초록 ▼

The present invention generally relates to polysilicate microgels. More specifically, the invention relates to a process for preparing aqueous polysilicate microgels which comprises mixing an aqueous solution of alkali metal silicate with an aqueous phase of silica-based material having a pH of 11 o

The present invention generally relates to polysilicate microgels. More specifically, the invention relates to a process for preparing aqueous polysilicate microgels which comprises mixing an aqueous solution of alkali metal silicate with an aqueous phase of silica-based material having a pH of 11 or less, to polysilicate microgels per se and to the use thereof as flocculating agents in paper making and water purification. The invention further relates to a process for the production of paper from a suspension of cellulosic fibers, and optional filler, which comprises adding to the suspension at least one cationic or amphoteric organic polymer and a polysilicate microgel, forming and draining the suspension on a wire.

대표청구항 ▼

We claim: 1. A process for preparing an aqueous polysilicate microgel which comprises mixing (i) an aqueous solution of alkali metal silicate with (ii) an aqueous phase of silica-based material having a pH within the range of from 7 to 11, which is selected from the group consisting of silica-based

We claim: 1. A process for preparing an aqueous polysilicate microgel which comprises mixing (i) an aqueous solution of alkali metal silicate with (ii) an aqueous phase of silica-based material having a pH within the range of from 7 to 11, which is selected from the group consisting of silica-based sols, fumed silica, silica gels, precipitated silicas and acidified solutions of alkali metal silicates, and (iii) a metal salt other than an aluminum salt, wherein the metal salt is based on an alkali metal or alkaline earth metal and has an anion selected from of the group consisting of borate, nitrate, chloride, formate and acetate, wherein the polysilicate microgel has a specific surface area of at least 1000 m2/g. 2. The process of claim 1, wherein the metal salt is based on an alkali metal or alkaline earth metal and it has an anion, and the anion is borate, nitrate or acetate. 3. The process of claim 1, wherein the metal salt is a borate. 4. The process of claim 1, wherein the polysilicate microgel obtained has a molar ratio SiO2:M2O, where M is alkali metal, between 3:1 and 20:1. 5. The process of claim 1, wherein the aqueous polysilicate microgel obtained has a SiO2 content of at least 5% by weight. 6. The process of claim 5, wherein the aqueous polysilicate microgel obtained has a SiO2 content of at least 15% by weight. 7. The process of claim 1, wherein the aqueous polysilicate microgel prepared by the process is anionic. 8. The process of claim 1, further comprising a step of diluting the aqueous polysilicate microgel by adding an aqueous solution or suspension. 9. The process of claim 1, wherein the aqueous solution of alkali metal silicate, component (i), has a pH of at least about 13. 10. The process of claim 1, wherein the aqueous phase of silica-based material, component (ii), has a pH of up to 10.6. 11. A process for preparing an aqueous polysilicate microgel which comprises mixing (i) an aqueous solution of alkali metal silicate with (ii) an aqueous phase of silica-based material having a pH within the range of from 7 to 11, which is selected from the group consisting of silica-based sols, fumed silica, silica gels, precipitated silicas and acidified solutions of alkali metal silicates, and (iii) a metal salt, wherein the aqueous polysilicate microgel obtained has a molar ratio of SiO2:M2O, where M is alkali metal, between 3:1 and 20:1, wherein the polysilicate microgel has a specific surface area of at least 1000 m2/g. 12. The process of claim 11, wherein the salt is a metal salt other than an aluminium salt and based on an alkali metal or alkaline earth metal. 13. The process of claim 12, wherein the salt is a borate. 14. The process of claim 11, wherein the aqueous polysilicate microgel obtained has a SiO2 content of at least 15% by weight. 15. The process of claim 11, wherein the aqueous polysilicate microgel prepared by the process is anionic. 16. The process of claim 11, further comprising a step of diluting the aqueous polysilicate microgel by adding an aqueous solution or suspension. 17. The process of claim 11, wherein the aqueous solution of alkali metal silicate, component (i), has a pH of at least about 13. 18. The process of claim 11, wherein the aqueous phase of silica-based material, component (ii), has a pH of up to 10.6. 19. The process of claim 11, wherein the aqueous polysilicate microgel obtained has a SiO2 content of at least 5% by weight. 20. The process of claim 11, further comprising mixing components (i) and (ii) with (iii) an aluminium salt. 21. The process of claim 20, wherein the aluminium salt, component (iii), is sodium aluminate. 22. The process of claim 11, wherein the aqueous solution of alkali metal silicate, component (i), is an aqueous solution of sodium silicate. 23. The process of claim 11, wherein the aqueous phase of silica-based material, component (ii), is an acidified solution of an alkali metal silicate. 24. The process of claim 23, wherein the acidified solution of an alkali metal silicate, component (ii), is sodium silicate. 25. The process of claim 23, wherein the acidified solution of an alkali metal silicate, component (ii), is an alkali metal silicate that has been both acidified and aluminated.