Equipment and process method for preparing polyvinyl chloride fiber by melt spinning method

Abstract

According to the technical scheme, the equipment and the technological method for preparing the polyvinyl chloride fibers through the melt spinning method are provided, the unique spinning assembly is designed, and the spinning assembly comprises an outer shell, a conical melt flow channel distribution body arranged in the outer shell and a spinning plate assembled on the lower end face of the melt flow channel distribution body; a plurality of semi-fan-shaped holes are evenly distributed in the conical surface of the upper end face of the melt runner distribution body along a generatrix, every two adjacent semi-fan-shaped holes intersect to form a semi-fan-shaped knife edge, a plurality of round holes are evenly distributed in the conical surface of the lower end face of the melt runner distribution body along the generatrix, and a plurality of spinneret holes are evenly distributed in the spinneret plate. Each round hole is in smooth transition with the corresponding half-fan-shaped hole to form runner cavities which are evenly distributed along the generatrix of the conical surface of the melt runner distribution body, the round holes and the spinneret holes are arranged in a one-to-one correspondence mode so that it can be guaranteed that no liquid accumulation area exists in the melt in the spinneret assembly, and meanwhile the two-time feeding mode is achieved in the technological method.

Description

Technical Field

[0001] The invention relates to the field of preparation of polyvinyl chloride, and in particular to equipment and a process for preparing polyvinyl chloride fibers by melt spinning. Background Art

[0002] Polyvinyl chloride fiber is a synthetic fiber made of polyvinyl chloride or its copolymers, which has the effects of high strength, non-flammability, acid and alkali corrosion resistance. The existing technology usually produces fibers by wet spinning or dry spinning of polyvinyl chloride resin, but both wet spinning and dry spinning processes require the polyvinyl chloride resin to be swollen in acetone. Acetone is a flammable and toxic substance that will pollute the environment, and this production method is inefficient. However, polyvinyl chloride (PVC) resin is a polymer that is insoluble in its monomer, so in its early polymerization process, the polymerization product will precipitate and grow into primary particles. The particles exist in the form of glassy microspheres to form tassel-shaped microbundle crystals. They cannot be completely melted during the heat extrusion process. During the processing, they flow in the form of molecular bundles containing about 10 million molecules. The primary particles interact through partial melting, entanglement, fusion and recrystallization, so it is difficult to directly carry out melt spinning processing of PVC resin.

[0003] In order to solve the problem that polyvinyl chloride (PVC) resin is prone to thermal oxidative degradation during heating, the method currently used in the melt spinning process of polyvinyl chloride is to add heat stabilizers, plasticizers, lubricants, etc. during the granulation process: for example, domestic and foreign scholars add heat stabilizers, plasticizers and other additives to PVC resin, and use a short-process melt spinning process to prepare PVC fibers for use in the wig industry; Liu Shujia's team at Donghua University studied the melt spinning of PVC hair fibers under different molding processes; Liu Mengzhu and others from Dalian University of Technology used the melt spinning method to study the rheology and thermal stability of PVC systems with different additive contents, starting from PVC raw materials, plasticizers, heat stabilizers and other additives, and prepared PVC fibers for hair with good thermal stability; Application No. 20161 09916703 discloses a method for producing polyvinyl chloride hair fibers for hair, wherein the main materials are low-polymerization degree, relatively high-polymerization degree and high-polymerization degree polyvinyl chloride; the invention patent application No. 200480028726.0 of Nippon Electric Chemical Industry Co., Ltd. discloses "polyvinyl chloride fibers for artificial hair, a method for producing the same and a manufacturing device thereof", wherein the polyvinyl chloride fibers for artificial hair are obtained by spinning a polyvinyl chloride resin composition using a nozzle having a nozzle hole diameter of D=2mm, an aspect ratio L / D=1~3, a nozzle introduction part thickness of 4mm or more, and an introduction angle of 20~90°; however, the PVC melt-spun fibers described in the above documents can only be used in industries such as wigs or toy doll hair, and cannot meet the requirements of the textile industry for stable size of the woven fiber mesh. This is because the melt processing temperature of polyvinyl chloride resin is usually (160-190°C). At this temperature, antioxidants and plasticizers are easily decomposed, volatilized and precipitated, which requires a shorter melt processing time. Otherwise, the melt is prone to yellowing, blackening, aging and degradation, and the requirement for dimensional stability of the fiber mesh cannot be achieved.

[0004] Conventional melt spinning equipment basically includes screw extruder, melt filter, metering pump, melt distribution plate, spinneret, cooling winding system, etc. After the melt flows out of the distribution plate, it flows flat to the upper surface of the spinneret. There is a liquid accumulation area before the melt flows out of the distribution plate under pressure and enters the spinneret. The melt in the liquid accumulation area just above or near the spinneret guide hole can directly enter the guide hole, but the melt in the liquid accumulation area in the middle of the line between the guide holes must flow parallel to the spinneret guide hole in a nearly vertical direction to enter the guide hole, that is, there is a flow of about 90°, which makes it easy to form eddy current dead corners in the liquid accumulation area, which easily leads to the retention of a small amount of PVC resin. Moreover, due to the poor thermal stability of PVC, at the spinning temperature, the retained PVC resin gradually turns red, turns yellow, and then gradually turns black and carbonized, causing the spinning process to terminate. In addition, due to the low crystallinity of polyvinyl chloride resin, its fibers and other products exhibit typical viscoelastic mechanical properties. The PVC fibers processed using conventional chemical fiber equipment have a large elongation at break and shrink slowly, especially during the heating and water washing process, where the shrinkage is more obvious. This also limits the practical application of polyvinyl chloride fibers. Summary of the invention

[0005] The purpose of the present invention is to provide a device and a process method for preparing polyvinyl chloride fibers by a melt spinning method. A melt spinning device is designed in which the entire melt flow channel has a smooth transition and no vortex dead corners, thereby solving the problem of easy formation of vortex dead corners in the design of traditional melt spinning components. A process method for adding additives in two stages is designed, thereby reducing the volatilization of the additives and slowing down the oxidative decomposition of PVC.

[0006] To achieve the above objectives, the present technical solution provides a device for preparing polyvinyl chloride fibers by melt spinning, comprising: a feeding component, a melt spinning component, a cooling component, a heating component, a heat setting component and a winding component, wherein polyvinyl chloride masterbatch and additives are added from the feeding component to the melt spinning component for melt spinning to form polyvinyl chloride monofilaments, and the polyvinyl chloride monofilaments are sequentially cooled by the cooling component, heated by the heating component, heat set by the heat setting component and wound by the winding component to obtain polyvinyl chloride fibers; wherein the melt spinning component comprises a screw extruder, a spinning metering pump and a spinneret component connected in sequence, and the spinneret component The component includes an outer shell, a conical melt flow channel distributor installed in the outer shell, and a spinneret installed on the lower end surface of the melt flow distributor. A plurality of semi-fan-shaped holes are evenly distributed along the generatrix on the conical surface of the upper end surface of the melt flow channel distributor, and adjacent semi-fan-shaped holes intersect to form a semi-fan-shaped blade. A plurality of circular holes are evenly distributed along the generatrix on the conical surface of the lower end surface of the melt flow channel distributor, and a plurality of spinneret holes are evenly distributed on the spinneret. Each circular hole smoothly transitions with the corresponding semi-fan-shaped hole to form a flow channel cavity evenly distributed along the generatrix of the conical surface of the melt flow channel distributor, and the circular holes and the spinneret holes are arranged one by one.

[0007] The present invention provides a process for preparing polyvinyl chloride fibers by melt spinning, which is realized by relying on equipment for preparing polyvinyl chloride fibers by melt spinning, and comprises the following steps: polyvinyl chloride masterbatch, antioxidant, plasticizer, first heat stabilizer, internal lubricant and external lubricant are mixed, and then added from a feeding component to a screw extruder for melt spinning to obtain a polyvinyl chloride melt; a second heat stabilizer and a cross-linking agent are mixed and pressurized to achieve pressure balance with the polyvinyl chloride melt, and then added to the connecting flange position of the screw extruder and a spinning metering pump, and then extruded by the spinning metering pump, the mixture enters the spinneret component to extrude polyvinyl chloride monofilaments; the polyvinyl chloride monofilaments are sequentially cooled by a cooling component, heated by a heating component, heat-set by a heat-setting component, and wound by a winding component to obtain polyvinyl chloride fibers.

[0008] Compared with the prior art, this technical solution has the following characteristics and beneficial effects: 1. Through the design of a unique spinneret assembly, the conical design of the melt flow distributor, combined with the smooth transition between the semi-fan-shaped holes and the circular holes, the flow cavity is formed to achieve uniform melt distribution, so that the flow cavity in the spinneret assembly has no right angles or mutations, avoiding the vortex and liquid accumulation area caused by the discontinuity of the flow channel of the traditional spinneret. Reduce the residence time of the melt in the flow channel, prevent PVC from thermal decomposition due to high temperature, improve fiber uniformity and strength, and extend the cleaning or replacement cycle of the spinneret assembly.

[0009] 2. Through the secondary feeding method, the volatilization or premature reaction of heat-sensitive additives in the high-temperature extrusion section is reduced, and the utilization rate is increased by 20-30%. In addition, through pressure-balanced injection, the additives and the melt are evenly mixed to avoid fiber defects caused by excessive local concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the overall structure of the equipment for preparing polyvinyl chloride fibers by the melt spinning method of this scheme.

[0011] Figure 2 It is a structural schematic diagram of the outer shell.

[0012] Figure 3 It is a schematic diagram of the overall structure of the melt flow channel distributor.

[0013] Figure 4 It is a top view of the upper end surface of the melt flow channel distributor.

[0014] Figure 5 It is a cross-sectional view of the lower end surface of the melt flow channel distributor.

[0015] Figure 6 is a cross-sectional view of the spinneret.

[0016] Figure 7 It is a top view of the spinneret.

[0017] In the figure: a feeding component (10), a melt spinning component (20), a cooling component (30), a heating component (40), a heat setting component (50), a winding component (60), a screw extruder (21), a spinning metering pump (22) and a spinneret component (23), an outer shell (231), a melt flow channel distributor (232), a spinneret (233), a semi-fan-shaped hole (2321), a circular hole (2322), a spinneret hole (2331), a flow channel cavity (2320), a first feeding unit (11), a second feeding unit (12), a mixer (111), a feeder (112), a silo (113), a first feeding port (114), an additive tank (121), a booster pump (122), an additive metering pump (123), and a second feeding port (124). DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0019] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0020] Embodiment 1 Figure 1 The overall structure diagram of the equipment for preparing polyvinyl chloride fiber by melt spinning provided in this scheme is as follows: Figure 1 As shown, the apparatus for preparing polyvinyl chloride fiber by melt spinning provided in this scheme comprises: A feeding component (10), a melt spinning component (20), a cooling component (30), a heating component (40), a heat setting component (50), and a winding component (60), wherein polyvinyl chloride masterbatch and an auxiliary agent are added from the feeding component (10) into the melt spinning component (20) for melt spinning to form polyvinyl chloride monofilaments, and the polyvinyl chloride monofilaments are sequentially cooled by the cooling component (30), heated by the heating component (40), heat set by the heat setting component (50), and wound by the winding component (60) to obtain polyvinyl chloride fibers; The melt spinning assembly (20) comprises a screw extruder (21), a spinning metering pump (22) and a spinneret assembly (23) connected in sequence, the spinneret assembly (23) comprising an outer shell (231), a conical melt flow channel distributor (232) installed in the outer shell (231), and a spinneret (233) mounted on the lower end surface of the melt flow channel distributor (232), a plurality of semi-fan-shaped holes (2321) are evenly distributed along a generatrix on the conical surface of the upper end surface of the melt flow channel distributor (232), and adjacent semi-fan-shaped holes (2321) are evenly distributed along a generatrix. The fan-shaped holes intersect to form a semi-fan-shaped blade, a plurality of circular holes (2322) are evenly distributed along the generatrix on the conical surface of the lower end surface of the melt flow channel distributor (232), and a plurality of spinneret holes (2331) are evenly distributed on the spinneret plate (233), and each circular hole (2322) smoothly transitions with the corresponding semi-fan-shaped hole (2321) to form a flow channel cavity (2320) evenly distributed along the generatrix of the conical surface of the melt flow channel distributor (232), and the circular holes (2322) and the spinneret holes (2331) are arranged in a one-to-one correspondence.

[0021] The present invention is particularly designed for a spinneret assembly for melt spinning of polyvinyl chloride. After the polyvinyl chloride and the additives are melt-spun in a screw extruder (21), they are pumped into the spinneret assembly (23) in the form of a melt through a spinning metering pump (22). The cylindrical plug flow melt pumped out from the spinning metering pump (22) is divided into an annular melt at the top of the cone of the melt flow channel distributor (23). The annular melt flows from the semi-fan-shaped hole (232) of the melt flow channel distributor (23). 321) flows into the flow channel cavity (2320) and flows out from the first circular hole (2322) of the melt flow channel distributor (232), and then enters the corresponding spinneret hole (2331) to be ejected. The design of the spinneret assembly of this scheme allows the flow channel cavity (2320) to have a smooth transition without vortex dead corners, that is, the melt will not generate vertical flow in the spinneret assembly, and no liquid accumulation area will be generated, thereby eliminating the problems of vortex dead corners and melt retention, and extending the replacement cycle of the spinneret assembly.

[0022] Specifically, Figure 2 FIG. 2 is a schematic diagram of the structure of the outer shell (231) of the present invention. Figures 3 to 5 The figure shows the structure of the melt flow channel distributor (232) of the present invention, wherein Figure 3 is a schematic diagram of the overall structure of the melt flow channel distributor (232). Figure 4 is a top view of the upper end surface of the melt flow channel distributor (232), Figure 5 is a cross-sectional view of the lower end surface of the melt flow channel distributor (232), Figure 6 to Figure 7 is a schematic diagram of the structure of the spinneret (233) of this scheme, wherein Figure 6 is a cross-sectional view of the spinneret (233), Figure 7 It is a top view of the spinneret (233) of this embodiment.

[0023] The outer shell (231) of the present solution is designed to be a truncated cone with a small top and a large bottom. Specifically, the outer shell (231) comprises a first channel, a conical main channel, and a second channel which are connected from top to bottom, wherein the width of the first channel is smaller than the width of the second channel, and the width of the conical main channel gradually increases from top to bottom, and the first channel is connected to the melt pipe of the spinning metering pump (22).

[0024] In some embodiments, the first channel and the second channel are designed to be cylindrical. As described above, the advection flow out of the melt pipe of the spinning metering pump (22) pushes the melt from the first channel into the spinning assembly (23).

[0025] The melt flow channel distributor (232) of the present embodiment is a cone with a flow channel cavity (2320) formed on the outside, wherein the cone angle α of the cone is 60 to 90°, wherein the size of the cone angle determines the height of the melt flow channel distributor (232). When the cone angle α is greater than 90°, the melt pushed by the cylindrical horizontal flow out of the spinning metering pump (22) is not easy to be diverted into a circular ring shape; when the cone angle α is less than 60°, the melt flow channel distributor (232) is too high, and the mechanical processing difficulty of the flow channel cavity (2320) increases.

[0026] In a specific embodiment, the cone vertex angle of the conical main body channel of the outer shell (231) is the same as the cone angle of the cone of the melt flow channel distributor (232), which is also 60 to 90 degrees. The horizontal position of the tip of the cone of the melt flow channel distributor (232) is located on the horizontal line where the first channel of the outer shell (231) and the conical main body channel meet, and the main body of the cone of the melt flow channel distributor (232) is placed in the conical main body channel of the outer shell (231), the outer wall of the flow channel cavity (2320) is connected to the inner wall of the conical main body channel, and the lower end surface of the spinneret (233) is flush with the lower end surface of the second channel.

[0027] In some embodiments, 24 to 48 flow channel cavities (2320) are evenly distributed along the busbar on the conical surface of the melt flow channel distributor (232), and the number of flow channel cavities (2320) is related to the diameter of the lower end surface of the melt flow channel distributor (232) and the diameter of the spinneret (233). When the number of flow channel cavities (2320) is less than 24, the spacing between the spinneret holes (2331) on the spinneret (233) is large, and the number of filaments formed by spinning is small; and when the number of flow channel cavities (2320) is greater than 48, the semi-fan-shaped holes on the upper end surface of the melt flow channel distributor (232) are too dense, resulting in increased difficulty in mechanical processing.

[0028] like Figure 3As shown, the flow channel cavity (2320) formed on the conical surface of the melt flow channel distributor (232) is formed by the semi-fan-shaped hole (2321) on the upper end surface and the circular hole (2322) on the lower end surface of the melt flow channel distributor (232), and there is a smooth transition between the semi-fan-shaped hole (2321) and the corresponding circular hole (2322). In some embodiments, the width of the flow channel cavity (2320) gradually decreases from top to bottom.

[0029] Correspondingly, 24 to 48 semi-fan-shaped holes (2321) are evenly distributed along the generatrix on the conical surface of the upper end surface of the melt flow channel distributor (232), such as Figure 4 The melt flow channel distributor (232) shown has 24 semi-fan-shaped holes (2321) on the conical surface of the upper end surface.

[0030] Specifically, each half of the fan-shaped hole (2321) is a truncated cone with a central opening, and the side wall of each half of the fan-shaped hole (2321) is a fan-shaped arc surface. The melt dispersed into a circular ring enters the flow channel cavity (2320) from the opening position of the half fan-shaped hole (2321).

[0031] In some embodiments, the evenly distributed semi-fan-shaped holes (2321) on the upper end surface of the melt flow channel distributor (232) are adjacently arranged to form a circular ring, and the openings of the semi-fan-shaped holes (2321) are also located on the same circular ring. Adjacent semi-fan-shaped holes (2321) intersect with each other to form a semi-fan-shaped blade, and the circular ring formed by the semi-fan-shaped holes (2321) is also an arc-shaped blade-shaped protrusion, so that the melt diverted by the tip of the cone can be evenly divided into 24 to 48 parts, so that no eddy current dead angle and melt retention are generated, and each melt enters the flow channel cavity (2320) and flows downward.

[0032] like Figure 5 As shown, a plurality of circular holes (2322) are evenly distributed along the generatrix on the conical surface of the lower end face of the melt flow channel distributor (232), and the number and position of the circular holes (2322) correspond to the semi-fan-shaped holes (2321) to form a flow channel cavity (2320). In some embodiments, the diameter of the circular hole (2322) is 3 to 4 mm. It is emphasized again that the channel of the flow channel cavity (2320) formed by the circular hole (2322) and the semi-fan-shaped hole (2321) of this solution has a smooth wall surface to facilitate the flow of the melt.

[0033] like Figure 6 and Figure 7As shown, the spinneret (233) and the melt flow channel distributor (232) are mirror-sealed to prevent the melt from leaking under pressure. The number and position of the spinneret holes (2331) on the spinneret (233) correspond to the circular holes (2322) one by one, so that the melt flowing out of each flow channel cavity (2320) can enter the spinneret holes (2331), so as to ensure that there is no liquid accumulation area, and eliminate dead corners and melt retention.

[0034] like Figure 6 As shown, each spinneret hole (2331) is a truncated cone with a larger top and a smaller bottom. The upper surface of the spinneret hole (2331) is a circular inlet with the same diameter as the circular hole (2322), and the lower surface is a circular outlet with a smaller diameter than the circular hole (2322), and there is a smooth transition between the circular inlet and the circular outlet.

[0035] In some embodiments, the diameter of the circular inlet of the spinneret (2331) is 3-4 mm, the diameter of the circular outlet is 0.3-0.35 mm, and the taper formed between the circular inlet and the circular outlet is 10-20°.

[0036] A plurality of spinneret holes (2331) are evenly distributed on the spinneret hole (233), and each circular hole (2322) smoothly transitions with the corresponding semi-fan-shaped hole (2321) to form a flow channel cavity (2320) evenly distributed along the generatrix of the conical surface of the melt flow channel distributor (232).

[0037] In addition, the feeding assembly (10) of the apparatus for preparing polyvinyl chloride fibers by melt spinning of the present scheme comprises a first feeding unit (11) and a second feeding unit (12), wherein the first feeding unit (11) comprises a mixer (111), a feeder (112), a silo (113) and a first feeding port (114) connected in sequence, and the first feeding port (114) is connected to the screw extruder (21); wherein the second feeding unit (12) comprises an auxiliary agent tank (121), a booster pump (122), an auxiliary agent metering pump (123) and a second feeding port (124) connected in sequence, and the second feeding port (124) is connected to the connecting flange of the screw extruder (21) and the spinning metering pump (22). The feeding assembly (10) of the present scheme adopts a secondary feeding method in the melt spinning process of polyvinyl chloride to reduce the volatilization of the auxiliary agent and slow down the oxidative decomposition of PVC.

[0038] In some embodiments, the first feeding unit (11) is used to add polyvinyl chloride masterbatch, antioxidant, plasticizer, first heat stabilizer, internal lubricant and external lubricant, wherein the polyvinyl chloride masterbatch, antioxidant, plasticizer, first heat stabilizer, internal lubricant and external lubricant are mixed in the mixer (111), fed into the first feed port (114) through the feeder (112), and melt-spun through the screw extruder (21).

[0039] In some embodiments, the second feeding unit (12) is used to add a second heat stabilizer and a cross-linking agent, wherein the second heat stabilizer and the cross-linking agent are liquid additives. After the liquid additives are pressurized twice by the booster pump (122) and the additive metering pump (123) to reach a state of pressure equilibrium with the polyvinyl chloride melt, they enter the screw extruder (21) and are mixed with the polyvinyl chloride melt before being extruded.

[0040] Specifically, the second feeding unit (12) is arranged at the connection flange of the screw extruder (21) and the spinning metering pump (22). The reaction raw materials added to the first feeding unit (11) are gradually melted and pushed through the feeding section and the compression section of the screw extruder (21). After further plasticization in the metering section, they are squeezed into the connecting flange at a certain pressure to obtain a polyvinyl chloride melt. The liquid additive in the second feeding unit (12) is pressurized to the same pressure as the polyvinyl chloride melt and then squeezed into the polyvinyl chloride melt. After being evenly mixed by the melt static mixer arranged in the outlet of the connecting flange, they flow into the spinneret assembly (23) through the spinning metering pump.

[0041] In some embodiments, the degree of polymerization of the polyvinyl chloride masterbatch of the first feeding unit (11) is 900-1200. Based on 100 parts by weight, the weight of the antioxidant is 0.5-1, the weight of the plasticizer is 30-40, the weight of the internal lubricant is 1-3, the weight of the external lubricant is 1-2, and the weight of the first thermal stabilizer is 0.1-0.5.

[0042] In some embodiments, the antioxidant is selected as 1010, the plasticizer is selected as one or any combination of dioctyl phthalate (DOP) and dibutyl phthalate (DBP), the internal lubricant is selected as one or any combination of paraffin wax, polyvinyl chloride wax, and oxidized polyvinyl chloride wax; the external lubricant is selected as one or any combination of glyceryl monostearate, calcium stearate, lead stearate, barium stearate and zinc stearate.

[0043] In some embodiments, the first stabilizer is selected as dibutyltin laurate maleate, and the weight portion of dibutyltin laurate maleate is 0.2-0.5; or it is selected as dibutyltin dilaurate, and the weight portion of dibutyltin dilaurate is 0.2-0.5; or it is selected as triphenyl phosphite, and the weight portion of triphenyl phosphite is 0.1-0.3.

[0044] In some embodiments, based on 100 parts by weight of the polychloroacetic acid masterbatch, the weight of the second heat stabilizer in the second feeding unit (12) is 0.1 to 0.3 parts, and the weight of the cross-linking agent is 0.2 to 0.4 parts.

[0045] In some embodiments, the cross-linking agent is selected from one or any combination of dicumyl peroxide, di-tert-butyl dicumyl peroxide (DCP); the second thermal stabilizer is selected as epoxidized soybean oil, the weight portion of epoxidized soybean oil is 0.1-0.2, the second thermal stabilizer is selected as methyltin isooctyl ethyl ester, the weight portion of methyltin isooctyl ethyl ester is 0.1-0.2, the second thermal stabilizer is selected as organic tin such as butyl tin mercaptan, the weight portion of organic tin such as butyl tin mercaptan is 0.1-0.3.

[0046] In some embodiments, the cross-linking agent selected in this scheme is an ultraviolet cross-linking agent. Therefore, correspondingly, after the winding component (60) is wound, the polyvinyl chloride fiber is subjected to ultraviolet light for 30 to 60 seconds to obtain the cross-linked polyvinyl chloride fiber, so that a small amount of cross-linking reaction occurs between the ultraviolet cross-linking agent and the PVC linear macromolecules, so that the elongation of the PVC fiber remains stable in a relaxed state and no longer shrinks slowly. At the same time, the long-lasting effect of the heat stabilizer is improved to prevent the thermal oxidation degradation of the PVC in the spinning box.

[0047] Embodiment 2 This solution provides a process for preparing polyvinyl chloride fibers by melt spinning, which is implemented based on the equipment for preparing polyvinyl chloride fibers by melt spinning shown in Example 1, and includes the following steps: The polyvinyl chloride masterbatch, antioxidant, plasticizer, first heat stabilizer, internal lubricant and external lubricant are mixed and added into a screw extruder (21) from a feeding component (10) for melt spinning to obtain a polyvinyl chloride melt; The second heat stabilizer and the cross-linking agent are mixed and pressurized until the pressure is balanced with that of the polyvinyl chloride melt, and then added to the connecting flange position of the screw extruder (21) and the spinning metering pump (22), and then extruded by the spinning metering pump (22) and entered into the spinneret assembly (23) to extrude the polyvinyl chloride monofilament; The polyvinyl chloride monofilament is sequentially cooled by a cooling component (30), heated by a heating component (40), heat-set by a heat-setting component (50), and rolled up by a rolling component (60) to obtain polyvinyl chloride fibers.

[0048] In some embodiments, the degree of polymerization of the polyvinyl chloride masterbatch is 900-1200. Based on 100 parts by weight, the weight portion of the antioxidant is 0.5-1, the weight portion of the plasticizer is 30-40, the weight portion of the internal lubricant is 1-3, the weight portion of the external lubricant is 1-2, and the weight portion of the first thermal stabilizer is 0.1-0.5.

[0049] In some embodiments, the antioxidant is selected as 1010, the plasticizer is selected as one or any combination of dioctyl phthalate (DOP) and dibutyl phthalate (DBP), the internal lubricant is selected as one or any combination of paraffin wax, polyvinyl chloride wax, and oxidized polyvinyl chloride wax; the external lubricant is selected as one or any combination of glyceryl monostearate, calcium stearate, lead stearate, barium stearate and zinc stearate.

[0050] In some embodiments, the first thermal stabilizer is selected from one or any combination of dibutyltin laurate maleate, dibutyltin dilaurate, and triphenyl phosphite. The first stabilizer is selected from dibutyltin laurate maleate, and the weight portion of dibutyltin laurate maleate is 0.2-0.5; or selected from dibutyltin dilaurate, and the weight portion of dibutyltin dilaurate is 0.2-0.5; or selected from triphenyl phosphite, and the weight portion of triphenyl phosphite is 0.1-0.3.

[0051] In some embodiments, based on 100 parts by weight of the polychloroacetic acid masterbatch, the weight of the second thermal stabilizer is 0.1 to 0.3, and the weight of the cross-linking agent is 0.2 to 0.4.

[0052] In some embodiments, the cross-linking agent is selected from one or any combination of diisopropylbenzene peroxide and di-tert-butyl diisopropylbenzene peroxide (DCP); the second thermal stabilizer is selected from one or any combination of epoxyd soybean oil, methyltin isooctyl ethyl ester, and butyltin mercaptan. When the second thermal stabilizer is selected as epoxyd soybean oil, the weight portion of the epoxyd soybean oil is 0.1-0.2; when the second thermal stabilizer is selected as methyltin isooctyl ethyl ester, the weight portion of methyltin isooctyl ethyl ester is 0.1-0.2; when the second thermal stabilizer is selected as organic tin such as butyltin mercaptan, the weight portion of the organic tin such as butyltin mercaptan is 0.1-0.3.

[0053] In some embodiments, the cross-linking agent selected in this scheme is an ultraviolet cross-linking agent. Therefore, correspondingly, after the winding component (60) is wound, the polyvinyl chloride fiber is subjected to ultraviolet light for 30 to 60 seconds to obtain the cross-linked polyvinyl chloride fiber, so that a small amount of cross-linking reaction occurs between the ultraviolet cross-linking agent and the PVC linear macromolecules, so that the elongation of the PVC fiber remains stable in a relaxed state and no longer shrinks slowly. At the same time, the long-lasting effect of the heat stabilizer is improved to prevent the thermal oxidation degradation of the PVC in the spinning box.

[0054] Embodiment 3 Specific design of the spinneret assembly The spinneret assembly provided in this embodiment has 24 flow channel cavities evenly distributed along the busbar on the conical surface of the melt flow channel distributor, the top cone angle α of the melt flow channel distributor is 60°, and 24 semi-fan-shaped holes are evenly distributed on the circular upper end face, the holes intersect to form sharp knife-like protrusions, and the outer circle of the ring is also an arc-shaped sharp knife-like protrusion, so that the melt flowing from the spinning metering pump is evenly divided into 24 equal parts, and 24 circular holes with a diameter of 4 mm are evenly distributed on the circular ring of the lower end face of the melt flow channel distributor, the connecting channel between the semi-fan-shaped holes on the upper end face ring and the circular holes on the lower end face has a smooth transition, and the channel wall is smooth. The spinneret is installed under the melt flow channel distributor, and the two are mirror-sealed. There are 24 spinneret holes evenly distributed on the spinneret. The diameter and distribution of the circular inlet of the spinneret hole correspond one-to-one with the circular hole on the lower end ring of the melt flow channel distributor. The size is consistent, and the position is fixed by the positioning pin, so that the melt in each flow channel cavity flows into the spinneret hole one-to-one. The taper θ1 of the circular inlet of the spinneret hole is 11°. The diameter of the circular outlet hole of the spinneret is 0.35mm, and the inner cavity cone vertex angle of the outer shell is also α. The melt flow channel distributor and the spinneret are installed in the outer shell together and fit tightly. The upper end of the outer shell is connected to the melt pipe of the spinning metering pump. The cylindrical melt flowing from the melt pipe is gradually diverted into a circular ring at the top of the melt flow channel distributor, and is evenly divided into 24 equal parts when flowing through the inlet of the semi-fan-shaped hole on the upper end ring. Each melt flows into the spinneret hole through the flow channel cavity, and is then ejected from the circular outlet of the spinneret after compression.

[0055] Embodiment 4 Specific design of the spinning assembly The spinneret assembly provided in this embodiment has 30 flow channel cavities evenly distributed along the busbar on the conical surface of the melt flow channel distributor. The top cone angle of the melt flow channel distributor is 70°, and 30 semi-fan-shaped holes are evenly distributed on the circular upper end face. The holes intersect to form sharp knife-like protrusions, and the outer circle of the ring is also an arc-shaped sharp knife-like protrusion, so that the melt flowing from the melt pipe is evenly divided into 30 equal parts, and 30 circular holes with a diameter of 4 mm are evenly distributed on the circular ring of the lower end face of the melt flow channel distributor. The connecting channel between the semi-fan-shaped holes on the upper end face ring and the circular holes on the lower end face has a smooth transition, and the channel wall is smooth. The spinneret is assembled under the melt flow channel distributor, and the two are mirror-sealed. There are 30 spinneret holes evenly distributed on the spinneret. The diameter and distribution of the circular inlet of the spinneret holes correspond one-to-one with the circular holes on the circular ring of the lower end face of the melt flow channel distributor. The size is consistent, and the position is fixed by the positioning pin, so that the melt in each flow channel cavity flows into the spinneret introduction hole one-to-one. The taper θ1 of the circular inlet of the spinneret is 15°. The diameter of the circular outlet of the spinneret is 0.35mm. The inner cavity cone vertex angle of the outer shell is also 70°. The melt flow channel distributor and the spinneret are installed in the outer shell together and fit tightly. The upper end of the outer shell is connected to the melt pipe. The cylindrical melt flowing from the melt pipe is gradually diverted into a ring shape at the top of the cone of the melt flow channel distributor, and is evenly divided into 30 equal parts when flowing through the entrance of the upper half of the fan-shaped hole of the upper end ring. Each melt flows into the spinneret hole through the flow channel cavity, and is then ejected from the circular outlet of the spinneret after compression.

[0056] Embodiment 5 In addition to the 36 flow channel cavities evenly distributed along the busbar on the conical surface of the melt flow channel distributor, the top cone angle of the melt flow channel distributor is 80°, 36 semi-fan-shaped holes are evenly distributed on the circular upper end surface, 36 circular holes with a diameter of 4 mm are evenly distributed on the lower end ring, 36 spinneret holes are evenly distributed on the spinneret, the inner cavity cone top angle of the outer shell is 80°, and other parameters are the same as those in Example 4.

[0057] Those skilled in the art should understand that the technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A device for preparing polyvinyl chloride fiber by melt spinning, characterized in that: include: A feeding component, a melt spinning component, a cooling component, a heating component, a heat setting component and a winding component, wherein polyvinyl chloride masterbatch and additives are added from the feeding component to the melt spinning component for melt spinning to form polyvinyl chloride monofilaments, and the polyvinyl chloride monofilaments are sequentially cooled by the cooling component, heated by the heating component, heat set by the heat setting component and wound by the winding component to obtain polyvinyl chloride fibers; The melt spinning component includes a screw extruder, a spinning metering pump and a spinneret component connected in sequence, the spinneret component includes an outer shell, a conical melt flow channel distributor installed in the outer shell, and a spinneret plate assembled on the lower end face of the melt fluid distributor, a plurality of semi-fan-shaped holes are evenly distributed along the busbar on the conical surface of the upper end face of the melt flow channel distributor, adjacent semi-fan-shaped holes intersect to form a semi-fan-shaped blade, a plurality of circular holes are evenly distributed along the busbar on the conical surface of the lower end face of the melt flow channel distributor, a plurality of spinneret holes are evenly distributed on the spinneret, each circular hole smoothly transitions with the corresponding semi-fan-shaped hole to form a flow channel cavity evenly distributed along the busbar of the conical surface of the melt flow channel distributor, and the circular holes and the spinneret holes are arranged in a one-to-one correspondence.

2. The device for preparing polyvinyl chloride fiber by melt spinning method according to claim 1, characterized in that: The outer shell includes a first channel, a conical main channel and a second channel which are connected from top to bottom, wherein the width of the first channel is smaller than that of the second channel, the width of the conical main channel gradually increases from top to bottom, and the first channel is connected to the melt pipe of the spinning metering pump.

3. The device for preparing polyvinyl chloride fiber by melt spinning method according to claim 2, characterized in that: The horizontal position of the tip of the cone of the melt flow channel distributor is located on the horizontal line where the first channel of the outer shell and the cone main body channel meet, and the main body of the cone of the melt flow channel distributor is placed in the cone main body channel of the outer shell, the outer wall of the flow channel cavity is connected to the inner wall of the cone main body channel, and the lower end surface of the spinneret is flush with the lower end surface of the second channel.

4. The equipment for preparing polyvinyl chloride fiber by melt spinning method according to claim 1, characterized in that: The melt flow channel distributor is a cone with a flow channel cavity formed on the outside, wherein the cone angle α of the cone is 60 to 90 degrees.

5. The equipment for preparing polyvinyl chloride fiber by melt spinning method according to claim 1, characterized in that: 24 to 48 flow channel cavities are evenly distributed along the generatrix on the conical surface of the melt flow channel distributor.

6. The device for preparing polyvinyl chloride fiber by melt spinning according to claim 1, characterized in that: Each half-sector-shaped hole is a truncated cone with a central opening, and the side wall of each half-sector-shaped hole is a sector-shaped arc surface. The half-sector-shaped holes evenly distributed on the upper end surface of the melt flow channel distributor are adjacently arranged to form a ring, and the openings of the half-sector-shaped holes are also located on the same ring.

7. The device for preparing polyvinyl chloride fiber by melt spinning according to claim 1, characterized in that: Each spinneret hole is a truncated cone with a larger upper surface and a smaller lower surface. The upper surface of the spinneret hole is a circular inlet with the same diameter as the circular hole, and the lower surface is a circular outlet with a smaller diameter than the circular hole, and there is a smooth transition between the circular inlet and the circular outlet.

8. The device for preparing polyvinyl chloride fiber by melt spinning according to claim 1, characterized in that: The feeding component includes a first feeding unit and a second feeding unit, wherein the first feeding unit includes a mixer, a feeder, a silo and a first feed port connected in sequence, and the first feed port is communicated with a screw extruder; wherein the second feeding unit includes an additive tank, a booster pump, an additive metering pump and a second feed port connected in sequence, and the second feed port is communicated with a connecting flange of the screw extruder and the spinning metering pump, the first feeding unit is used for adding polyvinyl chloride masterbatch, an antioxidant, a plasticizer, a first heat stabilizer, an internal lubricant and an external lubricant, and the second feeding unit is used for adding a second heat stabilizer and a cross-linking agent.

9. A process for preparing polyvinyl chloride fibers by melt spinning, which is realized by using the apparatus for preparing polyvinyl chloride fibers by melt spinning as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: The polyvinyl chloride masterbatch, antioxidant, plasticizer, first heat stabilizer, internal lubricant and external lubricant are mixed and added into a screw extruder from a feeding component for melt spinning to obtain a polyvinyl chloride melt; The second heat stabilizer and the crosslinking agent are mixed and pressurized to balance the pressure with the polyvinyl chloride melt, and then added to the connecting flange position of the screw extruder and the spinning metering pump, and then extruded by the spinning metering pump into the spinneret assembly to extrude the polyvinyl chloride monofilament; The polyvinyl chloride monofilament is sequentially cooled by a cooling component, heated by a heating component, heat-set by a heat-setting component, and rolled up by a rolling component to obtain the polyvinyl chloride fiber.

10. The process for preparing polyvinyl chloride fiber by melt spinning according to claim 9, characterized in that: The polymerization degree of the polyvinyl chloride masterbatch is 900-1200, the antioxidant is selected as 1010, the plasticizer is selected as one or any combination of dioctyl phthalate and dibutyl phthalate, the internal lubricant is selected as one or any combination of paraffin, polyethylene wax, and oxidized polyethylene wax; the external lubricant is selected as one or any combination of glyceryl monostearate, calcium stearate, lead stearate, barium stearate and zinc stearate, the crosslinking agent is selected from one or any combination of diisopropylbenzene peroxide and di-tert-butyl diisopropylbenzene peroxide, the first thermal stabilizer is selected as one or any combination of dibutyltin laurate maleate, dibutyltin dilaurate, and triphenyl phosphite, and the second thermal stabilizer is selected as one or any combination of epoxy soybean oil, methyltin isooctyl ethyl ester, and butyltin mercaptan.

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