JPS61168552A - Wear-resistant crystallized glass bead - Google Patents

Abstract

PURPOSE:To develop wear-resistant crystallized glass beads having improved mechanical strength free from elution of alkali component, by heat-treating glass beads comprising B2O3, Fe2O3, BaO, SiO2, Al2O3, and ZrO2, etc., as main components under specific conditions. CONSTITUTION:Glass comprising 20-40wt% B2O3, 20-45wt% Fe2O3, 30-55wt% BaO, 0.01-5wt% SiO2+Al2O3, and 0.01-5wt% ZnO2 is melted at 1,200-1,300 deg.C, molten glass is dropped on a disc rotating at high speed, scattered by centrifugal force, to give glass beads formed into spheres by surface tension. These glass beads are heat-treated at 500-550 deg.C for 3-5hr, further at 800-850 deg.C for 5-7hr, to give crystallized glass beads comprising BaO.6Fe2O3 and BaO.B2O3 as main constituent oxides. Since the glass beads contain no alkali component, glass beads having no elution of alkali in use, high mechanical strength and improved wear resistance can be produced.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention has excellent alkali elution resistance, mechanical strength, and abrasion resistance, and is particularly suitable for grinding with a molecular machine such as a sand mill.
Regarding wear-resistant crystallized glass beads suitable as a dispersion accelerator [Technical background of the invention and its problems] Conventionally, powders such as pigments and magnetic materials for magnetic tapes have been made into sludge particles or homogeneously mixed in a solvent. It was dispersed into

For this purpose, a decomposition machine such as a sand mill using glass beads is used. This sand mill uses stirring blades that rotate at high speed to stir the raw material powder, glass beads, and dispersant housed in a container into a high-speed flow, and the particles collide and rub against each other to create a homogeneous flow. It is something that disperses. The glass beads used in this case are generally made by crushing soda lime glass to a predetermined particle size ζ and heating it to form it into a spherical shape. This type of glass beads has low water resistance, a large amount of alkali elution, and changes in pH during dispersion, which affects the chemical and physical properties of the product.

In addition, because the mechanical strength is poor and the abrasion rate is fast, fine glass fragments due to crushing and abrasion are mixed into the raw material powder, significantly reducing the quality of the product. Furthermore, since the glass beads wear out in a short period of time, the glass beads must be replaced frequently to maintain a desired particle size.

Moreover, recently there has been a trend toward higher speed rotation in order to improve the dispersion efficiency of sand mills, etc., and for this reason, there is a strong demand for glass beads with excellent mechanical strength and abrasion resistance.

The conditions for glass beads that are suitable for the sand mill are: ■ The bead particle size must be constant to maintain the fractional effect and be difficult to wear; ■ The mechanical strength must be high and strong against impacts such as collisions and will not shatter; ■ The glass beads must be compatible with the dispersion solvent. It is difficult to elute and has excellent chemical durability.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and is based on a crystallized product (mainly Ba0.8FesOs m BaO.Bs
The object of the present invention is to provide abrasion-resistant crystallized glass beads that are composed of 0s), have almost no elution of alkaline components, and have excellent mechanical strength.

[Summary of the Invention J The present invention provides Boom 20-4096, F
e5Os20~4696, BaO30~5L%, Sin
, , 7v, Os combination JiO, 01~596, ZrO
These are wear-resistant crystallized glass beads made by heat-treating and crystallizing glass beads having a composition of 20.0.01-596. In order to use these crystallized glass beads as a dispersion accelerator in a sand mill, the diameter of the beads must be 0.7 to 2.
A value within the range of 4111111 is suitable. If the diameter of the beads is smaller than 0.7 mm, the beads will be lightweight and will lack kinetic energy during milling, resulting in poor dispersion effect.
If the diameter exceeds 2.4 mm, not only will the gap between the beads become large and the dispersion effect will be reduced, but also the beads will have a low percentage of sphericity during bead molding, increasing the probability of being crushed during i-) blowfishing. There is a risk that thick (and relatively large) fragments may occur during the dispersion process and interrupt the process.

The reason why the glass composition of the present invention is limited to the above range will be described below.

Boom is a basic component necessary for glass composition209
If it is less than 6, the devitrification during melting will be large and it will be difficult to form beads, and if it exceeds 4096, no crystallized product will be formed during heat treatment and high strength will not be obtained. If Fe*Os is less than 2096%, the desired crystallized product cannot be obtained, and if it exceeds 46%, it is outside the vitrification range. If BaO is less than 3096, the chemical durability is extremely poor and the gloss on the bead surface is easily lost.
If it exceeds 5%, no high-strength crystallized product will be formed.

The high-strength crystallized product according to the present invention is mainly Ba0.6F.
elOs, and Ba() B*Os as an accessory precipitate
It is a crystallized product of # and γ・Fe*Os. Sin,
.

A41fiO1 is added in small amounts as a chemical stabilizer for the glass matrix of these crystallized glass beads, but 59
If it exceeds 6, the glass becomes resolvable, making it difficult to mold beads. ZrO is not only effective as a crystal nucleating agent for BaO・6Fe*Os (ZrO is added to improve the chemical durability of matrix glass, but 59
If it exceeds 6, the meltability becomes poor (and it becomes difficult to mold beads).

Alkali metal oxides such as Nano, K*O, and LtsO are not added in order to avoid elution of alkaline components during dispersion, and even if they are included, they may be mixed in from raw material impurities.
It is a trace amount of less than %.

Next, glass having the above composition is melted at a temperature of 1200 to 1300°C, and when this molten glass is continuously flowed down at a viscosity of 100 poise or less onto the upper surface of a disk rotating at high speed, it comes into contact with the disk. At times, shock waves are transmitted to the glass stream, and the glass stream is dispersed and scattered by centrifugal force, and while flying through the air, it is shaped into a spherical shape by surface tension and becomes glass beads. By heat-treating the glass beads at 500-550°C for 3-5 hours and further at 800-850°C for 5-7 hours, Ba0.6 Fe, O, # and BaO-
Crystallized glass beads containing Boom as the main constituent oxide are obtained.

[Embodiments of the invention]

Examples of the invention will be described and described. In the table, 4.
Na5 is a comparative example using conventional glass beads, and the glass composition is shown in weight percentage. The compressive strength is the compressive crushing strength value measured using an autograph compression device, and the abrasion resistance is measured by placing 2 # of glass beads and water in a 21-inch sand mill and rotating the stirring blade at 3,000 times/min. This is the value expressed as a percentage of the abrasion loss of the glass beads. Also,
The alkali elution property was determined by placing glass beads in a quartz Soxhlet elution device with a specific gravity x 2 weight, and after boiling for 4 hours, the amount of alkali elution was determined using a plasma emission spectrometer and expressed in ppm.

(Hereinafter referred to as "Kinshiro") [Effects of the Invention] As described above, the present invention provides heat treatment of glass beads to produce Ba0.6Fe*Os and BaO"B*O.
It is a wear-resistant crystallized glass bead formed of a crystallized product mainly composed of s, and when used in a sand mill or plain mill as a powder dispersion promoter, it has the following effects.

■ Glass beads have a long lifespan due to their excellent abrasion resistance (can be used continuously for long periods of time).

■ High mechanical strength (as the glass beads themselves are less likely to fracture, it is possible to prevent glass bead fragments from being mixed into the powder, improving product quality).

■ Since there is almost no elution of alkaline components, there is no chemical deterioration of the fractional material, and it can be stably used in acidic or alkaline dispersion materials.

Note that the glass beads of the present invention are not limited to the above uses.

Claims (1)

[Claims] B_2O_320-40% in weight percentage, Fe_2O_
320-46%, BaO30-55%, SiO_2, A
Total amount of l_2O_3 0.01-5%, ZrO_20.0
Abrasion-resistant crystallized glass beads obtained by heat-treating and crystallizing glass beads having a composition of 1 to 5%.