Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1993-04-30
1996-04-02
Hampton-Hightower, P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
528125, 528126, 528172, 528173, 528179, 528185, 528192, 528336, 528337, 528341, 528345, 528348, C08G 6300, C08G 7500
Patent
active
055041825
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Thermoplastically processable aromatic polyether amide
The invention relates to thermoplastically processable aromatic polyether amides laving a high heat distortion point, their preparation via solution or melt condensation, and their use for the production of shaped articles, filaments, fibers, films and coatings.
Aromatic polyamides are a known class of high performance polymers (Coprehensive Polymer Sci. Vol. 5, page 375 (1989), Encyclopedia of Polymer Science Vol. 11, page 381 (1986); U.S. Pat. Nos. 3,063,966; 3,671,542 and GB 1,246,168).
Aromatic polyamides are generally highly crystalline polymers which often cannot be melted without decomposition and which lave high glass transition temperatures. They have excellent mechanical, thermal and chemical properties. The aromatic polyamide of terephthalic acid and p-phenylenediamine (formula 1) ##STR2## thus has very good mechanical properties and is comparable to steel on a weight basis.
However, an essential disadvantage of these materials is that they are very difficult and expensive to process. Because of the high crystallinity, the melting point (about 550.degree. C.) is far above the decomposition temperature (about 350.degree. C.), so that thermoplastic processing by standard techniques such as extrusion or injection molding is not possible.
The only possible method is therefore processing to give fibers or films from solution. Aggressive media, such as concentrated sulfuric acid, chlorosulfonic acid or nitrogen-containing solvents, such as N-methylpyrrolidone or dimethylacetamide with considerable additions of salts (up to 6% by weight) are often the only media which can be used for this purpose (DE-A-22 19 703). The content of inorganic concomitant substances, determined by ash analysis, is typically several thousand ppm in this process (C. O. Pruneda, R. J. Morgan, R. Lim, J. Gregory, J. W. Fischer, "The Impurities in Kevlar 49 Fibers", SAMPE Journal, Sept./Oct. 1985, 17).
A better solubility can be achieved by incorporation of meta-linkages, for example by reaction of isophthaloyl chloride with m-phenylenediamine (U.S. Pat. No. 3,063,966). Although these polyamides (formula 2) ##STR3## have a better solubility, they cannot be processed thermoplastically.
Thermoplastic processing is an essential prerequisite for wide use as a polymeric material.
In DSC (differential scanning calorimetry), amorphous polymers exhibit a glass transition temperature which indicates the start of cooperative chain mobility. Just above the glass transition temperature, however, the viscosity of the melt is so high (>10 000 Pa.s), that processing by injection molding or extrusion is not possible. Only as the temperature increases further does the melt viscosity fall to the values necessary for this processing. The processing range for amorphous polymers is typically at least 100.degree. C. above the glass transition temperature, for example polyether sulfone having a glass transition temperature of 225.degree. C. is processed by injection molding at 340.degree.-360.degree. C.
Partly crystalline polymers exhibit a melting peak in DSC, in addition to a glass transition point. Processing via the melt is therefore possible only above the melting point. The processing temperatures are typically about 10.degree.-50.degree. C. above the melting point.
The desired decrease in melt viscosity can be achieved--above all in the case of amorphous polymers--by increasing the temperature. However, this is counteracted by the limited thermal stability of the polymers. Although polymers can often be converted into the liquid state by increasing the temperature, processing from the melt is thus not always implicitly associated with this. For processing via injection molding or extrusion under the usual conditions in practice, it is necessary for the material to undergo practically no change in melt viscosity, for example by degradation or crosslinking, over a prolonged period of time at the processing temperature.
There has been no lack of attempts to prep
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Sample Journal, The Impurities in Kevlar 49 Fibres, Sep./Oct. 1985, pp. 17-20.
Encyl. Polym. Sci, Polyamides Aromatic, 1986, vol. 11, pp. 381-409.
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Cherdron Harald
Herrmann-Schonherr Otto
Kreuder Willi
Schneller Arnold
Hampton-Hightower P.
Hoechst Aktiengesellschaft
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