Skin-core type composite fiber and self-heating melting type manufacturing method thereof

Abstract

The invention belongs to the field of filter material fibers for bag type dust collectors, and particularly relates to a sheath-core type composite fiber and a self-heating melting type manufacturing method thereof. Aiming at the characteristics of low folding resistance and corrosion resistance of the glass fiber, the glass fiber-PTFE composite fiber is prepared by adopting a self-heating melting method, so that the corrosion resistance and folding resistance of the glass fiber are enhanced. A spinneret bushing is connected with a positive pole of a high-voltage direct-current power supply, so that molten glass fibers penetrating through the spinneret bushing are positively charged; a hollow powder tank is arranged below the spinneret bushing and is connected with the negative electrode of the high-voltage direct-current power supply, so that the polytetrafluoroethylene powder in the powder tank is negatively charged; polytetrafluoroethylene powder is adsorbed and instantly melted through electrostatic force and waste heat of the glass fibers to coat the surfaces of the glass fibers, and the sheath-core type composite fiber with the glass fibers as an inner core and polytetrafluoroethylene as an outer sheath layer is prepared through the processes of cooling, infiltration and the like.

Description

Technical Field

[0001] The present invention belongs to the field of filter materials for bag filters, and particularly relates to a sheath-core composite fiber and a self-heating melting manufacturing method thereof. Background Art

[0002] Glass fiber has low cost, high tensile strength, and good heat resistance, and is used in various industries. For example, it is used to make filter bags for high-temperature flue gas dust removal processes, wind turbine blades, instrument casings, and hull materials for small boats. However, glass fiber is not fold-resistant, which greatly limits its application range. In addition, its corrosion resistance is limited, which also makes glass fiber filter materials unsuitable for some flue gas conditions containing acid or alkali.

[0003] Polytetrafluoroethylene is a kind of high molecular organic material with excellent comprehensive properties. After coating polytetrafluoroethylene on the surface of glass fiber, due to the good flexibility and corrosion resistance of polytetrafluoroethylene and its large creep at high temperature, the fold resistance and corrosion resistance of glass fiber are greatly improved, and it also has excellent high-temperature resistance, which has a great impact on the performance of filter bags. Compared with pure PTFE fiber, this composite fiber can also reduce the consumption of PTFE and save a lot of costs. Summary of the Invention

[0004] In order to meet the requirements of filter materials for bag filters in some places with higher requirements for the fold resistance and corrosion resistance of glass fiber, the primary object of the present invention is to provide a self-heating melting manufacturing method of a sheath-core composite fiber, and the secondary object of the present invention is to provide the sheath-core composite fiber product.

[0005] The self-heating melting manufacturing method of a sheath-core composite fiber described in the present invention is as follows:

[0006] (1) When producing glass fiber by the wire drawing method, the spinneret is connected to the "+" pole of the high-voltage DC power supply, so that the glass fiber passing through the spinneret is positively charged;

[0007] (2) A hollow powder tank is arranged below the spinneret, and the powder tank is connected to the "-" pole of the high-voltage DC power supply, so that the polytetrafluoroethylene powder in the powder tank is negatively charged;

[0008] (3) When producing glass fiber by the wire drawing method, the glass melt passes through the spinneret and the powder tank in sequence. After passing through the spinneret, the glass melt becomes a molten positively charged glass fiber. When the molten positively charged glass fiber passes through the powder tank, the negatively charged polytetrafluoroethylene powder in the powder tank will be adsorbed on the surface of the positively charged glass fiber. At the same time, the heat carried by the molten glass fiber will cause the polytetrafluoroethylene powder to melt instantly and coat on the surface of the glass fiber, forming a polytetrafluoroethylene coating layer on the surface of the glass fiber, that is, a sheath-core composite fiber;

[0009] Further, after the sheath-core composite fiber passes through the powder tank and undergoes the cooling and infiltration processes, the polytetrafluoroethylene coating layer on the surface of the glass fiber cools and solidifies, forming a glass fiber-PTFE sheath-core composite fiber product with the glass fiber as the inner core and polytetrafluoroethylene wrapped around the outer layer.

[0010] In steps (1) and (2), the output power of the high-voltage DC power supply is 1 kW to 100 kW, and the DC voltage is 1 kV to 100 kV.

[0011] In step (2), the powder tank is arranged 5 cm to 50 cm below the spinneret plate, preferably a hollow U-shaped stainless steel powder tank, and holes are provided on the powder tank for the glass fiber to pass through, which are matched with the shape, size, and position of the spinneret holes of the spinneret plate.

[0012] When the glass fiber passes through the powder tank in step (3), its temperature ≥ 330 °C; further, the temperature of the glass fiber is 330 °C to 600 °C.

[0013] The equipment used for preparing the sheath-core composite fiber described above includes the following components: a melting furnace, a spinneret plate, a powder tank, a powder feeder, a high-voltage DC power supply, and a wire drawing guide wheel.

[0014] The sheath-core composite fiber prepared by the above method has a glass fiber as the inner core and polytetrafluoroethylene as the skin layer coated on the surface of the glass fiber; the diameter of the glass fiber is 3 μm to 50 μm (depending on the product use), and the skin layer is formed by melting and coating with polytetrafluoroethylene powder with a particle size of 0.1 μm to 100 μm (the median diameter is preferably not greater than 5 μm);

[0015] Further, the skin layer is formed by melting and coating with ultrafine polytetrafluoroethylene powder with a particle size of 0.1 μm to 20 μm.

[0016] The present invention operates the glass fiber spinning according to the general glass fiber drawing process flow, mainly based on the transformation of the original drawing production line. The spinneret plate is mainly retained from the original glass fiber production line, and the specifications, sizes, and shapes of the glass fiber drawing equipment are different in actual production. The spinneret plate is connected to the "+" pole of the high-voltage DC power supply, and the "-" pole of the high-voltage DC power supply is connected to the U-shaped stainless steel powder tank. The power and voltage of the power supply are adjusted according to the size of the original drawing equipment and the production task. The U-shaped stainless steel powder tank is generally arranged 5 cm to 50 cm below the spinneret plate, and the specific size of the powder tank is matched with the spinning amount and position of the spinneret plate to ensure that the glass fiber can pass through smoothly from the inside. The powder feeder continuously supplies polytetrafluoroethylene powder to the powder tank. During the production process, the polytetrafluoroethylene powder in the powder tank is negatively charged and is sent out from the slit in the inner cavity of the powder tank to the inside through a blowing air flow by an adjustable-rate transmission device.

[0017] When the spinneret of the wire drawing operation extrudes filaments, confirm that the transmission system and the high-voltage electrostatic device are turned on. Guide the glass fibers extruded from the spinneret to pass through the powder tank filled with PTFE powder and then wind them onto the wire drawing machine for wire drawing. During this process, under the action of the electric field force, the negatively charged PTFE powder in the powder tank will be quickly attracted and adhered to the surface of the positively charged high-temperature molten glass fibers. The temperature of the molten glass fibers can reach above 700 °C, and some can even be as high as 1200 °C, while the melting point of polytetrafluoroethylene is 327 °C. Utilizing the remaining heat of the glass fibers, the PTFE powder can be instantaneously melted and coated on the glass fibers, that is, a layer of polytetrafluoroethylene cortex is wrapped around the glass fibers in a self-heating melting manner. As the glass fibers move forward, the fibers cool down, and the PTFE solidifies and coats on the glass fibers, forming a core-sheath composite fiber with glass fibers as the core and PTFE coated on the outside. This composite fiber not only has the extremely high tensile strength of glass fibers but also greatly improves the corrosion resistance of glass fibers. Brief Description of the Drawings

[0018] Figure 1 Schematic diagram of the processing device for preparing the core-sheath composite fiber in Example 1; where: A - crucible furnace, 2 - spinneret, 3 - screw powder feeder, 4 - U-shaped stainless steel powder tank, 5 - high-voltage DC power supply, 6 - sizing coating device, 7 - wire drawing guide wheel;

[0019] Figure 2 Front view of the U-shaped powder supply tank in the core-sheath composite fiber processing device of Example 1;

[0020] Figure 3 Top view of the U-shaped powder supply tank in the core-sheath composite fiber processing device of Example 1;

[0021] Figure 4 Side view of the U-shaped powder supply tank in the core-sheath composite fiber processing device of Example 1;

[0022] Figure 5 Schematic three-dimensional structure diagram of the U-shaped powder supply tank in the core-sheath composite fiber processing device of Example 1;

[0023] Figure 6 Schematic diagram of the processing device for the core-sheath composite fiber in Example 2; where: B - tank furnace, 2 - spinneret, 3 - screw powder feeder, 4 - U-shaped stainless steel powder tank, 5 - high-voltage DC power supply, 6 - sizing coating device, 7 - wire drawing guide wheel. Detailed Description of the Embodiments

[0024] The technical solution of the present invention is clearly and completely described below in conjunction with the embodiments and drawings. It should be noted that the embodiments described in the present invention are only used to further explain and illustrate, and are not intended to limit the scope of its application. Based on the present invention, all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of the present invention.

[0025] The method and device for preparing glass fiber-PTFE composite fiber of the present invention are improvements made on existing production equipment. The spinneret is provided in the original crucible kiln or pool kiln equipment. The powder trough structure and the position of the powder trough from the spinneret can be adjusted according to actual production conditions. The voltage and power of the high-voltage DC power supply, the diameter and temperature of the glass fiber, the PTFE powder particle size and the conveying amount can all be adjusted according to the specifications of the drawing equipment, production requirements and product uses.

[0026] In the prior art, glass fibers are mostly prepared by the crucible furnace drawing method and the tank furnace drawing method. Therefore, methods for preparing glass fiber-PTFE composite fibers by using these two types of drawing methods are provided in the examples.

[0027] Example 1

[0028] This embodiment uses a crucible furnace drawing method to prepare sheath-core composite fibers.

[0029] In the composite fiber prepared in this embodiment, the glass fiber has a diameter of 3 μm to 50 μm, and the skin layer is formed by melt-coating polytetrafluoroethylene powder with a particle size of 0.1 μm to 100 μm (with a median diameter of 5 μm or less).

[0030] (1) A crucible furnace A for producing glass fiber contains molten glass. A spinneret 2 is connected to the + terminal of a high-voltage DC power supply 5, which positively charges the glass fiber passing through the spinneret. The high-voltage power supply has an output power of 1 kW to 100 kW and an output voltage of 1 kV to 100 kV.

[0031] (2) A circular stainless steel powder trough 4 is provided 5 cm to 50 cm below the spinneret 2. A hole matching the spinning position and spinning amount is provided at the bottom of the circular stainless steel powder trough 4 for the glass fiber to pass through. The circular stainless steel powder trough 4 is connected to the "-" pole of a high-voltage DC power supply 5 so that the polytetrafluoroethylene powder in the circular stainless steel powder trough 4 is negatively charged. The ultrafine PTFE powder preferably has a particle size of 0.1 μm to 20 μm, and a median diameter of 5 μm or less.

[0032] The side wall of the U-shaped stainless steel powder tank 4 is a closed hollow cavity structure. The powder tank is connected to the spiral powder feeder 3. The spiral powder feeder 3 continuously transports ultrafine PTFE powder into the U-shaped stainless steel powder tank 4 at a uniform speed. At the same time, the airflow blows the PTFE powder in the cavity into the powder tank through the narrow slit for the preparation of composite fibers. The front view of the U-shaped stainless steel powder tank 4 is as shown in Figure 2 shown, the top view is as shown in Figure 3 shown, the side view is as shown in Figure 4 shown, and the schematic diagram of the three-dimensional structure is as shown in Figure 5 shown.

[0033] (3) When producing glass fiber by the crucible furnace wire drawing method, the glass melt in the crucible furnace A sequentially passes through the spinneret plate 2 and the U-shaped stainless steel powder tank 4. After passing through the spinneret plate 2, the glass melt becomes a molten positively charged glass fiber. When the molten positively charged glass fiber passes through the U-shaped stainless steel powder tank 4, the negatively charged ultrafine PTFE powder in the U-shaped stainless steel powder tank 4 adheres to the surface of the positively charged high-temperature incandescent molten glass fiber under the action of electrostatic force. The PTFE powder instantaneously melts and coats the glass fiber, forming a PTFE coating layer on the surface of the glass fiber.

[0034] The glass fiber passing through the U-shaped stainless steel powder tank 4 continues to move forward under the traction of the wire drawing guide wheel 7. When passing through the sizing agent coating device 6, the sizing agent is coated on the fiber surface. After cooling, the PTFE coating layer on the fiber surface is cured, and a glass fiber-PTFE core-shell type composite fiber product with a glass fiber as the inner core and PTFE as the coating layer is obtained.

[0035] In the crucible furnace wire drawing method for glass fiber manufacturing process, the schematic diagram of the device is shown in Figure 1 , and the device includes the following components: crucible furnace A, spinneret plate 2, spiral powder feeder 3, U-shaped stainless steel powder tank 4, high-voltage DC power supply 5, sizing agent coating device 6, wire drawing guide wheel 7.

[0036] Among them, the spinneret plate 2 is connected to the "+" pole of the high-voltage DC power supply 5, the U-shaped stainless steel powder tank 4 is connected to the "-" pole of the high-voltage DC power supply 5. The U-shaped stainless steel powder tank 4 is arranged 5 cm to 50 cm below the spinneret plate 2. The glass fiber passes through the inside of the U-shaped stainless steel powder tank 4. The spiral powder feeder 3 continuously supplies polytetrafluoroethylene powder to the U-shaped stainless steel powder tank 4. During the production process, the polytetrafluoroethylene powder in the U-shaped stainless steel powder tank 4 is negatively charged.

[0037] Example 2

[0038] This example is for the preparation of core-shell type composite fiber by the tank furnace wire drawing method.

[0039] In the composite fiber prepared in this embodiment, the diameter of the glass fiber is 3 μm to 50 μm, and the cortex is formed by melting and coating PTFE powder with a particle size of 0.1 μm to 100 μm (the median diameter is concentrated at 5 μm or below 5 μm).

[0040] (1) In the tank furnace B for producing glass fibers, there is glass melt. The spinneret 2 is connected to the "+" pole of the high-voltage DC power supply 5. The output power of the high-voltage power supply is 1 kW to 100 kW, and the output voltage is 1 kV to 100 kV, so that the glass fiber passing through the spinneret is positively charged.

[0041] (2) At a position 5 cm to 50 cm below the spinneret 2, there is a U-shaped stainless-steel powder tank 4. The U-shaped stainless-steel powder tank 4 is provided with holes matching the spinning position and spinning amount for the glass fiber to pass through. The U-shaped stainless-steel powder tank 4 is connected to the "-" pole of the high-voltage DC power supply 5. The ultra-fine PTFE powder is supplied into the U-shaped stainless-steel powder tank 4 at a uniform speed by a screw feeder 3, so that the PTFE powder in the U-shaped stainless-steel powder tank 4 is negatively charged. The ultra-fine PTFE powder preferably has a particle size of 0.1 μm to 20 μm, and the median diameter is concentrated at 5 μm or below 5 μm.

[0042] The structure of the U-shaped stainless-steel powder tank 4 is the same as that of the powder tank in Embodiment 1.

[0043] (3) When using the tank furnace drawing method to produce glass fibers, the glass melt in the tank furnace B passes through the spinneret 2 and the U-shaped stainless-steel powder tank 4 in sequence. After the glass melt passes through the spinneret 2, it becomes a molten positively charged glass fiber. When the molten positively charged glass fiber passes through the U-shaped stainless-steel powder tank 4, the negatively charged PTFE powder in the U-shaped stainless-steel powder tank 4 adheres to the surface of the positively charged high-temperature incandescent molten glass fiber under the action of the electric field force. The PTFE powder instantaneously melts and coats on the glass fiber, forming a PTFE coating layer on the surface of the glass fiber.

[0044] The glass fiber passing through the U-shaped stainless-steel powder tank 4 continues to move forward under the traction of the wire drawing guide wheel 7. When passing through the sizing agent coating device 6, a sizing agent is coated on the fiber surface. After cooling, the PTFE layer on the fiber surface solidifies, and a glass fiber-PTFE core-shell composite fiber product with a glass fiber as the inner core and a PTFE as the coating layer is obtained.

[0045] When using the tank furnace drawing method for glass fiber manufacturing process, the schematic diagram of the device is shown in Figure 6 , Figure 6 In it, 2 sets of the same tank furnace wire drawing devices can carry out wire drawing operations simultaneously. The device includes the following components: tank furnace B, spinneret 2, screw feeder 3, U-shaped stainless-steel powder tank 4, high-voltage DC power supply 5, sizing agent coating device 6, wire drawing guide wheel 7.

[0046] Among them, the spinneret 2 is connected to the "+" pole of the high-voltage DC power supply 5, the U-shaped stainless steel powder tank 4 is connected to the "-" pole of the high-voltage DC power supply 5, the U-shaped stainless steel powder tank 4 is arranged 5 cm to 50 cm below the spinneret 2, and the glass fiber passes through the inside of the U-shaped stainless steel powder. During the production process, the polytetrafluoroethylene powder in the U-shaped stainless steel powder tank 5 is negatively charged and is sent out through the blowing air flow from the slits inside the powder supply tank.

Claims

1. A manufacturing method for core-sheath composite fibers by self-heating melting, characterized in that, The following contents are included: (1) When producing glass fibers by the wire drawing method, the spinneret is connected to the positive pole of a high-voltage DC power supply, so that the glass fiber belt passing through the spinneret is positively charged; (2) A hollow powder tank is arranged below the spinneret, and the powder tank is connected to the negative pole of the high-voltage DC power supply, so that the polytetrafluoroethylene powder in the powder tank is negatively charged; (3) When producing glass fibers by the wire drawing method, the glass melt passes through the spinneret and the powder tank in sequence. After passing through the spinneret, the glass melt becomes a molten positively charged glass fiber. When the molten positively charged glass fiber passes through the powder tank, the negatively charged polytetrafluoroethylene powder in the powder tank is adsorbed onto the surface of the positively charged glass fiber. At the same time, the heat carried by the molten glass fiber will cause the polytetrafluoroethylene powder to instantaneously melt and coat the surface of the glass fiber, forming a polytetrafluoroethylene coating layer on the surface of the glass fiber, that is, a core-shell type composite fiber is obtained.

2. The self-heating melting manufacturing method of a sheath-core composite fiber according to claim 1, characterized in that, After the core-shell type composite fiber passes through the powder tank, through the cooling and infiltration processes, the polytetrafluoroethylene coating layer on the surface of the glass fiber cools and solidifies, forming a core-shell type composite fiber product with the glass fiber as the inner core and polytetrafluoroethylene wrapped on the outer layer.

3. A method for manufacturing a sheath-core composite fiber by self-heating melting according to claim 1, characterized in that The output power of the high-voltage DC power supply described in step (1) and step (2) is 1 kW to 100 kW, and the DC voltage is 1 kV to 100 kV.

4. A method for manufacturing a core-shell composite fiber by self-heating melting according to claim 1, characterized in that, The powder tank described in step (2) is arranged 5 cm to 50 cm below the spinneret, and the powder tank is provided with holes matching the spinneret holes of the spinneret for the glass fiber to pass through.

5. A method for manufacturing a core-sheath composite fiber by self-heating melting according to claim 1, characterized in that, The powder tank is a stainless steel powder tank.

6. A method for manufacturing a sheath-core composite fiber by self-heating melting according to claim 1, characterized in that When the glass fiber passes through the powder tank in step (3), the temperature of the glass fiber is ≥330 °C.

7. A method for manufacturing a sheath-core composite fiber by self-heating melting according to claim 6, characterized in that, When the glass fiber passes through the powder tank in step (3), the temperature of the glass fiber is 330 °C to 600 °C.

8. The sheath-core composite fiber prepared by the manufacturing method according to any one of claims 1 to 7, characterized in that, The composite fiber has a glass fiber as the inner core and polytetrafluoroethylene as the skin layer coated on the surface of the glass fiber; the diameter of the glass fiber is 3 μm to 50 μm, and the skin layer is formed by melting and coating with polytetrafluoroethylene powder with a particle size of 0.1 μm to 100 μm.

9. The sheath-core type composite fiber according to claim 8, wherein The skin layer is formed by melting and coating with ultrafine polytetrafluoroethylene powder with a particle size of 0.1 μm to 20 μm.

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