Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/26—Polyamides; Polyimides
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
  • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
  • C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
  • C08G69/32—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids from aromatic diamines and aromatic dicarboxylic acids with both amino and carboxylic groups aromatically bound
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/10—Polyamides derived from aromatically bound amino and carboxyl groups of amino-carboxylic acids or of polyamines and polycarboxylic acids
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
  • D01F6/60—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides
  • D01F6/605—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides from aromatic polyamides

Definitions

• the present invention relates, in general, to a method for preparing wholly aromatic polyamide pulp and, more particularly, to reuse of polymerization solvent as a heating medium for ageing.
• Wholly aromatic polyamide pulp is typically prepared through polymerization, ageing, extraction and pulverization. Among them, ageing is recognized to be one of the most important process for determining the quality of wholly aromatic polyamide pulp.
• U.S. Pat. No. 4,511,623 discloses a method in which a polymer is produced by polymerizing in the presence of pyridine and then, aging by standing it for at least 5 hours at ordinary temperatures.
• wholly aromatic polyamide pulp is prepared by conferring an orientation on a prepolymer with a porous die, ageing the oriented prepolymer at 25-60 "C for 90 minutes in air or a nitrogen atmosphere while cutting it at a time between 2 and 8 minutes after the start of ageing, placing the resulting prepolymer in a solidifying solution and pulverizing it.
• the hydrogen chloride gas contained in the reclaimed nitrogen should be neutralized by use of acid-base reaction, followed by the removal of the moisture which is produced during neutralization.
• the removal of moisture from the reclaimed nitrogen in an industrial scale if possible, requires a considerable amount of energy. That is, when employing nitrogen, a large amount of nitrogen with high temperature is charged continuously and considerable energy cost is needed to reclaim it.
• NMP N-methyl-2- pyrrolidone
• the ageing process of polymerized and oriented wholly polyamide is very important because its molecular weight and crystallinity increase with the development of fibril during the process.
• heating is critical. Dry air or nitrogen gas may be used as a heating medium in a laboratory scale but it is not preferable to use it on an industrial scale because of the above-mentioned problems.
• Microwaving may be employed as a heating means for ageing but it has a higher possibility of explosion. Thus, the industrial application of microwaving is improper.
• the present inventors have researched and made various experiments on the preparing methods of wholly aromatic polyamide pulp comprising the step of conferring an orientation to the polymer just before gelation, ageing and pulverizing the gel, with an expectation that if the solvent used in the polymerization is employed as a heating medium for ageing oriented gel, it might not adversely affect the polymerization by swelling the polymerized and oriented gel, so that the polymerization solvent can simply and economically be reclaimed without additional facilities.
• the matter of grave concern to the present inventors is that the heating medium might have a considerable ill influence on the crystallinity of polymer and the development of fibril.
• a method for preparing wholly aromatic polyamide pulp which comprises conferring an orientation to the polymer just before gelation of the polymer and ageing the gel, wherein the polymerization solvent is used as a heating medium for the ageing.
• a heating medium for ageing is a typical polymerization solution used to prepare aromatic polyamide pulp, with preferred examples including N-methyl-2-pyrrolidone (NMP), N,N'-dimethylacetamide ( DMAc ) , N , N ' - di me thy1 fo rm am id e ( DMF) , hexamethylenephosphoamide (HMPA) and the combinations thereof.
• NMP N-methyl-2-pyrrolidone
• DMAc N,N'-dimethylacetamide
• DMF N ' - di me thy1 fo rm am id e
• HMPA hexamethylenephosphoamide
• the danger of explosion in the ageing process can be excluded.
• NMP which may explode at a particular concentration in air
• there is no danger of explosion because it does not evaporate in the air owing to its high boiling point, 203 ⁇ C.
• a single amide solvent or the mixture of amide solvents may be used as a heating medium for the ageing, alone or in combination with inorganic salts, Lewis acids or the mixtures thereof.
• Useful inorganic salts include alkali metal salts and alkaline earth metal salts.
• Preferred alkali metal salts include alkali metal halides, such as LiCl, NaCl, KCl, LiBr, and KBr, and preferred alkaline earth metal salts include alkaline earth metal halides, such as CaC ⁇ .
• the ageing time if affected by the thickness and temperature of the gel to be treated, generally ranges from 2 to 30 minutes.
• the ageing of a gel about up to 3 cm thick can be finished in 30 minutes with the polymerization solvent while a gel with a thickness of not more than 1 cm can be treated in 20 minutes or less.
• the gel with a thickness of 2 mm or less can age in a short time ranging from 1 sec to 10 min.
• the factor critical in determining the ageing time is not the length to the oriented direction but the thickness or width perpendicular to the oriented direction. Preferred is less than 3 cm in the thickness or width perpendicular to the oriented direction. Gels with a large thickness or width can be aged without any problems other than a long ageing time.
• an oriented gel is cut to the oriented direction to make it relatively long. Particularly preferred is to cut gel in a length of 1 cm or longer to the oriented direction.
• the heating medium for the ageing ranges from 30 to 100 "C and preferably from 35 to 70 * C. It is important to maintain the heating medium at a temperature as high as or higher than that of gel.
• Moisture content in the heating medium for the ageing plays an important role.
• a moisture content higher than 10 % causes the resulting pulp to have a somewhat lowered polymerization degree, the reason of which is that its polymerization ceases as soon as the surface portion of the oriented gel comes into contact with moisture.
• the gel is restricted to have a moisture content of up to 5 % and preferably up to 3 %.
• the heating media have a moisture content of at least 10 ppm.
• the thermal conduction rate is faster than the diffusion rate of water into the oriented gel.
• the use of the polymerization solvent as a heating medium for the ageing can be applied to all processes that comprise the orienting of wholly aromatic polyamide pulp during its polymerization and the ageing thereof.
• a prepolymer is prepared with a continuous kneader, oriented in batch and subjected to ageing
• a process in which a prepolymer is prepared with a continuous kneader, oriented on a belt and subjected to ageing can adopt the method according to the present invention.
• the polymerization solvent can be used as a heating medium for the ageing in a process in which a continuous kneader is cleaned out by itself and equipped with a nozzle at its end and an orientation is conferred to polymer by extrusion spinning it from the nozzle.
• a heating medium for ageing, exclusive of explosion can be reclaimed simply and economically without installing additional facilities, according to the present invention.
• the method according to the present invention may not adopt processes of the regeneration of nitrogen and the removal of moisture.
• the increase of inherent viscosity and crystallinity and the development of fibril are achieved together in the present invention, so that wholly aromatic polyamide pulp with excellent physical properties can be prepared at a low cost.
• Microfibril Observation can be done with an electron scanning microscope or optical microscope.
• An X-ray analyzer is used for the observation of orientation degree in molecular level.
• the degree of orientation in pulp, the final article is difficult to measure.
• the orientation degree of the pulp was observed with an X-ray analyzer after it was aged and dried.
• ⁇ rej is a relative viscosity obtained by measuring the relative retention time at 30 "C of a solution in which 0.5 g of a sample is dissolved in 100 ml of sulfuric acid, and C represents the concentration of the sample solution.
• Crystallinity, Crystal Size, Orientation Angle of Crystal They were measured with an X-ray diffractometer by reference to BLADES disclosed in U.S. Pat. No. 3,869,430. Orientation angle and Crystal size were determined on the (110) face.
• CSF Canadian Standard Freeness
• Example II Polymerization and orientation were achieved in the same manner as that of Example I, except that 30 g of CaCl2 was dissolved in 500 ml of NMP. At the time of ageing the solution was 300 g in weight and after the ageing it was 290 in weight. It was certificated that NMP was extracted. The final pulp had an IV of 4.9 and a crystallinity of 51 %.
• a polymerization solvent was prepared by completely dissolving 80 kg of CaCl 2 in 1000 kg of NMP at 80 * C.
• 48.67 kg of para-phenylene diamine was added and dissolved, to give a solvent premix, also known as an amine solution.
• This amine solution the temperature of which was adjusted into 5 °C was added into a mixer at a speed of 1128.67 g/min with a quantitative pump.
• molten terephthaloyl chloride was added into the mixer at a speed of 27.41 g/min and mixed, to prepare primary polymer.
• the primary polymer was cooled into 5 °C and charged into a continuous reaction kneader at a speed of 1156.08 g/min, during which molten terephthaloyl chloride was also charged at a speed of 63.95 g/min.
• the first kneader was 2 inches (about 5.08 cm) in diameter and showed a retention time of 5 seconds with a jacket warmed to 35 'C whereas the second continuous reactor was 6 inches (about 15.24 cm) in diameter and showed a retention time of about 2 min. with a temperature of 35 °C.
• vapor was drained at the middle upper cover of the 6 inch kneader. While polymerization proceeded, the viscosity increased with polymerization, yielding so-called prepolymer.
• the prepolymer was continuously output from the 6 inch kneader at the end of which a nozzle was not amounted.
• the prepolymer had a temperature of 42 ⁇ C and an IV of 2.2.
• the extruded gel went through an air layer into an ageing bath 1 m in length which contained NMP heated into 80 °C. After 5 minutes in the ageing bath, a thread of gel was removed therefrom and measured for orientation angle. It was 22 ' , an excellent orientation degree.
• the gel was pre-chopped and then, pulverized with a disc mill. The pre-chopping was performed by use of a 12 inch (about 30.48 cm) disc mill, such as that sold by Andritz Sprout Bauer Co. Ltd., and a plate of spike type. For the pulverization, a 12 inch disc mill, commercially available from Andritz Sprout Bauer Co. Ltd., and a plate, such as that sold by the same company, identified as D2A507, were used.
• the concentration of the slurry on the disc mill was about 1 %.
• the first interval was 5 mils (about 0.127 mm) while the second was about 2 mils (about 0.05 mm).
• the pulp thus obtained was 10.2 ⁇ r/g in specific surface area when measured by nitrogen absorption. It had an IV of 4.5 and a crystallinity of 49 %.
• a prepolymer was prepared in the same manner as that of Example III.
• the temperature was 32 °C for the 6 inch kneader and 38 °C for the prepolymer passed through the nozzle. And, the prepolymer had an IV of 2.0.
• a bath 5 m long which contained a CaC ⁇ solution in NMP, the polymerization solvent. This solvent was maintained at 70 °C and had a moisture content of 7 %. The retention time in the bath was 2 min.
• the final pulp had an IV of 4.6, a crystallinity of 55 % and was 53 Angstrom in crystal size of (110) face.
• Example IV A procedure was carried out in a manner similar to that of Example IV, except that the solution temperature in the bath was 120 °C and the retention time was 5 minutes. The sample in the course of solvent extraction was dried and measured for orientation angle, which was identified as 20 degrees. The final pulp had an IV of 4.3 and a crystallinity of 41 %.
• Example IV A procedure was carried out in a manner similar to that of Example IV, except that the solution temperature in the bath was 100 "C, the moisture content in the bath was 20 % and the retention time was 3 minutes. The sample in the course of solvent extraction was dried and measured for orientation angle, which was identified as 25 degrees. The final pulp had an IV of 3.5 and a crystallinity of 40 %.
• Example III was repeated using a batch-type orienting machine for orientation which was equipped with a screw- type interior impeller.
• a gel was separated from the batch-type orienting machine and cut into a size of 5cm x 5cm x 5cm, followed by the immersion in NMP which had a temperature maintained at 70 "C and a moisture content of 300 ppm.
• the retention time was 10 minutes.
• the gel was washed by being immersed in water, to extract the polymerization solvent. Thereafter, the gel was subjected to pulverization in the same manner as that of Example III, to give pulp.
• Its IV and CSF were measured and identified to be 3.6 and 740 ml, respectively, which were known to be insufficient. Consequently, retention time of 10 minutes cannot provide a desirable ageing degree.
• the gel obtained in the batch-type orienting machine was whole immersed in NMP for ageing. Two hours were needed to confer good physical properties to the final pulp. After being aged for two hours, the gel was pulverized in the same manner as that of Example III, to obtain pulp, which had an IV of 4.6, a crystallinity of 49 % and a CSF of 420 ml.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Paper (AREA)
• Polyamides (AREA)
• Artificial Filaments (AREA)

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• 1995
  • 1995-11-03 KR KR1019950039631A patent/KR970027518A/ko not_active Application Discontinuation
  • 1995-12-27 CN CN95197218A patent/CN1171828A/zh active Pending
  • 1995-12-27 EP EP95941913A patent/EP0801699A1/en not_active Withdrawn
  • 1995-12-27 WO PCT/KR1995/000175 patent/WO1997016596A1/en not_active Application Discontinuation

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