JPS627138B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition of a glass for beads having excellent abrasion resistance and impact resistance, and in particular, a glass for beads having characteristics suitable for use as a dispersion medium in a dispersion machine such as a sand mill.

In recent years, in industrial fields such as pigment paints, dispersion machines such as sand mills using glass beads as a dispersion medium have been used in the dispersion and homogenization process of raw materials. Sand mills contain raw materials and glass beads with a diameter of 0.5 to 5 mm in a container with built-in stirring blades.
The movement of the blades and glass beads disperses and homogenizes the raw material.

Conventionally, the bead material used as the dispersion medium in such a dispersion machine is mainly Na ₂ O−CaO
-SiO ₂ glass is used.

However, this type of glass has poor abrasion resistance and impact resistance, and causes significant wear and tear in the dispersion machine, which not only reduces the dispersion efficiency but also reduces the operating efficiency of the dispersion machine. In addition, it has disadvantages such as elution of alkaline components and changing the pH value of the raw material.

As described in Japanese Patent Application Laid-Open No. 53-102325, the present inventors have discovered a glass that improves the drawbacks of the above glass,
In other words, SiO ₂ −Al ₂ O ₃ −CaO− has excellent wear resistance and has the characteristics that the change in the above PH value is small.
Although MgO−B ₂ O ₃ −ZrO ₂ −TiO ₂ glass was invented, the impact resistance of this glass has not been sufficiently improved, so it is difficult to disperse raw materials with low viscosity or with high circumferential speed of stirring blades. When used in a dispersion machine, impact damage and wear occur, and broken beads clog the mesh provided in the container of the dispersion machine, significantly reducing workability.

Note that Otsutawa sand made of quartz, beads made of zircon, and corundum are known as dispersion media other than glass, but Otsutawa sand is a natural product and its quality is not stable, and it also contains many impurities. Therefore, it is easy to contaminate the product. In addition, zirconium and corundum beads have extremely high hardness, which causes severe wear on the container and stirring blades of a disperser, and they are also expensive, making them difficult to put to practical use.

As a result of repeated testing and research aimed at eliminating the various drawbacks found in the above-mentioned conventional glass, the inventor of the present invention found that
In SiO ₂ -Al ₂ O ₃ -MgO-B ₂ O ₃ -TiO ₂ -fluoride glass, a glass composition with excellent abrasion resistance and impact resistance was found, and the present invention was accomplished.

The composition range of each component of the glass according to the present invention for achieving the above object is as follows in weight percentage.

_SiO2 35.0~55.0%, _{Al2O3 15.0} ~35.0%,
MgO7.0~25.0%, _{B2O3 0.5} ~10.0%, _TiO22.0 ~
12.0%, CaO0~20.0%, however, MgO+
CaO15.0-30.0 _{% , ZrO2} + _La2O3 + _{Y2O3 + Ta2O5}
+Nb ₂ O ₅ +WO ₃ 0 to 6.0%, and a total of 0.2 to 5.0% of F, a fluoride substituted for part or all of one or more of the above oxides.

The reason for limiting the composition range of each of the above components is as follows.

If the content of SiO ₂ is less than 35%, the abrasion resistance and impact resistance will deteriorate, and the glass will tend to devitrify, making it difficult to mold the glass into a perfect sphere using the conventional bead molding method. Moreover, if it exceeds 55%, melting becomes difficult.

When the Al ₂ O ₃ content is less than 15%, wear resistance deteriorates, and when it exceeds 35%, devitrification tends to occur.

In the glass of the present invention, MgO is a component that greatly improves the wear resistance of the glass, but if its content decreases or increases beyond the range of 7 to 25%, its effect becomes poor.

B ₂ O ₃ is an important component that improves the stability against devitrification and melting properties of glass, but if its content is less than 0.5%, the effect is poor, and 10
%, wear resistance deteriorates.

TiO ₂ is necessary to improve the abrasion resistance and meltability of glass, but if its content is less than 2%, it will have little effect, and if it exceeds 12%, the glass will tend to devitrify.

CaO can be reduced to 20% by partial substitution or addition of MgO.
%, but CaO and MgO
If the total amount is less than 15%, it will be difficult to melt the glass, and if it exceeds 30%, the abrasion resistance will deteriorate.

For improved wear and impact resistance
_ZrO2 , _{La2O3 , Y2O3 , Ta2O5 , Nb2O3 and WO3}
However, if the total amount of one or more of these components exceeds 6%, it is not preferable because it increases the tendency to devitrify or increases the cost of raw materials.

The fluoride substituted for part or all of one or more of the above oxides is an important component in the glass of the present invention, and can be used without deteriorating the abrasion resistance.
Impact resistance can be significantly improved, but if the total amount of F in the fluorides is less than 0.2%, the above effect is not significant, and if it exceeds 5%, the glass tends to devitrify, resulting in the above-mentioned As shown in the figure, it is difficult to form a perfect sphere using the conventional bead forming method. A specific example of the above effect of F is shown in FIG. this is,
By weight, _SiO2 45.0%, _{Al2O3 20.0} %, MgO15.0
%, CaO7.0%, _{B2O3 5.0} %, _TiO2 5.0%, ZrO2 _3.0
%, some of the O is replaced by F
The figure shows the change in impact fracture strength (the measurement method will be described later) when replacing with .

In addition, the glass of the present invention contains a small amount of BaO, in addition to the above components, without impairing the properties of the glass.
PbO, P ₂ O ₅ , Fe ₂ O ₃ , CeO ₂ and trace amounts of Na ₂ O, K ₂ O
Also, defoamers (As ₂ O ₃ , Sb ₂ O ₃ , SO ₃ ), etc. can be contained.

Next, Table 1 shows the results of various measurement tests for examples of the glass of the present invention and conventional glass examples.

Here, the degree of abrasion was determined using the test method according to the standards of the Japan Optical Glass Industry Association. In other words, a plate-shaped sample of 30 x 30 x 10 mm was placed on a rotating disk, and alumina abrasive grains of 20μ particle size were
After lapping for 5 minutes while giving 20 ml of water and 20 ml of water, the ratio of abrasion loss to standard glass (BK7) was calculated using the following formula.

Abrasion degree = Abrasion loss of sample / Specific gravity / Abrasion loss of standard glass / Specific gravity × 100 Abrasion loss is calculated by combining 500 ml of glass beads with a diameter of 1.5 to 2.0 mm in actual volume and 500 ml of 50% barite aqueous solution in a stainless steel container with a diameter of 120 mm. The abrasion loss of the glass beads after 100 hours of operation was expressed as a percentage of the original actual volume by rotating a stirring blade with three stainless steel disks with a diameter of 100 mm at a circumferential speed of 12 m/s. be.

Further, the amount of damage is a value expressed as a weight percentage of broken glass pieces contained in the glass that have become irregularly shaped after the abrasion loss measurement.

Impact breaking strength is measured by the weight and fall of glass beads of 1.50±0.02 m/m when placed on a cemented carbide metal table and a hammerhead-shaped carbide metal weight dropped from above. This is a value calculated from distance. The measurement was performed for each glass bead, and the value obtained when all five glass beads were broken under the same conditions was defined as the impact breaking strength, which was determined from the following formula.

Impact breaking strength (Kg/ ^cm2 ) = Weight of weight x Falling distance of weight/Volume of sample PH value is calculated by taking 50 times the specific gravity of glass crushed to a particle size range of 420 to 590μ, and adding 20ml of pure water. Pour into a quartz glass flask and shake with a shaker for 24 hours.
This is the value measured using a PH meter for the solution in the flask after shaking for an hour.

The glasses of the above examples were all made by melting batches prepared using raw materials such as oxides, carbonates, nitrates, and fluorides at 1400 to 1500°C using a normal melting device.
It can be obtained by melting at a temperature of . Furthermore, bead formation can be easily carried out by a conventional method such as passing glass powder mixed with carbon powder through a high-temperature rotary furnace to form spheres.

As is clear from Table 1, the degree of abrasion of the glass of the example of the present invention is reduced by about 40% or more compared to the Na ₂ O-CaO-SiO ₂ glass of the conventional example (1). The wear loss and damage amount are 1/5 or less, and the impact fracture strength is about twice or more. Furthermore, while Na ₂ O--CaO--SiO ₂ type glass exhibits strong alkalinity, the PH value of the glass of the present invention is in the range of 7.0 to 8.5. Furthermore, the glass of the present invention has SiO ₂ − of the conventional example (2).
Compared to Al ₂ O−CaO ₃ −MgO and B ₂ O ₃ −ZrO ₂ −TiO ₂ glasses, the degree of abrasion and wear loss are reduced, and the amount of damage is less than 1/2, and , the impact fracture strength is about 1.5 times or more. Although not listed in the table, the Knoop hardness of zircon and corundum beads is 1200 to 1800 Kg/mm, whereas the glass of the present invention has a suitable numerical value range of 550 to 670 Kg/mm. be.

As mentioned above, the glass of the present invention has excellent abrasion resistance and impact resistance, so when used as glass beads for the dispersion medium of a raw material dispersion machine, it has higher dispersion efficiency than when using conventional glass beads. and increase the operating efficiency of the disperser.
It is particularly suitable for low-viscosity raw materials and dispersers with high wind speeds of stirring blades. In addition, since the change in the pH value is small, there are very few problems such as changes in the color of the raw material, and the hardness is moderate, reducing wear and tear on the disperser container and stirring blades, extending their lifespan. I can do it.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the present invention, SiO ₂ 45.0
%, _{Al2O3 20.0} %, MgO15.0%, CaO7.0%,
The relationship between the amount of F and impact fracture strength when a part of O is replaced with F in a glass having a _composition of 5.0% B ₂ O ₃ , 0.5% TiO ₂ and 3.0% ZrO 2 is shown.

【table】

【table】

Claims (1)

[Claims] 1. SiO ₂ 35.0-55.0%, Al ₂ O ₃ 15.0-35.0%, MgO 7.0-25.0%, B ₂ O ₃ 0.5-10.0%, TiO ₂ 2.0-12.0%, CaO 0 to 20.0%, however, MgO + CaO 15.0 to 30.0%, ZrO ₂ + La ₂ O ₃ + Y ₂ O ₃ + Ta ₂ O ₅ + Nb ₂ O ₅ + WO ₃
0 to 6.0%, and a total of 0.2 to 6.0% of F of the fluoride that replaced part or all of one or more of the above oxides.
Glass for beads characterized by having a composition of 5.0%.