AU641846B2 - In-situ polymerization process for producing epoxy microcapsules - Google Patents

Description

P/Oil1 2815191 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

-S

4

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: IN-SITU POLYMERIZATION MICRcCAPSULES.

PROCESS FOR PRODUCING EPOXY The following statement is a full description of this invention, Including the best mnethod of performing It known to US IN-SITU POLYMERIZATION PROCESS FOR PRODUCING EPOXY MICROCAPSULES Background of the Invention Field of the Invention The present invention relates to microcapsules and methods of microencapsulating a core of fill material. The resulting microcapsules are adaptable to a variety of applications, but are particularly for use in carbonless copying systems.

Description of the Prior Art Microcapsules generally comprise a core of fill material surrounded by a wall or shell of polymeric material. The fill material may be either gaseous, liquid, or solid and may be composed of a single substance, a solution, a suspension or a mixture of substances. The wall surrounding the core of fill material acts to isolate the fill material from the external environment. When it is desirable to release the fill material, the capsule wall may be ruptured to thereby introduce the fill material into its surroundings. Generally, microcapsules comprise separate and discrete capsules, thus the fill material is enveloped within the generally continuous polymeric walls of a microcapsule.

4< A process for the production of microcapsules using coacervation is disclosed in U.S. Patent No. 4,228,031 to Iwasaki et al. A process is described for making impermeable microcapsules comprising )preparing an aqueous dispersion of microcapsules each having a capsule wall. The capsule wall is a coacervate of a cationic polyamine-epoxy resin/anionic colloid.

An electrolyte is added to dehydrate the wall. The coacervate wall contains as high as 80% water. Preferably, dehydration of the microcapsules is carried out to such an extent that each of the microcapsules is deformed into a hollow ball form.

Coacervation has a number of disadvantages. As "the properties of natural colloids are not standardized, coacervation conditions such as temperature and pH-value have to be continually adjusted. Accordingly, the process cannot be carried out continuously. Also, as a result of agglomeration, microcapsules with an undesirably wide particle size distribution are obtained.

This technology does not relate, except by way of background, to in-situ formation of polymeric microcapsule walls as disclosed in the instant invention.

There are several known processes for the production of microcapsules by interfacial polymerization. Generally, these processes use a system of two phases. One phase is a discontinuous phase which is used to form the core of the microcapsules. This phase contains, in solution, one or two substances capable of wall formation, which are insoluble in the continuous phase. The continuous phase contains the other substance, which is necessary to react and form polymeric walls.

2 Generally, the second reactant should have some solubility partition coefficient) in the discontinuous phase, 'n order to effectively migrate from the continuous phase to react at the interface. A polymerization reaction takes place at the interface between the two phases resulting in a shell surrounding the core material.

One disadvantage common to these processes lies in the fact that, after the formation of a first extremely thin capsule membrane, mutual contact between the wall-forming compounds may be made difficult or even impossible. The result of this is that both the core material and also the aqueous phase remain contaminated by unreacted material, thus making it more difficult to adjust the thickness of the capsule wall.

U.S. Patent No. 4,496,509 to Chao describes a process for forming microcapsules using two organic-in-aqueous emulsions, each containing at least one oil soluble reactive compound that will react to form polymeric microcapsule walls. Microencapsulation is obtained by mixing the two organic-in-aqueous emulsions for a time and temperature sufficient to permit the emulsified organic droplets of each emulsion to collide with one another. Collision of two or more emulsions droplets causes the emulsified droplets to exchange at least a portion of their contents.

U.S. Patent No. 4,626,471 to Chao describes a process for insitu polymerization of microcapsule walls by forming a solution containing a polyfunctional amine, an epoxy resin selected from the group of methylolated bisphenol A based epoxy resins, and an organic solvent. The resulting solution is then emulsified or 3 J0N dispersed to form droplets within a substantially continuous aqueous phase. The amine compound polymerizes the epoxy resin and the polymeric reaction product migrates outward to the interface of the organic droplet and the substantially aqueous phase. This polymerization and migration eventually results in the formation of a microcapsule wall at the interface.

U.S. Patent 3,432,327 to Kan et al. describes a process for forming capsules by interfacial polymerization of an epoxy resin and an amine in hydrophilic and hydrophobic liquids.

U.S. Patent No. 4,120,518 to Baatz et al. discloses a process for forming microcapsules containing a solution of color formers and having polyurea shells. The process describes an oil-in-water emulsion with a polycarbodimide incorporated in the oil phase, which will react with an amine contained within the aqueous phase to form microcapsules at the phase interface.

U.S. Patent No. 3,981,821 to Kiritani et al. describes a process for forming microcapsules by emulsifying a hydrophobic liquid, to be encapsulated as a dispersed phase, in a hydrophilic liquid immiscible therewith as a continuous phase. At least one capsule wall-forming substance present in the hydrophilic liquid continuous phase is then polymerized and the resulting polymer is deposited around the hydrophobic liquid droplets from the outside.

A substance in the continuous phases that has reactivity with at least one of the wall-forming substances promotes the deposition of the polymer, resulting in the continuous phase being present in the droplets of the hydrophobic liquid prior to the step of emulsifying the hydrophobic liquid.

4 U.S. Patent 4,317,743 to Chang discloses a process for forming microcapsules by forming an oil-in-water emulsion. The oil phase comprises materials to be encapsulated and isocyanatoamidine product as the wall-forming material in a hydrophobic liquid. The aqueous phase contains a water-soluble emulsifier which acts solely as the protective colloid. The isocyanatoamidine product is then hydrolyzed at the interface of each oil droplet into a strong solid capsule wall which is insoluble in either the oil or water.

U.S. Patent No. 4,138,362 to Vassiliades et al. describes a process for forming pressure-rupturable, oil-containing microcapsules by admixing a water-immiscible, oily material containing an oil soluble, non-polymeric polyfunctional isocyanate cross-linking agent, and an aqueous solution of a polymeric emulsifying agent in the form of a water soluble polymer containing recurring -NH 2 or =NH groups or a water soluble natural gum containing recurring hydroxy groups. An oil-in-water emulsion is formed and a solid capsule wall is formed by the cross-linking of the emulsifying agent by the isocyanate.

There are several disadvantages associated with the above processes of making microcapsules, due to the rapid reaction of the two wall-forming materials during the emulsification step.

The size and shape of the microcapsules varies over a wide range, making control of the microcapsule size and size distribution difficult if not impossible.

5 1 U.S. Patent No. 4,356,108 to Schwab et al. describes a process for forming microcapsules by interfacial condensation of a polyfunctional amine and a polyfunctional wall forming material reactable with the amine. The process comprises emulsifying a mixture of a hydrophobic phase which includes an oil, a chromogenic material and an oil soluble polyfunctional wallforming material, and a hydrophilic phase, which includes water, a water soluble emulsifying agent and a water soluble salt of the desired polyfunctional amine. The amine salt may be formed in- LO situ in the hydrophilic phase before the emulsification step.

After emulsification, sufficient base is added to the emulsion to convert the polyfunctional amine salt to a polyfunctional amine and to neutralize acid formed during subsequent condensation reactions, thus initiating the reaction of the polyfunctional amine with the oil soluble polyfunctional wall forming material and thus forming microcapsule walls around the droplets of the hydrophobic phase. The masked amine used in Schwab's patent, which discloses an interfacial process, is a water soluble salt.

It cannot be incorporated into an oil core phase for use in insitu polymerization processes.

Patent No. 4,428,983 to Nehen et al. describes a process for forming microcapsules by in-situ polymerization in which a stabilized dispersion of droplets of a first liquid to be encapsulated or a stabilized dispersion of solid particles to be encapsulated is formed in a continuous phase of a second liquid.

One of the two capsule wall-forming reaction components is present in free form and contains at least two isocyanate groups while the 6 other of the two capsule wall-forming reaction components is present in reversibly blocked form and contains at least two reversibly blocked functional groups. The functional groups are deblocked by water and contain at least two NH groups or one NH group and one OH group. Both reaction components are present in the first or second liquid without reacting with one another. The reaction component which is present in reversibly blocked form is deblocked by means of water present in the first or second liquid and then reacts with the reaction component present in free form to form a polymeric capsule wall. The droplets of the first liquid or the solid particles are thus encapsulated in small capsules consisting of polymeric material.

Summary of the Invention It is an object cf the present invention to provide a process for the formation of epoxy microcapsules having uniform wall thickness and capsule size distribution. In-situ polymerization of the microcapsules by the process of the present invention results in microcapsules highly suitable for use in carbonless copying systems.

In the process according to the present invention, microcapsules are produced by in-situ polymerization. Two wallforming components, an epoxy and a ketimine, are provided within a first liquid. The first liquid preferably contains a colorless dye precursor or precursor mixture in an organic carrier solvent.

A stable dispersion of droplets of the first liquid is formed in a continuous phase of a second liquid. An oil/water emulsion is 7 1 formed in the.presence of an emulsifier, of which water is the main ingredient. Droplet sizes are determined by the emulsifier type and its concentration, emulsification speed, time and temperature. The ketimine, which is incorporated together with an epoxy resin in the oil core discontinuous phase, is hydrolyzed at the surface of the droplets by contact with tne aqueous continuous phase to release a reactive amine. The released reactive amine then reacts with the epoxy resin to form polymeric capsule walls at the interface between the droplets of the first liquid and the aqueous continuous phase. The droplets of the first liquid are encapsulated in capsules of epoxy.

Additional objects and advantages of the invention will become apparent in the description which follows.

1Bifeoriptien e-th Figre 1 i.s .ar ning electr n r s .h o a microcapsule dispersion of Versami K-13, Araldite 6060 and KMC oil at magnifications of 200X an 1000X.

Figure 2 is a scanning e ctron microscope photograph of a microcapsule dispersion of ersamine K-11 and Araldite 3337 at magnifications of 200X aid 1000X.

Figure 3 is a sc ning electron microscope photograph of a microcapsule dispe ion of Versamine K-il and Araldite 6060 at magnifications o 200X and 1000X.

Figure 4 is a scanning electron microscope photograph of a microcapsu dispersion of Versamine K-ll and Araldite 3336 at '7)A -8-nfti f 0 1n.

^8 1 rFigure 5e i.-a 5canning l ctron mic L-ehotograph f a microcapsule dispersion of Versami -12, Araldite 3337 and KMC/ Ucane at magnifications of OX and 1000X.

Figure 6 is canning electron microscope photograph of a microca e dispersion of Versamine K-13, Araldite 3337 and KMC/ Detailed Description of the Preferred Embodiments The present invention relates to the microencapsulation of a LO core mateial in an epoxy microcapsule wall. The process employs two phases, a discontinuous phase that forms the core materials to be encapsulated and a continuous phase. Within the core material phase is contained two wall-forming components, an epoxy resin and a ketimine. Upon hydrolysis of the ketimine, an amine is formed which is reactive with the epoxy resin.

Epoxy resins which are suitable for use in accordance with the present invention 4re the aromatic resins that contain multifunctional epoxide groups. For example, Bisphenol A and Bisphenol F based glycidyl ethers, phenol and cresol based novolac resins, 1,1,2,2-(p-hydroxyphenol) ethane based glycidyl ether, 4glycidyloxy-N,N-di-glycidyl aniline, methylolated bisphenol A based resins, methylenedianiline based resins, etc., are all useful in this invention. Preferably, bisphenol A and bisphenol F epoxy resins are used.

9 1 The bisphenol A resins suitable for use in the instant invention preferably have an equivalent weight or WPE (weight per epoxy) in the range of 175 to 500. Examples of suitable bi.-phenol A resins include Araldite 6005, 6010, 6020 and 6060, all from Ciba Geigy.

The bisphenol F resins suitable for use in the instant invention preferably have an equivalent weight or WPE in the range of 150-300. Examples of suitable bisphenol F resins include Araldite 281, 306, 3336 and 3337, all from Ciba Geigy.

Ketimines are amine-ketone adducts which are unreactive with epoxy resin. Upon release of amine through hydrolysis with water, the compound becomes reactive with epoxy resin. Ketimines which are suitable for use in accordance with the present invention correspond to the general formula:

H

2

NRNH

2 R'COR" R'R"C=NRN=CR'R" wherein R is a lower alkyl radical, such as methyl, ethyl, propyl, isopropyl, isobutyl, etc.

Preferably, ketimine% of the following formulas are used, R R I I C N (CH 2 2 N C (II) I I

CH

3

CH

3 R H R C N (CH 2 2 N (CH 2 2 N C (III)

CH

3 CH 3 10 1 R

R

I

I

C N (CH 2 N (CH 2 2 N C

CH

3

/CH

2 CH 3 CH OH CH2 0 6 wherein R is an isobutyl radical.

Other aliphatic amines, such as hexamethylenediamine, dipropylenetriamine and triethylenetetramine can be reacted with methyl isobutyl ketone (MIBK) to form other ketimines which are suitable for use in the present invention. Examples of suitable ketimines are Versamine K-11, K-12 and K-13, all from Henkel Chemicals. Versamine K-li, K-12 and K-13 correspond to Formulas II, III and IV, respectively.

The rate of the reaction can be increased by the addition of a small amount of accelerator. Accelerators which are suitable for use in the present invention include accelerator 399 (from Texaco Chemicals), DMP-10 and DMP-30 (both from Rohm Haas).

The discontinuous phase contains at least one organic carrier solvent which contains at least one substance to be encapsulated, for example, a colorless dye or a colorless dye precursor. The organic carrier solvent should be capable of dissolving or suspending the dye precursor. Typical organic carrier solvents include alkyl naphthalenes, diarylalkanes, alkylated biphenyls, terphenyls, linear alkyl benzenes and phthalate esters.

11 In connection with carbonless copy systems, the fill material to be encapsulated within the inventive microcapsules will usually be a colorless dye precursor such as crystal violet lactone (CVL) benzoylleucomethylene blue (BLMB), rhodamine lactam, ptoluenesulfinate of Michler's hydrol (PTSMH), or any of the various chromogenic compounds that are capable of changing from a colorless to a colored form on contact with reactive substances, such as phenolic resins or reactive clays.

Generally, once the substance to be encapsulated the colorless dye precursor or precursor mixture) is dissolved in a carrier organic solvent, the solution can be mixed with the epoxy resin and the ketimine compound. To this solution can be added an emulsification agent which aids in the formation of a oil-in-water emulsion. Typical emulsification agents include partially hydrolyzed polyvinyl acetate, such as Vinol 523 and 540 from Air Products and Chemicals; sodium naphthalene sulfonate/formaldehyde condensate, such as Tamol L from Rohm Haas Chemicals; gelatins, starch and cellulose derivatives such as carboxylated starch or cellulose, hydroxyethyl cellulose, polyacrylamide, polystyrenesulfonate, etc. Suitable emulsification agents are those surface active chemicals which contain both hydrophilic and hydrophobic groups in the same molecules. In an oil/water emulsion, these molecules adsorb at the oil-water interface, preventing the oil droplets from collapsing into each other.

Particle size of the oil droplets can be adjusted by emulsification agent concentration, speed, temperature and time of agitation. Particle sizes in the range of 1-10 microns are most 12 1 suitable for carbonless paper applications. Capsules useful for other applications may need adjustment of their sizes. During emulsification, the oil droplets are in a state of intermediate contact with water molecules. Consequently, a reactive amine is released due to the hydrolysis of the ketimine. The newly released reactive amino compound reacts with a nearby epoxy resin molecule in-situ. Upon completion of the reaction, microcapsules having epoxy walls and an encapsulated core material in an organic carrier solvent are formed. Warming of the emulsion slurry to about 60 to 95 0 C, preferably to about 70-85 0 C, accelerates the curing rate.

The present invention and some of its advantages are further illustrated, but not limited, by the following examples.

EXAMPLE 1 63 parts of a 6% colorless dye in KMC oil were mixed with 8..11 parts of Araldite 6060, 0.97 parts of Versamine K-ll and 0.20 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523 (95:5) solution. The slurry was heated to 75 0 C for four hours. Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about 5 microns. The capsule slurry was coated as a CB sheet. When it was written against a phenolic resin coated receiving sheet, a clear black image was obtained.

13 1 EXAMPLE 2 63 parts of a 6% colorless dye in KMC oil were mixed with 6.87 parts of Araldite 3336, 2.20 parts of Versamine K-11 and 0.20 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523 (95:5) solution. The slurry was heated to 75 0 C for four hours. Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about 6 microns. The capsule slurry was coated as a CB sheet. When it was written against a phenolic resin LO coated receiving sheet, a clear black image was obtained.

EXAMPLE 3 63 parts of a 6% colorless dye in KMC oil were mixed with parts of Araldite 3337, 2.07 parts of Versamine K-11 and 0.20 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523 (95:5) solution. The slurry was heated to 75 0 C for four hours. Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about 4 microns. The capsule slurry was coated as a CB sheet. When it was written against a phenolic resin coated receiving sheet, a clear black image was obtained.

EXAMPLE 4 63 parts of a 6% colorless dye in Suresol 330/Ucane 11 (50:50) solution were mixed with 6.98 parts of Araldite 6010, 2.09 parts of Versamine K-12 and 0.21 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vino 14 1 523 (95:5) solution. The slurry was heated to 75 0 C for four hours. Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about microns. The capsule slurry was overcoated onto a phenolic resin coated receiving sheet. Under writing pressure, a clear black image was obtained.

EXAMPLE 63 parts of a 6% colorless dye in Suresol 330/Ucane 11 (50:50) solution were mixed with 8.1 parts of Araldite 6060, 0.98 parts of Versamine K-12 and 0.1 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523 (95:5) solution. The slurry was heated to 75 0 C for four hours. Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about microns. The capsule slurry was overcoated onto a phenolic resin coated receiving sheet. Under writing pressure, a clear black image was obtained.

EXAMPLE 6 63 parts of a 6% colorless dye in Suresol 330/Ucane 11 (50:50) solution were mixed with 6.86 parts of Araldite 281, 2.22 parts of Versamine K-12 and 0.22 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vin.c 523 (95:5) solution. The slurry was heated to 75 0 C for four hours. Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about 4 15 1 microns. The capsule slurry was overcoated onto a phenolic resin coated receiving sheet. Under writing pressure, a clear black image was obtained.

EXAMPLE 7 63 parts of a 6% colorless dye in KMC/Ucane 11 (50:50) solution were mixed with 6.86 parts of Araldite 3336, 2.24 parts of Versamine K-12 and 0.22 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523 (95:5) solution. The slurry was heated to 75 0 C for four hours.

Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about 4 microns. The capsule slurry was overcoated onto a phenolic resin coated receiving sheet. Under writing pressure, a clear black image was obtained.

EXAMPLE 8 63 parts of a 6% colorless dye in Suresol 330/Ucane 11 (50:50) solution were mixed with 6.47 parts of Araldite 6010, 2.16 parts of Versamine K-13 and 0.2 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523 solution. The slurry was heated to 75 0 C for four hours. Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about microns. The capsule slurry was overcoated J ,o a phenolic resin coated receiving sheet. Under writing pressure, a clear black image was obtained.

16 1 EXAMPLE 9 63 parts of a 6% colorless dye in Suresol 330/Ucane 11 (50:50) solution were mixed with 6.26 parts of Araldite 281, 2.82 parts of Versamine K-13 and 0.21 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523 (95:5) solution. The slurry was heated to 75°C for four hours. Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about microns. The capsule slurry was overcoated onto a phenolic resin coated receiving sheet. Under writing pressure, a clear black image was obtained.

EXAMPLE 63 parts of a 6% colorless dye in KMC/Ucane 11 (50:50) solution were mixed with 6.36 parts of Araldite 3337, 2.72 parts of Versamine K-13 and 0.2 parts of Accelerator 399. The mixture was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523 (95?5) solution. The slurry was heated to 75 0 C for four hours.

Under scanning electron microscope, spherical microcapsules were obtained. Average particle size was about 4 microns. The capsule slurry was overcoated onto a phenolic resin coated receiving sheet. Under writing pressure, a clear black image was obtained.

Although the present invention has been described in connection with the preferred embodiments, it is to be understood that modifications and variations may be resorted to without 17 departing from the spirit and scope of the invention. Such modifications are considered to be within the purview and scope of the invention and the appended claims.

18

Claims (8)

1. A process for producing microcapsules by in-situ polymerization comprising: providing two capsule wall-forming reaction components within a first liquid, wherein said reaction components are an epoxy resin and a ketimine; and forming a stable dispersion of droplets of said first liquid in an aqueous continuous phase of a second liquid; :herein said ketimine is hydrolyzed at the surface of the droplets by contact with said aqueous continuous phase to release a reactive amine, said reactive amine thereby contacting the epoxy resin to form polymeric capsule walls at the interface between the droplets of the first liquid and the aqueous continuous phase, the droplets of the first liquid being encapsulated in capsules of epoxy.

2. The process of claim 1, wherein said first liquid is an organic carrier solvent containing a colorless dye or precursor thereof.

3. The process of claim 1, wherein said first or second liquid further contains an accelerating agent.

4. The process of claim 1, wherein the epoxy resin is bisphenol A or bisphenol F based glycidyl ether resin. The process of claim 4, wherein the epoxy resin is bisphenol A based glycidyl ether resin. 19

6. The process of claim 5, wherein the bisphenol A based glycidyl ether resin has a weight per epoxy within the range of

175-500. 7. The process of claim 4, wherein the epoxy resin is bisphenol F based glycidyl ether resin. 8. The process of claim 7, wherein the bisphenol F based glycidyl ether resin has a weight per epoxy in the range of 150-

300. 9. The method of claim 1, further comprising heati-I said stable dispersion to 70-850 C to accelerate the curing rate of the epoxy. A process for forming microcapsules comprising; dissolving a colorless dye precursor or precursor mixture in an organic carrier solvent; mixing the resulting solution with an epoxy resin and a ketimine compound; emulsifying the resulting solution in the presence of an emulsification agent to form an oil-in-water emulsion; the oil droplets in the emulsion thereby coming into contact with water molecules to release a reactive amine through hydrolysis of the ketimine, said reactive amine then reacting with the epoxy resin to form microcapsules having epoxy walls. 11. The process of claim 10, wherein the microcapsules are 1-10 microns. 12. The process of claim 10, further comprising heating the emulsion to 70-85 0 C to accelerate the cure rate. 20 13. The process of claim 10, wherein the epoxy resin is bisphenol A or bisphenol F based glycidyl ether resin. 14. The process of claim 13, wherein the epoxy resin is bisphenol A based glycidyl ether resin. The process of claim 14, wherein the bisphenol A based glycidyl ether resin has a weight per epoxy within tY s range of 175-500. 16. The-process of claim 13, wherein the epoxy resin is bisphenol F based glycidyl ether resin. 17. The process of claim 16, wherein the bisphenol F based glycidyl ether resin has a weight per epoxy in the range of 150- 300. 18. A process of making microcapsules for use in carbonless paper comprising: incorporating a colorless dye or precursor thereof and a carrier solvent within a capsule member, wherein said capsule member is formed by reacting an epoxy resin together with a ketimine in the presence of said colorless dye, said carrier solvent and water. 19. The method of claim 18, wherein the epoxy resin is bisphenol A or bisphenol F based glycidyl ether resin. The method of claim 19, wherein the epoxy resin is bisphenol A based glycidyl ether resin. 21. The method of claim 20 wherein the bisphenol A based glycidyl ether resin has a weight per epoxy in the range of 175-

500. 21 22. The method of claim 19, wherein the epoxy resin is bisphenol F based glycidyl ether resin. 23. The method of claim 22, wherein the bisphenol F based glycidyl ether resin has a weight per epoxy in the range of 150- 300. 24. The method of claim 18, wherein the microcapsules are 1- microns in size. A process for producing microcapsules by ip-situ polymerization comprising: forming a stable dispersion of droplets of a first liquid in a continuous phase of a second liquid by emulsification, said dispersion containing two capsule wall-forming reaction components, which are an epoxy resin and a ketimine; introducing water to said dispersion to cause a reactive amine to be released by hydrolysis of the ketimine, said reactive amine contacting the epoxy resin to form polymeric capsule walls at the surface of the droplets of the first liquid, the droplets of the first liquid being encapsulated in capsules of epoxy. DATED THIS 10th February, 1992 MOORE BUSINESS FORMS, INC. WATERMARK PATENT TRADEMARK ATTORNEYS, 2nd Floor, The Atrium 290 Burwood Road, HAWTHORN. VICTORIA 312-. 22 ABSTRACT OF THE DISCLOSURE A process for producing microcapsules by contacting an epoxy resin with a ketimine in the presence of water. The ketimine and epoxy resin are provided in a stable dispersion of droplets of a first liquid in an aqueous continuous phase of a second liquid. The ketimine is hydrolyzed- at the surface of the droplets to release a reactive amine. The reactive amine contacts the epoxy resin to form polymeric capsule walls of epoxy at the interface between the two phases. The resultant microcapsules are suitable for use in carbonless copying systems. 23