JPH0346412B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hollow glass fiber spinning method and apparatus.

Glass fiber is produced in the highest volume among man-made inorganic fibers, and its utilization technology is also advanced, but it has drawbacks such as higher density and lower modulus of elasticity compared to carbon fiber, whose production volume has recently increased rapidly. Therefore, hollow glass fibers were developed to overcome this problem and provide new functions.

Hollow glass fibers may be formed accidentally and locally during spinning of glass fibers, but in this case they are treated rather as defective glass fibers.

Conventionally, in order to make hollow glass fibers, a spinning nozzle 2 is provided at the bottom of a molten glass tank 1 as shown in FIG.
The molten glass 5 in the molten glass tank 1 is fed from the spinning nozzle 2 using a spinning device 4 which is vertically installed in the molten glass tank 1 by inserting the tip of an air introduction pipe 3 into the spinning nozzle 2. At the same time as the molten glass was discharged, air was injected into the molten glass 5 through an air introduction tube 3 to produce hollow glass fibers 6.

By the way, although the hollow glass fiber 6 can be easily obtained in the above-mentioned spinning apparatus 4, it is extremely difficult to attach the air introduction tube 3, and the vertical air introduction tube 3 may be misaligned with the spinning nozzle 2 or tilted during high-temperature operation. This makes the device 4 unstable, and it is difficult to provide a large number of spinning nozzles 2 at the bottom of the molten glass tank 1, and furthermore, constant monitoring is required for operation and maintenance. Therefore, it is not suitable for mass production, the hollow glass fibers 6 obtained are expensive, and some are of poor quality.

Therefore, prior to developing a device to replace the spinning device 4 for hollow glass fibers 6, the present inventors conducted a detailed investigation on the outflow behavior of molten glass near the spinning nozzle 2 in the spinning device 4, and found that The following was discovered.

(1) The molten glass 5 at the upper center of the spinning nozzle 2 flows fastest.

(2) The flow velocity lines are congested outward from the center of the spinning nozzle 2. Here, the flow velocity line indicates that the flow of the molten glass 5 in a minute region (layer) changes with time,
The molten glass 5 located in the center of the glass flows out the fastest, and those on the outside flow slower.

(3) Within a distance corresponding to the nozzle diameter at the top of the spinning nozzle 2, the part where the molten glass 5 is flowing fastest is at a position about 1/3 of the nozzle diameter.

Therefore, it has been found that the hollow glass fibers 6 can be easily created by blowing air into the fastest flowing portion of the molten glass 5. That is, it has been found that when the liquid depth of the molten glass 5 is maintained at about the nozzle diameter, the hollow glass fibers 6 can be easily created simply by drawing out the molten glass 5. However, the optimum liquid depth varies depending on the nozzle shape, but in general, it depends on the nozzle diameter.
10 times or less.

On the other hand, when the liquid depth of the molten glass 5 is made shallow, the liquid pressure becomes small, the outflow force of the molten glass 5 becomes small, and it becomes difficult to continuously spin the hollow glass fibers 6.

The present invention has been made with attention to the above points, and consists of forming a thin layer of molten glass by continuously and gradually causing molten glass to flow down using its own hydraulic pressure or pressure adjustment from the outside, and forming a thin molten glass layer. It is an object of the present invention to provide a method and apparatus for spinning hollow glass fibers by drawing out molten glass from a layer and injecting air.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method and apparatus for spinning hollow glass fibers according to the present invention will be explained below with reference to the drawings. First, an example of a spinning device for carrying out the spinning method is shown in Figure 2 a and b.
10 is a large amount of molten glass 5
This molten glass tank 1 holds
A plurality of molten glass flowing down nozzles 11 (four in this example) are provided at equal intervals in the front, back, left and right at the bottom of the nozzle.
Below this molten glass flowing down nozzle 11, it has the same planar area as the molten glass tank 10 and is connected to it by a peripheral wall, and on the bottom surface there are a plurality of spinning nozzles 13, nine in this example, located at the projected position of the molten glass flowing down nozzle 11. Trays 12 are provided at regular intervals at diagonal positions around the periphery of the glass to form a thin layer of molten glass. An air layer forming tank 14 is formed around the molten glass downstream nozzle 11 by a peripheral wall connecting the molten glass tank 10 and the tray 12, and an air introduction pipe 15 is communicated with the air layer forming tank 14.

Next, a spinning method of the present invention using the spinning device 16 having such a structure will be explained. Molten glass tank 10
The molten glass 5 held in the molten glass 5 is continuously and gradually flowed down from the molten glass flow down nozzle 11 at the bottom of the molten glass tank 10 by its own hydraulic pressure or pressure adjustment from the outside and received on the tray 12. is formed into a certain thin molten glass layer 18, and then the molten glass 5 is drawn out from this thin molten glass layer 18 through the spinning nozzle 13, and the molten glass is drawn out by the peripheral wall connecting the molten glass tank and the tray by the suction pressure generated by the drawing. Air in the air layer forming tank 14 formed around the downstream nozzle is drawn in to spin hollow glass fibers 19.

Note that it is preferable to actively supply air into the air layer forming tank 14 to balance it with the liquid pressure of the molten glass tank 10. However, the part that holds the air layer does not have to be a closed space, but may be a space that is open to the atmosphere. By creating a closed air layer, the liquid pressure of the molten glass can be directly transmitted to the molten glass flowing out from the nozzle, making spinning easier. However, as long as a thin molten glass layer that is sufficiently controlled by the liquid pressure of the molten glass can be spun, the air layer may be open to the atmosphere.

The hollow glass fiber 19 spun as described above is
The wall thickness is almost uniform all around, with almost no misalignment on the inner and outer circumferential surfaces, and the wall thickness is almost uniform all the way along the entire length, with almost no locally thin areas, and dimensional accuracy. It is of good quality.

In order to clarify the effects of the hollow glass fiber spinning method of the present invention, specific examples and conventional examples thereof will be described.

Example 1 Platinum spinning device 1 having the structure shown in FIGS. 2a and 2b
In step 6, the dimensions of the molten glass tank 10 are 100 mm in length and 100 mm in width.
100 mm rectangular cross section, height 150 mm, molten glass falling nozzle 11 diameter 4.0 mm, length 7.0 mm, tray 12 depth 10 mm, spinning nozzle 13 diameter 2.0 mm, length 0.5
The molten glass 5 made of E-type glass is spun into hollow glass under the following spinning conditions using the spinning device 16 in which the height of the air layer forming tank 14 is 7.0 mm, and the inner diameter of the air supply pipe 15 is 4.0 mm. Fiber 19 was obtained.

Spinning conditions Molten glass temperature 1260℃ Spinning nozzle temperature 1050℃ Molten glass liquid depth 40mm Thin molten glass layer 3mm Spinning speed 500m/min Obtained hollow glass fiber diameter 14μm Hollowness ratio 25% Wall thickness Maximum 5μm, minimum 3μm Example 2 Using the same spinning device 16 as in Example 1, molten glass 5 made of E-type glass was spun under the following spinning conditions to obtain hollow glass fibers 19.

Spinning conditions Molten glass temperature 1260℃ Spinning nozzle temperature 1050℃ Molten glass liquid depth 40mm Thin molten glass layer 3mm Spinning speed 800m/min Obtained hollow glass fiber diameter 12μm Hollowness ratio 30% Wall thickness Maximum 4μm, minimum 2μm Example 3 In order to change the liquid depth of the thin molten glass layer 18, only the length of the molten glass flowing down nozzle 11 was changed to 5.0 mm, and the other dimensions were the same as in Example 1.
A hollow glass fiber 19 is obtained by spinning molten glass 5 made of E type glass under the following spinning conditions using
I got it.

Spinning conditions Molten glass temperature 1250℃ Spinning nozzle temperature 1050℃ Molten glass liquid depth 100mm Thin molten glass layer 5mm Spinning speed 800m/min Obtained hollow glass fiber diameter 13μm Hollowness ratio 20% Wall thickness Maximum 4μm, minimum 3μm Conventional example No. In the spinning device 4 made of platinum having the structure shown in Fig. 1, the molten glass tank 1 has a rectangular cross section with a length of 50 mm and a width of 50 mm, a height of 100 mm, a diameter of the spinning nozzle 2 of 4.0 mm,
Length 5.0mm, opening diameter 2.0mm, diameter of air introduction pipe 3 1.0
A hollow glass fiber 6 was obtained by spinning a molten glass 5 made of E type glass under the following spinning conditions using a spinning device 4 having a diameter of 2 mm.

Spinning conditions Molten glass temperature 1260℃ Spinning nozzle temperature 1050℃ Spinning speed 500m/min Obtained hollow glass fiber diameter 20μm Hollowness ratio 13% Wall thickness Maximum 9μm, minimum 5μm Hollow glass of Examples 1, 2, and 3 as described above It can be seen that the fibers have a smaller fiber diameter and a higher hollowness ratio than the conventional hollow glass fibers, have a substantially uniform thickness with very little variation in wall thickness, have high dimensional accuracy, and are of good quality.

The molten glass flowing down nozzle 11 and the tray 12 of the spinning device 16 of the above embodiment are different from the molten glass tank 1.
0, but as shown in FIG. 3, a guide part 20 is provided on the side of the molten glass tank 10 and the bottom, a molten glass flowing down nozzle 11 is provided at the bottom of this guide part 20, and a tray 12 is provided below the guide part 20. It is also possible to provide an air layer forming tank 14 around the molten glass flowing down nozzle 11.

As can be seen from the above explanation, according to the hollow glass fiber spinning method of the present invention, it is possible to produce hollow glass of good quality with high dimensional accuracy, which has a small fiber diameter, a high hollowness ratio, and a substantially uniform wall thickness over the entire circumference and length. It has the excellent effect of being able to easily obtain fibers.

Further, the hollow glass fiber spinning apparatus of the present invention has a simple structure, is easy to manufacture, is inexpensive, and is easy to maintain. Moreover, it has advantages such as easy addition of spinning nozzles, suitable for mass production, and extremely easy operation control.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a conventional hollow glass fiber spinning device, FIG. 2 a is a vertical cross-sectional view showing an example of the hollow glass fiber spinning device of the present invention, and FIG. 2 b is a
FIG. 3 is a longitudinal sectional view showing another example of the hollow glass fiber spinning apparatus of the present invention. 5... Molten glass, 10... Molten glass tank, 1
1... Molten glass flowing down nozzle, 12... Tray,
13...Spinning nozzle, 14...Air layer forming tank, 1
5... Air supply pipe, 16... Spinning device, 17...
Air layer, 18... Thin molten glass layer, 19... Hollow glass fiber.

Claims (1)

[Claims] 1. Thin molten glass by continuously and gradually flowing down molten glass held in a molten glass tank from a molten glass flow down nozzle at the bottom of the molten glass tank using its own hydraulic pressure or pressure adjustment from the outside. A layer is formed, and then the molten glass is drawn out from this thin molten glass layer through a spinning nozzle, and air in an air layer forming tank formed by a peripheral wall connected to the molten glass tank is injected to spin hollow glass fibers. A method for spinning hollow glass fibers. 2. A molten glass tank holding multiple pieces of molten glass, a plurality of molten glass flow down nozzles provided at the bottom of this molten glass tank, and a peripheral wall connected to the molten glass tank provided below the molten glass flow down nozzles. an air layer is formed by a tray in which the molten glass is placed, a plurality of spinning nozzles provided on the bottom of the tray at equal intervals at diagonal positions around the projected position of the molten glass flowing down nozzle, and a peripheral wall connecting the molten glass tank and the tray. A hollow glass fiber spinning device comprising a tank and an air introduction pipe communicating with the air layer forming tank.