Spinning assembly, installation method thereof and preparation method of polyacrylonitrile fiber

Abstract

The invention relates to a spinning assembly, an installation method thereof and a preparation method of polyacrylonitrile fibers, and relates to the technical field of polyacrylonitrile fibers. According to the main technical scheme, the spinneret assembly comprises a spinneret plate, a distribution plate and a filter assembly. The distribution plate is located at the upstream position of the spinneret plate so as to distribute the spinning solution into all spinneret holes in the spinneret plate. The filtering assembly comprises a first-stage filtering structure, a second-stage filtering structure and a third-stage filtering structure; the secondary filtering structure is mounted at the upstream position of the distribution plate; the first-stage filtering structure is mounted at the upstream position of the second-stage filtering structure, and the filtering precision of the second-stage filtering structure is greater than that of the first-stage filtering structure; the third-stage filtering structure is mounted at the downstream position of the distribution plate and the upstream position of the spinneret plate; the filtering precision of the third-stage filtering structure is greater than that of the second-stage filtering structure. The spinning assembly is mainly used for improving the discharging uniformity of the spinning assembly, liquid leakage, blockage and the like are avoided, and the continuity of the spinning process is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of polyacrylonitrile fibers, in particular to a spinneret assembly and an installation method thereof, and a method for preparing polyacrylonitrile fibers. Background Art

[0002] With the rapid development of aerospace, national defense, military, automobile industry, medical equipment and other fields, the demand for high-performance polyacrylonitrile fiber is increasing. The preparation process of polyacrylonitrile fiber is constantly developing, from traditional wet spinning to dry and wet spinning, melt spinning, etc. Fiber quality is a key factor affecting its application performance and market competitiveness.

[0003] Among them, the spinneret assembly and its installation are the first step in the spinning process. The structural design of the spinneret assembly and its installation quality are directly related to the quality stability of the fiber. Reasonable structural design and correct installation of the spinneret assembly can avoid problems such as leakage and blockage of the spinneret assembly, ensure the continuity of the spinning process, reduce broken fibers caused by discontinuous spinning, avoid shutdowns and plate changes caused by leakage, and improve production efficiency. The precisely installed spinneret assembly can make the spinning liquid extrude evenly and stably through the spinneret hole, forming primary fibers with uniform thickness and smooth surface, reducing defects such as fiber breakage and hairy fibers, and improving fiber strength, modulus and other performance indicators.

[0004] Different spinneret assembly structures and installation methods can achieve different spinning process requirements, such as controlling the diameter, shape, orientation, etc. of the fiber, so as to meet the requirements of polyacrylonitrile fiber performance in different application fields. As described in patent CN105671651, the existing spinneret assembly uses an embedded spinneret as the spinning assembly, and the spinneret plate, distribution plate, gasket, multi-layer composite filter and other components are located in the embedded groove of the spinneret. The various components are tightly installed, which can effectively filter the impurities in the spinning solution, so that the spinning solution is evenly distributed to each spinneret hole, and the fiber quality and spinnability are improved. In the installation of the spinneret assembly, seals such as O-rings are used to seal each connection part to prevent leakage of the spinning solution. However, the existing spinneret assembly still has at least the following problems:

[0005] (1) The mesh size and installation position design of the above-mentioned multi-layer combined filter cannot ensure uniform and continuous discharge of the spinneret, and some of the spinneret holes even discharge gel, which is prone to clogging.

[0006] (2) The prior art spinneret assembly installation method lacks relevant research on offline installation process and online installation method, and its guidance is still insufficient. At present, there is an urgent need for a spinneret assembly installation method that can improve the uniformity and stability of the spinneret assembly discharge. Summary of the invention

[0007] In view of this, the present invention provides a spinneret assembly and an installation method thereof, and a method for preparing polyacrylonitrile fiber, the main purpose of which is to improve the uniformity of the discharge of the spinneret assembly.

[0008] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0009] On the one hand, an embodiment of the present invention provides a spinneret assembly, wherein the spinneret assembly comprises:

[0010] Spinneret;

[0011] A distribution plate, located upstream of the spinneret, for distributing the spinning solution so that the spinning solution passes through each spinneret hole on the spinneret;

[0012] A filter assembly, the filter assembly comprising a primary filter structure, a secondary filter structure and a tertiary filter structure;

[0013] Wherein, the secondary filtering structure is installed at an upstream position of the distribution plate;

[0014] The primary filter structure is installed at an upstream position of the secondary filter structure, and the filtering accuracy of the secondary filter structure is greater than the filtering accuracy of the primary filter structure;

[0015] The three-stage filter structure is installed at a downstream position of the distribution plate and an upstream position of the spinneret; wherein the filtering accuracy of the three-stage filter structure is greater than the filtering accuracy of the two-stage filter structure.

[0016] Preferably, the filtration accuracy of the filtration structure and the diameter of the spinneret holes on the spinneret plate need to meet the following conditions:

[0017] a1=15000×k1 / b1;

[0018] Wherein, a1 represents the mesh number of the filter structure; b1 represents the diameter of the spinneret hole, in μm; k1 is a constant;

[0019] Wherein, when the filtering structure is a primary filtering structure, k1 is 1-6;

[0020] When the filtration structure is a two-stage filtration structure, k1 is 7-13;

[0021] When the filtering structure is a three-stage filtering structure, k1 is 14-20.

[0022] Preferably, the filtering accuracy of the filtering structure and the aperture of the distribution plate need to meet the following conditions:

[0023] a2=150000×k2 / b2;

[0024] Wherein, a2 represents the mesh number of the filter structure; b2 represents the pore size of the distribution plate, in μm; k2 is a constant;

[0025] Wherein, when the filtering structure is a primary filtering structure, k2 is 2-10;

[0026] When the filtration structure is a two-stage filtration structure, k2 is 12-20;

[0027] When the filtering structure is a three-stage filtering structure, the k2 number is 22-30.

[0028] Preferably, the mesh number of the primary filter structure is 100-800 meshes; and / or the mesh number of the secondary filter structure is 900-1600 meshes; and / or the mesh number of the tertiary filter structure is 1700-2400 meshes. The pore size of the distribution plate is 2000-5000 μm; and / or the pore size of the spinneret holes on the spinneret is 120-150 μm.

[0029] Preferably, the porosity of the distribution plate is ≥40%; and / or the pressure resistance of the distribution plate is ≥50 kg.

[0030] Preferably, the spinneret assembly further comprises:

[0031] A support ring, wherein the primary filter structure, the secondary filter structure, the distribution plate, the tertiary filter structure, and the spinneret are all in contact with the inner wall of the support ring;

[0032] A funnel-shaped feeding structure, one end of which is a bell mouth, and the other end is a feeding pipe for connecting a feeding pipeline, and the bell mouth is connected to the feeding pipe; wherein the bell mouth extends into the support ring and abuts against the inner wall of the support ring, and the feeding pipe is located outside the support ring; wherein the bell mouth is located at the upstream position of the primary filtering structure;

[0033] A nut, the nut is connected to the support ring and is used to fix the bell mouth of the funnel-shaped feeding structure, the primary filtering structure, the secondary filtering structure, the distribution plate, the tertiary filtering structure, and the spinneret on the support ring;

[0034] Preferably, a circle of platforms is provided at the bottom of the support ring; wherein the spinneret is placed on the platform;

[0035] Preferably, the inner side wall at the upper end of the support ring is provided with a thread for fastening with the nut.

[0036] Preferably, the spinneret assembly further comprises a first gasket, wherein the first gasket is installed at a position between the bell mouth of the funnel-shaped feeding structure and the primary filtering structure; and / or the spinneret assembly further comprises a second gasket, wherein the second gasket is installed at a position between the distribution plate and the tertiary filtering structure.

[0037] Preferably, the spinneret assembly is a spinneret assembly for preparing polyacrylonitrile fibers.

[0038] On the other hand, an embodiment of the present invention further provides a method for installing the above-mentioned spinneret assembly, wherein the installation method comprises the following steps:

[0039] Step 1): placing the components of the spinneret assembly in a solvent for soaking treatment; wherein the solvent is consistent with the solvent in the spinning solution; wherein the components include: a spinneret, a distribution plate, a primary filtering structure, a secondary filtering structure and a tertiary filtering structure, and preferably also include: a support ring, a funnel-shaped feeding structure and a nut;

[0040] Step 2): After assembling the components of the spinning assembly, install them on the line;

[0041] Preferably, in step 1), the soaking treatment time is 10-20 minutes;

[0042] Preferably, in the step 2), the assembling step comprises: placing the spinneret, the three-stage filtering structure, the second gasket, the distribution plate, the secondary filtering structure, the primary filtering structure, the first gasket, the bell mouth of the funnel-shaped feeding structure, and the nut in the order from downstream to upstream in the support ring on the jack; and then tightening the nut to fix it;

[0043] Preferably, in the step 2), before the spinneret assembly is installed online, the metering pump needs to be turned on to discharge the material from the feed pipeline until the discharge meets the set conditions, and then the metering pump is turned off, and then the spinneret assembly is installed online; preferably, the set conditions include: there are no bubbles or material blocks in the discharged liquid, and the discharge is continuous and stable;

[0044] Preferably, in the step 2), after the spinneret assembly is installed online, after the feed liquid is ejected from the spinneret assembly, the spinneret assembly needs to be rotated to observe whether the spinning is continuous. If the spinning is continuous, the installation is completed.

[0045] In another aspect, an embodiment of the present invention provides a method for preparing polyacrylonitrile fiber, wherein the method for preparing polyacrylonitrile fiber comprises the following steps:

[0046] Spinning and coagulation forming step: extruding the polyacrylonitrile spinning solution through the spinneret assembly and then entering the coagulation bath for coagulation treatment to obtain primary fibers; wherein the spinneret assembly is any one of the spinnerets described above;

[0047] Post-processing step: post-processing the as-spun fibers to obtain polyacrylonitrile fibers;

[0048] Preferably, the post-treatment includes water washing, hot water drawing, oiling, drying and densification, steam drawing, and winding;

[0049] Preferably, before the spinning and solidification steps, the method further comprises:

[0050] Spinning assembly installation steps: Use the above-mentioned spinning assembly installation method to install.

[0051] Compared with the prior art, the spinneret assembly and installation method thereof, and the method for preparing polyacrylonitrile fiber of the present invention have at least the following beneficial effects:

[0052] The present embodiment provides a spinneret assembly, by sequentially arranging a primary filtering structure and a secondary filtering structure at the upstream position of a distribution plate, and simultaneously arranging a tertiary filtering structure at the upstream position of a spinneret, and increasing the filtering accuracy of the primary filtering, the secondary filtering, and the tertiary filtering in sequence, such an arrangement, on the basis of achieving uniform distribution of the distribution plate, further improves the uniformity of the discharge of the spinneret holes on the spinneret, avoids clogging of the spinneret holes, enables the spinning liquid to be extruded through the spinneret holes evenly and stably, and thus can improve the uniformity of the polyacrylonitrile fiber.

[0053] Furthermore, a spinneret assembly provided in an embodiment of the present invention mainly comprises: a support ring, and a plurality of components installed in the support ring, wherein these components are, from downstream to upstream (from the spinneret end to the feed end), a spinneret plate, a three-stage filter structure, a second gasket, a distribution plate, a secondary filter structure, a primary filter structure and a first gasket, a bell mouth of a funnel-shaped feed structure, and a nut. Through the above design, the uniformity of the spinning of the spinneret assembly can be improved, and problems such as leakage, blockage, uneven and discontinuous spinning of the spinneret assembly can be avoided, thereby ensuring the continuity of the spinning process.

[0054] On the other hand, an embodiment of the present invention further provides an installation method for the above-mentioned spinneret assembly. Specifically, before assembling the components of the spinneret assembly, the components are first placed in a solvent for soaking treatment, and the solvent is consistent with the solvent type in the spinning solution. This can avoid the phenomenon of uneven distribution of the spinning solution after it enters the spinneret assembly due to the relatively dry components. This operation in this embodiment can further improve the uniformity of spinning.

[0055] Furthermore, before the spinneret assembly is installed online, the metering pump needs to be turned on to discharge the material from the feed pipeline until the discharge meets the set conditions, and then the metering pump is turned off, and then the spinneret assembly is installed online; preferably, the set conditions include: there are no bubbles and material blocks in the discharged liquid, the liquid is discharged continuously and stably, and preferably also includes uniform color of the discharged material. It should be noted that the above design can avoid the phenomenon of bubbles and gel during the spinning process.

[0056] On the other hand, a method for preparing polyacrylonitrile fiber provided by an embodiment of the present invention adopts the above-mentioned spinneret assembly, and preferably also adopts the above-mentioned method for installing the spinneret assembly, so as to avoid problems such as leakage, blockage, uneven and discontinuous spinning of the spinneret assembly, ensure the continuity of the spinning process, reduce broken fibers caused by discontinuous spinning, avoid shutdowns and plate changes caused by leakage, improve production efficiency, and make the spinning liquid evenly and stably extruded through the spinneret holes to form primary fibers with uniform thickness and smooth surface, reduce defects such as fiber breakage and fuzz, and improve fiber strength, modulus and other performance indicators.

[0057] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a schematic structural diagram of a spinneret assembly provided by an embodiment of the present invention;

[0059] Figure 2 It is another structural schematic diagram of a spinneret assembly provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0060] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0061] Example 1

[0062] On the one hand, this embodiment provides a spinning assembly; wherein, Figure 1 and Figure 2As shown, the spinneret assembly described in this embodiment includes: a spinneret 8, a distribution plate 5, and a filter assembly. The distribution plate 5 is located at the upstream position of the spinneret 8 to distribute the spinning solution to each spinneret hole on the spinneret 8. The filter assembly includes a primary filter structure 3, a secondary filter structure 4, and a tertiary filter structure 7. The secondary filter structure 4 is installed at the upstream position of the distribution plate 5. The primary filter structure 3 is installed at the upstream position of the secondary filter structure 4, and the filtering accuracy of the secondary filter structure 4 is greater than the filtering accuracy of the primary filter structure 3. The tertiary filter structure 7 is installed at the downstream position of the distribution plate 5 and the upstream position of the spinneret 8; wherein, the filtering accuracy of the tertiary filter structure 7 is greater than the filtering accuracy of the secondary filter structure 5.

[0063] Here, this embodiment provides a spinneret assembly. On the one hand, by sequentially setting a primary filtering structure 3 and a secondary filtering structure 4 at the upstream position of the distribution plate 5, on the basis of achieving impurity removal, it can also avoid the phenomenon of "more in the middle and less on both sides" when the material passes through the distribution plate (this phenomenon leads to uneven distribution and is prone to blockage); on the other hand, a three-stage filtering structure is set at the upstream position of the spinneret 8, on the basis of impurity removal, the spinneret discharges the material evenly and avoids the phenomenon of "more in the middle and less on both sides"; on the other hand, the filtering accuracy of the primary filtration, the secondary filtration, and the tertiary filtration is increased in turn, further improving the uniformity of the discharge. Through the coordinated setting of the above three aspects, on the basis of achieving uniform distribution of the distribution plate, the uniformity of the discharge of the spinneret holes on the spinneret is further improved, the blockage of the spinneret holes is avoided, and the spinning liquid can be extruded through the spinneret holes evenly and stably, thereby improving the uniformity of the polyacrylonitrile fiber.

[0064] Preferably, the spinneret assembly of this embodiment and the following embodiments is a spinneret assembly for preparing polyacrylonitrile fibers.

[0065] Preferably, the primary filtering structure, the secondary filtering structure, and the tertiary filtering structure in this embodiment and the following embodiments are all filter nets.

[0066] Preferably, in this embodiment and the following embodiments: the porosity of the distribution plate is ≥40%, and the pressure resistance of the distribution plate is ≥50 kg. By setting it in this way, the distribution plate can match the filtering structure; and if the porosity of the distribution plate is too large, it is easy to have insufficient pressure resistance, and if the porosity of the distribution plate is too small, the filtering accuracy is too high, the material discharging resistance is large, and the spinneret assembly is easy to leak or the spinneret is deformed.

[0067] Example 2

[0068] Preferably, this embodiment provides a spinneret assembly. Compared with the previous embodiment, this embodiment is further designed as follows:

[0069] In this embodiment, the filtering accuracy of the primary filtering structure, the secondary filtering structure, and the tertiary filtering structure are matched with the aperture of the distribution plate and the aperture of the spinneret to further improve the distribution uniformity of the distribution plate and the spinning uniformity of the spinneret. The details are as follows:

[0070] First, the filtration accuracy of the filtration structure and the diameter of the spinneret holes on the spinneret plate must meet the following conditions:

[0071] a1=15000×k1 / b1;

[0072] Wherein, a1 represents the mesh number of the filter structure; b1 represents the diameter of the spinneret hole, in μm; k1 is a constant;

[0073] Wherein, when the filtering structure is a primary filtering structure, k1 is 1-6;

[0074] When the filtration structure is a two-stage filtration structure, k1 is 7-13;

[0075] When the filtering structure is a three-stage filtering structure, k1 is 14-20.

[0076] Second, the filtering accuracy of the filtering structure and the aperture of the distribution plate must meet the following conditions:

[0077] a2=150000×k2 / b2;

[0078] Wherein, a2 represents the mesh number of the filter structure; b2 represents the pore size of the distribution plate, in μm; k2 is a constant;

[0079] Wherein, when the filtering structure is a primary filtering structure, k2 is 2-10;

[0080] When the filtration structure is a two-stage filtration structure, k2 is 12-20;

[0081] When the filtering structure is a three-stage filtering structure, the k2 number is 22-30.

[0082] Preferably, the filter mesh number of the primary filter structure of the present embodiment is 100-800 meshes; the filter mesh number of the secondary filter structure is 900-1600 meshes. Preferably, the filter mesh number of the tertiary filter structure of the present embodiment is 1700-2400 meshes. Preferably, the aperture of the distribution plate is 2000-5000μm, and the aperture of the spinneret hole on the spinneret is 120-150μm. The matching of the aperture of the distribution plate, the aperture of the spinneret hole and the filter mesh number of the filter structure is designed by comprehensively considering the pressure of the spinneret and the distribution plate (to prevent excessive pressure, spinneret bulging and deformation, or leakage during operation affecting stable operation and requiring plate replacement) and filtering uniformity; among them, if the filter mesh number is too large, it is easy to have high pressure during operation; if the filter mesh number is too small, it will not have a filtering effect, impurities or gels are easy to block the spinneret hole, resulting in too small indicators such as linear density, and it is also easy to cause material blocks and hair balls to wrap around the roller during the process.

[0083] Example 3

[0084] Preferably, this embodiment provides a spinneret assembly. Compared with the above embodiment, this embodiment is further designed as follows:

[0085] like Figure 1 and Figure 2 As shown, the spinneret assembly of this embodiment also includes a support ring 9, a funnel-shaped feeding structure, and a nut 10. Among them, the primary filtering structure 3, the secondary filtering structure 4, the distribution plate 5, the tertiary filtering structure 7, and the spinneret 8 are all in contact with the inner wall of the support ring 9. One end of the funnel-shaped feeding structure is a bell mouth 12, and the other end is a feeding pipe 11 for connecting the feeding pipeline; wherein the bell mouth 12 extends into the support ring 9 and abuts against the inner wall of the support ring 9, and the feeding pipe 11 is located outside the support ring 9; wherein the bell mouth 12 is located at the upstream position of the primary filtering structure 3. The nut 10 is connected to the support ring 9 (the nut 10 is located above the bell mouth 12), and is used to fix the bell mouth 12 of the funnel-shaped feeding structure, the primary filtering structure 3, the secondary filtering structure 4, the distribution plate 5, the tertiary filtering structure 7, and the spinneret 8 in the support ring 9.

[0086] Preferably, the spinneret assembly further comprises a first gasket 2 ; wherein the first gasket 2 is installed at a position between the bell mouth 12 of the funnel-shaped feeding structure and the primary filtering structure 3 .

[0087] Preferably, the spinning assembly further comprises a second gasket 6 ; wherein the second gasket 6 is installed at a position between the distribution plate 5 and the tertiary filtering structure 7 .

[0088] Here, the first gasket and the second gasket are designed mainly to seal and fix the filter structure, the distribution plate, and the bell mouth.

[0089] Preferably, a circle of platform is provided at the bottom of the support ring 9, the spinneret 8 is placed on the platform, and then the tertiary filter structure 7 is placed on the spinneret 8; the second gasket 6 is placed on the tertiary filter structure 7; the distribution plate 5 is placed on the second gasket 6; the secondary filter structure 4 is placed on the distribution plate 5; the primary filter structure 3 is placed on the secondary filter structure 4; the first gasket 2 is placed on the primary filter structure 3; the bell mouth 12 is placed on the first gasket 2.

[0090] Preferably, a thread is provided on the inner wall of the upper end of the support ring 9 to fasten the nut 10 so as to fix the bell mouth 12 of the funnel-shaped feeding structure, the primary filtering structure 3, the secondary filtering structure 4, the distribution plate 5, the tertiary filtering structure 7, and the spinneret 8 in the support ring 9.

[0091] In summary, the spinneret assembly provided by the above embodiment of the present invention mainly comprises: a support ring 9, and a plurality of components installed in the support ring 9, which are, from downstream to upstream (from the spinneret end to the feed end), a spinneret plate 8, a three-stage filter structure 7, a second gasket 6, a distribution plate 5, a two-stage filter structure 4, a primary filter structure 3 and a first gasket 2, a bell mouth 12 of a funnel-shaped feed structure, and a nut 10. Through the above design, the uniformity of the spinning of the spinneret assembly can be improved, and problems such as leakage, blockage, uneven and discontinuous spinning of the spinneret assembly can be avoided, thereby ensuring the continuity of the spinning process.

[0092] Example 4

[0093] On the other hand, an embodiment of the present invention provides a method for installing the spinneret assembly described in the above embodiment, wherein the installation method comprises the following steps:

[0094] Step 1): placing the components of the spinneret assembly in a solvent for soaking treatment; wherein the solvent is consistent with the solvent in the spinning solution; wherein the components include: a spinneret, a distribution plate, a primary filtering structure, a secondary filtering structure and a tertiary filtering structure, and preferably also include: a support ring, a funnel-shaped feeding structure and a nut;

[0095] Step 2): After assembling the components of the spinning assembly, install them online.

[0096] Here, in the installation method of the spinneret assembly provided in this embodiment, before assembling the components of the spinneret assembly, the components are first placed in a solvent for soaking treatment (the soaking treatment time is 10-20 minutes), and the solvent is consistent with the solvent type in the spinning solution. This can avoid the phenomenon of uneven distribution of the spinning solution after it enters the spinneret assembly due to the relatively dry components. This operation in this embodiment can further improve the uniformity of spinning.

[0097] Preferably, in step 2), the assembly step includes placing the spinneret, the three-stage filter structure, the second gasket, the distribution plate, the secondary filter structure, the primary filter structure, the first gasket, the bell mouth of the funnel-shaped feed structure, and the nut in the order from downstream to upstream in the support ring on the jack; then tighten the nut to fix it. It should be noted that the purpose of placing it on the jack is to make the spinneret assembly evenly stressed during assembly, ensure uniform discharge, and be able to tighten to avoid leakage. After all the components are placed, the crossbeam above the jack is pressed down to compress the components, and then the nut is tightened with a handle (the nut is provided with a hole that cooperates with the handle), which can ensure that the component is evenly stressed 360° to avoid leakage or uneven discharge.

[0098] Preferably, before the spinneret assembly is installed online: the metering pump needs to be turned on to discharge the material from the feed pipeline until the discharge meets the set conditions, then the metering pump is turned off, and then the spinneret assembly is installed online; preferably, the set conditions include: there are no bubbles and material blocks in the discharged liquid, the liquid is discharged continuously and stably, and preferably also includes uniform color of the discharged material. It should be noted here that the above design can avoid the phenomenon of bubbles and gel during the spinning process.

[0099] Preferably, after the spinneret assembly is installed online, after the feed liquid is ejected from the spinneret assembly, the spinneret assembly needs to be rotated 360 degrees to observe whether the spinning is continuous. If the spinning is continuous, the installation is completed.

[0100] Example 5

[0101] On the other hand, the present embodiment provides a method for preparing polyacrylonitrile fiber, wherein the method for preparing polyacrylonitrile fiber comprises the following steps:

[0102] Spinning and coagulation forming step: extruding the polyacrylonitrile spinning solution through the spinneret assembly and then entering the coagulation bath for coagulation treatment to obtain primary fibers; wherein the spinneret assembly is any one of the spinnerets described above;

[0103] Post-processing step: post-processing the as-spun fibers to obtain polyacrylonitrile fibers;

[0104] Preferably, the post-treatment includes water washing, hot water drawing, oiling, drying and densification, steam drawing, and winding;

[0105] Preferably, before the spinning and solidification steps, the method further comprises:

[0106] Spinning assembly installation steps: adopt the above-mentioned spinning assembly installation method to assemble the spinning assembly, and install the assembled spinning assembly on-line.

[0107] It should be noted here that the method for preparing polyacrylonitrile fiber provided in this embodiment adopts the above-mentioned spinneret assembly and preferably also adopts the above-mentioned method for installing the spinneret assembly, so as to avoid problems such as leakage, blockage, uneven and discontinuous spinning of the spinneret assembly, ensure the continuity of the spinning process, reduce broken fibers caused by discontinuous spinning, avoid shutdowns and plate changes caused by leakage, improve production efficiency, make the spinning liquid evenly and stably extruded through the spinneret holes, form primary fibers with uniform thickness and smooth surface, reduce defects such as fiber breakage and fuzz, and improve fiber strength, modulus and other performance indicators.

[0108] The following is further described by experimental examples:

[0109] Experimental Example 1

[0110] This experimental example provides a method for preparing polyacrylonitrile fiber, which mainly includes the following steps:

[0111] 1) Spinning assembly installation steps: Figure 1 and Figure 2 As shown, the spinneret assembly of the embodiment of the present invention is adopted. Specifically, the spinneret assembly mainly includes: a support ring 9, and a plurality of components installed in the support ring 9, and these components are, from downstream to upstream (from the spinneret end to the feed end), a spinneret plate 8, a three-stage filter structure 7, a second gasket 6, a distribution plate 5, a secondary filter structure 4, a primary filter structure 3 and a first gasket 2, a bell mouth 12 of a funnel-shaped feed structure, and a nut 10.

[0112] The mesh number of the primary filter structure is 200 mesh, the mesh number of the secondary filter structure is 1200 mesh, and the mesh number of the tertiary filter structure is 1700 mesh. The distribution plate is a perforated plate with a pressure resistance of 80 kg and a porosity of 60%. The aperture of the spinneret on the spinneret is 130 μm, and the aperture of the distribution plate is 2500 μm.

[0113] Before assembly, the various components of the above spinneret assembly were soaked in dimethyl sulfoxide (soaking time was 20 minutes). Then, assembly was performed. Specifically, the spinneret, the three-stage filtering structure, the second gasket, the distribution plate, the secondary filtering structure, the primary filtering structure, the first gasket, the bell mouth of the funnel-shaped feeding structure, and the nut were placed in the support ring on the jack in order from downstream to upstream, and the pressure was raised to 70 kg; then the nut was tightened clockwise with a handle to fix it.

[0114] Before the spinneret assembly is installed online, the metering pump is turned on to discharge the material until there are no bubbles or lumps in the liquid. After the liquid is discharged continuously and stably and the color is uniform, the metering pump is turned off, and the spinneret assembly is connected and installed (the feed pipe of the funnel-shaped feed structure in the spinneret assembly is connected to the feed pipeline and fixed), and then the metering pump is turned on. After the liquid is ejected from the spinneret assembly, the spinneret assembly is rotated 360 degrees to observe that the spinning is continuous and uniform, which means that the installation is completed and spinning (i.e., spinning and coagulation molding steps) is carried out.

[0115] 2) Spinning and coagulation step: The polyacrylonitrile spinning solution (solid content of 20% and falling ball viscosity of 100 Pa.s) is extruded through the spinneret assembly and then enters a coagulation bath (the temperature of the coagulation bath is 5° C. and the concentration of the coagulation bath liquid is 35%) for coagulation treatment to obtain primary fibers.

[0116] 3) Post-treatment steps: The spun fibers are sequentially washed with water (washing temperature is 40°C), drawn with hot water (the temperature of the hot water drawing is 80°C), oiled (the concentration of the oil is 2.5%), dried and densified (the temperature of the drying and densification is 100-150°C), steam drawn (the pressure of the steam drawing is 0.5MPa), and wound (the winding speed is 300m / min) to obtain polyacrylonitrile fibers.

[0117] Here, the polyacrylonitrile fiber of this embodiment has a smooth surface, no fuzzy or broken fibers, a strength of 780 MPa, and a modulus of 16 GPa.

[0118] Experimental Example 2

[0119] This experimental example provides a method for preparing polyacrylonitrile fiber, which mainly includes the following steps:

[0120] 1) Spinning assembly installation steps: Figure 1 and Figure 2 As shown, the spinneret assembly of the embodiment of the present invention is adopted. Specifically, the spinneret assembly mainly includes: a support ring 9, and a plurality of components installed in the support ring 9, and these components are, from downstream to upstream (from the spinneret end to the feed end), a spinneret plate 8, a three-stage filter structure 7, a second gasket 6, a distribution plate 5, a secondary filter structure 4, a primary filter structure 3 and a first gasket 2, a bell mouth 12 of a funnel-shaped feed structure, and a nut 10.

[0121] The mesh number of the primary filter structure is 300 meshes, the mesh number of the secondary filter structure is 1000 meshes, and the mesh number of the tertiary filter structure is 2000 meshes. The distribution plate is a perforated plate with a pressure resistance of 100 kg and a porosity of 50%. The aperture of the spinneret on the spinneret is 110 μm, and the aperture of the distribution plate is 2000 μm.

[0122] Before assembly, the various components of the above spinneret assembly were soaked in dimethyl sulfoxide (the soaking time was 10 minutes). Then, the assembly was performed. Specifically, the spinneret, the three-stage filtering structure, the second gasket, the distribution plate, the secondary filtering structure, the primary filtering structure, the first gasket, the bell mouth of the funnel-shaped feeding structure, and the nut were placed in the support ring on the jack in order from downstream to upstream, and the pressure was raised to 60 kg; then the nut was tightened clockwise with a handle to fix it.

[0123] Before the spinneret assembly is installed online, the metering pump is turned on to discharge the material until there are no bubbles or lumps in the liquid. After the liquid is discharged continuously and stably and the color is uniform, the metering pump is turned off, and the spinneret assembly is connected and installed (the feed pipe of the funnel-shaped feed structure in the spinneret assembly is connected to the feed pipeline and fixed), and then the metering pump is turned on. After the liquid is ejected from the spinneret assembly, the spinneret assembly is rotated 360 degrees to observe that the spinning is continuous and uniform, which means that the installation is completed and spinning (i.e., spinning and coagulation molding steps) is carried out.

[0124] 2) Spinning and coagulation step: The polyacrylonitrile spinning solution (solid content of 21% and falling ball viscosity of 90 Pa.s) is extruded through the spinneret assembly and then enters a coagulation bath (the temperature of the coagulation bath is 4° C. and the concentration of the coagulation bath liquid is 32%) for coagulation treatment to obtain primary fibers.

[0125] 3) Post-treatment steps: The spun fibers are sequentially washed with water (washing temperature is 40°C), drawn with hot water (the temperature of the hot water drawing is 75°C), oiled (the concentration of the oil is 4%), dried and densified (the temperature of the drying and densification is 90-130°C), steam drawn (the pressure of the steam drawing is 0.4MPa), and wound (the winding speed is 280m / min) to obtain polyacrylonitrile fibers.

[0126] Here, the polyacrylonitrile fiber of this embodiment has a smooth surface, no fuzzy or broken fibers, a strength of 760 MPa, and a modulus of 15 GPa.

[0127] Experimental Example 3

[0128] This experimental example provides a method for preparing polyacrylonitrile fiber, which mainly includes the following steps:

[0129] 1) Spinning assembly installation steps: Figure 1 and Figure 2 As shown, the spinneret assembly of the embodiment of the present invention is adopted. Specifically, the spinneret assembly mainly includes: a support ring 9, and a plurality of components installed in the support ring 9, and these components are, from downstream to upstream (from the spinneret end to the feed end), a spinneret plate 8, a three-stage filter structure 7, a second gasket 6, a distribution plate 5, a secondary filter structure 4, a primary filter structure 3 and a first gasket 2, a bell mouth 12 of a funnel-shaped feed structure, and a nut 10.

[0130] The mesh number of the primary filter structure is 600 mesh, the mesh number of the secondary filter structure is 1200 mesh, and the mesh number of the tertiary filter structure is 1800 mesh. The distribution plate is a perforated plate with a pressure resistance of 80 kg and a porosity of 60%. The aperture of the spinneret on the spinneret is 120 μm, and the aperture of the distribution plate is 2500 μm.

[0131] Before assembly, the various components of the above spinneret assembly were soaked in dimethyl sulfoxide (soaking time was 10 minutes). Then, assembly was performed. Specifically, the spinneret, the three-stage filtering structure, the second gasket, the distribution plate, the secondary filtering structure, the primary filtering structure, the first gasket, the bell mouth of the funnel-shaped feeding structure, and the nut were placed in the support ring on the jack in order from downstream to upstream, and the pressure was raised to 80 kg; then the nut was tightened clockwise with a handle to fix it.

[0132] Before the spinneret assembly is installed online, the metering pump is turned on to discharge the material until there are no bubbles or lumps in the liquid. After the liquid is discharged continuously and stably and the color is uniform, the metering pump is turned off, and the spinneret assembly is connected and installed (the feed pipe of the funnel-shaped feed structure in the spinneret assembly is connected to the feed pipeline and fixed), and then the metering pump is turned on. After the liquid is ejected from the spinneret assembly, the spinneret assembly is rotated 360 degrees to observe that the spinning is continuous and uniform, which means that the installation is completed and spinning (i.e., spinning and coagulation molding steps) is carried out.

[0133] 2) Spinning and coagulation step: The polyacrylonitrile spinning solution (solid content of 20% and falling ball viscosity of 100 Pa.s) is extruded through the spinneret assembly and then enters a coagulation bath (the temperature of the coagulation bath is 5° C. and the concentration of the coagulation bath liquid is 35%) for coagulation treatment to obtain primary fibers.

[0134] 3) Post-treatment steps: The spun fibers are sequentially washed with water (washing temperature is 40°C), drawn with hot water (the temperature of the hot water drawing is 80°C), oiled (the concentration of the oil is 2.5%), dried and densified (the temperature of the drying and densification is 100-150°C), steam drawn (the pressure of the steam drawing is 0.5MPa), and wound (the winding speed is 300m / min) to obtain polyacrylonitrile fibers.

[0135] Here, the polyacrylonitrile fiber of this embodiment has a smooth surface, no fuzzy or broken fibers, a strength of 800 MPa, and a modulus of 16 GPa.

[0136] Experimental Example 4

[0137] This experimental example provides a method for preparing polyacrylonitrile fiber, which mainly includes the following steps:

[0138] 1) Spinning assembly installation steps: Figure 1 and Figure 2 As shown, the spinneret assembly of the embodiment of the present invention is adopted. Specifically, the spinneret assembly mainly includes: a support ring 9, and a plurality of components installed in the support ring 9, and these components are, from downstream to upstream (from the spinneret end to the feed end), a spinneret plate 8, a three-stage filter structure 7, a second gasket 6, a distribution plate 5, a secondary filter structure 4, a primary filter structure 3 and a first gasket 2, a bell mouth 12 of a funnel-shaped feed structure, and a nut 10.

[0139] The mesh number of the primary filter structure is 150 mesh, the mesh number of the secondary filter structure is 900 mesh, and the mesh number of the tertiary filter structure is 1700 mesh. The distribution plate is a perforated plate with a pressure resistance of 80 kg and a porosity of 62%. The aperture of the spinneret on the spinneret is 150 μm, and the aperture of the distribution plate is 2600 μm.

[0140] Before assembly, the various components of the above spinneret assembly were soaked in dimethyl sulfoxide (soaking time was 15 minutes). Then, assembly was performed. Specifically, the spinneret, the three-stage filtering structure, the second gasket, the distribution plate, the secondary filtering structure, the primary filtering structure, the first gasket, the bell mouth of the funnel-shaped feeding structure, and the nut were placed in the support ring on the jack in order from downstream to upstream, and the pressure was raised to 70 kg; then the nut was tightened clockwise with a handle to fix it.

[0141] Before the spinneret assembly is installed online, the metering pump is turned on to discharge the material until there are no bubbles or lumps in the liquid. After the liquid is discharged continuously and stably and the color is uniform, the metering pump is turned off, and the spinneret assembly is connected and installed (the feed pipe of the funnel-shaped feed structure in the spinneret assembly is connected to the feed pipeline and fixed), and then the metering pump is turned on. After the liquid is ejected from the spinneret assembly, the spinneret assembly is rotated 360 degrees to observe that the spinning is continuous and uniform, which means that the installation is completed and spinning (i.e., spinning and coagulation molding steps) is carried out.

[0142] 2) Spinning and coagulation step: The polyacrylonitrile spinning solution (solid content of 20% and falling ball viscosity of 100 Pa.s) is extruded through the spinneret assembly and then enters a coagulation bath (the temperature of the coagulation bath is 4° C. and the concentration of the coagulation bath liquid is 32%) for coagulation treatment to obtain primary fibers.

[0143] 3) Post-treatment steps: The spun fibers are sequentially washed (washing temperature is 40°C), hot water stretched (hot water stretched temperature is 75°C), oiled (the oiling concentration is 5%), dried and densified (drying and densifying temperature is 100-150°C), steam stretched (steam stretched pressure is 0.5MPa), and wound (winding speed is 300m / min) to obtain polyacrylonitrile fibers.

[0144] Here, the polyacrylonitrile fiber of this embodiment has a smooth surface, no fuzzy or broken fibers, a strength of 790 MPa, and a modulus of 15 GPa.

[0145] Comparative Example 1

[0146] Comparative Example 1 provides a method for preparing polyacrylonitrile fiber, which has the following differences compared with Experimental Example 1:

[0147] (1) The spinneret assembly in Comparative Example 1 does not have a three-stage filtering structure, and other structures are consistent with those in Example 1.

[0148] (2) During the installation step of the spin pack, the components of the spin pack are not wetted.

[0149] The other steps are the same.

[0150] Here, in Comparative Example 1, there is a problem of discontinuous spinning at the extrusion point of the spinneret during the spinning process, resulting in broken fibers, and the fiber finally prepared has hairy fibers and broken ends on the surface.

[0151] Comparative Example 2

[0152] Comparative Example 2 provides a method for preparing polyacrylonitrile fiber, which has the following differences compared with Experimental Example 1:

[0153] In the spinneret assembly in Comparative Example 2, the mesh sizes of the primary filtering structure, the secondary filtering structure, and the tertiary filtering structure are 50 mesh, 3000 mesh, and 3000 mesh, respectively.

[0154] The other steps are the same.

[0155] Here, since the filtering structure of Comparative Example 2 does not match the aperture of the spinneret holes and the aperture of the distribution plate, during the spinning process of Comparative Example 2, the material is extruded quickly at the spinneret and the spinneret is discontinuous, resulting in broken ends that are easy to entangle with the rollers. In addition, the spinneret pressure is high, the spinneret operation is unstable, and the fiber finally prepared has hairy fibers and broken ends on the surface.

[0156] Comparative Example 3

[0157] Comparative Example 3 provides a method for preparing polyacrylonitrile fiber, which has the following differences compared with Experimental Example 1:

[0158] In Comparative Example 3, during the installation step of the spinning assembly, the various components of the spinning assembly were not wetted.

[0159] Here, in Comparative Example 3, since the components of the spinneret assembly were not soaked during the installation step of the spinneret assembly, the material was locally discontinuous during the spinning process, resulting in fuzzy fibers, and the fibers finally prepared had fuzzy fibers.

[0160] In summary, the embodiments of the present invention provide a spinneret assembly and an installation method thereof, and a method for preparing polyacrylonitrile fiber. Through the design of the spinneret assembly structure (such as the design of the installation sequence of the filtering structure, the distribution plate and the spinneret plate) and the design of the spinneret assembly installation method, problems such as leakage, blockage, uneven and discontinuous spinning of the spinneret assembly can be avoided, the continuity of the spinning process can be ensured, the breakage of the yarn due to discontinuous spinning can be reduced, the shutdown for plate replacement due to leakage can be avoided, the production efficiency can be improved, the spinning liquid can be extruded evenly and stably through the spinneret hole, and primary fibers with uniform thickness and smooth surface can be formed, defects such as fiber breakage and hairy fibers can be reduced, and the performance indicators such as fiber strength and modulus can be improved.

[0161] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A spinning assembly, characterized in that: The spinneret assembly comprises: Spinneret; A distribution plate, located upstream of the spinneret, for distributing the spinning solution so that the spinning solution passes through each spinneret hole on the spinneret; A filter assembly, the filter assembly comprising a primary filter structure, a secondary filter structure and a tertiary filter structure; Wherein, the secondary filtering structure is installed at an upstream position of the distribution plate; The primary filter structure is installed at an upstream position of the secondary filter structure, and the filtering accuracy of the secondary filter structure is greater than the filtering accuracy of the primary filter structure; The three-stage filter structure is installed at a downstream position of the distribution plate and an upstream position of the spinneret; wherein the filtering accuracy of the three-stage filter structure is greater than the filtering accuracy of the two-stage filter structure.

2. The spinneret assembly according to claim 1, characterized in that The filtration accuracy of the filtration structure and the diameter of the spinneret holes on the spinneret plate must meet the following conditions: a1=15000×k1 / b1; Wherein, a1 represents the mesh number of the filter structure; b1 represents the diameter of the spinneret hole, in μm; k1 is a constant; Wherein, when the filtering structure is a primary filtering structure, k1 is 1-6; When the filtration structure is a two-stage filtration structure, k1 is 7-13; When the filtering structure is a three-stage filtering structure, k1 is 14-20.

3. The spinneret assembly according to claim 1, characterized in that The filtering accuracy of the filtering structure and the aperture of the distribution plate must meet the following conditions: a2=150000×k2 / b2; Wherein, a2 represents the mesh number of the filter structure; b2 represents the pore size of the distribution plate, in μm; k2 is a constant; Wherein, when the filtering structure is a primary filtering structure, k2 is 2-10; When the filtration structure is a two-stage filtration structure, k2 is 12-20; When the filtering structure is a three-stage filtering structure, the k2 number is 22-30.

4. The spinning assembly according to any one of claims 1 to 3, characterized in that: The filtering mesh number of the primary filtering structure is 100 to 800 meshes; and / or The filtering mesh number of the secondary filtering structure is 900 to 1600 mesh; and / or The filtration mesh number of the three-stage filtration structure is 1700-2400 mesh; and / or The pore size of the distribution plate is 2000-5000 μm; and / or The diameter of the spinneret holes on the spinneret plate is 120-150 μm.

5. The spinning assembly according to any one of claims 1 to 3, characterized in that: The porosity of the distribution plate is ≥ 40%; and / or The distribution plate has a pressure resistance of ≥50 kg.

6. The spinning assembly according to any one of claims 1 to 5, characterized in that: The spinneret assembly also includes: A support ring, wherein the primary filter structure, the secondary filter structure, the distribution plate, the tertiary filter structure, and the spinneret are all in contact with the inner wall of the support ring; A funnel-shaped feeding structure, one end of which is a bell mouth, and the other end is a feeding pipe for connecting a feeding pipeline, and the bell mouth is connected to the feeding pipe; wherein the bell mouth extends into the support ring and abuts against the inner wall of the support ring, and the feeding pipe is located outside the support ring; wherein the bell mouth is located at the upstream position of the primary filtering structure; A nut, the nut is connected to the support ring and is used to fix the bell mouth of the funnel-shaped feeding structure, the primary filtering structure, the secondary filtering structure, the distribution plate, the tertiary filtering structure, and the spinneret on the support ring; Preferably, a circle of platforms is provided at the bottom of the support ring; wherein the spinneret is placed on the platform; Preferably, the inner side wall at the upper end of the support ring is provided with a thread for fastening with the nut.

7. The spinneret assembly according to claim 6, characterized in that The spinneret assembly further comprises a first gasket; wherein the first gasket is installed at a position between the bell mouth of the funnel-shaped feeding structure and the primary filtering structure; and / or The spinning assembly further includes a second gasket; wherein the second gasket is installed at a position between the distribution plate and the three-stage filtering structure.

8. The spinning assembly according to any one of claims 1 to 7, characterized in that: The spinneret assembly is a spinneret assembly for preparing polyacrylonitrile fibers.

9. The method for installing a spinning assembly according to any one of claims 1 to 8, characterized in that: The installation method comprises the following steps: Step 1): placing the components of the spinneret assembly in a solvent for soaking treatment; wherein the solvent is consistent with the solvent in the spinning solution; wherein the components include: a spinneret, a distribution plate, a primary filtering structure, a secondary filtering structure and a tertiary filtering structure, and preferably also include: a support ring, a funnel-shaped feeding structure and a nut; Step 2): After assembling the components of the spinning assembly, install them on the line; Preferably, in step 1), the soaking treatment time is 10-20 minutes; Preferably, in the step 2), the assembling step comprises: placing the spinneret, the three-stage filtering structure, the second gasket, the distribution plate, the secondary filtering structure, the primary filtering structure, the first gasket, the bell mouth of the funnel-shaped feeding structure, and the nut in the order from downstream to upstream in the support ring on the jack; and then tightening the nut to fix it; Preferably, in the step 2), before the spinneret assembly is installed online, the metering pump needs to be turned on to discharge the material from the feed pipeline until the discharge meets the set conditions, and then the metering pump is turned off, and then the spinneret assembly is installed online; preferably, the set conditions include: there are no bubbles or material blocks in the discharged liquid, and the discharge is continuous and stable; Preferably, in the step 2), after the spinneret assembly is installed online, after the feed liquid is ejected from the spinneret assembly, the spinneret assembly needs to be rotated to observe whether the spinning is continuous. If the spinning is continuous, the installation is completed.

10. A method for preparing polyacrylonitrile fiber, characterized in that: The preparation method of the polyacrylonitrile fiber comprises the following steps: Spinning and coagulation forming step: extruding the polyacrylonitrile spinning solution through the spinneret assembly and then entering the coagulation bath for coagulation treatment to obtain primary fibers; wherein the spinneret assembly is the spinneret assembly according to any one of claims 1 to 8; Post-processing step: post-processing the as-spun fibers to obtain polyacrylonitrile fibers; Preferably, the post-treatment includes water washing, hot water drawing, oiling, drying and densification, steam drawing, and winding; Preferably, before the spinning and solidification steps, the method further comprises: Spinning assembly installation step: installing by using the spinning assembly installation method described in claim 9.

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