DE2607665C3 - Method for starting a spinning process for glass fibers - Google Patents

Description

The invention relates to a method for starting a spinning process for glass fibers, in which a Molten glass flows through nozzle plates and is drawn into threads.

Z '/ r manufacture of glass fibers will be in practice flat multi-hole nozzles are used. Such nozzle plates must be made of materials, which at the high Temperatures at which glass is spun from the melt are stable. Are known for example Multi-hole nozzles made of a platinum-rhodium alloy. When the glass melt flows through the Nozzles and when the threads are pulled out of the droplets forming under the nozzle plate, there is now the There is a risk that the droplets will flood the underside of the nozzle plate and that the Threads and finding the individual threads becomes difficult or impossible. The convergence of the Bottom of the nozzle formed droplets occurs in particular when the number of nozzles per Unit area is large. On the other hand, for reasons of productivity, the largest possible number of Nozzles per unit area desirable in the manufacture of glass fibers.

To avoid flooding on the underside of the nozzle plate / u and as large as possible To enable the number of nozzle openings per unit area / u, the nozzles are on the underside configured like a horn, as is described, for example, in GB-PS 10 49 517.

From DEOS 24 20 650 is the production of Glass fibers known, in which you exit a glass melt from a flat nozzle plate to unien and the Can flood the underside of the nozzle plate. the The melted glass that has run together is then transported at a speed greater than the flow rate withdrawn from the melt. In order to divide the converged on the underside of the nozzle plate Allow melt into individual threads ZU is a temperature control on one in the known method Intermediate plate provided. By combining air cooling with a precisely regulated glass temperature ature and a controlled disc temperature then becomes an asymptotic geometry of the thread-forming Cone reached.

The object of the invention is to start up a spinning process for glass fibers, in which a spinneret plate is provided with a large number of openings per unit area, to facilitate.

ίο The task is through the in claim 1 specified procedure solved.

In the method according to the invention, glass is made in a melting furnace, for example a port furnace or furnace melted. There is a special flat spinneret at the bottom of the port furnace arranged. The spinneret plate must be made of a material that has a contact angle of 60 ° or more, preferably 90 "or nithr, for having molten glass

The contact angle of the material to the molten glass is measured as follows. A small glass bead (0.1 to 0.2 g) is placed on a flat plate made of the material to be tested; then the plates and the glass bead are placed in an oven - the plate being arranged horizontally - and held there at a constant temperature of 1100 to 1200 ^° C. for 1 hour. Then they are taken out and quenched with air. They are then photographed from an exactly lateral direction. Then the

jo contact angle measured. The one after this deterrent The measured contact angle is almost the same as the contact angle at high temperatures.

When the contact angle with the molten glass is 90 degrees or more, the material is used as a material

π defined with non-wetting I, property; if the Contact angle is 60 ° or more and less than 90 °, the material has poor properties.

The materials having a contact angle of 90 ° or more with the molten glass are particularly preferred materials for making nozzle plates for the present invention. Examples of such materials are graphite (150 °, measured at 1100 ° C), boron nitride (130 °. ^C measured at 1100 C), and the like. The materials with a contact angle of 60 ° or more and less than 90 "to the molten glass are certain platinum-rhodium-gold alloys or gold-palladium alloys.

The spinneret plate has a large number of openings per unit area, so that from the

ίο coherent molten glass emerging from openings Forms glass beads. The distances between the individual openings in such a plate are 5 mm or less. preferably from 0.5 to 2.5 mm. Since the diameter of an opening is generally from

r> 0.1 to 2.0 mm, the number of openings per unit area in the spinneret plate is preferably 25 to 200 per cm ² . Since the number of openings per unit area in known spinneret plates made of a platinum-rhodium alloy is around 2.4 per cm ²

bo, the value of 25 to 200 openings per cm ^{2 means} 10 to 80 times the known value.

In contrast to this, the combined, molten glass beads easily separated into single strands Wefdeh, and it can end of the individual threads can easily be found, since the material of the Spifmdüsetiplatte is made of one material with non-wetting or hardly wetting property exists, and since the combined melted

Glass beads gradually from the lower surface of the Spinneret are drawn.

When spinning glass fibers using a spinneret plate made of a material with a Contact angles of 90 "or more to the molten glass, i.e. made of a material with non-wetting Property and provided that the distances between each opening are 5 mm or less the following procedure can be used. As the number of openings per unit area is very large, and since molten glass is itself slightly wetted, every molten glass bead that flows out of the openings spreads to the underside of the Spinneret plate and merges with the others, so that the whole area of the underside is flooded. Since the spinneret plate is non-wetting to molten glass, the molten Glass that has flooded the entire underside of the spinneret plate to each periphery of the orifice withdrawn and thus easily divided into filaments when the molten glass increases with it Viscosity at a rate greater than the rate of outflow of the molten glass the furnace is pulled down. The greater the viscosity of the molten glass, the The underside of the spinneret plate is covered, the easier the separation into individual threads can follow. To this This way, the respective end of each thread can be easily found.

If the separation into individual threads takes place to an insufficient extent, an air current opens up the glass melt is blown on the underside of the spinneret plate to cool it down and increase the viscosity of the to increase the molten glass. In this way the end of the single;) threads can easily be r> being found. When the separation into individual threads has been achieved, and constant winding of the Threads can occur, the blowing of air is stopped.

A graphite or boron nitride spinneret plate is 4ii known plates far superior in terms of wettability and can be used for spinning glass fibers under Making great products the easy way to use. A spinneret plate made of a platinum-rhodium-gold alloy with a τ> Contact angle of 60 ° or more to the molten glass shows excellent properties as to of strength, durability. Oxidation resistance and the like and can be used for constant spinning of Use glass fibers over a long period of time-> o be det. On the other hand, a spinneret plate made of graphite or boron nitride is one of the above Alloy a little inferior in durability, but non-wetting since the former Has properties, it has many advantages, such as v> for example, ease of operation, low manufacturing cost, and the like.

The following examples further illustrate the present invention. ho

example 1

A nozzle plate made of graphite with 87 openings of 1.0 mm diameter - the number of openings being 29 per cm ² - was placed at the bottom of a known harbor furnace. E ^ GIas was used for spinning the glass - 0.3 g / Min, molten glass made of every molten glass bead flowing out of each opening was combined with the others and then flooded the underside of the nozzle plate as the viscosity of the glass increased. Then, the molten glass covering the underside was pulled downward at a rate greater than the rate of flow of the molten glass out of the furnace. The combined, molten glass beads were thereby separated into individual threads; In addition, the respective end of the individual threads could easily be found in this way. The threads were wound up at a speed of 1000 m / min. Glass threads with a diameter of 13 μm were obtained. The spinning temperature was 1120 ⁰ C. The contact angle between the molten glass unc the graphite was 150 ° at 1100 ⁰ C.

If a spinneret plate made of graphite with 400 openings of 1.0 mm diameter is used, the number of openings being 36 per cm ² , the same method is used at a winding speed of 500 m / min. Glass threads of the same fineness.

Example 2

When a spinneret plate made of boron nitride was used instead of the graphite and the procedure described in Example 1 was repeated, the same results as in Example 1 were obtained. The contact angle between the molten glass and the boron nitride was 130 ° at 1 RO ⁰ C.

Example 3

There were spinneret plates made of a platinum-rhodium-gold alloy (Composition: Pt 85.5% by weight. Rh 9.5% by weight and Au 5% by weight) with Openings of 1.3 mm diameter were used, the number of openings being those given in Table 1 Showed values. Each spinneret plate was placed at the bottom of a well-known port furnace and that Spinning of the glass fibers was carried out according to Example 1, using E-GIas. the end molten glass poured out from each opening at a rate of about 0.6 g / min. Each from each opening outflowing molten glass bead was bonded together so that the beads are the underside of the Covered spinneret plate. Then the molten glass covering the bottom was coated with a is withdrawn at a rate greater than the rate of outflow of the molten glass. the The melted glass that had run together was separated into individual threads, and the end of each Threads could be found easily. The threads grow at speeds of 1000 to 3000 m / Min. Wound, the exact values are given in Table 1. That way were Glass threads with diameters of 6 to 10 μίτι obtained, as it is inclined in Table 1.

Table I.

approach number number Winding Spinning Fine No. the the speed win tempera Ness openings openings age door per cm ² (m / min.) Cc) (μπι) 1 100 29 3000 1160 10 2 400 36 3000 1160 10 3 800 45 2000 1150 8th 4th 2000 45 1000 1140 6th

The contact angle between the molten glass and the platinum-rhodium-gold alloy was 76 ° at 1200 ⁰ C. When an air stream having a Geschwindigktit of 10 to 50 l / min, to the underside of the spinneret plate covering together overflowed molten glass was blown for cooling, While the ends of the individual threads were being found, the separation of the molten glass into individual threads could be carried out more easily than if no air was blown in. The air stream was blown in in the direction of the openings, so that in this way the minisks of the molten glass emerging from the openings could be effectively cooled. The blowing of air was stopped after constant winding of the threads had started.

Example 4

When using a spinneret plate made of a gold-palladium alloy (composition: Au 80 % By weight and Pd 20% by weight) were glass fibers in the same manner as in Example 3, batch No. 1, 2 and 3 described, spun. Almost the same results were obtained as in Example 3, batch no. 1,2 and 3 received. The contact angle between the

molten glass and the gold-palladium alloy was 82 ° at 1200 ⁰ C.

Comparative experiment

A platinum-rhodium alloy, as it is widely used for the production of spinning nozzle plates, has a contact angle to the glass melt of 32 ° at 1200 ⁰ C. Using a spinneret plate from the platinum-rhodium alloy was the spinning of glass fibers in the same Way as described in Example 3, batch no. 2, tried. Since the PIai: n-rhodium alloy has wetting properties for the molten glass, it was very difficult to separate into filaments and constant spinning of the glass fibers could not be achieved.

As is clearly evident from the above examples, according to the invention it is not only possible to spin glass fibers in a constant manner, but it is also possible to produce very fine glass fibers in a simple manner, since the ends of the individual threads can be found according to dent The method of the present invention is simple. It is also possible to increase the production of the glass fibers by 10 to 80 times compared to known processes when a spinneret plate of the same size as is used in known processes is used.

Claims (4)

Patent claims: 1. Method for starting a spinning process in which glass melts from a flat glass plate exits downwards and the underside of the nozzle plate is flooded, then the converged one Melting glass at a speed greater than the outflow speed of the Melt is withdrawn, the melt being divided into individual threads, characterized in that that a spinneret plate made of a material is used which has a contact angle of 60 ° or more to molten glass. 2. The method according to claim 1, characterized in that that one uses a spinneret plate made of a material with a contact angle of 90 degrees or more to the molten glass. 3. The method according to claim 1, characterized in that a spinneret plate is used, made of graphite or boron nitride. 4. The method according to claim 1, characterized in that the spinneret plate has ^{25 to 200 openings per cm 2.}