CN116024676A - Preparation method of high-strength high-modulus carbon fiber precursor wet spinning - Google Patents
Preparation method of high-strength high-modulus carbon fiber precursor wet spinning Download PDFInfo
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Abstract
The invention belongs to the field of carbon fiber production processes, and particularly relates to a preparation method of high-strength high-modulus carbon fiber precursor wet spinning; the method comprises the steps of feeding spinning solution into a coagulation bath from a spinning assembly for molding, stretching at a certain multiplying power to obtain PAN primary fibers, and performing washing, hot water drafting, oiling, drying and compactness, saturated steam drafting, steam heat setting and drying treatment on the PAN primary fibers to obtain PAN primary fibers; pre-oxidizing PAN precursor, carbonizing at low temperature and carbonizing at high temperature, wherein the solution flow direction in the coagulating bath is divided into a direction along the filament bundle and a direction perpendicular to the filament bundle, and the solution along the filament bundle and the solution perpendicular to the filament bundle both act on the filament outlet position of the filament spraying assembly; according to the invention, the flow of the coagulating bath solution in the direction perpendicular to the filament bundles is additionally arranged at the filament spraying outlet, so that the dimethyl sulfoxide solvent coming out of the filament spraying assembly can be rapidly diffused, and each filament bundle is ensured to be in the same coagulating environment and the coagulating state is kept consistent.
Description
Technical Field
The invention belongs to the field of carbon fiber production processes, and particularly relates to a preparation method of high-strength high-modulus carbon fiber precursor wet spinning.
Background
The polyacrylonitrile carbon fiber and the composite material thereof have a series of excellent performances such as high specific strength, high specific modulus, high temperature resistance, corrosion resistance, fatigue resistance, creep resistance, conductivity, small heat transfer and thermal expansion coefficient, and the like, and are widely used in aerospace and civil industries.
In the prior art, a solution inlet and a solution outlet are arranged in a coagulating bath, the flow is controlled according to the temperature and the concentration of the solution, the coagulating bath is only used for guaranteeing the stability of the components and the temperature of the solution in the coagulating bath, when spinning stock solution comes out of a spinning component, dimethyl sulfoxide solvent is mixed in tows, the dimethyl sulfoxide solvent is gathered at the outlet of the spinning component, the environment of contact of each tow with the coagulating bath is different, the coagulating state of each tow is different, the solution inlet and outlet in the prior art are only used for replacing the solution in the coagulating bath, the flowing dimethyl sulfoxide solvent at the outlet of the spinning component cannot be timely diffused rapidly, the stability of the coagulating environment of each tow cannot be guaranteed, and the quality of the formed carbon fiber is affected.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention designs a preparation method of high-strength high-modulus carbon fiber precursor wet spinning, which can rapidly diffuse dimethyl sulfoxide solvent coming out of a spinning assembly by adding the flow of coagulating bath solution in the direction vertical to the filament bundle at a spinning outlet, thereby ensuring that each filament bundle is in the same coagulating environment and the coagulating state of each filament bundle is kept consistent.
The technical scheme of the invention is as follows:
the preparation method of the high-strength high-modulus carbon fiber precursor wet spinning comprises the steps of feeding spinning solution into a coagulation bath from a spinning assembly for molding, stretching at a certain multiplying power to obtain PAN primary fibers, and carrying out washing, hot water stretching, oiling, drying and compactness, saturated steam stretching, steam heat setting and drying treatment on the PAN primary fibers to obtain PAN precursor; and then pre-oxidizing, carbonizing at low temperature and carbonizing at high temperature the PAN precursor, which is characterized in that: the flow direction of the solution in the coagulating bath is divided into the direction along the filament bundle and the direction vertical to the filament bundle, and the solution along the filament bundle and the solution vertical to the filament bundle both act on the filament outlet position of the filament spraying assembly.
Further, the total flow rate Q of the solution of the coagulating bath is more than 5m 3 And/h, wherein the ratio of the flow along the direction of the filament bundle to the flow perpendicular to the direction of the filament bundle is 1.5:1-2.5:1.
Further, the concentration of the solution of the coagulating bath is 30-60 (wt)%, the temperature of the coagulating bath is 40-75 ℃, and the stretching ratio of the spray head assembly is 0.4-0.8 times.
Further, the device comprises a first temperature measuring point and a second temperature measuring point, wherein the first temperature measuring point is used for monitoring the temperature of the spinning solution; the second temperature measuring point is used for monitoring the temperature of the coagulating bath, and the temperature difference between the first temperature measuring point and the second temperature measuring point is less than 1 ℃.
Further, the number of holes of the spinning assembly is 12000-15000.
Further, the water washing temperature: 50-70 ℃,
heat traction temperature: stretching ratio at 70-98 ℃): 1.5-5.0;
oiling: organic silicone oil agent, oil concentration: 3.5-4.0%, target oil-up rate: 1.0-1.2%, oiling temperature: 20-40 ℃;
drying and densification: 100-130 ℃;
steam drafting: steam pressure: 0.1-0.3MPa, stretching multiplying power: 1.5-3.5;
steam heat setting: steam setting pressure: 0.1-0.2MPa, stretching multiplying power: 0.9-1.0;
and (3) drying: 100-120 ℃.
Further, the pre-oxidation temperature: 220-280 ℃, wherein the atmosphere is hot air, and the stretching multiplying power is as follows: 1.0,
low temperature carbonization temperature: 600-800 ℃, the atmosphere is nitrogen, and the stretching multiplying power is as follows: 1.02-1.08
High temperature carbonization temperature: 1300-1400 ℃, nitrogen is used as atmosphere, and the stretching multiplying power is as follows: 0.95-1.0.
Further, the concentration of the spinning solution is 15% -25%, the molecular weight of the polymer is 15-20 ten thousand, and the polymerized monomer composition of the spinning solution is as follows: AN and IA, the mass ratio is: 99.5:0.5.
In summary, the invention has the following beneficial effects:
1. the invention improves the preparation method of the carbon fiber precursor wet spinning, in particular to the improvement of the flow direction of the solution in the coagulating bath, and the flow direction and the action position of the solution in the coagulating bath are limited, so that the solution in the coagulating bath can pass through the filament outlet position of the filament spraying assembly along the filament bundle direction and the direction vertical to the filament bundle direction, namely the solution in the coagulating bath can rapidly take away the dimethyl sulfoxide solvent flowing out of the filament spraying assembly, the coagulation condition of each filament bundle is kept consistent in the same coagulation environment in the coagulation process of each filament bundle, and the performance of the prepared carbon fiber is improved.
2. The flow rate of the solution in the coagulating bath is further limited, and the flow rates along the direction of the filament bundles and the direction perpendicular to the filament bundles are optimized.
3. The concentration and the temperature of the coagulating bath are further limited, and the stretching ratio of the spray head of the spinning assembly is also limited.
4. The invention further detects the temperature of the spinning solution before spinning and the temperature of the coagulating bath after spinning, controls the temperature of the spinning solution before spinning and the temperature of the coagulating bath after spinning, and preferably controls the temperature difference between the spinning solution and the coagulating bath within less than 1 ℃, thereby reducing the problem of uneven heat transfer caused by inconsistent filament bundle temperature and coagulating temperature, and reducing the influence of inconsistent temperature on the uniformity of filament bundle coagulation.
Drawings
FIG. 1 is a schematic view of the coagulation bath according to the present invention;
in the figure, 1 is a spinning assembly, 2 is a filament bundle, and 3 is a coagulation bath.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
It will be understood that when an element is referred to as being "disposed" or "fixed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "fixedly disposed" on or "fixedly connected" to another element, it can be detachably or non-detachably fixed therebetween. When an element is referred to as being "connected," "rotatably connected," or "rotatably connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," "up," "down," and the like are used for illustration purposes only and are not meant to be the only embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The terms "first," "second," "third," and the like in this disclosure are used for descriptive purposes and not for describing particular amounts or sequences, but for distinguishing between similar names.
The preparation method of the high-strength high-modulus carbon fiber precursor wet spinning comprises the steps of feeding spinning solution into a coagulation bath from a spinning assembly for molding, stretching at a certain multiplying power to obtain PAN primary fibers, and carrying out washing, hot water stretching, oiling, drying and compactness, saturated steam stretching, steam heat setting and drying treatment on the PAN primary fibers to obtain PAN precursor; and then pre-oxidizing, carbonizing at low temperature and carbonizing at high temperature the PAN precursor, which is characterized in that: the invention improves the preparation method of carbon fiber precursor wet spinning, in the process of wet spinning, a spinning component 1 is immersed in the solution in a coagulating bath 3, specifically, the flow direction of the solution is limited in the coagulating bath, specifically, the solution is divided into the flow along the direction of the filament bundle and the flow perpendicular to the direction of the filament bundle, in the actual production process, the filament bundle coming out of the spinning component receives the action of drafting and has a certain inclination angle, and the direction along the filament bundle expressed herein is the direction of the filament bundle flowing out of the spinning component, and is combined with the schematic diagram of the invention, the direction perpendicular to the filament bundle direction is the direction of the filament bundle flowing out of the spinning component, and is combined with the schematic diagram of the invention; the solution flow mainly acts on the filament outlet position of the filament spraying assembly 1, particularly, the solution flow perpendicular to the filament bundle direction is carried with a large amount of dimethyl sulfoxide solvent in the filament spraying process of the filament spraying assembly, if the dimethyl sulfoxide solvent is easy to move forwards along with the filament bundles continuously, the solidification environment of the filament bundles at the central part of the filament spraying assembly is different from the solidification environment of the filament bundles at the periphery of the filament spraying assembly, the filament bundles are subjected to external force drafting in the filament spraying process, the difference between the filament bundles at the central part and the filament bundles at the periphery is further increased, the final forming quality of the carbon fiber bundles is influenced, so that the arranged solution perpendicular to the filament bundle direction can increase the movement of the solution at the outlet of the filament spraying assembly in the perpendicular direction, the dimethyl sulfoxide solvent diffused from the filament bundles can be rapidly taken away, the influence of the dimethyl sulfoxide solvent on the solidification of spinning stock solution is reduced, the solidification process of each filament bundle is ensured to be in the same solidification environment, the solidification state of each filament bundle is kept consistent, the subsequent carbon fiber production steps are further facilitated, and the carbon fiber with higher strength and higher modulus can be obtained.
Further, in the present embodiment, the flow rate of the solution in the coagulation bath is limited, and the flow rate distribution in different directions is limited, specifically, the total flow rate Q of the solution in the coagulation bath is more than 5m 3 And (h) diluting the dimethyl sulfoxide solvent flowing out of the spinning assembly by increasing the flow of the coagulating bath solution, so as to reduce the influence of the concentration of the dimethyl sulfoxide solvent on the coagulation of the filament bundle, and further, limiting the flow along the filament bundle direction and the flow perpendicular to the filament bundle direction within the ratio of 1.5:1-2.5:1, wherein the diffusion of the dimethyl sulfoxide is more uniform within the range of the ratio, and the coagulating forming process of the filament bundle is consistent, so that the fiber performance CV value of the obtained fiber is low.
Furthermore, the concentration of the solution in the coagulating bath is 30-60 (wt)%, the temperature of the coagulating bath is 40-75 ℃, the stretching ratio of the spray head component is 0.4-0.8 times, the concentration and the temperature of the solution in the coagulating bath are limited, the optimal coagulating condition is achieved through matching of the concentration and the temperature of the solution with the flow, and the coagulation of the tows caused by the change of the coagulating environment is not influenced while the rapid diffusion of the dimethyl sulfoxide solvent is accelerated.
The device comprises a first temperature measuring point and a second temperature measuring point, wherein the first temperature measuring point is used for monitoring the temperature of spinning solution; the second temperature measuring point is used for monitoring the temperature of the coagulating bath, the temperature difference between the first temperature measuring point and the second temperature measuring point is less than 1 ℃, the temperature of the spinning solution and the temperature of the coagulating bath are detected to control the temperature of the filament bundle and the temperature of the coagulating bath, the heat transfer non-uniformity caused by the inconsistent temperature of the filament bundle and the temperature of the coagulating is reduced, and the uniformity of the coagulation of the filament bundle is ensured.
The number of holes of the spinning assembly is 12000-15000, when the number of holes of the spinning assembly is larger, the distance between the spinning holes is smaller, the tows are denser, and the dimethyl sulfoxide solvent flowing out of the spinning holes at the central part is more difficult to diffuse, so that when the number of holes is larger than 12000, the dimethyl sulfoxide solvent at the central part can be better diffused by the additionally arranged flow of the coagulating bath solution perpendicular to the direction of the tows, and the consistency of the coagulating environment of each tow at the central part and the peripheral part is ensured.
The process parameters in the various steps of the subsequent carbon fiber production process steps are defined below for the tows obtained in the solidification environment described above,
further, the water washing temperature: 50-70 ℃,
heat traction temperature: stretching ratio at 70-98 ℃): 1.5-5.0;
oiling: organic silicone oil agent, oil concentration: 3.5-4.0%, target oil-up rate: 1.0-1.2%, oiling temperature: 20-40 ℃;
drying and densification: 100-130 ℃;
steam drafting: steam pressure: 0.1-0.3MPa, stretching multiplying power: 1.5-3.5;
steam heat setting: steam setting pressure: 0.1-0.2MPa, stretching multiplying power: 0.9-1.0;
and (3) drying: 100-120 ℃.
Further, the pre-oxidation temperature: 220-280 ℃, wherein the atmosphere is hot air, and the stretching multiplying power is as follows: 1.0,
low temperature carbonization temperature: 600-800 ℃, the atmosphere is nitrogen, and the stretching multiplying power is as follows: 1.02-1.08
High temperature carbonization temperature: 1300-1400 ℃, nitrogen is used as atmosphere, and the stretching multiplying power is as follows: 0.95-1.0.
Based on the technological parameters, the strength of the PAN-based carbon fiber obtained by production is more than or equal to 7.0GPa, the modulus is more than or equal to 330GPa, and the elongation at break is more than or equal to 2 percent.
Further, the concentration of the spinning solution is 15% -25%, the molecular weight of the polymer is 15-20 ten thousand, and the polymerized monomer composition of the spinning solution is as follows: AN and IA, the mass ratio is: 99.5:0.5, further, the invention limits the concentration of spinning solution and polymerized monomers, adopts acrylonitrile and itaconic acid as polymerized monomers, and limits the mass ratio of the two polymerized monomers, and can carry out polymerization reaction within a specified concentration range, thus obtaining polymer with larger molecular weight, the molecular weight of the polymer is between 15 and 20 ten thousand, and the larger the molecular weight is, the better the modulus and strength of the carbon fiber are.
Example 1
Carrying out solution polymerization on 99.5 wt% of AN and 0.5 wt% of IA, carrying out removal of monomers and defoaming treatment to prepare AN AN polymer 19 wt% of dimethyl sulfoxide solution as a spinning solution, carrying out wet spinning by a spinneret plate with 12000 holes, carrying out concentration of a coagulating bath to obtain a dimethyl sulfoxide aqueous solution with the concentration of 55%, controlling the stretching ratio of the spray head to be 0.55 times, forming in the coagulating bath, controlling the temperature of the first temperature measuring point (spinning solution) to be 60 ℃ and the total circulating amount of the coagulating bath to be 10m 3 And/h, wherein the flow rate of the inlet in the direction of the filament bundle is 6m 3 And/h, the flow rate of the inlet perpendicular to the direction of the filament bundle is 4m 3 /h；
The primary fiber is washed by deionized water at 50 ℃, then is subjected to hot water drafting, the hot water temperature is 90 ℃, the drafting multiplying power is 2.5 times respectively, and the fiber after hot water drafting is immersed into an oil bath at 25 ℃ with the concentration of the organic silicone oil agent of 3.5 (wt)%, so that the adhesion of the fiber in a subsequent working section is prevented.
Drying and densification are carried out at 100-130 ℃ by controlling the temperature, then stretching is carried out for 2.2 times in 0.25MPa of pressurized steam, shaping treatment is carried out by 0.95 of stretching multiplying power through 0.1MPa of pressurized steam, and then the PAN precursor is obtained after drying at 100-120 ℃.
And heating the obtained fiber bundle in air at 200-280 ℃ at a stretching ratio of 1.0 to convert the fiber bundle into preoxidized fiber with the density of 1.38g/cm < 3 >. Then in the nitrogen atmosphere of 600-800 ℃, the stretching multiplying power is 1.03, the low-temperature carbonization is carried out, the stretching multiplying power is 0.97 in the 1300-1400 ℃ temperature area, the high-temperature carbonization is carried out, and the obtained product has the stretching strength of 7.25GPa and the strength CV value of 2.5%; the modulus is 340GPa, and the modulus CV value is 1.2%; the elongation at break is 2.1 percent, and the CV value of the elongation at break is 2.6 percent.
Example 2
Carrying out solution polymerization on 99.5 wt% of AN and 0.5 wt% of IA, carrying out removal of monomers and defoaming treatment to prepare 15 wt% of dimethyl sulfoxide solution of AN polymer as spinning stock solution, carrying out wet spinning by a spinneret plate with 15000 holes, carrying out coagulating bath concentration of 60%, controlling the stretching ratio of the spray head to be 0.4 times, forming in a coagulating bath, wherein the temperature of the first temperature measuring point (spinning stock solution) is 45 ℃, and the circulating total amount of the coagulating bath is 12m 3 And/h, wherein the flow rate of the inlet in the direction of the filament bundle is 9.6m 3 And/h, the flow of the inlet perpendicular to the direction of the filament bundle is 4.8m 3 /h；
Washing the nascent fiber with deionized water at 55 ℃, carrying out hot water drafting, wherein the hot water temperature is 70 ℃, the drafting multiplying power is 3 times respectively, and immersing the fiber after hot water drafting in an oil bath at 20 ℃ with the concentration of organic silicone oil agent of 3.6 (wt)%, so as to prevent the fiber from adhering in the subsequent working section.
Drying and densification are carried out by controlling the temperature to be 100-130 ℃. Then, stretching 2 times in 0.2MPa of pressurized steam, shaping by 0.95 of stretching ratio through 0.2MPa of pressurized steam, and drying at 100-120 ℃ to obtain PAN precursor.
And heating the obtained fiber bundle in air at 200-280 ℃ at a stretching ratio of 1.0 to convert the fiber bundle into preoxidized fiber with the density of 1.41g/cm < 3 >. Then in the nitrogen atmosphere of 600-800 ℃, the stretching multiplying power is 1.05, the low-temperature carbonization is carried out, the stretching multiplying power is 0.95 in the 1300-1400 ℃ temperature area, the high-temperature carbonization is carried out, and the obtained product has the stretching strength of 7.31GPa and the strength CV value of 2.6%; modulus is 338GPa, and modulus CV value is 1.3%; the elongation at break is 2.3 percent, and the CV value of the elongation at break is 2.7 percent.
Example 3
Solution polymerization of AN99.5 wt% and IA0.5 wt%After the processes of demono-removal and deaeration, preparing 25 (wt)% dimethyl sulfoxide solution of AN polymer as spinning stock solution, wet spinning by a spinneret plate with 15000 holes, controlling the stretching ratio of the spray head to be 0.8 times by using a dimethyl sulfoxide aqueous solution with the concentration of a coagulating bath of 60% and the temperature of a second temperature measuring point (coagulating bath temperature) of 75 ℃, forming in the coagulating bath, wherein the temperature of the first temperature measuring point (spinning stock solution) is 75 ℃ and the circulating total amount of the coagulating bath is 14m 3 And/h, wherein the flow rate of the inlet in the direction of the filament bundle is 10m 3 And/h, the flow rate of the inlet perpendicular to the direction of the filament bundle is 4m 3 /h；
The primary fiber is washed by deionized water at 70 ℃, then is subjected to hot water drafting, the hot water temperature is 98 ℃, the drafting multiplying power is 5 times respectively, and the fiber after hot water drafting is immersed into an oil bath at 40 ℃ with the concentration of organic silicone oil agent of 4 (wt)%, so that the adhesion of the fiber in a subsequent working section is prevented.
Drying and densification are carried out by controlling the temperature to be 100-130 ℃. Then, stretching 3.5 times in 0.3MPa pressure steam, shaping with a stretching ratio of 1.0 by 0.2MPa pressure steam, and drying at 100-120deg.C to obtain PAN precursor.
And heating the obtained fiber bundle in air at 200-280 ℃ at a stretching ratio of 1.0 to convert the fiber bundle into preoxidized fiber with the density of 1.41g/cm < 3 >. Then in the nitrogen atmosphere of 600-800 ℃, the stretching multiplying power is 1.05, the low-temperature carbonization is carried out, the stretching multiplying power is 0.95 in the 1300-1400 ℃ temperature area, the high-temperature carbonization is carried out, and the obtained product has the stretching strength of 7.4GPa and the strength CV value of 2.3%; modulus 345GPa and modulus CV value 1.5%; the elongation at break is 2.4 percent, and the CV value of the elongation at break is 2.8 percent.
Comparative example 1
Carrying out solution polymerization on 99.5 wt% of AN and 0.5 wt% of IA, carrying out demono-removal and defoaming treatment to prepare 19 wt% of DMSO solution of AN polymer as spinning stock solution, carrying out wet spinning by a spinneret plate with 12000 holes, carrying out coagulating bath concentration of 55%, controlling the stretching ratio of the spray head to be 0.55 times, forming in a coagulating bath, and carrying out wet spinning on the first temperature measuring point (spinning stock solution)Liquid) at a temperature of 50℃and a coagulation bath temperature of 60℃and a total coagulation bath circulation of 10m3/h, wherein the flow rate at the inlet in the direction of the filament bundle was 10m 3 And/h, the flow rate of the inlet perpendicular to the direction of the filament bundle is 0m 3 /h；
The primary fiber is washed by deionized water at 50 ℃, then is subjected to hot water drafting, the hot water temperature is 90 ℃, the drafting multiplying power is 2.5 times respectively, and the fiber after hot water drafting is immersed into an oil bath at 25 ℃ with the concentration of the organic silicone oil agent of 3.5 (wt)%, so that the adhesion of the fiber in a subsequent working section is prevented.
Drying and densification are carried out by controlling the temperature to be 100-130 ℃. Then, stretching 2.2 times in 0.25MPa pressure steam, shaping with 0.1MPa pressure steam and stretching multiplying power of 0.95, and drying at 100-120deg.C to obtain 3kPAN precursor.
And heating the obtained fiber bundle in air at 200-280 ℃ at a stretching ratio of 1.0 to convert the fiber bundle into preoxidized fiber with the density of 1.38g/cm < 3 >. Then in the nitrogen atmosphere of 600-800 ℃, the stretching multiplying power is 1.03, the low-temperature carbonization is carried out, and further in the 1300-1400 ℃, the stretching multiplying power is 0.97, the high-temperature carbonization is carried out, and the obtained product has the stretching strength of 6.5GPa and the strength CV value of 5%; the modulus is 340GPa, and the modulus CV value is 2.5%; the elongation at break is 1.9 percent, and the CV value of the elongation at break is 5.6 percent.
Comparative example 2:
carrying out solution polymerization on 99.5 wt% of AN and 0.5 wt% of IA, carrying out demono-removal and defoaming treatment to prepare 19 wt% of DMSO solution of AN polymer as spinning stock solution, carrying out wet spinning by a spinneret plate with 12000 holes, carrying out shaping in a coagulating bath by controlling the stretching ratio of the spray head to be 0.55 times through DMSO aqueous solution with the coagulating bath concentration of 55% and the coagulating bath temperature of 60 ℃, wherein the temperature of the spinning stock solution T1 is 60 ℃, the coagulating bath temperature is 60 ℃, and the total circulating amount of the coagulating bath is 10m 3 And/h, wherein the flow rate of the inlet in the direction of the filament bundle is 8m 3 And/h, the flow rate of the inlet perpendicular to the direction of the filament bundle is 2m 3 /h；
The primary fiber is washed by deionized water at 50 ℃, then is subjected to hot water drafting, the hot water temperature is 90 ℃, the drafting multiplying power is 2.5 times respectively, and the fiber after hot water drafting is immersed into an oil bath at 25 ℃ with the concentration of the organic silicone oil agent of 3.5 (wt)%, so that the adhesion of the fiber in a subsequent working section is prevented.
Drying and densification are carried out by controlling the temperature to be 100-130 ℃. Then, stretching 2.2 times in 0.25MPa pressure steam, shaping with 0.1MPa pressure steam and stretching multiplying power of 0.95, and drying at 100-120deg.C to obtain PAN precursor.
And heating the obtained fiber bundle in air at 200-280 ℃ at a stretching ratio of 1.0 to convert the fiber bundle into preoxidized fiber with the density of 1.38g/cm < 3 >. Then in the nitrogen atmosphere of 600-800 ℃, the stretching multiplying power is 1.03, the low-temperature carbonization is carried out, the stretching multiplying power is 0.97 in the 1300-1400 ℃, the high-temperature carbonization is carried out, and the stretching strength is 7GPa, and the strength CV value is 3.0%; modulus 335GPa, modulus CV value 3%; the elongation at break is 2.1 percent, and the CV value of the elongation at break is 3.0 percent.
Comparative analysis of example 1 with comparative example 1 and comparative example 2:
1. example 1 was substantially identical to comparative example 1 in terms of the respective process parameters, except that: the flow of the solution in the coagulation bath of example 1 was divided into a direction perpendicular to the filament bundle and a direction along the filament bundle, and the flow ratio in the direction along the filament bundle and the direction perpendicular to the filament bundle was 1.5:1, and the flow of the solution in the direction perpendicular to the filament bundle was not found in comparative example 1, but only in the direction of the filament bundle, and the properties of the produced PAN carbon fiber were found to be: the flow of the coagulating bath solution perpendicular to the direction of the filament bundles can be beneficial to the preparation of the carbon fibers, the tensile strength of the prepared carbon fibers is obviously improved, the quality of the obtained carbon fibers is more stable, and the mass production of the product is more beneficial.
2. The process parameters of example 1 are substantially the same as those of comparative example 2, except that: the flow of the solution in the coagulation bath of example 1 was divided into a direction perpendicular to the filament bundle and a direction along the filament bundle, and the flow of the solution in the coagulation bath of comparative example 2 was also divided into a direction perpendicular to the filament bundle and a direction along the filament bundle, but the flow perpendicular to the filament bundle was different from each other, the flow perpendicular to the filament bundle of comparative example 2 was small, the flow ratio required in the present application was not reached, the diffusion effect of the dimethyl sulfoxide solvent in comparative example 2 was slightly decreased compared with the parameters of the finally produced carbon fiber, and the tensile strength of the carbon fiber was slightly deteriorated, and the CV value of the strength, modulus CV value and elongation at break were deteriorated to some extent, so that the dispersion efficiency of the dimethyl sulfoxide solvent was affected, and the quality of the finished carbon fiber was affected.
In summary, the invention has the following beneficial effects:
1. the invention improves the preparation method of the carbon fiber precursor wet spinning, in particular to the improvement of the flow direction of the solution in the coagulating bath, and the flow direction and the action position of the solution in the coagulating bath are limited, so that the solution in the coagulating bath can pass through the filament outlet position of the filament spraying assembly along the filament bundle direction and the direction vertical to the filament bundle direction, namely the solution in the coagulating bath can rapidly take away the dimethyl sulfoxide solvent flowing out of the filament spraying assembly, the coagulation condition of each filament bundle is kept consistent in the same coagulation environment in the coagulation process of each filament bundle, and the performance of the prepared carbon fiber is improved.
2. The flow rate of the solution in the coagulating bath is further limited, and the flow rates along the direction of the filament bundles and the direction perpendicular to the filament bundles are optimized.
3. The concentration and the temperature of the coagulating bath are further limited, and the stretching ratio of the spray head of the spinning assembly is also limited.
4. The invention further detects the temperature of the spinning solution before spinning and the temperature of the coagulating bath after spinning, controls the temperature of the spinning solution before spinning and the temperature of the coagulating bath after spinning, and preferably controls the temperature difference between the spinning solution and the coagulating bath within less than 1 ℃, thereby reducing the problem of uneven heat transfer caused by inconsistent filament bundle temperature and coagulating temperature, and reducing the influence of inconsistent temperature on the uniformity of filament bundle coagulation.
All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.
Claims (8)
1. The preparation method of the high-strength high-modulus carbon fiber precursor wet spinning comprises the steps of feeding spinning solution into a coagulation bath from a spinning assembly for molding, stretching at a certain multiplying power to obtain PAN primary fibers, and carrying out washing, hot water stretching, oiling, drying and compactness, saturated steam stretching, steam heat setting and drying treatment on the PAN primary fibers to obtain PAN precursor; and then pre-oxidizing, carbonizing at low temperature and carbonizing at high temperature the PAN precursor, which is characterized in that: the flow direction of the solution in the coagulating bath is divided into the direction along the filament bundle and the direction vertical to the filament bundle, and the solution along the filament bundle and the solution vertical to the filament bundle both act on the filament outlet position of the filament spraying assembly.
2. The method for preparing the high-strength high-modulus carbon fiber precursor wet spinning according to claim 1, wherein the method comprises the following steps: the total flow Q of the solution of the coagulating bath is more than 5m 3 And/h, wherein the ratio of the flow along the direction of the filament bundle to the flow perpendicular to the direction of the filament bundle is 1.5:1-2.5:1.
3. The method for preparing the high-strength high-modulus carbon fiber precursor wet spinning according to claim 1 or 2, wherein: the concentration of the solution of the coagulating bath is 30-60 (wt)%, the temperature of the coagulating bath is 40-75 ℃, and the stretching ratio of the spray head component is 0.4-0.8 times.
4. A method for preparing high strength high modulus carbon fiber precursor wet spinning according to claim 3, wherein: the device comprises a first temperature measuring point and a second temperature measuring point, wherein the first temperature measuring point is used for monitoring the temperature of spinning solution; the second temperature measuring point is used for monitoring the temperature of the coagulating bath, and the temperature difference between the first temperature measuring point and the second temperature measuring point is less than 1 ℃.
5. The method for preparing the high-strength high-modulus carbon fiber precursor wet spinning according to claim 1, wherein the method comprises the following steps: the number of holes of the spinning assembly is 12000-15000.
6. The method for preparing the high-strength high-modulus carbon fiber precursor wet spinning according to claim 1, wherein the method comprises the following steps:
washing temperature: 50-70 ℃,
heat traction temperature: stretching ratio at 70-98 ℃): 1.5-5.0;
oiling: organic silicone oil agent, oil concentration: 3.5-4.0%, target oil-up rate: 1.0-1.2%, oiling temperature: 20-40 ℃;
drying and densification: 100-130 ℃;
steam drafting: steam pressure: 0.1-0.3MPa, stretching multiplying power: 1.5-3.5;
steam heat setting: steam setting pressure: 0.1-0.2MPa, stretching multiplying power: 0.9-1.0;
and (3) drying: 100-120 ℃.
7. The method for preparing the high-strength high-modulus carbon fiber precursor wet spinning according to claim 6, wherein: preoxidation temperature: 220-280 ℃, wherein the atmosphere is hot air, and the stretching multiplying power is as follows: 1.0,
low temperature carbonization temperature: 600-800 ℃, the atmosphere is nitrogen, and the stretching multiplying power is as follows: 1.02-1.08
High temperature carbonization temperature: 1300-1400 ℃, nitrogen is used as atmosphere, and the stretching multiplying power is as follows: 0.95-1.0.
8. The method for preparing the high-strength high-modulus carbon fiber precursor wet spinning according to claim 1, wherein the method comprises the following steps: the concentration of the spinning solution is 15% -25%, the molecular weight of the polymer is 15-20 ten thousand, and the polymerized monomer composition of the spinning solution is as follows: AN and IA, the mass ratio is: 99.5:0.5.
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