JP2007293174A - Manufacturing method of color filter - Google Patents

Abstract

In a method for producing a color filter using an ink jet coating apparatus, the ink is discharged in a state where the ink viscosity is lowered. G. B. An object of the present invention is to provide a method for producing a color filter in which the film thickness of each color is uniform, unevenness is eliminated, and the color mixing or spilling phenomenon of each color does not occur due to vibration caused by high-speed conveyance and rotation after ejection.
A transparent substrate 2 placed on a substrate transfer stage 10 is R.D. G. B. In the manufacturing method of the color filter which discharges ink from the inkjet head unit 1 in which the nozzles for each color are arranged, the temperature of the substrate transport stage 10 is adjusted to a range of 25 to 50 ° C., and the ink viscosity at that time is 20 to This is a method for producing a color filter that has a range of 10 mPa · s, irradiates ultraviolet rays onto the transparent substrate to be carried out after the ink is discharged, and cures the discharged ink.
[Selection] Figure 1

Description

  The present invention relates to a method for producing a color filter mounted on a liquid crystal display such as a color television or a personal computer using an ink jet method.

  In recent years, with the development of personal computers, the increase in size of liquid crystal televisions and the spread of mobile phones, demand for color liquid crystal displays tends to increase. However, cost reduction is indispensable for further spread, and there is an increasing demand for cost reduction of a color filter having a large cost ratio.

  Currently, the color filter manufacturing method includes a dyeing method, a pigment dispersion method, a printing method, an electrodeposition method, and an ink jet method.

  The above dyeing method forms a water-soluble polymer to be dyed on a glass substrate, patterns it into a desired shape through a photolithography process, and then immerses it in a dyeing solution to obtain a colored pattern. This is repeated three times. G. B. The color filter obtained by this method is widely used in color solid-state imaging devices (CCDs) at present because of its high transmittance and abundant hue and high degree of perfection of the technology. However, since it uses a dye and is inferior in light resistance and has a large number of manufacturing processes, it has recently been replaced by a pigment dispersion method for liquid crystal display elements (LCD).

  The pigment dispersion method is the most mainstream color filter manufacturing method in recent years. In the manufacturing method, a resin layer in which a pigment is dispersed is first formed on a glass substrate and patterned through a photolithography process. This is repeated three times. G. B. The color filter layer is obtained, and although the degree of perfection of the technology is high, the number of steps is large and the cost is high.

  In addition, the printing method described above is, for example, by dispersing a pigment in a thermosetting resin and repeating printing three times. G. B. And then applying heat to cure the resin to obtain a color filter layer. G. B. Photolithography is not required for forming the layer, but there is a problem in terms of resolution and film thickness uniformity.

  In addition, the above electrodeposition method is an electrodeposition coating in which an electrodeposition film is formed by applying a high voltage of about 70 V on a previously patterned transparent electrode in an electrolytic solution in which a pigment is dispersed in a water-soluble polymer. Was repeated three times and R.M. G. B. In this method, it is necessary to pattern a transparent electrode in advance by photolithography and use this as an electrode for electrodeposition, and the shape of the pattern is limited. Has the disadvantage that it cannot be used.

  In order to compensate for the drawbacks of the above methods, color filter manufacturing methods using an ink jet method have been actively developed and studied. The method using the ink jet method has an advantage that the manufacturing process is simple and the cost is low.

An inkjet apparatus, which is an example of a color filter manufacturing apparatus using the inkjet system, includes a recording medium made of a transparent substrate and an R.P. G. B. Or Y. M.M. C. The ink jet head in which a plurality of nozzles are linearly arranged in each color is reciprocally moved in the main scanning direction relatively, and includes recording medium feeding means for intermittently feeding a set amount in the sub scanning direction. As is well known, the ink liquid is applied to the recording medium from the head while the ink is pressurized at a predetermined pressure by a pressure generator, and the ink is controlled from the nozzle on the nozzle forming surface toward the recording medium based on the pressure. A plurality of colored portions are simultaneously colored in each color by discharging as ink droplets of a certain size.

  The ink jet method has a characteristic that when the ink used is warmed to some extent to reduce the viscosity of the ink, the discharge performance is improved. However, since the temperature of the transparent substrate to which the ink is ejected is about 23 degrees which is the temperature of the clean room, the temperature of the ink on the substrate also becomes that temperature, and the wettability of the ink drops drastically. As a result, the film thickness of the applied (discharged) ink becomes non-uniform and appears uneven.

  Further, in the case of ejection onto a transparent substrate by the ink jet method, R.D. G. B. In order to apply the three colors simultaneously, when the transparent substrate is conveyed and rotated at a high speed, R. G. B. In order to solve the problem of ink film thickness unevenness due to coating (ejection), more colors are mixed by increasing the temperature of the ink (the temperature of the transparent substrate). Therefore, there is a problem that the ink spills as the film thickness increases.

  The present invention solves the problems of the prior art, and the problem is that R.A. G. B. In a method for manufacturing a color filter in which ink is ejected from an inkjet head in which nozzles for each color are arranged, the ink is ejected in a state where the ink viscosity is lowered. G. B. The film thickness of each color is uniform and non-uniform, and the ink viscosity is lowered, so that the R.V. G. B. It is an object of the present invention to provide a method for manufacturing a color filter that does not cause color mixing or spilling of each color.

  In order to achieve the above object in the present invention, first, in the invention of claim 1, R.D. is placed on a transparent substrate placed on a substrate transfer stage. G. B. In the method of manufacturing a color filter that ejects ink from an inkjet head in which nozzles for each color are arranged, the temperature of the substrate transport stage is adjusted to a range of 25 to 50 ° C., and the ink viscosity at that time is 20 to 10 mPa · s. This is a method for producing a color filter characterized by being in the range described above.

  According to a second aspect of the present invention, after the ink is discharged, the transparent substrate to be carried out is irradiated with ultraviolet rays to cure the discharged ink. It is what.

  Since this invention is the above structure, there exist the following effects.

  That is, according to the first aspect of the present invention, the R.D. is placed on the transparent substrate placed on the substrate transfer stage. G. B. In the manufacturing method of the color filter which discharges ink from the inkjet head in which the nozzles of each color are arranged, the temperature of the substrate transport stage is adjusted to a range of 25 to 50 ° C., and the ink viscosity at that time is 20 to 10 mPa · s. By setting the range, the transparent substrate on which the ink is discharged is also warmed by heat conduction, so that the wettability of the discharged ink is improved, the film pressure is made uniform, and unevenness does not appear. It can be set as a manufacturing method.

According to the second aspect of the invention, after the ink is discharged as described above, the transparent substrate to be carried out is irradiated with ultraviolet rays (UV light) to cure the discharged ink. Even if the ink viscosity is lowered and the ink wettability is improved as described in claim 1 above, when carrying out the transparent substrate on which the ink has been discharged, the vibration, acceleration / deceleration, centrifugal force, etc. R. G. B. It is possible to provide a method for manufacturing a color filter that suppresses the occurrence of color mixing and spilling of ink.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  The present invention relates to a method for producing a color filter by an ink jet method, which basically applies ink onto a transparent substrate such as a glass substrate. G. B. A method of forming a colored portion of the ink by curing the ink itself, and a method of forming a receiving layer made of a resin having ink absorptivity on a transparent substrate, and coloring the receiving layer by applying ink In addition, the method is roughly classified into a method of applying ink to a bank having a black matrix habit ink property on a transparent substrate, and coloring the method, but the present invention is applicable to any method.

  FIG. 1 is an external view showing an outline of an ink-jet color filter manufacturing apparatus used in the color filter manufacturing method of the present invention, wherein 1 is an ink-jet head unit, and 2 is a transparent substrate on which the ink-jet head 1 applies ink. Reference numeral 3 denotes a discharge characteristic maintaining device for maintaining the discharge stability of the ink jet head 1, and reference numeral 4 denotes a main scanning direction moving device for the Y-direction movable part (substrate transport stage 10), which reciprocates during coating. Reference numeral 5 denotes a sub-scanning direction moving device for the X-direction movable part, which is intermittently sent to apply the necessary width to the transparent substrate 2. The inkjet head unit 1 in which the inkjet heads are arranged is moved relative to the transparent substrate 2 in the main scanning direction, and the ink liquid is ejected from the inkjet head onto the transparent substrate 2 for coating. After discharging a predetermined number of times, the discharge characteristics are maintained using the discharge characteristic maintaining device 3.

  Next, a drawing process for producing a color filter by the coating apparatus 20 will be described. In FIG. 1, the ejection stability of the inkjet head mounted on the inkjet head unit 1 is improved by the ejection characteristic maintaining device 3. Next, the inkjet unit 1 is moved to the end of the transparent substrate 2 by the sub-scanning direction moving device 5. Then, it is applied on the transparent substrate a predetermined number of times n (n is a natural number) by the main scanning direction moving device 4. The relationship between the substrate transport stage 10 and the ink ejection timing during the drawing operation is that the substrate transport stage 10 moves in the main scanning direction, and ink is ejected from the nozzles of the inkjet head in synchronization with the position in the main scanning direction. After scanning for a predetermined number of times, the sub-scanning moving device 5 moves to an uncoated portion of the transparent substrate 2 and moves in the main scanning direction to apply again a predetermined number of times.

  The color filter obtained by the above process will be described. For the color filter, a method for curing and coloring the ink itself, a method for forming a receiving layer made of an ink-absorbing resin or the like on the transparent substrate 2, and applying the ink to the receiving layer for coloring, or the transparent substrate 2 There is a method of applying ink to a bank having a black matrix habit ink property and coloring it. An example is shown to FIG. 2, FIG. 3 in the schematic diagram in the process of coating of the color filter 30 obtained with a coating apparatus. Reference numeral 6 denotes a black matrix including ink properties formed on the transparent substrate 2 and serves as a barrier for curing the ink. 7 is an R (red) ink droplet, 8 is a G (green) ink droplet, and 9 is a B (blue) ink droplet. In this example, R.I. G. In order to form the three colored portions B, it is necessary to apply ink droplets corresponding to the openings of the black matrix 6 using three inkjet heads. Even when ink is applied to a receiving layer made of an ink-absorbing resin or the like, it must be ejected to a predetermined location in order to prevent color mixing and misdirection of the ejection position. The applied ink spreads wet within the pattern of the opening of the black matrix 6.

  The flatness of the ink applied to the transparent substrate 2 may cause unevenness. The flatness of the ink is mostly due to the viscosity and wettability which are the characteristics of the ink, but shows the best wettability at about 25 to 50 ° C. Although it depends on the ink composition, for example, the viscosity is about 20 mPa · s near 25 ° C., but when it reaches about 40 ° C., it decreases to about 15 mPa · s, and when it approaches 50 ° C., it decreases to about 10 mPa · s. However, if the temperature is raised too much, the ejection characteristics will change and color mixing and misdelay will occur due to ink mist, so it is important to set the temperature appropriately. The temperature of the substrate transfer stage 10 of the coating apparatus 20 is controlled by a thermostat, and the temperature is adjusted to a temperature suitable for the ink.

  The height BH of the black matrix 6 shown in FIG. 3 is about 2 μm, and the height IH of the ink is about 1.7 μm. In order to prevent color mixing, the black matrix 6 includes a habit ink property. However, if vibration, acceleration / deceleration, centrifugal force, or the like applied during the transfer of the transparent substrate 2 is applied, there is a risk of color mixing beyond the black matrix 6. To prevent this, if the transfer speed is lowered, the tact time is involved. End up.

  Therefore, as in the invention of claim 2, by irradiating the transparent substrate 2 with ultraviolet rays (UV light) when the transparent substrate 2 is carried out by the carry-out robot, the ink is cured to some extent in the subsequent steps. In addition, it can withstand external forces such as an increase in substrate transfer speed and centrifugal force due to rotation.

For example, the ultraviolet light (UV light) is irradiated under an ultra-high pressure mercury lamp having a peak illuminance of 100 mw / cm ² or more through a transparent substrate at a rate of about 0.9 m / min, and an integrated light quantity of 1100 mj / cm ² or more. By doing so, the ink on the transparent substrate can be appropriately cured.

It is an external view showing an example of an ink jet type coating apparatus used in the color filter manufacturing method of the present invention. It is a schematic diagram explaining an example of the color filter under coating by the manufacturing method of the color filter of this invention. It is a sectional side view explaining an example of the color filter obtained with the manufacturing method of the color filter of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inkjet head unit 2 ... Transparent substrate 3 ... Discharge characteristic maintenance device 4 ... Main scanning direction moving device 5 ... Sub scanning direction moving device 6 ... Black matrix 7 ... R ink 8 ... G ink 9 B ink 10 Substrate transport stage 20 Coating device 30 Color filter BH Black matrix height IH Pattern ink height

Claims (2)

  On the transparent substrate placed on the substrate transfer stage, R.P. G. B. In the method of manufacturing a color filter that ejects ink from an inkjet head in which nozzles for each color are arranged, the temperature of the substrate transport stage is adjusted to a range of 25 to 50 ° C., and the ink viscosity at that time is 20 to 10 mPa · s. A method for producing a color filter, characterized in that   2. The method for producing a color filter according to claim 1, wherein after the ink is ejected, ultraviolet rays are irradiated onto the carried-out transparent substrate to cure the ejected ink.

Images