Poly(vinylbenzyl quaternary phoshonium) salt charge control agents

A poly(vinylbenzyl quaternary phosphonium) salt having the following general structure: M represents Fe or Zn; PA1 X represents F, Cl, Br or I; PA1 p is 3 when M represents Zn and p is 4 when M represents Fe; PA1 ortho, meta and para isomers of the vinyl benzyl moiety are included; PA1 R.sup.1, R.sup.2 and R.sup.3 represent hydrogen; alkyl having from 1 to 24 carbon atoms; hydroxy-; carboxy-; alkoxy-; carboalkoxy; acyloxy-; amino-; nitro-; cyano-; keto-; or halo-; and R.sup.1, R.sup.2 and R.sup.3 may be independently substituted in the ortho, meta or para positions. R.sup.1, R.sup.2 and R.sup.3 may represent more than one substituent per ring; PA1 .brket open-st.Z.brket close-st. represents a copolymerized comonomer selected from the group consisting of acrylamides, acrylic acid, acrylonitrile, alkyl acrylates, alkyl methacrylates, alkyl vinyl ethers, styrenes, maleic anhydride, methacrylamides, methacrylic acid, methacrylonitrile, silyl methacrylates, vinyl esters, vinyl amides and vinyl halides and PA1 m and n together total 100 mole percent wherein m is 0.01 to 100.00 mole percent.

FIELD OF THE INVENTION 
This invention relates to charge control agents for electrostatographic 
toners and developers. 
BACKGROUND OF THE INVENTION 
In electrostatography, an image comprising an electrostatic toner and field 
pattern, usually of non-uniform strength (also referred to as an 
electrostatic latent image) is formed on an insulative surface of an 
electrostatographic element by any of various methods. For example, the 
electrostatic latent image may be formed electrophotographically (i.e., by 
imagewise photo-induced dissipation of the strength of portions of an 
electrostatic field of uniform strength previously formed on a surface of 
an electrophotographic element comprising a photoconductive layer and an 
electrically conductive substrate), or it may be formed by dielectric 
recording (i.e., by direct electrical formation of an electrostatic field 
pattern on a surface of a dielectric material). Typically, the 
electrostatic latent image is then developed into a toner image by 
contacting the latent image with an electrostatographic developer. If 
desired, the latent image can be transferred to another surface before 
development. 
One well-known type of electrostatographic developer comprises a dry 
mixture of toner particles and carrier particles. Developers of this type 
are commonly employed in well-known electrostatographic development 
processes such as cascade development and magnetic brush development. The 
particles in such developers are formulated such that the toner particles 
and carrier particles occupy different positions in the triboelectric 
continuum, so that when they contact each other during mixing to form the 
developer, they become triboelectrically charged, with the toner particles 
acquiring a charge of one polarity and the carrier particles acquiring a 
charge of the opposite polarity. These opposite charges attract each other 
such that the toner particles cling to the surfaces of the carrier 
particles. When the developer is brought into contact with the latent 
electrostatic image, the electrostatic forces of the latent image 
(sometimes in combination with an additional applied field) attract the 
toner particles, and the toner particles are pulled away from the carrier 
particles and become electrostatically attached imagewise to the latent 
image-bearing surface. The resultant toner image can then be fixed in 
place on the surface by application of heat or other known methods 
(depending upon the nature of the surface and of the toner image) or can 
be transferred to another surface, to which it then can be similarly 
fixed. 
A number of requirements are implicit in such development schemes. Namely, 
the electrostatic attraction between the toner and carrier particles must 
be strong enough to keep the toner particles held to the surfaces of the 
carrier particles while the developer is being transported to and brought 
into contact with the latent image, but when that contact occurs, the 
electrostatic attraction between the toner particles and the latent image 
must be even stronger, so that the toner particles are thereby pulled away 
from the carrier particles and deposited on the latent image-bearing 
surface. In order to meet these requirements for proper development, the 
level of electrostatic charge on the toner particles should be maintained 
within an adequate range. 
The toner particles in dry developers often contain material referred to as 
a charge agent or a charge-control agent, which helps to establish and 
maintain toner charge within an acceptable range. Many types of 
charge-control agents have been used and are described in the published 
patent literature. One general type of known charge-control agent 
comprises a quaternary phosphonium salt. While many such salts are known, 
some do not perform an adequate charge-control function in any type of 
developer, some perform the function well in only certain kinds of 
developers, and some control charge well but produce adverse side effects. 
A number of quaternary phosphonium salt charge-control agents are 
described, for example, in U.S. Pat. Nos. 4, 496,643 and 4,537,848. 
One of the important characteristics which is desirable for a quaternary 
phosphonium salt charge-control agent to possess is high thermal stability 
so that the salt will not totally or partially decompose during attempts 
to mix the salt with known toner binder materials in well-known processes 
of preparing toners by mixing addenda with molten toner binders. Such 
processes are often referred to as melt-blending or melt-compounding 
processes and are commonly carried out at temperatures ranging from about 
120.degree. C. to about 150.degree. C. Thus, charge agents that are 
thermally unstable at temperatures at or below about 150.degree. C. can 
exhibit this decomposition problem. 
Another important property or characteristic for a quaternary phosphonium 
salt to possess is, as mentioned previously, the ability to establish 
toner charge within an acceptable range necessary for optimum toner 
development so that the quality of the image that is to be developed is 
ideal. 
It would, therefore, be desirable to provide new, dry electrographic toners 
and developers containing quaternary phosphonium salts that have high 
thermal stability and can perform the charge-controlling function well. 
The present invention provides such toners and developers. 
SUMMARY OF THE INVENTION 
The present invention provides a poly(vinylbenzyl quaternary phosphonium) 
salt having the following general structure: 
##STR1## 
M represents Fe or Zn; X represents F, Cl, Br or I; 
p is 3 when M represents Zn and p is 4 when M represents Fe; 
ortho, meta and para isomers of the vinyl benzyl moiety are included; 
R.sup.1, R.sup.2 and R.sup.3 represent hydrogen; alkyl having from 1 to 24 
carbon atoms; hydroxy-; carboxy-; alkoxy-; carboalkoxy; acyloxy-; amino-; 
nitro-; cyano-; keto-; or halo-; and R.sup.1, R.sup.2 and R.sup.3 may be 
independently substituted in the ortho, meta or para positions. R.sup.1, 
R.sup.2 and R.sup.3 may represent more than one substituent per ring; 
.brket open-st.Z.brket close-st. represents a copolymerized comonomer 
selected from the group consisting of acrylamides, acrylic acid, 
acrylonitrile, alkyl acrylates, alkyl methacrylates, alkyl vinyl ethers, 
styrenes, maleic anhydride, methacrylamides, methacrylic acid, 
methacrylonitrile, silyl methacrylates, vinyl esters, vinyl amides and 
vinyl halides and 
m and n together total 100 mole percent wherein m is 0.01 to 100.00 mole 
percent. 
These polymer salts provide good charge-control in electrographic toners 
and developers. The quaternary phosphonium tetrahaloferrate and 
trihalozincate moieties responsible for charge control have enhanced 
activity when bound in the polymer backbone structure compared to 
quaternary phosphonium tetrahaloferrate and trihalozincate salts disclosed 
in U.S. Pat. Nos.5,459,006 and 5,561,020. They are also less fugitive in 
toners than quaternary phosphonium tetrahaloferrate and trihalozincate 
salts disclosed in U.S. Pat. Nos. 5,459,006 and 5,561,020. The thermal 
stabilities of the copolymers are significantly greater than compounding 
temperatures or fusing temperatures thereby minimizing concern over 
formation of toxic degradation products during melt compounding of toner 
or during heat fusing of toner to receiver. 
DETAILED DESCRIPTION OF THE INVENTION 
A particularly useful group of salts according to the above structure are 
where: 
R.sup.1, R.sup.2 and R.sup.3 represent hydrogen; alkyl having from 1 to 24 
carbon atoms such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, 2-butyl, 
n-pentyl, 3-pentyl, 2-ethylhexyl, cyclohexyl, n-octadecyl, and the like; 
hydroxy-; carboxy-; alkoxy-; such as methoxy, ethoxy, propoxy, butoxy, 
tert-butoxy, decyloxy and the like; carboalkoxy such as carbomethoxy, 
carboethoxy, carbobutoxy and the like, acyloxy such as acetoxy and 
benzoyloxy; amino such as unsubstituted amino, methylamino, diethylamino, 
phenylamino and the like; nitro; cyano; keto such as acetyl, benzoyl, 
propionyl, butyryl, hexanoyl and the like; or halo such as fluoro, chloro, 
bromo or iodo; 
.brket open-st.Z.brket close-st. represents a copolymerized comonomer 
selected from the group consisting of acrylamide, acrylic acid, 
acrylonitrile, benzyl methacrylate, n-butyl acrylate, t-butyl acrylate, 
n-butyl vinyl ether, 4-chloromethylstyrene, cyclohexyl acrylate, n-decyl 
methacrylate, 2-diethylaminoethyl acrylate, 2-dimethylaminoethyl 
methacrylate, ethyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl 
acrylate, isobornyl methacrylate, isobutyl vinyl ether, lauryl 
methacrylate, maleic anhydride, methacrylamide, methacrylic acid, 
methacrylonitrile, methyl methacrylate, styrene, .alpha.-methylstyrene, 
4-methylstyrene, 4-t-butylstyrene, n-octadecyl acrylate, 2-phenylethyl 
methacrylate, tetrahydrofurfuryl acrylate, trimethylsilyl methacrylate, 
vinyl acetate, vinyl caprolactam, vinylidene chloride and 
N-vinyl-2-pyrrolidone; and 
m is 1.00 to 10.00 mole percent. 
Poly(vinylbenzyl quaternary phosphonium tetrahaloferrate) and 
poly(vinylbenzyl quaternary phosphonium trihalozincate) salts of the 
invention are prepared by a three step process (Scheme I). Vinylbenzyl 
quaternary phosphonium halide is prepared by quaternization of triaryl 
phosphine with vinylbenzyl halide. The second step requires the 
polymerization or copolymerization with another comonomer to give polymer 
I. Step three involves dissolving polymer I in a solvent and pouring the 
resultant polymer solution into a methanolic solution of metal halide to 
give a precipitate of polymer II. Optionally and less preferred, the 
polymers could also be prepared by polymerization of vinylbenzyl halide 
followed by quaternization with triarylphosphine and treatment with metal 
halide. A third option involving treatment of vinylbenzyl quaternary 
phosphonium halide with metal halide to give vinylbenzyl quaternary 
phosphonium tetrahaloferrate and trihalozincate and subsequent 
polymerization is least desirable owing to the tendencies of certain 
halometallic anions to inhibit free radical initiated polymerization. 
##STR2##

The above method of preparation is illustrated in detail in Examples 1 and 
2. 
EXAMPLE 1 
Preparation of Copoly[4-vinylbenzyl triphenylphosphonium 
tetrachloroferrate:styrene] 2.7:97.3 mol % 
Step 1--Preparation of 4-vinylbenzyltriphenylphosphonium chloride 
4-Vinylbenzyl triphenylphosphonium chloride was prepared as described by 
Ruckenstein and Hong, Macromolecules, 26(6), 1363(1993). 
A solution of 85.00 g (557 mmol) of 4-vinylbenzyl chloride, 146.10 g (557 
mmol) of triphenylphosphine, 4-t-butylpyrocatechol inhibitor and 800 ml of 
DMF was heated in a 60.degree. C. bath under nitrogen for 23 hrs and 
cooled. Ether (100 ml) was added after which precipitation of product 
commenced. The mixture was allowed to stand overnight and filtered. The 
solid was washed with ether and ligroine and then dried. 
Step 2--Preparation of Copoly[4-vinylbenzyl triphenylphosphonium 
chloride:styrene] 2.7:97.3 mol % 
A solution of 10.00 g (24.1 mmol) of 4-vinylbenzyl triphenylphosphonium 
chloride (prepared as described above), 90.00 g (864.1 mmol) of styrene 
and 100.00 g of DMF was purged with nitrogen in a 60.degree. C. bath. AIBN 
(0.50 g) was added and the solution was heated under nitrogen in a 
60.degree. C. bath for 65.5 hrs. The polymer was precipitated in 
isopropanol, isolated, rinsed again with isopropanol and redissolved in 
methylene chloride. The polymer was reprecipitated in ligroine, isolated, 
rinsed again with ligroine and dried. The yield of polymer was 69.58 g 
(69.58% conversion). 
Step 3--Preparation of Copoly[4-vinylbenzyltriphenylphosphonium 
tetrachloroferrate:styrene] 2.7:97.3 mol % 
A solution of 6.50 g (1.57 meq of Cl.sup.-) of copoly[4-vinylbenzyl 
triphenylphosphonium chloride:styrene] 2.7:97.3 mol % (prepared as 
described above) in 35 ml of methylene chloride was added to a filtered 
solution of 2.12 g (13.08 mmol) of ferric chloride in 210 ml of anhydrous 
methanol. The polymer which precipitated was collected, washed with 
methanol and dried. The yield of polymer was 6.00 g. 
EXAMPLE 2 
Preparation of Copoly[4-vinylbenzyl triphenylphosphonium 
trichlorozincate:styrene] 2.7:97.3 mol % 
A solution of 10.00 g (2.41 meq of Cl.sup.-) of copoly[4-vinylbenzyl 
triphenylphosphonium chloride:styrene] 2.7:97.3 mol % (prepared as 
described above) in 25 ml of methylene chloride was added to a solution of 
2.73 g (20.00 mmol) of zinc chloride in 150 ml of methanol. The polymer 
which precipitated was collected, washed with methanol and dried. The 
yield of polymer was 6.95 g. Table I lists tetrachloroferrate and 
trichlorozincate copolymers prepared from copoly[4-vinylbenzyl 
triphenylphosphonium chloride: styrene] 2.7:97.3. 
Table I 
Copoly [4-vinylbenzyltriphenylphosphonium Tetrachloroferrate and 
Trichlorozincate:styrene] 2.7:97.3 
##STR3## 
where MX.sub.p.sup.-1 represents FeCl.sub.4.sup.-1 or ZnCl.sub.3.sup.-1. 
Other polymer charge control agents of the invention that can be prepared 
by the methods of Examples 1 and 2 are listed below. 
poly[4-vinylbenzyl triphenylphosphonium tetrachloroferrate] 
copoly[4-vinylbenzyl triphenylphosphonium tetrachloroferrate:styrene] 50:50 
copoly[4-vinylbenzyl triphenylphosphonium tetrachloroferrate:methyl 
methacrylate] 5:95; 
copoly[4-vinylbenzyl triphenylphosphonium tetrachloroferrate:acrylamide] 
5:95 
copoly[4-vinylbenzyl triphenylphosphonium tetrachloroferrate:methyl vinyl 
ether] 5:95; 
copoly[4-vinylbenzyl triphenylphosphonium 
tetrachloroferrate:methacrylonitrile] 5:95; 
copoly[4-vinylbenzyl triphenylphosphonium tetrabromoferrate:styrene] 10:90; 
copoly[4-vinylbenzyl triphenylphosphonium tribromochloroferrate:styrene] 
2.7:97.3; 
copoly[3-vinylbenzyl triphenylphosphonium tetrachloroferrate:styrene] 
2.7:97.3; 
copoly[2-vinylbenzyl triphenylphosphonium tetrachloroferrate:styrene] 
2.7:97.3; 
copoly[4-vinylbenzyl bis(4-carbomethoxyphenyl)phenylphosphonium 
tetrachloroferrate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl bis(4-acetoxyphenyl)phenylphosphonium 
tetrachloroferrate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl tris(4-acetoxyphenyl)phosphonium 
tetrachloroferrate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl tris(4-methoxyphenyl)phosphonium 
tetrachloroferrate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl tri(4-tolyl)phosphonium tetrachloroferrate:styrene] 
2.7:97.3; 
copoly[4-vinylbenzyl tris(4-chlorophenyl)phosphonium 
tetrachloroferrate:styrene] 2.7:97.3]; 
copoly[4-vinylbenzyl tris(4-carbomethoxyphenyl)phosphonium 
tetrachloroferrate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl (4-acetoxyphenyl)diphenylphosphonium 
tetrachloroferrate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl [3,5-bis(carbomethoxy)phenyl]diphenylphosphonium 
tetrachloroferrate:styrene] 2.7:97.3; 
poly[4-vinylbenzyl triphenylphosphonium trichlorozincate] 
copoly[4-vinylbenzyl triphenylphosphonium trichlorozincate:styrene] 50:50; 
copoly[4-vinylbenzyl triphenylphosphonium trichlorozincate:methyl 
methacrylate] 5:95; 
copoly[4-vinylbenzyl triphenylphosphonium trichlorozincate:acrylamide] 
5:95; 
copoly[4-vinylbenzyl triphenylphosphonium trichlorozincate:methyl vinyl 
ether] 5:95; 
copoly[4-vinylbenzyl triphenylphosphonium 
trichlorozincate:methacrylonitrile] 5:95; 
copoly[4-vinylbenzyl triphenylphosphonium dichlorobromozincate:styrene] 
5:95; 
copoly[4-vinylbenzyl triphenylphosphonium tribromozincate:styrene] 10:90 
copoly[4-vinylbenzyl triphenylphosphonium dibromochlorozincate:styrene] 
2.7:97.3 
copoly[3-vinylbenzyl triphenylphosphonium trichlorozincate:styrene] 
2.7:97.3 
copoly[2-vinylbenzyl triphenylphosphonium trichlorozincate:styrene] 
2.7:97.3 
copoly[4-vinylbenzyl bis(4-carbomethoxyphenyl)phenylphosphonium 
trichlorozincate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl bis(4-acetoxyphenyl)phenylphosphonium 
trichlorozincate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl tris(4-acetoxyphenyl)phosphonium 
trichlorozincate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl tris(4-methoxyphenyl)phosphonium 
trichlorozincate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl tri(4-tolyl)phosphonium trichlorozincate:styrene] 
2.7:97.3; 
copoly[4-vinylbenzyl tris(4-chlorophenyl)phosphonium 
trichlorozincate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl tris(4-carbomethoxyphenyl)phosphonium 
trichlorozincate:styrene] 2.7:97.3; 
copoly[4-vinylbenzyl (4-acetoxyphenyl)diphenylphosphonium 
trichlorozincate:styrene] 2.7:97.3 and 
copoly[4-vinylbenzyl [3,5-bis(carbomethoxy)phenyl]diphenylphosphonium 
trichlorozincate:styrene] 2.7:97.3. 
To be utilized as a charge-control agent in the electrostatographic toners 
of the invention, the quaternary phosphonium salt is mixed in any 
convenient manner (preferably by melt-blending) with an appropriate 
polymeric toner binder material and any other desired addenda, and the mix 
is then ground to desired size to form a free-flowing powder of toner 
particles containing the charge agent. Other methods include those 
well-known in the art such as spray drying, melt dispersion and dispersion 
polymerization. 
Toner particles of the invention have an average diameter between about 0.1 
.mu.m and about 100 .mu.m, a value in the range from about 1.0 to about 30 
.mu.m being preferable for many currently used machines. However, larger 
or smaller particles may be needed for particular methods of development 
or development conditions. 
Generally, it has been found desirable to add from about 0.05 to about 6 
parts and preferably 2.0 to about 5.0 parts by weight of the 
aforementioned quaternary phosphonium tetrahaloferrate and trihalozincate 
salts per 100 parts by weight of a polymer to obtain the improved toner 
compositions of the present invention. Of course, it must be recognized 
that the optimum amount of charge-control agent to be added will depend, 
in part, on the particular quaternary phosphonium charge-control agent 
selected and the particular polymer to which it is added. The polymeric 
charge-control agents may also serve as the toner binder. However, the 
amounts specified hereinabove are typical of the useful range of 
charge-control agents utilized in conventional dry toner materials. 
The polymers useful as toner binders in the practice of the present 
invention can be used alone or in combination and include those polymers 
conventionally employed in electrostatic toners. Useful amorphous polymers 
generally have a glass transition temperature within the range of from 
50.degree. to 120.degree. C. Preferably, toner particles prepared from 
these polymers have relatively high caking temperature, for example, 
higher than about 60.degree. C., so that the toner powders can be stored 
for relatively long periods of time at fairly high temperatures without 
having individual particles agglomerate and clump together. The melting 
point of useful crystalline polymers preferably is within the range of 
from about 65.degree. C. to about 200.degree. C. so that the toner 
particles can readily be fused to a conventional paper receiving sheet to 
form a permanent image. Especially preferred crystalline polymers are 
those having a melting point within the range of from about 65.degree. to 
about 120.degree. C. Of course, where other types of receiving elements 
are used, for example, metal plates such as certain printing plates, 
polymers having a melting point or glass transition temperature higher 
than the values specified above can be used. 
The various polymers which can be employed in the toner particles of the 
present invention are polycarbonates, resin-modified maleic alkyd 
polymers, polyamides, phenol-formaldehyde polymers and various derivatives 
thereof, polyester condensates, modified alkyd polymers, aromatic polymers 
containing alternating methylene and aromatic units such as described in 
U.S. Pat. No. 3,809,554 and fusible crosslinked polymers as described in 
Re. U.S. Pat. No. 31,072. 
Typical useful toner polymers include certain polycarbonates such as those 
described in U.S. Pat. No. 3,694,359, which include polycarbonate 
materials containing an alkylidene diarylene moiety in a recurring unit 
and having from 1 to about 10 carbon atoms in the alkylidene moiety. Other 
useful polymers having the above-described physical properties include 
polymeric esters of acrylic and methacrylic acid such as poly(alkyl 
acrylate), and poly(alkyl methacrylate) wherein the alkyl moiety can 
contain from 1 to about 10 carbon atoms. Additionally, other polyesters 
having the aforementioned physical properties are also useful. Among such 
other useful polyesters are copolyesters prepared from terephthalic acid 
(including substituted terephthalic acid), fumaric acid, a 
bis[(hydroxyalkoxy)phenyl]alkane having from 1 to 4 carbon atoms in the 
alkoxy radical and from 1 to 10 carbon atoms in the alkane moiety (which 
can also be a halogen-substituted alkane), and an alkylene glycol having 
from 1 to 4 carbon atoms in the alkylene moiety. 
Other useful polymers are various styrene-containing polymers. Such 
polymers can comprise, e.g., a polymerized blend of from about 40 to about 
100 percent by weight of styrene, from 0 to about 45 percent by weight of 
a lower alkyl acrylate or methacrylate having from 1 to 4 carbon atoms in 
the alkyl moiety such as methyl, ethyl, isopropyl, butyl, etc. and from 
about 5 to about 50 percent by weight of another vinyl monomer other than 
styrene, for example, a higher alkyl acrylate or methacrylate having from 
about 6 to 20 or more carbon atoms in the alkyl group. Typical 
styrene-containing polymers prepared from a copolymerized blend as 
described herein-above are copolymers prepared from a monomeric blend of 
40 to 60 percent by weight styrene or styrene homolog, from about 20 to 
about 50 percent by weight of a lower alkyl acrylate or methacrylate and 
from about 5 to about 30 percent by weight of a higher alkyl acrylate or 
methacrylate such as ethylhexyl acrylate (e.g., styrene-butyl 
acrylate-ethylhexyl acrylate copolymer). Preferred fusible styrene 
copolymers are those which are covalently crosslinked with a small amount 
of a divinyl compound such as divinylbenzene. A variety of other useful 
styrene-containing toner materials are disclosed in U.S. Pat. Nos. 
2,917,460; Re. U.S. Pat. Nos. 25,316; 2,788,288; 2, 638,416; 2,618,552 and 
2,659,670. 
Various kinds of well-known addenda (e.g., colorants, release agents, etc.) 
can also be incorporated into the toners of the invention. 
Numerous colorant materials selected from dyestuffs or pigments can be 
employed in the toner materials of the present invention. Such materials 
serve to color the toner and/or render it more visible. Of course, 
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 density. In those instances where 
it is desired to utilize a colorant, the colorants 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 are such materials as Hansa Yellow G (C.I. 11680), Nigrosine 
Spirit soluble (C.I. 50415), Chromogen Black ET00 (C.I. 45170), Solvent 
Black 3 (C.I. 26150), Fuchsine N (C.I. 42510), C.I. Basic Blue 9 (C.I. 
52015). Carbon black also provides a useful colorant. The amount of 
colorant added may vary over a wide range, for example, from about 1 to 
about 20 percent of the weight of the polymer. Particularly good results 
are obtained when the amount is from about 1 to about 10 percent. 
To be utilized as toners in the electrostatographic developers of the 
invention, the toners of this invention can be mixed with a carrier 
vehicle. The carrier vehicles, which can be used with the present toners 
to form the new developer compositions, can be selected from a variety of 
materials. Such materials include carrier core particles and core 
particles overcoated with a thin layer of a film-forming resin. 
The carrier core materials can comprise conductive, non-conductive, 
magnetic, or non-magnetic materials. For example, carrier cores can 
comprise glass beads; crystals of inorganic salts such as aluminum 
potassium chloride; other salts such as ammonium chloride or sodium 
nitrate; granular zircon; granular silicon; silicon dioxide; hard resin 
particles such as poly(methyl methacrylate); metallic materials such as 
iron, steel, nickel, carborundum, cobalt, oxidized iron; or mixtures or 
alloys of any of the foregoing. 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 the polymers described in U.S. Pat. Nos. 
3, 547,822; 3,632,512; 3,795,618; 3,898,170 and Belgian Pat. No. 797,132. 
Other useful resins are fluorocarbons such as polytetrafluoroethylene, 
poly(vinylidene fluoride), mixtures of these and copolymers of vinylidene 
fluoride and tetrafluoroethylene. See, for example, U.S. Pat. Nos. 
4,545,060; 4,478,925; 4,076,857; and 3,970,571. Such polymeric 
fluorocarbon carrier coatings can serve a number of known purposes. One 
such purpose can be to aid the developer to meet the electrostatic force 
requirements mentioned above by shifting the carrier particles to a 
position in the triboelectric series different from that of the uncoated 
carrier core material, in order to adjust the degree of triboelectric 
charging of both the carrier and toner particles. Another purpose can be 
to reduce the frictional characteristics of the carrier particles in order 
to improve developer flow properties. Still another purpose can be to 
reduce the surface hardness of the carrier particles so that they are less 
likely to break apart during use and less likely to abrade surfaces (e.g., 
photoconductive element surfaces) that they contact during use. Yet 
another purpose can be to reduce the tendency of toner material or other 
developer additives to become undesirably permanently adhered to carrier 
surfaces during developer use (often referred to as scumming). A further 
purpose can be to alter the electrical resistance of the carrier 
particles. 
A typical developer composition containing the above-described toner and a 
carrier vehicle generally comprises from about 1 to about 20 percent by 
weight of 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, 
preferably 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 charge-control agents of the present invention impart a positive charge 
to the toner composition. The level of charge on the developer 
compositions utilizing a charge-control agent of the present invention is 
preferably in the range of from about 15 to 60 microcoulombs per gram of 
toner for toner particles having a volume average diameter of from about 7 
to 15 micrometers in the developer as determined in accordance with the 
procedure described below. 
The toner and developer compositions of this invention can be used in a 
variety of ways to develop electrostatic charge patterns or latent images. 
Such developable charge patterns can be prepared by a number of means and 
be carried for example, on a light sensitive photoconductive element or a 
non-light-sensitive dielectric-surfaced element such as an 
insulator-coated conductive sheet. One suitable development technique 
involves cascading the developer composition across the electrostatic 
charge pattern, while another technique involves applying toner particles 
firm a magnetic brush. This latter technique involves the use of a 
magnetically attractable carrier vehicle in forming the developer 
composition. After imagewise deposition of the toner particles, the image 
can be fixed, e.g., by heating the toner to cause it to fuse to the 
substrate carrying the toner. If desired, the unfused image can be 
transferred to a receiver such as a blank sheet of copy paper and then 
fused to form a permanent image. 
The following examples are presented to further illustrate the present 
invention. 
Toner Preparation 
Toners were formulated by compounding 100 parts of cross-linked 
styrene/n-butyl acrylate copolymer with 6 parts of Black Pearls 430 (Cabot 
Corporation, Boston Mass.) with 2 and 5 parts of the novel charge agents 
described above at 150.degree. C. on a 4 inch roll mill. The toner binder 
consisted of styrene, n-butyl acrylate and divinyl benzene (77/23/0.3325 
weight ratio). The copolymer was synthesized by a limited coalescence 
based suspension polymerization technique and devolatilized by an 
extrusion method. 
The resultant melt compounded product was pulverized in a fluid energy mill 
to yield a volume average particle size of about 12 microns as measured by 
Coulter Counter. 
Preparation of Developer 
The developers were prepared by combining 10 grams of toner with 90 grams 
of carrier particles. The carrier consisted of strontium ferrite based 
core which had been melt coated at 230.degree. C. with 2 pph of 
poly(vinylidene flouride) (Kynar 301F manufactured by Elf Atochem). 
Evaluation of Toner Charging, Aging and Throw-Off 
The charge to mass of the developer was measured by the following 
conventional charge measuring technique. 4 grams of the above developer 
was gently agitated in an appropriate bottle or vial to allow developer to 
reach its optimum maximum charge. This was achieved by a wrist action 
robot shaker operating at 2 Hz and an overall amplitude of 11 cm for 2 
minutes. The toner charge was measured by placing 0.1 to 0.2 grams of 
charged developer in a sample dish situated between electrode plates and 
subjecting it simultaneously for 30 seconds to a 60 Hz magnetic field to 
cause developer agitation and to an electric field of about 2000 volts/cm 
between the plates. Some toner releases from the plate having polarity 
opposite to the toner charge. The total charge was measured by an 
electrometer connected to the plate. The toner charge divided by the 
weight of toner on the opposite plate yielded the charge/mass ratio for 
the toner in microcoulombs/gram (.mu.C/gm). 
The exercised charge/mass ratio was determined similarly except that the 
charged developer was vigorously aged by placing it into a plastic vial, 
capping the vial and placing the vial for 10 minutes on a "bottle brush" 
device comprising a magnetic toning roller with a stationary shell and a 
magnetic core rotating at 2000 rpm. The magnetic core had 12 magnetic 
poles arranged around its periphery in alternating north-south fashion. 
The throw-off value (TO) for the toner was determined by taking the 2 gram 
developer sample that had been bottle-brush exercised for 10 minutes, 
admixing in 5 percent more toner to provide a final toner concentration of 
15 percent, followed by 15 seconds of agitation on a wrist action shaker. 
This developer was then placed on a toning roller containing a rotating 
magnetic core similar to a magnetic brush used for electrostatic 
development. A Plexiglass.TM. housing contained the assembly and having a 
vacuum filter mounted directly over the roll with a vacuum applied to 
direct any toner throwoff to the vacuum filter. The weight of toner in 
milligrams collected on a piece of filter paper after one minute of 
running the magnetic core at 2000 rpm was reported as the throw-off value. 
The extended aging behavior of the developer was determined by placing a 
six gram developer on a bottle-brush for 16 hours. The aged developer was 
then stripped of all toner and rebuilt with fresh toner again at 10% toner 
concentration. The fresh exercised charge/mass values were calculated as 
described previously along with the throw-off results. 
Tables II and III establish the utility of black toners containing the 
polymeric charge-control agents of the invention. The charge stability can 
be estimated by the relative stability of the 10 min bottle brush 
charge/mass values obtained on first day and after overnight exercising. 
Typically, the charge/mass value obtained after 2 minutes on wrist shaker, 
indicates the lack of preconditioning. The similar value obtained 
following overnight exercise is generally low due to stripping action, 
which leaves behind highly charged, small particles on the carrier 
surface. 
A measure of charging rate is the amount of dusting observed when fresh 
toner is ad(led to a charged developer. If for any reason, the toner is 
unable to charge sufficiently in the short agitation period, then the 
centrifugal force experienced in a rotating developing brush will overcome 
the weak electrostatic attraction between the toner and the carrier 
surface and dusting will ensue. 
Table II summarizes the charging behavior of copoly[4-vinylbenzyl 
triphenylphosphonium tetrachloroferrate:styrene] 2.7:97.3. The two 
critical criteria for establishing the effectiveness of any charge agent 
is the charge stability and the charging rate. 
The copolymer sample in Table II contains 2.7 mole percent amount of 
4-vinylbenzyl triphenylphosphonium tetrachloroferrate moiety. The results 
in Table II show that, in general, the developers containing the above 
copolymer exhibit fairly stable charge at both 2 and 5 pph levels. The 
toners formulated with 4-vinylbenzyl triphenylphosphonium 
tetrachloroferrate moiety as charge controlling agent maintain this 
charge/mass stability even after the developer is aged overnight. Further, 
the charge stability of the developer appears to be maintained regardless 
of the amount of the charge agent used. Hence, it would be possible to 
control the charge/mass ratio of toner by changing the charge agent amount 
while not affecting the long term developer charging characteristics. The 
dusting behavior with 4-vinylbenzyl triphenylphosphonium 
tetrachloroferrate is found to be excellent even when the charge/mass is 
low indicating a rapid charging behavior of the toner. 
TABLE II 
______________________________________ 
Copoly[4-vinylbenzyl triphenylphosphonium tetrachloroferrate:styrene] 
2.7:97.3 Charge Control Properties 
- 
#STR4## 
- Initial Overnight, Strip & Rebuild 
fresh Q/m 
10 min Q/m 
TO, Fresh Q/m 
10 min Q/m 
TO, 
pph (.mu.C/g) (.mu.C/g) mg (.mu.C/g) (.mu.C/g) mg 
______________________________________ 
2 53.21 16.30 4.5 27.63 22.57 0.9 
5 75.91 49.46 0.3 46.27 47.86 0.4 
______________________________________ 
Table III summarizes the charging behavior of copoly[4-vinylbenzyl 
triphenylphosphonium trichlorozincate:styrene] 2.7:97.3. The two critical 
criteria for establishing the effectiveness of any charge agent is the 
charge stability and the charging rate. 
The copolymer sample in Table III contains 2.7 mole percent amount of 
4-vinylbenzyl triphenylphosphonium trichlorozincate moiety. The results in 
Table III show that, in general, the developers containing the above 
moiety in copolymeric CCA exhibit fairly stable charge at both 2 and 5 pph 
levels. The toners formulated with 4-vinylbenzyl triphenylphosphonium 
trichlorozincate moiety as charge controlling agent maintain this 
charge/mass stability even after the developer is aged overnight. Further, 
the charge stability of the developer appears to be maintained regardless 
of the amount of the charge agent used. 
Hence, it would be possible to control the charge/mass ratio of toner by 
changing the charge agent amount while not affecting the long term 
developer charging characteristics. Overall, these copolymers provide 
slightly higher charge than many other char,,e agent in its class. Dusting 
behavior with 4-vinylbenzyl triphenylphosphoniun trichlorozincate is found 
to be quite good even when the charge/mass is low suggesting a rapid 
charging behavior of the toner. 
TABLE III 
______________________________________ 
Copoly[4-vinylbenzyl triphenylphosphonium trichlorozincate:styrene] 
2.7:97.3 Charge Control Properties 
- 
#STR5## 
- Initial Overnight, Strip & Rebuild 
fresh Q/m 
10 min Q/m 
TO, Fresh Q/m 
10 min Q/m 
TO, 
pph (.mu.C/g) (.mu.C/g) mg (.mu.C/g) (.mu.C/g) mg 
______________________________________ 
2 59.8 32.0 0.7 23.3 28.0 4.6 
5 66.2 51.5 0.5 39.7 48.0 2.2 
______________________________________ 
The invention has been described in detail with particular reference to 
certain preferred embodiments thereof, but it will be understood that 
variations and modifications can be effected within the spirit and scope 
of the invention.