JP2000103635A - Nozzle tip for producing flat glass fiber and glass fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle tip designed to have a molten glass pool above the orifice hole provided at the bottom and having the ratio of the major axis to minor axis of a specified value or greater so as to efficiently produce glass fiber with modified cross section of high flatness ratio. SOLUTION: This nozzle tip 1 has such a design that, the bottom face thereof is provided with an orifice hole 2 of rectangular or ellipsoidal shape or of shape approximate thereto for the purpose of affording modified cross-section glass fiber with a flatness ratio of as high as >=2.0, the ratio of the major axis to minor axis for the orifice hole is set at (1:2.5) or greater; above the orifice hole 2, there is furnished a molten glass pool 3 in order to stabilize molten glass flow and the flat shape of the aimed glass fiber, and the cross-section area of the pool is pref. 1.5-8 times the area of the orifice hole 2 and the depth of the pool pref. 2-6 mm; and it is preferable that the projected height from the lower surface of the nozzle plate of this nozzle tip 1 is set at pref. 3-6 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bushing nozzle plate capable of producing glass fibers having a deformed cross section with a high flatness ratio in a high yield, a method of manufacturing the nozzle plate, and flat glass fibers spun from the bushing. It is about.

[0002]

2. Description of the Related Art Glass fibers having a ratio of a major axis to a minor axis of 2 or more and having a substantially rectangular cross section increase the strength of a resin product containing the fibers, increase the smoothness of the surface, and reduce warpage and twist. It reduces the vibration damping effect and increases the strength of the glass non-woven fabric even if the amount of binder is small, and has the effect of increasing the packing density and being able to be used as a substitute for glass cloth. Efficient industrial production is desired. However, the conventional manufacturing method has various problems, and its production capacity is not sufficient compared with demand. As a conventional manufacturing method, for example, Japanese Patent Application Laid-Open No. 1-266937 discloses a method of manufacturing a nozzle plate in which a number of nozzle tips having straight holes having various cross sections are arranged. To draw molten glass from the hole provided in the nozzle tip, the length of the hole is long by the height of the nozzle and the resistance is large, so the outflow of molten glass is reduced compared to the orifice provided in the flat bushing plate However, in order to sufficiently increase the spinning speed, it is necessary to increase the size of the holes. However, there is a problem that it is difficult to control the discharge amount of the molten glass when the size of the hole is large. Also, Japanese Patent Application Laid-Open Nos. Hei 6-228806 and Hei 7-122603 filed by the present inventors.
No. 3 and Japanese Patent Application Laid-Open No. Hei 7-133132 disclose a technique relating to a nozzle tip having a rectangular hole cross section and an orifice having projections on both short sides of the rectangular hole. However, it has been difficult to stably produce a large amount of flat glass fibers even with a bushing plate having a large number of holes having these shapes.

[0003]

The molten glass spun from orifice holes and nozzle tip holes for the production of glass fibers generally has a low viscosity and a large surface tension, and therefore has a strong tendency to immediately become circular in cross section. In the nozzle tip disclosed as the prior art, the aspect ratio is 2.
Flat glass fiber of stable quality of 0 or more is 1500 m /
When spinning at a high speed of min or more, there is a problem that many yarn breaks occur and the cross-sectional shape becomes unstable. In the present invention, the ratio of the cross-sectional area of the flat glass fiber to the rectangular area in which the cross-section of the flat glass fiber is inscribed (hereinafter referred to as the filling rate) is preferably 85% or more, with the flattening ratio being 2.0 or more by improving the shape of the nozzle tip. The present invention enables stable production of flat glass fibers of 90% or more at a high speed.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have found that molten glass flowing into a nozzle tip portion undergoes a rapid change in flow at an inflow port, and that the length of a straight hole is too long to be discharged. It has been found that factors such as preventing the increase in the amount and insufficient cooling of the molten glass when the length is short are preventing the high-speed stable production of flat glass fibers. In order to solve these problems, the structure of the nozzle plate provided on the nozzle plate (plate on which a large number of nozzle chips are provided) of the present invention is changed to a structure in which a molten glass reservoir is provided above an orifice hole on the bottom surface of the nozzle chip. By making the shape, the outflow amount of the molten glass and the cross-sectional shape of the flat glass fiber are stabilized in the high-speed spinning.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The shape of a nozzle tip may be a cylindrical shape or the like as long as it has a desired nozzle hole, but first, the external shape should be a rectangular parallelepiped or a similar shape. Since it is possible, a large number of nozzle tips can be arranged in a limited number of nozzle plates in an orderly and dense manner. The arrangement is the same as the arrangement of the conventional nozzle tips, and no special conditions are required. Further, since the shape is simple, the production of the nozzle tip plate is not limited to the method of attaching the nozzle tip to the nozzle plate by welding, but is generally performed by machining such as a commonly used milling machine, end mill or the like, or by electric discharge machining. There is an advantage that it can be easily produced from a plate made of steel. An orifice hole is provided on the bottom surface of the nozzle tip. Its shape is an aspect ratio of 2.0
In order to obtain the above-mentioned highly flat irregular-shaped glass fiber, a rectangle or an oval (the shape of the hole provided in the nozzle in the present invention, or the oval representing the cross section of the flat glass fiber is a semicircular shape at both ends of the rectangle) , Or a shape similar to it), elliptical, dumbbell-shaped, or a shape similar to these, with its short side and long side or the longest short diameter and longest long diameter (hereinafter short side, longest shortest) The ratio of the short diameter including the diameter, the long side, and the long diameter including the longest long diameter is 1: 2.5.
As described above, the ratio is preferably 1: 4-1: 8. When the ratio is 1: 2.5 or less, it is difficult to obtain a glass fiber having an aspect ratio of 2.0 or more,
If the ratio is 1: 8 or more, it is difficult to produce fibers efficiently. The minor diameter of the orifice hole varies depending on the thickness of the orifice hole, but it is preferably at least 0.3 mm, and more preferably at least 0.5 mm. The upper limit of the minor diameter is the same as that of a normal glass fiber nozzle tip having a circular cross section.

In the upper part of the orifice hole of the nozzle tip,
A pool of molten glass is provided for stabilizing the flow of the molten glass and for stabilizing the flat shape. The cross section is 1.5 times or more the area of the orifice hole,
Preferably, it is eight times. 1.5 times or less
The difference from the conventional nozzle tip with no glass reservoir is small, and when it is 8 times or more, a dead zone is formed in the glass reservoir, a high-viscosity molten glass is easily generated, the spinning is stabilized, and the cross section of the flat fiber is formed. Not only does the shape stabilization have an adverse effect, but the cross-sectional area of the nozzle tip having a glass reservoir increases, and the number of nozzle tips that can be arranged in the same area decreases, which is not preferable in terms of production volume. The depth of the portion where the molten glass accumulates is 1-10 mm, preferably 2-6 mm.
mm. If it is less than 1 mm, the effect of providing the pool is not clear. If it is 6 mm or more, the molten glass is cooled too much, and the discharge amount of the molten glass from the nozzle is reduced, and the cross-sectional shape of the flat glass fiber tends to be unstable. The thickness of the orifice hole depends on the shape of the orifice.
It is about -10 mm, preferably about 0.5-4 mm. The projection height of such a nozzle tip from the lower surface of the nozzle plate is 1-10 mm, preferably 3-6 mm. 1m
If it is less than m, the cooling effect is not clear, and if it is more than 10, the viscosity of the glass increases due to the cooling effect, and the cross-sectional shape of the flat glass fiber tends to become unstable.

In a nozzle tip having a glass reservoir above the orifice of a round nozzle, a cylindrical or conical reservoir having the same central axis is generally provided. However, in the present invention, the long diameter of the orifice hole is long. In order to make the distribution of the outflow amount suitable for the cross-sectional shape to be manufactured, the shape is not the same as the outlet shape, for example, if the orifice hole is oval, change the shape of the pool such as a rectangular inflow hole, dumbbell shape, etc. This makes it possible to control the cooling of the glass in the nozzle. Specific molten glass pool shape,
The dimensions, the minor diameter and major diameter of the orifice hole, and the shape are as follows: the thickness of the orifice hole, the type of molten glass, the temperature, the winding speed of the glass fiber, the flattening ratio of the flat glass fiber to be manufactured, the converted fiber diameter (flat glass It varies greatly depending on spinning conditions and product quality, such as the cross-sectional area of the fiber converted to a circular cross-sectional area, and can be determined by experience or experiment. Even by simply providing the flat glass fiber orifice hole of the present invention at the tip of the nozzle tip provided with such a molten glass reservoir, stable high-speed spinning becomes possible, and the production efficiency is significantly improved as compared with the prior art. You.

However, if the outer shape of the orifice hole provided on the bottom surface of the nozzle tip is appropriately processed to suppress the force of the molten glass drawn from the hole to curl due to surface tension, the cross-sectional shape is further increased. The effect of stabilization can be increased. One of the shapes has a width not exceeding the maximum width of the minor axis of the orifice hole along the center line of the orifice hole and a depth of 0.1-2.0 mm, preferably from end to end of the nozzle tip. Is 0.3-0.5mm
Orifice having a concave groove. The effect is small at 0.1 mm or less, and there is no difference in the effect at 2.0 mm or more.
The molten glass spreads in this groove and exerts the action of pulling the thin ends of the molten glass spun from the orifice hole from both sides, suppressing the force of curling by surface tension and stabilizing the cross-sectional shape of high flat glass fiber It is to make it. Another shape is one in which convex edges are provided at both ends so as to sandwich the long diameter of the orifice hole disclosed in Japanese Patent Application Laid-Open No. Hei 7-126033, and the molten glass spun from the orifice hole has a convex edge. It spreads along the surface and suppresses the force of curling due to the surface tension of the glass, creating a force to pull the glass to the left and right, and plays a role of high flattening. The width of the surface of the convex edge in contact with the molten glass is from 0.3 mm to the full length of the short side of the nozzle tip, preferably 0.5 mm or more. 0.3
If it is less than mm, the pulling force is weak. The height of the portion in contact with the molten glass is 0.1-3 mm, preferably 0.3-
1.0 mm. Less than 0.1mm has little effect,
If it is 3 mm or more, the spinning is adversely affected.

Further, the opening at both ends of the orifice provided with a groove or a convex edge is widened, for example, in the form of a dumbbell, and the effect of suppressing the flat ends of the molten glass fibers from gathering at the center is obtained. Yes, the aspect ratio will further rise.

Regarding the thickness of the glass fiber that can be manufactured by the nozzle tip of the present invention, various conversion fiber diameters can be manufactured by setting the manufacturing conditions. However, those having a shortest diameter of 1.0-25 microns and a longest diameter of 2.0-300 μm in the cross section are preferable for production. If it is too thin, spinning of the glass fiber itself is difficult, and if it is too thick, the contact area with the resin is reduced, and the reinforcing effect is reduced. By adopting the nozzle tip configuration as described above and selecting the spinning conditions by trial and error while spinning, the filling rate can be 85% or more. Compared to the conventional flat glass fiber having a cross section close to an ellipse with a filling factor of about 78%, a high flat glass fiber can be manufactured. Therefore, when used as a paper material, the surface has a smooth surface and a large bulk density. When used in injection molding, the strength of the glass fiber has a large tear strength, the warp and twist are greatly reduced, and a product with a smooth surface can be obtained. Products can be manufactured.

[0011]

Example 1 400 rectangular parallelepiped nozzle tips were cut out on a single nozzle plate. Each of the nozzle tips has an oblong orifice hole having a minor axis: major axis of 1: 6.5 and a thickness of 1.65.
5 mm, the upper portion of the molten glass reservoir is an ellipse whose major axis is 1.3 times the major axis of the orifice hole, whose minor axis is 3.75 times the minor axis of the orifice hole, and whose area is 4.9 times longer. This is a shape in which the area of the inflow portion of glass, which is 0.83 times the minor axis, is larger than the orifice area. Spinning temperature 1200 ° C,
The spinning was performed at a spinning speed of 3000 m / min. The cross section of the spun filament was a glass fiber having an oval stable shape. The flattening ratio is 3.0, the flattening efficiency (the ratio of the flattening ratio of the flat glass fiber / the major axis / the minor axis of the orifice hole) is 46.1%, and the filling rate of the flat glass fiber (the sectional area of the flat glass fiber / The area of the rectangle that inscribes it) is 9
It was 0%. (See Fig. 1)

Example 2 A nozzle plate having 400 nozzle tips similar to that of Example 1 was manufactured, and a 1/1 of the minor diameter of the orifice hole was formed on the bottom of the width along the center line of the major axis of the orifice at the tip of the nozzle tip.
A nozzle tip having a width of 2 and a depth of 1.25 times the groove width was cut to form a nozzle tip, and spinning was performed at a spinning temperature of 1200 ° C. and a spinning speed of 3000 m / min. The cross section of the spun filament was a stable glass fiber having an oval shape. The average flattening ratio is 1: 3.4, and the flattening efficiency is 52.3.
%, And the filling factor of the flat glass fibers was 93.5%.
(See Fig. 2)

Example 3 In Example 1, a nozzle plate having an orifice hole thickness of 2.0 mm and 400 nozzle tips was used.
The thickness, width, and height of the orifice hole are 0.625 and 3.7, respectively, with respect to the minor diameter of the orifice hole so as to sandwich the major axis of the orifice hole at the tip of the nozzle tip.
5, a nozzle tip having a convex edge of 0.625 was prepared, and a spinning temperature of 1200 ° C. and a spinning speed of 3000 m / min.
Was spun. The cross section of the spun filament was a stable glass fiber having an oval shape. The flattening ratio is 3.8, the flattening efficiency is 58.5%, and the flat glass filling rate is 9
It was 4.1%. (See Fig. 3)

Example 4 A nozzle plate having 400 nozzle tips similar to that of Example 3 was manufactured, and orifice holes at the tip of the nozzle tip were provided at both ends with a hole having a diameter of 1 / 5.2 of the major axis, and a gap between them. A dumbbell-shaped orifice hole whose major axis was 5.2 times the maximum minor axis connected by a slit having a width of 1 / 8.7 of the major axis was provided. Example 3 Contacting both ends of a dumbbell-shaped orifice hole
A nozzle tip provided with a convex edge having the same dimensions as those used in the above was prepared, and a spinning temperature of 1200 ° C. and a spinning speed of 3000 m /
The spinning was performed at min. The cross section of the spun filament was a stable glass fiber having an oval shape. The flattening ratio was 4.2, the flattening efficiency was 64.6%, and the filling rate of flat glass fibers was 94.1%. (See Fig. 4)

Comparative Example 1 400 rectangular parallelepiped nozzle tips were cut out on one nozzle plate, and the short diameter was 1.0 mm and the long diameter was 6.5 m.
m, a nozzle tip provided with an oval orifice hole having a protruding portion having a length of 2.8 mm was prepared.
The spinning was performed at a spinning speed of 2000 m / min. A stable glass fiber having an elliptical cross section was obtained. The flattening ratio is 1.6 and the flattening efficiency is 24.6%
Met. The filling rate of the flat glass fibers was 79.5%. (See Fig. 5)

[0016]

Although the viscosity of the molten glass inside increases even in a normal nozzle tip due to the cooling effect, the nozzle tip of the present invention has a molten glass in which the flow area of the orifice hole is at least twice as large as the flow area. By providing the reservoir, the flow of the glass inside the nozzle tip is less likely to be disturbed, the viscosity of the glass increases along the inner surface of the nozzle tip, and the molten glass coming out of the orifice hole has a high viscosity on the outer periphery of the cross section, The low-viscosity, low-viscosity glass is sandwiched between the high-viscosity molten glass planes, and the force of returning to a circular cross section due to surface tension is reduced, and flat glass fibers having a stable cross section can be spun at high speed. In addition, since the molten glass reservoir was provided above the orifice hole, the flow was not disturbed and the outflow resistance was small, so that high-speed spinning was possible. Efficient production of high-flat cross-section glass fiber with a stable filling rate of 85% or more by forming grooves or edges with orifice holes similar to rectangular, oval, oval, and dumbbell shapes. can do. Further, according to the present invention, since the shapes of the nozzle tip, the orifice hole, and the molten glass pool are simplified, general machining and electric discharge machining are possible, and there is also an economic advantage that the production cost of the nozzle plate is small. .

[Brief description of the drawings]

FIG. 1 Nozzle having a molten glass reservoir above the orifice hole

FIG. 2 is a nozzle having a groove connected to the orifice hole of FIG.

FIG. 3 is a nozzle having a convex edge in an orifice hole of FIG.

FIG. 4 is a nozzle in which both ends of the orifice hole in FIG. 1 are circular holes thicker than the width of the orifice.

FIG. 5 is a drawing showing nozzles without molten glass pool (a), (b), and (c) in each of the above drawings, where (a) is the upper surface, (b) is the cross section, and (c) Is a diagram showing a lower surface.

[Explanation of symbols]

 1, nozzle tip 2, orifice hole 3, molten glass pool 4, groove 5, convex edge

Claims (6)

[Claims] 1. A nozzle tip comprising a molten glass reservoir above an orifice hole having a ratio of a minor axis to a major axis of 1: 2.5 or more provided on the bottom surface of the nozzle tip. 2. The method according to claim 1, wherein the ratio of the area of the orifice on the outflow side to the area of the inflow portion of the molten glass reservoir provided above the nozzle tip is 1: 1.5-1: 8. Nozzle tip. 3. From the end of the tip surface of the nozzle tip to the end,
2. The nozzle tip according to claim 1, further comprising a concave groove having a width not exceeding a maximum width of a minor axis of the orifice hole along a center line of the orifice hole. 4. The nozzle tip according to claim 1, wherein the nozzle tip has a convex edge sandwiching the orifice hole at both ends of the major axis of the orifice hole. 5. The nozzle tip according to claim 3, wherein the width of the opening at both ends of the major axis of the orifice hole of the nozzle tip is wider than the width of the central portion. 6. An oblate ratio (major axis / minor axis) obtained by spinning from the nozzle tip of claim 1 is 2.5 or more, and the obtained flat glass fiber cross section is inscribed in a rectangular area. The flat glass fiber, wherein the cross-sectional area of the flat glass is 85% or more.