JPH0218338A - Crystallized glass material and its production - Google Patents

Abstract

PURPOSE:To eliminate the bubbles and pores in glass by subjecting a powder mixture composed of low softening point glass powder specified in SiO2, CaO, etc., and high softening point glass powder contg. quartz to pressurized molding and heating under prescribed conditions, thereby crystallizing the mixture. CONSTITUTION:The low softening point glass powder consisting, by weight %, of 65-80% SiO2, 5-10% CaO, 10-20% Na2O+K2O and 2-8% MgO is prepd. The high softening point glass powder is prepd. from the high softening point fusible glass powder consisting of 65-80% SiO2, <=25% Al2O3, and 5-15% Na2O+ K2O is prepd. and quartz powder. This high softening point glass powder and the above-mentioned low softening point glass powder are mixed. The powder mixture is then subjected to the pressurized molding at a prescribed temp. The molding fused with the low softening point glass around the high softening point glass is obtd. This molding is heated to the temp. within the prescribed temp. range and is crystallized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a crystallized glass material used as a building material, wall material, etc., and a method for manufacturing the same.

(Prior Art) Conventionally, as disclosed in Japanese Unexamined Patent Application Publication No. 48-78217, a suitable method for manufacturing crystallized glass materials involves accumulating glass powder particles of a specific composition in a fire-resistant mold, There is a method (hereinafter referred to as the accumulation method) in which the entire mold is heated to a temperature higher than the glass softening point to soften and fuse the glass powder and crystallize it.

According to this method, a pattern-forming glass powder containing an appropriate coloring component is added to a base-forming glass powder, which is accumulated and heat-treated to form an arbitrary color pattern. It has the advantage that crystallized glass material can be easily obtained.

(Problem to be solved by the invention) However, according to the accumulation method, the glass powder particles are softened and fused almost simultaneously during heat treatment, so the air existing between the powder particles is trapped in the softened and fused body. , and remain as bubbles. The smaller the particles of the powder or granular material, the more these bubbles are generated, and they aggregate together to form large pores.

Bubbles and pores in the softened and fused body expand during heat treatment, which causes blisters and cracks in the crystallized glass material. In addition, crystallized glass materials are often used as plate materials after the surface is polished smooth, so if there are many air bubbles or pores in the glass material, dents due to the air bubbles or pores may appear on the surface after polishing. A large number of defects are exposed, resulting in product defects. In addition, air bubbles and pores cannot bear the stress acting on the member, which causes a decrease in strength.

In addition, since the accumulation method softens and crystallizes the aggregate of glass powder particles, it is necessary to prevent the aggregate from deforming due to softening during heat treatment, and for this reason, the entire mold is subjected to heat treatment. There must be. That is, the process from the accumulation of the glass powder to the completion of the heat treatment must be handled on a mold-by-molding mold basis, resulting in complicated handling and poor productivity. Furthermore, a large number of expensive heat-resistant molds must be prepared, which increases equipment costs.

The present invention was made in view of the above problems, and includes a crystallized glass material that can easily be colored and patterned and can suppress the inclusion of air bubbles as much as possible, and a crystallized glass material that does not require the handling of each mold. The purpose is to provide a method for manufacturing materials.

(Means for Solving the Problems) In the crystallized glass material of the present invention, which has been made to achieve the above object, a low softening point glass powder and a high softening point glass powder are bonded together after softening and fusing of the low softening point glass powder. A crystallized glass material formed by fusion and integration and crystallization, wherein the main component of the low softening point glass powder is 5in2 by weight:
65-80%, CaO: 5-10%NatO+
KzO: 10-20%, MgO 22-8%, and the main component of the high softening point glass powder is SiO□:
65-80%, Al2O3: 25% or less NaxO+K
The structure of the invention is composed of a high softening point melting glass powder having a tO of 5 to 15% and a quartz glass powder.

In addition, as a preferred manufacturing method, the main components are Stow: 65-80%, CaO: 5-10% by weight.
%NatO+ KzO: 10-20%, MgO:
Low softening point glass powder which is 2-8% and main component is wt%
SiO□: 65-80%, N2O2: 25% or less N
a, a mixed powder of a high softening point glass powder consisting of a high softening point fusible glass powder having 5 to 15% of zo 7 to O+ and a high softening point glass powder consisting of a quartz glass powder at a temperature equal to or higher than the softening point of the low softening point glass powder and having low softening temperature. Pressure molding is performed at a temperature below the crystallization start temperature of point glass powder to obtain a glass powder molded body in which low softening point glass powder is softened and adhered or fused around high softening point glass powder. The structure of the invention is to perform crystallization by heating to a temperature higher than the crystallization start temperature of the softening point glass powder and lower than the softening point of the high softening point fusion glass powder.

(Function) The crystallized glass material of the present invention has a low softening point glass powder and a high softening point glass powder that are fused and crystallized after softening and fusing the low softening point glass powder. When the softening point glass powders are softened and fused together, the air existing between the glass powders is discharged to the outside of the glass powder along the particle surface of the unsoftened high softening point glass powder. Therefore, it is difficult for air bubbles to remain in the fused body of both glass powders, and as a result,
It is assumed that air bubbles and pores are eliminated as much as possible in the crystallized glass material of the present invention.

The low softening point glass powder used in the present invention has the composition of ordinary soda lime glass, while the high softening point fusible glass powder, which is the main component of the high softening point glass powder, has a 5iOz content of low softening point glass. Since it is in the same range as powder,
From a low softening point glass powder that is softened and fused even at a temperature above the softening edge of the low softening point glass powder and below the crystallization start temperature of the same powder, to an unsoftened high softening point fusion glass powder, Na, etc. Diffusion migration of network-modifying ions is likely to occur. As a result, the softening temperature decreases in the component diffusion region of the high softening point fusible glass powder, and the softened and fused low softening point glass powder and high softening point glass powder are easily fused and integrated.

The reasons for limiting the main components of the low softening point and high softening point fusible glass powders are shown below. The unit is weight %.

A. Low softening point glass powder SiO□: 65 to 80% If it is less than 65%, SiO□ crystals are difficult to precipitate, but on the other hand, if it is 80%
If it exceeds 100%, the softening point becomes high and high temperature heating is required in heat treatment, which is not preferable in terms of manufacturing.

CaO: 5-10% If it is less than 5%, the softening point will be high, while if it exceeds 10%, SiO□ crystals will be difficult to precipitate.

NazO+MgO: 10-20% If it is less than 10%, the softening point will be high, while if it exceeds 20%, Si0g crystals will be difficult to precipitate.

MgO: 2 to 8% If it is less than 2%, Si0g crystals will grow too quickly and crystallization will start before densification by sufficient softening and fusion is achieved. On the other hand, if it exceeds 8%, it becomes difficult for 5in2 crystals to precipitate.

B. High softening point fusible glass powder 5iOt: 65-80% At less than 65%, SiO□ crystals are difficult to precipitate, while at 80%
If it exceeds this, the softening point will become too high, making it difficult for the components to diffuse with the low softening point glass powder.

N, o,: 25% or less N2O3 has the effect of increasing the glass softening point, but 2
If it exceeds 5%, SiO□ crystals will precipitate.

Na2O+K2O: 5 to 15% If it is less than 5%, the softening point becomes too high and diffusion of the components with the low softening point glass powder becomes difficult. On the other hand, if it exceeds 15%, the softening point will become too low, and there is a possibility that the softening temperature will fall below the crystallization start temperature of the low softening point glass powder.

The main components of the low softening point and high softening point fusible glass powders are as described above, but in addition, coloring agents and other components commonly added in the glass industry for adjusting physical properties may be included.

High softening point glass powder includes quartz glass powder. Quartz glass powder is difficult to fuse with low softening point glass powder due to diffusion of components, but it has a coefficient of linear expansion of 0.3 to 0.
5 Xl0-b/''C, and the coefficient of linear expansion is about one order of magnitude smaller than that of low softening point glass powder.

Therefore, by adding the quartz glass powder, compressive stress can be left in the crystallized glass material during the cooling process after crystallization, and the crystallized glass material can be strengthened. Furthermore, since the coefficient of thermal expansion of the crystallized glass material itself can be lowered, it has excellent thermal shock resistance. As mentioned above, silica glass powder is difficult to fuse with low softening point glass powder, and adding a large amount will result in a decrease in strength and an increase in water absorption. It is preferable to limit the amount to 30% by weight or less based on the total amount. However, in order to obtain an effective reinforcing effect due to compressive residual stress, it is desirable to add 1% by weight or more.

Further, according to the manufacturing method of the present invention, the mixed powder of the high softening point glass powder and the low softening point glass powder is prepared at a temperature higher than the softening point of the low softening point glass powder and lower than the crystallization start temperature of the low softening point glass powder. Since the pressure is applied at a temperature of , the low softening point glass powder is softened and fused in a state adjacent to the high softening point glass powder, and is attached to the high softening point glass powder. At this time, the air existing between the glass powders is discharged to the outside through the surface of the unsoftened high softening point glass powders. In addition, when the heating temperature is relatively high within the above temperature range, components diffuse and migrate between the softened and fused portion of the low softening point glass powder and the surface of the high softening point fused glass powder to which the portion is attached. , the component diffusion region is softened, and the high softening point fusible glass powder and the softened and fusible portion of the low softening point glass powder are fused together.

In this way, the mixed powder of the low softening point glass powder and the high softening point glass powder is adhered or fused to form a dense glass powder compact. This glass powder compact has sufficient strength required for handling and can be handled alone.

Next, the glass powder molded body is heated to a temperature above the crystallization start temperature of the low softening point glass powder and below the softening point of the high softening point fusible glass powder, so that the low softening point glass powder and Fusion with the high softening point melting glass powder progresses, and the softened and fused portion expands. In addition, the high softening point fusible glass powder and quartz glass powder whose interior is unsoftened serve as aggregates, and the low softening point glass powders are softened and fused together while maintaining the shape of the compact. Crystals precipitate and grow in the softened and fused portions of the component diffusion region and the high softening point fused glass powder.

Therefore, it is not necessary to subject the glass powder molded body to the crystallization heat treatment together with the mold required for pressure molding of the mixed powder, and the glass powder molded body can be handled independently, making the work easy and excellent in productivity. Further, there is no need to prepare a large number of expensive heat-resistant molds.

After the crystallization heat treatment, it is cooled to room temperature, but during this time, the quartz glass powder part has a smaller coefficient of thermal expansion than the base, so
Compressive stress remains in the crystallized glass, strengthening the material.

(Example) Hereinafter, the crystallized glass material of the present invention will be explained along with its manufacturing method.

First, the glass powder used in the present invention will be explained.

The main components of the low softening point glass powder and the high softening point fusible glass powder are as described above, but for the latter, it is desirable to adjust the components so that the glass softening point is about 800°C or higher. . The low softening point glass powder has the composition of normal soda lime glass and has a softening point of 600 to 750.
This is because the crystallization initiation temperature in °C1 is about 800''C or lower.

Glass powder can be obtained by melting glass of the desired composition, pulverizing it, and then crushing it, but soda lime glass current (waste glass) can be used as a raw material for low softening point glass powder. Furthermore, for the high softening point fusible glass powder, crushed pearlite can be used. Perlite is N20
．． It has a softening point of about 900°C or higher, is supplied in large quantities to the market as aggregate, etc., is easily available, and has excellent economic efficiency.

Naturally produced pearlite has a layered structure and has slightly different properties than artificially produced glass even though it has the same components, and in the present invention, the term "glass" includes such things. Perlite contains 3 to 5% water between the eyebrows, but it is dehydrated during heat treatment. Additionally, it has a higher softening point compared to the same ingredient as Nigarasu.

Regarding the particle size of low softening point and high softening point glass powders, the smaller the particle size and the larger the amount, the easier the softening and fusion of low softening point glass powders with each other, and the easier the fusion with high softening point glass powder. This facilitates adhesion, and in turn promotes densification and crystallization of the glass powder compact. For this reason, it is desirable that the particle size of the glass powder is such that 80% or more (preferably 90% or more) of the glass powder has a particle size of 200 mesh or less.

Incidentally, when the particle size of the quartz glass powder becomes coarse, it becomes easy to be cranked during the cooling process after heat treatment due to the difference in thermal expansion with the base, so it is preferable to use one having a mesh size of 100 mesh or less.

In the mixed powder of the low softening point glass powder and the high softening point glass powder containing quartz glass powder, it is desirable that the blending ratio of both powders is such that the low softening point glass powder accounts for 20 to 90% by weight. If it is less than 20%, insufficient softening and fusing with the high softening point fusible glass powder and insufficient densification of the glass powder compact result.

Furthermore, the amount of crystals is insufficient, resulting in a decrease in strength. On the other hand, 90%
If it exceeds this value, the shape retention of the glass powder molded body during heat treatment will be insufficient, and the effect of discharging air bubbles in the molded body will be insufficient.

It is possible to use a colored glass powder having the same components as the low softening point glass powder and/or the high softening point melting glass powder, except that the colored component is contained in part or all of the glass powder. By using a mixed powder of such a low softening point colored glass powder and a high softening point colored glass powder (hereinafter referred to as colored mixed powder), or by using a combination of multiple types thereof, various colored crystallizations can be achieved. Glass materials and crystallized glass materials with colored patterns can be obtained.

Additionally, an additive mixed powder is obtained by adding and mixing a metal oxide coloring agent (usually a fine powder of 200 mesh or less is used) to a mixed powder of a low softening point glass powder and a high softening point glass powder that does not contain a coloring component. It is also possible to produce colored crystallized glass materials by using. The colorant is added within a range that does not reduce the physical properties (particularly strength) required of the crystallized glass material, and an example of the amount added is shown below. The amount added is based on the added mixed powder, and the unit is weight%.
It is.

CrzOi+ CuO+ Mn0z'-'-' 1%
Below Coo -3% or below FeO+ Fe, 04. Peg'5 - 40% or less In addition, to form a spotted colored pattern, if you use coarse grained low softening point and/or high softening point fusible glass powder of 4 to 100 meshes, Regarding the amount of colored glass powder to be used, as mentioned above, it is desirable that the glass powder should account for 80% or more of powder of 200 mesh or less.
It is preferable to limit the amount to 20% or less based on the total amount of powder.

In order to produce the crystallized glass material of the present invention, first, a glass powder molded body is molded using the mixed powder described above (hereinafter, the term "mixed powder" includes colored mixed powder and additive mixed powder).

As shown in FIG. 1, a method for forming a glass powder compact is, for example, a method in which a mixed powder 2 is put into a mold 1 (mold), an upper mold 3 is fitted therein, and the molded body is press-molded at room temperature ( Room temperature pressure molding method), the mixed powder 2 is heated at a temperature higher than the softening point of the low softening point glass powder and lower than the crystallization start temperature of the same powder (hereinafter referred to as densification temperature), and pressure molded. There is a method (high temperature pressure molding method). After molding, the glass powder molded body is taken out from the mold, placed in a heat treatment furnace, and subjected to heat treatment as described below. Note that after molding, heat treatment can be performed while the mold is in the mold, but handling becomes complicated and the molded shape needs to have good heat resistance.

When using the room temperature press molding method, the powders are usually pressurized to such an extent that they contact each other (relative density is preferably 50% or more), and handling strength (bending strength 10 kgf/a1) is applied.
The above is desirable. ) and to improve moldability, a few percent of binder is added to the mixed powder.

When obtaining a large molded body, it is essential to add a binder to ensure strength. Organic binders, such as polyvinyl alcohol (PVA), are usually used.

The glass powder compact formed under pressure at room temperature is subjected to heat treatment as shown by the solid line in FIG. Section C is a drying section for eliminating moisture and organic solvent in the binder.

Section b is a binder removal section, and by maintaining the temperature at 300 to 400°C, the polymer component of the binder is decomposed, gasified, and discharged out of the molded body. If the binder remains in the molded article, it may cause blistering or cracking in the subsequent heat treatment section or deteriorate the physical properties of the product, so it is necessary to actively remove the binder. Section C is a densification section, in which the low softening point glass powders soften and fuse together at the densification temperature (usually 600 to 800°C), and also adhere or fuse to the high softening point glass powder, and further rise in temperature. As a result, fusion progresses. In the same figure, C is shown as a continuous temperature increase state, but it may be held at a certain temperature in the densification temperature range to sufficiently soften and fuse, and then move on to the next section. is the crystallization zone, which is at a temperature above the crystallization start temperature of the low softening point glass powder and below the softening point of the high softening point fusible glass powder (hereinafter referred to as crystallization temperature, usually 800 to 1000'C). Hold it to crystallize the softened and fused portion. Note that crystallization may be performed at a temperature equal to or higher than the softening point of the high softening point fusible glass powder, but in this case, it is necessary to heat-treat the glass powder molded body together with the mold to prevent deformation. Section C is a slow cooling section.

According to the high-temperature pressure molding method, the glass powder in the mold is pressurized at the densification temperature, so the low softening point glass powders soften and fuse together and adhere to the high softening point glass powder without using any binder. Relative density of 50% or more, bending strength L Okg f /
A glass powder compact having a cff of 1 or more can be easily obtained. In this case, it is sufficient to rapidly heat the material to the pressure molding temperature, and the molding time may be very short (about several minutes).

After pressure molding, the glass powder molded body is taken out from the mold and promptly charged into a heat treatment furnace. The subsequent heat treatment can be performed by rapid heating to the densification temperature of , and the heating in the a % b interval required in the room temperature pressing method can be omitted. Since the awb section usually takes a long time, the high temperature press molding method has extremely high productivity. For example, to obtain a plate-shaped crystallized glass material 700 cm square and 20 to 30 mm thick, the a-b section is 70 to 80 mm thick.
Even if the glass powder molded body is dried in advance before heat treatment, it takes about 40 to 40 hours to remove the binder.
Requires heating for 50 hours.

In the high-temperature pressure molding method, the mixed powder is heated and molded by putting the mixed powder at room temperature into a mold at room temperature, heating the mold together to the desired temperature, and then pressing at a pressure of 5 kgf/cr1 or more. A common method is molding. In this case, the mold is usually heated by a heater provided in the mold or by placing the mold together in a heating furnace. In addition, various heat forming methods can be used. For example, ■ A method in which a mixed powder heated to a predetermined temperature is placed in a mold at room temperature and pressure-molded ■ A mixed powder at room temperature is placed in a mold heated to a predetermined temperature and heated by the heat held by the mold. Pressure molding method■ There is a method of pressure molding by placing room temperature mixed powder in a room temperature mold and heating only the surface thereof to a predetermined temperature by electric radiation, infrared radiation, direct heating with a burner, etc. Further, it is also possible to heat the mixed powder at room temperature to a predetermined temperature using a pair of heating rolls and to press-form it. Note that the term "normal temperature" here includes a state where the glass powder is preheated to a temperature lower than the softening temperature of the low softening point glass powder.

In order to prevent the low softening point glass powder from sticking, the mold should preferably be coated with a coating agent such as zircon sand or graphite, or ceramic powder, or coated with a ceramic sheet. .

Next, specific examples will be described.

(1) Various glass powders having the composition and particle size shown in Table 1 were prepared. In addition, cullet is used as a raw material for low softening point glass powder.
Pearlite was used as a raw material for high softening point fusion glass powder.

(Next page) Table 1 (2) A mixed powder was prepared from the glass powders in Table 1 A to C according to the formulations in Table 2, and a plate of 350 x 350 mm (thickness 20M) was prepared under the high-temperature pressing conditions in the same table. A shaped glass powder compact was produced. In the same table, NcLl is (3) After high-temperature pressure molding, the glass powder molded bodies of Nα1 and Nα2 are taken out from the molding mold, inserted into a heating furnace maintained at 600°C, and soaked at 30°C. /Hr to 900°C, held for 4 hours to achieve crystallization, and then slowly cooled.

(4)゛ The mechanical properties of the obtained crystallized glass material were
Shown in the table.

Table 3 According to Table 3, Nα2 according to the example is Nα2 according to the comparative example
A remarkable improvement in bending strength was observed compared to α1. It was also confirmed that the coefficient of linear expansion at floor 2 was smaller than Nα1. Therefore, it is known that the crystallized glass material of the example is strong against thermal shock. In addition, 100-200°C
The reason why the coefficient of linear expansion is large is that volume expansion occurs as the 5iOz crystal transforms. Also,
For both No. 1 and Nα2, there were no pores or bubbles observed with the naked eye in the tissues.

(Effects of the Invention) As explained above, in the crystallized glass material of the present invention, the low softening point glass powder and the high softening point glass powder are fused and integrated after the low softening point glass powder is softened and fused, and crystallized. Therefore, when the low softening point glass powders are softened and fused together, the air that existed between the glass powders is discharged to the outside along the unsoftened high softening point glass powder surface, creating pores and bubbles in the structure. It becomes almost non-existent.

In addition, the low softening point and high softening point fusible glass powders of the specific composition used in the present invention are easily available, and it is easy to ensure a softening temperature difference, and they are easy to fuse with each other, increasing productivity.
Excellent economy. Further, by using the desired colored glass powder or coloring agent, a crystallized glass material having an arbitrary color pattern can be easily obtained.

Furthermore, since quartz glass powder is added to the high softening point glass powder, it is possible to leave compressive stress in the crystallized glass material, improving strength, and coupled with a decrease in thermal expansion coefficient, it improves heat resistance. Impact resistance can be improved.

On the other hand, according to the manufacturing method of the present invention, it is possible to easily obtain a strong glass powder molded body that can be handled independently without using any binder. No binder is required, resulting in extremely high productivity. Moreover, since the glass powder molded body is crystallized at a temperature below the softening temperature of the high softening point fusible glass powder, the high softening point fusible glass powder and quartz glass powder whose internal parts are not softened function as aggregates. Even during high-temperature crystallization heat treatment, the shape of the molded body is maintained and no deformation occurs. Therefore, there is no need to subject the entire mold to heat treatment.
It is possible to improve productivity and reduce equipment costs.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a mold showing the procedure for forming a glass powder compact, and FIG. 2 is a heat treatment diagram showing an example of the heat treatment of the crystallized glass material of the present invention.

Claims (2)

[Claims] (1) A crystallized glass material obtained by fusing and crystallizing a low softening point glass powder and a high softening point glass powder after softening and fusing the low softening point glass powder, wherein the low softening point glass powder is Main components are SiO_2: 65-80% by weight, C
aO: 5-10% Na_2O+K_2O: 10-20%
, MgO: 2 to 8%, and the main component of the high softening point glass powder is SiO_2 in weight%.
: 65-80%, Al_2O_3: 25% or less Na_2
A crystallized glass material comprising a high softening point melting glass powder having an O+K_2O content of 5 to 15% and a quartz glass powder. (2) Main components are SiO_2: 65-80%, CaO: 5-10% Na_
A low softening glass powder whose main components are SiO_2: 65-80% and Al_2O_3: 25% or less Na_2O+K_2O: 5-15% by weight. A mixed powder of a high softening point glass powder consisting of a point melting glass powder and a quartz glass powder is pressed at a temperature above the softening point of the low softening point glass powder and below the crystallization start temperature of the low softening point glass powder. Molding is performed to obtain a glass powder molded body in which a low softening point glass powder is softened and adhered or fused around a high softening point glass powder, and the molded body is heated to a temperature equal to or higher than the crystallization start temperature of the low softening point glass powder and is highly softened. A method for producing a crystallized glass material, which comprises heating to a temperature below the softening point of point-fusible glass powder to crystallize it.