Process for producing microcapsules

Claim 2

A PROCESS FOR PRODUCING MICROCAPSULES OF A HYDROPHOBIC OIL SOLUTION COMPRISING THE SEQUENTIAL STEPS OF ADDING AT LAAST ONE POLYISOCYANATE COMPOUND, POLYISOTHIOCYANATE COMPOUND, OR A PREPOLYMER THEREOF, TO SAID HYDROPHOBIC OIL SOLUTION IN AN AMOUNT SUFFICIENT TO PROVIDE MICROCAPSULE WALLS WITH LOW POROSITY, PREPARING AN EMULSION OF SAID HYDROPHOBIC OIL SOLUTION IN A COACERVATE DISPERSION COMPRISING AT LEAST TWO HYDROPHILIC HIGH MOLECULAR WEIGHT COMPOUND COLLOIDS HAVING OPPOSITE ELECTRICAL CHARGES FROM EACH OTHER, THEN CAUSING COMPLEX COACERVATION TO FORM COACERVATE WALLS OF SAID AT LEAST TWO COLLOIDS AROUND DROPLETS OF SAID HYDROPHOBIC OIL SOLUTION BY ADDING WATER THERETO, ADJUSTING THE PH THEREOF OR BY A COMBINATION OF ADDING WATER AND ADJUSTING THE PH, COOLING TO CAUSE GELLING OF THE COACERVATE WALLS AND HARDENING SAID COACERVATE WALLS BY A COMBINATION OF ADDING A HARDENING AGENT TO THE SYSTEM AND ADJUSTING THE PH OF THE SYSTEM TO AN ALKALINE CONDITION.

Claim 3

The process for producing microcapsules of claim 1, wherein the combination of said colloids is selected from members of the group consisting of gelatin, casein, albumin, alginate, fibrinogen, gum arabic, carboxymethyl cellulose, cellulose phthalate, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, and carrageenan. anhydride copolymer, carrageenan.

Claim 4

The process for producing microcapsules of claim 2, wherein one of said colloids is gelatin.

Claim 5

The process for producing microcapsules of claim 1, wherein said hydrophobic oil is a mineral oil, an animal oil, synthetic oil, or a vegetable oil.

Claim 6

The process for producing microcapsules of claim 4, wherein said mineral oil is petroleum or distillates thereof, wherein said vegetable oil is peanut oil, linseed oil, soybean oil, castor oil or corn oil, wherein said animal oil is fish oil, or lard oil, and wherein said synthetic oil is a biphenyl derivative, a phosphoric acid derivative, a naphthalene derivative, a phthalic acid derivative, or a salicylic acid derivative.

Claim 7

The process for producing microcapsules of claim 5, wherein said mineral oil is kerosene, gasoline, naphtha, or paraffin oil.

Claim 8

The process for producing microcapsules of claim 1, wherein said hydrophobic oil solution contains additionally an anionic, a cationic, or a nonionic surface active agent.

Claim 9

The process for producing microcapsules of claim 1, wherein said polyisocyanates or polyisothiocyanates are diisocyanates, diisothiocyanates, triisocyanates, or triisothiocyanates.

Claim 10

The process for producing microcapsules of claim 1, wherein said polyisocyanate, said polyisothiocyanate, or said prepolymer thereof is m-phenylene diisocyanate, p-phenylenediisocyanate, 2, 6-tolylenediisocyanate, 2,4-tolylenediisocyanate, naphthalene-1, 4-diisocyanate, diphenylmethane-4,4''-diisocyanate, 3,3''-dimethoxy-4,4''-biphenyldiisocyanate, 3,3-dimethyldiphenylmethane-4,4''-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, 4,4''-diphenylpropanediisocyanate, trimethylenediisocyanate, hexamethylenediisocyanate propylene-1, 2-diisocyanate, butylene-1,2-diisocyanate, ethylidynediisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylenediisothiocyanate, xylylene-1,4-diisothiocyanate, ethylidynediisocyanate, 4,4'',4''''-triphenylmethanetriisocyanate, toluene-2,4,6-triisocyanate, polymethylenepolyphenyl-triisocyanate, 4,4''-dimethyldiphenylmethane-2,2'',5,5''-tetraisocyanate, the addition product of hexamethylenediisocyanate and hexanetriol, the addition product of 2,4-tolylenediisocyanate and catechol, the addition product of tolylenediisocyanate and hexanetriol, the addition product of tolylenediisocyanate and trimethylolpropane, the addition product of xylylenediisocyanate and trimethylolpropane, or the addition product of hexamethylenediisocyanate and trimethylolpropane.

Claim 11

The process for producing microcapsules of claim 1, wherein said polyisocyanate compound, polyisothiocyanate compound, or prepolymer thereof is present in an amount ranging from About 1/300 to 1/5 parts by weight for each part by weight of said hydrophobic oil solution.

Claim 12

The process for producing microcapsules of claim 1, wherein a shock preventing agent selected from the group consisting of modified cellulose, an anionic starch derivative, an anionic acid polysaccaride, a condensate of naphthalene sulfonic acid and formalin, a hydroxyethyl cellulose derivative, a copolymer of vinylbenzene sulfonate and a copolymer of sodium acrylate is added to the system after said gelation and prior to hardening.

Claim 13

The process for producing microcapsules of claim 11, wherein said shock preventing agent comprises carboxymethyl cellulose or carboxymethyl starch.