Glass manufacturing – Processes – Self-supporting particle making
Patent
1983-05-23
1985-10-29
Tufariello, T. M.
Glass manufacturing
Processes
Self-supporting particle making
106 75, 428406, B32B 516, C03B 1910
Patent
active
045498920
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a material. In a particular aspect this invention relates to hollow microspheres.
It is known to make hollow microspheres by the process of U.S. Pat. No. 3,796,777, the prior art disclosed therein, and U.S. Pat. Nos. 2,797,201; 2,978,340; 3,030,215 and 3,699,050.
However, various of the prior art processes have difficulties such as producing ammonia as a pollutant.
The present invention provides a hollow microsphere wherein the inner portion of the shell of which comprises the reaction product of a silicate and a first insolubilizing agent, the outer portion of the shell of which comprises the reaction product of a silicate and a second insolubilizing agent and wherein the equivalent ratio of silicate to, respectively, the first and second insolublizing agent is less in respect of said inner portion than said outer portion.
Preferably the silicate is selected from the group consisting of sodium and potassium silicate.
Preferably the first insolubilizing agent is a weak acid.
Preferably the weak acid is selected from the group consisting of boric and phosphoric acid.
Preferably the second insolubilizing agent is selected from the group consisting of weak acids and salts capable of reacting with the silicate to form an insoluble reaction product.
Preferably said salts are selected from the group consisting of calcium salts, magnesium salts, aluminium salts and salts of polyvalent metals capable of reacting with the silicate to form an insoluble reaction product.
Preferably the second insolubilizing agent is selected from the group consisting of boric and phosphoric acid.
In one instance the second insolubilizing agent is different to the first insolubilizing agent.
Preferably the first and the second insolubilizing agents are the same.
Preferably the equivalent ratio of the silicate to the first insolubilizing agent in the inner portion is such that unreacted silicate remains therein.
Preferably the equivalent ratio of the silicate to the second insolubilizing agent in the outer portion is such that substantially no unreacted silicate remains therein.
Preferably the second insolubilizing agent is present in said shell to a depth of not more than 50% thereof or, more preferably, not more than 25%.
Preferably the silicate is sodium silicate, wherein the first and second insolubilizing agents are both boric acid and wherein the weight ratio of silicate to second insolubilizing agent in the outer portion, expressed as Na.sub.2 O:B.sub.2 O.sub.3, is from 1.6-3:1 preferably 1.8-2.4:1 and most preferably about 2:1.
Preferably said shell contains an hydroxylated and/or an oxygenated organic compound.
Preferably said compound is ethylene glycol diacetate
Preferably the microspheres have an effective density of 0.18-0.21 gm/cc, a size of 10-200 micron, a shell wall thickness of 1-2 micron and a crush resistance of 150-1500 psi.
Preferably the microspheres have a silane or a siloxane on the surface thereof.
The present invention also provides a process for producing hollow microspheres comprising forming a feedstock containing water, a silicate and a first insolubilizing agent, spray drying the feedstock to form hollow microspheres and applying to the hollow microspheres so formed a second insolubilizing agent whereby to produce hollow microspheres the inner portion of the shell of which comprises the reaction product of the silicate and the first insolubilizing agent, the outer portion of which comprises the reaction product of the silicate and the second insolubilizing agent and wherein the equivalent ratio of silicate to, respectively the first and second insolubilizing agent is less in respect of said inner surface than said outer portion.
In a preferred aspect the present invention provides a process for producing hollow microspheres comprising
(a) mixing together an aqueous solution (i) containing a silicate and an aqueous solution (ii) containing a first insolubilizing agent to form a feedstock,
(b) forming the feedstock into droplets and drying the droplets to form hollow microspheres,
REFERENCES:
patent: 2797201 (1957-06-01), Veatch
patent: 2978340 (1961-04-01), Veatch
patent: 3030215 (1962-04-01), Veatch
patent: 3699050 (1972-10-01), Henderson
patent: 3794503 (1974-02-01), Netting
patent: 3960583 (1976-06-01), Netting
patent: 4132560 (1979-01-01), Marquisee
patent: 4173491 (1979-11-01), Abrams
patent: 4340642 (1982-07-01), Netting et al.
Baker Alfred G.
Baker Andrew J.
LandOfFree
Process for producing hollow, bilayered silicate microspheres does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing hollow, bilayered silicate microspheres, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing hollow, bilayered silicate microspheres will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-726989