JP7522387B2 - Nozzle for irregular cross-section glass fiber and manufacturing method for irregular cross-section glass fiber - Google Patents

Description

The present invention relates to a nozzle for producing irregular cross-section glass fibers having a flat cross-sectional shape from molten glass, and a method for producing irregular cross-section glass fibers using the nozzle.

As a type of glass fiber, irregular cross-section glass fibers with a flat cross-sectional shape are manufactured (see Patent Document 1). Since irregular cross-section glass fibers can achieve a high reinforcing effect when kneaded with resin to form a composite, they are used in a variety of fields, such as being adopted as fibers for fiber-reinforced plastics (FRP).

When manufacturing modified cross-section glass fibers, for example, molten glass is supplied to a bushing from a feeder for circulating the molten glass, and the molten glass is cooled while being drawn out from each of the multiple nozzles provided in the bushing. The nozzle holes provided in these nozzles generally have a flat hole shape (rectangle, oval, etc.).

International Publication No. 2017/221471

The following problems had to be solved when manufacturing irregular cross-section glass fibers. That is, the molten glass flowing out of the nozzle hole is deformed by surface tension so that its surface area becomes smaller, making it difficult to mold irregular cross-section glass fibers with a high flattening ratio.

In light of the above circumstances, the technical objective of the present invention is to make it possible to produce fibers with a high flatness when producing modified cross-section glass fibers.

The present invention, which aims to solve the above problems, provides a nozzle for irregular cross-section glass fibers, which is provided with a flat nozzle hole having an inlet and an outlet for molten glass, and the wall surrounding the nozzle hole has a pair of short wall portions opposed in the long diameter direction of the nozzle hole and a pair of long wall portions opposed in the short diameter direction, and is used to produce irregular cross-section glass fibers from molten glass discharged from the nozzle hole, and is characterized in that the average width of the bottom wall surface of the short wall portions is wider than the average width of the bottom wall surface of the long wall portions.

When manufacturing the irregular cross-section glass fiber, the inner peripheral surface of the nozzle hole (including the inner wall surface of the short wall portion and the long wall portion) as well as the bottom wall surface of the short wall portion and the long wall portion are wetted with molten glass. At this time, the bottom wall surface of the short wall portion and the long wall portion can pull the molten glass in a direction along the bottom wall surface, and the wider the width of the bottom wall surface (the width along the thickness direction of the short wall portion or the width along the thickness direction of the long wall portion) is, the easier it is to pull the molten glass. In order to increase the flattening ratio of the manufactured irregular cross-section glass fiber, it is advantageous to pull the molten glass along the major axis direction of the nozzle hole rather than the minor axis direction. Therefore, as in this configuration, if the average width of the bottom wall surface of the short wall portion is wider than the average width of the bottom wall surface of the long wall portion, the molten glass can be effectively pulled along the major axis direction of the nozzle hole. As a result, it is possible to mold the irregular cross-section glass fiber with a high flattening ratio.

In the above configuration, it is preferable that the average width of the bottom wall surface of the short wall portion is 1.5 times or more the average width of the bottom wall surface of the long wall portion.

This makes it possible to effectively pull the molten glass along the long diameter of the nozzle hole, which is even more advantageous in forming irregular cross-section glass fibers with a high flatness.

In the above configuration, it is preferable that the area of the bottom wall surface of the short wall portion is larger than the area of the long wall portion.

This makes it possible to effectively pull the molten glass along the long diameter of the nozzle hole, which is even more advantageous in forming irregular cross-section glass fibers with a high flatness.

Furthermore, to solve the above problems, the present invention provides a method for producing irregular cross-section glass fiber from molten glass discharged from a nozzle hole for irregular cross-section glass fiber, the method being characterized in that the nozzle hole is provided with a flat nozzle hole having an inlet and an outlet for molten glass, and the wall portion surrounding the nozzle hole has a pair of short wall portions opposed in the major axis direction of the nozzle hole and a pair of long wall portions opposed in the minor axis direction, and the average width of the bottom wall surface of the short wall portions is made wider than the average width of the bottom wall surface of the long wall portions.

This method makes it possible to obtain the same effects and advantages as those already described for the nozzle for irregular cross-section glass fibers.

According to the present invention, when producing irregular cross-section glass fibers, it is possible to produce fibers with a high flatness ratio.

FIG. 1 is a cross-sectional view that illustrates a manufacturing method and manufacturing apparatus for modified cross section glass fibers. FIG. 2 is a cross-sectional view showing the periphery of a nozzle for modified cross-section glass fibers. FIG. 2 is a bottom view showing the periphery of a nozzle for modified cross-section glass fibers. 1A is a side view of a nozzle for modified cross-section glass fibers as seen from the long wall side, FIG. 1B is a cross-sectional view, and FIG. 1C is a bottom view. FIG. 2 is a cross-sectional view showing a modified cross-section glass fiber. FIG. 2 is a bottom view of the nozzle for modified cross section glass fiber. 1A is a side view of a nozzle for modified cross-section glass fibers as seen from the long wall side, FIG. 1B is a bottom view, and FIG. 1C is a cross-sectional view. FIG. 7B is an enlarged view of a portion A in FIG.

The following describes a nozzle for irregular cross-section glass fibers and a method for manufacturing irregular cross-section glass fibers according to an embodiment of the present invention, with reference to the attached drawings.

As shown in FIG. 1, the irregular cross-section glass fiber is manufactured by a manufacturing apparatus 1. The manufacturing apparatus 1 includes a feeder 3 that circulates molten glass 2 produced in a melting furnace (not shown), a bushing 4 that is disposed below the feeder 3, and a pipe 5 that connects the feeder 3 and the bushing 4. The molten glass 2 is supplied from the feeder 3 to the bushing 4 via the pipe 5. The molten glass 2 then flows out of a nozzle hole 6 of the bushing 4. The molten glass 2 is cooled to become an irregular cross-section glass fiber 2f (hereinafter referred to as glass fiber 2f).

In this embodiment, the molten glass 2 is made of E glass. However, this is not limited, and the molten glass 2 may be made of other glasses such as D glass, S glass, AR glass, and C glass.

The feeder 3 is connected to a glass melting furnace (not shown). The feeder 3 is capable of circulating the molten glass 2 that is continuously produced in the glass melting furnace. Inside the feeder 3, a liquid surface 2a of the molten glass 2 is formed.

The bushing 4 has a base plate 7 at its bottom. The base plate 7 has a number of nozzles 8 for irregular cross-section glass fibers (hereinafter referred to as nozzles 8) and cooling pipes 9 arranged in the vicinity of these nozzles 8. The multiple nozzles 8 have the same configuration. The nozzle holes 6 provided in each nozzle 8 are formed flat, as will be described in detail later.

The pipe 5 is formed into a cylindrical shape with a tube axis extending in the vertical direction. The upper end of the pipe 5 is connected to the bottom of the feeder 3, and the lower end of the pipe 5 is connected to the upper end of the bushing 4. Note that the shape and the direction in which the tube axis of the pipe 5 extends may differ from that of this embodiment, as long as the pipe 5 can connect the feeder 3 and the bushing 4.

The bushing 4, pipe 5, nozzle 8, and cooling tube 9 are each made in part or in whole of platinum or a platinum alloy (e.g., a platinum-rhodium alloy, etc.). In this embodiment, of these components, the pipe 5 is made entirely of platinum or a platinum alloy.

The entire flow path from the connection between the feeder 3 and the pipe 5 to the nozzle hole 6 of the bushing 4 is filled with molten glass 2. As a result, the pressure (head pressure) for causing the molten glass 2 to flow out of the nozzle hole 6 is determined by the height difference H between the nozzle hole 6 and the liquid surface 2a of the molten glass 2 in the feeder 3. Here, the height difference H can be adjusted, for example, by changing the length of the pipe 5.

The temperature and viscosity of the molten glass 2 when forming the glass fiber 2f are set to 1100°C to 1250°C (preferably 1150°C to 1200°C) and 10 ^2.6 dPa·s to 10 ^3.8 dPa·s (preferably 10 ^2.9 dPa·s to 10 ^3.3 dPa·s), respectively. The "temperature and viscosity of the molten glass 2" here refers to the temperature and viscosity of the molten glass 2 at the position where the molten glass flows into the nozzle 8. The temperature and viscosity of the molten glass 2 may be adjusted, for example, by individually heating the bushing 4 and the pipe 5 by any heating means (for example, an electric heating device). In addition, the temperature and viscosity of the molten glass 2 may be adjusted by heating the molten glass 2 in the glass melting furnace and the feeder 3 by electric heating or the like.

A bundling agent is applied to the surface of the glass fiber 2f by an applicator (not shown). As a result, several hundred to several thousand glass fibers 2f are spun into a single strand 2s. The spun strand 2s is wound as a fiber bundle 2r around a bobbin 10, which is a winding device. The strand 2s is cut to a length of, for example, about 1 mm to 20 mm, and used as a chopped strand.

As shown in Figures 2 and 3, the nozzle 8 has a pair of long wall portions 11, 11 and a pair of short wall portions 12, 12. A flat nozzle hole 6 is formed by being surrounded by these walls. The nozzle hole 6 has an inlet 6a through which the molten glass 2 flows and an outlet 6b through which the molten glass 2 flows. Each of the pair of long wall portions 11, 11 has a notch portion 13 that opens toward the outlet 6b. This allows the nozzle hole 6 to communicate with the external space of the nozzle 8 through the notch portion 13.

Cooling water 14 circulates inside the cooling pipe 9 to cool the molten glass 2. The cooling pipe 9 has a plate-like outer shape, and the plate surface is parallel to the long wall portion 11. Here, the cooling pipe 9 is provided integrally with the base plate 7, but it may be provided at a position away from the base plate 7. The cooling pipe 9 may also be formed in a circular pipe shape.

The height position of the cooling pipe 9 can be adjusted according to the cooling conditions of the molten glass 2. As an example, the cooling pipe 9 may be arranged above the lower end of the nozzle 8 so that the molten glass 2 drawn from the nozzle 8 does not face the plate surface. On the other hand, the cooling pipe 9 may be arranged above and below the lower end of the nozzle 8 so that both the nozzle 8 and the molten glass 2 drawn from the nozzle 8 face the plate surface. In addition to the cooling pipe 9, cooling fins that cool with air flow may be used to cool the molten glass 2. The cooling pipe 9 is not an essential component and may be omitted.

A number of nozzle rows P are arranged in parallel with a gap between them on the base plate 7. A number of nozzles 8 belong to each nozzle row P. The nozzles 8 belonging to the same nozzle row P are arranged so that the nozzle holes 6 formed therein are positioned on the same straight line.

The cooling pipe 9 is arranged between the adjacent nozzle rows P, P so as to extend parallel to the nozzle row P. This allows the molten glass 2 in the nozzle hole 6 to be cooled through the notch 13 facing the cooling pipe 9. Specifically, the molten glass 2 is rapidly cooled from a temperature of 1000°C or higher by the cooling pipe 9. Here, the cooling pipe 9 also functions to suppress deterioration of the bushing 4 (base plate 7) and the nozzle 8 due to heat and increase their durability by cooling these components.

As shown in Figures 4(a) to (c), the notch 13 provided in the long wall portion 11 of each nozzle 8 is an isosceles trapezoid whose upper base is shorter than its lower base. As a result, the opening width of the notch 13 gradually increases from the inlet 6a side of the nozzle hole 6 toward the outlet 6b side. The depth of the notch 13 (the length in the direction along the axis 6x of the nozzle hole 6) is set to 0.1 mm to 2 mm. This is because if the depth of the notch 13 exceeds 2 mm, both ends in the longitudinal direction of the cross section of the manufactured glass fiber 2f will become too thin, making the glass fiber 2f more susceptible to breakage.

The shape of the cutout portion 13 is not limited to a trapezoidal shape, and may be other shapes. For example, it may be triangular, semicircular, or rectangular. However, even when these other shapes are adopted, it is preferable that the opening width of the cutout portion 13 gradually increases from the inlet 6a side to the outlet 6b side of the nozzle hole 6.

As shown in FIG. 4, in this embodiment, a single nozzle hole 6 is provided in one nozzle 8. The nozzle hole 6 is formed in an elongated hole shape. A pair of long wall portions 11, 11 face each other in the short diameter direction of the elongated nozzle hole 6, and a pair of short wall portions 12, 12 face each other in the long diameter direction. Here, the flattening ratio (ratio of long diameter to short diameter) of the nozzle hole 6 is set to 2 to 5. The inner peripheral surface of the nozzle hole 6, including the inner wall surface 11a of the long wall portion 11 and the inner wall surface 12a of the short wall portion 12, is made of platinum or a platinum alloy. In addition, the inner wall surface 11a of the long wall portion 11 is linear and parallel to each other as shown in FIG. 4(c).

The boundary 15 between the long wall portion 11 and the short wall portion 12 is the point where the inclination of the inner wall surface in the left-right direction (Z direction) in Figure 4 (c) changes from 0, and the part where the inclination in the left-right direction is 0 is the long wall portion 11, and the part where the inclination is other than 0 is the short wall portion 12.

The long wall portion 11 has a bottom wall surface 11b that is continuous with the inner wall surface 11a. The bottom wall surface 11b at the location where the cutout portion 13 is provided in the long wall portion 11 corresponds to the upper base of the isosceles trapezoid or the side connecting the upper base and the lower base. In this embodiment, the bottom wall surface 11b is a flat surface (a flat surface perpendicular to the axis 6x at the location corresponding to the upper base of the isosceles trapezoid). Similarly, the short wall portion 12 has a bottom wall surface 12b that is continuous with the inner wall surface 12a. In this embodiment, the bottom wall surface 12b is a flat surface perpendicular to the axis 6x. The bottom wall surfaces 11a and 12a do not necessarily have to be flat surfaces, and may be uneven or curved surfaces.

Here, as shown in FIG. 4(c), when the nozzle hole 6 is viewed from the front from the outlet 6b side, the average value of the width (width along the short diameter direction) of the bottom wall surface 11b of the long wall portion 11 is the average width W1, and the average value of the width (width along the long diameter direction) of the bottom wall surface 12b of the short wall portion 12 is the average width W2. At this time, the average width W2 is larger than the average width W1. Specifically, the average width W2 is 1.5 times or more, preferably 2 times or more, of the average width W1. In this embodiment, the thickness of the long wall portion 11 is constant at W11, so W1 = W11, but the thickness of the short wall portion 12 is not constant (for example, W21 ≠ W22 ≠ W23). Therefore, the average width W2 is the average value of the thickness of each part of the short wall portion 12. In addition, in this embodiment, the area of the bottom wall surface 12b of the short wall portion 12 is larger than the area of the bottom wall surface 12b of the long wall portion 12.

The main actions and effects of the method for producing irregular cross-section glass fibers using the nozzle 8 described above are explained below.

In the nozzle 8, when the bottom wall surface 11b of the long wall portion 11 and the bottom wall surface 12b of the short wall portion 12 are wetted with the molten glass 2, these bottom wall surfaces 11b, 12b pull the molten glass 2 in a direction along the bottom wall surfaces 11b, 12b. The wider the bottom wall surfaces 11b, 12b are, the easier they are to pull the molten glass 2. Therefore, in the nozzle 8 in which the average width W2 is greater than the average width W1, the molten glass 2 can be effectively pulled along the major axis direction of the nozzle hole 6. As a result, it is possible to manufacture glass fibers 2f with a high flatness as shown in FIG. 5. Here, the cross-sectional shape of the glass fibers 2f is formed to be close to an oval shape.

The nozzle for irregular cross-section glass fiber and the manufacturing method for irregular cross-section glass fiber according to the present invention are not limited to the configurations and aspects described in the above embodiment. For example, in the above embodiment, a notch 13 is provided in each of the pair of long wall portions 11, 11, but providing the notch 13 is not essential and may be removed. In addition, the nozzle hole 6 may be an ellipse, dumbbell, diamond, triple perfect circle, rectangular, etc., other than a long hole shape.

Next, a second embodiment that differs from the above embodiment will be described. Note that the configuration other than the nozzle 8 is the same as the above embodiment. Therefore, only the differences from the above embodiment will be described.

As shown in FIG. 6, the nozzle 18 in the second embodiment has a pair of long wall portions 21, 21 and a pair of short wall portions 22, 22. Each of the pair of long wall portions 21, 21 has a notch portion 23 that opens toward the outlet port 6b. The shape of the notch portion 23 is the same as in the above embodiment.

The long wall portion 21 has an inner wall surface 21a and a bottom wall surface 21b connected to the inner wall surface 21a. In the second embodiment, unlike the above embodiment, the inner wall surface 21a is not parallel to the horizontal direction of the paper, but is formed so as to approach the outer wall surface 21c of the long wall portion 21 as it approaches the center of the inner wall surface 21a. Therefore, the width W13 of the center part of the bottom wall surface 21b of the long wall portion 21 is narrower than the width W12 of the bottom wall surface 21b of the long wall portion 21 on the short wall portion 22 side. Therefore, the average width W1 in the second embodiment is the average value of the thickness of each part of the long wall portion 22. In addition, in the second embodiment, the thickness of the bottom wall surface 22b of the short wall portion 22 is constant at W24, so W2 = W24. Note that the average width W2 is greater than the average width W1.

Unlike the above embodiment, when the inner wall portion is linear and not parallel as in this embodiment, the boundary 15 between the long wall portion 21 and the short wall portion 22 can be determined by the following method. First, as shown in FIG. 6, a rectangle C is drawn that is in contact with the inner wall portion of the nozzle 18 as described below, and each vertex of the rectangle C becomes the boundary 15. This rectangle C has a shape such that D1 + D2 = D3 + D4, where D1 is the area of the figure enclosed by the first side C1 of the rectangle C and the inner wall portion, D2 is the area of the figure enclosed by the second side C2 opposite to this first side C1 and the inner wall portion, D3 is the area of the figure enclosed by the third side C3 adjacent to the first side C1 and the inner wall portion, and D4 is the area of the figure enclosed by the fourth side C4 opposite to the third side C3 and the inner wall portion.

In the second embodiment, since the average width W2 is larger than the average width W1, the nozzle 18 can effectively pull the molten glass 2 along the major axis of the nozzle hole 16. As a result, it is possible to produce glass fibers 2f with a high flatness as shown in FIG. 5.

Next, a third embodiment that differs from the above two embodiments will be described. Note that the configuration other than the nozzle 8 is the same as the above embodiments. Therefore, only the differences from the above embodiments will be described.

As shown in FIG. 7, the nozzle 28 in the third embodiment has a pair of long wall portions 31, 31 and a pair of short wall portions 32, 32. Each of the pair of long wall portions 31, 31 has a notch portion 33 that opens toward the outlet port 6b. The shape of the notch portion 33 is the same as in the above embodiment. The widths of the long wall portion 31 and the short wall portion 32 when viewed in a plane are both constant at W3.

As shown in FIG. 8, the short wall portion 32 has an inner wall surface 32a and a bottom wall surface T connected to the inner wall surface 32a. The bottom wall surface T has a vertical bottom wall surface 32b perpendicular to the inner wall surface 32a, and an inclined bottom wall surface 32c connected to the vertical bottom wall surface 32b and the inner wall surface 32a and inclined with respect to the inner wall surface 32a. In the third embodiment, the thickness of the short wall portion 32 is constant as in the second embodiment. As shown in FIG. 8, the width of the vertical bottom wall surface 32b is L2, and the width of the inclined bottom wall surface 32c is L1. Here, the average width W2 of the bottom wall surface T is (L1+L2).

By providing the inclined bottom wall surface 32c in this manner, the average width W2 of the bottom wall surface T can be made longer by (L1-L3) compared to when the inclined bottom wall surface 32c is not provided (in this case, the width of the bottom wall surface is L2+L3=W3). The relationship between L1 and L3 is L1=L3/cosθ, and for example, when θ=55°, L1=1.74×L3.

In the third embodiment, the average width W2 (W3 + 0.74L3) is longer than the average width W1 (W3) by 0.74L3, so that the nozzle 28 can effectively pull the molten glass 2 along the major axis of the nozzle hole 26. As a result, it is possible to manufacture glass fibers 2f with a high flatness as shown in FIG. 5.

2 Molten glass 2f Deformed cross-section glass fiber 6 Nozzle hole 6a Inlet 6b Outlet 8 Nozzle for deformed cross-section glass fiber 11 Long wall portion 11b Bottom wall surface 12 Short wall portion 12b Bottom wall surface W1 Width W2 Width

Claims (6)

a flat nozzle hole having an inlet and an outlet for molten glass is provided;
a wall portion surrounding the nozzle hole has a pair of short wall portions opposed to each other in a major axis direction of the nozzle hole and a pair of long wall portions opposed to each other in a minor axis direction,
A nozzle for producing a modified cross-section glass fiber from molten glass flowing out of the nozzle hole,
A nozzle for irregular cross-section glass fibers, in which the average width of the bottom wall surface of the short wall portion is wider than the average width of the bottom wall surface of the long wall portion, and the inner wall surface of the long wall portion approaches the outer wall surface of the long wall portion as it moves toward the center. The nozzle for irregular cross-section glass fibers according to claim 1, wherein the average width of the bottom wall surface of the short wall portion is 1.5 times or more the average width of the bottom wall surface of the long wall portion. The nozzle for irregular cross-section glass fibers according to claim 1 or 2, in which the area of the bottom wall surface of the short wall portion is greater than the area of the long wall portion. 3. The nozzle for a modified cross-section glass fiber according to claim 1, wherein the inner wall surface and the outer wall surface of the short wall portion are arc-shaped. 3. The nozzle for a modified cross-section glass fiber according to claim 1, wherein the thickness of the bottom wall surface of the short wall portion is constant. A nozzle for a modified cross section glass fiber is provided with a flat nozzle hole having an inlet and an outlet for molten glass, and a wall portion surrounding the nozzle hole has a pair of short wall portions opposed to each other in the major axis direction of the nozzle hole and a pair of long wall portions opposed to each other in the minor axis direction,
A method for producing a modified cross section glass fiber from molten glass flowing out of the nozzle hole, comprising:
A method for manufacturing a modified cross section glass fiber, wherein the average width of the bottom wall surface of the short wall portion is wider than the average width of the bottom wall surface of the long wall portion, and the inner wall surface of the long wall portion approaches the outer wall surface of the long wall portion as it moves toward the center.