CA1084783A - Process for encapsulation by interfacial polymerization - Google Patents
Process for encapsulation by interfacial polymerizationInfo
- Publication number
- CA1084783A CA1084783A CA278,422A CA278422A CA1084783A CA 1084783 A CA1084783 A CA 1084783A CA 278422 A CA278422 A CA 278422A CA 1084783 A CA1084783 A CA 1084783A
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- Prior art keywords
- liquid
- precursor
- droplets
- polycondensate
- phase
- Prior art date
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- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing Of Micro-Capsules (AREA)
- Polyamides (AREA)
- Polymerisation Methods In General (AREA)
- Other Resins Obtained By Reactions Not Involving Carbon-To-Carbon Unsaturated Bonds (AREA)
- Polyurethanes Or Polyureas (AREA)
Abstract
PROCESS FOR ENCAPSULATION BY INTERFACIAL
POLYMERIZATION (IR 2229) Abstract of the Disclosure An efficient process is disclosed for the encapsulation of products using an interfacial polymerization procedure wherein a stabilized dis-persion of liquid droplets within a continuous fluid phase is formed by incorporating a reactive precursor of an emulsifier in said liquid prior to dispersing the liquid in the continuous phase, and then dispersing the liquid in the continuous fluid phase containing a component reactive with said precursor for forming said emulsifier whereby said emulsifier is formed in situ.
POLYMERIZATION (IR 2229) Abstract of the Disclosure An efficient process is disclosed for the encapsulation of products using an interfacial polymerization procedure wherein a stabilized dis-persion of liquid droplets within a continuous fluid phase is formed by incorporating a reactive precursor of an emulsifier in said liquid prior to dispersing the liquid in the continuous phase, and then dispersing the liquid in the continuous fluid phase containing a component reactive with said precursor for forming said emulsifier whereby said emulsifier is formed in situ.
Description
~ r J~783 This invcnlion concerns an improved proccss for thc enc~lpsula-tlon of products by inter~aci~l polymcrization of one or more polymer formincJ int~ a~es whcrein a stabllizccl disperslon of droplets oE the substance to b~ encapsulatcd is formed, ancl polymerization (polycon- ;
densation or poly-addition) occurs at the interface`o~ the droplets and the continuou.s liquid phase in which they are dispersed.
Prior methods of forming droplets of suitable size in int~rfacial polymerization procedures generally require that a droplet stabilizer first be dissolved in the continuous phase usually in a separate mixing l tank employing special agitation equipment. Frequently, the required stabilizers are such poor emulsifiers tha t the formation of droplets of suitable size required the use of hlgh shear equipment whlch is expen-sive, mechanically tr a~ilesome, requires accurate flow-control and li-mits the rate of production.
The above described prior method of forming dispersed droplets as the discontinuous phase within a dissimilar continuous liquid phase has .
been practiced in the past, for example, as disclosed in USP 3, 577, 515.
This patent describes a procedure for encapsulation by in~erfacial con-densatlon polymerization wherein it is required that a dispersion of one liquid phase in another be Eormed as an lnitial step, and then in sub~
sequent steps, a polymer walL is farme~ ~ound each drop1et to provide the desired encapsulated sukstance. It is noted in said patent that, when the organic phase is the one tobe dispersed, polyvinyl alcohol, gelatin, and methyl cellulose are effective droplet stabilizers. These are, by choice, poor emulsifiers that serve only to stabilize the drop-. :~
: .
~ --2-- !
:
. , . ~ ~
. . ' ' ' ~ . '.
c ) 1(?89L'7l~3 lets durincJ polyrneri~ation; an officiell~ emulsifie~r would disperse the droplets too ~inely.
Likewlse, in 13ritish 1, 371,179, there is described a process for preparin~7 polyurea capsules by an interfacial p~lymerization technique 5 and, in this process similar stabilizers are employed. Other prior dis-closures of the preparatisn of encapsulated products by related inter-facial polymerization techniques include, for example, U. S. Patenl:s No. 3, 429J 827; 3, 575, 882 and 3, 886, 085; Belgian Patent No.
832, 897; and British Patent No. 1, 416, 294. Such processes have in common, the dispersion of a substance to be encapsu~ ted as a dis-continuous phase within a continuous liquid phase. The present inven-tion will be advantageously employed in any such processes wherein stabilizers are employed to provide for the formation of droplets of suitable size in the dispersion.
It is a primary object of this invention toprovidea more efficient .
method cf prep3ring encapsulat~dsubstances employing an interfacial polymerlzation procedure wherein the substance to be encapsulated is more rapidly and easily iormed into dispersed, stabilized droplets Oe suitable size in a continuous liquid phase.
It is a further object Oe this invention to provide a more ePicient method of preparing microencapsulated liquids employing an interfacial polycondensation procedure wherein the formation and size of droplets o said liquids within a continuous fluid phase is facilitated.
These and other objects are accomplished in accordance with thls invention which ls a prooess for encapsulatlng products wlthln ~¦
`- "_3_ ~ I
I .
. ~ I .
it4'7~3 a capsulc polymcr wall by an in-L~rfacial p~lymeriz~tion procedur~
wherein a sta~ cd dispersion of droplets of a first liquid to be encap-sulated is forrrlcd withill a continuous phase of a second liquid, including the improvement which comprisè.s incorporating a precursor of an emul-slfying agent for said dlspersion in said first liquid, and then mixlng said first liquid illtO said second liquid to form said droplets within a continuous liquid phase, said second liquid having incorporated therein a component reactive with sàid precursor for forming said emul-sifying agent whereby said emulsifying agent is Eorrned in situ, said precursor and component reactive therewith being incorporated in said first and second liquids in amounts sufficient to provide an amount o emulsifying agent sufficient to improve the stability o sald dispersion.
The emulsifier which is formed in situ, as disclosed herein, may be anionic, cationic or non-ionic depending on the liquid system em-:
: 15 ployed inthe lnterEacial polymerization technique.
In a preferred embodiment of this invention, the liquid of the dis-persed droplet phase is an organic liquid, more preferably, an organic liquid whlch is to be encapsulated by interfacial polycondensation :~ while the continuous phase or second liquid is an aqueous medium more preferably containing at least one ingredlent that will ultimately react to become part of the capsule wall.
In the practice of the preerred form o this invé~fnion, a controlbd amount of one reactive component of an anionic emulsifier is dissolved ln one of the liquid phases, and the remaining reactive component or compon~ts dissolvedin the other liquid phase. When the phases are ~ ~ . , .
~ ~4~
; 4~83 are brought together w~th only mild a~itation, sufficiently stabill~ed droplets are rapLdly produced. For example, in the preparation of encapsulated products wherein the contlnuous phase is aqueous, a fatty acid is dissolved in the organlc phase and a base is diqsolved in the aqueous phase.
Preferably, the base is dissolved in the aqueous phase before the addition of the organic phase thereto, although the base may be added to the aqueous phase simultaneously with the organic phase. On conventional reactor mixing, stabilized droplets are efficiently formed because the stabilizer is produced where it is needed, i.e., at the interface.
The amount of emulsifier to be formed varies with the system and the particle size desired, but for systems employing aqueous media as the continuous phase, it is typically in the range of 0.05~ based on the weight of the dispersed phase. Thus, sufficient amounts of each of the emulsifier precursors are employed to provide the desired amount of in situ ~ormed emulsifying agent.
This new process eliminates the need for special mixing equipment and lengthy mixing times for preparing stabilizer solutions, and also eliminates the need to employ high shear mixing devices for dispersing the droplets. In actual practice several hours can be saved per batch of encapsulated material, the process control requirements are greatly simplified, and frequently, much higher-solids dispersions can be prepared. The eEEicient technique of this invention lends itself especially well to continous production.
In the preferred practice of this invention any oE a wide variety of surfactants or emulsifiers can be formed at thè phase interface, for example, carboxylates, sulfonates, sulfates, and phosphates in which the cation is either a metal or an amine. Obviously, the choice will depend on the particular overall system and will be made so as not to adversely interfere with the capsule-wall forming reaction. Most commonly, the cation precursor component for the emulslfier will be a metal. Particularly useful are the - 5 - ;
' ~0~ 83 alkali metals including Na ~3, K ~and Li , wlth Na6~being especially preferred.
A wlde variety of anions are applicable and are well kno~l to those famillar with dispers:Lon technology.
The choice of anion or catlon or mixtures thereof, will depend on the particular system oE interest. C16-C18 aliphatic fatty acids, for example, oleic, stearic and palmitic acids, have been found to be generally useful as the anionic precusors component for the emulsifier, and oleic acid is .
preferred for the preferred embodiment.
A good review of anionic, cationic and non-ionic surfactants is -~
presented in the Kirk-Othmer "Encyclopedia of Chemical Technology", 2nd Ed., Vol. 19, pp. 512-566. `
As more specific preferred examples of polymerization reactions to which the present encapsulation process is applicable, the following may be mentioned: Diamines or polyamines in the aqueous phase and diacid or polyacid chlorides in the organic phase are reacted to yield capsule walls consisting oE p~y rides. Di~mLnes or polya-ine~ in '.
~; ~ ''; ~ . "
'~ ' ' ~;''' -, f~
the aqucous liquid and l~lsc~lloroforlrlatos or polychloroEormates in the organlc liquid afford a polyuretll~ne capsule skin. Agaln, diamines or polyamines in l:he aqlleous medium antl disulfonyl or polysulfonyl chlorides in the ~rganic solv~nt pr~uce a pc>lysulfonamide skin. Like-wise, with diamines or polyamines in the aqueous phase, a polyurea capsule wall is obtainable when the organic phase contains phosgene (chloroformyl chloride) which, for convenience oE classification herein, may be considered to have the properties of a difunctional acid chloride, i. e., in some correspondence with diacid chlorides such as sebacoyl chloride. Also, diamines or polyamine s in the aqueous media and diisocyanates or polyisocyanates in the organic solvents produce a polyurea sl~in.
With diols or polyols in the aqueous liquid, various other con-densate resins are achieved. Thus with diacid or polyacid chlorides in the organic phase, polyesters are produced to constitute the capsule wall. When bischloroformatesJ polychloroformates or phosgene are used in the organic liquid the capsule skins are polycarbonates. Not only are there other complementary intermediates which react to orm polycondensates in a direct manner useful in the interfacial poly-condensation proaess~ enaapsul~tlon, but various mixtures of inter-mediates may be employed in either or both liquid phases. For oxampl0, mixtures of diols and diamines in the aqueous liquid and also or alter-natively, mixtures oE acid chlorides and chloroformates in the organic solvent are useful to achieve corresponding condensation copolymers.
A primary example of a condensation copolymer is one formed with a . , "
7l~3 difunctional acid chlorlde, e. g. sebacoyl dichloride; a multifunctional amine, e.g. ethylene diamine/diethylene triamine mixture; and a polyeunctional isocyanate, e.g. polymethylene polyphenyllsocyanate. This copolymer has been referred to as a crosslinked polyamide-polyurea (amide-urea copolymer). Also, diols or polyols in the aqueous liquid and diisocyanates or polyisocyanates in the organic liquid produce a polyurethane skin. ;?
In the system for interfacial polymerization wherein a stabilized ;~
dispersion of droplets of a first liquic1 to be encapsulated is ~ormed within a continuous phase of a second liquid, the two liquids should be immiscible, at least one of them being an organic liquid, and the other preferably an aqueous medium. A wide variety of organic solvents may be employed, e.g., as will be recognized to be appropriate for the selected intermediate or intermediates.
Some examples, are mineral oil, xylene, benzene, carbon disulfide, carbon tetrachloride, pentane, and the like, as well as liquids which may not only serve the function of a solvent for the polymer-forming reactant but may also have a reactant function to be availed of after formation of the capsules.
Instances of such reactant liquids which in the encapsulation steps of the invention serve simply the function of an organic solvent are styrene and di-t-butyl peroxide.
,~.
Examples of difunctional acid-derived compounds are sebacoyl chloride, ethylene bischloroformate, phosgene, terephthaloyl chloride, adipoyl chloride, azelaoyl chloride (azelaic acid chloride)S dodecanedioic acld chloride, dimer acid chloride, and l,3-benzenesulfonyl dichloride.
. . .
; ' ' ' ' ' ' ....
, .
~'~
- 8 - i;
, . '; '.
'' ' ' ' '~
.... .. , , . . ,. . . , . , .: . . . .
Polyf~lnctlonal compl~unds o~ tllis type are exempllfied by trlmcsoyl chloricle; 1, 2, ~, 5 benzene tcl:raacid chloride; l, 3, 5-~_nzene l:risulfonyl chlc>ride; trlmer acid chloride; citrlc acid chloride; and l, 3, 5-benæene trischloroformate. Intermediates similarly useful in the organic phase also include diisocyanates and polyisocyanates,for example,toluene diisocyanate, hexamethylene diisocyanaie and polymethylene polyphenylisocyanate, e. ~., P~lPI~The Upj ohn Co. ) .
As examples of suitable diols for use as intermediates in an aqueous phase, there may be named bisphenol A[2, 2bis (p, p'dihydrox~
diphenyl) propane], hydroquinone, resorcinol, catechol, and various glycols such as ethylene glycol, pentanediol, hexanediol, dodecanediol :
and the like. Polyfunctional alcohols e. g. triols, are exernplified by pyrogallol (l, 2, 3-benzenetriol) phloroglucinol dihydrate, pentaerythritol, trimethylolpropane, 1, 4, 9,10-tetrahydroxyanthracene, 3, 4-dihydroxyan-thranol, diresorcinol, tetrahydroxyquinone and antralin.
Suitable diami.as and polyamlnes, usually selected as water soluble per se or in water soluble salt form, where such reactant is to be included in an a~ueous phase, are: substances eEfective as difunc-tional reactants (contributing no significant cross~linking effect of themselves~, namely ethylene diamine, phenylene dlamine, toluene diamine, hexamethylene diamine, cliçthYlere triiamine. pipera~in~^ an~J
substances effecti~e as polyfunctional reactants (contributing cross-linking effect, and usèful alone or at least in combination with another amine of at least dif~ctional character), namelyl, 3, 5-benzene triamine trihydrochloride, 2, 4, 6-triamino toluene trihydrochloride, tetraethylene ': `
? ~ &~ 9 . .
, . ' ,,,,'.
4t~83 pentamine, pentaethylene hexamine, polyethylene-imine, 1,3,6-triaminonaph-thalene, 3S4,5-triamino-1,2,4-trla~ole, melamine, and 1,4,5,8-tetraminosnthra-quinone. To t~e extent that the reactant to be used in the aqueous phase may be insoluble or have limited solubil~ty in water per se, it may be used in a form or with appropriate cooperating substances to render it, in effect, soluble. Thus, certain amines may be used in hydrochloride or other salt form, while a compound of little or no water solubility (by itself), such as bisphenol A, may be used in a composition appropriately ad~usted as with alkali, to afford such solubility.
Interfacial polycondensation to form the capsule wall as shown in British Patent No. 1,371~179 provides a reac~ant amine by the hydrolysis of an isocyanate which reactant amine in turn reacts with a free isocyanate to form the polyurea enclosure (capsule wall). After the dispersion establishing droplets of the organic phase within a continuous liquid phase has been accompllshed, and preferably with moderate agitation of the dispersion~ the formation of the polyurea capsule wall around the dispersed droplets i9 brought about by heating thecontinuous liquid phase or by introducing a catalytic amount of a basic amine or other agent capable of increasing the rate of isocyanate hydrolysis, and optionally in addition, ad~usting the pH
of the dispersion, thereby effecting the desired condensation reaction at ~:
the interface between the droplets and the continous phase.
~ The organic polyisocyanates contemplated in the above described process are those members of the aromatic polyisocyanate class which ~'~ '',' , , ................................. . . . . . .
7~
includes the aron~atic diisocyanates, the aliphatic diisocyanate class, high moiecular weigllt linear aliphatic diisocyanates and the isocyanate prepolymers.
Representative of the aromatic diisocyanates and other polyisocyanates are the following:
l-Chloro - 2,4 - phenylene diisocyanate m-Phenylene diisocyanate p-Phenylene diisocyanate 4,4'-Methylene bis (phenyl isocyanate)
densation or poly-addition) occurs at the interface`o~ the droplets and the continuou.s liquid phase in which they are dispersed.
Prior methods of forming droplets of suitable size in int~rfacial polymerization procedures generally require that a droplet stabilizer first be dissolved in the continuous phase usually in a separate mixing l tank employing special agitation equipment. Frequently, the required stabilizers are such poor emulsifiers tha t the formation of droplets of suitable size required the use of hlgh shear equipment whlch is expen-sive, mechanically tr a~ilesome, requires accurate flow-control and li-mits the rate of production.
The above described prior method of forming dispersed droplets as the discontinuous phase within a dissimilar continuous liquid phase has .
been practiced in the past, for example, as disclosed in USP 3, 577, 515.
This patent describes a procedure for encapsulation by in~erfacial con-densatlon polymerization wherein it is required that a dispersion of one liquid phase in another be Eormed as an lnitial step, and then in sub~
sequent steps, a polymer walL is farme~ ~ound each drop1et to provide the desired encapsulated sukstance. It is noted in said patent that, when the organic phase is the one tobe dispersed, polyvinyl alcohol, gelatin, and methyl cellulose are effective droplet stabilizers. These are, by choice, poor emulsifiers that serve only to stabilize the drop-. :~
: .
~ --2-- !
:
. , . ~ ~
. . ' ' ' ~ . '.
c ) 1(?89L'7l~3 lets durincJ polyrneri~ation; an officiell~ emulsifie~r would disperse the droplets too ~inely.
Likewlse, in 13ritish 1, 371,179, there is described a process for preparin~7 polyurea capsules by an interfacial p~lymerization technique 5 and, in this process similar stabilizers are employed. Other prior dis-closures of the preparatisn of encapsulated products by related inter-facial polymerization techniques include, for example, U. S. Patenl:s No. 3, 429J 827; 3, 575, 882 and 3, 886, 085; Belgian Patent No.
832, 897; and British Patent No. 1, 416, 294. Such processes have in common, the dispersion of a substance to be encapsu~ ted as a dis-continuous phase within a continuous liquid phase. The present inven-tion will be advantageously employed in any such processes wherein stabilizers are employed to provide for the formation of droplets of suitable size in the dispersion.
It is a primary object of this invention toprovidea more efficient .
method cf prep3ring encapsulat~dsubstances employing an interfacial polymerlzation procedure wherein the substance to be encapsulated is more rapidly and easily iormed into dispersed, stabilized droplets Oe suitable size in a continuous liquid phase.
It is a further object Oe this invention to provide a more ePicient method of preparing microencapsulated liquids employing an interfacial polycondensation procedure wherein the formation and size of droplets o said liquids within a continuous fluid phase is facilitated.
These and other objects are accomplished in accordance with thls invention which ls a prooess for encapsulatlng products wlthln ~¦
`- "_3_ ~ I
I .
. ~ I .
it4'7~3 a capsulc polymcr wall by an in-L~rfacial p~lymeriz~tion procedur~
wherein a sta~ cd dispersion of droplets of a first liquid to be encap-sulated is forrrlcd withill a continuous phase of a second liquid, including the improvement which comprisè.s incorporating a precursor of an emul-slfying agent for said dlspersion in said first liquid, and then mixlng said first liquid illtO said second liquid to form said droplets within a continuous liquid phase, said second liquid having incorporated therein a component reactive with sàid precursor for forming said emul-sifying agent whereby said emulsifying agent is Eorrned in situ, said precursor and component reactive therewith being incorporated in said first and second liquids in amounts sufficient to provide an amount o emulsifying agent sufficient to improve the stability o sald dispersion.
The emulsifier which is formed in situ, as disclosed herein, may be anionic, cationic or non-ionic depending on the liquid system em-:
: 15 ployed inthe lnterEacial polymerization technique.
In a preferred embodiment of this invention, the liquid of the dis-persed droplet phase is an organic liquid, more preferably, an organic liquid whlch is to be encapsulated by interfacial polycondensation :~ while the continuous phase or second liquid is an aqueous medium more preferably containing at least one ingredlent that will ultimately react to become part of the capsule wall.
In the practice of the preerred form o this invé~fnion, a controlbd amount of one reactive component of an anionic emulsifier is dissolved ln one of the liquid phases, and the remaining reactive component or compon~ts dissolvedin the other liquid phase. When the phases are ~ ~ . , .
~ ~4~
; 4~83 are brought together w~th only mild a~itation, sufficiently stabill~ed droplets are rapLdly produced. For example, in the preparation of encapsulated products wherein the contlnuous phase is aqueous, a fatty acid is dissolved in the organlc phase and a base is diqsolved in the aqueous phase.
Preferably, the base is dissolved in the aqueous phase before the addition of the organic phase thereto, although the base may be added to the aqueous phase simultaneously with the organic phase. On conventional reactor mixing, stabilized droplets are efficiently formed because the stabilizer is produced where it is needed, i.e., at the interface.
The amount of emulsifier to be formed varies with the system and the particle size desired, but for systems employing aqueous media as the continuous phase, it is typically in the range of 0.05~ based on the weight of the dispersed phase. Thus, sufficient amounts of each of the emulsifier precursors are employed to provide the desired amount of in situ ~ormed emulsifying agent.
This new process eliminates the need for special mixing equipment and lengthy mixing times for preparing stabilizer solutions, and also eliminates the need to employ high shear mixing devices for dispersing the droplets. In actual practice several hours can be saved per batch of encapsulated material, the process control requirements are greatly simplified, and frequently, much higher-solids dispersions can be prepared. The eEEicient technique of this invention lends itself especially well to continous production.
In the preferred practice of this invention any oE a wide variety of surfactants or emulsifiers can be formed at thè phase interface, for example, carboxylates, sulfonates, sulfates, and phosphates in which the cation is either a metal or an amine. Obviously, the choice will depend on the particular overall system and will be made so as not to adversely interfere with the capsule-wall forming reaction. Most commonly, the cation precursor component for the emulslfier will be a metal. Particularly useful are the - 5 - ;
' ~0~ 83 alkali metals including Na ~3, K ~and Li , wlth Na6~being especially preferred.
A wlde variety of anions are applicable and are well kno~l to those famillar with dispers:Lon technology.
The choice of anion or catlon or mixtures thereof, will depend on the particular system oE interest. C16-C18 aliphatic fatty acids, for example, oleic, stearic and palmitic acids, have been found to be generally useful as the anionic precusors component for the emulsifier, and oleic acid is .
preferred for the preferred embodiment.
A good review of anionic, cationic and non-ionic surfactants is -~
presented in the Kirk-Othmer "Encyclopedia of Chemical Technology", 2nd Ed., Vol. 19, pp. 512-566. `
As more specific preferred examples of polymerization reactions to which the present encapsulation process is applicable, the following may be mentioned: Diamines or polyamines in the aqueous phase and diacid or polyacid chlorides in the organic phase are reacted to yield capsule walls consisting oE p~y rides. Di~mLnes or polya-ine~ in '.
~; ~ ''; ~ . "
'~ ' ' ~;''' -, f~
the aqucous liquid and l~lsc~lloroforlrlatos or polychloroEormates in the organlc liquid afford a polyuretll~ne capsule skin. Agaln, diamines or polyamines in l:he aqlleous medium antl disulfonyl or polysulfonyl chlorides in the ~rganic solv~nt pr~uce a pc>lysulfonamide skin. Like-wise, with diamines or polyamines in the aqueous phase, a polyurea capsule wall is obtainable when the organic phase contains phosgene (chloroformyl chloride) which, for convenience oE classification herein, may be considered to have the properties of a difunctional acid chloride, i. e., in some correspondence with diacid chlorides such as sebacoyl chloride. Also, diamines or polyamine s in the aqueous media and diisocyanates or polyisocyanates in the organic solvents produce a polyurea sl~in.
With diols or polyols in the aqueous liquid, various other con-densate resins are achieved. Thus with diacid or polyacid chlorides in the organic phase, polyesters are produced to constitute the capsule wall. When bischloroformatesJ polychloroformates or phosgene are used in the organic liquid the capsule skins are polycarbonates. Not only are there other complementary intermediates which react to orm polycondensates in a direct manner useful in the interfacial poly-condensation proaess~ enaapsul~tlon, but various mixtures of inter-mediates may be employed in either or both liquid phases. For oxampl0, mixtures of diols and diamines in the aqueous liquid and also or alter-natively, mixtures oE acid chlorides and chloroformates in the organic solvent are useful to achieve corresponding condensation copolymers.
A primary example of a condensation copolymer is one formed with a . , "
7l~3 difunctional acid chlorlde, e. g. sebacoyl dichloride; a multifunctional amine, e.g. ethylene diamine/diethylene triamine mixture; and a polyeunctional isocyanate, e.g. polymethylene polyphenyllsocyanate. This copolymer has been referred to as a crosslinked polyamide-polyurea (amide-urea copolymer). Also, diols or polyols in the aqueous liquid and diisocyanates or polyisocyanates in the organic liquid produce a polyurethane skin. ;?
In the system for interfacial polymerization wherein a stabilized ;~
dispersion of droplets of a first liquic1 to be encapsulated is ~ormed within a continuous phase of a second liquid, the two liquids should be immiscible, at least one of them being an organic liquid, and the other preferably an aqueous medium. A wide variety of organic solvents may be employed, e.g., as will be recognized to be appropriate for the selected intermediate or intermediates.
Some examples, are mineral oil, xylene, benzene, carbon disulfide, carbon tetrachloride, pentane, and the like, as well as liquids which may not only serve the function of a solvent for the polymer-forming reactant but may also have a reactant function to be availed of after formation of the capsules.
Instances of such reactant liquids which in the encapsulation steps of the invention serve simply the function of an organic solvent are styrene and di-t-butyl peroxide.
,~.
Examples of difunctional acid-derived compounds are sebacoyl chloride, ethylene bischloroformate, phosgene, terephthaloyl chloride, adipoyl chloride, azelaoyl chloride (azelaic acid chloride)S dodecanedioic acld chloride, dimer acid chloride, and l,3-benzenesulfonyl dichloride.
. . .
; ' ' ' ' ' ' ....
, .
~'~
- 8 - i;
, . '; '.
'' ' ' ' '~
.... .. , , . . ,. . . , . , .: . . . .
Polyf~lnctlonal compl~unds o~ tllis type are exempllfied by trlmcsoyl chloricle; 1, 2, ~, 5 benzene tcl:raacid chloride; l, 3, 5-~_nzene l:risulfonyl chlc>ride; trlmer acid chloride; citrlc acid chloride; and l, 3, 5-benæene trischloroformate. Intermediates similarly useful in the organic phase also include diisocyanates and polyisocyanates,for example,toluene diisocyanate, hexamethylene diisocyanaie and polymethylene polyphenylisocyanate, e. ~., P~lPI~The Upj ohn Co. ) .
As examples of suitable diols for use as intermediates in an aqueous phase, there may be named bisphenol A[2, 2bis (p, p'dihydrox~
diphenyl) propane], hydroquinone, resorcinol, catechol, and various glycols such as ethylene glycol, pentanediol, hexanediol, dodecanediol :
and the like. Polyfunctional alcohols e. g. triols, are exernplified by pyrogallol (l, 2, 3-benzenetriol) phloroglucinol dihydrate, pentaerythritol, trimethylolpropane, 1, 4, 9,10-tetrahydroxyanthracene, 3, 4-dihydroxyan-thranol, diresorcinol, tetrahydroxyquinone and antralin.
Suitable diami.as and polyamlnes, usually selected as water soluble per se or in water soluble salt form, where such reactant is to be included in an a~ueous phase, are: substances eEfective as difunc-tional reactants (contributing no significant cross~linking effect of themselves~, namely ethylene diamine, phenylene dlamine, toluene diamine, hexamethylene diamine, cliçthYlere triiamine. pipera~in~^ an~J
substances effecti~e as polyfunctional reactants (contributing cross-linking effect, and usèful alone or at least in combination with another amine of at least dif~ctional character), namelyl, 3, 5-benzene triamine trihydrochloride, 2, 4, 6-triamino toluene trihydrochloride, tetraethylene ': `
? ~ &~ 9 . .
, . ' ,,,,'.
4t~83 pentamine, pentaethylene hexamine, polyethylene-imine, 1,3,6-triaminonaph-thalene, 3S4,5-triamino-1,2,4-trla~ole, melamine, and 1,4,5,8-tetraminosnthra-quinone. To t~e extent that the reactant to be used in the aqueous phase may be insoluble or have limited solubil~ty in water per se, it may be used in a form or with appropriate cooperating substances to render it, in effect, soluble. Thus, certain amines may be used in hydrochloride or other salt form, while a compound of little or no water solubility (by itself), such as bisphenol A, may be used in a composition appropriately ad~usted as with alkali, to afford such solubility.
Interfacial polycondensation to form the capsule wall as shown in British Patent No. 1,371~179 provides a reac~ant amine by the hydrolysis of an isocyanate which reactant amine in turn reacts with a free isocyanate to form the polyurea enclosure (capsule wall). After the dispersion establishing droplets of the organic phase within a continuous liquid phase has been accompllshed, and preferably with moderate agitation of the dispersion~ the formation of the polyurea capsule wall around the dispersed droplets i9 brought about by heating thecontinuous liquid phase or by introducing a catalytic amount of a basic amine or other agent capable of increasing the rate of isocyanate hydrolysis, and optionally in addition, ad~usting the pH
of the dispersion, thereby effecting the desired condensation reaction at ~:
the interface between the droplets and the continous phase.
~ The organic polyisocyanates contemplated in the above described process are those members of the aromatic polyisocyanate class which ~'~ '',' , , ................................. . . . . . .
7~
includes the aron~atic diisocyanates, the aliphatic diisocyanate class, high moiecular weigllt linear aliphatic diisocyanates and the isocyanate prepolymers.
Representative of the aromatic diisocyanates and other polyisocyanates are the following:
l-Chloro - 2,4 - phenylene diisocyanate m-Phenylene diisocyanate p-Phenylene diisocyanate 4,4'-Methylene bis (phenyl isocyanate)
2,4 - Tolylene diisocyanate 2,6-Tolylene diisocyanate 60% 2,4 Tolylene diisocyanate and 40% 2,6 isomer of Tolylene diisocyanate 80% 2,4 Tolylene diisocyanate and 20% 2,6 isomer of Tolylene diisocyanate
3,3' - Dimethyl - 4,4'-biphenylene diisocyanate
4,4' - Methylene bis (2-methylphenyl isocyanate) 3,3' - Dimethoxy - 4,4' - biphenylene diisocyanate 2,2', 5,5' - Tetramethyl - 4,4' biphenylene diisocyanate Polymethylene polyphenylisocyanate (PAPI) By forming a stabilizing agent in situ at the interface of the discontinuous and continuous phases, the production of encapsulated products by the interfacial polymerization process, as exemplified by USP's 3,429,827, 3,575,882, 3,577,515 and British 1,371,179, is greatly simplified.
Surprisingly, the addition of the same amount of the preEormed stabllizer to either phase gives totally unsatisfactory results, usually . .' , , , ' , ',, re~Ult~ J lna co~r5c slurry of capc;ule wall polymer.
.~ 1 The capsulcs formed using the techniqucs of th~ invcntion have the same utility as those produced by thc prior art methods.
The following examples serve to Illustrate the method of this invention.
EXAMPLE I
To a 250 mL Erlenmeyer flask equipped with a magnetic stirrer is charged 90 g. deionized wa~er, 0. 95 g. sodium carbonate, 0. 93 g, ethylene diamine, and 1. 07 g. diethylene triamine. Then, with rapid, agitation, a premixed blend of 10 g. xylene, 1. 5 g, sebacoyl chloride, 0. 5 g. polymethylene polyphenylisocyanate, and 0.1 g. oleic acid is added. Capsule formation ls observed almost immediately; however, stirring to complete polymerization, is continued for two hours. Micro-.
scopic examination of the resultant slurry shows xylene-containing .
, capsules having an average diameter of ca, 25 microns.
EXAMPLE II
Using the procedure of Example I, the iolloY~ing reaction is per-formed. ~ mix oi:
90 g. delonized water 1. Sg. sodium hydroxide (50% aqueous) 0. 93g. ethylene diamine, and 1. 0 7g . diethylene triamine is prepared and to it the follo~ng pre-mix i9 added with agitation:
~: . ' .
~ 10 g. xylene :
~ 1. 5g, sebacoyl chloride . ~ , ' .
-- o ~OB4783 O. 5~. pol~7methylone polyphenol isbcyanate, and 0.1 g. palmitic acid, ~fter stirring for two hours~ the run is shut down and the product is examined. Complete encapsulation is observed microscopically;
S spheroids of (a, 50-microns average size are found. No xylene sepa-ration is evident. The slurry contains ca. 9. 5% encapsulated xylene by weight.
EXAMPLES III - XVIII
To a one liter resin flask iitted with stainless steel baffles and an agitator,is charged the ingredients of Part A. Then, with fairly i vigorous agitation, a pre-mix of the ingredients oE Part B is added to form a dispersion. A pre-mix of the ingredients o~ Part C is added, and the reactor c~ntents are stirred for two hours to aomplete the poly-merization. Finally, Part D is added for post-stabilization and pH
adjustment.
The individual recipes are given in Table I, and results and comments are presented in Table II
....
.
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~ ~ ~ It ~ rr ~ O ~ ~ ~Pl ~ ~ O ~
P' ~ ~ p J P ~ P ~ p~~ rt 3 ~ ~ .Q I' P.
î~ o (D p ~D ~D ~ O O , ID p ~
~_ ~ ~ ~Po g ~ ~ ~ 'C C UC~ ~E; ~ `;
P ~ p t~ ~ ~ h g ~ O- P ~ p o~
fD P o p~ o 1'- 1~ (D ~ ~ O ~I) O~
O 1- n n P~ p ~ ~ ~ ~ - ~ O ~D ~ o~o ~ ~1 It ~ ~ p~ D o ~ P rt ~ (D Y îT~ ~ ~ ~
O~ P~ ~D 1~ ~ ,u.
~_ I W IDO rh ~ ::~ O 1~ 0~ D P O
o ~ ~ E. ~ ,, tD ~:: P ~, ~q _ P~O n O ID ~ n C ~ ~n ~ ~ r~ ~ Ep~ 'q p p ph ~
~ I_ o P~ /D p~ ~ i, . '~ ~* ~ 0~ - '~.', ;'~, . \ ~ . ~":
. ,'" ' .' _ . 1_ _ _ ~3 I I ~ I O I I I I I I I ~ I O I I I I I ~ H ~;
1~ o o~ ~o o a~ O . ~ ~ H 1 ~_. __ _____. H Pl 1--~ ~11 q~ ~9 $ a~ o o $ ~1~ g C H
. ~_~ ~i- ' ' ~ ~ `
n I~n I III III~n~Ig IIIII~IO C . ' '~.
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__y_Co -~- ~F _.~- ' ~ ~ C
~ I .; O I I I I 1. 1 1 1 ~n I I I ~ ~ I I I I ~ ~
I I ~ o cr~ ~o o . I ~ c _I . . C I I I ~ .n I C I ~ I I I l l Ci~ H
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Surprisingly, the addition of the same amount of the preEormed stabllizer to either phase gives totally unsatisfactory results, usually . .' , , , ' , ',, re~Ult~ J lna co~r5c slurry of capc;ule wall polymer.
.~ 1 The capsulcs formed using the techniqucs of th~ invcntion have the same utility as those produced by thc prior art methods.
The following examples serve to Illustrate the method of this invention.
EXAMPLE I
To a 250 mL Erlenmeyer flask equipped with a magnetic stirrer is charged 90 g. deionized wa~er, 0. 95 g. sodium carbonate, 0. 93 g, ethylene diamine, and 1. 07 g. diethylene triamine. Then, with rapid, agitation, a premixed blend of 10 g. xylene, 1. 5 g, sebacoyl chloride, 0. 5 g. polymethylene polyphenylisocyanate, and 0.1 g. oleic acid is added. Capsule formation ls observed almost immediately; however, stirring to complete polymerization, is continued for two hours. Micro-.
scopic examination of the resultant slurry shows xylene-containing .
, capsules having an average diameter of ca, 25 microns.
EXAMPLE II
Using the procedure of Example I, the iolloY~ing reaction is per-formed. ~ mix oi:
90 g. delonized water 1. Sg. sodium hydroxide (50% aqueous) 0. 93g. ethylene diamine, and 1. 0 7g . diethylene triamine is prepared and to it the follo~ng pre-mix i9 added with agitation:
~: . ' .
~ 10 g. xylene :
~ 1. 5g, sebacoyl chloride . ~ , ' .
-- o ~OB4783 O. 5~. pol~7methylone polyphenol isbcyanate, and 0.1 g. palmitic acid, ~fter stirring for two hours~ the run is shut down and the product is examined. Complete encapsulation is observed microscopically;
S spheroids of (a, 50-microns average size are found. No xylene sepa-ration is evident. The slurry contains ca. 9. 5% encapsulated xylene by weight.
EXAMPLES III - XVIII
To a one liter resin flask iitted with stainless steel baffles and an agitator,is charged the ingredients of Part A. Then, with fairly i vigorous agitation, a pre-mix of the ingredients oE Part B is added to form a dispersion. A pre-mix of the ingredients o~ Part C is added, and the reactor c~ntents are stirred for two hours to aomplete the poly-merization. Finally, Part D is added for post-stabilization and pH
adjustment.
The individual recipes are given in Table I, and results and comments are presented in Table II
....
.
' ., . ' , ' .
: ~ : :
. ~ ~, .
.~ . , .
:' . ' , ' . :' '7~3 .
~, _ _ _ o~a p ~ o IJ- ~ ~D I O ~ , o (D ~ ~ O a~ o P
~ ~ ~ It ~ rr ~ O ~ ~ ~Pl ~ ~ O ~
P' ~ ~ p J P ~ P ~ p~~ rt 3 ~ ~ .Q I' P.
î~ o (D p ~D ~D ~ O O , ID p ~
~_ ~ ~ ~Po g ~ ~ ~ 'C C UC~ ~E; ~ `;
P ~ p t~ ~ ~ h g ~ O- P ~ p o~
fD P o p~ o 1'- 1~ (D ~ ~ O ~I) O~
O 1- n n P~ p ~ ~ ~ ~ - ~ O ~D ~ o~o ~ ~1 It ~ ~ p~ D o ~ P rt ~ (D Y îT~ ~ ~ ~
O~ P~ ~D 1~ ~ ,u.
~_ I W IDO rh ~ ::~ O 1~ 0~ D P O
o ~ ~ E. ~ ,, tD ~:: P ~, ~q _ P~O n O ID ~ n C ~ ~n ~ ~ r~ ~ Ep~ 'q p p ph ~
~ I_ o P~ /D p~ ~ i, . '~ ~* ~ 0~ - '~.', ;'~, . \ ~ . ~":
. ,'" ' .' _ . 1_ _ _ ~3 I I ~ I O I I I I I I I ~ I O I I I I I ~ H ~;
1~ o o~ ~o o a~ O . ~ ~ H 1 ~_. __ _____. H Pl 1--~ ~11 q~ ~9 $ a~ o o $ ~1~ g C H
. ~_~ ~i- ' ' ~ ~ `
n I~n I III III~n~Ig IIIII~IO C . ' '~.
~ ~ ~Jl I H CO ~n I I O I C
. _ ~ . .
: ~ . I 1~ ~n l l OI I I I ~ I O . ~ C :
~ ~ Ul ~/1 0~ Jl O ~Jl O H
,~___ .. Ul _ ~ IJ . ~ ' C .~ , 00 Ul l.n I I I I I I i`~ . . O~ ~Jl O H
_ _ ~Vl IJ7, __ . _ H
I ....... t- l I I 'I I I ' I I Ul ~ I I I I I I ~ ~ t~! E
u~ oo ~ 11 . i~ ~11 0 W ~
~C~ . . ___ 11~_ ~ w ~
.----~i;F I I I ~ li --I H
, C~CJ~ ~O C O ~ W ~
I 1_ l l 1 I I I I I . I O I I I I I 1, ~. H
Ul ~ n C O ~J~ ~JI 0 ~n O H
. . l O IJI ~11 1- W
It!~ _. _, C0 ~n ~ C O H
O1--I ~n`~JI g I I I I 1~ ~0 1 O O H
__y_Co -~- ~F _.~- ' ~ ~ C
~ I .; O I I I I 1. 1 1 1 ~n I I I ~ ~ I I I I ~ ~
I I ~ o cr~ ~o o . I ~ c _I . . C I I I ~ .n I C I ~ I I I l l Ci~ H
_ . I I O I . C I I I I H I I I ~n I ¦ . ~. C I
* ~ ~ ._ __ ~. ~ . ._ ~ . ' ' I_ . `. C ~.~
I V, Vl I I II I I I I Vl V~ O I )-- I I I I O H ~ .
: . H
. . _ _ .~ . .
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. ~
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~: ~ ~:
' ~: : ~ ~
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Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for encapsulating products within a capsule polymer wall by an interfacial polymerization procedure wherein a stabilized dispersion of droplets of a first liquid to be encapsulated is formed within a continuous phase of a second liquid, the improvement which comprises incorporating a precursor of an emulsifying agent for said dispersion in said first liquid, and then mixing said first liquid into said second liquid to form said droplets within a continuous liquid phase, said second liquid having incorporated therein a compo-nent reactive with said precursor for forming said emulsifying agent whereby said emulsifying agent is formed in situ, said precursor and component reactive therewith incorporated in said first and second li-quids in amounts sufficient to provide an amount of emulsifying agent sufficient to improve the stability of said dispersion.
2. The process of Claim 1 wherein the component reactive with said precursor has been incorporated in said second liquid prior to mixing said first liquid into said second liquid.
3. The process of Claim 1 wherein said first liquid is an organic liquid containing a polycondensate-forming intermediate for forming capsule walls about said droplets.
4. The process of Claim 3 wherein said second liquid is an aqueous liquid.
5. The process of Claim 4 wherein said precursor and component reactive therewith are selected to form an anionic emulsifying agent.
6. The process of Claim 4 wherein said precursor and compo-nent reactive therewith are selected to form an alkali metal salt of an aliphatic fatty acid having from 16 to 18 carbon atoms.
7. The process of Claim 5 wherein said polycondensate-forming intermediate is an organic polyisocyanate.
8. The process of Claim 5 wherein said second liquid contains a polycondensate-forming intermediate complementary to the polyconden-sate-forming intermediate in said first liquid.
9. The process of Claim 8 wherein the polycondensate-forming intermediate is selected to form a polymer from the group consisting of polyamide, polyurea, polyester, polycarbonate, polysulfonamide and polyurethane.
10, The process of Claim 8 wherein the polycondensate-forming intermediate is selected to form a crosslinked amide-urea copolymer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US68977576A | 1976-05-25 | 1976-05-25 | |
| US689,775 | 1976-05-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1084783A true CA1084783A (en) | 1980-09-02 |
Family
ID=24769849
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA278,422A Expired CA1084783A (en) | 1976-05-25 | 1977-05-13 | Process for encapsulation by interfacial polymerization |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS52148579A (en) |
| BE (1) | BE854984A (en) |
| CA (1) | CA1084783A (en) |
| DE (1) | DE2722973A1 (en) |
| FR (1) | FR2352586A1 (en) |
| GB (1) | GB1543454A (en) |
| IT (1) | IT1078859B (en) |
| MX (1) | MX145889A (en) |
| NL (1) | NL7705740A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4384975A (en) * | 1980-06-13 | 1983-05-24 | Sandoz, Inc. | Process for preparation of microspheres |
| AU547532B2 (en) * | 1980-08-20 | 1985-10-24 | Kureha Kagaku Kogyo K.K. | Microcapsule |
| JPS59166966A (en) * | 1983-03-14 | 1984-09-20 | Fuji Photo Film Co Ltd | Production of capsule toner |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE717134A (en) * | 1968-08-05 | 1968-12-27 | ||
| BE741741A (en) * | 1968-12-17 | 1970-04-16 | Microencapsulation | |
| US4001140A (en) * | 1974-07-10 | 1977-01-04 | Ncr Corporation | Capsule manufacture |
-
1977
- 1977-05-13 CA CA278,422A patent/CA1084783A/en not_active Expired
- 1977-05-18 GB GB2093277A patent/GB1543454A/en not_active Expired
- 1977-05-20 DE DE19772722973 patent/DE2722973A1/en not_active Withdrawn
- 1977-05-23 FR FR7715729A patent/FR2352586A1/en active Granted
- 1977-05-24 JP JP5949077A patent/JPS52148579A/en active Pending
- 1977-05-24 BE BE177860A patent/BE854984A/en unknown
- 1977-05-24 IT IT4954077A patent/IT1078859B/en active
- 1977-05-25 NL NL7705740A patent/NL7705740A/en not_active Application Discontinuation
- 1977-05-30 MX MX16917977A patent/MX145889A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| FR2352586B1 (en) | 1981-04-30 |
| IT1078859B (en) | 1985-05-08 |
| JPS52148579A (en) | 1977-12-09 |
| BE854984A (en) | 1977-09-16 |
| NL7705740A (en) | 1977-11-29 |
| FR2352586A1 (en) | 1977-12-23 |
| GB1543454A (en) | 1979-04-04 |
| DE2722973A1 (en) | 1977-12-08 |
| MX145889A (en) | 1982-04-19 |
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