Claims
- 1. A process for the production of silica beads having a substantially spherical morphology and a mean particle size of at least 80 μm, a maximum BET specific surface area of 130 m2/g, a fill density in paced state (DRT) of greater than 0.32, and a total pore volume of at least 1.6 cm3/g, including providing a silica suspension by reacting a silicate with an acidifying agent and precipitating silica therefrom, and then drying/atomizing such precipitate, said silica precipitation and atomization comprising:(i) preparing a base mixture containing at least a portion of the silicate required for complete reaction and an electrolyte; (ii) adding said acidifying agent to such base mixture as to adjust the pH thereof to a value of about 7; (iii) optionally, simultaneously adding any remaining silicate and any required additional acidifying agent to said base mixture; (iv) adjusting the dry solids content of the resulting suspension to at least 18% and adjusting the pH thereof to a value of at least 4; and (v) atomizing such adjusted suspension to dryness.
- 2. The process as defined by claim 1, comprising the step (iii) and thereafter adding a supplementary amount of acidifying agent to the reaction medium.
- 3. The process as defined by claim 2, comprising adding such amount of supplementary acidifying agent as to adjust the pH of the reaction medium to a value ranging from about 3 to about 6.5.
- 4. The process as defined by claim 1, said electrolyte comprising an alkali or akaline earth metal salt.
- 5. The process as defined by claim 4, said salt comprising a salt of the acidifying agent.
- 6. The process as defined by claim 1, comprising (iv) adjusting the dry solids content of the resulting suspension to at least 25%.
- 7. An elastomeric matrix material comprising a reinforcing amount of the spherical silica beads as defined by claim 1.
- 8. A shaped article comprising the reinforced elastomeric matrix as defined by claim 7.
Priority Claims (1)
Number |
Date |
Country |
Kind |
89/05812 |
May 1989 |
FR |
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Parent Case Info
This application is a divisional of application Ser. No. 07/517,719, filed May 2, 1990 now U.S. Pat. No. 6,107,226 issued Aug. 22, 2000.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
6107226 |
Chevallier |
Aug 2000 |
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