FI85365C - FOERFARANDE OCH ANORDNING FOER FRAMSTAELLNING AV IHAOLIGA MIKROSFAERER. - Google Patents

Description

The invention relates to a method and an apparatus for the production of hollow microspheres by heating microsphere blanks made of a material containing a blowing agent at a high temperature in a blowing agent from the origin of the blowing agent. In particular, the invention relates to a method and apparatus for manufacturing hollow glass microspheres.

Microspheres are increasingly used, e.g. in construction materials as fillers, reinforcements and lighteners. Their diameters can range from about 5 to 300, typically 20 microspheres have a diameter of about 40 to 125. The wall thickness is about 1 to 6 and the density, depending on the material, diameter and wall thickness, is typically about 0.02 to 0.5 g / cm 3. Microspheres can be made of thermoplastic materials e.g. glass, ceramics, organic polymers, and carbon. The production of microspheres from all these materials is based on dissolving the blowing agent in the raw material in the molten state and raising the temperature of the microsphere blanks prepared from the resulting mixture to a temperature higher than the initial dissolution temperature at a later stage, where final swelling and microsphere formation occurs.

1. The commonly used technique for making hollow microspheres *; * 35 is as follows:

In the first stage, the raw material of the microspheres is melted and a suitable blowing agent, e.g.

! 2 δ 5 365 SO3. Various blowing agents are described, for example, in U.S. Pat. No. 3,030,215 and U.S. Pat. No. 3,365,315. In the next step, the blowing agent-containing material is allowed to cool, after which it is crushed and sieved into suitable fractions. The crush of the desired size is then fed into a hot gas stream where the crushed particles re-melt. When the temperature of the molten particles rises above the initial dissolution temperature of the blowing agent, the blowing agent leaves the molten particles, swelling them into hollows. Surface tension forces shape the particles into spherical ones. The preparation of hollow microspheres and manufacturing equipment are described, for example, in the following publications: US 2,794,301, US 3,030,215, US 3,129,086, US 3,230,064, US 3,365,315, DE 19 61,628, US 4,340,407, GB 2,162 509, GB 1,493,209 and U.S. 4,661,137.

In all known processes, the molten raw material has to be cooled, crushed and crushed screened before reaching the above-mentioned actual manufacturing step of the hollow microsphere 20, i.e. the prior art is complicated and costly and energy-intensive; after all, they have to be defrosted twice. The cost of the raw material itself is very small in relation to the total cost of the product. The yield of hollow microspheres of acceptable quality manufactured with the current technology ---- 25 la is poor, i.e. the percentage of waste is - * high.

It is an object of the present invention to provide an improvement in the currently known methods and apparatus for making hollow microspheres, while improving the yield of good quality microspheres, i.e. reducing the percentage of waste, by eliminating intermediate cooling, crushing and crushing screening, making expandable microspheres and in a new way. The preparation of microspheres from all the above starting materials is based on the same basic principle, i.e. that an blowing agent is dissolved in the molten raw material and the temperature of the microsphere blanks prepared from the mixture thus obtained is raised at a later stage to a temperature higher than the initial dissolution temperature of the blowing agent. takes place. Since glass is the most common and most widely used raw material for the production of hollow microspheres, the method and apparatus for making hollow microspheres will be described below, although the same method 10 and apparatus can be applied equally to hollow microspheres from other thermoplastic raw materials.

The object of the invention is achieved by a method characterized in that the molten material in which the blowing agent is dissolved is drained through the nozzle opening or openings, after which the wires in the molten state are led to an oven immediately below the nozzle openings, where the wire temperature is raised by electromagnetic radiation. whereby the wires contract into droplets under the action of surface tension forces and viscous frictional forces, and the temperature of the droplets thus formed is further raised, whereby the expanding agent expands. . causes the interior of the constricted droplets to form a hollow, after which the microspheres thus prepared are cooled.

It is already known to use electromagnetic radiation, e.g. microwaves, to heat glass tubes. Such methods are described, for example, in FR 2 249 847, FR 2 288 958 and FI 78060. It is also known from FI 78060 that microwave heating of materials with a low loss factor is only possible if preheating and / or or the shape of the heating furnace is selected to be suitable.

The invention also relates to an apparatus suitable for carrying out the method, which is characterized in that the heating device immediately below the nozzle chamber 4 85365 is a microwave oven in which the temperature is raised above the initial dissolution temperature of the blowing agent.

The method and apparatus of the present invention will be described in more detail with reference to the accompanying schematic diagram showing the manufacture of hollow glass microspheres. The molten glass mass containing the blowing agent introduced into the nozzle chamber 1, prepared by a known method, is drained through the nozzle plates 2 at the bottom of the nozzle chamber 1. The nozzle plates are made of platinum and have several openings with a diameter of approx. 1 mm. The molten glass wires flowing out of the nozzle openings enter the microwave 3 of rotationally symmetrical shape immediately below the nozzle openings, where their temperature is raised by means of microwaves above the initial dissolution temperature of the blowing agent. The temperature of the droplets is further raised in the microwave oven 20 3, whereby the expanding agent, as it expands, causes the interior of the constricted droplets to form hollow. The hollow microspheres thus formed are cooled in a microwave. in the cylindrical cooling chamber 4 below the furnace 3, a medium which may be e.g. air, water or a solution of water and a surface treatment agent or; dispersion, using. The medium is introduced into the cooling chamber 4,; through openings 5 in the wall of the cooling chamber. The cooled microspheres are then transferred by means of a vacuum-operated conveying apparatus 6 to a screening apparatus 30, where they are screened into the desired fractions.

.1. The embodiment described above is, of course, only one possible embodiment of the invention. The following is *; 35 deals with one of the embodiments related to various embodiments of the invention details and options.

5 85365

At the bottom of the nozzle chamber 1, there may be one or more nozzle plates 2, such as a fiber glass drawing nozzle, in the area of which there are several small openings of about 1 mm in diameter. The nozzle plate is usually made of platinum. 5 It is also usually electrically heated so that there are no temperature differences in the nozzle and the glass flowing from it, nor mass flow differences between the different holes.

The heating device 3, is preferably a microwave oven, with which the temperature of the molten material is raised to a final expansion temperature of about 1300-1400 ° C on the glass. It has a substantially rotationally symmetrical shape, so that the heating of the molten wires takes place evenly. The frequency of the microwaves is e.g. 2-4 MHz. By using high intensity energy to raise the temperature of the material in the molten state, the energy can be directed to raising the temperature of that material itself, rather than being wasted raising the temperature of the surrounding atmosphere, as is the case with current manufacturing methods.

The wall of the cooling chamber 4 has openings or nozzles 5, from which a cooling medium, which may be air, water or a solution or dispersion between water and a surface treatment agent, is fed into the cooling chamber 4.

25

When applying the invention, e.g. to the manufacture of glass microspheres, the results according to the following example have been obtained:

Raw material: Boron-containing sodium calcium silicate glass "I Nozzle plates: 1 30 Nozzle plate openings: 200

Diameter of openings: 0.8 mm

Blowing agent: SO3

Blowing agent concentration. in the glass mass: 0,9% 35 Dissolution of the blowing agent

temperature: 1200 ° C

Expansion temperature: 1300 ° C

6 85365

The center of the microspheres.

diameter: 120 μπι 5 Wall thickness: 2 pm

Bulk density of microspheres: 40 kg / m- *

Waste percentage: As already stated, the production of hollow microspheres from the above-mentioned thermoplastic materials, such as glass, ceramics, organic polymers, or carbon, is based on the same basic principle, so that the method and apparatus of the invention are of course not limited to the example of hollow glass microspheres. it can be varied according to the following claims.

Claims (13)

A method for producing hollow microspheres by heating microsphere blanks made of a blowing agent-containing material at a temperature higher than the initial dissolution temperature of the blowing agent, characterized in that the molten blowing agent material is drained through the nozzle orifices and immediately passed through the nozzles. an oven in which the temperature of the molten wires is raised by electromagnetic radiation, whereby the molten wires contract into 15 droplets due to surface tension forces and viscous frictional forces, and the temperature of the resulting droplets is further raised. 2. For the purposes of claim 1, the provisions of this Directive apply to the following microspheres: air filtration. 25 Method according to Claim 1, characterized in that the microspheres produced are cooled by air cooling. 25 3. A patent according to claim 1, which is incorporated herein by reference in its entirety. 4. A patent according to claim 1, which comprises a microsphere, which comprises water and water and disperses. Method according to Claim 1, characterized in that the microspheres produced are cooled by means of water. A method according to claim 1, characterized in that the microspheres are cooled with a solution or dispersion formed by water and silane. 5. A method according to claim 1, comprising 35 microspheres of a medium and a solution or dispersion of a polycarboxylic acid syringe; or Ester av syra. 85365 Process according to Claim 1, characterized in that the microspheres are cooled by means of a solution or dispersion of an acid or acid ester belonging to the polycarboxylic acids. __________ - Γ 8 85365 6. For the purposes of claim 1, the terms of reference are set out in SO3. Process according to Claim 1, characterized in that the blowing agent is SO 3. 7. A method according to claim 1, comprising 5 microspherical frameworks of thermoplastic material. Method according to Claim 1, characterized in that the microspheres are made of a thermoplastic material. 7 85365 8. The first patent claim 1, which is incorporated into a microcomputer frame, is incorporated in glass. 10 Method according to Claim 1, characterized in that the microspheres are made of glass. 10 9. A preferred embodiment of claim 8, which comprises an expansion temperature of 1100 to 1500 ° C. Process according to Claim 8, characterized in that the expansion temperature is 1100 to 1500 ° C. 10. The method according to claim 1, having a frequency of 15 microns, having a high frequency of 1 to 10 MHz, a high frequency of 2 to 4 MHz. Method according to Claim 1, characterized in that the temperature of the wires is raised by microwaves having a frequency of 1 to 10 MHz, most preferably 2 to 4 MHz. 11. Anordning for the use of a micro-spherical genome of up to 20 microscopic frameworks with 20 material inputs at the same temperature as the expansion medium at the same temperature as the one of the two (more than one) en eller flera öppningar, samt en under dyskammaren (1) belägen 25 uppvärmningsanordning (3), velt en en uppvärmningsanord-ningen belägen avkylningsanordning (4), kännetecknad därav,. : att den omedelbart under dyskammaren belägna uppvärmnings-. ···. anordningen (3) utilörs av en microvägsugn, i vilken temperaturen höjs account en högre temperatur än expansionsmedlets 30 ursprungliga lösningstemperatur. Apparatus for producing hollow microspheres from microsphere blanks made of a material containing 20 blowing agents heated to a temperature higher than the initial dissolution temperature of the blowing agent, comprising a nozzle chamber (1) and at its bottom at least one nozzle plate (2) with one or more nozzles; Heating device (3) below (1) and cooling device (4) below the heating device, characterized in that the heating device (3) immediately below the nozzle chamber (1) is a microwave oven in which the temperature is raised to the initial dissolution temperature of the blowing agent. higher. 12. An arrangement according to claim 11, which comprises a further arrangement of a side chamber (4) and a method according to which the side chamber (5), the genome flashes 35 and the microspheres of the side chamber (4). 12 85365 Apparatus according to Claim 11, characterized in that the cooling chamber (4) acting as a cooling device has nozzles or openings (5) through which microspheres are introduced into the cooling chamber (4). medium. 9 85365 Apparatus according to claim 11 or 12, characterized in that in connection with the cooling chamber (4) there is a conveying device (6) which transports the microspheres out of the cooling chamber (4). 5 ___- - - - · i ... 10 85365 5 1. Förfarande för tillverkning av ihäliga micro- sfärer genoni att uppvärma mikrosfärsämnen, framställda av material innehällande expansionsmedel, veri en högre temperatur än expansionsmedlets urspreml perer in the form of a variation of 10 materials, in which the splice is exposed to an exponential state, a ring is shown in the form of an expansions, -15 Ning, varvid de smälta trädarna snör ihop sig account droppar pä Grund av ytspänningskrafter och viscous friktionskrafter och de head dät sätt alstrade dropparnas temperatur ytterli-Gare höjs, varvid expansionsmedlet dä det utvidgar sig ästadkommer att de hops de pä detta sätt framställda mikrosfärerna avkyls. 13. An arrangement according to claims 11 or 12, which can be used as a transport device (6), for a microsphere in a side chamber (4), or in a row with a side row (4).