The present invention relates to an exfoliating agent and to a process for producing random form of nanoscale silicate plates. The exfoliating agent applied in the present invention has the formula: wherein n=1 to 5 and R is a polyoxypropylene group, poly(oxyethylene/oxypropylene) group, polyoxyb
The present invention relates to an exfoliating agent and to a process for producing random form of nanoscale silicate plates. The exfoliating agent applied in the present invention has the formula: wherein n=1 to 5 and R is a polyoxypropylene group, poly(oxyethylene/oxypropylene) group, polyoxybutylene group, or polyoxyethylene group. In this invention, layered silicate clays are exfoliated into random silicate plates by acidifying AMO with inorganic acid, adding the acidified AMO to layered silicate clay with agitation, and adding sodium hydroxide or chloride of alkali metal or alkaline-earth metal, in ethanol, water and a hydrophobic organic solvent to the intermediate product and repeating phase separation procedures to isolate random silicate plates from water phase.
대표청구항▼
What is claimed is: 1. A method for producing random form of nanosilicate plates, comprising the steps of: (a) preparing amine-terminating Mannich oligomers (AMO) from polyoxyalkylene amine, p-cresol and formaldehyde to obtain a polymeric exfoliating agent having a general formula: wherein n is
What is claimed is: 1. A method for producing random form of nanosilicate plates, comprising the steps of: (a) preparing amine-terminating Mannich oligomers (AMO) from polyoxyalkylene amine, p-cresol and formaldehyde to obtain a polymeric exfoliating agent having a general formula: wherein n is from 1 to 5; R represents an organic group selected from the group consisting of polyoxypropylene groups, poly(oxyethylene/oxypropylene) groups, polyoxybutylene groups, and polyoxyethylene groups; wherein said formaldehyde is added at an appropriate addition rate by which the exothermic temperature is kept in the range of 25�� C. to 160�� C.; (b) adding inorganic acid to said AMO to form an acidified AMO; (c) mixing said acidified AMO with a swelled inorganic layered silicate clay so as to exfoliate said silicate clay directly through cationic exchange to form an exfoliated silicate clay; and (d) mixing an aqueous solution containing a hydroxide or a chloride of alkali metal or alkaline-earth metal, ethanol, water and an organic solvent with said exfoliated silicate clay obtained in step (c) to form a mixture and then, after mixing, keeping the mixture static to form an upper organic phase and a lower water phase containing nanosilicate plates. 2. The method as claimed in claim 1, wherein said polyoxyalkylene amine used in said step (a) has molecular weight ranging from 400 to 4,000 g/mol. 3. The method as claimed in claim 1, wherein said polyoxyalkylene amine used in said step (a) has molecular weight ranging from 1,000 to 2,000 g/mol. 4. The method as claimed in claim 1, wherein said polyoxyalkylene amine used in said step (a) is selected from the group consisting of polyoxypropylene diamine, polyoxyethylene diamine, polyoxybutylene diamine and poly(oxyethylene-oxypropylene)diamine. 5. The method as claimed in claim 1, wherein said polyoxyalkylene amine used in said step (a) is polyoxypropylene diamine. 6. The method as claimed in claim 1, wherein said polyoxyalkylene diamine, p-cresol and formaldehyde in said step (a) are added at a molar ratio (n+1):n:2n, wherein n is 1 to 5. 7. The method as claimed in claim 1, wherein more than 25 wt % of said exfoliating agent obtained in said step (a) has molecular weight ranging from 5,000 to 10,000. 8. The method as claimed in claim 1, wherein said exfoliating agent and said inorganic acid are mixed in an equivalent ratio 2:1 in said step (b). 9. The method as claimed in claim 1, wherein said inorganic acid used in said step (b) is selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid. 10. The method as claimed in claim 1, wherein the molar ratio of amino groups in said exfoliating agent to cationic exchange capacity of said silicate clay ranges from 3:1 to 1:1 in said step (c). 11. The method as claimed in claim 1, wherein said silicate clay used in said step (c) is selected from the group consisting of montmorillonite, kaolin, mica and talc. 12. The method as claimed in claim 1, wherein said silicate clay used in said step (c) has a cationic exchange capacity ranging from 50 meq/100 g to 200 meq/100 g. 13. The method as claimed in claim 1, wherein said hydroxide or chloride of alkali metal or alkaline-earth metal used in said step (d) is sodium hydroxide. 14. The method as claimed in claim 1, wherein said hydroxide or chloride of alkali metal or alkaline-earth metal is added at the same equivalence in said step (d). 15. The method as claimed in claim 1, wherein said organic solvent used in said step (d) is selected from the group consisting of ether, ketone, ester, nitrile, saturated hydrocarbon, chlorinated hydrocarbon and aromatic hydrocarbon. 16. The method as claimed in claim 1, wherein said organic solvent used in said step (d) is selected from the group consisting of tetrahydrofuran, isopropyl ether, methyl tert-butyl ether, methyl isobutyl ketone, ethylnitrile, ethyl acetate, pentane, hexane, heptane, cyclohexane, dichloromethane, benzene, toluene, dimethylbenzene, chlorobenzene and methoxybenzene. 17. The method as claimed in claim 1, wherein said hydroxide or chloride of alkali metal or alkaline-earth metal is added at 1 to 5 equivalences in step (d). 18. The method as claimed in claim 1, wherein said organic phase formed in said step (d) comprises said exfoliating agent suitable for recycling.
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이 특허에 인용된 특허 (5)
Kaylo Alan J. ; Karabin Richard F. ; Lan Tie ; Sandala Michael G., Acidified aqueous dispersions of high aspect ratio clays.
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