Increasing the molecular weight of polyamides

Details Increasing the molecular weight of polyamides Increasing the molecular weight of polyamides

1999-04-22

2000-02-15

Boykin, Terressa M.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Treating polymer containing material or treating a solid...

524 99, 524115, 524130, 525419, 525420, 528310, 528322, 528480, 528492, C08F 600

Patent

active

060254637

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a process for increasing the molecular weight and/or viscosity of polyamides and to the polyamides obtainable by the process.
Polyamides are important thermoplastic materials from the engineering plastics group with high strength, rigidity, hardness and heat deformation resistance and a wide variety of potential uses, for example in the form of films, bottles, fibres and injection mouldings. The industrial preparation of polyamides by means of polycondensation reactions leads to polymer chains having functional end groups. Similarly, damage to such polyamides as a result of processing and use leads, owing to chain cleavage, to polymer fragments containing functional end groups.
The mechanical and physical properties are crucially dependent on the molecular weight of the polymer. High-grade recycling of used polyamides and of production waste, for example from fibre production and injection moulding, is only possible to a restricted extent without aftertreatment, owing to the reduced molecular weight. For certain applications, there is also a demand for virgin polyamides of high molecular mass, whose synthesis is difficult or relatively complex.
Increasing the molecular weight of polycondensation polymers such as, for example, polyamides is known in principle. For example, post-condensation in the solid state ("solid state polycondensation") is possible, as is described in "Ullmann's Encyclopedia of Industrial Chemistry Vol. A 21, 5th Edition", page 188 (1992) and is also practised industrially. An alternative method is to build up the molecular weight by means of reactive additives, which is referred to in general as chain extension.
EP-A-0 604 367 discloses a process for increasing the molecular weight of polyamides, which comprises heating a polyamide, with the addition of a polyfunctional epoxy resin and of a sterically hindered hydroxyphenyl-alkyl-phosphonic ester or monoester, at above the melting point or glass transition point of the polyamide.
U.S. Pat. No. 5,496,920 likewise discloses a process for increasing the molecular weight of polyamides, which comprises heating a polyamide, with the addition of a bismaleimide and of a sterically hindered hydroxyphenyl-alkyl-phosphonic ester or monoester at above the melting point or glass transition point of the polyamide.
Among the polyfunctional epoxy resins, a broad selection of commercial products is available. From an economic standpoint, therefore, such epoxides therefore appear particularly appropriate for these reactions. So that the concentration in which they are used can be kept low, difunctional epoxides with a high epoxide content are expedient. Commercial difunctional epoxides of high epoxide content are frequently liquid or low-melting products, whereas the abovementioned sterically hindered hydroxyphenyl-alkyl-phosphonic esters or monoesters are solids. The simultaneous addition of solid and liquid components in connection with increasing the molecular weight of polyamides gives rise to technical problems which can be solved only with complex technical apparatus.
The object of the present invention, therefore, was to provide a system for building up the molecular weight of polyamides, which is highly effective and consists preferably of liquid or homogeneously miscible components, which components are obtainable at economically acceptable expense.
It has now surprisingly been found that a mixture comprising a secondary aromatic amine and a difunctional epoxide is suitable for increasing the molecular weight and/or viscosity of virgin polyamide or recycled polyamide.
The present invention therefore provides a process for increasing the molecular weight and/or viscosity of polyamides, which comprises heating a polyamide, with the addition of a secondary aromatic amine and of a difunctional epoxide, at above the melting point or glass transition point of the polyamide.
The term polyamides, i.e. both virgin and recycled polyamides, refers to aliphatic and aromatic polyamides or copolyamides which are derived from diamine

REFERENCES:
patent: 5496920 (1996-03-01), Pfaendner et al.
patent: 5756596 (1998-05-01), Pfaendner et al.
Ullmann's Encyclopedia of Industrial Chemistry, 5.sup.th Completely Revised Ed., vol. A21, pp. 187-189.
Gachter et al, Plastics Additives Handbook, 3.sup.rd Ed., pp. 43-45.

Affiliated with

Also associated with

Rating

Increasing the molecular weight of polyamides does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Increasing the molecular weight of polyamides, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Increasing the molecular weight of polyamides will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1906912