CA1104882A - Encapsulation process - Google Patents
Encapsulation processInfo
- Publication number
- CA1104882A CA1104882A CA164,086A CA164086A CA1104882A CA 1104882 A CA1104882 A CA 1104882A CA 164086 A CA164086 A CA 164086A CA 1104882 A CA1104882 A CA 1104882A
- Authority
- CA
- Canada
- Prior art keywords
- water
- immiscible
- phase
- aqueous phase
- organic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
- A01N25/26—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests in coated particulate form
- A01N25/28—Microcapsules or nanocapsules
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/02—Making microcapsules or microballoons
- B01J13/06—Making microcapsules or microballoons by phase separation
- B01J13/14—Polymerisation; cross-linking
- B01J13/16—Interfacial polymerisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/30—Low-molecular-weight compounds
- C08G18/302—Water
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Wood Science & Technology (AREA)
- Agronomy & Crop Science (AREA)
- Medicinal Chemistry (AREA)
- Pest Control & Pesticides (AREA)
- Plant Pathology (AREA)
- Dispersion Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Dentistry (AREA)
- Polymers & Plastics (AREA)
- Zoology (AREA)
- Environmental Sciences (AREA)
- Manufacturing Of Micro-Capsules (AREA)
- Medicinal Preparation (AREA)
- Fats And Perfumes (AREA)
- Fireproofing Substances (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
Abstract
ENCAPSULATION PROCESS
Abstract of the Disclosure Encapsulation process to prepare encapsulated water-immiscible material em-ploying an organic polyisocyanate inter-mediate to form a polyurea capsule enclosure around a water-immiscible material dispersed in an aqueous continuous phase comprising the steps of heating the dispersion or adding a catalyst, and optionally adjusting the pH
to a value between 0 and 14.
Abstract of the Disclosure Encapsulation process to prepare encapsulated water-immiscible material em-ploying an organic polyisocyanate inter-mediate to form a polyurea capsule enclosure around a water-immiscible material dispersed in an aqueous continuous phase comprising the steps of heating the dispersion or adding a catalyst, and optionally adjusting the pH
to a value between 0 and 14.
Description
This invention relates -to encapsulation and particularly to the production of small or minute capsules constituted by a skin or a thin wall of organic composition enclosing a body of material such as a liquid. The p:rocess of this invention is di-rected to the production of such capsules which may be produced to a predetermined size, and in a convenient and rapid method by chemical reaction in situ, wherein a suspension or a collection of discrete spheres or capsular spheroids is ~ormed in a body of liquid which then may be readily separated or retained and used in said liquid.
Capsules of this nature and description have a variety of uses, such as for containing dyes, inks, chemical reagents, pharmaceuticals, flavoring materials, fungicides, bactericides, pesticides, such as herbicides, insecticides and the like, which substances can be dissolved, suspended or otherwise dispersed in or as the material to be enclosed by the capsule. The material to be encapsulated can be employed in the initial dispersion at a temperature above its melting point, or dissolved or dispersed ~0 in suitable water-immiscible organic solvent. The nature of the ~ water-immiscible material to be encapsulated can be organlc or - inorganic in origin. Once encapsulated, the liquid or other form is preserved until it is re].eased by some means or instrumentality that breaks, crushes, melts, dissolves or otherwise removes the capsule skin, or until release by diffusion is effected under suitable conditions. An important specific aspect of this inven-tion, together with other features and advantages contemplated . by the invention, is the procedure for polymerization involving : the reaction between polyisocyanate monomers, to produce a cap-~ 30 sular skin of polyurea.
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D C IPTION OF T~IE PRIOR ART
A variety of techniques have been heretofore used or described for encapsulation purposes. Among -these is the method, wherein the enclosing film is deposited by condensation and other procedures which involve polymerizing a substance contained in droplets or in a surrounding continuous liquid phase, so as to deposit the resulting polymer at the surface of such droplets.
Another method involves the shooting of droplets through a falling film of liquid capsule-wall material which then solidifies around the individual clroplets. Various methods of encapsulation by interfacial condensation between direct-acting, complimentary reactants are known. Within these methods are reactions for producing various types of polymers as the capsule walls.
Many of such reactions to produce the coating substance occur be-tween an amine which must be of at least difunctional character and a second reactant intermediate of acid or, more accurately, acid-derived nature, which for producing a polyamide is a difunc-tional or polyfunctional acid chloride. The amines chiefly used or proposed in these methods are typified by ethylene diamine or the like, having at least two primary amino groups.
~` For many processes of encapsulation, there is a final requirement of separation of the encapsulated materials from the forming media. During the handling process, the capsule wall material is subjected to great stresses and strains. For this reason, the highly desirable thin skin or cell wall is greatly -~ restricted in the prior art methods. A particular object of the present invention is to provide a new and improved encapsulation process which is rapid and effective and which avoids the neces-sity of separation of the encapsulated material. A special ~;
~ ~- 3-advantage, therefore, is the permissible formation of extremely thin skin or cellular wall in conjunction with the capsules.
Interfacial polymerization generally involves bringing together two immiscible liquids, e.g., water and organic solvent, respectively, containing complimentary, direct-acting, organic intermediates that will react with each other to establish a solid polycondensate. Such polycondensates, such as a polyamide, polyester, polyurethane, polyurea, or like substances, can be formed from resin intermediates or monomers. It has also 10 been proposed to spray droplets of organic solvent containing a diacid chloride into an aqueous liquid conkaining~ Eor instance, ethylene glycol with the object of encapsulating the organic liquid or oil in polyester capsules. These efforts have fallen short of a practical value in various respects. For example, ; special apparatus is required for this technique. Further, various experiments have indicated the difficulty in establishing the desired capsules in discrete form whereby coalescense of the partially formed capsules into a heterogeneous mass of materials lacking distinct capsule formation will result. Control of cap-sule size or uniformity is troublesome in the prior art method.
The processes appear limited in types of reactions and products involved. One particular method of encapsulation by interfacial polycondensation is disclosed in U.S. Patent 3,577,515, issued May 4r 1971. This patent describes a continuous or batch method which requires a first reactant and a second reactant complimen-tary to the first reactant with each ~eactant in separate phases, .-such that the first and second reactant react at the interfacebetween the droplets to form encapsulated droplets. As will become apparent hereinafter, the instant invention eliminates the necessity for a second reactant wherein it has been found that a polyurea type encapsulation body can be formed with great ease and provides special advantages.
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In contradistinction to the prior art and in accor-dance with the preferred practice of ~he present invcntion, it has been discovered that effective encapsulation by interfacial polymerization of an organic isocyanate intermedia~e can be effec-ted in a process which utilizes t~70 substantially immiscible liquids, one termed an aqueous phase and ~he other termed an organic phase, and which comprises establishing a physical dis-persion of the organic phase in the aqueous phase, said organic phase containing the organic isocyanate intermediate for the polyurea capsule skin or enclosure. The interfacial polymeri-zation of the present inven~ion to form the capsular wall involves hydrolysis of an isocyanate monomer to form an amine which in ; turn reacts with another isocyanate monomer to ~orm the polyurea - enclosure. During the hydrolysis of the isocyanate monomer, car-lS bon dioxide is liberated. The addition of no other reac~ant is required once the dispersion establishing drop1ets of the organic phase ~ithin a continuous liquid phase, i.e., aqueo~ls phase, has - been accomplished. Thereafter, and preferably with moderate agi-tation of the dispersion, the ormation of the polyurea capsule skin or enclosure around the dispersed organic droplets is brough about by heating the continuous liquid phase or by introducing a catalytic amount of a basic amine or other agent capable of in creasing the rate of isocyanate hydrolysis, such as tri-n-butyl tin acetate, optionally in addition adjusting the pH of the dis-persion, thereby effecting the desired condensation reaction at ~he interface between the organic droplets and the continuous phase.
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In this fashion, fully satisfactory, discrete capsules are formed having a skin consisting of the polyurea produced by the reaction and containing the encapsulated material. Within the process of the invention the reaction which forms the skin or enclosure for the capsule generally is complete, such that essent-ially no unreacted polyisocyanate remains. It is not n~cessary to separate the capsules for desired utilization, l.e., the en-capsulated material may be directly usable, depending upon the intended utilization. ~Iowever, such separation prior to utiliza-tion may be carried out by any of the normal separation processesinvolving, for example, settling, filtration or skimming of the collected capsules, washing and, if desired, drying. The product from the process of this invention is particularly suitable for direct agricultural pesticidal applications, additional agents can be added such as thickeners, biocides, surfactants and dis-persants to improve storage stability and aasé of application.
The initial dispersion of the organic phase in the a~ueous ~ phase may be assisted with an appropriate emulsifying or dis-- persing agent and the control of the size and uniformity of the ultimate capsules is readily effected by any convenient method to disperse one liquid into another.
In accordance with the present teachings, a process ~; is provided for encapsulating water-immiscible material within a shell of polyurea which comprises the steps of a) providing in an aqueous phase a solution comprising water, a surfactant and a protective colloid; b) adding to the aqueous phase a .~`, '.
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water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate; c) dispersing the water-immiscible phase in the aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
d) adjusting the pH of the aqueous phase to a value between O and 14; e) heating and maintaining the dispersed water-immiscible phase and aqueous phase in a temperature range of about 20C to about 90C. whereupon the water-ilNmiscible material is encapsulated within a polyurea capsular enclosure.
lOIn accordance with further embodiment of the present teachings, a process for encapsulating water-immiscible material with a polyurea capsule is provided which comprises the steps of ; a) providing an aqueQus phase a solution of water, a surfactant and a protective colloid; b) adding to the aqueous phase a water-immiscible phase comprising organic polyisocyanate, a water-immiscible material and a based organic tertiary amine catalyst in the amount of about 0.01~ to about 10.0~ by weight based on the organic phase; c) dispersing the water-immiscible phase in the aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase; d) adjusting the pH of the aqueous phase to a value between 0 and 14 whereupon the water-immiscible material is encapsulated within a polyurea capsular enclosure.
Within a further embodiment of the present teaching, a process is provided for encapsulating water-immiscible material with a polyurea capsule which comprises the steps of a) providing in an aqueous phase a solution of water, sur~actant and a protective colloid; b) add;ng to the aqueous solution a water-immiscible phase , ~
~ -6a-',, ' : ,. .. ,, -, . . ' : , , : :' ~ ' ' ' , ' . ' ' ' ' ' . :' ' .
comprising organic polyisocyanate, a water-immiscible material and an alkyl tin acetate catalyst in the amount of about 0.001~
to about 1.0% by weight based on t:he organic phase; c) dispersing the water-immiscible phase in the aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase; d) adjusting the pH of the aqueous phase to a value between 0 and 14 whereupon the wa-ter-immiscible material is encapsulated within the polyurea capsular enclosure.
By yet a further embodiment a process is provided for encapsulating water-immiscible material within a shell of polyurea which comprises the steps of a) providing in an aqueous phase a solution of water, surfactant and protective colloid; b) heating and maintaining the aqueous phase at a temperature range of about 20C. to about 90C.; c) adding to the aqueous phase a water-immiscible phase comprising the water-immiscible material to be encapsulated and an organic polyisocyanate; d) dispersing the water-immiscible phase in the aqueous phase to establish droplets `- of the water~immiscible phase in the aqueous phase; e) adjusting the pH of the aqueous phase to a value between 0 and 1~ whereupon the water-immiscible material is encapsulated with a polyurea , capsular enclosure.
In accordance with yet a further embodiment of the present teachings, capsules are produced by such process which ~ are capable of controIled release of encapsulated organic material ,; which comprises a thiocarbamate herbicide which is enclosed in the ~ ~ skin of the polyurea in the form of a microcapsule.
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BRIEE' DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic representation of one embodi-ment of a process according to the instant invention for pre-paring capsule dispersions;
FIG. 2 is a schema-tic representation of a second embodiment of a process according to the instant invention for preparing capsule dispersions; ancl FIG. 3 is a schematic representation of a third embodiment of a process according to the instant invention or preparing capsule dispersions.
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DETAILED DESCRIPTION OF THE INVENTION
In all cases, within the practice of the present inven-tion, the effective procedure involves first, producing, as by simple agitation, a solution of water, a suitable surfactant and protective colloid. These three ingredients comprise the aqueous phase or continuous phase of the process. The aqueous or continuous phase is essentially free of any components that will react with the material therein or any of such group of materials.
The surfactant and protective colloid in the aqueous phase do not enter into the polycondensation reaction by which the capsule wall is formed.
By way of further exemplification, the surfactants in the aqueous or continuous phase can be described as nonionic, : anionic, or cationic surfactants in the HLB (hydrophile-lipophile balance) range from about 12 to about 16. There are many sur-factants which satisfy this HLB range requirement. Among the acceptable surfactants are the compounds known as sodium iso-propyl naphthalene sulfonate, polyoxyethylenesorbitol oleate laurate, ethoxylated nonylphenols, however, the preferred sur-factant is of the class polyethylene glycol ethers of linear alcohols. Whereas the surfactant is described herein as placed in the aqueous phase, it can also be placed in the organic phase.
Without specific rsference to the phase in which the surfactant is placed, there will be a partitioning and distribution of the surfactant between each phase upon the mixing of the phases depending upon the relative solubility therein. Use of a surfac-tant may be omitted provided that a sufficiently high shear rate is employed to form the dispersion. In the preferred embodiment of this invention a surfactant is employed. The range of . 30 surfactant concentration found most acceptable in this system `. is from about 0.01 per cent to about 3.0 per cent by weight based ~: :
on the aqueous phase. Higher concentrations of surfactant may i~! :
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be used without increased ease of dispersibility.
Also present in the aqueous or continuous phase is a protective colloid which can be selected from a wide range of such materials. The usable protec:tive colloids can be exempli-fied by the following: Polyacrylates, methyl cellulose, poly-vinyl alcohol, polyacrylamide and poly(methylvinyl e-ther/maleic anhydride). The amount of colloid employed will depend upon various factors such as molecular weight, type and effectiveness within the media, compatability and the like. It has been Eound that the protective colloid can be added to the aqueous phase prior to addition of the organic phase to the aqueous phase Alternatively, the protective colloid can be added to the system following the addition of the organic phase or following the : dispersion thereof. As another alternative, the protective colloid can be added partially prior to addition of the organic phase and partially after the dispersion step. Generally, from about 0.1 per cent to about 5.0 per cent by weight based on the aqueous phase is used.
A second phase, known as the organic phase, comprises the material to be encapsulated, and a polyisocyanate. The material to be encapsulated can be used in a concentrated form or in a solution of a water-immiscible solvent. The material to be encapsulated can be used as the solvent for the polyisocyanate.
However, to achieve a desired concentration of active material in the final product, a water-immiscible organic solvent can be ' ~8--~ .
- used to dissolve ttle material to be encapsulatcd and polyiso cyanate. The m~terial to be enc~psulated and the polyisocyanat~
are addcd simultaneously to the aqueous phase. Whereas, the material to be encapsulated and the polyisocyanate may be added separate~ly ~ith s1O~1 agitat:ion in the reactor for a time surfi-cient to cause a homogeneous organic solution, the pre~erred method of simultaneous addition of the components of the organic phase is in a pre-mixed state. That is, the material to be encapsulated ~nd the polyisocyanate are pre-mixed to obtain a homogeneous phase be~ore addition to and mixing with the aqueous phase. The amount of the organic phase may vary ~rom about 1 per cent to about 75 per cent by volume of the aqueous phase present in the reaction vessel. The concentrations in the lol~er end of the range are relatively undesirable since they result in a very dilute suspension of capsules. The preferred amount of organic phase is about 25 per cent to about 50 per cent by volume.
The nature of the organic polyisocyanate determines ~ the release properties of the capsule formed by this process.;` 20 The polyisocyanates also determine the structural physical strength of the capsular skin. The organic polyisocyanates con-templated in this process include those members of the aromatic polyisocyanate class ~hich includes the aromatic diisocyanates, the aliphatic diisocyanate class, high molecular weight linear aliphatic diisocyanates and the isocyanate prc~-polymers. Repre-sentative of the aromatic diisocyanates and other polyisocyanates are the fo:llo~ing:
]L-Chloro-2,4-phenylene diisocyanate m Phenylene diisocyanate ~ p-Phenylene diisocyanate :, ~ 9_ ,.
4,4'Methylenebis (phenyl isocyanate)
Capsules of this nature and description have a variety of uses, such as for containing dyes, inks, chemical reagents, pharmaceuticals, flavoring materials, fungicides, bactericides, pesticides, such as herbicides, insecticides and the like, which substances can be dissolved, suspended or otherwise dispersed in or as the material to be enclosed by the capsule. The material to be encapsulated can be employed in the initial dispersion at a temperature above its melting point, or dissolved or dispersed ~0 in suitable water-immiscible organic solvent. The nature of the ~ water-immiscible material to be encapsulated can be organlc or - inorganic in origin. Once encapsulated, the liquid or other form is preserved until it is re].eased by some means or instrumentality that breaks, crushes, melts, dissolves or otherwise removes the capsule skin, or until release by diffusion is effected under suitable conditions. An important specific aspect of this inven-tion, together with other features and advantages contemplated . by the invention, is the procedure for polymerization involving : the reaction between polyisocyanate monomers, to produce a cap-~ 30 sular skin of polyurea.
. ~, .
. ~.
.. - : .
.
: . . ... - - .. ~ ' , ' .. .:
D C IPTION OF T~IE PRIOR ART
A variety of techniques have been heretofore used or described for encapsulation purposes. Among -these is the method, wherein the enclosing film is deposited by condensation and other procedures which involve polymerizing a substance contained in droplets or in a surrounding continuous liquid phase, so as to deposit the resulting polymer at the surface of such droplets.
Another method involves the shooting of droplets through a falling film of liquid capsule-wall material which then solidifies around the individual clroplets. Various methods of encapsulation by interfacial condensation between direct-acting, complimentary reactants are known. Within these methods are reactions for producing various types of polymers as the capsule walls.
Many of such reactions to produce the coating substance occur be-tween an amine which must be of at least difunctional character and a second reactant intermediate of acid or, more accurately, acid-derived nature, which for producing a polyamide is a difunc-tional or polyfunctional acid chloride. The amines chiefly used or proposed in these methods are typified by ethylene diamine or the like, having at least two primary amino groups.
~` For many processes of encapsulation, there is a final requirement of separation of the encapsulated materials from the forming media. During the handling process, the capsule wall material is subjected to great stresses and strains. For this reason, the highly desirable thin skin or cell wall is greatly -~ restricted in the prior art methods. A particular object of the present invention is to provide a new and improved encapsulation process which is rapid and effective and which avoids the neces-sity of separation of the encapsulated material. A special ~;
~ ~- 3-advantage, therefore, is the permissible formation of extremely thin skin or cellular wall in conjunction with the capsules.
Interfacial polymerization generally involves bringing together two immiscible liquids, e.g., water and organic solvent, respectively, containing complimentary, direct-acting, organic intermediates that will react with each other to establish a solid polycondensate. Such polycondensates, such as a polyamide, polyester, polyurethane, polyurea, or like substances, can be formed from resin intermediates or monomers. It has also 10 been proposed to spray droplets of organic solvent containing a diacid chloride into an aqueous liquid conkaining~ Eor instance, ethylene glycol with the object of encapsulating the organic liquid or oil in polyester capsules. These efforts have fallen short of a practical value in various respects. For example, ; special apparatus is required for this technique. Further, various experiments have indicated the difficulty in establishing the desired capsules in discrete form whereby coalescense of the partially formed capsules into a heterogeneous mass of materials lacking distinct capsule formation will result. Control of cap-sule size or uniformity is troublesome in the prior art method.
The processes appear limited in types of reactions and products involved. One particular method of encapsulation by interfacial polycondensation is disclosed in U.S. Patent 3,577,515, issued May 4r 1971. This patent describes a continuous or batch method which requires a first reactant and a second reactant complimen-tary to the first reactant with each ~eactant in separate phases, .-such that the first and second reactant react at the interfacebetween the droplets to form encapsulated droplets. As will become apparent hereinafter, the instant invention eliminates the necessity for a second reactant wherein it has been found that a polyurea type encapsulation body can be formed with great ease and provides special advantages.
. ~ .
~ RY 0~ THE I~FJ ~I0`~
In contradistinction to the prior art and in accor-dance with the preferred practice of ~he present invcntion, it has been discovered that effective encapsulation by interfacial polymerization of an organic isocyanate intermedia~e can be effec-ted in a process which utilizes t~70 substantially immiscible liquids, one termed an aqueous phase and ~he other termed an organic phase, and which comprises establishing a physical dis-persion of the organic phase in the aqueous phase, said organic phase containing the organic isocyanate intermediate for the polyurea capsule skin or enclosure. The interfacial polymeri-zation of the present inven~ion to form the capsular wall involves hydrolysis of an isocyanate monomer to form an amine which in ; turn reacts with another isocyanate monomer to ~orm the polyurea - enclosure. During the hydrolysis of the isocyanate monomer, car-lS bon dioxide is liberated. The addition of no other reac~ant is required once the dispersion establishing drop1ets of the organic phase ~ithin a continuous liquid phase, i.e., aqueo~ls phase, has - been accomplished. Thereafter, and preferably with moderate agi-tation of the dispersion, the ormation of the polyurea capsule skin or enclosure around the dispersed organic droplets is brough about by heating the continuous liquid phase or by introducing a catalytic amount of a basic amine or other agent capable of in creasing the rate of isocyanate hydrolysis, such as tri-n-butyl tin acetate, optionally in addition adjusting the pH of the dis-persion, thereby effecting the desired condensation reaction at ~he interface between the organic droplets and the continuous phase.
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In this fashion, fully satisfactory, discrete capsules are formed having a skin consisting of the polyurea produced by the reaction and containing the encapsulated material. Within the process of the invention the reaction which forms the skin or enclosure for the capsule generally is complete, such that essent-ially no unreacted polyisocyanate remains. It is not n~cessary to separate the capsules for desired utilization, l.e., the en-capsulated material may be directly usable, depending upon the intended utilization. ~Iowever, such separation prior to utiliza-tion may be carried out by any of the normal separation processesinvolving, for example, settling, filtration or skimming of the collected capsules, washing and, if desired, drying. The product from the process of this invention is particularly suitable for direct agricultural pesticidal applications, additional agents can be added such as thickeners, biocides, surfactants and dis-persants to improve storage stability and aasé of application.
The initial dispersion of the organic phase in the a~ueous ~ phase may be assisted with an appropriate emulsifying or dis-- persing agent and the control of the size and uniformity of the ultimate capsules is readily effected by any convenient method to disperse one liquid into another.
In accordance with the present teachings, a process ~; is provided for encapsulating water-immiscible material within a shell of polyurea which comprises the steps of a) providing in an aqueous phase a solution comprising water, a surfactant and a protective colloid; b) adding to the aqueous phase a .~`, '.
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water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate; c) dispersing the water-immiscible phase in the aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
d) adjusting the pH of the aqueous phase to a value between O and 14; e) heating and maintaining the dispersed water-immiscible phase and aqueous phase in a temperature range of about 20C to about 90C. whereupon the water-ilNmiscible material is encapsulated within a polyurea capsular enclosure.
lOIn accordance with further embodiment of the present teachings, a process for encapsulating water-immiscible material with a polyurea capsule is provided which comprises the steps of ; a) providing an aqueQus phase a solution of water, a surfactant and a protective colloid; b) adding to the aqueous phase a water-immiscible phase comprising organic polyisocyanate, a water-immiscible material and a based organic tertiary amine catalyst in the amount of about 0.01~ to about 10.0~ by weight based on the organic phase; c) dispersing the water-immiscible phase in the aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase; d) adjusting the pH of the aqueous phase to a value between 0 and 14 whereupon the water-immiscible material is encapsulated within a polyurea capsular enclosure.
Within a further embodiment of the present teaching, a process is provided for encapsulating water-immiscible material with a polyurea capsule which comprises the steps of a) providing in an aqueous phase a solution of water, sur~actant and a protective colloid; b) add;ng to the aqueous solution a water-immiscible phase , ~
~ -6a-',, ' : ,. .. ,, -, . . ' : , , : :' ~ ' ' ' , ' . ' ' ' ' ' . :' ' .
comprising organic polyisocyanate, a water-immiscible material and an alkyl tin acetate catalyst in the amount of about 0.001~
to about 1.0% by weight based on t:he organic phase; c) dispersing the water-immiscible phase in the aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase; d) adjusting the pH of the aqueous phase to a value between 0 and 14 whereupon the wa-ter-immiscible material is encapsulated within the polyurea capsular enclosure.
By yet a further embodiment a process is provided for encapsulating water-immiscible material within a shell of polyurea which comprises the steps of a) providing in an aqueous phase a solution of water, surfactant and protective colloid; b) heating and maintaining the aqueous phase at a temperature range of about 20C. to about 90C.; c) adding to the aqueous phase a water-immiscible phase comprising the water-immiscible material to be encapsulated and an organic polyisocyanate; d) dispersing the water-immiscible phase in the aqueous phase to establish droplets `- of the water~immiscible phase in the aqueous phase; e) adjusting the pH of the aqueous phase to a value between 0 and 1~ whereupon the water-immiscible material is encapsulated with a polyurea , capsular enclosure.
In accordance with yet a further embodiment of the present teachings, capsules are produced by such process which ~ are capable of controIled release of encapsulated organic material ,; which comprises a thiocarbamate herbicide which is enclosed in the ~ ~ skin of the polyurea in the form of a microcapsule.
: : :
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-6b-~ 2~, `r~`
` ::
':; ~ :. .. '. :' .' ' ' ' - ' ' ' - . .
~3~
BRIEE' DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic representation of one embodi-ment of a process according to the instant invention for pre-paring capsule dispersions;
FIG. 2 is a schema-tic representation of a second embodiment of a process according to the instant invention for preparing capsule dispersions; ancl FIG. 3 is a schematic representation of a third embodiment of a process according to the instant invention or preparing capsule dispersions.
~6c-,, ~ .
DETAILED DESCRIPTION OF THE INVENTION
In all cases, within the practice of the present inven-tion, the effective procedure involves first, producing, as by simple agitation, a solution of water, a suitable surfactant and protective colloid. These three ingredients comprise the aqueous phase or continuous phase of the process. The aqueous or continuous phase is essentially free of any components that will react with the material therein or any of such group of materials.
The surfactant and protective colloid in the aqueous phase do not enter into the polycondensation reaction by which the capsule wall is formed.
By way of further exemplification, the surfactants in the aqueous or continuous phase can be described as nonionic, : anionic, or cationic surfactants in the HLB (hydrophile-lipophile balance) range from about 12 to about 16. There are many sur-factants which satisfy this HLB range requirement. Among the acceptable surfactants are the compounds known as sodium iso-propyl naphthalene sulfonate, polyoxyethylenesorbitol oleate laurate, ethoxylated nonylphenols, however, the preferred sur-factant is of the class polyethylene glycol ethers of linear alcohols. Whereas the surfactant is described herein as placed in the aqueous phase, it can also be placed in the organic phase.
Without specific rsference to the phase in which the surfactant is placed, there will be a partitioning and distribution of the surfactant between each phase upon the mixing of the phases depending upon the relative solubility therein. Use of a surfac-tant may be omitted provided that a sufficiently high shear rate is employed to form the dispersion. In the preferred embodiment of this invention a surfactant is employed. The range of . 30 surfactant concentration found most acceptable in this system `. is from about 0.01 per cent to about 3.0 per cent by weight based ~: :
on the aqueous phase. Higher concentrations of surfactant may i~! :
~: . ` . , ,` . -` `
.
. `
be used without increased ease of dispersibility.
Also present in the aqueous or continuous phase is a protective colloid which can be selected from a wide range of such materials. The usable protec:tive colloids can be exempli-fied by the following: Polyacrylates, methyl cellulose, poly-vinyl alcohol, polyacrylamide and poly(methylvinyl e-ther/maleic anhydride). The amount of colloid employed will depend upon various factors such as molecular weight, type and effectiveness within the media, compatability and the like. It has been Eound that the protective colloid can be added to the aqueous phase prior to addition of the organic phase to the aqueous phase Alternatively, the protective colloid can be added to the system following the addition of the organic phase or following the : dispersion thereof. As another alternative, the protective colloid can be added partially prior to addition of the organic phase and partially after the dispersion step. Generally, from about 0.1 per cent to about 5.0 per cent by weight based on the aqueous phase is used.
A second phase, known as the organic phase, comprises the material to be encapsulated, and a polyisocyanate. The material to be encapsulated can be used in a concentrated form or in a solution of a water-immiscible solvent. The material to be encapsulated can be used as the solvent for the polyisocyanate.
However, to achieve a desired concentration of active material in the final product, a water-immiscible organic solvent can be ' ~8--~ .
- used to dissolve ttle material to be encapsulatcd and polyiso cyanate. The m~terial to be enc~psulated and the polyisocyanat~
are addcd simultaneously to the aqueous phase. Whereas, the material to be encapsulated and the polyisocyanate may be added separate~ly ~ith s1O~1 agitat:ion in the reactor for a time surfi-cient to cause a homogeneous organic solution, the pre~erred method of simultaneous addition of the components of the organic phase is in a pre-mixed state. That is, the material to be encapsulated ~nd the polyisocyanate are pre-mixed to obtain a homogeneous phase be~ore addition to and mixing with the aqueous phase. The amount of the organic phase may vary ~rom about 1 per cent to about 75 per cent by volume of the aqueous phase present in the reaction vessel. The concentrations in the lol~er end of the range are relatively undesirable since they result in a very dilute suspension of capsules. The preferred amount of organic phase is about 25 per cent to about 50 per cent by volume.
The nature of the organic polyisocyanate determines ~ the release properties of the capsule formed by this process.;` 20 The polyisocyanates also determine the structural physical strength of the capsular skin. The organic polyisocyanates con-templated in this process include those members of the aromatic polyisocyanate class ~hich includes the aromatic diisocyanates, the aliphatic diisocyanate class, high molecular weight linear aliphatic diisocyanates and the isocyanate prc~-polymers. Repre-sentative of the aromatic diisocyanates and other polyisocyanates are the fo:llo~ing:
]L-Chloro-2,4-phenylene diisocyanate m Phenylene diisocyanate ~ p-Phenylene diisocyanate :, ~ 9_ ,.
4,4'Methylenebis (phenyl isocyanate)
2,4-Tolylene diisocyanate Tolylene diisocyanate (60% 2,4-isomer, 40% 2,6-isomer) 2,6 Tolylene diisocyanate
3,3'-Dimethyl-4,4'-biphenylene diisocyanate
4,4'-Me~hylenebis (2-mel:hylphenyl isocyanatel 3,3'-Dimethoxy-4,4'-biphenylene diisocyanate 2,2',5,5'-Tetramethyl-4,4'-biphenylene diisocyanate 80~ 2,4- and 20% 2,6-isomer of tolylene diisocyanate Polymethylene polyphenylisocyanate (PAPI) It is highly desirable to use combinations of the above-mentioned organic polyisocyanates. Such combinations as, for example, polymethylene polyphenylisocyanate and -tolylene diisocyanate, containing 80% 2,4- and 20% 2,6-isomers, produce excellent cap-sular enclosures with exceptional controlled release properties.
The amount of organic polyisocyanate used in the pro- -cess will determine the wall content of the capsules formed therein. Generally, based on the organic phase, there will be greater than about 2 per cent by weight organic polyisocyanate present. However, this is by no means limiting and a greater amount can be used that is approaching 100 per cent. Clearly, 100 per cent would not be entirely desirable since this would result in a product with no encapsulated material. The preferred ` range is from about 2.0 per cent to about 75.0 per cent by weight of organic polyisocyanate, thereby ~orming an encapsulated product having a corresponding wall content, i.e., about 2.0 per cent to about 75.0 per cent. More particularly, the preferred range is from about 5.0 per cent to about 50.0 per cent wall content.
~ .
: - 10 -; ~ , ,r~" ~
In accordance ~itll preferred practice o~ th~ present invention, the follot~ing general steps comDrise the process which utilizes the t~Jo substantially immiscible phases describec above. In essence, the process comprises estabiishing a pnysi-cal dispersion of the organic phase in the aqueous or continuou, phase, such dispersion thereby establishing droplets of desired size in the aqueous phase. Thereafter, by adjusting the pH or the resulting mixture, and temperature ~ithin the appropriate temperature range, the desired condensation r~action is theréby effected at the interfaces between the droplets and the continu-ous phase, FIG. 1. Certain variations in the sequence of steps between adjustment of the pH and addition of required heat ~7ill be apparent in the ollowing discussion and examples.
The temperature of the two phase mixture, that is, the dispersion of the organic phase in the aqueous phase, is raised to about 40C. to about 60C. The temperature range for the condensation reaction within the present invention is between .
about 20C. to about 90~C. Whereas the heat ~o initiate the reaction can be applied to the dispersion OL the organic phase Z0 in the aqueous phase slmultanèously or after the adjustment of the pH to the desired value, the aqueous phase can be heated to the required temperature prior to the steps of addition of the organic phase and dispersion, FIG. 3~ In this alternative procedure, ~he adjustment of the pH is performed after the dis-persion is accomplished and the pH is maintained within the :::
limits to be discussed below.
Within one embodiment of the present invention, FIG. ~, it has been found that a catalyst capable of increasin~ the ra,e ::
--1 1 `- .
, of isocyanate hydrolysis, for example, the basic amine type, may be added to the organic phase or aqueous phase prior to the initlation oE the desired condensation reactiol~. However, this step is not necessary to the successful practice of the present invention. When it is selected to substitute a catalyst for the increase in temperature in the process, the product obtained thereby is comparable to a non catalyzed system. Increased temperature and catalyst can be used simultaneously to effect the desired polycondensation reaction. The catalyst in such a procedure is added preferably to the organic phase and is added to the system at the time o mixing of the aqueous and organic phases. Various catalysts have been found acceptable, their selection will depend upon factors easily determinable by one skilled in the art. It has been found that certain basic organic amines~ preferably the tertiary amines, and alkyl tin acetates such as tri-butyl tin acetate and di-n-butyl tin di-acetate are acceptable catalysts. When an alkyl tin acetate is used, about 0.001 per cent to about 1.0 per cent by weight based on the organic phase is employed. Included among the basic or-ganic tertiary amines are triethylene diamine, N3N,N',N'-tetra-methyl-1,3-butane-diamine, triethylamine, tri-n-butyl amine and the like. The amount of catalyst will vary with the particular system and conditions When a basic organic amine is used, about 0~01 per cent to about l0.0 per cent by weight based on the organic phase is employed.
Oftentimes it will be found that water will be slightly soluble in the water-immiscible material to be encapsulatedO The amount of water which will be dissolved in the material to be encapsulated wiIl depend upon the nature of the material.
.
.
,. ' ' ' '' , :. , - :
.
.
~ 2 Usually the amount of wa~er dissolved will be relatively minor.
Howevera when using a water-immiscible material that can dissolve an appreciable quantity of water, slight deviation in the normal processes described herein is preferred. In such a system it has been found that particles with poorly de~ined wall struc~
ture result. Well-defined microcapsules within the description of this invention can be prepared by adding an appropriate catalyst to the a~ueous phase after the emulsion is formed~
Thereby, the bulk of the polymeriæatlon takes place at the inter-face where the catalyst is present. No heating o~ the process mixture is advised, otherwise polymer will form not only on the surface, but an increased proportîon will form within the water~
immiscible material that can dissolve an appreciable amount of water. This procedure is preferably performed at about room tem-perature (15 to 30C.3. This method of addition of the catalyst to the aqueous phase after dispersion is not limited to encap-sulation of only water immiscible material that can dissolve appreciable quantity of water, but finds general applicability with any water immiscible material herein discussed and described.
It is satlsfactory to prepare the aqueous phase as described above~ While stirring the a~ueous phase, the organic phase is added, preferably in a pre-mixed state. Upon addition of the organic phase to the aqueous phase, a suitable dispersing means to disperse one liquid into the other is employed. Any high shear device can be used conveniently to obtain the desired droplet siæe within the range o from about 0.5 microns to about 4,00a microns. The actual range will depend upon the desired end use. As an example, the preferred range for most pesticidal applications is from about 1 micron to about 100 microns. The , .
~: ~ ~ " , - ~ .
.
Z
lnstant process is applicable to preparil~ widely varied but unlform si~ed capsules. Once the proper droplet size is obtained, the dispersion means employed to establish the desired droplet size is discontinued. Only mild agitation is required for the balance of the process~
The process of the instant invention is capable of satis~actory performance and production of encapsulated material without adjustment to a specific pH value. That is, no adjustment of the pH of the system need be made during the encapsulation 10 process. The encapsula~ion process will proceed at a pH value of between about 0 to about 14. The desirability of any adjust~
ment of pH to a par~icular value wil~ depend upon ~he nature of the systems components, such as surfactant~ colloid, catalyst, temperature, material to be encapsulated and the like. For lS e~ample9 if the p~ is allowed to drop below about 7.0, carbon dioxide will be liberated during the course of the reaction.
If it is desira~le to eliminate this evolution o carbon dioxide, then adjustment can be made to a pH value at least about 7Ø
Within the embodiment9 FIG. 1 and FIG. 2, the pH is adjusted 20 after dispersion and maintained at ~hat value for the remainder of the condensation reac~ion. The adjustment of the pH can take place in the aqueous phase prior to the addition and dispersion therein of the organic phaseO The adjustment and maintenance of a particular pH throughout the reaction can be accomplished with 25 varlous water soluble bases or acids nonreactive with the poly-~; isocyanate intermediate. Preferably3 concentrated sodium hydroxide (25% solution) 3 potassium hydroxide, hydrochloric acid and the like can be used.
.
:; :
.
The evolution of carbon dioxide may cause considerable undesirable foam formation and/or volume expansion which inter-fexes with the processing o the reaction mi~ture. An alternative to the adjustment of the pH in order to eliminate the excessive foam produced by the carbon dioxide evolution is the addition of a defoamer. By the use of a defoamer, it is possible to satisfac-torily produce the encapsulated material at an acid pH withuut the addition of caustic to l:he acidic system. The defoamer can be added at any time to the processing mixture wherein said poly-mer capsular enclosures are formed to encapsulate a water-immiscible material.
Whereas the desired condensation reaction at the inter-face between the droplets and the continuous phase occurs very rapidly, the majority within the first one-half hour of reaction time, in order to insure near completion of the condensation reaction throughout the system, the reaction conditions are con-tinued for from about 2 to 3 hours9 Under properly adjusted conditions or with a proper catalyst, the reaction time can be shortenedO At the end of this time, the formation of a capsule wall has been completed, thereby encapsulating the organic mat-- erial within the skin of a polycondensate, and there exis~s a ;~ usable encapsulated product. A specific feature of the present invention, which is highly desirable, resides in the fact that for certain intended applications, no further separa~ion or hand-ling of the encapsulated material is required~ i.e., the product is directly usable. The encapsulated material can be used for various direet applications at this point or indirectly by `~ incorporating the material into other products.
:;
~15-- ' The thickness or chemlcal composition of the capsule-wall can be selected or controlled in various ways~ For example, these properties can be afected by control of the reac~ion con-dition, by chemical selection~ especially in the creation of S eross linkage which is determined by the functionality of the polyisocy~nate in accordance with the inventlon. The thickness of the capsule skin can also be altered by varylng the amounts of reactants withi~ the organic phase. One convenient mode of con-trolling the size o the capsule ls adjustment of the speed of agitation, that i~) in bringing about the original disperslon of the organic phase, smaller capsules can be obtained with higher speeds of agitation resulting in a greater shearing force.
Tests have indicated ~hat capsules produced in accor-dance with the present invention can be utilized in the same manner as produets of other encapsulation procedures. Thus, for example, eneapsulated herbicides or insecticides ean be embodied in dispersions for applieation purposes~ for controlled release of the eneapsulated material at the desired loeality. Special utillty is noted for the encapsulation of various volatile or unsta~le insecticides and herbicides~ By encapsulation, prema-ture volat~lizatien or other deterioration of the material is avoided; such encapsulation can also serve the purpos~ of retard-ing or delaying action to the time when desired. Controlled release of these materials is important for environmental pro~
teetion and the proper effect on th~ organism to be controlled, as well as decreased toxicity on beneicial organisms.
The present invention may be practiced in a batch or bateh-like form or in a continuous or con~inuous-like form~
`, ~ -. . . . .. ~ .... . , . . . . . -When the inventioll is prnctlced in a rnanner rcsembling n bntch process, all the varlous liquids and various reactants will be brought tcgether and various steps determlned by the proper time sequence into a slngle body of liquid. The batch process may be altered by using the suitable reactors such that a continuous or continuous-lllce form of the encapsulation process is achieved.
In the continuous form o~ the inventive proc~ss, dlsperslon ~nd agitation o~ the rcacting phascs may continuously be practiced at a proper rate to continuously form a suitable dispersion o~
droplets i~ the contlnuous phase and such that a continuously supplied portion of the dispersion of droplets in a continuous phase is added to a reactor ln which the pH can be adjusted and the appropriate heat applied to achieve the condensation, With-in the continuous system, the proper rate for reaction may be obtained by selecting the appropriate conditions. Both the batch and continuous aspects of the present in~ention are highly desir-abIe, and choice there between will rest solely with the desired manufacturing conditions.
.
- EXAMPLE I
Water (500 cc.), containing 1.0% of neutralized poly-(methyl vinyl ether/maleic anhydride) protective colloid (Gantrez* AN 139) and 0.26 lillear al~ l ethoxylate emulsifler ; (Tergitol* 15-S-20) is placed into an open reactor vessel. In a separate container 167 g. 0-ethyl S-phenyl ethylphosphonodithioate (an insecticide), 39 g~ polymethylene polyphenylisocyanate (PAPI) ~5 and l9.5 g. tolylene diisocyanate ~TDI 80% 2,4 and 20% 236) are - mixed togetherO This mir~ture is thcn added to the reactor vesscl and emulsified with a hlgh shear stirrer~ The resulting particlc * Trademar]c t~
. .. ~, ,. . . ' : ' ' sizc ran~c ls nbout l to n~Jout 20 ~l. Only mild agitation is requlred ~or the baLance of the reaction. The tempcrature of the reactants is raised to 50C. over ~ 17 rrllnut~ period and at the same'time, the pll of Lhe dispersion is malntained at 8.5 by addition ~f 25% sodium hydroxide solution~ The temperature of the reaction mixture is maintain~d at 50C~ and the p~l is maln-tained at 8.5 for 2-l/2 hours in order to complete the inter-~ faclal poLymeri~ation.
- At this point, O.25% sodium bentonite thickener and 005% sodium pentachlorophenate biocide for example, can be added to formulate the product without separatlon or further washing.
The p~l of the forrnulation is usually adjusted to 9.75 by addi-tion of 25% NaOH solutlon and the reaction mixture cooled to room temperature. These formulations dlsperse very well in water and discrete capsules are observed under a microscope.
These capsules have a wall content of about 26 per cent, EXAMPLE II
Water (500 cc~), 'containing 1.5% hydroxypropvlmeth~l cellulose protective colloid (Methocel* 65~1G) and 0.2~ linear alcohol ethoxylate emulsifierl(Tergitol 15-S-20) is placed into an open reactor vessel. In a separate container, 150 g. S-ethyl diisobutylthiocarbamate (~m herbici~e~, 35 g. polymethylene pol~-phenylisocyanate (PAPI), 17.5 g. tolylene diisocyanate (TDI
80% 2,4 and 20% 2,6) and 0.05 g. of tributyl tin aceta,te catal~st are mixed together. This mixture is then added to the rcactor vessel and emulsi~ied with a high speed stirr~ra The resultirlg particle,sLze rangc is about 1 to about 20 ~. Only mild agita-tion is required for thc balance of the reaction. The p~l o the reaction mixture is now adjusted to 8,0 wlth 10~/~ sodium * Trademark ~ . : . - . . : .
3~ 3~
hyclroxiclc solution. Thls 1-ll is maLntnil)ccl ~or 3 hours by con-tinued addition of 10% sodium hydroxide solution~ The prescnce of the cntalyst allows the interacial polymerlzatlon to be con-ducted at room temperature (25~C.~. Thls,formulation disperses very well in water and discrete capsules can be observed under a microscope. These capsules have a wall content o~ about 26 per cent.
E~MPLE III
Water (500 cc.), containing 0.5% polyacrylamide protecti~
colloid (Cyanamer* A370) and 0.2% linear ~lcohol ethoxyate (Tergitol 15-S-20) is placed lnto an open reactor vessel. In a separate container, 167 g. O-ethyl S-phenyl ethylphosphonodithioate (an insecticide), 14.5 g, polymethylene polyphenylisocyanate SPAPI) and 14.5 g. tolylene diisocyanate (TDI 8~/o 294 and 20% 2,6) are mixed together. The aqueous phase in the open reactor vessel is heated to 45C. after which the above organic mixture is added to - the reactor and emuls~ied with a high shear stirrer. At this point, the pH is equal to about 6.5. The resulting particle size range is 1 - 20 ~. Only mild agitation is required for the bal-ance of the reaction. The p~l of thc reaction mixture is adjusted to 8.5 with 25% sodium hydroxide solution. The temperature o .
the reaction mixture is adjusted to 50C. The temperature and pH
of the reaction mixture ~re maintained at 50C. and 8.5~-respect-ively, for 3 hours in order t~ complete the interfacial polymeri zation., ~?e pH is maintained at 8.5 by continued addition of 25%
sodium hydroxide solution. At this point 0.25% sodium bentonite ,~ thickener can be added to the capsule dispersion and thc pH
adjusted to 9~8 to formulate the encapsulated material without ~ur ther scparation or handling. The formulation is cool,ed to room temperaturleO This formulation can be d~sperscd readily in water and discrete capsules can be observed under a microscope. These capsules have a wall conten~ of about 15 per ccnt.
!
~ * ~rademark ~B: ~ ~ -19-. ~ . . . . . . ~ . . . . .. . . . . . .
EXAMPLE IV
Water (100 cc.), containing 3~ of polyacrylate protec-tive colloid (Goodrite* K-718) and 0.2~ linear alcohol ethoxylate emulsifier (Tergitol 15-S-20) is placed into an open reactor vessel.
In a separate container, 30 g. of ~'-ethylphenyl geranyl ether-6,7-epoxide (insect hormone mimic) and 2.4 g. o tolylene diisocyanate (TDI 80% 2,4- and 206 2,6-) are mixed together. This mixture is then added to the open reactor vessel and emulsified with a high shear stirrer. The resulting particle size range is 1-20~. O~ly mild agitation is required for the balance of the reaction. In order to increase the rate of interfacial polymerization, the temperaturé of the reactants is now raised to 50C. over a 15 minute period and at the same time, the pH o~ the dispersion is maintained at 8.5 by addition of 10% sodium hydroxide solution. The tempera-ture and pH of the reaction mixture is maintained at 50C. and 8.5, respectively, for 2 hours in order to complete the interfacial polymerization. The pH of the formulation is adjusted to 8.9.
me form~lation was cooled to room tempera-ture. This formulation dispersed very well in water and discrete capsules can be observed under a micro-scope. These capsules have a wall content of about 7.4 pex cent.
EXAMPLE V
Water (500 cc.), containing 1.0~ polyvinyl alcohol pro-tective colloid (Vinol* 540) and 0.2~ linear alcohol ethoxylate .
emulsifier (Tergitol 15-S 20) is placed into an open reactor vessel.
The temperature of this solution is raised to 40C. In a separate container, 30 g. of S~ethyl dipropylthioca'rbamate ~, * Trademark : :~
~ .
(an herbicide) and l0 g. o~ polymethylene polyphenylisocyanat~
(PAPI) are mixed ~ogetller, This rni~ure is then added to the reactor vessel and emulsified ~ith a high speed stirrer, The temperature of the system is then raised to 60C. and mild 2gi-tation is continued for l-l/2 hours while the temperature is maintained at 50C. The material is then ~iltered and washed three times and then allo.7ed to dry at room temperature, ~Iicro scopic observation sho~7s discrete spheroid particles, The C2p-sules have a wall content o~ 25 per cent.
EXA~IPLE VI
~0 Water ~500 cc.) containing 3.0% hydroxypropylmethyl cellulose protective colloid (Methocel 65 ~IG) and 0,2% linear alcohol ethoxylate emulsi~ier (Tergitol 15-S-20) is placed in~o an open reactor vessel. In a separate container, 150 g. S-ethyl dipropylthiocarbamate (an herbicide), 35 g. polymethyler.
polyphenylisocyanate (PAPI), 17.5 g. tolylene diisocyanate (TDI 80% 2,4- and 20% 2j6-) and 0,05 g, tributyl tin acetate - catalyst are mixed together, This mixture is then added to th2 reactor vessel and emulsified using a high speed stirrer. The resulting particle sir~e is about 5 microns. Only mild agitation is required for the balance of the reaction. The temperature o~
the system is slowly raised to 50C, over a l-l/2 hour period, At 50C., considerable foaming too~c place, The system is kept at 50C, for an additional l~l/2 hour a~ter which it is cooled to room ternperature, Microscopic examination o~ the system sho.wed discrete, well-formec] capsules. These capsules have a wall content o~ 26 per cent.
~2 :
_A~IPLE~ VII
l~ater (500 cc.), containing 3% polyacryla~e protectivz colloid (Goodrite 7l~~71S) and 0,3% linear alcohol ethoxylate emulsifier (Tergitol 15-S-7) is placed into an open reactor vessel. In a separate container, 30 g. of S-ethyl diisobutyl-thiocar~amate (an herbicide), 6.7 g. polymethylene polyphenyl-isocyanate (PAPI~ and 3.3 g. tolylene diisocyanate (TDI 80% 2,' and 20% 2,6) are mixed together. The organic phase then is added to the reactor and emulsified with a high shear stirrer.
The resulting particle size range is about 1 - 10/u. Only ~ild agitation is required for the balance of the reaction~ The pH
of the reaction mixture is adjusted to 4.5 with concentrated hydrochloric acid. The temperature of the reaction mixture is raised to 50C. and maintained at that temperature for 3 hours.
The system is cooled to room temperature. The pH remained a~
4~5 duxing the course of the reaction. This product can be dis-persed readily in water and discrete capsules can be observed under the microscope. These capsules have a ~all content of about 25 per cent.
EXAMPJ.E VIII
Water (900 cc~), containing 0.3% linear alcohol etho,~
late emulsifier (Tergitol 15~S-7) is placed into an open reactor vessel. In a separate container, 334 g. of S~ethyl diisobutyl-thiocarbaMate (an herbicide), 20.7 g, polymethylene polyphenyl-isocyanate and 20.7 g, tolylene diisocyanate (TDI 80% 2,4 and 20% 2,6) are mixed together. The organic phase is then added to the reactor and emulsified ~ith a high shear s~irrer, The resulting particle size range is 5 - 15,~. Only mild agita~ion ~2-` :
-~ .
is required for the balance of the reaction. One hundred grams o~ 5.0% aqueous solution of polyacrylamlde protective colloid (Cyanamer A-370) is then adclled to the reaction mixture. The temperature of the reaction mixture is ra~sed to 50~C. and at the same time~ the pH of the dispers~on is maintained at 8,5 by addition of 25% sodium hydroxide solution. The temperature of the reaction mixture is maintalned at 50~Co and the pH is main-talned at 8.5 for about 3 hours ln order to complete the inter-facial polymerization. The reaction mixture is cooled to room temperature. The reaction mixture can be dispersed readlly in water and discrete capsules can be observed under the microscope.
These capsules have a wall conten~ of about 11 per cent.
EXAMPLE IX
This example illustrates the u~e of a highly baslc pH
value (l.e. pH o 13.6).
Water t500 cc.), containing 2~0% hydroxypropylme~hyl cellulose protective colloid (Methooel 65 HG), 0.2% linear alcohol ethoxylate e~ulsifier (Tergitol 15-S-20) and 1,5% sodium hydroxide (pH - 1306) is placed into an open reactor vessel. In a separate con~ainer, 150 gO S-ethyl diisobutyl thiocarb~mate (an herbicide), 3590 g. polymethylene polyphenylisocyanate ~PAPI), 17.5 g~ tolylene diisocyanate (TDI 80% 2,4 and 20% 2,6) and 0.05 g. tribu~yl tin ace~a~e are mixed toge~her. The aqueous phase is cooled down to 9C. The organic phase is then added to ~he reactor vessel and emulsified with a high shear stlrrer. All particles were reduced below 40 ~ in size. Only mild agitation is required for the bal-ance of the reaction. The temperature was all~wed to rlse slowly to room temperature (~2~C.). Stirring contînued for approximately 16 hours. Discrete capsules were observed under a microscope.
, The capsules have a wall content of about ~5 per cent.
; -~3-E I.E X
This example lllustrates the use of a highly acldic pH value (i~e. pH ~ 0).
Water (500 cc.), containlng 3O0% poly~lnyl alcohol protective colloid (V~nol 540), 0.3% linear alcohol eth~x~late emulsifier (Tergitol 15-S-7) and 3.7% hydrochloric acid ~pH = 0 is placed ln~o an open reactor ve~selO In a separate container 150 g. S~n-propyl di-n-propyl thiocarbamate (an herbicide~, 17.7 g.
polymethylene polyphenylisocyanate (PAPI~ and 8.8 g. tolylene diisocyanate (TDI 80V/o 2,4 and 20% 2~6) are mixed together, This mixt~re is then added to the reactor vessel and emulsified with a high shear stirrerO ~11 particles were reduced below 15 ~ in size.
Only mi~ d agitation is required for the balance of the reaction.
The temperature o the reactants is raised to 50~C. over a 20 minute period. The temperature of the reaction mlxture is main-: 15 ta~ned at 50~C. for 2~1/2 hours to complete the interfac~al poly-merization. Discrete capsules are observed under a microscope~
; The capsules have a wall content of about 15 per cent~
EXAMPLE XI
Thls is an example of encapsulation of water-lmmiscible material which can dissolve an appreciable quanti~y o~ water, in ~his inst~nce 5.~%.
: Wa~ 500 cc.), con aining 1.0% polyacrylamide protec : t~ve colloid (Cyanamer A370) and 0.3% linear aloohol ethoxylate : (Tergitol 15~S-20) is placed into an open reactor vessel. In a separate container 33.4 g, tris- ~-chloroethylphosphate (a flame retardant)" 4.0 g. polymethylene polyphenyl lsocyanate (PAPI) : ~ and 2.0 g. tolylene diisocyanate (TDI ~0% ~,4 and 20% 296) are . .
~ ~ -24-, -~ , . . . .
mixed together. The mixture is then adde~ to the reactor vessel and emulslied with ~ hlgh shear stirrer. l~le resultlng partlcl~
size range is 2 - 15 ~. Vnly mild agitation ls required for the balance of the reaction. At this point, 1,0 g, triethylene d-lamine catalyst dissolved in 10 ml~ water is added to the aqueous phase and the pH Ls adJusted to 9.5~ The pl-l ls malntained at 9.5 by addition of 25% sodi~n hydroxide solutlon and stirring con tinued at room temperature (about 25C.) for 17 hours. Dlscrete, well-formed microcapsules are observed under a microscope, Ihe capsules have a wall content of 15 per cent.
EXAMPLE XII
This ex~mple illustrates the encapsulation o a normally solid ma~erial by enclosure formation around a water-lmmisclble solvent ln which the solid material is dissolved.
Water (500 cc.) 9 containing 2.070 of hydrolyzed poly (methyl vinyl ether/maleic anhydride~ protective colloid (Gantrez ANll9) and O.3% linear alcohol ethoxylate emulsifier (Tergitol 15~S~7) is placed into an open reactor vesselO The pH of thls ~....~
solutio~ is adj~sted to 405. In a separate container, 157 g. of a 30% solution o~ N-(mercaptomethyl) phthalimide S-(O,O-dimethyl phosphorodithioate~ (an lnsecticide with melting po-Lnt of 72C.) in heavy aromatic naphtha solvent 'IPanasol* AN-3) 8.3 g. poly-methylene polyphenyl isocyanate (PAPI) and 4~2 g. tolylene d~iso-cyanate (TDI 80% 2,4 and 20~!o 2,6) are mixed together. Thi~ mlx-ture ls then added to the reactor vessel and emulsified with a . ( .
high shear stlrrer. All particles are reduced below 20 ~ in siz~.
Only mild agitation is required for the balance of the reaction.
This temperature of the reactants is raised to 50C, ov~r a * Trademark ~ -25 .. lB~.
: . .
20 mlnute period. The temperature of the reac~ion mixture is ~
tained at 50C, for 2~1/2 hours ~o complete the lnterfacial pol~J-merization~ The formulation disperses ~ery well in water and discrete capsules are observed under a microscope., The capsules have a wall con~ent of about 7.5 per cent. No crystals of insec-ticide ~r,e~ observed under a microscope after the preparation is stored at room temperature or 2 'days, EXAMPLE X'III
This example illustrates the encapsulation of two w~ter-immiscible substances in the organic phase.
Water (500 cc.), containing 0.5% polyacryLa~ide protec-~ive colloid (Cyanamer A370) ~nd 0O3% linear alcohol ethoxyla~e (Tergitol 15-S-7) is placed into an open reactor vessel and t~e pH adjusted to 8.5. ~n a separate container, 138.5 g. S-ethyl dipropyl thiocarbamate ~an herbi~ide), 11.5 g. N3~-diallyldiohloro~
~cetamide (an herbicide antidote), 35.0 g. polymethylene pol~-phenyl isoeyanate (PAPI) and 17.5 g. tolylene diisocyanate (TDI
807o ~2~4 and 20% 2,6~ are mlxed together. This mixture is the~
added to the op~n reactor vessel and emulsiied with a high s ear stirrer~ The resulting particle size range is 5 - 30 ~O Onl~
mild agitation ~s required for the balance of the reaction. Th2 reaction mixture is ~hen heated to 50C. over a 2~ minute period.
The reac~ion mixture is maintained at 50G. ~or 2-1/2 hours~ The pH is maintained at 8, 5 by the addition o~ 25~ sodium hydroxide . olution. This formulation d~sperses very well in water and ~is^
crete microcapstlles can be obs~rved~under a microscope~t These c~-sules ~ave a wall content o~ a~ou~ 25 per cent.
, ~ 6-A~ previously mentioned ancl illustrated by the examples herein~ the process or encapsulation of the lnstant invention pro~ides capsules capable o~ con~rolling release of encapsulated organic materialO Representat~e and especially of importance are the process and capsules comprising as a constituent in the organic phase herbic~des of the class thiocarbamate such as S-ethyl diisobutylthiocarbamate; S-e~hyl dipropylthlocarb$ma~e;
S-ethyl he~ahydro-l-H-azepine-l-carbothioate; S-propyl hexahydro-l-H-azepine-l-carbothioate; S-propyl dipropylthiocarbamate;
S-ethyl ethylcyclohexyl thiocarbamate; S-propyl butylethyl thio-carbamate; organo phosphorus insecticides of the class organo phosphono and phosphorothioates and dithioates such as O-ethyl S-phenyl ethylphosphonodithioate, S-[(p-chlorophenylthio)methyl~
O,O-dim~thyl phosphorodithioate, S~[(p-chlorophenylthio)methyl]
O,O-diethylphosphorodithioate, O,O-dimethyl O-p-nitrophenyl .
phosphorothioate, O,O-diethyl O-p-nitrophenyl phosphorothioate;
and insect hormones and mimics such as:
.
. ~ .
-27~
Cecro~:La - Juven~l~ llormone - I
1-(41-ethyl)phenoxy-3,7-dimethyl-6,7~epoxy-tranC;~2-octene __ ~~~
' 1~(3',4'-methylenedioxy)phenoxy~3~7-dimethyl -6 7-e~oxv-trans-2-nonene (~~
,~
0~\
Isopropyl ll-methoxy-3~7,11-trimethyl-dodeca~
oJ~
. .
: Capsules of compounds useIul for plant disease control provide a route to long term control of disease using compounds generally regarded to have only short term effectiveness. Simi-larly, herbicides, nematocides, insecticides, rodenticides and .. . .
.
-~ -2~-i . - . . ~ -soil nutrients can be encapsulated with useful results Cheml~
cals used for seed treatment are also readily encapsulated by the process of the invention. Other biological products can be encapsulated including: Anthelmintics, lamphrey and slime con-trol agents, algicides~ swimming pool chemicals, miticides~ acara-cides, animal attractants~ antiseptics, deodorants, disinfec-tants, mildewicides, and the like.
The material to be encapsulated utilizlng the process of the instant invention can be of any type which is water-immlscible. The material need not consist of only one type, but may be a combination of two or more various types of water~
immlscible materials. For example, employing an appropriate water-immiscible material, such a combination is an active her-bicide and an active insecticide. Also contemplated is a water-immiscible material to be encapsulated which comprises an active ingredient, such as an herbicide and an inactive ingredient such as a solvent or adjuvant. Encapsulation of a solid material can be accomplished by this method by forming a solution of the solid material in an appropriate solvent; thereby~ normally solid water-immiscible material can be encapsulated~ For example, the insec-ticide N-~mercaptomethyl) phthalimide S-(O,Owdimethyl phosphoro-dithioate~, m.p. 72C~, can be encapsulated by first dissolving the solid in an appropriate solvent, such as heavy aromatic naphtha solvent.
~ , .
:
.
,
The amount of organic polyisocyanate used in the pro- -cess will determine the wall content of the capsules formed therein. Generally, based on the organic phase, there will be greater than about 2 per cent by weight organic polyisocyanate present. However, this is by no means limiting and a greater amount can be used that is approaching 100 per cent. Clearly, 100 per cent would not be entirely desirable since this would result in a product with no encapsulated material. The preferred ` range is from about 2.0 per cent to about 75.0 per cent by weight of organic polyisocyanate, thereby ~orming an encapsulated product having a corresponding wall content, i.e., about 2.0 per cent to about 75.0 per cent. More particularly, the preferred range is from about 5.0 per cent to about 50.0 per cent wall content.
~ .
: - 10 -; ~ , ,r~" ~
In accordance ~itll preferred practice o~ th~ present invention, the follot~ing general steps comDrise the process which utilizes the t~Jo substantially immiscible phases describec above. In essence, the process comprises estabiishing a pnysi-cal dispersion of the organic phase in the aqueous or continuou, phase, such dispersion thereby establishing droplets of desired size in the aqueous phase. Thereafter, by adjusting the pH or the resulting mixture, and temperature ~ithin the appropriate temperature range, the desired condensation r~action is theréby effected at the interfaces between the droplets and the continu-ous phase, FIG. 1. Certain variations in the sequence of steps between adjustment of the pH and addition of required heat ~7ill be apparent in the ollowing discussion and examples.
The temperature of the two phase mixture, that is, the dispersion of the organic phase in the aqueous phase, is raised to about 40C. to about 60C. The temperature range for the condensation reaction within the present invention is between .
about 20C. to about 90~C. Whereas the heat ~o initiate the reaction can be applied to the dispersion OL the organic phase Z0 in the aqueous phase slmultanèously or after the adjustment of the pH to the desired value, the aqueous phase can be heated to the required temperature prior to the steps of addition of the organic phase and dispersion, FIG. 3~ In this alternative procedure, ~he adjustment of the pH is performed after the dis-persion is accomplished and the pH is maintained within the :::
limits to be discussed below.
Within one embodiment of the present invention, FIG. ~, it has been found that a catalyst capable of increasin~ the ra,e ::
--1 1 `- .
, of isocyanate hydrolysis, for example, the basic amine type, may be added to the organic phase or aqueous phase prior to the initlation oE the desired condensation reactiol~. However, this step is not necessary to the successful practice of the present invention. When it is selected to substitute a catalyst for the increase in temperature in the process, the product obtained thereby is comparable to a non catalyzed system. Increased temperature and catalyst can be used simultaneously to effect the desired polycondensation reaction. The catalyst in such a procedure is added preferably to the organic phase and is added to the system at the time o mixing of the aqueous and organic phases. Various catalysts have been found acceptable, their selection will depend upon factors easily determinable by one skilled in the art. It has been found that certain basic organic amines~ preferably the tertiary amines, and alkyl tin acetates such as tri-butyl tin acetate and di-n-butyl tin di-acetate are acceptable catalysts. When an alkyl tin acetate is used, about 0.001 per cent to about 1.0 per cent by weight based on the organic phase is employed. Included among the basic or-ganic tertiary amines are triethylene diamine, N3N,N',N'-tetra-methyl-1,3-butane-diamine, triethylamine, tri-n-butyl amine and the like. The amount of catalyst will vary with the particular system and conditions When a basic organic amine is used, about 0~01 per cent to about l0.0 per cent by weight based on the organic phase is employed.
Oftentimes it will be found that water will be slightly soluble in the water-immiscible material to be encapsulatedO The amount of water which will be dissolved in the material to be encapsulated wiIl depend upon the nature of the material.
.
.
,. ' ' ' '' , :. , - :
.
.
~ 2 Usually the amount of wa~er dissolved will be relatively minor.
Howevera when using a water-immiscible material that can dissolve an appreciable quantity of water, slight deviation in the normal processes described herein is preferred. In such a system it has been found that particles with poorly de~ined wall struc~
ture result. Well-defined microcapsules within the description of this invention can be prepared by adding an appropriate catalyst to the a~ueous phase after the emulsion is formed~
Thereby, the bulk of the polymeriæatlon takes place at the inter-face where the catalyst is present. No heating o~ the process mixture is advised, otherwise polymer will form not only on the surface, but an increased proportîon will form within the water~
immiscible material that can dissolve an appreciable amount of water. This procedure is preferably performed at about room tem-perature (15 to 30C.3. This method of addition of the catalyst to the aqueous phase after dispersion is not limited to encap-sulation of only water immiscible material that can dissolve appreciable quantity of water, but finds general applicability with any water immiscible material herein discussed and described.
It is satlsfactory to prepare the aqueous phase as described above~ While stirring the a~ueous phase, the organic phase is added, preferably in a pre-mixed state. Upon addition of the organic phase to the aqueous phase, a suitable dispersing means to disperse one liquid into the other is employed. Any high shear device can be used conveniently to obtain the desired droplet siæe within the range o from about 0.5 microns to about 4,00a microns. The actual range will depend upon the desired end use. As an example, the preferred range for most pesticidal applications is from about 1 micron to about 100 microns. The , .
~: ~ ~ " , - ~ .
.
Z
lnstant process is applicable to preparil~ widely varied but unlform si~ed capsules. Once the proper droplet size is obtained, the dispersion means employed to establish the desired droplet size is discontinued. Only mild agitation is required for the balance of the process~
The process of the instant invention is capable of satis~actory performance and production of encapsulated material without adjustment to a specific pH value. That is, no adjustment of the pH of the system need be made during the encapsulation 10 process. The encapsula~ion process will proceed at a pH value of between about 0 to about 14. The desirability of any adjust~
ment of pH to a par~icular value wil~ depend upon ~he nature of the systems components, such as surfactant~ colloid, catalyst, temperature, material to be encapsulated and the like. For lS e~ample9 if the p~ is allowed to drop below about 7.0, carbon dioxide will be liberated during the course of the reaction.
If it is desira~le to eliminate this evolution o carbon dioxide, then adjustment can be made to a pH value at least about 7Ø
Within the embodiment9 FIG. 1 and FIG. 2, the pH is adjusted 20 after dispersion and maintained at ~hat value for the remainder of the condensation reac~ion. The adjustment of the pH can take place in the aqueous phase prior to the addition and dispersion therein of the organic phaseO The adjustment and maintenance of a particular pH throughout the reaction can be accomplished with 25 varlous water soluble bases or acids nonreactive with the poly-~; isocyanate intermediate. Preferably3 concentrated sodium hydroxide (25% solution) 3 potassium hydroxide, hydrochloric acid and the like can be used.
.
:; :
.
The evolution of carbon dioxide may cause considerable undesirable foam formation and/or volume expansion which inter-fexes with the processing o the reaction mi~ture. An alternative to the adjustment of the pH in order to eliminate the excessive foam produced by the carbon dioxide evolution is the addition of a defoamer. By the use of a defoamer, it is possible to satisfac-torily produce the encapsulated material at an acid pH withuut the addition of caustic to l:he acidic system. The defoamer can be added at any time to the processing mixture wherein said poly-mer capsular enclosures are formed to encapsulate a water-immiscible material.
Whereas the desired condensation reaction at the inter-face between the droplets and the continuous phase occurs very rapidly, the majority within the first one-half hour of reaction time, in order to insure near completion of the condensation reaction throughout the system, the reaction conditions are con-tinued for from about 2 to 3 hours9 Under properly adjusted conditions or with a proper catalyst, the reaction time can be shortenedO At the end of this time, the formation of a capsule wall has been completed, thereby encapsulating the organic mat-- erial within the skin of a polycondensate, and there exis~s a ;~ usable encapsulated product. A specific feature of the present invention, which is highly desirable, resides in the fact that for certain intended applications, no further separa~ion or hand-ling of the encapsulated material is required~ i.e., the product is directly usable. The encapsulated material can be used for various direet applications at this point or indirectly by `~ incorporating the material into other products.
:;
~15-- ' The thickness or chemlcal composition of the capsule-wall can be selected or controlled in various ways~ For example, these properties can be afected by control of the reac~ion con-dition, by chemical selection~ especially in the creation of S eross linkage which is determined by the functionality of the polyisocy~nate in accordance with the inventlon. The thickness of the capsule skin can also be altered by varylng the amounts of reactants withi~ the organic phase. One convenient mode of con-trolling the size o the capsule ls adjustment of the speed of agitation, that i~) in bringing about the original disperslon of the organic phase, smaller capsules can be obtained with higher speeds of agitation resulting in a greater shearing force.
Tests have indicated ~hat capsules produced in accor-dance with the present invention can be utilized in the same manner as produets of other encapsulation procedures. Thus, for example, eneapsulated herbicides or insecticides ean be embodied in dispersions for applieation purposes~ for controlled release of the eneapsulated material at the desired loeality. Special utillty is noted for the encapsulation of various volatile or unsta~le insecticides and herbicides~ By encapsulation, prema-ture volat~lizatien or other deterioration of the material is avoided; such encapsulation can also serve the purpos~ of retard-ing or delaying action to the time when desired. Controlled release of these materials is important for environmental pro~
teetion and the proper effect on th~ organism to be controlled, as well as decreased toxicity on beneicial organisms.
The present invention may be practiced in a batch or bateh-like form or in a continuous or con~inuous-like form~
`, ~ -. . . . .. ~ .... . , . . . . . -When the inventioll is prnctlced in a rnanner rcsembling n bntch process, all the varlous liquids and various reactants will be brought tcgether and various steps determlned by the proper time sequence into a slngle body of liquid. The batch process may be altered by using the suitable reactors such that a continuous or continuous-lllce form of the encapsulation process is achieved.
In the continuous form o~ the inventive proc~ss, dlsperslon ~nd agitation o~ the rcacting phascs may continuously be practiced at a proper rate to continuously form a suitable dispersion o~
droplets i~ the contlnuous phase and such that a continuously supplied portion of the dispersion of droplets in a continuous phase is added to a reactor ln which the pH can be adjusted and the appropriate heat applied to achieve the condensation, With-in the continuous system, the proper rate for reaction may be obtained by selecting the appropriate conditions. Both the batch and continuous aspects of the present in~ention are highly desir-abIe, and choice there between will rest solely with the desired manufacturing conditions.
.
- EXAMPLE I
Water (500 cc.), containing 1.0% of neutralized poly-(methyl vinyl ether/maleic anhydride) protective colloid (Gantrez* AN 139) and 0.26 lillear al~ l ethoxylate emulsifler ; (Tergitol* 15-S-20) is placed into an open reactor vessel. In a separate container 167 g. 0-ethyl S-phenyl ethylphosphonodithioate (an insecticide), 39 g~ polymethylene polyphenylisocyanate (PAPI) ~5 and l9.5 g. tolylene diisocyanate ~TDI 80% 2,4 and 20% 236) are - mixed togetherO This mir~ture is thcn added to the reactor vesscl and emulsified with a hlgh shear stirrer~ The resulting particlc * Trademar]c t~
. .. ~, ,. . . ' : ' ' sizc ran~c ls nbout l to n~Jout 20 ~l. Only mild agitation is requlred ~or the baLance of the reaction. The tempcrature of the reactants is raised to 50C. over ~ 17 rrllnut~ period and at the same'time, the pll of Lhe dispersion is malntained at 8.5 by addition ~f 25% sodium hydroxide solution~ The temperature of the reaction mixture is maintain~d at 50C~ and the p~l is maln-tained at 8.5 for 2-l/2 hours in order to complete the inter-~ faclal poLymeri~ation.
- At this point, O.25% sodium bentonite thickener and 005% sodium pentachlorophenate biocide for example, can be added to formulate the product without separatlon or further washing.
The p~l of the forrnulation is usually adjusted to 9.75 by addi-tion of 25% NaOH solutlon and the reaction mixture cooled to room temperature. These formulations dlsperse very well in water and discrete capsules are observed under a microscope.
These capsules have a wall content of about 26 per cent, EXAMPLE II
Water (500 cc~), 'containing 1.5% hydroxypropvlmeth~l cellulose protective colloid (Methocel* 65~1G) and 0.2~ linear alcohol ethoxylate emulsifierl(Tergitol 15-S-20) is placed into an open reactor vessel. In a separate container, 150 g. S-ethyl diisobutylthiocarbamate (~m herbici~e~, 35 g. polymethylene pol~-phenylisocyanate (PAPI), 17.5 g. tolylene diisocyanate (TDI
80% 2,4 and 20% 2,6) and 0.05 g. of tributyl tin aceta,te catal~st are mixed together. This mixture is then added to the rcactor vessel and emulsi~ied with a high speed stirr~ra The resultirlg particle,sLze rangc is about 1 to about 20 ~. Only mild agita-tion is required for thc balance of the reaction. The p~l o the reaction mixture is now adjusted to 8,0 wlth 10~/~ sodium * Trademark ~ . : . - . . : .
3~ 3~
hyclroxiclc solution. Thls 1-ll is maLntnil)ccl ~or 3 hours by con-tinued addition of 10% sodium hydroxide solution~ The prescnce of the cntalyst allows the interacial polymerlzatlon to be con-ducted at room temperature (25~C.~. Thls,formulation disperses very well in water and discrete capsules can be observed under a microscope. These capsules have a wall content o~ about 26 per cent.
E~MPLE III
Water (500 cc.), containing 0.5% polyacrylamide protecti~
colloid (Cyanamer* A370) and 0.2% linear ~lcohol ethoxyate (Tergitol 15-S-20) is placed lnto an open reactor vessel. In a separate container, 167 g. O-ethyl S-phenyl ethylphosphonodithioate (an insecticide), 14.5 g, polymethylene polyphenylisocyanate SPAPI) and 14.5 g. tolylene diisocyanate (TDI 8~/o 294 and 20% 2,6) are mixed together. The aqueous phase in the open reactor vessel is heated to 45C. after which the above organic mixture is added to - the reactor and emuls~ied with a high shear stirrer. At this point, the pH is equal to about 6.5. The resulting particle size range is 1 - 20 ~. Only mild agitation is required for the bal-ance of the reaction. The p~l of thc reaction mixture is adjusted to 8.5 with 25% sodium hydroxide solution. The temperature o .
the reaction mixture is adjusted to 50C. The temperature and pH
of the reaction mixture ~re maintained at 50C. and 8.5~-respect-ively, for 3 hours in order t~ complete the interfacial polymeri zation., ~?e pH is maintained at 8.5 by continued addition of 25%
sodium hydroxide solution. At this point 0.25% sodium bentonite ,~ thickener can be added to the capsule dispersion and thc pH
adjusted to 9~8 to formulate the encapsulated material without ~ur ther scparation or handling. The formulation is cool,ed to room temperaturleO This formulation can be d~sperscd readily in water and discrete capsules can be observed under a microscope. These capsules have a wall conten~ of about 15 per ccnt.
!
~ * ~rademark ~B: ~ ~ -19-. ~ . . . . . . ~ . . . . .. . . . . . .
EXAMPLE IV
Water (100 cc.), containing 3~ of polyacrylate protec-tive colloid (Goodrite* K-718) and 0.2~ linear alcohol ethoxylate emulsifier (Tergitol 15-S-20) is placed into an open reactor vessel.
In a separate container, 30 g. of ~'-ethylphenyl geranyl ether-6,7-epoxide (insect hormone mimic) and 2.4 g. o tolylene diisocyanate (TDI 80% 2,4- and 206 2,6-) are mixed together. This mixture is then added to the open reactor vessel and emulsified with a high shear stirrer. The resulting particle size range is 1-20~. O~ly mild agitation is required for the balance of the reaction. In order to increase the rate of interfacial polymerization, the temperaturé of the reactants is now raised to 50C. over a 15 minute period and at the same time, the pH o~ the dispersion is maintained at 8.5 by addition of 10% sodium hydroxide solution. The tempera-ture and pH of the reaction mixture is maintained at 50C. and 8.5, respectively, for 2 hours in order to complete the interfacial polymerization. The pH of the formulation is adjusted to 8.9.
me form~lation was cooled to room tempera-ture. This formulation dispersed very well in water and discrete capsules can be observed under a micro-scope. These capsules have a wall content of about 7.4 pex cent.
EXAMPLE V
Water (500 cc.), containing 1.0~ polyvinyl alcohol pro-tective colloid (Vinol* 540) and 0.2~ linear alcohol ethoxylate .
emulsifier (Tergitol 15-S 20) is placed into an open reactor vessel.
The temperature of this solution is raised to 40C. In a separate container, 30 g. of S~ethyl dipropylthioca'rbamate ~, * Trademark : :~
~ .
(an herbicide) and l0 g. o~ polymethylene polyphenylisocyanat~
(PAPI) are mixed ~ogetller, This rni~ure is then added to the reactor vessel and emulsified ~ith a high speed stirrer, The temperature of the system is then raised to 60C. and mild 2gi-tation is continued for l-l/2 hours while the temperature is maintained at 50C. The material is then ~iltered and washed three times and then allo.7ed to dry at room temperature, ~Iicro scopic observation sho~7s discrete spheroid particles, The C2p-sules have a wall content o~ 25 per cent.
EXA~IPLE VI
~0 Water ~500 cc.) containing 3.0% hydroxypropylmethyl cellulose protective colloid (Methocel 65 ~IG) and 0,2% linear alcohol ethoxylate emulsi~ier (Tergitol 15-S-20) is placed in~o an open reactor vessel. In a separate container, 150 g. S-ethyl dipropylthiocarbamate (an herbicide), 35 g. polymethyler.
polyphenylisocyanate (PAPI), 17.5 g. tolylene diisocyanate (TDI 80% 2,4- and 20% 2j6-) and 0,05 g, tributyl tin acetate - catalyst are mixed together, This mixture is then added to th2 reactor vessel and emulsified using a high speed stirrer. The resulting particle sir~e is about 5 microns. Only mild agitation is required for the balance of the reaction. The temperature o~
the system is slowly raised to 50C, over a l-l/2 hour period, At 50C., considerable foaming too~c place, The system is kept at 50C, for an additional l~l/2 hour a~ter which it is cooled to room ternperature, Microscopic examination o~ the system sho.wed discrete, well-formec] capsules. These capsules have a wall content o~ 26 per cent.
~2 :
_A~IPLE~ VII
l~ater (500 cc.), containing 3% polyacryla~e protectivz colloid (Goodrite 7l~~71S) and 0,3% linear alcohol ethoxylate emulsifier (Tergitol 15-S-7) is placed into an open reactor vessel. In a separate container, 30 g. of S-ethyl diisobutyl-thiocar~amate (an herbicide), 6.7 g. polymethylene polyphenyl-isocyanate (PAPI~ and 3.3 g. tolylene diisocyanate (TDI 80% 2,' and 20% 2,6) are mixed together. The organic phase then is added to the reactor and emulsified with a high shear stirrer.
The resulting particle size range is about 1 - 10/u. Only ~ild agitation is required for the balance of the reaction~ The pH
of the reaction mixture is adjusted to 4.5 with concentrated hydrochloric acid. The temperature of the reaction mixture is raised to 50C. and maintained at that temperature for 3 hours.
The system is cooled to room temperature. The pH remained a~
4~5 duxing the course of the reaction. This product can be dis-persed readily in water and discrete capsules can be observed under the microscope. These capsules have a ~all content of about 25 per cent.
EXAMPJ.E VIII
Water (900 cc~), containing 0.3% linear alcohol etho,~
late emulsifier (Tergitol 15~S-7) is placed into an open reactor vessel. In a separate container, 334 g. of S~ethyl diisobutyl-thiocarbaMate (an herbicide), 20.7 g, polymethylene polyphenyl-isocyanate and 20.7 g, tolylene diisocyanate (TDI 80% 2,4 and 20% 2,6) are mixed together. The organic phase is then added to the reactor and emulsified ~ith a high shear s~irrer, The resulting particle size range is 5 - 15,~. Only mild agita~ion ~2-` :
-~ .
is required for the balance of the reaction. One hundred grams o~ 5.0% aqueous solution of polyacrylamlde protective colloid (Cyanamer A-370) is then adclled to the reaction mixture. The temperature of the reaction mixture is ra~sed to 50~C. and at the same time~ the pH of the dispers~on is maintained at 8,5 by addition of 25% sodium hydroxide solution. The temperature of the reaction mixture is maintalned at 50~Co and the pH is main-talned at 8.5 for about 3 hours ln order to complete the inter-facial polymerization. The reaction mixture is cooled to room temperature. The reaction mixture can be dispersed readlly in water and discrete capsules can be observed under the microscope.
These capsules have a wall conten~ of about 11 per cent.
EXAMPLE IX
This example illustrates the u~e of a highly baslc pH
value (l.e. pH o 13.6).
Water t500 cc.), containing 2~0% hydroxypropylme~hyl cellulose protective colloid (Methooel 65 HG), 0.2% linear alcohol ethoxylate e~ulsifier (Tergitol 15-S-20) and 1,5% sodium hydroxide (pH - 1306) is placed into an open reactor vessel. In a separate con~ainer, 150 gO S-ethyl diisobutyl thiocarb~mate (an herbicide), 3590 g. polymethylene polyphenylisocyanate ~PAPI), 17.5 g~ tolylene diisocyanate (TDI 80% 2,4 and 20% 2,6) and 0.05 g. tribu~yl tin ace~a~e are mixed toge~her. The aqueous phase is cooled down to 9C. The organic phase is then added to ~he reactor vessel and emulsified with a high shear stlrrer. All particles were reduced below 40 ~ in size. Only mild agitation is required for the bal-ance of the reaction. The temperature was all~wed to rlse slowly to room temperature (~2~C.). Stirring contînued for approximately 16 hours. Discrete capsules were observed under a microscope.
, The capsules have a wall content of about ~5 per cent.
; -~3-E I.E X
This example lllustrates the use of a highly acldic pH value (i~e. pH ~ 0).
Water (500 cc.), containlng 3O0% poly~lnyl alcohol protective colloid (V~nol 540), 0.3% linear alcohol eth~x~late emulsifier (Tergitol 15-S-7) and 3.7% hydrochloric acid ~pH = 0 is placed ln~o an open reactor ve~selO In a separate container 150 g. S~n-propyl di-n-propyl thiocarbamate (an herbicide~, 17.7 g.
polymethylene polyphenylisocyanate (PAPI~ and 8.8 g. tolylene diisocyanate (TDI 80V/o 2,4 and 20% 2~6) are mixed together, This mixt~re is then added to the reactor vessel and emulsified with a high shear stirrerO ~11 particles were reduced below 15 ~ in size.
Only mi~ d agitation is required for the balance of the reaction.
The temperature o the reactants is raised to 50~C. over a 20 minute period. The temperature of the reaction mlxture is main-: 15 ta~ned at 50~C. for 2~1/2 hours to complete the interfac~al poly-merization. Discrete capsules are observed under a microscope~
; The capsules have a wall content of about 15 per cent~
EXAMPLE XI
Thls is an example of encapsulation of water-lmmiscible material which can dissolve an appreciable quanti~y o~ water, in ~his inst~nce 5.~%.
: Wa~ 500 cc.), con aining 1.0% polyacrylamide protec : t~ve colloid (Cyanamer A370) and 0.3% linear aloohol ethoxylate : (Tergitol 15~S-20) is placed into an open reactor vessel. In a separate container 33.4 g, tris- ~-chloroethylphosphate (a flame retardant)" 4.0 g. polymethylene polyphenyl lsocyanate (PAPI) : ~ and 2.0 g. tolylene diisocyanate (TDI ~0% ~,4 and 20% 296) are . .
~ ~ -24-, -~ , . . . .
mixed together. The mixture is then adde~ to the reactor vessel and emulslied with ~ hlgh shear stirrer. l~le resultlng partlcl~
size range is 2 - 15 ~. Vnly mild agitation ls required for the balance of the reaction. At this point, 1,0 g, triethylene d-lamine catalyst dissolved in 10 ml~ water is added to the aqueous phase and the pH Ls adJusted to 9.5~ The pl-l ls malntained at 9.5 by addition of 25% sodi~n hydroxide solutlon and stirring con tinued at room temperature (about 25C.) for 17 hours. Dlscrete, well-formed microcapsules are observed under a microscope, Ihe capsules have a wall content of 15 per cent.
EXAMPLE XII
This ex~mple illustrates the encapsulation o a normally solid ma~erial by enclosure formation around a water-lmmisclble solvent ln which the solid material is dissolved.
Water (500 cc.) 9 containing 2.070 of hydrolyzed poly (methyl vinyl ether/maleic anhydride~ protective colloid (Gantrez ANll9) and O.3% linear alcohol ethoxylate emulsifier (Tergitol 15~S~7) is placed into an open reactor vesselO The pH of thls ~....~
solutio~ is adj~sted to 405. In a separate container, 157 g. of a 30% solution o~ N-(mercaptomethyl) phthalimide S-(O,O-dimethyl phosphorodithioate~ (an lnsecticide with melting po-Lnt of 72C.) in heavy aromatic naphtha solvent 'IPanasol* AN-3) 8.3 g. poly-methylene polyphenyl isocyanate (PAPI) and 4~2 g. tolylene d~iso-cyanate (TDI 80% 2,4 and 20~!o 2,6) are mixed together. Thi~ mlx-ture ls then added to the reactor vessel and emulsified with a . ( .
high shear stlrrer. All particles are reduced below 20 ~ in siz~.
Only mild agitation is required for the balance of the reaction.
This temperature of the reactants is raised to 50C, ov~r a * Trademark ~ -25 .. lB~.
: . .
20 mlnute period. The temperature of the reac~ion mixture is ~
tained at 50C, for 2~1/2 hours ~o complete the lnterfacial pol~J-merization~ The formulation disperses ~ery well in water and discrete capsules are observed under a microscope., The capsules have a wall con~ent of about 7.5 per cent. No crystals of insec-ticide ~r,e~ observed under a microscope after the preparation is stored at room temperature or 2 'days, EXAMPLE X'III
This example illustrates the encapsulation of two w~ter-immiscible substances in the organic phase.
Water (500 cc.), containing 0.5% polyacryLa~ide protec-~ive colloid (Cyanamer A370) ~nd 0O3% linear alcohol ethoxyla~e (Tergitol 15-S-7) is placed into an open reactor vessel and t~e pH adjusted to 8.5. ~n a separate container, 138.5 g. S-ethyl dipropyl thiocarbamate ~an herbi~ide), 11.5 g. N3~-diallyldiohloro~
~cetamide (an herbicide antidote), 35.0 g. polymethylene pol~-phenyl isoeyanate (PAPI) and 17.5 g. tolylene diisocyanate (TDI
807o ~2~4 and 20% 2,6~ are mlxed together. This mixture is the~
added to the op~n reactor vessel and emulsiied with a high s ear stirrer~ The resulting particle size range is 5 - 30 ~O Onl~
mild agitation ~s required for the balance of the reaction. Th2 reaction mixture is ~hen heated to 50C. over a 2~ minute period.
The reac~ion mixture is maintained at 50G. ~or 2-1/2 hours~ The pH is maintained at 8, 5 by the addition o~ 25~ sodium hydroxide . olution. This formulation d~sperses very well in water and ~is^
crete microcapstlles can be obs~rved~under a microscope~t These c~-sules ~ave a wall content o~ a~ou~ 25 per cent.
, ~ 6-A~ previously mentioned ancl illustrated by the examples herein~ the process or encapsulation of the lnstant invention pro~ides capsules capable o~ con~rolling release of encapsulated organic materialO Representat~e and especially of importance are the process and capsules comprising as a constituent in the organic phase herbic~des of the class thiocarbamate such as S-ethyl diisobutylthiocarbamate; S-e~hyl dipropylthlocarb$ma~e;
S-ethyl he~ahydro-l-H-azepine-l-carbothioate; S-propyl hexahydro-l-H-azepine-l-carbothioate; S-propyl dipropylthiocarbamate;
S-ethyl ethylcyclohexyl thiocarbamate; S-propyl butylethyl thio-carbamate; organo phosphorus insecticides of the class organo phosphono and phosphorothioates and dithioates such as O-ethyl S-phenyl ethylphosphonodithioate, S-[(p-chlorophenylthio)methyl~
O,O-dim~thyl phosphorodithioate, S~[(p-chlorophenylthio)methyl]
O,O-diethylphosphorodithioate, O,O-dimethyl O-p-nitrophenyl .
phosphorothioate, O,O-diethyl O-p-nitrophenyl phosphorothioate;
and insect hormones and mimics such as:
.
. ~ .
-27~
Cecro~:La - Juven~l~ llormone - I
1-(41-ethyl)phenoxy-3,7-dimethyl-6,7~epoxy-tranC;~2-octene __ ~~~
' 1~(3',4'-methylenedioxy)phenoxy~3~7-dimethyl -6 7-e~oxv-trans-2-nonene (~~
,~
0~\
Isopropyl ll-methoxy-3~7,11-trimethyl-dodeca~
oJ~
. .
: Capsules of compounds useIul for plant disease control provide a route to long term control of disease using compounds generally regarded to have only short term effectiveness. Simi-larly, herbicides, nematocides, insecticides, rodenticides and .. . .
.
-~ -2~-i . - . . ~ -soil nutrients can be encapsulated with useful results Cheml~
cals used for seed treatment are also readily encapsulated by the process of the invention. Other biological products can be encapsulated including: Anthelmintics, lamphrey and slime con-trol agents, algicides~ swimming pool chemicals, miticides~ acara-cides, animal attractants~ antiseptics, deodorants, disinfec-tants, mildewicides, and the like.
The material to be encapsulated utilizlng the process of the instant invention can be of any type which is water-immlscible. The material need not consist of only one type, but may be a combination of two or more various types of water~
immlscible materials. For example, employing an appropriate water-immiscible material, such a combination is an active her-bicide and an active insecticide. Also contemplated is a water-immiscible material to be encapsulated which comprises an active ingredient, such as an herbicide and an inactive ingredient such as a solvent or adjuvant. Encapsulation of a solid material can be accomplished by this method by forming a solution of the solid material in an appropriate solvent; thereby~ normally solid water-immiscible material can be encapsulated~ For example, the insec-ticide N-~mercaptomethyl) phthalimide S-(O,Owdimethyl phosphoro-dithioate~, m.p. 72C~, can be encapsulated by first dissolving the solid in an appropriate solvent, such as heavy aromatic naphtha solvent.
~ , .
:
.
,
Claims (88)
1. A process of encapsulating water-immiscible material within a shell of polyurea which comprises the steps:
(a) providing in an aqueous phase a solution comprising water, a surfactant and a protective colloid;
(b) adding to said aqueous phase a water-immiscible phase comprising the water-immiscible material to be encapsulated and an organic polyisocyanate;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in said aqueous phase;
(d) adjusting the pH of said aqueous phase to a value between 0 and 14;
(e) heating and maintaining the dispersed water-immiscible phase and aqueous phase in a temperature range of about 20°C. to about 90°C.; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution comprising water, a surfactant and a protective colloid;
(b) adding to said aqueous phase a water-immiscible phase comprising the water-immiscible material to be encapsulated and an organic polyisocyanate;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in said aqueous phase;
(d) adjusting the pH of said aqueous phase to a value between 0 and 14;
(e) heating and maintaining the dispersed water-immiscible phase and aqueous phase in a temperature range of about 20°C. to about 90°C.; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
2. A process for encapsulating water-immiscible material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water, a surfactant and a protective colloid;
(b) adding to said aqueous phase a water immiscible phase comprising organic polyisocyanate, a water-immiscible material and a basic organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the organic phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, a surfactant and a protective colloid;
(b) adding to said aqueous phase a water immiscible phase comprising organic polyisocyanate, a water-immiscible material and a basic organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the organic phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
3. A process for encapsulating water-immiscible mater-ial with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water, a surfactant and a protective colloid;
(b) adding to said aqueous solution a water-immiscible phase comprising organic polyisocyanate, a water-immiscible material and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the organic phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, a surfactant and a protective colloid;
(b) adding to said aqueous solution a water-immiscible phase comprising organic polyisocyanate, a water-immiscible material and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the organic phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
4. A process for encapsulating water-immiscible mater-ial within a shell of polyurea which comprises the steps:
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) heating and maintaining the aqueous phase at a temperature range of about 20°C. to about 90°C.;
(c) adding to said aqueous phase. a water-immiscible phase comprising the water-immiscible material to be encapsulated and an organic polyisocyanate;
(d) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) heating and maintaining the aqueous phase at a temperature range of about 20°C. to about 90°C.;
(c) adding to said aqueous phase. a water-immiscible phase comprising the water-immiscible material to be encapsulated and an organic polyisocyanate;
(d) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
5. The process of Claim 1 in which said water-immiscible material is water-immiscible organic material.
6. The process of Claim 5 for encapsulating water-immiscible organic material wherein the organic phase added to the aqueous phase contains organic polyisocyanate within the range of about 2.0 per cent to about 75.0 per cent by weight.
7. The process of Claim 6 for encapsulating water-immiscible organic material wherein said organic polyisocyanate is aromatic diisocyanate.
8. The process of Claim 7 for encapsulating water-immiscible organic material wherein said aromatic diisocyanate is 80 per cent 2,4- and 20 per cent 2,6-isomer of tolylene diisocyanate.
9. The process of Claim 6 for encapsulating water-immiscible organic material wherein said organic polyisocyanate is aromatic polyisocyanate.
10. The process of Claim 9 for encapsulating water-immiscible organic material wherein said aromatic polyisocyanate is polymethylene polyphenylisocyanate.
11. The process of Claim 5 for encapsulating water-immiscible organic material wherein the organic phase added to the aqueous phase is a combination of organic polyisocyanates, the total amount of which is within the range of about 2.0 per cent to about 75 per cent by weight.
12. The process of Claim 11 wherein said combination of organic polyisocyanates consist of polymethylene polyphenyl-isocyanate and 80 per cent 2,4- and 20 per cent 2,6-isomers of tolylene diisocyanate.
13. The process of Claim 2 in which said water-immiscible material is water-immiscible organic material.
14. The process of Claim 13 for encapsulating water-immiscible organic material wherein said basic organic tertiary amine catalyst is triethylene diamine in the amount of about 0.05 per cent to about 5.0 per cent by weight based on the organic phase.
15, The process of Claim 3 in which said water-immiscible material is water-immiscible organic material.
16. The process of Claim 15 for encapsulating water-immiscible organic material wherein said alkyl tin acetate catalyst is tri-n-butyl tin acetate.
17. The process of Claim 4 in which said water-immiscible material is water-immiscible organic material.
18. The process of Claim 5 wherein said water-immiscible organic material is a thiocarbamate herbicide and the temperature range is about 40°C. to about 60°C.; whereupon said thiocarbamate herbicide is encapsulated within a polyurea cap-sular enclosure,
19. The process of Claim 18 for encapsulating water-immiscible organic material within a polyurea capsule wherein said thiocarbamate herbicide is S-ethyl diisobutyl thiocarbamate.
20. The process of Claim 18 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said thiocarbamate herbicide is S-ethyl dipropylthio-carbamate.
21. The process of Claim 18 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said thiocarbamate herbicide is S-ethyl hexahydxo-1-H-azepine-1-carbothioate.
22. The process of Claim 18 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said thiocarbamate herbicide is S-propyl dipropylthio-carbamate.
23. The process of Claim 18 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said thiocarbamate herbicide is S-ethyl ethylcyclohexyl-thiocarbamate.
24. The process of Claim 18 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said thiocarbamate herbicide is S-propyl butylethyl-thiocarbamate.
25. The process of Claim 18 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said thiocarbamate herbicide is S-propyl hexahydro-1-H-azepine-1-carbothioate.
26. The process of Claim 5 wherein said water-immiscible organic material is an organophosphorus insecticide and the temperature range is about 40°C. to about 60°C., where-upon said organophosphorus insecticide is encapsulated within a polyurea capsular enclosure.
27. The process of Claim 26 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said organophosphorus insecticide is 0-ethyl S-phenyl ethylphosphonodithioate.
28. The process of Claim 26 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said organophosphorus insecticide is 0,0-dimethyl 0-p-nitrophenyl phosphorothioate.
29. The process of Claim 26 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said organophosphorus insecticide is 0,0-diethyl 0-p-nitrophenyl phosphorothioate.
30. The process of Claim 26 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said organophosphorus insecticide is S[(p-chlorophenyl-thio)methyl] 0,0-dimethyl phosphorodithioate.
31. The process of Claim 26 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said organophosphorus insecticide is S[(p-chlorophenyl-thio)methyl] 0,0-diethyl phosphorodithioate.
32. The process of Claim 5 wherein said water-immiscible organic material is an insect hormone mimic and the temperature range is about 40°C. to about 60°C., whereupon said insect hormone mimic is encapsulated within a polyurea capsular enclosure.
33. The process of Claim 32 for encapsulating a water-immiscible organic material within a polyurea capsule wherein said insect hormone mimic is 1-(4'-ethyl)phenoxy-3,7-dimethyl-6,7-epoxy-trans-2-octene.
34. The process of Claim 13 wherein said water-immiscible organic material is a thiocarbamate herbicide.
35. The process of Claim 15 wherein said water-immiscible organic material is a thiocarbamate herbicide.
36. The process of Claim 17 wherein said water-immiscible organic material is a thiocarbamate herbicide.
37. The process of Claim 13 wherein said water-immiscible organic material is an organophosphorus insecticide.
38. The process of Claim 15 wherein said water-immiscible organic material is an organophosphorus insecticide.
39. The process of Claim 17 wherein said water-immiscible organic material is an organophosphorus insecticide.
40. The process of Claim 13 wherein said water immiscible organic material is an insect hormone mimic.
41. The process of Claim 15 wherein said water-immiscible organic material is an insect hormone mimic.
42. The process of Claim 17 wherein said water immiscible organic material is an insect hormone mimic.
43. A process of encapsulating a water-immiscible organic material within a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) adding to said aqueous phase an organic phase comprising organic polyisocyanate and a water-immiscible organic material to be encapsulated;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in said aqueous phase;
(d) heating and maintaining the dispersed organic phase and aqueous phase in a temperature range of about 20°C.
to about 90°C.; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) adding to said aqueous phase an organic phase comprising organic polyisocyanate and a water-immiscible organic material to be encapsulated;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in said aqueous phase;
(d) heating and maintaining the dispersed organic phase and aqueous phase in a temperature range of about 20°C.
to about 90°C.; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
44. A process for encapsulating a water-immiscible organic material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) adding to said aqueous solution an organic phase comprising organic polyisocyanate, a water-immiscible organic material and a basic organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the organic phase;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) adding to said aqueous solution an organic phase comprising organic polyisocyanate, a water-immiscible organic material and a basic organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the organic phase;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
45. A process for encapsulating a water-immiscible organic material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) adding to said aqueous solution an organic phase comprising organic polyisocyanate, a water-immiscible organic material and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the organic phase;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) adding to said aqueous solution an organic phase comprising organic polyisocyanate, a water-immiscible organic material and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the organic phase;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
46. A process for encapsulating a water-immiscible organic material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution com-prising water, surfactant and protective colloid;
(b) heating and maintaining the aqueous phase at a temperature range of about 20°C. to about 90°C.;
(c) adding to said aqueous phase an organic phase comprising organic polyisocyanate and a water-immiscible organic material;
(d) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase; whereupon said water-immiscible organic material is encap-sulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution com-prising water, surfactant and protective colloid;
(b) heating and maintaining the aqueous phase at a temperature range of about 20°C. to about 90°C.;
(c) adding to said aqueous phase an organic phase comprising organic polyisocyanate and a water-immiscible organic material;
(d) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase; whereupon said water-immiscible organic material is encap-sulated within a polyurea capsular enclosure.
47. Capsules capable of controlled release of encap-sulated organic material comprising a thiocarbamate herbicide enclosed in a skin of a polyurea in the form of a microcapsule produced by the process of Claim 5.
48. Capsules of Claim 47 in which said thiocarbamate herbicide is S-ethyl diisobutylthlocarbamate.
49. Capsules of Claim 47 in which said thiocarbamate herbicide is S-ethyl dipropylthiocarbamate.
50. Capsules of Claim 47 in which said thiocarbamate herbicide is S-ethyl hexahydro-1-H-azepine-1-carbothioate,
51. Capsules of Claim 47 in which said thiocarbamate herbicide is S-propyl dipropylthiocarbamate.
52. Capsules of Claim 47 in which said thiocarbamate herbicide is S-ethyl ethylcyclohexylthiocarbamate.
53. Capsules of Claim 47 in which said thiocarbamate herbicide is S-propyl butylethylthiocarbamate.
54. Capsules of Claim 47 in which said thiocarbamate herbicide is S-propyl hexahydxo-1-H-azepine-1-carbothioate.
55. Capsules capable of controlled release of encap-sulated organic material comprising an organophosphorus insecti-cide enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 5.
56. Capsules of Claim 55 in which said organophos-phorus insecticide is O-ethyl S-phenyl ethylphosphonodithioate.
57. Capsules of Claim 55 in which said organophos-phorus insecticide is S[(p-chlorophenylthio)methyl] 0,0-dimethyl phosphorodithioate.
58. Capsules of Claim 55 in which said organophos-phorus insecticide is S[(p-chlorophenylthio)Methyl] 0,0-diethyl phosphorodithioate.
59. Capsules of Claim 55 in which said organophos-phorus insecticide is 0,0-dimethyl 0-p-nitrophenyl phosphoro-thioate.
60. Capsules of Claim 55 in which said organophos-phorus insecticide is 0,0-diethyl 0-p-nitrophenyl phosphoro-thioate.
61. Capsules capable of controlled release of encap-sulated organic material comprising an insect hormone mimic enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 5.
62. Capsules of Claim 61 in which said insect hormone mimic is 1-(4'-ethyl)phenoxy-3,7-dimethyl-6,7-epoxy-trans-2-octene.
63. Capsules capable of controlled release of encap-sulated organic material comprising a thiocarbamate herbicide enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 13.
64. Capsules capable of controlled release of encap-sulated organic material comprising an organophosphorus insec-ticide enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 13.
65. Capsules capable of controlled release of encap-sulated organic material com?rising an insect hormone mimic enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 13.
66. Capsules capable of controlled release of encap-sulated organic material comprising a thiocarbamate herbicide enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 15.
67. Capsules capable of controlled release of encap-sulated organic material comprising an organophosphorus insec-ticide enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 15.
68. Capsules capable of controlled release or encap-sulated organic material comprising an insect hormone mimic enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 15.
69. Capsules capable of controlled release of encap-sulated organic material comprising a thiocarbamate herbicide enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 17.
70. Capsules capable of controlled release of encap-sulated organic material comprising an organophosphorus insecticide enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 17.
71. Capsules capable of controlled release of encapsulated organic material comprising an insect hormone mimic enclosed in a skin of a polyurea in the form of a capsule produced by the process of Claim 17.
72. A process for encapsulating water-immiscible organic material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution comprising water, surfactant and protective colloid;
(b) adding to said aqueous solution an organic phase comprising organic polyisocyanate, a water-immiscible organic material and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the organic phase;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase;
(d) heating and maintaining the dispersed organic phase and aqueous phase in a temperature range of about 20°C.
to about 90°C.; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution comprising water, surfactant and protective colloid;
(b) adding to said aqueous solution an organic phase comprising organic polyisocyanate, a water-immiscible organic material and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the organic phase;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase;
(d) heating and maintaining the dispersed organic phase and aqueous phase in a temperature range of about 20°C.
to about 90°C.; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
73. A process for encapsulating a water-immiscible organic material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) adding to said aqueous solution an organic phase comprising organic polyisocyanate, a water-immiscible organic material and a basic organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the organic phase;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase; whereupon said water-immiscible organic material is encap-sulated within a polyurea capsular enclosure;
(d) heating and maintaining the dispersed organic phase and aqueous phase in a temperature range of about 20°C. to about 90°C.; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, surfactant and protective colloid;
(b) adding to said aqueous solution an organic phase comprising organic polyisocyanate, a water-immiscible organic material and a basic organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the organic phase;
(c) dispersing said organic phase in said aqueous phase to establish droplets of the organic phase in the aqueous phase; whereupon said water-immiscible organic material is encap-sulated within a polyurea capsular enclosure;
(d) heating and maintaining the dispersed organic phase and aqueous phase in a temperature range of about 20°C. to about 90°C.; whereupon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
74. A process of encapsulating water-immiscible material within a shell of polyurea which comprises the steps:
(a) providing in an aqueous phase a solution comprising water and a surfactant;
(b) adding to said aqueous phase a water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate.;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in said aqueous phase;
(d) adding to the dispersion a protective colloid;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14;
(f) heating and maintaining the dispersed water-immiscible phase and aqueous phase in a temperature range of about 20°C. to about 90°C.; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution comprising water and a surfactant;
(b) adding to said aqueous phase a water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate.;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in said aqueous phase;
(d) adding to the dispersion a protective colloid;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14;
(f) heating and maintaining the dispersed water-immiscible phase and aqueous phase in a temperature range of about 20°C. to about 90°C.; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
75. A process for encapsulating water-immiscible material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) adding to said aqueous phase a water-immiscible phase comprising organic polyisocyanate, a water immiscible material to be encapsulated and an organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the water immiscible phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a protective colloid;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) adding to said aqueous phase a water-immiscible phase comprising organic polyisocyanate, a water immiscible material to be encapsulated and an organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the water immiscible phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a protective colloid;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
76. A process for encapsulating water-immiscible material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) adding to said aqueous solution a water-immiscible phase comprising organic polyisocyanate, a water-immiscible material to be encapsulated and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the water-immiscible phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a protective colloid;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) adding to said aqueous solution a water-immiscible phase comprising organic polyisocyanate, a water-immiscible material to be encapsulated and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the water-immiscible phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a protective colloid;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
77. A process for encapsulating water-immiscible material within a shell of polyurea which comprises the steps:
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) heating and maintaining the aqueous phase at a temperature range of about 20°C. to about 90°C.;
(c) adding to said aqueous phase a water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate;
(d) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(e) adding to the dispersion a protective colloid;
(f) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) heating and maintaining the aqueous phase at a temperature range of about 20°C. to about 90°C.;
(c) adding to said aqueous phase a water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate;
(d) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(e) adding to the dispersion a protective colloid;
(f) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
78. The process of Claim 74 in which said water-immiscible material is water-immiscible organic material, where-upon said water-immiscible organic material is encapsulated with-in a polyurea capsular enclosure.
79. The process of Claim 75 in which said water-immiscible material is water-immiscible organic material, where-upon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
80. The process of Claim 76 in which said water-immiscible material is water-immiscible organic material, where upon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
81. The process of Claim 77 in which said water-immiscible material is water-immiscible organic material, where-upon said water-immiscible organic material is encapsulated within a polyurea capsular enclosure.
82. A process for encapsulating water-immiscible mater ial with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water, a surfactant and a protective colloid;
(b) adding to said aqueous phase a water-immiscible phase comprising organic polyisocyanate and a water-immiscible material;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a catalyst;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, a surfactant and a protective colloid;
(b) adding to said aqueous phase a water-immiscible phase comprising organic polyisocyanate and a water-immiscible material;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a catalyst;
(e) adjusting the pH of said aqueous phase to a value between 0 and 14; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
83. The process of Claim 82 for encapsulating water-immiscible material wherein said catalyst is a basic organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the total dispersion.
84. A process for encapsulating water-immiscible material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water, a surfactant and a protective colloid;
(b) adding to said aqueous phase a water immiscible phase comprising organic polyisocyanate and a water-immiscible material;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a catalyst; where-upon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water, a surfactant and a protective colloid;
(b) adding to said aqueous phase a water immiscible phase comprising organic polyisocyanate and a water-immiscible material;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a catalyst; where-upon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
85. A process of encapsulating water-immiscible material within a shell of polyurea which comprises the steps:
(a) providing in an aqueous phase a solution comprising water and a surfactant;
(b) adding to said aqueous phase a water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in said aqueous phase;
(d) adding to the dispersion a protective colloid;
(e) heating and maintaining the dispersed water-immiscible phase and aqueous phase in a temperature range of about 20°C. to about 90°C.; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution comprising water and a surfactant;
(b) adding to said aqueous phase a water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in said aqueous phase;
(d) adding to the dispersion a protective colloid;
(e) heating and maintaining the dispersed water-immiscible phase and aqueous phase in a temperature range of about 20°C. to about 90°C.; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
86. A process for encapsulating water-immiscible material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) adding to said aqueous phase a wate??
immiscible phase comprising organic polyisocyanate, a water immiscible material to be encapsulated and an organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the water-immiscible phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a protective colloid; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) adding to said aqueous phase a wate??
immiscible phase comprising organic polyisocyanate, a water immiscible material to be encapsulated and an organic tertiary amine catalyst in the amount of about 0.01 per cent to about 10.0 per cent by weight based on the water-immiscible phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a protective colloid; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
87. A process for encapsulating water-immiscible material with a polyurea capsule which comprises the steps:
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) adding to said aqueous solution a water-immiscible phase comprising organic polyisocyanate, a water-immiscible material to be encapsulated and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the water-immiscible phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a protective colloid;
whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) adding to said aqueous solution a water-immiscible phase comprising organic polyisocyanate, a water-immiscible material to be encapsulated and an alkyl tin acetate catalyst in the amount of about 0.001 per cent to about 1.0 per cent by weight based on the water-immiscible phase;
(c) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(d) adding to the dispersion a protective colloid;
whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
88. A process for encapsulating water-immiscible material within a shell of polyurea which comprises the steps:
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) heating and maintaining the aqueous phase at a temperature range of about 20°C. to about 90°C.;
(c) adding to said aqueous phase a water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate;
(d) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(e) adding to the dispersion a protective colloid; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
(a) providing in an aqueous phase a solution of water and a surfactant;
(b) heating and maintaining the aqueous phase at a temperature range of about 20°C. to about 90°C.;
(c) adding to said aqueous phase a water-immiscible phase comprising a water-immiscible material to be encapsulated and an organic polyisocyanate;
(d) dispersing said water-immiscible phase in said aqueous phase to establish droplets of the water-immiscible phase in the aqueous phase;
(e) adding to the dispersion a protective colloid; whereupon said water-immiscible material is encapsulated within a polyurea capsular enclosure.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US23479372A | 1972-03-15 | 1972-03-15 | |
| US234,793 | 1972-03-15 | ||
| US32317173A | 1973-01-12 | 1973-01-12 | |
| US323,171 | 1973-01-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1104882A true CA1104882A (en) | 1981-07-14 |
Family
ID=26928288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA164,086A Expired CA1104882A (en) | 1972-03-15 | 1973-02-20 | Encapsulation process |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS585697B2 (en) |
| AT (1) | AT339257B (en) |
| BE (1) | BE796746A (en) |
| CA (1) | CA1104882A (en) |
| CH (1) | CH589478A5 (en) |
| DK (1) | DK144784C (en) |
| FR (1) | FR2176071B1 (en) |
| GB (1) | GB1371179A (en) |
| HU (1) | HU166773B (en) |
| IL (1) | IL41773A (en) |
| IT (1) | IT988133B (en) |
| MX (1) | MX147152A (en) |
| NL (1) | NL180985C (en) |
| RO (4) | RO68788A (en) |
| YU (2) | YU67473A (en) |
Families Citing this family (31)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1044134A (en) * | 1975-04-09 | 1978-12-12 | Minnesota Mining And Manufacturing Company | Microcapsule insecticide composition |
| US4140516A (en) * | 1977-05-31 | 1979-02-20 | Stauffer Chemical Company | Encapsulation process employing phase transfer catalysts |
| US4223070A (en) * | 1978-05-04 | 1980-09-16 | Stauffer Chemical Company | Impregnated porous granules with slow release pore membranes and process therefor |
| DK253779A (en) * | 1978-08-03 | 1980-02-04 | Du Pont | INSECTICID AGENT AND PROCEDURE FOR PREPARING THEREOF |
| JPS5579867U (en) * | 1978-11-29 | 1980-06-02 | ||
| US4280833A (en) * | 1979-03-26 | 1981-07-28 | Monsanto Company | Encapsulation by interfacial polycondensation, and aqueous herbicidal composition containing microcapsules produced thereby |
| JPS5615836A (en) * | 1979-07-19 | 1981-02-16 | Mitsubishi Paper Mills Ltd | Micro capsule |
| DE2930409A1 (en) * | 1979-07-26 | 1981-02-12 | Bayer Ag | SPRAY DRYING OF MICROCAPSEL DISPERSIONS |
| JPS56115635A (en) * | 1980-02-18 | 1981-09-10 | Kanzaki Paper Mfg Co Ltd | Production of microcapsule |
| US4384975A (en) * | 1980-06-13 | 1983-05-24 | Sandoz, Inc. | Process for preparation of microspheres |
| US4439581A (en) * | 1981-09-03 | 1984-03-27 | Kanzaki Paper Manufacturing Co., Ltd. | Method for the production of microcapsules |
| JPS5880992U (en) * | 1981-11-24 | 1983-06-01 | 日立化成工業株式会社 | bathroom unit |
| JPS59166966A (en) * | 1983-03-14 | 1984-09-20 | Fuji Photo Film Co Ltd | Production of capsule toner |
| AR240875A1 (en) * | 1984-01-09 | 1991-03-27 | Stauffer Chemical Co | PROCEDURE FOR PRODUCING MULTIPLE SIZE POLYUREA CAPSULES CONTAINING A WATER IMMISCIBLE MATERIAL INSIDE IT AND THE RESULTING CAPSULES |
| US4681806A (en) * | 1986-02-13 | 1987-07-21 | Minnesota Mining And Manufacturing Company | Particles containing releasable fill material and method of making same |
| JPH0818937B2 (en) * | 1987-07-06 | 1996-02-28 | 住友化学工業株式会社 | Organophosphorus insecticidal composition for agricultural and horticultural use |
| GB8827029D0 (en) * | 1988-11-18 | 1988-12-21 | Ici Plc | Insecticidal compositions |
| US5461027A (en) | 1989-01-24 | 1995-10-24 | Griffin Corporation | Microencapsulated pendimethalin and method of making and using same |
| US5160530A (en) * | 1989-01-24 | 1992-11-03 | Griffin Corporation | Microencapsulated polymorphic agriculturally active material |
| US5526607A (en) * | 1991-08-15 | 1996-06-18 | Net/Tech International | Water dispersible delivery system for an agriculturally active chemical |
| US5335449A (en) * | 1991-08-15 | 1994-08-09 | Net/Tech International, Inc. | Delivery system for an agriculturally active chemical |
| KR100313589B1 (en) * | 1993-02-09 | 2002-11-29 | 노바티스 아게 | Process for the preparation of microcapsules |
| US5866153A (en) * | 1993-02-09 | 1999-02-02 | Novartis Corporation | Process for the preparation of microcapsules |
| IL108835A (en) * | 1994-03-03 | 1997-08-14 | Ben Researchiversity Of The Ne | Microencapsulated composition containing chlorpyrifos or endosulfan |
| US6248364B1 (en) | 1997-04-07 | 2001-06-19 | 3M Innovative Properties Company | Encapsulation process and encapsulated products |
| US6080418A (en) * | 1997-04-07 | 2000-06-27 | 3M Innovative Properties Company | Suspensions of microcapsules containing biologically active ingredients and adhesive microspheres |
| US6540991B2 (en) | 2001-04-06 | 2003-04-01 | 3M Innovative Properties Company | Stabilized active materials |
| KR20060031602A (en) * | 2003-05-11 | 2006-04-12 | 벤 구리온 유니버시티 오브 더 네게브 리서치 앤드 디벨로프먼트오서리티 | Encapsulated essential oils |
| BR112015001697A2 (en) | 2012-07-27 | 2017-07-04 | Fmc Corp | clomazone formulations |
| BR112017007586B1 (en) | 2014-11-07 | 2020-12-01 | Givaudan Sa | composition for encapsulated perfume, its formation method and personal hygiene product without rinsing |
| ES2746271T3 (en) | 2014-11-07 | 2020-03-05 | Basf Se | Process for the preparation of microcapsules that have a polyurea coating and a lipophilic core material |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH453305A (en) * | 1963-10-21 | 1968-06-14 | Pilot Pen Co Ltd | Process for encapsulating fine droplets of dispersed liquids |
| US3577515A (en) * | 1963-12-13 | 1971-05-04 | Pennwalt Corp | Encapsulation by interfacial polycondensation |
| US3464926A (en) * | 1965-04-26 | 1969-09-02 | Pennwalt Corp | Process for encapsulation |
-
1973
- 1973-02-20 CA CA164,086A patent/CA1104882A/en not_active Expired
- 1973-02-26 GB GB929473A patent/GB1371179A/en not_active Expired
- 1973-03-13 IT IT48761/73A patent/IT988133B/en active
- 1973-03-14 FR FR7309186A patent/FR2176071B1/fr not_active Expired
- 1973-03-14 BE BE128772A patent/BE796746A/en not_active IP Right Cessation
- 1973-03-14 YU YU00674/73A patent/YU67473A/en unknown
- 1973-03-14 IL IL41773A patent/IL41773A/en unknown
- 1973-03-15 NL NLAANVRAGE7303636,A patent/NL180985C/en not_active IP Right Cessation
- 1973-03-15 RO RO7388706A patent/RO68788A/en unknown
- 1973-03-15 RO RO7300074170A patent/RO63946A/en unknown
- 1973-03-15 HU HUSA2477A patent/HU166773B/hu unknown
- 1973-03-15 MX MX142259A patent/MX147152A/en unknown
- 1973-03-15 DK DK139873A patent/DK144784C/en active
- 1973-03-15 AT AT233373A patent/AT339257B/en not_active IP Right Cessation
- 1973-03-15 RO RO7388705A patent/RO68787A/en unknown
- 1973-03-15 JP JP48029562A patent/JPS585697B2/en not_active Expired
- 1973-03-15 CH CH382373A patent/CH589478A5/xx not_active IP Right Cessation
- 1973-03-15 RO RO7388704A patent/RO68786A/en unknown
-
1978
- 1978-03-14 YU YU674/73A patent/YU39646B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB1371179A (en) | 1974-10-23 |
| AT339257B (en) | 1977-10-10 |
| RO68787A (en) | 1980-01-15 |
| CH589478A5 (en) | 1977-07-15 |
| FR2176071A1 (en) | 1973-10-26 |
| YU67473A (en) | 1982-02-28 |
| ATA233373A (en) | 1977-02-15 |
| FR2176071B1 (en) | 1977-04-22 |
| DK144784B (en) | 1982-06-07 |
| BE796746A (en) | 1973-09-14 |
| HU166773B (en) | 1975-05-28 |
| JPS585697B2 (en) | 1983-02-01 |
| IL41773A0 (en) | 1973-05-31 |
| JPS492779A (en) | 1974-01-11 |
| RO68788A (en) | 1980-01-15 |
| DK144784C (en) | 1982-10-25 |
| RO68786A (en) | 1980-10-30 |
| NL180985B (en) | 1987-01-02 |
| MX147152A (en) | 1982-10-19 |
| NL180985C (en) | 1987-06-01 |
| IT988133B (en) | 1975-04-10 |
| IL41773A (en) | 1975-11-25 |
| NL7303636A (en) | 1973-09-18 |
| YU39646B (en) | 1985-03-20 |
| RO63946A (en) | 1978-09-15 |
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