METHOD FOR PREPARING STABLE AQUEOUS DISPERSION OF POLYCARBODIIMIDE THAT DO NOT CONTAIN ORGANIC SOLVENTS AND CAN BE USED AS CROSS-LINKING AGENTS Russian patent published in 2007 - IPC C08G18/02 C08G18/28 

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing stable aqueous dispersions of polycarbodiimide for using as a cross-linking agent and no containing organic solvents. Method is realized by carrying out interaction of polyisocyanate in the presence of 0.5-3% of catalyst in reaction for formation of carbodiimide to form polycarbodiimide intermediate substance at 120-180⁰C for aliphatic polyisocyanate and at 80-120⁰C for aromatic polyisocyanate up to preparing 5-10% of NCO wherein polyisocyanate is represented by toluene-2,4-diisocyanate, toluene-2,6-diisocyanate or their mixture, diphenyl-4,4'-diisocyanate, 1,4-phenylenediisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, 1,6-hexyldiisocyanate, 1,4-cyclohexyldiisocyanate, norbornyldiisocyanate or their mixture. Then method involves carrying out break and/or elongation of polycarbodiimide chain of intermediate substance by addition of equivalent compound comprising hydrophilic group and one or more amino- and/or hydroxyl functional groups during formation of polycarbodiimide intermediate substance or after formation of polycarbodiimide at temperature 70-100⁰C for aliphatic polycarbodiimide intermediate substance and at temperature 40-70⁰C for aromatic polycarbodiimide intermediate substance. Then reaction in mixture is carried out up to disappearance of isocyanate functional group wherein a hydrophilic group-containing compound is represented by polyethoxymono- or diol, polyethoxy/polypropoxymono- or diol, polyethoxymono- or diamine, polyethoxy/polypropoxymono- or diamine, diol or diamine with polyalkoxy-containing by-side chain, hydroxy- or aminoalkylsulfonate, or dialkylaminoalkyl alcohol or -amine, or their mixture. Prepared compound is dispersed in water at temperature 40-100⁰C at pH 11-14 by addition of a base and/or buffer to water used for dispersing, and/or to prepared aqueous dispersion wherein a base is represented by alkaline metal hydroxide, such as lithium hydroxide, sodium hydroxide, potassium hydroxide, or trialkylamine, or trialkylamine containing hydroxy-groups, and wherein buffer is represented by usually used buffer with effective pH value 11-14. Polycarbodiimide dispersions prepared by above described method are stable for at least some weeks at temperature 50⁰C. Also, invention describes a covering mixture comprising polycarbodiimide dispersions and solidified material prepared by applying abovementioned covering mixture on substrate and evaporation of water.

EFFECT: improved preparing method of dispersions.

3 cl, 2 tbl, 15 ex