Silica sols, method and apparatus for producing the same and use thereof in papermaking

Patent metadata

Field	Value
Publication number	US-9975781-B2
Application number	US-201415105801-A
Country	US
Kind code	B2
Filing date	Dec 17, 2014
Priority date	Dec 18, 2013
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

The present invention relates to colloidal silicas having a low S-value and a high solids content, the preparation thereof, and the use thereof in the production of paper. When used in the production of paper, the colloidal silicas of the invention exhibit good retention and drainage performance so that they can be used in lower amounts compared to conventional colloidal silicas. The present invention also relates to an apparatus and a method for producing such activated colloidal silicas.

First claim

What is claimed is:

1. A method of activating colloidal silica for use in papermaking comprising:
(a) contacting an unmodified colloidal silica feedstock with an activating agent selected from the group consisting of an inorganic acid, an organic acid, salts of sodium or potassium, and mixtures thereof for a period of time sufficient to convert the colloidal silica feedstock into the activated colloidal silica, wherein the activated colloidal silica has an S-value that is at least 10% lower than the colloidal silica feedstock and a shelf-life of less than 30 days; and
(b) adding the activated colloidal silica to papermaking furnish.

2. The method of claim 1 , wherein the activating agent is used in an amount so as to afford an activation reaction mixture having a pH value of from 7.5 to 10.5.

3. The method of claim 1 , wherein the activating agent is used in an amount so as to afford an activation reaction mixture having a pH value of from 0.5 to 3.5.

4. The method of claim 1 , wherein the activating agent is at least one salt, and the activating agent is used in an amount so as to afford an activation reaction mixture having a conductivity of from 0.1 mS/cm to 100 mS/cm greater than the conductivity of the colloidal silica feedstock.

5. The method of claim 4 , further comprising measuring the conductivity with a sensor.

6. The method of claim 5 , further comprising adding a terminator source if the conductivity exceeds a predetermined threshold.

7. The method of claim 6 , wherein the terminator source is selected from the group consisting of water, hydroxide salts, aluminum salts, and mixtures thereof.

8. The method of claim 1 , wherein the activating agent is selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carbonic acid, formic acid, acetic acid, propionic acid, butyric acid, citric acid, oxalic acid, malonic acid, maleic acid, fumaric acid, benzoic acid, benzene sulfonic acid, p-toluene sulfonic acid, sodium bicarbonate, potassium bicarbonate, monosodium phosphate, monopotassium phosphate, disodium phosphate, dipotassium phosphate, sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, potassium nitrate, sodium chlorate, and potassium chlorate and mixtures thereof.

9. The method of claim 1 , wherein the contacting lasted for a period of time in the range of from 5 minutes to 12 hours.

10. The method of claim 1 , wherein the colloidal silica feedstock has a specific surface area of from 400 m 2 /g to 1100 m 2 /g, an S-value of from 15 to 50%, and a solids content of from 5 to 20 wt %.

11. The method of claim 1 , wherein the activated colloidal silica is added to the furnish in a concentration of from about 0.0001 to about 1.25 percent by weight based on the dry weight of the fibers in the furnish and the activated colloidal silicate calculated as SiO 2 .

12. The method of claim 1 , wherein the activated colloidal silica has a shelf-life of 1 to 7 days.

13. The method of claim 1 , wherein the activated colloidal silica is at least 20% more effective as a drainage aid compared to unactivated colloidal silica.

14. The method of claim 1 , wherein the activated colloidal silica has an S-value that is at least 20% lower than the S-value of the colloidal silica feedstock.

Assignees

• Ecolab Usa Inc

Inventors

• Bai Wen
• Xu Jian
• Wu Jia
• Chen Zhi
• Shen Jian Kun
• Miller Jr Raymond D
• Wong Shing Jane B

Classifications

• C09C1/3063

  Treatment with low-molecular organic compounds · CPC title

• C01B33/146 Primary

  After-treatment of sols ({preparation of hydrosols or aqueous dispersions from hydroorganosols, organosols or dispersions in an organic medium C01B33/141}; preparation of hydroorganosols, organosols or dispersions in an organic medium from hydrosols {or aqueous dispersions} C01B33/145) · CPC title

• D21H21/10

  Retention agents or drainage improvers · CPC title

• D21H17/68

  siliceous, e.g. clays · CPC title

• C09C1/3045

  Treatment with inorganic compounds · CPC title