JPH0251445A - Glass beads and its production - Google Patents

Abstract

PURPOSE:To enable to adhere glass beads to another material without causing any adverse influences on dimensional accuracy, optical characteristics, etc., by sticking fused fine glass powder having a lower softening point than the main body of the glass beads to the surface of the main body of glass beads. CONSTITUTION:Glass beads utilizable as spacer for controlling cell gaps in a liquid crystal display, or light reflector for road sign, etc., are obtd. by sticking fused fine glass powder (130-350 deg.C softening point, 1-5mum particle size) prepd. by mixing Se, Tl, As, S, etc., with borate glass such as spelter glass to the surface of a main body of hard glass (generally, 700-800 deg.C softening point, 5-20mum particle size) such as silicate glass, borosilicate glass, etc. The glass beads are produced by treating the surface of a main body of the glass beads previously with HF, and pulverizing the glass beads particles with a grinding mixer, and sticking the pulverized glass fused by the heat generated by the grinding to the main body of the glass beads.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to glass beads used in various applications such as spacers for controlling cell gaps in liquid crystal displays (LCDs), light reflectors in road signs, etc.; , regarding its manufacturing method.

[Conventional technology]

Conventionally, beads consisted only of a glass bead body, and when used, the bead body was adhered to another object using an organic adhesive.

[Problem to be solved by the invention]

However, due to the organic adhesive, there is a drawback that troubles tend to occur.

For example, in an LCD, the cell gap is 170±5μm.
Extremely high dimensional accuracy is required, but it is difficult to adhere the organic adhesive extremely thinly and uniformly to the bead body, so the cell gap is caused by the thickness of the organic adhesive. It is easy to fall outside the allowable dimensional error range.

Furthermore, when used as a light reflector, the organic adhesive is easily stained and discolored, so there is a risk that the optical properties will deteriorate in a short period of time.

An object of the present invention is to provide glass beads that can be bonded to other objects without adversely affecting dimensional accuracy or optical properties as described above, and a method for manufacturing the same.

[Means to solve the problem]

The characteristic structure of the glass beads according to the first invention is that fine glass powder having a softening point lower than that of the bead body is thermally fused to the entire surface of the glass bead body, and its functions and effects are as follows. That's right.

[For production]

In other words, when adhering to another object, if the beads themselves are heated to a temperature that hardly softens and only the fine glass powder, which has a lower softening point, is sufficiently softened, and then cooled,
The fine glass powder softened by heating adheres to other objects, allowing the bead body to be fixed to other objects.

If it is necessary to suppress the negative effect of adhesion on dimensional accuracy, such as in the case of the above-mentioned LCD, it is sufficient to adjust the particle size of the fine glass powder and heat-fuse it to the bead body so that it has an almost monolayer structure. This is easy at today's technology level and can reliably maintain a predetermined dimensional accuracy.

In addition, when it is necessary to suppress the negative effects of adhesion on optical properties, such as with the light reflector mentioned above, we use fine glass powder that maintains the same good optical properties as the beads themselves, so they can be used reliably over a long period of time. can maintain good optical properties.

〔Effect of the invention〕

As a result, it is possible to bond to other objects without adversely affecting the dimensional accuracy or optical properties required depending on the application.
We are now able to provide glass beads that are much more convenient and can produce high-quality products at a high yield.

[Means to solve the problem]

The characteristic means of the glass bead manufacturing method according to the second invention is that a glass bead body and a glass powder having a lower mechanical strength and softening point than the bead body are rotated at high speed in a dry grinding and mixing device. is pressed against the inner circumferential surface of the casing by centrifugal force, and only the glass powder particles are pulverized into a raw material layer formed by the pressing by compressive force and shear force by the grinding pieces that rotate relative to the casing, and the The raw materials are stirred and mixed by the action of the pick pieces, and the glass fine powder generated as the glass powder granules are finely pulverized is
The purpose is to thermally weld the entire surface of the bead body by the action of the softened part due to the heat generated by the grinding.
The effects are as follows.

[For production]

In other words, the bead bodies and glass powder are pressed against the inner peripheral surface of a casing rotating at high speed by centrifugal force, and the crushed pieces are pressed against the raw material layer where the movement of the beads and glass powder is restricted by centrifugal force. When the grinding action is performed by relative rotation, the grinding pieces can grind the raw material layer strongly, reliably, and efficiently.

Since the mechanical strength of the glass powder granule is lower than that of the bead body, the bead body is crushed and acts like a grinding ball in a ball mill, and only the glass powder granule is sufficiently and efficiently pulverized. Can be crushed.

Further, since the raw material layer is stirred and mixed by scraping that rotates relative to the raw material layer, the glass powder can be evenly pulverized.

Moreover, since the softening point of the glass powder granules is lower than that of the beads themselves, the heat generated during grinding hardly softens the beads itself, making it possible to sufficiently soften only the glass powder at the part where it comes in contact with the beads itself. By the action of the softened portion, the glass fine powder can be thermally welded to the entire surface of the bead body, and the glass beads according to the first invention can be manufactured.

Incidentally, it is also possible to prepare glass fine powder in advance, heat the bead body below its softening point and above the softening point of the fine powder, and bring the glass fine powder into contact with the heated bead body to thermally weld it to the bead body. However, according to the second invention, the work is troublesome and takes a long time because it requires a fine grinding process, a heating process, and a mixing process, and there are problems in terms of work efficiency and manufacturing cost. Grinding, mixing, and heat welding can be performed all at once in one process, which can sufficiently improve work efficiency and reduce manufacturing costs.

〔Effect of the invention〕

As a result, the useful glass beads according to the first invention can be easily mass-produced and provided at a sufficiently low cost.

〔Example〕

Next, examples will be shown.

As shown in Figure 1, the bead body is made of glass and has a spherical shape (A
) is thermally welded to the entire surface of the glass powder (B), and the glass powder (B) is softened by heating to form glass beads that are used by adhering to other objects.

The bead body (A) is made of a suitable silicate glass such as potash glass containing a large amount of silicic anhydride, or
Made of materials with high mechanical strength, hardness, and softening point, such as hard glass made of suitable borosilicate glass, etc.
Its softening point is generally 700 to 800°C or higher, and its particle size is generally about 5 to 20 μm.

The glass fine powder (B) has mechanical strength, hardness, Made of material with a low softening point,
Its softening point is generally about 130 to 350°C, and its particle size is generally about 1 to 5 μm.

Next, a method for manufacturing the above glass beads will be explained.

(b) Surface-treating the spherical glass beads (A) with diameters within a predetermined range with hydrofluoric acid to make the surface rough so that the glass fine powder (B) can be easily thermally welded to the surface. Perform pre-treatment and treatment.

(b) The pretreated bead body (A) and the glass powder granules, which are the raw materials for the glass fine powder (B), are mixed in an appropriate ratio.
For example, about 5 to 10% by weight is supplied to a soft grinding mixer.

(c) Activate the grinding and mixing device to pulverize only the glass powder without pulverizing the bead bodies (A), mix the bead bodies (A) and the glass fine powder (B), and The main body (A) is hardly softened, and only the glass fine powder (B) is sufficiently softened by the heat generated by the grinding.
Glass fine powder (B) is transferred to the bead body (A) by the action of the softened part.
heat weld the entire surface of the

The above-described grinding and mixing device will now be described in detail with reference to FIGS. 2 and 3.

A bottomed cylindrical casing (4) forming a processing chamber (3) is concentrically attached to the upper end of a vertical rotating shaft (2) attached to a base (1), and an electric motor (5a) and a variable speed Machine (5b
) etc. is interlocked with the lower end of the rotating shaft (2), and the casing (4) is rotated at high speed so that the raw material inside is pressed against the inner circumferential surface (4a) of the casing by centrifugal force. The rotational speed of the casing (4) can be adjusted so as to obtain an appropriate centrifugal force depending on the properties of the raw material.

The casing (4) is surrounded by a cover (7), a fan (12) is connected to the bottom of the casing (4), and the cover (7) is surrounded by a fan (12).
) The outside air is sucked in through an intake port (13) formed in the cover (7), and the outside air is discharged through an exhaust pipe (10) connected to the cover (7).

A support (8b) having a conical portion (8C) formed at the upper center thereof is provided in the casing (4) while being fixed to the upper end of the rotating shaft (2) and the same rotating shaft (8a). .

A grinding piece (9a) that compresses and shears the raw material in cooperation with the inner circumferential surface (4a) of the casing, and a scraping piece (9b) that stirs, mixes and disperses the raw material are placed in an appropriate direction in the rotational direction of the casing (4). They are arranged at intervals and attached to the tip of the support (8a) and placed in the processing chamber (3).

The grinding piece (9a) has an inclined surface formed so that the gap with the casing (4) becomes narrower in the direction of rotation of the casing (4), and the scraping piece (9b) is attached to the casing (4). ) is formed in a wedge-like or comb-like shape so that the gap with the casing (4) becomes wider in the direction of rotation of the casing (4), and its working surface gradually becomes wider.

The rotating shaft (8a) is interlocked with the drive device (5), and the grinding pieces (9a) and the scraping pieces (9b) are rotated relative to the casing (4) at a constant speed difference, thereby removing the grinding pieces (9a). The structure is such that fine pulverization by the scraper and stirring and mixing by the scraping piece (9b) are performed.

In the rotating shaft (8a), a support (8b), a grinding piece (9a)
, a passage (27) is formed through which a heating or cooling medium flows into the scraping piece (9b), and a rotary joint (2
4) connects the passageway (27) to the medium storage tank (26).

A path (6) is formed in the center of the cover (7) by attaching a pipe (14) for supplying the raw material from the feeder (19) toward the conical portion (8C) of the support (8b). A blower (18cm
) is connected to the path (6), and a jacket (25) is provided around the cover (7) to pass the heating or cooling medium from the tank (26).

Connect the upper part (7a) of the cover (7) to the pipe (10), (1
4) It is configured to be removably attached to the glass beads and to enable recovery of the manufactured glass beads.

In short, the casing (4) is rotated at high speed, and the bead body and glass powder from the feeder (19) are pressed against the inner peripheral surface (4a) of the casing by centrifugal force, and the casing is applied to the raw material layer formed by the pressing. A grinding piece (9a) and a scraping piece (9b) which rotate relative to each other are applied to (4), and the grinding piece (9a) finely pulverizes only the glass powder particles with low mechanical strength, and the scraping piece In (9b), the raw materials are stirred and mixed, and the glass fine powder is softened by the heat generated by the grinding and is thermally welded to the entire surface of the bead body.

At this time, the temperature of the temperature regulating gas sent into the casing (4) by the blower (18) and the temperature of the medium sent to the jacket (25) are set appropriately in accordance with the softening point of the bead body and the glass fine powder, Only the fine glass powder is sufficiently softened without softening the beads themselves.

[Another example]

Next, another embodiment will be described.

Bead bodies (A) and glass fine powder (B) can be selected appropriately in terms of composition, mechanical strength, softening point, particle size, etc., and there is a large difference in the correlation between mechanical strength, softening point, and particle size. However, the difference can be selected appropriately.

The specific means in the manufacturing method can be changed as appropriate, and for example, the means listed in (a) to (2) below can be used.

(b) The surface treatment of the bead body (A) with hydrofluoric acid is omitted.

(b) Bead body (A) with a suitable substance other than hydrofluoric acid.
) surface treatment.

(/1) Glass fine powder (
B), and the glass fine powder (B) is brought into contact with the bead body (A).
) by heat welding to the bead body (A).
Fine glass powder (B) is thermally welded onto the entire surface of the glass.

(d) Use the grinding and mixing device by appropriately changing its specific configuration.

Glass beads can be used for any purpose; for example, when sealing is required, such as when joining a lid to a glass container,
Alternatively, it is also useful when it is necessary to firmly bond glasses together.

Note that although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structures and methods shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a conceptual diagram of glass beads, FIG. 2 is a conceptual diagram of a grinding and mixing device, and FIG.
It is a view taken along the line ■-■ in the figure. (A)...Bead body, (B)...Fine glass powder, (4)...Casing, (4a)...
...Inner peripheral surface of casing, (9a)...Grinded piece, (9b)...Scraped piece.

Claims (1)

[Claims] 1. Glass beads in which glass fine powder (B) having a softening point lower than that of the bead body (A) is thermally fused to the entire surface of the glass bead body (A). 2. Claim 1, wherein the bead body (A) has a particle size of 5 to 20 μm, and the glass fine powder (B) has a particle size of 1 to 5 μm.
Glass beads as described. 3. The inner peripheral surface of the casing (4) that rotates at high speed in a dry grinding and mixing device (
4a) by centrifugal force, and only the glass powder particles are finely pulverized into the raw material layer formed by the pressing by compressive force and shear force by the grinding pieces (9a) rotating relative to the casing (4). At the same time, the raw materials are stirred and mixed by the action of the scraping piece (9b), and the glass fine powder generated as a result of the pulverization of the glass powder granules is softened by the action of the softened part due to the heat generated by the grinding. A method of manufacturing glass beads that is heat-welded to the entire surface. 4. The method for producing glass beads according to claim 3, wherein the bead body is surface-treated with hydrofluoric acid to roughen the surface prior to the treatment by the grinding and mixing device.