Papermaking and products made thereby

DETAILED DESCRIPTION What is claimed is: 1.
In a paper making process in which an aqueous papermaking stock containing a sufficient amount of cellulosic pulp to give a finished paper containing at least 50% cellulosic fiber is formed and dried, the improvement which comprises providing in the stock prior to the formation of the sheet a binder comprising colloidal silicic acid having an average particle size of less than 20 nm, and cationic starch having a degree of substitution of not less than 0.
01, the weight ratio of cationic starch to SiO.
sub.
2 being between 1:1 and 25:1, the solids in said binder amounting to 0.
1-15% of the weight of said pulp, said cationic starch and said colloidal silicic acid being admixed with each other in the presence of cellulosic fiber to form a complex of cationic starch and colloidal silicic acid which serves as a binder for the cellulosic fibers.
2.
The process of claim 1 wherein the pH of the stock is maintained between about 4 and 9.
3.
The process of claim 1 wherein the weight ratio of cationic starch to SiO.
sub.
2 is between 1.
5:1 and 10:1.
4.
The process of claim 3 wherein the solids in the binder amount to 1.
0-15% of the weight of the pulp.
5.
The process of claim 1 wherein the degree of substitution of the starch is from about 0.
01 to about 0.
05.
6.
The process of claim 5 wherein the degree of substitution of the starch is from about 0.
02 to about 0.
04.
7.
In a papermaking process in which an aqueous papermaking stock containing a sufficient amount of cellulosic pulp to give a paper containing at least 50 percent of cellulosic fiber is formed and dried, the improvement which comprises providing in the stock prior to the formation of the sheet a binder comprising a colloidal silica sol having silica particles having a surface area of about 50 to about 1000 m.
sup.
2 /g and cationic starch having a degree of substitution of not less than 0.
01, the weight ratio of cationic starch to SiO.
sub.
2 being between 1:1 and 25:1, the solids in said binder amounting to 0