JPH1078507A - Production of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a color filter by which a black matrix layer having an excellent pattern shape can be formed and low production cost can be realized. SOLUTION: Color filter layers 1 are formed at a specified distance on the surface of a transparent substrate 4. Then an ink 21 for a black matrix layer is applied on the surface of the transparent substrate 4 to fill the space 40 between adjacent color filter layers 1 with the ink 21. Then the ink on the surface of the transparent substrate 4 is removed to obtain a color filter having a black matrix layer 2 formed between adjacent color filter layers 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a color filter used for a liquid crystal display or the like.

[0002]

2. Description of the Related Art A liquid crystal display used as a display device in place of a cathode ray tube or the like realizes color display using a color filter. For example, as shown in FIG. 4, the color filter includes a red (R), green (G), and blue (B) color filter layer 1 patterned for each pixel, and a black matrix layer 2 for shading. Are formed on the transparent substrate 4.

[0003] The black matrix layer is composed of, for example, a lattice-like pattern provided at the boundary between the color filter layers of each color and the boundary between the pixels, and prevents light leakage between color filter layers of different colors and between pixels. In. Current,
A photosensitive resin in which a chromium film, a chromium oxide film, carbon black, or the like is dispersed is used for the black matrix layer. However, since both are patterned by the photolithography method, although a pattern with high dimensional accuracy can be formed, a large amount of expensive photoresist is required, the manufacturing process is complicated and complicated, and the yield is low, There is a problem that the manufacturing cost of the color filter increases.

[0004]

Therefore, in recent years, it has been studied to manufacture a color filter by a printing method such as intaglio offset printing. According to the printing method, an ink colored with a pigment or the like is printed on a transparent substrate, and a color filter layer or a black matrix layer of each color is formed by curing the ink, so that an expensive photoresist is unnecessary. The manufacturing process is simple and excellent in mass productivity. Therefore, the printing method is promising as a method capable of realizing cost reduction of the color filter.

[0005] In recent years, with the improvement of printing technology, offset printing presses and blankets capable of high-precision printing have been provided. Therefore, it is possible to print a pattern having an excellent shape, such as a sharp edge and excellent linearity, with extremely high dimensional accuracy in the color filter layer. However, for the black matrix layer, since the pattern shape is a lattice shape, the line width becomes large at the intersection of the patterns, and as a result, the image quality of the color filter is adversely affected, for example, the aperture ratio is reduced. There was such a problem.

Accordingly, an object of the present invention is to solve the above-mentioned technical problems and to provide a method of manufacturing a color filter capable of forming a black matrix layer having an excellent pattern shape and realizing a low cost color filter. It is.

[0007]

According to a method of manufacturing a color filter of the present invention, a color filter layer is formed on a surface of a transparent substrate.
A black matrix layer ink is applied to the surface of the transparent substrate, the ink is filled in the gap, and the ink on the surface of the transparent substrate is removed. The black matrix layer is formed with the ink remaining inside.

According to the method for manufacturing a color filter of the present invention described above, the black matrix layer is formed in the gap between the adjacent color filter layers. There is no problem such as thickening. Therefore, a black matrix layer having an excellent pattern shape can be formed. Further, in the present invention, since the black matrix layer can be formed without using the photolithography method, the cost of the color filter can be reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a color filter according to the present invention will be described with reference to FIG. First, as shown in FIG. 1A, a color filter layer 1 is formed on a surface of a transparent substrate 4 at predetermined intervals. Next, as shown in FIG. 1B, an ink 21 for a black matrix layer is applied to the surface of the transparent substrate 4, and the gap 21 between the adjacent color filter layers 1 is filled with the ink 21. Further, the transparent substrate 4
By removing the ink on the surface of (1), a color filter having a black matrix layer 2 formed between adjacent color filter layers 1 can be obtained as shown in FIG. 1 (c).

Hereinafter, the method for producing a color filter of the present invention will be described with reference to (i) formation of a color filter layer, and (ii)
Application of an ink for a black matrix layer, and (iii)
The process will be described in detail in three steps of removing the ink on the surface of the transparent substrate. (i) Formation of Color Filter Layer It is preferable to use a printing method for forming the color filter layer from the viewpoint of reducing the cost of the color filter. Various methods can be used for this printing method, but intaglio offset printing is particularly preferably used from the viewpoints of printing accuracy, linearity of the printing line, uniformity of the ink film thickness, and the like. Therefore, a method of manufacturing a color filter by intaglio offset printing will be described.

In the method of manufacturing a color filter by the intaglio offset printing method, the color filter layer ink filled in the intaglio recess is temporarily transferred to the surface of a blanket, and further transferred to the surface of a transparent substrate. , A color filter layer is formed. Color filter layers are usually red (R), green (G) and blue (B)
Of three colors. Examples of the pattern of the color filter layer include a dot pattern and a stripe pattern. When the color filter layer has a dot pattern, a lattice-like black matrix layer is formed. On the other hand, when the color filter layer has a stripe pattern, a stripe-shaped black matrix layer is formed.

As described above, the color filter layers are formed at a predetermined interval, and the interval is usually set to 10 according to the line width required for the black matrix layer.
It is set in the range of ７０70 μm. The size of the pattern of the color filter layer varies depending on the size of the color filter, but is usually set so that the line width of the pattern is 50 to 150 μm.

The intaglio substrate used for printing the color filter layer includes, for example, glass such as soda lime glass, non-alkali glass, quartz glass, low alkali glass and low expansion glass; fluororesin, polycarbonate resin, polyether sulfone resin , Resins such as polymethacrylic resins;
Metals such as stainless steel, copper, and low expansion alloy invar are used. Among them, it is preferable to use soft glass such as soda lime glass in order to reproduce a fine pattern with high accuracy.

The concave portions formed on the surface of the intaglio are formed according to the pattern of the color filter layer. The depth of the recess is not particularly limited, but is appropriately set in the range of usually 1 to 15 μm, preferably 5 to 10 μm, depending on the thickness of the color filter layer. The color filter layer ink is a vehicle containing a binder resin and a colorant. The binder resin is preferably excellent in various properties such as transparency, heat resistance, light resistance, solvent resistance, chemical resistance, adhesiveness to a transparent substrate, dispersibility of a colorant, and, for example, polyester-melamine. Resins, melamine resins, epoxy resins, epoxy-melamine resins and the like can be used. These resins are used alone or in combination of two or more.
Further, a curing catalyst such as an acid catalyst may be appropriately blended in the resin for the purpose of adjusting the curing speed of the resin.

The colorant is appropriately selected from, for example, an anthraquinone-based red pigment, a halogenated phthalocyanine-based green pigment, and a phthalocyanine-based blue pigment according to a desired color of the color filter layer. Also, for the purpose of adjusting the spectral characteristics of the color filter layer,
Red and green inks may contain yellow pigments such as isoindoline and isoindolinone, and blue inks may contain dioxazine violet pigments.

The ink for the color filter layer is prepared by blending the above exemplified binder resin, colorant, and, if necessary, a solvent and extender, and mixing them with a mixer such as a three roll or kneader. . The viscosity of such an ink is preferably low. Specifically, the viscosity is 1
0 to 30,000 poise (P), preferably 500 to 1
A suitable value is 0000 poise.

As the blanket used for printing the color filter, various types of conventionally known blankets can be used. In particular, it is preferable to use a silicone blanket whose surface is made of silicone rubber from the viewpoint of obtaining an excellent pattern shape. The transparent substrate of the color filter has a wavelength of 40
Those having high transmittance for light of 0 to 700 nm are preferable, for example, non-alkali glass, soda lime glass,
A glass substrate such as low alkali glass or a film such as polyether, polysulfone, or polyarylate is preferably used.

The ink for the color filter layer printed on the transparent substrate is usually cured by heating and drying at 80 to 300 ° C. for 10 to 240 minutes, preferably at 150 to 250 ° C. for 80 to 180 minutes. The next step is provided. In addition, if the color of the color filter layer ink does not change in the pattern shape by the next step,
In this step, it may not be completely cured, and may be, for example, a semi-cured state.

FIGS. 2A and 2B show the printing of the color filter layer.
When the offset printing machine shown in (1) is used, a color filter layer having extremely excellent printing accuracy can be formed. Fig. 2 (a),
In the offset printing press shown in (b), the intaglio 41 and the transparent substrate 4 are held on the base 5 at a predetermined interval, can move on the rail 54 laid on the base 51, and can be moved to any position. Can be stopped with high accuracy. The blanket 3 is a pinion gear 3 attached to both ends of the blanket cylinder 31.
0 and the pair of rack gears 6 fixed to the base 51 engage with each other to move while rotating. The blanket cylinder 31 has both ends of a shaft 34 rotatably held at the tip of an air cylinder 35, as in the conventional case.

The printing by the offset printing machine is performed as follows. First, the base plate 5 is moved so that the center line 63 of the intaglio 41 coincides with the reference position 60 located between the rotation start position 61 and the rotation end position 62 of the rack gear 6, and then the rotation start position 61. Then, the pinion gear 30 and the rack gear 6 are engaged with each other to bring the blanket 3 into contact with the surface of the intaglio 41 at a predetermined pressure (nip pressure). If the blanket 3 is moved to the rotation end position 62 in this state, the blanket 3 moves while rotating by the meshing of the two gears, and the ink filled in the concave portion (not shown) of the intaglio 41 is filled with the ink. Transferred to the surface (transfer step).

Next, after the center line 64 of the transparent substrate 4 is matched with the reference position 60, the pinion gear 30 and the rack gear 6 are engaged at the rotation start position 61, and the blanket 3 is fixed on the surface of the transparent substrate 4. At a pressure (nip pressure). At this time, the two gears mesh at the same position as in the transfer step. If the blanket 3 is moved to the rotation end position 62 in this state, the blanket 3 moves while rotating in the same rotation state as in the transfer step, and the ink (not shown) transferred to the surface of the blanket 3 is transparent. Transferred to the surface of the substrate 4 (printing step).

According to the offset printing machine, since the rack gear 6 and the pinion gear 30 mesh at the same position in both the transfer step and the print step, an error in the transfer position generated in the transfer step occurs in the print step. This can be offset by the error of the transfer position, and high-precision printing becomes possible. Specifically, the error (printing accuracy) between the transfer position of the ink printed by the offset printing machine and the position of the concave portion of the intaglio corresponding to the ink is a maximum of 5μ.
m, which sufficiently satisfies the printing accuracy required for the color filter. In addition, in the offset printing press shown in FIG. 2, in principle, printing accuracy is not degraded due to variations in accuracy when manufacturing the rack gear 6 and the pinion gear 30 and wear of the gear during continuous printing. Therefore, the printing accuracy is sufficiently maintained even when continuous printing of 100,000 sheets is performed.

(Ii) Application of ink for black matrix layer After the color filter layer is formed on the transparent substrate by the above-mentioned step (i), the ink for the black matrix layer is applied to the surface of the transparent substrate so as to be adjacent to each other. The gap between the color filter layers is filled with the ink. As a method of applying the ink for the black matrix layer, for example, (1) a method using a flexographic printing method, (2) a method using a screen printing method, (3) a method using a spin coating method, or (4)
Examples thereof include a method using a bar coater.

The ink for the black matrix layer is usually composed of a vehicle containing a binder resin and a colorant, and the same binder resin as that used for the ink for the color filter layer is used as the binder resin. it can. Examples of the coloring agent used in the ink for the black matrix layer include black pigments such as carbon black, iron oxide (iron black), titanium black, and iron sulfate. The amount of the coloring agent is appropriately set according to the optical density (OD value) of the black matrix layer and the viscosity of the ink. The optical density of the black matrix layer is 2.3 or more (visible light transmittance is about 0.5%
Or less), preferably 3.0 or more (the transmittance of visible light is 0.1 or less).
1% or less).

The ink for the black matrix layer is applied so that the thickness from the surface of the transparent substrate is usually 0.5 to 5 μm, preferably 1 to 3 μm, depending on the thickness of the color filter layer. You. To set the thickness of the black matrix layer ink within the above range, for example,
In the flexographic printing of (1), the depth of the concave portion on the anilox roll may be adjusted. In the screen printing of the above (2), the amount of ink to be put on the screen plate may be adjusted. In the spin coating of the above (3), the rotation speed of the transparent substrate may be adjusted. In the application by the bar coater of the above (4), a spacer corresponding to the thickness of the ink may be provided between the transparent substrate and a bar coater such as a metal bar.

The ink for a black matrix layer applied on a transparent substrate is usually at 80 to 300 ° C. for 10 to 24 hours.
The composition is cured by heating and drying for 0 minute, preferably at 150 to 250 ° C. for 80 to 180 minutes, and further subjected to the next step. If the color filter layer ink is not completely cured in the step (i), this step
In (ii), the heating conditions may be set so that the inks of both the color filter layer and the black matrix layer are completely cured.

(Iii) Removal of ink on the surface of the transparent substrate After the ink for the black matrix layer is applied onto the transparent substrate by the above-mentioned step (ii), the ink on the surface of the transparent substrate is removed, so that adjacent colors are removed. A color filter having a black matrix layer formed between the filter layers is obtained. As a method of removing the ink on the transparent substrate surface, for example, (a) polishing and removing the ink surface,
(b) removing the ink surface by slicing, or
(c) A method of removing the ink surface by etching or the like.

The degree of removal of the cured ink film may be such that the pattern of the color filter layer covered with the ink film appears on the surface with a desired line width. That is, when the color filter layer is formed by the printing method, the cross-sectional shape is rounded on the surface as shown by reference numeral 10 in FIG. Therefore, if the amount of removing the ink film is too small, the line width of the color filter layer appearing on the surface becomes thin, and the aperture ratio of the color filter may be reduced. On the other hand, when the amount of removing the ink film increases, the thickness of the color filter layer and the black matrix layer becomes too thin, and the contrast of the color filter may decrease.

The thickness of the color filter layer and the thickness of the black matrix layer are usually set in the range of 0.5 to 5 μm, preferably 1 to 3 μm.

[0030]

The present invention will be described below with reference to examples and comparative examples. In Examples and Comparative Examples shown below,
As the inks for the color filter layer and the black matrix layer, those obtained by kneading a polyester resin, a colorant and a solvent were used.

The polyester resin was synthesized using trimellitic anhydride, phthalic anhydride and adipic acid as the polybasic acid component and neopentyl glycol as the polyhydric alcohol component. As the colorant, red
(R) Anthraquinone red pigment in filter layer ink, green (G) halogenated phthalocyanine green pigment in filter layer ink, blue (B) phthalocyanine blue pigment in filter layer ink, black matrix layer Carbon black was used for each of the inks.
As the solvent, butyl carbitol acetate and a higher alcohol (13 to 15 carbon atoms) were used.

Example 1 In the printing of the color filter layer, an intaglio plate made of soda lime glass having a depth of 10 μm was used. The blanket used had a surface made of silicone rubber. FIG. 2 shows an offset printing press.
The following was used.

After sequentially printing the red (R), green (G) and blue (B) color filter layer inks on a transparent substrate, heating and curing at 230 ° C. for 3 hours without flattening. Thus, a color filter layer having a thickness of 2 μm consisting of the above three colors was formed. FIG. 3 shows the shape of the pattern of the color filter layer. The pattern 11 of the color filter layer was a dot pattern. As shown in FIG. 3, the line width w was 120 μm, the length d was 360 μm, and the pattern interval p was 70 μm.

Next, an ink for a black matrix layer is printed on the surface of the transparent substrate on which the color filter layer is formed by a flexographic printing machine, and the gap between adjacent color filter layers is filled with the ink while the transparent ink is filled. An ink film having a thickness of 5 μm from the surface of the substrate was formed. further,
The ink was cured by heating at 230 ° C. for 3 hours in an oven.

Next, a rotary polishing machine having a diameter of 20 cm (Model “TCLD-1000” manufactured by Nanotech Machines)
To remove the ink on the surface of the transparent substrate, and reduce the thickness of the color filter layer and the black matrix layer to 1.2 μm.
m to obtain a color filter. Note that α-alumina having a particle size of 3 μm was used as a roughening abrasive, and α-alumina having a particle size of 0.1 μm was used as a finishing abrasive. The load at the time of polishing was 180 kg / cm ² . The polishing rate was set such that the film thickness was reduced by 2 μm in one minute at the time of rough cutting, and was set so that the film thickness was reduced by 0.1 μm in one minute at the time of finish polishing.

After polishing, the steps on the surface of the color filter layer and the black matrix layer were measured to evaluate the flatness of the surface. In addition, the thickness of the ink and the level difference of the surface are measured by a stylus type surface roughness meter (Model “P-10” manufactured by Tencor).
It measured using. The pattern shape of the black matrix layer in the color filter obtained in Example 1 was extremely good, such as excellent linearity. Further, the steps on the surfaces of the black matrix layer and the color filter layer were 0.3 μm at the maximum, and the flatness was very excellent.

Example 2 In the same manner as in Example 1, red (R),
Green (G) and blue (B) color filter layer inks were sequentially printed. Next, a black matrix layer ink is applied to the surface of the transparent substrate by a spin coater, and the gap between adjacent color filter layers is filled with the ink, and the thickness from the surface of the transparent substrate is 7 μm. An ink film was formed. Further, the ink was heated in an oven at 230 ° C. for 3 hours to cure the ink.

Next, the ink on the surface of the transparent substrate was removed using a thin film slicer, and the thickness of the color filter layer and the black matrix layer was adjusted to 1.5 μm to obtain a color filter. The steps on the surfaces of the color filter layer and the black matrix layer were measured in the same manner as in Example 1. The pattern shape of the black matrix layer in the color filter obtained in Example 2 was extremely good, as in Example 1. Further, the steps on the surfaces of the black matrix layer and the color filter layer were at most 0.5 μm, and the flatness was good.

COMPARATIVE EXAMPLE 1 A metal chromium film formed on the surface of a transparent substrate was patterned by a photolithography method to have a line width of 60 μm and a pitch of 180 μm.
A black matrix layer having a thickness of 0.1 μm and having a lattice-like pattern was formed. Next, on the surface of the transparent substrate on which the black matrix layer was formed, a red (R)
, Green (G) and blue (B) color filter layer inks were sequentially printed. Printing of the color filter layer ink was performed in the same manner as in Example 1 using an offset printing machine shown in FIG. The color filter layer thus formed was subjected to a flattening treatment, heated in an oven at 230 ° C. for 180 minutes, and cured to obtain a color filter.

In the color filter obtained in Comparative Example 1, the printing shape and the dimensional accuracy of the color filter layer were almost the same as those of Examples 1 and 2, and were very good. However, since the thickness of the portion of the color filter layer that overlaps the black matrix layer is thinner by the thickness of the black matrix layer, the shrinkage ratio of the ink at the time of curing is different, and the surface step after curing is large. That is, the steps on the surface of the color filter layer and the black matrix layer have a maximum of 1.
2 μm, and the flatness was practically inappropriate. In addition, since the photolithography method was used to form the black matrix layer, there was a problem that the manufacturing cost was high.

Comparative Example 2 An ink for a black matrix layer was printed on the surface of a transparent substrate, heated and dried to form a black matrix layer similar to that of Comparative Example 1. For this printing, an offset printing machine shown in FIG. 2 was used. The blanket and black matrix ink used for printing are
Same as Example 1. The intaglio printing plate was the same as that used in Example 1 except that the concave portions corresponded to the pattern of the black matrix layer.

Next, red (R), green (G) and blue (B) color filter layer inks were sequentially printed on the openings of the black matrix layer. Printing of the color filter layer ink was performed in the same manner as in Example 1 using an offset printing machine shown in FIG. The color filter layer thus formed is subjected to a flattening process, and the temperature is set to 230 ° C. in an oven.
And cured for 180 minutes to obtain a color filter.

In the color filter obtained in Comparative Example 2, the line width of the pattern becomes large at the intersection of the black matrix layers, and the aperture ratio is reduced by about 15% as compared with the color filters of Examples 1 and 2. A problem arose. The steps on the surface of the color filter layer and the surface of the black matrix layer were almost the same as in Comparative Example 1, and were not practically appropriate.

[0044]

As described above, according to the present invention, it is possible to form a black matrix layer having an excellent printing shape and to realize a low cost color filter. Therefore, the method for manufacturing a color filter of the present invention is suitably used as a method for manufacturing a color filter corresponding to high image quality and low cost.

[Brief description of the drawings]

FIGS. 1A to 1C are diagrams illustrating a method for manufacturing a color filter of the present invention.

FIG. 2A is a sectional view showing an example of an offset printing machine used in the present invention, and FIG. 2B is a plan view thereof.

FIG. 3 is an explanatory diagram showing a pattern of a color filter layer.

FIG. 4 is a cross-sectional view illustrating an example of a color filter.

[Explanation of symbols]

 Reference Signs List 1 color filter layer 2 black matrix layer 4 transparent substrate 40 gap

Claims (1)

[Claims] 1. A color filter layer is formed on the surface of a transparent substrate with a gap between adjacent layers, and then a black matrix layer ink is applied to the surface of the transparent substrate.
A method for manufacturing a color filter, comprising: filling the gap with the ink, removing the ink on the surface of the transparent substrate, and forming a black matrix layer with the ink remaining in the gap.