Claims
- 1. Amorphous silica which comprises:
- an RDA value of between 30 and 70;
- an oil absorption capacity of between 100 and 155 cm.sup.3 /100 g; and
- a BET surface area of up to 200 m.sup.2 /g.
- 2. Amorphous silica according to claim 1 in which the RDA value is between 40 and 70.
- 3. Amorphous silica according to claim 1 in which the RDA value is between 50 and 60.
- 4. Amorphous silica according to claim 1 in which the oil absorption capacity is between 100 and 145 cm.sup.3 /100 g.
- 5. Amorphous silica according to claim 1 in which the oil absorption capacity is between 115 and 130 cm.sup.3 /100 g.
- 6. Amorphous silica according to claim 1 having a light transmission of more than 70% at a refractive index within the range of 1.445 to 1.456.
- 7. Amorphous silica according to claim 6 having a peak of light transmission in the refractive index range of 1.445 to 1.456.
- 8. Amorphous silica according to claim 1 having a mercury pore volume of above 1 cm.sup.3 /g.
- 9. Amorphous silica according to claim 1 having a mercury pore volume of above 1.2 cm.sup.3 /g.
- 10. Amorphous silica according to claim 1 having a Mean Pore Diameter between 25 and 100 nm.
- 11. Amorphous silica according to claim 10 having a Mean Pore Diameter above 40 nm.
- 12. Amorphous silica according to claim 1 having a structural water content of between 3.5 and 5.0%, a BET surface area of 50 to 200 m.sup.2 /g, a pH in a 5% solution of between 6 and 7.5, a loose bulk density of between 180 and 300 g/l, and a skeletal density of above 2.1 g/cm.sup.3.
- 13. Amorphous silica according to claim 12 having a structural water content of between 4.0 and 4.5%.
- 14. Amorphous silica according to claim 12 having a BET surface area of 50 to 150 m.sup.2 /g.
- 15. Amorphous silica according to claim 12 having a loose bulk density of between 200 and 250 g/l.
- 16. Process for the production of amorphous silicas having an RDA value of between 30 and 70; an oil absorption capacity of between 100 and 155 cm.sup.3 /100 g; and a BET surface area of up to 200 m.sup.2 /g, said process comprising:
- a) adding a 17.0 to 21.5% solution of 2.1 to 2.5 Molar Ratio silicate solution to water,
- b) then further adding a 17.0 to 21.5% solution of 2.1 to 2.5 Molar Ratio silicate solution together with a 15 to 20% sulfuric acid solution, over period of over 40 minutes at such flow rates that the pH is maintained in the range from 8.0 to 9.0,
- c) then aging the resultant slurry for a perod of 0 to 30 minutes at a temperature of 90 to 100.degree. C.,
- d) doing a second addition to a 15 to 20% sulfuric acid solution to bring the pH down to pH 3 to 5,
- e) aging the resulting slurry for a period of 0 to 20 minutes at pH 5 at a temperature of between 90 and 100.degree. C.,
- f) adjusting the pH to pH 3.5 to 5, and
- g) eventually filtering, washing and drying the final slurry.
- 17. Process as claimed in claim 16 in which the addition of said silicate solution together with the sulfuric acid solution is made over a period of less than 80 minutes.
- 18. Process as claimed in claim 16 in which the first aging step is carried out over a period of 8 to 12 minutes.
- 19. Process as claimed in claim 16 in which the second aging step is carried out over a period of 8 to 12 minutes.
Priority Claims (1)
Number |
Date |
Country |
Kind |
95304614 |
Jun 1995 |
EPX |
|
Parent Case Info
This is a continuation under 35 U.S.C. section 120 of PCT application PCT/EP96/02535 which designated the United States, filed internationally on Jun. 10, 1996.
US Referenced Citations (19)
Foreign Referenced Citations (5)
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0 139 754 |
May 1985 |
EPX |
0 272 380 |
Jun 1988 |
EPX |
0 368 130 |
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EPX |
1 598 233 |
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GBX |
A 9202454 |
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WOX |
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/EP96/02535 |
Jun 1996 |
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