Claims
- 1. Hydrophobic silicic acid having the following properties:
- ______________________________________BET surface acc. to DIN 66 131 m.sup.2 /g 110 .+-. 30Average size of the primaryparticles from EM pictures nm 15-22Loss after drying acc. to DIN55 921 after 2 hours at 105.degree. C. % <2.5Loss at red heat (related to thesubstance dried for 2 hours at105.degree. C.) acc. to DIN 55 921 % 5.5 .+-. 1.5pH value (in 5% aqueousdispersion) acc. to DIN 53 200 7 .+-. 1Conductivity (in 4% aqueousdispersion) .mu.S 600Tamped density of the unaeratedsubstance acc. to DIN 53 194 g/l 50 .+-. 20Water wettability <0.05Carbon content % 2.5 .+-. 0.6Water absorption at 30.degree. C. & 30% RM % 1.2 .+-. 0.4at 30.degree. C. & 70% % 1.5 .+-. 0.5DBP adsorption % 260 .+-. 30______________________________________
- said hydrophobic silicic acid having been prepared from a precipitated silicic acid by treating and agitating said silicic acid with a hydrophobic agent in a ratio of 10:0.5 to 10:3 followed by tempering for 60 to 180 minutes at a temperature of 200.degree. C. to 400.degree. C. and grinding to form a finely divided product, and said precipitated silicic acid having the following properties:
- ______________________________________BET surface acc. to DIN 66 131 m.sup.2 /g 150 .+-. 30Average size of the primary particlesfrom EM pictures nm 15-22Loss after drying acc. to DIN 55921 after 2 hours at 150.degree. C. % 2.5-3.5Loss at red heat (related to thesubstance dried for 2 hours at105.degree. C.) acc. to DIN 55 921 % 3 .+-. 0.5pH value (in 5% aqueous dispersion)acc. to DIN 53 200 3.5-5.5Conductivity (in 5% aqueous dispersion) .mu.S <500Tamped density of the unaeratedsubstance acc. to DIN 53 194 g/l 60 .+-. 20SO.sub.3 content (related to thesubstance dried for 2 hours at105.degree. C.) % <0.3Na.sub.2 O content (related to thesubstance dried for 2 hours at105.degree. C.) % <0.3______________________________________
- 2. Hydrophobic silicic acid having the following properties:
- ______________________________________BET surface acc. to DIN 66 131 m.sup.2 /g 110 .+-. 30Average size of the primaryparticles from EM pictures nm 15-22Loss after drying acc. to DIN55 921 after 2 hours at 105.degree. C. % <2.5Loss at red heat (related to thesubstance dried for 2 hours at105.degree. C.) acc. to DIN 55 921 % 5.5 .+-. 1.5pH value (in 5% aqueous dis-persion) acc. to DIN 53 200 7 .+-. 1Conductivity (in 4% aqueousdispersion) .mu.S <600Tamped density of theunaerated substance acc. toDIN 53 194 g/l 50 .+-. 20Water wettability <0.05Carbon content % 2.5 .+-. 0.6Water absorption at 30.degree. C. & 30%RM % 1.2 .+-. 0.4at 30.degree. C. & 70%RM % 1.5 .+-. 0.5DBP adsorption % 260 .+-. 30______________________________________
- said hydrophobic silicic acid having been prepared by treating and agitating a precipitated silicic acid with a hydrophobic agent and grinding to form a finely divided product, said precipitated silicic acid having the following properties:
- ______________________________________BET surface acc. to DIN 66 131 m.sup.2 /g 150 .+-. 30Average size of the primary particlesfrom EM pictures nm 15-22Loss after drying acc. to DIN 55921 after 2 hours at 150.degree. C. % 2.5-3.5Loss at red heat (related to thesubstance dried for 2 hours at105.degree. C.) acc. to DIN 55 921 % 3 .+-. 0.5pH value (in 5% aqueous dispersion)acc. to DIN 53 200 3.5-5.5Conductivity (in 5% aqueous dispersion) .mu.S <500Tamped density of the unaeratedsubstance acc. to DIN 53 194 g/l 60 .+-. 20SO.sub.3 content (related to thesubstance dried for 2 hours at105.degree. C.) % <0.3Na.sub.2 O content (related to thesubstance dried for 2 hours at105.degree. C.) % <0.3______________________________________
- 3. An elestomeric forming composition comprising precipitated silicic acid as defined in claim 1 as a reinforcing filler in a mass which may be hardened into an elastomer.
- 4. An elastomeric forming composition according to claim 3 wherein a hot vulcanizing diorganopolysiloxane elastomer is used as the elastomer.
- 5. An elastomeric forming composition according to claim 3 wherein an organopolysiloxane elastomer which may be hardened at room temperature is used as the elastomer.
- 6. An elastomeric forming composition according to claim 5 wherein a 2-component silicone molding material is used as the organopolysiloxane elastomer and which is hardenable at room temperature.
- 7. An elastomeric forming composition according to claim 5 wherein a 1-component sealing mass for joints is used as the organopolysiloxane elastomer and which is hardenable at room temperature.
- 8. A cured elastomer composition comprising a finely divided filler which is a precipitated silicic acid as defined in claim 1 homogeneously dispersed in the elastomeric binder.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2628975 |
Jun 1976 |
DEX |
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Parent Case Info
This is a continuation of application Ser. No. 810,441 filed June 27, 1977, now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3132961 |
Pierpoint |
May 1964 |
|
3649588 |
Kennedy-Skipton |
Mar 1972 |
|
3677784 |
Nilzsche et al. |
Jul 1972 |
|
Continuations (1)
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Number |
Date |
Country |
Parent |
810441 |
Jun 1977 |
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