JPH04338133A - Production of glass powder - Google Patents

Abstract

PURPOSE:To offer the production method of glass powder by which such particles having extremely large or small aspect ratios are hardly produced, the powder can be produced at high yield and is easily classified, and the obtd. powder can be used as a spacer for a liquid crystal display device to make a uniform distance between substrates. CONSTITUTION:Glass filament is preliminarily pulverized to 200-1000mum fiber length and then continuously pressurized in a pressurizing chamber to obtain the glass powder. The obtd. glass powder hardly includes such particles having extremely large or small aspect ratios. Thereby, classification of the powder can be done simply and the production yield can be improved.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for producing glass powder, which is mainly used as a spacer for uniformizing the spacing between substrates of liquid crystal display devices, and can also be used as a filler for injection molded composite materials. .

0002

[Prior Art] Until now, cylindrical glass powder obtained by crushing long glass fibers, polystyrene,
Spherical plastic beads made of acrylic resin, phenolic resin, etc. have been used. Moreover, among these, glass powder has been effectively used as a filler for FRP and FRTP or for electrical insulation purposes.

Conventionally, glass powder is made by sandwiching long glass fibers and cutting them into appropriate lengths on the millimeter order using a guillotine cutter or other cutting device. As described on page 75 (published by Gihodo Publishing Co., Ltd., 1st edition, 1st printing), it has been made by finely pulverizing it with a ball mill, stirring blade type pulverizer, etc.

0004

[Problems to be Solved by the Invention] However, depending on the above-mentioned method, no matter how devised the crushing operation is, the fiber length is 100 μm, which is not preferable for use as a spacer for uniformizing the distance between the substrates of a liquid crystal display device. The above items are 5
% or more, and similarly cannot be used as a spacer, aspect ratio, i.e. (fiber length) / (fiber diameter)
is less than 1 in 10% or more, and in some cases nearly 40%, and no remarkable improvement in yield can be expected. In addition,
The generation of a large amount of such defective products (hereinafter referred to as junk powder) has made it difficult to perform a classification operation to obtain glass powder as a product.

The object of the present invention is to reduce the occurrence of extremely large and extremely small aspect ratios, to have a high yield, and to facilitate classification operations, and to be used primarily as a spacer for uniformizing the spacing between substrates of liquid crystal display devices. An object of the present invention is to provide a method for producing glass powder that is possible.

[0006]

[Means for Solving the Problems] Instead of performing the crushing operation in one step using a ball mill, stirring blade type crusher, etc., the present inventor has proposed a preliminary pulverization process using a ball mill, stirring blade type crusher, etc. As a process, first the fiber length is 200 to 100.
By preparing a base glass powder with a diameter of 0 μm and then continuously applying pressure to the base, a glass powder that can be used as a spacer for uniformizing the distance between substrates of a liquid crystal display device can be produced in a high yield. Based on this finding, the present invention has been completed.

[0007] That is, the gist of the present invention is a method for producing glass powder by pre-pulverizing long glass fibers to a fiber length of 200 to 1000 μm, and then packing the fibers into a pressurizing container and subjecting them to continuous pressurization. It is.

The present invention will be explained in detail below. Preliminary crushing of glass fibers is performed as follows. First, the long glass fibers to be pre-pulverized are sandwiched and cut into an appropriate length on the order of millimeters to centimeters, preferably about 10 to 20 mm, using a guillotine cutter or other cutting device. Next, the cut glass fibers are crushed into a fiber length of 200 to 1000 μm using a crushing device used for preparing glass powder, such as a stirring blade type crusher.
m.

[0009] The pre-milled glass fibers are packed into a pressure container and subjected to continuous pressure to form a glass powder that can be used as a spacer. The pressurized container is
It is schematically shown as a combination of formworks having the shapes shown in the cross-sectional view of FIG. The material and appearance are not particularly limited as long as the pressurizing container has durability against repeated pressurization of 1000 kg/cm2. In addition, there are no other restrictions on the volume or volume, as long as at least several grams of glass fiber can be processed at one time. Continuous pressurization of pre-milled glass fibers
As shown in FIG. 1, the above-mentioned pre-pulverized glass fibers 4 are packed in the container-like space obtained by combining the side part formwork 2 and the bottom part formwork 3, and the pressurizing part formwork 1 is placed on it, and then the press machine Apply pressure. As the press device used at this time, a generally known press device such as a mechanical type or a hydraulic type can be used. The pressure to be applied and the pressurizing time are determined from the capacity of the press device, the aspect ratio of the intended glass powder, and the cross-sectional area of the pressurizing surface of the pressurizing container. The pressurization time changes depending on the applied pressure, and both control the aspect ratio of the glass powder obtained. For example, in order to obtain an aspect ratio of approximately 2, a pressure of 550 kg/cm2 is applied to the material to be crushed for 5 to 8 minutes.

0010

[Function] In the manufacturing method of the present invention described above, the action of the pressurizing operation on the pre-pulverized glass fibers can be explained as follows.

First, since the pre-pulverized glass fibers have a certain length, it is presumed that they are oriented relatively two-dimensionally, albeit at random, to form overlapping layers. When pressure is applied perpendicularly to it, the pressure is concentrated in the area where the glass fibers overlap, so
Only the overlapping parts will break. Since the length between the overlapping parts is more than twice the radius of the fiber, in principle there is nothing that can be broken shorter than the fiber diameter. Furthermore, by maintaining a constant pressure, the random orientation becomes more dense, and the crushing continues for a certain period of time and is completed at a certain point. In fact, due to this progress of crushing,
The abundance of junk powder having a fiber length of 100 μm or more was reduced to 1% or less, and it became possible to reduce the average aspect ratio of the obtained glass powder to 2 or less. Furthermore, it has become possible to control the average aspect ratio relatively freely by changing the pressurizing conditions.

0012

EXAMPLES Next, the present invention will be explained in more detail with reference to examples. Note that the present invention is not limited to the examples shown below.

Example 1 A bundle of glass fibers with a diameter of 7 μm that was wound around a drum and spun was cut with scissors into fiber lengths of 10 to 20 mm, and then crushed for 10 to 30 minutes using a stirring blade type crusher to obtain fibers. A pre-pulverized product with a length of 200 to 1000 μm is obtained. It is a stainless steel cylindrical pressurizing container (inner diameter 100 mm).
), and a pressure of 450 kg/cm2 was applied to the pre-pulverized product for 5 minutes using a 50 ton class hydraulic press. Measure 50 of the obtained glass powder (counting is done this way because the shape is assumed to be cylindrical with an aspect ratio of 1 or more), and calculate the average fiber length, standard deviation of the average fiber length, maximum and minimum fiber length, The range of fiber length was determined. The results are shown in Figure 2.

Further, the yield of the glass powder obtained at this time was 94% at the stage where the pre-pulverized product was further subjected to a classification operation after pressurization. This value indicates that the yield is 50% when pulverization is performed using a ball mill or the like.
It can be said that this is significantly higher than that of about 60%.

Example 2 When pressurizing with a press device, the pressure was set at 550 kg/cm2.
Except for the above, glass powder was prepared under the same conditions as in Example 1, and the same operations as in Example 1 were conducted to examine various properties, yield, etc. of the obtained glass powder. The results are shown in Figure 3. The yield was 96%.

[0016]

As described above, the method of the present invention is simple because it uses a simple pressurizing container formed by combining a mold and a general press device. However, since it is possible to almost eliminate the presence of fibers with a fiber length of 100 μm or more and fibers with an aspect ratio of 1 or less, which are undesirable for use as spacers for uniformizing the spacing between substrates of liquid crystal display devices, fiber length distribution can be adjusted to suit the purpose. This makes it possible to obtain glass powder, which dramatically improves yield. Therefore, the classification operation is also significantly simplified.

[0017]

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a pressurizing container.

FIG. 2 is a histogram showing the fiber length distribution of the glass powder obtained in Example 1.

FIG. 3 is a histogram showing the fiber length distribution of the glass powder obtained in Example 2.

[Explanation of symbols]

1　Pressure part formwork 2 Side formwork 3 Bottom formwork 4 Glass fiber

Claims (1)

[Claims] Claim 1: Long glass fibers with a fiber length of 200 to 10
1. A method for producing glass powder, which comprises pre-pulverizing the powder to a particle size of 0.00 μm, then filling it in a pressurizing container and continuously pressurizing it.