Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1994-06-10
1997-11-04
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528 73, 528 84, 528310, 528322, 528350, 524111, 524211, 524233, 428357, 428395, C08G 7314
Patent
active
056841191
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to solutions of polyamideimides which can be directly spun and processed in .gamma.-butyrolactone. It also relates to the yarns and fibres obtained by solution-spinning of these solutions.
It also relates to a process for obtaining solutions exhibiting an improved colour.
BACKGROUND DISCUSSION
It is already known, according to FR 2,079,785, to prepare solutions based on polyamideimides in N-methylpyrrolidone, but the solutions and the polymers thus obtained exhibit an intense dark colour limiting the possibilities of subsequent colouring of the articles formed from these solutions.
It is also known, according to FR 2,627,497, to prepare directly spinnable solutions based on polyamideimides, by polycondensation in .gamma.-butyrolactone, followed by dilution at a temperature of 120.degree. to 165.degree. C. in another solvent to obtain a polymer concentration of 5 to 30%, the weight proportion of the reaction solvent to the diluent solvent being between 40/60 and 80/20. The use of .gamma.-butyrolactone as solvent for the polycondensation of the polyamideimides, even jointly with a diluent solvent of the amide type, enables the colour of the polyamideimide solutions to be improved. However, such solutions are only of limited interest because it is difficult to avoid completely the precipitation of the polymer after a few months.
In addition, the use of a cosolvent does not promote the elimination of the colour and, during the subsequent conversion of these solutions, the simultaneous presence of two solvents is found to be complicated and relatively uneconomical industrially.
SUMMARY OF THE INVENTION
It has now been found, and this is what forms the subject of the present invention, that it is possible to prepare solutions of polyamideimides in .gamma.-butyrolactone as the only solvent. More particularly, it relates to clear solutions of polyamideimides (PAI) which can be directly spun and processed, containing: ##STR1## in which: Ar.sub.1 denotes the tolylene divalent aromatic radical, butyl alcohol in sufficient quantity to enable solutions to be formed, generally from 5 to 35%.
The solutions according to the present invention are practically free from any undesirable colour.
The present invention also relates to a process for obtaining clear solutions which can be directly spun and processed based on polyamideimides, including the reaction, carried out in substantially anhydrous .gamma.-butyrolactone (.gamma.-BL) free from butyl alcohol as polycondensation solvent, in substantially stoichiometric proportions, between: concentration of polyamideimide in the .gamma.-BL being at least 27%, preferably approximately from 27 to 50%, at a temperature increasing from the ambient to approximately 200.degree. C., and then addition of .gamma.-butyrolactone (.gamma.-BL) to obtain a concentration permitting the subsequent conversion.
The final PAI concentration which is suitable for spinning or filming is generally between 5 and 30%.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The .gamma.-butyrolactone employed must be substantially anhydrous, that is to say it must contain less than 500 ppm of water; it must also be free from butyl alcohol, that is to say it must contain less than 500 ppm of butyl alcohol, to avoid any secondary reaction.
The tolylene diisocyanate (TDI) generally employed is commercial TDI, which is in the form of a mixture of 2,4-TDI and 2,6-TDI in a proportion of at least 60% of 2,4-TDI, preferably 80% of 2,4-TDI and 20% of 2,6-TDI.
A minor proportion of another aromatic diisocyanate may be optionally added to the TDI to improve certain properties of the processed articles obtained.
Trimellitic anhydride will be preferably employed as acid anhydride.
On the other hand, in contrast with the teaching of FR 2,079,785 and FR 2,627,497, the polyamideimides according to the present invention must not contain more than 5% of units originating from other aromatic diacids such as terephthalic acid or an alkali or alkaline-earth metal dicarb
REFERENCES:
patent: 4950700 (1990-08-01), Balme et al.
Patent Abstracts of Japan, vol. 7, No. 273 (C-198) (1418), Dec. 6, 1983, & JP,A,58154728 (Hitachi) Sep. 14, 1983. Copies of Both Documents Are Attached Hereto in English.
Michaud Philippe
Russo Jean
Hampton-Hightower P.
Rhone-Poulenc Fibres
Seidleck James J.
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