SU1731746A1 - Method of producing flaky material from molten glass - Google Patents

Abstract

SUMMARY OF THE INVENTION: A film is formed on the inner surface of a truncated inverse cone. The cone rotates at a speed of 250-300 m / min. Shot the film on flakes with a pulsed stream of compressed air with a frequency of 70-90 pulses per minute at a pressure of 1.8-2.2 kg / cm. Collected scales cyclone, 1 silt., 1 tab.

Description

This invention relates to a technology for producing glass flakes or flocculent particles by forming thin glass films under the action of centrifugal forces with their subsequent grinding and can be used in the building materials industry.

A known method of making glass flakes involves the preparation of glass melt, the formation of individual melt streams under the action of centrifugal force, the formation of a thin film of glass from melt streams thrown onto a fixed surface when the thin melt layer flows down under the action of gravity, the film is crushed by compressed air in the annular zone, blowing discrete flakes and selecting them using vacuum.

However, the known method is labor-intensive and material-intensive, and the resulting film is not thin enough and uneven in thickness, while the flakes obtained in

the result of the chaotic crushing of the film with compressed air, non-identical in linear dimensions

The closest to the invention to the technical essence and the achieved result is a method of making flaky material from a glass melt by molding a film from it under the action of centrifugal force, crushing the film with an annular flow of compressed air into discrete flakes and collecting them under vacuum.

This method provides thinner glass flakes than the previous method by pulling (thinning) the film with compressed air, however, this technique is ineffective, as the film is rapidly cooled. At the same time, it is not possible to reduce the thickness of the film and, therefore, the flakes by increasing the speed of rotation of the mushroom-shaped element, since the melt separates from the surface of the element.

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The process of film forming is disturbed.

In addition, the flakes produced by this method are not identical in size as a result of chaotic film crushing.

Due to the fact that corrosion- and wear-resistant protective coatings with scaly filler are applied to the surface using sprayers, the scraps must be sufficiently thin and of a certain size so as not to clog the openings of the sprayers. The thinner the scales, the more flexible they are.

The aim of the invention is to reduce the film thickness and to obtain scales of a given size.

The drawing shows an apparatus for making flaky material, a general view.

Molding a film from a glass melt on the inner surface of a truncated inverse cone rotating with a speed of 250-300 m / min consists in the fact that the glass melt fed into the rotating cone is thrown onto its lateral surface by centrifugal force evenly distributed on it and stretched to film when climbing an inclined surface.

The speed of rotation of the cone, equal to 250-300 m / min, is optimal and provides a film with a thickness of 0.5-5 microns. At speeds in excess of 300 m / min, the magnitude of the centrifugal force prevails over the value of the adsorption coupling of the melt to the surface of the cone and therefore the melt is thrown out. At a speed of less than 250 m / min, a thick film is formed as a result of weak stretching of the melt.

The exposure of the film to a stream of cold compressed air with a predetermined frequency in the range of 70-90 pulses per minute at a pressure of 1.8-2.2 kg / cm2 ensures the fragmentation of the film into discrete flakes of a given size. When air is applied to the film with a frequency of less than 70 pulses per minute, large-sized flakes are formed, which break down during use. When compressed air is fed to the film with a frequency of more than 90 pulses per minute, very small flakes are formed, the use of which for the manufacture of multilayer coatings is inefficient, and the delivery of coating compositions based on them through the sprayers is difficult.

The pressure of compressed air, which produces the crushing of the film, in the interval

1.8-2.2 kg / cm2 is optimal for flakes with well-defined edges. With a pressure of compressed air below 1.8 kg / cm, the resulting flakes are not identical in area, with torn edges. When the air pressure is above 2.2 kg / cm2, the process energy consumption unnecessarily increases, which leads to an increase in the cost of scales.

The dependence of the quality indicators of flakes on the parameters of the technological mode is presented below (at air pressure of 2 kg / cm and a frequency of 80 pulses per minute).

Rotational speed-Line thickness truncated lines, microns

reverse cone, m / min

23016-50

2505-15

2702-5

3000.5-3

340No stable thickness

The dependence of the area of scales on the frequency of the pulsed flow of compressed air with air. 2 kg / cm2 and a cone rotation speed of 270 m / min are presented in the table.

From the presented data it can be seen that the optimal value of the rotational speed of the truncated reverse cone lies in the range of 250–300 m / min, and thus a scale of 0.5 to 15 µm thick is formed, which finds use as an anti-corrosion filler and wear-resistant protective coatings, paper, cardboard, polymer composites, etc. For example, the scale thickness of 0.5-3 microns is most effectively used for the manufacture of multilayer coatings, and the scale thickness of 5-15 microns - as a filler for the manufacture of cardboard. Thus, by adjusting the magnitude of the rotational speed of the film-forming element, it is possible to produce scales of predetermined thickness dimensions. By reducing the rotational speed below 250 m / min, flakes up to 5 microns thick are obtained, which become somewhat brittle and therefore unsuitable for use as a filler. An increase in the rotation speed of the forming element (above 300 m / min) leads to a destabilization of the film production process, i.e. to film thickness variation.

From the table it can be seen that the frequency of the pulsation of the stream of compressed cold air, which carries out the fragmentation of the film, determines the size of the area of flakes. The optimal frequency limit for this is the interval. equal to 70-90 pulses per minute so

how the flakes obtained under this pulsation regime meet the requirements of the fillers.

The installation contains an element for forming a film from a glass melt, made in the form of a truncated inverse cone 1, into which the glass melt is fed from the feeder of a glass melting furnace 2. The cone 1 is rotated by means of a drive device 3, made in the form of a wedge-belt transfer from the electric motor to the hollow a spindle which is the working body of the cone.

An annular slit blow head 4 is placed above the reverse truncated cone, into which cold compressed air is supplied by fan 5 to crush the film, an interrupter valve 6 adjoins the slit of the blow head, with which a pulsating air flow is created

The resultant scale is deposited in chamber 7 on a perforated conveyor 8, to which a vacuum chamber 9 adjoins from below.

Collected on a conveyor scale passes sequentially through a series of cyclones.

10, where it is divided into fractions according to the mass.

The method according to the invention provides for obtaining scales of a given size in thickness and area in a wide range of values, obtaining scales with a thickness of 0.5-15 μm at lower energy and material costs.

Claims (1)

The invention method of making flaky material from molten glass by forming a film from it under the action of centrifugal force, crushing the film with an annular stream of compressed air into discrete flakes and collecting them under the action of rarefaction, characterized in that in order to reduce the film thickness and obtain scales of given sizes the film is formed on the inner surface of a truncated reverse cone rotating at a speed of 250-300 m / min; the film is divided into flakes by a pulsed flow air at a frequency of 70–90 pulses per minute at a pressure of 1.8–2.2 kg / cm2, and the collected flakes are cycloned. h