KR100262695B1 - Method for producing high strength glass bead for dispersion - Google Patents

Abstract

The present invention relates to the production of high strength glass grains for dispersion, which is used to homogeneously disperse powder in high viscosity liquids in the process of making paints, inks, magnetic tapes, chemicals, foods and the like. The production method for enhancing the strength includes a quenching method and an ion exchange method, but the production method is not applicable to the production of dispersion glass beads requiring wear resistance and impact resistance. The present invention is a method that can increase the strength by recrystallizing the glass in the manufacture of the glass beads for dispersion. To this end, a composition design is required to be crystallized when the glass is first heated, and a heat treatment process suitable for this composition is required after the composition is determined. The glass composition found in the present invention comprises 40 to 55 parts by weight of SiO ₂ , 5 to 15 parts by weight of B ₂ O ₃ , 10 to 20 parts by weight of MgO (or CaO or a mixture of MgO and CaO) and 10 to 20 parts by weight of Al ₂ O _3. Part, Na ₂ O (or K ₂ O or a mixture of Na ₂ O and K ₂ O), 5 to 20 parts by weight, ZrO ₂ 2 to 10 parts by weight, the glass crushed product of this composition is mixed with carbon powder, Alternatively, primary heat treatment with rotary kiln may be formed into a sphere and at the same time partially crystallized, followed by second heat treatment to increase crystallinity, thereby producing crystallized dispersion glass grains having superior physical properties than those currently available. have.

Description

Dispersion High Strength Glass Egg Manufacturing Method

The present invention relates to a glass having a composition which is particularly suitable for producing glass beads for dispersion and a method for producing high strength glass beads for dispersion using the same.

Spherical glass pellets are formed from several micrometers in diameter to several millimeters in diameter, with diameters of less than about 1mm used for road marking, and those with diameters of 1mm to 5mm for making paints, inks, magnetic tapes, chemicals, foods, etc. In the process, it is used as a dispersion medium for homogeneously dispersing the powder in a high viscosity liquid.

Dispersion glass pellets are particularly required for wear resistance and impact resistance because they are impacted and sheared by a disk rotating at high speed in a Vessel of a Dispersion Mill. Sometimes.

Such glass grains for dispersing are prepared by mixing glass particles pulverized to an appropriate size and carbon powder, and heating them to the vicinity of the softening point of the glass to spheroidize by the surface tension of the glass. When glass fragments are heated to near the softening temperature, they tend to lose their acute angle due to surface tension and become spherical, but sphericalization is prevented by self-weighting or attachment of softened glass particles. Since carbon has the worst wettability with glass, it becomes possible to shape | mold to a spherical shape by heating the mixture of the carbon component and glass crushed product with poor wettability to the vicinity of a softening point. Carbon film formed on the surface of the spherical glass is removed by washing with weak hydrofluoric acid.

Dispersion glass grains prepared by the above-described process are particularly required to have abrasion resistance and impact resistance as described above. However, since conventional dispersion glass grains have an amorphous structure, the chemical composition is simply changed. Even if it was made, it was difficult to expect improvement of mechanical properties such as wear resistance and impact resistance.

The glass balls made of soda-lime glass, glass balls made of long-fiber E-glass, and glass balls made of borosilicate glass for chemistry are respectively 547kgf / mm2, 580kgf / mm2, 560kgf / mm2, and wear levels are 4.47. %, 3.06%, 3.48%, despite the difference in chemical composition, it can be seen that there is no significant difference in the mechanical properties, the use is limited to the manufacture of low-grade magnetic tape or paint.

Here, the hardness is the Knoop hardness value, and the wear degree is tested by using a sand mill at the conditions of 500g of glass grains, 5g of silicon silicon # 1000 (16㎛), 300ml of distilled water, disk rotation speed 650rpm, rotation time 5hours, It indicates that the weight loss is measured.

On the other hand, there is a method of improving the mechanical properties of the glass by the post-treatment without changing the composition of the glass, the typical examples are the quenching method and the ion exchange method.

The quenching method is a method of increasing the strength by generating residual compressive stress on the glass surface by rapidly cooling the glass after heating it to a predetermined temperature or more. This method has limitations on the shape and thickness of the glass, and is not suitable for dispersing glass grains because the glass thus treated propagates into very small pieces.

The method of increasing the strength by ion exchange involves immersing the glass in the alkali melting tank of a certain component for a long time, thereby changing the alkali component inside the glass and the alkali component (different from the alkali inside the glass) of the melting tank, thereby making very thin ions on the surface. Exchange layer is formed, The compressive stress is generated in the layer to increase the strength. This method is effective in increasing strength, but is not suitable for dispersing applications because the surface is gradually worn out when used in the production of dispersing glass beads due to poor wear resistance.

Therefore, in recent years, zirconia-based ceramic beads are manufactured and used as a substitute for dispersing glass beads, but are only used in specific fields because they are expensive.

The present invention is to solve the above problems, by providing a glass for dispensing glass grains having a composition that can improve the wear resistance and impact resistance by crystallization while maintaining the spherical formability, high-strength crystallized glass beads for low price dispersion The purpose is to be able to manufacture.

Still another object of the present invention is to prepare a high-strength crystallized glass grain for dispersing using the glass-dispersion glass preparation for dispersing according to the present invention. To provide.

The glass for producing the high-strength crystallized glass grains for dispersion according to the present invention for achieving the above object has a composition component of 32 to 63% by weight of SiO ₂ , 4 to 18% by weight of B ₂ O ₃ , and at least one of MgO and CaO. It is characterized by consisting of 8 to 24% by weight of the component, 8 to 24% by weight of Al ₂ O ₃ , 4 to 23% by weight of at least one of Na ₂ O and K ₂ O, and 2 to 13% by weight of ZrO ₂ .

In general, the glass is changed from the amorphous state to the crystalline state when heated for a long time, but heating the currently commercialized plate glass, etc. to make the crystalline state requires a long time heating, and the crystals produced at this time do not contribute to the increase in strength because can not do it. Since the glass for producing a high-strength crystallized glass grain for dispersion having a composition according to the present invention can be easily crystallized and crystallized at the same time, the wear resistance and impact resistance of the glass grain to be produced are significantly improved.

In addition, the high-strength crystallized glass grains manufacturing method according to the present invention, the method for producing a high-strength crystallized glass grains for dispersion using the glass having the above composition, the step of crushing the glass; Mixing the crushed glass with carbon powder and subjecting the mixture to heat treatment at 870 ° C. to 970 ° C. to crystallize and form a sphere; Reheating the heat-treated spherical glass at 860 ℃ to 900 ℃ for 30 minutes to 2 hours to increase the crystallinity; and characterized in that to improve the crystallinity up to about 80%.

Hereinafter, the present invention will be described in detail through examples.

Example 1

43.7 wt% SiO ₂ , 14.6 wt% B ₂ O _3, 14.6 wt% MgO, 14.6 wt% Al ₂ O ₃ , 7.7 wt% Na ₂ O, 4.8 wt% ZrO ₂ , and a glass having a chemical composition were prepared. SiO ₂ is SiO ₂ , MgO is 4MgCO ₃ · Mg (OH) ₂ · 5H ₂ O, Al ₂ O ₃ is Al (OH) ₃ , Na ₂ O is NaCO ₃ , ZrO ₂ is ZrO ₂ , B ₂ O ₃ used B ₂ O ₃ as a starting material. The starting materials are weighed and mixed well using mortar, etc., put in an alumina crucible or platinum crucible, placed in an electric furnace, heated to about 1500 ° C, and melted. Then, the melt is poured on a graphite plate to form a transparent glass. This glass is a glass having a composition found through dozens of experiments, and is a glass having a composition that is well vitrified and crystallized when heated to a temperature near the softening point. After crushing the molten glass to 4mm ~ 5mm size, 50g glass crushed and 50g of carbon powder was mixed well, put in an alumina crucible, put into a box-type electric furnace and heated at about 890 ℃ for 30 minutes to prepare a spherical crystallized opaque white glass.

For reference, the softening point of glass refers to a temperature at which the glass viscosity is 4.5 × 10 7 poise, which varies depending on the glass composition. At this temperature, the glass that can crystallize easily crystallizes. That is, the glass fragments were heat-treated at about 890 ° C. for 30 minutes, thereby making the glass spherical and crystallizing at the same time. The crystallized glass grains thus prepared exhibited physical properties of hardness 630 kgf / mm 2, wear level 2.7%, and compressive strength 30 N / mm 2, and the precipitated crystals were forsterite (MgO · SiO ₂ ) and badelite (ZrO ₂ ) crystals. Compressive strength is a value obtained by measuring the breaking load when a pressure is applied at a speed of 1 mm / min with a compressive strength tester and dividing it by the glass ball cross section.

Since the crystallized glass produced in this way was made into a crystallized state by heating the glass, the crystallized glass is not a state in which only 100% crystalline is present, but a state in which glass and crystalline are mixed. The amount of crystalline depends on the heat treatment temperature and time, and the physical properties also depend on the crystalline mass. The amount of crystalline is called crystallinity, and the crystallinity of the crystallized glass grains produced by the above method is about 30%.

Example 2

44.5 wt% SiO ₂ , 4.9 wt% B ₂ O ₃ , 17.9 wt% MgO, 17.9 wt% Al ₂ O ₃ , 9.9 wt% Na ₂ O, 4.9 wt% ZrO _2. It was prepared in the same manner. After the prepared glass was crushed into 4 ~ 5mm size and mixed with 100 parts by weight of the carbon crushed to 10 parts by weight of carbon fraction and then passed through a rotary kiln, forming and crystallization into a spherical shape occurred simultaneously. Rotary kiln is designed to rotate the pipe-type furnace, and it has the advantage of being able to heat the heated object evenly and continuous production. The manufacturing conditions at this time were a temperature of about 900 ℃, rotation speed 30rpm, tilt angle 4 °. The physical properties of the crystallized glass grains thus prepared were 625 kgf / mm 2, abrasion of 2.9%, and a compressive strength of 30 N / mm 2 with similar properties to those of the first embodiment. However, the rotary kiln used a short manufacturing time and continuous manufacturing was possible.

Example 3

43.3 wt% SiO ₂ , 10.1 wt% B ₂ O ₃ , 16.2 wt% MgO, 16.2 wt% Al ₂ O ₃ , 9.1 wt% Na ₂ O, 5.1 wt% ZrO glass, the same as in Example 1 above. It was prepared by the method, and molding and crystallization using a rotary kiln under the same conditions as in Example 2 (temperature about 900 ℃, rotation speed 300rpm, inclination angle 4 °). The physical properties at this time were 620kgf / mm 2, wear rate 2.8%, and compressive strength 30N / mm 2. In order to further improve the physical properties, the degree of crystallization may be increased. For this purpose, the crystallized glass pellets passed through the rotary kiln were placed in an alumina crucible and heated at 880 ° C. for 2 hours. As a result of the secondary heat treatment, the hardness was improved to 670kgf / mm2, the abrasion was 2.1%, and the compressive strength was 35N / mm2. This was due to the increased amount of crystallinity. The crystallinity was about 80% when the secondary heat treatment was performed and about 30% when the secondary heat treatment was not performed.

According to the glass for producing high-strength crystallized glass grains for dispersion and the high-strength crystallized glass grains manufacturing method using the same according to the present invention configured as described above, crystallization of the glass can be easily performed simultaneously with the spheroidization, and thus the wear resistance and impact resistance of the glass grains produced are effectively As a result, it is possible to replace expensive zirconia-based ceramic beads used as high-definition magnetic tapes or medicines for dispersing media, so that the production cost can be significantly reduced.

Claims (2)

The composition is 32 to 63% by weight of SiO ₂ , 4 to 18% by weight of B ₂ O ₃ , 8 to 24% by weight of at least one of MgO and CaO, 8 to 24% by weight of Al ₂ O ₃ , Na ₂ O and 4 to 23% by weight of at least one component of K ₂ O, and 2 to 13% by weight of ZrO ₂ . A method of producing a high strength crystallized glass grain for dispersion using a glass having a composition as claimed in claim 1, the method comprising: crushing the glass; Mixing the crushed glass with carbon powder and subjecting the mixture to heat treatment at 870 ° C. to 970 ° C. to crystallize and form a sphere; And reheating the heat-treated spherical glass at 860 ° C. to 900 ° C. for 30 minutes to 2 hours, thereby increasing the crystallinity.