Continuous preparation of polyamides from aminonitriles

Details Continuous preparation of polyamides from aminonitriles Continuous preparation of polyamides from aminonitriles

2000-07-25

2001-11-13

Hampton-Hightower, P. (Department: 1711)

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

Synthetic resins

From carboxylic acid or derivative thereof

Reexamination Certificate

active

06316588

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a continuous process for preparing polyamides from aminonitriles and water at elevated temperature and elevated pressure.
PRIOR ART
U.S. Pat. No. 4,629,776 describes a catalytic process for producing polyamides from &ohgr;-aminonitriles such as &ohgr;-amino-capronitrile (ACN). ACN is reacted with water in the presence of a catalytic amount of an oxidized sulfur compound as catalyst. Sulfuric acid is an example of the catalyst used.
U.S. Pat. No. 4,568,736 describes a similar catalytic process for producing polyamides. The catalyst used in this case is an oxygen-containing phosphorus compound, phosphoric acid or a phosphonic acid.
Complete removal of catalyst is virtually impossible in either process. The presence of catalyst in the polymer can hinder the building of high molecular weight polymers and compromise later processing operations, for example spinning. Moreover, the level of volatiles in the polymers obtained is high, so that the polyamides are difficult to process.
EP-A-0 479 306 describes the production of polyamides from &ohgr;-aminonitriles. The &ohgr;-aminonitriles are reacted with water in the presence of an oxygen-containing phosphorus compound as catalyst. Once a reaction temperature from 200 to 260° C. has been obtained, ammonia and water are continuously removed by decompressing and at the same time water is continuously added, the pressure being selected within the range from 14 to 24×10
6
Pa (14-24 bar).
DE-A-43 39 648 relates to a process for producing caprolactam by reacting aminocarbonitriles with water in the liquid phase using heterogeneous catalysts. Suitable heterogeneous catalysts include acidic, basic or amphoteric oxides of the elements of main groups 2, 3 and 4 of the Periodic Table. Titanium dioxide can be used, for example. The catalyst is used in the form of extrudates, for example.
Existing processes have in some cases inadequate space-time yields and a molecular weight buildup which needs to be improved. In addition, the product is not always obtained in the requisite purity.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for preparing polyamides from aminonitriles and water with an improved molecular weight buildup and an improved space-time yield without contamination of the product compared with existing processes.


REFERENCES:
patent: 2301964 (1942-11-01), Martin
patent: 4568736 (1986-02-01), Curatolo et al.
patent: 4625023 (1986-11-01), Mares et al.
patent: 4628085 (1986-12-01), Mares et al.
patent: 4629776 (1986-12-01), Curatolo et al.
patent: 5646277 (1997-07-01), Fuchs et al.
patent: 5739324 (1998-04-01), Fuchs et al.
patent: 5874575 (1999-02-01), Fuchs et al.
patent: 35 34 817 A1 (1987-04-01), None
patent: 43 39 648 A1 (1995-05-01), None
patent: 44 43 125 A1 (1996-06-01), None
patent: 196 35 077 A1 (1998-03-01), None
patent: 0 479 306 A2 (1992-04-01), None
patent: WO 98/08889 (1998-03-01), None

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