Process for the continuous production of polyether polyols

Abstract

This invention relates to a process for the continuous production of polyether polyols, polyether polyols produced by the inventive continuous process and their use in polyurethane applications.

1 : A process for continuous production of polyether alcohols, the process comprising:
 (a) continuously adding at least one aromatic amine (AA) at one dosing point D1 to an arrangement R1 comprising at least one plug-flow reactor (PFR) and/or a cascade of at least two continuously stirred tank reactors (CSTRs), and reacting with at least one alkylene oxide 1(AO1) which is continuously dosed into the arrangement R1 at one or more dosing points D2 to generate an intermediate (I); and subsequently   (b) continuously transferring the intermediate (I) into another arrangement R2 comprising at least one further reactor, and reacting with at least one alkylene oxide 2 (AO2) in the presence of at least one amine compound (AC), wherein at least one of the at least one amine compounds AC is selected from the group consisting of imidazoles.   
     
     
         2 : The process according to  claim 1 , wherein the adding (a) comprises an autocatalytic reaction. 
     
     
         3 : The process according to  claim 1 , wherein no additional compounds are added in the adding (a), in addition to the at least one aromatic amine (AA) and the at least one alkylene oxide 1 (AO1). 
     
     
         4 : The process according to  claim 1 , wherein the arrangement R1 in the adding (a) consists of a cascade of two continuously stirred tank reactors (CSTRs). 
     
     
         5 : The process according to  claim 1 , wherein the arrangement R1 in the adding (a) consists of one plug-flow reactor, two plug-flow reactors or three plug-flow reactors. 
     
     
         6 : The process according to  claim 1 , wherein the arrangement R1 in the adding (a) is a combination of (i) at least one plug-flow reactor and (ii) one continuously stirred tank reactor (CSTR) or a cascade of at least two continuously stirred tank reactors. 
     
     
         7 : The process according to  claim 1 , wherein each of the at least one PFRs and/or CSTRs of the arrangement R1 in the adding (a) have at least one dosing point for alkylene oxide AO1. 
     
     
         8 : The process according to  claim 1 , wherein the arrangement R2 consists of at least one CSTR. 
     
     
         9 : The process according to  claim 1 , wherein the transferring (b) is initiated when the amount of free aromatic amine (AA) in the adding (a), as determined by gas chromatography, is less than 2% by weight, in relation to the total amount of the intermediate. 
     
     
         10 : The process according to  claim 1 , wherein at least one aromatic amine (AA) is selected from the group consisting of aromatic amines having at least two amino groups. 
     
     
         11 : The process according to  claim 1 , wherein at least one aromatic amine (AA) is tolylenediamine (TDA). 
     
     
         12 : The process according to  claim 1 , wherein at least one aromatic amine (AA) is vic-TDA. 
     
     
         13 : The process according to  claim 12 , wherein a ratio of isomers in the vic-TDA is in the range of 50 to 70% by weight 3,4-TDA and 30 to 50% by weight 2,3-TDA, based on the sum of the weight of both TDA isomers. 
     
     
         14 : The process according to  claim 1 , wherein in addition to the at least one aromatic amine (AA), at least one at least difunctional alcohol (DA) is added continuously in the adding (a). 
     
     
         15 : The process according to  claim 14 , wherein the at least difunctional alcohols DA are used in an amount of 0.1 to 20% by weight, based on the sum of weights of the components AA, AO1 and DA. 
     
     
         16 : The process according to  claim 14 , wherein at least one of the at least difunctional alcohols DA is selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol and reaction products thereof with alkylene oxides. 
     
     
         17 : The process according to  claim 1 , wherein no additional difunctional alcohol (DA) is used. 
     
     
         18 : The process according to  claim 1 , wherein at least one alkylene oxide AO1 is selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide and mixtures thereof. 
     
     
         19 : The process according to  claim 1 , wherein at least one alkylene oxide AO2 is selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide and mixtures thereof. 
     
     
         20 : The process according to  claim 1 , wherein the alkylene oxide AO1 is the same as alkylene oxide AO2. 
     
     
         21 : The process according to  claim 1 , wherein the alkylene oxide AO1 is different from the alkylene oxide AO2. 
     
     
         22 : The process according to  claim 1 , wherein the at least one amine compound AC in the transferring (b) has a catalytic activity on the reaction of the intermediate (I) and the at least one alkylene oxide AO2. 
     
     
         23 : The process according to  claim 1 , wherein all of the at least one amine compounds AC are selected from the group consisting of imidazoles. 
     
     
         24 : The process according to  claim 1 , wherein the produced polyether alcohols have a hydroxyl number in the range from 200 to 800 mg KOH/g. 
     
     
         25 : The process according to  claim 1 , wherein the produced polyether alcohols have a residual content of aromatic amine AA below 1000 ppm. 
     
     
         26 : A polyether alcohol, obtainable by the process according to  claim 1 . 
     
     
         27 : The polyether alcohol according to  claim 26 , wherein the polyether alcohol has a residual content of aromatic amine AA below 1000 ppm. 
     
     
         28 : A process for producing a polyurethane, the process comprising:
 reacting at least one polyether alcohol according to  claim 26  with at least one di- or polyisocyanate, optionally in the presence of a blowing agent.   
     
     
         29 : The process according to  claim 28 , wherein the polyurethane is a rigid foam.