of about 1.1 times) or more, and more preferably 30% (equivalent to an expansion ratio of about 1.2 times) or more. preferable. Increasing the area occupied by bubbles in the high-foaming region can increase the amount of change in the area occupied by bubbles in the entire light diffusing section, so the distribution of light emitted from the light guide section can be fully controlled and uniformized. Easy to do. However, even in the highly foamed region, it is preferable to have a bubble occupation area ratio of 65% or less (corresponding to a foaming ratio of about 2 times) or less. Thereby, it becomes easy to maintain the intensity | strength of a light-diffusion part.

Between the low foaming area and the high foaming area, the middle foaming area where the bubble occupation area ratio gradually increases from the side adjacent to the low foaming area toward the side adjacent to the high foaming area so as to connect between the two areas. It is preferable to provide. That is, it is preferable that the light diffuser of the present invention is configured such that the bubble occupation area ratio gradually increases from the low foaming region toward the high foaming region.
A plurality of low foaming regions and high foaming regions may be alternately arranged. For example, this is effective in a direct type backlight having a plurality of light sources and an edge type backlight in which a plurality of bright line dark lines are generated. The direct type backlight including a plurality of light sources is preferably arranged in order of a high foaming region, a low foaming region, and a high foaming region from one light source to the other light source.
It is preferable that the bubble distribution in each foaming region is uniform, but a configuration in which dot-like portions composed of a group of fine bubbles are interspersed is also possible. When dot-like portions are scattered, a low-foaming region is obtained by reducing the dot density, and a high-foaming region is obtained by increasing the dot density. In addition, it is preferable that the inside of each dot-shaped part is a high bubble occupation area rate to the same extent as a light reflecting part to be described later.

When the light diffuser of the present invention is used, the high foam area of the light diffusing portion is appropriately disposed at a location near the light source or near the bright line, and the low foam region is disposed at a position away from the light source or near the dark line. . In other words, the area closest to the light source has the largest occupied area ratio and is used in such an arrangement that the bubble occupied area ratio is minimized at the farthest place. Further, in a configuration in which dot-shaped portions composed of a group of fine bubbles are scattered, the number density of the dots is used in an arrangement in which the closer to the light source is denser and the further away it is, the sparser.
The bubbles in the light diffusion portion are preferably configured with a bubble diameter in the range of 0.1 to 20 μm, and more preferably configured with a bubble diameter in the range of 0.1 to 10 μm. By setting the bubble diameter to be equal to or less than the wavelength of visible light, bubbles and dot-like portions are hardly visible. Therefore, it is not necessary to use other light diffusers together.
The specific bubble distribution in the light diffusing unit is set with parameters related to the shape and position of the light source or bright line dark line, the area of the light diffuser, etc., and optical simulation software and ray tracing that take geometric optics, Mie scattering, and multiple scattering into account. It can be optimized by making full use of the law.

The light reflection part of the present invention has a bubble occupation area ratio of 15% or more, preferably 30% or more. If the bubble occupation area ratio of the light reflecting portion is increased, the light reflectance can be increased. However, even the light reflecting portion preferably has a bubble occupation area ratio of 65% or less. Thereby, it becomes easy to maintain the intensity | strength of a light reflection part.
The bubble distribution in the light reflecting portion is preferably uniform in order to prevent uneven light reflection. Moreover, it is preferable that the bubble in a light reflection part is comprised with the bubble diameter of the range of 0.1-10 micrometers, and it is more preferable that it is comprised with the bubble diameter of the range of 0.2-1 micrometer.
When the bubble occupation area ratio is in the range of 30 to 65% and the bubble diameter is in the range of 0.2 to 1 μm, the total light reflectance can be 80% or more with a thickness of 50 μm or less.

  The prism portion of the present invention is configured as a layer in which a V-groove is engraved on one surface so as to exhibit a prism function. The prism portion does not require air bubbles and is formed of a general resin. However, it is also possible to use the foamable composition without foaming.

  Hereinafter, embodiments of the light guide according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

FIG. 1 is a cross-sectional view showing a first embodiment (light diffuser) of the present invention. The light diffuser of the present embodiment is composed of only the light diffusing unit 10. The light diffusing unit 10 is made of a foam in which a large number of bubbles B are formed in the matrix M, and has a bubble distribution pattern in which the bubble occupation area ratio gradually decreases in the direction of the end face away from the central position close to the light source 200. That is, the vicinity of the end surface is the low foaming region 13, the central position is the high foaming region 14, and the space between the low foaming region 13 and the high foaming region 14 is the medium foaming region 15. In addition, the bubble diameter may be gradually reduced from the center to the end face together with the bubble occupation area ratio.
The light diffuser of the present embodiment is provided with such a bubble distribution pattern, so that the biased incident light having a nonuniform luminance distribution with respect to the incident surface 11 is emitted from the emission surface 16 as substantially uniform light. It has become.

FIG. 2 is an example of a method for manufacturing the light guide of FIG. As shown in FIG. 2, a matrix 1 is formed by irradiating a molded body 1 in which a foamable composition is preliminarily formed using a photomask 2 whose energy permeability is a gradation pattern, with radiation having a gradation pattern. It is possible to obtain the light diffusing unit 10 having the bubbles B with a gradient distribution in M.
FIG. 3 is another example of a method for manufacturing the light diffuser of FIG. As shown in FIG. 3, when the photomask 2 provided with the triangular opening 3 is slid on the molded body 1 during radiation irradiation, the irradiation time is shorter when the triangular apex side 3a slides, The bottom side 3b has a long irradiation time. It is obvious that the same effect can be obtained by sliding the molded body 1. With this photomask shape, an inclined bubble distribution pattern from the center position to the end face of the light diffuser in FIG. 1 is obtained. That is, by using a photomask in which another triangular opening is symmetrically arranged with respect to the opening 3a, the light diffusion portion 10 having an inclined bubble distribution can be obtained. In this way, a distribution of radiation energy can be created and a bubble distribution pattern can be obtained in the same manner as when using a photomask having a gradation pattern.

FIG. 4 is a cross-sectional view showing a second embodiment (light diffuser) of the present invention. The light diffusing body of the present embodiment is also composed of only the light diffusing unit 10. The light diffusing portion 10 is made of a foam in which a large number of dot-like portions D are formed in the matrix M, and the distribution of the dot-like portions D gradually decreases in the direction of the end face away from the center position close to the light source 200. Since each dot-like portion D is an aggregate of a large number of bubbles B, when the entire light diffusion portion 10 is viewed from the viewpoint of bubble distribution, the bubble occupation area ratio gradually decreases from the central position close to the light source 200 toward the end face direction. It has a bubble distribution pattern. That is, the vicinity of the end surface is the low foaming region 13, the central position is the high foaming region 14, and the space between the low foaming region 13 and the high foaming region 14 is the medium foaming region 15.
The light diffuser of the present embodiment is provided with such a bubble distribution pattern, so that substantially uniform light is emitted from the entire emission surface 16 as biased incident light having a non-uniform luminance distribution with respect to the incident surface 11. It has become so.

FIG. 5 is a cross-sectional view showing a third embodiment (light diffuser) of the present invention. The light diffuser of this embodiment is also composed of only the light diffuser 10, but the light diffuser 10 is a laminate of foam 10a and transparent resin 10b. If it does in this way, when foam 10a is very thin, transparent resin 10b functions as a support.
The foam 10a is substantially the same as the light diffusion portion 10 of the first embodiment. That is, it is made of a foam in which a large number of bubbles B are formed in the matrix M, and has a bubble distribution pattern in which the bubble occupation area ratio gradually decreases in the end face direction away from the central position near the light source 200.
One transparent resin 10b does not have bubbles. Examples of the material of the transparent resin 10b include acrylic resins such as polymethyl methacrylate, methacrylic resins, cyclic olefin resins such as norbornene, polycarbonate resins, celluloses such as cellulose triacetate, styrene resins, and blends of two or more of these materials. The mixed resin is preferable.
In this embodiment, the vicinity of the end surface is the low foaming region 13, the central position is the high foaming region 14, and the space between the low foaming region 13 and the high foaming region 14 is the medium foaming region 15. As with the light diffusing unit 10 of the first embodiment, the bubble diameter may be gradually reduced along with the bubble occupation area ratio in the direction of the end face away from the central position near the light source 200.
The light diffuser of the present embodiment is provided with such a bubble distribution pattern, so that biased incident light having a non-uniform luminance distribution with respect to the incident surface 11 can be obtained from the entire emission surface 16 (upper surface of the transparent resin 10b). A substantially uniform light is emitted.

The light diffuser of FIG. 5 can be manufactured by bonding the foam 10a obtained in the same manner as the light guide of the first embodiment and the transparent resin 10b. Moreover, as shown in FIG. 6, it can manufacture using an in-mold injection molding method.
As shown in FIG. 6, in the in-mold injection molding method, first, a roll-wrapped transparent resin sheet 4 is passed between molds 5a and 5b for injection molding (step (1)). Next, the transparent resin sheet 4 is sandwiched between the molds 5a and 5b, the foamable composition 6 is injected and filled into the molds 5a and 5b, and the transparent resin sheet 4 and the foamable resin composition are integrated. (Step (2)). Then, after the filled foamable composition 6 is solidified, the molds 5a and 5b are removed (step (3)). Then, the transparent resin sheet 4 is sent (step (4)). Hereinafter, by repeating steps (1) to (4), a large number of laminates in which the transparent resin sheet 4 and the foamable resin composition are integrated can be obtained. The light diffuser shown in FIG. 5 can be obtained by applying radiation energy and thermal energy to the laminate to cause foaming in a predetermined pattern. In addition, before or after a foaming process, it is necessary to cut the laminated body connected in roll shape separately.

FIG. 7 is a sectional view showing a fourth embodiment (light diffuser) of the present invention. The light diffuser of this embodiment is also composed of only the light diffuser 10, but the light diffuser 10 is a laminate of foam 10a and transparent resin 10b.
The foam 10a is substantially the same as the light diffusion part 10 of the second embodiment. That is, the foam 10a is made of a foam in which a large number of dot-like portions D are formed in the matrix M, and the distribution of the dot-like portions D gradually decreases in the direction of the end face away from the central position close to the light source 200. Yes. Each dot-like portion D is an aggregate of a large number of bubbles B. One transparent resin 10b does not have bubbles. As the material of the transparent resin 10b, the same material as the transparent resin 10b of the third embodiment can be used. When the entire light diffusing unit 10 is viewed from the viewpoint of bubble distribution, the bubble distribution pattern is such that the bubble occupation area ratio gradually decreases in the direction of the end face away from the central position close to the light source 200. Also in the present embodiment, the vicinity of the end surface is the low foaming region 13, the central position is the high foaming region 14, and the space between the low foaming region 13 and the high foaming region 14 is the medium foaming region 15. As with the light diffusing unit 10 of the first embodiment, the bubble diameter may be gradually reduced along with the bubble occupation area ratio in the direction of the end face away from the central position near the light source 200. The light diffuser of the present embodiment is provided with such a bubble distribution pattern, so that biased incident light having a non-uniform luminance distribution with respect to the incident surface 11 can be obtained from the entire emission surface 16 (upper surface of the transparent resin 10b). A substantially uniform light is emitted.

  The light diffuser of FIG. 7 can be manufactured by bonding the foam 10a obtained in the same manner as the light diffuser of the second embodiment and the transparent resin 10b. Moreover, it can manufacture using the in-mold injection molding method similarly to 3rd Embodiment.

FIG. 8 is a sectional view showing a fifth embodiment (light diffuser) of the present invention. The light diffusing body of the present embodiment includes a light diffusing portion 10 and a light reflecting portion 20 provided in contact with the four end faces thereof. As the light diffusing unit 10 in FIG. 8, the light diffusing unit 10 in the first to fourth embodiments can be appropriately employed. By providing the light reflecting portion 20 around the end face of the light diffusing portion 10, light leakage from the end face can be prevented and light utilization efficiency can be increased.
As a manufacturing method of the light diffuser of the present embodiment, a plate-shaped molded product of the foamable composition is irradiated with radiation by covering a region where the light diffusion portion 10 is to be formed with a photomask (inclined pattern or the like), The method of heating and foaming after that is mentioned. That is, the part through the photomask becomes a light diffusion part 10 having a bubble distribution pattern with the amount of radiation energy controlled, and the surrounding area protruding from the photomask is irradiated with a uniform and sufficient amount of radiation to produce a large number of fine bubbles. It becomes the light reflection part 20 which made the group exist uniformly with high density. Alternatively, in a photomask substrate (for example, quartz glass) having a size equal to or larger than the plate-shaped molding of the foamable composition, a radiation energy distribution pattern is created in an area where the light diffusion portion 10 is to be formed, and the area other than that area is highly foamed. The light diffusing unit 10 can also be obtained by setting the light transmittance so that the amount of radiant energy necessary for the transmission can be transmitted.

FIG. 9 is a sectional view showing a sixth embodiment (light diffuser) of the present invention. The light diffusing body of the present embodiment includes a light diffusing unit 10 and a light guide unit 40 provided in contact with the light source side surface. As the light diffusing unit 10 in FIG. 9, the light diffusing unit 10 in the first to fourth embodiments can be appropriately employed. By providing the light guide unit 40, the incident light having a nonuniform luminance distribution with respect to the incident surface 11 is guided, and the unevenness of the luminance distribution is softened in advance, thereby further improving the luminance uniformity. Can be enhanced well. Although the light source 200 is an embodiment arranged outside the light guide unit, the light source 200 may be an embodiment fitted inside the light guide unit.
As a manufacturing method of the light diffuser of the present embodiment, a plate-shaped molded product of a foamable composition is prepared, irradiated with radiation through a photomask (inclined pattern or the like), and then the light guide unit together with the light guide unit 40. For example, a stamper or a mold that does not change the shape of 40 can be combined and integrated, and heated and foamed simultaneously with the integration. That is, the light diffuser of the present embodiment in which the light diffusing unit 10 having a bubble distribution pattern in contact with the light guide unit 40 is controlled in the portion through the photomask. Integration and foaming may not be simultaneous. That is, in the manufacturing method in which the plate-like molded product of the foamable composition and the light guide unit 40 are integrated and then irradiated with radiation through a photomask (inclined pattern or the like) and heated and foamed in the same manner. A diffuser is obtained.
Further, the in-mold injection molding method described in the third embodiment can be used. In this case, a light guide sheet or a light guide plate may be used instead of the transparent resin sheet 4 in FIG.

FIG. 10 is a sectional view showing a seventh embodiment (light diffuser) of the present invention. The light diffusing body of the present embodiment includes a light diffusing unit 10 and a prism unit 30 provided in contact with the surface facing the light source. As the light diffusing unit 10, the light diffusing unit 10 in the first to fourth embodiments can be appropriately employed.
As a method of manufacturing the light diffuser of the present embodiment, a translucent resin is molded in a mold in which V-grooves to be prisms are engraved in advance, and then a photomask (inclined pattern) is taken out without removing it from the mold. ), A plate-like molded product of a foamable composition irradiated with light is added, heated and pressurized, and foamed simultaneously with lamination to produce. When taken out from the mold after foaming, a light diffuser in which a light diffusion part having a bubble distribution pattern and a prism layer of a V-groove are integrated on the surface thereof is obtained.
Further, the in-mold injection molding method described in the third embodiment can be used. In this case, a prism sheet may be used instead of the transparent resin sheet 4 in FIG.

The light diffuser of the present invention may be a combination of the fifth to seventh embodiments as appropriate. For example, it is good also as a structure which has the light guide part 40 in contact with the four end surfaces of the light-diffusion part 10, and the surface at the side of the light source. Moreover, it is good also as a structure which added the prism part 30 to this.
Moreover, the light guide part may be a conventional transparent light guide or a light guide made by foaming the foamed composition of the present invention (the bubble distribution may be patterned as a light guide function). The prism portion can also be used without foaming the foamed composition of the present invention.

<Surface emitting device>
The surface light-emitting device of the present invention is a direct type backlight including the light diffuser of the present invention and a light source disposed in close proximity to or in contact with the light diffuser. As the surface light-emitting device of the direct type backlight, the surface light source device 100 in the first to seventh embodiments can be representatively employed.
Further, as shown in the cross-sectional view of FIG. 11, the surface light emitting device of the present invention includes the light diffuser 10 of the present invention and a light guide plate 41 disposed in close proximity to or in contact with the light diffuser 10; In addition, the light guide plate 41 is an edge type backlight including the light source 200 on at least one side surface and the light reflecting sheet 21 on the lower surface.
As a surface light-emitting device for an edge-type backlight, a surface light-emitting device 100 shown in the cross-sectional view of FIG. 11 can be typically employed.

In the direct type backlight in the surface light emitting device of the present invention, the light diffuser of the present invention is configured to emit uneven incident light having a non-uniform luminance distribution incident from a light source disposed immediately below the light diffuser. Since the light is emitted uniformly, surface emission with high luminance uniformity can be obtained.
Further, in the edge type backlight in the surface light emitting device of the present invention, when the light scatterer of the present invention is emitted from the light guide portion or luminance unevenness (eyeball phenomenon) in the vicinity of the light source arranged at the edge. Since the luminance unevenness of the generated bright lines and dark lines is finally made uniform and emitted, surface emission with high luminance uniformity can be obtained.

As the light source 200 used in the surface light emitting device, 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. A single light source or a plurality of light sources may be used, and in the case of a plurality of light sources, various light sources may be combined.

<Example 1>
・ Single inclined foamed light diffuser (1) Sheet formation of foamable composition Degradable compounds tert-butyl acrylate (60 wt%), methyl methacrylate (30 wt%) and methyl methacrylic acid (10 wt%) 3 parts of bis (4-tert-butylphenyl) iodonium perfluorobutanesulfonate (BBI-109, manufactured by Midori Chemical Co., Ltd.) as an iodonium salt-based acid generator is mixed with 100 parts of the copolymer. An ethyl acetate solution was prepared (solid content: 25%). This solution was coated on a silicon-treated surface of a silicon PET sheet (Lumirror SP-PET-01-75BU, manufactured by Panac) using an applicator bar (Doctor blade TD type, manufactured by YOSHIMITSU SEIKI) having a coating thickness of 11
The solvent was removed by evaporation in a constant temperature dryer at 0 ° C. to obtain a colorless and transparent coating layer. This coating layer was peeled from the silicon PET sheet to obtain a foamable sheet having a thickness of 35 μm.

(2) Flat plate forming The foamable sheet prepared in the step (1) is cut into dimensions of 50 mm in length and 50 mm in width, and three of them are stacked, as shown in (a) and (b) of FIG. It was sandwiched between flat-pressed dies with smooth surfaces (dimensions: 50 mm long and 35 mm wide) and heated and pressed using a hand press machine (Mini TEST PRESS-10, manufactured by TOYOSEIKI) (pressing pressure; 6 MPa, pressing temperature: 150 ° C. for 3 minutes) ). Thereafter, as shown in FIG. 12 (c), when the pressure was returned to normal pressure and air-cooled to 40 ° C., the mold was removed to obtain a colorless and transparent foamable sheet.

(3) UV irradiation As shown in FIG. 12D, the entire surface of the foamable sheet obtained in the step (2) is covered with a quartz glass photomask (dimensions: 50 mm long, 50 mm wide). Then, it was irradiated with ultraviolet rays from above. The photomask used an inclined pattern in which the light transmittance gradually decreases gradually from 45% to 0% (measurement wavelength 254 nm) along two directions from the center position toward the opposite end faces. The changes gradually decreasing in the two directions were the same (see FIG. 2). Ultraviolet rays were irradiated using a metal halide lamp (ultraviolet curing multi-metal lamp M03-L31, manufactured by Eyegraphic Co., Ltd.) as a light source so that the irradiation dose was 2000 mJ / cm ² . The photomask was removed after the irradiation, and a colorless and transparent foamable sheet similar to that in the step (1) was obtained.

(4) Heat Foaming As shown in FIG. 12 (e), the foamable sheet irradiated with ultraviolet rays in the step (3) is sandwiched between flat pressing dies as in the step (2), and heated by a hand press. Foaming was performed (press pressure: 4 MPa, press temperature: 130 ° C. for 2 minutes). Thereafter, as shown in FIG. 12 (f), while being pressurized, cooling water was immediately circulated inside the mold and rapidly cooled to 50 ° C. Subsequently, as shown in FIG. 12 (g), when the pressure is returned to normal pressure and air-cooled to 40 ° C., the mold is removed, and a light diffuser made of foam is obtained as shown in FIG. 12 (h). It was. The obtained light diffuser was a flat sheet having a uniform thickness, and the thickness was 100 μm. A micrometer (MCD-25M manufactured by Mitutoyo) was used for thickness measurement. In addition, the sheet-like light diffuser and the light beam reflectivity became an inclined pattern that gradually and gradually decreased along two directions from the center position toward the opposite end face.

(5) Evaluation of foam structure The bubble diameter (average value of the bubble diameter) and the bubble occupation area ratio of the sheet-like light diffuser obtained in the step (4) (a cross section of 100 μm ² when the maximum bubble diameter is less than 1 μm) The ratio of the area occupied by the bubble cross section in the cross section of 2500 μm ² when the maximum bubble diameter is 1 μm or more and 5 μm, or the cross section of 10000 μm ² when the maximum bubble diameter is 5 μm or more. Calculated from the observed image.
The cross-section observation image is obtained by cleaving a sheet-like light diffuser immersed in liquid nitrogen along the direction in which the light reflectivity changes in inclination (two directions from the central position toward the opposite end face), After the metal vapor deposition treatment, it was obtained by observing with a scanning electron microscope (S-510, manufactured by Hitachi, Ltd., magnification 5000 times). Then, after the bubble and the matrix in the observation image were binarized, the bubble diameter and the bubble occupation area ratio were calculated using an image analyzer (Image Analyzer V10, manufactured by TOYOBO).
The obtained sheet-like light diffuser had an inclined distribution in which the bubble diameter and bubble occupation area ratio gradually decreased from the center position close to the light source toward the end face direction. The maximum bubble diameter was 0.4 μm. Moreover, the bubble occupation area ratio changed from 0% to 9% (0% to 57% in terms of light reflectance).

(6) Surface light emitting device and light emission evaluation The sheet-like light diffuser obtained in the step (4) is a rectangular box type lamp house (50 mm long, 50 mm wide, 50 mm wide, with one cold cathode tube arranged in the center). A surface light-emitting device serving as a direct type backlight was obtained by arranging so that no gap was formed on the upper surface having a thickness of 10 mm. At this time, the arrangement of the sheet-like light diffuser was adjusted so that the long axis direction of the cold cathode tube and the direction in which the light reflectivity of the sheet-like light diffuser changed in inclination was orthogonal. That is, the sheet-like light diffuser was disposed along the direction away from the vicinity of the light source so that the light reflectance was low (the bubble occupation area ratio was low).
The luminance uniformity was evaluated from the luminance variation calculated from the following equation.
Size of luminance variation (%) = (maximum luminance value−minimum luminance value) / average luminance value × 100
Good: Variation is less than 10%
Defect x: The variation is 10% or more. The maximum luminance value, the minimum luminance value, and the average luminance value are the luminance values measured for each division, assuming a total of 25 equal sections of 5 × 5 on the emission surface of the surface light emitting device. Based on (luminance value when the cold-cathode tube emits light stably).
The light emission utilization efficiency was evaluated from the ratio of the luminance average value when the light diffuser was installed to the luminance average value when the PMMA transparent sheet was installed without a gap on the upper surface of the lamp house.
Good ○: 70% or more
Defect x: The thickness of the surface light emitting device obtained was less than 70%, which was about 20 mm as a whole, and both the luminance uniformity and the light emission utilization efficiency were good. Furthermore, the unevenness of the luminance distribution in each section was also confirmed visually.

(7) Integration of light reflecting portions at the four-sided end surface portions of the light diffuser The photomask in the step (3) has a pattern such that the light transmittance is 100% in the width of several millimeters at the four-sided end portions of the photomask. In place of the added photomask, the steps (1) to (4) were performed to obtain a light diffuser. At that time, it was visually confirmed whether or not the light reflecting portion was integrated with the four end faces of the light diffuser.
The four-side end surfaces of the obtained sheet-like light diffuser were equipped with a light reflecting portion made of a white foam and integrated.

<Example 2>
Single-dot foamed light diffuser In step (1) of Example 1, decomposable compounds tert-butyl acrylate (60 wt%), methyl methacrylate (30 wt%) and methyl methacrylic acid (10 wt%) In place of 100 parts of the copolymer, 100 parts of a copolymer of tert-butyl methacrylate (62% by weight) and methyl methacrylate (38% by weight) was used, and instead of the applicator bar having a coating thickness of 200 μm, the coating thickness was 300 μm. A foamable sheet having a thickness of 50 μm was obtained by using an applicator bar. The obtained foamable sheet was irradiated with ultraviolet rays through a dot pattern photomask in the step (3) of Example 1 (irradiation dose 200 mJ / cm ² ). At this time, a dot pattern was used in which the dot diameter and density gradually decreased along two directions from the center position of the photomask toward the opposite end faces. Moreover, the parallel light of a Deep-UV light source was used for the ultraviolet-ray used by light irradiation. After the ultraviolet irradiation, the process (4) of Example 1 was performed in the same manner to obtain a sheet-like light diffuser. The thickness of the sheet-like light diffuser was 50 μm.
When the bubble diameter and bubble occupying area ratio of the obtained sheet-shaped light diffuser were determined in the same manner as in Example 1, the portion made of the foam had a dot-like portion extending from the central position near the light source toward the end surface. The slope distribution gradually decreased. The maximum bubble diameter in the dot-like portion was 0.4 μm, and the bubble occupation area ratio was 52% (light reflectivity was about 90%), which was almost uniform within the dot. Since no bubbles were seen except for the dots, the bubble occupation area ratio as a whole of the light diffuser varied from 0% to 52%.
The luminance uniformity and light emission utilization efficiency of the surface light emitting device provided with the obtained sheet-like light diffuser were evaluated in substantially the same manner as in step (6) of Example 1, and the thickness of the obtained surface light emitting device was measured. Was about 20 mm as a whole, and both luminance uniformity and light emission utilization efficiency were good.
Further, the light reflection part integration of the obtained sheet-like light diffuser was evaluated in substantially the same manner as in step (7) of Example 1, and a white foam was formed on the four end faces of the obtained light diffuser. The light reflection part which consists of was able to be integrated.

<Example 3>
-Light diffuser with dot foam laminated on transparent resin In step (1) of Example 1, an applicator bar with a coating thickness of 300 μm was used instead of an applicator bar with a coating thickness of 200 μm to obtain a foamable sheet with a thickness of 50 μm. It was. The foamed sheet thus obtained was irradiated with ultraviolet rays through a dot pattern photomask in the step (3) of Example 1 (irradiation dose 2000 mJ / cm ² ). At this time, a dot pattern was used in which the dot diameter and density gradually decreased along two directions from the center position of the photomask toward the opposite end faces. Moreover, the parallel light of a Deep-UV light source was used for the ultraviolet-ray used by light irradiation. After the UV irradiation, the transparent resin sheet having the same dimensions as the foamable sheet (thickness 50 μm, resin composition is polymethylmethacrylate) is stacked on the foamable sheet at the time of the heat press in the step (4) of Example 2 The sheet-like light diffuser having the light diffusing portion in close contact with the transparent resin sheet was obtained by heat-pressing the cake. The thickness of the sheet-like light diffuser was 100 μm.
When the bubble diameter and bubble occupying area ratio of the obtained sheet-shaped light diffuser were determined in the same manner as in Example 1, the portion made of the foam had a dot-like portion extending from the central position near the light source toward the end surface. The slope distribution gradually decreased. The maximum bubble diameter in the dot-like portion was 0.4 μm, and the bubble occupation area ratio was 52% (light reflectivity was about 90%), which was almost uniform within the dot. Bubbles were not seen except for the dots, and there were no bubbles in the transparent resin itself, so the bubble occupying area ratio as a whole of the light diffuser varied from 0% to 26%.
The luminance uniformity and light emission utilization efficiency of the surface emitting device provided with the obtained sheet-like light diffuser were evaluated in substantially the same manner as in step (6) of Example 1. At this time, the sheet-like light diffuser was installed in the lamp house with the light diffusion portion facing the light source side. The thickness of the obtained surface light emitting device was about 20 mm as a whole, and both the luminance uniformity and the light emission utilization efficiency were good.
Further, the integration of the light reflecting portion of the obtained sheet-like light diffuser was evaluated in substantially the same manner as in step (7) of Example 1, and as a result, the four side end surfaces of the light diffusing portion of the obtained light diffuser were white. A light reflecting part made of foam was provided and integrated.

<Comparative Example 1>
・ Diffusion agent-dispersed light diffuser Sheet-shaped by extruding pellets in which 0.1% by mass of silicone particles (Toshiba Silicone Corp., average particle size 12 μm) is uniformly mixed with methacrylic resin (manufactured by Mitsubishi Rayon Co., Ltd.) from a T-die. A light diffuser was obtained. The thickness of the sheet-like light diffuser was 145 μm.
There were no bubbles in the obtained sheet-shaped light diffuser, and the luminance uniformity and light emission utilization efficiency of the surface light emitting device provided with the bubbles were evaluated in substantially the same manner as in step (6) of Example 1. As a result, the thickness of the obtained surface light emitting device was about 20 mm as a whole, and both the luminance uniformity and the light emission utilization efficiency were poor.
In other words, the bright line of the light source is visible at the central position in the vicinity of the light source, and the brightness decreases from the central position to the end face direction.
Further, the integration of the light reflecting portion of the obtained sheet-like light diffuser was insufficient because the light reflectivity was insufficient only by mixing the silicone particles.

<Comparative Example 2>
・ Light diffuser in which hollow particles are dispersed Hollow particles (diameter 5 to 30 μm) having an acrylic highly crosslinked polymer as an outer shell are melt-dispersed in an acrylic resin and extruded from a T-die to form a sheet-like light diffuser. Got. The thickness of the sheet-like light diffuser was 200 μm.
The obtained sheet-like light diffuser had a uniform distribution in both the bubble diameter and the bubble occupation area ratio. The bubble diameter was about 10 μm, and the bubble occupation area ratio was 42 to 43% (60% in terms of light reflectivity), and the bubble distribution pattern was not seen in the end face direction away from the central position near the light source with a uniform distribution.
The luminance uniformity and light emission utilization efficiency of the surface emitting device provided with the obtained sheet-like light diffuser were evaluated in substantially the same manner as in step (6) of Example 1. As a result, the thickness of the obtained surface light emitting device was about 20 mm as a whole, and both the luminance uniformity and the light emission utilization efficiency were poor. In other words, the bright line of the light source is visible at the central position in the vicinity of the light source, and the brightness decreases from the central position to the end face direction. Since the light reflectance is high, the light emission utilization efficiency has also decreased. Furthermore, since most of the hollow particles that are present have a bubble diameter of 10 μm or more, the dispersion pattern of the hollow particles is visually recognized unless another light diffusion sheet is used in combination. It became surface emission with. Moreover, the light reflection part integration of the obtained sheet-like light diffuser was able to be integrated by providing a white light reflection part with hollow particles.

<Comparative Example 3>
・ Dot-printed light diffusing material Transparent resin sheet (length 50mm, width 50mm, thickness 100μm, resin composition is polymethylmethacrylate), printed dot pattern with white ink (including titanium dioxide and barium sulfate) (screen printing) A sheet-like light diffuser was obtained. At this time, a dot pattern in which the dot diameter and the density gradually decreased along two directions from the center position of the transparent resin sheet toward the opposite end surface was used. The dot diameter was 200 μm even at the minimum diameter. The thickness of the sheet-like light diffuser was 100 μm.
Bubbles were not present in the obtained sheet-shaped light diffuser, and the luminance uniformity and light emission utilization efficiency of the surface light emitting device provided with the bubbles were evaluated in substantially the same manner as in step (6) of Example 1. As a result, the thickness of the obtained surface light emitting device was about 20 mm as a whole, and both luminance uniformity and light emission utilization efficiency were good. However, since the size of the printed dots can be visually recognized as 200 μm or more, the dot pattern is visually recognized. Eventually, this defect causes surface light emission having a nonuniform luminance distribution.

In Example 1 and Example 3 in which fine bubble groups are contained and the bubble distribution is present, not only can uneven polarized light having a non-uniform luminance distribution (or illuminance distribution) from the light source be made uniform, The light utilization efficiency was good, and it was easy to achieve both thinning and integration.
On the other hand, Comparative Example 1 and Comparative Example 2 in which the diffusing agent and the hollow particles were dispersed had a nonuniform luminance distribution, and the light emission utilization efficiency was poor. In Comparative Example 3 in which a white ink dot pattern was printed, the luminance uniformity and macroscopicity were good, and the dot pattern was several hundred μm and could be visually observed. Therefore, the luminance uniformity was poor microscopically. . Table 1 shows the characteristics of the light diffuser obtained in the example, and Table 2 shows the characteristics of the light diffuser obtained in the comparative example.

The surface light-emitting device of the present invention can be used for various display devices. 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, a word processor, a mobile phone, a PDA, a digital camera, a video camera, various game machines, an automobile, etc. . Further, it can also be used as internal illumination of a display device used for a guide sign board, a signboard, a traffic sign, a light box, a projection screen, a Schaukasten, a copying machine, a projector, or the like in a station or public facility. Further, it can be used for general lighting used in offices and homes.

It is sectional drawing which shows an example of the light diffusing body in 1st Embodiment of this invention. It is a figure which shows the one aspect | mode of radiation energy irradiation in the manufacturing method of the light diffusing material of 1st Embodiment of this invention. It is a figure which shows the one aspect | mode of radiation energy irradiation in the manufacturing method of the light diffusing material of 1st Embodiment of this invention. It is sectional drawing which shows an example of the light diffusing body in 2nd Embodiment of this invention. It is sectional drawing which shows an example of the light diffusing body in 3rd Embodiment of this invention. It is a figure which shows an example of the manufacture process of the light diffusing body in 3rd Embodiment of this invention. It is sectional drawing which shows an example of the light diffusing body in 4th Embodiment of this invention. It is sectional drawing which shows an example of the light diffusing body in 5th Embodiment of this invention. It is sectional drawing which shows an example of the light diffusing body in 6th Embodiment of this invention. It is sectional drawing which shows an example of the light diffusing body in 7th Embodiment of this invention. It is sectional drawing which shows an example of the surface emitting device in 8th Embodiment of this invention. It is a figure which shows the manufacture process of the light guide in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Molded body 2 ... Photomask 3a ... Opening vertex side 3b ... Opening bottom side 4 ... Transparent resin sheet 5a, 5b ... Mold 6 ... Foaming property Composition 10 ... Light diffusion part 10a ... Foam 10b ... Transparent resin 11 ... Incident surface 13 ... Low foaming region 14 ... High foaming region 15 ... Middle foaming region 16 ..Emission surface 20 ... light reflection part 30 ... prism part 40 ... light guide part 41 ... light guide plate 100 ... surface light emitting device 200 ... light source
B ... Bubble D ... Dot M ... Matrix

Claims (14)

  A light diffusing body comprising a light diffusing portion which is made of a foam foamed by application of radiation energy and thermal energy and has a predetermined distribution pattern of bubble density.   The light diffuser according to claim 1, wherein a bubble occupation area ratio of the foam is distributed in a range of 65% or less.   3. The light diffusion according to claim 1, wherein the light diffusion portion has a low foaming region in which a bubble occupation area ratio is 0.5% or less and a high foaming region in which the bubble occupying area ratio is 1% or more. body.   Between the low-foaming region and the high-foaming region according to claim 3, the bubble occupation area ratio is increased from the side adjacent to the low-foaming region toward the side adjacent to the high-foaming region so as to connect the two regions. A light diffuser comprising a gradually increasing middle foaming region.   The light reflectance of the light diffusing portion according to any one of claims 1 to 4 is distributed in a range of 0% to 99.5% along the bubble density distribution pattern. Light diffuser.   6. A light diffusing body, wherein the light diffusing portion according to claim 1 is provided on a surface of a translucent support.   The light diffusing body according to any one of claims 1 to 6, further comprising a light reflecting portion made of the foam and having a bubble occupation area ratio of 15% or more adjacent to a part of a surface of the light diffusing portion. .   The light diffusing body according to claim 1, further comprising a light guide portion adjacent to a part of the surface of the light diffusing portion.   The light diffusing body according to claim 1, further comprising a prism portion adjacent to a part of the surface of the light diffusing portion.   The foam is an acid generator that generates an acid by the action of radiation energy or a base generator that generates a base and a decomposition foam that decomposes and desorbs one or more low-boiling volatile substances by reacting with the acid or base. The light diffuser according to claim 1, which is obtained by foaming a foamable composition containing a decomposable foamable compound having a functional functional group. The method for producing a light diffuser according to any one of claims 1 to 10, wherein an acid generator that generates an acid or a base generator that generates a base by the action of radiation energy reacts with an acid or a base. Forming a foamable composition containing a decomposable foamable compound having a decomposable foamable functional group that decomposes and desorbs one or more kinds of low-boiling volatile substances, and radiation energy to the molded body And a foaming process for foaming by applying thermal energy,
(A) Radiation energy applied to the molded body, (b) Thermal energy applied to the molded body, (c) Decomposable foamable functional group concentration in the molded body, (d) Acid generator in the molded body Alternatively, any one or more of the concentrations of the base generator have a predetermined non-uniform distribution.   A surface light-emitting device comprising: the light diffuser according to any one of claims 1 to 11; and a light source disposed in proximity to or in contact with one surface of the light diffuser.   A display device comprising the surface light-emitting device according to claim 12. An illumination device comprising the surface light-emitting device according to claim 13.

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