Starch oil sizing composition and glass fibers treated therewith

An aqueous sizing composition for glass fibers comprising:

• between 50 and 60 weight percent on a non-aqueous basis of a mixture of two starches, a first starch being an hydroxyl propyl corn starch which has been formed by the reaction of propylene oxide with a high amylose corn starch, and a second starch being a highly crosslinked low amylose non-ionic corn starch;
• between 23 and 33 weight percent of a non-aqueous basis of a lubricating mixture selected from the group consisting of fatty triglycerides and waxes, or waxes and humectants, wherein the triglyceride, where present, is in a ratio to the other lubricants of at least 1:1 on a weight basis;
• between 6 and 12 weight percent of a non-aqueous basis of a second lubricant which is the salt of a polyamino functional polyamide resin, said polyamino functional polyamide resin salt being formed from the condensation reaction product of a polycarboxylic acid and a polyamine, said polyamine having greater than two amine groups per molecule, and the carboxylic acid having 1 to 5 carbon atoms;
• between 2 and 7 weight percent on a non-aqueous basis of at least one coupling agent selected from the group consisting of hydrolyzed silanes and non-hydrolyzed silanes, and mixtures thereof;
• and
• water in an amount sufficient to apply the solution to glass fibers.