Apparatus and process for the production of coloured monofilaments of polyvinyl chloride by colouring with organic pigments

Abstract

The application discloses a device and a process for preparing colored monofilament of polyvinyl chloride by organic pigment coloring. The screw extruder of the device comprises a sleeve, a screw, a pigment coloring unit, a static mixing unit and a melt flow channel outlet arranged in sequence along the axial direction in the melt flow channel of the sleeve. The pigment coloring unit is formed by a pigment solid inner core body and a pigment solid outer cylindrical body which are clamped and pressed by two porous plates, and an annular melt passage is formed between the two. The inner core body and the outer cylindrical body are both pressed into shape by organic pigment particles with a coating structure layer, and the coating layer can be melted or volatilized. When the melt flows through the annular passage, the surface layer of the pigment particles is mixed into the melt, and then the static mixing unit is used for fully mixing the melt. The coating layer is melted or volatilized after contacting the melt, and the release of the pigment core material is delayed. The pigment coloring unit is arranged at the rear end, and the pigment does not need to follow the resin for screw mixing, so that the thermal damage of the pigment molecular structure caused by high temperature is reduced, the brightness and gloss of the pigment are retained, and the appearance and texture requirements of high-end wig products are met.

Description

Technical Field

[0001] This invention relates to the field of colored monofilament preparation technology, and in particular to an equipment and process for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments. Background Technology

[0002] Polyvinyl chloride (PVC) resin possesses excellent flame-retardant properties and good drape characteristics, and the finished fiber texture closely resembles that of natural human hair. Therefore, colored PVC filaments are widely used in the production of high-end wigs. Due to the inherent structural characteristics of the PVC macromolecule, PVC fibers have poor dyeability. Except for a few special dyes such as disperse dyes and metallic mordant dyes, most conventional dyes cannot effectively dye PVC fibers. Based on these characteristics, the industry currently commonly uses a method of blending pigments with PVC resin to produce colored PVC monofilaments.

[0003] Currently, pigments used for coloring in hair spinning are mainly divided into two categories: inorganic pigments and organic pigments. Most inorganic pigments contain heavy metals such as chromium and lead, posing a certain toxicity risk. They also generally suffer from insufficient color vibrancy and a darker tone, making it difficult to meet the requirements of high-end wig products for bright and textured colors. Compared to inorganic pigments, organic pigments can be used to create a wider variety of products by adjusting their molecular structure. They offer advantages such as more vibrant colors and brighter tones, while also possessing excellent lightfastness and weatherfastness, making them a more promising coloring material.

[0004] In existing blending spinning equipment, organic pigments are typically added to the extruder's sleeve along with PVC resin from the extruder's feed hopper. Driven and sheared by the screw, they undergo the entire blending process with the molten resin. The melt spinning temperature of PVC resin is usually 160℃~190℃. The organic pigments, from entering through the feed inlet to being ejected from the spinneret and cooled, spend 10~15 minutes in the high-temperature sleeve. During this process, the organic pigments are continuously exposed to a high-temperature environment and subjected to the strong shearing and blending action of the screw, leading to irreversible degradation of their color gloss and vibrancy. The resulting PVC hair wigs generally have a darker color and insufficient gloss, failing to replicate the shine and bright color of natural hair, greatly limiting the application of organic pigments in the high-end PVC hair wig market. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing an apparatus and process for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments.

[0006] The objective of this invention is achieved through the following technical solution: an apparatus for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments, comprising a screw extruder, wherein the screw extruder comprises a sleeve, a melt flow channel is provided inside the sleeve, and a screw, a pigment coloring unit, a static mixing unit and a melt flow channel outlet are sequentially arranged along its axial direction inside the melt flow channel; The pigment coloring unit includes a pigment solid inner core, a pigment solid outer ring column, and two perforated plates coaxially fixed to the inner wall of the sleeve. The pigment solid inner core and the pigment solid outer ring column are sandwiched between the two perforated plates. The pigment solid inner core is located at the center of the pigment solid outer ring column, and an annular channel for the melt to pass through is formed between the two. Both the pigment solid inner core and the pigment solid outer ring cylinder are made of pressed organic pigment particles. The organic pigment particles include a pigment core material and a coating structure layer that is molten or volatile and wrapped around the pigment core material. When the melt passes through the annular channel, the organic pigment particles located on the surface of the annular channel are mixed into the melt. When the melt containing organic pigment particles passes through the static mixing unit, the organic pigment particles and the melt are fully mixed. When the coating structure layer comes into contact with the melt, it melts or volatilizes and delays the release of the internal pigment core material to reduce the contact time between the pigment core material and the melt.

[0007] Preferably, the static mixing unit includes at least three mixers arranged sequentially along the axial direction of the melt flow channel, and the mixers have a tetrahedral structure.

[0008] Preferably, the length of the edge of the mixer is the same as the inner diameter of the sleeve. Two non-adjacent and perpendicular edges on the mixer are fixed edges. The fixed edges are arranged in the melt flow channel along the diameter direction of the sleeve, and the two ends of the fixed edges are fixedly connected to the inner wall of the sleeve. The fixed edge on the side of the mixer closer to the pigment coloring unit is the first fixed edge, and the fixed edge on the other side is the second fixed edge. In two adjacent mixers, the second fixed edge of the first mixer is perpendicular to the first fixed edge of the second mixer.

[0009] Preferably, the material of the coating layer is chitosan.

[0010] Preferably, chitosan is coated onto the surface of the pigment core material by spray drying, thereby obtaining organic pigment particles with a coating structure layer.

[0011] Preferably, the radius r of the pigment solid inner core and the inner radius of the pigment solid outer ring cylinder satisfy the following relationship: D / 2 R=r; In the formula, D is the inner diameter of the sleeve; through the above relationship, the total contact area between the pigment coloring unit and the melt remains stable as the organic pigment particles are consumed.

[0012] Preferably, a heater is provided on the outer side of the sleeve.

[0013] A process for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments includes the following steps: S1: Organic pigment particles with a coating structure layer are prepared by spray drying using organic pigments as the core material and chitosan as the coating structure layer. S2: Organic pigment particles are filled into a mold and compacted to form a pigment solid inner core and a pigment solid outer ring cylinder. Pigment coloring units are made by using the pigment solid inner core, pigment solid outer ring cylinder and perforated plate. Pigment coloring units are placed in the corresponding installation positions in the screw extruder. S3: The monofilament raw material is fed into the screw extruder, melted and plasticized at 160-190℃ and conveyed forward to form a flowing melt; S4: After the melt leaves the screw, it flows through the annular channel of the pigment coloring unit. The organic pigment particles on the surface of the annular channel are mixed into the melt, resulting in a melt mixed with organic pigment particles. S5: The melt containing organic pigment particles passes through multiple mixers in the static mixing unit in sequence. After being divided and cross-fused radially and axially by the mixers, a uniform colored melt is formed. S6: The colored melt is sprayed out through the spinneret and then cooled and solidified to obtain colored polyvinyl chloride monofilament.

[0014] Preferably, the monofilament raw material is polyvinyl chloride resin.

[0015] Preferably, the total time from the moment the melt first comes into contact with the organic pigment particles to the moment it is ejected from the spinneret does not exceed 3 minutes.

[0016] The beneficial effects of this invention are: 1. This invention places the pigment coloring unit in the melt flow channel at the screw outlet, eliminating the need for organic pigment particles to undergo the entire screw mixing process with the resin. This reduces the contact time between the organic pigment and the high-temperature melt from 10-15 minutes in traditional processes to less than 3 minutes, fundamentally reducing the thermal damage to the organic pigment molecular structure caused by the high-temperature environment. Combined with the coating structure layer of the organic pigment particles, this layer preferentially melts and evaporates upon contact with the melt, forming a buffer protective layer. This further delays the direct contact time between the pigment core material and the high-temperature melt, maximizing the preservation of the original high vibrancy, bright hue, and gloss of the organic pigment. The resulting monofilament product has a bright color and a natural hair-like shine, thus meeting the appearance and texture requirements of high-end wig products.

[0017] 2. The pigment coloring unit adopts a combination structure of "pigment solid inner core + pigment solid outer ring column". An annular channel is formed between the pigment solid inner core and the pigment solid outer ring column, allowing the melt to pass through. When the melt passes through the annular channel, the organic pigment particles are uniformly mixed into the melt. Under the mixing action of the static mixing unit, the organic pigment particles are uniformly mixed with the melt, so that the organic pigment particles are uniformly dispersed in the melt, resulting in a colored melt with highly uniform color, ensuring the consistency of the color of the final monofilament product. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] Figure 2 This is a sectional view of the sleeve.

[0020] Figure 3 This is a schematic diagram of the structure of a pigment coloring unit.

[0021] Figure 4 A horizontal cross-sectional view of a pigment coloring unit.

[0022] Figure 5 This is a schematic diagram of a perforated plate.

[0023] Figure 6 This is a schematic diagram of the mixer.

[0024] In the diagram: 1. Frame, 2. Sleeve support, 3. Melt flow channel outlet, 4. Heater, 5. Sleeve, 6. Bucket, 7. Reducer, 8. Drive motor, 9. Pigment solid outer ring cylinder, 10. Pigment solid inner core, 11. Perforated plate, 12. Mixer, 13. Screw, 14. Annular channel, D is the outer diameter of the pigment solid outer ring cylinder or the inner diameter of the sleeve, r is the radius of the pigment solid inner core, and R is the inner radius of the pigment solid outer ring cylinder. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0027] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0028] like Figures 1 to 6 As shown, an apparatus for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments includes a screw extruder 13. The screw extruder 13 includes a sleeve 5, and a melt flow channel is provided inside the sleeve 5. The screw 13, a pigment coloring unit, a static mixing unit, and a melt flow channel outlet 3 are arranged sequentially along the axial direction of the melt flow channel. The pigment coloring unit includes a pigment solid inner core 10, a pigment solid outer ring column 9, and two perforated plates 11 coaxially fixed to the inner wall of the sleeve 5. The pigment solid inner core 10 and the pigment solid outer ring column 9 are clamped between the two perforated plates 11. The pigment solid inner core 10 is located at the center of the pigment solid outer ring column 9, and an annular channel 14 is formed between the two for the melt to pass through. Both the pigment solid inner core 10 and the pigment solid outer ring column 9 are made of pressed organic pigment particles. The organic pigment particles include a pigment core material and a coating structure layer that is molten or volatile and wrapped around the pigment core material. When the melt passes through the annular channel 14, the organic pigment particles located on the surface of the annular channel 14 are mixed into the melt. When the melt mixed with organic pigment particles passes through the static mixing unit, the organic pigment particles and the melt are fully mixed. When the coating structure layer comes into contact with the melt, it melts or volatilizes and delays the release of the internal pigment core material to reduce the contact time between the pigment core material and the melt.

[0029] This invention places the pigment coloring unit downstream of the screw 13 outlet into the melt flow channel. The organic pigment particles no longer undergo the entire mixing process with the resin via the screw 13, reducing the contact time between the organic pigment and the high-temperature melt from 10-15 minutes in traditional processes to less than 3 minutes. This fundamentally reduces the thermal damage to the organic pigment molecular structure caused by the high-temperature environment. Combined with the coating layer of the organic pigment particles, this coating layer preferentially melts and evaporates upon contact with the melt, forming a buffer protective layer. This further delays the direct contact time between the pigment core material and the high-temperature melt, maximizing the preservation of the original high vibrancy, bright hue, and gloss of the organic pigment. The resulting monofilament product has a bright color and a natural hair-like shine, thus meeting the appearance and texture requirements of high-end wig products.

[0030] The pigment coloring unit adopts a combination structure of "pigment solid inner core 10 + pigment solid outer ring column 9". An annular channel 14 is formed between the pigment solid inner core 10 and the pigment solid outer ring column 9, allowing the melt to pass through. When the melt passes through the annular channel 14, the organic pigment particles are uniformly mixed into the melt. Under the mixing action of the static mixing unit, the organic pigment particles are uniformly mixed with the melt, so that the organic pigment particles are uniformly dispersed in the melt, resulting in a colored melt with highly uniform color, which ensures the consistency of the color of the final monofilament product.

[0031] The static mixing unit includes at least three mixers 12, which are arranged sequentially along the axial direction of the melt flow channel. Each mixer 12 has a tetrahedral structure.

[0032] The structure of mixer 12 is as follows Figure 6 As shown. The length of the edge of the mixer 12 is the same as the inner diameter of the sleeve 5. Two non-adjacent and perpendicular edges on the mixer 12 are used as fixed edges. The fixed edges are arranged in the melt flow channel along the diameter direction of the sleeve 5. The two ends of the fixed edges are fixedly connected to the inner wall of the sleeve 5. The fixed edge on the side of the mixer 12 closest to the pigment coloring unit is the first fixed edge, and the fixed edge on the other side is the second fixed edge. In two adjacent mixers 12, the second fixed edge of the first mixer 12 is perpendicular to the first fixed edge of the second mixer 12.

[0033] Figure 6 In the above, the mixer with a tetrahedral structure includes six edges of equal length, namely AB, CD, AC, BC, AD, and BD, and the length of these six edges is the same as the inner diameter D of the sleeve, that is: AB=CD=AC=BC=AD=BD=D.

[0034] The tetrahedron is a fully three-dimensional spatial structure. When the melt flows through it, it can simultaneously generate multi-directional flow and mixing in the radial (center-wall), axial (front and rear layers), and circumferential (rotational intersection) directions. A single pass can complete multi-dimensional fluid reorganization, effectively breaking the laminar flow state of the melt and accelerating the diffusion of pigments adhering to the surface into the melt interior. Among them, the edge length of the mixer 12 is consistent with the inner diameter of the sleeve 5, so that the mixer 12 completely fills the entire radial section of the flow channel, eliminating the short-circuit flow channel of the melt at the wall of the sleeve 5, ensuring that all melt passes through edge cutting and spatial deflection, without mixing dead corners, and avoiding color difference and color spot defects at the edge of the filaments caused by insufficient mixing of melt on the wall.

[0035] The mixer 12 uses two mutually perpendicular, non-adjacent edges as its fixing structure, fixed to the inner wall at both ends along the diameter of the sleeve 5, forming a bidirectional symmetrical support structure. This ensures uniform stress distribution in the high-temperature, high-pressure melt environment, strong structural resistance to deformation, convenient installation and positioning, and high coaxiality, allowing for long-term stable resistance to continuous melt erosion. This symmetrical fixing structure makes the mixer 12 symmetrical about the flow channel axis, ensuring uniform resistance distribution in all directions as the melt flows through, preventing flow deviation and excessive local velocity differences. This guarantees that the mixing path, residence time, and shearing degree of each melt segment are basically consistent, ensuring uniform coloring of the single filament cross-section, and no significant color differences between sections of the same batch of filaments or between batches.

[0036] The first and second fixed edges of adjacent mixers 12 are perpendicular to each other, meaning that the cutting direction of the melt rotates by 90° after each stage of mixer 12. The laminar flow stream formed by the segmentation of the previous stage mixer 12 is orthogonally cut, flipped, and recombined again by the perpendicular edges after entering the next stage. This is equivalent to a "cross-shaped" step-by-step subdivision of the melt, with each stage further dispersing and fusing the result of the previous stage. This application, with at least 3 mixers 12, can achieve 4³~4 4 The number of split mixing cycles is reduced to a minimum, allowing for uniform dispersion of pigments from the melt surface to the whole within a very short axial flow channel length, eliminating the need for long mixing sections. The significantly shortened mixing section length strictly controls the total contact time between the organic pigments and the high-temperature melt (within 3 minutes), further preventing color degradation of the organic pigments due to prolonged high-temperature heating.

[0037] The material of the coating layer should not chemically react with the pigment core material and should provide a certain degree of protection for the pigment core material. In this application, the material of the coating layer is chitosan.

[0038] Organic pigment particles with a coated structure layer are prepared by coating chitosan onto the surface of a pigment core material using a spray drying method. The specific operation method is as follows: The pigment core material made of organic pigments is stably emulsified and dispersed in chitosan material. After homogenization, an emulsion dispersion is formed and then added to a spray drying device. By adjusting the temperature, pressure, atomization frequency, atomizer orifice size, nozzle flow rate and velocity, the falling speed and size of the droplets formed by the fusion of pigment core material and chitosan material are controlled, so that the solvent in the atomized emulsion evaporates in the dry hot airflow, and finally organic pigment particles with a coating structure layer are formed.

[0039] like Figure 3 and Figure 4 As shown, the radius of the pigment solid inner core is r, the inner radius of the pigment solid outer ring cylinder is R, and the outer diameter of the pigment solid outer ring cylinder is consistent with the inner diameter of the sleeve, both being D; the lengths of the pigment solid inner core and the pigment solid outer ring cylinder are L. Assuming that each time the melt flows through, organic pigment particles of thickness u (the total thickness of the two contact surfaces is 2u) are carried away from the outer surface of the pigment solid inner core and the inner surface of the pigment solid outer ring cylinder respectively, then the radius r of the pigment solid inner core and the inner diameter of the pigment solid outer ring cylinder satisfy the following relationship: D / 2 R=r; Through the above relationship, the total contact area between the pigment coloring unit and the melt remains stable as the organic pigment particles are consumed; and the inner and outer pigment solids are depleted simultaneously before being refilled.

[0040] Under the above conditions, the total contact area between the melt and the organic pigment is... for: .

[0041] As can be seen from the above formula, the surface area of ​​the pigment solid in contact with the melt remains unchanged. Therefore, the amount of melt extruded by the screw 13 per unit time can remain unchanged. When passing through the annular channel 14, the melt flow rate will slow down slightly due to the increased channel size. However, the total amount of organic pigment particles carried away by the melt per unit volume remains stable, ensuring the stability of the dyeing rate and avoiding the problems of color difference between the front and back sections of the same batch of filaments and color fluctuation between batches.

[0042] The organic pigment particles adopt a one-piece structure formed by compression molding and are clamped and fixed by two perforated plates 11. The installation and replacement methods are simple, and the pigment can be quickly refilled after it is exhausted, making production and maintenance convenient.

[0043] like Figure 5 As shown, the perforated plate 11 has several through holes that allow the melt to pass through.

[0044] A heater 4 is provided on the outer side of the sleeve 5. The heater 4 can provide a stable target temperature for the melt flow channel inside the sleeve 5 and maintain the temperature between 160-190°C.

[0045] The sleeve 5 is mounted on the feeding hopper and is used to add raw materials into the screw 13 extruder.

[0046] The screw 13 extruder also includes a frame 1, a reducer 7, and a drive motor 8. The output shaft of the drive motor 8 is connected to the input shaft of the reducer 7, and the output shaft of the reducer 7 is connected to the screw 13 to drive the screw 13 to rotate. The sleeve 5, the reducer 7, and the drive motor 8 are all mounted on the frame 1. The sleeve 5 is connected to the frame 1 through a sleeve bracket 2.

[0047] This invention also provides a process for preparing colored polyvinyl chloride monofilaments using organic pigments, comprising the following steps: S1: Organic pigment particles with a coating structure layer are prepared by spray drying using organic pigments as the core material and chitosan as the coating structure layer.

[0048] S2: Organic pigment particles are filled into a mold and compacted to form a pigment solid inner core 10 and a pigment solid outer ring column 9. Pigment coloring units are made by using the pigment solid inner core 10, pigment solid outer ring column 9 and perforated plate 11. The pigment coloring units are placed in the corresponding installation positions in the screw 13 extruder.

[0049] S3: The monofilament raw material is fed into the screw 13 extruder, melted and plasticized at 160-190℃ and conveyed forward to form a flowing melt; wherein, the monofilament raw material is polyvinyl chloride resin.

[0050] S4: After the melt leaves the screw 13, it flows through the annular flow channel of the pigment coloring unit. The organic pigment particles located on the surface of the annular channel 14 are mixed into the melt, resulting in a melt mixed with organic pigment particles.

[0051] S5: The melt containing organic pigment particles passes through multiple mixers 12 in the static mixing unit in sequence. After being divided by the mixers 12 and cross-fused radially and axially, a uniform colored melt is formed.

[0052] S6: The colored melt is sprayed out through the spinneret and then cooled and solidified to obtain colored polyvinyl chloride monofilament.

[0053] In this invention, the total time from the moment the melt first contacts the organic pigment particles to the moment it is ejected from the spinneret does not exceed 3 minutes.

[0054] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. An apparatus for preparing colored polyvinyl chloride monofilaments using organic pigments, characterized in that, The invention includes a screw extruder, which includes a sleeve, a melt flow channel is provided inside the sleeve, and a screw, a pigment coloring unit, a static mixing unit and a melt flow channel outlet are arranged sequentially along the axial direction of the melt flow channel. The pigment coloring unit includes a pigment solid inner core, a pigment solid outer ring column, and two perforated plates coaxially fixed to the inner wall of the sleeve. The pigment solid inner core and the pigment solid outer ring column are sandwiched between the two perforated plates. The pigment solid inner core is located at the center of the pigment solid outer ring column, and an annular channel for the melt to pass through is formed between the two. Both the pigment solid inner core and the pigment solid outer ring cylinder are made of pressed organic pigment particles. The organic pigment particles include a pigment core material and a coating structure layer that is molten or volatile and wrapped around the pigment core material. When the melt passes through the annular channel, the organic pigment particles located on the surface of the annular channel are mixed into the melt. When the melt containing organic pigment particles passes through the static mixing unit, the organic pigment particles and the melt are fully mixed. When the coating structure layer comes into contact with the melt, it melts or volatilizes and delays the release of the internal pigment core material to reduce the contact time between the pigment core material and the melt.

2. The apparatus for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments according to claim 1, characterized in that, The static mixing unit includes at least three mixers, which are arranged sequentially along the axial direction of the melt flow channel. The mixers are tetrahedral in structure.

3. The apparatus for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments according to claim 2, characterized in that, The length of the edge of the mixer is the same as the inner diameter of the sleeve. Two non-adjacent and perpendicular edges on the mixer are fixed edges. The fixed edges are arranged in the melt flow channel along the diameter direction of the sleeve. The two ends of the fixed edges are fixedly connected to the inner wall of the sleeve. The fixed edge on the side of the mixer closer to the pigment coloring unit is the first fixed edge, and the fixed edge on the other side is the second fixed edge. In two adjacent mixers, the second fixed edge of the first mixer is perpendicular to the first fixed edge of the second mixer.

4. The apparatus for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments according to claim 1, characterized in that, The material of the coating structure layer is chitosan.

5. The apparatus for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments according to claim 4, characterized in that, Organic pigment particles with a coating structure layer are prepared by coating chitosan onto the surface of pigment core material using a spray drying method.

6. The apparatus for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments according to claim 1, characterized in that, The radius r of the pigment solid inner core and the inner radius R of the pigment solid outer ring cylinder satisfy the following relationship: D / 2 R=r; In the formula, D is the inner diameter of the sleeve; through the above relationship, the total contact area between the pigment coloring unit and the melt remains stable as the organic pigment particles are consumed.

7. The apparatus for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments according to claim 1, characterized in that, A heater is provided on the outer side of the sleeve.

8. A process for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments, based on the equipment for preparing colored polyvinyl chloride monofilaments by coloring with organic pigments according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Organic pigment particles with a coating structure layer are prepared by spray drying process using organic pigments as core material and chitosan as coating structure layer. S2: Organic pigment particles are filled into a mold and compacted to form a pigment solid inner core and a pigment solid outer ring cylinder. Pigment coloring units are made by using the pigment solid inner core, pigment solid outer ring cylinder and perforated plate. Pigment coloring units are placed in the corresponding installation positions in the screw extruder. S3: The monofilament raw material is fed into the screw extruder, melted and plasticized at 160-190℃ and conveyed forward to form a flowing melt; S4: After the melt leaves the screw, it flows through the annular channel of the pigment coloring unit. The organic pigment particles on the surface of the annular channel are mixed into the melt, resulting in a melt mixed with organic pigment particles. S5: The melt containing organic pigment particles passes through multiple mixers in the static mixing unit in sequence. After being divided and cross-fused radially and axially by the mixers, a uniform colored melt is formed. S6: The colored melt is sprayed out through the spinneret and then cooled and solidified to obtain colored polyvinyl chloride monofilament.

9. The preparation process for preparing colored polyvinyl chloride monofilaments by organic pigment coloring according to claim 8, characterized in that, The raw material for the monofilament is polyvinyl chloride resin.

10. The preparation process for preparing colored polyvinyl chloride monofilaments by organic pigment coloring according to claim 8, characterized in that, The total time from the moment the melt first comes into contact with the organic pigment particles to the moment it is ejected from the spinneret does not exceed 3 minutes.

Images