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AssigneeMisuzawa Industrial Chemicals, Ltd.
InventorsKiyoshi Abe, Kazuhiko Suzuki, Hiroshi Ogawa, Masaichi Kikuchi
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A porous and spherical silica is recovered in high yields from a neutralized product of an alkali silicate obtained by using an acrylamide type polymer as a coagulation growing agent, and the above silica is reacted as a precursor with a metal compound of the Group II of periodic table in an aqueous medium to obtain amorphous or fine, laminar and crystalline porous and spherical silica or silicate granules having a high degree of true sphericality, a symmetrical grain size distribution and a refractive index over a range of from 1.4 to 1.7. The porous and spherical granules have a primary grain diameter of 0.3 to 30 .mu.m as observed through an electron microscope, have an apparent specific gravity of from 0.05 to 0.5 g/ml, and are cheaply obtained in high yields, and can hence be used as a filler for various paints and resins. In particularly, the granules excellently disperse in the resins, have a refractive index close to those of the resins, are not crushed during the kneading with resins or extrusion, or do not damage the apparatus. The films obtained by using these granules exhibit very excellent transparency, anti-blocking property and scar resistance. Moreover, the porous and spherical zinc phyllosilicate type granules having fine grain sizes and symmetrical grain size distributions, are excellent in their odor scavenging property and sweat controlling property.
A process for producing porous and spherical silica granules comprising mixing an aqueous solution of an alkali silicate, an acrylamide polymer and an aqueous solution of an acid of a partly neutralizing amount together, leaving the mixture solution to stand to form a granular material composed of a partly neutralized product of the alkali silicate, and separating the granular material followed by neutralization with an acid.
Porous and spherical silica or silicate granules comprising a silica or a silicate having a composition, SiO.sub.2 :MO=99:1 to 50:50 (wherein M is a metal of the Group II of periodic table) as expressed by a weight ratio based on the oxides, and further having amorphous or fine laminar crystalline property as observed through X-ray diffraction, independent and distinct spherical shapes with a true sphericality expressed by a ratio D.sub.S /D.sub.L of a long diameter D.sub.L to a short diameter D.sub.S of the granules of from 0.8 to 1.0, a BET specific surface area of from 50 to 800 m.sup.2 /g, a sharpness of granular size distribution defined by the relation.
An anti-blocking agent for resin films comprising porous and spherical silicate granules which have a composition SiO.sub.2 :MO=99:1 to 50:50 (wherein M is a metal of the Group II of periodic table), as expressed by a weight ratio based on the oxides, amorphous or fine laminar crystalline property as observed through X-ray diffraction, independent and distinct spherical shapes with a true sphericality expressed by a ratio D.sub.S /D.sub.L of a long diameter D.sub.L to a short diameter D.sub.S of the granules of from 0.8 to 1.0, and a grain diameter of from 0.3 to 20 .mu.m as observed through a scanning electron microscope.
Dependencies are inferred from the claim text.