Method for making an amino-functional polydiorganosiloxane using a removable acid catalyst

A method for preparing an amino-functional polydiorganosiloxane comprising:

• 1) mixing and heating, at a temperature of 50° C. to 150° C., starting materials comprising
• A) a silanol functional polydiorganosiloxane,
• B) an aminoalkyl-functional alkoxysilane,
• where amounts of starting materials A) and B) are such that a molar excess of silanol groups with respect to alkoxy groups is present, and
• C) 0.1% to 0.5%, based on combined weights of all starting materials, of an endblocker having triorganosilyl groups;
• and thereafter
• 2) adding starting material D) 0.01% to 5%, based on weight of starting material B), of a carboxylic acid having a boiling temperature of 90° C. to 150° C. and pKa value of 1 to 5;
• thereby forming a reaction mixture;
• 3) mixing and heating the reaction mixture to form the reaction product and reduce amount of residual acid in the form of the carboxylic acid and/or carboxylate salt to 0 to <500 ppm, based on the weight of the amino-functional polydiorganosiloxane.