U.S. patent application number 11/494627 was filed with the patent office on 2006-11-23 for shaped article for use as an optical component and method of producing the shaped article.
This patent application is currently assigned to Mitsubishi Rayon Co., Ltd.. Invention is credited to Toshiaki Hattori, Yoshihiro Uozu.
Application Number | 20060263583 11/494627 |
Document ID | / |
Family ID | 34823933 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060263583 |
Kind Code |
A1 |
Hattori; Toshiaki ; et
al. |
November 23, 2006 |
Shaped article for use as an optical component and method of
producing the shaped article
Abstract
An optical component and a method of producing the same, which
optical component is obtained by photopolymerizing a
photopolymerizable composition so as to comprise a matrix and
numerous columnar structure bodies oriented in one direction within
the matrix, wherein the columnar structure bodies differ in
refractive index from the matrix and are arrayed in a lattice in
the plane perpendicular to said orientation direction to have a
highly arrayed structure whose refractive index periodically
changes on the order of 80 nm to 1,000 micrometer. The optical
component according to the invention is imparted with a structure
whose refractive index periodically changes with high regularity on
the order of about 80 nm to 1,000 micrometer and, owing to this
property, is usable in optical sheet, optical film and other
ordinary optical applications.
Inventors: |
Hattori; Toshiaki;
(Hiroshima, JP) ; Uozu; Yoshihiro; (Kawasaki-shi,
JP) |
Correspondence
Address: |
FITCH, EVEN, TABIN & FLANNERY
P. O. BOX 65973
WASHINGTON
DC
20035
US
|
Assignee: |
Mitsubishi Rayon Co., Ltd.
Tokyo
JP
1088506
|
Family ID: |
34823933 |
Appl. No.: |
11/494627 |
Filed: |
July 28, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP05/01221 |
Jan 28, 2006 |
|
|
|
11494627 |
Jul 28, 2006 |
|
|
|
Current U.S.
Class: |
428/221 ;
264/1.34; 264/1.37 |
Current CPC
Class: |
Y10T 428/249921
20150401; G02B 5/1857 20130101; G02B 27/46 20130101; G02B 5/1871
20130101 |
Class at
Publication: |
428/221 ;
264/001.34; 264/001.37 |
International
Class: |
B29D 7/01 20060101
B29D007/01; B29D 11/00 20060101 B29D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2004 |
JP |
2004-024354 |
Claims
1. A shaped article for use as an optical component obtained by
photopolymerizing a photopolymerizable composition so as to
comprise a matrix and numerous columnar structure bodies oriented
in one direction within the matrix, wherein the columnar structure
bodies differ in refractive index from the matrix and are arrayed
in a lattice in a plane perpendicular to said orientation direction
to have a highly arrayed structure whose refractive index
periodically changes on the order of 80 nm to 1,000 micrometer.
2. The shaped article for use as an optical component according to
claim 1, wherein the diameter of the columnar structure bodies is
not less than 80 nm and not greater than 1,000 micrometer.
3. The shaped article for use as an optical component according
claim 1, wherein the array periodicity of the columnar structure
bodies is not less than 80 nm and not greater than 1,000
micrometer.
4. A method of producing a shaped article for use as an optical
component comprising: a step of injecting into a cell a
photopolymerizable composition containing a multifunctional monomer
or oligomer comprising two or more functions and a
photopolymerization initiator and a step of directing parallel rays
onto the photopolymerizable composition, thereby
polymerization-curing the photopolymerizable composition to form a
shaped article for use as an optical component composed of a matrix
and numerous columnar structure bodies arrayed in one direction
within the matrix.
5. The method according to claim 4, wherein the full width at half
maximum of the parallel rays is not greater than 100 nm.
6. The method according to claim 4, wherein the optical intensity
distribution of the parallel rays is substantially constant.
7. A shaped article for use as an optical component obtained by
photopolymerizing a photopolymerizable composition, which when
exposed to a laser beam produces a diffraction pattern exhibiting
the influence of a periodic change in refractive index imparted to
the shaped article.
8. The shaped article for use as an optical component according
claim 2, wherein the array periodicity of the columnar structure
bodies is not less than 80 nm and not greater than 1,000
micrometer.
9. The method according to claim 5, wherein the optical intensity
distribution of the parallel rays is substantially constant.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a shaped article for use as an
optical component and a method of producing the shaped article,
particularly to a shaped article for use as an optical component
such as an optical sheet or optical film having diffraction,
polarization, diffusion or other optical property, and a method of
producing the shaped article.
[0002] An example of the shaped article for use as an optical
component of the invention is the optical low-pass filter for
suppressing the occurrence of moire fringes in an image pickup
device used in a CCD detector.
DESCRIPTION OF THE PRIOR ART
[0003] Components made of plastic film or sheet in which portions
of different optical property are arrayed to have one- or
two-dimensional regularity are being studied for use as optical
control panels and other optical components.
[0004] For instance, an arrayed configuration imparting
two-dimensional regularity has been described in Macromolecules,
which gives an example of arraying block polymers regularly within
the plane perpendicular to the sheet thickness direction (see
Macromolecules 2003, 36, 3272-3288; Ref. No. 1).
[0005] In addition, Japanese Patent Unexamined Publication No.
63-309902 (Ref. No. 2), for example, teaches an arrayed
configuration imparting one-dimensional regularity. The disclosed
configuration is obtained by exposing a membranous UV-curable
composition to ultraviolet rays at a prescribed angle to cure the
UV-curable composition, next holding a second UV-curable
composition on the cured UV-curable composition, and curing the
second UV-curable composition in this state by exposing it to
ultraviolet rays at another angle, thereby overlaying portions of
different optical property in a direction perpendicular to the
sheet thickness direction.
[0006] Non Patent Document 1: Macromolecules 2003, 36, 3272-3288;
Ref. No. 1 Patent Document 1: Japanese Patent Unexamined
Publication No. 63-309902; Ref No. 2
SUMMARY OF THE INVENTION
[0007] However, the structure set out in Ref. No. 1 has an array
periodicity on the nanometer order and therefore cannot be used in
ordinary optical applications requiring an array periodicity of
around 80 nm to 1,000 micrometer.
[0008] Although the structure set forth in Ref. No. 2 has
micro-order regularity, the array accuracy is low and is therefore
not suitable for use in optical applications requiring high-level
optical control.
[0009] This invention was accomplished for overcoming these
problems of the prior art and has as its object to provide a shaped
article for use as an optical component and a method for producing
the same, which shaped article for use as an optical component is
imparted with a structure whose refractive index periodically
changes with high regularity on the order of about 80 nm to 1,000
micrometer.
[0010] This invention provides a shaped article for use as an
optical component obtained by photopolymerizing a
photopolymerizable composition so as to comprise a matrix and
numerous columnar structure bodies (domains) oriented in one
direction within the matrix, wherein the columnar structure bodies
differ in refractive index from the matrix and are arrayed in a
lattice in a plane perpendicular to said orientation direction to
have a highly arrayed structure whose refractive index periodically
changes on the order of 80 nm to 1,000 micrometer.
[0011] In accordance with a preferred aspect of the invention, the
diameter of the columnar structure bodies is not less than 80 nm
and not greater than 1,000 micrometer.
[0012] In accordance with another preferred aspect of the
invention, the array periodicity of the columnar structure bodies
is not less than 80 nm and not greater than 1,000 micrometer.
[0013] In accordance with another aspect, the invention provides a
method of producing a shaped article for use as an optical
component comprising a step of injecting into a cell a
photopolymerizable composition containing a multifunctional monomer
or oligomer comprising two or more functions and a
photopolymerization initiator and a step of directing parallel rays
onto the photopolymerizable composition, thereby
polymerization-curing the photopolymerizable composition to form a
shaped article for use as an optical component composed of a matrix
and numerous columnar structure bodies arrayed in one direction
within the matrix.
[0014] When the parallel rays are directed onto the
photopolymerizable composition in accordance with this method, a
periodic change in refractive index is produced in the
photopolymerizable composition and, as a result, the
photopolymerizable composition is polymerized into a shaped article
for use as an optical component composed of a matrix and numerous
columnar structure bodies arrayed in one direction within the
matrix. An optical sheet, optical film or other such shaped article
for use as an optical component that is capable of high-level
optical control can therefore be obtained without need for
complicated steps.
[0015] In accordance with another preferred aspect of the
invention, the full width at half maximum of the parallel rays is
not greater than 100 nm.
[0016] In accordance with another preferred aspect of the
invention, the optical intensity distribution of the parallel rays
is substantially constant.
[0017] In accordance with another aspect, the invention provides a
shaped article for use as an optical component obtained by
photopolymerizing a photopolymerizable composition, which when
exposed to a laser beam produces a diffraction pattern due to a
periodic change in refractive index imparted to the shaped
article.
[0018] This invention provides a shaped article for use as an
optical component and a method for producing the same, which is
imparted with a structure whose refractive index periodically
changes with high regularity on the order of about 80 nm to 1,000
micrometer and, owing to this property, is usable as an optical
sheet, optical film and other ordinary optical applications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic view of a shaped article according to
the invention.
[0020] FIG. 2 is an explanatory view of a cubic lattice.
[0021] FIG. 3 is an explanatory view of a hexagonal lattice.
[0022] FIG. 4 is an explanatory view of a primitive rectangular
lattice.
[0023] FIG. 5 is an explanatory view of a face-centered rectangular
lattice.
[0024] FIG. 6 is an explanatory view of an orthorhombic
lattice.
[0025] FIG. 7 a schematic view of a regular array of columnar
structure bodies.
[0026] FIG. 8 is a schematic view of a primary diffraction
pattern.
[0027] FIG. 9 is a schematic configuration diagram showing
diffraction pattern measurement.
[0028] FIG. 10 is a schematic configuration diagram showing a
light-scattering optical system.
[0029] FIGS. 11(a) and 11(b) are a plan view and a sectional view
showing the structure of a cell for producing the shaped article of
this invention.
[0030] FIG. 12 is a diagram showing measurement points for
measurement of actinic intensity distribution.
[0031] FIG. 13 is a diagram showing the emission spectrum of an
ultra-high pressure mercury lamp used in the invention.
[0032] FIG. 14 is a photograph showing a diffraction spot observed
for a shaped article of the invention.
[0033] FIG. 15 is a photograph showing a polarization microscope
image of a shaped article of the invention.
[0034] FIG. 16 is a photograph showing a Fourier transform image of
a shaped article of the invention.
[0035] FIG. 17 is a photograph showing a light-scattering image
observed for the shaped article of a comparative example.
[0036] FIG. 18 is a photograph showing a polarization microscope
image of the shaped article of the comparative example.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] FIG. 1 a schematic view of the arrayed structure of a shaped
article 1 according to a preferred embodiment of the invention. The
shaped article 1 is intended for use as an optical component. As
shown in FIG. 1, the shaped article 1 comprises a sheet- or
film-like matrix 2 and numerous columnar structure bodies 3
arranged within the matrix 2. The columnar structure bodies 3
differ from the matrix 2 in refractive index and are oriented in
one direction (thickness direction of the of the matrix 2) and
regularly arrayed. In this embodiment, the array periodicity of the
columnar structure bodies 3 is set at 80 nm to 1,000 micrometer,
preferably 90 nm to 5,000 nm, more preferably 100 nm to 500 nm.
[0038] The diameter of the columnar structure bodies 3 (the
circumscribed circle diameter in the case of prismatic columnar
structure bodies) is 80 nm to 1,000 micrometer, preferably 90 nm to
5,000 nm, more preferably 100 nm to 500 nm.
[0039] When the array periodicity or diameter of the columnar
structure bodies 3 is less than 80 nm or larger than 1,000
micrometer, no optical function is exhibited because the
interference effect with respect to light in the wavelength range
of 350 nm to 2,000 nm is weak. In this embodiment, the diameter of
the columnar structure bodies 3 is therefore defined as 80 nm to
1,000 micrometer in order to obtain the diffraction, polarization
and other optical properties required by ordinary optical
components.
[0040] The shaped article 1 therefore has a structure whose
refractive index periodically changes with high regularity on the
order of 80 nm to 1,000 micrometer. Because of its high-optical
control capability, the shaped article of this configuration is
suitable for ordinary optical applications, particularly for use as
various kinds of optical components such as optical sheet and
optical film.
[0041] The shaped article 1 is formed by injecting a
photopolymerizable composition into a prescribed cell and
polymerization-curing the photopolymerizable composition by
exposing it to light. The photopolymerizable composition used
contains a multifunctional monomer or oligomer comprising two or
more functions and a photopolymerization initiator.
[0042] Owing to the inclusion of the monomer comprising two or more
functions in the composition, densification and rarefaction of the
polymerization degree (crosslink density) tends to occur in the
plane perpendicular to the thickness direction of the
photopolymerizable composition during the polymerization-curing.
The regions where the polymerization degree (crosslink density) is
dense have a higher refractive index than the regions where it is
rare. When such a high-low refractive index pattern is established,
the high refractive index regions assume a waveguide mode, whereby
more light passes through the high refractive index regions.
[0043] It is thought, therefore, that downward of the regions where
the polymerization degree (crosslink density) is dense and
refractive index high, the photoreaction of the photocurable
composition proceeds with still more pronounced densification and
rarefaction of the polymerization degree (crosslink density). And
this phenomenon is believed to form within the matrix 2 numerous
columnar structure bodies 3 whose refractive index differs from
that of the matrix.
[0044] The multifunctional monomer comprising two or more functions
is limited only in that it must be a monomer that, for example, has
two or more polymerizable carbon-to-carbon double bonds in the
molecule. However, among such monomers, ones including a
(metha)acryloyl group, vinyl group, acryl group or the like are
particularly preferable.
[0045] Specific examples of such multifunctional monomers
comprising two or more functions include triethylene glycol
di(metha)acrylate, polyethylene glycol di(metha)acrylate,
neopentylglycol di(metha)acrylate, 1,4-butanediol
di(metha)acrylate, 1,6-hexanediol di(metha)acrylate,
hydro-dicyclo-penta-dienyl di(metha)acrylate, ethylene
oxide-modified bisphenol A di(metha)acrylate, trimethylolpropane
tri(metha)acrylate, pentaerythritol tetra(metha)acrylate,
tetramethylolmethane tetra(metha)acrylate, pentaerythritol
hexa(metha)acrylate, multifunctional epoxy(metha)acrylate,
multifunctional urethane(metha)acrylate, divinylbenzene, triallyl
cyanurate, triallyl isocyanurate triallyl trimellitate, diallyl
chlorendate, N,N'-m-phenylene bismaleimide, and diallyl phthalate.
These monomers can be used alone or in combinations of two or
more.
[0046] When a multifunctional monomer having three or more
polymerizable carbon-to-carbon double bonds in the molecule is
used, the densification and rarefaction of the polymerization
degree (crosslink density) is still stronger, so that the columnar
structure bodies tend to form more easily.
[0047] Particularly preferable multifunctional monomers comprising
three or more functions include trimethylolpropane
tri(metha)acrylate, pentaerythritol tetra(metha)acrylate,
tetramethylolmethane tetra(metha)acrylate, and pentaerythritol
hexa(metha)acrylate.
[0048] In the case of using two or more multifunctional monomers or
oligomers as the photopolymerizable composition, it is preferable
to use ones whose individual polymers differ from one another in
refractive index and still more preferably to combine ones whose
polymers differ greatly from one another in refractive index.
[0049] The refractive index difference has to be made large in
order to obtain diffraction, polarization, diffusion and other such
functions at high efficiency. The refractive index difference is
therefore preferably 0.01 or greater, more preferably 0.05 or
greater.
[0050] When using two or more multifunctional monomers or
oligomers, it suffices for the refractive index difference between
at least two of their individual polymers to fall within the
aforesaid range. In order to obtain highly efficient diffraction,
polarization, diffusion and other functions, the two polymers or
oligomers whose individual polymers have the greatest refractive
index difference are preferably used in a weight ratio of 10:90 to
90:10.
[0051] In this embodiment, the photopolymerizable composition can
also include, in addition to the aforesaid multifunctional monomers
or oligomers, a monofunctional monomer or oligomer having a single
polymerizable carbon-to-carbon double bond in the molecule.
[0052] Particularly preferable as such monofunctional monomers or
oligomers are ones containing (metha)acryloyl group, vinyl group,
acryl group of the like.
[0053] Specific examples of monofunctional monomers include, for
example, methyl(metha)acrylate, tetrahydrofurfuryl (metha)acrylate,
ethylcarbitol (metha)acrylate, dicyclopentenyloxyethyl
(metha)acrylate, isobornyl (metha)acrylate phenylcarbitol
(metha)acrylate, nonylphenoxyethyl (metha)acrylate,
2-hydroxy-3-phenoxypropyl (metha)acrylate, (metha)acryloyloxyethyl
succinate, (metha)acryloxyethyl phthalate, phenyl (metha)acrylate,
cyanoethyl (metha)acrylate, tribromophenyl (metha)acrylate,
phenoxyethyl (metha)acrylate, tribromophenoxyethyl (metha)acrylate,
benzyl (metha)acrylate, p-bromobenzyl (metha)acrylate, 2-ethylhexyl
(metha)acrylate, lauryl (metha)acrylate, trifluoroethyl
(metha)acrylate, 2,2,3,3-tetrafluoropropyl (metha)acrylate and
other (metha)acrylate compounds; styrene, p-chlorostyrene,
vinylacetate, acrylonitrile, N-vinylpyrrolidone, vinylnaphthalene
and other vinyl compounds; and ethylene glycol bisallylcarbonate,
diallyl phthalate, diallyl isophthalate, and other allyl
compounds.
[0054] These monofunctional monomers and oligomers are used to
impart flexibility to the shaped article. The multifunctional
monomers and oligomers are preferably used in an amount in the
range of 10 to 99 mass %, more preferably 10 to 50 mass %, of the
total amount of multifunctional monomers and oligomers.
[0055] As the photopolymerizable composition can also be used a
uniform dissolved mixture containing the multifunctional monomers
or oligomers and a compound not possessing a polymerizable
carbon-to-carbon double bond.
[0056] Usable compounds not possessing a polymerizable
carbon-to-carbon double bond include, for example, polystyrene,
poly (methyl methacrylate), polyethylene oxide, polyvinyl
pyrrolidone, polyvinyl alcohol, nylon and other polymers; toluene,
n-hexane, cyclohexane, acetone, methylethylketone, methyl alcohol,
ethyl alcohol, acetic ester, acetonitrile, dimethylacetamide,
dimethylformamide, tetrahydrofuran and other such monomeric
compounds; and organic halogen compounds, organic silicon
compounds, plasticizers, stabilizers and other such additives.
[0057] The compound not possessing a polymerizable carbon-to-carbon
double bond is used to lower the viscosity of the
photopolymerizable composition and make it easy to handle during
production of the shaped article. The amount used is preferably in
the range of 1 to 99 mass % of the total amount of multifunctional
monomers and oligomers, and preferably in the range of 1 to 50%
thereof for improving handleability while also ensuring formation
of regularly arrayed columnar structure bodies.
[0058] In this embodiment, the photopolymerization initiator used
in the photopolymerizable composition is not particularly limited
and can be any of various types used in ordinary
photopolymerization, i.e., polymeraization conducted by exposing a
photopolymerizable composition to untraviolet or other actinic
rays. Usable photopolymerization initiators include, for example,
benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone,
benzoinethylether, diethoxyacetophenone,
p-t-butyltrichloroacetophenone, benzyldimethylketal,
2-hydroxy-2-methylpropiophenone, 1-hydroxy cyclohexylphenyl ketone,
2-benzyl-2-dimethylamino-1-(4-morpho-lenophenyl) butanone,
dibenzosuberone and the like.
[0059] The amount of these photopolymerization initiators used is
preferably in the range of 0.001 to 10 parts by weight per 100
parts by weight of the remainder of the photopolymerizable
composition, and more preferably 0.001 to 5 parts by weight thereof
from the viewpoint of preventing degradation of shaped article
transparency.
[0060] As explained earlier, the shaped article 1 of this
embodiment has numerous columnar structure bodies 3 differing in
refractive index from the matrix 2 arranged within the matrix 2 to
be oriented in one direction. The columnar structure bodies 3 are
arranged to have two-dimensional regularity in the plane
perpendicular to the orientation direction. The columnar structure
bodies can be of any of various shapes including
circular-cylindrical, elliptic-cylindrical and prismatic.
[0061] The regularity is represented by a two-dimensional Bravais
lattice generated by primitive translation vectors a, b.
Specifically, in this embodiment, the unit lattice is one among the
five lattices (cubic lattice, hexagonal lattice, primitive
rectangular lattice, face-centered rectangular lattice, and
orthorhombic lattice) shown in FIGS. 2 to 6. As shown in FIG. 2,
these five unit lattices are represented by the magnitudes of their
vectors a, b. and the angle .phi. therebetween.
[0062] The cylindrical structure bodies arranged in a hexagonal
lattice (the array of the columnar structure bodies 3 in the matrix
2 is shown schematically in FIG. 7) or a cubic lattice are
preferable for use as optical low-pass filters that generate a
triaxial or biaxial diffraction pattern and can achieve multiaxial
separation in a single shaped article. The hexagonal lattice
includes the triangular lattice and honeycomb lattice.
[0063] The regularity of the shaped article of this invention is
preferably such as to provide up to the secondary diffraction
pattern, but in some applications, such as polarization, need only
provide up to the primary diffraction pattern 4 as shown in FIG. 8.
TABLE-US-00001 TABLE 1 Lattice Unit lattice axis Cubic |a| = |b|, o
= 90.degree. Hexagonal |a| = |b|, o = 120.degree. Primitive
rectangular |a| .noteq. |b|, o = 90.degree. Face-centered
rectangular |a| .noteq. |b|, o = 90.degree. Orthorhombic |a|
.noteq. |b|, o = 90.degree.
[0064] When the shaped article 1 of this embodiment is placed at
the location of the specimen 7 in FIG. 9 and a laser beam 6 is
directed from a laser beam source 5 the direction of the columnar
structure body 3 orientation, a diffraction pattern 9 attributable
to the regularity of the columnar structure bodies 3 is observed on
a screen 8.
[0065] One method of evaluating high-order structure based on the
crystallization or phase separation of a plastic film or other
polymer solid is the light-scattering method of exposing the
polymer solid to a laser beam and detecting the scattering pattern
produced in accordance with the structure of the polymer solid.
[0066] FIG. 10 shows an optical system used in the light-scattering
method. The laser beam 6 from the laser beam source 5 is directed
through a polarizing element 10 onto the specimen 7 and the
scattered light resulting from the internal structure of the
specimen 7 is passed through an analyzer 11 and projected onto the
rearward screen 8 for observation of a scattering pattern 12. The
arrows 12 in the drawing indicate the polarization direction of the
light after passing through the polarizing element 10 and analyzer
11.
[0067] An optical system whose polarization directions are
perpendicular to each other as shown in FIG. 10 is called an Hv
scattering optical system, and one whose polarization directions
are parallel is called a Vv scattering optical system. Information
regarding the optical anisotropy of the specimen can be obtained
from the Hv scattering, while information regarding the density
fluctuation and optical anisotropy of the specimen can be obtained
from the Vv scattering.
[0068] When the light-scattering pattern of polyethylene, which is
known to be a crystalline polymer, is observed by such an optical
system, the clover-shaped scattering pattern 12 of FIG. 10 is
observed because polyethylene is composed of spherical crystals
having radial optical anisotropy.
[0069] In contrast, when an optical system like that of FIG. 10 but
with the analyzer 11 removed is used to project on the screen 8 the
scattering pattern of the shaped article of this embodiment having
the cylindrical structure bodies regularly arrayed in a hexagonal
lattice or cubic lattice on the order of not less than 80 nm and
not greater than 1,000 micrometer, a diffraction pattern is
obtained owing to the interference effect caused by the regular
arrangement of the cylindrical structure bodies. With regard to
this invention, a diffraction pattern is said to be obtained when a
diffraction pattern such as shown in FIG. 14 is observed.
[0070] The shaped article 1 of the invention ordinarily takes the
form of a sheet or film suitable for use as an optical component
but is not limited thereto.
[0071] The method of producing the shaped article 1 of this
embodiment will now be explained. FIG. 11(a) is a plan view of a
cell 14 and FIG. 11(b) is a sectional view thereof.
[0072] The upper cover 15 of the cell 14 and other members
positioned on the light source side are made of optically
transparent material that does not optically absorb incident light.
Specific materials that can be used include Pyrex (registered
trademark) glass and quartz glass, and transparent plastic
materials like fluorine-containing (metha)acrylic resin.
[0073] The cell 14 can be variously modified in shape in accordance
with the shape of the shaped article to be formed. The rectangular
shape shown in FIG. 11 is only one example. When a film-like shaped
article is to be produced, for example, the cell 14 can be
fabricated by forming a gap between two glass plates, in which case
the photopolymerizable mixture is retained in the gap.
[0074] In this embodiment, the cell 14 is preferably hermetically
sealed to prevent the photopolymerizable composition from coming in
contact with air, so that the photopolymerization can proceed
unhindered.
[0075] First, the photopolymerizable composition is charged into
the void region of the cell 14. Next, the photopolymerizable
composition sealed in the cell 14 is exposed to parallel
ultraviolet rays or the like to polymerization-cure the
photopolymerizable composition. In order to ensure regular arraying
of the columnar structure bodies, it is preferable at this time for
the optical intensity distribution of the parallel rays to be
substantially constant in the plane perpendicular to the direction
of light travel.
[0076] The light source is preferably one that uses a mirror, lens
or the like to convert light from a spot light source into parallel
rays of substantially constant optical intensity distribution (top
hat distribution), a surface-emitting semiconductor laser (VCSEL),
or other such surface-emitting light source.
[0077] From the viewpoint of ensuring that the columnar structure
bodies are formed in a regular array, the parallelism of the
incident light should preferably be such that the beam spread angle
is not greater than .+-.0.03 rad, more preferably in the range of
not greater than .+-.0.001 rad. Although a laser beam is preferable
in the point of high parallelism, the optical intensity
distribution of the beam is Gaussian and should preferably be made
substantially constant by means of an appropriate filter or the
like during use.
[0078] In order to array the columnar structure bodies with high
regularity in the shaped article, the polymerization reaction
should preferably proceed uniformly in the plane perpendicular to
the film thickness direction of the shaped article. For this, the
optical intensity measured at multiple points within the exposed
area (points I to IX shown in FIG. 12) is preferably such that the
illumination distribution given by Equation (1) below is not
greater than 2.0%, more preferably not greater than 1.0%.
Illumination distribution=(max value-min value)/(max value+min
value).times.100 Eq. (1)
[0079] In addition, the regularity of the columnar structure body
array improves with shorter wavelength of the incident light. The
full width at half maximum of the parallel rays should therefore be
not greater than 100 nm, preferably not greater than 20 nm.
EXAMPLES
[0080] The present invention will now be explained with reference
to specific examples. However, it should be noted that the present
invention is in no way limited to the details of the described
arrangements.
Example 1
[0081] The photopolymerizable composition used was prepared by
mixing 50 parts by mass of methymethacylate having a refractive
index of 1.489 as an independent polymer and 50 parts by mass of
trimethylolpropane triacrylate having a refractive index of 1.535
as an independent polymer and dissolving in the mixture 1 part by
mass of 1-hydroxy cyclohexylphenyl ketone as photopolymerization
initiator.
[0082] The obtained photopolymerizable composition was sealed
film-like in a glass cell that resembled the one shown in FIG. 11
and measured 50 mm.times.50 mm and 0.1 mm in thickness. Next, an
ultraviolet beam having a beam spread angle of not greater than
.+-.0.001 rad and an illumination distribution in its optical
intensity distribution in the plane perpendicular to the direction
of light travel of not greater than 2.0% was directed
perpendicularly onto the surface of the upper cover 15, thereby
polymerization-curing the photopolymerizable composition to produce
a plastic film.
[0083] The light source used was a parallel ray ultraviolet
irradiator e1uipped with an ultra-high pressure mercury lamp having
an emission spectrum like that shown in FIG. 13. A monochromatic
beam having a center wavelength of 365 nm and a full width at half
maximum of 10 nm was extracted by means of an interference filter
and used as the irradiation light.
[0084] The plastic film obtained was placed in the manner shown in
FIG. 9 and diffraction pattern evaluation was performed by
directing a 532 nm laser beam on to it in the direction of film
thickness. As shown in FIG. 14, a diffraction pattern was observed
that was attributable to the presence of 2-micron diameter
cylindrical structure bodies arrayed in a hexagonal lattice at a
period of 5 microns within the plane of the polymer perpendicular
to the thickness direction. In addition, an image of the obtained
plastic film taken with a polarization microscope is shown in FIG.
15. As can be seen from the Fourier transform image of the
polarization microscope image shown in FIG. 16, a pattern
attributable to the arraying of the cylindrical structure bodies in
a hexagonal lattice was observed.
Example 2
[0085] The photopolymerizable composition used was prepared by
dissolving 1 part by mass of
2-benzyl-2-dimethylamino-1-(4-morpho-lenophenyl) butanone in 100
parts by mass of pentaerythritol tetraacrylate having a refractive
index of 1.537 as an independent polymer.
[0086] An ultraviolet beam having a beam spread angle of .+-.0.001
rad and an illumination distribution in its optical intensity
distribution in the plane perpendicular to the direction of light
travel of not greater than 2.0% was directed onto the
photopolymerizable composition, thereby polymerization-curing it
into a plastic film.
[0087] The light source used was a parallel ray ultraviolet
irradiator equipped with an ultra-high pressure mercury lamp having
an emission spectrum like that shown in FIG. 13. An ultraviolet
beam of 100 nm full width at half maximum and 250 to 400 nm
wavelength was obtained for use by means of an ultraviolet pass
filter.
[0088] The diffraction pattern of the obtained plastic film was
evaluated in the manner of Example 1. Similarly to in Example 1, a
diffraction pattern was obtained that was attributable to the
presence of 2-micron diameter cylindrical structure bodies arrayed
in a hexagonal lattice at a period of 6 microns within the plane of
the polymer perpendicular to the thickness direction.
Comparative Example 1
[0089] The photopolymerizable composition used was prepared by
dissolving 1 part by mass of
2-benzyl-2-dimethylamino-1-(4-morpho-lenophenyl) butanone as
photopolymerization initiator in 100 parts by mass of
trimethylolpropane triacrylate having a refractive index of 1.535
as an independent polymer.
[0090] A parallel ray ultraviolet irradiator equipped with an
ultra-high pressure mercury lamp having an emission spectrum like
that shown in FIG. 13 was used. An ultraviolet beam having a beam
spread angle of not greater than .+-.0.001 rad and an illumination
distribution in its optical intensity distribution in the plane
perpendicular to the direction of light travel of not greater than
2.0% was directed onto a glass cell charged with the
photopolymerizable composition without passing it through an
optical filter or the like, thereby producing a plastic film.
[0091] The diffraction pattern of the obtained plastic film was
evaluated in the manner of Example 1. The light-scattering image
shown in FIG. 17 was obtained and no characteristic pattern was
observed. An image of the obtained plastic film taken with a
polarization microscope is shown in FIG. 18. The Fourier transform
image of the polarization microscope image also did not show any
characteristic pattern.
* * * * *