Size for forming glass fibers having a reduced tendency to give gumming deposits

DETAILED DESCRIPTION OF THE INVENTION It is believed but the invention is not limited by this belief that the composition and method of the invention gives improved sized glass fiber strands and yarn because of the use of the particular amount and kind of the starch.
The amount of starch used is about 50 to about 65 weight percent based on non-aqueous components of the size composition.
The kind of starch used is a cross-linked, partially cooked starch.
The kind and amount of starch used in the size formulation increases the hydrophobic character of the sized glass fiber strands and therefore under high relative humidity conditions makes the glass fiber strands less susceptible to forming gummy deposits because a high moisture content is absorbed by the starch on the sized glass fiber strand.
The starch constituent of the size of the present invention is incorporated to bind the glass fibers together into a strand in order that the strand will have enough integrity to withstand the winding and twisting operation encountered in processing the strand, and to reduce the tendency of fiber glass strand containing a starch binder to leave gummy deposits on fabrication machinery under high relative humidity fabrication conditions.
The starch constituent can be any starch from the commercially available starches such as those derived from corn, potato, wheat, sago, tapioca and arrow root which has been modified by cross-linking.
The cross-linking modification may be carried out by any conventional method known to those skilled in the art.
The starch can contain any percentage of amylose starch and any percentage of amylopectin starch that are known to be used in the art.
The starch may be a low amylose starch, which is a water repellant starch that contains from 25 to 27 percent amylose with the remainder being amylopectin starch.
The low amylose starch contains cross-links and is preferably a lightly cross-linked corn starch.
Also considered to be included for the purpose of this invention are starch mixtures containing a low amylose component and a high amylose component that are lightly cross-bonded to each other to provide a weak knit