Nalco Chemical Company

Ondeo Nalco Company

Maureen B Nunn

Bruce A Keiser

Cheng-Sung Huang

Dennis L MacDonald

Kristine S Salmen

Pek L Choo

David A Picco

Michio Kobayashi

Dennis I MacDonald

A stable aquasol containing colloidal silica having a surface area of from about 700 m /g to about 1100 m /g, and an S-value of from about 20 to about 50; wherein the colloidal silica is not surface treated; wherein the molar ratio of SiO /Na O in the colloidal silica is greater than about 13.0:1 and is less than about 17.0:1; and wherein the aquasols have a percent by weight SiO solids level of from about 7.00 percent to about 16.80 percent is described and claimed.

Stable colloidal silica aquasols

Disclosed are stable, aqueous colloidal silicas having surface area of greater than 700 m /g and S-values of from 20-50. These colloidal silicas do not require treatment with surface treatment agents such as aluminum to achieve stability. These colloidal silica aquasols can be produced and stored at concentrations of greater than 7 percent by weight SiO solids, and even as high as 15 percent by weight solids or higher, and remain stable at room temperature for at least 30 days compared to art-known silica aquasols. These colloidal silica sols demonstrate advantageously improved performance over art-known colloidal silica sots in applications such as in drainage and retention in papermaking processes. Also disclosed are processes for making aqueous colloidal silicas of the invention and the use of such colloidal silicas in papermaking processes.

Method of making colloidal silica

Method of making paper

A method for the manufacture of paper comprising the steps of:

Colloidal silica/polyelectrolyte blends for pulp and paper applications

A method of detecting microbiological fouling of felts used in paper making machines is described. A felt suspected of containing microbiological deposits is contacted with iodonitrotetrazolium and then examined for a predetermined color change confirming the presence of bacteria on the felt. The felt assumes a red color in the presence of at least one million colony forming units of bacteria per gram of dry felt within thirty minutes after the iodonitrotetrazolium has contacted the felt.

Microbiological detection method for felts using iodonitrotetrazolium

Biocide treatment of the water system of a papermaking process comprising the steps of encapsulating the biocide as the core of the capsule in a water suspension, in which the shell is degradable at high water dilution, and introducing the microcapsules into the water stream to undergo dilution release.

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Naperville, IL, United States of America

Maureen B Nunn