Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2003-01-10
2004-11-09
Hightower, P. Hampton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S312000, C528S322000, C528S323000, C528S324000
Reexamination Certificate
active
06815527
ABSTRACT:
DESCRIPTION
The present invention relates to a continuous process for preparing polyamides from aminonitriles and water at elevated temperature and elevated pressure.
DE-A-19804023 discloses a continuous process for preparing a polyamide by reacting at least one aminonitrile with water, which comprises:
(1) reacting at least one aminonitrile with water at from 90 to 400° C. and from 0.1 to 35×10
6
Pa in a flow tube containing a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, to obtain a reaction mixture,
(2) further reacting the reaction mixture at from 150 to 400° C. and a pressure which is lower than the pressure in stage 1 in the presence of a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, the temperature and pressure being selected so as to obtain a first gas phase and a first liquid phase or a first solid phase or a mixture of first solid and first liquid phases and so that the first gas phase is separated from the first liquid phase or first solid phase or from the mixture of first liquid and first solid phases, and
(3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phases with a gaseous or liquid phase comprising water at from 150 to 370° C. and from 0.1 to 30×10
6
Pa, to obtain a product mixture.
This process provides polyamide in good quality, but there is a need for further improvements in quality. One problem with the quality of polyamides is the unwanted formation of secondary amines as described in WO 00/24808.
It is an object of the present invention to provide a process for preparing polyamides from aminonitriles and water that ensures a further quality improvement compared to existing processes.
We have found that this object is achieved according to the invention by a continuous process for preparing a polyamide by reacting at least one aminonitrile with water, which comprises:
(1) reacting at least one aminonitrile with water in the presence of an organic liquid diluent at from 90 to 400° C. and from 0.1 to 35×10
6
Pa in a flow tube containing a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, to obtain a reaction mixture,
(2) further reacting the reaction mixture at from 150 to 400° C. and a pressure which is lower than the pressure in stage 1 in the presence of a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, the temperature and pressure being selected so as to obtain a first gas phase and a first liquid phase or a first solid phase or a mixture of first solid and first liquid phases and so that the first gas phase is separated from the first liquid phase or first solid phase or from the mixture of first liquid and first solid phases, and
(3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phases with a gaseous or liquid phase comprising water at from 150 to 370° C. and from 0.1 to 30×10
6
Pa, to obtain a product mixture.
The invention further provides a continuous process for preparing a polyamide by reacting at least one aminonitrile with water, which comprises:
(1) reacting at least one aminonitrile with water in the presence of an organic liquid diluent at from 90 to 400° C. and from 0.1 to 35×10
6
Pa in a flow tube containing a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, to obtain a reaction mixture,
(2) further reacting the reaction mixture at from 150 to 400° C. and a pressure which is lower than the pressure in stage 1 in the presence of a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, the temperature and pressure being selected so as to obtain a first gas phase and a first liquid phase or a first solid phase or a mixture of first solid and first liquid phases and so that the first gas phase is separated from the first liquid phase or first solid phase or from the mixture of first liquid and first solid phases, and
(3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phases with a gaseous or liquid phase comprising water at from 150 to 370° C. and from 0.1 to 30×10
6
Pa in a flow tube containing a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, to obtain a product mixture.
The above processes preferably further comprise the following step:
(4) postcondensing the product mixture at from 200 to 350° C. and a pressure which is lower than the pressure in stage 3, the temperature and pressure being selected so as to obtain a second gas phase, which contains water and ammonia with or without organic diluent, and a second liquid or second solid phase or mixture of second liquid and second solid phases, which each include the polyamide.
The present invention further provides a continuous process for preparing a polyamide by reaction of at least one aminonitrile with water, which comprises:
(1) reacting at least one aminonitrile with water in the presence of an organic liquid diluent at from 90 to 400° C. and from 0.1 to 35×10
6
Pa in a flow tube containing a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, to obtain a reaction mixture,
(2) further reacting the reaction mixture at from 150 to 400° C. and a pressure which is lower than the pressure in stage 1 in the presence of a Brönsted acid catalyst selected from a beta-zeolite catalyst, a sheet-silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile and in which up to 40% by weight of the titanium dioxide may be replaced by tungsten oxide, the temperature and pressure being selected so as to obtain a first gas phase and a first liquid phase or a first solid phase or a mixture of first solid and first liquid phases and so that the first gas phase is separated from the first liquid phase or first solid phase or from the mixture of first liquid and first solid phases, and
(3) postcondensing the first liquid or the first solid phase or the mixture of first liquid and first solid phases at from 200 to 350° C. and a pressure which is lower than the pressure in stage 2, the temperature and pressure being selected so as to obtain a second gas phase, which contains water and ammonia
Bassler Peter
Fischer Rolf-Hartmuth
Loth Wolfgang
Winterling Helmut
BASF - Aktiengesellschaft
Hampton Hightower P.
Keil & Weinkauf
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