阅读说明：本技术 一种聚酰亚胺纤维的连续化生产方法 (Continuous production method of polyimide fibers ) 是由 袁小平 陶岩 魏党召 张杨 于 2021-09-08 设计创作，主要内容包括：本发明属于聚酰亚胺纤维制备技术领域,尤其是一种聚酰亚胺纤维的连续化生产方法,包括如下步骤：S1,原材料准备,以均苯四甲酸二酐、联苯醚二胺为原料,以二甲基乙酰胺为溶剂；S2,对S1中的均苯四甲酸二酐原料通过升华釜进行升华提纯,制得精均苯四甲酸二酐,其占重量份为50-52份。此聚酰亚胺纤维的连续化生产方法,通过设置升华釜,达到了先对均苯四甲酸二酐原料进行脱水,在加热真空条件下除去均苯四甲酸二酐原料中游离的水和分子水生产粗酐,同时,脱去低沸点副产物,再在经脱水后的均苯四甲酸二酐原料表面铺设硅胶颗粒,同时利用升华再结晶法提纯,使提纯后的均苯四甲酸二酐原料纯度为99.85%,进而使后续聚合更容易的效果。(The invention belongs to the technical field of polyimide fiber preparation, and particularly relates to a continuous production method of polyimide fibers, which comprises the following steps: s1, preparing raw materials, namely, taking pyromellitic dianhydride and diphenyl ether diamine as raw materials, and taking dimethylacetamide as a solvent; s2, carrying out sublimation purification on the pyromellitic dianhydride raw material in the S1 through a sublimation kettle to prepare refined pyromellitic dianhydride, wherein the weight portion of the refined pyromellitic dianhydride is 50-52. The continuous production method of the polyimide fiber achieves the effects that the pyromellitic dianhydride raw material is dehydrated firstly by arranging the sublimation kettle, free water and molecular water in the pyromellitic dianhydride raw material are removed under the heating vacuum condition to produce crude anhydride, meanwhile, low-boiling-point byproducts are removed, silica gel particles are laid on the surface of the dehydrated pyromellitic dianhydride raw material, and the purified pyromellitic dianhydride raw material is purified by a sublimation recrystallization method to ensure that the purity of the purified pyromellitic dianhydride raw material is 99.85 percent, so that the subsequent polymerization is easier.)

1. A continuous production method of polyimide fibers comprises the following steps:

s1, preparing raw materials, namely, taking pyromellitic dianhydride and diphenyl ether diamine as raw materials, and taking dimethylacetamide as a solvent;

s2, carrying out sublimation purification on the pyromellitic dianhydride raw material in the S1 through a sublimation kettle to prepare refined pyromellitic dianhydride, wherein the weight parts of the refined pyromellitic dianhydride are 50-52 parts;

s3, recrystallizing and purifying the diphenyl ether diamine raw material in the S1 through a reaction kettle to obtain refined diphenyl ether diamine, wherein the refined diphenyl ether diamine accounts for 40-45 parts by weight;

s4, heating the dimethylacetamide solvent in the S1 to remove water, and when the heating temperature reaches 120 ℃, carrying out reduced pressure distillation to obtain purified dimethylacetamide solvent which accounts for 3-10 parts by weight;

s5, carrying out low-temperature polycondensation on the refined pyromellitic dianhydride in the S2 and the refined diphenyl ether diamine in the S3 in a refined dimethylacetamide solvent to form a polyimide solution, heating to 300 ℃, and carrying out high-temperature dehydration ring closure to prepare the polyimide fiber.

2. The continuous production method of polyimide fibers according to claim 1, wherein: the sublimation kettle in the S2 firstly dehydrates the pyromellitic dianhydride raw material at the dehydration temperature of 220-230 ℃ and the vacuum degree of-0.09 MPa, and then sublimates the dehydrated pyromellitic dianhydride raw material at the heating temperature of 240-250 ℃ and the vacuum degree of-0.0999 MPa, the reaction kettle in the S3 at the heating temperature of 50 ℃ and the vacuum degree of-0.09 MPa, and the refined dimethylacetamide solvent prepared in the S4 is stored by a molecular sieve.

3. The continuous production method of polyimide fibers according to claim 1, wherein: sublimation cauldron specifically includes first box (1) in S2, reation kettle specifically includes second box (2) in S3, the material of first box (1) and second box (2) is pottery, the inside of first box (1) is provided with first heating cavity (100), the interior diapire fixed mounting of first heating cavity (100) has first carbon fiber heating pipe (101) that are the distribution of rectangle array.

4. The continuous production method of polyimide fibers according to claim 3, wherein: first annular heat conduction chamber (102) have been seted up to the interior roof of first heating cavity (100), the inner wall fixedly connected with insulating layer (103) in first annular heat conduction chamber (102), the inboard fixed surface of insulating layer (103) is connected with heat-conducting layer (104), the material of insulating layer (103) is aerogel felt, heat-conducting layer (104) material is silver-copper alloy, the lower extreme surface of heat-conducting layer (104) and the inner wall fixed connection in first annular heat conduction chamber (102).

5. The continuous production method of polyimide fibers according to claim 3, wherein: the upper surface of the first box body (1) is provided with a first reaction tank (105), the outer surface of the upper end of the first box body (1) is fixedly communicated with a first connecting pipe (106), a second connecting pipe (107), a third connecting pipe (108) and a fourth connecting pipe (109) respectively, the first connecting pipe (106) corresponds to the third connecting pipe (108), the second connecting pipe (107) corresponds to the fourth connecting pipe (109), the inner walls of one ends of the first connecting pipe (106), the second connecting pipe (107), the third connecting pipe (108) and the fourth connecting pipe (109) are communicated with each other and extend to the inner wall of the first reaction tank (105), the inner wall of the other end of the first connecting pipe (106) is fixedly communicated with a first vacuum pipe (1010) through an electromagnetic valve, the inner wall of the other end of the second connecting pipe (107) is fixedly communicated with a first electromagnetic flowmeter (1011), the inner wall of the other end of the third connecting pipe (108) is fixedly communicated with a second conveying pipe (1016) through an electromagnetic valve And the inner wall of the other end of the fourth connecting pipe (109) is fixedly communicated with a second vacuum pipe (1013) through an electromagnetic valve.

6. The continuous production method of polyimide fibers according to claim 5, wherein: the fixed intercommunication of inner wall of first electromagnetic flowmeter (1011) has fifth connecting pipe (1014), the one end inner wall of fifth connecting pipe (1014) has first conveying pipeline (1015) through the fixed intercommunication of solenoid valve, the surface of first box (1) fixed mounting respectively has first pressure sensor (1017), first temperature sensor (1018), first time relay (1019), second pressure sensor (1020), second temperature sensor (1021) and second time relay (1022), the interior roof of first reaction tank (105) has end cover (1012) through sealing washer threaded connection, the sublimation cauldron still includes telescopic link (1023), the lower fixed surface fixedly connected with shovel dish (1024) of telescopic link (1023).

7. The continuous production method of polyimide fibers according to claim 3, wherein: the inside of second box (2) is provided with second heating cavity (200), the interior diapire fixed mounting of second heating cavity (200) has second carbon fiber heating pipe (2010), second annular heat conduction chamber (201) have been seted up to the interior roof of second heating cavity (200), second reaction tank (202) have been seted up to the upper surface of second box (2), the inner wall of second reaction tank (202) has sealed dish through sealing washer threaded connection.

8. The continuous production method of polyimide fibers according to claim 3, wherein: the right side surface of the second box body (2) is fixedly communicated with a sixth connecting pipe (203) and a seventh connecting pipe (204) respectively, the inner wall of one end of the sixth connecting pipe (203) is communicated with the inside of the second reaction tank (202) and extends to the inside of the second reaction tank, the inner wall of the other end of the sixth connecting pipe (203) is fixedly communicated with a third vacuum pipe (205) through an electromagnetic valve, the inner wall of the other end of the seventh connecting pipe (204) is fixedly communicated with a third conveying pipeline (206) through an electromagnetic valve, and the right side surface of the second box body (2) is fixedly provided with a third time relay (207), a third temperature sensor (208) and a third pressure sensor (209) respectively.

9. The sublimation retort operating method for polyimide fibers according to any one of claims 1 to 6, wherein: step one, opening an end cover (1012) on the upper surface of a first box body (1), pouring a pyromellitic dianhydride raw material into a first reaction tank (105), controlling an electromagnetic valve between a fifth connecting pipe (1014) and a first conveying pipe (1015) to be electrified through a pre-programmed program, at the moment, communicating the first conveying pipe (1015) with the fifth connecting pipe (1014), enabling a water-soluble demulsifier to flow into the fifth connecting pipe (1014) through the first conveying pipe (1015) and the electromagnetic valve, sequentially flowing through a first electromagnetic flow meter (1011) and a second connecting pipe (107) and finally flowing into the first reaction tank (105), detecting the flow of the flowing water-soluble demulsifier by arranging the electromagnetic flow meter between the second connecting pipe (107) and the fifth connecting pipe (1014), and controlling the electromagnetic valve to be powered off through the program when the flow of the flowing water-soluble demulsifier reaches a preset value, stopping a first material conveying pipe (1015) and a fifth connecting pipe (1014), detecting the temperature in a first reaction tank (105) by a first temperature sensor (1018), controlling the internal temperature of the first reaction tank to 230 ℃, controlling the energization of an electromagnetic valve between a first connecting pipe (106) and a first vacuum pipe (1010) by a program, conducting the first vacuum pipe (1010) and the first connecting pipe (106), communicating the inner wall of one end of the first vacuum pipe (1010) with external vacuum pump equipment, vacuumizing the first reaction tank (105) by the vacuum pump equipment to ensure that the vacuum degree in the first reaction tank (105) is-0.09 MPa, detecting the pressure in the first reaction tank (105) by a first pressure sensor (1017), controlling the electromagnetic valve to be powered off when a set pressure value is reached, setting a first time relay (1019) to enable a first carbon fiber heating pipe (101) to work, and increasing the heat generated by the first carbon fiber heating pipe (101) to a first annular heat conducting cavity (102), arranging a heat insulation layer (103) on the inner wall of a first annular heat conduction cavity (102) to insulate heat of the heat lifted into the first annular heat conduction cavity (102), arranging a heat conduction layer (104) to uniformly heat the inner wall of a first reaction tank (105) so as to uniformly heat a pyromellitic dianhydride raw material in the first reaction tank, heating the first carbon fiber heating pipe (101) in the first reaction tank (105) for 6 hours, removing free water and molecular water in the pyromellitic dianhydride raw material under a heating vacuum condition to produce crude anhydride, and removing low-boiling-point byproducts;

step two, the time relay reaches the set time, the electromagnetic valve between the third connecting pipe (108) and the second conveying pipe (1016) is controlled to be electrified, the third connecting pipe (108) is conducted with the second conveying pipe (1016), so that silica gel particles flow into the first reaction tank (105) through the third connecting pipe (108) and the second conveying pipe (1016), the electromagnetic valve is controlled to be automatically powered off after one minute, at the moment, the thickness of the silica gel particles on the surface of the dehydrated pyromellitic dianhydride raw material is 1cm, the connection between the third connecting pipe (108) and the second conveying pipe (1016) is cut off, the second temperature sensor (1021) is arranged to control the temperature in the first reaction tank (105) to be 250 ℃, the electromagnetic valve between the fourth connecting pipe (109) and the second vacuum pipe (1013) is controlled to be electrified through a program, the first reaction tank (105) is vacuumized through vacuum pump equipment, the vacuum degree in the first reaction tank (105) is set to-0.0999 MPa, a second pressure sensor (1020) is arranged to detect the pressure in the first reaction tank (105), when the pressure reaches a set pressure value, the electromagnetic valve is controlled to be powered off, and the dehydrated pyromellitic dianhydride raw material is sublimated and crystallized to obtain the refined pyromellitic dianhydride because the first reaction tank (105) is in a heating and high vacuum state.

10. The method of claim 8, wherein the step of operating the reaction vessel for polyimide fibers comprises: pouring a diphenyl ether diamine raw material into a second reaction tank (202), controlling a second carbon fiber heating pipe (2010) to work by a program, and uniformly heating the inner wall of the second reaction tank (202) by heat generated by the work of a first carbon fiber heating pipe (101) through a second annular heat-conducting cavity (201) to uniformly heat the diphenyl ether diamine raw material in the second reaction tank (202);

step two, controlling an electromagnetic valve between a sixth connecting pipe (203) and a third vacuum pipe (205) to be electrified to lead the sixth connecting pipe (203) and the third vacuum pipe (205) to be conducted, vacuumizing the second reaction tank (202) by an external vacuum pump, arranging a third pressure sensor (209) to lead the vacuum degree in the second reaction tank (202) to be-0.09 MPa, when the pressure in the second reaction tank (202) reaches a set pressure value, switching off the electromagnetic valve, arranging a third temperature sensor (208) on the right side surface of a second box body (2) to lead the temperature in the second reaction tank (202) to be controlled at 50 ℃, arranging a third time relay (207) to lead a first carbon fiber heating pipe (101) to heat the second reaction tank (202) for 40 minutes to remove moisture contained in the diphenyl ether diamine raw material, when the third time relay (207) reaches a set time, controlling an electromagnetic valve between the seventh connecting pipe (204) and the third material conveying pipe (206) to be electrified, enabling the ethanol solution to flow into the second reaction tank (202) through the seventh connecting pipe (204) and the third material conveying pipe (206), controlling the electromagnetic valve to be automatically powered off after one minute through a program, starting the third time relay (207) again, controlling the first carbon fiber heating pipe (101) to heat the second reaction tank (202) again for 1 hour, and obtaining the refined diphenyl ether diamine.

Technical Field

The invention relates to the technical field of polyimide fiber preparation, in particular to a continuous production method of polyimide fibers.

Background

Polyimide refers to a class of polymers containing imide rings (-CO-N-CO-) on the main chain, and is one of organic polymer materials with the best comprehensive performance. The high-temperature-resistant insulating material has high temperature resistance of more than 400 ℃, long-term use temperature range of-200-300 ℃, no obvious melting point in part, high insulating property, dielectric constant of 4.0 at 103 Hz and dielectric loss of only 0.004-0.007, and belongs to F-H grade insulation.

Polyimide fibers can be prepared by solution spinning or melt spinning, but it is difficult to obtain highly heat-resistant polyimide fibers by melt spinning, and thus, in the prior art, highly heat-resistant polyimide fibers are generally prepared by solution spinning. When the solution spinning method is adopted to prepare the polyimide fiber, the polyimide can be directly dissolved in an organic solvent, the polyimide fiber is obtained after solution spinning, but the polyimide with a proper chemical structure is generally insoluble in the organic solvent, so the polyimide fiber structure obtained by the method is greatly limited, and meanwhile, due to the mature synthesis of aromatic amine in the prior art, when the polyimide fiber is synthesized by the method, the synthesis process is complex, the purity is not enough, the continuous production of the polyimide fiber is difficult to realize, the yield of the synthesized polyimide fiber is limited, the cost is high, and the development of the polyimide fiber is greatly limited.

Disclosure of Invention

Based on the technical problems that the existing polyimide fiber is complex in synthesis process, insufficient in purity and difficult to realize continuous production of polyimide fibers when the polyimide fibers are synthesized by aromatic amine, the yield of the synthesized polyimide fibers is limited, the cost is high, and the development of the polyimide fibers is greatly limited, the invention provides a continuous production method of the polyimide fibers.

The invention provides a continuous production method of polyimide fibers, which comprises the following steps:

s1, preparing raw materials, namely, taking pyromellitic dianhydride and diphenyl ether diamine as raw materials, and taking dimethylacetamide as a solvent;

s2, carrying out sublimation purification on the pyromellitic dianhydride raw material in the S1 through a sublimation kettle to prepare refined pyromellitic dianhydride, wherein the weight parts of the refined pyromellitic dianhydride are 50-52 parts;

s3, recrystallizing and purifying the diphenyl ether diamine raw material in the S1 through a reaction kettle to obtain refined diphenyl ether diamine, wherein the refined diphenyl ether diamine accounts for 40-45 parts by weight;

s4, heating the dimethylacetamide solvent in the S1 to remove water, and when the heating temperature reaches 120 ℃, carrying out reduced pressure distillation to obtain purified dimethylacetamide solvent which accounts for 3-10 parts by weight;

s5, carrying out low-temperature polycondensation on the refined pyromellitic dianhydride in the S2 and the refined diphenyl ether diamine in the S3 in a refined dimethylacetamide solvent to form a polyimide solution, heating to 300 ℃, and carrying out high-temperature dehydration ring closure to prepare the polyimide fiber.

Preferably, the sublimation kettle in the S2 firstly dehydrates the pyromellitic dianhydride raw material at a dehydration temperature of 220-230 ℃ and a vacuum degree of-0.09 MPa, and then sublimates the dehydrated pyromellitic dianhydride raw material at a heating temperature of 240-250 ℃ and a vacuum degree of-0.0999 MPa, the heating temperature of the reaction kettle in the S3 is 50 ℃ and the vacuum degree of-0.09 MPa, and the refined dimethylacetamide solvent prepared in the S4 is stored by a molecular sieve.

Preferably, the sublimation kettle in the S2 specifically comprises a first box body, the reaction kettle in the S3 specifically comprises a second box body, the first box body and the second box body are made of ceramic, a first heating cavity is arranged inside the first box body, and first carbon fiber heating pipes distributed in a rectangular array are fixedly mounted on the inner bottom wall of the first heating cavity;

through above-mentioned technical scheme, first box and second box are made by pottery, have high melting point, high rigidity, high wear resistance, oxytolerant and adiabatic, and the inner diapire of first heating cavity sets up first carbon fiber heating pipe as the heating source, provides the heat to the sublimation cauldron.

Preferably, a first annular heat conduction cavity is formed in the inner top wall of the first heating cavity, a heat insulation layer is fixedly connected to the inner wall of the first annular heat conduction cavity, a heat conduction layer is fixedly connected to the inner side surface of the heat insulation layer, the heat insulation layer is made of aerogel felt, the heat conduction layer is made of silver-copper alloy, and the lower end surface of the heat conduction layer is fixedly connected with the inner wall of the first annular heat conduction cavity;

through above-mentioned technical scheme, the insulating layer insulates against heat to the inner wall outside in first annular heat conduction chamber, avoids first carbon fiber heating pipe in the heating process, the heat loss appears, sets up the heat-conducting layer and carries out the heat transfer to the heat that rises into in the first annular heat conduction chamber.

Preferably, the upper surface of the first box body is provided with a first reaction tank, the outer surface of the upper end of the first box body is respectively and fixedly communicated with a first connecting pipe, a second connecting pipe, a third connecting pipe and a fourth connecting pipe, the first connecting pipe corresponds to the third connecting pipe, the second connecting pipe corresponds to the fourth connecting pipe, the inner walls of one ends of the first connecting pipe, the second connecting pipe, the third connecting pipe and the fourth connecting pipe are all communicated and extend to the inner wall of the first reaction tank, the inner wall of the other end of the first connecting pipe is fixedly communicated with a first vacuum pipe through an electromagnetic valve, a first electromagnetic flowmeter is fixedly communicated with the inner wall of the other end of the second connecting pipe, a sixth connecting pipe is fixedly communicated with the inner wall of the other end of the third connecting pipe through an electromagnetic valve, and a second vacuum pipe is fixedly communicated with the inner wall of the other end of the fourth connecting pipe through an electromagnetic valve;

through the technical scheme, the first electromagnetic flow meter is arranged to detect the flow of the water-soluble demulsifier, so that the capacity of the water-soluble demulsifier flowing into the first reaction tank is controlled.

Preferably, the inner wall of the first electromagnetic flow meter is fixedly communicated with a fifth connecting pipe, the inner wall of one end of the fifth connecting pipe is fixedly communicated with a first conveying pipe through an electromagnetic valve, the inner wall of one end of the sixth connecting pipe is fixedly communicated with a second conveying pipe through an electromagnetic valve, the outer surface of the first box body is respectively and fixedly provided with a first pressure sensor, a first temperature sensor, a first time relay, a second pressure sensor, a second temperature sensor and a second time relay, the inner top wall of the first reaction tank is in threaded connection with an end cover through a sealing ring, the sublimation kettle further comprises a telescopic rod, and the lower surface of the telescopic rod is fixedly connected with a shovel disc;

through above-mentioned technical scheme, when needs take out smart pyromellitic dianhydride, open the end cover, drive the refined pyromellitic dianhydride of shovel dish to first reaction tank inner wall through the telescopic link and strike off.

Preferably, a second heating cavity is arranged inside the second box body, a second carbon fiber heating pipe is fixedly installed on the inner bottom wall of the second heating cavity, a second annular heat conduction cavity is formed in the inner top wall of the second heating cavity, a second reaction tank is formed in the upper surface of the second box body, and the inner wall of the second reaction tank is in threaded connection with a sealing disc through a sealing ring;

through above-mentioned technical scheme, the second reaction tank uses with sealed dish cooperation, seals the roof in the second reaction tank, makes the inside encapsulated situation that is in of second reaction tank to be convenient for carry out the evacuation to it.

Preferably, a sixth connecting pipe and a seventh connecting pipe are fixedly communicated with the right side surface of the second box body respectively, the inner wall of one end of the sixth connecting pipe penetrates through and extends into the second reaction tank, the inner wall of the other end of the sixth connecting pipe is fixedly communicated with a third vacuum pipe through an electromagnetic valve, the inner wall of the other end of the seventh connecting pipe is fixedly communicated with a third conveying pipe through an electromagnetic valve, and a third time relay, a third temperature sensor and a third pressure sensor are fixedly mounted on the right side surface of the second box body respectively;

through above-mentioned technical scheme, seventh connecting pipe and third conveying pipeline cooperation are used, are convenient for flow into the second reaction tank with ethanol solution, purify the diphenyl ether diamine raw materials.

Preferably, an operation method of a sublimation kettle for polyimide fibers is provided, which comprises the steps of opening an end cover on the upper surface of a first box body, pouring pyromellitic dianhydride raw material into a first reaction tank, controlling the energization of an electromagnetic valve between a fifth connecting pipe and the first connecting pipe by a pre-programmed program, communicating the first connecting pipe and the fifth connecting pipe at the moment, enabling water-soluble demulsifier to flow into the fifth connecting pipe through the first connecting pipe and the electromagnetic valve, sequentially flowing through a first electromagnetic flow meter and a second connecting pipe, finally flowing into the first reaction tank, detecting the flow of the flowing water-soluble demulsifier by arranging the electromagnetic flow meter between the second connecting pipe and the fifth connecting pipe, controlling the power-off of the electromagnetic valve at the position by the program when the flow of the flowing water-soluble demulsifier reaches a preset value, stopping the first connecting pipe and the fifth connecting pipe, and arranging a first temperature sensor to detect the temperature in the first reaction tank, controlling the internal temperature of the first vacuum tube to 230 ℃, controlling the electromagnetic valve between the first connecting tube and the first vacuum tube to be electrified by a program, communicating the first vacuum tube and the first connecting tube, communicating the inner wall of one end of the first vacuum tube with external vacuum pump equipment, vacuumizing the first reaction tank by the vacuum pump equipment to ensure that the vacuum degree in the first reaction tank is-0.09 MPa, arranging a first pressure sensor to detect the pressure in the first reaction tank, controlling the electromagnetic valve to be powered off when a set pressure value is reached, arranging a first time relay to enable a first carbon fiber heating tube to work, enabling the heat generated by the first carbon fiber heating tube to rise into a first annular heat conduction cavity, arranging a heat insulation layer on the inner wall of the first annular heat conduction cavity to insulate the heat rising into the first annular heat conduction cavity, arranging a heat conduction layer to uniformly heat the inner wall of the first reaction tank, and enabling the pyromellitic dianhydride raw material in the first reaction tank to be uniformly heated, the first carbon fiber heating pipe heats the first reaction tank for 6 hours, removes free water and molecular water in the pyromellitic dianhydride raw material under the heating vacuum condition to produce crude anhydride, and removes by-products with low boiling points;

step two, controlling an electromagnetic valve between a third connecting pipe and a second conveying pipe to be electrified when a time relay reaches a set time, conducting the third connecting pipe and the second conveying pipe to enable silica gel particles to flow into a first reaction tank through the third connecting pipe and the second conveying pipe, automatically powering off the electromagnetic valve after one minute through program control, controlling the thickness of the silica gel particles on the surface of the dehydrated pyromellitic dianhydride raw material to be 1cm at the moment, stopping the connection between the third connecting pipe and the second conveying pipe, setting a second temperature sensor to control the temperature in the first reaction tank to be 250 ℃, controlling the electromagnetic valve between a fourth connecting pipe and the second vacuum pipe to be electrified through program control, vacuumizing the first reaction tank through vacuum pump equipment to enable the vacuum degree in the first reaction tank to be-0.0999 MPa, setting a second pressure sensor to detect the pressure in the first reaction tank, and when a set pressure value is reached, controlling the electromagnetic valve to be powered off, and subliming and crystallizing the dewatered pyromellitic dianhydride raw material to obtain the refined pyromellitic dianhydride because the first reaction tank is in a heating and high vacuum state.

Preferably, a polyimide fiber reaction kettle operation method is provided, wherein in the first step, a diphenyl ether diamine raw material is poured into a second reaction tank, a second carbon fiber heating pipe is controlled to work firstly through a program, and heat generated by the work of the first carbon fiber heating pipe uniformly heats the inner wall of the second reaction tank through a second annular heat conduction cavity, so that the diphenyl ether diamine raw material in the second reaction tank is uniformly heated;

step two, controlling an electromagnetic valve between a sixth connecting pipe and a third vacuum pipe to be electrified to ensure that the sixth connecting pipe is conducted with the third vacuum pipe, vacuumizing the second reaction tank by an external vacuum pump, arranging a third pressure sensor to ensure that the vacuum degree in the second reaction tank is-0.09 MPa, when the pressure in the second reaction tank reaches a set pressure value, powering off the electromagnetic valve, arranging a third temperature sensor on the right side surface of a second box body to ensure that the temperature in the second reaction tank is controlled at a temperature, arranging a third time relay to ensure that a first carbon fiber heating pipe heats the second reaction tank for minutes to remove water contained in the diphenyl ether diamine raw material, and when the third time relay reaches a set time, controlling the electromagnetic valve between the seventh connecting pipe and the third conveying pipe to be electrified to ensure that the ethanol solution flows into the second reaction tank through the seventh connecting pipe and the third conveying pipe, and automatically powering off the electromagnetic valve after one minute through program control, starting the third time relay again, and controlling the first carbon fiber heating pipe to heat the second reaction tank for 1 hour again to prepare the refined diphenyl ether diamine.

The beneficial effects of the invention are as follows:

1. through setting up the sublimation cauldron, reached earlier to the pyromellitic dianhydride raw materials dewater, detached water and molecular water produce crude anhydride in the pyromellitic dianhydride raw materials under the heating vacuum condition, simultaneously, take off low boiling point accessory substance, again lay silica gel granule on the pyromellitic dianhydride raw materials surface after the dehydration, utilize the purification of sublimation recrystallization method simultaneously, make the purity of the pyromellitic dianhydride raw materials after the purification 99.85%, and then make follow-up polymerization effect easier.

2. Through the arrangement of the reaction kettle, the effects that the moisture contained in the diphenyl ether diamine raw material is removed firstly under the heating vacuum condition, and then the diphenyl ether diamine raw material is recrystallized and purified through the ethanol solution, so that the purity of the purified diphenyl ether diamine raw material is 99.95%, and further the subsequent polymerization is easier are achieved.

Drawings

FIG. 1 is a schematic view of a continuous production method of polyimide fibers;

FIG. 2 is a perspective view of a first tank structure of a continuous production method of polyimide fibers;

FIG. 3 is a sectional view showing the structure of a second tank in a continuous process for producing polyimide fibers;

FIG. 4 is an exploded view of a first tank structure of a continuous process for producing polyimide fibers;

FIG. 5 is a perspective view showing a second connecting tube structure of a method for continuously producing polyimide fibers;

FIG. 6 is an exploded view of a shovel plate structure of a continuous production method of polyimide fibers;

fig. 7 is a perspective view of a telescopic rod structure of a continuous production method of polyimide fibers.

In the figure: 1. a first case; 100. a first heating chamber; 101. a first carbon fiber heating pipe; 102. a first annular heat-conducting cavity; 103. a thermal insulation layer; 104. a heat conductive layer; 105. a first reaction tank; 106. a first connecting pipe; 107. a second connecting pipe; 108. a third connecting pipe; 109. a fourth connecting pipe; 1010. a first vacuum tube; 1011. a first electromagnetic flow meter; 1012. an end cap; 1013. a second vacuum tube; 1014. a fifth connecting pipe; 1015. a first feed delivery pipe; 1016. a second delivery pipe; 1017. a first pressure sensor; 1018. a first temperature sensor; 1019. a first time relay; 1020. a second pressure sensor; 1021. a second temperature sensor; 1022. a second time relay; 1023. a telescopic rod; 1024. a shovel plate; 2. a second case; 200. a second heating chamber; 201. a second annular heat-conducting cavity; 202. a second reaction tank; 203. a sixth connecting pipe; 204. a seventh connecting pipe; 205. a third vacuum tube; 206. a third delivery pipe; 207. a third time relay; 208. a third temperature sensor; 209. a third pressure sensor; 2010. a second carbon fiber heating pipe.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Referring to fig. 1 to 7, a method for continuously producing polyimide fibers includes the steps of:

s1, preparing raw materials, namely, taking pyromellitic dianhydride and diphenyl ether diamine as raw materials, and taking dimethylacetamide as a solvent;

s2, carrying out sublimation purification on the pyromellitic dianhydride raw material in the S1 through a sublimation kettle to prepare refined pyromellitic dianhydride, wherein the weight parts of the refined pyromellitic dianhydride are 50-52 parts;

s3, recrystallizing and purifying the diphenyl ether diamine raw material in the S1 through a reaction kettle to obtain refined diphenyl ether diamine, wherein the refined diphenyl ether diamine accounts for 40-45 parts by weight;

s4, heating the dimethylacetamide solvent in the S1 to remove water, and when the heating temperature reaches 120 ℃, carrying out reduced pressure distillation to obtain purified dimethylacetamide solvent which accounts for 3-10 parts by weight;

s5, carrying out low-temperature polycondensation on the refined pyromellitic dianhydride in the S2 and the refined diphenyl ether diamine in the S3 in a refined dimethylacetamide solvent to form a polyimide solution, heating to 300 ℃, and carrying out high-temperature dehydration ring closure to prepare the polyimide fiber.

Further, in S2, firstly, the sublimation kettle dehydrates the pyromellitic dianhydride raw material at the dehydration temperature of 220-230 ℃ and the vacuum degree of-0.09 MPa, and then sublimates the dehydrated pyromellitic dianhydride raw material at the heating temperature of 240-250 ℃ and the vacuum degree of-0.0999 MPa, and in S3, the heating temperature of the reaction kettle is 50 ℃ and the vacuum degree of-0.09 MPa, and the refined dimethylacetamide solvent prepared in S4 is stored by a molecular sieve.

Further, in order to purify the pyromellitic dianhydride raw material, the sublimation kettle in the S2 specifically comprises a first box body 1, the reaction kettle in the S3 specifically comprises a second box body 2, the first box body 1 and the second box body 2 are made of ceramic, a first heating cavity 100 is arranged inside the first box body 1, and first carbon fiber heating pipes 101 distributed in a rectangular array are fixedly installed on the inner bottom wall of the first heating cavity 100; first box 1 and second box 2 are made by pottery, have high melting point, high rigidity, high wear resistance, anti oxidation and adiabatic, and the interior diapire of first heating chamber 100 sets up first carbon fiber heating pipe 101 as the heating source, provides the heat to the sublimation cauldron.

Further, in order to provide a heat source for the first box body 1, a first annular heat conduction cavity 102 is formed in the inner top wall of the first heating cavity 100, a heat insulation layer 103 is fixedly connected to the inner wall of the first annular heat conduction cavity 102, a heat conduction layer 104 is fixedly connected to the inner side surface of the heat insulation layer 103, the heat insulation layer 103 is made of aerogel felt, the heat conduction layer 104 is made of silver-copper alloy, and the lower end surface of the heat conduction layer 104 is fixedly connected with the inner wall of the first annular heat conduction cavity 102; the heat insulation layer 103 insulates heat of the outer side of the inner wall of the first annular heat conduction cavity 102, so that heat loss of the first carbon fiber heating pipe 101 in the heating process is avoided, and the heat conduction layer 104 is arranged to conduct heat transfer on heat rising into the first annular heat conduction cavity 102.

Further, in order to implement dehydration and sublimation of pyromellitic dianhydride raw material, a first reaction tank 105 is disposed on the upper surface of the first tank 1, a first connection pipe 106, a second connection pipe 107, a third connection pipe 108 and a fourth connection pipe 109 are fixedly communicated with the outer surface of the upper end of the first tank 1, the first connection pipe 106 corresponds to the third connection pipe 108, the second connection pipe 107 corresponds to the fourth connection pipe 109, inner walls of one ends of the first connection pipe 106, the second connection pipe 107, the third connection pipe 108 and the fourth connection pipe 109 are communicated with each other and extend to the inner wall of the first reaction tank 105, a first vacuum pipe 1010 is fixedly communicated with the inner wall of the other end of the first connection pipe 106 through an electromagnetic valve, a first electromagnetic flowmeter 1011 is fixedly communicated with the inner wall of the other end of the second connection pipe 107, and a second material conveying pipe 1016 is fixedly communicated with the inner wall of the other end of the third connection pipe 108 through an electromagnetic valve, the inner wall of the other end of the fourth connecting pipe 109 is fixedly communicated with a second vacuum pipe 1013 through an electromagnetic valve; the first electromagnetic flowmeter 1011 is arranged to detect the flow of the water-soluble demulsifier, thereby controlling the volume of the water-soluble demulsifier flowing into the first reaction tank 105.

Further, in order to realize the extraction of purified pyromellitic dianhydride, a fifth connecting pipe 1014 is fixedly communicated with the inner wall of the first electromagnetic flowmeter 1011, a first material conveying pipe 1015 is fixedly communicated with the inner wall of one end of the fifth connecting pipe 1014 through an electromagnetic valve, a first pressure sensor 1017, a first temperature sensor 1018, a first time relay 1019, a second pressure sensor 1020, a second temperature sensor 1021 and a second time relay 1022 are respectively and fixedly installed on the outer surface of the first box body 1, the inner top wall of the first reaction tank 105 is connected with an end cover 1012 through a sealing ring thread, the sublimation kettle further comprises a telescopic rod 1023, and a shovel disc 1024 is fixedly connected to the lower surface of the telescopic rod 1023; when the fine pyromellitic dianhydride needs to be taken out, the end cover 1012 is opened, and the telescopic rod 1023 drives the shovel disc 1024 to scrape the fine pyromellitic dianhydride on the inner wall of the first reaction tank 105.

Through setting up the sublimation cauldron, reached earlier to the pyromellitic dianhydride raw materials dewater, detached water and molecular water produce crude anhydride in the pyromellitic dianhydride raw materials under the heating vacuum condition, simultaneously, take off low boiling point accessory substance, again lay silica gel granule on the pyromellitic dianhydride raw materials surface after the dehydration, utilize the purification of sublimation recrystallization method simultaneously, make the purity of the pyromellitic dianhydride raw materials after the purification 99.85%, and then make follow-up polymerization effect easier.

Further, in order to remove water contained in the diphenyl ether diamine raw material, a second heating cavity 200 is arranged inside the second box body 2, a second carbon fiber heating pipe 2010 is fixedly mounted on the inner bottom wall of the second heating cavity 200, a second annular heat conduction cavity 201 is formed in the inner top wall of the second heating cavity 200, a second reaction tank 202 is formed in the upper surface of the second box body 2, and a sealing disc is connected to the inner wall of the second reaction tank 202 through a sealing ring thread; the second reaction tank 202 is matched with a sealing disc for use, and the inner top wall of the second reaction tank 202 is sealed, so that the inside of the second reaction tank 202 is in a sealed state, and the second reaction tank 202 is convenient to vacuumize.

Further, in order to realize recrystallization purification of the diphenyl oxide diamine raw material, a sixth connecting pipe 203 and a seventh connecting pipe 204 are fixedly communicated with the right side surface of the second box 2, an inner wall of one end of the sixth connecting pipe 203 penetrates through and extends into the second reaction tank 202, an inner wall of the other end of the sixth connecting pipe 203 is fixedly communicated with a third vacuum pipe 205 through an electromagnetic valve, an inner wall of the other end of the seventh connecting pipe 204 is fixedly communicated with a third feed delivery pipe 206 through an electromagnetic valve, and a third time relay 207, a third temperature sensor 208 and a third pressure sensor 209 are fixedly installed on the right side surface of the second box 2; the seventh connecting pipe 204 is used in cooperation with the third feeding pipe 206, so that the ethanol solution can conveniently flow into the second reaction tank 202 to purify the diphenyl ether diamine raw material.

Through the arrangement of the reaction kettle, the effects that the moisture contained in the diphenyl ether diamine raw material is removed firstly under the heating vacuum condition, and then the diphenyl ether diamine raw material is recrystallized and purified through the ethanol solution, so that the purity of the purified diphenyl ether diamine raw material is 99.95%, and further the subsequent polymerization is easier are achieved.

Sublimation kettle working principle: step one, opening an end cover 1012 on the upper surface of a first box body 1, pouring a pyromellitic dianhydride raw material into a first reaction tank 105, controlling an electromagnetic valve between a fifth connecting pipe 1014 and the first connecting pipe 1015 to be electrified through a pre-programmed program, at the moment, enabling the first connecting pipe 1015 to be communicated with the fifth connecting pipe 1014, enabling a water-soluble demulsifier to flow into the fifth connecting pipe 1014 through the first connecting pipe 1015 and the electromagnetic valve, sequentially flowing through a first electromagnetic flowmeter 1011 and a second connecting pipe 107, finally flowing into the first reaction tank 105, detecting the flow of the flowing water-soluble demulsifier by arranging the electromagnetic flowmeter between the second connecting pipe 107 and the fifth connecting pipe 1014, controlling the electromagnetic valve at the position to be powered off through the program when the flow of the flowing water-soluble demulsifier reaches a preset value, stopping the first connecting pipe 1015 and the fifth connecting pipe 1014, and setting a first temperature sensor 1018 to detect the temperature in the first reaction tank 105, controlling the internal temperature of the first vacuum tube 1010 to 230 ℃, controlling the energization of an electromagnetic valve between the first connecting tube 106 and the first vacuum tube 1010 through a program, conducting the first vacuum tube 1010 and the first connecting tube 106, communicating the inner wall of one end of the first vacuum tube 1010 with external vacuum pump equipment, vacuumizing the first reaction tank 105 through the vacuum pump equipment to enable the vacuum degree in the first reaction tank 105 to be-0.09 MPa, arranging a first pressure sensor 1017 to detect the pressure in the first reaction tank 105, controlling the electromagnetic valve to be powered off when a set pressure value is reached, arranging a first time relay 1019 to enable the first carbon fiber heating tube 101 to work, increasing the heat generated by the first carbon fiber heating tube 101 into the first annular heat-conducting cavity 102, arranging a heat-conducting layer 103 on the inner wall of the first annular heat-conducting cavity 102 to insulate the heat raised into the first annular heat-conducting cavity 102, and arranging 104 to uniformly heat the inner wall of the first reaction tank 105, enabling the pyromellitic dianhydride raw material in the pyromellitic dianhydride raw material to be heated uniformly, heating the first carbon fiber heating pipe 101 in the first reaction tank 105 for 6 hours, removing free water and molecular water in the pyromellitic dianhydride raw material under the heating vacuum condition to produce crude anhydride, and simultaneously removing low-boiling-point byproducts;

step two, the time relay reaches the set time, the electromagnetic valve between the third connecting pipe 108 and the second material conveying pipe 1016 is controlled to be electrified, the third connecting pipe 108 and the second material conveying pipe 1016 are conducted, silica gel particles flow into the first reaction tank 105 through the third connecting pipe 108 and the sixth connecting pipe 1012, the electromagnetic valve is controlled by a program to be automatically powered off after one minute, at the moment, the thickness of the silica gel particles on the surface of the dehydrated pyromellitic dianhydride raw material is 1cm, the third connecting pipe 108 and the second material conveying pipe 1016 are cut off, the second temperature sensor 1021 is arranged to control the temperature in the first reaction tank 105 to be 250 ℃, the electromagnetic valve between the fourth connecting pipe 109 and the second vacuum pipe 1013 is controlled to be electrified by the program, the first reaction tank 105 is vacuumized by a vacuum pump device, the vacuum degree in the first reaction tank 105 is-0.0999 MPa, the second pressure sensor is arranged to detect the pressure in the first reaction tank 105, when the set pressure value is reached, the electromagnetic valve is controlled to be powered off, and the dehydrated pyromellitic dianhydride raw material is sublimated and crystallized to obtain the refined pyromellitic dianhydride because the first reaction tank 105 is in a heating and high vacuum state.

The working principle of the reaction kettle is as follows: firstly, pouring a diphenyl ether diamine raw material into a second reaction tank 202, controlling a second carbon fiber heating pipe 2010 to work through a program, and uniformly heating the inner wall of the second reaction tank 202 by heat generated by the work of a first carbon fiber heating pipe 101 through a second annular heat-conducting cavity 201 to uniformly heat the diphenyl ether diamine raw material in the second reaction tank 202;

step two, controlling the electromagnetic valve between the sixth connecting pipe 203 and the third vacuum pipe 205 to be electrified, so as to lead the sixth connecting pipe 203 and the third vacuum pipe 205 to be conducted, vacuumizing the second reaction tank 202 through an external vacuum pump, setting a third pressure sensor 209 to lead the vacuum degree in the second reaction tank 202 to be-0.09 MPa, when the pressure in the second reaction tank 202 reaches a set pressure value, switching off the electromagnetic valve, setting a third temperature sensor 208 on the right side surface of the second box body 2 to lead the temperature in the second reaction tank 202 to be controlled at 50 ℃, setting a third time relay 207 to lead the first carbon fiber heating pipe 101 to heat the second reaction tank 202 for 40 minutes, removing the moisture contained in the diphenyl ether diamine raw material, when the third time relay 207 reaches a set time, controlling the electromagnetic valve between the seventh connecting pipe 204 and the third delivery pipe 206 to be electrified, so as to lead the ethanol solution to flow into the second reaction tank 202 through the seventh connecting pipe 204 and the third delivery pipe 206, the electromagnetic valve is automatically powered off after one minute through program control, the third time relay 207 is started again, and the first carbon fiber heating pipe 101 is controlled to heat the second reaction tank 202 for 1 hour again, so that the refined diphenyl ether diamine is prepared.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.