PROCEDE DE POLYMERISATION IN SITU POUR LA PRODUCTION DE MICROCAPSULES D'EPOXYDE

IN-SITU POLYMERIZATION PROCESS FOR PRODUCING EPOXY MICROCAPSULES

Abrégé anglais

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.

Revendications

What is claimed is:
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;
wherein 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.
5. The process of claim 4, wherein the epoxy resin is
bisphenol A based glycidyl ether resin.
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63423-370
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 process of claim 1, further comprising heating said
stable dispersion to 70-85° C to accelerate the curing rate of the
epoxy.
10. 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 molecule 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°C to accelerate the cure rate.
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63423-370
13. The process of claim 10, wherein the epoxy resin s
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.
15. The process of claim 14, wherein the bisphenol A based
glycidyl ether resin has a weight per epoxy within the 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 process of claim 18, wherein the epoxy resin is
bisphenol A or bisphenol F based glycidyl ether resin.
20. The process of claim 19, wherein the epoxy resin is
bisphenol A based glycidyl ether resin.
21. The process of claim 20 wherein the bisphenol A based
glycidyl ether resin has a weight per epoxy in the range of 175-
500.
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63423-370
22. The process of claim 19, wherein the epoxy resin is
bisphenol F based glycidyl ether resin.
23. The process of claim 22, wherein the bisphenol F based
glycidyl ether resin has a weight per epoxy in the range of 150-
300.
24. The process of claim 18, wherein the microcapsules are 1-
10 microns in size.
25. A process for producing microcapsules by in-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.
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63423-370
26. The process of claim 1, wherein the epoxy resin is an
aromatic epoxy resin containing two or more epoxide groups and
having an equivalent weight of 175 to 500.
27. The process of any one of claims 1 to 26, wherein the
ketimine is a reaction product of (1) a ketone of the formula
R'-CO-R" with (2) an amine selected from the group consisting of
a diamine of the formula: H2N-R-NH2
(wherein R' and R" are each a lower alkyl and
R is (CH2)2, (CH2)2-NH-(CH2)2, <IMG>
or a residue of hexamethylenediamine), dipropylenetriamine and
triethylenetetramine.
28. The process of any one of claims 1 to 26, wherein the
ketimine is represented by the formula:
(II)
<IMG>
(III) or
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(IV)
<IMG>
(wherein R is an isobutyl radical).
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Description

20~98~1
IN-SITU POLYMERIZATION PROCESS FOR PRODUCING
~PO~Y MICROCAPSUL~S
Backqround of tho Inventlon
1 Pield of th~ Invention
The present invention relates to microcapsules and methods of
microencapsulating a core of fill material. The resulting
microcapeules are adaptable to a variety of applications, but are
particularly for u~e in carbonle s copying systemsO
Descri~tion of the Prior Art
Microcapsulec generally comprise a core of fill material
~urrounded by a wall or shell of polymeric material. The fill
material may be either gaseous, liquid, or ~olid and may be
composed of a ~ingle substance, a 301ution, a ~u~pen~ion or a
mixture of substance~. The wall ~urrounding the core of fill
material acts to i301ate the fill material from the external
environment. When :Lt i9 desirable to release the fill material,
tho capsule wall may be ruptured to thereby introduce the fill
material into its ~urrounding3. Generally, microcap3ules comprise
separate and discrete cap4ules, thuR the fill material i~
enveloped within the generally continuous polymeric walls of a
microcap~ule.
~, ~

20~9~51
1 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 contain~ as high a~ 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 o f disadvantages. As the
properties of natural colloids are not standardized, coacervation
conditions such as temperature and pH-value have to ba continually
ad~usted. Accordingly, the process cannot be carried out
lS continuously. A1YO, as a result of agglomeration, microcapsules
with an undesirably wide particle size di~tribution are obtained.
This technology doe~ not relate, except by way of background, to
in- itu formation of polymeric microcap~ule wall~ as disclosed in
the instant invention.
There are ~everal known proce~se~ for the production of
microcapsules by ln~erfacial polymerization. ~enerallyl these
procecses use a system of two phases. One phase is a
discontinuous phaso which i~ used to form the coro of the
microcap4ules. This ph~se contains, in solution, one or two
substances capable of wall formation, which are insoluble in the
continuous phase. The continuous phase contain~ the other
substance, which is nec2ssary ~o react and form polymaric walls.

20~98~
1 Generally, the second reactant should have some solubility (i.e.,
partition coefficient) in the discontinuous phase, in 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 i5 that
both the core material and also the aqueous phase remain
contaminatad by unreacted material, thus making it more difficult
to ad~ust the thickness of the capsule wall.
U.5. Patent No. 4,459,509 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 ~t le~st a portion of their contents.
U.S. Patent No. 4,625,471 to Chao describes a proceqs for in-
situ polymerization of microcapsule walls by forming 8 solution
containing a polyfunc~ional amLnel an epoxy resin selected from
the group of methylolated bisphenol A based epoxy resins, and an
organic ~olven~. ~he resulting solution i8 then emul~ified or
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20~9~
1 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 r0sults in the formation
of a microcapsule wall at the interfacs.
U.S. Patent 3,432,327 to Ran et al. describes a process for
forming capsules by int rfacial polymerization of a~ epoxy resin
and an amine in hydrophilic and hydrophobic liquid~.
U.S. Patent ~o. 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 de~cribe~ an oil-in-water
emulQion with a polycarbodimide incorporated in the oil phase,
which will react with an amine contained within the aqueous phase
to form microcapsuleq at the phase interface.
U.S. Patent No. 3,981,821 to Kiritani et al. describes a
proce~s 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
cap~ule wall-forming ~ubstance present in the hydrophilic liquid
continuous phase is then polymerized and the resultlng polymer is
deposited around the hydrophobic liquid droplets from the outside.
A ~ubstance in the continuous phase~ that ha~ reactivity with at
least one of the wall-forming sub4tance~ promote~ the deposition
of the polymer, resulting in the continuous pha~e being present in
the droplets of the hydrophobic liquid prior to the step of
emulsifyiny the hydrophobic liquid.

20~98~
1 U.S. Patent 4,317,743 to Chang disclose~ a process for
forming microcapsules by forming an oil-in-water emulsion. ~he
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.
10- U.S. Patent No. 4,138,362 to Vassiliades et al. describes a
process for forming pressure-rupturable, oil-containing
microcapsule~ by admixing a water-immi~cible, 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 ~ water soluble polymer
containing recurring -NH2 or =NH groups or a water soluble
natural gum containing recurring hydroxy groups. An oil-in^water
emulsion $s formed and a solid cspsule wall i~ formed by the
croYs-linking of the emulsifying agent by the isocyanate.
There are several disadvantages associatad with the above
proces~es of maklng microcapsules, due to the rapid reaction of
the two wall-forming materialR during the emulsification step.
The size and shape of the microcapsule3 varies over a wide range,
making control of the microcapsule size and size distribution
difficult if not impo3sible.
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20598~1
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 pha-~e which includes an oil, a
chromogenic material and an oil soluble polyfunctional wall-
forming material, and a hydrophilic phase, which includes water, a
water soluble emulsifying agent and a water ~oluble salt of the
desired polyfunctional amine. The amine salt may be formed in-
situ in the hydrophilic phase before the emulsification step.
After emul~ification, ~ufficient base is added to the emulsion to
convert the polyfunctional amine salt to a polyfunctional amine
and to neutralize acid formed during ~ub~equent condensation
reactions, thuY initiating the re~ction of the polyfunctional
amine with the oil soluble polyfunc~ional wall forming material
and thus forming microcapsule walls around the dropletc of the
hydrophobic phase. The maskad amine used in Schwab~ patent,
which disclose~ an interfacial proce3g~ i8 a water soluble salt.
It cannot be incorpor~tsd into an oil core pha~e for use in in-
situ polymerization procQs~e~.
U.S. Patent No. 4,428,983 to Nehen et ~1. de3cribes a process
for forming microcap~ulos by in-~itu polymeriz~tion in which a
stabilized dispersion of droplets of a fir~t liquid to be
encapsulated or a stabilized dispersion of solid particles to be
encapsulated iQ formed in a continuous pha~e of a second liquid.
One of the two capsule wall-forming reaction components is present
in free form and contains at lea~t two isocyanate group4 while the
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20~9~1
1 other of the two cap3ule 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
S qroup 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
1~ to form ~ 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 tha In~ention
It is an ob~ect of the present invent~on to provide a process
for the formation of epoxy microcapsules having uniform wall
thickneqs and capsule 8ize distribution. In-~itu polymerization
of the microcapsules by the process of the present invontion
results in microc~p~uleR highly suitable for usn in carbonless
copying sy-~tem~.
In the proceE~s according to the present invention,
microcap~ules sre produced by in-situ polymerization. Two wall-
forming components, ~n apoxy and a ~etimine, ara provided within a
first liquid. The fir~t liquid preferably contain~ a colorless
dye precur~or or precursor mixture in an organic carrier solvent.
A stable disper~ion of droplets of the fir-qt liquid iR formed in a
continuous phase of a second liquid. An oil/water emul~ion is
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~Q~8~1
3423-370
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, emulsifLcation speed, time and
temperature. The ketimine, which is incorporated together with an
epoxy r~sin in the oil core discentinuouR phase, is hydrolyzed at
the surface of the droplets by contact with the aqueous continuous
phase to release a reactive amine. The released reactive amine
then react~ with the epoxy resin to form polymeric capsule walls
at the interface between the droplets of the fixst liquid and the
aqueou~ continuous pha~e. The droplet-~ of the firqt liquid are
encapsulated in capsules of epoxy.
Additional ob~ects and advantages of the invention will
become apparent in the de~cription which follow~.
Brief D~scri~tion of the Drawinq~
Figura l i a scann~ng electron miCroQCOp~ photograph of a
microcapsule di~persion of Versamine K-13, Araldite 6060 and KMC
oil at magnific~tions of 200X and 1000X.
Figure 2 i~ a scanning electron microscope photograph of a
microcapsule dispersion of Versamine X-ll and Araldite 3337 at
magnification~ of 200X and 1000X.
Figure 3 19 ~I scannlng electron microscope photograph of d
microcapsule dlspersion of Versamine* K-ll and Araldite*6060 at
magnifications of 200X and l000X.
Figure 4 i~ a scanning electron microscope photograph of a
microcap~ule diqpersion of Ver~amine*X-ll and Araldite*3336 at
magnifications of 200X and 1000X.
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~0~9~1
1 Figure S is a scanning electron microscope photograph of a
microcapsule dispersion of Versamine K-12, Araldite 3337 and ~C/
Ucane at maqnifications of 200X and lOOOX.
Figure 6 is a scanning electron microscope photograph of a
microcapsule dispersion of Versamine K-13, Araldite 3337 and ~UC/
Ucane.
Detailed DeseriPtion of the Preferred Embodiments
The present invention relates to the microencapsulation of a
core material in an epoxy microcapsule wall. The process employs
two phases, a discontinuous phase tha~ forms the core materials to
be encapsulated and a continuous pha~e. Within the core material
phase i~ 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 are the aromatic resins that contain
multifunctional epoxide group~. For example, sisphenol A and
Bisphenol F ba~ed glycidyl ethers, phenol and cre~ol based novolac
re~ins, 1,1,2,2-(p-hydroxyphenol) ethane based glycidyl ether, ~-
glycidyloxy-N,N-di-glycidyl aniline, methylolated bisphenol A
based re~in~, methylenedianiline based resin~, etc., are all
useful in this invention. Preferably, bisphenol A and bisphenol
F epoxy resinY are used.
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~59~1
1 The bi~phenol A recin~ suitable for use in the instan
invention preferably have an equivalent weight or WPE (weight pe_
epoxy) in the range of 175 to 500. Examples of suitable bisphenol
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.
XetimineQ ara 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 3uitable for use in accordance with the present invention
correspond to the general formula:
H2NRNH2 + R'COR" -> R'R"C=NRN-CR'R"
wherein R iQ 2 lower alkyl radical, ~uch as methyl, ethyl,
propyl, isopropyl, i~obutyl, ètc.
Preferably, ketimines of the following formulas are used.
R R
C = N - (CH2)2 - N ~ C (II)
CH3 CH3
R H R
C a N - (CH2)2 - N ~ (CH2)2 ~ (III)
CH3 CH3
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20~851
1 R R
C = N - (CH2)2 - I ~ (CH2)2 ~ (IV)
CH3 ~ CH2 c~3
CH - OH
o
(~ .
wherein R is an isobutyl radical.
Other aliphatic amineR, such as hexamethylenediamine,
dipropylenetriamine and triethylenetetra~ine c~n 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-ll, ~-12 and R-13, all from Henkel
Chemicals. Versamine K-11, K-12 and X-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~ Acc~lerators which are suitable
for u~e in ths pre~ent in~entlon include accelerator 399 (from
Texaco chemicals)~ DMP-10 and DMP-30 (both from Rohm ~ Haas).
The discontiriuous phase contains at least one organic carrier
solvent which contains at least one substance to be encapsula~ed,
for example, a colorless dye or a colorles~ dye precur-~or. The
organic carrier sol~ent should be capable of dissolving or
~uspending the dye precursor. Typical orsanic carrier solvents
include alkyl naphthalene~, diarylalkane3, alkylated biphenyls,
terphenyl~, linear alkyl benzenes and phthalate ester~.

~2.0~51
63423-370
1 In COnnQction 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 (~LMB), rhodamine lactam, p-
S toluene~ulfinatQ of Michler's hydrol (PTSMH), or any of the
various chromogenic compounds that ara 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 ~ubstance to be encapsulated (i.e. the
colorless dye precur~or or precurRor mixture) i~ di~solved in a
carrier organic solvent, the solution can be mixed with the epoxy
res$n and the ketimine compound. To thls 001ution can be added an
emul~ification aqent which aids in the formation of a oil-in-water
emulsion. Typical emul~ification agents include partially
hydrolyzed polyvinyl acetate, such a~ Vinol 523 and 540 from Air
Products and Chemlcals; sodium naphthalene sulfonate/formaldehyde
condensate, such as Tamol~ L from Rohm & Haas Chemicals; gelatins,
starch and cellulose derivatives such as carboxylated starch or
celluloce, hydrcxyethyl cellulose, polyacrylamide,
polystyrQnesulfon~te, etc. Suitable emul~ification agents are
tho~e Rurface active chemical~ which contain both hydrophilic and
hydrophobic groups in the same molecules. In an oil/water
emulsion, thes~ molQcules adsorb at the oil-wat~r interface,
prevent$ng the oll droplet~ from collap~ing into each other.
Particle size of the o$1 droplet~ can be ad~usted by
emul~ification agent concentration, ~peed, temperature and time of
agitation. Particle size~ in the range of 1-10 microns are most
*
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20~98~1
1 suitable for çarbonless paper application~. Capsules useful for
other applications may need ad~ustment 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 95C, preferably to about 70-85C, 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 0.2~
parts of Accelerator 399. The mixture was emulsified in 130 parts
of a 3% aqueou~ Tamol L/Vinol 523 (95:5) ~olution. The slurry was
heated to 75C for four hours. Under 3canning electron
microscope, spherical microcapsules were obtained. Average
particle size was about 5 microns. The capsule slurry was coated
as a CB sheet. When it wa~ written against a phenolic resin
coated receiving sheet, a clear black image was obtzined.
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20598~1
63423-370
1 EXAMPL~ 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 ~-11 and 0.20
parts of Accelerator 399. The mixture was emulsified in 130 parts
of a 3~ aqueous Tamol LtVinol 523 (95:5) solution. The slurry was
heated to 75C for four hour~. Under scanning electron
microscope, spherical microcapsules were obtained. Average
particle size was about 6 microns. The capsule slurry was coated
as a C3 sheet. When it was written against a phenolic resin
coated receiving sheet, a clear black image was obtained.
, .
EXAMPLE 3
63 parts of a 63 colorless dye in KMC oil were mixed with 7.0
parts of Araldite 3337, 2.07 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) olution. The slurry was
heated to 75C for four hours. Under scanning electron
microscope, spherical microcapqules were obtained. Average
particle size was about 4 microns. The capsule ~lurry was coated
a9 a CL sheet. When it was written against a phenolic resin
coated receiving shcet, a clear black image was obtained.
E~AMPL~ 4
* *
63 parts of a 6~ colorless dye in Sure~ol 330/Ucane 11
(50s50) ~olution were mixed wlth 6.98 parts of Araldite 6010, 2.09
parts of Versamine X-12 and 0.21 part~ of Accelerator 399. The
mixture was emulsified in 130 parts of a 3~ aqueous Tamol L/Vi,sol
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2~5~8~
1 523 (95:5) solution. The slurry was heated to 75C for feur
hours. Under scanning electron microscope, spherical
microcapsules were obtained. Average particie size was about 5
microns. The capsule slurry was overcoated onto a phenolic resin
coated receiving sheet. Under writing pressure, a clear black
image was obtained.
EXAMPLE 5
63 parts of a 6% colorless dye in Suresol 330/Ucane 11
(50:s0) solution were mixed with 8.1 parts of Araldite 6060, 0.98
parts of versamine ~-12 and 0.1 parts of Accelerator 399. The
mixture was emul~ified in 130 parts of a 3~ aqueou-~ Tamol L/Vinol
523 (95:5) solution. The slurry was heated to 75C for four
hours. Under scanning electron microscope, spherical
microcapsules were obtained. Average particle size was about ~.5
microns. The cap~ule slurry was overcoated onto a phenolic resi~
coated receiving sheet. Under writing pressure, a clear black
image was obtained.
LXAMPLE 6
63 parts of a 6% colorless dye in Suresol 330/Ucane 11
(50:50) ~olution were mixed with 6.86 parts of Araldite 281, 2.22
parts of VerYamine X-12 and 0.22 parts of Accelerator 399. The
m$xture waq emulsified in 130 parts of a 3% aqueous Tamol L/Vi-.^l
523 (95:5) solution. The ~lurry wa~ heated to 75C for four
hours. Under scanning electron microscope, spherical
microcapsules were obtained. Average particle size was about
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~5~5~
1 microns. The capsule slurry was overcoated onto a phenoli~ -esin
coated receiving sheet. Under writing pressure, a clear bla-k
image was obtained.
~A~PLE 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 mix.ure
was emulsified in 130 parts of a 3% aqueous Tamol L/Vinol 523
10- (95:5) solution. The slurry was heated to 75C for four hours.
Under qc~nning electron microscope, Ypherical microcapsuleq were
obtained. Average particle size was about 4 micron~. The capsule
slurry was overcoated onto a phenolic resin coated receiving
sheet. Under writing pressure, a clear black image was obtained.
~XA~PLE 8
63 parts of a 6~ colorless dye in Suresol 330/Ucane 11
t50:50) solution were mixed wlth 6.47 parts of Araldite 6010, 2.'6
parts of Versamine X-13 and 0.2 parts of Accelerator 399. The
mixture wa~ emulsified in 130 parts of a 3~ aqueou~ Tamol L/Vinol
523 t95:5) solution. The slurry was heated to 75C for four
hours. Under scanninq electron microscope, spherical
microcapsules were obtained. Average particle size was about ~.5
microns. The cap~ule slurry was overcoated onto a phenolic resln
coated receiving sheet. Under writing pre~sure, a clear blac~
image was obtained.
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2~8~
1 , EXAMPLE 9
63 parts of a 6~ colorless dye in Suresol 330/Ucane 11
(s0:50) solution were mixed with 6.26 parts of Araldite 281, 2.82
parts of versamine X-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 75C for four
hours. Under scanning electron microscope, spherical
microcapsules were obtained. Average particle size was about 5
microns. The capsule slurry was overcoated onto a phenolic resin
coated receiving sheet. Under writing pressure, a clear black
image was obtained.
EXAMPLE 10
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 R-13 and 0.2 parts of Accelerator 39g. The mixture
was emulsified in 130 parts of a 3~ aqueous Tamol L/Vinol 523
(95:5) qolution. The slurry was heated to 75C for four hours.
Under scanning electron microscope, spherlcal microcapsules were
obtained. Average particle size was about 4 microns. The capsule
slurry wa~ overcoated onto a phenolic resin coated receivinq
sheet. Under writing pressure, a clear black image was obtained.
Although the pre~ent invention has been described in
connection with the preferred embodiments, it is to be understood
that modlficstion~ and variations may be resorted to without
- 17 _

~OS98~1
departing from the spirit and scope of the invention. Such
modifications are considered to be within the purview and s~cpe o.
the inven~ion and the appended claims.
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