JPS60204635A - Manufacture of ultrafine roller - Google Patents

Abstract

PURPOSE:To manufacture an ultrafine roller having a relatively uniform length with high productivity without dusting, by giving a sudden temperature change to crush conjugate glass fibers consisting of plural kinds of glass of cross section having different thermal expansion coefficients. CONSTITUTION:Glass having a low thermal expansion coefficient is placed in the inside of a crusible 1 of double structure, and glass having a high thermal expansion coefficient is placed on the outside thereof. Both are melted under heating in an electric furnace 2, and drawn to give a conjugate glass fiber 3 of cross section consisting of a glass part (3a) having the low thermal expansion coefficient and a glass part (3b) having the high thermal expansion coefficient. The resultant conjugate glass fiber 3 is then wound onto a capstan 4 in a thermostatic chamber 5 kept at the strain point of the above-mentioned glass. A sudden temperature change is given to the above-mentioned conjugate glass fiber 3 by adjusting the temperature thereof to ordinary temperature or above and dipping the glass fiber 3 in a cryogenic liquid to give the aimed ultrafine roller having abot 2-12mu diameter and a length about 3-20 times that of the diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing microscopic rollers used as spacers for liquid crystal cell containers.

[Prior art]

Usually, this type of microscopic roller is made of glass fiber, and has a diameter of 2 to 12 μm and a length of about 3 to 20 times the diameter. When using such microscopic rollers as spacers to maintain the distance between transparent electrodes in a liquid crystal cell container,
Microscopic rollers are mixed into an adhesive and applied to the peripheral area of one transparent electrode, and the other transparent electrode is overlapped and bonded to form a liquid crystal cell container. in this case,
If the length of the microscopic rollers is at least three times the diameter, all the rollers will fall sideways, and the two electrodes will be fixed at an interval corresponding to the diameter of the rollers. In addition, the length of the microscopic rollers is designed to eliminate overlapping of rollers.
It shouldn't be too long either.

Conventionally, such microscopic rollers have been manufactured as follows. The method involves crushing glass fibers of the desired thickness in a mortar, sieving them, and then repeating the crushing and sieving process several times to obtain microscopic rollers of the desired length. be.

However, since this method involves (1) crushing and sieving, it is difficult to make the lengths of the microscopic rollers uniform. ■Dust is generated during crushing, worsening the working environment.

■Crushing and sieving are performed many times, resulting in poor productivity and high costs.

In addition, as a method for manufacturing ultra-fine rollers,
7-60306 proposes the following method. The method involves using multiple glass cores that are circular in cross section and difficult to dissolve in acids, covered with glass coatings that are easily soluble in acids.
It is inserted in parallel into a glass cylinder that is easily soluble in acid, and then heated and fused and stretched in the longitudinal direction to form a long and narrow fused glass body, which is crushed and then the glass covering body and the glass cylinder body are crushed. The corresponding portion is dissolved with acid to obtain microscopic rollers made of the glass mandrel.

However, this method has the disadvantage that the manufacturing process is complicated, such as covering the glass mandrel with a glass covering, putting multiple pieces together in a glass tube, and drawing them under heating, resulting in low productivity and high costs. There is.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a method for manufacturing microscopic rollers that can make the length of microscopic rollers relatively uniform, does not generate dust, and has high productivity. It is in.

[Structure of the invention]

The method for manufacturing microscopic rollers of the present invention that achieves the above object is as follows:
This method is characterized in that a composite glass fiber whose cross section is composed of two or more types of glass having different coefficients of thermal expansion is crushed by applying a sudden temperature change.

In general, when a multi-component glass molded body is subjected to a sudden temperature change, that is, a thermal shock, distortion occurs due to the difference in thermal expansion due to the temperature difference between the inside and the outside, and if the amount of strain exceeds a limit, it will break. However, fibrous glass with an outer diameter of several hundred μm or less,
Because it has a small heat capacity, it easily adapts to temperature changes, and because the amount of strain does not increase, it will not break. However, this only applies when glass fibers are made of a single material; composite structures consisting of a core and cladding, such as those found in optical fibers, are susceptible to thermal shock.

For this reason, in optical fibers, the glass I materials for the core and cladding are selected to have the same or similar thermal expansion coefficients to reduce distortion.

On the contrary, the present invention attempts to manufacture ultra-fine rollers by combining glasses with as large a difference in thermal expansion coefficient as possible to form a composite glass fiber, and then subjecting it to a rapid temperature change to crush it into fine pieces. It is something to do. The composite glass fibers mentioned above are formed by drawing wire from molten glass, but in order to prevent wire breakage during this process, the composite glass fibers that are formed and the capstans that come into contact with them must be It is best to draw the wire while keeping it at or above the strain point temperature of the glass material (the temperature at which no internal strain remains). The strain point temperature is generally around 550C in the case of multi-component glass, but if the strain point temperatures of the glasses used are different, the temperature should be higher than the lower one.

An effective way to apply a rapid temperature change to the composite glass fiber that I received is to immerse the composite glass fiber, which is at least at room temperature or higher after drawing, into a cryogenic liquid such as liquid nitrogen or liquid oxygen. It is.

〔Example〕

As shown in Fig. 1 (a), a double-structured crucible 1 similar to that used for manufacturing optical fibers is used, and the inside is made of glass with a small coefficient of thermal expansion (aluminosilicate α = 4).
0 x 10 mIn/C), the outside is glass with a large coefficient of thermal expansion (soda lime type α”ll0XIQ mm/C)
As a combination of
00, and the fiber was drawn to a diameter of 10 μm. The formed composite glass fiber 3 was wound directly onto a capstan 4, and the capstan 4 and composite glass fiber 3 were kept at 750±20C in a constant temperature bath 5 at all times. The cross-sectional structure of the composite glass fiber 3 thus obtained is as shown in FIG. 3a is a glass portion with a small coefficient of thermal expansion, and 3b is a glass portion with a large coefficient of thermal expansion.

When the composite glass fiber was removed from the capstan while maintaining the above temperature and immediately immersed in liquid nitrogen, the composite glass fiber was crushed into pieces.

After removing the liquid crystals by evaporation, the length of the crushed glass fibers, that is, microscopic collages, was measured using a microscope and most of the results were in the range of 10 to 50 ttm.
, 20 to 30 μm accounted for more than 40 inches. Immersion in liquid nitrogen is an effective method because it allows for a large temperature difference, has a higher specific heat than air, and is easier to dry than water.

When the cross-sectional ratio of the glass portion 3a with a small coefficient of thermal expansion and the glass portion 3b with a large coefficient of thermal expansion of the composite glass fiber is changed, the ratio of the diameter of the inner glass portion 3a to the outer diameter becomes 0.
The range of 6 to 0.8 was most effective for crushing. In addition,
The length of the microscopic rollers is approximately determined by the difference in thermal expansion coefficient and the difference in cooling temperature, and can be controlled by changing them.

Next, for comparison, one angular diameter 10μI made of a single material
n glass fiber, 750 tl? When immersed in liquid nitrogen, the glass fibers were not destroyed.

Next, as shown in FIG. 2, a composite glass fiber 7 was manufactured under the same conditions as in FIG. 1(A) using a crucible 6 whose lower drawer opening was partitioned off with a plate. The cross-sectional structure of the glass fiber 7 is shown in FIG. 2 (b).

γa is a glass portion with a small coefficient of thermal expansion, and 7b is a glass portion with a large coefficient of thermal expansion. When such composite glass fibers were crushed in the same manner as in the previous example, almost the same results were obtained.

〔Effect of the invention〕

As explained above, according to the present invention, composite glass fibers made of glasses with different coefficients of thermal expansion are crushed by applying thermal shock. Since ultra-fine rollers are manufactured, there is an advantage that no dust is generated during crushing, no foreign matter is mixed into the trenches, and ultra-fine rollers with relatively uniform length can be manufactured. Furthermore, since the manufacturing process is simple, productivity is increased and the cost of the microscopic rollers can be reduced.

[Brief explanation of drawings]

Figure 1 (a) is a schematic diagram showing the method for manufacturing composite glass fibers necessary for manufacturing ultra-fine rollers, Figure 1 (b) is a cross-sectional view of the composite glass fiber obtained by the same method, and Figure 2 (i) ) is a schematic diagram showing another example of the method for manufacturing composite glass fibers, and the same figure (
B) The cross section of the composite glass fiber obtained by the same method is 1. 3.7...Composite glass fiber, 3a, 7a...
...Glass part with small coefficient of thermal expansion, 3 b, 7
b...Glass part with a large coefficient of thermal expansion. Figure 1 (a) (b) Figure 2 (a) (b)

Claims (3)

[Claims] (1) A method for producing microscopic rollers, which comprises crushing a composite glass fiber whose cross section is composed of two or more types of glass having different coefficients of thermal expansion by applying a sudden temperature change. (2) The manufacturing method according to claim 1, wherein the composite glass fiber is obtained by drawing the composite glass fiber while maintaining itself and the object with which it comes into contact at a temperature higher than the strain point temperature of the glass used. Items characterized by being made of (3) The manufacturing method according to claim 1, comprising:
The rapid temperature change is achieved by immersing the composite glass fiber at a temperature above room temperature in a cryogenic liquid.