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

A method for preparing an amino-functional polydiorganosiloxane comprising:

• 1) mixing and heating, at a temperature of 50° C. to 160° 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 to 0.5%, based on combined weights of all starting materials, of an endblocker having triorganosilyl groups;
• and thereafter
• 2) providing starting material D) 0.01% to 5%, based on weight of starting material B), of a solid (at conditions of 20° C. to 25° C. and 101 kPa) precatalyst selected from the group consisting of a carboxylic acid, an acid anhydride, and a combination of both the carboxylic acid and the acid anhydride under conditions permitting the precatalyst to react to form a catalyst;
• thereby forming a reaction mixture;
• and
• 3) mixing and heating the reaction mixture under conditions to form a reaction product;
• and
• 4) removing all or a portion of residual acid by a technique comprising cooling the reaction product, thereby reducing amount of the residual acid to 0 to <500 ppm, based on the weight of the amino-functional polydiorganosiloxane, where step 4) further comprises filtering and/or centrifuging the reaction product after cooling.