U.S. patent application number 11/020664 was filed with the patent office on 2005-07-21 for donor sheet, color filter, organic el element and method for producing them.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Iwasawa, Masaru, Kiguchi, Hiroshi, Miyashita, Satoru, Shimoda, Tatsuya, Tsukamoto, Yoji.
Application Number | 20050157157 11/020664 |
Document ID | / |
Family ID | 17985926 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050157157 |
Kind Code |
A1 |
Tsukamoto, Yoji ; et
al. |
July 21, 2005 |
Donor sheet, color filter, organic EL element and method for
producing them
Abstract
A donor sheet for transferring an image pattern to an image
receiving element by a thermal imaging process using laser beam,
comprising a base having formed in order on the base a
light-to-heat conversion layer, and a transfer layer containing an
image component which is melted by heating due to an action of the
light-to-heat conversion layer and transferred to the image
receiving element in a patterned form, in which the image component
of the transfer layer contains an ink-repellent or
solvent-repellent compound in an optimized amount. Using the donor
sheet, it becomes possible to produce an separation member such as
partition pattern and black matrix of a color filter by a shortened
manufacturing step with ease and accuracy at high contrast, and can
impart excellent ink repellency to the separation member.
Inventors: |
Tsukamoto, Yoji;
(Sagamihara-shi, JP) ; Iwasawa, Masaru;
(Sagamihara-shi, JP) ; Shimoda, Tatsuya;
(Suwa-shi, JP) ; Miyashita, Satoru; (Suwa-shi,
JP) ; Kiguchi, Hiroshi; (Suwa-shi, JP) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
3M Innovative Properties
Company
St. Paul
MN
Seiko Epson Corporation
Shinjuku-ku
|
Family ID: |
17985926 |
Appl. No.: |
11/020664 |
Filed: |
December 22, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11020664 |
Dec 22, 2004 |
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10111681 |
Apr 25, 2002 |
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10111681 |
Apr 25, 2002 |
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PCT/JP00/07599 |
Oct 27, 2000 |
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Current U.S.
Class: |
347/213 |
Current CPC
Class: |
H01L 51/0004 20130101;
B41M 5/265 20130101; B41M 5/38214 20130101; H01L 51/0013 20130101;
G02B 5/201 20130101; H05B 33/10 20130101; H01L 27/3283 20130101;
H01L 51/0005 20130101; B41M 5/395 20130101; H01L 27/3246 20130101;
B41M 5/42 20130101; G02F 1/133512 20130101; H01L 51/5012 20130101;
Y02E 10/549 20130101; Y10S 430/146 20130101; Y10S 428/917 20130101;
H01L 51/56 20130101 |
Class at
Publication: |
347/213 |
International
Class: |
B41J 002/325 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 1999 |
JP |
11-308840 |
Claims
1. A donor sheet for transferring an image pattern to an image
receiving element by a thermal imaging process using laser beam,
comprising a base, a light-to-heat conversion layer, and a transfer
layer containing an image component which is melted by heating due
to an action of the light-to-heat conversion layer and transferred
to the image receiving element in a patterned form, said layers
being formed in order on the base, characterized in that: the image
component of the transfer layer contains an ink-repellent or
solvent-repellent compound in an optimized amount.
2. The donor sheet according to claim 1, which further comprises an
intermediate layer disposed between the light-to-heat conversion
layer and the transfer layer.
3. The donor sheet according to claim 1, wherein the transfer layer
contains an fluorine-containing compound and/or a silicone
compound.
4. A color filter comprising a transparent substrate, a plurality
of picture elements disposed on a predetermined position of the
substrate, and a partition pattern for separating adjacent picture
elements, characterized in that: the partition pattern on the
substrate is formed by making the transfer layer of the donor sheet
of claim 1 and the surface of the substrate come closely into
contact with each other and transferring the image component of the
transfer layer of the donor sheet in a pattern corresponding to the
partition pattern by a thermal imaging process using laser
beam.
5. The color filter according to claim 4, wherein the picture
elements are formed by forming the partition pattern and applying
ink to a picture element forming area using an ink-jet system.
6. The color filter according to claim 4, wherein the partition
pattern is a black matrix of a liquid crystal display device.
7. A method of producing a color filter comprising a transparent
substrate, a plurality of picture elements disposed on a
predetermined position of the substrate, and a partition pattern
for separating adjacent picture elements, which comprises the steps
of: forming a thin film-like black matrix in a predetermined
pattern on the surface of the substrate; making the surface of the
black matrix side of the substrate and a transfer layer of a donor
sheet comprising a base, a light-to-heat conversion layer, and the
transfer layer containing an image component which is melted by
heating due to an action of the light-to-heat conversion layer and
transferred to the substrate in a patterned form, said layers being
formed in order on the base, come closely into contact with each
other; irradiating laser beam from the base side of the donor sheet
corresponding to the pattern of the black matrix by a thermal image
process using laser beam, thereby to melt the image component of
the transfer layer of the donor sheet with heating and to pile up
the molten image component on the black matrix; and filling an
opening portion surrounded by the formed partition pattern with ink
having a predetermined color using an ink-jet method.
8. The method according to claim 7, wherein the donor sheet 3
transfers an imaging pattern to an image receiving element by a
thermal imaging process using laser beam, comprising a base, a
light-to-heat conversion layer, and a transfer layer containing an
image component which is melted by heating due to an action of the
light-to-heat conversion layers and transferred to the image
receiving element in a patterned form, said layers being formed in
order on the base, characterized in that: the image component of
the transfer layer contains an ink-repellent or solvent-repellent
compound in an optimized amount.
9. A method of producing a color filter comprising a transparent
substrate, a plurality of picture elements disposed on a
predetermined position of the substrate, and a partition pattern
for separating adjacent picture elements, which comprises the steps
of: coating the surface of the substrate to form a thin film of a
black matrix forming material; laying the substrate and a donor
sheet comprising a base, a light-to-heat conversion layer, and a
transfer layer containing an image component which is melted by
heating due to an action of the light-to-heat conversion layer and
transferred to the substrate in a patterned form, said layers being
formed in order on the base, one upon another so that the thin
film-like black matrix forming material and the transfer layer of
the donor sheet come closely into contact with each other;
irradiating laser beam from the base side of the donor sheet
corresponding to a desired pattern of the black matrix by a thermal
image process using laser beam, thereby to melt the image component
of the transfer layer of the donor sheet with heating and to
transfer the melted image component on the thin film-like black
matrix forming material; removing the exposed black matrix forming
material by etching using, as a mask, the image component
transferred to the surface of the thin film-like black matrix
forming material of the substrate in a patterned form; and filling
an opening portion surrounded by the partition pattern formed from
the image component and black matrix as a ground thereof with ink
having a predetermined color using an ink-jet method, thereby to
form picture elements.
10. The method according to claim 9, wherein the donor sheet
transfers an imaging pattern to an image receiving element by a
thermal imaging process using laser beam, comprising a base a
light-to-heat conversion layer, and a transfer layer containing an
image component which is melted by heating due to an action of the
light-to-heat conversion layers and transferred to the image
receiving element in a patterned form, said layers being formed in
order on the base, characterized in that: the image component of
the transfer layer contains an ink-repellent or solvent-repellent
compound in an optimized amount.
11. A method of producing a color filter comprising a transparent
substrate, a plurality of picture elements disposed on a
predetermined position of the substrate, and a light shielding
partition pattern for separating adjacent picture elements, which
comprises the steps of: laying the substrate and a donor sheet
comprising a base, a light-to-heat conversion layer, and a transfer
layer containing an image component which is melted by heating due
to an action of the light-to-heat conversion layer and transferred
to the substrate in a patterned form, said layers being formed in
order on the base, one upon another so that the thin surface of the
substrate and the transfer layer of the donor sheet come closely
into contact with each other; irradiating laser beam from the base
side of the donor sheet corresponding to a desired pattern of the
black matrix by a thermal image process using laser beam, thereby
to melt the image component of the transfer layer of the donor
sheet with heating and to transfer the molten image component on
the substrate; and filling an opening portion surrounded by the
light shielding partition pattern formed from the image component
with ink having a predetermined color using an ink-jet method,
thereby to form picture elements.
12. The method according to claim 11, wherein the donor sheet
transfers an imaging pattern to an image receiving element by a
thermal imaging process using laser beam, comprising a base, a
light-to-heat conversion layer, and a transfer layer containing an
image component which is melted by heating due to an action of the
light-to-heat conversion layers and transferred to the image
receiving element in a patterned form, said layers being formed in
order on the base, characterized in that: the image component of
the transfer layer contains an ink-repellent or solvent-repellent
compound in an optimized amount.
13. An organic EL element comprising a transparent substrate, a
plurality of pixel electrodes disposed on a predetermined position
of the substrate, a partition pattern for separating adjacent pixel
electrode, at least one luminescent layer formed on the pixel
electrodes, and a counter electrode formed on the luminescent
layer, characterized in that: the partition pattern on the
substrate is formed by making the transfer layer of the donor sheet
of claim 1, and the surface of the substrate come closely into
contact with each other and transferring the image component of the
transfer layer of the donor sheet in a pattern corresponding to the
partition pattern by a thermal imaging process using laser
beam.
14. The organic EL element according to claim 13, wherein the
luminescent layer is formed by forming the partition pattern and
applying an organic material using an ink-jet system.
15. A method of producing an organic EL element comprising a
transparent substrate, a plurality of pixel electrodes disposed on
a predetermined position of the substrate, a partition pattern for
separating adjacent pixel electrodes, at least one luminescent
layer formed on the pixel electrodes, and a counter electrode
formed on the luminescent layer, which comprises the steps of:
forming pixel electrodes in a predetermined pattern on the surface
of the substrate; making the surface of the pixel electrodes side
of the substrate and a transfer layer of a donor sheet comprising a
base, a light-to-heat conversion layer, and the transfer layer
containing an image component which is melted by heating due to an
action of the light-to-heat conversion layer and transferred to the
substrate in a patterned form, said layers being formed in order on
the base, come closely into contact with each other; irradiating
laser beam from the base side of the donor sheet corresponding to
the partition pattern by a thermal image process using laser beam,
thereby to melt the image component of the transfer layer of the
donor sheet with heating and to pile up the molten image component
on the substrate; and filling an opening portion surrounded by the
formed partition pattern with an organic material having a
predetermined color using an ink-jet method to form the luminescent
layer.
16. The method according to claim 15, wherein the donor sheet
transfers an imaging pattern to an image receiving element by a
thermal imaging process using laser beam, comprising a base, a
light-to-heat conversion layer, and a transfer layer containing an
image component which is melted by heating due to an action of the
light-to-heat conversion layers and transferred to the image
receiving element in a patterned form said layers being formed in
order on the base, characterized in that: the image component of
the transfer layer contains an ink-repellent or solvent-repellent
compound in an optimized amount.
Description
TECHNICAL FIELD
[0001] The present invention relates to a thermal imaging process
using laser beam and, more particularly, to a donor sheet
(so-called "image forming sheet") used in the process, and an
optical element formed by using the donor sheet, particularly,
color filter and organic EL element and their production methods.
Particularly, the present invention relates to a method of
producing a separation rib of a color filter, a black matrix of a
liquid crystal display device and a partitioning wall (bank) of an
organic EL element. A thermal imaging process using laser beam is
generally referred to as a laser beam thermal transfer method or
LITI (Laser-induced Thermal Imaging) method.
BACKGROUND ART
[0002] As is well known, an ink-jet recording method is one method
of printing methods and is utilized in various fields of image
formation because multi-color fine images can be formed. For
example, the ink-jet recording method is used for formation of a
picture element area in the production of a separation rib
(so-called "partition pattern") of a color filter and a black
matrix of a liquid crystal display device.
[0003] For example, Japanese Unexamined Patent Publication (Kokai)
No. 6-347637 discloses a method of printing a color pattern between
the space of partition patterns (black matrix) containing
fluorine-based water and oil repellency agents, characterized in
that printing is conducted by using ink having a specific surface
tension. In the case of this printing method, the partition pattern
can be produced by known methods such as gravure printing method,
photoresist method, thermal transfer method and the like. Japanese
Unexamined Patent Publication (Kokai) No. 7-35915 discloses a color
filter comprising a transparent substrate, a plurality of picture
elements formed at a predetermined position of the transparent
substrate, and a light shielding black matrix between the space of
the picture elements, characterized in that the light shielding
black matrix is a black resin layer containing a
fluorine-containing compound and/or a silicon-containing compound.
In the case of this color filter, the black matrix can be formed by
using a black photosensitive resin composition as a starting
material according to a photoresist method and the following
formation of the picture elements can be conducted by a printing
method or an ink-jet recording method.
[0004] The reason why the black matrix is formed from the black
resin layer containing the fluorine-containing compound and/or
silicon-containing compound in the above-described color filter is
as follows. That is, when picture elements are formed by the
ink-jet recording method, droplets of ink are ejected and dropped
from a head of an ink-jet printer to an opening portion (picture
element area) surrounded by the black matrix. In that case, ink
having very low viscosity and small surface tension must be used so
as to accurately eject small droplets of ink at high speed and to
quickly spread them in a uniform thickness in the opening portion.
Therefore, it becomes necessary to impart ink repellency (water
repellency and oil repellency) to the black matrix itself for the
purpose of preventing color mixture caused by leakage of ink from
the black matrix. Suitable material includes the above-described
fluorine-containing compound and silicon-containing compound.
[0005] By the way, a conventional method of forming a black matrix
has several problems. For example, in case where the black matrix
is formed from the above-described black photosensitive resin
composition or a similar photosensitive composition prepared by
dispersing black pigments, dyes or metal powders in a resin for the
purpose of imparting a light shielding property according to a
photoresist method, it is essential to conduct various treatments
such as coating, curing, exposure, development, drying and the like
of the resin composition. Therefore, not only the working is
complicated, but also problems such as complexation of a processing
device and increase in manufacturing cost occur. The black matrix
is formed from a metal thin film, e.g. thin film of chromium (Cr)
or chromium oxide (CrO.sub.2) in place of the photosensitive resin
composition. In this case, however, a photoresist method must be
used for patterning the metal thin film and, therefore, the
above-described problems can not be avoided.
[0006] Specifically explaining, the above-described black matrix is
usually formed through a series of processing steps.
[0007] 1) A black matrix precursor made of metal, i.e. a thin film
of a black matrix forming material is formed on a substrate. For
example, a thin film of Cr or a thin film of Cr and CrO.sub.2 is
formed by a sputtering method.
[0008] 2) A photosensitive resin composition is coated on the thin
film of the black matrix in a predetermined film thickness.
Generally, a spin-coating method is used as a coating method.
[0009] 3) The photosensitive resin composition is cured by
prebaking in an oven to obtain a resist film.
[0010] 4) The resist film is subjected to pattern exposure via a
mask with a desired pattern of a black matrix. As an exposure light
source, an ultraviolet lamp and the like is used.
[0011] 5) The unexposed area of the resist film is removed, for
example, by developing with an alkali developer.
[0012] 6) Using, as a mask, the resist film remained without being
removed, the exposed area of the underlying thin film of the black
matrix precursor is removed by dissolving with an etching
solution.
[0013] 7) The residue on etching is removed by washing. As a
result, a black matrix having a desired pattern is obtained.
[0014] 8) The resist film used as the mask is removed.
[0015] Alternatively, the black matrix can also be formed by
dispersing the light shielding material such as black pigment in
the photosensitive resin composition. In this case, the black
matrix precursor, i.e. metal thin film is not used and a glass
substrate is used as the substrate. Accordingly, the steps (1) and
(6) among the above-described processing steps are omitted and
curing is conducted by post baking in place of removal of the
resist in the step (8) and the cured resist is remained as it
is.
[0016] As is understood from the above description, in the method
of forming the black matrix by using a photoresist method, six to
eight processing steps are generally required, whereby processing
devices such as coating device of the resin composition, baking
device, exposure device and the like are also required. A method of
forming a black matrix of metal according to a deposition method,
electroless plating method or the like without using a photoresist
method is also considered, however, a problem about the processing
step is remained and there is not a merit as compared with the
photoresist method.
[0017] Under these circumstances, it is desired to provide a method
of producing a black matrix, capable of directly forming the black
matrix on a substrate without making processing steps and
processing devices complex.
[0018] By the way, Japanese Unexamined Patent Publication (Kokai)
No. 6-347637 cited above discloses a possibility of formation of a
partition pattern according to a thermal transfer method, but it is
not specifically described. Accordingly, a method of producing a
color filter element using a LITI method described in U.S. Pat. No.
5,521,035 will be referred herein with regard to this respect.
According to this method, a black matrix can be formed in a desired
pattern by transferring a coloring agent from a black donor sheet
containing a fluorine surfactant onto a substrate of a color filter
element, utilizing thermal transfer due to laser beam. According to
the black matrix using the LITL method, satisfactory results can be
obtained as compared with a conventional photoresist method, but it
is desired to further improve water repellency and oil
repellency.
[0019] Further, the ink-jet recording method has been utilized in
the formation of a luminescent layer made of an organic compound in
the production of organic EL elements and devices. For example,
International Publication WO98/24271 discloses a method of
manufacturing an organic EL element, comprising the steps of:
forming pixel electrodes on a transparent substrate; forming on
said pixel electrodes by patterning at least one luminescent layer
having a certain color and made of an organic compound; and forming
a counter electrode opposing the pixel electrodes, wherein the
formation of the luminescent layer is performed by means of an
ink-jet method.
DISCLOSURE OF THE INVENTION
[0020] It is an object of the present invention to solve the
above-described problems of the prior art and to provide a donor
sheet, which can produce an separation member of an optical
element, e.g. partition pattern and black matrix of a color filter,
by a shortened manufacturing step with ease and accuracy at high
contrast, and can impart excellent ink repellency, i.e. water
repellency and oil repellency to the separation member.
[0021] It is another object of the present invention to provide a
method of producing an separation member such as black matrix,
partition pattern, etc., capable of directly forming the insulation
member on a substrate using the donor sheet of the present
invention without making processing steps and processing devices
complex.
[0022] It is still another object of the present invention to
provide a color filter provided with the separation member formed
using the donor sheet of the present invention.
[0023] It is a further object of the present invention to provide a
method of producing the color filter provided with the separation
member formed using the donor sheet of the present invention.
[0024] It is, a still another object of the present invention to
provide an organic EL element having partitioning walls formed upon
use of the donor sheet of the present invention, and a production
method thereof.
[0025] The above-described objects as well as other objects will
become apparent from the following detailed description.
[0026] The present invention provides, in an aspect thereof, a
donor sheet for transferring an image pattern to an image receiving
element by a thermal imaging process using laser beam, comprising a
base, a light-to-heat conversion layer, and a transfer layer
containing an image component which is molten by heating due to an
action of the light-to-heat conversion layer and transferred to the
image receiving element in a patterned form, said layers being
formed in order on the base, characterized in that:
[0027] the image component of the transfer layer contains an
ink-repellent or solvent-repellent compound in an optimized
amount.
[0028] In the donor sheet of the present invention, it is preferred
that an intermediate layer is disposed between the light-to-heat
conversion layer and the transfer layer. Further, it is preferred
that the transfer layer contains an fluorine-containing compound or
a silicone compound alone or in combination.
[0029] The present invention provides, in another aspect thereof, a
color filter comprising a transparent substrate, a plurality of
picture elements disposed on a predetermined position of the
substrate, and a partition pattern for separating adjacent picture
elements, characterized in that:
[0030] the partition pattern on the substrate is formed by making
the transfer layer of the donor sheet of the present invention and
the surface of the substrate come closely into contact with each
other and transferring the image component of the transfer layer of
the donor sheet in a pattern corresponding to the partition pattern
by a thermal imaging process using laser beam.
[0031] In the color filter of the present invention, the picture
elements are preferably formed by forming the partition pattern and
applying ink to a picture element forming area using an ink-jet
system.
[0032] In the color filter of the present invention, the partition
pattern can function as a separation rib of the color filter, or
the partition pattern itself has a light shielding property in a
predetermined level and functions as a black matrix of a liquid
crystal display device.
[0033] The present invention provides, in a still another aspect, a
method of producing a color filter comprising a transparent
substrate, a plurality of picture elements disposed on a
predetermined position of the substrate, and a partition pattern
for separating adjacent picture elements, which comprises the steps
of:
[0034] coating the surface of the substrate to form a thin film of
a black matrix forming material;
[0035] laying the substrate and a donor sheet of the present
invention one upon another so that the thin film-like black matrix
forming material and the transfer layer of the donor sheet come
closely into contact with each other;
[0036] irradiating laser beam from the base side of the donor sheet
corresponding to a desired pattern of the black matrix by a thermal
image process using laser beam, thereby to melt the image component
of the transfer layer of the donor sheet with heating and to
transfer the melted image component on the thin film-like black
matrix forming material;
[0037] removing the exposed black matrix forming material by
etching using, as a mask, the image component transferred to the
surface of the thin film-like black matrix forming material of the
substrate in a patterned form; and
[0038] filling an opening portion surrounded by the partition
pattern formed from the image component and black matrix as a
ground thereof with ink having a predetermined color using an
ink-jet method, thereby to form picture elements.
[0039] The present invention also provide a method of producing a
color filter comprising a transparent substrate, a plurality of
picture elements disposed on a predetermined position of the
substrate, and a partition pattern for separating adjacent picture
elements, which comprises the steps of:
[0040] forming a thin film-like black matrix in a predetermined
pattern on the surface of the substrate;
[0041] making the surface of the black matrix side of the substrate
and a transfer layer of a donor sheet of the present invention come
closely into contact with each other;
[0042] irradiating laser beam from the base side of the donor sheet
corresponding to the pattern of the black matrix by a thermal image
process using laser beam, thereby to melt the image component of
the transfer layer of the donor sheet with heating and to pile up
the melted image component on the black matrix; and
[0043] filling an opening portion surrounded by the formed
partition pattern with ink having a predetermined color using an
ink-jet method.
[0044] Furthermore, the present invention provides a method of
producing a color filter comprising a transparent substrate, a
plurality of picture elements disposed on a predetermined position
of the substrate, and a light shielding partition pattern for
separating adjacent picture elements, which comprises the steps
of:
[0045] laying the substrate and a donor sheet of the present
invention one upon another so that the thin surface of the
substrate and the transfer layer of the donor sheet come closely
into contact with each other;
[0046] irradiating laser beam from the base side of the donor sheet
corresponding to a desired pattern of the black matrix by a thermal
image process using laser beam, thereby to melt the image component
of the transfer layer of the donor sheet with heating and to
transfer the melted image component on the substrate; and
[0047] filling an opening portion surrounded by the light shielding
partition pattern formed from the image component with ink having a
predetermined color using an ink-jet method, thereby to form
picture elements.
[0048] Further, the present invention provides an organic EL
element comprising a transparent substrate, a plurality of pixel
electrodes disposed on a predetermined position of the substrate, a
partition pattern for separating adjacent pixel electrodes, at
least one luminescent layer formed on the pixel electrodes, and a
counter electrode formed on the luminescent layer, characterized in
that:
[0049] the partition pattern on the substrate is formed by making
the transfer layer of the donor sheet of the present invention and
the surface of the substrate come closely into contact with each
other and transferring the image component of the transfer layer of
the donor sheet in a pattern corresponding to the partition pattern
by a thermal imaging process using laser beam.
[0050] The present invention also provides a method of producing an
organic EL element comprising a transparent substrate, a plurality
of pixel electrodes disposed on a predetermined position of the
substrate, a partition pattern for separating adjacent pixel
electrodes, at least one luminescent layer formed on the pixel
electrodes, and a counter electrode formed on the luminescent
layer, which comprises the steps of:
[0051] forming pixel electrodes in a predetermined pattern on the
surface of the substrate;
[0052] making the surface of the pixel electrodes side of the
substrate and a transfer layer of a donor sheet comprising a base,
a light-to-heat conversion layer, and the transfer layer containing
an image component which is molten by heating due to an action of
the light-to-heat conversion layer and transferred to the substrate
in a patterned form, said layers being formed in order on the base,
come closely into contact with each other;
[0053] irradiating laser beam from the base side of the donor sheet
corresponding to the partition pattern by a thermal image process
using laser beam, thereby to melt the image component of the
transfer layer of the donor sheet with heating and to pile up the
molten image component on the substrate; and
[0054] filling an opening portion surrounded by the formed
partition pattern with an organic material having a predetermined
color using an ink-jet method to form the luminescent layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0055] FIG. 1 is a schematic sectional view showing a typical
construction of a donor sheet according to the present
invention;
[0056] FIGS. 2A to 2C are a series of sectional views showing in
sequence a mechanism of transfer of an image pattern to an image
receiving element in the donor sheet of FIG. 1;
[0057] FIG. 3 is a sectional view showing one embodiment of a
separation rib of a color filter of the present invention formed by
using the donor sheet of FIG. 1;
[0058] FIG. 4 is a sectional view showing one embodiment of a black
matrix of a liquid crystal display device of the present invention
formed by using the donor sheet of FIG. 1;
[0059] FIGS. 5A to 5E are a series of sectional views showing in
sequence a method of producing the separation rib of FIG. 3
according to the present invention;
[0060] FIGS. 6A to 6D are a series of sectional views showing in
sequence another method of producing the separation rib of FIG. 3
according to the present invention;
[0061] FIGS. 7A to 7D are a series of sectional views showing in
sequence a method of producing the black matrix of FIG. 4 according
to the present invention in order; and
[0062] FIGS. 8A to 8G are a series of sectional views showing in
sequence a method of producing an organic EL element using a donor
sheet of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0063] Subsequently, the embodiments of the present invention will
be described with reference to the accompanying drawings. In the
description with reference to the following drawings, different
part names are sometimes applied to those of the same reference
numerals for convenience's sake.
[0064] The donor sheet according to the present invention is used
as an image forming element so as to transfer an image pattern to
an image receiving element by a thermal imaging process (LITI
method). FIG. 1 shows a typical construction of a donor sheet of
the present invention. As shown in the drawing, a donor sheet 10
comprises a base 1, being formed in order on the base 1, a
light-to-heat conversion layer 2, an intermediate layer 3 and a
transfer layer 4 containing an image component which is molten by
heating due to an action of the light-to-heat conversion layer 2
and transferred to an image receiving element (not shown) in a
patterned form. The donor sheet of the present invention may also
have any additional layer, if necessary.
[0065] In the donor sheet according to the present invention, the
base can be formed from various natural or synthetic materials as
far as the material can meet the requirements to the donor sheet.
The requirements to this base include, for example, transmittance
of laser beam and heat resistance (because heating is conducted by
irradiation of laser beam to transfer the image component), and
proper flexibility, lightness, handling property and mechanical
strength (because the donor sheet is used by applying to the image
receiving element and then peeled off after use). Suitable base
includes various plastic materials such as polyester resin and the
like. The thickness of the base can vary depending on details of
the desired donor sheet and is usually within a range from about
0.01 to 2.54 mm.
[0066] The light-to-heat conversion layer (also referred to as LTHC
layer) supported by the base has a function of converting optical
energy from laser beam irradiation into thermal energy, thereby to
melt an image component in a transfer layer adjacent to the
light-to-heat conversion layer via an intermediate layer and to
transfer and adhere the melted image component to the surface of
the image receiving element. Accordingly, the light-to-heat
conversion layer is preferably made of a light absorbing material
itself, such as carbon black, or made of a layer containing the
light absorbing material dispersed therein. Furthermore, this
light-to-heat conversion layer preferably contains a
photopolymerizable component for the purpose of curing. Suitable
light-to-heat conversion layer is, for example, a layer wherein a
photopolymerizable monomer or oligomer and a photopolymerization
initiator are dispersed in a binder resin. Such a light-to-heat
conversion layer can be usually formed, for example, by coating a
resin composition having a predetermined composition on the surface
of a base according to a conventional coating method such as
spin-coating method, gravure printing method, die coating method or
the like, and drying the resin composition. The thickness of the
light-to-heat conversion layer can vary depending on details and
effect of the desired donor sheet and is usually within a range
from about 0.001 to 10 .mu.m.
[0067] The intermediate layer existing between the light-to-heat
conversion layer and transfer layer has a function of enabling a
uniform light-to-heat conversion action of the light-to-heat
conversion layer. Usually, the intermediate layer can be formed
from a resin material capable of meeting the above-described
requirements. Such an intermediate layer can be usually formed, for
example, by coating a resin composition having a predetermined
composition on the surface of the light-to-heat conversion layer
according to a conventional coating method such as spin-coating
method, gravure printing method, die coating method or the like,
and drying the resin composition in the same manner as in the case
of the light-to-heat conversion layer. The thickness of the
intermediate layer can vary depending on details and effect of the
desired donor sheet and is usually within a range from about 0.05
to 10 .mu.m.
[0068] The transfer layer to be disposed as an outermost layer of
the donor sheet of the present invention contains an image
component which is molten by heating due to an action of the
light-to-heat conversion layer and transferred to the image
receiving element in a patterned form, as described above.
Accordingly, the transfer layer plays a very important role in the
donor sheet of the present invention. As described in detail
hereinafter, the image component of the transfer layer must contain
a fluorine-containing compound and/or a silicone compound in an
optimized amount for the purpose of accomplishing excellent
controlled ink repellency, in addition to the component concerned
directly to image formation, i.e. component which is transferred to
the image receiving element and constitutes its separation
member.
[0069] The transfer layer can transfer the image component
contained therein to the surface of the image receiving element at
high contrast according to the LITI method and adhere it as a
transferred image pattern, and can be formed in any composition as
far as any peel residue is not formed when the used donor sheet is
peeled from the image receiving element. According to use of the
image pattern to be formed from the image component, the
composition suited for each use can be prepared. In case where the
image pattern is used as a separation member, i.e. separation rib
or partition pattern, on the black matrix of the liquid crystal
display device, or case where the image pattern is used both as the
black matrix and separation rib after imparting the light shielding
property to the image pattern, the composition of the transfer
layer can be changed considering the light shielding property. To
improve the light shielding property, a black pigment (e.g. carbon
black, etc.) and other coloring pigments may be added in the
enhanced amount or metal powders may be added.
[0070] In any case, according to the present invention, the water
repellency and oil repellency in high level can be imparted to the
transferred image pattern and the adhesion of the image pattern to
the surface of the image receiving element is good. That is, in the
transfer layer of the present invention, a fluorine-containing
compound, a silicone compound or a mixture thereof as a ink
repellent component is contained in the image component and, at the
same time, the content of the ink repellent component is controlled
within an optimum range. When the content of the ink repellent
component is too large, the adhesion to the base is lowered. On the
other hand, when the content is too small, sufficient water
repellency and oil repellency can not be obtained.
[0071] Thus, according to the present invention, a colored image
pattern with excellent water repellency and oil repellency can be
formed without impairing the image receiving element or its
adhesion to the base when the transfer layer is a colored ink layer
containing a colored image component. In case where such a colored
image pattern is formed on the base and then another colored image
pattern is formed from water-based or oil-based ink at the area
other than that of the colored image pattern using a conventional
technique such as printing method, ink-jet recording method,
brushing method or the like, two colored image patterns can be
separately formed, effectively, thereby making it possible to
effectively prevent defects such as color mixture, unevenness of
thickness or the like. In case where three-color or multi-color
colored image pattern is formed according to the same technique as
described above, an initial colored image pattern derived from the
transfer layer can also be utilized as a partition pattern or
separation rib for separating the other colored image pattern (e.g.
second and third colored image patterns).
[0072] In the present invention, various fluorine-containing
compounds as the ink repellent component can be contained in the
image component so as to obtain the above-described functions and
effects. Suitable fluorine-containing compound includes, but are
not limited to, monomer, oligomer or polymer containing fluorine
atoms in the molecule, fluorine-containing surfactant or the like.
These fluorine-containing compounds are preferably those which are
compatible with or dispersed in a binder resin used as a portion of
the image component in the transfer layer, e.g. acrylic resin or
the like.
[0073] The amount of the above-described fluorine-containing
compound to be added to the image component can vary widely
depending on the kind of the compound, but is preferably optimized
according to a surface tension of ink used for formation of the
colored image pattern. Specifically, the amount is preferably
within a range of not more than 10% by weight, based on the total
amount of the image component.
[0074] In the practice of the present invention, the same amount of
a silicone compound can be used in place of the above-described
fluorine-containing compound or used in combination with it.
Suitable silicone compound includes, but are not limited to,
resins, rubbers, surfactants, coupling agents and the like which
are based on an organic polysiloxane.
[0075] In the present invention, it is necessary to ensure the ink
repellency enhanced in the resulting transferred image pattern,
i.e. water repellency and oil repellency. The term "ink repellency"
used herein has almost the same meaning as that of "water
repellency" defined in Japanese Unexamined Patent Publication
(Kokai) No. 6-347637. That is, the "ink repellency" is defined by a
relation between the surface tension of the surface of the
substrate of the image receiving element to which image pattern is
transferred, that of ink and that of the partition pattern (e.g.
black matrix, etc.). In the present invention, the following
matters are required to obtain enhanced ink repellency:
[0076] (1) The following relationship: Critical surface tension of
the surface of substrate>Surface tension of ink>Critical
surface tension of partition pattern shall be satisfied;
[0077] (2) The critical surface tension of the partition pattern
should be smaller than 35 dyne/cm;
[0078] (3) The critical surface tension of the surface of the
substrate should be 35 dyne/cm or more; and
[0079] (4) Comparing the surface tension of ink with that of the
partition pattern or that of the surface of the substrate, a
difference should be 5 dyne or more.
[0080] The ink repellency required in the present invention can be
defined from another point of view. Preferably, the ink repellency
can be defined by a contact angle of the surface of the substrate
with ink ejected from a head of an ink-jet printer. When using
solvent-based ink whose surface tension is from 20 to 40 mN/m, the
contact angle with ink is preferably within a range from 30 to
55.degree., and more preferably from 40 to 50.degree.. When using
water-based ink having a surface tension of 40 to 55 mN/m, the
contact angle with ink is preferably within a range from 60 to
80.degree.. When the contact angle with ink to be used is smaller
than the above-described range, color mixture with the other color
in adjacent picture element area occurs and, therefore, a desired
color filter can not be produced. On the other hand, when the
contact angle with ink to be used is larger than the
above-described range, color mixture with the other color in
adjacent picture element area does not occur. However, ink retained
in the picture element area comes into a state where the center
portion is exclusively protuberant (concave state) and, therefore,
the picture element center portion is protuberant as compared with
the peripheral portion even after drying ink, resulting in color
spot.
[0081] A mechanism of transfer of the image component in the donor
sheet of the present invention will be apparent from FIGS. 2A to
2C. FIGS. 2A to 2C are a series of sectional views showing in
sequence a mechanism of transfer of an image pattern to an image
receiving element in the donor sheet of FIG. 1.
[0082] As shown in FIG. 2A, a donor sheet 10 having the same
construction as that of the donor sheet shown in FIG. 1 are
prepared, and then this donor sheet and a substrate 11 are laid one
upon another so that a transfer layer 4 and the substrate 11 as an
image receiving element come closely into contact with each other.
Then, the donor sheet 10 of the resulting laminate is irradiated
with laser beam L from the side of the base 1 in a predetermined
pattern. The pattern of laser beam L corresponds to an image
pattern to be transferred to the image receiving element.
[0083] As a result of pattern irradiation of laser beam, optical
energy is converted into thermal energy by an action of a
light-to-heat conversion layer 2 adjacent to the base 1 of the
donor sheet 10 and the resulting thermal energy is further evened
by an action of an intermediate layer 3. Therefore, as shown in
FIG. 2B, an image component 14 contained in the transfer layer 4 is
molten by heating in a patterned form, and then transferred and
adhered to the substrate 11 as the image receiving element.
[0084] FIG. 2C shows a transferred image pattern 7 formed on the
substrate 11 as described above. This image pattern 7 is made
closely into contact with the substrate through a strong force.
Since this image pattern 7 has sufficiently high ink repellency,
oozing of ink to the other area or color mixture with the color of
adjacent area can be prevented in case where ink is adhered to the
non-image pattern area using an ink-jet recording method.
Accordingly, when using such a donor sheet, color mixture or
unevenness of thickness of color stripe can be effectively
prevented in the production of the color filter using the ink-jet
recording method.
[0085] Also, the present invention is directed to a color filter
comprising a transparent substrate, a plurality of picture elements
disposed at a predetermined position on the substrate, and a
partition pattern for separating adjacent picture elements. In such
a color filter, the partition pattern for separating adjacent
picture elements (e.g. separation rib or black matrix) can be
formed by making the transfer layer of the donor sheet of the
present invention and the surface of the substrate come closely
into contact with each other using the donor sheet of the present
invention according to the above-described technique, and
transferring the image component of the transfer layer of the donor
sheet in a pattern corresponding to the partition pattern by a
thermal imaging process using laser beam.
[0086] FIG. 3 is a sectional view showing one embodiment of a
separation rib of a color filter of the present invention formed by
using the donor sheet of FIG. 1. As shown in the drawing, a
partition pattern composed of a black matrix 15 and a separation
rib 7 is formed at a predetermined area (partition pattern area) of
a substrate 11. Picture elements can be formed by applying ink 6 to
a picture element area 8 by an ink-jet printing method after
forming the partition pattern.
[0087] FIG. 4 shows one modification of FIG. 3 and is a sectional
view showing one embodiment of a black matrix of a liquid crystal
display device of the present invention formed by using the donor
sheet of FIG. 1. As is shown in the drawing, the black matrix 15 is
omitted and thus the separation 7 can also serve as a black
matrix.
[0088] The color filters shown in FIGS. 3 and 4 can be preferably
produced by the steps shown in order in FIGS. 5A to 5E, FIGS. 6A to
6D and FIGS. 7A to 7D. It will be appreciated that the embodiments
shown in the drawings are illustrative and various modifications
and improvements may be made within the scope of the present
invention.
[0089] FIGS. 5A to 5D are a series of sectional views showing in
sequence a method of producing the separation rib of FIG. 3
according to the present invention.
[0090] As shown in FIG. 5A, a transparent substrate 11 suited for
production of a color filter is provided. Suitable substrate
includes various glass substrates used conventionally in this
technical field, but a transparent plastic substrate can also be
used, if necessary.
[0091] Then, the surface of the provided substrate 11 is coated
with a thin film of a black matrix forming material, as shown in
FIG. 5B. The usable black matrix forming material includes, for
example, metal or oxide thereof, such as chromium (Cr), chromium
oxide (CrO.sub.2) or the like. The thin film of the black matrix
forming material can be formed in a predetermined film thickness by
using various film forming methods including sputtering method,
deposition method and the like. This thin film may be a single
layer or a multi-layer of two or more layers. The thickness of the
black matrix forming material can vary widely, but is preferably
within a range from 0.01 to 1 .mu.m, and more preferably from 0.1
to 0.25 .mu.m. In such way, a thin film 5 as a black matrix
precursor is formed on the substrate 11.
[0092] As shown in FIG. 5C, the donor sheet 10 of the present
invention is placed on the substrate 11 via the thin film 5, and
then they are laid on upon another so that the thin film-like black
matrix forming material 5 and a transfer layer (not shown) of the
donor sheet 10 come closely into contact with each other.
[0093] Laser beam L is irradiated from the substrate side of the
donor sheet 10 in a pattern corresponding to a desired pattern of
the black matrix by a thermal imaging process using laser beam, and
then an image component of the transfer layer of the donor sheet 10
is molten by heating and transferred onto the thin film-like black
matrix forming material 5.
[0094] As shown in FIG. 5D, there can be obtained an image
component 7 transferred on the surface of the thin film-like black
matrix forming material 5 of the substrate 11 in a patterned form.
A matrix-like pattern of the image component 7 serves as a
separation rib in the finally obtained color filter and its
thickness can vary widely depending on the desired effect, but is
preferably within a range from 0.5 to 3.0 .mu.m, and more
preferably from 1.5 to 2.5 .mu.m. The thickness of less than 0.5
.mu.m does not ensure a height of separation rib sufficient to
receive ink, whereas the thickness of more than 3.0 .mu.m causes a
reduction of flatness of the color filter produced upon drying of
filter.
[0095] Using the matrix-like pattern of the image component 7 as a
mask, the exposed thin film-like black matrix forming material 5 is
removed by etching. As an etchant, various acids can be used or a
dry etching may also be used, if necessary. The residue, which was
not removed by etching, can be completely removed by a treatment
such as washing or the like.
[0096] As a result of the etching, as shown in FIG. 5E, there can
be obtained a substrate 11 having a partition pattern composed of a
black matrix 15 and a separation rib 7. The separation rib 7 used
as the mask for formation of the black matrix 15 may also be
removed by alkaline solution washing or any other peeling
techniques.
[0097] Subsequently, although not shown in the drawing, an opening
portion surrounded by a partition pattern formed of a separation
rib and a black matrix forming material as a ground (this portion
is referred to as a picture element area) is preferably filled with
ink having a predetermined color by an ink-jet recording method,
thereby to form picture elements (see FIG. 3).
[0098] A color filter comprising a transparent substrate, a
plurality of picture elements disposed on a predetermined position
of the substrate, and a partition pattern for separating adjacent
picture elements, as the color filter of the present invention, is
obtained through processing steps whose number is smaller than that
of a conventional method, using a simplified processing device.
Since the separation rib 7 is superior in ink repellency in this
color filter, oozing of ink to the other area or color mixture with
the color of adjacent area can be prevented in case where picture
elements are formed by filling the picture element area with ink
using an ink-jet recording method.
[0099] FIGS. 6A to 6D are a series of sectional views showing in
sequence another method of producing the separation rib of FIG. 3
according to the present invention. The method shown in the drawing
can be carried out basically in the same manner as that shown in
FIGS. 5A to 5E described previously, except for changing the
procedure of the treatment.
[0100] First, as shown in FIG. 6A, a thin film-like black matrix 15
is formed on the surface of a prepared transparent substrate 11 in
a predetermined pattern. The black matrix 15 can be formed by
depositing Cr in a form of a thin film using a sputtering
method.
[0101] Then, as shown in FIG. 6B, the surface of the black matrix
15 of the substrate 11 and a transfer layer (not shown) of the
donor sheet of the present invention are made come closely into
contact with each other. Furthermore, as shown in FIG. 6C, laser
beam L is irradiated from the substrate side of the donor sheet 10
in a pattern corresponding to the pattern of the black matrix 15 by
a thermal imaging process using laser beam.
[0102] As a result of pattern irradiation of laser beam, the image
component of the transfer layer of the donor sheet 10 can be melted
by heating and then piled up as a separation rib 7 on the black
matrix 15, as shown in FIG. 6D. As a result, a partition pattern
composed of the black matrix 15 and the separation rib 7 disposed
thereon is obtained.
[0103] Subsequently, as described previously with reference to FIG.
3, picture elements are formed by filling an opening portion
(picture element area) surrounded by the formed partition pattern
with ink having a predetermined color using an ink-jet method.
Therefore, a color filter comprising a transparent substrate, a
plurality of picture elements disposed on a predetermined position
of the substrate, and a partition pattern for separating adjacent
picture elements can be obtained.
[0104] FIGS. 7A to 7D are a series of sectional views showing in
sequence a method of producing the black matrix of FIG. 4 according
to the present invention. This method can also be carried out
basically in the same manner as those shown in FIGS. 5A to 5E and
FIGS. 6A to 6D described previously. In the case of this method,
since the separation rib can also act as the black matrix, it is
essential that the composition of the image component of the
transfer layer is determined so that the transfer layer can provide
a separation rib superior in light shielding property. This
description was stated previously in the item of the donor
sheet.
[0105] First, a transparent substrate 11 as shown in FIG. 7A is
prepared, and the substrate and donor sheet 10 of the present
invention are laid one upon another as shown in FIG. 7B. In this
case, attention is paid so that the surface of the substrate 11 and
the transfer layer (not shown) of the donor sheet 10 come closely
into contact each other.
[0106] Then, a thermal imaging process using laser beam is carried
out. This process is carried out by irradiating laser beam L from
the substrate side of the donor sheet 10 in a pattern corresponding
to a desired pattern of the black matrix, as shown in FIG. 7C. As a
result of pattern irradiation of laser beam, the image component of
the transfer layer of the donor sheet 10 can be melted by heating
and then transferred onto the substrate. As shown in FIG. 7D, a
light shielding partition pattern 7 serving both as the black
matrix and separation rib is formed.
[0107] Subsequently, although not shown, picture elements are
formed by filling an opening portion (picture element area)
surrounded by the light shielding partition pattern formed from the
image component with ink having a predetermined color using an
ink-jet method (see FIG. 4).
[0108] As a result, a color filter having excellent
characteristics, comprising a transparent substrate, a plurality of
picture elements disposed on a predetermined position of the
substrate, and a partition pattern for separating adjacent picture
elements, can be obtained by a very simple technique using a
simplified processing device.
[0109] According to the present invention, organic EL elements or
devices and other optical devices can be advantageously produced,
in addition to the production of the color filters. As described
above, the organic EL element of the present invention comprises a
transparent substrate, a plurality of pixel electrodes disposed on
a predetermined position of the substrate, a partition pattern for
separating adjacent pixel electrodes, at least one luminescent
layer formed on the pixel electrodes, and a counter electrode
formed on the luminescent layer, and is characterized in that the
partition pattern on the substrate is formed by making the transfer
layer of the donor sheet of the present invention and the surface
of the substrate come closely into contact with each other and
transferring the image component of the transfer layer of the donor
sheet in a pattern corresponding to the partition pattern by a
thermal imaging process using laser beam. In the organic EL element
of the present invention, the luminescent layer-is preferably
formed by forming the partition pattern, followed by applying an
organic material to a luminescent layer-forming area using an
ink-jet system.
[0110] The organic EL element having partition pattern, i.e.,
partitioning wall (bank), according to the present invention may
have a wide variety of embodiments or structures, and accordingly
they can be produced in accordance with the different methods.
[0111] FIGS. 8A to 8G illustrate one embodiment of the organic EL
element of the present invention, along with a production process
thereof. The organic EL element of the present invention will be
described hereinafter referring to the illustrated element, to
which the present invention should not be restricted.
[0112] The illustrated organic EL element is a full color organic
EL element with three colors, and, as is illustrated, it can be
produced by the step (FIG. 8A) of forming pixel electrodes 21, 22
and 23 or a transparent substrate 24, the step (FIG. 8B) of
conducting a LITI method using donor sheet 10 of the present
invention, the step (FIG. 8C) of forming partitioning walls (banks)
25, the step (FIG. 8D) of patterning luminescent layers 26 and 27,
made of an organic compound, on the respective pixel electrodes,
the step (FIG. 8E) of forming a luminescent layer 28, and the step
(FIG. 8F) of forming a cathode 31. The formation of the luminescent
layer 26 and 27 can be carried out by means of an ink-jet
method.
[0113] The transparent substrate 24 functions not only as a support
but also as a surface through which light is taken out.
Accordingly, the material for the transparent substrate 24 is
selected by taking the light-permeability, thermal stability and
the like into consideration. As for examples of the material to be
used for the transparent substrate, glass, transparent plastic or
the like can be mentioned, and among these materials, a substrate
made of glass is particularly preferable in view of its excellent
heat resistance.
[0114] As is shown in FIG. 8A, first, pixel electrodes 21, 22 and
23 are formed on the transparent substrate 24. As for examples of
methods of forming these pixel electrodes, photolithography, vacuum
deposition method, sputtering method and pyrosol method can be
mentioned. Among these methods, the photolithography is
particularly preferable. As for these pixel electrodes, it is
preferred that they are formed into transparent pixel electrodes.
As for the materials constituting the transparent pixel electrodes,
a tin oxide film, an ITO film and a composite oxide film of indium
oxide and zinc oxide can be mentioned.
[0115] Next, as shown in FIG. 8C partitioning walls (banks) 25 are
formed to fill the spaces between the pixel electrodes. In this
way, it is possible to improve the contrast, to prevent mixing of
colors of the luminescent materials, and to prevent light from
leaking between the pixels.
[0116] The formation of the partitioning walls 25 can be carried
out in accordance with the LITI method which was applied to the
formation of the partition pattern in the above-described
production of the color filter. That is, as is shown in FIG. 8C, a
donor sheet 10 having the same construction as that of the donor
sheet shown in FIG. 1 are prepared, and then this donor sheet and a
transparent substrate 24 are laid one upon another so that a
transfer layer and the substrate come closely into contact with
each other. Then, the donor sheet 10 of the resulting laminate is
irradiated with laser beam L from the side of the base of the donor
sheet in a predetermined pattern. The pattern of laser beam L
corresponds to a pattern of the partitioning walls 25 to be
transferred to the transparent substrate 24.
[0117] As a result of pattern irradiation of laser beam, optical
energy is converted into thermal energy by an action of a
light-to-heat conversion layer adjacent to the base of the donor
sheet 10 and the resulting thermal energy is further evened by an
action of an intermediate layer. Therefore, an image component
contained in the transfer layer is melted by heating in a patterned
form, and then transferred and adhered to the substrate 24. FIG. 8C
shows a transferred pattern of the partitioning walls 25 formed on
the substrate 24. This pattern of the partitioning walls 25 is made
closely into contact with the substrate 24 through a strong force.
Since this pattern has sufficiently high ink repellency, oozing of
ink to the other area or color mixture with the color of adjacent
area can be prevented in case where ink is adhered to the non-image
pattern area using an ink-jet recording method. Color mixture or
unevenness of thickness of color stripe can be effectively
prevented in the production of the color filter using the ink-jet
recording method.
[0118] As for the materials constituting the banks 25, no
particular limitation is imposed, if they have a resistance to the
solvent for the EL material. For example, organic material such as
acrylic resin, epoxy resin, photosensitive polyimide and the like;
and inorganic material such as liquid glass and the like can be
mentioned. In this regard, it is to be noted that the banks 25 may
be formed into a black resist which is formed by mixing carbon
black and the like into the above-mentioned material. Of course, it
is necessary that these materials satisfy the requirements for the
donor sheet of the present invention.
[0119] Further, organic luminescent layers are formed respectively
on the pixel electrodes according to a predetermined pattern. In
this case, it is preferable to provide organic luminescent layers
with three color types. In this connection, it is preferred that at
least one layer among these organic luminescent layers is formed by
an ink-jet method.
[0120] In the illustrated embodiment, a red luminescent layer 26
and a green luminescent layer 27 are formed on the pixel electrodes
21 and 22, respectively, by the ink-jet method. That is, as is
shown in FIG. 8D, a pixel of one of the three primary colors
including red, green and blue or a pixel of at least one color
which is intermediate between the primary colors is formed by
dissolving or dispersing a droplet 6 of the luminescent material in
a solvent to obtain a discharge liquid and then discharging a
droplet 6 of the discharge liquid from a head of an ink-jet device
(not shown).
[0121] According to such an ink-jet method, it is possible to carry
out fine patterning in a simple manner and in a short time.
Further, it is also possible to control easily and freely the
luminescent characteristics such as color balance and brightness
(luminance) by adjusting the thickness of the layer through
adjustment of the discharge amount of the ink or by adjusting the
ink concentration.
[0122] When the organic luminescent materials are conjugated
polymer precursors, the luminescent layers are formed by
discharging the luminescent materials by the ink-jet method to
carry out patterning, and then conjugating (to form a film) the
precursor components by heating or irradiation with light or the
like.
[0123] Next, as shown in FIG. 8E, a blue luminescent layer 28 is
formed on the red luminescent layer 26, the green luminescent layer
27 and the pixel electrode 23. In this way, it is possible not only
to form layers having the three primary colors including red, green
and blue, but also to bury the level differences between the banks
25 and each of the red luminescent layer 26 and the green
luminescent layer 27 so as to be flattened.
[0124] No particular limitation is imposed upon the forming method
for the blue luminescent layer 28, and it is possible to form the
layer using the general film forming method known as deposition
method or wet method, for instance, or using the ink-jet
method.
[0125] Further, the blue luminescent layer 28 can be formed of an
electron injection and transfer material such as aluminum
quinolynol complex. In this case, it is possible to promote the
injection and transfer of the carriers so as to improve the
luminous efficiency. Furthermore, when such a blue luminescent
layer 28 is laminated with red and green luminescent layers formed
of a hole injection and transfer material, it is also possible to
inject and transfer the electrons and the holes from the respective
electrodes into these laminated luminescent layers with appropriate
balance, thereby enabling to improve the luminous efficiency.
[0126] In the illustrated embodiment, organic luminescent layers
for two colors are formed by the ink-jet method while the layer for
the remaining one color is formed by a different method. Therefore,
according to this embodiment, even when a luminescent material
which is not so suited for the ink-jet method is used, a full color
organic EL element can be formed by using such a material in a
combination with other organic luminescent materials that are
suited for the ink-jet method, so that the latitude in the design
for the EL element will be expanded. Of course, if desired, all the
luminescent layers may be formed by the ink-jet method.
[0127] Finally, as is shown in FIG. 8F, a cathode (a counter
electrode) 31 is formed, thereby the organic EL element of the
present invention is completed. In this case, it is preferred that
the cathode 31 is formed into a metallic thin film electrode, and
as for examples of the metal for forming the cathode, Mg, Ag, Al,
Li and the like can be mentioned. In addition, a material having
small work function can be used for the material for the cathode
31, and for example, alkali metal, alkali earth metal such as Ca
and the like, and alloys containing these metals can be used. Such
a cathode 31 may be formed using a deposition method, a sputtering
method or the like.
[0128] Further, as shown in FIG. 8G, a protective film 32 may be
formed on top of a cathode 31. By forming such a protective film
32, it becomes possible to prevent deterioration, damage, peeling
and the like from occurring in the cathode 31 and in the
luminescent layers 26, 27 and 28. As for materials for constructing
the protective film 32, epoxy resin, acrylic resin, liquid glass
and the like can be mentioned. Further, as for examples of the
forming method for the protective film 32, spin coating method,
casting method, dipping method, bar coating method, roll coating
method, capillary method and the like can be mentioned.
[0129] In this embodiment, it is preferable that the luminescent
layers are formed of an organic compound, and it is more preferable
that these luminescent layers are formed of a polymer organic
compound. By providing such luminescent layers that are formed of
the organic compound, it is possible to obtain high brightness
surface luminescence at low voltages. Further, since luminescent
materials can be selected from wide range of field, a rational
design for the luminescent element becomes possible. In particular,
polymer organic compounds have an excellent film formation
property, and the luminescent layers composed of polymer organic
compounds have an extremely good durability. Further, these polymer
organic compounds have a band gap in the visible region and a
relatively high electrical conductivity. Among such polymer organic
compounds, a conjugated polymer can exhibit such properties
prominently.
[0130] As for materials for the organic luminescent layers, polymer
organic compound itself, precursor of conjugated organic polymer
compound which is to be conjugated (to form a film) by heating or
the like, and other materials are used.
[0131] In the above descriptions referring to the attached
drawings, use of the donor sheet of the present invention in the
formation of the separation ribs of the color filter, black matrix
of the liquid crystal display device and partitioning walls of the
organic EL element according to the LITI method was explained in
detail, however, it should be noted that the donor sheet of the
present invention can be advantageously applied to the formation of
other separation members. In particular, the donor sheet of the
present invention is noticeable, because it can be used to form
separation members for all the materials capable of being patterned
in accordance with the ink-jet method.
EXAMPLES
[0132] The present invention will be described by way of the
examples thereof. It is appreciated that the present invention is
not limited to the following examples.
Example 1
[0133] (1) Production of Donor Sheet
[0134] A donor sheet comprising a base, a light-to-heat conversion
layer, an intermediate layer and a transfer layer, said layers
being formed on the base, was produced according to the following
procedure.
[0135] After a polyethylene terephthalate (PET) film having a
thickness of 75 .mu.m was prepared as a base, a light-to-heat
conversion layer (LTHC layer), an intermediate layer and a transfer
layer each having the following composition and film thickness were
formed in the order as described below. The (LTHC layer) and the
intermediate layer were coated with die coating method, followed by
being cured by irradiation with ultraviolet rays, and then the
transfer layer was similarly formed with die coating method.
1 Light-to-heat conversion layer Carbon black 100.0% by weight
(trade name: "Raben 760", manufactured by Colombian Carbon Co.)
Dispersant 8.9% by weight (trade name: "Disperbyk 161",
manufactured by BYK-Cheimie Co.) Vinyl butyral resin 17.9% by
weight (trade name: "Burvar B-98", manufactured by Nippon Monsanto
Co.) Carboxyl group-containing 53.5% by weight acrylic resin (trade
name: "Joncryi 67", manufactured by Jonson Polymer Co.) Acrylic
oligomer 834.0% by weight (trade name: "Evecryl EB629",
manufactured by UCB Radcure Co.) Carboxyl group-containing 556.0%
by weight acrylic resin (trade name: "Elvacite 2669", manufactured
by ICI Co.) Photopolymerization initiator 45.2% by weight (trade
name: "Irgacure 369", manufactured by Ciba Geigy Co.)
Photopolymerization initiator 6.7% by weight (trade name: "Irgacure
184", manufactured by Ciba Geigy Co.) Total 1622.3% by weight Solid
content: 30% in PMA:MEK = 60:40 Film thickness: 5 .mu.m
[0136]
2 Intermediate layer Vinyl butyral resin 4.76% by weight (trade
name: "Burvar B-98", manufactured by Nippon Monsanto Co.) Carboxyl
group-containing 14.29% by weight acrylic resin (trade name:
"Joncryi 67", manufactured by Jonson Polymer Co.) Acrylic monomer
79.45% by weight (trade name: "Sartomer 351", manufactured by
Sartomer Co.) Photopolymerization initiator 4.50% by weight (trade
name: "Irgacure 369", manufactured by Ciba Geigy Co.) Fluorescent
dye 1.12% by weight Total 104.12% by weight Solid content: 9.3% in
IPA:MEK = 90:10 Film thickness: 1 .mu.m
[0137]
3 Transfer layer Pigment, Dioxane Violet 50.0% by weight (trade
name: "Hostaperum Violet RL NF", manufactured by BASF Co.) Pigment,
Disazoyellow 50.0% by weight (trade name: "ECY-204", manufactured
by Dainippon Seika Industries Co.) Dispersant 15.0% by weight
(trade name: "Disperbyk 161", manufactured by BYK-Cheimie Co.)
Carboxyl group-containing 268.8% by weight acrylic resin (trade
name: "CARBOSET GA1162", manufactured by B.F. Goodrich Co.)
Fluororesin 0.05% by weight (trade name: "FC55/35/10", manufactured
by 3M Co.) Epoxy crosslinking agent 111.1% by weight (trade name:
"SU8", manufactured by Shell Chemical Co.) Total 497.44% by weight
Solid content: 13.5% in PMA:MIBK:BC = 60:30:10 BC = butylcellosolve
Film thickness: 2.0 .mu.m
[0138] (2) Production of Black Matrix
[0139] Using an exclusive LITI machine (laser beam thermal transfer
machine, wavelength of laser beam: 1064 nm), a black matrix was
produced on a glass substrate. The donor sheet produced in the
previous step and the glass substrate were laid one upon another,
and then laser beam was irradiated in a striped form under the
conditions of an output of 11 W, a scan speed of 15 m/s and an
irradiation width of 20 .mu.m. Then, baking was conducted in an
oven at 230.degree. C. for 1 hour so as to cure and make the
transfer portion come closely into contact. As a result, a black
matrix having a width of 20 .mu.m and a thickness of 2.0 .mu.m was
formed on the glass substrate.
[0140] [Evaluation Test]
[0141] Determination of contact angle and critical surface
tension:
[0142] To evaluate an ink repellency of the black matrix (partition
pattern) produced in accordance with the above-described process, a
contact angle of the pattern with ink was determined. The contact
angle was 65.degree. as shown in the following Table 1. Further, a
critical surface tension was calculated from the contact angles
with different solvents in each of the opening area, surrounded by
the partition pattern, and the pattern area. As is shown in the
following Table 1, the critical surface tension was
[0143] 55 dyne/cm in the opening area, and
[0144] 33 dyne/cm in the pattern area.
[0145] Note that a water-based color ink (red, green and blue;
surface tension 45 dyne/cm) was used in the above
determination.
[0146] Determination of color mixture and color spot in the color
filter:
[0147] Using the glass substrate with black matrix (partition
pattern) produced in accordance with the above-described process, a
color filter was produced to evaluate color mixture and color spot
in each picture element area of the filter.
[0148] Using the ink jet printing device, water-based color ink
(red, green and blue) was poured into each of the opening areas on
the glass substrate having the previously produced partition patter
to form red, green and blue colored areas, followed by drying at
200.degree. C. for 10 minutes. In each of the thus produced red,
green and blue picture element areas, presence or absence of color
mixture and color spot was observed by using an optical microscope
and a microscopic spectrometer. The presence or absence of color
mixture was evaluated from the migration of ink into the adjacent
picture element area. With regard to the color spot, samples where
no color spot was observed were rated "good (.circle-w/dot.)",
samples where color spot was slightly observed, but permissible
were rate "fair (.largecircle.)", and samples where severe color
spot was observed were rated "bad (.times.)". For the samples
showing color mixture, the observation of the color spot was
omitted. As is shown in the following Table 1, no color mixture
observed and the color spot was rated "fair" in this example.
Example 2
[0149] The procedure of Example 1 was repeated with the proviso
that, in this example, a glass substrate with chromium (Cr) black
matrix (hereinafter, referred to as "CrBM") was used in place of
the glass substrate, and a separation rib was produced on the black
matrix of the substrate in accordance with the following
method.
[0150] Using an exclusive LITI machine (laser beam thermal transfer
machine, wavelength of laser beam: 1064 nm), a separation rib was
laid on a glass substrate provided with a black matrix. The donor
sheet produced in Example 1 was laid on the black matrix side of
the glass substrate, and then laser beam was irradiated from the
side of the donor sheet in the same striped pattern as that of the
black matrix under the conditions of an output of 11 W, a scan
speed of 15m/s and an irradiation width of 20 .mu.m. Then, baking
was conducted in an oven at 230.degree. C. for 1 hour so as to cure
and adhere the transferred portion. A separation rib having a width
of 20 .mu.m and a thickness of 2.0 .mu.m was formed on the black
matrix of the glass substrate.
[0151] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substrate with the partition pattern
(black matrix plus separation rib). As shown in the following Table
1, the contact angle between the ink and the pattern was
65.degree., the critical surface tension of the pattern was 33
dyne/cm, no color mixture was observed, and the color spot was
rated "fair".
Comparative Example 1
[0152] The procedure of Example 1 was repeated with the proviso
that, in this example, for the comparison purpose, a solvent-based
color ink (red, green and blue; surface tension 30 dyne/cm) was
used in place of the water-based ink.
[0153] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix). As shown in the following Table 1, the contact
angle was 7.degree., the critical surface tension was 33 dyne/cm,
and color mixture was observed.
Comparative Example 2
[0154] The procedure of Example 1 was repeated with the proviso
that, in this example, for the comparison purpose, an amount of the
fluororesin (trade name "FC55/35/10", available from 3M Co.) added
to the transfer layer was changed from 0.05% by weight to 0.51% by
weight.
[0155] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix). As shown in the following Table 1, the contact
angle was 88.degree., the critical surface tension was 27 dyne/cm,
no color mixture was observed, but the picture element had a
convexity, and the color spot was rated "bad".
Comparative Example 3
[0156] The procedure of Example 1 was repeated with the proviso
that, in this example, for the comparison purpose, a solvent-based
color ink was used as in Comparative Example 1, and an amount of
the fluororesin added was changed to 0.51% by weight as in
Comparative Example 2.
[0157] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix). As shown in the following Table 1, the contact
angle was 30.degree., the critical surface tension was 27 dyne/cm,
and color mixture was observed.
Example 3
[0158] The procedure of Example 1 was repeated with the proviso
that, in this example, a solvent-based color ink was used as in
Comparative Example 1, and an amount of the fluororesin added was
changed from 0.05% by weight to 7.62% by weight.
[0159] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix). As shown in the following Table 1, the contact
angle was 45.degree., the critical surface tension was 20 dyne/cm,
no color mixture was observed, and the color spot was rated
"good".
Example 4
[0160] The procedure of Example 2 was repeated with the proviso
that, in this example, a solvent-based color ink was used as in
Comparative Example 1, and an amount of the fluororesin added was
changed from 0.05% by weight to 7.62% by weight.
[0161] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix plus separation rib). As shown in the following Table
1, the contact angle was 45.degree., the critical surface tension
was 20 dyne/cm, no color mixture was observed, and the color spot
was rated "good".
Example 5
[0162] The procedure of Example 3 was repeated with the proviso
that, in this example, a thickness of the baked transfer layer
(that is, a height of pattern) was changed from 2 .mu.m to 1.6
.mu.m.
[0163] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix). As shown in the following Table 1, the contact
angle was 45.degree., the critical surface tension was 20 dyne/cm,
no color mixture was observed, and the color spot was rated
"good".
Comparative Example 4
[0164] The procedure of Example 3 was repeated with the proviso
that, in this example, for the comparison purpose, a thickness of
the baked transfer layer (that is, a height of pattern) was changed
from 2 .mu.m to 0.9 .mu.m.
[0165] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix). As shown in the following Table 1, the contact
angle was 45.degree., the critical surface tension was 20 dyne/cm,
and color mixture was observed.
Example 6
[0166] The procedure of Example 1 was repeated with the proviso
that, in this example, a solvent-based color ink was used as in
Comparative Example 1, and an amount of the fluororesin added was
changed from 0.05% by weight to 10.16% by weight.
[0167] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix). As shown in the following Table 1, the contact
angle was 50.degree., the critical surface tension was 18 dyne/cm,
no color mixture was observed, and the color spot was rated
"good".
Comparative Example 5
[0168] The procedure of Example 1 was repeated with the proviso
that, in this example, for the comparison purpose, a solvent-based
color ink was used as in Comparative Example 1, and an amount of
the fluororesin added was changed from 0.05% by weight to 55.00% by
weight.
[0169] The evaluation test similar to that of Example 1 was carried
out using the resulting glass substate with the partition pattern
(black matrix). As shown in the following Table 1, the contact
angle was 60.degree., the critical surface tension was 15 dyne/cm,
no color mixture was observed, but the picture element had a
convexity, and the color spot was rated "bad".
Example 7
[0170] The procedure of Example 3 was repeated with the proviso
that, in this example, the BM substrate was used as in Example 2,
in place of the glass substrate. The evaluation test similar to
that of Example 1 was carried out using the resulting glass
substate with the partition pattern (black matrix). As shown in the
following Table 1, the contact angle was 45.degree., and the
critical surface tension was 20 dyne/cm.
4 TABLE 1 Critical surface Pattern Contact tension.sup.3) (dyne/cm)
Height angle.sup.2) Opening Pattern Color Color Example No.
Ink.sup.1) Substrate (.mu.m) (.degree.) area area mixture
spot.sup.4) Example 1 b) Glass 2 65 55 33 None .largecircle.
Example 2 b) CrBM 2 65 55 33 None .largecircle. Comp. Ex. 1 a)
Glass 2 7 55 33 Observed -- Comp. Ex. 2 b) Glass 2 88 55 27 None X
Comp. Ex. 3 a) Glass 2 30 55 27 Observed -- Example 3 a) Glass 2 45
55 20 None .circleincircle. Example 4 a) CrBM 2 45 55 20 None
.circleincircle. Example 5 a) Glass 1.6 45 55 20 None
.circleincircle. Comp. Ex. 4 a) Glass 0.9 45 55 20 Observed --
Example 6 a) Glass 2 50 55 18 None .circleincircle. Comp. Ex. 5 a)
Glass 2 60 55 15 None X Example 7 a) BM 2 45 55 20 -- -- .sup.1)a)
Solvent-based ink (surface tension 30 dyne/cm); b) water-based ink
(surface tension 40 dyne/cm) .sup.2)Contact angle of pattern with
ink .sup.3)Determined from contact angle with different solvents
.sup.4).circleincircle.: good; .largecircle.: fair; X: bad
[0171] As is seen from the results described in Table 1, according
to the present invention, a black matrix or separation rib suited
for producing a color filter by an ink-jet recording method can be
produced in a simple technique. Furthermore, suitable ink
repellency can be obtained by controlling an amount of a
fluororesin to be contained in an image component of a transfer
layer. Further, in the resulting color filters, the generation of
color mixture and color spot can be effectively prevented.
[0172] Industrial Applicability
[0173] As described above, according the present invention, there
can be provided a donor sheet, which can produce an separation
member of an optical element, e.g. partition pattern of a color
filter, black matrix of a liquid crystal display device, and
partitioning wall of the organic EL element by a shortened
manufacturing step with ease and accuracy at high contrast, and can
impart excellent ink repellency, i.e. water repellency and oil
repellency to the separation member. Use of this donor sheet has an
effect capable of producing a color filter, a liquid crystal
display device, organic EL element and other optical elements at
low cost by a simple technique. It should be particularly noted
that, on providing such an optical element with a separation
member, the substrate separation member can be provided by directly
writing onto the substrate without using a complex method such as
lithography method, like the prior art. The separation member of
the optical element thus obtained, such as partition pattern,
separation rib, black matrix, partitioning wall or the like, is
suited for formation of picture elements according to an ink-jet
recording method because it is particularly superior in ink
repellency (water repellency and oil repellency). Furthermore,
since the amount of a fluorine-containing compound and/or a
silicone compound contained in the transfer layer of the donor
sheet is optimized in the present invention, there is also exerted
an effect capable of controlling the water repellency and oil
repellency of the separation member with maintaining the adhesion
of the image component (separation member) to be transferred to the
image receiving element.
* * * * *