CH434748A - Polycondensation process - Google Patents

Description

  

  
 



  Polycondensation process
 The present invention relates to a novel polycondensation process.



     It is already known to carry out polycondensation reactions in a homogeneous phase from at least two reagents when all the reagents are melted or dissolved in the reaction mixture. It is also known to carry out polycondensations from immiscible solutions of the constituents (interfacial polymerization). However, these processes cannot be used when one of the products of the polycondensation is infusible or insoluble under the optimum temperature conditions required.



     It has now been found, and this is the subject of the present invention, that high molecular weight polycondensates can easily be obtained by condensation of diols with chlorides of diacids, provided that the operation is carried out in an inert organic diluent chosen from aryl oxides, aralkyl oxides and hydrocarbons and in which the polycondensate and the diol are insoluble and maintained in dispersed form during the polycondensation.



   The polycondensate is obtained in the form of a powder, more or less gelled with the diluent, which is nevertheless easily isolated by filtration of its suspension.



   This process can be used when the diol is solid at the reaction temperature; in this case it is used in finely ground form, the powder being kept in suspension in the inert diluent.



   The process is also applicable when, at the temperature of the polycondensation, the diol is liquid but not dissolved in the reaction medium, or when the final polycondensate is liquid but not dissolved at this temperature. The operation is then carried out on liquid suspensions instead of operating on suspensions of solids, but the polycondensation is carried out according to the same operating mode.



   The diol is kept in suspension by any known means; generally simple mechanical agitation is sufficient.



   One of the preferred embodiments of the invention consists in preparing a suspension of the diol in the inert diluent, in heating the suspension with stirring in an inert atmosphere (for example nitrogen, argon) at a suitable temperature, optionally under pressure if the diluent has too high a vapor pressure at this temperature, then in introducing the diacid chloride (either liquid or dissolved in the inert diluent) into the reaction mass. The temperature and duration of the reaction are then adjusted according to the molecular weight desired for the polycondensate. (This molecular weight is identified by measuring the specific viscosity).

   The polycondensate formed is in the form of a suspension; the latter is cooled with stirring, filtered, the polycondensate collected, washed with an appropriate solvent to remove traces of diluent and dried.



   For convenience, preferred are inert diluents whose boiling point is greater than 200, such as phenyl oxide, devahydronaphthalene, α-methylbenzyl oxide ... but it is also possible to use diluents with a lower boiling point, then optionally operating under pressure.



   The diols which are insoluble or infusible under optimum polycondensation conditions can, for example, be compounds containing one or more oxamic units —NH — CO — CO — NH— such as the diols described in French patent 1,338,399 filed on July 9, 1962.



   The present invention is particularly advantageous in the case where part of one of the difunctional reagents is replaced by a reagent containing more than two functional groups, which promotes the formation of infusible or insoluble polycondensates under the reaction conditions.



   The following example shows how the process of the invention can be put into practice.



   50 cm3 of decahydronaphthalene and 17.6 g of bis-hydroxyethyloxamide are charged in a 250 cm3 Pyrex reactor, passing through an AFNOR sieve.
No. 25. It is heated while stirring under nitrogen to 1200 and introduced in one hour 20.3 g of terephthaloyl chloride dissolved in 50 cm3 of deaahydronaphthalene.



   The mixture is heated with stirring and under a nitrogen atmosphere for 15 hours at 1300 then for 8 hours at 200 "; the suspended solid swells very little during the reaction and remains pulverulent. After cooling with stirring, the solid is separated by filtering. , washed this solid with ethanol to remove the decahydronaphthaiene and then dried. 26.6 g of white, pulverulent polyester are thus obtained, softening at around 2600 and whose specific viscosity (measured at 250 in a 1 O / o solution in l. sulfuric acid (d = 1.83) is 0.27 This polyester can be transformed into threads from its sulfuric solution.
  

 

Claims (1)

CLAIM Process for polycondensation of a diol with a diacid chloride, characterized in that the operation is carried out in an inert organic diluent chosen from aryl oxides, aralkyl oxides and hydrocarbons and in which the polycondensate and the diol are insoluble and maintained in dispersed form during polycondensation. SUB-CLAIM Process according to claim, characterized in that the diol contains at least one -NH-CO-CO-NH- group.