Novel silica products and silicone rubber containing same coated silica aerogel, silicone rubber reinforced therewith and method of making

• US 2,870,108 A
• Filed: 05/06/1954
• Issued: 01/20/1959
• Est. Priority Date: 05/06/1954
• Status: Expired due to Term

• Current Assignee: Ralph F. Nickerson
• Original Assignee: Ralph F. Nickerson
• Inventors: Nickerson, Ralph F.
• Application Number:
  US03/428,115
• Time in Patent Office: 1,720 Days
• US Class Current: 524/261
• CPC Class Codes: C07F 7/025 without C-silicon linkages
• CPC Class Codes: C08K 3/36 Silica
• CPC Class Codes: C08L 83/04 Polysiloxanes

Claims

1. A PROCESS OF PRODUCING IMPROVED SILICA AEROGELS WHICH COMPRISES COMMINUTING IN AN AIR ATTRITION MILL HYDROPHILIC SILICA AEROGEL PARTICLES HAVING AN ACID NUM BER BETWEEN 0.3 AND 3. A SURFACE AREA BETWEEN 100 AND 600 SQUARE METERS PER GRAM, A BULK DENSITY OF 2 TO 8 POUNDS PER CUBIC FOOT AND AN ULTIMATE PARTICLE SIZE BETWEEN ABOUT 5 AND 40 MILLIMICRONS AND CONCURRENTLY SPRAYING SAID PARTICLES WITH DROPLETS CONTAINING TETRA ETHYL ORTHOSILICATE, SAID SILICATE BEING APPLIED IN AMOUNTS OF ABOUT 3 TO 20% BY WEIGHT, BASED ON THE DRY SILICA AEROGEL PARTICLES, WHEREBY SILICA AEROGELS ARE OBTAINED WHICH ARE HYDROPHILIC TO PARTIALLY HYDROPHOBIC BUT NON ORGANOPHILIC, SAID COMMINUTING STEP BEING CARRIED OUT IN AN ATMOSPHERE OF AIR AT A TEMPERATURE BETWEEN ABOUT 110 AND 200* C. UNTIL SAID AEROGEL PARTICLES HAVE AN AGGREGATE PARTICLE SIZE BETWEEN 0.01 AND 15 MICRONS.