JPH0359019B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing glass fibers having irregular cross-sections such as oval, elliptical, cocoon-shaped, polygonal, etc.

Conventional technology Generally, glass fiber is manufactured by spinning molten glass from a bushing with a large number of circular cross-section nozzle holes to form a large number of filaments, and then collecting and winding these filaments into a strand. , each filament of glass fiber produced has a circular cross-sectional shape. The main use of glass fiber is as a reinforcing material mixed into thermosetting resins, thermoplastic resins, etc. A treatment agent is generally attached to the surface of the glass fiber to provide adhesive strength at the glass-resin interface.

Problems to be Solved by the Invention In recent years, it has been increasingly desired to improve the strength of composite materials containing resin and glass fiber. Additionally, thin strands are now required for long fiber applications such as filament winding, pultrusion, roving cloth, and electric insulation cloth.

As a result of various studies in view of such requests, the present inventors have found that it is important to strengthen the adhesive force between glass fibers and resin in order to improve the strength of composite materials. It has been found that glass fibers having irregular cross-sections such as oval, elliptical, cocoon-shaped, polygonal, etc. can be used instead of the conventional circular cross-section. The reason for this is thought to be that glass fibers with irregular cross sections have a larger specific surface area than those with circular cross sections, and therefore the total adhesive force between the glass fibers and the resin becomes larger, resulting in a greater reinforcing effect. Also,
If the cross-sectional shape has a recess on the outer periphery, the adjacent fibers will fit into the recess, making it difficult for the fibers to separate, resulting in an even greater reinforcing effect. They also discovered that glass fibers overlap flatly to form thin strands. However, glass fibers with such irregular cross sections are extremely difficult to manufacture.
That is, as mentioned above, in the production of glass fiber, molten glass is spun out from a nozzle hole and made into fibers. At this time, since molten glass has low viscosity and high surface tension at high temperatures, even if the cross section of the nozzle hole is Even if the fibers have an irregular cross section, the molten glass spun from the nozzle hole immediately becomes a circular cross section, making it impossible to obtain glass fibers with the desired irregular cross section.

The present invention aims to solve these problems, and aims to provide a method for manufacturing glass fibers having irregular cross-sections such as oval, elliptical, eyebrow-shaped, and polygonal shapes.

Means for Solving the Problems The present invention, which has been made to achieve the above object, provides a nozzle plate having a concave portion on the lower surface, and a plurality of nozzle plates arranged close to each other so as to sandwich or surround the center of the concave portion. at least a part of each nozzle hole opens in the recess, and the opening position on the outflow side of each nozzle hole is such that the side closer to the center of the recess is higher than the side farther from the center of the recess. The method is characterized in that molten glass is spun out from the plurality of arranged nozzle holes, and the spun molten glass is joined together to form a single filament.

Here, the opening position on the outflow side of each nozzle hole is
It means the position where the nozzle hole is opened on the lower surface side of the nozzle plate. In the present invention, the opening position on the outflow side of each nozzle hole is determined to be higher on the side closer to the center of the recess than on the far side. This is not limited to cases where the height gradually increases from the far side to the near side to the center of the nozzle (when the lower end of the nozzle hole is inclined as shown in the embodiment of Fig. 4); This also includes the case where the lower end of the nozzle hole is stepped, as shown in the embodiment.

Function As mentioned above, when molten glass is spun out from multiple nozzle holes and then joined to form a single filament, the temperature of the molten glass at the time of joining has decreased to a certain extent and the viscosity has increased. For this reason, compared to the case where the molten glass is simply spun from a single nozzle hole with an irregular cross section such as an oval or ellipse, there is a weak tendency for the molten glass to deform into a circular shape, and the final shape is an oval, an ellipse, or an eyebrow shape. , it is possible to obtain glass fibers having irregularly shaped cross sections such as polygons.

Here, the plurality of nozzle holes are arranged so as to sandwich or surround the center of a recess formed on the lower surface of the nozzle plate, and at least a portion thereof is opened within the recess, and the outflow of each nozzle hole is The opening positions on the sides are such that the side closer to the center of the recess is higher than the side farther away. Therefore, the molten glass spun from each nozzle hole is cooled less by the outside air on the side closer to the center of the recess (the side that joins the molten glass spun from other nozzle holes), and its temperature is lower than that on the far side. Therefore, it is easy to bond the molten glass spun from adjacent nozzle holes, and even if the interval between the nozzle holes is increased, the molten glass can be stably bonded. Also, the temperature on the other side is low and the viscosity is high, so it is difficult to deform. In this way, glass fibers with a highly irregular cross section can be stably produced.

Embodiments Hereinafter, embodiments of the present invention shown in the drawings will be described in more detail.

Fig. 1 is a schematic side view showing an example of an apparatus for producing glass fibers with flat irregular cross-sections such as oval, elliptical, or cocoon-shaped cross sections by the method of the present invention, and Fig. 2 is a front view of the main parts thereof. It is a diagram. Reference numeral 11 is a bushing having a nozzle plate 12 at the bottom with a large number of nozzle holes, 13 is a sizing agent application roller, 14 is a focusing roller, 15 is a winding device, and 16 is a cooling gas (hereinafter referred to as cold air). This is a cold air blowing device. As shown in FIG. 3, the nozzle plate 12 has a pair of nozzle holes 18A, which are arranged close to each other.
18B are formed in many pairs, and the nozzle plate 1
As can be clearly seen from FIG. 4, a conical or spherical recess 19 is formed on the lower surface of the nozzle 2, centered at the center of each pair of nozzle holes 18A, 18B. In other words, the pair of nozzle holes 18A, 18B are arranged to sandwich the center of the conical or spherical recess 19 and at least partially open in the recess 19, and each nozzle hole 18A, 18B The opening position on the outflow side (lower end of the nozzle hole) is higher on the side closer to the center of the recess than on the side farther away.

In FIGS. 1 and 2, the molten glass 17 supplied to the bushing 11 is spun out from each pair of nozzle holes 18A, 18B of the nozzle plate 12, and then joined together, and cold air is blown from the cold air blowing device 16. The filament 20 is then rapidly cooled and solidified to become a filament 20 having a relatively flat irregular cross section such as an oval, an ellipse, or an eyebrow shape. After the large number of filaments 20 are coated with a sizing agent by the sizing agent application roller 13,
It is focused into a strand 21 by a focusing roller 14,
It is wound onto the winding tube 22 of the winding device 15. During this process, when the strand 21 runs on a sizing agent application roller or guide, each filament falls flat and overlaps, resulting in a strand that is flatter than before (all filaments are lined up facing the same direction). By the above method, a flat strand made of glass fibers having irregular cross-sections such as an oval, an ellipse, or an eyebrow shape is manufactured.

When implementing the above method, the following precautions must be taken in order to obtain glass fibers with a flat and irregular cross section.
Molten glass spun from a nozzle hole generally has a low viscosity and a high surface tension, so it has a strong tendency to immediately become circular in cross section. For this reason, a pair of nozzle holes 1
Joining the molten glass spun from 8A and 18B,
Even if the cross section is cocoon-shaped, by the time the molten glass solidifies, the cross section may deform into an oval or an ellipse due to surface tension, and finally become circular.
This tendency becomes stronger as the distance between the nozzle holes becomes shorter, and therefore, if the distance between the nozzle holes becomes too close, the cross-sectional shape of the filament becomes circular. On the other hand, if they are too far apart, the molten glass from each nozzle hole will not be bonded, and the 2
It becomes a filament with a circular cross section of a book. Therefore, it is necessary to set the distance between the nozzle holes in each pair based on the spinning conditions so that the cross section is not circular and the fibers are not separated into two fibers. In this embodiment, a recess 19 is formed on the lower surface of the nozzle plate 12 as shown in FIG.
A, 18B are opened in this recess 19, and the positions of the openings on the outflow side of each nozzle hole 18A, 18B are such that the side closer to the center of the recess 19 is higher than the side farther away. With this configuration, the cooling of the molten glass spun from the two nozzle holes 18A, 18B by the outside air to the center side of the recess (the part that joins each other) is weakened, and therefore the temperature of that part is high, and the two nozzle holes Molten glass spun from can be easily bonded. In other words, by providing the recess 19, it becomes possible to widen the interval between the nozzle holes 18A and 18B, and it becomes possible to manufacture glass fiber with a more elongated cross section. The shape of the recesses 19 is not limited to the conical or spherical shapes formed in each pair of nozzle holes, but may also be groove-like as shown in FIGS.
Instead of being formed by deforming the nozzle plate 12, they may be formed by cutting the lower surface of the nozzle plate 12, as shown in FIG. The cross-sectional shapes of the nozzle holes 18A and 18B are oval, instead of rectangular as shown in FIG.
Although the shapes can be arbitrary, such as elliptical or circular shapes, it is preferable to use rectangular or elliptical shapes lined up in the longitudinal direction as shown in FIG. 3 because glass fibers with an elongated cross-sectional shape and a large specific surface area can be produced. In the nozzle plate shown in FIGS. 3 and 4, a pair of nozzle holes 18A,
It was preferable to set the clearance 18B (FIG. 4d) between 0.1 mm and 1 mm. This gap d
When it is smaller than 0.1 mm, the filament cross section may become circular, and when it is larger than 1 mm, the filament may split into two.

The cold air from the cold air blowing device 16 rapidly cools the filament spun from the nozzle plate and accelerates solidification.
This is because the molten glass spun from two nozzle holes and joined together to form a cocoon-shaped cross section with large irregularities is prevented from deforming into a circular cross-section due to its own surface tension. This is an effective means for making glass fibers with a cross section of . Air or nitrogen is usually used as the gas for cooling, but other gases such as inert gases may be used depending on the cost. Although the cold air blowing device 16 is shown in the drawing as having a large number of cold air blowing pipes 25 provided corresponding to each pair of nozzle holes, the cold air blowing device 16 is not limited to this example. It may also be equipped with an exit. The direction of the cold air blowing can range from parallel to the nozzle surface to perpendicular to the nozzle surface, but it is most desirable to blow the cold air toward the nozzle surface at an angle of 75 degrees to 85 degrees. When spraying at an angle smaller than this, it is preferable to spray from opposing directions while keeping a balance, as spraying from only one direction may disrupt the flow of the glass fibers. It is preferable that the amount of cold air is selected from 10 ml/min to 2/min. Air volume 10
If it is less than ml/min, there is not much cooling effect, while if it is more than 2/min, the air flow may disrupt the flow of glass fibers, causing problems such as fibers getting tangled or separating into filaments with circular cross sections. . It goes without saying that the cold air blowing device 16 may be omitted if the cross-sectional shape of the filament can be maintained even without blowing cold air.

It is also effective to lower the temperature and increase the viscosity of the molten glass extruded from the nozzle plate as a means of inhibiting the tendency of the molten glass spun from the nozzle plate to deform into a circular cross section. However, if the viscosity is simply increased, the amount of spinning decreases and the glass fibers produced become thinner. Therefore, it is preferable to pressurize the molten glass in the bushing by an appropriate method and extrude the molten glass under pressure. By extruding the molten glass under pressure in this way, it is possible to extrude the molten glass in a highly viscous state, which further limits the tendency of the spun molten glass to deform into a circular shape, creating a more uneven cocoon shape. of glass fiber is obtained. The higher the pressure applied to the molten glass, the more viscous the molten glass can be spun, which is preferable from the point of view of maintaining the deformation. However, due to limitations on the strength of the bushing, it is usually less than 8 kg/cm ² is preferred.

In the above device, two nozzle holes are placed close to each other, and the molten glass spun from the two nozzle holes is joined to form a single filament.Instead, three or more nozzle holes are placed close to each other. It is also possible to produce glass fibers with irregular cross sections by arranging them and joining the molten glass spun out from these nozzle holes to form a single filament. Figures 7 and 8 show three nozzle holes 18A, 18B, 18 with circular cross sections.
A nozzle plate 12 is shown in which C are arranged close to each other and at the apex positions of an equilateral triangle, and further a conical recess 19 is provided in a region including each nozzle hole on the lower surface.
Using this nozzle plate 12, the molten glass spun from each nozzle hole is joined in the same manner as described above.
By forming the filament into a book filament, a glass fiber having an approximately triangular cross section can be produced. In this case, by appropriately adjusting the amount by which the molten glass spun and bonded from three nozzle holes is deformed into a circular shape due to surface tension, a triangular shape with a depression on each side is formed as shown in Figure 10. Alternatively, each side may be substantially straight or bulged outward. By increasing the number of nozzle holes arranged close to each other to four or five, it is also possible to manufacture glass fibers with various irregular cross-sections, such as square or pentagonal. In any case, the cross-sectional shape of the nozzle hole used is not limited to a circle, but may be any shape such as a rectangle, an ellipse, or an oval. Further, the arrangement of the nozzle holes is not limited to the apex positions of regular polygons such as regular triangles and squares, but can be placed at various positions, thereby making it possible to obtain glass fibers with various cross-sectional shapes.

Example I Glass fibers were produced using a nozzle plate having nozzle holes 18A, 18B and recesses 19 having the shapes and dimensions shown in Table 1 and FIGS. 3 and 4. A glass fiber having a cocoon-shaped cross section as shown in FIG. 9 was obtained. When a rod was made from a strand of glass fiber as a pultrusion, the bending strength was improved by 10 to 15% compared to conventional glass fiber with a circular cross section.

Table 1 Nozzle hole shape Rectangular Nozzle long side 2.5mm Nozzle short side 1.1mm Molten glass temperature 1240℃ Spinning pressure Normal pressure (glass head pressure) Cold air flow rate 0.5/min vs. Blowing angle 75 degrees Cold air blowing pipe diameter 2mm Filament long diameter (a ) 30μ Filament short diameter (b) 10μ Filament center diameter (c) 0.9 to 0.8×b Example Nozzle holes 18A, 18B, 18C and recess 1 having shapes and dimensions shown in Table 2 and FIGS. 7 and 8
When manufacturing glass fiber using a nozzle plate having No. 9, it was found that the nozzle plate had the dimensions shown in Table 2 and
A glass fiber having a substantially triangular cross section as shown in Figure 0 was obtained. Using this strand made of glass fiber,
When bending strength was measured using FRTP, the bending strength was improved by 10 to 15% compared to conventional glass fibers with a circular cross section.

Table 2 Nozzle hole shape Circular Nozzle position Vertex of equilateral triangle Nozzle diameter 1.6 mm Molten glass temperature 1200℃ Spinning pressure Normal pressure (glass head pressure) Cold air flow 0.5/min Recess Blow angle 75 degrees Cold air blowing pipe diameter 2 mm Recess 19 diameter 4 mm Filament diameter (R) 10μ Effects of the invention As explained above, according to the present invention, the molten glass spun from a plurality of nozzle holes is bonded to each other to form a single filament. The amount by which the subsequent molten glass deforms into a circular shape due to surface tension is small, and as a result, glass fibers with irregular cross sections such as oval, elliptical, cocoon-shaped, and polygonal shapes can be manufactured. The glass fibers produced in this way have an increased specific surface area compared to conventional glass fibers with a circular cross section, and when used as a reinforcing material for composite materials, they have a strong adhesive force to resin and can improve the strength of composite materials. can. In particular, with glass fibers having a cocoon-shaped cross section, the adhesive force between the filaments is large due to the interlocking effect of the filaments, and the reinforcing effect on the composite material is even higher.Furthermore, it is possible to obtain a wide and thin strand. It also has the advantage that thin fabrics can be manufactured using it.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing an example of an apparatus used for carrying out the method of the present invention, FIG. 2 is a front view of the main parts thereof,
3 is a diagram showing a part of the bottom surface of the nozzle plate 12 used in the apparatus shown in FIG. 1, FIG. 4 is a cross-sectional view taken from FIG. 3, and FIG. Figure 6 is a sectional view showing still another modification of the nozzle plate;
Fig. 7 is a cross-sectional view of a part of a nozzle plate used for producing glass fibers with an approximately triangular cross section, Fig. 8 is a bottom view thereof, and Fig. 9 was created based on a cross-sectional micrograph of the glass fiber produced in Example I. cross-sectional view, No. 10
The figure is a cross-sectional view created based on a cross-sectional micrograph of the glass fiber produced in the example. 12... nozzle plate, 13... sizing agent application roller, 14... focusing roller, 15... winding device,
18A, 18B, 18C... Nozzle hole, 19...
Recessed portion, 20... filament, 21... strand, 25... cold air blowing pipe.

Claims (1)

[Scope of Claims] 1. A nozzle plate having a recess on the lower surface, a plurality of nozzle holes arranged close to each other so as to sandwich or surround the center of the recess, at least one of each nozzle hole. The molten glass is ejected from the plurality of nozzle holes, each of which has a hole in the recess and is arranged such that the opening position on the outflow side of each nozzle hole is such that the side closer to the center of the recess is higher than the side farther from the center of the recess. A method for producing glass fiber, comprising spinning the spun molten glass together and bonding the spun molten glass to each other to form a single filament. 2. The method for manufacturing glass fiber according to claim 1, wherein the plurality of nozzle holes are two nozzle holes with a rectangular cross section arranged in a longitudinal direction. 3. The method for manufacturing glass fiber according to claim 1, wherein the plurality of nozzle holes are two nozzle holes arranged in the longitudinal direction and each having an oval cross section. 4. The method for manufacturing glass fiber according to claim 1, wherein the plurality of nozzle holes are three nozzle holes arranged on the vertices of a triangle. 5. The method for manufacturing glass fiber according to any one of claims 1 to 4, wherein the recess is conical or spherical. 6. The method for manufacturing glass fiber according to any one of claims 1 to 4, wherein the recess is groove-shaped.