CN104278338A - Gel spinning method for manufacturing aramid fiber III - Google Patents

Abstract

The invention provides a gel spinning method for manufacturing aramid fiber III, belonging to the technical field of chemical synthesis fibers. The gel spinning method comprises the following technological steps: A. extruding a spinning stock solution through a metering pump and a spinneret to form fine flow entering an air layer; B. leading the extruded fine flow passing through the air layer to enter first-level freezing liquid to form gel fibers and treating by adopting negative stretching; C. leading the gel fibers to enter second-level freezing liquid, performing plasticized positive stretching and further freezing to form aramid fiber III with a collection state primary structure; D. washing, oiling and drying the secondarily frozen and formed aramid fiber III to obtain aramid fiber III protofilament; and E. performing heat setting to the aramid fiber III protofilament to obtain finished fibers. According to the gel spinning method, the performance of the aramid fiber III products can be further improved, the fiber production efficiency can be markedly increased, the fiber impregnation strength of the finished fiber is improved to 5.8GPa, and the spinning speed achieves 30-100m/min.

Description

A kind of gel spinning method for manufacturing aramid fiber III

technical field

The invention relates to a spinning method of aramid III fiber, more specifically, the invention relates to a spinning process for producing aramid III fiber by gel spinning method, which belongs to the technical field of chemical synthetic fiber.

Background technique

Aramid III polymer is formed by polycondensation of terephthaloyl dichloride, p-phenylenediamine, and 5(6)-amino-2-(4-aminophenyl) benzimidazole. The polymer passes After spinning, it is made into high-performance aramid fiber III. Aramid III fibers have excellent properties of high strength, high modulus, high temperature resistance, and corrosion resistance. They are often used in the manufacture of fiber-reinforced composite materials, and are widely used in aircraft components, armor bulletproof, individual protection, advanced motor vehicles and other applications.

The currently disclosed aramid III fiber spinning technologies include wet spinning, dry spinning, and dry-wet spinning methods, among which only the wet spinning method is truly industrialized in China. Chinese patent 201010108545.6 discloses a high-performance heterocyclic aramid fiber and its preparation and application. It uses a wet spinning method. The wet spinning steps include: spinning, coagulation, plasticizing and stretching, washing, oiling, and drying , heat treatment, surface treatment and other steps. Although the aramid III fiber manufactured by this technology not only has excellent performance, but also has been recognized by the market. However, the wet spinning technology of aramid III has a slow spinning speed and low production efficiency, resulting in high fiber production costs, making it difficult to obtain large-scale application and promotion of fibers.

Chinese patent 201010192686.0 discloses a method for preparing aramid fiber III, including: (1) Synthesizing spinning dope: using p-phenylenediamine, terephthaloyl chloride and 5(6)-amino-2-(4- Aminophenyl) benzimidazole three monomers are used as raw materials, and dimethylacetamide/lithium chloride is used as a solvent for low-temperature copolymerization; (2) the dry spinning process is used for spinning, and the spinning stock solution obtained in the previous step is passed through After the spinneret enters the thermal inert gas tunnel directly, the solvent in the spinning stock solution is evaporated and removed by the thermal inert gas to obtain solidified raw silk; (3) After the raw silk is washed with water and heat-treated, it is wound to obtain aramid fiber III Fiber. The method is dry spinning, the spinning stock solution has a high solid content, the spinning speed is fast, the spinning efficiency is greatly improved, the fiber manufacturing cost is significantly reduced, and the mechanical properties of the prepared aramid fiber III are improved, which has wide application prospect. However, due to practical problems such as process maturity and engineering difficulty, this technology has not seen industrial application.

Chinese patent 201310494249.8 discloses a dry jet-wet spinning method for manufacturing aramid III fiber developed by China Blue Chenguang Chemical Research and Design Institute on the basis of wet spinning technology. Although this invention has greatly improved the spinning speed and production efficiency of aramid III fiber, effectively reduced the cost of fiber production, and the manufactured fiber has excellent performance and appearance quality, and is cost-effective, but it still needs to be improved in terms of fiber performance. Further improve.

Gel spinning, also known as gel spinning, belongs to the category of solution spinning. During spinning, the spinning dope basically has no solvent diffusion during the solidification and forming process, and only heat exchange occurs, so the as-spun fibers contain a large amount of solvent and are in a gel state. So far, the technology of gel spinning has become more and more mature, and it plays an important role in the production of high-strength and high-modulus fibers. PVA fibers, PTFE fibers, and UHMWPE fibers produced by the gel method have been widely used in various fields. The relevant patent documents are as follows:

Chinese patent 200980146604.4 discloses a gel spinning method for preparing UHMWPE fibers, the method comprising the following steps: a) feeding the slurry containing UHMWPE and spinning solvent to the extruder; Converting in the machine to a solution of UHMWPE in spinning solvent; c) passing the solution of step b) through a spinneret comprising a plurality of spinneret holes to spin fluid UHMWPE fibers; d) cooling the fluid UHMWPE fibers to form a gel UHMWPE fibers; e) at least partially removing the spinning solvent from the gelled UHMWPE fibers; and f) drawing the UHMWPE fibers in at least one drawing step before, during or after removing the spinning solvent, the spinneret per cm ² with up to 6 spinneret holes.

Chinese patent 201110223871.6 discloses a method for manufacturing ultra-high molecular weight polyethylene fiber gel spinning, the ultra-high molecular weight polyethylene powder and solvent are preliminarily treated by a twin-screw extruder under certain conditions to obtain an extrusion liquid; The above-mentioned extruded liquid is processed again by a single-screw extruder under certain conditions to obtain extruded materials; the above-mentioned extruded materials are subjected to spinning, static equilibrium, extraction, preliminary stretching, and super-stretching under certain conditions and other processes to obtain ultra-high molecular weight polyethylene fiber gel spinning. The invention solves the problem that in the process of the existing ultra-high molecular weight polyethylene fiber gel spinning process, excessive high temperature and high shear force are used to make the molecular chain ultra-high orientation, which leads to serious degradation of the molecular chain and low screw efficiency. The problem is that the spinnability of the fiber stream is greatly improved, its molecular orientation is improved, and its strength and toughness are enhanced.

However, there has been no relevant report on the production of aramid Ⅲ fiber by gel method.

Contents of the invention

The purpose of the present invention is to provide a method for continuously and stably manufacturing aramid III fiber products by using known polymerization solution as raw material and adopting gel spinning technology. The method can not only effectively increase the spinning speed, but also further improve the mechanical properties of the fiber, and realize the simultaneous improvement of production efficiency and product performance.

For realizing above-mentioned purpose of the invention, the technical scheme that the present invention adopts is as follows:

A method for producing aramid fiber III fiber gel spinning, characterized in that the process steps are as follows:

A. The spinning stock solution is metered by the metering pump and extruded through the spinneret to form a thin stream into an air layer with a height of 5-30mm;

B. The thin stream extruded through the air layer enters the low-concentration first-stage coagulation liquid to become a gel fiber, and the fiber adopts negative stretching in the first-stage coagulation liquid, and the negative stretch rate is -40~-90%;

C. The gel fiber enters the second-stage coagulation solution with a higher concentration, undergoes plasticization and stretching, and at the same time further solidifies to form a fiber with an aggregated primary structure. The gel fiber is plasticized in the second-stage coagulation solution. Stretch, the positive stretch rate is 80-160%;

D. The aramid fiber III fiber with aggregated primary structure formed by secondary solidification is obtained through washing, oiling and drying processes to obtain the aramid fiber III fiber precursor;

E. Aramid III fiber precursors become finished fibers after heat setting treatment.

The intrinsic viscosity of the spinning dope polymer described in step A is 5-9 dL/g. Within this range of intrinsic viscosity, the production efficiency will not decrease due to the decrease of polymer solubility due to too large intrinsic viscosity; nor will the fiber performance be reduced due to too small intrinsic viscosity.

The air layer of the height described in step A can avoid the problem that the thin stream extruded from the spinneret is seriously affected by the air flow and the problem of easy merging due to the high height of the air layer; Affected by coagulation liquid fluctuations, resulting in unstable spinning. Among them, the height of the air layer is preferably 10 to 20 mm.

The first-stage coagulation liquid described in step B is a mixed liquid of an organic solvent and water. The organic solvent is any one of ethanol, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

The content of the organic solvent in the first stage coagulation liquid is 1-20%wt. If the organic solvent content is too high, the coagulation effect of the thin stream extruded from the spinneret in the coagulation liquid will be deteriorated, which is not conducive to the implementation of the subsequent stretching and orientation process. Wherein the organic solvent content in the first stage coagulation liquid is preferably 5-15%wt.

Under the negative stretching ratio of -40～-90% described in step B, neither will cause the spinneret to extrude fine flow to form the gel state to have a deteriorating influence because of negative stretching ratio too; If the negative stretch ratio is too small, the fiber cannot be drawn and spun normally.

The second-stage coagulation liquid described in step C is a mixed liquid of an organic solvent and water having the same composition as that of the first-stage coagulation liquid. The organic solvent is any one of ethanol, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

The content of the organic solvent in the second-stage coagulation liquid is 20-40%wt. If the organic solvent content in the second-stage coagulation liquid is too low, the stretchability of the gel fiber will be reduced, thereby affecting the fiber performance; if the organic solvent content is too high, it will cause a difference in the concentration of the solvent in the coagulation liquid and the gel fiber If it is too large, the coagulation effect will be deteriorated, and the high content of organic solvent will also increase the load of the subsequent washing process, so it is difficult to completely remove the impurities in the primary fiber. Wherein the organic solvent content in the second-stage coagulation liquid is preferably 25-35%wt.

Under the positive stretch ratio of 80% to 160% described in step C, the structural performance of the finished fiber will not be affected because the draw ratio is too low; and the spinning ratio will not be deteriorated due to too high draw ratio. The stability of the silk process will affect the fiber quality.

The washing water used in the washing step in step D is deionized water, and the temperature is 80-95°C. If the temperature is too low, the washing effect will not be good.

The heat setting treatment described in step E is a conventional heat treatment method, or a method combining heat treatment and heat stretching.

The heat treatment and heat stretching devices are conventional tunnel equipment. The heat treatment temperature is 350-390°C, and the heat-stretching temperature is 390-430°C.

The advantages of the present invention are:

1. Compared with the conventional wet spinning technology, the present invention can greatly increase the fiber spinning speed and improve the fiber production efficiency. The gel spinning speed of the invention reaches 30m/min-100m/min, and while improving the fiber production efficiency, the fiber manufacturing cost is effectively reduced. It has been further proved by practice that the gel spinning method of the present invention is used to produce aramid III fiber, not only is the production process stable, but also the fiber performance and appearance quality are both excellent.

2. The gel spinning technology of the present invention further improves the mechanical properties of fibers. Compared with the fibers made by wet spinning technology, the mechanical properties of aramid III fibers made by gel spinning technology are better, reaching 5.8GPa. In the present invention, the fine stream extruded from the spinneret quickly forms a gel in the first-stage coagulation liquid, then enters the second-stage coagulation liquid to fully stretch and solidify to form, and solidifies into an aggregated primary structure. Stability and fiber product quality are effectively improved.

3. The fiber appearance state produced by the method of the present invention is better. Due to the limitations of the process characteristics of the wet spinning technology, there are grooves on the surface of the produced fibers, and it is difficult to completely avoid the wool phenomenon. The aramid III fiber produced by gel spinning technology has no hair, smooth surface, soft fiber, dispersed monofilament, and better fiber appearance.

Detailed ways

Example 1

A method for manufacturing aramid fiber III fiber gel spinning, the process steps are as follows:

A. The polymer intrinsic viscosity of the spinning stock solution is 6.5dL/g. The stock solution is accurately metered by the metering pump and extruded through the spinneret to form a thin flow into a section of air layer with a height of 15mm;

B, the extruded stream through the air layer enters the low-concentration first-stage coagulation liquid to become a gel fiber; the coagulation liquid is a mixed liquid of ethanol and water, wherein the content of ethanol is 15%wt; Negative stretching is used in the primary coagulation solution, and the negative stretching rate is -80%;

C. The gel fiber enters the coagulation solution composed of the second-stage ethanol and water with a higher concentration, wherein the ethanol content is 30%wt; the gel fiber is plasticized and stretched in the second-stage coagulation solution. The elongation rate is 160%;

D. The aramid fiber III formed by secondary coagulation is washed with deionized water at 80°C, then oiled and dried to obtain the original silk of the aramid fiber III;

E. The fiber precursor becomes a finished fiber after heat treatment and heat stretching; the heat treatment temperature is 350°C, and the heat stretching temperature is 390°C.

The strength of the prepared aramid Ⅲ finished fiber dipped yarn is 5.6GPa.

Example 2

A method for manufacturing aramid fiber III fiber gel spinning, the process steps are as follows:

A. The polymer intrinsic viscosity of the spinning stock solution is 7.2dL/g. The stock solution is accurately metered by the metering pump and extruded through the spinneret to form a thin stream into a section of air layer with a height of 20mm;

B. The extruded fine stream through the air layer enters the low-concentration first-stage coagulation liquid to become a gel fiber; the coagulation liquid is a mixed liquid of N, N-dimethylacetamide and water, wherein N, N -The content of dimethylacetamide is 6%wt; the fiber adopts negative stretching in the first stage coagulation liquid, and the negative stretching rate is -70%;

C, gel fiber enters in the coagulation liquid that the second stage N of higher concentration, N-dimethylacetamide and water form, and wherein N, N-dimethylacetamide content is 35%wt; Gel fiber is in In the second-stage coagulation liquid, the plasticizing positive stretching and orientation operation is carried out, and the stretching rate is 135%;

D. The aramid III fiber formed by secondary coagulation is washed with deionized water at 90°C, then oiled and dried to obtain the aramid III fiber precursor;

E. The fiber precursor becomes a finished fiber after heat treatment; the heat treatment temperature is 380°C.

The strength of the prepared aramid Ⅲ finished fiber dipped yarn is 5.5GPa.

Example 3

A method for manufacturing aramid fiber III fiber gel spinning, the process steps are as follows:

A. The polymer intrinsic viscosity of the spinning stock solution is 8.1dL/g. The stock solution is accurately metered by a metering pump and extruded through a spinneret to form a thin stream into a section of air layer with a height of 10mm;

B. The extruded fine stream through the air layer enters the low-concentration first-stage coagulation liquid to become a gel fiber; the coagulation liquid is a mixed liquid of N, N-dimethylformamide and water, wherein N, N - The content of dimethylformamide is 10%; the fiber is negatively stretched in the first stage coagulation solution, and the negative stretch rate is -55%;

C. The gel fiber enters the coagulation liquid composed of the second stage N, N-dimethylformamide and water with a higher concentration, wherein the N, N-dimethylformamide content is 25%wt; the gel fiber is in In the second-stage coagulation liquid, the plasticizing positive stretching and orientation operation is carried out, and the stretching rate is 110%;

D. The aramid fiber III formed by secondary coagulation is washed with deionized water at 95°C, then oiled and dried to obtain the original silk of the aramid fiber III;

E. The fiber precursor becomes a finished fiber after heat treatment and heat stretching; the heat treatment temperature is 390°C, and the heat stretching temperature is 400°C.

The strength of the prepared aramid Ⅲ finished fiber dipped yarn is 5.8GPa.

Example 4

A method for manufacturing aramid fiber III fiber gel spinning, the process steps are as follows:

A. The polymer intrinsic viscosity of the spinning stock solution is 5.0dL/g. The stock solution is accurately metered by the metering pump and extruded through the spinneret to form a thin stream into a section of air layer with a height of 5mm;

B. The extruded fine stream through the air layer enters the low-concentration first-stage coagulation liquid to become a gel fiber; the coagulation liquid is a mixed liquid of N, N-dimethylformamide and water, wherein N, N -The content of dimethylformamide is 20%wt; the fiber adopts negative stretching in the first-stage coagulation liquid, and the negative stretching rate is -40%;

C. The gel fiber enters the coagulation solution composed of the second-stage N, N-dimethylformamide and water with a higher concentration, wherein the N, N-dimethylformamide content is 40%wt; the gel fiber is in In the second-stage coagulation liquid, the plasticizing positive stretching and orientation operation is carried out, and the stretching rate is 80%;

D. The aramid fiber III formed by secondary coagulation is washed with deionized water at 92°C, then oiled and dried to obtain the original silk of the aramid fiber III;

E. The fiber precursors become finished fibers after heat treatment; the heat treatment temperature is 360°C,

The strength of the prepared aramid Ⅲ finished fiber dipped yarn is 5.3GPa.

Example 5

A method for manufacturing aramid fiber III fiber gel spinning, the process steps are as follows:

A. The polymer intrinsic viscosity of the spinning stock solution is 6.9dL/g. The stock solution is accurately metered by a metering pump and extruded through a spinneret to form a thin stream into a section of air layer with a height of 30mm;

B. The extruded fine stream through the air layer enters the low-concentration first-stage coagulation liquid to become a gel fiber; the coagulation liquid is a mixed liquid of N, N-dimethylacetamide and water, wherein N, N -The content of dimethylacetamide is 1%wt; the fiber is negatively stretched in the first stage coagulation solution, and the negative stretch rate is -63%;

C, gel fiber enters in the coagulation liquid that the second stage N of higher concentration, N-dimethylacetamide and water form, and wherein N, N-dimethylacetamide content is 33%wt; Gel fiber is in In the second-stage coagulation liquid, the plasticizing positive stretching and orientation operation is carried out, and the stretching rate is 105%;

D. The aramid fiber III formed by secondary coagulation is washed with deionized water at 86°C, then oiled and dried to obtain the original silk of the aramid fiber III;

E. The fiber precursor becomes a finished fiber after heat treatment; the heat treatment temperature is 370°C.

The strength of the prepared aramid Ⅲ finished fiber dipped yarn is 5.7GPa.

Example 6

A method for manufacturing aramid fiber III fiber gel spinning, the process steps are as follows:

A. The polymer intrinsic viscosity of the spinning stock solution is 9.0dL/g. The stock solution is accurately metered by the metering pump and extruded through the spinneret to form a thin stream into a section of air layer with a height of 19mm;

B. The extruded stream through the air layer enters the low-concentration first-stage coagulation liquid to become a gel fiber; the coagulation liquid is a mixed liquid of N-methylpyrrolidone and water, wherein the content of N-methylpyrrolidone It is 13%wt; the fiber is negatively stretched in the first stage coagulation solution, and the negative stretch rate is -90%;

C. The gel fiber enters the coagulation solution composed of the second-stage N-methylpyrrolidone and water with a higher concentration, wherein the content of N-methylpyrrolidone is 20%wt; the gel fiber is plasticized in the second-stage coagulation solution Normalized stretching and orientation operation, the stretching rate is 136%;

D. The aramid III fiber formed by secondary coagulation is washed with deionized water at 90°C, then oiled and dried to obtain the aramid III fiber precursor;

E. The fiber precursor becomes a finished fiber after thermal stretching; the thermal stretching temperature is 430°C.

The strength of the prepared aramid Ⅲ finished fiber dipped yarn is 5.8GPa.

Claims (10)

1. A method for making aramid fiber III fiber gel spinning is characterized in that the process steps are as follows: A. The spinning stock solution is metered by the metering pump and extruded through the spinneret to form a thin stream into an air layer with a height of 5-30mm; B. The thin stream extruded through the air layer enters the low-concentration first-stage coagulation liquid to become a gel fiber, and the fiber adopts negative stretching in the first-stage coagulation liquid, and the negative stretch rate is -40~-90%; C. The gel fiber enters the second-stage coagulation solution with a higher concentration, undergoes plasticization and stretching, and at the same time further solidifies to form a fiber with an aggregated primary structure. The gel fiber is plasticized in the second-stage coagulation solution. Stretch, the positive stretch rate is 80-160%; D. The aramid fiber III fiber with aggregated primary structure formed by secondary solidification is obtained through washing, oiling and drying processes to obtain the aramid fiber III fiber precursor; E. Aramid III fiber precursors become finished fibers after heat setting treatment. 2. The gel spinning method for producing aramid III fiber according to claim 1, characterized in that: the intrinsic viscosity of the spinning dope polymer described in step A is 5-9 dL/g. 3. The gel-spinning method for producing aramid fiber III according to claim 1, characterized in that: the height of the air layer in step A is 10-20 mm. 4. manufacture aramid fiber III fiber gel spinning method according to claim 1, it is characterized in that: the first stage coagulation liquid described in step B is the mixed solution of organic solvent and water, and described organic solvent is Any one of ethanol, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone. 5 . The gel spinning method for manufacturing aramid III fiber according to claim 4 , characterized in that: the content of the organic solvent in the first-stage coagulation liquid is 1-20%wt. 6. The gel-spinning method for producing aramid III fiber according to claim 4 or 5, characterized in that the organic solvent content in the first-stage coagulation liquid is preferably 5-15%wt. 7. The gel spinning method for producing aramid fiber III fiber according to claim 1, characterized in that: the second-stage coagulation liquid described in step C adopts an organic solvent and water having the same composition as the first-stage coagulation liquid The mixed solution; the organic solvent is any one of ethanol, N, N-dimethylacetamide, N, N-dimethylformamide, and N-methylpyrrolidone. 8. The gel-spinning method for producing aramid III fiber according to claim 7, characterized in that: the content of the organic solvent in the second-stage coagulation liquid is 20-40%wt. 9. The gel spinning method for producing aramid III fiber according to claim 7 or 8, characterized in that the organic solvent content in the second-stage coagulation liquid is preferably 25-35%wt. 10. manufacture aramid fiber III fiber gel spinning method according to claim 1, it is characterized in that: The washing water used in the washing step in step D is deionized water, and the temperature is 80-95°C.