JPS602095B2 - Method for producing beads of heat-softening material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing beads of thermoplastic material.

Beads of heat-softening materials, especially glass, tin holders, and other minerals, generally have a diameter of several tens of micrometers.

It ranges from a few millimeters to a few millimeters. These mineral beads can be mixed into other organic or inorganic materials as reinforcing materials to improve various properties such as heat resistance, film resistance, mechanical strength, etc. For example, the beads can be arranged in a letter shape and used for road signs, etc.As a method for manufacturing mineral beads, crushed and segmented mineral particles are suspended and melted in a hot gas, and the surface tension A well-known method is to spheroidize the mineral under the action of minerals and then cool and solidify it. However, this manufacturing method requires a wide range of operational steps, and increases energy costs due to the double melting of the mineral, as well as crushing and throttling. In addition, it is difficult to process a large amount of finely ground minerals at high temperature to prevent mineral balls from coming into contact with each other in hot gas, which inevitably reduces productivity. On the other hand, attempts have been made to directly disperse and spheroidize molten minerals using methods such as ultrasonic pulsation or intermittent jetting of high-pressure gas in order to save on the costs of crushing, particle size control, and double melting.

However, dispersion using ultrasonic pulsation requires complicated equipment, and intermittent ejection of high-pressure gas requires relatively high compression energy, and it is difficult to control the grain size of mineral beads. There are problems such as the contamination of substances that cannot be converted into raw materials. Recently, molten minerals are supplied onto a high-speed rotating member to form a film, and the molten mineral film is dispersed in a high-temperature zone under the action of centrifugal force due to the rotation of the rotating member, and is then subjected to the action of surface tension. Spherical,
Furthermore, a method for producing mineral beads has been proposed in which they are released into a cold temperate zone and solidified. This manufacturing method has simple operation steps and has advantages over the above-mentioned methods in terms of energy costs and productivity, but the selection of rotating parts does not prevent wear and tear even under high temperatures and under the influence of molten glass. Finding a material that can withstand wear and tear involves high temperatures, and requires close attention to process control. In view of the above-mentioned drawbacks, the present invention aims to provide a method for producing mineral beads that has simple operating steps and simple equipment. The present invention blows away molten minerals using high-speed airflow,
The method of adding molten minerals to high-speed airflow has been devised.

The present inventors have previously developed a method for producing fibers made of heat-softening substances (
Tokuiso Showa 50-101618 Filed on August 20, 1975 (
He proposed the following:

This is a so-called swirling gas jet method, and in detail, it involves continuously flowing out a melt of a heat-softening material, and discharging the melt in a first area along the progress of the melt that flows out. A gas flow having a tangential component in the transverse south outer circumference is brought into contact with the molten material in such a way as to prevent the molten material from displacing in the lateral direction. rotating the melt about a central axis, thereby moving the melt laterally from said first zone along the melt progression in a second zone mainly by centrifugal force due to rotation due to the inertia of said rotational force. A thermosoftening method characterized by continuously drawing out fibers of a thermosoftening substance from a molten material by causing the fibers to pop out and spread in the circumferential direction as seen from the central axis and in the same direction as the rotation. This is a method for producing fibers of matter. More preferably, the melt of the thermosoftening substance is continuously flowed out from the melt nozzle outlet with a cross-sectional diameter of 0.5 to 1 shipboard, and the first area along the progress of the flowed melt is preferably A gas flow having a component in the tangential direction to the outer circumference of the cross section of the melt and a component that approaches the central axis along the progress of the melt is directed to the tip of the melt nozzle and to the center axis of the progressing melt. The gas flow is brought into contact with the point closest to the melt nozzle so that the distance between the points is 0.2 to 10 times the inner diameter of the melt nozzle and to prevent the melt from displacing in the lateral direction. in a second zone following the melt progression from said first zone, comprising rotating the object about the central axis of the melt while confining it in a defined position and forming a tapered conical shape; The melt is ejected from the tapered tip of the conical shape in the lateral direction by the centrifugal force caused by the rotation mainly based on the inertia of the rotational force, and the ejection direction is in the circumferential direction as seen from the central axis and is the same as the rotation. This is a method for producing fibers of a heat-softening material, characterized in that fibers of a heat-softening material are continuously drawn out from a melt by rotating the fibers in the same direction. When the present inventors studied a method for producing minute objects, especially glass fibers, using this swirling gas jet method, the present inventors found that the viscosity of the melt of the heat-softening material, the flow rate of the melt, and the effect on the melt It has been discovered that by adjusting the flow rate of the gas, it is possible to produce beads of high quality thermoplastic material. That is, the present invention provides a method in which a swirling gas jet is applied to a molten cylindrical flow of a thermosoftening substance, in which the molten cylindrical flow is maintained at a viscosity of 100 poise or less, and the cylindrical flow is This is a method for producing beads of a heat-softening material, characterized in that the weight ratio of the flow rate is 0.15 or more.

In the present invention, first, a melt of a heat-softening substance, such as glass, a melt of minerals such as slag, is continuously flowed out or discharged. This melt may be discharged by melting the mineral in a crucible or pot and drawing it out through a nozzle provided at one end of the crucible, or by moving the solidified mineral rod along its length at a constant speed. This may be done by heating the tip of the rod and drawing a mineral melt from the tip equal to the amount of displacement.

The mineral melt is continuously flowed out in the form of a filament, and the viscosity of the filamentous melt immediately after discharge is preferably 100 poise or less.

With a viscosity greater than 100 poise, when a high-speed gas flow acts on a molten cylindrical flow, the viscous force increases and the stretching effect becomes stronger, and the influence of surface tension becomes relatively small, resulting in a spherical shape. This makes it difficult to make beads efficiently.

Therefore, the viscosity is preferably 100 poise or less, particularly 30 poise or less. Generally, a suitable cross-sectional diameter of the cylindrical melt immediately after it flows out of the pot is 0.5 to 10 mm, but these selections can be changed depending on the speed, etc. of the high-speed gas flow. The molten cylinder stream then advances and comes under the action of a high velocity gas stream.

This high-speed gas flow rotates the first zone that stably confines the cylindrical flow and the tip of the molten cylindrical flow relative to the central axis of the molten cylindrical flow while moving outward. It is blown out from a jet nozzle arranged so as to form a second zone which serves to blow out the liquid. For example, three or more jet nozzles are tilted at an angle of 30° to 700° with respect to the central axis of the molten cylindrical flow in the same direction as its traveling direction, and viewed from a plane perpendicular to the central axis of the molten cylindrical flow. This is achieved by arranging each jet nozzle so that the gas flow exiting the jet nozzle just forms a closed polygon, and the central scale is at the center of the closed polygon. When the tip of the cone stably formed in the first zone advances to the second zone, the flow rate of the molten mineral expressed as a weight ratio to the flow rate of the high-speed gas flow acting on the molten cylindrical flow is 0. It has been found that beads can be obtained particularly efficiently when the value is .15 or more, more preferably 0.3 or more. The reason for this is thought to be as follows.

In other words, the tip of the cone of molten mineral that has advanced to the second zone is rotated and is affected by the high-speed gas flow, but as the ratio of the flow rate of the molten mineral to the flow rate of the high-speed gas becomes large, the effect of the high-speed gas flow becomes relative. This makes the molten mineral weaker and its ability to thin the molten mineral becomes smaller, so the unstretched portions easily become spheroidized due to surface tension.

Furthermore, increasing the flow rate ratio corresponds to relatively reducing the diameter of the jet nozzle that forms the high-speed gas flow, and also corresponds to requiring a low pressure to obtain the high-speed gas flow. However, this means that the chance of the high velocity gas flow in the second zone acting on the tip of the swirling cone is reduced. In other words, most of the tip of the cone slips through the gap without being affected by the high-speed gas flow. At this time, since the viscosity of the molten cylindrical flow is low, the surface tension exerts a large influence, and the tip of the cone easily becomes spherical. Next, the method of the present invention will be explained with reference to embodiment figures.

Figure 1 shows a bead manufacturing unit. Mineral substances such as glass, setomono, ore are melted in pot 1, and molten minerals 2
is provided at the bottom of the pot or passes through the kid nozzle 3,
The thin cylindrical flow 5 is affected by the high-speed gas flow 6 blown out from the jet nozzle 4. Here, it is essential that the temperature of the molten cylindrical flow is such that the viscosity is 100 poise or less. Normally, it is extremely difficult to heat the liquid nozzle 3, so the viscosity of the molten cylindrical flow can be reduced by making the temperature at the bottom of the pot as high as possible to compensate for the temperature drop caused by passage through the liquid nozzle 3. Can be kept low. Alternatively, the length of the liquid nozzle 3 may be shortened or heated air may be used as the high-speed gas for the swirling gas jet. Furthermore, it is also effective to use a type with a jet nozzle built into the bottom of the pot. The tip of the cone, which has received a swirling force due to the action of the high-speed gas flow, attempts to come under the action of the high-speed gas flow for stretching again. This high-speed gas flow for stretching is the same as the high-speed gas flow that contributed to the formation of the cone, but it works as it is for stretching in the next step. This makes it possible to manufacture . FIG. 2 is a bottom view when the tip of the cone enters the action area (second area) of the high-speed gas flow for drawing. The molten cylindrical flow 5 forms a cone by the action of the high-speed gas flow 6, and the tip 7 of the cone moves in the order of 7' and 7'' over time and comes under the action of the high-speed gas flow 8 for drawing. However, if the swirling force at the tip of the cone is large and the range of action of the high-speed gas flow for stretching is narrow, the tip of the cone will slip through the high-speed gas flow and fly out of it; A part A is stretched by the action of the high-speed gas flow.

However, since the viscosity is kept low, the stretched portion is usually easily cut, and the portion pulled away from the cone immediately becomes spheroidized under the action of surface tension, forming a bead 9.
Then, they pop out into the surrounding area. Therefore, in order to eject beads efficiently, the arrangement of the jet nozzle and the spread of the high-speed gas flow must be adjusted to provide a large swirling force to the tip of the cone while reducing the influence of the stretching action, or to apply the effect to an extremely narrow local area. It is desirable to limit it.

To achieve this, it is preferable to reduce the aperture of the jet nozzle and to make the "aperture" (the area where the centers of mutual high-speed gas flows are closest) as narrow as possible within a range where a cone can be stably formed. . Further, the number of jet nozzles is preferably three to four. In the apparatus shown in Fig. 1, expressed by weight, Si0250%, AI203 3
．． 5%, Ca0 16.0%, Mg0 5.5%, (Na
20TK20) 16% and B203 9% glass were melted and flowed out through a glue-hard nozzle with a cross-sectional diameter of 2.0.
Caliber 1. Adonis jet nozzle (gauge pressure 2-4k9/
A test was conducted in which beads with a diameter of about 100 microns were produced by arranging three (carp) beads so that the aperture was 2.6 ribs.

The amount of beads (%) is also expressed as the weight ratio of the amount of beads to the total amount of glass flowing out.

Note that the amount of glass flowing out was adjusted by the height of the base surface in the pot and the melting temperature. The results are shown in the table below.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the bead manufacturing unit of the present invention, and FIG. 2 is a bottom view taken along line A-A' in FIG. 5... Molten cylindrical flow of thermosoftening substance, 6...
・Swirling gas jet, 9...Beads. O' figure O'2 figure

Claims (1)

[Claims] 1. In a method for producing minute objects of a thermosoftening substance by applying a swirling gas jet to a molten cylindrical flow of a thermosoftening substance, the viscosity of the molten cylindrical flow is maintained at 100 poise or less,
A method for producing beads of a thermosoftening material, characterized in that the weight ratio of the flow rate of the molten columnar flow to the flow rate of swirling gas per unit time is 0.15 or more.