JPH0146465B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to abrasion-resistant crystallized glass beads that have excellent alkali elution resistance, mechanical strength, and abrasion resistance, and are particularly suitable as a material for accelerating pulverization and dispersion using a dispersion machine such as a sand mill. . [Technical background of the invention and its problems] Conventionally, a dispersing machine such as a sand mill using glass beads has been used to make powders such as pigments and magnetic materials for magnetic tapes into fine particles and homogeneously disperse them in a solvent. ing. 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 a matter of dispersion. The glass beads used in this case are generally made by crushing soda lime glass to a predetermined particle size 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. moreover,
Since the glass beads are worn out in a short period of time, there is a disadvantage that the glass beads must be replaced frequently in order to maintain a predetermined particle size. Moreover, recently there has been a trend toward higher speed rotation in order to improve the dispersion efficiency of sun mills and the like, 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 that the bead particle size must be constant and difficult to wear in order to maintain the dispersion effect, the beads must have high mechanical strength and can withstand impacts such as collisions and will not shatter, and they must be difficult to dissolve into the dispersion solvent. , it has excellent chemical durability. [Object of the Invention] The present invention was made in consideration of the above circumstances, and is based on crystallized products (mainly BaO・6Fe ₂ O ₃ , BaO・
The purpose of the present invention is to provide wear-resistant crystallized glass beads that are composed of B ₂ O ₃ ), have almost no elution of alkaline components, and have excellent mechanical strength. [Summary of the Invention] The present invention provides B ₂ O ₃ 20-40% by weight percentage;
_{Fe2O3 20-45} %, BaO _30-55 %, _SiO2 , _Al2O3
These are wear-resistant crystallized glass beads made by heat-treating and crystallizing glass beads having a composition of 0.01 to 5% of ZrO ₂ and 0.01 to 5% of ZrO 2 . In order to use the crystallized glass beads as a dispersion accelerator in a sand mill, beads having a diameter in the range of 0.1 to 2.4 mm are 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 it exceeds mm, not only will the mutual gap between the beads become large and the dispersion effect will be reduced, but also the beads will have a low sphericity ratio during bead molding, and there is a high probability that they will be crushed during milling, and relatively large fragments will be generated. There is a risk that this will occur during the dispersion process and the process will be interrupted. The reason why the glass composition of the present invention is limited to the above range will be described below. B ₂ O ₃ is a basic component necessary for glass composition, but
If it is less than 20%, the devitrification during melting will be large, making it difficult to form beads, and if it exceeds 40%, no crystallized products will be formed during heat treatment, making it impossible to obtain high strength. _{Fe2O3 is}
If it is less than 20%, the desired crystallized product cannot be obtained, and if it exceeds 45%, it is outside the gasification range. When BaO is less than 30%, the chemical durability is extremely poor and the gloss on the bead surface is easily lost, and when it exceeds 55%, high-strength crystallized products are not formed. The high strength crystallized product according to the present invention is mainly
BaO・6Fe ₂ O ₃ , with BaO・6Fe 2 O 3 as an accessory precipitate.
It is a crystallized product of B ₂ O ₃ and α・Fe ₂ O ₃ .
A small amount of SiO ₂ and Al ₂ O ₃ is added as a chemical stabilizer for the glass matrix of the crystallized glass beads, but if the amount exceeds 5%, the glass becomes poorly soluble, making it difficult to mold the beads. ZrO ₂ is not only effective as a crystal nucleating agent for BaO 6Fe ₂ O ₃ but also
It is added to improve the chemical durability of matrix glass, but if it exceeds 5%, meltability deteriorates and it becomes difficult to mold beads. Alkali metal oxides such as Na ₂ O, K ₂ O, Li ₂ O, etc. are not added in order to avoid the elution of alkaline components during dispersion, and even if they are contained, they are added in trace amounts of less than 0.5% from raw material impurities. be. 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 this disk. At times, shock waves are transmitted to the glass flow, and the glass flow is dispersed and scattered by centrifugal force, becoming glass beads shaped into spheres due to surface tension while flying through the air. Heat the glass beads at 500 to 550℃ for 3 to 5 hours, and then heat them for 800℃.
By heat treatment at ~850°C for 5-7 hours,
Crystallized glass beads whose main constituent oxides are BaO.6Fe ₂ O ₃ and BaO.B ₂ O ₃ are obtained. [Embodiments of the Invention] Examples of the present invention will be described and explained. In the table, glasses No. 4 and No. 5 are comparative examples using conventional glass beads, and the glass composition is shown in weight percentage. The compressive strength is measured using a compression crushing strength meter using an autograph compression device, and the abrasion resistance is measured using a sand mill containing 2 kg of glass beads and water and a stirring blade of 3000 ml.
This is a value expressed as a percentage of the abrasion loss of glass beads after 48 hours of rotation at a rate of rotation per minute. In addition, the alkali elution property was determined by placing glass beads in a quartz Soxley elution device with a specific gravity x 2 weight, and quantifying the amount of alkali elution after 4 hours of boiling using a plasma luminescence spectroscopy device.
Shown in ppm.

〔Effect of the invention〕

As described above, the present invention provides BaO・6Fe ₂ O ₃ and BaO・B ₂ O ₃ by heat treating glass beads.
It is a wear-resistant crystallized glass bead formed of a crystallized product mainly composed of, and when used in a sand mill or a blend mill as a powder dispersion promoter, it has the following effects. Due to their excellent abrasion resistance, the glass beads have a long lifespan and can be used continuously for long periods of time. Since the mechanical strength is high and the glass beads themselves are not easily crushed, it is possible to prevent glass bead fragments from being mixed into the powder, improving the quality of the product. There is almost no elution of alkaline components, causing no chemical deterioration of the dispersion 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-mentioned uses.

Claims (1)

[Claims] 1 B ₂ O ₃ 20-40%, Fe ₂ O ₃ 20-45 in weight percentage
%, BaO 30 _~ 55%, total amount of _SiO2 , _Al2O3 0.01~
5% and ZrO ₂ 0.01 to 5%, the wear-resistant crystallized glass beads are heat-treated and crystallized.