Polymer mixing or devolatilization device and mixing devolatilization method

Abstract

The invention discloses a polymer mixing or devolatilization device and a mixing and devolatilization method, and the mixing and devolatilization method comprises the following steps: dispersing an additive fluid into micro / small liquid drops or micro / small bubbles, injecting the micro / small liquid drops or micro / small bubbles into a polymer melt in a high-frequency and intermittent manner, and mixing the micro / small liquid drops or micro / small bubbles with the polymer melt; then controlling reaction conditions to change to remove volatile components; the mixing or devolatilization device comprises a shell, and a plurality of additive injection ports are formed in the shell; the additive distributor is communicated with the additive injection ports; the pulse flow generator is connected with the additive distributor; an additive sequentially passes through the pulse flow generator, the additive distributor and the additive injection port and is jetted into the shell in a high-frequency and intermittent mode. The method provided by the invention can promote the small molecular substances to diffuse into the bubbles / liquid drops, so that the volatilizable small molecular substances are rapidly removed, the polymer melt suitable for direct spinning or other subsequent processing is obtained, the process flow can be shortened, the energy consumption is reduced, and the investment is saved.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and chemical equipment, specifically, it relates to a polymer mixing or devolatilization device and a mixing and devolatilization method. Background Technology

[0002] Polyamide 6 fiber ranks second in production volume among synthetic fibers, but industrial production still relies on melt spinning of chips. Due to technical limitations, direct melt spinning of polyamide 6 fibers has not been industrialized. The key lies in preparing a suitable polyamide 6 melt for direct spinning. Polyamide 6 is a condensation polymer with caprolactam as the reactant monomer. When the reaction reaches equilibrium, the polymerization product is approximately 90% polyamide 6 and 10% extractable low-molecular-weight substances (of which caprolactam monomer accounts for about 80% and oligomers about 20%). Because of the presence of these extractable low-molecular-weight substances, direct spinning is not possible. Currently, the main method used in industrial plants is to cool and granulate the polyamide 6 melt, then extract the chips with hot water, dry the extracted chips, and then melt spin them. Hot water extraction and drying consume more than 50% of the energy and time of the entire polymerization process, and also require the treatment of large amounts of wastewater. Therefore, direct spinning of the polymer melt without extraction and drying is an effective method for shortening the process flow, reducing production costs, and providing environmental and economic benefits for polyamide 6 fibers. However, the current technical challenge lies in how to directly extract small-molecule extractable substances in the polymer molten state and meet the requirements for direct spinning.

[0003] Patent application CN105669969A discloses a method for polymerizing nylon 6 and its melt spinning method. The method involves first preparing a polyamide 6 prepolymer at low temperature and pre-controlling the oligomer content in the melt. Then, by strengthening the kinetics of the polycondensation reaction, the polymerization is completed before a large amount of cyclic oligomers are generated, resulting in a nylon 6 polymer melt with a certain molecular weight. The extracted content of the obtained product is ≤1.5wt%, and the cyclic dimer content is ≤0.2wt%. After the polycondensation reaction kinetics are strengthened, the product is directly melt-spun into fibers.

[0004] Patent application CN109811423A discloses a technical improvement method for producing functional polyamide fibers through continuous melt direct spinning. This method involves obtaining a functional powder slurry through multi-stage grinding and dispersion, which is then uniformly mixed with caprolactam melt and a catalyst via a dynamic mixer. The mixture is then fed into a hydrolysis and polymerization reactor via a heat exchanger. Polymer melt dehydrators are installed after the open-loop reactor and the prepolymerization reactor, respectively. The resulting functional polyamide melt is then directly fed into a spinning box to obtain functional polyamide fibers after caprolactam monomer removal via a thin-film evaporation devolatilization system. The dehydrators and thin-film evaporation devolatilization system effectively reduce the oligomer content in the melt.

[0005] Due to the limitations of reaction equilibrium conditions and the high melting point and low solubility of oligomers, industrial equipment uses hot water extraction to remove small molecules. After extraction, the product needs to be dried and remelted before spinning. Moreover, the extract needs to be evaporated and concentrated before the extract can be recycled. The process is long and energy-intensive.

[0006] Existing methods for reducing small molecule substances in melts all have some problems due to the particular difficulty in removing oligomers, making it difficult to directly spin the polymerized melt for industrial application.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The technical problem to be solved by this invention is to overcome at least one of the shortcomings of the prior art and provide a polymer mixing or devolatilization device and a mixing and devolatilization method. In the mixing or devolatilization device of this invention, the additive passes sequentially through a pulse flow generator, an additive distributor, and an additive injection port, forming a large number of small droplets or small bubbles, which are sprayed into the interior of the shell in a high-frequency, intermittent manner. This not only improves the mixing effect but also promotes the diffusion of small molecules into the bubbles / droplets, thereby promoting the removal of small volatile molecules.

[0009] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention provides a polymer mixing or devolatilization apparatus, comprising:

[0011] A housing having multiple additive injection ports;

[0012] An additive dispenser connected to multiple additive injection ports;

[0013] A pulse flow generator is connected to the additive dispenser;

[0014] The additive is sequentially injected into the housing through a pulse generator, an additive distributor, and an additive injection port in a high-frequency, intermittent manner.

[0015] In a further embodiment, the additive injection ports are regularly distributed in the axial and circumferential directions of the shell.

[0016] In a further embodiment, the additive injection port is located below the liquid level during normal operation of the mixing or devolatilization device.

[0017] In a further embodiment, the diameter or width of the additive injection port is 0.1-3 mm;

[0018] Preferably, the diameter or width of the additive injection port is 0.3-1.5 mm.

[0019] In a further embodiment, the number of additive injection ports gradually decreases from the inlet end to the outlet end in the axial direction of the shell.

[0020] Preferably, no additive injection ports are distributed at the discharge end.

[0021] In a further embodiment, the additive dispenser includes a delivery pipe and multiple distribution pipes, with one end of each distribution pipe connected to the delivery pipe and the other end connected to an additive injection port.

[0022] In a further embodiment, a rotating element is provided inside the housing, corresponding to the positions where additive injection ports are located on the housing.

[0023] In a further embodiment, the rotating element has an additive channel inside and an additive injection port on its surface.

[0024] In a further embodiment, a fixing element is provided inside the housing, the fixing element has an additive channel inside, and the surface of the fixing element has an additive injection port.

[0025] Preferably, the fixing element is fixed to the inner wall of the housing, and the additive channel of the fixing element is connected to the additive dispenser.

[0026] In a second aspect, the present invention provides a method for polymer melt mixing and devolatilization, comprising:

[0027] The additives are injected into the polymer melt at multiple points, at high frequency, and intermittently in the form of micro / small droplets or micro / small bubbles, and are uniformly dispersed in the polymer melt under stirring. The reaction conditions are then controlled to complete further mixing and removal of volatile components. The resulting polymer melt can be directly spun or otherwise processed.

[0028] As a preferred method, mixing and devolatilization are performed using the mixing or devolatilization device described above, the method comprising:

[0029] The additive fluid is sequentially fed to a pulse flow generator and an additive distributor. Within the distributor, a pulse flow of a specific frequency is generated, and the fluid is broken into small droplets or bubbles through multiple additive injection ports. This is then injected into the mixing or devolatilization device in a high-frequency, intermittent manner, and uniformly dispersed into the polymer melt under the action of rotating elements. This promotes the diffusion of volatile substances, allowing the resulting polymer melt to be directly spun or subjected to other subsequent processing.

[0030] It should be noted that the polymer described in this invention can be any type, as long as it involves polymer melt devolatiles removal and direct spinning, this invention can be applied. Alternatively, the polymer can be a polyamide, such as polyamide 6.

[0031] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0032] 1. In the polymer mixing or devolatilization device of the present invention, the additive fluid can sequentially pass through a pulse flow generator, an additive distributor, and an additive injection port, and be injected into the shell in the form of micro / small bubbles or droplets in a high-frequency, intermittent manner, entering the polymer melt. Under the action of the rotating element of the mixing or devolatilization device, it is fully mixed with the polymer melt, so that a large number of uniformly dispersed micro / small bubbles or droplets are formed inside the polymer melt, which increases a large number of gas-liquid mass transfer interfaces. Polymer monomers and sparingly soluble oligomers can quickly diffuse into the bubbles or droplets, laying the foundation for mixing and removal of small molecule oligomers.

[0033] In the devolatilization unit, a large number of small bubbles expand rapidly under a high vacuum environment, or droplets vaporize into bubbles. Due to the film-pulling effect of the rotating elements inside the devolatilization unit, it has a strong surface renewal capability. Not only are volatiles continuously removed from the renewed surface, but these bubbles are also constantly exposed to the melt surface and burst. Small molecules such as polymer monomers and oligomers inside the bubbles also enter the gas phase space and are extracted. At this time, the bursting liquid of the bubbles promotes the surface renewal of the melt, realizing the efficient removal of small molecules and obtaining a polymer melt suitable for direct spinning or other subsequent processing. This reduces the need for polymer fibers and products to process the polymer melt into slices and remelt them, further shortening the process flow, reducing energy consumption, and saving investment.

[0034] In addition, by adjusting the types of additives, the molecular weight, physical and chemical properties of polymers can be effectively regulated and controlled, enabling polymer melts to meet the requirements for direct spinning or direct subsequent processing, thereby further shortening the process flow and reducing product costs.

[0035] 2. The device of the present invention can also add various other functional additives and modified additives, and can also replace various functional masterbatches, eliminating the processes of masterbatch manufacturing and remelting, resulting in significant energy saving and cost reduction.

[0036] 3. The polymer mixing or devolatilization device of the present invention can be improved based on existing devices, and is suitable for mixing, devolatilization and direct spinning of various polymer melts, and is applicable to the field of fibers and products of various types of polymers.

[0037] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0038] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0039] Figure 1 This is a schematic flowchart of the mixed devolatilization method of the present invention;

[0040] Figure 2 This is a cross-sectional view of the horizontal high-efficiency mixer in Embodiment 1 of the present invention (the internal structure of the shell is not shown), wherein A is a side cross-sectional view and B is a main cross-sectional view;

[0041] Figure 3 This is a cross-sectional view of the horizontal rotary degassing device in Embodiment 2 of the present invention (the internal structure of the housing is not shown), wherein A is a side cross-sectional view and B is a main cross-sectional view;

[0042] Figure 4 This is a front sectional view of the horizontal high-efficiency mixer in Embodiment 3 of the present invention (only partial structure is shown);

[0043] Figure 5 This is a front sectional view of the vertical rotary devolatile generator in Embodiment 4 of the present invention (only partial structure is shown);

[0044] Among them, 1-shell, 2-additive dispenser, 21-delivery pipe, 22-distribution pipe, 3-additive injection port, 4-pulse flow generator, 5-rotating element, 51-rotating shaft, 52-rotating blade, 6-fixing element, 7-additive channel.

[0045] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0047] like Figures 1 to 5 As shown, the present invention provides a polymer mixing or devolatilization apparatus. include:

[0048] The housing 1 has multiple additive injection ports 3; the housing 1 is equipped with a rotating element 5 inside.

[0049] Additive dispenser 2 is connected to multiple additive injection ports 3;

[0050] Pulse flow generator 4 is connected to additive dispenser 2;

[0051] The additive passes sequentially through the pulse generator 4, the additive distributor 2, and the additive injection port 3, and is sprayed into the interior of the housing 1 in a high-frequency, intermittent manner.

[0052] The polymer mixing or devolatilization device of the present invention has a hollow housing 1 that can accommodate polymer melt. After the additive passes through the pulse generator 4, the additive distributor 2, and the additive injection port 3 in sequence, it forms a large number of small droplets or bubbles, which are sprayed into the housing 1 in a high-frequency, intermittent manner. Under the action of the rotating element 5, more micro / small bubbles or droplets appear in the melt and are evenly distributed in the melt. This can improve the mixing effect and promote the diffusion of small molecules in the melt into the bubbles / droplets. Then, when the reaction equilibrium conditions are changed, the small volatile molecules are rapidly removed to obtain a polymer melt suitable for direct spinning, which is then directly transported to the spinning box for spinning or directly subjected to other subsequent processing.

[0053] In this invention, there is no limitation on the specific type of additive; the additive can be any compound or composition that needs to be added to the polymer melt. For example, the additive can be selected from polymer monomers, solvents, functional additives or modifiers, additives that improve light, heat, climate, chemical stability, and physical properties, etc. Specifically, the additive can be selected from nucleating agents, foaming agents, stripping agents, extractants, catalysts, matting agents, molecular weight regulators, antioxidants, UV stabilizers, colorants, flame retardants, antibacterial agents, chain extenders, etc.

[0054] The additive can be a gas, a liquid, a solid, or a mixture of two or three of these states. The average particle size of the solid additive mixture is not higher than 0.5-5 μm and has good dispersibility.

[0055] After the additive is stirred evenly in the preparation tank, it is first sent to a preheater for preheating. The preheating temperature of the slurry is lower than the boiling point of each component under the operating pressure. The preheated additive is then sequentially injected into the melt through the pulse flow generator 4, the additive distributor 2, and the additive injection port 3.

[0056] In this invention, the additive injection ports 3 are regularly distributed in the axial and circumferential directions of the housing 1.

[0057] In this invention, the additive injection port 3 is located below the liquid surface during normal operation of the mixing or devolatilization device. In this way, the fluid injected through the additive injection port 3 directly enters the melt, which is conducive to the formation of a large number of tiny liquids or bubbles.

[0058] In this invention, the diameter or width of the additive injection port 3 is 0.1-3 mm;

[0059] Preferably, the diameter or width of the additive injection port 3 is 0.3-1.5 mm.

[0060] In this invention, the additive injection port 3 can be a small-diameter tube, a small hole, or a slit. Its diameter or width needs to be controlled to be 0.1-3 mm. This allows the additive fluid to form a large number of small liquids or small bubbles after passing through the narrow additive injection port 3, thereby fully mixing with the melt. At the same time, it is beneficial for small molecules in the melt to diffuse into the bubbles / droplets and then be quickly removed.

[0061] In this invention, the number and distribution pattern of the additive injection ports 3 are determined according to different material requirements.

[0062] In this invention, the number of additive injection ports 3 can be set according to actual needs, and the number of additive injection ports 3 is related to the flow rate of the additive.

[0063] In this invention, as a preferred embodiment, the number of additive injection ports 3 gradually decreases from the feed end to the discharge end in the axial direction of the housing 1; preferably, no additive injection ports 3 are distributed at the discharge end.

[0064] The additive dispenser 2 includes a delivery pipe 21 and a plurality of dispensing pipes 22. One end of each dispensing pipe 22 is connected to the delivery pipe 21, and the other end is connected to an additive injection port 3.

[0065] In this invention, one or more conveying pipes 21 can be provided, and multiple distribution pipes 22 are connected to each conveying pipe 21. The conveying pipe 21 can be a straight pipe, parallel to the axial direction of the housing 1; or it can be an annular pipe or a semi-annular pipe, surrounding the outer periphery of the housing 1.

[0066] When the delivery pipe 21 is a straight pipe, multiple distribution pipes 22 are spaced apart along the axial direction of the delivery pipe 21, and the line connecting the multiple distribution pipes 22 to the delivery pipe 21 is parallel to the axial direction. That is to say, the multiple distribution pipes 22 are located at the same position on the outer periphery of the delivery pipe 21. The multiple distribution pipes 22 correspond to multiple additive injection ports 3 distributed along the axial direction on the housing 1.

[0067] When the delivery pipe 21 is annular, multiple distribution pipes 22 are located on the inner circumference of the annular delivery pipe 21, arranged at intervals, and extending in the radial direction, corresponding to and communicating with multiple additive injection ports 3 distributed around the circumference of the housing 1. Preferably, when the delivery pipe 21 is semi-annular, it is located below the normal liquid level in the housing 1.

[0068] In this invention, the diameter of the delivery pipe 21 is much larger than the diameter of the distribution pipe 22, and the diameter of the distribution pipe 22 is much larger than the diameter of the additive injection port 3. This facilitates the gradual increase of pressure, and the additive fluid can form a large number of tiny bubbles or droplets inside the melt, which is beneficial for mixing or devolatilization.

[0069] The housing 1 is equipped with a rotating element 5, which is distributed on the housing 1 at the position where the additive injection port 3 is located.

[0070] In this invention, the rotating element 5 includes a rotating shaft 51 and blades distributed on the rotating shaft 51. The rotating element 5 can also be called a stirrer. The blades can be distributed at intervals or continuously on the rotating shaft 51. The housing 1 is provided with an additive injection port 3, and blades are distributed accordingly. In this way, the small droplets or bubbles of additive injected into the melt can be uniformly dispersed into the polymer melt under the action of the rotating blades 52.

[0071] In this invention, the rotating element 5 has an additive channel 7 inside and an additive injection port 3 on its surface.

[0072] In this invention, the rotating shaft 51 is a hollow shaft, and multiple sets of rotating blades 52 are arranged at intervals on the rotating shaft 51. An additive channel 7 is provided inside the rotating shaft 51 and / or the rotating blades 52, and an additive injection port 3 is provided on the surface of the rotating shaft 51 and / or the rotating blades 52.

[0073] In this invention, a fixing element 6 is provided inside the housing 1, an additive channel 7 is provided inside the fixing element 6, and an additive injection port 3 is provided on the surface of the fixing element 6.

[0074] Preferably, the fixing element 6 is fixed on the inner wall of the housing 1, and the additive channel 7 of the fixing element 6 is connected to the additive dispenser 2.

[0075] The fixing element 6 can be any structure disposed on the inner wall of the housing 1. As an alternative embodiment, the fixing element 6 of the present invention can be a structure that cooperates with the rotating element 5 to increase the shearing effect of the melt, such as a rod or plate extending into the housing 1. The rotating element 5 and the fixing element 6 can be kneaded together to further enhance the mixing effect.

[0076] The dispensing tube 22 of the additive dispenser 2 can pass through the housing 1 and communicate with the additive channel 7 of the fixing element 6. The diameter of the additive channel 7 is not greater than the diameter of the dispensing tube 22.

[0077] In this invention, the additive fluid can enter the melt not only through the additive injection port 3 on the wall of the housing 1, but also through the additive channel 7 inside the rotating element 5 or the stationary element 6, and enter the melt through the additive injection port 3 on the surface of the rotating element 5 or the stationary element 6. The number of additive injection ports 3 on the surface of the rotating element 5 or the stationary element 6 is also related to the flow rate of the additive.

[0078] In this invention, the pulse flow generator 4 can generate a pulse flow of a certain frequency in the additive fluid, and the pulse flow is injected into the mixing or devolatilization device in a high-frequency intermittent manner through the additive distributor 2.

[0079] In this invention, the pulse flow generator 4 can be electromagnetic or mechanical, and the frequency of the generated pulse flow is related to the rotational speed of the mixing or devouring device and the number of rotor blades.

[0080] In this invention, the mixing or devolatification device is a mixer or a devolatifier, which can be horizontal or vertical.

[0081] In this invention, the rotating shaft 51 of the mixing or devolatilization device is one or more types, such as single shaft, double shaft, triple shaft, or multi-shaft.

[0082] In this invention, the agitator in the mixing or devolatilization device can be one or more of the following types: cage type, disc type, scraper type, rod / bar type, paddle type, screw / ribbon type, etc.

[0083] In this invention, the cross-section of the housing 1 of the mixing or devolatilization device can be any shape, such as one or more of the following: circular, oblong, figure-eight, peach-shaped, and plum-blossom-shaped.

[0084] As one specific implementation method, The rotating element 5 and the fixed element 6 in the devouring device are arranged as follows:

[0085] The rotating element 5 includes a rotating shaft 51, a rotating disc, and a rotating film-stretching component. The rotating disc is mounted on the rotating shaft 51 and rotates with the rotating shaft 51. The radial direction of the rotating disc is perpendicular to the axis of the rotating shaft 51. The rotating film-stretching component is mounted on the rotating disc.

[0086] The rotating disk can be any shape found in the prior art. Alternatively, the rotating disk can be one or a combination of several of the following shapes: disc-shaped, ring-shaped, fan-shaped, star-shaped, triangular, eye-shaped, spindle-shaped, spoke-shaped, or others. Preferably, the rotating disk is either disc-shaped or star-shaped.

[0087] The described rotating disk can be integral or split. The integral type means the entire structure of the rotating disk is a single entity and is entirely connected to the rotating shaft 51; the split type means the rotating disk is divided into multiple parts and is independently connected to the shaft.

[0088] There are various ways to set the rotating film pulling member. As an optional way, the rotating film pulling member can be set as one or a combination of a bar shape, a strip shape, a C shape, a ┝ shape, an L shape, a 干 shape, a 丰 shape.

[0089] As a preferred way, the rotating film pulling member on the rotating disk is one or a combination of a bar shape, a C shape, a 干 shape.

[0090] The rotating film pulling members are arranged on one or both sides of the surface of the rotating disk. The film pulling members can be arranged on different diameter circumferences of each rotating disk. As several specific schemes, for example:

[0091] Scheme 1: The rotating film pulling member is set as a bar or a strip and is fixed on the outermost periphery of the rotating disk. The length direction of the bar or the strip is parallel to or forms a certain angle with the axis direction of the rotating shaft 51. The two ends of the bar or the strip in the length direction are located on both sides of the rotating disk.

[0092] Scheme 2: The rotating film pulling member is set as a C shape, that is, it includes two side plates and a connecting plate. The two ends of the two side plates opposite to the connecting plate are connected. A fixing groove is provided on the outermost periphery of the rotating disk, and the middle part of the connecting plate is installed in the fixing groove. In this way, after the rotating film pulling member is on the outermost periphery of the rotating disk, the rotating film pulling member and the rotating disk form an E-shaped structure.

[0093] The length direction of the rotating film pulling member is parallel to or forms a certain angle α with the axis of the rotating shaft 51. Preferably, the angle α is 0.5 - 20°.

[0094] The length direction of each rotating film pulling member can be parallel to or form a certain angle α with the axis of the rotating shaft 51; or, it can also be that the connection line of multiple rotating film pulling members arranged along the axial direction is parallel to or forms a certain angle α with the axis, or it can also be set in combination. In this way, the shearing effect on the melt can be increased.

[0095] The described rotating film forming assembly includes multiple groups and is arranged at intervals along the axis direction of the rotating shaft 51. The rotating disks in each group of rotating film forming assemblies are concentric and parallel.

[0096] The rotating film pulling members can be arranged on different diameter circumferences of each rotating disk. Multiple rotating film pulling members are provided on each rotating disk, and the multiple rotating film pulling members can be located on the same circumference or different circumferences;

[0097] As a preferred embodiment, the number of the rotary film pulling members located on the same circumference is 2 - 8.

[0098] As a preferred embodiment, the gap between the rotary film pulling member located on the outermost periphery and the inner wall of the housing 1 is 0.5 - 80 mm. In this way, it can not only ensure the unobstructed rotation of the rotary film pulling member, but also cooperate with the inner wall of the housing 1 and the fixed film pulling member to play a better shearing and stretching role on the melt.

[0099] The fixed element 6 is a fixed film pulling member. The length direction of the fixed film pulling member is parallel to the axis of the rotary shaft 517 or forms a certain included angle α. Corresponding to the rotary film pulling member, and it is located below the melt liquid level during normal operation;

[0100] Preferably, the included angle α is 0.5 - 20°.

[0101] The length direction of each fixed film pulling member can be parallel to the axis of the rotary shaft 51 or form a certain included angle α; or, it can also be that the connection line of multiple fixed film pulling members arranged along the axial direction is parallel to the axis or forms a certain included angle α, or it can also be a combined setting. In this way, the shearing effect on the melt can be increased.

[0102] The fixed film pulling member is set as one or a combination of a bar shape, a strip shape, a C shape, a ┝ shape, an L shape, a dry character shape, a feng character shape, etc.;

[0103] The shape of the fixed film pulling member is correspondingly set with that of the rotary film pulling member, and the two are in a mutually kneading relationship. For example, both the fixed film pulling member and the rotary film pulling member are in a C shape, and the C shapes of the two members are mutually kneaded. A channel with a certain width for the melt to pass through is formed between the side plates of the two members, increasing the shearing and stretching effects on the melt.

[0104] Multiple fixed film pulling members located on the same cross-section of the housing 1 form a set of fixed film pulling members. Along the axis direction of the rotary shaft 51, a set of fixed film pulling members is provided between two adjacent rotary film forming assemblies. In this way, the rotary film forming assemblies and the fixed film pulling members are arranged alternately, facilitating the formation of a kneading relationship.

[0105] Preferably, each set of fixed film pulling members includes 1 - 6 independent fixed film pulling members.

[0106] In the present invention, a fluid channel is provided inside the fixed film pulling member; a heat medium or an additive can be introduced inside. When an additive is introduced inside, an additive injection port 3 is further provided on the surface of the fixed film pulling member to connect the fluid channel with the internal space of the housing 15, and the additive is sprayed into the melt inside the housing 1 through the additive injection port 3.

[0107] The dispensing pipe 22 of the additive dispenser 2 can pass through the housing 1 and communicate with the fluid channel of the fixed membrane assembly. The diameter of the fluid channel is not greater than the diameter of the dispensing pipe 22.

[0108] This invention also provides A method for mixing and devolatilization using the mixing or devolatilization apparatus described above, comprising:

[0109] (1) The polymer melt is conveyed into the housing 1 of the mixing or devolatilization device;

[0110] (2) After the additive fluid is preheated, it is sequentially transported to the pulse flow generator 4 and the additive distributor 2. A pulse flow of a certain frequency is formed in the additive distributor 2 and is broken into small droplets or small bubbles through multiple additive injection ports 3. It is sprayed into the shell 1 in a high-frequency, intermittent manner and mixed with the polymer melt. The extractable small molecules in the melt diffuse into the small droplets or small bubbles to complete the mixing or devolatilization.

[0111] Reference Figure 1 The process shown involves continuously polymerized polymer melt being fed with various additives (especially nucleating agents, foaming agents, and molecular weight stabilizers) via a pulse flow generator 4 and an additive distributor 2 in the form of high-frequency, intermittent small droplets or bubbles. Under the action of a high-efficiency mixer or rotating mixing component, more micro / small bubbles or droplets appear in the melt and are evenly distributed throughout the melt, promoting the diffusion of small molecules in the melt into the bubbles / droplets. Then, the reaction equilibrium conditions are changed to rapidly remove small volatile molecules, resulting in a polymer melt suitable for direct spinning. This melt is then directly transported to the spinning box for spinning or directly subjected to other subsequent processing.

[0112] In this invention, the additive fluid can be added to the mixer or to the devolatilizer. Figure 1 The dashed section indicates that in cases where it is inconvenient to add a high-efficiency mixer, or where the process does not require or allows a mixer, the polymer melt directly enters the devolatilizer, and the additives are also directly injected into the devolatilizer through the additive distributor and additive injection port.

[0113] Specifically, the present invention provides the following embodiments to further illustrate the solution of the present invention.

[0114] Example 1

[0115] like Figure 2 As shown, a horizontal high-efficiency mixer has multiple additive injection ports evenly distributed along the circumferential and axial directions on the shell wall 1 of the mixer. The additive injection ports are connected to the delivery pipe 2 through the distribution pipe 3, and the delivery pipe 2 is connected to the pulse flow generator.

[0116] After polymerization in the polymerizer, the polyamide 6 melt is pumped to a high-efficiency mixer, which is a horizontal dynamic rotary type. Figure 2 Multiple additive injection ports are regularly distributed on the inner surface of the high-efficiency mixer housing. The additives are injected into the high-efficiency mixer at high frequency and intermittently from the additive injection ports and are stirred and mixed by the rotating blades of the mixer, and uniformly dispersed in the polyamide 6 melt.

[0117] Caprolactam, used as an additive, is melted and preheated to 180-230°C, then pumped to a pulse flow generator. The pulse flow generator then generates a pulse flow of a certain frequency within the delivery pipe 2. This pulse flow is injected into the high-efficiency mixer at a high frequency and intermittently through the distribution pipe 3 and additive injection ports distributed on the inner wall of the high-efficiency dynamic mixer. Under the action of the rotating components of the high-efficiency mixer, the caprolactam liquid is dispersed into small droplets at the additive injection port opening in the shell, and thoroughly mixed with the polyamide 6 melt from the subsequent polymerization reactor. This further breaks up the caprolactam droplets and evenly disperses them within the polyamide 6 melt. The polyamide 6 melt is heated to 240-280°C by the jacket heat medium of the high-efficiency mixer, causing the caprolactam droplets to rapidly vaporize into bubbles. Extractable small molecules (mainly caprolactam oligomers) in the polyamide 6 melt continuously diffuse into the small bubbles and droplets.

[0118] The polyamide 6 melt exiting the high-efficiency mixer is conveyed to the devolatifier under pressure differential. The devolatifier operates at a temperature of 240–280°C, a pressure of 0.05–100 kPa, and a duration of 5–90 min. The devolatifier is a horizontal rotary type, with rotating components exhibiting excellent film-stretching properties and a high melt surface renewal rate. Under high temperature and vacuum conditions, the continuously renewed melt surface allows extractable small molecules to diffuse out continuously. Simultaneously, small bubbles introduced by the high-efficiency mixer expand and rupture upon reaching the melt surface, releasing the extractable substances diffused into these bubbles. This combined effect removes most of the extractable small molecules from the polyamide melt, achieving an extractable small molecule content of ≤1.0 wt%. After devolatation, the relative viscosity of the polyamide 6 melt is 2.0–5.0.

[0119] Example 2

[0120] like Figure 3 As shown, a horizontal rotary devolveizer has multiple additive injection ports evenly distributed along the circumferential and axial directions on the shell wall 1 of the devolveizer. All additive injection ports are located below the liquid surface during normal operation of the devolveizer. The additive injection ports are connected to the delivery pipe 2 through the distribution pipe 3, and the delivery pipe 2 is connected to the pulse flow generator.

[0121] After polymerization in the polymerizer, the polyamide 6 melt is pumped to a devolver. The devolver is a horizontal, dynamic, rotating type, with rotating components that provide excellent film-stretching properties and a high melt surface renewal rate. Figure 3 Multiple additive injection ports are regularly distributed on the inner surface of the devolvator shell. In the axial direction of the shell, the number of additive injection ports gradually decreases from the feed end to the discharge end, and there are no more additive injection ports at the discharge end. The additive is injected into the devolvator at a high frequency and intermittently from the additive injection ports, and is stirred and mixed by the rotating blades of the devolvator, and uniformly dispersed in the polyamide 6 melt.

[0122] The caprolactam, used as an additive, is melted and preheated to 180–230°C, and then pumped to a pulse flow generator. The pulse flow generator then generates a pulse flow of a certain frequency in the delivery pipe 2. The pulse flow is injected into the devoluter in a high-frequency, intermittent manner through the distribution pipe 3 and the additive injection ports distributed on the inner wall of the devoluter. Under the action of the rotating parts of the devoluter, the caprolactam liquid is dispersed into small droplets at the opening of the additive injection port entering the shell, and is fully mixed with the polyamide 6 melt delivered from the subsequent polymerization reactor. The caprolactam droplets are further broken up and evenly dispersed in the polyamide 6 melt. Heat is provided by the jacket heat medium of the devoluter, and the caprolactam droplets are rapidly vaporized into bubbles. Extractable small molecules (mainly caprolactam oligomers) in the polyamide 6 melt continuously diffuse into the small bubbles and droplets.

[0123] Under the high temperature and vacuum conditions of the devolatizer, on the one hand, the interface between the polyamide 6 melt and the gas phase is constantly renewed, causing the extractable small molecules inside the melt to diffuse out continuously; on the other hand, the small bubbles inside the polyamide 6 melt expand and are exposed to the melt surface and rupture, and the extractable substances diffused into the small bubbles are also released. Under the combined effect, most of the extractable small molecules in the polyamide melt can be removed, so that the content of extractable small molecules reaches ≤1.0wt%. After the devolatization is completed, the relative viscosity of the polyamide 6 melt is 2.0 to 5.0.

[0124] Example 3

[0125] like Figure 4 As shown, a horizontal high-efficiency mixer has multiple additive injection ports evenly distributed along the circumferential and axial directions on the shell wall 1 of the mixer. The additive injection ports are connected to the delivery pipe 2 through the distribution pipe 3, and the delivery pipe 2 is connected to the pulse flow generator.

[0126] The mixer contains a rotating element, which includes a rotating shaft and rotating blades. The rotating shaft is a hollow shaft, and multiple sets of rotating blades are spaced apart on the rotating shaft. Additive channels are provided inside the rotating shaft and / or rotating blades, and additive injection ports are provided on the surface of the rotating shaft and / or rotating blades.

[0127] The mixer is equipped with a fixing element 5 that is fixed to the shell wall 1 and extends into the shell 1. The rotating blades and the fixing element 5 interact with each other to enhance the mixing effect. The fixing element 5 can be in various forms such as rod / stick, ring, mountain, T, L, convex, spiral, and sheet. The surface of the fixing element 5 of the mixer has multiple additive injection ports regularly opened. The additive injection ports are connected to the additive channel inside the fixing element 5. The additive channel inside the fixing element 5 is connected to the distribution pipe 3 outside the mixer. The distribution pipe 3 is connected to the conveying pipe 2.

[0128] After polymerization in the polymerizer, the polyamide 6 melt is pumped to a high-efficiency mixer. The high-efficiency mixer is a horizontal, dynamic rotary type, with the rotating element and the fixed element 5 structurally matched. Figure 4 Multiple additive injection ports are regularly distributed on the inner surface of the high-efficiency mixer housing and the surface of the fixed element 5. The additives are injected into the high-efficiency mixer at high frequency and intermittently from the additive injection ports and are stirred and mixed by the rotating blades of the mixer, and uniformly dispersed in the polyamide 6 melt.

[0129] The nitrogen and water vapor mixture, used as an additive, is preheated to 100–180°C and sent to a pulse flow generator via a pipeline. The pulse flow generator then generates a pulse flow of a certain frequency in the delivery pipe 2. The pulse flow is injected into the high-efficiency mixer in a high-frequency, intermittent manner through the additive injection ports distributed on the inner wall of the distribution pipe 3, the inner wall of the high-efficiency dynamic mixer, and the surface of the fixed element 5. Under the action of the rotating part of the high-efficiency mixer, the mixed gas is divided into small bubbles at the opening of the additive injection port entering the shell and is fully mixed with the polyamide 6 melt sent from the subsequent polymerization reactor. At the same time, the small bubbles of the mixed gas are further broken up and uniformly dispersed in the polyamide 6 melt. Extractable small molecules (mainly caprolactam oligomers) in the polyamide 6 melt continuously diffuse into the small bubbles.

[0130] The polyamide 6 melt exiting the high-efficiency mixer is conveyed to the devolatifier under pressure differential. The devolatifier operates at a temperature of 240–280°C, a pressure of 0.05–100 kPa, and a duration of 5–90 min. The devolatifier is a horizontal rotary type, with rotating components exhibiting excellent film-stretching properties and a high melt surface renewal rate. Under high temperature and vacuum conditions, the continuously renewed melt surface allows extractable small molecules to diffuse out continuously. Simultaneously, small bubbles introduced by the high-efficiency mixer expand and rupture upon reaching the melt surface, releasing the extractable substances diffused into these bubbles. This combined effect removes most of the extractable small molecules from the polyamide melt, achieving an extractable small molecule content of ≤1.0 wt%. After devolatation, the relative viscosity of the polyamide 6 melt is 2.0–5.0.

[0131] Example 4

[0132] like Figure 5 As shown, a vertical rotary devolveizer has multiple additive injection ports distributed on its rotating element 6. All additive injection ports are located below the liquid surface during normal operation of the devolveizer. The additive injection ports are connected to the delivery pipe 2 via the rotating hollow shaft 7 of the devolveizer. The delivery pipe 2 is connected to the pulse flow generator.

[0133] After polymerization in the polymerizer, the polyamide 6 melt is pumped to a devolver. The devolver is a horizontal, dynamic, rotating type, with rotating components that provide excellent film-stretching properties and a high melt surface renewal rate. Figure 5 Multiple additive injection ports are regularly distributed on the surface of the rotating element 6 of the devolvator. The additives are injected into the devolvator at high frequency and intermittently through the additive injection ports, and are stirred and mixed by the rotating blades of the devolvator, and are evenly dispersed in the polyamide 6 melt.

[0134] The nitrogen and water vapor mixture, used as an additive, is preheated to 100–180°C and sent to a pulse flow generator via a pipeline. The pulse flow generator then generates a pulse flow of a certain frequency within the delivery pipe 2. The pulse flow is injected into the high-efficiency mixer in a high-frequency, intermittent manner through the additive injection ports distributed on the surface of the rotating hollow shaft 7 and rotating element 6 of the devolatilizer. Under the action of the rotating components of the high-efficiency mixer, the mixed gas is divided into small bubbles at the opening of the additive injection port entering the shell and is fully mixed with the polyamide 6 melt supplied from the subsequent polymerization reactor. At the same time, the small bubbles of the mixed gas are further broken up and uniformly dispersed in the polyamide 6 melt. Extractable small molecules (mainly caprolactam oligomers) in the polyamide 6 melt continuously diffuse into the small bubbles.

[0135] Under the high temperature and vacuum conditions of the devolatizer, on the one hand, the interface between the polyamide 6 melt and the gas phase is constantly renewed, causing the extractable small molecules inside the melt to diffuse out continuously; on the other hand, the small bubbles inside the polyamide 6 melt expand and are exposed to the melt surface and rupture, and the extractable substances diffused into the small bubbles are also released. Under the combined effect, most of the extractable small molecules in the polyamide melt can be removed, so that the content of extractable small molecules reaches ≤1.0wt%. After the devolatization is completed, the relative viscosity of the polyamide 6 melt is 2.0 to 5.0.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A polymer mixing or devolatilization device, characterized in that, include: A housing having multiple additive injection ports; An additive dispenser connected to multiple additive injection ports; A pulse flow generator is connected to the additive dispenser; The additive is sequentially injected into the housing through a pulse generator, an additive distributor, and an additive injection port in a high-frequency, intermittent manner.

2. The polymer mixing or devolatilization apparatus according to claim 1, characterized in that, The additive injection ports are regularly distributed in the axial and circumferential directions of the shell.

3. The polymer mixing or devolatilization apparatus according to claim 2, characterized in that, The additive injection port is located below the liquid level during normal operation of the mixing or devolatilization device.

4. The polymer mixing or devolatilization apparatus according to claim 1, characterized in that, The diameter or width of the additive injection port is 0.1-3 mm; Preferably, the diameter or width of the additive injection port is 0.3-1.5 mm.

5. The polymer mixing or devolatilization apparatus according to claim 1, characterized in that, In the axial direction of the shell, the number of additive injection ports gradually decreases from the inlet end to the outlet end; Preferably, no additive injection ports are distributed at the discharge end.

6. The polymer mixing or devolatilization apparatus according to any one of claims 1-5, characterized in that, The additive dispenser includes a delivery pipe and multiple distribution pipes, with one end of each distribution pipe connected to the delivery pipe and the other end connected to an additive injection port.

7. The polymer mixing or devolatilization apparatus according to any one of claims 1-5, characterized in that, The housing is equipped with rotating elements, which are distributed on the housing at the locations where additive injection ports are set.

8. The polymer mixing or devolatilization apparatus according to claim 7, characterized in that, The rotating element has an additive channel inside and an additive injection port on its surface.

9. The polymer mixing or devolatilization apparatus according to any one of claims 1-5, characterized in that, The housing is provided with a fixing element inside, the fixing element is provided with an additive channel inside, and the surface of the fixing element is provided with an additive injection port; Preferably, the fixing element is fixed to the inner wall of the housing, and the additive channel of the fixing element is connected to the additive dispenser.

10. A method for polymer melt mixing and devolatilization, characterized in that, include: The additives are injected into the polymer melt at multiple points, at high frequency, and intermittently in the form of micro / small droplets or micro / small bubbles, and are uniformly dispersed into the polymer melt under stirring. The reaction conditions are then controlled to complete further mixing and removal of volatile components. The resulting polymer melt can be directly spun or otherwise processed. Preferably, the polymer melt is mixed and devolatilized using the mixing or devolatilization apparatus as described in any one of claims 1-9, and the method includes: The additive fluid is sequentially delivered to the pulse flow generator and the additive distributor. A pulse flow of a certain frequency is formed in the additive distributor and injected into the mixing or devolatilization device in a high-frequency, intermittent manner through multiple additive injection ports as micro / small droplets or micro / small bubbles. Under the action of the rotating element, it is uniformly dispersed into the polymer melt, promoting the diffusion of volatiles, so that the resulting polymer melt can be directly spun or otherwise processed.

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