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

Abstract

This solution provides an apparatus and a process method for preparing polyvinyl chloride fibers by melt spinning. The apparatus is designed with a unique spinneret assembly, which includes an outer housing, a conical melt flow channel distributor disposed within the outer housing, and a spinneret plate assembled to the lower end face of the melt flow distributor. A plurality of semi-sector-shaped holes are evenly distributed along the generatrix on the conical surface of the upper end face of the melt flow channel distributor, and semi-sector-shaped knife edges are formed by the intersection between adjacent semi-sector-shaped holes. A plurality of circular holes are evenly distributed along the generatrix on the conical surface of the lower end face of the melt flow channel distributor, and a plurality of spinneret holes are evenly distributed on the spinneret plate. Each circular hole is smoothly transitioned with the corresponding semi-sector-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 in one-to-one correspondence to ensure that there is no liquid accumulation area in the spinneret assembly. At the same time, a two-stage feeding method is realized in the process method.

Description

Technical Field

[0001] The present invention relates to the field of the preparation of polyvinyl chloride, and particularly relates to an apparatus and a process for preparing polyvinyl chloride fibers by a melt spinning method. Background Art

[0002] Polyvinyl chloride fiber is a synthetic fiber made of polyvinyl chloride or its copolymer, and has the effects of high strength, nonflammability, and resistance to acid and alkali corrosion. In the prior art, polyvinyl chloride resin is usually made into fibers by wet spinning or dry spinning. However, in the processes of wet spinning and dry spinning, the polyvinyl chloride resin needs to be swollen in acetone. Acetone is a flammable and toxic substance, which will pollute the environment, and this production method has low efficiency. However, polyvinyl chloride (PVC) resin is a polymer that is insoluble in its monomer. Therefore, during its preliminary polymerization process, the polymerization product will precipitate and grow into primary particles, and the particles exist in the form of glassy microspheres to form fringed micelle crystals. During the process of being heated and extruded, it cannot be completely melted. During its processing, it flows in the form of a molecular beam containing about 10 million molecules. The primary particles interact through partial melting, entanglement, fusion, and recrystallization. Therefore, it is very difficult to directly process PVC resin by melt spinning.

[0003] In order to solve the problem that polyvinyl chloride (PVC) resin is prone to thermal oxidative degradation during the heating process, currently in the melt spinning process of polyvinyl chloride, the method adopted is to add heat stabilizers, plasticizers, lubricants, etc. during the granulation process: for example, domestic and foreign scholars have prepared PVC fibers for use in the wig industry by adding additives such as heat stabilizers and plasticizers to PVC resin and adopting a short-process melt spinning process; the team of Liu Shujia from Donghua University has studied the melt spinning of PVC hair fibers under different forming processes; Liu Mengzhu et al. from Dalian Polytechnic University have used the melt spinning method to start from additives such as PVC raw materials, plasticizers, and heat stabilizers, and studied the rheology and thermal stability of PVC systems with different additive contents, and prepared hair PVC fibers with better thermal stability; Application No. 2016109916703 discloses a method for producing hair polyvinyl chloride fibers, and the main materials used are low-polymerization-degree, higher-polymerization-degree, and high-polymerization-degree polyvinyl chloride; the Japanese Electric Chemical Industry Co., Ltd. Application No. 200480028726.0 discloses an invention patent of "PVC fiber for artificial hair, its manufacturing method and its manufacturing device", and the PVC fiber for artificial hair is obtained by spinning a polyvinyl chloride resin composition using a nozzle with a nozzle hole diameter D = 2 mm, a length-to-diameter ratio L / D = 1 to 3, a nozzle inlet part thickness of 4 mm or more, and an inlet angle of 20 to 90°; however, the PVC melt-spun fibers described in the above-mentioned documents can only be used in industries such as wigs or toy doll hairs, and cannot meet the requirement of the textile industry for the size stability of the woven fiber web. This is because the melting processing temperature of polyvinyl chloride resin is usually (160 - 190 °C), at this temperature, antioxidants and plasticizers are prone to decomposition, volatilization, and precipitation, and then the melt processing time must be shorter, otherwise it is easy to produce problems such as the melt turning yellow and black and aging degradation, and then the requirement for the size stability of the fiber web cannot be achieved.

[0004] Conventional melt spinning equipment basically includes a screw extruder, a melt filter, a metering pump, a melt distribution plate, a spinneret plate, a cooling and winding system, etc. The melt belongs to plug flow after flowing out of the distribution plate to the upper surface of the spinneret plate. There is a liquid accumulation area before the melt flows out of the distribution plate and enters the spinneret plate under pressure drive. The melt in the liquid accumulation area directly above or near the guide hole of the spinneret plate can directly enter the guide hole. However, for the melt in the liquid accumulation area at the middle of the connection line between the guide holes, it has to flow parallel along the nearly vertical direction of the guide hole of the spinneret plate to enter the guide hole, that is, there is a flow of about 90°, which makes it easy to form a vortex dead angle in the liquid accumulation area, and it is easy to cause a small amount of PVC resin to form stagnation. Moreover, due to the poor thermal stability of PVC, at the spinning temperature, the stagnant PVC resin gradually turns red, yellow, and then gradually blackens and carbonizes, resulting in the termination of the spinning process. In addition, due to the low crystallinity of polyvinyl chloride resin, its fiber and other products exhibit typical viscoelastic mechanical property characteristics. The PVC fibers processed by conventional chemical fiber equipment have a large elongation at break and will slowly shrink, especially during the warm water washing process, the shrinkage is more obvious, which 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 melt spinning. A melt spinning device with a smooth melt flow channel and no vortex dead angle is designed, which solves the problem of easy formation of vortex dead angles in the design of traditional melt spinning components. Moreover, a process method of adding additives in two stages is designed, which reduces the volatilization of additives and slows down the oxidative decomposition of PVC.

[0006] To achieve the above purpose, the present technical solution provides a device for preparing polyvinyl chloride fibers by melt spinning, including: a feeding component, a melt spinning component, a cooling component, a heating component, a heat setting component, and a winding component. Among them, polyvinyl chloride masterbatch and additives are added from the feeding component into the melt spinning component for melt spinning to form polyvinyl chloride monofilaments. The polyvinyl chloride monofilaments are successively 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 assembly connected in sequence. The spinneret assembly includes an outer housing, a conical melt flow channel distributor installed in the outer housing, and a spinneret plate assembled on the lower end surface of the melt fluid distributor. On the conical surface of the upper end surface of the melt flow channel distributor, a plurality of semi-sector holes are evenly distributed along the generatrix. The semi-sector knife edges are formed by the intersection between adjacent semi-sector holes. On the conical surface of the lower end surface of the melt flow channel distributor, a plurality of circular holes are evenly distributed along the generatrix. A plurality of spinneret holes are evenly distributed on the spinneret plate. Each circular hole is smoothly transitioned with the corresponding semi-sector 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 in one-to-one correspondence.

[0007] This solution provides a process for preparing polyvinyl chloride fibers by melt spinning, which is realized relying on the equipment for preparing polyvinyl chloride fibers by melt spinning, and includes the following steps: mixing polyvinyl chloride masterbatch, antioxidant, plasticizer, first heat stabilizer, internal lubricant and external lubricant, adding them into a screw extruder from a feeding assembly for melt spinning to obtain polyvinyl chloride melt; mixing the second heat stabilizer and crosslinking agent, pressurizing them to be in pressure balance with the polyvinyl chloride melt, adding them to the connecting flange position between the screw extruder and the spinning metering pump, extruding through the spinning metering pump and then entering into a spinneret assembly to extrude polyvinyl chloride monofilaments; the polyvinyl chloride monofilaments are successively cooled by a cooling assembly, heated by a heating assembly, heat-set by a heat setting assembly and wound by a winding assembly to obtain polyvinyl chloride fibers.

[0008] Compared with the prior art, this technical solution has the following characteristics and beneficial effects:

[0009] 1. By designing a unique spinneret assembly, through the conical design of the melt flow channel distributor, combined with the flow channel cavity formed by the smooth transition between semi-sector holes and circular holes, uniform diversion of the melt is achieved, and thus there are no right angles or mutations in the flow channel cavity within the spinneret assembly, avoiding the eddy currents and liquid accumulation areas caused by discontinuous flow channels in traditional spinnerets. The residence time of the melt in the flow channel is reduced, preventing the thermal decomposition of PVC due to high-temperature residence, improving the uniformity and strength of the fibers, and extending the cleaning or replacement cycle of the spinneret assembly.

[0010] 2. By means of secondary feeding, the volatilization or premature reaction of heat-sensitive additives in the high-temperature extrusion section is reduced, the utilization rate is increased by 20 - 30%, and through pressure-balanced injection, it is ensured that the additives are uniformly mixed with the melt, avoiding fiber defects caused by excessive local concentration. Description of the Drawings

[0011] Figure 1 is the overall structural schematic diagram of the equipment for preparing polyvinyl chloride fibers by the melt spinning method of this solution.

[0012] Figure 2 is the structural schematic diagram of the outer housing.

[0013] Figure 3 is the overall structural schematic diagram of the melt flow channel distributor.

[0014] Figure 4 is the top view of the upper end face of the melt flow channel distributor.

[0015] Figure 5 is the cross-sectional view of the lower end face of the melt flow channel distributor.

[0016] Figure 6 is the cross-sectional view of the spinneret plate.

[0017] Figure 7 is the top view of the spinneret plate.

[0018] In the figure: feeding component (10), melt spinning component (20), cooling component (30), heating component (40), heat setting component (50), winding component (60), screw extruder (21), spinning metering pump (22) and spinneret component (23), outer housing (231), melt flow channel distributor (232), spinneret plate (233), semi-sector holes (2321), circular holes (2322), spinneret holes (2331), flow channel cavity (2320), first feeding unit (11), second feeding unit (12), mixer (111), feeder (112), storage bin (113), first feed inlet (114), additive tank (121), booster pump (122), additive metering pump (123), second feed inlet (124). Specific embodiments

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0020] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationships indicated by the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0021] Embodiment 1

[0022] Figure 1 is the overall structural schematic diagram of the equipment for preparing polyvinyl chloride fibers by the melt spinning method provided by this solution. As Figure 1 shown, the equipment for preparing polyvinyl chloride fibers by the melt spinning method provided by this solution includes:

[0023] 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). PVC masterbatch and additives are added from the feeding component (10) into the melt spinning component (20) for melt spinning to form PVC monofilaments. The PVC monofilaments are successively 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 PVC fibers.

[0024] The melt spinning component (20) includes a screw extruder (21), a spinning metering pump (22), and a spinneret assembly (23) connected in sequence. The spinneret assembly (23) includes a housing (231), a conical melt flow channel distributor (232) disposed in the housing (231), and a spinneret plate (233) assembled on the lower end surface of the melt fluid distributor (232). A plurality of semi-sector holes (2321) are uniformly distributed along the generatrix on the conical surface of the upper end surface of the melt flow channel distributor (232). Semi-sector knife edges are formed at the intersections between adjacent semi-sector holes. A plurality of circular holes (2322) are uniformly distributed along the generatrix on the conical surface of the lower end surface of the melt flow channel distributor (232). A plurality of spinneret holes (2331) are uniformly distributed on the spinneret plate (233). Each circular hole (2322) is smoothly transitioned with the corresponding semi-sector hole (2321) to form a flow channel cavity (2320) uniformly 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 one-to-one correspondence.

[0025] This solution specifically designs a spinneret assembly for PVC melt spinning. When PVC and additives are melt-spun in the screw extruder (21) and then pumped into the spinneret assembly (23) in the form of a melt by the spinning metering pump (22), the cylindrical plug flow melt pumped out from the spinning metering pump (22) is split into an annular melt at the conical tip of the melt flow channel distributor (23). The annular melt flows into the flow channel cavity (2320) from the semi-sector holes (2321) of the melt flow channel distributor (232) and flows out from the first circular hole (2322) of the melt flow channel distributor (232), and then enters the corresponding spinneret hole (2331) and is ejected. The design of the spinneret assembly in this solution enables the flow channel cavity (2320) to have a smooth transition without vortex dead ends, that is, the melt will not have vertical flow in the spinneret assembly, and thus there will be no liquid accumulation area, eliminating the problems of vortex dead ends and melt retention, and extending the replacement cycle of the spinneret assembly.

[0026] Specifically, as Figure 2 shown is the structural schematic diagram of the housing (231) of this solution. As Figures 3 to 5 shown is the structural schematic diagram of the melt flow channel distributor (232) of this solution. Among themFigure 3 It is a schematic diagram of the overall structure of the melt channel distributor (232). Figure 4 It is a top view of the upper end face of the melt channel distributor (232). Figure 5 It is a cross-sectional view of the lower end face of the melt channel distributor (232). Figures 6 to 7 It is a schematic diagram of the structure of the spinneret plate (233) of this solution, where Figure 6 It is a cross-sectional view of the spinneret plate (233). Figure 7 It is a top view of the spinneret plate (233) of this solution.

[0027] The outer shell (231) of this solution is designed as a frustum of a cone with a smaller upper part and a larger lower part. Specifically, the outer shell (231) includes a first channel, a conical main body channel, and a second channel that are connected from top to bottom. The width of the first channel is smaller than that of the second channel, and the width of the conical main body channel gradually increases from top to bottom. The first channel is connected to the melt pipe of the spinning metering pump (22).

[0028] In some embodiments, the first channel and the second channel are designed as cylindrical. As described above, the laminar flow pushing melt flowing out of the melt pipe of the spinning metering pump (22) enters the spinning assembly (23) from the first channel.

[0029] The melt channel distributor (232) of this solution is a cone with a flow channel cavity (2320) formed on the outside. The cone angle α of the cone is 60-90°. The size of the cone angle determines the height of the melt channel distributor (232). When the cone angle α is greater than 90°, the cylindrical laminar flow pushing melt flowing out of the spinning metering pump (22) is not easily split into an annular shape; when the cone angle α is less than 60°, the melt channel distributor (232) is too high, and the machining difficulty of the flow channel cavity (2320) increases.

[0030] In a specific embodiment, the cone apex 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 channel distributor (232), which is also 60-90°. The horizontal position of the tip of the cone of the melt channel distributor (232) is located on the connection horizontal line between the first channel and the conical main body channel of the outer shell (231), and the main body of the cone of the melt 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 face of the spinneret plate (233) is flush with the lower end face of the second channel.

[0031] In some embodiments, 24 to 48 runner cavities (2320) are evenly distributed along the generatrix on the conical surface of the melt runner distributor (232). The number of runner cavities (2320) is related to the diameter of the lower end surface of the melt runner distributor (232) and the diameter of the spinneret plate (233). When the number of runner cavities (2320) is less than 24, the spacing between the spinneret holes (2331) on the spinneret plate (233) is relatively large, and the number of filaments formed by spinning is small; while when the number of runner cavities (2320) is greater than 48, the semi-sector holes on the upper end surface of the melt runner distributor (232) are too dense, resulting in great difficulty in machining.

[0032] As Figure 3 shown, the runner cavities (2320) formed on the conical surface of the melt runner distributor (232) are formed by penetrating the semi-sector holes (2321) on the upper end surface and the circular holes (2322) on the lower end surface of the melt runner distributor (232), and there is a smooth transition between the semi-sector holes (2321) and the corresponding circular holes (2322). In some embodiments, the width of the runner cavity (2320) gradually decreases from top to bottom.

[0033] Correspondingly, 24 to 48 semi-sector holes (2321) are evenly distributed along the generatrix on the conical surface of the upper end surface of the melt runner distributor (232). As Figure 4 shown, there are 24 semi-sector holes (2321) on the conical surface of the upper end surface of the melt runner distributor (232) as shown.

[0034] Specifically, each semi-sector hole (2321) is a frustum of a cone with an opening at the center. The side wall of each semi-sector hole (2321) is a sector arc surface. The melt dispersed into an annular shape enters the runner cavity (2320) from the opening position of the semi-sector hole (2321).

[0035] In some embodiments, the semi-sector holes (2321) evenly distributed on the upper end surface of the melt runner distributor (232) are adjacent to each other to form a ring, and the openings of the semi-sector holes (2321) are also located on the same ring. Adjacent semi-sector holes (2321) intersect with each other to form semi-sector knife edges, and the ring formed by the semi-sector holes (2321) is also an arc-shaped knife-edge protrusion. Thus, the melt split by the tip of the cone can be evenly divided into 24 to 48 portions, and thus no eddy current dead angles and melt retention will occur. Each portion of the melt enters the runner cavity (2320) and flows downward.

[0036] As Figure 5As shown, a plurality of circular holes (2322) are uniformly distributed along the generatrix on the conical surface of the lower end face of the melt channel distributor (232). The number and positions of the circular holes (2322) correspond to those of the semi-sector holes (2321) to form a flow channel cavity (2320). In some embodiments, the diameter of the circular holes (2322) is 3 - 4 mm. It is emphasized again that the channel of the flow channel cavity (2320) formed by the connection between the circular holes (2322) and the semi-sector holes (2321) in this solution has a smooth wall surface to facilitate the flow of the melt.

[0037] As Figure 6 and Figure 7 shown, a mirror seal is provided between the spinneret plate (233) and the melt channel distributor (232) to prevent the melt from leaking under pressure. The number and positions of the spinneret holes (2331) on the spinneret plate (233) correspond one-to-one with those of the circular holes (2322) to ensure that the melt flowing out of each flow channel cavity (2320) can enter the spinneret holes (2331), ensuring that there is no liquid accumulation area, eliminating dead corners and melt retention.

[0038] As Figure 6 shown, each spinneret hole (2331) is a frustum of a cone with a larger upper part and a smaller lower part. The upper surface of the spinneret hole (2331) is a circular inlet with a diameter dimension the same as that of the circular hole (2322), and the lower surface is a circular outlet with a diameter dimension smaller than that of the circular hole (2322), and there is a smooth transition between the circular inlet and the circular outlet.

[0039] In some embodiments, the diameter of the circular inlet of the spinneret hole (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°.

[0040] A plurality of spinneret holes (2331) are uniformly distributed on the spinneret plate (233). Each circular hole (2322) and the corresponding semi-sector hole (2321) are smoothly transitioned to form a flow channel cavity (2320) that is uniformly distributed along the generatrix of the conical surface of the melt channel distributor (232).

[0041] In addition, the feeding assembly (10) of the equipment for preparing polyvinyl chloride fibers by the melt spinning method of the present solution includes a first feeding unit (11) and a second feeding unit (12). The first feeding unit (11) includes a mixer (111), a feeder (112), a silo (113), and a first feed port (114) connected in sequence. The first feed port (114) communicates with the screw extruder (21). The second feeding unit (12) includes an additive tank (121), a booster pump (122), an additive metering pump (123), and a second feed port (124) connected in sequence. The second feed port (124) communicates with the connection flange between the screw extruder (21) and the spinning metering pump (22). The feeding assembly (10) of the present solution adopts a two-stage feeding method during the melt spinning process of polyvinyl chloride, so as to reduce the volatilization of additives and slow down the oxidative decomposition of PVC.

[0042] 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. After the polyvinyl chloride masterbatch, antioxidant, plasticizer, first heat stabilizer, internal lubricant, and external lubricant are mixed in the mixer (111), they are fed into the first feed port (114) through the feeder (112), and melt spinning is carried out through the screw extruder (21).

[0043] In some embodiments, the second feeding unit (12) is used to add a second heat stabilizer and a crosslinking agent. The second heat stabilizer and the crosslinking 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 balance with the polyvinyl chloride melt, they then enter the screw extruder (21) and are mixed with the polyvinyl chloride melt and then extruded.

[0044] Specifically, the second feeding unit (12) is arranged at the connection flange between the screw extruder (21) and the spinning metering pump (22). After the reaction raw materials added in the first feeding unit (11) are gradually melted and advanced through the feeding section and the compression section of the screw extruder (21), they are further plasticized in the metering section and then extruded into the connection flange at a certain pressure to obtain a polyvinyl chloride melt. The liquid additives in the second feeding unit (12) are pressurized to the same pressure as the polyvinyl chloride melt and then extruded into the polyvinyl chloride melt. After being mixed evenly by the melt static mixer arranged at the outlet of the connection flange, they flow into the spinning metering pump and then into the spinneret assembly (23).

[0045] In some embodiments, the degree of polymerization of the polyvinyl chloride masterbatch in the first feeding unit (11) is 900 - 1200. Calculated based on 100 parts by weight, the weight parts of the antioxidant are 0.5 - 1, the weight parts of the plasticizer are 30 - 40, the weight parts of the internal lubricant are 1 - 3 parts, the weight parts of the external lubricant are 1 - 2 parts, and the weight parts of the first heat stabilizer are 0.1 - 0.5 parts.

[0046] In some embodiments, the antioxidant is selected as 1010, the plasticizer is selected from one or any combination of dioctyl phthalate (DOP) and dibutyl phthalate (DBP), the internal lubricant is selected from one or any combination of paraffin wax, polyvinyl chloride wax, and oxidized polyvinyl chloride wax; the external lubricant is selected from one or any combination of glycerol monostearate, calcium stearate, lead stearate, barium stearate, and zinc stearate.

[0047] In some embodiments, the first stabilizer is selected as dibutyltin maleate laurate, and the weight part of dibutyltin maleate laurate is 0.2 - 0.5; or it is selected as dibutyltin dilaurate, and the weight part of dibutyltin dilaurate is 0.2 - 0.5; or it is selected as triphenyl phosphite, and the weight part of triphenyl phosphite is 0.1 - 0.3.

[0048] In some embodiments, based on 100 weight parts of the polyvinyl chloride masterbatch, the weight part of the second heat stabilizer in the second feeding unit (12) is 0.1 - 0.3, and the weight part of the crosslinking agent is 0.2 - 0.4.

[0049] In some embodiments, the crosslinking agent is selected from one or any combination of dicumyl peroxide and di - tert - butyl peroxide dicumyl (DCP); the second heat stabilizer is selected as epoxidized soybean oil, and the weight part of epoxidized soybean oil is 0.1 - 0.2, the second heat stabilizer is selected as ethyl isooctyl methyltin, and the weight part of ethyl isooctyl methyltin is 0.1 - 0.2, the second heat stabilizer is selected as organotin such as mercaptobutyltin, and the weight part of mercaptobutyltin and other organotin is 0.1 - 0.3.

[0050] In some embodiments, the crosslinking agent selected in this solution is an ultraviolet crosslinking agent. Correspondingly, after the winding component (60) winds up, the polyvinyl chloride fiber is irradiated with ultraviolet light for 30 - 60 to obtain the crosslinked polyvinyl chloride fiber, so that a small amount of crosslinking reaction occurs between the ultraviolet crosslinking agent and the PVC linear macromolecules, the elongation at break of the PVC wire remains stable in the relaxed state, slow shrinkage no longer occurs, and at the same time, the lasting effect of the heat stabilizer is improved, preventing the thermal oxidative degradation of PVC in the spinning box.

[0051] Example Two

[0052] This solution provides a process method for preparing polyvinyl chloride fiber by melt spinning, which is realized relying on the equipment for preparing polyvinyl chloride fiber by melt spinning shown in Example One, and includes the following steps:

[0053] Mix the polyvinyl chloride masterbatch, antioxidant, plasticizer, first heat stabilizer, internal lubricant, and external lubricant, and then add them into the screw extruder (21) from the feeding component (10) for melt spinning to obtain the polyvinyl chloride melt;

[0054] Mix the second heat stabilizer and the crosslinking agent, and after pressurizing to the pressure balance with the polyvinyl chloride melt, add them to the connecting flange position of the screw extruder (21) and the spinning metering pump (22). After being extruded by the spinning metering pump (22), it enters the spinneret assembly (23) to extrude polyvinyl chloride monofilaments.

[0055] The polyvinyl chloride monofilaments are successively cooled by the cooling assembly (30), heated by the heating assembly (40), heat-set by the heat-setting assembly (50), and wound by the winding assembly (60) to obtain polyvinyl chloride fibers.

[0056] In some embodiments, the degree of polymerization of the polyvinyl chloride masterbatch is 900 - 1200. Based on 100 parts by weight, the parts by weight of the antioxidant is 0.5 - 1, the parts by weight of the plasticizer is 30 - 40, the parts by weight of the internal lubricant is 1 - 3 parts, the parts by weight of the external lubricant is 1 - 2 parts, and the parts by weight of the first heat stabilizer is 0.1 - 0.5 parts.

[0057] 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 glycerol monostearate, calcium stearate, lead stearate, barium stearate, and zinc stearate.

[0058] In some embodiments, the first heat stabilizer is selected as one or any combination of dibutyltin dilauryl maleate, dibutyltin dilaurate, and triphenyl phosphite. The first stabilizer is selected as dibutyltin dilauryl maleate, and the parts by weight of dibutyltin dilauryl maleate is 0.2 - 0.5; or selected as dibutyltin dilaurate, and the parts by weight of dibutyltin dilaurate is 0.2 - 0.5; or selected as triphenyl phosphite, and the parts by weight of triphenyl phosphite is 0.1 - 0.3.

[0059] In some embodiments, based on 100 parts by weight of the polyvinyl chloride masterbatch, the parts by weight of the second heat stabilizer is 0.1 - 0.3, and the parts by weight of the crosslinking agent is 0.2 - 0.4.

[0060] In some embodiments, the crosslinking agent is selected from one or any combination of dicumyl peroxide and bis(tert-butylperoxy)dicumyl (DCP); the second heat stabilizer is selected from one or any combination of epoxidized soybean oil, methyltin isooctyl ethyl ester, and mercaptobutyltin. When the second heat stabilizer is epoxidized soybean oil, the weight part of epoxidized soybean oil is 0.1 - 0.2. When the second heat stabilizer is methyltin isooctyl ethyl ester, the weight part of methyltin isooctyl ethyl ester is 0.1 - 0.2. When the second heat stabilizer is an organotin such as mercaptobutyltin, the weight part of the organotin such as mercaptobutyltin is 0.1 - 0.3.

[0061] In some embodiments, the crosslinking agent selected in this solution is an ultraviolet crosslinking agent. Correspondingly, after the winding component (60) winds up, the polyvinyl chloride fiber is irradiated with ultraviolet light for 30 - 60 to obtain the crosslinked polyvinyl chloride fiber, so that a small amount of crosslinking reaction occurs between the ultraviolet crosslinking agent and the PVC linear macromolecules, the elongation at break of the PVC wire is kept stable in the relaxed state, and slow shrinkage no longer occurs. At the same time, the lasting effect of the heat stabilizer is improved, and PVC thermal oxidative degradation in the spinning box is prevented.

[0062] Design of the specific spinneret assembly in Embodiment III

[0063] On the conical surface of the melt flow channel distributor of the spinneret assembly provided in this embodiment, 24 flow channel cavities are evenly distributed along the generatrix. The top conical angle α of the melt flow channel distributor is 60°. 24 semi-sector-shaped holes are evenly distributed on the circular upper end surface thereof. The intersections between the holes form sharp knife-edge-shaped protrusions. The outer circle of the ring is also an arc-shaped sharp knife-edge-shaped protrusion, so that the melt flowing from the spinning metering pump is evenly divided into 24 equal parts. 24 circular holes with a diameter of 4 mm are evenly distributed on the circular ring of the lower end surface of the melt flow channel distributor. The connecting channels between the semi-sector-shaped holes on the upper end surface circular ring and the circular holes on the lower end surface are smoothly transitioned, and the channel walls are smooth. A spinneret plate is assembled below the melt flow channel distributor, and the two are hermetically sealed with a mirror surface. 24 spinneret holes are evenly distributed on the spinneret plate. The diameter and distribution of the circular inlets of the spinneret holes correspond one by one to the circular holes on the circular ring of the lower end surface of the melt flow channel distributor, and the sizes are the same, and the positions are fixed by positioning pins, so that the melt in each flow channel cavity flows into the spinneret holes one by one. The taper θ1 of the circular inlet of the spinneret hole is 11°. The diameter of the circular outlet hole of the spinneret plate is 0.35 mm, and the inner cavity conical vertex angle of the outer shell is also α. The melt flow channel distributor and the spinneret plate are jointly installed in the outer shell and closely fit. The upper end of the outer shell is connected to the melt pipeline of the spinning metering pump. The cylindrical melt flowing from the melt pipeline is gradually split into a circular ring at the tip of the melt flow channel distributor, and is evenly divided into 24 equal parts when flowing through the inlets of the semi-sector-shaped holes on the upper end surface circular ring. Each strand of melt flows into the spinneret hole through the flow channel cavity respectively, and is then ejected from the circular outlet of the spinneret plate after being compressed.

[0064] Example 4: Design of a Specific Spinneret Assembly

[0065] In the spinneret assembly provided in this example, 30 flow channels are evenly distributed along the generatrix on the conical surface of the melt flow channel distributor. The apex cone angle of the melt flow channel distributor is 70°. 30 semi-sector holes are evenly distributed on its circular upper end face. The intersections between the holes form sharp knife-edge-like protrusions. The outer circle of the ring is also an arc-shaped sharp knife-edge-like protrusion, so that the melt flowing from the melt pipe is evenly divided into 30 equal parts. 30 circular holes with a diameter of 4 mm are evenly distributed on the circular lower end face of the melt flow channel distributor. The connecting channels between the semi-sector holes on the upper end face ring and the circular holes on the lower end face have a smooth transition, and the channel walls are smooth. A spinneret plate is assembled below the melt flow channel distributor, and the two are mirror-sealed. 30 spinneret holes are evenly distributed on the spinneret plate. The diameter and distribution of the circular inlets of the spinneret holes correspond one by one to the circular holes on the circular lower end face of the melt flow channel distributor, with the same size, and their positions are fixed by positioning pins, so that the melt in each flow channel flows into the inlet holes of the spinneret plate one by one. The taper θ1 of the circular inlet of the spinneret plate is 15°. The diameter of the circular outlet of the spinneret plate is 0.35 mm. The inner cavity cone apex angle of the outer housing is also 70°. The melt flow channel distributor and the spinneret plate are jointly installed in the outer housing and fit tightly. The upper end of the outer housing is connected to the melt pipe. The cylindrical melt flowing from the melt pipe is gradually split into an annular shape at the apex of the cone of the melt flow channel distributor. When flowing through the inlets of the semi-sector holes on the upper end face ring, it is evenly divided into 30 equal parts. Each strand of melt flows into the spinneret holes through the flow channels respectively, and then is ejected from the circular outlet of the spinneret plate after being compressed.

[0066] Example 5

[0067] Except that 36 flow channels are evenly distributed along the generatrix on the conical surface of the melt flow channel distributor, the apex cone angle of the melt flow channel distributor is 80°, 36 semi-sector holes are evenly distributed on its circular upper end face, 36 circular holes with a diameter of 4 mm are evenly distributed on the circular lower end face, 36 spinneret holes are evenly distributed on the spinneret plate, and the inner cavity cone apex angle of the outer housing is 80°, other parameters are the same as those in Example 4.

[0068] Those skilled in the art should understand that the technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should all be considered as the scope described in this specification.

[0069] The above embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended 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; wherein the feeding component comprises a first feeding unit and a second feeding unit, wherein the first feeding unit comprises 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 comprises 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 to add 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 to add a second heat stabilizer and a cross-linking agent; 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 60-90°.

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. 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 7, 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.

9. The process for preparing polyvinyl chloride fiber by melt spinning according to claim 8, 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.

Images