CA1062945A - Imaging system - Google Patents

Abstract

IMAGING SYSTEM
ABSTRACT OF THE DISCLOSURE
Electrostatographic developer compositions for use in developing electrostatic latent images wherein the triboelectric charging potential of functional polymers employed in the developer materials are controlled through chemical alteration by aminolysis of ester functions. The controlled variation of the triboelectric behavior of functional polymers by aminolysis provides a means of attaining optimum triboelectric responses in develpement systems.

Description

~06~945 This invention relates in general to imaging systems and more paxticularly to improved electrostatographic developer mixtures for use in such systems.
The formation and development of images on the surface o photoconductive materials by electrostatographic means is known. The basic electrostatographic process as taught by C. F. Carlson in U. S. Patent 2,297,691 involves placing a uniform electrostatic charge on a photoconductive insulating lay-er, exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light, and developing the resultant electrostatic latent image by depositing on the image, a finely-divided electroscopic material referred to in the art as "toner". The toner is attracted to those areas of the layer which retain a charge, thereby forming a ~ ;
toner image corresponding to the electrostatic latent image.
This ~"powder" image may then be transferred, usually electrostatically, to a support surface such as paper. The transferred image may subsequently be permanently affixed to the support surface by heat or other suitable affixing means such as solvent or overcoating treatment may be used instead.
Many methods~are known for applying the electroscopic particles to the latent image tc be developed. One development method as disclosed by E. N. Wise in U. S. Patent 2,618,582 is known as "cascade" development. In this method, developer màterial, comprising relatively large carrier particles, having finely-divided toner particles electrostatically clinging to the .i surface of the carriex particles, is conveyed to, and rolled or cascaded across the surface bearing the electrostatic latent i~
image. The charged portions of the surfacl~ have a charge of the same polarity as, but stronger than, the carrier particles.
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Toner and carrier particles having opposite polarities are selected so that the toner particles cling to the carrier particles. In order to develop a negatively charged electrostatic ~; latent image, a toner and carrier combination are selected in which the toner is triboelectrically positive in relation to the carrier. Conversely, to develop a positively charged electrostatic latent image, a toner and carrier combination wherein the toner is triboelectrically negative in relation to the carrier is used. The triboelectric relationship between 0 the toner and carrier depends on the relative positions of the ~ i !
materials in the "triboelectric series". In this series, materials are arranged in ascending order of their ability ~' to take on a positive charge. Each material is positive with .. ;~ .
~, respect to any material classified below it in the series; and, negative with respect to any material above it in the series.
As the developer mixture cascades or rolls across the image-bearing surface, the toner particles are electrostatically attracted from the carrier to the charged portions of the image-bearing surface, whereas they are not electrostatically ;
~'0 attracted to the uncharged or background portions of the image which they contact. The carrier particles and unused toner ~- ~ particles are then recycled. The cascade development process ~i i9 extremely good for the development of line copy images, and is the most widely used commercial electrostatographic develop-~5 ment technique. A general purpose office copying machine :~ incorporating this technique is described in U.S. Patent `
~;! 3~099~943 Another technique for developing electrostatic latent `
images is the "magnetic brush" process as disclosed, for example, ~?~o in U. S. Patent 2,874,063. In this process, a developer material ~, ' ' .

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containing toner and magn~ttic carrier particles is attracted -to and is carried by a magnet. The magnetic field causes alignment of the magnetic particles in a brush-like configuration.
When this magnetic brush is brought into contact with an electrostatic latent image-bearing surface, the toner particles are attracted from the carrier particles of the brush to the `!~ charged areas of the image-bearing surface but not to the uncharged areas. Since the charged areas have an imagewise configuration, the toner material clings to the surface in imagewise configuration, thus developing the latent image.
;~ Another method for developing electrostatic latent images is disclosed in U. S. Patent 3,503,776 issued to R. W.
Gundlach. In this method, images are formed by transporting an electrostatic latent image-bearing surface in a generally ~15 ascending arcuate path, and contacting only the image in a ;j contact zone with a ba~h of developer material transported in a concave chamber adjacent to the lower path of the imaging surface. me contact zone extends from about the lower-most point of the arcuate pa~h to the uppermost point of the arcuate ,20 path. As the imaging surface is transported along its arcuate ~ -~, path, frictional contact between the developer and the imaging ;
surface in the contact zone circulates the developer in the - `
bath and brings developer material into developing configuration with the imaged surface. ` ; ~
:'' ~.. : -,25 Many other methods, such as the "touchdown" develop- i ment method disclosed by C. R. Mayo in U. S. Patent 2,895,847 are known for applying electroscopic particles to the electro-t static latent image to be developed. The development process, as described above, together with numerous modifications, are ~ :
well-Xnown to the art through various patents and pubIications -3~

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r 106;~945 and through the widespread availability and utilization of electrostatographic imaging equipment.
In automatic reproduction equipment, it is conven-tional to employ as the imaging plate, a photoconductor on a !
conductive substrate in the form of a cylindrical drum or a flexible belt which is continuously rotated through a cycle li of sequential operations including charging, exposing developing, transferring, and cleaning. The developer chamber is charged with a developer mixture comprising carrier particles and '~ enough toner particles for hundreds of reproduction cycles.
~!1, Generally, the freshly charged developer mixtures contain between about 1.5 and about 5% toner particles based upon the ~`
weight of the developer. This initial concentration provides sufficient toner for many reproduction cycles without causing '5 undesirably high background toner deposition. `
i .
~, While ordinarily capable of producing good quality images, conventional developing systems suffer serious defi-ciencies in certain areas. In the reproduction of high contrast .~ . ...
copies such as letters, tracings, and the like, it is desirable D to select the electroscopic powder and carrier materials so that their mutual electrification is relatively large; the degree of such electrification being governed in most cases by the distance between their relative positions in the triboelectric ~j;
series. However, when otherwise compatible electroscopic powder ~5 ~ and carrier materials are removed from each other in the tribo- ~-!i electric series by too great a distance, the resulting images ;-;i are very faint because the attractive forces between the carrier and toner particles compete with the-attractive forces between the electrostatic latent image and the carrier particles.
~b Although the image density described in the immediately preceding :t ~ : `^ .. : .
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L0629~5 sentence may be improved by increasing the toner concentration - in the developer mixture, undesirably high background toner deposition as well as increased toner impaction and agglomera-tion is encountered when the developer mixture is overtoned.
The initial electrostatographic plate charge may be increased to improve the density of the deposited powder image, but the plate charge would ordinarily have to be excessively high in order to attract the electroscopic powder away from the carrier particle. Excessively high electrostatographic plate charges are not only undesirable because of the high power consumption -necessary to maintain the electrostatographic plate at high potentials, but also because the high potential causes the 1 carrier particles to adhere to the electrostatographic plate `~ surfaces rather than merely roll across and off the electrostato- -~15 graphic plate surface. Print deletion and massive carry-over i~ of carrier particles often occur when carrier particles adhere to reusable electrostatographic imaging surfaces. Massive -`3 carrier carry-over problems are particularly acute when the developer is employed in solid area coverage machines where -~
,~ , .
~20 excessive quantities of toner particles are removed from carrier particles thereby leaving many carrier particles substantially -`! bare of toner particles. Further, adherence of carrier particles -to reusable electrostatographic imaging surfaces promotes the formation of undesirable scratches on the surface during image ~25 transfer and surface cleaning operations.
` It is, therefore, apparent that many materials which otherwise have suitable properties for employment as carrier particles are unsuitable because they possess too high a triboelectric value. In addition, uniform triboelectric ;`~
~0 surface characteristics of many carrier surface~ are difficult ~
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~` ~` ~IL0~;299~5 to achieve with mass production techniques. Quality images are, in some instances almost impossible to obtain in high speed automatic machines when carriers having non-uniform triboelectric properties are employed. Although it may be possible to alter the triboelectric value of an insulating carrier material by blending the carriex material with another insulating material having a triboelectric value remote from the triboelectric value of the original carrier material, relatively larger quantities of additional material are necessary to alter the triboelectric value of the original carrier material. The addition of large quantities of material to the original carrier material to change the triboelectric properties thereof requires a major manufacturing operation and often undesirably alters the original physical character- ;
istics of the carrier material. Further, it is highly desirable to control the triboelectric properties o* carrier surfaces to accommodate the use of desirable toner compositions while retaining the other desirable physical characteristics of the carrier. The alteration of the triboelectric properties of a carrier by applying a surface coating thereon is a ~`~
particularly desirable technique. With this technique, not only is it possible to control the triboelectric properties of a carrier made from materials having desirable physical characteristics, it is also possible to employ materials previously not suitable as a carrier. Thus, for example, a carrier having desirable physical properties with the excep-tion of hardness, can be coated with a material having desirable hardness as well as other physical properties, rendering the resultant pr~oduct more u-seful as a carrier. ~;
However, since most carrier coating materials a~re deicient `

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1062g45 in one or more of the above areas, there is a continuing need for improved electrostatographic carrier and developer compo-sitions and methods for forming the same.
It is also apparent that the toner is subjected to severe mechanical attrition which tends to break down the particles into undesirable dust fines. The formation of fines is retarded when the toner contains a tough, high molecular weight resin which is capable of withstanding the shear and impact forces imparted to the toner in the -machine. Unfortunately, many high~molecular weight materials cannot be rapidly fused during a powder image heat fixing ;~
step. On the other hand, low molecular weight resins which ;~
are easily heat fused at relatively low temperatures are usually undesirable because these materials tend to form thick films on reusable p~lotoconductor surfaces. These films tend -to cause image degradation and contribute to machine maintenance down time. Many low molecular weight resins decompose when subjected to fusing conditions in high speed copying and duplicating machines. In addition, low molecular weight resins tend to form tacky images on the copy sheet which are -easily smudged and often offset to other adjacent sheets.
Additionally, low mole~ular weight resins are often extremely difficult or even impossible to comminute in conventional ~ -grinding apparatus. Also, the toner materials must be capable of accepting a charge of the correct polarity when brought into rubbing contact with the surface of carrier materials in cascade or touchdown development systems. ~Additionally, many toner materials cannot satisactorily be transferred by con-ventional electrostatographic development systems from reusable imaging surfaces in~automatic copying and duplicating ;;
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~06z945 machines. Since most polymeric toner materials are deficient in one or more of the above areas, there is a continuing need for improved toners and developers. -In accordance with one aspect of this invention there is provided an electrostatographic developer composition having controlled triboelectric charging properties for use in developing electrostatic latent images on a recording surface, ' comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles, at least the toner or carrier particles comprising an aminolyzed polymer having the general structure : ,. : ,. ~
CH3 ~ ~
" ' 2f~2-oNH (CH2 )6 where X may be NH2, OH, NHCOC6H4R, OCOC6H4R, and H, and wherein R may be an electron donating or electron releasing substituent.
In accordance with another aspect of this invention there is provided an electrostatographic developer composition comprising finely-divided toner particles having an average E,: .: . ,: . ' particle diameter of less than 30 microns electrostatically clinging to the surface of carrier particles having an average 7'~ ' r -particle diameter of between about 50 microns and about 1,000 i -microns, at least the toner particles or the carrier particles ~;
comprising an aminolyzed polymer having the general structure ~ fCHz-~ C~NH(CH ~

where X may be NH2, OH, NHCOC6H4R, OCOC6H4R, and H, and wherein R may be an electron donating or electron releasing substituent.
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In accordance with another aspect of this invention ~ :
there is provided an electrostatographic imaging process com~
prising the steps of providing an electrostatographic imaging member having a recording surface, forming an electrostatic ::
latent image on said recording surface, and contacting said ; :
electrostatic latent image with a developer mixture comprising ~ :.
finely-divided toner particles having an average particle :
diameter of less than about 30 microns electrostatically cling~
ing to the surface of carrier particles having an average : ~ :
10 partlcle diameter of between about 50 microns and about 1,000 ~ -microns, at least the carrier particles or the toner particles being an aminolyzed polymer having the general structure ~H3 ~'' :" .:.

~ CONH(CH ) ~

where X may be NH2, OH, NHCOC6H4R, OCOC6H4R, and H, and wherein R may be an electron donating or electron releasing substituent, whereby at least a portion of said finely-divided toner particles . -are attracted to and deposited on said recording surface in con- ~:
formance with said electrostatic latent image.
In accordance with another aspect of this invention ~ .
there is provided an electrostatographic developer composition ~
comprising finely-divided toner particles electrostatically . ~ ;
clinging to the surface of carrier particles, said toner particles. :
having an average particle diameter of less than about 30 microns, ;~.
said toner particles comprising a colorant and a polymer contain- ~
30 ing pendant ester functions, said polymer having been selected ~. :~.;

from the group consisting of styrene-alkylmethacrylate and sty- ~;
rene-alkylacrylate, and whereln said polymer has been exposed to systematic chemical alteration of said pendant ester ~ -8a- .

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functions by aminolysis with an aminoalcohol to result in the 1 ' formation of hydroxyalkylamide functions and provide toner ~ .:
particles characterized as having controlled triboelectric charging properties.
In accordance with another aspect of this invention .::
there is provided an electrostatographic developer composition for use in developing electrostatic latent images on a record- ~.
ing surface, said developer composition comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles, said toner particles having an average particl~ diameter of less than about 30 microns, and comprising a colorant and a polymer-selected from the group consisting of styrene-alkylmethacrylate and styrene-alkyl- ~ ~.
acrylate, and wherein said polymer has been exposed to systematic ,~ . . chemical alteration by ester group aminolysis to produce an aminolyzed polymer having the general structure .- ::
.... ..
CH3 ,~

~CIHC~ f CH2-: ~ CNH(CH2)6X ~, where X may be NH2 OH, and H, and provide toner particles ;~
characterized as having controlled triboelectric charging proper- ;
ties. i .In accordance with another aspect of this invention there is provided an electrostatographic imaging process compris~
ing the steps of providing an electrostatographic imaging .i.
member having a recording surface, forming an electrostatic 30 latent image on said recording surface, and contacting said .:
electrostatic latent image with a developer composition compris~
ing finely-divided toner particles electrostatically clinging :~
to the surface of carrier particles, said toner particles i `

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having an average particle diameter o~ less than about 30 - : ~
- : ..
microns, said toner particles comprising a colorant and a polymer : ~

containing pendant ester functions, said polymer having been ; -~ `
.... ......
selected from the group consising of styrene-alkylmethacrylate .~ .
.
and styrene-alkylacrylate, and wherein said polymer has been :

exposed to systematic chemical alteration of said pendant ester .
, functions by aminolysis with an aminoalcohol resulting in the formation of hydroxyalkylamide functions and to provide toner :-particles characterized as having controlled triboelectric charging properties, whereby at least a portion of said finely~
divided toner particles are attracted to and deposited on said ~ -recording surface in conformance with said electrostatic latent ~ ~
image. :~ :
In accordance with another aspect of this invention :~ :
there is provided an electrostatographic carrier composition . .
for use in developing electrostatic latent images on a record- ~:
ing-surface, said carrier composition comprising carrier particles having an average particle diameter of between about . ~:
50 microns and about l,000 microns, each of said carrier particles comprising a core surrounded by an outer coating of a polymer selected from the group consisting of styrene-alkyl-methacrylate and styrene-alkylacrylate, said polymer having ; been functionalized by ester group aminolysis to produce an ;;.
aminolyzed polymer having the general structure ~.

CH x -.~
...
-~ ~H2( CH2 .: . .
~ C~NH(CH2)6X ` t where X may be NH2, OH, and H said carrier particles being characterized as having controlled triboelectric charging properties. :

~ ' t '1 ~ -8c-` ~1162945 By way of added explanation, in accordance with an aspect of this invention the chemical alteration of the tribo-electric charging potential of functional polymers employed as -~
developer materials is controlled. The controlled variation of the triboelectric behavior of functional polymers provides . .
a means of attaining optimum triboelectric responses of elec- .
trostatographic developer materials for specifically defined applications. Thus, in accordance with this invention, mono- .
meric and/or polymeric materials are systematically chemically ~ -10 modified to provide structural effects which yield structure- -triboelectric property relationships among amines, amides, .
alcohals, esters, urethanes, silyl ethers, nitroaromatics, haloaromatics, aromatic ' i`'' '~
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ethers, and alkylaromatics. These relationships have been found to be extremely helpful in designing new developer , .................................................................... .
materials, i.e. bo-th carriers and developers. By this invention, the triboelectric charging properties of toner-. earrier pairs are controlled to enable optimum triboelectric relationships in developer compositions.
It is to be noted that, by itself, no material hasa triboelectrie charge. The magnitude of a triboelectric charge ; depends upon both the toner and the carrier material. Thus, `:~ ,. . .
replaeement of one of the components to optimize triboelectric charging properties is generally necessary to provide the desired -triboelectric response. By so doing, greater latitude is available for specific electrostatographic applications. In aecordance with this invention, it has been found that by `
varying the degree of chemical modification of polymeric materials i for use as developer particles, either stoichiometrically or , kinetically, the triboelectric properties of developer materials j ean be controlled in a continuous manner. ~j;;
In electrostatographic development of selenium photo- -eonductor latent images, polymers which tend to take on a rela-tively high negative charge are generally satisfactory for use as toner materials and those that take on a high positive char~e ~i are satisfactory for carrier materials. In electrostatographic development of other photoconductor latent images, for example, ~5 zine oxide, phthalocyanine, cadmium sulfide, polyvinylcarbazole-trinitroflurenone, the opposite is true. In accordance ` with this invention, the triboelectric properties of developer ~ materials are correlated with their structural composition `` and thereby predictably controlled. Since the distance between`!
~`0 a given toner-carrier pair on a triboelectric charging scale _9_ :: . .:
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determines the tri~oelectric charge between them, their relative positions determine the sign of the triboelectric charge.
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Those materials low on the scale prefer to adopt a positive charge and those materials high on the scale prefer to adopt a negative charge. Appropriate toner-carrier pairs can be selected based -on their triboelectric charging or triboelectric series relationship to satisfy a particular acceptable triboelectric charging range requirement for a given electrostatographic machine developer -~
housing.
... .
~~ It has been found that triboelectric behavior is a ., j function of molecular structure which now allows the controlled and progressive modification of the triboelectric charging ~;, properties of developer compositions so as to obtain optimum tri-boelectric charging properties between toner and carrier pairs.
Thus, by this invention, adjustment of the triboelectric charging properties of electrostatographic developer materials need not 31 be done in stepwise fashion but may be accomplished in a con- `
;~ tinuous manner providing a high degree of "fine tuning" of ^i~ triboelectric properties for developer materials.
In accordance with this invention, the triboelectric charging properties of monomeric and polymeric compounds may be modified by systematic chemical modification by means of aminolysis of their pendant ester functions. Cascade develop- ' ment trlboelectric charging evaluations of such functianalized ~i polymers have demonstrated that these materials charge less negatively than the starting polymeric esters. In the resultant `
amides the propensity for negative charging increases in the ~,~
i following order of terminal group structure for NH2, OH, H.
`~ In addition to these transformations, functionalize~d ~`

) polymers may be further derivatized. For example, an aminoIyzed j 1 0-- '' ., "
,~'i, ' ' i,. ~ , , 106Z~45 polymer having the general structure

2 1 2 CONH (CH2) 6X ' ' ,~ .
, .
Where X may be N~I2, OH, NHCOC6H4R, OCOC6H~R and H provides polymer compositions of varying triboelectric charging potential.
More specifically, conversion of the ~H2 group to be a benzamide (X=NHCOC6H4R) causes the polymer to accept more negative charge^
The nitro substituent (R) causes more negative charging than does -~
methoxy (R). Likewise, conversion of the OH group to OCOC6EI4R
also allows the polymer to accept more negative charge. `~ `
It is also noted that the triboelectric charging ~
.:- - .
capaaity is controlled by the substituent R of the benzamides (X=~HCOC6H4R) and benzoates (X=OCOC6H4R). The propensity for negative charging increases with increasing electron .
withdrawing power of R as measured by substituent constants in each case.
An alternative to reactions of polymers in many ;
applications is the polymerization of monomers bearing the ..
desired substituent. The aforementioned techniques may be applied to many polymers such as those disclosed above and' their derivatives including styrene-alkylmethacrylates and i styrene-alkyl acrylates. ~ ~, The chemical modification of such materials enables the alteration of materials having optimum physical properties in such a way as to improve their triboelectric properties for electrostatographic use. This invention may serve as a guide ~for the preparation of toner and carrier compositions having "finely-tuned" triboelectric charging properties, and the capacity ~, . ..

- for continuous control of such properties through variation in `;

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-- - - 106Z94S ~::
extent of reaction may be employed for such purpose. ;~
;'i~ . .
For the preparation of toners, in accordance with this invention, any suitable vinyl resin having a melting point of at least about 110F may be employed. The vinyl resin may be a homopolymer or a copolymer of two or more vinyl monomers. Typical monomeric units which may be employed ;l to form constituents of vinyl polymers include: styrene, p-chlorostyrene; vinyl naphthalene; ethylenically unsaturated mono-i olefins such as ethylene, propylene, butylene, isobutylene and ~`0 the like; vinyl esters such as vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, ~
;, vinyl butyrate and the like; esters of alphamethylene aliphatic ;
monocarboxylic acids such as methyl acrylate, ethyl acrylate, " . . . .
n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chioroethyl acrylate, phenyl acrylate, methylalpha-.~ chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl ~3 methacrylate and the like; acrylonitrile, methacrylonitrile, -¦ acrylamide, vinyl ethers such as vinyl methyl ether, vinyl., ,~ .
`~ isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones `~o ~ such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone and the like; vinylidene halides such as vinylidene chloride, ~'` vinyliden~ chlorofluoride and the like; and N-vinyl compounds such as ~-vinylpyrrole, ~-vinylcarbozole, ~-vinylindole, ~-vinyl- ;
pyrrolidene and the like; and mixtures thereof. Generally, ~;5 suitable vinyl resins employed in the toner have a weight average molecular weight between about 3,000 to about 500,000~ The resins may be formed by the polymerization of mixtures of two or more of these unsaturated monomers. The expression "addition poly-merization" is intended to include known polymerization techniques ~0 such as free radical, anionic and cationic polymerizatlon processes. r~
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The combination of the resin component and colorant ., ~ ~ . .
whether the resin component is a homopolymer, copolymer, or blend, should have a blocking temperature of at least about 110F and a melt viscosity of less than about 2.5 x 10 4 poise at temperatures of to about 450F. When the toner is characterized by a blocking temperature less than about 110F, the toner particles tend to agglomerate during storage and machine operation and also form undesirable films on the surface of reusable photoreceptors which adversely affect image quality.
Any suitable pigment or dye may be employed as the colorant for the toner particles. Toner colorants are well-known and include, for example, carbon black, nigrosine dye, aniline blue, Calco Oil Blue, chrome yellow, ultra marine blue, duPont Oil Red, Quinoline Yellow, methylene blue chloride, phthalocyanine blue, Malachite Green Oxalate, lamp black, Rose Bengal and mixtures thereof. The pigment or dyes should be present in the toner in a sufficient quantity to render it highly colored so that it will form a clearly visible image --' ,~: . ' - ' on a recording member. Thus, for example, where conventional i electrostatographic copiès of typed documents are desired, the ~ -toner may comprise a black pigment such as carbon black or a black dye such as Amaplast Black dye, available from the ~ -National Aniline Products, Inc. Generally, the pigment is -employed in an amount from about 1 percent to about 20 percent by weight based on the total weight of the colored toner. If Ir~
the toner colorant employed is a dye, substantially smaller quantities of colorant may be used. However, since a number of the above pigments used in electrostatographic toner compo~
;! ,~ ' ~
sitions may affect both the glass transition and fusion temper-atures of the toner compositions of this invention, their ::~...

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`: ~06Z945 - concentration preferably should not exceed about 10 percent by weight of the colored toner.
The toner compositions of the present invention may be prepared by any well-known toner mixing and comminution S technique. For example, the ingredients may be thoroughly mixed by blending, mixing and milling the components and there-` after micropulverizing the resulting mixture. Another well-known technique for forming toner particles is to spray-dry a ball-milled toner composition comprising a colorant, a resin, 0 and a solvent.
. ~
li When the toner materials of this invention are to : be employed in a cascade development process, the toner should -~
have an average particle size less than about 30 microns and preferably between about 4 and about 20 microns for optimum results. For use in powder cloud development methods, particle diameters of slightly less than 1 micron are preferred.
1 In addition to the carrier materials in accordance ¦ with this invention, any suitable coated and uncoated carrier materials for well-known in the art may be used. The carrier ,o particles comprise any suitable solid materials, provided that the carrier particles acquire a charge having an opposite : ` .
;~ polarity to that of the toner particles when brought in close ` ~ contact with the toner particles so that the toner particles adhere to and surround the carrier particles. When a positive ;
~-,5 reproduction of the electrostatic images is desired, the carrier ~ `
particle is selected so that the toner particles acquire a ~
charge having a polarity opposite to that of the electrostatic .r image. Alternatively, if a reversal reproduction of the electrostatic image is desired, th~e carrier is selected so that ~-qO the toner particles acquire a Fharge having the same polarity .1 .,.,~
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as that of the electrostatic image. Thus the materials for the carrier particles are selected in accordance with their triboelectric properties in respect to the electroscopic toner -: .: - ;. :
; so that when mixed or brought into mutual contact, one .. ~ , . . .
component of the developer is charged positively if the other component is below the first component in the triboelectric series and negatively if the other component is above the first component in a triboelectric series. By proper selection of caxrier materials in accordance with their triboelectric ;o effects, the polarities of their charge, when mixed, are such that the electroscopic toner particles adhere to and are coated on the surfaces of carrier particles and also adhere to that ` portion of the electrostatic image-bearing surface ha~ing a `, greater attraction for the toner than the carrier particles.
~5 Typical known carriers include sodium chloride, aluminum potassiu~
. `! .
chloride, Rochelle salt, granular zircon, granular silicon, ~' methyl methacrylate, glass, silicon dioxide, nickel, steel, .
iron, ferrites, and the like. The carriers may be employed with or without a coating. Many of the foregoing and other o typical carriers are described by L. E. Walkup et al in ~ U.S. Patent 2,638,416 and E. ~. Wise in U.S. Patent 2,618,552.
,i An ultimate coated carrier particle diameter between about - ;
i 50 microns to about l,OOO microns is preferred because the ~i carrier particles then possess sufficient density and inertia ~5 to avoid adherence to the electrostatic images during the cascade development process. Adherence of carrier beads to electrostatographic drums is undesirable because of the forma-tion o deep scratches on the surface during the imaging transfer and drum cleaning steps, particularly where cleaning is accomplished by a web cleaner such as the web disclosed by ~il '~ .

~ - `
s ~0~2945 W. P. Graff, ~r., et al in U. S. Patent 3,186,838. ~lso print deletion occurs when carrier beads adhere to electro-statographic imaging surfaces. Generally spea~ing, satis-factory results are obtained when about 1 part toner is used with about 10 to 200 parts by weight of carrier. Continuous control of such properties through variation in e~tent of reaction may be employed for such purpose.
With regard to carrier materials in accordance with this invention, it is to be noted that materials such as those derived by aminolysis of styrene-methacrylate copolymers provide .. . .
excellent carrier or carrier coatings, especially in view of their crosslinkability. By the use of such materials, toners that previously provided unacceptable triboelectric response with conventional carriers now function properly. Thus, the coating of carrier cores, for example, metallic beads, with functionalized polymers containing a~crosslinking agent provides carrier materials which, in addition to improved toughness, the . A ., .
triboelectric properties thereof may be continuously varied by `~``` means of controlling the amount of the crosslinking agent in `) the coating composition. ~ -The coating of metallic carriers with hydroxy or amino f~mctionalized polymers and crosslinking these materials .~ :
via reaction of the pendant hydroxyl or amino moieties with .' a crosslinking agent such as diisocyanate provides a means of continuous control of the triboelectric properties of the coated carriers. It has been found that as the degree of con-' version increases, the capacity for positive triboelectric . ~. " . .
~;~ charging decreases. In addition, the degree of conversion can "~ be controlled stoichiometrically. Further, various types of .~ ., .~ . .
.`-3 crosslinking agents which are reactive toward hydroxyl or amino .~,.` ''.'.,",'.' :.
: .: .
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. !'. ' : ' ' ~ ` ` 106Z945 -~ functions may be employed. In addition, various hydroxyl or amino containing polymers exhibit similar effects~ It is to be noted that it is not necessary for the polymer material ., : ..
to be crosslinked to observe a change in the triboelectric charging properties since the change in triboelectric charging .. . ..
is not c1ue to molecular weight change. Monofunctional reagents .. .. .
; have been found to bring about similar changes.
Any suitable carrier or carrier coating material may be chemically modified in accordance with this invention to control the triboelectric properties of the carrier. Typical carrier materials include vinyl chloride-vinyl acetate copolymers, styrene-acrylate-organosilicon terpolymers, natural resins such as caoutchouc, colophony, copal, dammar, Dragon's Blood, jalap, 1 storax; thermoplastic resins including the polyolefins such as '~lS polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polyvinyls and polyvinylidenes such as polystyrene, polymethlstyrene, polymethacrylate, poly-~¦ acrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl O ethers, and polyvinyl ketones; fluorocarbons such as poly- -?,~l tetrafluorothylene, polyvinyl fluoride, polyvinylidene fluoride;
~,~` and polychlorotrifluoroethylene; polyamides such as polycaprolactam ~ ;
and polyhexamethylene adipamide; polyesters such as polyethylene ``~
terephthalate; polyurethanes; polysulfides, polycarbonates; thermo-setting resins including phenolic resins such as phenol-formaldehyde, ~ -phenol-furfuraI and resorcinol formaldehyde; amino resins such ~'Ji''. ~''' ~,~?~ as urea-formaldehyde and melamineformaldehyde~; polyester resins;
epoxy resins; and the like. Many of the foregoing and other typical ~. ~ , . . . .
carrier coating materials are descrihed in h. E. Walkup in ~30 U. S. Patent 2,618,551; B. 8. JacXnow et al in U. S. Patent ~'" ..... . '.' ' .. , ;

,."~,i ~ ' i~

3,526,533; and R. ~. IIagenbach et al in U. S. Patents 3,533,835 and 3,658,500~
, Any suitable electrostatographic carrier coating thickness may be employed. However, a carrier coating having a thic~ness at least sufficient to form a thin, continuous film on the carrier particle is preferred because the carrier : , coating will then possess sufficient thickness to resist abrasion and prevent pinholes which adversely affect the triboelectric properties of the coated carrier particles.
O Generally, for cascade and magnetic brush development, the carrier coating may comprise from about 0.1 percent to about 10.0 percent by weight based on the weight of the coated l carrier particles. Preferably, the carrier coating should 3 comprise from about 0.3 percent to about 1.0 percent by ~]5 weight based on the weight of the coated carrier particles ;~, because maximum durability, toner impaction resistance, and `
copy quality are achieved. To achieve further variation in the properties of the coated carrier particles, well-known additives such as plasticizers, reactive and non-reactive O polymers, dyes, pigments, wetting agents and mixtures thereof ~,~ may be mixed with the coating materials. An ultimate coated i~
't carrier particle having an average diameter between about 50 microns and about 1,000 microns is preferred in cascade s i! systems because the carrier particle then possesses sufficient -~5 density and inertia to avoid adherence to the electrostatic -1 image during the cascade deveIopment process. Adherence of ;
i; carxier particles to an electrostatographic drum is undeslrable , ~ because of the formation of deep scratches on the drum surface ~' during the image transfer and drum cleaning steps, particularly `
0 where cleaning is accomplished by a web cleaner such as the , i ,...

,,", 106;~945 web disclosed by W. P. Graff, Jr., et al in U. S. Patent 3,186,838.
The surprisingly better results obtained with the electrostatographic carriers of this invention may be due to '5 many factors. For example, the carriers of this invention possess smooth outer surfaces which are highly resistant to craeking, ehipping, and flaking. In cascade development systems, the smooth surface enhances the rolling action of the earrier partieles across the electrostatographic surfaees and reduced the tendency 0 of carrier particles to adhere to the electrostatographic imaging surfaces. When these coated carriers are employed in electro-statographic development systems, carrier life is unexpectedly ? extended partieularly with respect to toner impaction resistance.
Additionally, the carrier materials of this invention appear to eontribute to the stability of the triboeleetrie properties of 3 the earrier over a wide relative humidity range. Beeause of their triboelectric properties, these carrier materials may be ¦ employed in reversal development of positively charged images.
Further, the earriers of this invention provide more uniform ~
~0 triboelectric characteristics than current carriers when employed ~ :
in electrostatographic development systems. In addition, the .
carriers of this invention provide exceptionally good life performance, durability, copy quality, quality maintenanee, `
i less earrier bead sticking and agglomeration, and also provides ~S improved abrasion resistance thereby minimizing earrier chipping and flaking. Further, the earriers of this invention provide tri-~l boeleetrie values sueh that they ean be used with a wide variety of presently available toners in present electrostatographic processes, and retain a predictable triboelectric value. Thus o the improved carrier particles of this invention have desirable ~.
;.. .

.1 ~'.1 ~ 106Z945 .
properties which permit their wide use in presently avail-able electrostatographic systems.
` Any suitable well known coated or uncoated electro- , statographic carrier bead material may be employed as the core of the beads of this invention. Typical carrier core materials include sodium chloride, ammonium chloride, aluminum potassium chloride, Rochellesalt, sodium nitrate, potassium chlorate, granular zircon, granular silicon, methyl methacrylate, ~ --I glass, silicon dioxide, flintshot, iron, steel, ferrite, .;~ .
'o nickel, Carborundum, and mixtures thereof.
'''A,;j In addition to the toner materials in accordance with i`~ this invention, any suitable well-known toner material may be -;
employed with the carriers of this invention. Typical toner ~ materials include gum copaI, gum sandarac, rosin, cumaroneindene ;,~5 resin, asphaltum, gilsonite, phenolformaldehyde resins, rosin modified phenolformaldehyde resins, methacrylic resins, poly-, styrene resins, polypropylene resins, epoxy resins, polyethylene ~ resins, polyester resins, and mixtures thereof. The particular '¦ toner material to be employed obviously depends upon the separation ~o ~ of the toner particles from the coated carrier in the triboelectric ; -series and should be sufficient to cause the toner particles to electrostatically cling to the carrler surface. Among -the patents describing electroscopic toner compositions are U.S. Patent 2,659,670 to Copley; U. S. Patent 2,753,308 to ~5 Landrigan; U. S. Patent 3,079,342 to Insalaco; U.S. Patent Reissue 25,136 to Carlson and U. S. Patent 2,788,288 to - Rheinfrank et al. .-~, The developer compositions of the instant in~ention may `
be employed to develop electrostatic latent images on any `,o suitable electrostatic latent image-bearing surface including ;;`
~,y '~

20- ' , j.

~:.j i;
," `.: . - ' conventional photoconductive surfaces. Well-known photocon-'! ductive materials include vitreous selenium, organic or inor-~,J
ganic photoconductors embedded in a non-photoconductive matrix, organic or inorganic photocanductors embedded in a photocon-5 ductive matrix, or the like. Representative patents in which photoconductive materials are disclosed include U. S Patent 'J 2,903,542 to Ullrich, U. S. Paten-t 2,970,906 to Bixby, U. S.
;l Patent 3~121~006 to Middleton, U. S. Patent 3~121~007 to Middleton, and U. S. Patent 3~151~982 to Corrsin.

;10 DESCRIPTION OF PREFERRED EMBODIMENTS
The following examples further define, describe, and compare methods of preparing the toner materials of the present invention and of utilizing them to develop electro-j.:: . . :,.:
, static latent images. Parts and percentages are by weight unless ~;
;15 otherwise indicated.
In the following, the relative triboelectric values ! generated by contact of carrier beads with toner particles is measured by means of a cascade device. The device comprises `'~ a grounded metal plate set at an arbitrary but constant angle ~20 of elevation to horizontal, for example, 30 degrees, and a cup at the bottom of the incline. The cup is not attached to the incline and is thus not grounded; it is attached to an electro- -meter. The material to be tested is coated onto a metallic ~, sheet, such as aluminum, and this is attached to the incline.
~5 Then beads of the desired carrier material are cascaded down , the film and into the electrometer cup, where the charge i`
acquired by the beads is measured. From this quantity and ~`
the weight of the beads the charge to mass ratio is calculated.
This quantity is a direct measure of the triboelectric charging O capacity of the polymeric film. The measurement is done at , ., :, . . . . ~

~O~Z94S
constant relative humidity and temperature. Since triboelectric measurements are relative, the measurements should, for compar- -ative purposes, be conducted under substantia~ly identical conditions.
~5 EXAMPLE I
Correlation of molecular structure and triboelectric behavior in polymeric systems is of practical importance when ', considering electrostatographic carrier coating candidates and `
such is demonstrated herein. Thus a polymeric system based on 0 a polystyrene series, chosen for accessibility and simplicity, ~;
having the generic structure~
.. ~ . .. .. :
~ -CH2CIH~

.'i X . :.
wherein X may be H, t-Bu, Cl, Br, CH2Cl, ~2 ~ and CH3 was studied. Poly(p-nitrostyrene), where X = N02, was synthesized ~ -~. ~ . . . .
1, from polystyrene by nitration; poly(p-bromostyrene), where ~ -. ~ . . .
X = Br, was prepared by using bromine/thallium acetate; poly '~
(p-chloromethylstyrene), where X = CH2Cl, was prepared by ~0 ~ polymerization of the corresponding monomer; and poly(p-i~ ~ methylstyrene), where X = CH3, was formed by reduction of ~
the polystyrene, X = CH2Cl by reductive dehalogenation with `-i~ lithium aluminum hydride. Films of the polymers were cast -~
onto aluminum sheets from tetrahydrofuran solution except that poly(p-nitrostyrene) was cast from dimethylformamide.
The films were dried for about fi~teen hours in vacuo at about 60 and then transferred without exposure to moist air to a dry box maintained at zero relative humidity. Zinc carrier beads were similarly dried for about 15 houxs ln i;

~0 vacuo at about 120C and transferred. Cascade triboelectric ;~ -22-x' ;''~' ~

` 106Z94~
~ measurements were conducted using an angle of about 30C, a ; drop height of about 1 cm, and a film length of about nine inches. The humidity was raised to successive constant levels by use of saturated salt solutions. The films and carrîer beads were equiiibrated at each relative humidity , condition for about twenty hours prior to triboelectric charging measurement. The results indicate that with increased electron drawing power of the substituent, there is an ~ -.`.j '' :
~, accompanying increase in the amount of negative charge gen-0 erated on the film. Though both carrier beads and films may be affected by moisture, the slope of a line at a given rela-2 tive humidity is a function only of the materials and their response to water vapor since the same carrier is used for each film. These results indicate a practical means of predicting the relative triboelectric behavior of polymers which are ':i! substituted in the aromatic moiety, such as predictably increas-;' ing the negative chargin~ property of the polymer. While the , triboelectric chargin~ property of mixtures and copolymers is not generally linear with composition, it is a linear function 0 of the exten~ of reaction for chemical modifications as shown ~-~ in the following.
EXAMPLE II
Functionalized polymers were prepared for carrier coating materials by ester group ami~olysis of a styrene-n-~5 butyl methacrylate copolymer (2.54:1.00 mole ratio) with an aminoaIcohol resulting in formation of hydroxyalkylamide func- s`
tions.
:,,' ,:s~
A mixture of about 117.5 ~rams (0.289 mole of ester ~ -;~ functions based on elemental analysis) of the styrene-n-butyl , ~;
3 ~ methacrylate, about 41.0 grams (0.350 mole) of 6-aminohexanol, -23~
,. .
, ,, ... . .

: - : ..... -. : : , . . .

and about 39.3 grams (0.350 mole) of 1,4-diazabicyclo 12,2,2~
octane was stirred under dry nitrogen at about lg0C ~oil ~ath temperature 205C) using an ambient air-cooled condenser to - allow escape of the n-butanol produced. Samples were removed-periodically, quenched in 10% HCl by volume and purified as follows. Each sample was dissolved in tetrahydrofuran ana then 10% HCl was added. The liquid phase was decanted from - the gummy polymer. This procedure was repeated twice, followed by a fourth and fifth wash using 5% methanolic HCl. The polymer was taken up in tetrahydrofuran and precipitated by dropwise addition with rapid stirring to 10% HCl. After homogenization in a blender and filtration, the process was repeated. The polymer in tetrahydrofuran solution was then precipitated in like manner from deionized water, and this process repeated.
After a final precipitation from methanol, the sample was dried in vacuo. Generally, the polymer sample was dissolved in about five times its weight of tetrahydrofuran. ~olumes of the pre-: cipitating solutions were 6-10 times those of the polymer-tetrahydrofuran solution.
!0 Following the above procedure to obtain functional-ized polymers by aminolysis, the ester functions of styrene-n-butyl methacrylate copolymer (2.54:1.00 mole ratio) were aminolyzed with 6-aminohexanol from 0 to 25 mole percent of available ester functions and films were cast from solution !5 onto aluminum plates and thoroughly dried. Figure 1 illustrates the dependence of triboelectric charging on the degree of conversion of the functionalized copolymer when using 250 micron nickel beads as a carrier. Other carriers gave similar results.
~0 , .
-2~- , ~L~629~5 ~; EXAMP~E III ~ -~
; Functionaliæed polymers were prepared for toner ~! materials by ester group aminolysis of a styrene-n-butyl methacrylate copolymer (2.54:1.00 mole ratio) with a diamine resulting in formation of aminoalkylamide functions.
... ..
l A mixture of about 200 grams of the styrene-n-butyl . j , . ~ .
methacrylate copolymer and about 50.0 grams of hexane-1.6-~i diamine was stirred under dry nitrogen at about ]80C (oil : . . . .
bath temperature 250C) for a period of about 20 hours using an ambient air-cooled condenser to allow escape of the n-~'' butanol produced. Samples were removed periodically, quenched .
in 10% HCl by volume and purified as follows. Each sample wasdissolved in tetrahydrofuran and then 10% HCl was added.
The liquid phase was decanted from the gummy polymer. This ~y , . .. .
procedure was repeated twice, followed by a fourth and fifth wash using 5% methanolic HCl. The polymer was taken up in tetrahydrofuran and precipitated by dropwise addition with ~ -rapid stirring to 10% HCl. After homogenization in a blender ;~
and filtration, the process was repeated. The polymer in tetrahydrofuran solution was then precipitated in like manner from deionized water, and this process repeated. After a final precipitation from methanol, the sample was dried in vacuo. Generally, the polymer sample was dissolved in about five times its weight of tetrahydrofuran. Volumes of the precipitating solutions~were 6-10 times those of the polymer-tatrahydrofuran solution.
Following the above procedure to obtain function-alized polymers by aminolysis, the ester functions of styrene-n-butyl methacrylate copolymer (2.5~:1.00 mole ~atio) were aminolyzed with hexane-l, 6--diamine from 0 ~o 2.3 mole percent - :, ., ,~ -25- ~
:~ .

: . :
. ~ .
.,~. . ~
.. ,, '`.
.~ i A ~' ~:., :' ' `
;; of availahle ester functions and films were cast from solution onto aluminum plates and thoroughly dried. Triboelectric measurements following the procedure of Example I illustrated --~ the dependence of triboelectric charging on the degree of ... . . .. ..
~(5 conversion of the functionalized copolymer when using 250 ! micron nickel beads as a carrier. Other carriers gave com-parable results.
, EXAMPLE IV
, ;~ ~ ' . ' Functionalized polymers were prepared for toner ~LO materials by ester group aminolysis of a styrene-n-butyl ?f methacrylate copolymer (2.54:1.00 mole ratio) with an alkyl amine resulting in formation of alkylamide functions.
: A mixture of about 117.5 grams (0.289 mole of ester functions based on elemental analysis) of the styrene-n-butyl ~,L5 methacrylate, about 35.4 grams (0.350 mole~ of aminohexane, and about 39.3 grams (0.350 mole of 1,4-diazabicyclo [2,2,2]-octane was stirred under dry nitrogen at about 180C (oil bath temperature 205C) using an ambient air-cooled condenser -to allow escape of the n-butanol produced. Samples were removed periodically, quenched in 10% HCl by volume and purified as follows. Each sample was dissolved in tetra- ?, .
hydrofu~an and then 10% HC1 was added. The liquid phase was decanted from the gummy polymer. This procedure was repeated twice, followed by a fourth and fifth wash using 5% methanolic HC1. The polymer was taken up in tetrahydrofuran and precip- -itated by dropwise addition with rapid stirring to 10% ~ICl.
After homogenization in a blender and filtration, the process '~ was repeated. The polvmer in tetrahydrofuran solution was ~i then precipitated in like manner from deionized water, and this ~o process repeated. After a final precipitation from methanol, ~;

-26- ' .. ~.,, . :
,:. : .
f.,~
',' ', ' ,:

1~6Z94S ~
- the sample was dried in vacu~. Generally, the polymer sample was dissolved in about five times its weight of tetrahydrofuran.
Volumes of the precipitating solutions were 6-10 times those of the polymer-tetrahydrofuran solution.
~ .: . , .
3 Following the above procedure the ester functions ; of styrene n-butyl methacrylate copolymer (2.54:1.00 mole ratio) ` were aminolyzed with aminohexane to the extent of 10 mole percent of available ester functions. ~
: . ' .: .' .
EXAMPLE V ~-p The effect of triboelectric charging properties as .... . .
~` a function of mixture composition was studied employing solutions of a styrene-n-butyl methacrylate copolymer (2.54:1.00 mole ~` ratio) and the copolymer from Example II which had been func-', tionalized via aminolysis with 6-aminohexanol to the extent of . S, .
;5 25 mole percent of available ester functions. From 0 to 100 weight percent of the styrene-n-butyl methacrylate copolymer was mixed with the functionalized polymer. Films were cast from solution onto aluminum plates and thoroughly dried. The cascade triboelectric charging properties obtained using these ;
films are illustrated in Figure 2 when using 250 micron nickel ~,~ beads as a carrier, and in Figure 3 when using 250 micron steel carrier beads. It is seen that triboelectric charging prop-erties are related to composition in an S-shaped fashion and are not linear as might be expected ideally. By comparing quantitatively these results with those obtained in Example '~ II as illustrated in Figure 1, it was concluded that due to its higher surface energy, proportionally less of the func-tionalized material resides on the surface of the polymer film that in the bulk. Therefore, the prediction of tribo~
`~0 electric charging properties for mixtures is quantitatively ~- -27 :;~

.. . ...

~06294~ ~
precarious, while chemical alterations of a single phase - -offers linear control of triboelectric charging properties.

EXAMPLE VI

The aminolyzed copolymers of Examples II and III were - derivatized.~ The copolymers have the géneral structure ;J
fH3 ~EICEI2COEI2 loN~ (CH2 ) 6X
wherein 1, X=N~I2; 2, X=OH, 3, X=NHCOC6H4R; 4, X=OCOC6H4R; and ~0 5, X=M.
. .. . .
To a stirred solution of about 10.0 grams of the hydroxy polymer in about 30 ml. of dry pyridine was added a ~ -solution of about 5.0 grams of substituted benzo~l chloride I in dry pyridine. The solution was refluxed about 18 hours ~;;5 and then poured into about 400.0 ml of 10% by volume HCl.
'~ After homogenization in a blender with 10% by volume HCl, ;~
then saturated sodium bicarbonate solution, and then water, ~ -the polymer was dissolved in tetrahydrofuran and precipitated ~`
into 10% by volume HC1. In like manner, the polymer was ~0~ successively precipitated from saturated sodium bicarbonate twice, methanol and water thrice. In this way, the following ; p-substituted benzoate esters were prepared: ~2 ~60%), OCH
(85%), Cl (100%), H (90%). The degree of conversions was ., , i determined by elemental analysis. `
~5 While the degree of conversions with various reagents ' ~;
were not exactly the same, trends can be discerned from Table I.
That is, conversion of 1 to a benzamide 3 causes the polymer to accept more negative charge. The nitro substituent causes ~i more negative charging than does methoxy, an electron releasing i~0 substituent. In a similar way, conversion of 2 to 4 also -, .. ;, . ~ .: :

106294~

- allows t'he polymer to accept more negative charge. To ascer~tain the effect of changing the ester linkage of a styrene-n- ' ', butyl methacrylate copolymer to an amide linkage, 5 was pre- . . .' pared by aminolysis of the copolymer with hexylamine. As ,'~, Sls can be seen from Table I, the amide polymer 5 charges more . , :
'; positively that the ester polymer even though the degree of , .
conversion to 5 is relatively low.
TABIE I
,,,i . . Effect of polymer structure on triboelectric charging at about 30% relative humidity '~ :

`~ Polymer 250 micron nickel carrier charge tnano-coulombs/gram) i . ~
Copolymer of styrene-n- ~1.1 ` ' :
butyl methacrylate 2a -2.5

4, R - NO2 -1.4 . : :
4, R = ClC ~ -1.9 ~ 4, R = Hd : -1.5 ~-'p~: 4,'R=OCH3 -1.9 , 3, R~N02 ~ +1.2 ''`' ,,1, '.~ 3, R~OC~
... .. .
a) 28 mole % of ester groups of copolymer of styrene-n-butyl ',,.
,., methacrylate aminolyzed .. ~.5 b) 60 mole % of available OH groups esterified ~'~ c) 100~mole % of available OH groups esterified . ;
ii d) 90 mole % of available OH groups esterified t;i~ e) 85 mole % of available OH groups ester,ified.
.'. ' From these results, it can be concluded that the ,, ~ effect of polymer structure on its triboelectric charging i'~ capacity is as follows: Electron withdrawing substituents ' ',~, ~ -29- , .. .

^ ` ~062945 : ~
attached to aromatic moieties increase the negative charging ability of the material relative to electron releasing i substituents. In aliphatic systems, the extent of negative , charging of the material inreases in the order NH~L OH H.
~5 Benzamldes and al~anamides charge more negatively than the ~, corresponding free amines. Benzoates, and alkanoates charge rl more negatively than the corresponding free alcohols. In aliphatic systems, the extent of negative charging is greater ~ for esters than for amides.
XO EXAMPLE VII
~, A sample of about 100 grams of 250 micron steel ,. . .
beads was continuously extracted with tetrahydrofuran for about 24 hours to remove soluble organics from their surface.
The beads were then vigorously stirred mechanically in tetra-~5 hydrofuran for about 20 hours. The solvent and suspended rust particles were decanted. This was repeated until no further rust~was evident in the decantate. The beads were ' dried in vacuo.
A solution of about 0.14 grams of polymer in about ~,o 125 ml. tetrahydrofuran was added to about 50.0 grams of the ~;~ cleaned beads. The polymer was prepared by ester group amin- -"i olysis of a s~tyrene-n-butyl methacrylate copolymer (2.54:1.00 mole ratio) as in Example~II with 6-aminohexanol to the extent , - of 25 mole percent of available ester functions. The solvent ,~5 was removed on a rotary evaporator at room temperature under `
,jl vacuum. The coated carrier beads which did not pass through 1 ~ a 177 micron sieve were then used in a cascade triboelectric ! ~,~ ' ,,, ' ... . ...
charging test. The triboelectric value obtained by cascading the coated carrier beads against a film of the untreated ~,0 styrene-n-butyl methacrylate copolymer was found to be about i~'l o ., , ~ r _ 3 0_ ~
i;, ~ , ' -` ~L062945 ., .
`` +1.2 nano-coulombs per gram after correction for background charge of the beads. Uncoated carrier beads developed a triboelectric charge of about -0.30 nano-coulombs per gram against the same film under the same test conditions. Thus, ~5 the triboelectric charge on the uncoated carrier beads developed against the film changed sign from positive to negative.
EXAMPLE VIII
A hydroxy functionalized styrene-n-butyl methacrylate ,0 copolymer containing about 0.05 percent by weight of tolylene i '.~ A
~i -2,4-diisocyanate which had been blocked with acetone oxime , was coated onto steel carrier beads at a coating weight of .~ .
the beads. A portion of the beads were heated at 190C for 0.5 hour to release the diisocyanate and cause crosslinking. In triboelectric response measurements against a film of the .... ~ .
`` non-functionalized styrene-methacrylate copolymer, the beads coated with crosslinked polymer acquired a triboelectric charge of about +0.15 nanocoulombs per gram. By comparison, ~ beads coated with the uncrosslinked copolymer and measured ,io against the film of untreated styrene-methacrylate copolymer acquired a triboelectric charge of about +1.2 nanocoulombs . . . .
per gram. Versus a film of the hydroxy functionalized `~
styrene-methacrylate copolymer, the triboelectric charge acquired by the uncrosslinked coated beads and the crosslinked ~5 coated beads was about ~0.76 and -0.52 nanocouIombs per gram respectively. Thus a relatively large change in triboelectric charging properties was observed against both films; in both cases the beads with crosslinked coating accepted less positive charge.
,0 Although specific components, proportions and pro- ~ i '"'' ~ -31-.'. ' ':
: . :
.~,,,", ',:

` 106Z945 ~ :
cedures have been stated in the above description of the ~ -preferred embodiments of the novel coated carrier compositions, other suitable components, proportions and procedures as listed : . .
above may be used with similar results. Further, other materials and procedures may be employed to synergize, enhance or other-wise modify the novel system.
Other modifications and ramifications of the present invention will appear to those skilled in the art upon the reading of this disclosure of this invention.

' ,, '' - :
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,~ ,;~.

Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An electrostatographic developer composition having controlled triboelectric charging properties for use in developing electrostatic latent images on a recording surface, comprising finely-divided toner particles electro-statically clinging to the surface of carrier particles, at least the toner or carrier particles comprising an aminolyzed polymer having the general structure where X may be NH2, OH, NHCOC6H4R, OCOC6H4R, and H, and where-in R may be an electron donating or electron releasing subs-tituent.

2. A developer composition in accordance with Claim 1 wherein the particles of said polymer are finely-divided toner particles having an average diameter of less than 30 microns and said toner particles include a colorant.

3. An electrostatographic toner composition in accor-dance with Claim 1 wherein said aminolyzed polymer comprises a vinyl resin having a melting point of at least about 110°F.

4. An electrostatographic developer composition in accordance with Claim 1 wherein the particles of said polymer are toner particles having a blocking temperature of at least about 110°F and a melt viscosity of less than about 2. 5 x 10-4 poise at temperatures of up to about 450°F.

5. An electrostatographic developer composition in accordance with Claim 1 wherein said aminolyzed polymer com-prises styrene-alkylmethacrylate.

6. An electrostatographic developer composition in accordance with Claim 1 wherein said aminolyzed polymer contains hydroxyalkylamide functional groups.

7. An electrostatographic developer composition in accordance with Claim 1 wherein said aminolyzed polymer is the product of aminolysis of the pendant ester functions of said polymer with an aminoalcohol.

8. An electrostatographic developer composition in accordance with Claim 7 wherein said aminoalcohol is 6-amino-hexanol.

9. An electrostatographic developer composition in accordance with Claim 1 wherein said aminolyzed polymer is the product of aminolysis with a diamine and said product contains aminoalkylamide functions.

10. An electrostatographic developer composition in accordance with Claim 1 wherein the particles of said polymer are carrier particles having an average particle diameter of between about 50 microns and about 1,000 microns.

11. An electrostatographic developer composition in accordance with Claim 10 wherein the carrier particles comprise a core coated with from about 0.1 percent to about 10.0 percent by weight based on the weight of said carrier particles of said polymer.

12. An electrostatographic developer composition comprising finely-divided toner particles having an average particle diameter of less than 30 microns electrostatically clinging to the surface of carrier particles having an average particle diameter of between about 50 microns and about 1,000 microns, at least the toner particles or the carrier particles comprising an aminolyzed polymer having the general structure where X may be NH2, OH, NH COC6H4R, OCOC6H4R, and H, and wherein R may be an electron donating or electron releasing substituent.

13. An electrostatographic imaging process comprising the steps of providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on said recording surface, and contacting said electrostatic latent image with a developer mixture comprising finely-divided toner particles having an average particle diameter of less than about 30 microns electrostatically clinging to the surface of carrier particles having an average particle diameter of between about 50 microns and about 1,000 microns, at least the carrier particles or the toner particles being an aminolyzed polymer having the general structure where X may be NH2, OH, NHCOC6H4R, OCOC6H4R, and H, and wherein R may be an electron donating or electron releasing substituent, whereby at least a portion of said finely-divided toner particles are attracted to and deposited on said recording surface in conformance with said electrostatic latent image.

14. An electrostatographic developer composition comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles, said toner particles having an average particle diameter of less than about 30 microns, said toner particles comprising a colorant and a polymer containing pendant ester functions, said polymer having been selected from the group consisting of styrene-alkylmethacrylate and sty-rene-alkalacrylate, and wherein said polymer has been exposed to systematic chemical alteration of said pendant ester functions by aminolysis with an aminoalcohol to result in the formation of hydroxyalkylamide functions and provide toner particles characterized as having controlled triboelectric charging properties,

15. An electrostatographic developer composition for use in developing electrostatic latent images on a recording surface, said developer composition comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles, said toner particles having an average particle diameter of less than about 30 microns, and comprising a colorant and a polymer selected from the group consisting of styrene-alkylmethacrylate and styrene-alkylacrylate, and wherein said polymer has been exposed to systematic chemical alteration by ester group aminolysis to produce an aminolyzed polymer having the general structure where X may be NH2, OH, and H, and provide toner particles characterized as having controlled triboelectric charging properties.

16. An electrostatographic imaging process comprising the steps of providing an electrostatographic imaging member having a recording surface, forming an electrostatic latent image on said recording surface, and contacting said electrostatic latent image with a developer composition comprising finely-aivided toner particles electrostatically clinging to the surface of carrier particles, said toner particles having an average particle diameter of less than about 30 microns, said toner particles comprising a colorant and a polymer containing pendant ester functions, said polymer having been selected from the group consisting of styrene-alkylmethacrylate and styrene-alkylacrylate, and wherein said polymer has been exposed to systematic chemical alteration of said pendant ester functions by aminolysis with an aminoalcohol resulting in the formation of hydroxyalkylamide functions and to provide toner particles characterized as having controlled triboelectric charging properties, whereby at least a portion of said finely-divided toner particles are attracted to and deposited on said record-ing surface in conformance with said electrostatic latent image.

17. An electrostatographic carrier composition for use in developing electrostatic latent images on a recording surface, said carrier composition comprising carrier particles having an average particle diameter of between about 50 microns and about 1,000 microns, each of said carrier particles comprising a core surrounded by an outer coating of a polymer selected from the group consisting of styrene-alkylmethacrylate and styrene-alkylacrylate, said polymer having been functionalized by ester group aminolysis to produce an aminolyzed polymer having the general structure where X may be NH2, OH, and H said carrier particles being characterized as having controlled triboelectric charging prop-erties.