U.S. patent application number 12/960071 was filed with the patent office on 2011-04-14 for mold for nanoimprinting, its production process, and processes for producing molded resin having fine concavo-convex structure on its surface and wire-grid polarizer.
This patent application is currently assigned to ASAHI GLASS COMPANY, LIMITED. Invention is credited to Yuriko Kaida, Takahira Miyagi, Hiroshi Sakamoto, Eiji Shidoji, Kosuke Takayama.
Application Number | 20110084424 12/960071 |
Document ID | / |
Family ID | 41398211 |
Filed Date | 2011-04-14 |
United States Patent
Application |
20110084424 |
Kind Code |
A1 |
Kaida; Yuriko ; et
al. |
April 14, 2011 |
MOLD FOR NANOIMPRINTING, ITS PRODUCTION PROCESS, AND PROCESSES FOR
PRODUCING MOLDED RESIN HAVING FINE CONCAVO-CONVEX STRUCTURE ON ITS
SURFACE AND WIRE-GRID POLARIZER
Abstract
To provide a mold for nanoimprinting capable of accurately
transcribing a fine concavo-convex structure, available at a low
cost and having high durability, its production process, and
processes for producing a molded resin having a fine concavo-convex
structure on its surface having the fine concavo-convex structure
of the mold accurately transcribed, and a wire-grid polarizer, with
high productivity. A mold 10 for nanoimprinting having on its mold
surface a fine concavo-convex structure comprising a plurality of
grooves 14 formed in parallel with one another at a constant pitch,
which comprises a mold base 12 made of a resin having on its
surface a fine concavo-convex structure to be the base of the fine
concavo-convex structure, a metal oxide layer 16 covering the
surface having the fine concavo-convex structure of the mold base
12, and a release layer 18 covering the surface of the metal oxide
layer 16, is used.
Inventors: |
Kaida; Yuriko; (Tokyo,
JP) ; Sakamoto; Hiroshi; (Tokyo, JP) ; Miyagi;
Takahira; (Tokyo, JP) ; Takayama; Kosuke;
(Tokyo, JP) ; Shidoji; Eiji; (Tokyo, JP) |
Assignee: |
ASAHI GLASS COMPANY,
LIMITED
|
Family ID: |
41398211 |
Appl. No.: |
12/960071 |
Filed: |
December 3, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2009/060289 |
Jun 4, 2009 |
|
|
|
12960071 |
|
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Current U.S.
Class: |
264/293 ;
425/385; 977/900 |
Current CPC
Class: |
B29C 33/56 20130101;
B29C 33/424 20130101; G03F 7/0002 20130101; B82Y 10/00 20130101;
B82Y 40/00 20130101 |
Class at
Publication: |
264/293 ;
425/385; 977/900 |
International
Class: |
B29C 59/02 20060101
B29C059/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 5, 2008 |
JP |
2008-148025 |
Claims
1. A mold for nanoimprinting having a fine concavo-convex structure
on its mold surface, which comprises a mold base made of a resin
having on its surface a fine concavo-convex structure to be the
base of the fine concavo-convex structure, a metal oxide layer
covering the surface having the fine concavo-convex structure of
the mold base, and a release layer covering the surface of the
metal oxide layer.
2. The mold for nanoimprinting according to claim 1, wherein the
fine concavo-convex structure on the mold surface is a structure
having convex stripes or grooves.
3. The mold for nanoimprinting according to claim 2, wherein the
width of the convex stripes or the width of the grooves is from 10
nm to 50 .mu.m on the average.
4. The mold for nanoimprinting according to claim 2, wherein the
thicknesses of the metal oxide layer and the release layer are at
least 1 nm, respectively, and the total thickness of them is at
most 0.4 time the width of the grooves.
5. The mold for nanoimprinting according to claim 1, wherein the
fine concavo-convex structure on the mold surface comprises a
plurality of grooves formed in parallel with one another at a
constant pitch, and the pitch of the grooves is from 30 to 300
nm.
6. The mold for nanoimprinting according to claim 1, wherein the
metal oxide layer is a layer containing an oxide of at least one
metal selected from the group consisting of Si, Al and Zr.
7. The mold for nanoimprinting according to claim 1, wherein the
release layer is a release layer formed by a compound having a
fluoroalkyl group (which may have an etheric oxygen atom).
8. The mold for nanoimprinting according to claim 1, wherein the
mold base is made of a cured product of a photocurable resin
composition.
9. A process for producing a mold for nanoimprinting, which
comprises a step of forming a layer of a photocurable resin
composition on the surface of a support substrate; a step of
overlaying a master mold having a fine concavo-convex structure on
its mold surface and the support substrate to sandwich the
photocurable resin composition between the mold surface of the
master mold and the surface of the support substrate; a step of
curing the photocurable resin composition in a state where the
photocurable resin composition is sandwiched to form a mold base
having on its surface a fine concavo-convex structure reverse of
the fine concavo-convex structure on the mold surface; a step of
separating the mold base and the master mold; a step of forming a
metal oxide layer on the surface having the concavo-convex
structure of the mold base; and a step of forming a release layer
on the surface of the metal oxide layer.
10. The process for producing a mold for nanoimprinting according
to claim 9, wherein the method of forming the metal oxide layer is
a sputtering method.
11. The process for producing a mold for nanoimprinting according
to claim 9, wherein the method of forming the release layer is a
method of bringing a solution containing a release agent into
contact with the surface of the metal oxide layer, and then
cleaning the surface of the metal oxide layer with a cleaning
liquid, followed by drying.
12. A process for producing a molded resin having a fine
concavo-convex structure on its surface, which comprises a step of
forming a layer of a photocurable resin composition on the surface
of a support substrate; a step of overlaying the mold for
nanoimprinting as defined in claim 1 and the support substrate to
sandwich the photocurable resin composition between the mold
surface having the fine concavo-convex structure and the surface of
the support substrate; a step of curing the photocurable resin
composition in a state where the photocurable resin composition is
sandwiched to form a molded resin having on its surface a fine
concavo-convex structure reverse of the fine concavo-convex
structure on the mold surface; and a step of separating the molded
resin and the mold.
13. A process for producing a wire-grid polarizer, which comprises
a step of forming a layer of a photocurable resin composition on
the surface of a support substrate; a step of overlaying the mold
for nanoimprinting as defined in claim 5 and the support substrate
to sandwich the photocurable resin composition between the mold
surface having the grooves and the surface of the support
substrate; a step of curing the photocurable resin composition in a
state where the photocurable resin composition is sandwiched to
form a light-transmitting substrate having a plurality of convex
stripes corresponding to the grooves on the mold surface; a step of
separating the light-transmitting substrate and the mold; and a
step of forming a metal layer on the convex stripes of the
light-transmitting substrate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a mold for nanoimprinting,
its production process and processes for producing a molded resin
having a fine concavo-convex structure on its surface and a
wire-grid polarizer, using the mold for nanoimprinting.
BACKGROUND ART
[0002] Nanoimprinting technology of using a mold having a fine
concavo-convex structure at the nanometer level formed on its
surface and transcribing the fine concavo-convex structure onto a
resist or a resin has been known. The nanoimprinting technology
requires a shorter processing time than an electron beam method,
requires low apparatus and material costs required to transcribe
the fine concavo-convex structure, and is also excellent in the
productivity, and thus attracts attention at present.
[0003] As a mold for nanoimprinting, the following has been
proposed.
[0004] (1) A mold for imprinting covered with a perfluoropolyether
having a functional group chemically reactive with the material of
the mold (Patent Document 1).
[0005] Further, as an apparatus to transcribe the fine
concavo-convex structure of the mold, the following has been
known.
[0006] (2) A nanoimprinting apparatus which heats and pressurizes a
substrate and a stamper having a fine concavo-convex structure
formed on its surface, to form a fine concavo-convex structure on
the substrate, and which has a mechanism to form a release material
only on convexes of the stamper (Patent Document 2).
[0007] As the material of the mold (1), a metal, a resin, a
semiconductor (silicon wafer) and an insulator may, for example, be
mentioned. Further, as the material of the stamper (mold) of (2), a
silicon wafer, a metal, glass, a ceramic and a plastic may, for
example, be mentioned. Among them, in order to accurately
transcribe the fine concavo-convex structure at the nanometer
level, a silicon wafer must be used as the material of the mold.
However, as a silicon wafer has low strength and durability, it can
be used only several tens times, and further it is very
expensive.
[0008] Accordingly, a method has been considered of using a silicon
wafer having a fine concavo-convex structure formed on its surface
as a master mold, and using a mold having the fine concavo-convex
structure of the master mold transcribed to a resin. For example,
Patent Document 3 discloses an intermediate stamper having a fine
concavo-convex structure of a mold transcribed to a photocurable
resin. However, this intermediate stamper is disposable, and there
are concerns about its cost and heavy environmental burden.
PRIOR ART DOCUMENTS
Patent Documents
[0009] Patent Document 1: JP-A-2002-283354 [0010] Patent Document
2: JP-A-2004-288783 [0011] Patent Document 3: JP-A-2007-165812
DISCLOSURE OF THE INVENTION
Object to be Accomplished by the Invention
[0012] The present invention provides a mold for nanoimprinting
capable of accurately transcribing a fine concavo-convex structure,
available at a low cost and having high durability, its production
process, and processes for producing a molded resin having a fine
concavo-convex structure on its surface having the fine
concavo-convex structure of the mold for nanoimprinting accurately
transcribed, and a wire-grid polarizer, with high productivity.
Means to Accomplish the Object
[0013] The mold for nanoimprinting of the present invention is a
mold for nanoimprinting having a fine concavo-convex structure on
its mold surface, which comprises a mold base made of a resin
having on its surface a fine concavo-convex structure to be the
base of the fine concavo-convex structure, a metal oxide layer
covering the surface having the fine concavo-convex structure of
the mold base, and a release layer covering the surface of the
metal oxide layer.
[0014] The fine concavo-convex structure on the mold surface is
preferably a structure having convex stripes or grooves.
[0015] The width of the convex stripes or the width of the grooves
is preferably from 10 nm to 50 .mu.m on the average.
[0016] It is preferred that the thicknesses of the metal oxide
layer and the release layer are at least 1 nm, respectively, and
the total thickness of them is at most 0.4 time the width of the
grooves.
[0017] It is preferred that the fine concavo-convex structure on
the mold surface comprises a plurality of grooves formed in
parallel with one another at a constant pitch, and the pitch of the
grooves is from 30 to 300 nm.
[0018] The metal oxide layer is preferably a layer containing an
oxide of at least one metal selected from the group consisting of
Si, Al and Zr.
[0019] The release layer is preferably a release layer formed by a
compound having a fluoroalkyl group (which may have an etheric
oxygen atom).
[0020] The mold base is preferably made of a cured product of a
photocurable resin composition.
[0021] The process for producing a mold for nanoimprinting of the
present invention comprises a step of forming a layer of a
photocurable resin composition on the surface of a support
substrate; a step of overlaying a master mold having a fine
concavo-convex structure on its mold surface and the support
substrate to sandwich the photocurable resin composition between
the mold surface of the master mold and the surface of the support
substrate; a step of curing the photocurable resin composition in a
state where the photocurable resin composition is sandwiched to
form a mold base having on its surface a fine concavo-convex
structure reverse of the fine concavo-convex structure on the mold
surface; a step of separating the mold base and the master mold; a
step of forming a metal oxide layer on the surface having the
concavo-convex structure of the mold base; and a step of forming a
release layer on the surface of the metal oxide layer.
[0022] The method of forming the metal oxide layer is preferably a
sputtering method.
[0023] The method of forming the release layer is preferably a
method of bringing a solution containing a release agent into
contact with the surface of the metal oxide layer, and then
cleaning the surface of the metal oxide layer with a cleaning
liquid, followed by drying.
[0024] The process for producing a molded resin having a fine
concavo-convex structure on its surface of the present invention
comprises a step of forming a layer of a photocurable resin
composition on the surface of a support substrate; a step of
overlaying the mold for nanoimprinting of the present invention and
the support substrate to sandwich the photocurable resin
composition between the mold surface having the fine concavo-convex
structure and the surface of the support substrate; a step of
curing the photocurable resin composition in a state where the
photocurable resin composition is sandwiched to form a molded resin
having on its surface a fine concavo-convex structure reverse of
the fine concavo-convex structure on the mold surface; and a step
of separating the molded resin and the mold.
[0025] The process for producing a wire-grid polarizer of the
present invention comprises a step of forming a layer of a
photocurable resin composition on the surface of a support
substrate; a step of overlaying the mold for nanoimprinting of the
present invention having a fine concavo-convex structure comprising
a plurality of grooves formed in parallel with one another at a
constant pitch, formed on its mold surface, and the support
substrate to sandwich the photocurable resin composition between
the mold surface having the grooves and the surface of the support
substrate; a step of curing the photocurable resin composition in a
state where the photocurable resin composition is sandwiched to
form a light-transmitting substrate having a plurality of convex
stripes corresponding to the grooves on the mold surface; a step of
separating the light-transmitting substrate and the mold; and a
step of forming a metal layer on the convex stripes of the
light-transmitting substrate.
EFFECTS OF THE INVENTION
[0026] The mold for nanoimprinting of the present invention is
capable of accurately transcribing a fine concavo-convex structure,
is available at a low cost and has high durability.
[0027] According to the process for producing a mold for
nanoimprinting of the present invention, a mold for nanoimprinting
capable of accurately transcribing a fine concavo-convex structure,
available at a low cost and having high durability can be produced
with high productivity.
[0028] According to the process for producing a molded resin having
a fine concavo-convex structure on its surface, and the process for
producing a wire-grid polarizer, of the present invention, a molded
resin having the fine concavo-convex structure of the mold
accurately transcribed, and a wire-grid polarizer, can be produced
at a low cost with high productivity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a cross-sectional view illustrating one example of
a mold for nanoimprinting of the present invention.
[0030] FIG. 2 is a cross-sectional view illustrating one step in a
process for producing a mold for nanoimprinting of the present
invention.
[0031] FIG. 3 is a cross-sectional view illustrating one step in a
process for producing a mold for nanoimprinting of the present
invention.
[0032] FIG. 4 is a cross-sectional view illustrating one step in a
process for producing a mold for nanoimprinting of the present
invention.
[0033] FIG. 5 is a cross-sectional view illustrating one step in a
process for producing a mold for nanoimprinting of the present
invention.
[0034] FIG. 6 is a cross-sectional view illustrating one step in a
process for producing a mold for nanoimprinting of the present
invention.
[0035] FIG. 7 is a cross-sectional view illustrating one example of
a wire-grid polarizer obtained by the production process of the
present invention.
[0036] FIG. 8 is a cross-sectional view illustrating one step in a
process for producing a wire-grid polarizer of the present
invention.
[0037] FIG. 9 is a cross-sectional view illustrating one step in a
process for producing a wire-grid polarizer of the present
invention.
[0038] FIG. 10 is a cross-sectional view illustrating one step in a
process for producing a wire-grid polarizer of the present
invention.
[0039] FIG. 11 is a cross-sectional view illustrating one step in a
process for producing a wire-grid polarizer of the present
invention.
[0040] FIG. 12 is a cross-sectional view illustrating one step in a
process for producing a wire-grid polarizer of the present
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Mold for Nanoimprinting
[0041] FIG. 1 is a cross-sectional view illustrating one example of
a mold for nanoimprinting of the present invention. A mold 10 for
nanoimprinting is a mold for nanoimprinting having a fine
concavo-convex structure on its mold surface, and is a mold to be
used for production of a molded resin having a fine concavo-convex
structure on its surface and a wire-grid polarizer described
hereinafter. The mold 10 for nanoimprinting comprises a mold base
12 made of a resin having on its surface a fine concavo-convex
structure to be the base of the fine concavo-convex structure on
the mold surface, a metal oxide layer 16 covering the surface of
the fine concavo-convex structure of the mold base 12 along the
shape of the fine concavo-convex structure, a release layer 18
covering the surface of the metal oxide layer 16, and a support
substrate 20 provided on the opposite side of the mold base 12 from
a side where the fine concavo-convex structure is formed.
(Fine Concavo-Convex Structure)
[0042] The fine concavo-convex structure in the present invention
means fine convexes and/or concaves formed on the surface of a
material (a mold, a molded product, etc.).
[0043] The convexes may, for example, be long convex stripes
extending on the surface of the material or protrusions dotted on
the surface.
[0044] The concaves may, for example, be long grooves extending on
the surface of the material or pores dotted on the surface.
[0045] The shape of the convex stripes or grooves may, for example,
be a linear, curved or bent shape. The convex stripes or the
grooves may be in the form of stripes present in parallel with one
another.
[0046] The cross-sectional shape in a direction perpendicular to
the longitudinal direction of the convex stripes or the grooves
may, for example, be rectangular, trapezoidal, triangular or
semicircular.
[0047] The shape of the protrusions or the pores may, for example,
be a triangle pole, a square pole, a hexagonal pole, a cylinder, a
triangular pyramid, a quadrangular pyramid, a hexagonal pyramid, a
conical hemisphere or a polyhedron.
[0048] The fine concavo-convex structure on the mold surface of the
mold for nanoimprinting of the present invention is a fine
concavo-convex structure formed by covering the surface having a
fine concavo-convex structure of a mold base with a metal oxide
layer and a release layer in this order.
[0049] Accordingly, the dimensions of the fine concavo-convex
structure on the mold surface of the mold for nanoimprinting of the
present invention differ from the dimensions of the fine
concavo-convex structure of the mold base by the thicknesses of the
metal oxide layer and the release layer. That is, the dimensions of
the fine concavo-convex structure of the mold surface of the mold
for nanoimprinting of the present invention are dimensions after
formation of the metal oxide layer and the release layer.
[0050] The following dimensions are dimensions of the fine
concavo-convex structure on the mold surface of the mold for
nanoimprinting of the present invention.
[0051] The width of the convex stripes or the grooves is preferably
from 10 nm to 50 .mu.m, more preferably from 15 nm to 30 .mu.m,
further preferably from 20 nm to 1 .mu.m, particularly preferably
from 40 nm to 500 nm, on the average. The width of the convex
stripes means the length of the base in the cross section in a
direction perpendicular to the longitudinal direction. The width of
the grooves means the length of the upper side in the cross section
in a direction perpendicular to the longitudinal direction.
[0052] The width of the protrusions or the pores is preferably from
10 nm to 50 .mu.m, more preferably from 15 nm to 30 .mu.m, further
preferably from 20 nm to 1 .mu.m, particularly preferably from 40
nm to 500 nm, on the average. The width of the protrusions means
the length of the base in the cross section in a direction
perpendicular to the longitudinal direction, when the base is
slender, and in other cases, means the maximum length at the base
of each protrusion. The width of the pores means the length of the
upper side in the cross section in a direction perpendicular to the
longitudinal direction, when the opening is slender, and in other
cases, means the maximum length at the opening of each pore.
[0053] The height of the convexes is preferably from 5 nm to 5
.mu.m, more preferably from 10 nm to 1 .mu.m, particularly
preferably from 30 to 500 nm, on the average.
[0054] The depth of the concaves is preferably from 5 nm to 5
.mu.m, more preferably from 10 nm to 1 .mu.m, particularly
preferably from 30 to 500 nm, on the average.
[0055] In a region where the fine concavo-convex structure is
dense, the distance between the adjacent convexes (or concaves) is
preferably from 10 nm to 10 .mu.m, more preferably from 15 nm to 2
.mu.m, particularly preferably from 20 to 500 nm, on the average.
The distance between the adjacent convexes means the distance from
the terminal end of the base in cross section of a convex to the
starting end of the base in cross section of the adjacent convex.
The distance between the adjacent concaves means the distance from
the terminal end of the upper side in cross section of a concave to
the starting end of the upper side in cross section of the adjacent
concave.
[0056] The minimum dimension of a convex is preferably from 5 nm to
1 .mu.m, more preferably from 20 to 500 nm. The minimum dimension
means the minimum dimension among the width, length and height of a
convex.
[0057] The minimum dimension of a concave is preferably from 5 nm
to 1 .mu.m, more preferably from 20 to 500 nm. The minimum
dimension means the minimum dimension among the width, length and
depth of a concave.
[0058] The fine concavo-convex structure in FIG. 1 comprises a
plurality of grooves 14 formed in parallel with one another at a
constant pitch, corresponding to convex stripes of a wire-grid
polarizer described hereinafter.
[0059] The pitch Pp of the grooves 14 is the total of the width Dp
of a groove 14 and the width of a convex stripe formed between
grooves 14. The pitch Pp of the grooves 14 is preferably from 30 to
300 nm, more preferably from 40 to 200 nm. When the pitch Pp is at
most 300 nm, a wire-grid polarizer produced by using the mold for
nanoimprinting will have a sufficiently high reflectance and high
polarization separation ability even in a short wavelength region
of about 400 nm. Further, coloring effect due to diffraction can be
suppressed. When the pitch Pp is at least 30 nm, the fine
concavo-convex structure of the mold for nanoimprinting has
sufficient strength, whereby favorable productivity and
transcription accuracy will be obtained.
[0060] The ratio (Dp/Pp) of the width Dp to the pitch Pp of the
grooves 14 is preferably from 0.1 to 0.6, more preferably from 0.4
to 0.55. When Dp/Pp is at least 0.1, a wire-grid polarizer produced
by using the mold for nanoimprinting will have sufficiently high
polarization separation ability. When Dp/Pp is at most 0.6,
coloring of transmitted light due to interference can be
suppressed.
[0061] The depth Hp of the grooves 14 is preferably from 50 to 500
nm, more preferably from 100 to 300 nm. When Hp is at least 50 nm,
selective forming of fine metallic wires on the convex stripes of a
wire-grid polarizer produced by using the mold for nanoimprinting
will be easy. When Hp is at most 500 nm, the incident angle
dependence of the degree of polarization of a wire-grid polarizer
produced by using the mold for nanoimprinting will be small.
[0062] The minimum height H of the mold 10 for nanoimprinting
excluding the support substrate 20 is preferably from 0.5 to 1,000
.mu.m, more preferably from 1 to 40 .mu.m. When H is at least 0.5
.mu.m, the strength of a resin constituting the mold base 12 is
high relative to the peel strength at the time of mold release,
whereby sufficient transcription durability will be obtained. When
H is at most 1,000 .mu.m, cracking derived from the deformation of
the mold at the time of mold release will be suppressed, whereby
sufficient transcription durability will be obtained. The minimum
thickness H is the thickness of the mold 10 for nanoimprinting
excluding the support substrate 20 at a portion where the grooves
14 are formed.
(Mold Base)
[0063] The resin constituting the mold base is preferably a
light-transmitting resin. The "light-transmitting" means that it
transmits light.
[0064] The resin constituting the mold base may be a cured product
of e.g. a thermosetting resin, a thermoplastic resin or a
photocurable resin composition, and preferred is a cured product of
a photocurable resin composition in view of the productivity and
the transcription accuracy.
[0065] The thermosetting resin may, for example, be a polyimide
(PI), an epoxy resin or a urethane resin.
[0066] The thermoplastic resin may, for example, be polypropylene
(PP), polyethylene (PE), polyethylene terephthalate (PET),
polymethyl methacrylate (PMMA), a cycloolefin polymer (COP), a
cycloolefin copolymer (COC), or a transparent fluororesin.
[0067] The cured product of a photocurable resin composition is
preferably one obtained by curing a photocurable resin composition
by photopolymerization, in view of the productivity.
[0068] The cured product of a photocurable resin composition is
preferably one having an ultraviolet transmittance at a wavelength
of 360 nm of at least 92%, more preferably at least 92.5%, at a
thickness of 200 .mu.m. When the ultraviolet transmittance is at
least 92%, the productivity will be improved when used as a
mold.
[0069] The ultraviolet transmittance is determined by the ratio
(T2.times.100/T1) of the sample transmitted light T2 to the total
quantity of light T1 at 360 nm by using an integration type light
transmittance meter.
[0070] The tensile strength of the cured product of a photocurable
resin composition is preferably at least 30 Pa, more preferably at
least 35 Pa. When the tensile strength is at least 30 Pa, the
mechanical strength will be high, and sufficient transcription
durability will be obtained.
[0071] The tensile strength is determined in accordance with JIS
K7113.
[0072] The contact angle of the cured product of a photocurable
resin composition to water is preferably at most 80.degree., more
preferably at most 75.degree.. When the contact angle is at most
80.degree., the adhesion between the mold base 12 and the metal
oxide layer 16 will be favorable.
[0073] The contact angle of the cured product of a photocurable
resin composition to water is measured in accordance with JIS K6768
by using a contact angle measuring apparatus at a portion of the
mold base 12 where no fine concavo-convex structure is formed.
[0074] The cured product of a photocurable resin composition
satisfying the above characteristics may be one obtained by curing
the following photocurable resin composition (A) by
photopolymerization.
[0075] Photocurable resin composition (A): A photocurable resin
composition comprising from 99 to 90 mass % of a photopolymerizable
monomer and from 1 to 10 mass % of a photopolymerization initiator,
which contains substantially no solvent, and which has a viscosity
at 25.degree. C. of from 1 to 2,000 mPas.
[0076] The photopolymerizable monomer may be a monomer having a
polymerizable group, and is preferably a monomer having an acryloyl
group or a methacryloyl group, a monomer having a vinyl group, a
monomer having an allyl group, a monomer having a cyclic ether
group, a monomer having a mercapto group, etc., and is more
preferably a monomer having an acryloyl group or a methacryloyl
group.
[0077] The number of the polymerizable group in the
photopolymerizable monomer is preferably from 1 to 6, more
preferably 2 or 3, particularly preferably 2. When the monomer has
two polymerizable groups, as the polymerization shrinkage is not so
significant, favorable transcription accuracy of the fine
concavo-convex structure of the master mold will be obtained, and
the cured product of a photocurable resin composition will have
sufficient strength.
[0078] The photopolymerizable monomer is preferably (meth)acrylic
acid, a (meth)acrylate, a (meth)acrylamide, a vinyl ether, a vinyl
ester, an allyl ether, an allyl ester or a styrene compound,
particularly preferably a (meth)acrylate. Here, (meth)acrylic acid
generically means acrylic acid and methacrylic acid, the
(meth)acrylate generically means an acrylate and a methacrylate,
and the (meth)acrylamide generically means an acrylamide and a
methacrylamide.
[0079] As specific examples of the (meth)acrylate, the following
compounds may be mentioned.
[0080] A mono(meth)acrylate such as phenoxyethyl (meth)acrylate,
benzyl (meth)acrylate, stearyl (meth)acrylate, lauryl
(meth)acrylate, 2-ethylhexyl (meth)acrylate, ethoxyethyl
(meth)acrylate, methoxyethyl (meth)acrylate, glycidyl
(meth)acrylate, tetrahydrofurfuryl (meth)acrylate, allyl
(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl
(meth)acrylate, N,N-diethylaminoethyl (meth)acrylate,
N,N-dimethylaminoethyl (meth)acrylate, dimethylaminoethyl
(meth)acrylate, methyladamantyl (meth)acrylate, ethyladamantyl
(meth)acrylate, hydroxyadamantyl (meth)acrylate, adamantyl
(meth)acrylate or isobornyl (meth)acrylate.
[0081] A di(meth)acrylate such as 1,3-butanediol di(meth)acrylate,
1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,
diethylene glycol di(meth)acrylate, triethylene glycol
di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl
glycol di(meth)acrylate, polyoxyethylene glycol di(meth)acrylate or
tripropylene glycol di(meth)acrylate.
[0082] A tri(meth)acrylate such as trimethylolpropane
tri(meth)acrylate or pentaerythritol tri(meth)acrylate.
[0083] A (meth)acrylate having at least four polymerizable groups
such as dipentaerythritol hexa(meth)acrylate.
[0084] The vinyl ether may, for example, be specifically an alkyl
vinyl ether (such as ethyl vinyl ether, propyl vinyl ether,
isobutyl vinyl ether, 2-ethylhexyl vinyl ether or cyclohexyl vinyl
ether), or a (hydroxyalkyl)vinyl ether (such as 4-hydroxybutyl
vinyl ether).
[0085] The vinyl ester may, for example, be specifically vinyl
acetate, vinyl propionate, vinyl (iso)butyrate, vinyl valerate,
vinyl cyclohexanecarboxylate or vinyl benzoate.
[0086] The allyl ether may, for example, be specifically an alkyl
allyl ether (such as ethyl allyl ether, propyl allyl ether,
(iso)butyl allyl ether or cyclohexyl allyl ether).
[0087] The allyl ester may, for example, be specifically an alkyl
allyl ester (such as ethyl allyl ester, propyl allyl ester or
isobutyl allyl ester).
[0088] The monomer having a cyclic ether group may be a monomer
having a glycidyl group, an oxetanyl group, an oxiranyl group or a
spiro ortho ether group.
[0089] The monomer having a mercapto group may, for example, be
specifically tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate,
trimethylolpropane tris(3-mercaptopropionate), pentaerythritol
tetrakis(3-mercaptopropionate) or dipentaerythritol
hexa(3-mercaptopropionate).
[0090] The number average molecular weight of the
photopolymerizable monomer is preferably from 100 to 800, more
preferably from 200 to 600.
[0091] The photopolymerizable monomers may be used alone or as a
mixture of two or more.
[0092] The photopolymerizable monomer preferably contains a
(meth)acrylate having at least two polymerizable groups, whereby
the cured product of the photocurable resin composition (A) has
high tensile strength. It may, for example, be specifically
1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexandiol
diacrylate, trimethylolpropane triacrylate, pentaerythritol
triacrylate, dipentaerythritol hexaacrylate, diethylene glycol
diacrylate, neopentyl glycol diacrylate, polyoxyethylene glycol
diacrylate or tripropylene glycol diacrylate. Among them, preferred
is dipentaerythritol hexaacrylate, neopentyl glycol diacrylate or
1,6-hexanediol diacrylate.
[0093] The proportion of the photopolymerizable monomer is from 99
to 90 mass %, preferably from 98 to 91 mass %, particularly
preferably from 97 to 92 mass %, in the photocurable resin
composition (A) (100 mass %). When the proportion of the
photopolymerizable monomer is at most 99 mass %, the
photopolymerizable monomer in the photocurable resin composition
(A) can easily be polymerized to form a cured product, and no
operation such as heating is necessary. When the proportion of the
photopolymerizable monomer is at least 90 mass %, the residue of
the photopolymerization initiator will be small, and physical
properties of the cured product will hardly be impaired.
[0094] The photopolymerization initiator is a compound which
induces a radical reaction or an ionic reaction by light.
[0095] The photopolymerization initiator may be the following
photopolymerization initiator.
[0096] Acetophenone type photopolymerization initiator:
acetophenone, p-(tert-butyl)-1',1',1'-trichloroacetophenone,
chloroacetophenone, 2',2'-diethoxyacetophenone,
hydroxyacetophenone, 2,2-dimethoxy-2'-phenylacetophenone,
2-aminoacetophenone, dialkylaminoacetophenone, etc.
[0097] Benzoin type photopolymerization initiator: benzyl, benzoin,
benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether,
benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone,
2-hydroxy-2-methyl-1-phenyl-2-methylpropan-1-one,
1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, benzyl
dimethyl ketal, etc.
[0098] Benzophenone type photopolymerization initiator:
benzophenone, benzoyl benzoic acid, benzoyl methyl benzoate,
methyl-o-benzoyl benzoate, 4-phenylbenzophenone,
hydroxybenzophenone, hydroxypropylbenzophenone, acrylbenzophenone,
4,4'-bis(dimethylamino)benzophenone, etc.
[0099] Thioxanthone type photopolymerization initiator:
thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone,
diethylthioxanthone, dimethylthioxanthone, etc.
[0100] Photopolymerization initiator containing a fluorine atom:
perfluoro(tert-butyl peroxide), perfluorobenzoyl peroxide, etc.
[0101] Other photopolymerization initiators: .alpha.-acyloxime
ester, benzyl-(o-ethoxycarbonyl)-.alpha.-monooxime,
acylphosphineoxide, glyoxyester, 3-ketocoumarin,
2-ethylanthraquinone, camphorquinone, tetramethylthiuram sulfide,
azobisisobutyronitrile, benzoyl peroxide, dialkyl peroxide,
tert-butyl peroxypivalate, a boron type iodonium salt, a
phosphorous type iodonium salt, a boron type onium salt, a
phosphorous type onium salt, etc.
[0102] Among them, an acetophenone type, a benzophenone type or a
boron type onium salt is preferred as the photopolymerization
initiator.
[0103] The proportion of the photopolymerization initiator is from
1 to 10 mass %, preferably from 2 to 9 mass %, particularly
preferably from 3 to 8 mass % in the photocurable resin composition
(A) (100 mass %). When the proportion of the photopolymerization
initiator is at least 1 mass %, the photopolymerizable monomer in
the photocurable resin composition (A) can easily be polymerized to
form a cured product, and no operation such as heating is
necessary. When the proportion of the photopolymerization initiator
is at most 10 mass %, the residue of the photopolymerization
initiator will be small, and physical properties of a cured product
will hardly be impaired.
[0104] The photocurable resin composition (A) contains
substantially no solvent. As it contains no solvent, it can be
cured without any other step (e.g. a step of distilling the solvent
off) when used. Further, the volume shrinkage of the photocurable
resin composition (A) when cured is small. Containing substantially
no solvent means no solvent is contained or a solvent used for
preparation of the photocurable resin composition (A) is removed as
far as possible.
[0105] The photocurable resin composition (A) may contain a
component (hereinafter referred to as other component) other than
the monomer and the photopolymerization initiator. Such other
component may, for example, be a surfactant, a photosensitizer, an
inorganic material or a carbon material.
[0106] The surfactant may, for example, be an anionic surfactant, a
cationic surfactant, an amphoteric surfactant or a nonionic
surfactant.
[0107] The anionic surfactant may, for example, be soap (fatty acid
sodium, RCOO.sup.-Na.sup.+), a monoalkyl sulfate
(ROSO.sub.3.sup.-M.sup.+), an alkylpolyoxyethylene sulfate
(RO(CH.sub.2CH.sub.2O).sub.mSO.sub.3.sup.- M.sup.+), an
alkylbenzene sulfonate
(RR'CH.sub.2CHC.sub.6H.sub.4SO.sub.3.sup.-M.sup.+) or a monoalkyl
phosphate (ROPO(OH)O.sup.-M.sup.+).
[0108] The cationic surfactant may, for example, be an alkyl
trimethyl ammonium salt (RN.sup.+(CH.sub.3).sub.3X.sup.-), a
dialkyl dimethyl ammonium salt (RR'N(CH.sub.3).sub.2X.sup.-) or an
alkyl benzyl dimethyl ammonium salt
(RN.sup.+CH.sub.2Ph)(CH.sub.3).sub.2X.sup.-).
[0109] The amphoteric surfactant may, for example, be an alkyl
dimethyl amine oxide (R(CH.sub.3).sub.2NO) or an alkyl
carboxybetaine (R(CH.sub.3).sub.2N.sup.+CH.sub.2COO.sup.-).
[0110] The nonionic surfactant may, for example, be a
polyoxyethylene alkyl ether (RO(CH.sub.2CH.sub.2O).sub.mH), fatty
acid sorbitan ester, an alkyl polyglucoside, fatty acid
diethanolamide (RCON(CH.sub.2CH.sub.2OH).sub.2) or an alkyl
monoglyceryl ether (ROCH.sub.2CH(OH)CH.sub.2OH).
[0111] In the above formulae, R is a C.sub.1-22 linear or branched
alkyl group, R' is a C.sub.1-22 linear or branched alkyl group,
M.sup.+ is a monovalent cation of an alkali metal atom, X.sup.-is a
monovalent anion of a halogen atom, Ph is a phenyl group, and m is
an integer of from 1 to 20.
[0112] The photosensitizer may, for example, be specifically
n-butylamine, di-n-butylamine, tri-n-butylphosphine, allylthiourea,
s-benzylisothiuronium-p-toluene sulfinate, triethylamine,
diethylaminoethyl methacrylate, triethylenetetramine or
4,4'-bis(dialkylamino)benzophenone.
[0113] The inorganic material may, for example, be specifically a
silicon compound (such as silicon, silicon carbide, silicon
dioxide, silicon nitride, silicon germanium or iron silicide), a
metal (such as platinum, gold, rhodium, nickel, silver, titanium,
lanthanide type element, copper, iron or zinc), a metal oxide (such
as titanium oxide, alumina, lead oxide, ITO, iron oxide, copper
oxide, bismuth oxide, manganese oxide, hafnium oxide, yttrium
oxide, tin oxide, cobalt oxide, cerium oxide or silver oxide), an
inorganic compound salt (such as a ferrodielectric material such as
barium titanate, a piezoelectric material such as lead zirconate
titanate, or a battery material such as a lithium salt), or a metal
alloy (such as a magnetic material such as a ferrite type magnet or
a neodymium type magnet, a semiconductor such as a
bismuth-tellurium alloy or a gallium-arsenic alloy, or a
fluorescence material such as gallium nitride).
[0114] The carbon material may, for example, be specifically
fullerene, carbon nanotubes, carbon nanohorns, graphite, diamond or
activated carbon.
[0115] The proportion of other component is preferably from 0 to 70
mass %, more preferably from 0 to 50 mass % to the
photopolymerizable monomer.
[0116] The viscosity of the photocurable resin composition (A) at
25.degree. C. is preferably from 1 to 2,000 mPas, particularly
preferably from 5 to 1,000 mPas. When the viscosity is within this
range, a smooth coating film can easily be formed by means of e.g.
spin coating.
[0117] The viscosity is measured at a temperature of 25.degree. C.
using a rotational viscometer.
(Metal Oxide Layer)
[0118] The metal oxide layer is preferably light-transmitting.
[0119] The metal oxide is preferably a compound stable against
light, oxygen and heat, preferably ZnO, SiO.sub.2, Al.sub.2O.sub.3,
ZrO.sub.2, SnO.sub.2 or CaO, more preferably an oxide of at least
one metal selected from the group consisting of Si, Al and Zr in
view of transcription durability, particularly preferably
SiO.sub.2, Al.sub.2O.sub.3 or ZrO.sub.2.
[0120] The thickness of the metal oxide layer is preferably from 1
to 10 nm, particularly preferably from 2 to 8 nm on the average.
When the thickness of the metal oxide layer is at least 1 nm, the
metal oxide layer will be dense, and when used as a mold, the mold
base will not be corroded by the photocurable resin composition as
a transcription material, whereby the transcription durability will
be improved. When the thickness of the metal oxide layer is at most
10 nm, the adhesion between the metal oxide layer and the mold base
will be improved, and the transcription durability will be
improved.
[0121] The thickness of the metal oxide layer is the maximum value
of the height of the metal oxide layer formed on the convex stripes
formed between the grooves of the mold base.
(Release Layer)
[0122] The release layer is formed by a release agent. The release
agent preferably contains a compound having a group capable of
being chemically bonded to the metal oxide of the metal oxide
layer. The chemical bond may be any of the covalent bond, the ionic
bond and the coordinate bond, and is preferably the covalent bond.
The group capable of being chemically bonded to the metal oxide may
be a hydrolysable group containing a silicon atom, a titanium atom
or an aluminum atom; or a carboxy group, an acyl group, a hydroxy
group, a phosphoric acid group, a phosphono group, a phosphino
group, an amino group or a mercapto group, particularly preferably
a group represented by the following formula (1):
--Si(R.sup.1).sub.t(R.sup.2).sub.3-t (1)
wherein R.sup.1 is a hydroxy group or a hydrolysable substituent,
R.sup.2 is a hydrogen atom or a monovalent hydrocarbon group, and t
is an integer of from 1 to 3.
[0123] The hydrolysable substituent as R.sup.1 may, for example, be
a halogen atom, an alkoxy group or an acyloxy group. The halogen
atom is preferably a chlorine atom. The alkoxy group is preferably
a methoxy group or an ethoxy group, more preferably a methoxy
group.
[0124] The monovalent hydrocarbon group as R.sup.2 may, for
example, be an alkyl group, an alkyl group substituted by at least
one aryl group, an alkenyl group, an alkynyl group, a cycloalkyl
group or an aryl group, and is preferably an alkyl group or an
alkenyl group. In a case where R.sup.2 is an alkyl group, it is
preferably a C.sub.1-4 alkyl group, more preferably a methyl group
or an ethyl group. In a case where R.sup.2 is an alkenyl group, it
is preferably a C.sub.2-4 alkenyl group, more preferably a vinyl
group or an allyl group.
[0125] The release agent preferably contains a compound having a
fluoroalkyl group (which may have an etheric oxygen atom), a
silicone chain or a C.sub.4-24 long chain alkyl group, particularly
preferably contains a compound having a fluoroalkyl group.
[0126] The fluoroalkyl group may, for example, be a perfluoroalkyl
group, a polyfluoroalkyl group or a perfluoropolyether group.
[0127] The silicone chain may, for example, be dimethyl silicone or
methylphenyl silicone.
[0128] The C.sub.4-24 long chain alkyl group may, for example, be a
n-hexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group,
a n-decyl group, a n-dodecyl group, a lauryl group or an octadecyl
group. Such groups may be either linear or branched.
[0129] The release agent is preferably a compound represented by
the following formula (2):
##STR00001##
wherein Rf is a perfluoroalkyl group, Z is a fluorine atom or a
trifluoromethyl group, each of "a", b, c, d and e is an integer of
at least 0, a+b+c+d+e is at least 1, the order of location of the
respective repeating units parenthesized with subscripts "a", b, c,
d and e is not limited in the formula, and X is a group capable of
being chemically bonded to the metal oxide.
[0130] X is preferably a group represented by the following formula
(3):
##STR00002##
wherein Y is a hydrogen atom or a C.sub.1-4 alkyl group, X' is a
hydrogen atom, a bromine atom or an iodine atom, R.sup.1 is a
hydroxy group or a hydrolysable substituent, R.sup.2 is a hydrogen
atom or a monovalent hydrocarbon group, k is an integer of from 0
to 2, m is an integer of from 1 to 3, and n is an integer of at
least 1.
[0131] The release agent is particularly preferably a compound
represented by the following formula (4):
##STR00003##
wherein p is an integer of at least 1, and Y, X', R.sup.1, R.sup.2,
k, m and n are as define for the above formula (3).
[0132] As commercially available release agents, the following may
be mentioned.
[0133] Fluorine type release agents: Zonyl TC coat (manufactured by
DuPont K.K.), OPTOOL DSX, OPTOOL HD2100 (manufactured by DAIKIN
INDUSTRIES LTD.), DURASURF HD-2101Z (manufactured by DAIKIN
INDUSTRIES LTD.), CYTOP CTL-107M (manufactured by Asahi Glass
Company, Limited), CYTOP CTL-107A (manufactured by Asahi Glass
Company, Limited), Novec EGC-1720 (manufactured by Sumitomo 3M
Limited), etc.
[0134] Organic release agents: A silicone resin (dimethyl silicone
oil KF96 (manufactured by Shin-Etsu Silicones), etc.), an alkane
resin (SAMLAY forming an alkyl monomolecular film (manufactured by
NIPPON SODA CO., LTD.), etc.), etc.
[0135] The thickness of the release layer is preferably from 1 to
10 nm, particularly preferably from 2 to 8 nm on the average. When
the thickness of the release layer is at least 1 nm, the metal
oxide layer will be sufficiently covered with the release layer,
thus improving the releasability. When the thickness of the release
layer is at most 10 nm, the fine concave-convex structure can be
accurately transcribed. The release layer includes a monomolecular
film of the release agent.
[0136] The thickness of the release layer is the maximum value of
the height of the release layer formed on the metal oxide layer
formed on the convex stripes formed between the grooves of the mold
base.
[0137] The thicknesses of the metal oxide layer and the release
layer are at least 1 nm, respectively, and the total thickness of
them is preferably at most 0.4 time the width of the grooves. It is
more preferred that the thicknesses of the metal oxide layer and
the release layer are at least 1 nm, respectively, and the total
thickness of them is at most 0.3 time the width of the grooves. By
the thicknesses of the metal oxide layer and the release layer
satisfying such conditions, widths capable of being transcribed are
present as grooves, whereby the mold functions.
[0138] The contact angle of the release layer to water is
preferably at least 90.degree., more preferably at least
95.degree.. When the contact angle is at least 90.degree.,
favorable releasability will be obtained.
[0139] The contact angle of the release layer to water is measured
in accordance with JIS K6768 by using a contact angle measuring
apparatus at a portion of the mold base 12 where no fine
concave-convex structure is formed at 25.degree. C.
(Support Substrate)
[0140] The support substrate is provided on the opposite side of
the mold base from a side where the fine concave-convex structure
is formed, as the case requires.
[0141] The support substrate is preferably light-transmitting.
[0142] As the material of the support substrate, preferred is PET,
polycarbonate (PC), polyvinyl chloride (PVC), PMMA, COP, a
transparent fluororesin or the like.
[0143] The above-described mold for nanoimprinting of the present
invention has a metal oxide layer between the mold base and the
release layer and thereby has high durability. Further, since the
release layer is formed on the surface of the metal oxide layer,
the fine concave-convex structure can be accurately transcribed
even though the mold base is made of a resin. Further, the mold is
available at a low cost since it is made of a resin.
<Process for Producing Mold for Nanoimprinting>
[0144] The process for producing the mold for nanoimprinting of the
present invention comprises the following steps (i) to (vii).
[0145] (i) A step of forming a layer of a photocurable resin
composition on the surface of a support substrate.
[0146] (ii) A step of overlaying a master mold having a fine
concave-convex structure on its mold surface and the support
substrate to sandwich the photocurable resin composition between
the mold surface of the master mold and the surface of the support
substrate.
[0147] (iii) A step of curing the photocurable resin composition in
a state where the photocurable resin composition is sandwiched to
form a mold base having on its surface a fine concave-convex
structure reverse of the fine concave-convex structure on the mold
surface.
[0148] (iv) A step of separating the mold base and the master
mold.
[0149] (v) A step of forming a metal oxide layer on the surface
having the fine concave-convex structure of the mold base.
[0150] (vi) A step of forming a release layer on the surface of the
metal oxide layer.
[0151] (vii) A step of separating the support substrate from the
mold base, as the case requires.
[0152] Now, the steps (i) to (vii) will be described with reference
to FIGS. 2 to 6 taking the mold 10 for nanoimprinting as an
example.
(Step (i))
[0153] As shown in FIG. 2, a photocurable resin composition 30 is
applied on a support substrate 20 to form a layer of the
photocurable resin composition 30 on the surface of the support
substrate 20.
[0154] The coating method may, for example, be a potting method, a
spin coating method, a roll coating method, a die coating method, a
spray coating method, a casting method, a dip coating method,
screen printing or a transcription method. Among them, a spin
coating method, a die coating method or a roll coating method is
preferred as the coating method.
[0155] The thickness of the coating film of the photocurable resin
composition 30 is preferably from 0.5 to 1,000 .mu.m, more
preferably from 1 to 40 .mu.m.
(Step (ii))
[0156] As shown in FIG. 3, a master mold 40 having on its surface a
fine concave-convex structure comprising a plurality of convex
stripes 42 is pressed against the photocurable resin composition 30
so that the fine concave-convex structure is in contact with the
photocurable resin composition 30, and the master mold 40 and the
support substrate 20 are overlaid to sandwich the photocurable
resin composition 30 between the mold surface of the master mold 40
and the surface of the support substrate 20.
[0157] As the material of the master mold 40, quartz, silicon,
nickel or the like is preferred. In a case where the support
substrate 20 is not light-transmitting, the material of the master
mold 40 is preferably a light-transmitting material such as
quartz.
[0158] The press pressure (gauge pressure) when the master mold 40
is pressed against the photocurable resin composition 30, is
preferably higher than 0 and at most 10 MPa (gauge pressure), more
preferably from 0.2 to 9 MPa.
(Step (iii))
[0159] As shown in FIG. 4, the photocurable resin composition 30 is
irradiated with light (such as ultraviolet light) in a state where
the photocurable resin composition 30 is sandwiched between the
mold surface of the master mold 40 and the surface of the support
substrate 20 to cure the photocurable resin composition 30 thereby
to form a mold base 12 having on its surface a fine concavo-convex
structure (grooves 14) reverse of the fine concavo-convex structure
(convex stripes 42) of the master mold 40.
[0160] Irradiation of light may be carried out from the support
substrate 20 side or the master mold 40 side, in a case where the
support substrate 20 and the master mold 40 are light-transmitting.
In a case where one of the support substrate 20 and the master mold
40 is light-transmitting and the other is not light-transmitting,
it is carried out from the light-transmitting side.
[0161] Curing by irradiation with light and curing by heating may
be combined.
[0162] As a light source for irradiation with light, a high
pressure mercury lamp may, for example, be used.
[0163] It is preferred to apply from 250 to 1,200 mJ of light
having a wavelength of 365 nm, whereby both deep part curing
properties and surface curing properties are favorable, and the
organic material will not be deteriorated.
(Step (iv))
[0164] As shown in FIG. 5, the mold base 12 and the master mold 40
are separated.
(Step (v))
[0165] As shown in FIG. 6, a metal oxide layer 16 is formed on the
surface having the fine concavo-convex structure of the mold base
12.
[0166] The method of forming the metal oxide layer 16 may, for
example, be a vapor deposition method, a sputtering method or a
plating method, and is preferably a sputtering method with a view
to uniformly forming the metal oxide layer 16.
[0167] Further, according to the sputtering method, since the mean
free path of particles is short as compared with vapor deposition,
the entire complicated fine concavo-convex structure can be covered
averagely. Further, by the sputtering method, since the collision
energy of particles is high, the film of the metal oxide layer 16
will be dense, and the adhesion between the metal oxide layer 16
and the mold base 12 will be improved, and as a result,
transcription durability will be improved.
[0168] As the sputtering method, a method of using the metal oxide
as a target; or a method (reactive sputtering method) of using a
metal as a target, and oxidizing the deposited metal layer by
oxygen ion bombardment to obtain a metal oxide layer may be
mentioned.
(Step (vi))
[0169] The surface of the metal oxide layer 16 is treated with a
releasing agent to form a release layer 18 on the surface of the
metal oxide layer 16 to obtain a mold 10 for nanoimprinting as
shown in FIG. 1.
[0170] As a method of treatment with a release agent, a wet coating
method or a dry coating method may be mentioned. The wet coating
method may, for example, be a spin coating method, a dip coating
method or a spray coating method, and is preferably a dip coating
method in view of uniformity of the release layer 18.
[0171] The dry coating method is preferably a CVD method or a vapor
deposition method.
[0172] In the wet coating method, the release agent is preferably
dissolved or dispersed in a solvent. The solvent is preferably a
fluorinated solvent, and may be CT-Solv.100, CT-Solv.180
(manufactured by Asahi Glass Company, Limited); HFE-700
(manufactured by DAIKIN INDUSTRIES LTD.); or Novec HFE
(manufactured by Sumitomo 3M Limited).
[0173] The concentration of the release agent in the solvent is
preferably from 0.001 to 10 mass %, more preferably from 0.01 to 1
mass %. If the concentration is too low, no dense release layer
will be formed, whereby the release performance may be decreased.
If the concentration is too high, the release layer will not be a
monomolecular layer but will be too thick, and the transcription
accuracy will be decreased.
[0174] The treatment after treatment by the wet coating method or
the dry coating method is not particularly limited so long as it is
carried out under conditions where the metal oxide film on the mold
surface and the functional group in the release agent are reacted
to form a chemical bond. The reaction can be accelerated by heating
at 60.degree. C. or higher. Further, the reaction can further be
accelerated by treatment under high humidity.
[0175] As the method of forming the release layer 18, preferred is
a method of bringing a solution containing the release agent into
contact with the surface of the metal oxide layer, and then
cleaning the surface of the metal oxide layer with a cleaning
liquid followed by drying.
(Step (vii))
[0176] In a case where the minimum thickness H of the mold for
nanoimprinting excluding the support substrate 20 is sufficiently
thick, the support substrate 20 may be separated from the mold base
12 to obtain a mold for nanoimprinting without the support
substrate 20.
[0177] The above-described process for producing the mold for
nanoimprinting of the present invention is a process comprising the
above steps (i) to (vi), that is, a process of forming a mold base
by photoimprinting and then forming a metal oxide layer and a
release layer in order, and accordingly by this process, a mold for
nanoimprinting capable of accurately transcribing a fine
concavo-convex structure, available at a low cost having high
durability can be produced with high productivity.
<Process for Producing Molded Resin Having Fine Concavo-Convex
Structure on its Surface>
[0178] The process for producing a molded resin (hereinafter
sometimes referred to simply as "a molded resin") having a fine
concavo-convex structure on its surface of the present invention
comprises the following steps (a) to (d).
[0179] (a) A step of forming a layer of a photocurable resin
composition on the surface of a support substrate.
[0180] (b) A step of overlaying the mold for nanoimprinting of the
present invention and the support substrate to sandwich the
photocurable resin composition between the mold surface having the
fine concavo-convex structure and the surface of the support
substrate.
[0181] (c) A step of curing the photocurable resin composition in a
state where the photocurable resin composition is sandwiched to
form a molded resin having on its surface a fine concavo-convex
structure reverse of the fine concavo-convex structure on the mold
surface.
[0182] (d) A step of separating the molded resin and the mold.
[0183] The molded resin may, for example, be a light-transmitting
substrate of a wire-grid polarizer, a light-transmitting substrate
for an optical member such as a prism, a light guide plate or a
moth eye, a support substrate for a biosensor, a patterning
substrate for a cell culture sheet, a process member for
preparation of a member to be used for a semiconductor, and a
process member for preparation of a member to be used for a
magnetic disk.
[0184] Now, the process for producing a molded resin of the present
invention will be described in detail with reference to a wire-grid
polarizer as an example.
<Wire-Grid Polarizer>
[0185] FIG. 7 is a cross-sectional view illustrating one example of
a wire-grid polarizer obtained by the production process of the
present invention. A wire-grid polarizer 50 comprises a
light-transmitting substrate 54 made of a cured product of a
photocurable resin composition, having on its surface a plurality
of convex stripes 52 formed in parallel with one another at a
constant pitch Pp, and fine metallic wires 56 formed on the convex
stripes 52 on the light-transmitting substrate 54.
(Light-Transmitting Substrate)
[0186] The pitch Pp of the convex stripes 52 is the total of a
width Dp of a convex stripe 52 and a width of a groove formed
between the convex stripes 52. The pitch Pp of the convex stripes
52 is preferably at most 300 nm, more preferably from 40 to 200 nm.
When the pitch Pp is at most 300 nm, the wire-grid polarizer 50
will have a sufficiently high reflectance and high polarization
separation ability even in a short wavelength region of about 400
nm. Further, coloring effect due to diffraction can be
suppressed.
[0187] The ratio (Dp/Pp) of the depth Dp to the pitch Pp of the
convex stripes 52 is preferably from 0.1 to 0.6, more preferably
from 0.4 to 0.55. When Dp/Pp is at least 0.1, the polarization
separation ability of the wire-grid polarizer 50 will be
sufficiently high. When Dp/Pp is at most 0.6, coloring of
transmitted light due to interference can be suppressed.
[0188] The height Hp of the convex stripes 52 is preferably from 50
to 500 nm, more preferably from 100 to 300 nm. When the height Hp
is at least 50 nm, selective forming of the fine metallic wires 56
on the convex stripes 52 will be easy. When Hp is at most 500 nm,
incident angle dependence of the degree of polarization of the
wire-grid polarizer 50 will be small.
[0189] The light-transmitting substrate is a substrate made of a
cured product of a photocurable resin composition.
[0190] The photocurable resin composition is preferably a
composition containing a photopolymerizable monomer in view of the
productivity.
[0191] The contact angle of the cured product of the photocurable
resin composition to water is preferably at least 90.degree., more
preferably at least 95.degree.. When the contact angle is at least
90.degree., when the convex stripes 52 are formed by
photoimprinting, the releasability from the mold will be good,
highly accurate transcription will be possible, and a wire-grid
polarizer 50 to be obtained will have sufficient aimed
performance.
(Fine Metallic Wire)
[0192] The height Hm of the fine metallic wires 56 is preferably
from 30 to 300 nm, more preferably from 100 to 150 nm. When the
height Hm is at least 30 nm, the wire-grid polarizer 50 will have
sufficiently high reflectance and polarization separation ability.
When the height Hm is at most 300 nm, light utilization efficiency
will be increased.
[0193] The ratio (Dm/Dp) of the width Dm of the fine metallic wires
56 to the width Dp of the convex stripes 52 is preferably from 1.0
to 3.0, more preferably from 1.1 to 2.0. When Dm/Dp is at least
1.0, the transmittance of the s-polarized light can be lowered, and
the polarization separation ability will be improved. When Dp/Pp is
at most 2.0, the high transmittance of the p-polarized light will
be obtained.
[0194] The width Dm of the fine metallic wires 56 is larger than
the width Dp of the convex stripes 52 in many cases. Accordingly,
the width Dm of the fine metallic wires 56 is the maximum value of
the width of the fine metallic wires 56 formed on the convex
stripes 52.
[0195] The material of the fine metallic wires is preferably
silver, aluminum, chromium or magnesium in view of a high
reflectance to visible light, small absorption of visible light and
a high electrical conductivity, and it is particularly preferably
aluminum.
[0196] The cross-sectional shape of the fine metallic wires may be
a square, a rectangle, a trapezoid, a circle, an ellipse or other
various shapes.
<Process for Producing Wire-Grid Polarizer>
[0197] The process for producing a wire-grid polarizer of the
present invention comprises the following steps (a) to (f).
[0198] (a) A step of forming a layer of photocurable resin
composition on the surface of a support substrate.
[0199] (b) A step of overlaying the mold for nanoimprinting of the
present invention having a fine concavo-convex structure comprising
a plurality of grooves formed in parallel with one another at a
constant pitch, formed on its mold surface, and the support
substrate to sandwich the photocurable resin composition between
the mold surface having the grooves and the surface of the support
substrate.
[0200] (c) A step of curing the photocurable resin composition in a
state where the photocurable resin composition is sandwiched to
form a light-transmitting substrate having a plurality of convex
stripes corresponding to the grooves on the mold surface.
[0201] (d) A step of separating the light-transmitting substrate
and the mold for nanoimprinting of the present invention.
[0202] (e) A step of forming a metal layer on the convex stripes of
the light-transmitting substrate.
[0203] (f) A step of separating the support substrate from the
light-transmitting substrate as the case requires.
[0204] Now, the steps (a) to (f) will be described with reference
to FIGS. 8 to 12 taking a wire-grid polarizer 50 as an example.
(Step (a))
[0205] As shown in FIG. 8, a photocurable resin composition 60 is
applied on a support substrate 58 to form a layer of the
photocurable resin composition 60 on the surface of the support
substrate 58.
[0206] As the material of the support substrate 58, an inorganic
material (such as quartz, glass or a metal) or a resin (such as
polydimethylsiloxane or a transparent fluororesin) may, for
example, be mentioned.
[0207] The coating method may, for example, be a potting method, a
spin coating method, a roll coating method, a die coating method, a
spray coating method, a casting method, a dip coating method,
screen printing or a transcription method. Among them, a spin
coating method, a die coating method or a roll coating method is
preferred as the coating method.
[0208] The thickness of the coating film of the photocurable resin
composition 60 is preferably from 0.5 to 1,000 .mu.m, more
preferably from 1 to 40 .mu.m.
(Step (b))
[0209] As shown in FIG. 9, a mold 10 for nanoimprinting having a
fine concavo-convex structure comprising a plurality of grooves 14
formed in parallel with one another at a constant pitch formed on
its surface, is pressed against the photocurable resin composition
60 so that the mold surface having the grooves 14 is in contact
with the photocurable resin composition 60, and the mold 10 for
nanoimprinting and the support substrate 58 are overlaid to
sandwich the photocurable resin composition 60 between the mold
surface having the grooves 14 and the surface of the support
substrate 58.
[0210] The press pressure (gauge pressure) when the mold 10 for
nanoimprinting is pressed against the photocurable resin
composition 60 is preferably higher than 0 and at most 10 MPa, more
preferably from 0.2 to 5 MPa.
[0211] When the mold for nanoimprinting is in the form of a roll,
it is possible to press the mold while being rotated against the
photocurable resin composition and to cure the photocurable resin
composition, whereby convex stripes corresponding to the grooves
can be continuously transcribed, and thus the obtained wire-grid
polarizer can have a large area.
(Step (c))
[0212] As shown in FIG. 10, the photocurable resin composition 60
is irradiated with light (such as ultraviolet light) in a state
where the photocurable resin composition 60 is sandwiched between
the mold surface having the grooves 14 and the surface of the
support substrate 58 to cure the photocurable resin composition 60
thereby to form a light-transmitting substrate 54 having a
plurality of convex stripes 52 corresponding to the grooves 14 on
the mold surface.
[0213] Irradiation with light may be carried out from the support
substrate 58 side or may be carried out from the mold 10 for
nanoimprinting side, in a case where the support substrate 58 and
the mold 10 for nanoimprinting are light-transmitting. In a case
where one of the support substrate 58 and the mold for
nanoimprinting is light-transmitting and the other is not
light-transmitting, it is carried out from the light-transmitting
side.
[0214] It is preferred to apply from 250 to 1,200 mJ of light
having a wavelength of 365 nm, whereby both deep part curing
properties and surface curing properties are favorable, and the
organic material will not be deteriorated.
(Step (d))
[0215] As shown in FIG. 11, the light-transmitting substrate 54 and
the mold 10 for nanoimprinting are separated. Further, the step (f)
may be carried out prior to the step (d).
(Step (e))
[0216] As shown in FIG. 12, fine metallic wires 56 are formed on
the convex stripes 52 of the light-transmitting substrate 54.
Further, the step (f) may be carried out prior to the step (e).
[0217] The method of forming the fine metallic wires 56 may, for
example, be a vapor deposition method, a sputtering method or a
plating method, and is preferably an oblique vapor deposition
method, with a view to selectively forming the fine metallic wires
56 on the convex stripes 52. In a case where the pitch Pp is narrow
and the convex stripes 52 are high as in the present invention, a
metal layer can be selectively formed on the convex stripes 52 by
carrying out oblique vapor deposition at a sufficiently low angle.
Further, it is possible to form fine metallic wires having a
desired thickness by forming a thin metal layer by an oblique vapor
deposition method and then overlaying another metal layer by a
plating method.
(Step (f))
[0218] The support substrate 58 is separated from the
light-transmitting substrate 54 to obtain a wire-grid polarizer 50
as shown in FIG. 7.
[0219] In a case where the support substrate 58 is made of a
light-transmitting material, an integrated product of the
light-transmitting substrate 54 and the support substrate 58
without separation of the support substrate 58 may be used as a
wire-grid polarizer.
[0220] The above-described process for producing a wire-grid
polarizer of the present invention is a process comprising the
above steps (a) to (f), that is, photoimprinting technology, and
accordingly by the production process, a wire-grid polarizer can be
produced with high productivity. Further, since the mold for
nanoimprinting of the present invention capable of accurately
transcribing a fine concavo-convex structure is used, a wire-grid
polarizer having the fine concavo-convex structure of the mold
accurately transcribed can be produced. Further, since the mold for
nanoimprinting of the present invention having high durability is
used, the mold can be repeatedly used and as a result, a wire-grid
polarizer can be produced at a low cost.
EXAMPLES
[0221] Now, the present invention will be described in further
detail with reference to Examples. However, it should be understood
that the present invention is by no means restricted to such
specific Examples.
[0222] Examples 1 to 6 and 9 to 11 are Examples of the present
invention, and Examples 7 and 8 are Comparative Examples.
(Ultraviolet Transmittance)
[0223] A photocurable resin composition was cured to obtain a cured
product having a thickness of 200 .mu.m. With respect to the
obtained cured product, the total quantity of light T1 at 360 nm
and the sample transmitted light T2 were measured by using an
ultraviolet visible spectrophotometer (manufactured by Shimadzu
Corporation, Solid-spec 3700) to determine the ratio
(T2.times.100/T1), which is regarded as the ultraviolet
transmittance.
(Tensile Strength)
[0224] A photocurable resin composition was cured to obtain a cured
product of 10 mm.times.50 mm.times.100 .mu.m in thickness. The
tensile strength of the cured product was measured in accordance
with JIS K7113 using a tensile testing apparatus (manufactured by
ORIENTEC Co., LTD., RTC-1210).
(Contact Angle)
[0225] The contact angle to water was measured in accordance with
JIS K6768 by using an automatic contact angle measuring apparatus
(manufactured by Kyowa Interface Science Co., Ltd., DM500) at a
portion where no fine concavo-convex structure was formed at
25.degree. C.
(Dimensions of Fine Concavo-Convex Structure)
[0226] The dimensions of the grooves and the convex stripes were
measured by a scanning electron microscope (manufactured by
Hitachi, Ltd., S-9000) and a transmission electron microscope
(manufactured by Hitachi, Ltd., H-9000) and estimated.
(Thickness)
[0227] The thickness of a metal oxide layer was measured by a film
thickness monitor comprising a quartz vibrator as a film thickness
sensor.
[0228] The thickness of a release layer was measured by a
transmission electron microscope and ESCA (manufactured by PERKIN
ELEMER-PHI, Model 5500).
(Durability I)
[0229] The photocurable resin composition 7 was applied by a spin
coating method on the surface of a highly transmitting polyethylene
terephthalate (PET) film (manufactured by Teijin DuPont Films Japan
Limited, Teijin Tetoron O3, 100 mm.times.100 mm) having a thickness
of 100 .mu.m, to form a coating film of the photocurable resin
composition 7 having a thickness of 1 .mu.m.
[0230] The mold for nanoimprinting was pressed against the coating
film of the photocurable resin composition 7 at 25.degree. C. under
0.5 MPa (gauge pressure) so that the grooves were in contact with
the coating film of the photocurable resin composition 7.
[0231] While this state was maintained, light from a high pressure
mercury lamp (frequency: 1.5 kHz to 2.0 kHz, main wavelength light:
255 nm, 315 nm and 365 nm, irradiation energy at 365 nm: 1,000 mJ)
was applied from the PET film side for 15 seconds to cure the
photocurable resin composition 7 to prepare a light-transmitting
substrate having a plurality of convex stripes corresponding to the
grooves of the mold for nanoimprinting (pitch Pp of convex stripes:
150 nm, width Dp of convex stripes: 40 nm, height Hp of convex
stripes: 200 nm). The mold for nanoimprinting was slowly separated
from the light-transmitting substrate.
[0232] The above operation as one cycle was repeatedly carried out,
and the number of cycles when the mold for nanoimprinting could not
be separated from the light-transmitting substrate was regarded as
the index of the durability.
(Durability II)
[0233] The same operation as for the evaluation of durability I was
carried out except that a photocurable resin composition 8 was used
instead of the photocurable resin composition 7, and the number of
cycles when the mold for nanoimprinting could not be separated from
the light-transmitting substrate was regarded as the index of the
durability.
(Transmittance)
[0234] A solid laser beam having a wavelength of 405 nm and a
semiconductor laser beam having a wavelength of 635 nm were guided
to the wire-grid polarizer at right angles from the fine metallic
wire side of the wire-grid polarizer, and the transmittances of
p-polarized light and s-polarized light were measured.
[0235] A transmittance of at least 70% was evaluated as
.largecircle., and a transmittance less than 70% was evaluated as
x.
(Reflectance)
[0236] A solid laser beam having a wavelength of 405 nm and a
semiconductor laser beam having a wavelength of 635 nm were guided
from the surface side of the wire-grid polarizer at an angle of
5.degree. to the surface of the wire-grid polarizer, and the
s-polarized light reflectance was measured.
[0237] A s-polarized light reflectance at a wavelength of 400 nm or
700 nm of at least 80% was evaluated as .largecircle., and a
reflectance less than 80% was evaluated as x.
(Degree of Polarization)
[0238] The degree of polarization was calculated from the following
formula.
Degree of polarization=((Tp-Ts)/(Tp+Ts)).sup.0.5
wherein Tp is the p-polarized light transmittance, and Ts is the
s-polarized light transmittance.
[0239] A degree of polarization at a wavelength of 400 nm or 700 nm
of at least 99.5% was evaluated as .largecircle., and a degree of
polarization less than 99.5% was evaluated as x.
(Preparation of Photocurable Resin Composition 1 (for Mold
Preparation))
[0240] Into a 300 mL four-necked flask equipped with a stirrer and
a condenser tube, 60 g of a monomer 1 (manufactured by Shin
Nakamura Chemical Co., Ltd., NK Ester, A-DPH, dipentaerythritol
hexaacrylate), 40 g of a monomer 2 (manufactured by Shin Nakamura
Chemical Co., Ltd., NK Ester, A-NPG, neopentyl glycol diacrylate),
4.0 g of a photopolymerization initiator 1 (manufactured by Ciba
Specialty Chemicals, IRGACURE 907) and 1.0 g of a polymerization
inhibitor (manufactured by Wako Pure Chemical Industries, Ltd.,
Q1301) were put.
[0241] In a state where the interior in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour to obtain a photocurable resin composition 1 having a
viscosity of 100 mPas.
[0242] The ultraviolet transmittance and the tensile strength of a
cured product of the photocurable resin composition 1 were
measured. The results are shown in Table 1.
(Preparation of Photocurable Resin Composition 2 (for Mold
Preparation))
[0243] Into a 300 mL four-necked flask equipped with a stirrer and
a condenser tube, 65 g of a monomer 3 (manufactured by Shin
Nakamura Chemical Co., Ltd., NK Oligo, EA-1020, bisphenol A type
epoxy acrylate), 35 g of a monomer 4 (manufactured by Shin Nakamura
Chemical Co., Ltd., NK Ester, 1,6-hexanediol diacrylate, hexane
diacrylate), 4.0 g of the photopolymerization initiator 1 and 1.0 g
of the polymerization inhibitor 1 were put.
[0244] In a state where the interior in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour to obtain a photocurable resin composition 1 having a
viscosity of 1,000 mPas.
[0245] The ultraviolet transmittance and the tensile strength of a
cured product of the photocurable resin composition 1 were
measured. The results are shown in Table 1.
(Preparation of Photocurable Resin Composition 3 (for Mold
Preparation))
[0246] Into a 300 mL four-necked flask equipped with a stirrer and
a condenser tube, 70 g of a monomer 5 (manufactured by Shin
Nakamura Chemical Co., Ltd., NK Ester A-DCP,
tricyclodecanedimethanol diacrylate), 30 g of the monomer 2, 4.0 g
of the photopolymerization initiator 2 (manufactured by Ciba
Specialty Chemicals, IRGACURE 184) and 1.0 g of the polymerization
inhibitor 1 were put.
[0247] In a state where the interior in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour to obtain a photocurable resin composition 3 having a
viscosity of 50 mPas.
[0248] The ultraviolet transmittance and the tensile strength of a
cured product of the photocurable resin composition 3 were
measured. The results are shown in Table 1.
(Preparation of Photocurable Resin Composition 4 (for Mold
Preparation))
[0249] Into a 1,000 mL four-necked flask equipped with a stirrer
and a condenser tube, 60 g of the monomer 1, 40 g of the monomer 2,
4.0 of the photopolymerization initiator 1, 1.0 g of the
polymerization inhibitor 1 and 65.0 g of cyclohexanone were
put.
[0250] In a state where the interior in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour. Then, with stirring the content in the flask, 100 g
(solid content: 30 g) of colloidal silica was slowly added, and in
a state where the interior in the flask was at room temperature and
shaded, the content was stirred and homogenized for one hour. Then,
340 g of cyclohexanone was added, and in a state where the interior
in the flask was at room temperature and shaded, the content was
stirred for one hour to obtain a solution of a photocurable resin
composition 4 having a viscosity of 250 mPas.
[0251] The ultraviolet transmittance and the tensile strength of a
cured product of the photocurable resin composition 4 were
measured. The results are shown in Table 1.
(Preparation of Photocurable Resin Composition 5 (for Mold
Preparation))
[0252] Into a 1,000 mL four-necked flask equipped with a stirrer
and a condenser tube, 60 g of a monomer 6 (manufactured by TOAGOSEI
CO., LTD., OXT-121, xylylene bisoxetane), 40 g of a monomer 7
(manufactured by Japan Epoxy Resins Co., Ltd., EP-801, monoepoxy
blend bisphenol A type epoxy resin) and 5.0 g of a
photopolymerization initiator 3 (manufactured by Wako Pure Chemical
Industries, Ltd., WPI113) were put.
[0253] In a state where the interior in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour to obtain a photocurable resin composition 5 having a
viscosity of 300 mPas.
[0254] The ultraviolet transmittance and the tensile strength of a
cured product of the photocurable resin composition 5 were
measured. The results are shown in Table 1.
(Preparation of Photocurable Resin Composition 6 (for Mold
Preparation))
[0255] Into a 1,000 mL four-necked flask equipped with a stirrer
and a condenser tube, 58 g of a monomer 8 (manufactured by Sakai
Chemical Industry Co., Ltd., TMMP, trimethylolpropane
tris(3-mercaptopropionate)), 42 g of the monomer 1, 2.0 g of the
photopolymerization initiator 1 and 1.0 g of the polymerization
inhibitor 1 were put.
[0256] In a state where the interior in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour to obtain a photocurable resin composition 6 having a
viscosity of 300 mPas.
[0257] The ultraviolet transmittance and the tensile strength of a
cured product of the photocurable resin composition 6 were
measured. The results are shown in Table 1.
(Preparation of Photocurable Resin Composition 7 (for Durability
Test I))
[0258] Into a 1,000 mL four-necked flask equipped with a stirrer
and a condenser tube, 60 g of the monomer 1, 40 g of the monomer 2,
4.0 g of the photopolymerization initiator, 0.1 g of a fluorinated
surfactant 1 (manufactured by Asahi Glass Company, Limited, a
cooligomer of fluoroacrylate
(CH.sub.2.dbd.CHCOO(CH.sub.2).sub.2(CF.sub.2).sub.8F) and butyl
acrylate, fluorine content: about 30 mass %, mass average molecular
weight: about 3,000) and 1.0 g of the polymerization inhibitor 1
were put.
[0259] In a state where the interior in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour to obtain a solution of a photocurable resin composition 7
having a viscosity of 100 mPas.
(Preparation of Photocurable Resin Composition 8 (for Durability
Test II))
[0260] Into a 1,000 mL four-necked flask equipped with a stirrer
and a condenser tube, 60 g of the monomer 1, 40 g of the monomer 2,
4.0 g of the photopolymerization initiator 1 and 1.0 g of the
polymerization inhibitor 1 were put.
[0261] In a state where the content in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour to obtain a solution of a photocurable resin composition 8
having a viscosity of 100 mPas.
(Preparation of Photocurable Resin Composition 9 (for Preparation
of Wire-Grid Polarizer))
[0262] Into a 1,000 mL four-necked flask equipped with a stirrer
and a condenser tube, 60 g of the monomer 1, 40 g of the monomer 2,
4.0 g of the photopolymerization initiator 1, 0.1 g of the
fluorinated surfactant 1, 1.0 g of the polymerization inhibitor 1
and 65.0 g of cyclohexanone were put.
[0263] In a state where the interior in the flask was at room
temperature and shaded, the content was stirred and homogenized for
one hour. Then, with stirring the content in the flask, 100 g
(solid content: 30 g) of colloidal silica was slowly added, and in
a state where the content in the flask was at room temperature and
shaded, the content was stirred and homogenized for one hour. Then,
340 g of cyclohexanone was added, and in a state where the interior
in the flask was at room temperature and shaded, the content was
stirred for one hour, to obtain a solution of a photocurable resin
composition 9 having a viscosity of 250 mPas.
(Treatment of Master Mold with Release Agent)
[0264] As a master mold, a silicon mold having a plurality of
convex stripes formed in parallel with one another at a constant
pitch (100 mm.times.100 mm, pitch Pp of convex stripes: 150 nm,
width Dp of convex stripes: 50 nm, height Hp of convex stripes: 200
nm, length of convex stripes: 50 nm, cross-sectional shape of
convex stripes: rectangular) was prepared.
[0265] A fluorinated release agent (manufactured by DAIKIN
INDUSTRIES, LTD., OPTOOL DSX) comprising a compound having a group
capable of being chemically bonded to a metal oxide was dissolved
in a fluorinated solvent (manufactured by Asahi Glass Company,
Limited, CT-Solv.100) to prepare a release agent solution 1
(concentration of fluorinated compound: 0.1 mass %).
[0266] The silicon mold was dipped in 100 mL of the release agent
solution 1, taken out, and immediately rinsed with a fluorinated
solvent (manufactured by Asahi Glass Company, Limited, CT-Solv.100)
and cured in a thermo-hydrostat at 60.degree. C. under 90% RH for
one hour to treat the surface of the silicon mold with a release
agent.
Example 1
Preparation of Mold Base
[0267] A photocurable resin composition 1 was applied by a spin
coating method on the surface of a highly transmitting polyethylene
terephthalate (PET) film (manufactured by Teijin DuPont Films Japan
Limited, Teijin Tetoron O3, 100 mm.times.100 mm) having a thickness
of 188 .mu.m to form a coating film of the photocurable resin
composition 1 having a thickness of 1 .mu.m.
[0268] The silicon mold treated with a release agent was pressed
against the coating film of the photocurable resin composition 1 at
25.degree. C. under 0.5 MPa (gauge pressure) so that the convex
stripes were in contact with the coating film of the photocurable
resin composition 1.
[0269] While this state was maintained, light from a high pressure
mercury lamp (frequency: 1.5 kHz to 2.0 kHz, main wavelength light:
255 nm, 315 nm and 365 nm, irradiation energy at 365 nm: 1,000 mJ)
was applied from the PET film side for 15 seconds to cure the
photocurable resin composition 1 to prepare a mold base having a
plurality of grooves corresponding to the convex stripes of the
silicon mold (pitch Pp of grooves: 150 nm, width Dp of grooves 50
nm, depth Hp of grooves: 200 nm). The silicon mold was slowly
separated from the mold base.
[0270] The contact angle of the mold base to water was measured.
The results are shown in Table 1.
Formation of Metal Oxide Layer:
[0271] SiO.sub.2 as a target was attached to an inline type
sputtering apparatus (manufactured by Nisshin Seiki) equipped with
a load lock mechanism. The mold base was set in the sputtering
apparatus, and SiO.sub.2 was deposited from a direction at right
angles to the surface where the grooves were formed of the mold
base to form a SiO.sub.2 layer having a thickness of 5 nm to obtain
an intermediate product having a PET film bonded to the rear side
of the mold base and a SiO.sub.2 layer formed on the front
surface.
Formation of Release Layer:
[0272] The intermediate product was dipped in 100 mL of the release
agent solution 1, taken out and immediately rinsed with a
fluorinated solvent (manufactured by Asahi Glass Company, Limited,
CT-Solv.100) and cured in a thermo-hydrostat at 60.degree. C. under
90% RH for one hour to form a release layer having a thickness of 2
nm on the surface of the SiO.sub.2 layer thereby to obtain a mold 1
for nanoimprinting. The contact angle of the surface of the release
layer of the mold 1 for nanoimprinting to water was measured. The
results are shown in Table 1.
[0273] With respect to the mold 1 for nanoimprinting, the
durability I was evaluated. Even after the operation for evaluation
of the durability was repeatedly carried out 100 cycles, there was
no change in the fine concavo-convex structure on the surface of
the light-transmitting substrate comprising the cured product of
the photocurable resin composition 7. Further, after the first
cycle, the contact angle of the surface of the release layer of the
mold 1 for nanoimprinting to water was measured, whereupon it was
93.degree..
[0274] Further, the durability II was evaluated. Even after the
operation for evaluation of the durability was repeatedly carried
out 100 cycles, there was no change in the fine concavo-convex
structure on the surface of the light-transmitting substrate
comprising the cured product of the photocurable resin composition
8. Further, after the first cycle, the contact angle of the surface
of the release layer of the mold 1 for nanoimprinting to water was
measured, whereupon it was 93.degree.. The results are shown in
Table 1.
Example 2
[0275] A mold 2 for nanoimprinting was prepared in the same manner
as in Example 1 except that the photocurable resin composition 2
was used instead of the photocurable resin composition 1. The
thickness of the SiO.sub.2 layer was 5 nm, and the thickness of the
release layer was 2 nm. The contact angle of the surface of the
release layer of the mold 2 for nanoimprinting to water was
measured. The results are shown in Table 1.
[0276] With respect to the mold 2 for nanoimprinting, the
durability I was evaluated. Even after the operation for evaluation
of the durability was repeatedly carried out 100 cycles, there was
no change in the fine concavo-convex structure on the surface of
the light-transmitting substrate comprising the cured product of
the photocurable resin composition 7.
[0277] Further, the durability II was evaluated. Even after the
operation for evaluation of the durability was repeatedly carried
out 100 cycles, there was no change in the fine concavo-convex
structure on the surface of the light-transmitting substrate
comprising the cured product of the photocurable resin composition
8. The results are shown in Table 1.
Example 3
Formation of Metal Oxide Layer
[0278] In the same manner as in Example 1 except that
Al.sub.2O.sub.3 was used as a target of sputtering, an
Al.sub.2O.sub.3 layer having a thickness of 5 nm was formed to
obtain an intermediate product having a PET film bonded to the rear
side of the mold base and an Al.sub.2O.sub.3 layer formed on the
front side.
Formation of Release Layer:
[0279] A fluorinated release agent (manufactured by DAIKIN
INDUSTRIES LTD., OPTOOL HD2100) comprising a compound having a
group capable of being chemically bonded to a metal oxide was
dissolved in a fluorinated solvent (manufactured by Asahi Glass
Company, Limited, CT-Solv.100) to prepare a release agent solution
2 (concentration of fluorinated compound: 1 mass %).
[0280] The intermediate product was dipped in 100 mL of the release
agent solution 2, withdrawn and immediately rinsed with a
fluorinated solvent (manufactured by Asahi Glass Company, Limited,
CT-Solv.100), and cured in a thermo-hydrostat at 60.degree. C.
under 90% RH for one hour to form a release layer having a
thickness of 2 nm on the surface of the Al.sub.2O.sub.3 layer
thereby to obtain a mold 3 for nanoimprinting. The contact angle of
the surface of the release layer of the mold 3 for nanoimprinting
to water was measured. The results are shown in Table 1.
[0281] With respect to the mold 3 for nanoimprinting, the
durability I was evaluated. Even after the operation for evaluation
of the durability was repeatedly carried out 100 cycles, there was
no change in the fine concavo-convex structure on the surface of
the light-transmitting substrate comprising the cured product of
the photocurable resin composition 7.
[0282] Further, the durability II was evaluated. Even after the
operation for evaluation of the durability was repeatedly carried
out 100 cycles, there was no change in the fine concavo-convex
structure on the surface of the light-transmitting substrate
comprising the cured product of the photocurable resin composition
8. The results are shown in Table 1.
Example 4
[0283] A mold 4 for nanoimprinting was prepared in the same manner
as in Example 1 except that the photocurable resin composition 3
was used instead of the photocurable resin composition 1. The
thickness of the SiO.sub.2 layer was 5 nm, and the thickness of the
release layer was 2 nm. The contact angle of the surface of the
release layer of the mold 4 for nanoimprinting to water was
measured. The results are shown in Table 1.
[0284] With respect to the mold 4 for nanoimprinting, the
durability I was evaluated. Even after the operation for evaluation
of the durability was repeatedly carried out 100 cycles, there was
no change in the fine concavo-convex structure of the surface of
the light-transmitting substrate comprising the cured product of
the photocurable resin composition 7.
[0285] Further, the durability II was evaluated. Even after the
operation for evaluation of the durability was repeatedly carried
out 100 cycles, there was no change in the fine concavo-convex
structure on the surface of the light-transmitting substrate
comprising the cured product of the photocurable resin composition
8. The results are shown in Table 1.
Example 5
Formation of Metal Oxide Layer
[0286] An intermediate product was prepared in the same manner as
in Example 1 except that the photocurable resin composition 4 was
used instead of the photocurable resin composition 1. The thickness
of the SiO.sub.2 layer was 5 nm.
Formation of Release Layer:
[0287] A fluorinated release agent (manufactured by DAIKIN
INDUSTRIES LTD., OPTOOL DSX) comprising a compound having a group
capable of being chemically bonded to a metal oxide was dissolved
in a fluorinated solvent (manufactured by Asahi Glass Company,
Limited, CT-Solv.100) to prepare a release agent solution 3
(concentration of fluorinated compound: 2 mass %).
[0288] Using the release agent solution 3 as a deposition source,
the release agent was deposited on the surface of the intermediate
product by a vacuum vapor deposition apparatus (manufactured by
SHOWA SHINKU CO., LTD. SEC-16CM). The intermediate product was
rinsed with a fluorinated solvent (manufactured by Asahi Glass
Company, Limited, CT-Solv.100) to form a release layer having a
thickness of 1 nm on the surface of SiO.sub.2 thereby to obtain a
mold 5 for nanoimprinting. The contact angle of the surface of the
release layer of the mold 5 for nanoimprinting to water was
measured. The results are shown in Table 1.
[0289] With respect to the mold 5 for nanoimprinting, the
durability I was evaluated. Even after the operation for evaluation
of the durability was repeatedly carried out 100 cycles, there was
no change in the fine concavo-convex structure on the surface of
the light-transmitting substrate comprising the cured product of
the photocurable resin composition 7.
[0290] Further, the durability II was evaluated. Even after the
operation for evaluation of the durability was repeatedly carried
out 100 cycles, there was no change in the fine concavo-convex
structure on the surface of the light-transmitting substrate
comprising the cured product of the photocurable resin composition
8. The results are shown in Table 1.
Example 6
[0291] In the same manner as in Example 1 except that ZrO.sub.2 was
used as the target of sputtering, a ZrO.sub.2 layer having a
thickness of 5 nm was formed to obtain a mold 6 for nanoimprinting
having a PET film bonded to the rear side of the mold base, a
ZrO.sub.2 layer formed on the front surface, and a release layer
further formed on the ZrO.sub.2 layer. The contact angle of the
surface of the release layer of the mold 6 for nanoimprinting to
water was measured. The results are shown in Table 1.
[0292] With respect to the mold 6 for nanoimprinting, the
durability I was evaluated. Even after the operation for evaluation
of the durability was repeatedly carried out 100 cycles, there was
no change in the fine concavo-convex structure on the surface of
the light-transmitting substrate comprising the cured product of
the photocurable resin composition 7.
[0293] Further, the durability II was evaluated. Even after the
operation for evaluation of the durability was repeatedly carried
out 100 cycles, there was no change in the fine concavo-convex
structure on the surface of the light-transmitting substrate
comprising the cured product of the photocurable resin composition
8. The results are shown in Table 1.
Example 7
[0294] In the same manner as in Example 1, an intermediate product
having a PET film bonded to the rear side of the mold base and a
SiO.sub.2 layer having a thickness of 5 nm formed on the front
side, was obtained, which was regarded as a mold 7 for
nanoimprinting. The contact angle of the surface of the SiO.sub.2
layer of the mold 7 for nanoimprinting to water was measured. The
results are shown in Table 1.
[0295] With respect to the mold 7 for nanoimprinting, the
durability I was evaluated. Even on the first cycle of the
operation for evaluation of the durability, the mold 7 for
nanoimprinting could not be separated from the light-transmitting
substrate comprising the cured product of the photocurable resin
composition 7.
[0296] Further, the durability II was evaluated. Even on the first
cycle of the operation for evaluation of the durability, the mold 7
for nanoimprinting could not be separated from the
light-transmitting substrate comprising the cured product of the
photocurable resin composition 8. The results are shown in Table
1.
Example 8
[0297] In the same manner as in Example 1, a mold base provided
with a PET film was prepared. On the mold base, a release layer
having a thickness of 2 nm was formed in the same manner as in
Example 1 to obtain a mold 8 for nanoimprinting. The contact angle
of the surface of the release layer of the mold 8 for
nanoimprinting to water was measured. The results are shown in
Table 1.
[0298] With respect to the mold 8 for nanoimprinting, the
durability I was evaluated. On the fifth cycle of the operation for
evaluation of the durability, the mold 8 for nanoimprinting could
not be separated from the light-transmitting substrate comprising
the cured product of the photocurable resin composition 7.
[0299] Further, the durability II was evaluated. Even on the first
cycle of the operation for evaluation of the durability, the mold 8
for nanoimprinting could not be separated from the
light-transmitting substrate comprising the cured product of the
photocurable resin composition 8. The results are shown in Table
1.
Example 9
[0300] A mold 9 for nanoimprinting was prepared in the same manner
as in Example 1 except that the photocurable resin composition 5
was used instead of the photocurable resin composition 1. The
thickness of the SiO.sub.2 layer was 5 nm, and the thickness of the
release layer was 2 nm. The contact angle of the surface of the
release layer of the mold 7 for nanoimprinting to water was
measured. The results are shown in Table 1.
[0301] With respect to the mold 9 for nanoimprinting, the
durability I was evaluated. Even after the operation for evaluation
of the durability was repeatedly carried out 100 cycles, there was
no change in the fine concavo-convex structure on the surface of
the light-transmitting substrate comprising the cured product of
the photocurable resin composition 7.
[0302] Further, the durability II was evaluated. Even after the
operation for evaluation of the durability was repeatedly carried
out 100 cycles, there was no change in the fine concavo-convex
structure on the surface of the light-transmitting substrate
comprising the cured product of the photocurable resin composition
8. The results are shown in Table 1.
Example 10
[0303] A mold 10 for nanoimprinting was prepared in the same manner
as in Example 1 except that the photocurable resin composition 6
was used instead of the photocurable resin composition 1. The
thickness of the SiO.sub.2 layer was 5 nm, and the thickness of the
release layer was 2 nm. The contact angle of the surface of the
release layer of the mold 10 for nanoimprinting to water was
measured. The results are shown in Table 1.
[0304] With respect to the mold 10 for nanoimprinting, the
durability was evaluated. Even after the operation for evaluation
of the durability was repeatedly carried out 100 cycles, there was
no change in the fine concavo-convex structure on the surface of
the light-transmitting substrate comprising the cured product of
the photocurable resin composition 7.
[0305] Further, the durability II was evaluated. Even after the
operation for evaluation of the durability was repeatedly carried
out 100 cycles, there was no change in the fine concavo-convex
structure on the surface of the light-transmitting substrate
comprising the cured product of the photocurable resin composition
8. The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Ex. 1 2 3 4 5 6 7 8 9 10 Mold Photocurable
resin 1 2 1 3 4 1 1 1 5 6 base composition Ultraviolet
transmittance 92.8 92.4 92.8 93.1 92.6 92.8 92.8 92.8 91.8 92.3 (%)
Tensile strength (MPa) 35 54 35 42 68 35 35 35 78 52 Contact angle
(.degree.) 70 68 70 72 64 70 70 70 48 54 Metal Type SiO.sub.2
SiO.sub.2 Al.sub.2O.sub.3 SiO.sub.2 SiO.sub.2 ZrO.sub.2 SiO.sub.2
-- SiO.sub.2 SiO.sub.2 oxide Thickness (nm) 5 5 5 5 5 5 5 -- 5 5
layer Release Type DSX DSX HD2100 DSX DSX DSX -- DSX DSX DSX layer
Treatment method Dipping Dipping Dipping Dipping Vapor Dipping --
Dipping Dipping Dipping deposition Thickness (nm) 2 2 2 2 1 2 -- 2
2 2 Contact angle (.degree.) 109 109 105 109 109 109 27 105 109 109
Durability I Number of transcription >100 >100 >100
>100 >100 >100 1 5 >100 >100 (cycles) Durability
Number of transcription >100 >100 >100 >100 >100
>100 1 1 >100 >100 II (cycles) DSX: OPTOOL DSX, HD2100:
OPTOOL HD2100
Example 11
Preparation of Light-Transmitting Substrate
[0306] The photocurable resin composition 9 was applied by a spin
coating method on the surface of a highly transmitting polyethylene
terephthalate (PET) film (manufactured by Teijin DuPont Films Japan
Limited, Teijin Tetoron O3, 100 mm.times.100 mm) having a thickness
of 100 .mu.m to form a coating film of the photocurable resin
composition 9 having a thickness of 1 .mu.m.
[0307] The mold 1 for nanoimprinting (100 mm.times.100 mm, pitch Pp
of grooves: 150 nm, width Dp of grooves: 40 nm, depth Hp of
grooves: 200 nm, length of grooves: 50 mm, cross-sectional shape of
grooves: rectangle) was pressed against the coating film of the
photocurable resin composition 9 at 25.degree. C. under 0.5 MPa
(gauge pressure) so that the grooves were in contact with the
coating film of the photocurable resin composition 9.
[0308] While this state was maintained, light from a high pressure
mercury lamp (frequency: 1.5 kHz to 2.0 kHz, main wavelength light:
255 nm, 315 nm and 365 nm, irradiation energy at 365 nm: 1,000 mJ)
was applied from the mold 1 for nanoimprinting side for 15 seconds
to cure the photocurable resin composition 9 thereby to prepare a
light-transmitting substrate having a plurality of convex stripes.
The mold 1 for nanoimprinting was slowly separated from the
light-transmitting substrate.
[0309] The above operation was repeatedly carried out three times
to obtain three light-transmitting substrates from the single mold
1 for nanoimprinting. Dimensions of convex stripes of the
respective light-transmitting substrates (pitch Pp of convex
stripes, width Dp of convex stripes, height Hp of convex stripes)
are shown in Table 2. Further, the contact angle of the surface of
each light-transmitting substrate to water was measured. The
results are shown in Table 2.
Formation of Fine Metallic Wire:
[0310] Fine metallic wires were formed on the convex stripes of the
three light-transmitting substrates by the following method.
[0311] Using a vacuum vapor deposition apparatus (manufactured by
SHOWA SHINKU CO., LTD., SEC-16CM) capable of changing the gradient
of the light-transmitting substrate facing the deposition source,
aluminum was deposited on the convex stripes of each
light-transmitting substrate by an oblique vapor deposition method
to form fine metallic wires (thickness Hm: 50 nm) on the convex
stripes of the light-transmitting substrate thereby to obtain a
wire-grid polarizer having a PET film bonded to the rear side. The
height of aluminum was measured by a film thickness monitor
comprising a quartz vibrator as a film thickness sensor. With
respect to each of the obtained wire-grid polarizers, the width
(Dm) of the fine metallic wires, the transmittance, the reflectance
and the degree of polarization were measured. The results are shown
in Table 2.
TABLE-US-00002 TABLE 2 No. 1 No. 2 No. 3 Pp (nm) 150 150 150 Dp
(nm) 40 40 40 Hp (nm) 200 200 200 Dm (nm) 50 50 50 Contact angle
(.degree.) 93 93 93 Transmittance .largecircle. .largecircle.
.largecircle. Reflectance .largecircle. .largecircle. .largecircle.
Degree of .largecircle. .largecircle. .largecircle.
polarization
INDUSTRIAL APPLICABILITY
[0312] The mold for nanoimprinting of the present invention is
useful for various applications. Specifically, it is useful for
production of an optical member such as a prism, a light guide
plate or a moth eye, a substrate for biotechnology such as a
substrate for a sensing device such as a biosensor or a cell
culture sheet, a member for a semiconductor, and a member for a
magnetic disk. Further, the mold for nanoimprinting of the present
invention is useful also for production of a wire-grid polarizer to
be used as a polarizer of an image display device such as a liquid
crystal display device, a rear-projection television or a front
projector.
[0313] The entire disclosure of Japanese Patent Application No.
2008-148025 filed on Jun. 5, 2008 including specification, claims,
drawings and summary is incorporated herein by reference in its
entirety.
MEANINGS OF SYMBOLS
[0314] 10: mold for nanoimprinting [0315] 12: mold base [0316] 14:
groove [0317] 16: metal oxide layer [0318] 18: release layer [0319]
20: support substrate [0320] 30: photocurable resin composition
[0321] 40: master mold [0322] 42: convex stripe [0323] 50:
wire-grid polarizer [0324] 52: convex stripe [0325] 54:
light-transmitting substrate [0326] 56: fine metallic wire [0327]
58: support substrate [0328] 60: photocurable resin composition
* * * * *