JP2007231075A - Method for producing pigment dispersion and paste for color filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for highly productively producing a paste which can give a color filter having high contrast and high surface smoothness by efficiently and finely dispersing a pigment and thereby preventing the pigment from being re-agglomerated with lapse of time. <P>SOLUTION: The method for producing the pigment dispersion is a method for producing a pigment dispersion by dispersing a pigment in a solvent by using a media stirring disperser having media and a dispersion treating tank, and a pump that pumps a pigment dispersion containing the pigment and the solvent into the media stirring disperser, wherein the dispersion is performed in a manner that the media used have an average particle diameter ϕ of 0.01 to 0.10 (mm), the pump used is a pump having a pulsation factor α of not larger than 10% (wherein the pulsation factor α is represented by formula (1) α(%)=[maximum fluetuation range of flow in a liquid feed pump (cm<SP>3</SP>)]/[average flow of the pump (cm<SP>3</SP>)]×0.5×100), and the residence time rt (min) is 0.5 to 1.0 (min) (wherein the residence time rt is the time during which the dispersion resides in the dispersion treatment tank per pass through the disperser and is represented by formula (2) rt (min)=[void space volume of a pulverizing chamber in the disperser (cm<SP>3</SP>)]/[average flow of the liquid feed pump (cm<SP>3</SP>/min)]). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a pigment dispersion excellent in dispersion stability, and a color filter paste and color filter using the dispersion produced by the production method.

  In general, a liquid crystal display device uses a color filter in which a plurality of different colors (for example, three primary colors of red, green, and blue light) are arranged at pixel portions of a transparent substrate. As a method of regularly arranging pixels of a plurality of colors on a transparent substrate, a photosensitive colored paste is used, or a photolithographic technique combining a non-photosensitive colored paste and a photosensitive positive resist, a printing method, A method using an electrodeposition method, a method using a film transfer method, a method using an ink jet method, and the like are known. Among these, the photolithography technique is generally used in view of the balance between the performance of the color filter such as pattern accuracy, light transmittance and contrast, and the manufacturing yield and cost. As a colored paste used for color filter production by photolithography technology, a colored paste in which a pigment is dispersed in a solution of polyamic acid, which is a precursor of polyimide, or a resin solution containing acrylic resin as a main component is known. These pigment dispersion type colored pastes are generally used in the production of color filters.

  Usually, before forming the colored layer, a light shielding layer called a black matrix is formed. The black matrix is a lattice-shaped light shielding region arranged between the pixels, and is provided to improve the display contrast of the liquid crystal display device. As the black matrix, a metal thin film (thickness of about 0.1 to 0.2 μm) such as Cr, Al, or Ni, or a multilayer chromium film in which a layer such as chromium oxide or chromium oxynitride is provided between Cr and a transparent substrate is used. However, a resin black matrix using a black paste made of a light shielding agent and a resin may be used from the viewpoint of cost and environmental pollution (for example, see Patent Document 1).

  In recent years, there has been a demand for colored pastes and black pastes (hereinafter simply referred to as “pastes”) as the properties required for color filters, such as transmittance, contrast, and surface smoothness, have improved. The characteristics are also high. In particular, in a pigment-dispersed colored paste, it is important to finely disperse the pigment to the order of several tens of nm (see, for example, Patent Documents 2 and 3).

  As a device for finely dispersing a pigment in a solvent, a disperser using a medium (hereinafter referred to as “bead mill”) is known, and examples thereof include a ball mill, an attritor, and a sand mill. The bead mill uses a dispersion medium. The processing material and dispersion medium supplied to the processing tank by a pump are stirred with a stirrer, and the shearing force and shear force applied to the processing material by the movement of the stirrer and the dispersion medium and the particles by the dispersion medium. The processing material is refined by capturing and destroying the body, and as factors affecting the dispersion of the processing material, the diameter of the medium, the filling rate in the processing tank, and the medium collide with the processing material. The rotation speed of the stir bar is dominant.

  In particular, it is known that the diameter of the dispersion medium has a great influence on the grinding efficiency, and that the larger the diameter, the larger the particles and the smaller the smaller the particles, the more efficiently. Further, as a method for efficiently finely dispersing the pigment, a method in which the medium and the object to be dispersed are separated by centrifugal force and a medium having a particle size of 0.3 mmφ or less is used (for example, see Patent Documents 4 and 5), A method is known in which a pigment composition containing a pigment, a pigment derivative, and a liquid medium is supplied and dispersed in a wet disperser equipped with a rotor pin using a medium having a diameter of 0.3 mmφ or less (see, for example, Patent Document 6). It has been. If the average particle size of the media is 0.3 mmφ or more, it is very difficult to disperse the dispersion to the order of several tens of nanometers, and even if reached, it takes a very long dispersion time and is unstable after dispersion. Although the problem of easy re-aggregation occurs, it has been found that dispersion using a minute medium of 0.1 mmφ or less dramatically improves the dispersion efficiency and can stably finely disperse the pigment. However, it is difficult to separate the minute media and the dispersion liquid, and generally the separation is performed by centrifugal force. However, if the dispersion liquid flow rate is high and the viscosity is high, the media cannot be separated. There were problems such as leakage and clogging.

In addition, as a method of increasing the pulverization force by beads and finely dispersing the pigment, a method is known in which the dispersion is pulsated using a pump and fed to the bead mill (Non-Patent Document 1). By using a metering pump such as a gear pump, a tube pump, a hose pump, or a diaphragm pump, which is generally used as a liquid-feeding pump, liquid is fed in a state where pulsation has occurred. However, if the dispersion is introduced into the bead mill in a state where pulsation has occurred, consolidation of the beads occurs on the outlet side of the mill, and as described above, it is difficult to further separate the beads by dispersion using a minute media of 0.1 mmφ or less. There's a problem. On the other hand, a diaphragm pump or a syringe pump is generally used because a coating apparatus does not have pulsation and requires high-precision liquid feeding. (For example, see Patent Documents 7 and 8)
On the other hand, as the pigment is finely dispersed, the pigment tends to aggregate and thicken. As a cause of thickening, dispersion of dispersion state such as over-dispersion and non-dispersion at the time of pigment dispersion can be mentioned, and it is necessary to sharpen the residence time distribution in the disperser. In order to sharpen the distribution, it is known to increase the number of passes for passing the liquid to be dispersed through the disperser. As a method, a tank for supplying the dispersion liquid to the disperser and a tank for receiving the treated dispersion liquid are provided, and a pass dispersion method in which the mill is passed through the mill multiple times while the tanks are replaced with each other, and a plurality of dispersers are connected in series. There are two types of connection and dispersion methods: a circulation dispersion method in which a circulation tank and a disperser are connected and dispersed while circulating. Currently, the circulation and dispersion method is the mainstream because of workability and ease of product changeover. Furthermore, a multi-path dispersion method has been proposed in which the residence time in the disperser per one pass is shortened by increasing the circulation flow rate, and the number of passes is increased to gradually approach the target particle size. (For example, Non-Patent Document 2) However, in dispersion using fine media, it is difficult to circulate and disperse at a large flow rate as described above, so that the particle size distribution of the pigment after dispersion becomes broad, and desired characteristics are obtained. It was difficult to get.
JP-A-5-72524 JP 60-129739 A JP 60-129707 A JP 2000-171931 A JP 2002-105356 A JP 2004-81945 A JP-A-8-229497 JP 2000-140739 "APEMA NO.14", [online], published in 2001, technical information magazine of Imex Corporation, [searched on November 1, 2005], Internet <URL: http://www.aimex-apema.jp/> "Paint Research No. 143" Kansai Paint Co., Ltd. Information Magazine, April 2005, p17

  The present invention was devised in view of the drawbacks of the prior art, and the object of the present invention is that the pigment particle size after dispersion is small in the process of producing a pigment dispersion using a media stirring type disperser, and To provide a method for stably producing a pigment dispersion excellent in storage stability and, in turn, to provide a method capable of producing a color filter paste capable of providing a color filter with high contrast and surface smoothness. It is in.

The object of the present invention is achieved by the following constitution.
That is, a pigment is dispersed in a solvent by using a media agitation type disperser having a medium and a dispersion treatment tank, and a liquid feed pump for feeding a pigment dispersion containing a pigment and a solvent to the media agitation type disperser. A method for producing a pigment dispersion, wherein a medium having an average particle diameter φ of 0.01 to 0.10 (mm) is used, and a pulsation rate α represented by the following formula (1) is 10 as a liquid feed pump. % Or less, and the residence time rt (min) in the dispersion treatment tank when the dispersion represented by the following formula (2) passes through the disperser once is 0.5 to 1.0 ( And a dispersion of the pigment dispersion liquid.

Also, as a pump for feeding the pigment dispersion liquid, it consists of two liquid feeding parts and the phase of each discharge flow rate waveform is shifted by 180 °, or it consists of three liquid feeding parts and the phase of each other discharge flow rate waveform It is preferable to use a pump that feeds liquid by shifting 120 °, and it is more preferable to use a triple diaphragm pump or a dual diaphragm pump.

  And as a medium used at a dispersion | distribution process, it is preferable that a bulk density is 4.0 g / cm <2> or more. Moreover, it is preferable that a pigment is an organic pigment. Further, as the media stirring type disperser, it is preferable to separate the media and the pigment dispersion by centrifugation.

  A method for producing a pigment dispersion having at least a first dispersion step and a second dispersion step, wherein the first dispersion step and the second dispersion step have the method for producing the pigment dispersion. When the average particle size of the media used in the first dispersion step is φ1 (mm) and the average particle size of the media used in the second dispersion step is φ2 (mm), φ1 / φ2 is 4 or more and 40 or less. Preferably there is.

  In the present invention, when a pigment composition mainly composed of a colorant, a resin, and a solvent is introduced into a media agitation type disperser using a liquid feed pump and wet dispersed, the liquid is fed while suppressing the pulsation of the pump, Makes it possible to produce a pigment dispersion excellent in storage stability with high operability by setting the residence time when the material to be treated passes once in the disperser within an appropriate range. Then, by mixing the pigment dispersion obtained by such a production method and the matrix resin, a color filter paste capable of producing a color filter having high transmittance, contrast and surface smoothness is produced.

  Hereinafter, the present invention will be described in more detail.

  That is, the present invention is made possible by dispersing a treatment material using a media stirring type disperser generally called a bead mill. The bead mill is a type in which a processing material flow path is provided in the gap between the stator and rotor, and dispersion processing is performed with media filled in this flow path. Dispersion processing with media filled in a cylindrical processing tank called a vessel There are many types, such as a type that performs the same, and various types of mechanisms, but the basic structure of dispersing the particles by stirring the media is common. Representative examples of the latter are as follows, but are not particularly limited to this form.

  Cylindrical vessel and treatment material inlet at one end, treatment material outlet at the other, and a separator for separating the treatment material and media and taking out only the treatment material at the treatment material outlet To do. Separators are roughly classified into screen separators, gap separators, and centrifugal separators. In recent years, separators that combine these various separators have been developed. The screen separator is a mechanism that has a stitch of a size that does not allow media to pass through and discharges only the processing material out of the processing tank, and the gap separator is a rotor that is attached to the rotating shaft and a stator that is provided in the bearing portion. It is a mechanism that creates a gap and separates the media and processing material.

  FIG. 1 shows an example of a schematic diagram of a disperser having a gap separator. The processing material is introduced into the pulverization processing chamber 7 filled with media from the inlet 4 and pulverized. Thereafter, the processing material is passed through a gap separator 2 provided with a gap equal to or smaller than the average particle diameter of the media, whereby the processing material and the media are separated, and only the processing material is taken out from the outlet 1. As a specific example of a dispersing machine having such a structure, “DYNO-MILL” manufactured by Shinmaru Enterprises Co., Ltd. can be mentioned. In addition, the centrifugal separator separates only the medium having a high specific gravity by centrifugal force by passing a mixture of the medium and the processing material through a centrifugal separation unit composed of a rotor blade or the like. FIG. 2 shows an example of a schematic diagram of a disperser having a centrifugal separator. The treatment material is introduced into the grinding chamber 15 filled with media from the inlet 14 and is ground. Thereafter, the processing material is passed through a centrifugal separator 10 called a sentry separator, and the medium and the processing material are centrifuged by a stirring blade called a rotor separator that rotates at high speed in synchronization with the rotating main shaft 11 and taken out from an outlet 8. . Specific examples of the dispersing machine having such a structure include UAM (“Ultra Apex Mill”) manufactured by Kotobuki Industries Co., Ltd.

  In the present invention, in the bead mill used in the first dispersion step and the second dispersion step, it is desirable to separate the media and the object to be dispersed by different methods. In the present invention, it is necessary to use a medium having a diameter of 0.1 mmφ or less. However, with a screen separator or a gap separator, it is difficult to completely separate the medium due to a problem of processing accuracy, or clogging at the separation part. Therefore, there is a problem that liquid cannot be passed at a sufficient flow rate. Therefore, it is preferable to separate the media by a centrifugal separation method, and it is further preferable to use a centrifugal separation and a screen in combination. FIG. 3 shows an example of a schematic diagram of a disperser having a centrifugal screen separator. Specific examples of the dispersing machine having such a structure include “Star Mill LMZ” and “Star Mill ZRS” manufactured by Ashizawa Finetech Co., Ltd.

  A bearing is fixed to one of the vessels, and a rotating shaft for stirring the inside of the cylindrical treatment tank in the circumferential direction is provided at the bearing in the center of the tank. The joint between the bearing and the rotating shaft has a seal mechanism for preventing the processing material from flowing out through the bearing. The seal mechanism includes a gland packing, a lip seal, a single mechanical seal, a double mechanical seal, and the like, and a highly durable double mechanical seal is preferably used, but is not particularly limited thereto.

  Agitating blades having various shapes are attached to the rotating shaft at regular intervals, and rotate in the circumferential direction to give kinetic energy and shearing force to the media and the processing material. The shape of the stirring blade includes a disk type, a pin type, and a disk type with a pin. The pin type has a structure in which several pins protrude in the circumferential direction from a ring attached to the rotating shaft. There are various thicknesses, shapes, and numbers of pins, but the present invention is not limited to these.

  The disc includes a perforated type, a cam type, a wavy disc type, a disc type with a projection, a disc type with a pin, and the like, but is not particularly limited thereto. As the material of the stirring blade, ceramic, polyurethane, Teflon (registered trademark), polyethylene, or the like is used. Among them, ceramic is preferably used from the viewpoint of wear resistance, chemical resistance, heat resistance, and the like. From the viewpoint of suppressing impact and mildly dispersing, resin stirring blades are preferably used. There are vertical and horizontal types of vessels depending on the installation direction, and some of the horizontal types have a mechanism for changing the angle of the vessel depending on the dispersion state, but the invention is not limited to these. As the material inside the vessel, glass, cemented carbide, stainless steel, iron, ceramic and the like are used, and among them, ceramic is preferably used from the viewpoint of wear resistance, chemical resistance, heat resistance and the like. Zirconia and zirconia reinforced alumina, which have high wear resistance, good thermal conductivity and high cooling effect, are particularly preferably used because the media collide violently and generate high temperature, but are not particularly limited thereto.

  Regarding the entrance and exit portions, the material of the part where the collision of the media can be considered is selected in the same way as the vessel, but is not particularly limited thereto. The outside of the vessel is preferably provided with a jacket for cooling the inside of the vessel, but is not particularly limited thereto. The processing tank of the apparatus configured as described above is filled with a medium at a constant filling rate, and is stirred and dispersed together with the processing material by a stirring blade.

  In order to make the effects of the present invention remarkable, it is very important to select and use an appropriate medium, and the characteristics thereof will be described below.

  In the present invention, the dispersion is performed using media having an average particle diameter of 0.1 mmφ or less, but a more remarkable effect can be obtained by performing dispersion in two steps using media having different particle diameters. Here, the average particle diameter in the present invention refers to the equivalent circle diameter of the media, and is obtained from the average value of the longest diameter and the shortest diameter of 100 media. Specifically, the beads can be magnified and photographed with a stereomicroscope, and the particle size can be obtained from the image. When the average particle diameter of the media used in the first dispersion step is φ1 (mm), φ1 is preferably in the range of 0.1 to 1.0 mm, and in the range of 0.3 to 1.0 mm. Particularly preferred. The first dispersion step aims at pulverizing a coarse material to be dispersed. The larger the average particle diameter of the media, the more effectively coarse particles can be crushed. On the other hand, when the average particle diameter of the media used in the second dispersion step is φ2 (mm), φ2 is preferably 0.01 mm or more and 0.10 mm or less, and preferably 0.01 mm or more and 0.05 mm or less. Particularly preferred. By using a medium having a smaller diameter, it is possible to disperse mildly in a short time without damaging the object to be dispersed.

  When the ratio R of the average particle diameter φ1 of the media used in the first dispersion process and the average particle diameter φ2 of the media used in the second dispersion process is R, the ratio range is R = φ1 / φ2 of 4 or more. It is preferably 40 or less, more preferably 6 or more and 20 or less. When the ratio R is less than 4, productivity improvement by two-stage dispersion is not observed, and when the ratio R exceeds 40, the dispersion to be dispersed after the first process is large, so that the second process is pulverized. The problem that it cannot be performed and remains as coarse particles arises.

As the material of the media, beads such as silica, cemented carbide, steel balls, and ceramics are used. Among them, ceramic is preferably used in terms of wear resistance, chemical resistance, heat resistance, etc., and more preferably wear resistance. Zirconia and zirconia reinforced alumina having high heat conductivity and good cooling effect are used, but not particularly limited thereto. However, the bulk density of the media used in the second dispersion step is preferably 4.0 g / cm ² or more. The higher the media, the greater the impact force and the shorter the dispersion treatment time. The term “bulk density” as used herein refers to the density obtained by considering the pores present in the media material as part of the material, but the term is not uniform depending on the field. Sometimes called density. Further, when separating a medium as small as 0.10 mm or less by a centrifugal separation method, it is preferable that the medium has a higher bulk density because stable separation is possible. The average particle size distribution of the media is σ / mm when the standard deviation of the media particle size distribution used in the second dispersion step is σ (mm) in order to make the effects of the present invention remarkable. φ2 is preferably 0.15 or less, and more preferably σ / φ2 is 0.10 or less. By using media with a sharp particle size distribution when the average particle diameter φ of the media is 0.10 mm or less, the particle size distribution of the dispersion becomes sharper, and a dispersion with good transparency and stability can be obtained. The media filling rate that can be obtained is preferably 50 to 90 (%), more preferably 70 to 87 (%). The filling rate here refers to the ratio of the volume including the space between the media of the closely packed media to the space volume in the pulverization chamber of the disperser. When the media filling rate is 50 (%) or less, the influence of the short path becomes remarkable, the residence time is required for a long time, and the dispersion efficiency is deteriorated. If the residence time is further increased, the part or all of the processing material is excessively dispersed, and part or all of the processing material is re-agglomerated, resulting in a problem that the quality of the entire processing material is lowered. When the filling rate of the media is 90 (%) or more, the load on the rotating shaft at the time of startup increases, causing damage to the device. For this reason, it is impossible to increase the packing efficiency more than necessary to increase the dispersion efficiency.

  The dispersion performed in the present invention employs a circulation dispersion method in which a circulation tank and a dispersion machine are connected to disperse the treatment material while circulating. The pump used when the dispersion is fed to the bead mill and circulated and dispersed will be described below.

  In the present invention, it is very important to select a pump for feeding the dispersion, and it is necessary that no pulsation occurs during the feeding. By suppressing the pulsation of the liquid feeding, the pressure fluctuation at the liquid introduction part into the dispersing machine is reduced, and it becomes possible to prevent the dispersion efficiency from being lowered and the beads from flowing out or clogging due to the dispersion beads being biased. The pulsation rate α (%) of the pump used for feeding the dispersion is preferably 10% or less, and more preferably 5% or less. Here, the calculation of the pulsation rate α (%) is expressed by the following equation (1).

However, the maximum fluctuation width per unit time of the liquid feed pump flow rate and the average flow rate of the liquid feed pump flow rate are measured at a measurement interval of 0.25 seconds at a discharge side pressure of 0.20 (MPa) using a mass flow meter, damping. The measured value at 0.20 seconds.

  In general, a metering pump is preferably used for feeding the dispersion, and a spiral pump, a gear pump, a tube pump, a hose pump, a diaphragm pump, or the like is used. However, in the spiral pump and the gear pump, the impeller, the gear, and the pump chamber are easily worn by the slurry such as the pigment in the dispersion, and the shaft seal (seal) is worn, and the slurry is firmly fixed. . On the other hand, some tube pumps and hose pumps have been devised to suppress the pulsation by setting the rotating gear portion to another stage, but the improvement is insufficient. Another problem other than pulsation is that depending on the solvent used, there is an extract from the pipe, which causes repelling in the coating liquid. Since the diaphragm pump repeats discharge and suction, the discharge state has a sine wave waveform, and since there is no discharge between 180 ° and 360 °, there is a problem that pulsation is large. In order to suppress pulsation, air chambers and accumulators that utilize the compressibility of air are generally used. However, the accumulation of dispersion liquid in the chamber and the aggregation due to sedimentation of slurry such as pigments are problematic. There are many.

  On the other hand, as the non-pulsating pump, there are “Heishin Mono pump”, “Dual diaphragm pump”, “Triple diaphragm pump”, etc. by Hyojin Equipment Co., Ltd.

  The Heisin Mono pump consists of a rotor with a male screw structure and a stator with a female screw structure, and the rotor rotates eccentrically so that the liquid between the rotor and the stator can be sent without pulsation and metering. Although it is excellent in solvent resistance, abrasion at the rotor / stator part becomes a problem depending on the slurry. In a dual diaphragm pump, the pump flow is set to two, and the phase of the discharge flow rate waveform is shifted by 180 °, so that the combined flow becomes a substantially constant flow. By making the waveform trapezoidal, liquid feeding without pulsation is possible. Similarly, a triple diaphragm pump that uses three pump heads and operates by changing the phase of the discharge flow rate waveform by 120 ° is also preferable. Further, in the diaphragm pump, it is easy to change the wetted part to a material having high solvent resistance, and there is no problem of deterioration due to wear. There is a double tube pump (WM-520DiN / L, manufactured by Iwaki Co., Ltd.) as a pump that suppresses pulsation based on the same idea, but it is not preferable because extraction from the piping is concerned as described above.

  In order to suppress thickening due to fine dispersion of the pigment, it is necessary to sharpen the residence time distribution of the dispersion in the disperser. To sharpen the dispersion in the disperser, increase the circulation flow rate to shorten the residence time in the disperser per pass and increase the number of passes to gradually approach the target particle size. A multipath distributed system is preferable. That is, it is necessary to shorten the residence time rt (minute) in the disperser per pass. The residence time rt (min) in the grinding chamber when the dispersion passes once through the disperser is expressed by the following equation.

Here, L (cm ³ / min) is the average flow rate of the pump when the dispersion is fed to the disperser, and V (cm ³ ) is the crushing chamber void volume of the disperser. This is the volume obtained by removing the volume of filled beads and disks from the volume of the grinding chamber.
On the other hand, the processing time in the circulation dispersion can compare the processing efficiency regardless of the amount of the processing tank and the processing material and the circulation flow rate by defining the residence time DT (min). The calculation of the residence time is expressed by the following formula when the volume of the processing material = v (cm ³ ), the pulverization chamber volume of the disperser = V (cm ³ ), and the operation time = T (min).

Accordingly, the number of passes in the cyclic dispersion is DT / rt = L / v × T.

  The flow rate of the pump is preferably controlled by feedback using a flow meter. Even with a non-pulsating metering pump, there is no flow rate variation, and by controlling the flow rate with feedback from the flow meter, it is possible to make every effort to avoid the effects of pressure variation at the disperser introduction section.

  The residence time rt (minute) per one pass is preferably 1 minute or less, and more preferably 0.5 minutes or more and 1 minute or less. In the range where the flow rate is small, the residence time distribution becomes broad as described above, and the dispersion stability deteriorates because the pigment is undispersed and overdispersed. On the other hand, if the flow rate is too high, beads are unevenly distributed in the disperser and the dispersibility is deteriorated.

  Further, the range of the residence time DT (min) is preferably 2 minutes or more and 60 minutes or less, and more preferably 2 minutes or more and 30 minutes or less.

  A factor that greatly contributes to the dispersion of the treated material is the rotational speed of a rotor such as a stirring blade. The rotational speed in the present invention is preferably 5 m / s to 15 m / s, and more preferably 7 m / s to 14 m / s. The following is preferred. When the rotational speed of the rotor is 5 m / s or less, it is not possible to sufficiently pulverize and disperse the object to be dispersed, or in a disperser using a centrifugal separator, media bias or media due to a decrease in centrifugal separation ability Problems such as spillage. Further, when the rotor rotational speed is 15 m / s or more, there is a problem that excessive energy is applied to the object to be dispersed and the dispersion tends to be excessively dispersed.

  In the present invention, the pigment dispersion supplied to the wet disperser is mainly composed of a pigment and a solvent, and optionally mixed with additives such as a resin, a pigment derivative, a dispersant, and a surfactant. Use things.

  In the second dispersion step of the present invention, the viscosity of the pigment dispersion is important for stable dispersion. If the viscosity of the pigment dispersion is too high, the minute media cannot be sufficiently centrifuged, causing the media to be biased, resulting in problems such as blockage at the separator and outflow of the media. Accordingly, the viscosity of the pigment dispersion used in the second dispersion step of the present invention is preferably less than 50 mPa · s at a shear rate of 38 / sec at 25 ° C., and more preferably at a shear rate of 38 at 25 ° C. The viscosity at / second is preferably less than 30 mPa · s.

  As the pigment used in the pigment dispersion, either an organic pigment or an inorganic pigment can be preferably used, but it is desirable to use an organic pigment in terms of chromaticity characteristics. Of the pigments, those having high transparency and excellent light resistance, heat resistance, and chemical resistance are particularly preferable.

The solvent used in the pigment dispersion is not particularly limited, and water and an organic solvent can be used in accordance with the dispersion stability of the pigment to be dispersed and the solubility of the resin to be added.
The resin used for the pigment dispersion is not particularly limited, and any photosensitive or non-photosensitive material can be used.
The dispersant added to the pigment dispersion is not particularly limited, and various types can be used alone or in combination.

  The color filter paste used in the present invention may be either a colored paste or a black paste, and is obtained by adding a resin, a solvent, or the like to the pigment dispersion and diluting it. Furthermore, various additives such as an ultraviolet absorber, a dispersant, and a surfactant may be added. For the photosensitive paste, a photopolymerization initiator, a polymerizable monomer, and the like are further added.

  The color filter produced with the paste obtained by the production method of the present invention will be described. A color filter consists of a plurality of colored layers composed of three primary colors arranged on a transparent substrate, and the color filter is composed of a large number of picture elements, each pixel being covered by each colored layer consisting of the three primary colors. ing. The transparent substrate used for the color filter is not particularly limited, and includes inorganic glass such as quartz glass, borosilicate glass, aluminosilicate glass, soda lime glass coated with silica on the surface, organic plastic film or sheet. Etc. are preferably used.

  The three primary colors referred to here are red (R), green (G), and blue (B) when the color display is performed by the additive color mixing method, and the color display is performed by the subtractive color mixing method. Three primary colors of cyan (C), magenta (M), and yellow (Y) are selected. In general, an element including these three primary colors can be used as a unit as a color display picture element.

  As a method of forming the colored layer, patterning is performed after applying or drying the colored paste directly or on a substrate on which a black matrix has been formed in advance.

  As a method for applying the paste, a spin coating method, a roll coating method, a bar coating method, a die coating method, or the like can be used, but it is not particularly limited to these methods. After a paste is applied to the substrate to form a wet film, heat drying (semi-cure) is performed using an oven or a hot plate. Semi-cure conditions vary depending on the resin, solvent, and paste coating amount used, but it is usually preferable to heat at 60 to 200 ° C. for 1 to 60 minutes.

  When the resin paste is a non-photosensitive resin, the paste coating obtained in this way is used after a positive photoresist coating is formed thereon, and when the resin is a photosensitive resin. Is exposed or developed as it is or after an oxygen blocking film is formed. If necessary, the positive type photoresist or the oxygen blocking film is removed, and then heat-dried (cured) again. The curing conditions vary depending on the resin, but when a polyimide resin is obtained from a polyimide precursor, it is generally heated at 200 to 300 ° C. for 1 to 60 minutes.

  The post-cure film thickness of the colored layer to be applied is determined by the required color characteristics and the colorant / matrix resin ratio of the colored paste. Usually, the colorant / matrix resin ratio is in the range of 5/95 to 70/30 by weight, but preferably in the range of 10/90 to 60/40. When the colorant ratio is less than 5, the film thickness that needs to be applied in order to obtain sufficient color purity becomes too thick, so that the level difference between the pixels becomes large, causing problems such as poor alignment of the liquid crystal. If the colorant ratio exceeds 70, the matrix resin is insufficient, and there are problems such as poor pixel adhesion. When the colorant / matrix resin ratio is set within this preferred range, the post-cure film thickness that needs to be applied to obtain the desired color characteristics is 0.2 to 4.0 μm. If it is thinner than 0.2 μm, sufficient color purity cannot be obtained, and if it is thicker than 4.0 μm, the light transmittance is insufficient.

  The black matrix is usually provided with openings of (20 to 200) μm × (20 to 300) μm, and a plurality of colored layers of three primary colors are arranged so as to cover at least the openings. The pattern arrangement of the three primary colors can be suitably used according to the purpose such as mosaic type, triangle type, stripe type, and four pixel arrangement type.

  The light shielding property of the black matrix is expressed by an OD value (common logarithm of the reciprocal of the transmittance), and is preferably 2.5 or more, more preferably 3 in order to improve the display quality of the liquid crystal display device. 0.0 or more. The upper limit of the OD value is determined by the film thickness of the black matrix.

  The film thickness of the black matrix is preferably 0.5 to 1.5 μm, more preferably 0.8 to 1.2 μm. When the film thickness is thinner than 0.5 μm, the light shielding property is insufficient, which is not preferable. On the other hand, when the film thickness is thicker than 1.5 μm, the light-shielding property can be secured, but the flatness of the color filter tends to be sacrificed and a step is likely to occur. If a surface level difference occurs, even if a transparent conductive film or liquid crystal alignment film is formed on the color filter, the level difference is hardly reduced, and the alignment process by rubbing the liquid crystal alignment film becomes non-uniform, resulting in a display quality of the liquid crystal display device. Decreases. In order to reduce the surface level difference, it is effective to provide a transparent protective film on the colored layer.

  Further, the reflectance of the black matrix is a reflection-corrected reflection in the visible region of 400 to 700 nm in order to reduce the influence of the reflected light at the boundary surface between the pixel and the light shielding region and improve the display quality of the liquid crystal display device. The rate (Y value) is preferably 2% or less, more preferably 1% or less. When the reflectance is 2% or more, the display contrast is lowered due to the surface reflected light.

Next, a liquid crystal display device produced using the present invention will be described. The color filter is formed by facing the color filter and the transparent electrode substrate. If necessary, the color filter may be provided with a transparent protective film on the colored layer. A transparent electrode such as an ITO film is formed on the color filter.

  Hereinafter, although the manufacturing method of this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to a following example.

The bead mill, liquid feed pump, and dispersion beads used in Examples and Comparative Examples are as follows.
・ Media stirring type disperser (1) “Dynomill KDL” Co., Ltd .: manufactured by Shinmaru Enterprises, Separator: Gap system (2) “Ultra Apex Mill” (UAM): manufactured by Kotobuki Kogyo Co., Ltd., separator: Centrifugation system・ Liquid feeding pump (1) Sanitary non-pulsating metering pump SPSYWA2: Takumina Co., Ltd., double diaphragm pump (2) Sanitary metering pump SARXMW1: Takumina Co., Ltd., monolithic diaphragm pump, dispersion beads (1) Zirconia beads 0.30 mmφ: manufactured by Toray Industries, Inc., bulk density = 6.03 g / cm ³
(2) Zirconia beads 0.10 mmφ: manufactured by Toray Industries, Inc., bulk density = 6.02 g / cm ³
(3) Zirconia beads 0.05 mmφ: manufactured by Nikkato Co., Ltd., bulk density = 6.06 g / cm ³
(4) Silica beads 0.10 mmφ: manufactured by Induction Thermal Engineering Co., Ltd., bulk density = 3.20 g / cm ³
The average flow rate and pulsation rate of the liquid feed pump are measured by the following method.

A. Flow rate measurement method The flow rate is measured by connecting a Coriolis mass flow meter ("Promass 83M", manufactured by Endless Hauser Japan Co., Ltd.) to the liquid feed part of the liquid feed pump, and the measurement interval when the discharge side pressure is 0.20 MPa. Was 0.25 seconds, current output damping was 0.20 seconds, the average flow rate of the feed pump and the maximum fluctuation range of the feed pump flow rate were measured for 2 minutes, and the phase of the discharge flow rate waveform and the pulsation rate were calculated.
In addition, the polyamic acid A-1 and the pigment dispersions G-0, G-1, G-2, and G-3 used in the examples are manufactured by the following method.
B. Production method of polyamic acid A-1 4,4′-diaminophenyl ether; 330.6 g (0.75 mol), 3,3′-diaminodiphenyl sulfone; 49.6 g (0.20 mol), bis (3-aminopropyl) Tetramethyldisiloxane; 12.4 g (0.005 mol) was charged with 2730 g of γ-butyrolactone, and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride; 161.0 g (0.49 mol) and pyromerit 106.8 g (0.49 mol) of acid dianhydride was added and reacted at 60 ° C. for 5 hours. 1.96 g (0.02 mol) of maleic anhydride was added and further reacted at 60 ° C. for 1 hour to obtain a polyamic acid (referred to as A-1) solution.

C. Preparation of pigment dispersions G-0, G-1 and G-2 Green pigment (Pigment Green 36); 3.3 wt%, yellow pigment (Pigment Yellow 138); 3.0 wt%, polyamic acid A-1; 4.7 wt%, γ-butyrolactone; 89.0 wt% was charged into a tank, and stirred for 1 hour with a homomixer (made by Tokushu Kika) to obtain a pigment dispersion G-0. The viscosity of this pigment dispersion G-0 was measured using an RC500 viscometer (manufactured by Toki Sangyo) equipped with a cone plate having a tip angle of 1 degree 34 seconds. The viscosity at / second was 2.85 mPa · s.

  Subsequently, the pigment dispersion G-0 was supplied to a bead mill (Dynomill) equipped with a gap separator filled with zirconia beads having a particle diameter of φ1; Dispersion was carried out so that (1) was 3 minutes to obtain a pigment dispersion G-1. The viscosity of this pigment dispersion G-1 was measured using an RC500 viscometer (manufactured by Toki Sangyo) equipped with a cone plate having a tip angle of 1 degree 34 seconds. The viscosity at / second was 2.90 mPa · s.

  Similarly, the pigment dispersion G-0 was supplied to a bead mill (Dynomill) equipped with a gap separator filled with zirconia beads having a particle diameter of φ1; 3.00 mm at a filling rate of 85%, and the residence time was 11 m / s. Dispersion was carried out so that DT (1) was 3 minutes to obtain a pigment dispersion G-2. The viscosity of this pigment dispersion G-1 was measured using an RC500 viscometer (manufactured by Toki Sangyo) equipped with a cone plate having a tip angle of 1 degree 34 seconds. The viscosity at 3 sec / sec was 3.10 mPa · s.

Example 1
Particle size φ2; 0.05 mm zirconia beads were packed in a bead mill (UAM-2, crushing chamber volume = 1700 (cm ³ )) at a filling rate of 75% (crushing chamber gap volume = 920 ( cm ³ )), and the pigment dispersion G-0 is supplied using a double diaphragm pump at a pulsation rate of 2.4% and a liquid feed pump average flow rate of 1500 (cm ³ / min) (rt = 0.61 ( Min)), and the dispersion was performed so that the residence time DT (2) was 25 minutes at a rotational speed of 10 m / s. This dispersion was filtered through a polyfluorone filter having a pore size of 2 μm (PF020 manufactured by ADVANTEC), and then diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate and then heat-treated to obtain a polyimide colored film (P1-0). Similarly, a polyimide colored film (P1-1) was obtained using a dispersion stored frozen for 2 weeks.

Example 2
Dispersion was carried out in the same manner as in Example 1 except that only the dispersion medium was changed, and a bead mill (UAM-2, pulverization chamber volume = 75% particle diameter φ2; filling rate of 0.10 mm zirconia beads; 75%) 1700 (cm ³ )) (pulverization chamber gap volume = 920 (cm ³ )), and the pigment dispersion G-0 is pulsated by using a double diaphragm pump; 2.4%, average pump flow rate Dispersion was carried out at a feed rate of 1500 (cm ³ / min) (rt = 0.61 (min)) and a dwell time DT (2) of 25 min at a rotational speed of 10 m / s. This dispersion was filtered through a polyfluorone filter having a pore size of 2 μm (PF020 manufactured by ADVANTEC), and then diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate, and then heat-treated to obtain a polyimide colored film (P2-0). Similarly, a polyimide colored film (P2-1) was obtained using a dispersion stored frozen for 2 weeks.

Example 3
Dispersion was carried out in the same manner as in Example 1 except that only the dispersion medium was changed, and a bead mill (UAM-2, crushing chamber volume = 75% particle diameter φ2; filling rate of alumina beads of 0.10 mm; 75%) 1700 (cm ³ )) (pulverization chamber gap volume = 920 (cm ³ )), and the pigment dispersion G-0 is pulsated by using a double diaphragm pump; 2.4%, average pump flow rate Dispersion was carried out at a feed rate of 1500 (cm ³ / min) (rt = 0.61 (min)) and a dwell time DT (2) of 25 min at a rotational speed of 10 m / s. This dispersion was filtered through a polyfluorone filter having a pore size of 2 μm (PF020 manufactured by ADVANTEC), and then diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate and then heat-treated to obtain a polyimide colored film (P3-0). Similarly, a polyimide colored film (P3-1) was obtained using a dispersion stored frozen for 2 weeks.

Example 4
Particle size φ2: Filled with zirconia beads of 0.05 mm in a bead mill (UAM-2, crushing chamber volume = 1700 (cm ³ )) with a filling rate of 75% (crushing chamber gap volume = 920 ( cm ³ )), and the pigment dispersion G-1 is supplied using a double diaphragm pump at a pulsation rate of 2.4% and a feed pump average flow rate 1500 (cm ³ / min) (rt = 0.61 ( Min)), and the dispersion was performed so that the residence time DT (2) was 25 minutes at a rotational speed of 10 m / s. This dispersion was diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate, and then heat-treated to obtain a polyimide colored film (P4-0). Similarly, a polyimide colored film (P4-1) was obtained using a dispersion stored frozen for 2 weeks.

Example 5
Dispersion was carried out in the same manner as in Example 4 except that only the liquid feed pump was changed, and the pulsation rate of the pigment dispersion G-1 was 2.7% using a double diaphragm pump; the liquid feed pump average flow rate 1000 (cm ³⁾ / Min) (rt = 0.92 (min)), and dispersion was performed such that the residence time DT (2) was 25 minutes at a rotational speed of 10 m / s. This dispersion was diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate and then heat-treated to obtain a polyimide colored film (P5-0). Similarly, a polyimide colored film (P5-1) was obtained using a dispersion stored frozen for 2 weeks.

Example 6
Particle size φ2: Filled with zirconia beads of 0.05 mm in a bead mill (UAM-2, crushing chamber volume = 1700 (cm ³ )) at a filling rate of 60% (crushing chamber gap volume = 1074 ( cm ³ )), and the pigment dispersion G-1 is supplied using a double diaphragm pump at a pulsation rate of 8.5% and a feed pump average flow rate of 2000 (cm ³ / min) (rt = 0.54 ( Min)), and the dispersion was performed so that the residence time DT (2) was 25 minutes at a rotational speed of 10 m / s. This dispersion was diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate and then heat-treated to obtain a polyimide colored film (P6-0). Similarly, a polyimide colored film (P6-1) was obtained using a dispersion stored frozen for 2 weeks.

Example 7
Dispersion was carried out in the same manner as in Example 4 except that only the pigment dispersion was changed, and the pulsation rate of the pigment dispersion G-2 using a double diaphragm pump; 2.4%; average flow rate of the feed pump 1500 (cm ³ / Min) (rt = 0.61 (min)), and dispersion was performed such that the residence time DT (2) was 25 minutes at a rotational speed of 10 m / s. This dispersion was filtered through a polyfluorone filter having a pore size of 2 μm (PF020 manufactured by ADVANTEC), and then diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate and then heat-treated to obtain a polyimide colored film (P7-0). Similarly, a polyimide colored film (P7-1) was obtained using a dispersion stored frozen for 2 weeks.

Comparative Example 1
Dispersion was carried out in the same manner as in Example 4 except that only the feed pump was changed, and the pulsation rate of the pigment dispersion G-1 using a single diaphragm pump; 28.0%; feed pump average flow rate 1500 (cm ³ / Min) (rt = 0.61 (min)) and dispersion was carried out at a rotational speed of 10 m / s, the operation was stopped because the beads flowed out.

Comparative Example 2
Dispersion was carried out in the same manner as in Example 4 except that only the feed pump was changed, and the pulsation rate of the pigment dispersion G-1 was 26.7% using a single diaphragm pump; the feed pump average flow rate 1000 (cm ³⁾ / Min) (rt = 0.92 (min)), and dispersion was performed such that the residence time DT (2) was 25 minutes at a rotational speed of 10 m / s. This dispersion was diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate and then heat-treated to obtain a polyimide colored film (P8-0). Similarly, a polyimide colored film (P8-1) was obtained using a dispersion stored frozen for 2 weeks.

Comparative Example 3
By changing only the liquid sending pump was dispersed in the same manner as in Example 4, the pulsation rate of the pigment dispersion G-1 using a twin Diaphragm pump; 8.5% & feeding pump average flow 2000 (cm ³ / Min) (rt = 0.46 (min)), and dispersion was performed so that the residence time DT (2) was 25 minutes at a rotational speed of 10 m / s. This dispersion was diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate and then heat-treated to obtain a polyimide colored film (P9-0). Similarly, a polyimide colored film (P9-1) was obtained using a dispersion stored frozen for 2 weeks.

Comparative Example 4
Dispersion was carried out in the same manner as in Example 4 except that only the liquid feeding pump was changed, and the pulsation rate of the pigment dispersion G-1 using a double diaphragm pump; 2.0%, liquid feeding pump average flow rate 500 (cm ³⁾ / Min) (rt = 1.83 (min)), and dispersion was performed so that the residence time DT (2) was 25 minutes at a rotational speed of 10 m / s. This dispersion was diluted with a polyimide precursor A-1 diluent to prepare a green colored paste. The obtained colored paste was spin-coated on an alkali-free glass substrate and then heat-treated to obtain a polyimide colored film (P10-0). Similarly, a polyimide colored film (P10-1) was obtained using a dispersion stored frozen for 2 weeks.

  The liquid feeding conditions in Examples 1 to 7 and Comparative Examples 1 to 4 are shown in Table 1.

  About the obtained dispersion liquid, the viscosity immediately after dispersion | distribution and the viscosity after 2 weeks time-lapse | temporarily under frozen storage were measured. The evaluation results are shown in Table 2 together with the presence or absence of bead outflow during dispersion.

  Further, the obtained colored coating film was evaluated for contrast and surface roughness, and the evaluation results are shown in Table 3. The values shown in Table 3 are obtained by the following method, and the value is y = 0.600 in the C light source of the colored film.

(1) Viscosity Using a RC500 viscometer (manufactured by Toki Sangyo) equipped with a cone plate having a tip angle of 1 degree 34 seconds, the viscosity at 25 ° C. and a shear rate of 38 / sec was measured.

(2) Chromaticity Using a microspectrophotometer MCPD-2000 (manufactured by Otsuka Electronics), transmittance Y, x value, and y value with a C light source were measured.

(3) Contrast A substrate sample was sandwiched between polarizing plates, and a contrast was measured from the ratio of the parallel Nicol luminance and the crossed Nicol luminance using a color luminance meter BM-5A (manufactured by Topcon).

(4) Surface roughness Surface roughness was measured using a surface shape measuring device Surfcom 1500A (Tokyo Seimitsu).

  It can be seen that in the operation in the examples, there is no outflow of beads and the obtained dispersion is excellent in storage stability. In addition, the colored coating film obtained in the examples also showed good contrast and surface roughness even when the dispersion was aged as compared with the coating film obtained in the comparative example.

It is the schematic which shows an example of the disperser which has a gap separator used for the manufacturing method of the pigment dispersion liquid of this invention. It is the schematic which shows an example of the disperser which has the centrifugal separator used for the manufacturing method of the pigment dispersion liquid of this invention. It is the schematic which shows an example of the disperser which has the centrifugal separation used for the manufacturing method of the pigment dispersion liquid of this invention, and a screen separator.

Explanation of symbols

1, 8, 19 Treatment material outlet 2 Gap separators 3, 12, 20 Stirring blades 4, 14 Treatment material inlets 5, 9, 16 Mechanical seals 6, 11, 17 Rotating spindles 7, 15, 21 Crushing treatment chamber 10 Sentry Separator 13 Backflow valve 18 Centrifugal screen separator

Claims (9)

Pigment dispersion for dispersing a pigment in a solvent by using a media agitation type disperser having a media and a dispersion treatment tank, and a liquid feed pump for feeding a pigment dispersion containing a pigment and a solvent to the media agitation type disperser A liquid production method using a medium having an average particle diameter φ of 0.01 to 0.10 (mm), and a pulsation rate α represented by the following formula (1) as a liquid feed pump is 10% or less. And the residence time rt (min) in the dispersion treatment tank when the dispersion represented by the following formula (2) passes through the disperser once is 0.5 to 1.0 (min) A method for producing a pigment dispersion, wherein the dispersion is performed as follows.

If the liquid feed pump has two or three liquid feed parts, and there are two liquid feed parts, a liquid feed pump that feeds liquid by shifting the phase of each discharge flow rate waveform at the liquid feed part by 180 ° The pigment according to claim 1, wherein a liquid feed pump is used, wherein when there are three liquid feed units, the phase of each discharge flow rate waveform at the liquid feed unit is shifted by 120 ° to feed the liquid. A method for producing a dispersion. 3. The method for producing a pigment dispersion according to claim 2, wherein the liquid feeding pump is a double diaphragm pump or a triple diaphragm pump. The method for producing a pigment dispersion according to claim 1, wherein the bulk density of the media is 4.0 g / cm ² or more. The method for producing a pigment dispersion according to any one of claims 1 to 4, wherein the pigment is an organic pigment. The method for producing a pigment dispersion according to any one of claims 1 to 5, wherein the media stirring type disperser separates the media and the pigment dispersion by centrifugation. The method for producing a pigment dispersion according to claim 1 is a method for producing a pigment dispersion having at least a first dispersion step and a second dispersion step, wherein the first dispersion step and the second dispersion step. The dispersion step of the method has the method for producing a pigment dispersion according to any one of claims 1 to 6, wherein the average particle diameter of the media used in the first dispersion step is φ1 (mm), and the second dispersion step. A method for producing a pigment dispersion, wherein φ1 / φ2 is 4 or more and 40 or less, when the average particle size of the media used in 1 is φ2 (mm). A paste for a color filter, comprising a pigment dispersion obtained by the method for producing a pigment dispersion according to any one of claims 1 to 7 and a resin. The color filter paste according to claim 8 is used for the colored layer or the light-shielding layer in a color filter having a pixel composed of a colored layer and a light-shielding layer provided in a desired pattern for each color with an arbitrary number of colors. A color filter characterized by

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