JPH0768197A - Dry powder sprinkling method and device therefor - Google Patents

Abstract

PURPOSE:To improve the efficiency in sprinkling a fine powder on a substrate by arranging a material to be sprinkled with the face to be deposited with a powder turned upward at the lower part of of a vertical cylinder-shaped powder sprinkling space surrounded by the face of an insulator or the face charged in the same polarity as the powder and sprinkling a charged powder over the material from the upper part of the space. CONSTITUTION:A material 11 to be sprinkled with a powder is supported by a supporting means 9, and a powder sprinkling means 4 is provided above the supporting means 9. The powder to be sprinkled from the means 4 is charged by a first charging means 5, a powder sprinkling space between the means 4 and 9 are surrounded by an enclosure 2, and the inner face of the enclosure 2 is charged in the same polarity as the powder by a second charging means 7. The material 11 with the face to be deposited with the powder turned upward is arranged at the lower part of the vertical cylinder-shaped powder sprinkling space surrounded by the enclosure 2 with the face charged in the same polarity as the face of an insulator or the powder, and the charged powder is sprinkled over the material 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder-dispersing device capable of uniformly distributing a fine powder of, for example, about 1 to 10 .mu.m to a target surface uniformly and efficiently without waste, typically a liquid crystal. The present invention relates to an electro-optical element used, and more particularly to a powder spraying device used for inserting fine powder particles as a spacer between two transparent substrates constituting a liquid crystal display panel.

[0002]

2. Description of the Related Art The prior art to which the present invention is applied will be described below by taking as an example a method of spraying fine powder used in manufacturing a liquid crystal display panel.

A liquid crystal display panel (liquid crystal display) is
A display area of segment type or matrix format is set by stacking transparent electrodes that can partially apply voltage to a panel consisting of two transparent substrates filled with liquid crystal in the middle, and selected to the appropriate part of the display area. It forms a panel part of a liquid crystal display device that displays information such as specific figures and characters by applying an electric field, and seals the peripheral parts of two liquid crystal substrates (transparent electrode substrates) that compose the panel. Then, an empty cell container is assembled, a liquid crystal material is injected through an injection hole provided in advance, and then the injection hole is sealed.

In such a structure, since it is necessary to make two liquid crystal substrates face each other with a uniform gap of several to 10 μm and to provide a space for injecting the liquid crystal material, a spacer (liquid crystal spacer) between these substrates is required. Say)
The fine powder is inserted with a uniform dispersion concentration and dispersion state. In order to insert the liquid crystal spacers between the substrates as described above, a method of spraying fine powder particles dispersed in the state of primary particles on the substrates from a nozzle has been conventionally adopted (for example, Japanese Patent Laid-Open No. Sho 64-64). No. 76031), the other substrate is laid on top of the liquid crystal spacers, and the above-mentioned peripheral portion seal and then liquid crystal material injection are performed.

There are a dry method and a wet method as a method of spraying the liquid crystal spacers on the liquid crystal substrate. The wet method is a method in which spacer particles (plastic or silica) dispersed in a liquid such as chlorofluorocarbon, alcohol or pure water are sprayed together with this liquid onto a substrate placed on a predetermined table or the like. The method is a method of forcibly charging the spacers with an electrostatic gun to attach them to the substrate on the above table, or a method of transporting the spacer particles in a high-speed airflow through a thin tube to frictionally charge the spacer particles and attaching them to the substrate in the same manner. Is.

[0006]

However, in the above-mentioned wet method, when the liquid used is, for example, chlorofluorocarbon, its use tends to be restricted due to environmental problems. Further, since alcohol is explosive, there are problems such as restrictions on the environment in which it is used and explosion-proof equipment. In addition, when pure water is used, there is a problem that dirt remains on the substrate and the dirt affects the display screen. Recently, in order to avoid this, it is called ultrapure water or ultrapure water. Although the use of high-purity water is considered, there is a problem that the facility load for producing ultrapure water is large.

On the other hand, the dry method does not have the above-mentioned problems such as the influence on the environment and the explosion when the gas such as air or nitrogen is used as the carrier air flow, and the spraying efficiency (adhesion to the substrate). It is superior to the wet method in that it is defined by powder amount / sprayed powder amount and is the same as the utilization rate. Therefore, the spraying of spacers by a dry method instead of the wet method has recently attracted attention.

However, although the spraying efficiency is higher than that of the wet method, the actual spraying efficiency in the case of powder spraying of this dry method is such that at most about 10% of the total spraying amount adheres to the substrate. The rest (about 9 in the example above)
0%) is wasted as non-use.

By the way, the fine powder particles for the spacers, which are inserted between the substrates of the liquid crystal display panel as described above, have a narrow particle size distribution range and a uniform particle size in order to maintain a high accuracy of the space between the substrates. Those that are highly demanded and are usually subjected to an advanced classification treatment are used. Moreover, since this fine powder is present in the liquid crystal material, it is a very high value-added fine powder that has properties that are chemically stable with respect to the liquid crystal material and that does not have an optical adverse effect on the screen display. The use of powder is needed. Such fine particles are generally expensive, and inefficient use of such fine particles at a low utilization ratio as described above not only wastes useful materials but also causes a rise in cost of the liquid crystal display panel. Will also be.
Therefore, there is a demand for a device for improving the efficiency of spraying the spacer particles onto the substrate.

The present invention has been made for the purpose of improving the spraying efficiency of such fine powder particles on a substrate.

Another object of the present invention is to improve the spraying efficiency of the fine powder on the substrate, to reduce the spraying amount of the fine powder and to effectively utilize the resources by improving the utilization rate. is there.

Another object of the present invention is to use fine powder which is expensive because it satisfies the requirements such as material and uniformity of particle size as described above, when it is used as a spacer between substrates of a liquid crystal display panel. By reducing the spray amount and improving the utilization rate, the cost of products such as liquid crystal display panels can be reduced.

[0013]

In order to achieve the above object, the present inventor has completed the present invention described in each claim of the above claims.

That is, the dry powder spraying method of the present invention as set forth in claim 1 is a powder in which the periphery is surrounded by a vertical tube shape by the surface of the insulator or the surface charged by the charging means to the same polarity as the sprayed powder. It is characterized in that an object to be sprayed is arranged in a lower part of the spraying space with the powder adhering surface facing upward, and the charged powder is sprayed to the object to be sprayed from the upper part of the space.

In the above description, surrounding the periphery in the form of a vertical cylinder by the surface of the insulator means isolating the powder dispersion space from the outer space in the horizontal direction by the insulator, for example, the object to be dispersed is a square or the like. In the case of the rectangular shape, the powder-dispersing space is provided in the shape of an enclosing wall which is formed as a planar rectangular tubular space by four side walls made of an insulating plate. It should be noted that the shape of the wall of the insulator surrounding the powder dispersion space is not limited to this, and may be surrounded by a circular cylindrical wall depending on the shape of the object to be dispersed. Further, the same insulator may be covered above the powder spraying position. As a material preferably used as such an insulator, for example, a plate material of vinyl chloride resin, acrylic resin or the like can be exemplified.

The position of the insulator surrounding wall with respect to the object to be scattered is preferably provided as close as possible on the condition that there is no hindrance to the drop and adhesion of the powder to the powder adhesion surface on the object to be scattered.

According to this method, the charged powder adheres to the inner surface of the insulator facing the powder dispersion space during the first spraying, and as a result, the surface is charged to the same polarity as the powder. After that, the powder to be sprayed is efficiently adhered to the object to be sprayed.

Instead of the insulator surrounding wall surrounding the powder-dispersing space, for example, a surrounding wall charged with the same polarity as the dust-dispersing powder by providing a charging electrode outside the surrounding wall can be used. In this way, the sprayed powder can be efficiently attached to the substrate from the initial stage of spraying.

In the above description, "charged powder" means a method of charging the sprayed powder using an electrostatic gun at the spraying nozzle,
The powder is charged by a method in which the powder is transported by a high-speed airflow in a narrow tube that transports the powder to a spray nozzle and frictionally charged. The charging method is not particularly limited. The degree of electrification is not particularly limited, but the larger the sum of the electrification amount of the surrounding wall surrounding the powder-dispersing space and the electrification amount of the powder, the more preferable.
It is desirable that the voltage is about 000V, preferably about 2000V to 10000V.

The powder can be sprayed by using, for example, a known powder spraying nozzle, and the powder spraying nozzle can be a fixed type, a circular swivel type, a zigzag moving type, a combined moving and swiveling type, or the like. Can be selected and used. The powder dispersed by the method of the present invention is not particularly limited in terms of material such as electrically charged plastic particles, ceramics, and inorganic particles such as silica (precipitated silicic acid). The particle size is 1μ
Typical examples are those of m to 10 μm, but the invention is not particularly limited to this, and is selected according to the purpose of use and action of the object to be sprayed to which the powder is attached. It should be noted that it is preferable to use, as the spraying powder, particles which have been dispersed in the state of primary particles by a dispersing means provided before the dispersing means such as a spraying nozzle. To disperse the powder, any of a method of using a rotating brush or the like and a method of dispersing the powder by collision during air flow transportation can be used.

The object to be sprayed to which the powder is applied is not limited to a plate material such as glass, a plastic film, a block body, etc., but if the uniformity of the spraying is required and the powder to be sprayed has a high added value. In particular, the method of the present invention can realize a high powder dispersion efficiency, which is particularly beneficial. As such, the case of spraying spacer particles on the transparent electrode substrate of the above-described liquid crystal display panel can be typically mentioned. it can.

In addition to the above construction, the method of the present invention as set forth in claim 2 is characterized in that the powder adhered surface of the object to be sprayed is charged to the opposite polarity to the sprayed powder. The degree of electrification of the powder adhering surface is different from that of the powder particles and the magnitude thereof is 100V to 10000V, preferably 2000V to 5V.
000V is good.

The present invention as set forth in claim 3 is characterized by a dry powder spraying device for realizing the above-described spraying method.

That is, a supporting means for supporting the object to be dispersed on which the powder is scattered, a powder dispersing means such as a powder dispersing nozzle provided above the supporting means, and the powder dispersing means. First charging means for charging the powder to be sprayed from the means, and an insulator made of vinyl chloride resin, acrylic resin, etc., which surrounds the periphery of the powder spraying space between the powder spraying nozzle and the support, which are vertically opposed to each other. It is characterized in that it has a structure including an enclosure wall.

In the above, examples of the supporting means for supporting the object to be scattered include a table on which the object to be scattered is placed. It is also possible to use a movable table such as a conveyor as a supporting means so as to transfer the object to be sprayed into and out of the powder spraying position.

As the first charging means for charging the powder to be sprayed, the powder spraying means, and the insulator surrounding wall, those described above can be used.

For the dry powder spraying of the present invention, air or an inert gas such as nitrogen gas is used as the gas, and the powder is conveyed from the powder storage tank to the powder spraying means via the dispersing means. can do.

Further, in place of the above-mentioned insulator surrounding wall, the periphery of the powder dispersion space is surrounded by a surrounding wall (not limited to the insulator surrounding wall), and the inner surface of the surrounding wall is charged to the same polarity as the dispersion powder. The charging means may be used, and in this case, the surrounding wall may be charged to a higher potential than the powder.

In the apparatus of the present invention, when, for example, the table on which the object to be sprayed is placed is electrostatically neutralized, it may be grounded as shown in the embodiments described later. Further, in order to improve the adhesion efficiency, the powder adhesion surface of the object to be sprayed may be charged with a polarity different from that of the sprayed powder. For example, the table can be charged to a high potential by means of an electrode having a polarity different from that of the sprayed powder as the third charging means. The charge amount has a polarity different from that of the powder particles, and the size thereof is 100V to 10000V, preferably 2000V to 5000V.

INDUSTRIAL APPLICABILITY The present invention is particularly effective as a method and apparatus for spraying spacer particles to be inserted between a pair of transparent substrates on a transparent electrode substrate of a liquid crystal optical element, and when used for manufacturing such a liquid crystal optical element. In order to make the distribution state of the spacer particles scattered on the substrate uniform on the substrate, the spray nozzle as the powder spraying means is caused to perform a circular motion or a zigzag motion according to a predetermined locus. It is also preferable to

For example, as the moving mechanism of the spray nozzle, a nozzle swing device for swinging the spray nozzle in the x and y directions of two horizontal axes with respect to the substrate, a conveyor such as a conveyor for moving the substrate in the x direction, etc. 1 means of movement and spray nozzle
Examples include a type in which a second moving unit that reciprocates in a direction (for example, a nozzle swinging unit that reciprocates a nozzle in one direction) is combined, a unit in which a plurality of spraying deviations are provided, and the like. According to these devices, it is possible to configure a continuous processing device for spraying powder while continuously transporting a large number of substrates by a conveyor or the like.

In the above-mentioned "zigzag movement", it is often preferable to draw the locus of the nozzle extension line in a rectangular meandering pattern on the substrate from the viewpoint of realizing uniform spraying without overlapping the spraying areas.

The present invention is preferably used in combination with a powder supply device (for example, the device described in Japanese Patent Application No. 3-287879) capable of supplying fine powder in a state of being dispersed in primary particles as much as possible. Such a device has an advantage that the powder is sufficiently dispersed during (transporting) the powder from the powder supply device to the nozzle. That is, the powder is quantitatively supplied to the circulating air, and the air containing the powder is transported at high speed in the thin tube from the powder supply device to the nozzle, thereby further promoting the dispersion in the thin tube. Because it is done.

The powder-dispersing device of the present invention can be used for various powder-dispersing purposes. In particular, powder as a spacer is inserted between the substrates of electro-optical elements using liquid crystal. Excellently applied in applications.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings.

Example 1 FIGS. 1 and 2 are views for explaining an example of an apparatus in which the method of the present invention is applied to manufacture of a liquid crystal display panel. In these figures, 1 is a space for powder dispersion. Is a chamber that is a container that is partitioned from the outside, and a rectangular substrate (for example, a transparent electrode is mounted on the lower surface side of the drawing) to be sprayed on a table 9 installed in the lower part of the chamber by an opening / closing door (not shown). One side substrate 11 of the liquid crystal display panel having the structure is provided so that it can be placed and taken out from the outside. In addition, the table 9 is a conductor wire provided with a changeover switch 13 in the middle so that the entire surface of the substrate 11 placed on the table 9 can be selectively placed in an electrostatically uniform neutral state or a charged state. 10 is connected, one of which is switched by the changeover switch 13 is grounded, and the other is another high voltage generator 7
Connected to B.

Reference numeral 4 denotes a spraying nozzle, and in this example, powder sent from a spacer supply tank 6 storing spacers through a thin tube 5 which is a spacer transport pipe by an air stream from a nitrogen stream supply source (not shown). That is, the powder is triboelectrically charged while being dispersed in the state of primary particles in the thin tube 5, and is sprayed from the tip of the nozzle at a predetermined wide-angle spray angle.

Reference numeral 12 is an exhaust pipe connected to the lower portion of the chamber 1 for exhausting the internal air to the outside by a suction blower 8.

Reference numeral 2 is an enclosure wall having a square cylindrical horizontal cross section so as to surround the area of the powder-dispersing space where the spray nozzle 4 and the substrate 11 placed on the table 9 face each other. For example, it is made of vinyl chloride resin, acrylic resin). In the present example, a ceiling portion made of the same insulator is also provided on the upper part of the surrounding wall, and the tip of the spray nozzle 4 is fixedly penetrated to the central portion thereof.

Reference numeral 3 denotes an electrode of the second charging means, which is connected to the high voltage generator 7 and is provided on the inner surface of the insulator surrounding wall 2 so as to apply the same polarity as the sprayed powder. The electrodes 3 are respectively installed on the outsides of the wall surfaces of the square surrounding wall as shown in FIG.

Using the above apparatus, spacer particles were scattered on the glass substrate under the following conditions, and the scattering efficiency (adhesion amount / dispersion amount) at that time was measured. The amount of adhesion was calculated by measuring the number of adhesions with a microscope and multiplying the number by the weight of one spacer particle.

(Spraying conditions) Spacer particles: Plastic particles having an average particle size of 5 μm Carrier gas: Nitrogen gas Glass substrate: 300 mm × 300 mm square Powder amount: 5 mmg powder Electrification ... Friction electrification Enclosure (insulator) ... Acrylic resin Enclosure electrification ... Potential (+ 2000V) The results are shown in Table 1 below.

Further, a comparison test of powder dispersion was conducted in the same manner except that the insulator surrounding wall was not provided, and the dispersion efficiency was measured. The results are shown in Table 1 below.

[0044]

[Table 1]

Second Embodiment Using the apparatus of the first embodiment, by switching the changeover switch 13, the substrate mounting table 8 is switched between the high voltage generator 7 and the earth 10 as follows. That is, in this example, the table was charged with a polarity different from that of the powder particles only during the powder dispersion, and after the dispersion, the switch was switched to the ground to remove the charge and the substrate was taken out.

The spraying was carried out under the following conditions. The measurement method and calculation method were the same as in Example 1.

(Spraying conditions) Spacer particles ··· Plastic particles with an average particle size of 5.5 μm Carrier gas ··· Nitrogen gas Glass substrate ··· 300 mm × 350 mm square · Powder dispersion amount ··· 7 mmg Powder electrification ... Friction electrification Enclosure (insulator) ... Vinyl chloride resin Enclosure electrification ... Potential (+ 2000V) Table electrification ... Potential (-5000V) The results are shown in Table 2 below. It was

[0048]

[Table 2]

Example 3 Using the apparatus of Example 1, the table 9 was connected to the ground by switching the changeover switch 13. The high voltage generator 7 was not used.

That is, in the present embodiment, the high voltage generator 7 is used to use the enclosure wall as an insulator, and the insulator enclosure wall is charged to the same polarity as the powder by the adhesion of the powder to be scattered. I did.

The spraying was carried out under the same conditions as in Example 2. The measurement method and calculation method were the same as in Example 1.
As a result, the charging of the surrounding wall and table became as follows. Charging of wall ... Potential (+ 1500V) (however, measured value) Charging of table ... Potential (0V) (earth) The results are shown in Table 2 below.

[0052]

[Table 3]

[0053]

According to the present invention, there is an effect that it is possible to improve the spraying efficiency of fine powder on the substrate. As a result, the amount of powder, which is extremely expensive to satisfy requirements such as material and particle size uniformity, is reduced, cost is reduced, and resources are used effectively. In addition, the cost of products such as liquid crystal display panels can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic plan view of an entire powder spraying device to which the present invention is applied,

FIG. 2 is a vertical cross-sectional front view showing the schematic configuration of the apparatus shown in FIG.

[Explanation of symbols]

1 ... Chamber, 2 ... Enclosure, 3 ... Electrode of charging device, 4 ... Spray nozzle, 5 ... Capillary tube, 6 ...
Spacer supply tank, 7, 7B ... High voltage generator,
8 ... Suction blower, 9 ... Table, 10 ...
Earth, 11 ... Substrate, 12 ... Exhaust pipe.

Claims (7)

[Claims] 1. A material to be sprayed having a powder adhering surface facing upward at a lower portion of a powder spraying space surrounded by a surface of an insulator or a surface charged with the same polarity as the sprayed powder in a vertical cylindrical shape. A dry powder-dispersing method, characterized in that electrically-charged powder is sprayed onto an object from above the space. 2. The dry powder-dispersing method according to claim 1, wherein the powder-adhering surface of the object to be sprayed is charged to the opposite polarity to the charged powder to be sprayed. 3. A support means for supporting an object to be sprayed on which powder is scattered, a powder spraying means provided above the support means so as to face the powder, and a powder sprayed from the powder spraying means. Dry powder dispersal comprising: a first electrifying means for electrifying the powder; and an insulator surrounding wall surrounding a perimeter of the powder dispersal space between the powder dispersal means and the support means, which are vertically opposed to each other. apparatus. 4. A support means for supporting an object to be sprayed on which powder is scattered, a powder spraying means provided above and above the support means, and a powder sprayed from this powder spraying means. First charging means for charging the above, a surrounding wall surrounding the periphery of the powder spraying space between the powder spraying means and the supporting means which are vertically opposed, and the inner surface of this surrounding wall is charged to the same polarity as the sprayed powder. A dry powder-dispersing device, comprising: a second charging unit. 5. A support means for supporting a transparent electrode substrate for constituting a liquid crystal display panel, which is an object to be sprayed, and a pair of transparent electrode substrates of the liquid crystal display panel, which are provided above the support means so as to face each other. A spraying means for spraying the spacer particles to be inserted, a first charging means for charging the spacer particles sprayed from the spraying means, and a space around the spacer particle spraying space between the spraying means and the supporting means which are vertically opposed to each other. A dry powder-dispersing device, comprising: an insulating surrounding wall. 6. A support means for supporting a transparent electrode substrate for constituting a liquid crystal display panel, which is an object to be sprayed, and a pair of transparent electrode substrates of the liquid crystal display panel, which are provided above the support means so as to face each other. A spraying means for spraying the spacer particles to be inserted, a first charging means for charging the spacer particles sprayed from the spraying means, and a space around the spacer particle spraying space between the spraying means and the supporting means which are vertically opposed to each other. A dry powder-dispersing device comprising: a surrounding wall; and a second charging unit that charges the inner surface of the surrounding wall to the same polarity as the powder to be sprayed. 7. The method according to any one of claims 3 to 6,
A dry powder-dispersing device comprising a third charging means for charging the powder-adhered surface of the object to be sprayed with a polarity opposite to that of the sprayed powder.