JP2001252587A - Powder classifying method and classified particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precise classifying method using an electroformed screen classifying a powder without clogging the screen and the agglomeration of particles and also provide particles classified by the method and also its use. SOLUTION: In the classifying method, a dispersed body formed of a raw material powder dispersed into a liquid medium is passed through a classifying device with the electroformed screen to classify the raw material powder into particles of desired particle size range, and (1) the density of the raw material powder is set at 0.01-50 wt.%, (2) the density of the particles in the dispersed body in the classifying device is set at 0.01-50 wt.%, (3) as the liquid medium, the medium of viscosity of 50 cP or less is used, (4) the temperature of the liquid medium and/or the dispersed body during the classification is set at 0-100 deg.C, (5) at least a part of the dispersed body in the classifying device is made to flow and (6) the liquid amount in the classifying device during the classification is kept to a given level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for classifying powder,
Classified particles and their use. More specifically, the present invention relates to a classification method for precisely classifying powders having various particle diameters into particles having a desired particle size range, particles classified thereby, and uses thereof.

[0002]

2. Description of the Related Art Powders handled in various fields have different required average particle diameters and distributions of particle diameters depending on the kind, purpose and application. In particular, in the case of powders used for spacers for liquid crystal display elements, conductive particles for anisotropic conductive films, fillers for liquid chromatography, lubricants for films or toners for developing electrostatic images, the particle size distribution is narrowed. There is a need to. Above all, the powder used as the spacer for the liquid crystal display element needs to have a particularly narrow particle size distribution, and the raw material powders produced by various methods are precisely adjusted to have the desired particle size and particle size distribution. It needs to be used separately.

Generally, a so-called classifier is used to narrow the particle size distribution of the powder. As a classifier, a cyclone, a sedimentation tower, a sieve, or the like is used in a dry type or a wet type. However, in cyclones that perform classification using the balance between centrifugal force and gravity in swirling flow, there are particles that short-pass the classification zone due to their structure, so there is a limit to narrowing the particle size distribution. In addition, there is a problem that, although in a small amount, particles that largely deviate from the particle size distribution remain. Further, in a sedimentation tower that classifies using a difference in sedimentation velocity in a medium, the sedimentation velocity changes due to factors such as temperature and vibration, so it is difficult to increase the classification accuracy, and the particle diameter is small. For those, the sedimentation speed is extremely low, so that a large amount of time is required for classification. An apparatus in which a settling tower is improved to supply a medium from below and overflow from above has also been proposed, but has the same problem as the above-mentioned settling tower.

[0004] On the other hand, a sieve performs classification based on whether or not it passes through a certain opening. For those with an opening of 10 μm or more, a fine wire knitting sieve is used. For those with a mesh size of 10 μm or less, a fine hole made by etching a metal foil or the like, or a rectangular hole by plating, called an electric sieve, is used. The screens are used, and the screens are very well aligned as compared with those obtained by knitting fine wires, and can improve the classification accuracy. In particular, compared to the electric sieve with holes drilled by etching, holes smaller than the thickness can be processed, the cross-sectional shape is beautiful without side edges,
It is an excellent sieve.

However, when the sieve is used as a classifier, the sieve may be clogged during operation,
A phenomenon is often observed in which the agglomeration of the particles significantly reduces the sieving speed. This phenomenon occurs more remarkably and in a shorter time as the sieve opening becomes smaller,
Each time, operations such as washing of a sieve and redispersion of particles are required.

[0006]

Accordingly, an object of the present invention is to provide a precise classification method using an electric sieve.
An object of the present invention is to provide a method for classifying powder without causing clogging of a sieve or aggregation of particles. Another object of the present invention is to provide particles classified thereby and uses thereof.

[0007]

In order to solve the above-mentioned problems, the present invention employs the following constitution. That is, in the classification method according to the first to sixth aspects of the present invention, the raw material powder is desirably prepared by passing a dispersion obtained by dispersing the raw material powder in a liquid medium through a classification device equipped with an electric sieve. The method according to the first aspect of the present invention, wherein the concentration of the raw material powder in the dispersion is 0.01%.
The classification method according to the second aspect of the present invention is characterized in that the concentration of particles in the dispersion in the classification device is 0.01 to 50% by weight. A classification method according to a third aspect of the present invention is characterized in that a liquid medium having a viscosity of 50 cP or less is used as the liquid medium. The classification method according to the fifth invention of the present invention is characterized in that the temperature is 0 to 100 ° C., wherein at least a part of the dispersion in the classification device is caused to flow, and the classification method according to the sixth invention of the present invention. Is characterized in that the amount of liquid in the classification device during classification is kept constant.

[0008] The classified particles of the present invention are particles classified by the powder classification method according to any one of the first to sixth inventions of the present invention. The spacer for a liquid crystal display element of the present invention has, as a main body, particles classified by the powder classification method according to any one of the first to sixth aspects of the present invention.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, particles are classified using a classifier equipped with an electric sieve. What is Densei Sieve?
A screen having a rectangular hole was produced by plating. As a method of manufacturing an electric sieve, a conductive film is formed on a glass plate corroded in a cross line shape with high precision by physical plating such as vacuum evaporation, sputtering, or chemical plating such as electrolytic plating or electroless plating. After that, there is a method of removing the plating layer other than the groove in the corroded portion, forming a mesh on the plating layer by a method such as electrolytic plating, and peeling the mesh from the glass plate. The mesh produced in this manner may be further subjected to electrolytic plating, if necessary, after peeling from the glass base plate. Also, as another manufacturing method, a vacuum plating, physical plating such as sputtering, or electrolytic plating, chemical plating such as electroless plating on a glass flat plate, a conductive film is formed, and after applying a resist on the film, There is also a method of forming a pattern having a predetermined shape, removing portions other than the pattern by etching, exfoliating the glass substrate, and then performing electrolytic plating.

The materials of the electric sieve include gold, platinum,
Silver, copper, iron, aluminum, nickel and various alloys based on these are used.
A material containing nickel as a main component is particularly preferably used because of its corrosion resistance and ease of plating. The electric sieve is not only easy to adjust the hole diameter and the number of holes per unit, but also has a very good hole diameter distribution, so it can be classified very accurately when used as a sieve. Becomes Since the electric sieve is very thin, it may be easily damaged or broken, and metal-based impurities may be mixed into the classified particles. In particular, when the classified particles are used for an electronic material such as a spacer for a liquid crystal display element, the incorporation of metallic impurities is a serious problem because it causes a decrease in reliability.
Therefore, it is preferable to increase the strength by providing a grid-like or ring-like support on one or both sides of the electric sieve.

Regarding the attachment of the electric sieve to the classifying device, particularly when ultrasonic vibration is applied, the electric sieve is rubbed with the classifying device and the electric sieve is broken, so that metal-based impurities are added to the classified particles. Since there is a possibility of being mixed, it is preferable to attach via a member made of an elastomer. In the present invention, classification is performed by a wet method by passing a dispersion obtained by dispersing the raw material powder in a liquid medium through a classification device equipped with an electric sieve. Compared to the dry method using inert gas or air as the medium, the wet method has higher ultrasonic irradiation efficiency and dispersion stability, and less particles adhere to the electric sieve. . In particular, particles having a small particle size of about 10 μm or less used for a spacer for a liquid crystal display element or the like have a strong cohesive force, so that dispersion may be insufficient by a dry method.

A third invention of the present invention is characterized in that a liquid medium having a viscosity of 50 cP or less is used. Preferably it is 20 cP or less. As the liquid medium in which the raw material powder is dispersed, the material of the electric sieve to be used, the opening diameter, the number of lines, and the properties of the powder or the particle size distribution can be appropriately selected, but in order to increase the classification speed. Is preferably as low as possible. In particular, in order to classify particles having a small particle size of about 10 μm or less used for a spacer for a liquid crystal display element or the like, it is necessary to use an electric sieve having a small opening diameter and a small opening area. In this case, since the liquid medium needs to be inert to the raw material powder, considering these factors, the liquid medium is water; alcohols such as methanol, ethanol, isopropanol, and butanol; hexane, octane, etc. And aromatic hydrocarbons such as benzene, toluene and xylene. Of these, methanol and n-hexane are preferably used.
Of course, various dispersants may be added to the liquid medium in order to improve the dispersibility of the particles. Further, a solution of various polymers (such as polyimide) may be used as the liquid medium.

In the first invention of the present invention, the concentration of the raw material powder in the dispersion is specified, and in the second invention of the present invention, the concentration of the particles in the dispersion in the classification device is specified. It is important that these are all 0.01 to 50% by weight, preferably 0.5 to 30% by weight. The concentration is 0.
If it is less than 01 wt%, a large amount of time is required for classification. On the other hand, if it exceeds 50 wt%, it becomes difficult to disperse the powder in the medium, and it is easy to clog the opening of the electric sieve, and the classification efficiency is reduced and the classification accuracy is reduced. In order to perform the classification for a long time or to perform the classification in a short time, it is necessary to apply a strong ultrasonic wave, so that the electric sieve is easily damaged. Especially used for spacers for liquid crystal display devices
When classifying particles having a small particle size of about μm or less, the tendency of clogging the electric sieve increases. In order to adjust the concentration of particles in the dispersion in the classification device to the above range, a medium may be appropriately added and adjusted. Further, if the particle concentration in the system fluctuates due to classification, the classification speed may change or the classification accuracy may change. Therefore, it is preferable to suppress the fluctuation in particle concentration by adding a medium as appropriate.

A fifth aspect of the present invention is characterized in that at least a part of the dispersion in the classification device is caused to flow. As a result, it is possible to prevent a change in concentration due to sedimentation and the like, and the accumulation of particles on the electric sieve. Examples of a method of causing at least a part of the dispersion to flow include a method of stirring the dispersion by a stirring blade or the like, and a method of circulating the dispersion by suctioning and discharging at least a part of the dispersion. When the dispersion is circulated by the pump, the discharge of the dispersion returning to the classifier is made to collide with the electric sieve surface, and the angle between the discharge direction and the electric sieve surface is preferably 30 to 90 degrees, more preferably. When the angle is set to 45 to 90 degrees, it is possible to more effectively prevent particles from being deposited on the surface of the electric sieve. The flow rate during circulation is not particularly limited, but if it is too large, metal impurities may be mixed into the classified powder by damaging the electric sieve, and if it is too small, the flow effect of the dispersion becomes small. , 0.1-10
L / min is appropriate.

[0015] A fourth invention of the present invention is characterized in that the temperature of the liquid medium and / or dispersion during classification is 0 to 100 ° C. Preferably it is 5-70 degreeC, More preferably, it is 5-50 degreeC. By being in this temperature range, classification can be performed without impairing the functions of the particles, the medium, and the electric sieve. Further, particles containing a thermoplastic resin,
For example, if the properties change significantly due to temperature changes, such as a fixed spacer having a thermoplastic resin component on the surface, a medium with a constant temperature is additionally supplied, or a jacket is provided in the liquid contact part of the device to control the temperature. When the dispersion is circulated as described above, it is preferable to reduce the temperature change by introducing a heat exchanger into the circulation line to control the temperature. The width of the temperature change during classification is preferably within 30 ° C,
More preferably, it is within 20 ° C.

A sixth aspect of the present invention is characterized in that the amount of liquid in the classification device during classification is kept constant. By keeping the liquid amount constant, the temperature, the concentration of the particles in the system, the magnitude of the ultrasonic vibration, and the like can be kept constant, so that changes in the classification speed and the classification accuracy can be suppressed. In the present invention, “keeping the liquid volume constant” means that the change in the liquid volume is within 30%, preferably within 20%. At the time of classification, the efficiency of classification can be improved by inserting an ultrasonic irradiation tip into the classification device and irradiating the medium with ultrasonic waves. FIG. 1 shows an example of a classifier provided with an electric sieve, but the present invention is not limited to this. In FIG. 1, an electric sieve 1 is fixed so as to be sandwiched between a housing upper part 4 and a housing lower part 4 '. A support 2 for increasing the strength of the electric sieve 1 is provided, and is connected to the housings 4 and 4 'via a packing 3 made of an elastomer. An ultrasonic irradiation chip 5 is inserted into the housing upper part 4, whereby the medium in the housing is irradiated with ultrasonic vibration. Inside the housing upper part 4 are circulation lines 6, 6 'for the medium.
And a medium supply line 7. The dispersion obtained by dispersing the raw material powder in the liquid medium is charged in the housing upper part 4, and particles smaller than the opening diameter of the electric sieve move to the housing lower part 4 'together with the medium. As the operation progresses, particles smaller than the aperture size of the electric sieve existing in the housing upper part 4 decrease, and finally, the particles having a larger particle size at the boundary of the aperture size of the electronic sieve ( The particles can be classified into particles remaining in the housing upper part 4) and particles having a small particle diameter (particles moved to the housing lower part 4 ').

According to the classification methods of the first to sixth aspects of the present invention, various kinds of powders are classified easily, at low cost and precisely, without causing clogging of sieves or aggregation of particles. Can be. Therefore, the obtained particles have an extremely uniform particle size and extremely low contamination with impurities. Depending on the average particle size of the powder used, the particle size distribution and the opening size of the electric sieve, the average particle size and particle size distribution of the particles obtained by classification are different,
The ratio Cv between the standard deviation of the particle diameter and the average particle diameter can be 2 to 10%. The average particle diameter of the particles obtained by the first to sixth classification methods of the present invention is not particularly limited, and may be as small as an average particle diameter of about 0.5 μm to as large as an average particle diameter of about 100 μm. is there. Among them, even when obtaining small particles having an average particle diameter of 10 μm or less, classification can be performed accurately at low cost and without causing clogging of the sieve and aggregation of the particles. is there.

In the above description, the first to sixth classification methods of the present invention have been described, respectively. However, a further effect can be obtained by implementing a plurality of the first to sixth classification methods of the present invention in combination. Of course. The powder that can be classified by the first to sixth classification methods of the present invention is not particularly limited, but in addition to a spacer for a liquid crystal display element described later, an electroless plating powder, a base powder thereof, and a chromatograph. Examples include various powders such as a filler for chromatography, various standard particles, a carrier for an immunological diagnostic reagent, an antiblocking agent, and a lubricant. Further, the material is not particularly limited, organic cross-linked polymer particles, inorganic particles,
Organic-inorganic composite particles and the like can be mentioned.

The spacer for a liquid crystal display element of the present invention has, as its main body, particles classified by the classification method of the first to sixth aspects of the present invention. Therefore, the particle diameters are extremely uniform, and the gap distance between a pair of electrode substrates to be arranged at an accurate interval can be accurately and constantly maintained. The spacer for a liquid crystal display element of the present invention has, as its main body, particles classified by the classification method of the first to sixth inventions of the present invention described above, and may be composed of only the particles. Alternatively, an adhesive spacer having an adhesive layer on the surface of the particles serving as the main body may be used. Further, a colored spacer composed of colored particles in which the main particles are colored by containing a dye and / or a pigment may be used.

In the liquid crystal display device, by interposing the liquid crystal display device spacer of the present invention between the electrode substrates instead of the conventional spacer, a liquid crystal display device having substantially the same gap distance as the spacer can be manufactured. . The amount of the spacer to be used depends on the material of the spacer, the size of the substrate, and the like.
Pcs / mm ² , and the same conditions as those of a conventionally used spacer can be taken. The liquid crystal display device includes, for example, a first electrode substrate, a second electrode substrate, a spacer for a liquid crystal display device, a sealing material, and liquid crystal, as shown in FIG. The first electrode substrate has a first substrate and a first electrode formed on a surface of the first substrate. The second electrode substrate has a second substrate and a second electrode formed on the surface of the second substrate, and faces the first electrode substrate. The above-described spacer of the present invention is used as a spacer for a liquid crystal display element, and is interposed between the first electrode substrate and the second electrode substrate to maintain a space between the electrode substrates. The sealant adheres the first electrode substrate and the second electrode substrate at a peripheral portion. The liquid crystal is sealed between the first electrode substrate and the second electrode substrate, and is filled in a space surrounded by the first electrode substrate, the second electrode substrate, and a sealing material.

In the liquid crystal display panel of the present invention, as for the electrode substrate, the sealing material, the liquid crystal, etc., other than the spacers, the same ones as in the prior art can be used. The electrode substrate has a substrate such as a glass substrate and a film substrate, and an electrode formed on the surface of the substrate.If necessary, an alignment film formed on the surface of the electrode substrate so as to cover the electrode is formed. Have more. As the sealing material, an epoxy resin adhesive sealing material or the like is used. As the liquid crystal, those conventionally used may be used, for example, biphenyl, phenylcyclohexane, Schiff base, azo, azoxy, benzoate, terphenyl, cyclohexylcarboxylate, biphenylcyclohexane , Pyrimidine, dioxane, cyclohexylcyclohexane ester, cyclohexylethane, cyclohexene, and fluorine liquid crystals can be used.

As a method of manufacturing a liquid crystal display element, for example, the spacer of the present invention is used as an in-plane spacer.
After the spacer of the present invention is dispersed in an adhesive sealing material such as an epoxy resin as a sealing portion spacer on one of the two electrode substrates uniformly dispersed by a wet method or a dry method on one of the electrode substrates, The adhesive applied to the electrode substrate is placed on the adhesive seal by means of screen printing or the like, and an appropriate pressure is applied.
Heating for up to 60 minutes, or irradiation dose of 40 to 300 mJ /
After the adhesive sealing material is cured by irradiating ultraviolet rays of ² cm ^2, a method of injecting liquid crystal and sealing the injected portion to obtain a liquid crystal display element can be mentioned. The invention is not limited. For example,
In-plane spacer, in addition to the above method, forming an alignment film using a polymer solution containing dispersed in-plane spacer,
It may be formed by a method of forming an in-plane spacer at the same time as forming the alignment film.

The liquid crystal display device of the present invention has the same applications as conventional liquid crystal display devices, for example, televisions, monitors, personal computers, word processors, car navigation systems, DVDs, digital video cameras,
It is used as an image display element such as HS (registered trademark) (portable information terminal).

[0024]

The present invention will be described in more detail with reference to the following examples. However, the following examples do not limit the scope of the present invention. It is within the technical scope of the invention. (Example 1) Average particle size of 4.7 produced by suspension polymerization
The powder comprising divinylbenzene-based spherical particles having a particle diameter of 0.5 μm and a standard deviation of the particle diameter of 0.52 μm was classified using the apparatus shown in FIG. For classification, methanol (viscosity: 0.6 cP) was used as a dispersion medium for the powder, and the initial powder concentration was 7 watts.
At t%, the particle concentration in the classifier is 7 to 5.5 wt%, 2 L
/ Min. In the liquid circulation, the angle between the discharge direction and the electrical sieving surface was adjusted to be 75 degrees. In addition, during the classification, supply methanol appropriately,
The change in the amount of liquid at the top of the housing was set to be within 18%.

Nickel-based sieve as an electric sieve;
After classifying for 1 hour under the above conditions using a 9 μm, 1500 lines / inch (Sieve A), the liquid remaining at the top of the housing was collected (lower classification), and this was nickel-based and the pore size was 4 mm. Classification was again performed for 10 minutes using an electric sieve (sieve B) having a line size of 1.7 μm and a number of lines of 1500 / inch, and the dispersion flowing out to the lower portion of the housing was collected (upper classification). The liquid temperature during the classification was between 20 and 35 ° C. The collected dispersion was filtered and dried to obtain classified particles 1. The average particle diameter of the classified particles 1 was 4.28 μm, and the standard deviation of the particle diameter was 0.18 μm.

Example 2 Using the same apparatus as in Example 1, the average particle diameter was 6.5 μm, and the standard deviation of the particle diameter was 0.73.
μm spherical silica particles, nickel-based
Classification was performed using a sieve having a diameter of 1,000 m / inch (sieve C) and a sieve having a pore size of 7.0 μm and a number of lines of 1000 / inch (sieve D) of nickel. In the classification, n-hexane (viscosity: 0.3 cP) was used as a dispersion medium for the powder, and the powder was circulated at an initial powder concentration of 25 wt% and a particle concentration of 25 to 22 wt% in the classifier at a flow rate of 2 L / min. In the liquid circulation, the angle between the discharge direction and the electrical sieving surface was adjusted to be 70 degrees. During the classification, n-hexane was replenished appropriately so that the change in the amount of liquid in the upper portion of the housing was within 15%.
The liquid temperature during the classification was between 20 and 30 ° C.

As a result of this classification, the average particle size was 6.52 μm.
m, classified particles 2 having a standard deviation of 0.21 μm in particle diameter were obtained. (Example 3) Using the same apparatus as in Example 1, acrylic-siloxane composite spherical particles having an average particle diameter of 5.3 µm and a standard deviation of the particle diameter of 0.34 µm were used as sieves A used in Example 1 and Classification was performed using the sieve C used in Example 2. In the classification, methanol (viscosity: 0.6 cP) was used as a dispersion medium for the powder, and the initial powder concentration was 5 wt.
%, The particle concentration in the classifier is 5-4 wt%, 1.5 L /
Circulated at a flow rate of min. In the liquid circulation, the angle between the discharge direction and the electrical sieving surface was adjusted to be 80 degrees. In addition, during the classification, the supply of methanol was appropriately performed so that the change in the amount of liquid in the upper part of the housing was within 12%. The liquid temperature during the classification was between 15 and 30 ° C.

As a result of this classification, the average particle size was 5.34 μm.
m, classified particles 3 having a standard deviation of 0.18 μm in particle diameter were obtained. Example 4 Using the same apparatus as in Example 1, spherical benzoguanamine particles having an average particle diameter of 10.5 μm and a standard deviation of the particle diameter of 0.50 μm were converted to nickel-based pore diameters of 9.3 μm.
m, sieve with 1000 lines / inch (Sieve E) and nickel-based sieve with an opening diameter of 11.4 μm, 1000 lines / inch
Classification was performed using an inch sieve (Sieve F).
In the classification, methanol (viscosity: 0.6 cP) was used as a dispersion medium for the powder, and the powder was circulated in the classification device at an initial powder concentration of 7 wt% and a particle concentration of 7 to 5 wt% at a flow rate of 3 L / min. In the liquid circulation, the angle between the discharge direction and the electrical sieving surface was adjusted to be 75 degrees. In addition, methanol was appropriately supplied during the classification, so that the change in the amount of liquid in the upper portion of the housing was within 25%. The liquid temperature during the classification was between 20 and 40 ° C.

As a result of this classification, the average particle size was 10.48 μm.
m, classified particles 4 having a standard deviation of 0.44 μm in particle diameter were obtained. (Example 5) In Example 2, a polyimide solution (viscosity: 20 cP) was used as a powder dispersion medium, and the initial powder concentration was 2
Classification was performed in the same manner except that the concentration of the particles in the classifier was 2 wt%, the circulation flow rate was 0.5 L / min, and the additional dispersion medium was changed to the above polyimide solution. The change in liquid volume at the top of the housing was within 15%. The liquid temperature during the classification was between 20 and 25 ° C.

As a result of this classification, the average particle size was 6.51 μm.
Polyimide solution 5 containing m and classified particles having a standard deviation of 0.18 μm in particle diameter was obtained. (Example 6) As the core particles, the surface of the classified particles 3 obtained in Example 3 was coated with a styrene-acrylic resin (average particle diameter of 0.1%).
Dry coating was performed at 4 μm, Tg of 68 ° C.) to obtain thermoplastic resin-coated particles. The average particle diameter of the particles was 6.2 μm, and the standard deviation of the particle diameter was 0.78 μm. The coated particles were classified using the same apparatus as in Example 1, using sieve A used in Example 1 and sieve C used in Example 2. In classification, n-butanol (viscosity 25c) was used as a dispersion medium for the powder.
Using P), the powder was circulated at an initial powder concentration of 5 wt%, a particle concentration of 5 to 4 wt% in the classifier, and at a flow rate of 1.5 L / min. In the liquid circulation, the angle between the discharge direction and the electrical sieving surface was adjusted to be 80 degrees. Also, during the classification, n-butanol was appropriately replenished, so that the change in the amount of liquid in the upper part of the housing was within 20%. The liquid temperature during the classification was between 15 and 30 ° C.

As a result of this classification, the average particle size was 5.54 μm.
Classified particles 6 having m and a standard deviation of particle diameter of 0.27 μm were obtained. (Comparative Example 1) In Example 1, the initial powder concentration was 55 wt.
%, A large amount of particles settled on the sieve B, and only a few classified particles (comparative classified particles 1) were obtained. The average particle diameter of the comparative classified particles 1 was 4.22 μm, and the standard deviation of the particle diameter was 0.27 μm.
Met. (Comparative Example 2) In Example 1, the initial powder concentration was 0.00
5 wt%, and the particle concentration in the classifier is 0.02 to 0.
When the same operation was performed except that the classification was performed at 005 wt%, classified particles were obtained only in a yield of 1/20 or less as compared with Example 1.

(Comparative Example 3) In Example 2, the initial powder concentration was set to 30 wt%, and classification was performed using a sieve C without adding a solvent during classification, and the particle concentration in the apparatus was 53 wt%. %. Also, the change in the amount of liquid in the upper part of the housing was 55%. At this time, a large amount of particles settled on the sieve C and the outflow of the classification liquid to the lower portion of the housing was significantly reduced, so that the lower classification was completed. Then, after performing upper classification using a sieve D, filtration and drying were performed to obtain comparative classified particles 3. The average particle size of the comparative classified particles 3 is 6.
The standard deviation of the particle diameter was 50 μm and the particle diameter was 0.25 μm.

(Comparative Example 4) In Example 2, the initial powder concentration was set to 0.02 wt%, and hexane as a solvent was added during the classification to reduce the particle concentration in the classification device to 0.1%.
When classification was performed with 008 to 0.005 wt%,
Classified particles were obtained only in a yield of 1/50 or less as compared with Example 2. (Comparative Example 5) The same operation was performed as in Example 5, except that the polyimide solution of the dispersion medium was changed to 60 cP. As a result, the liquid did not flow out to the lower portion of the housing, and classification could not be performed.

(Comparative Example 6)
When the temperature was set to 5 ° C., the particles aggregated and only the dispersion medium flowed out to the lower portion of the housing, so that classification was impossible. (Comparative Example 7) In Example 3, classification was performed using a sieve C without performing liquid circulation. After 30 minutes during the classification, the outflow of the classified liquid to the lower portion of the housing was significantly reduced, and the operation was stopped. The dispersion recovered so far was less than 20% by weight based on the yield of Example 3.

Example 7 A liquid crystal display device as shown in FIG. 2 was manufactured by the following method. First, 300mm × 3
After forming the transparent electrode 15 and the polyimide alignment film 14 on the lower glass substrate 21 of 45 mm × 1.1 mm, rubbing was performed to obtain the lower electrode substrate 210. On the lower electrode substrate 210, the classified particles 1 obtained in Example 1 were mixed in a mixed solvent of 30 parts by weight of methanol, 20 parts by weight of isopropanol, and 50 parts by weight of water.
A dispersion uniformly dispersed so as to be 1% by weight as 8 was sprayed for 5 seconds.

On the other hand, 300 mm × 345 mm × 1.1 m
After forming the transparent electrode 15 and the polyimide alignment film 14 on the m upper glass substrate 22, rubbing was performed to obtain the upper electrode substrate 220. Then, the classified particles 1 obtained in Example 1 dispersed in an epoxy resin adhesive sealant so as to be 30% by weight as a seal spacer 13 were screen-printed on the adhesive seal portion of the upper electrode substrate 220. Finally, the upper electrode substrate 220 and the lower electrode substrate 210 are bonded via the liquid crystal display element spacer 18 so that the electrode 15 and the alignment film 14 face each other, and a pressure of 4 kg / cm ² is applied, and The adhesive sealant 12 was cured by heating at a temperature of 30 minutes. Thereafter, the gap between the two electrode substrates 210 and 220 is evacuated, and the pressure is returned to the atmospheric pressure.
7, and the injection portion was sealed. Then, the polyvinyl alcohol-based polarizing film 1 is provided outside the upper and lower glass substrates 22 and 21.
6 was attached to the liquid crystal display element 1.

The liquid crystal display element 1 was visually evaluated for the presence or absence of image unevenness, and no image unevenness was confirmed. (Examples 8 to 11, Comparative Examples 8 and 9) Using the classified particles obtained in Examples 2 to 4 and 6, and Comparative Examples 1 and 3, in the same manner as in Example 7, the liquid crystal display elements 2 to 5, Comparative liquid crystal display elements 1 and 2 were produced, respectively, and evaluated in the same manner as in Example 7. Table 1 shows the results. (Example 12) A liquid crystal display device as shown in FIG. 2 was manufactured by the following method. First, 300mm x 345mm x
After forming the transparent electrode 15 on the lower glass substrate 21 of 1.1 mm, the polyimide solution containing the spacer 8 for the liquid crystal display element is formed using the polyimide solution obtained in Example 5, and rubbing is performed. Go to the lower electrode substrate 21
0 was obtained.

On the other hand, 300 mm × 345 mm × 1.1 m
After forming the transparent electrode 15 on the m upper glass substrate 22, the polyimide alignment film 14 containing no spacer was formed and rubbed to obtain an upper electrode substrate 220. Then, the classified particles 2 obtained in Example 2 dispersed in an epoxy resin adhesive sealant as a seal spacer 13 so as to be 30% by weight were screen-printed on the adhesive seal portion of the upper electrode substrate 220. Finally, the upper electrode substrate 220 and the lower electrode substrate 210 are bonded via the liquid crystal display element spacer 18 so that the electrode 15 and the alignment film 14 face each other, and a pressure of 4 kg / cm ² is applied, and The adhesive sealant 12 was cured by heating at a temperature of 30 minutes. Thereafter, the two electrode substrates 21
The gap between 0 and 220 was evacuated and then returned to atmospheric pressure to inject liquid crystal 17 mixed with biphenyl-based and phenylcyclohexane-based liquid crystal substances, and the injection portion was sealed. Then, a polyvinyl alcohol-based polarizing film 16 was attached to the outside of the upper and lower glass substrates 22 and 21 to obtain the liquid crystal display element 6.

When the presence or absence of image unevenness was visually evaluated for the liquid crystal display element 6, no image unevenness was confirmed.

[0040]

[Table 1]

[0041]

According to the classification method of the first invention of the present invention, since the concentration of the raw material powder in the dispersion is 0.01 to 50% by weight, a large amount of time is not required for classification and the electric sieve is not used. Clogging of the opening is unlikely to occur. Therefore, classification efficiency and classification accuracy are high, and there is little problem of damage to the electric sieve. In the classification method according to the second aspect of the present invention, the concentration of the particles in the dispersion in the classification device is 0.01 to 50 wt%.
Therefore, a large amount of time is not required for classification, and clogging of the opening of the electric sieve hardly occurs. Therefore, classification efficiency and classification accuracy are high, and there is little problem of damage to the electric sieve.

In the classification method according to the third invention of the present invention, since the liquid medium having a viscosity of 50 cP or less is used,
Classification speed can be improved. In the classification method of the fourth invention of the present invention, the classification is performed without impairing the functions of the particles, the medium, and the electric sieve since the temperature of the liquid medium and / or the dispersion during the classification is 0 to 100 ° C. be able to. In the classification method according to the fifth aspect of the present invention, since at least a part of the dispersion in the classification device is caused to flow, a change in concentration due to sedimentation or the like, a deposition of particles on the electric sieve, and the like can be prevented.

In the classification method according to the sixth aspect of the present invention, the temperature, the concentration of the particles in the system, the magnitude of the ultrasonic vibration, and the like are kept constant in order to keep the liquid volume in the classification device constant during the classification. Therefore, changes in classification speed and classification accuracy can be suppressed. Since the classified particles of the present invention are particles classified by the powder classification method according to any one of the first to sixth inventions of the present invention, the particle diameters are extremely uniform, and The contamination with impurities is extremely small. The spacer for a liquid crystal display element of the present invention has, as a main body, particles classified by the method for classifying a powder according to any one of the first to sixth inventions of the present invention, the particle diameter is extremely uniform, The gap distance between the pair of electrode substrates to be arranged at accurate intervals can be accurately and constantly maintained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating an example of a classification device used in a classification method of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating an example of a liquid crystal display device using the spacer for a liquid crystal display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric sieve 2 Support 3 Packing 4 Housing upper part 4 'Housing lower part 5 Ultrasonic irradiation chip 6, 6' Medium circulation line 7 Medium supply line 12 Adhesive sealing material 13 Seal part spacer 14 Alignment film 15 Electrode 16 Polarization film 17 Liquid crystal 18 In-plane spacer 21 Lower glass substrate 22 Upper glass substrate 210 Lower electrode substrate 220 Upper electrode substrate

Continued on the front page (72) Inventor Shinji Wakatsuki 5-8, Nishiobari-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. (72) Inventor Reinari Sasaki 5-8, Nishiobari-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. (72) Inventor Nobuhiko Fujisawa 5-8, Nishiobari-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. (72) Inventor Taiki 5-8, Nishi-Otabi-cho, Suita-shi, Osaka Nippon Shokubai F-term Co., Ltd. (Reference) 4D071 AA02 AB03 AB25 AB43 AB45 BB12 BB13 DA20

Claims (8)

[Claims] 1. A dispersion obtained by dispersing a raw material powder in a liquid medium is passed through a classification device equipped with an electric sieve,
A method of classifying the raw material powder into particles having a desired particle size range, wherein the concentration of the raw material powder in the dispersion is 0.01%.
A method for classifying powder, characterized in that the content is from 50 to 50% by weight. 2. A dispersion obtained by dispersing a raw material powder in a liquid medium is passed through a classifier equipped with an electric sieve,
A method for classifying the raw material powder into particles having a desired particle size range, wherein the concentration of the particles in the dispersion in the classification device is 0.01 to 50 wt%. 3. A dispersion obtained by dispersing a raw material powder in a liquid medium is passed through a classifier equipped with an electric sieve,
A method for classifying the raw material powder into particles having a desired particle size range, wherein the liquid medium has a viscosity of 50 cP or less. 4. A dispersion obtained by dispersing the raw material powder in a liquid medium is passed through a classifier equipped with an electric sieve,
A method for classifying the raw material powder into particles having a desired particle size range, wherein the temperature of the liquid medium and / or the dispersion during the classification is 0 to 100 ° C. . 5. A dispersion obtained by dispersing a raw material powder in a liquid medium is passed through a classifier equipped with an electric sieve,
A method for classifying the raw material powder into particles having a desired particle size range, wherein at least a part of the dispersion in the classifier is fluidized. 6. A dispersion obtained by dispersing a raw material powder in a liquid medium is passed through a classifier equipped with an electric sieve,
A method for classifying the raw material powder into particles having a desired particle size range, wherein a liquid amount in the classifier is kept constant during the classification. 7. Particles classified by the method for classifying powder according to any one of claims 1 to 6. 8. A spacer for a liquid crystal display element, comprising as a main body particles classified by the powder classification method according to any one of claims 1 to 6.