CS197149B1 - Process for preparing polyarylamides of phenylenphthalimide - Google Patents

Description

Polyaramides have become important synthetic materials and their main advantage is the relatively high heat resistance and strength compared to aliphatic polyamides.

The main representatives of polyaramides are the substances obtained by polycondensation of 1,3-phenylenediamine and isophthalic acid (Belg. Pat. 565 266, 565 267 and 565 268 finny Du Pont), to which the constitution is attributed

HOOC

NH ₂

Substance attributed to constitution

is prepared from terephthalic acid dichloride and p-phenylenediamine (Auslegsschrift 22 19 703 from Du Pont).

197 149

197 149

According to the invention, the phenylene phthalamide type polyaremides are produced by interacting phenylenediamines and benzenedicarboxylic acid esters with β alkyls at temperatures of from 200 to 350 ° C.

Of the phenylenediamines, m-phenylenediamine and p-phenylenediamine are suitable. The second component is methyl, o-propyl and butyl esters of isophthalic and terephthalic acids.

The selected diamine and diester are mixed as a rule in a molar ratio of III or with a slight excess of some of the components, and then heated above 200 DEG to 350 DEG C. in the reaction space. at this temperature maintains the specified · «

time or the mixture of components is heated above the melting point of the system, which is usually a temperature range of 150 to 180 ° C and the homogenized mixture is brought to a reaction space of 200 to 350 ° C) this alternative preparation can easily be converted into a continuous process passes through a reaction zone of 200 to 350 ° C.

In a continuous process, the temperature distribution in the reaction zone may be variable, e.g. 200 to 250 ° C at the beginning of the zone and 250 to 350 ° C at the exit of the zone.

In the new process for the production of polyarsaids, it is possible to prepare polymers from uniform dismides and uniform diesers, and mixtures of diamines, e.g. and p-phenylenediamines and a single ester or a single amine and a mixture of esters, for example dimethyl terephthalate and dimethyl isophthalate, or a mixture of diamines and a mixture of diethers is used.

The choice of reaction temperature and time depends on the reactivity of the diamines and diethers used.

From the reaction scheme

J ♦ (x-1) KOH shows that alcohol is released during the reaction, which, as the most volatile component in the system, can generate excess pressure in a confined space at elevated temperatures; the excess pressure of some of the starting components can also contribute to the overpressure. Thus, when working in closed reactors, the start of reactions is manifested by a pressure increase. The interaction of diamines and diethers is suitable, or only from time to time, forgiving the reaction overpressure, because the removal of volatile reaction products can be facilitated by the aidside.

In the case where an excess of any of the starting components is used, it can be removed directly from the distillation reactor or outside the reactor by distillation or extraction at the end of the synthesis.

The obtained polymers can be processed by some known methods.

they spin polymer solutions in concentrated sulfuric acid by introducing them into aqueous baths.

While the focus of the current processes for producing polyarsaid are reed dismides with diohlorides

197 149 aromatic dicarboxylic acids, uses a new method of esters.This measure has significant advantages over existing processes; on the one hand, alcohol is released during the reaction, which, in contrast to the strongly corrosive hydrogen chloride leaving the dichloride process, does not exhibit corrosion and allows the use of conventional construction materials for production apparatus. In addition, products are obtained which do not contain acidic fumes. , so that production was accompanied by intolerable amounts of acid wastewater.

The new process allows working without auxiliary solvents such as hexamethylphosphoramide and N-methylpyrrolidine, which has been necessary in the process and has led to increased production costs and complicated product washing and wastewater disposal.

Example

194.2 g of dimethyl terephthalate (1 mole) and 108.1 g of p-phenylenediamine (1 mole) are introduced into the autoclave, whereupon the obeah of the autoclave is heated with a sheath equipped with an electrical resistive heater so that the temperature rises evenly up to 245 ° C. where overpressure is achieved and reaches 0.75 MPa in a short boil. Further heating over a period of 25 min. reaches 280 ° C and an overpressure of 2 MPa; The overpressure was reduced to 10 bar by discharging and the autoclave was maintained at 280-290 ° C for a further 1 hour. Finally, the overpressure was discharged, the reaction mixture was allowed to cool freely and removed from the autoclave. 263 g of solid polymer were obtained. a phenylene terephthalamide type which does not melt below 375 ° C and 31 g of the cooled off-gas condensate discharged from the autoclave during the reaction.

Claims (3)

SUBJECT OF THE INVENTION Process for the production of polyaramides of the phenylene phthalamide type, characterized in that phenylenediamines and benzenedicarboxylic acid esters and alkyls are reacted with each other at temperatures of from 200 to 350 ° C. 2. A process according to claim 1, wherein a mixture of phenylenediamines and esters is first prepared, by heating the mixture to a homogeneous melt, which is introduced into a flow reaction proetor at a temperature of 200 to 350 ° C. 3. A process for the production of polyaramides according to claim 1 or 2, characterized in that a mixture of phenylenediamines and esters or of phenylenediamines and of mixtures of esters or of mixtures of phenylenediamines and of mixtures of esters is interacting with each other.