Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
1998-01-14
2001-07-10
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S049000, C528S052000, C528S310000, C524S589000, C524S590000, C524S871000, C524S873000, C264S289300, C264S184000
Reexamination Certificate
active
06258916
ABSTRACT:
The present invention relates to a process for obtaining thermally stable fibres by spinning in solution of polyamide-imides and to the fibres thus obtained.
According to FR 2,079,785 it is known to manufacture lustrous yarns based on polyamide-imides containing at least 3% of chain sequences originating from an alkali or alkaline-earth metal 3,5-dicarboxybenzenesulphonate by wet spinning from a solution of polymer in N-methylpyrrolidone, into an aqueous bath also containing N-methylpyrrolidone, followed by drawing, washing and drying.
However, besides a strong yellow colouring, such yarns also have inadequate thermomechanical behaviour for some applications.
In addition, according to this patent it is not possible to obtain polyamide-imide fibres with good mechanical properties while employing tolylene and meta-phenylene diisocyanates as initial isocyanate.
To improve the mechanical properties of polyamide-imides fibres have also been prepared, according to FR 2,643,084, which are based on polyamide-imides preferably produced from 4,4′-diphenyl ether diisocyanate. However, such fibres exhibit a low drawability which does not make it possible to gain access to low linear densities.
Furthermore, 4,4′-diphenyl ether diisocyanate is a product to which access is difficult on a commercial scale and which is costly.
The present invention relates to a process for obtaining yarns and fibres based on polyamide-imides by spinning from a solution of a polymer in dimethylalkyleneurea, the polymer comprising:
amide-imide chain sequences (A) of formula:
optionally amide chain sequences (B) of formula:
optionally amide chain sequences (C) of formula: —NH—Ar
1
—NH—CO—R—CO—
imide chain sequences (D) of formula:
in which:
Ar
1
denotes a tolylene and/or meta-phenylene divalent aromatic radical,
Ar
2
denotes a trivalent aromatic radical,
Ar
3
denotes a tetravalent aromatic radical,
R denotes a divalent aromatic radical,
M denotes an alkali metal or alkaline-earth metal,
the chain sequences (A) being present in a proportion of 0 to 100%, preferably 20 to 100%,
the chain sequences (B) being present in a proportion of 0 to 5%,
the chain sequences (C) being present in a proportion of 0 to <100%, preferably 0 to 80%,
the chain sequences (D) being present in a proportion of 0 to <100%, preferably 0 to 80%, the sum of the chain sequences (A)+(B)+(C)+(D) being equal to 100%, in an aqueous coagulating medium containing 30 to 80%, preferably so to 65%, by weight of dimethylalkyleneurea (DMAU),
drawing the filaments obtained to a ratio of at least 2×,
removal of the residual solvent,
drying by any known means,
overdrawing to a ratio of at least 2×, preferably at least 3×, at a temperature of at least 250° C., generally at least 300° C. or even higher, the total draw ratio being at least 5×, preferably at least 6×.
The polyamide-imide employed preferably has an inherent viscosity ≧0.8 dl/g.
The dimethylalkyleneurea employed is preferably dimethylethyleneurea or dimethylpropyleneurea.
The yarns and fibres according to the present invention can also be prepared by dry spinning from a solution at a concentration of 15 to 35%, preferably 20 to 30%, in dimethylalkyleneurea of a polyamide-imide containing the chain sequences of a copolymer A, B, C and D of the formula described above, with Ar
1
, Ar
2
, Ar
3
, R and M having the same meaning, into an evaporation atmosphere maintained at a temperature close to or higher than the boiling point of the solvent, the filaments at the exit of the evaporation vessel being freed from their residual solvent. For this purpose they may be washed with water, optionally boiling and under pressure, and dried in a conventional manner, preferably at a temperature above 80° C. They may also be heat-treated at a temperature ≧160° C. at reduced pressure and/or under inert atmosphere; after being freed from their residual solvent they are drawn at a temperature above 250° C., preferably above 300° C., preferably in the absence of oxygen.
The total draw ratio applied is at least 5×, preferably at least 6×.
Such polymers can be obtained by reaction (a), in substantially stoichiometric proportions and in the absence of catalyst, in an anhydrous polar solvent, of at least one aromatic diisocyanate chosen from 2,4-tolylene or 2,6-tolylene diisocyanate or meta-phenylene diisocyanate with at least one acidic reactant comprising an aromatic acid anhydride, optionally an aromatic dianhydride, optionally an alkali or alkaline-earth metal 3,5-dicarboxybenzenesulphonate, and optionally an aromatic diacid, under the operating conditions described in French Patent Application 1,600,067 filed on Dec. 30, 1968.
These polymers can also be obtained by reaction (b) of the diisocyanate(s) referred to above and of an acidic reactant comprising an aromatic dianhydride, and an aromatic diacid, optionally of an alkali or alkaline-earth metal 3,5-dicarboxybenzene sulphonate, in the absence of aromatic acid anhydride, in stoichiometric proportions and in the absence of catalyst.
When reaction (a) is employed the proportions of the various chain sequences are the following:
chain sequences (A): 20 to 100%
chain sequences (B): 0 to 5%
chain sequences (C): 0 to 80%
chain sequences (D): 0 to 80%
When reaction (b) is employed the proportions of the chain sequences are the following:
chain sequences (A): 0%
chain sequences (B): 0 to 5%
chain sequences (C): 0 to 80%, preferably 0 to 75%
chain sequences (D): 20 to 100%, preferably 20 to 80%.
The sum of the chain sequences (A)+(B)+(C)+(D)=100%.
The diisocyanates which can be employed for obtaining the polyamide-imides are 2,4- or 2,6-tolylene diisocyanates and meta-phenylene diisocyanate or mixtures thereof. In the trade tolylene diisocyanate takes the form of a mixture of 2,4- and 2,6-tolylene (2,4- and 2,6-TDI) isomers. It is preferable that the mixture should consist of at least 60% of 2,4-TDI.
A minor proportion of another aromatic, aliphatic or cycloaliphatic diisocyanate may be optionally added to the abovementioned diisocyanates with the aim of improving certain properties of the manufactured articles, for example, it may be advantageous to replace up to 30% of m-PDI with paraphenylene diisocyanate (p-PDI) to improve the mechanical properties of the fibres obtained.
The acidic anhydride employed is preferably trimellitic anhydride and, as aromatic dianhydride there may be mentioned the dianhydrides of pyromellitic acid, of 3,3′,4,4′-diphenyltetracarboxylic acid, of 2,3,6,7-naphthalenetetracarboxylic acid, of diphenyl ether 3,3′,4,4′-tetracarboxylic acid, of diphenyl sulphone 3,3′,4,4′-tetracarboxylic acid and, preferably, the dianhydride of diphenyl ketone 3,3′,4,4′-tetracarboxylic acid. A number of these dianhydrides may be employed as a mixture; and, among aromatic diacids, terephthalic and isophthalic acids are frequently employed and, although terephthalic acid is preferred, other diacids may be suitable, such as biphenyldicarboxylic or naphthalenedicarboxylic acids. The trimellitic anhydride employed must be pure and in particular must not contain more than 5 mol % of trimellitic acid.
The alkali or alkaline-earth metal 3,5-dicarboxybenzenesulphonate is preferably the sodium or potassium sulphonate.
The various acid or acid anhydride and dianhydride compounds are present in the following molar proportions:
aromatic acid anhydride: from 0 to 100% relative to the total of the acidic reactants, preferably 20 to 100%,
aromatic diacid: from 0 to <100%, preferably from 0 to 80%,
dicarboxybenzenesulphonate in a proportion of 0 to 5%.
aromatic dianhydride: from 0 to <100% relative to the total of the acidic reactants. The polymers thus obtained preferably have an inherent viscosity of at least 0.8 dl/g, preferably at least 0.9 dl/g in order to be capable of being spun and to yield yarns exhibiting good mechanical properties.
Below these viscosity values, which correspond to insufficient molecular m
Michaud Philippe
Perier Marie-Eve
Russo Jean
Rhone-Poulenc Fibres
Stevens Davis Miller & Mosher L.L.P.
Truong Duc
LandOfFree
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