Toner manufacture using chain transfer polyesters

Polymeric electrophotographic toner and developer compositions are produced by methods including conventional as well as limited coalescence manufacturing techniques. The compositions are prepared by heating a diacid and a diol under conditions effective to form a chain transfer polyester, wherein either the diacid or the diol contain a disulfide moiety. The polyester is reacted with one or more vinyl monomers to form a block copolymer having polyester blocks linked to polyvinyl blocks by sulfide groups previously constituting the disulfide moiety. The block copolymer is reduced to a particulate form to a size suitable for use as an electrophotographic toner by conventional methods, evaporation limited coalescence, and suspension limited coalescence.

FIELD OF THE INVENTION 
This invention relates to polymeric toner and developer compositions and to 
a method for preparing the same. More particularly, this invention relates 
to a method for preparing toner particles by polymerization and other 
processes including limited coalescence techniques. 
BACKGROUND OF THE INVENTION 
Electrographic imaging processes and techniques have been extensively 
described in patents and other literature. These processes may take the 
form of electrophotographic techniques whereby a photoconductive 
insulating material is first electrostatically charged and then imagewise 
exposed with light to form a latent image. Exemplary electrophotographic 
imaging processes are disclosed in U.S. Pat. Nos. 2,221,776; 2,277,013; 
2,297,691; 2,357,809; 2,551,582; 2,825,814; 2,833,648; 3,220,324; 
3,220,831; 3,220,833 and many others. 
Generally, these processes have in common the steps of forming a latent 
electrostatic charge image on an insulating electrographic element. The 
electrostatic latent image is then rendered visible by treatment with an 
electrostatic developing composition or developer. 
Conventional developers include a carrier that can be either a 
triboelectrically chargeable, magnetic material such as iron filings, 
powdered iron or iron oxide, or a triboelectrically chargeable, 
non-magnetic salt such as sodium or potassium chloride. In addition to the 
carrier, electrostatic developers include a toner which is 
electrostatically attractable to the carrier. Useful toners include 
powdered pigment resins made from various thermoplastic and thermoset 
remains such as polyacrylates, polystyrene, poly(styrene-coacrylate), 
polyesters, phenolics and the like, and can contain colorants such as 
carbon black or organic pigments or dyes. Other additives such as charge 
control agents and surfactants can also be included in the toner 
formulation. 
Other examples of suitable toner compositions include: the polyester toner 
compositions of U.S. Pat. No. 4,140,644, the polyester toners having a 
p-hydroxybenzoic acid recurring unit of U.S. Pat. No. 4,446,302, the 
toners containing branched polyesters of U.S. Pat. No. 4,217,440, and the 
crosslinked styrene-acrylic toners and polyester toners of U.S. Pat. No. 
Re. 31,072, the phosphonium charge agents of U.S. Pat. No. 4,496,643, and 
the ammonium charge agents of U.S. Pat. Nos. 4,394,430, 4,323,634, and 
3,893,935. These toners can be used with plural component developers with 
the various carriers such as the magnetic carrier particles of U.S. Pat. 
No. 4,546,060 and the passivated carrier particles of U.S. Pat. No. 
4,310,611. 
Toner binder compositions can be manufactured by various methods. For 
example, conventional condensation polymerization, such as disclosed in 
U.S. Pat. No. 4,140,644 to Sandhu, et al., U.S. Pat. No. 4,217,440 to 
Barkey, and U.S. Pat. No. Re. 31,072 to Jadwin, et al, is often utilized. 
Toners can also be manufactured by a form of suspension polymerization 
known as "limited coalescence". Exemplary limited coalescence techniques 
are described, for example, in U.S. Pat. No. 4,833,060 to Nair, et al., 
U.S. Pat. No. 4,835,084 to Nair, et al., and U.S. Pat. No. 4,965,131 to 
Nair, et al. 
It is known that, depending on the type and nature of the resin(s) used, 
the resulting toner will exhibit varying physical properties. For example, 
the branched polyester toners disclosed in U.S. Pat. No. 4,217,440 exhibit 
such favorable properties as high glossability, good flow properties 
during fusing, easy dispersibility of pigment, higher grindability, and 
superior charging rates as positive toners. In addition, dyes are 
generally more soluble in branched polyesters and it is generally easier 
to disperse pigment in branched polyesters. Toners derived from the 
polymerization of vinyl monomers exhibit superior fuser reliability in 
that the toner particles do not accumulate or stick to the fusing roll as 
readily as typical polyester toner particles. 
Because the favorable properties exhibited (or not) by a toner are often a 
product of the toner binder's structure, there are few toner compositions 
that exhibit the properties of, for example, both a polyester and a 
polyvinyl toner. Therefore, there continues to be a need for toners 
exhibiting the various favorable properties outlined above that can be 
practicably made by known methods of toner manufacture. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a method of making a toner 
composition that exhibits the favorable properties of both polyester and 
polyvinyl toners is disclosed. The method of the present invention 
includes the steps of heating a diacid and a diol, wherein either the 
diacid or the diol contain a disulfide moiety, under conditions effective 
to form a polyester. The formed polyester, a "chain transfer" polyester, 
is then reacted with one or more vinyl monomers and an initiator under 
conditions effective to produce a block copolymer. The block copolymer 
comprises polyester blocks linked to polyvinyl blocks by sulfide groups 
that previously constituted the disulfide moiety. The block copolymer is 
reduced to a particulate form to a size suitable for use as an 
electrographic toner. Optionally, the polyester can be prepared with 
hydroxy group termination and subsequently chain extended with a disulfide 
diisocyanate to give a polyester-polyurethane containing disulfide 
moieties. The formed chain transfer polymer can then be reacted with one 
or more vinyl monomers and an initiator under conditions to produce a 
block copolymer. 
The block copolymers formed by the method of the present invention can be 
reduced to a particulate form by any known method. For example, 
appropriately sized particles can be produced by crushing and melt 
blending the crushed block copolymer, optionally with toner addenda, 
recrushing and coarse grinding the melt blended block copolymer, and 
pulverizing the recrushed and ground block copolymer blend to a 
particulate form to a size suitable for use as an electrographic toner. 
Another embodiment of the present method includes the block copolymer 
dissolved in an organic solvent, and toner addenda if desired, to form an 
organic phase. A stabilizer and, optionally, a promoter are mixed in a 
suspending liquid which is immiscible with the organic phase to form a 
continuous phase. Next, the organic and continuous phases are mixed under 
high shear to form a suspension of small droplets of the organic phase 
suspended in the continuous phase. The droplets, with stabilizer particles 
on their surfaces, coalesce to form larger droplets. The stabilizer 
particles limit this coalescence and define the size of the resultant 
droplets. The organic solvent is then removed from the droplets to form 
solidified polymeric toner particles. 
A third embodiment of the inventive method includes the steps of mixing the 
chain transfer polyester with a polymerizable vinyl monomer, an initiator, 
and any desired toner addenda to form an organic phase, followed by mixing 
a stabilizer, a buffering agent, and a promoter in a suspending liquid 
which is immiscible with the organic phase (i.e., the organic solvent, 
chain transfer polyester, vinyl monomer, and initiator) to form a 
continuous phase. The continuous and organic phases are mixed to form a 
suspension of small droplets of the organic phase suspended in the 
continuous phase. After the droplets coalesce as limited by the stablizer, 
the vinyl monomer is polymerized with the chain-transfer polyester under 
conditions effective to form particles of block copolymer having polyester 
blocks linked to polyvinyl blocks by sulfide groups that previously 
constituted the disulfide moiety. 
The method of the present invention provides polymeric toner particles that 
have the favorable properties and features of both polyesters and 
polyvinyls. In addition, the present method produces the 
polyester-polyvinyl toners using known methods of toner manufacture. Also, 
the present method provides a method of inserting highly reactive 
functional groups into copolyesters. Copolyesters containing these highly 
reactive functional groups can subsequently serve as substrates for 
further chemical reactions with various reagents to further modify the 
properties of the inventive polyester-polyvinyl block copolymers.

DETAILED DESCRIPTION OF THE INVENTION 
In accordance with the present invention, disclosed is a toner comprising a 
block copolymer that is the polymerization product of a vinyl monomer and 
a chain transfer polyester containing a disulfide linkage. The toner can 
be prepared by any of the known methods of toner manufacture. Three 
methods of toner manufacture are disclosed. The toner of the present 
invention can be prepared by conventional toner manufacture processes, 
such as disclosed in U.S. Pat. No. 4,140,644 to Sandhu, et al., U.S. Pat. 
No. 4,217,440 to Barkey, and U.S. Pat. No. Re. 31,072 to Jadwin, et al; by 
"evaporation limited coalescence" techniques described, for example, in 
U.S. Pat. No. 4,833,060 to Nair, et al.; or by suspension polymerization 
limited coalescence techniques disclosed in U.S. Pat. No. 4,835,084 to 
Nair, et al., and U.S. Pat. No. 4,965,131 to Nair, et al. 
The chain transfer polyester used to prepare the present toner is the 
product of a conventional two-stage polyesterification of a diacid or its 
derivative and a diol. Either the diacid or the diol must contain a 
disulfide moiety. Preferably, a polyfunctional modifier (i.e., a branching 
agent) is also included. As used throughout this specification and in the 
claims, the terms "diol", "diacid", "polyfunctional modifier", and "vinyl 
monomer" include a mixture of diols, a mixture of diacids, a mixture of 
polyfunctional modifiers, and a mixture of vinyl monomers, respectively. 
The polyesterification comprises the steps of heating the diol and the 
diacid in the presence of a catalyst (e.g., zinc acetate, antimony (III) 
oxide) in an inert atmosphere (e.g., an atmosphere such as nitrogen or 
argon) at about 180.degree. C. to about 280.degree. C., preferably at 
about 220.degree. C. to about 240.degree. C. Next, a vacuum is applied at 
the upper temperature range, preferably about 240.degree. C. to about 
260.degree. C., while continuing to heat the mixture to increase the 
molecular weight of the chain transfer polyester and to remove excess diol 
from the mixture. After the polyester has reached the appropriate 
molecular weight, the product of the polyesterification is cooled and 
isolated. Further details relating to two-stage polyesterification can be 
found in U.S. Pat. No. 4,140,644 to Sandhu et al. 
The chain transfer polyester produced is characterized by the addition of 
one or more ester-forming compounds (e.g., a diacid or a diol) containing 
a disulfide group to copolymerize the disulfide-containing monomer with 
the other polyester monomers and, thereby, introduce the disulfide groups 
into the main polyester chain. For example, one class of chain transfer 
polyester produced by a disulfide-containing diacid and diol (or vice 
versa) by the above-described process has the general formula: 
##STR1## 
wherein R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are the same or different 
and can include alkylene, arylene, arylenedialkylene and alkylene 
diarylene; and where x and y are mole fractions where x can range from 
0.01 to 100.00 and x+y=100. A preferred chain transfer polyester is one 
with the above general formula where R.sub.1, R.sub.2 and R.sub.3 are 
p-phenylene and where R.sub.4 is 2,2-dimethyl-1,3-propylene and x=1.0 to 
10.0. 
In mixing the diol, diacid, and polyfunctional modifier, generally at least 
about 1.1 moles of diol are present for each mole of diacid, and 
preferably from about 1.3 to about 2.0 moles of diol are present for each 
mole of diacid. The concentration of polyfunctional modifier used in the 
reaction mixture is the concentration required to obtain a desired ratio 
of linearization to branching at a given inherent viscosity. This 
concentration can be conveniently determined by routine experimentation 
known in the art. The concentration of polyfunctional modifier is also 
dependent on the number of functional groups in the modifier molecule. In 
general, the more functional groups a modifier has, the less modifier is 
needed to achieve a desired amount of branching. As is understood in the 
art, the chemical and physical properties of resulting branched polyesters 
can be varied by the use of different concentrations of polyfunctional 
modifier. For information regarding the use of polyfunctional modifiers, 
see U.S. Pat. No. Re. 31,072 to Jadwin et al. the disclosure of which is 
hereby incorporated by reference. Typically, the concentration of 
polyfunctional modifier is in the range of from about 0.001 to about 10 
mole percent, preferably from about 0.1 to about 5.0 mole percent, based 
on moles of diacid or glycol. 
Diols useful in the practice of this invention are typically dihydric 
alcohols or their functional derivatives, such as esters, which are 
capable of condensing with diacids or their functional derivatives to form 
condensation polymers. These diols can be represented, for example, by the 
formula R.sub.5 --O--R.sub.6 --O--R.sub.7 wherein each of R.sub.5 and 
R.sub.7 is hydrogen or alkylcarbonyl, preferably of from 2 to 7 carbon 
atoms. An alkylcarbonyl can be represented by the formula: 
##STR2## 
wherein R' is an alkyl preferably of from 1 to 6 carbon atoms. 
Representative alkylcarbonyl radicals are acetyl, propionyl, butyryl, etc. 
Most preferably, both R.sub.5 and R.sub.7 are hydrogen. 
R.sub.6 is an aliphatic, alicyclic or aromatic radical, preferably of 2 to 
12 carbon atoms and, most preferably, of 2 to 6 carbon atoms. Typical 
aliphatic, alicyclic, and aromatic radicals include alkylene, 
cycloalkylene, alkylidene, arylene, alkylidyne, alkylenearylene, 
alkylenecycloalkylene, alkylenebisarylene, cycloalkylenebisalkylene, 
arylenebisalkylene, alkylene-oxy-alkylene, 
alkylene-oxy-arylene-oxyalkylene, etc. Preferably, R.sub.6 is a 
hydrocarbon, such as alkylene, cycloalkylene, cycloalkylenebisalkylene or 
arylene. 
Exemplary diols useful in the practice of this invention include ethylene 
glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 
1,4-butanediol, 1,2-propanediol, 2-methyl-1,5-pentanediol, 
1,4-cyclohexanedimethanol, 1,4-bis(.beta.-hydroxyethoxy)benzene, 
norcamphanediols, 2,2,4,4-tetraalkylcyclobutane-1,3-diols, p-xylene 
glycol, hydroquinone, 4,4'-isopropylidenediphenol and corresponding alkyl 
esters thereof. Neopentyl glycol is especially useful in the process of 
the present invention. 
Diacids useful in the practice of this invention are typically dicarboxylic 
acids which are capable of condensing with diols or their functional 
derivatives to form condensation polymers. As used throughout this 
specification and in the claims, the term "diacid" includes functional 
derivatives of diacids such as esters, acid halides or anhydrides. Useful 
diacids can be represented, for example, by the formula: 
##STR3## 
wherein n is 0 or 1, and both R.sub.8 and R.sub.10 are hydroxy, halogen, 
(e.g. flouro, chloro, etc.), or alkoxy, preferably of from 1 to 12 carbon 
atoms, (e.g., methoxy, ethoxy, t-butoxy, etc.), or R.sub.8 and R.sub.10 
taken together form an oxy linkage. Most preferably, both R.sub.8 and 
R.sub.10 are hydroxy or alkoxy of 1 to 4 carbon atoms. 
R.sub.9 is an aliphatic, alicyclic or aromatic radical, preferably of 1 to 
12 carbon atoms. The definition of R.sub.6 given above applies here as 
well for R.sub.9. Preferably, R.sub.9 is hydrocarbon, such as alkylene, 
cycloalkylene or arylene. 
Exemplary diacids useful in the practice of this invention include sebacic 
acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, glutaric acid, 
succinic acid, carbonic acid, oxalic acid, azelaic acid, 
4-cyclohexene-1,2-dicarboxylic anhydride, 2-ethylsuberic acid, 
2,2,3,3-tetramethylsuccinic acid, 4,4'-bicyclohexyldicarboxylic acid, 
terephthalic acid, isophthalic acid, dibenzoic acid, 
bis(p-carboxyphenyl)methane, 2,6-naphthalenedicarboxylic acid, 
phenanthrene dicarboxylic acid, 4,4'-sulfonyldibenzoic acid and other 
similar acids including those disclosed, for example, in U.S. Pat. No. 
3,546,180 to Caldwell, U.S. Pat. No. 3,929,489 to Arcesi, et al., and U.S. 
Pat. No. 4,101,326 to Barkey. As noted above, ester, acid halide and 
anhydride derivatives of these acids are also useful in the practice of 
this invention. Dimethyl terephthalate is especially useful as the diacid 
in the method of the present invention. 
Polyfunctional modifiers useful in the practice of this invention are also 
known as branching agents. These modifiers contain three or more 
functional groups, such as hydroxyl or carboxyl. As used in this 
specification and in the claims, the terms "polycarboxylic acid", 
"polyol", and "hydroxy acid" also include functional equivalents, such as 
anhydrides and esters. Exemplary modifiers include polyols having three or 
more hydroxyl groups, polycarboxylic acids having three or more carboxyl 
groups and hydroxy acids having three or more total hydroxyl and carboxyl 
groups. 
Representative polyfunctional modifiers are trimesic acid, trimellitic 
acid, trimellitic anhydride, pyromellitic acid, butanetetracarboxylic 
acid, naphthalenetricarboxylic acids, cyclohexane-1,3,5-tricarboxylic 
acid, glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, 
1,2,6-hexanetriol, 1,3,5-trimethylolbenzene, malic acid, citric acid, 
3-hydroxyglutaric acid, 4-(.beta.-hydroxyethyl)phthalic acid, 
2,2-dihydroxymethylpropionic acid, 10,11-dihydroxyundecanoic acid, 
5-(2-hydroxyethoxy) isophthalic acid and others known in the art as 
disclosed, for example, in U.S. Pat. No. 4,013,624 to Hoeschele. Preferred 
polyfunctional modifiers include modifiers having three or four functional 
groups, such as trimellitic anhydride and penaterythritol, glycerol and 
trimethylolpropane. 
To form a chain transfer polyester containing a disulfide moiety, a 
reactant containing a disulfide moiety must be added to the reaction 
mixture. The disulfide-containing reactant can be, therefore, one or more 
of the diacids or the diols mixed to form a chain transfer polyester. The 
polydisulfide/polyester used as a chain transfer polyester in the present 
method should have a chain transfer constant sufficiently high to permit 
reasonable activity. Chain transfer constants can be determined by the 
method described in detail below at Example 10. The chain transfer 
polyesters used in the present invention should have a chain transfer 
constant of at least about 0.03. Preferably, the chain transfer polyester 
has a chain transfer constant of at least about 0.20. Any diacid or diol 
containing a disulfide group and exhibiting the requisite chain transfer 
constant upon polyesterification can be used in the present process. 
Examples of disulfides useful as the diacid in the method of the present 
invention include bis(4-carboxyphenyl) disulfide, 
bis(4-carbomethoxyphenyl) disulfide, 2,2'-dithio(dibenzoyl chloride), 
bis(4-chlorocarbonylphenyl) disulfide, dimethyl 4,4'-dithiodibutyrate, 
N,N'-bis(4-carbomethoxybenzoyl)-4,4'-dithiodianiline, bis(3-carboxyphenyl) 
disulfide, bis(2-carboxyphenyl) disulfide, 2,3'-dicarboxydiphenyl 
disulfide, 2,4'-dicarboxydiphenyl disulfide, 3,4'-dicarboxydiphenyl 
disulfide, bis(4-carboxymethylphenyl) disulfide, 
bis(3-carboxymethylphenyl) disulfide, bis(2-carboxymethylphenyl) 
disulfide, bis(10-carboxy-n-decyl) disulfide, 3,3'-dithiodipropionic acid, 
N,N'-bis(beta-carboxypropionyl)-4,4'-dithiodianiline, 
N,N'-bis(gamma-carboxybutyryl)-2,2'-dithiodianiline, 
bis(3-carboxy-1-methylpropyl) disulfide, 
bis(2,3-di-methoxy-6-carboxyphenyl) disulfide and 
bis(4-carboxy-methoxyphenyl) disulfides. 
Disulfides useful as the diol in the method of the present invention 
include bis(gamma-hydroxypropyl) disulfide, bis(6-hydroxyhexyl) disulfide, 
bis(6-hydroxy-2-naphthyl) disulfide, bis(4-hydroxyphenyl) disulfide, 
bis(4-hydroxymethylphenyl) disulfide, bis(2-hydroxymethylphenyl) 
disulfide, bis(4-(beta-hydroxyethyl)phenyl) disulfide, 
bis(3-(beta-hydroxyethyl)phenyl) disulfide, and the like. 
In addition, the disulfide used in the method of the present invention can 
be a trifunctional or tetrafunctional compound. If a tri- or 
tetra-functional disulfide is used it can serve as both the 
disulfide-contributing reactant and as a branching agent. Examples of tri- 
and tetra-functional disulfides useful in the method of the present 
invention include 
2,2',3-tricarboxydiphenyl disulfide, 
2,3,3'-tricarboxydiphenyl disulfide, 
2,3,4'-tricarboxydiphenyl disulfide, 
2,2',4-tricarboxydiphenyl disulfide, 
2,3',4-tricarboxydiphenyl disulfide, 
2,4,4'-tricarboxydiphenyl disulfide, 
2',3,4-tricarboxydiphenyl disulfide, 
3,3',4-tricarboxydiphenyl disulfide, 
3,3,4'-tricarboxydiphenyl disulfide, 
bis(2,4-dicarboxyphenyl) disulfide, 
bis(2,3-dicarboxyphenyl) disulfide, 
bis(3,4-dicarboxyphenyl) disulfide, 
2,2',3,4'-tetracarboxydiphenyl disulfide, 
2,3,3',4-tetracarboxydiphenyl disulfide, 
2,3',4,4'-tetracarboxydiphenyl disulfide. 
The chain transfer polyesters used to prepare the present toner can also be 
formed by chain extending a hydroxy terminated polyester with a 
diisocyanate containing a disulfide moiety. This method provides an 
additional route for introducing the chain transfer moiety (i.e., the 
disulfide group) to the polyester under advantageously mild conditions 
(e.g., temperatures in the range of about 50.degree.-100.degree. C.). The 
resulting chain transfer polyester in this case is a 
polyester-polyurethane copolymer. For example, the resultant chain 
transfer polyester derived from chain extending the hydroxy terminated 
polyester derived from neopentyl glycol and terephthalic acid with 
bis(4-isocyanatophenyl) disulfide is: 
##STR4## 
where a and b are values representing the average degree of 
polymerization. For the purposes of the present invention, the term 
"diacid" also includes diisocyanate disulfides as described above. Useful 
diisocyanate disulfides include bis(4-isocyantophenyl) disulfide, 
bis(3-isocyanatophenyl) disulfide, bis(isocyanatomethyl) disulfide, 
bis(2-isocyanatoethyl) disulfide, and bis(3-isocyanatopropyl) disulfide. 
Further details regarding the synthesis of a polyester-polyurethane chain 
transfer polyester as described above and its use can be found in Examples 
14-16, infra. 
Preferably, the disulfide used in the method of the present invention is 
selected from the group consisting of bis(4-carboxyphenyl) disulfide, 
bis(4-carbomethoxyphenyl) disulfide, bis(3-carboxyphenyl) disulfide, and 
bis(3-carbomethoxyphenyl) disulfide. An especially preferred disulfide is 
bis(4-carbomethoxyphenyl) disulfide. 
The chain transfer polyester prepared according to the method outlined 
above is used as one of the reactants in preparing the toners of the 
present invention. The chain transfer polyester is reacted with a vinyl 
monomer in the presence of an initiator to produce a block copolymer 
having polyester blocks and polyvinyl blocks which are linked together by 
sulfide groups previously constituting part of the disulfide moiety. A 
generic form of this reaction (I) is illustrated below. 
##STR5## 
Essentially, the disulfide moiety reacts with free radicals formed in the 
polymerization process and the vinyl monomer is inserted between the 
sulfur atoms. The block copolymer is then reduced to a particulate form to 
a size suitable for use as an electrographic toner. 
In one embodiment of the present method, a vinyl polymerization in the 
presence of a chain transfer polyester is performed and, subsequently, the 
resultant block copolymer is reduced to a particulate form to a size 
suitable for use as an electrographic toner. The vinyl polymerization is 
performed by dispersing the chain transfer polyester in a solvent such as 
tetrahydrofuran ("THF"), N,N-dimethylformamide ("DMF"), or 1,4-dioxane. 
For the purposes of this invention, the term disperse includes dissolving 
or suspending. The chain transfer polyester must be sufficiently dispersed 
to allow vinyl monomer which is added to the reaction solution to reach 
the disulfide moiety for insertion. Preferably, therefore, the chain 
transfer polyester is dissolved in an organic solvent. 
Vinyl monomer is added to the chain transfer polyester solution and the 
solution is purged with an inert gas such as nitrogen or argon. An 
initiator, such as azobisisobutyronitrile or a peroxide such as lauroyl 
peroxide, is next typically added to the solution of chain transfer 
polyester and vinyl monomer. The vinyl polymerization generally is 
performed at a temperature between about 20.degree. C. to about 
100.degree. C., depending on the initiator used. The temperature must be 
high enough to activate the initiator. For example, if the initiator is 
azobisisobutyronitrile, the reaction solution is maintained at a 
temperature of about 50.degree. C. to 60.degree. C. Other methods of 
generating radicals to carry out the vinyl polymerization in the absence 
of an initiator include exposure of the reaction solution to ultraviolet 
light or higher temperatures. Preferably, an initiator is used. The 
solution should be stirred under positive nitrogen pressure for 10-30 
hours, or any suitable time for the highest conversion of the vinyl 
monomer. 
The stirred solution is poured into a precipitating agent (e.g., 
cyclohexane) to precipitate a block copolymer. The precipitated block 
copolymer is rinsed with the precipitating agent and a ligroine (a 
combination of alkanes generally having a boiling point of about 
35.degree.-60.degree. C.) to remove residual amounts of the vinyl monomer 
and/or vinyl polymer and is then dried. The resulting block copolymer is 
preferably further purified by redissolving in a solvent such as methylene 
chloride and repeating the steps of precipitating, washing, and drying the 
block copolymer. 
In polymerizing the vinyl monomer in the presence of a chain transfer 
polyester, the degree of polymerization will be inversely proportional to 
the concentration of disulfide moiety. 
Typical vinyl monomers useful in the present process include substituted 
and unsubstituted styrenes (e.g., styrene, m+p-chloromethylstyrene and the 
like), vinyl naphthalene, ethylenically unsaturated mono-olefins (e.g., 
ethylene, propylene, butylene, isobutylene and the like), vinyl halides 
(e.g. vinyl chloride, vinyl bromide, vinyl fluoride and the like), vinyl 
esters (e.g., vinyl acetate, vinyl propionate, vinyl benzoate, vinyl 
butyrate and the like), esters of alpha-methylene aliphatic monocarboxylic 
acids (e.g., methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl 
acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, 
phenyl acrylate, methyl alpha-chloroacrylate, methyl methacrylate, ethyl 
methacrylate, butyl methacrylate and the like), acrylonitrile, 
methacrylonitrile, acrylamide, vinyl ethers (e.g., vinyl methyl ether, 
vinyl isobutyl ether, vinyl ethyl ether, and the like), vinyl ketones 
(e.g., vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone 
and the like), vinylidene halides (e.g., vinylidene chloride, vinylidene 
chlorofluoride and the like), N-vinyl compounds (e.g., N-vinylpyrrole, 
N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidine and the like), and 
mixtures thereof. 
Toner resins containing a relatively high percentage of styrene resins are 
typically preferred. The presence of a styrene resin is preferred because 
a greater degree of image definition is achieved with a given quantity of 
additive material. Further, denser images are obtained when at least about 
25 percent by weight (based on the total weight of resin in the toner) of 
a styrene resin is present in the toner. The styrene resin can be a 
homopolymer of styrene or styrene homologues or copolymers of styrene with 
other monomeric groups containing a single methylene group attached to a 
carbon atom by a double bond. Thus, typical monomeric materials which can 
be copolymerized with styrene by addition polymerization include 
substituted styrenes (e.g, m+p-chloromethylstyrene, and the like), vinyl 
naphthalene, ethylenically unsaturated mono-olefins (e.g., ethylene, 
propylene, butylene, isobutylene and the like), vinyl halides (e.g., vinyl 
chloride, vinyl bromide, vinyl fluoride and the like), vinyl esters (e.g., 
vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and the 
like), esters of alpha-methylene aliphatic monocarboxylic acids (e.g., 
methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 
dodecyl acrylate, methyl alpha-chloroacrylate, methyl methacrylate, ethyl 
methacrylate, butyl methacrylate and the like), acrylonitrile, 
methacrylonitrile, acrylamide, vinyl ethers (e.g., vinyl methyl ether, 
vinyl isobutyl ether, vinyl ethyl ether, and the like), vinyl ketones 
(e.g., vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone 
and the like), vinylidene halides (e.g., vinylidene chloride, vinylidene 
chlorofluoride and the like), N-vinyl compounds (e.g., N-vinylpyrrole, 
N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidine and the like), and 
mixtures thereof. The styrene resins can also be formed by the 
polymerization of mixtures of two or more of these unsaturated monomeric 
materials with a styrene monomer. Polystyrene and copolymers of styrene 
and n-butyl methylacrylate have been found to be particularly suitable for 
the method of the present invention as they result in polymers which are 
suitable for use as toner material as they possess good triboelectric and 
fusing properties. 
Preferably, a mix of vinyl monomers is polymerized and at least one of the 
vinyl monomers is a divinyl compound which will act as a cross-linking 
agent. Cross-linking results in a copolymer with increased hot melt 
strength. Typical crosslinking agents of the present invention include 
aromatic divinyl compounds (e.g., divinylbenzene, divinylnaphthalene or 
their derivatives), diacrylates and dimethacrylates (e.g., 
diethyleneglycol dimethacrylate, and diethyleneglycol diacrylate), and any 
other divinyl compounds (e.g., divinyl sulfide or divinyl sulfone 
compounds), or mixtures thereof. Suitable cross-linking agents and their 
use are also disclosed in U.S. Pat. No. Re. 31,072 to Jadwin, et al., the 
disclosure of which is hereby incorporated by reference. 
Upon polymerization, the precipitated block copolymer can be prepared for 
use as a toner by various methods known in the art. Essentially, the block 
copolymer is reduced to a particulate form and desired addenda must be 
added, melt compounded and reground to a size suitable for use as an 
electrophotographic toner. Particles having an average diameter between 
about 0.1 micron and about 100 microns are useful in electrographic 
processes, although present day office copy devices typically employ 
particles having an average diameter between about 1.0 and 30 microns. 
One method of preparing the block copolymer toner is conventional 
melt-blending. Melt-blending involves melting a crushed form of the block 
copolymer and mixing it with other necessary or desirable addenda 
including colorants such as dyes or pigments and charge control agents. 
The polymer can readily be melted on heated compounding rolls which are 
also useful to stir or otherwise blend the block copolymer and addenda to 
promote the complete intermixing of the various ingredients. After 
thorough blending, the mixture is cooled and solidified. The resultant 
solid mass is recrushed, coarsely ground, and then finely ground (i.e., 
pulverized). A variety of techniques can be used in addition to 
melt-blending. For example, spray-drying or spray-freeze drying techniques 
can provide useful methods for preparing toner particles. An example of a 
spray-drying technique can be found in U.S. Pat. No. 2,357,809 to Carlson. 
Spray-freeze drying is described in Product Licensing Index, volume 84, p. 
34-36, April, 1971. 
A variety of colorant materials selected from dyes and/or pigments are 
advantageously employed in the toner materials of the present invention. 
Colorants serve to color the toner and/or render it more visible. Suitable 
toner materials having the appropriate charging characteristics can be 
prepared without the use of a colorant material where it is desired to 
have a developed image of low optical opacity. In those instances where it 
is desired to utilize a colorant, the colorants used, can, in principle, 
be selected from virtually any of the compounds mentioned in the Colour 
Index, Volumes 1 and 2, Second Edition. 
Included among the vast number of useful colorants would be such materials 
as Hansa Yellow G (C.I. 11680), Nigrosine Spirit soluble (C.I. 50415) 
Chromogen Black ETOO (C.I. 45170), Solvent Black 3 (C.I. 26150), Fuchsine 
N. (C.I. 42510), C.I. Basic Blue 9 (C.I. 52015), etc. Carbon black is a 
particularly useful colorant. The amount of colorant added can vary over a 
wide range, for example, from about 1 to about 20 percent of the weight of 
the binder. Particularly good results are obtained when the amount is from 
about 2 to 10 percent. When no colorant is needed, the lower limit of 
concentration would be zero. 
Charge control agents suitable for use in toners are disclosed, for 
example, in U.S. Pat. Nos. 3,893,935; 4,079,014; 4,323,634; and British 
Patent Nos. 1,501,065 and 1,420,839. Charge control agents are generally 
employed in small quantities, such as from about 0.1 to about 3 weight 
percent, preferably from about 0.2 to about 1.5 weight percent, based on 
the weight of the toner. 
The block copolymer product of the vinyl polymerization can also be 
prepared for use as a toner by evaporation limited coalescence processes. 
The product of the vinyl polymerization (i.e., the block copolymer) is 
first dissolved in an organic solvent which is immiscible with the 
suspending medium to be used. The toner addenda (e.g., colorant, charge 
control agent) can be added to the block copolymer either before or during 
this solution step. 
The quantity of solvent is important in that the size of the particles thus 
prepared under given agitation conditions influences the size of the 
powder particles that result. It is generally the case that higher 
concentrations of block copolymer in the solvent produce larger particle 
size powder particles having a lower degree of shrinkage than that 
produced by lower concentrations of block copolymer in the same solvent. 
The concentration of the block copolymer in the solvent should be from 
about 1 to about 80 and preferably from about 2 to about 60% by weight. 
When preparing electrographic toner particles the concentration of block 
copolymer in solvent is generally maintained at from about 10 to about 35% 
by weight for a resin having a number average molecular weight of 10,000 
and a weight average molecular weight of 200,000. 
The block copolymer in the solvent is next introduced into a suspending 
medium under high shear. The suspending medium is immiscible with the 
organic solvent and contains a stabilizer and, optionally, a promoter 
which drives the stabilizer to the interface between the suspending medium 
and the block copolymer-solvent droplets formed by the agitation conducted 
on the system. To achieve this effect, it is generally desired to control 
the pH of the system at a value of from about 2 to about 7, preferably 
from about 3 to 6 and most preferably 4. The promoter should be present 
in an amount of about 1 to about 10 percent and preferably from about 2 to 
about 7 percent based on the weight of the block copolymer and solvent. 
The size of the droplets formed depends on the shearing action on the 
system plus the amount of dispersing agent employed. While any high shear 
type agitation device is applicable to the process of this invention, it 
is preferred that the block copolymer in solution be introduced into the 
suspending medium in a microfluidizer such as Model No. 110T produced by 
Microfluidics Manufacturing. In this device the droplets of block 
copolymer in solvent are dispersed and reduced in size in the suspending 
medium in a high shear agitation zone. Upon exiting this zone, the small 
droplets of the block copolymer in solution are suspended as a 
discontinuous phase in the continuous suspending medium. Each of the block 
copolymer-in-solution droplets are surrounded by particles of the solid 
dipersing agent which limits and controls both the size and size 
distribution of the block copolymer-solvent droplets. 
After exiting the microfluidizer, the particle size of the block 
copolymer-solvent droplets is established. The small droplets of block 
copolymer-solvent coalesce to form larger droplets, as limited by the 
stabilizer on the surface of the small block copolymer-solvent droplets. 
The solvent is next removed from the droplets by any suitable technique, 
such as, for example, heating the entire system to vaporize the solvent 
and thus remove it from the discontinuous phase droplets remaining in the 
suspension solution surrounded by the stabilizer particles. 
Next, should it be desired, the stabilizer can be removed from the surface 
of the polymer particles by any suitable technique such as dissolving in 
hydrogen fluoride or other fluoride ion or, preferably, by adding an 
alkaline agent such as potassium hydroxide to the aqueous phase containing 
the polymer particles. After dissolving the stabilizer, the polymer 
particles can be recovered by filtration and finally washed with water or 
other agents to remove any impurities from the surface of the particles. 
Any suitable solvent which will dissolve the polymer and is also immiscible 
with the suspension medium can be used as the organic solvent in the 
practice of this invention. For example, chloromethane, dichloromethane, 
ethyl acetate, methyl ethyl ketone, trichloromethane, carbon 
tetrachloride, trichloroethane, toluene, xylene, cyclohexanone, 
2-nitropropane and the like are all useful solvents. A particularly useful 
solvent is dichloromethane due to its high volatility rendering it readily 
removed from the discontinuous phase droplets by evaporation. 
Any suitable suspending medium which is immiscible with the solvent can be 
used in the practice of the present invention. Water is often utilized due 
to its immiscibility with many useful organic solvents. 
The stabilizers useful in evaporation limited coalescence include silica, 
alumina, barium sulfate, calcium sulfate, barium carbonate, calcium 
carbonate, and calcium phosphate. The silica-based stabilizers disclosed 
in U.S. Pat. No. 4,833,060 to Nair, et al. are preferred. A particularly 
useful silica stabilizer is sold by DuPont under the name Ludox.TM.. The 
silicon dioxide particles used as a stabilizer generally should have 
dimensions from about 0.001 .mu.m to about 1 .mu.m, preferably from about 
5 to 35 nanometers and most preferably from about 10-25 nanometers. The 
size and concentration of these particles controls and predetermines the 
size of the final toner particle. In general, as the concentration of 
stabilizer is increased, the size of the coalesced droplets will decrease. 
Other preferred stabilizers include the latex-based copolymer stabilizers 
disclosed in U.S. Pat. No. 4,965,131 to Nair et al. If a latex-based 
copolymer stabilizer is used, the stabilizer need not be removed from the 
toner particles and no promoter is required to form the block copolymer 
toner particles. 
Any suitable promoter which is soluble in the suspending medium and affects 
the hydrophilic/hydrophobic balance of the stabilizer in the suspension 
medium can be employed in order to drive the solid stabilizer to the 
interface between the block copolymer-solvent droplet and the suspension 
medium. Exemplary promoters include sulfonated polystyrenes, alginates, 
carboxymethyl cellulose, tetramethylammonium hydroxide or chloride, 
diethylaminoethyl methacrylate, water-soluble complex resinous amine 
condensation products such as the water soluble condensation products of 
diethanolamine and adipic acid (a particularly suitable promoter of this 
type is poly(adipic acid-co-methylaminoethanol)), water-soluble 
condensation products of ethylene oxide, urea and formaldehyde and 
polyethyleneimine. Other useful promoters include gelatin, glue, casein, 
albumin, gluten and the like. Nonionic materials such as methoxy cellulose 
can be used. Generally, the promoter is used in amounts of from about at 
least 0.2 and preferably 0.25 to about 0.6 parts per 100 parts of 
suspension medium. 
Particles having an average size of from 0.05 .mu.m to 100 .mu.m and, 
preferably, from 0.1 .mu.m to 60 .mu.m can be prepared by evaporation 
limited coalescence. Further details relating to evaporation limited 
coalescence can be found in U.S. Pat. No. 4,833,060 to Nair et al., and 
U.S. Pat. No. 4,965,131 to Nair et al., the disclosures of which are 
hereby incorporated by reference. 
The present method also allows advantageous cross-linking of toners 
prepared by evaporation limited coalescence techiques. Typically, toners 
prepared by evaporation LC processes are not cross-linked because the 
cross-linked polymer required in the discontinuous phase will not 
adequately disperse in currently available dispersants. In this 
embodiment, a vinyl monomer containing a reactive functional group is 
polymerized in the presence of a chain transfer polyester according to the 
present method. The resulting block co-polymer, when dissolved in the 
dispersant to form the discontinuous phase of the evaporation LC system, 
can then be cross-linked at the reactive sites by adding an agent which 
will react with the block copolymer at the reactive sites to provide 
advantageously cross-linked toner particles. Although it should be noted 
that this cross-linking may result in the early precipitation of the 
dissolved block copolymer, the resulting toner particles will have a 
suitably small particle size as determined by the degree of limited 
coalescence. Vinyl monomers having reactive functional groups useful in 
the present embodiment include: vinyl halides (e.g., m+p-vinylbenzyl 
chloride, p-vinylbenzyl chloride, m+p-(vinylbenzyl)-2-chloroethylsulfone, 
and the like); vinyl alcohols (e.g., p-vinylbenzyl alcohol, 
N,N-bis(2-hydroxyethyl)-N'-(alpha, 
alpha-dimethyl-m-isopropenylbenzyl)urea, N,N-bis(2-hydroxypropyl)-N'-(alph 
a, alpha-dimethyl-m-isopropenylbenzyl)urea, 
N-acryloyltris(hydroxymethyl)aminomethane, and the like); vinyl amines 
(e.g., 2-aminoethyl methacrylate hydrochloride, 
N-(3-aminopropyl)methacrylamide hydrochloride, 2-dimethylaminoethyl 
methacrylate, N-(p-vinylbenzyl)-N,N-dimethylamine, 4-vinylpyridine, 
2-vinylpyridine, and the like); and active methylene monomers such as 
2-acetoacetoxyethyl methacrylate. Further details regarding this 
embodiment of the present method are found in Examples 12 and 13, infra. 
Alternatively, toners derived from a disulfide-containing chain transfer 
polyester can be prepared by suspension polymerization, a limited 
coalescence process disclosed in, for example, U.S. Pat. No. 4,835,084 to 
Nair et al., the disclosure of which is hereby incorporated by reference. 
Suspension polymerization includes the steps of dispersing a chain 
transfer polyester, polymerizable vinyl monomers, and an initiator in a 
dispersant to form a dispersion phase which is immiscible with the 
suspending medium. Addenda (e.g., colorants, charge control agents), if 
added, are also added to this phase. Next, the dispersion phase is 
introduced to a suspending medium containing a stabilizer and a promotor 
which drives the stabilizer to the surface of the dispersion phase 
particles. This mixture is agitated under heavy shearing forces in order 
to reduce the size of the droplets. During this time, an equilibrium is 
reached and the size of the droplets is stablized by the action of the 
colloidal stabilizer in coating the surface of the droplets. 
Polymerization is then completed by heating and stirring the mixture in an 
inert atmosphere to a temperature sufficient to activate the initiator and 
for a time suitable to get a suitably high conversion of vinyl monomer. 
The vinyl polymerization results in droplets of block copolymer containing 
polyester blocks and polyvinyl blocks linked by sulfide groups previously 
constituting the disulfide moiety of the chain transfer polyester. The 
suspended polymer particles are then collected, by filtration for example, 
and, optionally, the stabilizer is removed from the surface of the toner 
particles by dissolving the stabilizer in hydrogen fluoride or another 
fluoride ion. Preferably, if a silica stabilizer is used, it is removed by 
adding an alkaline agent (e.g., potassium hydroxide) to the aqueous phase 
to raise the pH to at least about 12 while stirring the particles. 
Subsequent to raising the pH and removing the stabilizer, the polymer 
particles can be recovered by filtration and finally washed with water or 
other agents to remove any impurities from the surface of the particles. 
Latex-based copolymer stabilizers, if used, do not require a promoter and 
need not be removed from the surface of the block copolymer. Further 
details relating to suspension polymerization are disclosed in U.S. Pat. 
No. 4,835,084 to Nair et al., and U.S. Pat. No. 4,965,131 to Nair et al. 
The toner particles, once formed according to the method of the present 
invention, can be mixed with a carrier vehicle. The carrier vehicles, used 
to form suitable developer compositions, are selected from a variety of 
materials. Such materials include carrier core particles and core 
particles overcoated with a thin layer of film-forming resin. 
The carrier core materials can comprise conductive, non-conductive, 
magnetic, or non-magnetic materials. See, for example, U.S. Pat. Nos. 
3,850,663 and 3,970,571. Especially useful in magnetic brush development 
schemes are iron particles such as porous iron particles having oxidized 
surfaces, steel particles, and other "hard" or "soft" ferromagnetic 
materials such as gamma ferric oxides or ferrites, such as ferrites of 
barium, strontium, lead, magnesium, or aluminum. See, for example, U.S. 
Pat. Nos. 4,042,518, 4,478,925, and 4,546,060. 
As noted above, the carrier particles can be overcoated with a thin layer 
of a film-forming resin for the purpose of establishing the correct 
triboelectric relationship and charge level with the toner employed. 
Examples of suitable resins are described in U.S. Pat. Nos. 3,547,822, 
3,632,512, 3,795,618, 3,898,170, 4,545,060, 4,478,925, 4,076,857, and 
3,970,571. 
A typical developer composition containing the above-described toner and a 
carrier vehicle generally comprises from about 1 to about 20 percent, by 
weight, particulate toner particles and from about 80 to about 99 percent, 
by weight, carrier particles. Usually, the carrier particles are larger 
than the toner particles. Conventional carrier particles have a particle 
size on the order of from about 20 to about 1200 micrometers, generally 
about 30-300 micrometers. 
Alternatively, the toners of the present invention can be used in a single 
component developer, i.e., with no carrier particles. 
The invention will further be illustrated by the following examples. 
EXAMPLES 
In the Examples below, melting points and boiling points are uncorrected. 
Inherent viscosities ("IV") were determined in methylene chloride at a 
concentration of 0.25 g/100 ml of solution. Nuclear Magnetic Resonance 
("NMR") spectra were determined with a Varian EM-390, 90 MHz NMR 
spectrometer, Varian Associates, Palo Alto, Calif. NMR was used 
extensively to characterize monomers and polymers. Size exclusion 
chromatography ("SEC") was performed on high performance chromatograph 
u-styragel columns of 10.sup.6, 10.sup.5, 10.sup.4, and 10.sup.3 .ANG. 
porosities, calibrated with monodisperse polysterene standards to 
determine polymer molecular weights. Results are displayed as polysterene 
equivalent molecular weights. Differential Scanning Colorimetry ("DSC") 
was performed to determine glass transition temperatures ("Tg"). 
Turbidimetric titrations of the block copolymers were performed by 
preparing 1% solutions in methylene chloride and titrating with methanol. 
Percent transmittance versus volume of methanol titrant were plotted to 
determine turbidity end points. Elemental analyses were performed by 
combustion. 
EXAMPLE 1 
Synthesis of bis(4-carboxyphenyl) disulfide 
A solution of 69.0 g (1.0 mole) of sodium nitrite in 280 ml of water was 
added in portions to a cold (0.degree.-5.degree. C.) mixture of 137.0 g 
(1.0 mole) of p-aminobenzoic acid in 500 ml of water and 200 ml of 
concentrated hydrochloric acid ("HCl"), keeping the reaction temperature 
below 5.degree. C. This mixture was then added in portions to a previously 
prepared solution of 260.0 g (1.1 mole) of Na.sub.2 S.9H.sub.2 O, 34.0 g 
of powdered sulfur and 290 ml of water to which was added a solution of 
40.0 g (1.0 mole) of sodium hydroxide in 200 ml of water. After addition 
of the diazonium salt was complete, the mixture was stirred and slowly 
allowed to come to room temperature. Nitrogen was evolved and the 
resultant foaming was controlled by the addition of ice and ether. 180 ml 
of concentrated HCl was then added and the mixture was filtered. The 
solids were washed with water, dissolved in a solution of 120 g of sodium 
carbonate in 2.0 liters of water, filtered, and acidified with 
concentrated HCl. The solid was collected, washed with water, and dried. 
The yield of bis(4-carboxyphenyl) disulfide was 123.0 g and had a melting 
point ("mp") of 315.degree.-325.degree. C. 
EXAMPLE 2 
Synthesis of bis(4-carbomethoxyphenyl) disulfide 
A mixture of 123.0g (0.402 mol) of bis(4-carboxyphenyl) disulfide and 1 
liter of methanol was saturated with HCl gas and heated at reflux for 1 
hour, intermittently adding more HCl gas. 1 liter of methanol was added 
and reflux was continued for another 2.5 hours while adding HCl gas. Most 
of the acid had been esterified by this time. The hot mixture was filtered 
and cooled. The solid which crystallized was collected, dissolved in 
methylene chloride, treated with decolorizing carbon and concentrated. The 
residue was recrystallized from acetonitrile to give 28.5 g of 
bis(4-carbomethoxyphenyl) disulfide having amp of 
123.5.degree.-124.5.degree. C. 
EXAMPLE 3 
Synthesis of 2,2'-dithio(dibenzoyl chloride) 
A mixture of 150.0 g (0.487 mol) of dithiosalicylic acid, 750 ml of thionyl 
chloride and 5 ml of N,N-dimethylformamide ("DMF") was heated at reflux 
for 2 hours and concentrated. The residue was washed with ligroine (bp of 
35.degree.-60.degree. C.) and recrystallized from toluene, collected, 
washed with ligroine (bp of 35.degree.-60.degree. C.) and dried. The yield 
of 2,2'-dithio(dibenzoyl chloride) was 97.5 g and had amp of 
156.degree.-158.degree. C. 
EXAMPLE 4 
Synthesis of bis(2-carbomethoxyphenyl) disulfide 
A mixture of 5.0 g (0.0162 mol) of 2,2'-dithio(dibenzoyl chloride) and 50 
ml of methanol was heated at reflux for 25 minutes and cooled. The solid 
was collected and dried to give 4.9 g of bis(2-carbomethoxyphenyl) 
disulfide having amp of 130.degree.-32.degree. C. 
EXAMPLE 5 
Synthesis of dimethyl 4,4'-dithiodibutyrate 
A solution of 100.0 g (0.42 mol) of 4,4'-dithiodibutyric acid, 1 liter of 
methanol and 10 drops of concentrated sulfuric acid was heated at reflux 
for 30 minutes and allowed to cool overnight. The solution was heated for 
30 minutes again and concentrated. The residual oil was dissolved in 
methylene chloride, washed twice with dilute sodium bicarbonate, once with 
water, dried over MgSO.sub.4 and concentrated. The oily residue was 
distilled to give 74.5 g of dimethyl 4,4'-dithiodibutyrate having a 
boiling point ("bp") of 172.degree.-174.degree. C. at a pressure of 0.8 mm 
Hg. 
EXAMPLE 6 
Synthesis of bis(4-chlorocarbonylphenyl) disulfide 
Bis(4-carbomethoxyphenyl) disulfide prepared according to Example 2 was 
saponified to form bis(4-carboxyphenyl) disulfide. 8.9 g (0.029 mol) of 
bis(4-carboxyphenyl) disulfide was heated at reflux in a mixture of 50 ml 
of thionyl chloride and 2 drops of DMF for 30 minutes. The resultant 
solution was concentrated, treated with ligroine (bp of 
35.degree.-60.degree. C.), concentrated again and allowed to stand in 
heptanes for two days. The initial oil crystallized and was taken up in 
methylene chloride, filtered, concentrated and recrystallized from 
heptanes. The yield of bis(4-chlorocarbonylphenyl) disulfide was 2.7 g and 
had amp of 66.degree.-68.degree. C. 
EXAMPLE 7 
Synthesis of bis(4-isocyanatophenyl) disulfide 
A mixture of 248.4 g (1.0 mol) of bis(4-aminophenyl) disulfide, 200.0 g 
(2.0 mol) of concentrated HCl and 400 ml of water was heated to boiling, 
treated with decolorizing carbon and filtered. The filtrate was cooled and 
the solid was collected, washed with acetone and then with ether and 
dried. The yield of bis(4-aminophenyl) disulfide dihydrochloride was 139.0 
g. 
A solution of 407.5 g (0.618 mol) of 15% phosgene in toluene was added 
dropwise to a mixture of 40.0 g (0.125 mol) of bis(4-aminophenyl) 
disulfide dihydrochloride in 150 ml of toluene while heating on a steam 
bath over 2 hours. Heating was continued for another 5 hours and then 
nitrogen was swept through the reaction mixture overnight. The mixture was 
filtered and the filtrate was concentrated to an oil. Ligroine (bp of 
35.degree.-60.degree. C.) was added to crystallize the oil. The solid was 
collected, recrystallized from hexanes, collected and dried. The yield of 
bis(4-isocyanatophenyl) disulfide was 5.6 g and had amp of 
60.degree.-62.degree. C. A second yield of 13.0 g was obtained from the 
filtrate on concentrating to dryness which had amp of 
61.degree.-63.degree. C. 
EXAMPLE 8 
Synthesis of N,N'-bis(4-carbomethoxybenzoyl)-N,N'-dithiodianiline 
19.9 g (0.10 mol) of 4-carbomethoxybenzoyl chloride was added in portions 
to a solution of 12.4 g (0.05 mol) of 4,4'-dithiodianiline in 300 ml of 
pyridine and stirred for 1 hour at room temperature. The reaction mixture 
was poured into water and the precipitate was filtered, washed with water 
and recrystallized from DMF. The crystals were collected, washed with 
methanol and then with ether. The yield of 
N,N'-bis(4-carbomethoxybenzoyl)-N,N'-dithiodianiline was 28.0 g and had a 
mp of 276.degree.-278.degree. C. 
EXAMPLE 9 
Synthesis of bis(2-hydroxymethylphenyl) disulfide 
A solution of 30.8 g (0.20 mol) of o-mercaptobenzoic acid in 300 ml of 
dioxane was added to a mixture of 15.2 g (0.40 mol) lithium aluminum 
hydride in 300 ml of dioxane. 160 ml of tetrahydrofuran ("THF") was slowly 
added to this mixture with some loss of material due to bumping. The 
mixture was stirred for 2 hours followed by the slow addition of 15.2 ml 
of water, then 15.2 ml of 15% NaOH and finally 45.6 ml of water. The 
mixture was filtered with a methanol wash and the filtrate was 
concentrated to 20.0 g of oil. Methanol (250 ml) and 18.1 g (0.07 mol) of 
iodine were added and the mixture was stirred over the weekend. An equal 
volume of saturated NaCl solution was added and the solid was collected, 
washed with water, and recrystallized from aqueous ethanol. The yield of 
bis(2-hydroxymethylphenyl) disulfide was 10.0 g and had amp of 
138.5.degree.-139.5.degree. C. 
EXAMPLE 10 
Determination of Chain Transfer Constants 
The chain transfer constants of the disulfides prepared in Examples 2, 4 
and 5 were determined by the bulk polymerization of styrene with varying 
concentrations of disulfide. A plot was made of the reciprocal of the 
degree of polymerization of the resultant polystyrene (determined by SEC) 
versus the molar ratio of disulfide concentration to styrene monomer 
concentration. The slope of the resultant line provides the chain transfer 
constant according to the Mayo equation. The Mayo equation is an 
integrated expression valid for instantaneous polymerization events. To 
maintain a constant molar ratio of disulfide concentration to styrene 
monomer concentration (and maintain the accuracy of the Mayo Equation), 
polymers must be prepared at low conversions. "Conversion" is a percentage 
equal to the yield of polymer divided by the total of the weight of the 
monomer plus the weight of the chain transfer agent.times.100. 
The Mayo equation is shown by equation I below: 
EQU 1/DP=1/DP.degree.+C.sub.T [[S--S]/[M]) (I) 
where 
DP=degree of polymerization 
DP.degree.=degree of polymerization in absence of chain transfer agent 
C.sub.T =chain transfer constant 
[S--S]=disulfide concentration 
[M]=styrene monomer concentration 
20.0 g of styrene, 0.020 g of azobisisobutyronitrile ("AIBN") and varying 
quantities (0.100, 0.200 or 0.300 g) of bis(4-carbomethoxyphenyl) 
disulfide, bis(2-carbomethoxyphenyl) disulfide, or dimethyl 
4,4'-dithiodibutyrate were weighed into an 8 dram vial, purged with 
nitrogen for 15 minutes and sealed. The vials were heated in a 50.degree. 
C. bath for 3.25-3.50 hours and poured into 400 ml of methanol. The 
polymer was collected and dried in a 50.degree. C. vacuum oven. 
Polystyrene equivalent molecular weights were determined by size exclusion 
chromatography. Data from these experiments are compiled in Table I, where 
A is bis(4-carbomethoxyphenyl) disulfide; B is bis(2-carbomethoxyphenyl) 
disulfide; and C is dimethyl 4,4'-dithiodibutyrate. 
TABLE I 
__________________________________________________________________________ 
[S--S] [S--S]/ 
[mol/L] .times. 
[M] [M] .times. 
CONVERSION 1/DP .times. 
DISULFIDE 
10.sup.3 
[mol/L] 
10.sup.3 
% Mn DP 10.sup.3 
__________________________________________________________________________ 
A 0.00 8.71 0.00 
4.2 208220 
1999 
0.500 
A 13.56 8.71 1.557 
2.7 134180 
1288 
0.776 
A 27.12 8.71 3.114 
2.6 90260 
866 
1.155 
A 40.68 8.71 4.671 
2.6 72030 
691 
1.447 
B 0.00 8.71 0.00 
4.2 208220 
1999 
0.500 
B 13.56 8.71 1.557 
2.9 171810 
1650 
0.606 
B 27.12 8.71 3.114 
2.6 152780 
1467 
0.692 
B 40.68 8.71 4.671 
2.3 149470 
1435 
0.697 
C 0.00 8.71 0.00 
4.2 208220 
1999 
0.500 
C 17.07 8.71 1.953 
4.2 158640 
1523 
0.657 
C 34.06 8.71 3.911 
4.0 162020 
1556 
0.643 
C 51.07 8.71 5.860 
4.3 141610 
1360 
0.735 
__________________________________________________________________________ 
wherein: 
[S--S]=disulfide concentration 
[M]=styrene monomer concentration 
Conversion=[(yield of polymer)/(total weight of 
monomer+disulfide)].times.100 
Mn=number average polystyrene equivalent molecular weight 
DP=degree of polymerization 
A plot of 1/DP vs. [S--S]/[M] shows that bis(4-carbomethoxyphenyl) 
disulfide was the most active with a chain transfer constant of 0.207. In 
determining this value, it was assumed that no volume changes occurred 
when the disulfide was dissolved in the styrene monomer. 
The chain transfer constants of bis(2-carbomethoxyphenyl) disulfide and 
dimethyl 4,4'-dithiodibutyrate were 0.043 and 0.035 respectively. The 
foregoing indicate that A is most effective in chain transfer activity 
leading to the lowest molecular weight of polystyrene. 
EXAMPLE 11 
Synthesis of Chain Transfer Polyesters 
Syntheses of chain transfer polyesters were conducted by the following 
representative procedure for the 5 mole percent case using 
bis(4-carbomethoxy)phenyl disulfide (Sample 4). 
A 500 ml polymer flask was charged with 92.2 g (0.475 mol) of dimethyl 
terephthalate ("DMT"), 8.36 g (0.025 mol) of bis(4-carbomethoxyphenyl) 
disulfide and 72.9 g (0.70 mol) of neopentyl glycol ("NPG"). The flask was 
equipped with a Vigreax-Claisen head and nitrogen inlet tube and the side 
arm of the flask was sealed. The monomer mixture was melted in a 
200.degree. C. bath and 5 drops of tetraisopropyl orthotitanate 
(Ti(OPr).sub.4) were added. The mixture was then heated at 220.degree. C. 
for 2 hours at which time the bath temperature was raised to 240.degree. 
C. The mixture was heated for 1 hour and the column was removed. After 
another hour of heating at 240.degree. C., a metal blade stirrer was 
introduced and the pressure was reduced to 0.30 mm. Heating and stirring 
were continued for 2.25 hours after which the polymer 
poly[2,2-dimethyl-1,3- propylene terephthalate co 4,4'-dithiodibenzoate 
(95:5)] was cooled and isolated. 
The experimental details regarding the chain transfer polyesters produced 
and their properties are listed in Tables II and III below. 
TABLE II 
______________________________________ 
S--S DMT NPG Ti(OPr).sub.4 
SAMPLE Amt. Amt. Amt. Amt. 
# S--S* (moles) (moles) 
(moles) 
(drops) 
______________________________________ 
1 -- -- 0.72 1.26 ** 
2 A 0.009 0.891 1.30 9 
3 B 0.018 1.782 2.60 18 
4 A 0.025 0.475 0.70 5 
5 A 0.050 0.450 0.70 5 
______________________________________ 
*S--S = disulfide used in sample [A = bis(4carbomethoxyphenyl) disulfide, 
B = bis(2carbomethoxyphenyl) 
**Sample 1 catalyst was a combination of 0.0763 g An(OAc).sub.2.2H.sub.2 
and 0.139 g of Sb.sub.2 O.sub.3 
TABLE III 
______________________________________ 
SAMPLE Tg IV Mw/ 
# X S--S .degree.C. 
(DCM) Mn Mw Mn 
______________________________________ 
1 0 -- 74 0.33 13245 31319 2.36 
2 1 A 74 0.30 12235 27939 2.28 
3 1 B 73 0.33 11329 26093 2.30 
4 5 A 74 0.37 11046 29554 2.68 
5 10 A 74 0.33 8479 22944 2.70 
______________________________________ 
wherein 
X=mole percent disulfide 
Tg=glass transition temperature 
IV=inherent viscosity 
Mn=number average polystyrene equivalent molecular weight 
Mw=weight average polystyrene equivalent molecular weight 
S--S=Disulfide used in sample 
EXAMPLE 12 
Polymerization of Vinyl Monomers in the Presence of Chain Transfer 
Polyesters 
Vinyl monomers were polymerized in the presence of various chain transfer 
polyesters according to the following general procedure. A solution of 
chain transfer polyester (the specific polyester used for each sample is 
listed below) in THF was prepared in a flask at 60.degree. C. A quantity 
of vinyl monomer was added to this solution and the solution was purged 
with nitrogen. A quantity of AIBN was added and the solution was stirred 
under nitrogen for 16-25 hours (the flasks were sealed in Samples 1, 2, 4, 
6, 8). The resultant mixture was poured into cyclohexane (Samples 2, 6, 8) 
or methanol (Samples 1, 3-5, 7) to precipitate polymer which was then 
dried. Samples 1-7 were dissolved in methylene chloride and reprecipitated 
in cyclohexane, collected, washed with ligroine, cyclohexane, or heptanes 
and dried. 
The chain transfer polyesters (CT) used in each sample are as follows: 
Sample 1--Poly[2,2-dimethyl-1,3-propylene terephthalate] 
Sample 2--Poly[2,2-dimethyl-1,3-propylene terephthalate 
co-4,4'-dithiodibenzoate (99:1)] 
Sample 3--Poly[2,2-dimethyl-1,3-propylene terephthalate 
co-4,4'-dithiodibenzoate (95:5)] 
Sample 4--Poly[2,2-dimethyl-1,3-propylene terephthalate 
co-4,4'-dithiodibenzoate (90:10)] 
Sample 5--Poly[2,2-dimethyl-1,3-propylene terephthalate 
co-4,4'-dithiodibenzoate (95:5)] 
Sample 6--Poly[2,2-dimethyl-1,3-propylene terephthalate 
co-4,4'-dithiodibenzoate (99:1)] 
Sample 7--Poly[2,2-dimethyl-1,3-propylene terephthalate 
co-4,4'-dithiodibenzoate (95:5)] 
Sample 8--Poly[2,2-dimethyl-1,3-propylene terephthalate 
co-4,4'-dithiodibenzoate (95:5)] 
The vinyl monomers ("M") were either styrene (S), a mix of 
m+p-chloromethylstyrene (ClS), butyl acrylate (BuA), or a combination of 
75% styrene and 25% butyl acrylate (SBu). The reaction for this example is 
illustrated as reaction II below, where x and y are the mole percents of 
each diacid moiety. x plus y equals 100. z is the mole percent of vinyl 
monomer M in the block coplolymer. 
##STR6## 
The procedural details of Samples 1-8 are listed in Table IV below. The 
properties of the resulting block copolymers are listed in Table V below. 
TABLE IV 
__________________________________________________________________________ 
Sample 
M x y CT (g) 
M (g) 
AIBN (g) 
THF (ml) 
Time (hrs) 
CONV (%) 
__________________________________________________________________________ 
1 S 0 100 
25 25 0.125 200 25 47.1 
2 S 1 99 25 25 0.125 125 21 46.4 
3 S 5 95 25 25 0.125 125 21 40.4 
4 S 10 90 25 25 0.125 125 23 45.4 
5 S 5 95 10 40 0.200 125 24 18.4 
6 ClS 
1 99 25 25 0.125 125 16 60.0 
7 BuA 
5 95 25 25 0.125 125 22 32.0 
8 SBu 
5 95 25 25 0.125 150 19 40.0 
__________________________________________________________________________ 
TABLE V 
______________________________________ 
IV Tg z 
Sample 
(DCM) .degree.C. 
(Mole %) 
Mn Mw Mw/Mn 
______________________________________ 
1 0.30 73 2.7 20219 32811 1.62 
2 0.36 74 19.8 18517 30822 1.66 
3 0.34 69 25.3 20137 35434 1.76 
4 0.34 64 19.9 15031 28378 1.89 
5 0.28 78 44.4 15396 30976 2.01 
6 0.33 75 33.3 16462 29130 1.77 
7 0.44 79 44.0 17247 33023 1.91 
8 0.42 74 16.7* 20079 36166 1.80 
______________________________________ 
*equal molar ratios 
Table V illustrates the incorporation of polyvinyl blocks into chain 
transfer polyesters. A comparison of Sample 1 (no chain transfer agent 
present) with Samples 2-8 (chain transfer agent present) indicates that 
significantly more polyvinyl incorporation occurs in the presence of chain 
transfer polyester. In addition turbidimetric titrations of these block 
copolymers show that they precipitate with volumes of titrant between that 
for pure polyvinyl and pure chain transfer polyester, indicating the 
polyvinyl blocks were incorporated into the chain transfer polyester. 
EXAMPLE 13 
Crosslinking of Vinylbenzyl Chloride Block Copolymer Sample 6 of Table V 
A solution of 2.0 g of the block copolymer of Sample 6 of Table V was 
prepared with 20 ml of methylene chloride. Several drops of 
1,4-bis(aminomethyl)cyclohexane were added and the solution was allowed to 
stand in a stoppered flask over night. The solution became hazy and 
viscous and eventually formed a gel indicating crosslinking of the block 
copolymer (which contains pendant benzyl chloride) by alkylation of the 
added diamino compound. 
EXAMPLE 14 
Synthesis of hydroxy-terminated poly(2,2-dimethyl-1,3-propylene 
terephthalate) 
A mixture of 501.4 g (4.814 mol) of neopentyl glycol, 636.5 g (3.831 mol) 
of terephthalic acid and 1.0 g of butyl stannoic acid was heated in a 
3-neck, 2 liter flask with metal blade stirrer, nitrogen inlet, 
thermocouple and partial condensing steam heated column from 150.degree. 
C. to 210.degree. C. over 20 minutes. Heating at 210.degree. C. was 
continued for 16.5 hours during which time 129 ml of distillate was 
collected. The temperature was raised to 235.degree. C. and maintained for 
7 more hours to collect a total of 130 ml of distillate. The resin, 
poly(2,2-dimethyl-1,3-propylene terephthalate) was then poured out and 
cooled. The resin exhibited the following properties: 
IV(DCM)=0.06 
Tg=44.degree. C. 
CO.sub.2 H=0.10 meq/g 
OH=1.73 meq/g 
Mn=3082 
Mw=4278 
Mw/Mn=1.39 
This hydroxy terminated polyester was chain extended according to Example 
15. 
EXAMPLE 15 
Chain Extension of poly(2,2-dimethyl-1,3-propylene terephthalate) Polyester 
of Example 14 with bis(4-isocyanatophenyl) disulfide 
25.0 g (43.23 meq) (polyester of Example 14) of 
Poly(2,2-dimethyl-1,3-propylene terephthalate) was dried at 100.degree. C. 
with high vacuum and stirring. 75.0 g of DMF was added to dissolve the 
polymer under nitrogen. 6.49 g (43.23 meq) of bis(4-isocyanatophenyl) 
disulfide was added and the solution was stirred for 1 hour at 100.degree. 
C. under nitrogen. The solution which became more viscous was cooled and 
poured into methanol to precipitate the polyester-polyurethane. The 
polymer was rinsed several times with methanol, redissolved in methylene 
chloride and reprecipitated into methanol. The polymer was rinsed several 
times with methanol and dried. The yield of polymer was 27.6 g. The 
polymer exhibited the following properties: 
IV(DCM)=0.19 
Tg=81.degree. C. 
Mn=9289 
Mw=23481 
Mw/Mn=2.53 
As shown by this Example, the hydroxy terminated polyester of Example 14 
was chain extended with the diisocyanate disulfide. This provides another 
route to introduce the chain transfer moiety into a polyester under 
advantageously mild conditions. The Mn and Mw indicate that the molecular 
weight of the polyester was substantially increased compared to the 
polyester of Example 14. Also the Tg increased significantly compared to 
the polyester of Example 14. This material was used in Example 16 to 
prepare a polyvinyl-polyester-polyurethane block copolymer. 
EXAMPLE 16 
Polymerization of Styrene in the Presence of Chain Transfer 
Polyester-polyurethane of Example 15 
A solution of 12.5 g of the chain transfer polyester-polyurethane of 
Example 15, 12.5 g of styrene and 100 g of THF was purged with nitrogen. 
AIBN (0.0625 g) was added and the solution was stirred under a positive 
pressure of nitrogen in a 60.degree. C. bath for approximately 20 hours. 
During this time the THF evaporated and the polymer was redissolved in 
THF. The solution was poured into cyclohexane to precipitate the block 
copolymer which was redissolved in methylene chloride and reprecipitated 
in cyclohexane. The polymer was rinsed with cyclohexane and dried to give 
11.6 g of polyvinyl-polyester-polyurethane block copolymer. The polymer 
exhibited the following properties: 
IV(DCM)=0.21 
Tg=74.degree. C. 
Mn=16145 
Mw=24554 
Mw/Mn=1.52 
Mole percent styrene by NMR=31.8. 
Inclusion of styrene was verified by NMR (31.8 mole %). 
EXAMPLE 17 
Synthesis of Poly[1,2-propylene terephthalate 
co-glutarate-co-4,4-dithiodibenzoate(80:15:5)] 
A 250 ml polymer flask was charged with 77.7 g (0.40 mol) of dimethyl 
terephthalate, 8.36 g (0.025 mol) of bis(4-carbomethoxyphenyl) disulfide, 
12.0 g (0.075 mol) of dimethyl glutarate, 53.3 g (0.70 mol) of 
1,2-propanediol and catalytic amounts of Zn(OAc).sub.2.2H.sub.2 O and 
Sb.sub.2 O.sub.3. The flask was equipped with a Vigreax-Claisen head and 
nitrogen inlet and was heated in a 180.degree. C. bath for 1 hour, 
190.degree. C. for 1 hour, and 200.degree. C. for 1 hour. The head was 
removed and heating was continued for 1 hour at 200.degree. C. A metal 
blade stirrer was introduced and the melt was stirred at 200.degree. C. 
for 2 hours at 0.20 mm. The resultant polymer exhibited the following 
properties: 
IV(DCM)=0.09 
Tg=41.degree. C. 
Mn=3685 
Mw=5290 
Mw/Mn=1.44 
This polymer was used as the chain transfer polyester in Example 18. 
EXAMPLE 18 
Preparation of a Block Copolymer by Limited Coalescence from the Chain 
Transfer Polyester of Example 17, Styrene, and Butyl Acrylate 
A solution of 4.0 g of Example 17 chain transfer polyester, 12.0 g of 
styrene, 4.0 g of butyl acrylate and 0.48 g of AIBN was added to an 
aqueous phase consisting of 60 ml of pH 4 buffer, 1.0 ml of LUDOX.TM. 
silica, 0.3 ml of 10% promoter and 0.6 ml of 2.5% potassium dichromate 
while stirring with a Polytron mixer manufactured by Brinkmann. This 
mixture was then passed through a Microfluidizer and stirred in a 
60.degree. C. bath for 24 hours under a positive nitrogen pressure. The 
suspension was stirred at room temperature over the weekend, collected, 
stirred with 5.61% KOH then with 0.561% KOH and washed with water several 
times and dried. 
This example demonstrates a method of preparing block copolymer by the 
limited coalescence method without toner addenda (pigment or charge 
agent). NMR showed incorporation of styrene and butyl acrylate. 
Turbidimetric titration showed incorporation of styrene/butyl acrylate as 
a block and not a mixture. 
EXAMPLE 19 
Preparation of Toners by Limited Coalescence (Polymerization of Styrene, 
Butyl Acrylate, 4-Vinylpyridine and Divinylbenzene with Chain Transfer 
Polyester of Example 17) 
Two toners were prepared as described in Example 18 except aluminum 
phthalocyanine pigment and other addenda were also added. The organic 
phase of the limited coalescence system consisted of: 
1. A dispersion of: 
(a) aluminum phthalocyanine (a pigment), 
(b) KRATON G1652.TM. (a stabilizer triblock polymer, 
styrene/ethylenebutylene/styrene, available from Shell Chemical Company), 
(c) Sr El (a stabilizer copolymer, t-butyl styrene/lithium methacrylate), 
(d) a monomer mixture of S (styrene), B (butyl acrylate) and V.sub.4 
(4-vinylpyridine, a charge control agent) in a ratio of 74:21.6:4, and 
(e) the chain transfer polyester of Example 17 ("CTP"); 
2. Divinyl benzene (cross linking agent); and 
3. VAZO-52.TM. (azobisdimethylvaleronitrile free radical initiator 
available from DuPont). 
The compositions of the organic and aqueous phases are listed below: 
______________________________________ 
A B 
______________________________________ 
Organic Phase 
Dispersion 36.9 g 45.2 g 
Aluminum Phthalocyanine 
6 pph 6 pph 
KRATON-G1652 .TM. 3 pph 3 pph 
SrEl 1.5 pph 1.5 pph 
S/B/V4 49.5 pph 69.5 pph 
CTP 40 pph 20 pph 
Divinyl benzene 0.37 g 0.63 g 
VAZO-52 .TM. 0.56 g 0.95 g 
Aqueous Phase 
pH 4 Buffer 111 ml 135 ml 
LUDOX .TM. 1.85 ml 2.25 ml 
Promoter 0.56 ml 0.68 ml 
2.5% K.sub.2 Cr.sub.2 O.sub.7 
1.1 ml 1.35 ml 
______________________________________ 
Particles having volume average particle sizes of 6.6 .mu.m (A) and 6.9 
.mu.m (B) were obtained. The resultant toner particles exhibited high 
charge and low throw-offs. Images were successfully made from the 
resultant particles and oven fused. 
This invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.