Classifications

• • 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
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
  • C08G73/14—Polyamide-imides
• • 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
  • D01F6/74—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles

Definitions

• the present invention relates to a process for making bright yarns which are homogeneous and stable at high temperature by spinning a copolymer containing amide-imide linkages and imide linkages and to the filaments and fibers thus obtained.
• a process is disclosed in US. Pat. No. 3,415,782 for making bright filaments having a base of polypyromellitiimide of good longitudinal and transverse strength by the dry-spinning of a solution of a polyamide-acid obtained from pyromellitic dianhydride and bis(amino- 4-phenyl) ether or bis (amino-4-phenyl) sulfide and then transforming the polyamide-acid into polyimide by subsequently heating the resulting filaments.
• a process has the disadvantage of being rather complicated technically because dry-spinning requires extensive apparatus and high evaporation-cell temperatures.
• polyamide-imide yarns prepared by heretofore .available wet-spinning processes are heterogeneous
• Another object of the invention is to provide an imacid groups in a polar organic solvent therefor into a solvent-non-solvent coagulating bath.
• the unreacted carboxyl groups in the copolymer should be equivalent to at least 0.5 acid milliequivalent per gram of dry copolymer.
• the inherent viscosity of the copolymer should be between 0.7 and 1.5.
• the copolymer may be prepared by reacting at a temperature of less than 80C in a polar organic solvent, a polyamide-imide and a polyamide-acid containing reactive isocyanate' groups.
• the copolymer contains to 50% polyamide acid.
• the spun copolymer after coagulation is drawn in air at room temperature, washed and dried by conventional methods and overdrawn at an elevated temperature.
• the dried product may be heat treated by a conventional method, if desired, before overdrawing.
• a solution of copolymer having an inherent viscosity of between 0.7 and 1.5 which is suitable for wetspinning may be prepared in accordance with this invention by mixing a solution of polyamide-imide with a separately prepared fresh solution of polyamide-acid prepolymer but it is preferably prepared by forming the 5 polyamide acid in situ in a solution of previously prepared polyamide-imide. The high viscosity of the copolymer tends to establish that a branched and/or sequential copolymer is obtained.
• the polyamide-imide may be prepared by reaction in substantially stoichiometrieal proportions in anhydrous polar organic solvent of at least one aromatic diisocyanate with an acid reagent formed of an aromatic acid anhydride and possibly a small proportion of an aromatic diacid, for example, up to terephthalic acid or the like.
• the polyamide-imide obtained has the following amide-imide linkages:
• R represents an aromatic divalent radical
• Ar represents a divalent aromatic radical
• Ar represents a trivalent aromatic radical having at least 6 carbon atoms.
• aromatic diisocyanate Any suitable aromatic diisocyanate may be used.
• Preferred diisocyanates are 4,4'-diisocyanato-diphenyl methane, 4,4-diisocyanatodiphenyl ether, 4,4-
• diisocyanato-diphenyl propane 2,4-toluylene diisocyanate, meta phenylene diisocyanate, para phenylene diisocyanate, 1,5-naphtylene diisocyanate and the like.
• Suitable acid anhydrides include trimel'litic anhydride and among the suitable aromatic diacids, terephthalic acid isophthalic acid, 4,4'-dicarboxy diphenyl methane, 4,4'- dicarboxy diphenyl ether, 4,4- dicarboxy diphenyl sulfone, 4,4'-dicarboxy diphenyl benzophenone, 4,4'-dicarboxy diphenyle are particularly well suited.
• the reaction takes place at a temperature which can range, for instance, from 80 up to 180C and even more.
• a preferred method of preparation consists in gradually raising the temperature of the reaction medium, for instance, for l to 3 hours and then maintaining this temperature for a period of time which may vary from 1 to 4 hours.
• the reaction takes place in an anhydrous polar organic solvent, preferably N-methyl pyrrolidone, so as to obtain a polymer concentration in the solution of between 18 and 35% by weight, and preferably between 22 and 28%, without taking into consideration a possible dilution at the end of the operation.
• an anhydrous polar organic solvent preferably N-methyl pyrrolidone
• the inherent viscosity of the polyamide-imide obtained is generally between 0.5 and 1.2 and generally close to
• the polyamide-acid prepolymer is obtained by reaction, in substantially stoichiometric proportions in the same organic solvent, of an aromatic diisocyanate (preferably the same that used for preparing the polyamide-imide) with an acid reagent formed of a tetracarboxylic acid dianhydride alone or mixed with the corresponding tetracarboxylic acid in the presence of a small amount of water, which may range up to about 3% by weight, based on the weight of solvent.
• the starting temperature is generally between about 25 and about 40C. It is preferably maintained within these limits for several hours. lt is possible then gradually to increase the temperature without, however, going beyond 80C, which would transform too many amide-acid groups into imide groups.
• the prepolymer then becomes insoluble. its concentration in the solution is generally between and 24%.
• the polyamide-acid solution must necessarily be freshly prepared (in the event that it is prepared separately) so that the polymer contains a maximum number of reactive isocyanate groups. In practice this solution must be used within 24 hours after its preparation.
• the inherent viscosity of the polyamide-acid is generally of the order of about 0.4 to 0.5.
• the copolymer thus obtained has a content of free carboxyl groups greater than 0.5 (this content being expressed in milliequivalents per gram of dry copolymer).
• the best homogeneity and the best characteristics of the yarns are obtained with rates of free carboxyl groups at least equal to 0.6.
• the proportions of polyamide-imide and polyamideacid in the copolymer wet-spun in accordance with the present invention are between 50 and 85% polyamideimide and 15 and 50% polyamidc-acid based on the I weight of copolymer.
• the preferred composition is 80% polyamide-imide and by weight polyamideacid.
• the solvent may be any suitable polar organic solvent such as dimethyl acctamide, tctramethylene sulfone, or the like, preferably N-methyl pyrrolidone.
• N-methyl pyrrolidone is poorly suited for the preparation of polyamide-acids of high molecular weight; on the other hand, it permits good reproducibility of the characteristics of the polyamide-imide and the polya mide-acid; surprisingly, copolymers of high molecular weight are obtained in this solvent. This is why N- methyl pyrrolidone constitutes the preferred solvent in the process claimed.
• the spinning of the solution of the copolymer as described above is earried out in a coagulating bath composed essentially of solvent and non-solvent, generally at room temperature.
• non-solvent for the copolymer which can be used in the coagulating bath mention may be made, for instance, of glycol, acetone, methylene chloride, although water is generally preferred for obvious reasons of economy.
• the filaments are drawn, preferably in air, at a slow rate, and then washed, for instance on rollers, possibly with counter-current flow, and preferably with water, and dried, for instance on rollers, preferably at temperature of about to 300C. Thereupon the yarn is subjected to another drawing at elevated temperature, generally above 300C, and possibly up to 400C, and even beyond, by any means known to the man skilled in the art, for instance, in a tube or on a heating plate.
• amid-acid groups are transformed into imid groups.
• filaments having particularly high mechanical properties, in particular excellent tenacity one can effect a heat treatment before the last drawing, for instance at a temperature of between 200 and 300C.
• the yarns obtained in addition to their brightness, have excellent physical and mechanical properties, and in particular good thermal stability and good non-inflammability.
• the textile applications of the yarns thus obtained are extremely varied protective clothing, equipment, conveyor belts, filtration of hot gases, etc.
• Example 1 There are prepared separately: A. On the one hand, a polyamide-imide solution from a mixture of:
• the two solutions A and B are mixed in different proportions so as to obtain C, D, E, F, G containing l0, 15, 20, 35 and 50% respectively of polyamide-aeid prepolymer.
• each of the solutions is spun separately through a spinneret of 64 holes of a diameter of 0.05 mm into a coagulating bath containing 60% N-methyl pyrrolidone and 4071 water, maintained at room temperature.
• the filaments are then washed with water in countercurrent, at room temperature, and then dried on rollers at 80C and then at 170C, drawn at room temperature, at rates given in Table 1 below. They are then heat treated in an oven for 2 hours at 240C and drawn again at 420C in a tube at rates indicated in Table I below, which sets forth the characteristics of the polymers and of the yarns obtained.
• sample E The heat stability of sample E was evaluated by the loss of strength upon aging. as follows:
• Example 2 A polyamide-imide is prepared from:
• diisocyanato-4A'-diphcnyl ether 32 g pyromellitie dianhydride 27.7 g N-methyl pyrrolidone 104 g water 1.37 g
• the yarn obtained is washed with water on rollers at room temperature, and then dried on two drying rollers of a temperature of and C respectively.
• the yarns After drawing in air at a rate of 1.22, the yarns undergo a second drawing in a tube at 400C, at a rate of 2.50.
• the properties of the yarns are as follows:
• a method for making a non-inflammable heatstable, bright yarn comprising 1. wet-spinning into a coagulating bath a solution in g a polar organic solvent of a copolymer which contains both amide-imide groups and amide-acid 2. The method of claim 1 wherein the copolymer contains from 15 to 50% polyamide-acid.
• polyamideimide is the reaction product of? an aromatic diisocyanate and trimellitie anhydride and the polyamide-acid is the reaction product of an aro matie diisocyanate and pyromellitic dianhydride.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)
• Polyurethanes Or Polyureas (AREA)
• Artificial Filaments (AREA)

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Cited By (1)

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Citations (7)

• 0
  • BE BE787500D patent/BE787500A/xx unknown
• 1971
  • 1971-08-12 FR FR7129799A patent/FR2149020A5/fr not_active Expired
• 1972
  • 1972-08-02 US US277163A patent/US3903058A/en not_active Expired - Lifetime
  • 1972-08-09 BR BR5368/72A patent/BR7205368D0/pt unknown
  • 1972-08-09 NL NL7210893A patent/NL7210893A/xx not_active Application Discontinuation
  • 1972-08-10 JP JP7280333A patent/JPS4827096A/ja active Pending
  • 1972-08-10 GB GB3745572A patent/GB1402559A/en not_active Expired
  • 1972-08-10 IT IT52092/72A patent/IT965975B/it active
  • 1972-08-11 DE DE2239651A patent/DE2239651A1/de active Pending
  • 1972-08-11 LU LU65894A patent/LU65894A1/xx unknown
  • 1972-08-11 NO NO2883/72A patent/NO138217C/no unknown
  • 1972-08-11 CA CA149,308A patent/CA994068A/fr not_active Expired

Patent Citations (7)

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