D E S C R I P T I O N
COLOR FILTER SUBSTRATE AND FRINGE-FIELD
SWITCHING MODE LIQUID CRYSTAL DISPLAY USING SAME
5
Technical Field
The present invention relates to a color filter
substrate for fringe-field switching mode liquid
crystal display and a fringe-field switching mode
10 liquid crystal display in which the color filter
substrate is used.
Background Art
Recently, an in-plane switching mode liquid
crystal display in which the initial alignment of
15 liquid crystal is horizontal to the surface of a
substrate and in which the liquid crystal is rotated
horizontally to the substrate surface and a novel
fringe-field switching mode liquid crystal display
designed to attain an enhanced transmittance have been
20 proposed and are being marketed. These liquid crystal
displays are used in a normally black mode (when no
driving voltage applied, the liquid crystal
horizontally aligned; crossed nicols used as the
polarizer), and realize a wide viewing angle and a high
25 contrast, so that they are becoming a mainstream
display for use in large-size TVs and mobile devices.
The fringe-field switching (hereinafter referred
to as FFS) mode liquid crystal display can realize
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higher transmittance and higher displayed image quality
than those of the conventional in-plane switching mode
liquid crystal display. However, the requirement for
the electrical properties, especially relative
5 dielectric constant, of color filter and other members,
including an insulating layer between the pixel
electrode for driving the liquid crystal and the common
electrode, for use in the fringe-field switching mode
liquid crystal display is becoming severe.
10 The difference between the in-plane switching mode
liquid crystal display and the fringe-field switching
liquid crystal display will be described with reference
to FIG. 1 and FIG. 2.
FIG. 1 shows a cross section of the in-plane
15 switching mode liquid crystal display. The in-plane
switching mode liquid crystal display is so constructed
that a color filter substrate 40 and an array substrate
50 are arranged facing each other and stuck together
with a liquid crystal layer 46 interposed therebetween.
20 Pixel electrodes 51 and common electrodes 52 are
provided on the array substrate 50 with an insulating
layer 22 interposed therebetween. The pixel electrodes
51 and the common electrodes 52 are wiring layers
comprised of a highly conductive material, such as a
25 metal. They are often provided in a comb-shaped
pattern with a pitch of tens of microns. In the liquid
crystal layer 46, use is made of a liquid crystal that
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makes an initial alignment horizontal to the surface of
the substrate and exhibits positive dielectric constant
anisotropy.
FIG. 1 shows the state of "white display" in
5 which, for example, a liquid-crystal-driving voltage of
5 V is applied between the pixel electrodes 51 and the
common electrodes 52. Electric field is applied in a
lateral direction as indicated by a line of electric
force 43 in FIG. 1, so that the liquid crystal
10 molecules between the pixel electrodes 51 and the
common electrodes 52 are horizontally rotated by the
applied voltage. The liquid crystal molecules 47 close
to the substrate surface cannot attain satisfactory
rotation because of a strong restraining force of
15 rubbing on the alignment film. In FIG. 1, not only the
liquid crystal molecules 48 on the pixel electrodes 51
but also the liquid crystal molecules 49 on the common
electrodes 52 remain in the initial horizontal
alignment and are not rotated because the application
20 of the voltage for rotating the liquid crystal
molecules is poor (liquid crystal molecules 49 are
oriented in the direction perpendicular to the sheet).
This means that even when, for example, the pixel
electrodes 51 and the common electrodes 52 are formed
25 of a transparent conductive film, such as ITO, liquid
crystal molecules that do not rotate regardless of the
application of a driving voltage are left, causing a
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lowering of transmittance.
FIG. 2 shows a cross section of the fringe-field
switching liquid crystal display. The fringe-field
switching liquid crystal display is so constructed that
5 a color filter substrate 40 and an array substrate 60
are arranged facing each other and stuck together with
a liquid crystal layer 56 interposed therebetween.
Pixel electrodes 61 and a common electrode 62 are
provided on the array substrate 60 with an insulating
10 layer 22 interposed therebetween. Both the pixel
electrodes 61 and the common electrode 62 are formed of
a transparent conductive film, such as ITO. A
characteristic feature of this electrode structure is
that within a pixel, the common electrode 62 is
15 provided in a solid planar form, while the pixel
electrodes 61 are provided very finely with an
electrode width (WL) of about 2 to 10 urn and with a
pitch of 15 urn or less.
For example, the pixel electrodes 61 can be
20 provided with an electrode width (WL) of 5 urn and a
pitch of 11 um. The smaller the electrode width (WL)
and pitch of the pixel electrodes 61 are, the greater
the contribution to the increase of the transmittance
of the liquid crystal display is. The reason therefor
25 is that the fringe electric field provided from the
pattern edges of the pixel electrodes 61 to the common
electrode 62 is the agent of liquid crystal drive.
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When the electrode width (WL) is, for example, 2 um,
rendering the inter-electrode distance (Ws) a little
bit large, about 3 um, realizes high efficiency from
the viewpoint of transmittance.
5 In the liquid crystal layer 56 shown in FIG. 2,
liquid crystal molecules are rotated across
substantially all the area within the pixel by the
application of a liquid crystal driving voltage between
the pixel electrodes 61 and the common electrode 62,
10 thereby realizing a display of high transmittance. In
a liquid crystal display device in which a liquid
crystal of initial horizontal alignment is used, the
FFS mode can be regarded as means for transmittance
enhancement by the generation of fringe electric field
15 at a short cycle.
Known technologies relating to the color filter
for in-plane switching mode liquid crystal display are
disclosed in Jpn. Pat. Appln. KOKAI Publication
No. (hereinafter referred to as JP-A-) 2009-229826 and
20 JP-A-H9-292514. The technology disclosed in JP-A-2009-
229826 comprises specifying the dielectric dissipation
factor and chromaticity of a color filter applicable to
an in-plane switching mode liquid crystal display. The
relative dielectric constant required for the in-plane
25 switching mode is claimed therein. However, there is
no disclosure of particular values with respect to the
relative dielectric constant of each of red, green and
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blue color layers, and there is no disclosure with
respect to a requisite average of relative dielectric
constant and an extent of variation thereof.
Therefore, naturally, no attention is drawn to the
5 respective dielectric constants to be uniformly
exhibited by red, green and blue color layers, which
are required at the time of halftone display.
Moreover, there is no disclosure at all with respect to
the influence of the dielectric constant of a black
10 matrix usually provided for ensuring contrast at the
time of color display by such color pixels. There is
no description with respect to the relative dielectric
constant of a color filter needed in the fringe-field
switching mode liquid crystal display that while
15 realizing a high-transmittance display, requires highlevel
electrical properties on liquid-crystalsurrounding
members. Further, no study is made with
respect to the liquid crystal driving frequency
(120 Hz, 240 Hz) prevailing in liquid crystal
20 televisions in which the in-plane switching mode or
fringe-field switching mode is employed. The relative
dielectric constant at the frequency is not disclosed.
The electrical properties of liquid-crystal-surrounding
members often change the values thereof in low-
25 frequency regions and high-frequency regions, so that
they should be measured in actual use conditions.
In the structuring of the color filter described
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in JP-A-2009-229826, an overcoat layer comprised of a
transparent resin layer is avoided. In the FFS mode
liquid crystal display device, an overcoat layer
comprised of a transparent resin layer must be provided
5 on the color layer of the color filter thereof. The
reason therefor is that there are extremely high-level
requirements with respect to the voltage holding ratios
of liquid crystal materials for use in the FFS mode,
and that in order to avoid any lowering of voltage
10 holding ratio attributed to any adverse effect of
impurity ions contained in an organic pigment of the
color layer, it is essential to provide an overcoat
layer comprised of a transparent resin layer.
JP-A-H9-292514 discloses a color film whose
15 relative dielectric constant is 4.5 or below, and in
paragraph 0014 discloses a pigment black 7 comprised of
carbon as a black pigment of black matrix. However,
with respect to the color films disclosed in FIG. 3 of
JP-A-H9-292514, for example, the relative dielectric
20 constant at a frequency of 100 Hz of blue color film
can be read as about 3.9, that of red color film as
about 3.45 and that of green color film as about 3.1.
The variation of relative dielectric constant is large,
so that the color films can be applied to the
25 conventional in-plane switching mode liquid crystal
display but cannot be applied to the display of high
image quality by fringe-field switching mode liquid
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crystal display. JP-A-H9-292514 does not disclose any
concept of uniformizing the relative dielectric
constants of individual color films. Further, there is
no disclosure with respect to any impact of the
5 relative dielectric constant of black matrix on the FFS
mode liquid crystal display device.
Summary of Invention
Technical Problem
In the FFS mode liquid crystal display device, the
10 relative dielectric constants of color filter members
must be uniformized. When there is a large variation
of relative dielectric constant as in, for example, the
color layers disclosed in FIG. 3 of JP-A-H9-292514,
there is a problem that the transmittance of a pixel of
15 high relative dielectric constant becomes lower than
those of other pixels at the time of gradation display,
thereby causing a color unbalance. In the black matrix
used for contrast improvement, generally, carbon is
used as a light-shielding (black) coloring agent. The
20 relative dielectric constant of the black matrix
containing carbon as a main pigment is as extremely
large as 10 to 40. The relative dielectric constant of
the black matrix capable of realizing light shielding
properties (optical density) required for the frame
25 pattern surrounding an effective display region of
liquid crystal generally exhibits a large value, such
as about 30. When use is made of such a black matrix
exhibiting a large relative dielectric constant, the
FFS mode liquid crystal display device encounters a
problem that at the time of intermediate display, such
as low gradation, light leakage occurs at a border of
5 black matrix and color layer. This is because at the
time of driving-voltage-application, an equipotential
line that should be originally uniform within a pixel
is deformed by an adverse effect of the high relative
dielectric constant of the black matrix, resulting in
10 the observation of light leakage around the black
matrix.
In the FFS mode liquid crystal display device,
because of its high image quality, color unevenness,
such as red unevenness or white unevenness, tends to be
15 observed. A cause of this color unevenness is the
leaching of ionic impurities from a color layer into
the liquid crystal. The leaching of ionic impurities
can be nearly solved by covering the color layer with a
highly purified transparent resin layer as an overcoat
20 layer. However, it is difficult to solve the
difference in relative dielectric constant attributed
to different organic pigment species between individual
color layers by covering with an overcoat layer only.
For example, a halogenated copper phthalocyanine
25 pigment used as a green pigment increases the relative
dielectric constant of a green pixel comprising the
same as a coloring agent, resulting in a slight
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lowering of the transmittance of the green pixel, so
that a problem of poor display, such as red unevenness,
arises.
In the FFS mode liquid crystal display device, use
5 is made of, for example, a liquid crystal whose
dielectric constant anisotropy ranges from 3.2 to 7. A
liquid crystal whose dielectric constant anisotropy is
about 5 on the large side is often used in order to
lower the threshold voltage or to shorten the response
10 time (rise of liquid crystal). When a dielectric
constant material whose dielectric constant anisotropy
is larger than the value of dielectric constant
anisotropy of this liquid crystal is used as a color
filter member, problems, such as the above-mentioned
15 color unevenness and light leakage, are likely to
arise. A bad example thereof is the above-mentioned
light leakage experienced when a black matrix of high
relative dielectric constant is employed in a color
filter.
20 The present invention has been made in these
circumstances. It is an object of the present
invention to provide a color filter substrate suitable
for FFS mode liquid crystal display device that can
ensure higher transmittance and higher image quality,
25 without color unevenness and light leakage, than in the
in-plane switching mode liquid crystal display. It is
another object of the present invention to provide an
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FFS mode liquid crystal display device.
Solution to Problem
According to the first aspect of the present
invention, there is provided a color filter substrate
5 for use in a fringe-field switching mode liquid crystal
display wherein the color filter substrate and an array
substrate provided with a comb-shaped pixel electrode
having an electrode width of 10 urn or less are arranged
facing each other with a liquid crystal layer
10 interposed therebetween, the color filter substrate
comprising: a transparent substrate; a black matrix
provided on the transparent substrate, comprising an
organic pigment as a main coloring agent; a red pixel,
a green pixel and a blue pixel which are provided in
15 regions partitioned by the black matrix on the
transparent substrate and each have a relative
dielectric constant of 2.9 or more but or less 4.4, as
measured at a frequency at which the liquid crystal is
driven; and a transparent resin layer provided on the
20 red pixel, the green pixel and the blue pixel, wherein
the relative dielectric constant of each of the color
pixels falls within ±0.3 of an average relative
dielectric constant of the red pixel, the green pixel
and the blue pixel.
25 According to the second aspect of the present
invention, there is provided a liquid crystal display
comprising the above-defined color filter substrate.
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According to the third aspect of the present
invention, there is provided a fringe-field switching
mode liquid crystal display comprising a color filter
substrate comprising a transparent substrate; a black
5 matrix provided on the transparent substrate; a red
pixel, a green pixel and a blue pixel which are
provided in regions partitioned by the black matrix and
each have a relative dielectric constant of 2.9 or more
but 4.4 or less, as measured at a frequency at which
10 the liquid crystal is driven, and a transparent resin
layer provided on the red pixel, the green pixel and
the blue pixel, wherein the relative dielectric
constant of each of the color pixels falls within ±0.3
of an average relative dielectric constant of the red
15 pixel, the green pixel and the blue pixel; an array
substrate disposed facing the color filter substrate,
and provided with a comb-shaped pixel electrode having
an electrode width of 10 urn or less; and a liquid
crystal layer interposed between the color filter
20 substrate and the array substrate.
In this description, a color layer patternwise
formed in a black matrix aperture is referred to as a
color pixel, and specifically referred to as a red
pixel, a green pixel or a blue pixel. The color layer
25 on a frame portion outside an effective display region
of liquid crystal is referred to as a red layer, a blue
layer or the like. The film as a measurement sample
4fc, I
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for use in the measuring of relative dielectric
constant is likewise referred to as a red layer, a
green layer or a blue layer. The relative dielectric
constant of a color pixel mentioned in this description
5 refers to the data obtained by forming a color layer as
a measurement sample and measuring the same.
Brief Description of Drawings
FIG. 1 shows a schematic cross section of the
conventional in-plane switching mode liquid crystal
10 display.
FIG. 2 shows a schematic cross section of the
conventional fringe-field switching mode liquid crystal
display.
FIG. 3 shows a schematic cross section of a color
15 filter substrate according to an embodiment of the
present invention.
FIG. 4 shows a schematic cross section of a color
filter substrate according to Example 2 of the present
invention.
20 FIG. 5 shows a schematic cross section of a liquid
crystal display according to Example 3 of the present
invention.
Mode for Carrying out the Invention
Embodiments of the present invention will be
25 described below.
The color filter substrate according to an aspect
of the present invention is one for use in a
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fringe-field switching mode liquid crystal display.
The fringe-field switching mode liquid crystal display
is so structured that the color filter substrate and an
array substrate provided with a comb-shaped pixel
5 electrode having an electrode width of 10 urn or less
are arranged facing each other with a liquid crystal
layer interposed therebetween. In the event that the
electrode width of the comb-shaped pixel electrode
exceeds 10 urn, the transmittance exhibited when the
10 normally black fringe-field switching mode liquid
crystal display is in on-states (at the time of
application of a liquid-crystal-driving-voltage to the
comb-shaped pixel electrode) becomes unfavorably low.
The smaller the electrode width (WL) and inter-
15 electrode distance (Ws) of the comb-shaped pixel
electrode are, the higher the transmittance is.
However, when the electrode width of the comb-shaped
pixel electrode is 1 urn or less, the accuracy of
pattern reproduction in photolithographic process
20 becomes poor, thereby causing a yield drop. It is
preferred for the electrode width (WL) and interelectrode
distance (Ws) of the comb-shaped pixel
electrode to fall within the range of 2 urn or more but
5 urn or less.
25 This color filter substrate comprises a
transparent substrate; a black matrix provided on the
transparent substrate, comprising an organic pigment as
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a main coloring agent; a red pixel, a green pixel and a
blue pixel which are provided in regions partitioned by
the black matrix on the transparent substrate and each
have a relative dielectric constant of 2.9 or more but
5 4.4 or less, as measured at a frequency at which the
liquid crystal is driven; and a transparent resin layer
provided on the red pixel, the green pixel and the blue
pixel. When the relative dielectric constant of each
of the color pixels is below 2.9, a coloring agent,
10 such as an organic pigment, cannot be added in an
amount sufficient to ensure chromatic purity to the
transparent resin, so that a color filter of favorable
performance cannot be provided. When the relative
dielectric constant of each of the color pixels exceeds
15 4.4, unfavorably, a response delay of liquid crystal
and nonuniformity in gradation display occur.
The relative dielectric constant of each of the
color pixels falls within ±0.3 of an average relative
dielectric constant of the red pixel, the green pixel
20 and the blue pixel (difference from the average: 0.3 or
less). When the difference in relative dielectric
constant falls outside this range, color unevenness
occurs.
In this color filter substrate, the black matrix
25 can have a relative dielectric constant of 2.9 or more
but 4.4 or less, as measured at a frequency at which
the liquid crystal is driven. Further, the black
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matrix can have a relative dielectric constant as
measured at a frequency at which the liquid crystal is
driven, which relative dielectric constant is smaller
than a value of dielectric constant anisotropy
5 exhibited by the liquid crystal used in the fringefield
switching mode. Still further, the coloring
agent of the black matrix can comprise the organic
pigment in an amount of 92 mass% or more based on the
whole amount of the coloring agent, and can comprise
10 carbon as a balance.
The green pixel can comprise a halogenated zinc
phthalocyanine pigment as a main coloring agent.
The average relative dielectric constant of the
red pixel, the green pixel and the blue pixel can be
15 smaller than a value of dielectric constant anisotropy
exhibited by the liquid crystal used in the fringefield
switching mode.
The frequency applied in the measuring of the
relative dielectric constant can be a frequency ranging
20 from 120 to 480 Hz.
The black matrix can have a pattern shape
configured to partition four sides of each of the color
pixels in a lattice form or two sides thereof in a
stripe form and can have a frame pattern surrounding an
25 effective display region of liquid crystal display,
wherein, on the frame pattern, one of a blue layer used
in forming the blue pixel and a red layer used in
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forming the red pixel can be superimposed, or two
thereof can be superimposed one upon the other.
In particular, the black matrix can have a pattern
shape configured to partition four sides of each of the
5 color pixels in a lattice form or two sides thereof in
a stripe form and can have a frame pattern surrounding
an effective display region of liquid crystal display,
wherein, on the frame pattern, a red layer used in
forming the red pixel and a blue layer used in forming
10 the blue pixel can be superimposed in this order one
upon the other.
According to an aspect of the present invention,
there can be provided a color filter substrate for FFS
mode liquid crystal display that when incorporated in
15 the liquid crystal display device, can avoid display
defects, such as color unbalance and red or white color
unevenness. Moreover, there can be provided a color
filter substrate for FFS mode liquid crystal display
that can avoid light leakage at a border of black
20 matrix and color layer. In addition, there can be
provided an FFS mode liquid crystal display freed of
the above display defects.
FIG. 3 shows a cross section of a color filter
substrate according to an embodiment of the present
25 invention. In FIG. 3, a black matrix (BM) comprising
an organic pigment as a main coloring agent is provided
on a transparent substrate (10) comprised of, for
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example, glass. A red pixel (R), a green pixel (G) and
a blue pixel (B) are provided in regions on the
transparent substrate (10) partitioned by the black
matrix (BM). The red pixel (R), green pixel (G) and
5 blue pixel (B) are covered by a transparent resin layer
(15). Thus, a color filter substrate is constructed.
This color filter substrate is one for use in a
fringe-field switching mode liquid crystal display, as
mentioned above, wherein the color filter substrate and
10 an array substrate provided with a comb-shaped pixel
electrode having an electrode width of 10 urn or less
are bonded to each other with a liquid crystal
interposed therebetween.
The main object of application of this embodiment
15 is a normally-black-display liquid crystal display
device comprising a liquid crystal whose initial
alignment is a horizontal alignment or perpendicular
alignment, and this embodiment presupposes a liquid
crystal display device comprising a color filter
20 substrate and an array substrate provided with a liquid
crystal driving element, such as TFT, that are bonded
to each other with a liquid crystal layer interposed
therebetween. As the liquid crystal, use can be made
of both a liquid crystal exhibiting a positive
25 dielectric constant anisotropy and a liquid crystal
exhibiting a negative dielectric constant anisotropy.
The liquid crystal exhibiting a positive dielectric
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constant anisotropy is advantageous in that the
dielectric constant anisotropy (As) and birefringence
(An) of liquid crystal can be selected from a wide
variety of liquid crystal materials.
5 A feature of this embodiment is to uniformize the
relative dielectric constants of color pixels in the
color filter so as to avoid any display difference
between pixels of different colors caused by the
driving of employed liquid crystal. Another feature of
10 this embodiment is to construct color pixels with a
material of dielectric constant anisotropy smaller than
the value of dielectric constant anisotropy of the
liquid crystal so as to avoid any influence upon the
driving of employed liquid crystal. In the FFS mode
15 liquid crystal display device comprising a liquid
crystal whose initial alignment is horizontal and whose
dielectric constant anisotropy is positive, a plurality
of advantages can be obtained by selecting As from the
range of somewhat large dielectric constant anisotropy,
20 for example, 4.5 to 6.5 and applying the same to this
embodiment. One of such advantages is to lower the
threshold voltage associated with liquid crystal
driving and to improve the response (rise) of liquid
crystal. Selection of liquid crystal materials for use
25 in the liquid crystal device comprising the color
filter substrate according to this embodiment will be
described in detail below.
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As mentioned above, the color filter must comprise
color pixels, the relative dielectric constant of each
of which falls within ±0.3 of an average relative
dielectric constant of the red pixel, the green pixel
5 and the blue pixel, so as to avoid any color unevenness
at the time of color display. As will be mentioned
hereinafter, when the difference in relative dielectric
constant between color pixels exceeds 0.8 or 1.0 in the
FFS mode liquid crystal display device, color
10 unevenness and light leakage are likely to occur at the
time of liquid crystal display. As a result of study
by the inventors, it has been found that, as will be
described in detail in Examples hereinafter, the
relative dielectric constants of color pixels, even if
15 comprised of materials likely to have a high relative
dielectric constant such as that of the black matrix,
can be suppressed to 4.4 or below by selection of
organic pigment as a coloring agent, pigment ratio and
material selection for base material resin, dispersant,
20 etc.
In the FFS mode liquid crystal display device
comprising a liquid crystal exhibiting a positive
dielectric constant anisotropy, the value of relative
dielectric constant of each of color filter constituent
25 materials can be made smaller than the value of
dielectric constant anisotropy of the liquid crystal by
selecting As from the range of somewhat large
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dielectric constant anisotropy, for example, 4.5 to
6.5, so that conditions not detrimental to liquid
crystal driving can be realized. Usually, a coloring
composition containing a photosensitive acrylic resin
5 is used in the formation of color pixels in the color
filter. The relative dielectric constant of a
transparent resin, such as an acrylic resin, is
generally around 2.8. As a result of study by the
inventors, it has been found that the lower limit of
10 the relative dielectric constant of each color pixel
being a dispersion system of organic pigment is 2.9.
(Measurement of relative dielectric constant)
In the Examples to be described hereinafter, the
relative dielectric constant of each color pixel was
15 measured at frequencies of 120, 240 and 480 Hz in the
condition of a voltage of 5 V by means of an impedance
analyzer, model 1260, manufactured by Solartron Mobrey.
The measurement sample was one obtained by applying a
color layer on a glass substrate having been
20 patternwise provided with a conductive film comprised
of an aluminum thin film, hardening the color layer
(thickness: the same as in the Examples to be described
hereinafter) and superimposing a conductive film
pattern comprised of an aluminum thin film on the color
25 layer.
(Measurement of OD of black matrix)
The optical density (OD value) as an index for
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light blocking property was measured by means of a
Gretag Macbeth D-200II.
(Measurement of chromaticity)
The chromaticity coordinate of each color layer
5 was measured by means of a microscopic
spectrophotometer OSP-2000 (manufactured by Olympus
Optical Co., Ltd.).
Examples of the transparent resins, organic
pigments, etc., that can be used in the color filter
10 substrate according to the foregoing embodiment will be
described below.
(Transparent resin)
The photosensitive color composition for use in
the formation of a light shielding layer and a color
15 pixel comprises a pigment dispersion and further a
polyfunctional monomer, a photosensitive resin, a
nonphotosensitive resin, a polymerization initiator, a
solvent, etc. Highly transparent organic resins that
can be used in this embodiment, including a
20 photosensitive resin and a nonphotosensitive resin, are
collectively referred to as a transparent resin. The
following resins can be used as the transparent resin.
In particular, a thermoplastic resin, a
thermosetting resin and a photosensitive resin can be
25 used as the transparent resins. As the thermoplastic
resin, there can be mentioned, for example, a butyral
resin, a styrene-maleic acid copolymer, a chlorinated
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polyethylene, a chlorinated polypropylene, polyvinyl
chloride, a vinyl chloride-vinyl acetate copolymer,
polyvinyl acetate, a polyurethane resin, a polyester
resin, an acrylic resin, an alkyd resin, a polystyrene
5 resin, a polyamide resin, a rubber resin, a cyclized
rubber resin, a cellulose, polybutadiene, polyethylene,
polypropylene, a polyimide resin or the like. As the
thermosetting resin, there can be mentioned, for
example, an epoxy resin, a benzoguanamine resin, a
10 rosin-modified maleic acid resin, a rosin-modified
fumaric acid resin, a melamine resin, a urea resin, a
phenolic resin or the like. As the thermosetting
resin, use can be made of a resin resulting from
reaction between a melamine resin and a compound
15 containing an isocyanate group.
(Alkali-soluble resin)
In the formation of a black matrix (light blocking
layer) as a material for black matrix formation, color
pixels and a transparent resin layer as an overcoat for
20 use in this embodiment, it is preferred to use a
photosensitive resin composition that permits
patterning by photolithography. It is preferred for
the transparent resin to be a resin imparted with
alkali solubility. The alkali-soluble resin is not
25 particularly limited as long as it is a resin
containing a carboxyl group or a hydroxyl group. For
example, there can be mentioned an epoxy acrylate
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resin, a novolac resin, a polyvinylphenol resin, an
acrylic resin, a carboxylated epoxy resin, a
carboxylated urethane resin or the like. Of these, an
epoxy acrylate resin, a novolac resin and an acrylic
5 resin are preferred. An epoxy acrylate resin and a
novolac resin are especially preferred.
(Acrylic resin)
As representative examples of the transparent
resins that can be employed in this embodiment, there
10 can be mentioned the following acrylic resins.
In particular, the acrylic resins can be polymers
prepared from, as monomers, (meth)acrylic acid; an
alkyl (meth)acrylate, such as methyl (meth)acrylate,
ethyl (meth)acrylate, propyl (meth)acrylate, butyl
15 (meth)acrylate, t-butyl (meth)acrylate, pentyl
(meth)acrylate or lauryl (meth)acrylate; a hydroxylated
(meth)acrylate, such as hydroxyethyl (meth)acrylate or
hydroxypropyl (meth)acrylate; an etherified
(meth)acrylate, such as ethoxyethyl (meth)acrylate or
20 glycidyl (meth)acrylate; an alicyclic (meth)acrylate,
such as cyclohexyl (meth)acrylate, isobornyl
(meth)acrylate or dicyclopentenyl (meth)acrylate; etc.
One of these monomers may be used alone, or two or
more thereof may be used in combination. Further, the
25 acrylic resins may be copolymers resulting from
reaction between these monomers and compounds
copolymerizable therewith, such as styrene,
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cyclohexylmaleimide and phenylmaleimide.
Moreover, photosensitive resins can be obtained
by, for example, performing copolymerization of a
carboxylic acid containing an ethylenically unsaturated
5 group, such as (meth)acrylic acid, and thereafter
reacting the resultant copolymer with a compound
containing an epoxy group and an unsaturated double
bond, such as glycidyl methacrylate, or by performing
addition reaction of a carboxylated compound, such as
10 (meth)acrylic acid, to a polymer of epoxidized
(meth)acrylate, such as glycidyl methacrylate, or a
copolymer resulting from reaction between the same and
another (meth)acrylate.
Still further, photosensitive resins can be
15 obtained by reacting a hydroxylated polymer obtained
from a monomer, such as hydroxyethyl methacrylate, with
a compound containing an isocyanate group and an
ethylenically unsaturated group, such as
methacryloyloxyethyl isocyanate.
20 Still further, as aforementioned, a carboxylated
resin can be obtained by reacting a copolymer obtained
from a monomer containing a plurality of hydroxyl
groups, such as hydroxyethyl methacrylate, with a
polyprotic acid anhydride to thereby introduce a
25 carboxyl group in the copolymer. The process for
producing a carboxylated resin is not limited to this
method.
W 26 I
As the acid anhydride for use in the above I
reaction, there can be mentioned, for example, malonic I
anhydride, succinic anhydride, maleic anhydride, I
itaconic anhydride, phthalic anhydride, 1
5 tetrahydrophthalic anhydride, hexahydrophthalic I
anhydride, methyltetrahydrophthalic anhydride, 1
trimellitic anhydride or the like.
It is preferred for the acid number of the solid
contents of the above-mentioned acrylic resins to be in
10 the range of 20 to 180 mg KOH/g. When the acid number
is smaller than 20 mg KOH/g, the speed of the
development of the photosensitive resin composition
tends to be extremely low to thereby increase the
development time and hence result in poor productivity.
15 On the other hand, when the acid number of the solid
contents is larger than 180 mg KOH/g, the development
speed tends to be extremely high to thereby cause
development failures, such as pattern exfoliation and
pattern chipping.
20 Further, when the acrylic resin exhibits
photosensitivity, it is preferred for the double bond
equivalent weight of the acrylic resin to be 100 or
greater. The double bond equivalent weight is more
preferably in the range of 100 to 2000, most preferably
25 100 to 1000. When the double bond equivalent weight
exceeds 2000, satisfactory photohardenability may not
be obtained.
W 27 I
(Photopolymerizable monomer) 1
Examples of photopolymerizable monomers include
various acrylic and methacrylic esters, such as
2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl
5 (meth)acrylate, cyclohexyl (meth)acrylate, polyethylene
glycol di(meth)acrylate, pentaerythritol
tri(meth)acrylate, trimethylolpropane
tri(meth)acrylate, dipentaerythritol
hexa(meth)acrylate, tricyclodecanyl (meth)acrylate,
10 melamine (meth)acrylate and epoxy (meth)acrylate, and
l
further include (meth)acrylic acid, styrene, vinyl
acetate, (meth)acrylamide, Nhydroxymethyl(
meth)acrylamide, acrylonitrile and the
like.
15 It is also preferred to use a polyfunctional
urethane acrylate containing a (meth)acryloyl group,
obtained by reacting a hydroxylated (meth)acrylate with
a polyisocyanate. Combinations of hydroxylated
(meth)acrylate and polyisocyanate are arbitrary and are
20 not particularly limited. One type of polyfunctional
urethane acrylate may be used alone, or two or more
types thereof may be used in combination.
(Photopolymerization initiator)
Examples of photopolymerization initiators include
25 an acetophenone compound, such as 4-
phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone,
diethoxyacetophenone, ;
W 28
1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-l-one, j
1-hydroxycyclohexyl phenyl ketone or 2-benzyl-2-
dimethylamino-1-(4-morpholinophenyl)-butan-1-one; a
benzoin compound, such as benzoin, benzoin methyl i
5 ether, benzoin ethyl ether, benzoin isopropyl ether or
benzyldimethyl ketal; a benzophenone compound, such as
benzophenone, benzoylbenzoic acid, methyl j
benzoylbenzoate, 4-phenylbenzophenone,
hydroxybenzophenone, acrylated benzophenone or 4-
10 benzoyl-4'-methyldiphenyl sulfide; a thioxanthone
compound, such as thioxanthone, 2-chlorothioxanthone,
2-methylthioxanthone, isopropylthioxanthone or 2,4-
diisopropylthioxanthone; a triazine compound, such as
2,4,6-trichloro-s-triazine, 2-phenyl-4,6-
15 bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-
4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-
bis(trichloromethyl)-s-triazine, 2-pipenyl-4,6-
bis(trichloromethyl)-s-triazine, 2,4-
bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphth-
20 1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4- !
methoxynaphth-1-yl)-4,6-bis(trichloromethyl)-striazine,
2,4-trichloromethyl-(piperonyl)-6-triazine or
2,4-trichloromethyl(4'-methoxystyryl)-6-triazine; an
oxime ester compound, such as 1,2-octanedione, l-[4-
25 (phenylthio)-2-(O-benzoyloxime)] or 0-(acetyl)-N-(1-
phenyl-2-oxo-2-(4'-
methoxynaphthyl)ethylidene)hydroxylamine; a phosphine
W 29
compound, such as bis(2,4,6-
trimethylbenzoyl)phenylphosphine oxide or 2,4,6-
trimethylbenzoyldiphenylphosphine oxide; a quinone
compound, such as 9,10-phenanthrenequinone,
5 camphorquinone or ethylanthraquinone; a borate
compound; a carbazole compound; an imidazole compound;
a titanocene compound; and the like. Oxime derivatives
(oxime compounds) are effective for sensitivity
enhancement. One of these initiators can be used
10 alone, or two or more thereof can be used in
combination. t
(Sensitizer) I
It is preferred to use a photopolymerization initiator in combination with a sensitizer. Compounds, 15 such as a-acyloxy esters, acylphosphine oxides, methyl
phenyl glyoxylate, benzyl-9,10-phenanthrenequinone,
camphorquinine, ethylanthraquinone, 4,4'- diethylisophthalophenone, 3,3 ',4,4'-tetra(tbutylperoxycarbonyl)
benzophenone and 4,4'-
20 diethylaminobenzophenone, can be used as sensitizers.
Any of these sensitizers can be incorporated in an
amount ranging from 0.1 to 60 parts by mass per 100
parts by mass of photopolymerization initiator.
(Ethylenically unsaturated compound)
25 It is preferred to use the above-mentioned
photopolymerization initiator in combination with an
ethylenically unsaturated compound. The term
i
W 30
"ethylenically unsaturated compound" means a compound ;
containing at least one ethylenically unsaturated bond [
in each molecule thereof. In particular, a compound |
containing two or more ethylenically unsaturated bonds
5 in each molecule is preferred from the viewpoint of
polymerizability, crosslinkability, an increase of any
difference in developer solubility between exposed
areas and nonexposed areas in accordance therewith, ;
etc. A (meth)acrylate compound containing an
10 unsaturated bond originating from a (meth)acryloyloxy f
group is particularly preferred. I
As the compound containing at least one I
ethylenically unsaturated bond in each molecule l
thereof, there can be mentioned, for example, an I
15 unsaturated carboxylic acid, such as (meth)acrylic ;
acid, crotonic acid, isocrotonic acid, maleic acid, p
itaconic acid or citraconic acid, or an alkyl ester |
thereof; (meth)acrylonitrile; (meth)acrylamide; j
styrene; or the like. Representative examples of the ;
20 compounds each containing two or more ethylenically ;
unsaturated bonds in each molecule thereof include an 1
ester from unsaturated carboxylic acid and polyhydroxy I
compound, a (meth)acryloyloxy-containing phosphate, a 1
urethane (meth)acrylate from hydroxy(meth)acrylate I
25 compound and polyisocyanate compound, an epoxy 1
(meth)acrylate from (meth)acrylic acid or I
hydroxy (meth) acrylate compound and polyepoxy compound, I;
31 I
and the like. I
The above-described photopolymerization initiator, 1
sensitizer and ethylenically unsaturated compound may 1
be added to a composition containing a polymerizable I
5 liquid crystal compound in the event that the color 1
filter substrate according to the present invention is 1
provided with a retardation layer. 1
(Polyfunctional thiol) 1
The photosensitive color composition can be loaded I
10 with a polyfunctional thiol capable of acting as a 1
chain-transfer agent. The polyfunctional thiol is not 1
limited as long as the compound contains two or more 1
thiol groups. For example, there can be mentioned 1
hexanedithiol, decanedithiol, 1,4-butanediol I
15 bisthiopropionate, 1,4-butanediol bisthioglycolate, 1
ethylene glycol bisthioglycolate, ethylene glycol 1
bisthiopropionate, trimethylolpropane I
tristhioglycolate, trimethylolpropane I
tristhiopropionate, trimethylolpropane tris(3- 1
20 mercaptobutyrate), pentaerythritol 1
tetrakisthioglycolate, pentaerythritol 1
tetrakisthiopropionate, tris(2-hydroxyethyl) 1
trimercaptopropionate isocyanurate, 1,4- I
dimethylmercaptobenzene, 2,4,6-trimercapto-s-triazine, I
25 2-(N,N-dibutylamino)-4,6-dimercapto-s-triazine, or the 1
like. 1
One of these polyfunctional thiols can be used §
]
€ 32 [
alone, or two or more thereof can be used in the form
of a mixture. The polyfunctional thiol can preferably I
be used in an amount of 0.2 to 150 parts by mass, more i
preferably 0.2 to 100 parts by mass, per 100 parts by |
5 mass of pigment in the photosensitive color
composition.
(Storage stabilizer) I
The photosensitive color composition can be loaded
with a storage stabilizer in order to stabilize the |
10 viscosity of the composition over time. As the storage ?
stabilizer, there can be mentioned, for example, a
quaternary ammonium chloride, such as one from
benzyltrimethyl chloride and diethylhydroxyamine; an organic acid, such as lactic acid or oxalic acid, or a 15 methyl ether thereof; t-butyl-pyrocatechol; an organic :
phosphine, such as triethylphosphine or
triphenylphosphine; a phosphite; or the like. The I
storage stabilizer can be incorporated in an amount of 0.1 to 10 parts by mass per 100 parts by mass of 20 pigment in the photosensitive color composition. (Adherence improver) f
The photosensitive color composition can further
be loaded with an adherence improver, such as a silane
coupling agent, in order to enhance the adherence f
25 thereof to the substrate. As the silane coupling
agent, there can be mentioned a vinylsilane, such as
vinyltris(p-methoxyethoxy)silane, vinylethoxysilane or
C 33
vinyltrimethoxysilane; a (meth)acrylsilane, such as ymethacryloxypropyltrimethoxysilane;
an epoxysilane, I
such as (3- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane,
|3-(3, 4-epoxycyclohexyl) methyltrimethoxysilane, (3-(3, 4- 5 epoxycyclohexyl) ethyltriethoxysilane, (3-(3,4- j
epoxycyclohexyl)methyltriethoxysilane, y- glycidoxypropyltrimethoxysilane or y- I
glycidoxypropyltriethoxy silane; an aminosilane, such 5
as N-(3 (aminoethyl)-Y-aminopropyltrimethoxysilane, N- I
10 (3 (aminoethyl)-Y_aminopropyl triethoxysilane, N- (3 (aminoethyl)-Y_aminopropylmethyldiethoxysilane, yaminopropyltriethoxysilane,
yaminopropyltrimethoxysilane,
N-phenyl-yaminopropyltrimethoxysilane
or N-phenyl-y- [
15 aminopropyltriethoxysilane; a thiosilane, such as ymercaptopropyltrimethoxysilane
or y~
mercaptopropyltriethoxysilane; or the like. The silane
coupling agent can be incorporated in an amount of 0.01
to 100 parts by mass per 100 parts by mass of pigment i
20 in the photosensitive color composition. f
(Solvent) |
The photosensitive color composition is loaded j
with a solvent, such as water or an organic solvent, so |
that the surface of the substrate can be uniformly
25 coated therewith. When the composition for use in this
embodiment is used in a color layer of color filter, l
the solvent also has the function of uniformly |
;
© 34 I
dispersing the pigment. Examples of the solvents
include cyclohexanone, ethyl Cellosolve acetate, butyl I
Cellosolve acetate, l-methoxy-2-propyl acetate, r
!
diethyleneglycol dimethyl ether, ethylbenzene, ethylene 5 glycol diethyl ether, xylene, ethyl Cellosolve, methyl- n-amyl ketone, propylene glycol monomethyl ether, i,
toluene, methyl ethyl ketone, ethyl acetate, methanol, [
ethanol, isopropyl alcohol, butanol, isobutyl ketone, a S
petroleum solvent, and the like. One of these solvents I
10 may be used alone, or two or more thereof may be used v
in the form of a mixture. The solvent can be incorporated in an amount of 800 to 4000 parts by mass, I
preferably 1000 to 2500 parts by mass, per 100 parts by mass of pigment in the color composition. f,
15 (Organic Pigment) I
t
As red pigment, for example, C. I. Pigment Red 7, 9, 14, 41, 48:1, 48:2, 48:3, 48:4, 81:1, 81:2, 81:3, [
I
97, 122, 123, 146, 149, 168, 177, 178, 179, 180, 184, |
I
185, 187, 192, 200, 202, 208, 210, 215, 216, 217, 220, f
20 223, 224, 226, 227, 228, 240, 242, 246, 254, 255, 264,
I
272, or 279, or the like may be used. I
I
Yellow pigment, for example, includes C. I. I
Pigment Yellow 1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, [
16, 17, 18, 20, 24, 31, 32, 34, 35, 35:1, 36, 36:1, 37, [
25 37:1, 40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, j
11, 81, 83, 86, 93, 94, 95, 97, 98, 100, 101, 104, 106, I
i
108, 109, 110, 113, 114, 115, 116, 117, 118, 119, 120, |
I
I
¥
j
I
I
I
W 35 j
I
123, 125, 126, 127, 128, 129, 137, 138, 139, 144, 146, f
147, 148, 150, 151, 152, 153, 154, 155, 156, 161, 162, j
164, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, j
176, 177, 179, 180, 181, 182, 185, 187, 188, 193, 194, j
5 199, 213, 214, and the like. As blue pigment, for example, C. I. Pigment Blue I
15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 60, 64, 80, or the like may be used. Among these, C. I. Pigment
Blue 15:6 is preferred. |
10 As violet pigment, for example, C. I. Pigment /
Violet 1, 19, 23, 27, 29, 30, 32, 37, 40, 42, 50, or the like may be used. Among these, C. I. Pigment |
Violet 23 is preferred. As green pigment, for example, C. I. Pigment Green |
15 1, 2, 4, 7, 8, 10, 13, 14, 15, 17, 18, 19, 26, 36, 45, j
i
48, 50, 51, 54, 55, 58, or the like may be used. In
particular, it is preferred to use C. I. Pigment Green 58 as the main coloring agent. i
Hereinafter, when the coloring agent species of |
20 the C. I. Pigment is indicated, the abbreviations, such f
as PB (Pigment Blue), PV (Pigment Violet), PR (Pigment (
Red), PY (Pigment Yellow), and PG (Pigment Green), may t
be simply used. ?
(Dye) 25 The color composition for use in the color filter l
according to this embodiment can be loaded with a dye *
aside from the above-mentioned pigment. t
W 36 t
As the dye, there can be mentioned an acid dye, an oil-soluble dye, a disperse dye, a reactive dye, a I
direct dye or the like. Examples of the dyes include
an azo dye, a benzoquinone dye, a naphthoquinone dye, j
5 an anthraquinone dye, a cyanine dye, a scuarylium dye, f
a croconium dye, a merocyanine dye, a stilbene dye, a I
diarylmethane dye, a triarylmethane dye, a fluoran dye, ".
a spiropyran dye, a phthalocyanine dye, an indigo dye, r:
a fulgide dye, a nickel complex dye and an azulene dye. :
10 The specific dye includes those having the i
following color index numbers: C. I. Solvent Yellow 2, ;
3, 7, 12, 13, 14, 16, 18, 19, 21, 25, 25:1, 27, 28, 29, I
30, 33, 34, 36, 42, 43, 44, 47, 56, 62, 72, 73, 77, 79, jj
81, 82, 83, 83:1, 88, 89, 90, 93, 94, 96, 98, 104, 107, f
I
15 114, 116, 117, 124, 130, 131, 133, 135, 141, 143, 145, [
146, 157, 160 : 1, 161, 162, 163, 167, 169, 172, 174, I
175, 176, 179, 180, 181, 182, 183, 184, 185, 186, 187, I
189, 190, 191, C. I. Solvent Orange 1, 2, 3, 4, 5, 7, 11, 14, 20, 23, 25, 31, 40:1, 41, 45, 54, 56, 58, 60, f
I
20 62, 63, 70, 75, 77, 80, 81, 86, 99, 102, 103, 105, 106, |
I
107, 108, 109, 110, 111, 112, 113, C. I. Solvent Red 1, I
I
2, 3, 4, 8, 16, 17, 18, 19, 23, 24, 25, 26, 27, 30, 33, [
I
35, 41, 43, 45, 48, 49, 52, 68, 69, 72, 73, 83:1, 84:1, |
89, 90, 90:1, 91, 92, 106, 109, 110, 118, 119, 122,
25 124, 125, 127, 130, 132, 135, 141, 143, 145, 146, 149,
150, 151, 155, 160, 161, 164, 164:1, 165, 166, 168, 169, 172, 175, 179, 180, 181, 182, 195, 196, 197, 198, '
I
!
i
I
C 37
207, 208, 210, 212, 214, 215, 218, 222, 223, 225, 227, 229, 230, 233, 234, 235, 236, 238, 239, 240, 241, 242, 243, 244, 245, 247, 248, C. I. Solvent Violet 2, 8, 9, |
I
II, 13, 14, 21, 21:1, 26, 31, 36, 37, 38, 45, 46, 47, [
5 48, 49, 50, 51, 55, 56, 57, 58, 59, 60, 61, C. I. !
I
Solvent Blue 2, 3, 4, 5, 7, 18, 25, 26, 35, 36, 37, 38, I
43, 44, 45, 48, 51, 58, 59, 59:1, 63, 64, 67, 68, 69, j
70, 78, 79, 83, 94, 97, 98, 100, 101, 102, 104, 105, I
i
"III, 112, 122, 124, 128, 129, 132, 136, 137, 138, 139, ( I
10 143, C. I. Solvent Green 1, 3, 4, 5, 7, 28, 29, 32, 33, 34, 35, C. I. Solvent Brown 1, 3, 4, 5, 12, 20, 22, 28, .
38, 41, 42, 43, 44, 52, 53, 59, 60, 61, 62, 63, C. I. i
Solvent Black 3, 5, 5:2, 7, 13, 22, 22:1, 26, 27, 28, )
29, 34, 35, 43, 45, 46, 48, 49, 50, C. I. Acid Red 6, 15 11, 26, 60, 88, 111, 186, 215, C. I. Acid Green 25, 27, i
C. I. Acid Blue 22, 25, 40, 78, 92, 113, 129, 167, 230, C. I. Acid Yellow 17, 23, 25, 36, 38, 42, 44, 72, 78, C. I. Basic Red 1, 2, 13, 14, 22, 27, 29, 39, C. I. '
Basic Green 3, 4, C. I. Basic Blue 3, 7, 9, 11, 17, 41,
20 66, C. I. Basic Violet 1, 3, 18, 39, 66, C. I. Basic *
Yellow 11, 23, 25, 28, 41, C. I. Direct Red 4, 23, 31, ';
75, 76, 79, 80, 81, 83, 84, 149, 224, C. I. Direct Green 26, 28, C. I. Direct Blue 71, 78, 98, 106, 108, I
192, 201, C. I. Direct Violet 51, C. I. Direct Yellow t
25 26, 27, 28, 33, 44, 50, 86, 142, C. I. Direct Orange I
26, 29, 34, 37, 72, C. I. Sulphur Red 5, 6, 7, C. I. f
Sulphur Green 2, 3, 6, C. I. Sulphur Blue 2, 3, 7, 9, =
W 38 I
F
r
l
13, 15, C. I. Sulphur Violet 2, 3, 4, C. I. Sulphur Yellow 4, C. I. Vat Red 13, 21, 23, 28, 29, 48, C. I. j
I
Vat Green 3, 5, 8, C. I. Vat Blue 6, 14, 26, 30, C. I. f
Vat Violet 1, 3, 9, 13, 15, 16, C. I. Vat Yellow 2, 12, [
v
5 20, 33, C. I. Vat Orange 2, 5, 11, 15, 18, 20, C. I. I
Azoic Coupling Component 2, 3, 4, 5, 7, 8, 9, 10, 11, I
13, 32, 37, 41, 48, C. I. Reactive Red 8, 22, 46, 120, |
I
C. I. Reactive Blue 1, 2, 7, 19, C. I. Reactive Violet I
k
2, 4, C. I. Reactive Yellow 1, 2, 4, 14, 16, C. I. [
10 Reactive Orange 1, 4, 7, 13, 16, 20, C. I. Disperse Red I
4, 11, 54, 55, 58, 65, 73, 127, 129, 141, 196, 210, 229, 354, 356, C. I. Disperse Blue 3, 24, 79, 82, 87, |
106, 125, 165, 183, C. I. Disperse Violet 1, 6, 12, 26, 27, 28, C. I. Disperse Yellow 3, 4, 5, 7, 23, 33, 42, 15 60, 64, C. I. Disperse Orange 13, 29, 30. I I In order to exhibit a desired optical spectrum, i;
[
one of these dyes can be used alone, or two or more
i
thereof may be used in combination. |
Among the dyes, cationic dyes are preferred. |
l
20' Counter-anions of the cationic dyes can be altered by f
i
conventional methods. It is preferred for the anions |
employed in the alteration to be anions of so-called l
t
superstrong acids from the viewpoint of high thermal f
stability and lightfastness. As examples of the «
25 cationic dyes, there can be mentioned those of the t
:
following color index numbers. "•
Those are: C. I. Basic Red 1, 2, 12, 13, 14, 16,
£
I',
i
i.
{
I
i
18:1, 21, 22, 26, 27, 28, 29, 36, 46, 54, 56, 58, 78, ;
C. I. Basic Yellow 1, 11, 12, 13, 14, 15, 24, 28, 29, [
30, 37, 40, 41, 45, 46, 51, 57, 62, 67, C. I. Disperse
Red 50, 90, 117, 118, 177, 122, 126, 128, 145, 146, i
5 157, C. I. Disperse Yellow 5, 8, 22, 27, 50, 56, 74, 1
84, 88, 114, 119, 160, 164, 182, 184, 187, 203, 227, j
i
t
221, C. I. Basic Green 4, 5, 8, 10, C. I. Disperse !
i
Green 7, C. I. Basic Blue, 1, 3, 4, 7, 8, 9, 11, 12, !.
15, 18:1, 22, 41, 42, 45, 53, 54, 54:1, 55, 57, 60, 62, [•
10 66, 71, 75, 77, 92, 105, 113, 141, 147, 148, 162, C. I. I
i
Disperse Blue 7, 9, 10, 20, 35, 55, 56, 58, 62, 63, 65, 82, 85, 86, 87, 89, 91, 95, 102, 104, 106, 118, 124, j
i
142, 143, 148, 162, 166, 179, 181, C. I. Violet 1, 3, j
!
4, 5, 6, 7, 10, 14, 15, 16, 20, 22, 27, 28, 35, 37, 39, Il
i
15 53, 62, 63, 83, and the like. Further preferred are C.
I. Basic Red 1, 2, 13, 14, 22, 27, 29, 39, C. I. Basic .
Green 3, 4, C. I. Basic Blue 3, 7, 9, 11, 17, 41, 66, j,
C. I. Basic Violet 1, 3, 18, 39, 66, C. I. Basic Yellow
i
II, 23, 25, 28, 41, and the like.
r
20 (Coloring agent of light-blocking layer) j
The light-blocking coloring agent contained in a :
i
light-blocking layer or black matrix is one having an ;
i
absorbing capability in visible wavelength regions to i
thereby exhibit a light-blocking function. In this i
i
25 embodiment, as the light-blocking coloring agent, there j
can be mentioned, for example, an organic pigment, an j
inorganic pigment, a dye or the like. The inorganic :
i
i
i
J
c
pigment is, for example, carbon black, titanium oxide I
or the like. The dye is, for example, an azo dye, an I
anthraquinone dye, a phthalocyanine dye, a quinoneimine |
dye, a quinoline dye, a nitro dye, a carbonyl dye, a 1
5 methine dye or the like. As the organic pigment, use |
can be made of those set forth above. One of these I
light-blocking components may be used alone, or two or 1
more thereof may be used in arbitrary combination and I
ratio. The volume resistance of this coloring agent 1
10 may be increased by providing the surface of the 1
coloring agent with a resin coating. Contrarily, the 1
volume resistance may be decreased by increasing the I
content of coloring agent relative to the base material I
of the resin to thereby impart some conductive 1
15 property. However, the volume resistance of this I
light-blocking material falls within the range of about |
1x10^ to lxlC)15 Q.Cm, so that the value is not on a I
level affecting the value of resistance of the I
transparent conductive film. Similarly, the relative |
20 dielectric constant of the light-blocking layer can be I
regulated so as to fall within the range of about 3 to I
20 by selection of a coloring agent and content ratio I
thereof. The relative dielectric constants of the I
light-blocking layer, first transparent resin layer and 1
25 color layer can be regulated in accordance with design I
conditions for the liquid crystal display device and I
driving conditions for the liquid crystal. In the I
© 41
present invention, use can be made of a black matrix
for FFS mode liquid crystal display device in which
while the addition amount of carbon tending to exhibit
an increased relative dielectric constant is decreased,
5 the content of organic pigment is increased.
(Dispersant, dispersion aid)
It is preferred to employ a polymer dispersant as
a pigment dispersant from the viewpoint that an
excellent dispersion stability over time can be
10 realized. As the polymer dispersant, there can be
mentioned, for example, a urethane based dispersant, a
polyethyleneimine based dispersant, a polyoxyethylene
alkyl ether based dispersant, a polyoxyethylene glycol
diester based dispersant, a sorbitan aliphatic ester
15 based dispersant, an aliphatic modified polyester based
dispersant or the like. Among these dispersants, a
dispersant comprised of a graft copolymer containing a
nitrogen atom is particularly preferred in the lightblocking
photosensitive resin composition containing a
20 large amount of pigment used in this embodiment from
the viewpoint of favorable developability.
Specific examples of these dispersants include, in
trade names, EFKA (produced by EFKA Additives B.V.),
Disperbyk (produced by BYK Chemie), DISPERON (produced
25 by Kusumoto Chemicals, Ltd.), SOLSPERSE (produced by
The Lubrizol Corporation), KP (produced by Shin-Etsu
Chemical Co., Ltd.), POLYFLOW (produced by Kyoeisha
Chemical Co., Ltd.), etc. One of these dispersants may
be used alone, or two or more thereof may be used in
arbitrary combination and ratio.
As the dispersion aid, use can be made of, for
5 example, any of pigment derivatives and the like.
Examples of the pigment derivatives include azo,
phthalocyanine, guinacridone, benzimidazolone,
guinophthalone, isoindolinone, dioxazine,
anthraguinone, indanthrene, perylene, perynone,
10 diketopyroropyrrole and dioxazine derivatives. Among
these, guinophthalone derivatives are preferred.
Substituents in these pigment derivatives are, for
example, a sulfonate group, a sulfonamide group or
guaternary salt thereof, a phthalimidomethyl group, a
15 dialkylaminoalkyl group, a hydroxyl group, a carboxyl
group and an amide group, which substituents may be
bonded to a pigment skeleton directly or through an
alkyl group, an aryl group, a heterocyclic group or the
like. Among these substituents, a sulfonate group is
20 preferred. These substituents may be introduced in a
pigment skeleton.
As specific examples of the pigment derivatives,
there can be mentioned a sulfonate derivative of
phthalocyanine, a sulfonate derivative of
25 quinophthalone, a sulfonate derivative of
anthraguinone, a sulfonate derivative of quinacridone,
a sulfonate derivative of diketopyroropyrrole, a
sulfonate derivative of dioxazine and the like.
One of these dispersion aids and pigment
derivatives may be used alone, or two or more thereof
may be used in arbitrary combination and ratio.
5
In the color filter according to this embodiment,
a red pixel, a green pixel and a blue pixel can be
formed by applying the above color compositions onto a
transparent substrate by use of a printing method, an
10 inkjet method, a photolithography method or the like.
The formation of varied-color filter segments by
use of a printing method excels in cost reduction and
mass productivity as a process for producing a color
filter because patterning can be performed by simply
15 repeating the printing and drying of the above varied
color compositions prepared as printing inks. Further,
due to the advance of printing techniques, it is now
feasible to print a very fine pattern with high
dimensional precision and smoothness. In printing, the
20 ink is preferably comprised of a composition formulated
so that drying or solidification thereof does not occur
on the surface of a printing plate or blanket.
Moreover, it is also important to control the fluidity
of the ink on a printing machine. The viscosity of the
25 ink can be regulated by selecting a dispersant and/or
an extender pigment.
The inkjet method is a method in which by means of
V 44
an inkjet apparatus including a plurality of minute
injection ports (inkjet heads) provided for individual
colors, direct printing formation is performed on a
transparent substrate or a substrate provided with an
5 active element, such as a TFT.
When each of color pixels is formed byphotolithography
process, the above color composition
formulated as a solvent-developable or alkalidevelopable
color resist is applied onto the surface of
10 a transparent substrate by any of coating methods, such
as spray coating, spin coating, slit coating or roll
coating, so that the thickness of a film upon drying
ranges from 0.2 to 10 urn. At the drying of the coated
film, use may be made of a vacuum dryer, a convection
15 oven, an IR oven, a hot plate or the like. According
to necessity, the dried film is exposed to ultraviolet
rays through a mask with a given pattern provided in or
out of contact with the film. Subsequently, the
resultant film is either immersed in a solvent or an
20 alkali developer, or sprayed with a developer by means
of a sprayer, so as to remove any unhardened portion,
thereby attaining desired patterning. Thereafter, the
same procedure is repeated for other colors. Thus, a
color filter can be obtained. For accelerating the
25 polymerization of the color resists, heating may be
applied thereto according to necessity. This
photolithography process makes it feasible to
manufacture a color filter with precision higher than
in the use of the above printing method.
In the development, an aqueous solution of sodium
carbonate, sodium hydroxide, etc., is used as an alkali
5 developer. Use also can be made of an organic alkali,
such as dimethylbenzylamine, triethanolamine or the
like. Further, the developer may be loaded with a
defoaming agent or a surfactant. As the development
processing method, use can be made of a shower
10 developing method, a spray developing method, a dip
(immersion) developing method, a puddle (liquid
accumulation) developing method, or the like.
In order to enhance the sensitivity to ultraviolet
exposure, ultraviolet exposure can be performed after a
15 procedure comprising coating the color resist having
undergone application and drying with a water-soluble
or alkali-soluble resin, for example, polyvinyl alcohol
or a water-soluble acrylic resin and drying the coated
resist to thereby form a film capable of preventing any
20 polymerization inhibition by oxygen.
The color filter according to this embodiment can
also be fabricated by an electrodeposition method, a
transfer method or the like aside from the abovementioned
methods. The electrodeposition method is a
25 method in which taking advantage of a transparent
conductive film formed on a transparent substrate, a
color filter is fabricated by the electrodeposition
formation of varied-color filter segments on the
transparent conductive film through the electrophoresis
of colloidal particles. The transfer method is a
method comprising forming in advance a color filter
5 layer on the surface of a releasable transfer base
sheet and then transferring this color filter layer
onto a desired transparent substrate.
EXAMPLES
Some Examples of the present invention will be
10 described below.
The present invention will be specifically
described below by way of its examples. However, the
gist of the present invention is in no way limited to
these examples. Various changes and modifications can
15 be made without departing from the spirit of the
inventions. With respect to the compositions appearing
in Examples, the contents without exception refer to
mass ratios, and the parts are parts by mass.
[Preparation of acrylic resin solution]
20 800 parts of cyclohexanone was placed in a
reaction vessel and heated to 100°C while introducing
nitrogen gas in the vessel. While maintaining the
temperature, a mixture of the following monomers and
thermal polymerization initiator was dropped thereinto
25 over a period of an hour, thereby performing a
polymerization reaction.
47
Styrene 60.0 parts I
Methacrylic acid 60.0 parts 1
Methyl methacrylate 65.0 parts I
Butyl methacrylate 65.0 parts 1
5 Azobisisobutyronitrile 10.0 parts I
After the dropping, the reaction was continued at I
100°C for 3 hours. Thereafter, a solution of 2.0 parts I
of azobisisobutyronitrile in 50 parts of cyclohexanone 1
was added thereto, and the reaction was further 1
10 continued at 100°C for an hour. Thus, a solution of 1
acrylic resin whose weight average molecular weight was I
about 40,000 was obtained. I
The solution was cooled to room temperature. The 1
cooled resin solution was sampled in an amount of about |
15 2 g and dried by heating at 180°C for 20 minutes, and |
the nonvolatile content thereof was measured. 1
Cyclohexanone was added to the above synthesized resin 1
solution so that the nonvolatile content became 20%, |
thereby obtaining an intended acrylic resin solution. |
20 Black, red, green and blue color compositions were 1
prepared in the following manner. 1
[Preparation of black pigment 1] I
A mixture of the following components was I
homogeneously blended, dispersed with glass beads of I
25 1-mm diameter by means of a sand mill for 5 hours, and I
passed through a 5-um filter. Thus, a dispersion of I
black pigment 1 was obtained. |
© 48
Red pigment: C. I. Pigment Red 254
("Irgaphor Red B-CF" produced by Ciba Specialty
Chemicals Inc.) 31.6 parts
Blue pigment: C. I. Pigment Blue 15:6
5 ("Lionol Blue ES" produced by Toyo Ink Mfg. Co., Ltd.)
34.2 parts
Carbon pigment ("#47" produced by Mitsubishi Chemical
Corporation) 11.1 parts
Dispersant ("Disperbyk-161" produced by BYK Chemie)
10 5 parts
Acrylic varnish (solid content 20 mass%)
72 parts
[Preparation of black pigment 2]
A mixture of the following components was
15 homogeneously blended, dispersed with glass beads of
1-mm diameter by means of a sand mill for 5 hours, and
passed through a 5-jim filter. Thus, a dispersion of
black pigment 2 was obtained.
Red pigment: C. I. Pigment Red 254
20 ("Irgaphor Red B-CF" produced by Ciba Specialty
Chemicals Inc.) 39.6 parts
Blue pigment: C. I. Pigment Blue 15:6
("Lionol Blue ES" produced by Toyo Ink Mfg. Co., Ltd.)
42.8 parts
25 Dispersant ("Disperbyk-161" produced by BYK Chemie)
5 parts
Acrylic varnish (solid content 20 mass%)
72 parts
[Preparation of black pigment 3]
A mixture of the following components was
5 homogeneously blended, and agitated by means of a beads
mill disperser. Thus, a dispersion of carbon black was
obtained.
Carbon pigment ("#47" produced by Mitsubishi Chemical
Corporation) 20 parts
10 Dispersant ("Disperbyk-161" produced by BYK Chemie)
8.3 parts
Copper phthalocyanine derivative (produced by Toyo Ink
Mfg. Co., Ltd.) 1.0 part
Propylene glycol monomethyl ether acetate
15 71 parts
[Preparation of black composition 1]
A mixture of the following components was
homogeneously blended, and passed through a 5-um
filter. Thus, a black color composition 1 was
20 obtained.
Black pigment 1 54.2 parts
Acrylic resin solution 8 parts
Dipentaerythritol penta/hexaacrylate ("M-402" produced
by Toagosei Co., Ltd.) 4.7 parts
25 Photopolymerization initiator ("IRGACURE OXE 02"
produced by Ciba Geigy) 0.9 part
W 50
Sensitizer ("EAB-F" produced by Hodogaya Chemical Co.,
Ltd.) 0.1 part
Leveling agent ("Disperbyk-163" produced by BYK Chemie)
0.1 part
5 Cyclohexanone 16 parts
Propylene glycol monomethyl ether acetate
16 parts
[Preparation of black composition 2]
A black composition 2 was prepared from the same
10 components by the same procedure as in the preparation
of black composition 1, except that the black pigment 2
was used as the dispersion.
[Preparation of black composition 3]
A mixture of the following components was
15 homogeneously blended, and passed through a 5-um
filter. Thus, a black color composition 3 was
obtained.
Black pigment 3 25.2 parts
Acrylic resin solution 18 parts
20 Dipentaerythritol penta/hexaacrylate ("M-402" produced
by Toagosei Co., Ltd.) 5.2 parts
Photopolymerization initiator ("IRGACURE OXE 02"
produced by Ciba Geigy) 1.2 part
Sensitizer ("EAB-F" produced by Hodogaya Chemical Co.,
25 Ltd.) 0.3 part
Leveling agent ("Disperbyk-163" produced by BYK Chemie)
0.1 part
Cyclohexanone 25 parts
Propylene glycol monomethyl ether acetate
25 parts
[Preparation of red pigment 1]
5 A mixture of the following components was
homogeneously blended, dispersed with glass beads of
1-mm diameter by means of a sand mill for 5 hours, and
passed through a 5-urn filter. Thus, a dispersion of
red pigment 1 was obtained.
10 Red pigment: C. I. Pigment Red 254
("Irgaphor Red B-CF" produced by Ciba Specialty
Chemicals Inc.) 8 parts
Red pigment: C. I. Pigment Red 177
("Cromophtal Red A2B" produced by Ciba Specialty
15 Chemicals Inc.) 10 parts
Yellow pigment: C. I. Pigment Yellow 150
("E4GN-GT" produced by LANXESS) 2 parts
Dispersant ("ADISPER PB821" produced by Ajinomoto Fine-
Techno Inc.) 2 parts
20 Acrylic varnish (solid content: 20 mass%) 108 parts
[Preparation of red pigment 2]
A dispersion of red pigment 2 was prepared from a
mixture of the following components in the same manner
as in the preparation of the red pigment 1.
25 Red pigment: C. I. Pigment Red 254
("Irgaphor Red B-CF" produced by Ciba Specialty
Chemicals Inc.) 11 parts
V 52
Red pigment: C. I. Pigment Red 177
("Cromophtal Red A2B" produced by Ciba Specialty
Chemicals Inc.) 9 parts
Dispersant ("ADISPER PB821" produced by Ajinomoto Fine-
5 Techno Inc.) 2 parts
Acrylic varnish (solid content: 20 mass%) 108 parts
[Preparation of red composition 1]
A mixture of the following components was
homogeneously blended, and passed through a 5-um
10 filter. Thus, a red color composition was obtained.
Red pigment 1 42 parts
Acrylic resin solution 18 parts
Dipentaerythritol penta/hexaacrylate ("M-402" produced
by Toagosei Co., Ltd.) 4.5 parts
15 Photopolymerization initiator ("IRGACURE-907" produced
by Ciba Specialty Chemicals Inc.) 1.2 parts
Sensitizer ("EAB-F" produced by Hodogaya Chemical Co.,
Ltd.) 2.0 parts
Cyclohexanone 32.3 parts
20 [Preparation of red composition 2]
A red composition 2 was prepared from the same
components by the same procedure as in the preparation
of red composition 1, except that the red pigment 2 was
used as the dispersion.
25 [Preparation of green pigment 1]
A mixture of the following components was
homogeneously blended, dispersed with glass beads of
© 53
1-mm diameter by means of a sand mill for 5 hours, and
passed through a 5-um filter. Thus, a dispersion of
red pigment 1 was obtained.
Green pigment: C. I. Pigment Green 58
5 ("Phthalocyanine Green A110" produced by DIC
Corporation) 10.4 parts
Yellow pigment: C. I. Pigment Yellow 150
("E4GN-GT" produced by LANXESS) 9.6 parts
Dispersant ("Disperbyk-163" produced by BYK Chemie)
10 2 parts
Acrylic varnish (solid content: 20 mass%)
66 parts
[Preparation of green pigment 2]
A dispersion of green pigment 2 was prepared from
15 a mixture of the following components in the same
manner as in the preparation of the green pigment 1.
Green pigment: C. I. Pigment Green 58
("Phthalocyanine Green A110" produced by DIC
Corporation) 10.4 parts
20 Yellow pigment: C. I. Pigment Yellow 150
("E4GN-GT" produced by LANXESS) 3.2 parts
Yellow pigment: C. I. Pigment Yellow 138
7.4 parts
Dispersant ("Disperbyk-163" produced by BYK Chemie)
25 2 parts
Acrylic varnish (solid content: 20 mass%)
66 parts
*
© 54
[Preparation of green pigment 3]
A dispersion of green pigment 3 was prepared from
a mixture of the following components in the same
manner as in the preparation of the green pigment 1.
5 Green pigment: C. I. Pigment Green 36
("Lionol Green 6YK" produced by Toyo Ink Mfg. Co.,
Ltd.) 10.4 parts
Yellow pigment: C. I. Pigment Yellow 150
i
("E4GN-GT" produced by LANXESS) 9.6 parts |
10 Dispersant ("Disperbyk-163" produced by BYK Chemie) }
2 parts |
Acrylic varnish (solid content: 20 mass%) I
!
66 parts j
[Preparation of green composition 1] '
i
f
15 A mixture of the following components was j
homogeneously blended, and passed through a 5-urn [
i
filter. Thus, a red color composition was obtained. !
Green pigment 1 4 6 parts !
Acrylic resin solution 8 parts I
20 Dipentaerythritol penta/hexaacrylate ("M-402" produced (
i
t
by Toagosei Co., Ltd.) 4 parts )
s
Photopolymerization initiator ("IRGACURE OXE 02" \.
i
produced by Ciba Geigy) 1.2 parts |
Photopolymerization initiator ("IRGACURE-907" produced
25 by Ciba Specialty Chemicals Inc.) 3.5 parts
Sensitizer ("EAB-F" produced by Hodogaya Chemical Co.,
t
Ltd.) 1.5 parts
•
I
i
i
Cyclohexanone 5.8 parts
Propylene glycol monomethyl ether acetate 30 parts i
[Preparation of green composition 2] I
i
A green composition 2 was prepared from the same I
5 components by the same procedure as in the preparation s
of green composition 1, except that the green pigment 2 f
was used as the dispersion. j
[Preparation of green composition 3]
A green composition 3 was prepared from the same
10 components by the same procedure as in the preparation
of green composition 1, except that the green pigment 3
•
was used as the dispersion.
[Preparation of blue pigment 1]
A mixture of the following components was I
15 homogeneously blended, dispersed with glass beads of j
1-mm diameter by means of a sand mill for 5 hours, and •
passed through a 5-um filter. Thus, a dispersion of j
i
blue pigment was obtained. I
Blue pigment: C. I. Pigment Blue 15:6 [
20 ("Lionol Blue ES" produced by Toyo Ink Mfg. Co., Ltd.) j
I
52 parts j
i Dispersant ("SOLSPERSE 20000" produced by Zeneca |
i
Limited) 6 parts j
i
Acrylic varnish (solid content 20 mass%) 200 parts
25 [Preparation of blue pigment 2]
A mixture of the following components was
homogeneously blended, dispersed with glass beads of
I
i
W 56
1-mm diameter by means of a sand mill for 5 hours, and
passed through a 5-um filter. Thus, a dispersion of
blue pigment was obtained.
Blue pigment: C. I. Pigment Blue 15:6
5 ("Lionol Blue ES" produced by Toyo Ink Mfg. Co., Ltd.)
49.4 parts
Dispersant ("SOLSPERSE 20000" produced by Zeneca
Limited) 6 parts
Acrylic varnish (solid content 20 mass%)
10 200 parts
This dispersion was loaded with the following
violet dye powder, and agitated well, thereby obtaining
a blue pigment 2.
Violet dye: NK-9402 produced by Hayashibara Biochemical
15 Laboratories 2.6 parts
[Preparation of blue composition 1]
Thereafter, a mixture of the following components
was homogeneously blended, and passed through a 5-um
filter. Thus, a blue color composition was obtained.
20 Blue pigment 1 16.5 parts
Acrylic resin solution 25.3 parts
Dipentaerythritol penta/hexaacrylate ("M-402" produced
by Toagosei Co., Ltd.) 1.8 parts
Photopolymerization initiator ("IRGACURE-907" produced
25 by Ciba Specialty Chemicals Inc.) 1.2 parts
Sensitizer ("EAB-F" produced by Hodogaya Chemical Co.,
Ltd.) 0.2 part
©
Cyclohexanone 25 parts
Propylene glycol monomethyl ether acetate
30 parts
[Fabrication of color filter]
5 Color filters were fabricated by combining
obtained color compositions through the following
procedure.
It should be noted that schematic cross sections
of two forms of color filter substrates according to
10 the following Examples are shown in FIG. 3 and FIG. 4.
In these figures, each of the color filters is shown
with its film surface facing downward. In the actual
fabrication process, however, fabrication is processed
with the film surface facing upward.
15 Example 1
First, the black color composition 1 was applied
on a glass substrate 10 as shown in FIG. 3 by a spin
coating method so that the film thickness was 2.0 um,
and prebaked in a clean oven at 70°C for 20 minutes.
20 Subsequently, the resultant substrate was cooled to
room temperature, and exposed to ultraviolet rays
through a photomask by means of an ultrahigh pressure
mercury lamp. Thereafter, the substrate was developed
by spraying an aqueous solution of sodium carbonate
25 held at 23°C, rinsed with ion-exchanged water, and
dried in air. Further, the substrate was postbaked in
a clean oven at 230°C for 30 minutes. Thus, a
© 58
stripe-patterned black matrix BM was provided on the
substrate.
Subsequently, in the same manner, the red color
composition 1 was applied by a spin coating method so
5 that the film thickness was 2.8 urn, dried, exposed by
means of an exposure apparatus so as to obtain a
stripe-patterned color layer, and developed. Thus, red
pixels R were provided.
Thereafter, also in the same manner, the green
10 color composition 1 was applied by a spin coating
method so that the film thickness was 2.8 um, dried,
exposed by means of an exposure apparatus so that a
stripe-patterned color layer was formed in a place
other than that of the red pixels, and developed.
15 Thus, green pixels G were provided in a position
adjacent to the red pixels R.
Moreover, in exactly the same manner as in the
formation of the red and green pixels, blue pixels B
were formed through the application of the blue color
20 composition 1 in a film thickness of 2.8 um in a
position adjacent to the red pixels R and green pixels
G.
As a result, there was obtained a color filter
substrate comprising three-color-stripe patterned color
25 pixels including the red pixels R, green pixels G and
blue pixels B provided on the transparent substrate 10,
as shown in FIG. 3.
i
© 59
Example 2
In the same manner as in Example 1, a color filter
substrate was fabricated using the black color
composition 2, red color composition 2, green color
5 composition 2 and blue color composition 2.
In Example 2, referring to FIG. 4, a frame portion
F was formed of a light-shielding layer (same material
and process as for the black matrix) of about 3 mm
width so as to surround effective display regions of 10 liquid crystal. A red layer 3 and a blue layer 4 were «
superimposed on the frame portion F. The lighti
i
shielding property of the frame portion F comprised of j
a black matrix material can be supplemented by the j
i
superimposition of the red layer 3 and blue layer 4, so j
15 that an optical density of 3 or higher can be ensured. ;
These two color layers can be formed while regulating !
•
j
the thickness thereof, for example, by use of a j
halftone mask. The relative dielectric constant of the i
i
i
i
blue layer 4 is smaller than those of other color t
20 layers, so that in the stacking of color layers, it is
advantageous to superimpose the blue layer 4 on a side •
close to the liquid crystal. j
Although not shown in the figures, a spacer [
i
I
comprised of, superimposed one upon another, a red 25 layer, green layer and blue layer was provided in j
j
accordance with the thickness of a liquid crystal layer j
to be incorporated in a liquid crystal display device. j
| 1 i
i i
i t
i i I
i
© 60
:
The relative dielectric constant of the blue layer is
smaller than those of other color layers, as mentioned
above, so that the blue layer can be used as an
>
uppermost layer of the layer-stacked spacer. Further,
5 the blue layer can be provided so as to cover the
spacer.
Example 3
A cross section of an FFS mode liquid crystal
display device according to this Example is shown in
10 FIG. 5.
The color filter substrate 20 used in this Example
was the color filter substrate shown in FIG. 4 of
Example 2. In an array substrate 30 comprising active
elements (TFTs), a pixel electrode 31 was disposed
15 through an insulating layer 22 on a solid-formed common I
electrode 32. The TFTs, an alignment film, a j
i
polarizer, a retarder, etc., are not shown. j
j
The color filter substrate 20 and the array
substrate 30 were bonded to each other in opposite
20 relationship through a liquid crystal 26 whose
dielectric constant anisotropy was 4.5 (liquid crystal
with a positive dielectric constant anisotropy). The
alignment film not shown underwent rubbing treatment,
thereby realizing a liquid crystal alignment horizontal
25 to the substrate surface. The pixel electrode 31 had a
comb-shaped pattern perpendicular to the sheet. The
rubbing direction thereof was not completely parallel
©
to the line of the comb pattern, and rubbing was ;
performed at an angle deviated therefrom by about
5 degrees.
Comparative Example
5 In the same manner as in Example 1, a color filter
substrate was fabricated using the black color
composition 3, red color composition 1, green color I
composition 3 and blue color composition 1.
Table 1 below shows the relative dielectric
10 constant values of individual color layers, together
with color resist compositions, employed in Example 1,
Example 2 and Comparative Example. •ft
W 62
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G C G C *H ^ O
CD CD CD ( P - r H ^ ; in ^r *a< Ci
M M D i M g - „ r o n n
m O 0> -H Di O O ^
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r ^ " D X ) 0 T 3 - r H < M ( M C S l O ]
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•H O O O
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•^ C rV
~ 0 CD O • «3LO IT) IT)
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^ rH oi • H E in m m ro
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•H 0i O O 3 > M C
-P -H Pj -H rH -H -P rO
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W 63
Table 1 {
Evaluation result Comparative Example 1 J
BM Red Green Blue
Pigment black red green blue :
pigment pigment pigment pigment
3 1 3 1
Composition black red green blue
comp. 3 comp. 1 comp. 3 comp. 1
Chromaticity x - 0.618 0.313 0.135
y - 0.326 0.56 0.118
OP value (/pm) 2.2 - - -
Relative 120 16.2 3.6 4.6 3.8
dielectric Hz
constant 240 16.1 3.6 4.5 3.8
Hz
480 15.5 3.5 4.5 3.7 ;
Hz
As apparent from Table 1 above, all the relative dielectric constant values measured at frequencies of I
5 120, 240 and 480 Hz of the red layer, green layer and blue layer used in each of Examples 1 and 2 fell within
the range of 2.9 to 4.4. These relative dielectric
constant values fall within ±0.3 of the average
relative dielectric constant of the red layer, green
10 layer and blue layer. In contrast, the main coloring agent of the green ;
layer in Comparative Example was a halogenated copper
phthalocyanine green pigment. The relative dielectric
constant values measured at frequencies of 120, 240 and I
15 480 Hz of the color layer were as large as 4.6, 4.5 and 5
4.5, respectively, thereby being outside the range of
2.9 to 4.4. The differences thereof from the average ;
relative dielectric constant values of 4.0, 4.0 and 3.9 at respective frequencies of the red layer, green layer
and blue layer were as large as 0.6, 0.5 and 0.6,
respectively, thereby being outside ±0.3 of the
average.
5 Moreover, carbon was used as the black pigment of
the black matrix in Comparative Example. The relative
dielectric constant values measured at frequencies of
120, 240 and 480 Hz of the black color layer (BM) in
Comparative Example were as large as 16.2, 16.1 and
10 15.5, respectively, and the differences thereof from
the relative dielectric constants of the red layer were
as extremely large as 12.6, 12.5 and 12.0,
respectively.
A color filter substrate was formed by using the 15 color resists (color compositions) and black color •
composition (BM) of the formulations indicated in Table {
1 above. This color filter substrate was bonded to an
array substrate through a liquid crystal of 4.5 j
dielectric constant anisotropy in the same manner as in 20 Example 3, thereby obtaining a liquid crystal display device of Comparative Example. j
In each of the liquid crystal display device of
Example 3 and the liquid crystal display device of
Comparative Example, a driving voltage was applied
25 between the pixel electrode and common electrode of the
array substrate, thereby displaying images. On the j
liquid crystal display device of Example 3, there was
no display failure and images of excellent quality were
obtained. By contrast, on the liquid crystal display ;'
device of Comparative Example, red unevenness and light I
leakage at pixel aperture edges were observed. (

^l' 66
We Claim:
1. A color filter substrate for use in a fringefield
switching mode liquid crystal display wherein the
color filter substrate and an array substrate provided
5 with a comb-shaped pixel electrode having an electrode
width of 10 lam or less are arranged facing each other
with a liquid crystal layer interposed therebetween,
the color filter substrate comprising:
a transparent substrate;
10 a black matrix provided on the transparent
substrate, comprising an organic pigment as a main
coloring agent;
a red pixel, a green pixel and a blue pixel which
are provided in regions partitioned by the black matrix
15 on the transparent substrate and each have a relative
dielectric constant of 2.9 or more but 4.4 or less, as
measured at a frequency at which the liquid crystal is
driven; and
a transparent resin layer provided on the red
20 pixel, the green pixel and the blue pixel,
wherein the relative dielectric constant of each
of the color pixels falls within ±0.3 of an average
relative dielectric constant of the red pixel, the
green pixel and the blue pixel.
25 2. The color filter substrate according to
claim 1, wherein a relative dielectric constant of the
black matrix, as measured at a frequency at which the
liquid crystal is driven, 2.9 or more but 4.4 or less.
3. The color filter substrate according to
claim 1, wherein a relative dielectric constant of the
black matrix, as measured at a frequency at which the
5 liquid crystal is driven, is smaller than a value of
dielectric constant anisotropy exhibited by the liquid
crystal used in the fringe-field switching mode.
4. The color filter substrate according to
claim 1, wherein a coloring agent of the black matrix
10 comprises the organic pigment in an amount of 92 mass%
or more based on the whole amount of the coloring
agent, and comprises carbon as a balance.
5. The color filter substrate according to
claim 1, wherein a main coloring agent of the green
15 pixel is a halogenated zinc-phthalocyanine pigment.
6. The color filter substrate according to
claim 1, wherein the average relative dielectric
constant of the red pixel, the green pixel and the blue
pixel is smaller than a value of dielectric constant
20 anisotropy exhibited by the liquid crystal used in the
fringe-field switching mode.
7. The color filter substrate according to
claim 1, wherein the frequency applied in the measuring
of the relative dielectric constant is a frequency
25 ranging from 120 to 480 Hz.
8. The color filter substrate according to
claim 1, wherein the black matrix has a pattern shape
c
configured to partition four sides of each of the color
pixels in a lattice form or two sides thereof in a
stripe form and has a frame pattern surrounding an
effective display region of liquid crystal display, and
5 wherein on the frame pattern, one of a blue layer used
in forming the blue pixel and a red layer used in
forming the red pixel is formed, or two thereof are
superimposed one upon the other.
9. The color filter substrate according to
10 claim 1, wherein the black matrix has a pattern shape
configured to partition four sides of each of the color
pixels in a lattice form or two sides thereof in a
stripe form and has a frame pattern surrounding an
effective display region of liquid crystal display, and
15 wherein a red layer used in forming the red pixel and a
blue layer used in forming the blue pixel are
superimposed in this order one upon the other on the
frame pattern.
10. A fringe-field switching mode liquid crystal
20 display comprising the color filter substrate according
to any of claims 1 to 9.
11. A fringe-field switching mode liquid crystal
display comprising:
a color filter substrate comprising a transparent
25 substrate, a black matrix provided on the transparent
substrate, a red pixel, a green pixel and a blue pixel
which are provided in regions partitioned by the black
matrix on the transparent substrate and each have a
relative dielectric constant of 2.9 or more but 4.4 or
less as measured at a frequency at which the liquid
crystal is driven, and a transparent resin layer
5 provided on the red pixel, the green pixel and the blue
pixel, wherein the relative dielectric constant of each
of the color pixels falls within ±0.3 of an average
relative dielectric constant of the red pixel, the
green pixel and the blue pixel;
10 an array substrate disposed facing the color
filter substrate, and provided with a comb-shaped pixel
electrode having an electrode width of 10 pm or less;
and
a liquid crystal layer interposed between the
15 color filter substrate and the array substrate.
12. The fringe-field switching mode liquid
crystal display according to claim 11, characterized in
that the electrode width of the comb-shaped pixel
electrode is 2 ]im or more but 5 \im or less.
20 13. The liquid crystal display according to
claim 11, wherein a relative dielectric constant of the
black matrix, as measured at a frequency at which the
liquid crystal is driven, is 2.9 or more but 4.4 or
less.
25 14. The liquid crystal display according to
claim 11, wherein a relative dielectric constant of the
black matrix, as measured at a frequency at which the
^*^ 70
liquid crystal is driven, is smaller than a value of
dielectric constant anisotropy exhibited by the liquid
crystal used in the fringe-field switching mode.
15. The liquid crystal display according to
5 claim 11, wherein a coloring agent of the black matrix
comprises an organic pigment in an amount of 92 mass%
or more based on the whole amount of the coloring agent
and comprises carbon as a balance.
16. The liquid crystal display according to
10 claim 11, wherein a main coloring agent of the green
pixel is a halogenated zinc-phthalocyanine pigment.
17. The liquid crystal display according to
claim 11, wherein the average relative dielectric
constant of the red pixel, the green pixel and the blue
15 pixel is smaller than a value of dielectric constant
anisotropy exhibited by the liquid crystal used in the
fringe-field switching mode.
18. The liquid crystal display according to
claim 11, wherein the frequency applied in the
20 measuring of the relative dielectric constant is a
frequency ranging from 120 to 480 Hz.
19. The liquid crystal display according to
claim 11, wherein the black matrix has a pattern shape
configured to partition four sides of each of the color
25 pixels in a lattice form or two sides thereof in a
stripe form and has a frame pattern surrounding an
effective display region of liquid crystal display, and
wherein on the frame pattern, one of a blue layer for
use in forming of the blue pixel and a red layer for
use in forming of the red pixel is formed, or two
thereof are superimposed one upon the other.
5 20. The liquid crystal display according to
claim 11, wherein the black matrix has a pattern shape
configured to partition four sides of each of the color
pixels in a lattice form or two sides thereof in a
stripe form and has a frame pattern surrounding an
10 effective display region of liquid crystal display, and
wherein a red layer used in forming the red pixel and a
blue layer used in forming the blue pixel are
superimposed in this order one upon the other on the
frame pattern.